Enhanced bone regeneration via ZIF-8 decorated hierarchical polyvinylidene fluoride piezoelectric foam nanogenerator: Coupling of bioelectricity, angiogenesis, and osteogenesis (Nano Energy, 2022)
Piezoelectric biomaterials are advantageous in terms of easy generation of transduced bioelectrical signals to skeleton systems in response to body movements or external stimulations. In the bone formation process, the coupling of angiogenesis-osteogenesis is crucial but the effect of piezoelectric biomaterials on angiogenesis and mechanism of stress-transformed electrical signals affecting vascular cells remain elusive. In this work, hierar-chically architected polyvinylidene fluoride (PVDF) foam fabricated by solid-state shearing milling was further decorated with ZIF-8 nanocrystals. The unique hierarchical porous structure realizes stable voltage outputs up to 10 V without polarization. The electric potential of piezoelectric PVDF affected molecular trajectory of Zn2+ released from ZIF-8, leading to Zn2+ enrichment around the PVDF surface. Under piezoelectric condition, PVDF/ ZIF-8 foams promoted in-vitro angiogenic and osteogenic activity as well as antibacterial effect. Upon calva rium and femur defect repair, PVDF/ZIF-8 piezoelectric foams also guided vascularized bone regeneration through micro-current stimulation and Zn2+ enrichment. RNA-seq demonstrated PVDF/ZIF-8 piezoelectric foam mainly up-regulated ATP coupled cation transmembrane transportation in vascular endothelial cells, which enhanced cellular uptake of Zn2+, indicating the synergistic effect of piezoelectric PVDF and bioactive ZIF-8. This work offers a preliminary explanation for mechanism of angiogenesis-osteogenesis coupling of PVDF/ZIF-8 foam nanogenerator and provides a valuable complement to clinical treatment strategies for bone defect repair.

Piezoelectricity enhancement in graphene/polyvinylidene fluoride composites due to graphene-induced α → β crystal phase transition (Energy Conversion and Management, 2022)
Piezoelectric polymers represented by polyvinylidene fluoride (PVDF) possess many attractive attributes so they are widely used in electromechanical energy conversion devices. To further enhance the piezoelectric effect of PVDF, graphene and its derivatives have been added. A central issue is how the added graphene improves the piezoelectric properties of the graphene/PVDF composites. Starting from consideration of crystal phase transition from alpha to beta phase in PVDF due to addition of graphene, we first introduce Cauchy's cumulative probability function to characterize the evolution of beta phase as a function of graphene content. Then, by considering the relationship between beta phase and the dipole, and between the microscopic dipole moment and the macroscopic piezoelectric coefficient, a theory of piezoelectricity for the composite is obtained. The theory shows that the beta phase increases slowly at low graphene content but the increase is very rapid as the graphene concentr ation approaches the percolation threshold, after which there is no significant growth. The piezoelectric coefficient also increases similarly until the percolation threshold, after which it starts to drop. When the graphene content is 0.11 vol%, the piezoelectric coefficient d33 increases from 22pC/N of pure PVDF to 39.73pC/N of graphene/ PVDF composite, which is an 80.5% increase in d33. In addition, this theory is further extended and applied to the other nanoparticle-enhanced piezoelectric polymer composites. This crystal phase transition model serves to fill up the theoretical gap in piezoelectric enhancement in piezoelectric enhancement of PVDF by graphene.

A Lead-Free Piezoelectric Fiber Generator with a High Energy Conversion Constant Material (Energies, 2022)
This paper introduces a fiber generator using PVDF with a high-performance lead-free piezoelectric ceramic as filler. The piezoelectric ceramic filler was Ba0.84Ca0.16Ti0.90Zr0.10O3 + CuO 0.25 wt% (BCTZC0.25) sintered at 1550 °C. The BCTZC0.25 has an improved high-energy conversion constant (d33 × g33). The fiber generator made of PVDF/BCTZC0.25 composite fiber showed 1.6 times better piezoelectric power generation performance compared to a pure PVDF fiber generator. The PVDF/BCTZC0.25 fiber generator produced an output voltage of 1.9 V at 4 Hz. Hence, we successfully demonstrated that a composite fiber generator that uses piezoelectric ceramics which are harmless to the human body can outperform a pure PVDF fiber generator.

Polar Phase Formation and Piezoelectricity of PVDF by Hot-pressing under Electrostatic Intermolecular Interactions - Zhao, Jing-Hua; He, Bao-Sheng; Li, Ao-Shen; Wang, Chao-Nan; Li, Qing-Qing; Hu, Zhi-Jun (CHINESE JOURNAL OF POLYMER SCIENCE, 2022)
Piezoelectric poly(vinylidene fluoride) (PVDF) has received considerable attention due to its ability of interconverting mechanical into electric energies and potential applications in wearable electronics. To achieve piezoelectricity, it is important to simultaneously control the formation of polar phases, crystallinity, and dipole alignments in PVDF-based films. Here we demonstrate that piezoelectricity can be obtained by directly hot-pressing PVDF films sandwiched between chitosan or cellulose films. The electrostatic interactions between PVDF and chitosan or cellulose enabled an exceptional high content of polar phases (beta- and gamma-phases) up to 90% and a measured piezoelectric charge coefficient d(33) of up to -30 pC/N. This study provides a simple and low-cost approach for obtaining piezoelectric PVDF films used for sensors, actuators, and energy harvesters.

Enhanced SERS and catalytic performance via piezoelectric and plasmonic coupling effects for organic pollutant molecule degradation - Xu, Jihua; Lv, Enze; Zhao, Xiaofei; Yu, Jing; Xu, Shicai; Li, Jinmeng; Li, Zhen; Xue, Mei; Zhang, Chao; Pan, Jie (JOURNAL OF ALLOYS AND COMPOUNDS, 2022)
The accurate detection and efficient catalytic treatment of pollutants are essential for environmental protection. In this study, we propose a Au/Ag/CuO nanowire (NW)/polyvinylidene fluoride (PVDF) substrate capable of achieving the highly sensitive surface-enhanced Raman scattering (SERS) detection as well as effective piezoelectric photodegradation of organic pollutant molecules. The piezoelectric modulation of the SERS performance of the Au/Ag/CuO NW/PVDF substrate was demonstrated experimentally using rhodamine 6 G and Crystal Violet. The piezoelectric photocatalytic performance was investigated using malachite green and methylene blue. The enhanced SERS and catalytic performance can be attributed to the coupling of the piezoelectric and plasmonic effects of the CuO NW/PVDF and Au/Ag bimetals. The proposed Au/Ag/CuO NW/PVDF substrate provides a robust method that employs plasmonic and piezoelectric materials for high-performance SERS detection and piezoelectric photocatalysis. (c) 2022 Elsevier B.V. All rights reserved.

Microfluidic fabrication of β-phase enriched poly(vinylidene fluoride) microfibers toward flexible piezoelectric sensor - Meng, Xiangyi; Li, Qingqing; Hu, Zhijun; Guo, Mingyu (JOURNAL OF POLYMER SCIENCE, 2022)
beta-phase enriched piezoelectric poly(vinylidene fluoride) (PVDF) films/fibers are often prepared by high-energy costing methods, including mechanical stretching, high-electric field or electrospinning. In this study, PVDF piezoelectric microfibers, for the first time, were prepared by microfluidic spinning technology. The beta-phase enriched PVDF microfibers with various diameters could be easily obtained inside the microfluidic channel due to the mass transfer induced phase inversion of the inner PVDF solution. The influence of diameter of the fibers, PVDF concentration of the inner phase and water content of the outer phase on the beta-phase content and crystallinity degree of the obtained fibers was studied in detail. The obtained beta-phase enriched fiber was weaved into meshes. Flexible piezoelectric fabrics were then developed based on these meshes, and further used as in-situ and real time human motion monitoring. This simple and effective strategy provides a promising microfl uidic spinning technique toward the development of functional microfibers and wearable piezoelectric sensors, which may also give some implies for the industrial wet-spinning of piezoelectric PVDF fibers in the future.

Improvement of adhesion characteristics of copper electrodes on polyvinylidene fluoride films using bovine serum albumin - Ahn, Tae-Chang; Hong, Hyun-Soo; Kim, Seong-Su; Hwang, Hui-Yun (INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES, 2022)
Polyvinylidene fluoride (PVDF) is one of the widely used piezoelectric polymers and has been used in flexible sensors, energy harvesting, wearable devices, and so on. However, the low adhesion characteristics of PVDF limits its application because of the fluorine components. To improve the adhesion characteristics of PVDF, we proposed a novel method to fabricate the electrodes on PVDF films using bovine serum albumin (BSA). To optimize the fabrication process, we manufactured the copper electrodes on PVDF films according to the concentrations of the BSA and palladium (Pd) solutions. The piezoelectric characteristics of the fabricated PVDF films and the adhesion strength between the electrodes and PVDF films were measured using a d(33) m and scratch tester, respectively. The adhesion strength and piezoelectric characteristics of the PVDF films fabricated using the proposed method increased compared with those of conventional PVDF films. In addition, we found that the best combination of BSA and Pd concentration were 0.5 and 0.6 mg/mL, respectively.

Revisiting of 8-PVDF nanoparticles via phase separation with giant piezoelectric response for the realization of self-powered biomedical sensors - Mishra, Hari Krishna; Gupta, Varun; Roy, Krittish; Babu, Anand; Kumar, Ajay; Mandal, Dipankar (NANO ENERGY, 2022)
Piezo-, pyro-, ferro-electricity in carbon-fluoro polymers such as poly(vinylidene fluoride) (PVDF), its copolymers and their nanostructures are gaining remarkable technological interest in self-powered flexible electronics. However, to achieve nanostructures of PVDF with preferred electroactive phase and enhanced piezoelectric coefficient is still remains a challenge. In this regard, we have introduced a nanoprecipitation technique to machinate PVDF nanoparticles with predominant piezoelectric delta (delta) phase (which is least studied till date) using the bi-solvent phase separation technique. It is noteworthy that 8-phase of PVDF possess excellent piezoelectric properties which is comparable to beta-phase, nevertheless it has been rarely explored because of its ultra-high electric field (similar to MV/m) based processing conditions adopted so far. In this context, solvent based phase separation approach is most convenient and thus expected to be an industrially viable approach to s cale up piezoelectric delta-PVDF nanoparticles which has enormous technological and commercial merits. The piezoresponse force microscopy (PFM) study is performed to confirm the nanoscale piezoand ferro-electricity in delta-PVDF nanoparticles that manifests the giant piezoelectric coefficient (d(33)) of similar to 43 pm/V and optimum phase reversal (Delta phi approximate to 180 degrees) behavior under very low applied bias (i.e., at similar to +/- 5 V). As a proof of concept, a flexible piezoelectric nanogenerator (f-PNG) was fabricated comprising of delta-PVDF nanoparticles. It generates promising electrical output with power density of 2 mu W/cm(2). Moreover, its ability to track the physiological signal such as arterial pulse detection indicates the potential utility of delta-PVDF nanoparticles based self-power sensors and actuators.

Piezoelectric Nanogenerator Based on Electrospinning PVDF/Cellulose Acetate Composite Membranes for Energy Harvesting - Li, Yuanyuan; Hu, Qing; Zhang, Rui; Ma, Wenmei; Pan, Siwei; Zhao, Yaohong; Wang, Qing; Fang, Pengfei (MATERIALS, 2022)
The organic piezoelectric polymer polyvinylidene fluoride (PVDF) has attracted extensive research because of its excellent flexibility and mechanical energy-harvesting properties. Here, the electrospinning technique was taken to fabricate synthesized fiber membranes of a PVDF/cellulose acetate (CA) composite. The obtained PVDF/CA electrospun fiber membranes (EFMs) were employed to prepare a flexible nanogenerator. XRD and FTIR spectroscopy revealed the enhancement of piezoelectric behavior due to an increase in beta-phase in PVDF/CA EFMs compared with cast films. The PVDF/CA fibers (mass ratio of PVDF to CA = 9:1) showed an output voltage of 7.5 V and a short-circuit current of 2.1 mu A under mechanical stress of 2 N and frequency of 1 Hz, which were 2.5 and two times greater than those of the pure PVDF fibers, respectively. By charging a 4.7 mu F capacitor for 15 min with the voltage generated by the PVDF/CA EFMs, nine LED lamps could be lit. The work provides an effective approach to enhancing the piezoelectric effects of PVDF for low-power electronic loading of macromolecule polymers.

Contact-Piezoelectric Bi-Catalysis of an Electrospun ZnO@PVDF Composite Membrane for Dye Decomposition - Jiang, Buwen; Xue, Xiaoxuan; Mu, Zuxiang; Zhang, Haoyuan; Li, Feng; Liu, Kai; Wang, Wenqian; Zhang, Yongfei; Li, Wenhui; Yang, Chao; Zhang, Kewei (MOLECULES, 2022)
The treatment of organic pollutants in wastewater is becoming a great challenge for social development. Herein, a novel contact-piezoelectric bi-catalysis of a ZnO@ PVDF composite membrane was prepared by electrospinning technology. The obtained ZnO@PVDF composite membranes is superior to the pure PVDF membrane in decomposing methyl orange (MO) under ultrasonication at room temperature, which is mainly attributed to the synergy effect of the contact-electro-catalysis of dielectric PVDF, as well as the piezoelectric catalysis of tetrapodal ZnO and the beta-phase of PVDF. The heterostructure of the piezoelectric-ZnO@dielectric-PVDF composite is beneficial in reducing the electron/hole pair recombination. As compared to the pure PVDF membrane, the catalytic degradation efficiency of the ZnO@PVDF composite membrane was improved by 444.23% under ultrasonication. Moreover, the reusability and stability of the composite membrane are comparable to those of the traditional powdered catalyst. Th is work offers a promising strategy for improving the pollutant degradation by combining contact-electro-catalysis with piezoelectric catalysis.

Enhanced electroactive β-phase formation in electrospun poly (vinylidene fluoride-co-hexafluoropropylene) nanowires with gold nanoparticles - Zhou, Xi; Suo, Tao (ACTA MECHANICA SINICA, 2022)
As a representative piezoelectric polymer, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) has been widely used in sensors transducers and actuators. In this paper, gold nanoparticles (AuNPs) are prepared and doped into the PVDF-HFP solution to enhance the piezoelectric property of electrospun PVDF-HFP nanowires. The results indicate that proper amounts of AuNPs within the nanowires can improve the piezoelectric phase in PVDF-HFP. Then, a nanogenerator was prepared using the PVDF-HFP/Au nanowires to verify the increase in piezoelectric performance. Experimental results show that compared with PVDF-HFP nanogenerator without AuNPs doping, the output voltage is increased by about two times, while the output current is doubled for the PVDF-HFP/Au nanogenerator. Furthermore, systematic molecular dynamics (MD) simulations are conducted to elucidate the physical mechanism of AuNPs enhanced beta-phase formation in PVDF-HFP. Our results show that the adsorption and electrostatic in teraction between the AuNPs and the PVDF chains promote the electroactive beta-phase formation, and also significantly increase the tension and poling effect during electrospinning process, which is the origin of the enhanced electroactive phase formation in electrospun PVDF-HFP nanowires.

Effects of biomimetic cross-sectional morphology on the piezoelectric properties of BaTiO3 nanorods-contained PVDF fibers - Kim, Young Kwang; Hwang, Sung-Ho; Seo, Hye-Jin; Jeong, Soon Moon; Lim, Sang Kyoo (NANO ENERGY, 2022)
In this study, the effects of the morphology of components on the performance of a piezoelectric nanogenerator were investigated. Polyvinylidene fluoride (PVDF) fibers with biomimetic cross-sectional morphologies inspired by plants were fabricated by integrating melt spinning, winding, and corona poling. The cross-sectional morphology of the PVDF fiber significantly influenced the piezoelectric performance because of differences in the exterior surface area and contact volume, which are important in the production of beta-phase PVDF and crystallinity. The daffodil flower-shaped PVDF fiber exhibited the best piezoelectric performance among the PVDF fibers with various biomimetic cross-sectional morphologies (i.e., daffodil flower, radish flower, papyrus stem, and stalk grain stem) possessing different active areas for piezoelectricity generation. Its open-circuit voltage of 36.05 V and short-circuit current of 3.126 mu A are attributable to its highest exterior surface area and contact volume, which maximize the active area (deformation area) for piezoelectricity generation. The effect of the morphology (nanoparticles and nanorods) of BaTiO3, which is another component of the piezoelectric nanogenerator, was also investigated using BaTiO3-contained PVDF fibers involving the daffodil flowerlike cross-sectional morphology, namely, the PVDF-daffodil/BaTiO3 nanoparticle (NP) and PVDF-daffodil/BaTiO3 nanorod (NR). Compared with nanoparticles, the rod morphology more efficiently promoted asymmetry in the fiber during fabrication. The PVDF-daffodil/BaTiO3 NR produced an excellent open-circuit voltage of 62 V and a maximum power of 91 mu W from human motion. This study provides new insights for the practical mass production and utilization of high-performance piezoelectric nanogenerators.

Piezoelectric sensor based on electrospun poly(vinylidene fluoride)/sulfonated poly(1,4-phenylene sulfide) blend nonwoven fiber mat - Pervin, Shamim-Ara; Sathiyanathan, Ponnan; Prabu, Arun Anand; Kim, Kap Jin (JOURNAL OF APPLIED POLYMER SCIENCE, 2022)
Electrospun poly(vinylidene fluoride) (PVDF)/sulfonated poly(1,4-phenylene sulfide) (sPPS) blend nanofiber webs are prepared to investigate the changes in piezoelectric behavior of PVDF as a function of sPPS content using spectral and electrical measurements. Initial fourier transform infrared (MK) spectral analysis carried out using PVDF/sPPS as-cast films provides useful information about the preferential formation of the beta-crystalline phase in PVDF. Even with the addition of 10 wt% of sPPS, beta-crystalline absorbance increases significantly in as-cast PVDF film at the expense of a corresponding decrease in a-crystalline absorbance. Cyclic-voltammetric analysis confirms the redox behavior of sPPS and its influence on improving the performance of PVDF/sPPS blend-based piezoelectric sensor through hydrogen bonding and ion-dipole interactions. The piezoelectric output signal recorded using PVDF/sPPS blend (95:5) nanofiber web shows similar to 4.4 times increase in output signal ampl itude compared to that of neat PVDF based sensor, which is an evidence that the PVDF/sPPS nanofiber web material can be used as a commercially viable flexible pressure sensor.

High-Aligned PVDF Nanofibers with a High Electroactive Phase Prepared by Systematically Optimizing the Solution Property and Process Parameters of Electrospinning - He, Zhongchen; Rault, Francois; Vishwakarma, Astha; Mohsenzadeh, Elham; Salaun, Fabien (COATINGS, 2022)
Poly(vinylidene fluoride) (PVDF)-electrosprayed nanofibers have been the subject of much research due to their flexibility and piezoelectric properties compared to other piezoelectrics, for example, ceramics or other polymeric materials. The piezoelectric performance of PVDF is mainly related to the presence of beta-phase. This study aims to determine the influence of working and formulation parameters on the generation of beta-phase, morphology, and crystal structure of PVDF nanofibers. In addition, this research innovatively analyzes the effect of the dispersion state of PVDF molecular chains in the solvent on the electrospinning results. The morphology and crystal structure of PVDF nanofibers were determined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Beadless nanofibers are obtained when the PVDF concentration reaches the semi-diluted regime entangled in dimethylformamide (DMF) or DMF/acetone solution. The optimization of the process parameters (static collector, tip to collector distance-25 cm, flow rate-1 mL/h, applied voltage-20 kV) allows the increase in the beta-phase fraction from 68.3% +/- 1.2% to 94.5% +/- 0.6% for a PVDF concentration of 25 w/v% in a DMF/acetone mixture (2/3 v/v). With these same parameters applied to a rotating collector, it was observed that the piezoelectric performance is at maximum for a maximum beta-phase fraction of 90.6% +/- 1.1%, obtained for a rotational speed of 200 rpm. The effect of orientation of PVDF nanofibers on piezoelectric properties was quantitatively discussed for the first time; the piezoelectric properties are independent of the alignment of the nanofibers.

Characterization of Piezoelectric Properties of Ag-NPs Doped PVDF Nanocomposite Fibres Membrane Prepared by Near Field Electrospinning - Pan, Cheng-Tang; Dutt, Karishma; Yen, Chung-Kun; Kumar, Ajay; Kaushik, Aman Chandra; Wei, Dong-Qing; Kumar, Amit; Wen, Zhi-Hong; Hsu, Wen-Hsin; Shiue, You-Ling (COMBINATORIAL CHEMISTRY & HIGH THROUGHPUT SCREENING, 2022)
Background: In this study, Near-field electrospinning (NFES) technique is used with a cylindrical collector to fabricate a large area permanent piezoelectric micro and nanofibers by a prepared solution. NFES requires a small electric field to fabricate fibers. Objective: The objective of this paper to investigate silver nanoparticle (Ag-NP)/ Polyvinylidene fluoride (PVDF) composite as the best piezoelectric material with improved properties to produced tremendously flexible and sensitive piezoelectric material with pertinent conductance. Methods: In this paper, we used controllable electrospinning technique based on Near-field electrospinning (NFES). The process parameter for Ag-NP/PVDF composite electrospun fiber based on pure PVDF fiber. A PVDF solution concentration of 18 wt.% and 6 wt.% silver nitrate, which is relative to the weight of PVDF wt.% with 1058 mu S conductivity fibers, have been directly written on a rotating cylindrical collector for aligned fiber PVDF/Ag-NP fibers ar e patterned on fabricated copper (Cu) interdigitated electrodes were implemented on a thin flexible polyethylene terephthalate (PET) substrate and Polydimethylsiloxane (PDMS) used as a package to enhance the durability of the PVDF/ Ag-NP device. Results: A notable effect on the piezoelectric response has been observed after Ag-NP addition, confirmed by XRD characterization and tapping test of Ag-NP/PVDF composite fiber. The morphology of the PVDF/Ag-NP fibers and measure diameter by scanning electron microscopy (SEM) and Optical micrograph (OM), of fiber. Finally, a diameter of PVDF/Ag-NP fibers up to-7 mu m. The high diffraction peak at 2 theta = 20.5 was investigated by X-ray diffraction (XRD) in the piezoelectric crystal beta-phase structure. Further addition of silver nanoparticles (Ag-NPs) in the PVDF solution resulted in enhancing the electromechanical conversion of the fibers from-0.1 V to-1 V. Conclusion: In conclusion, we can say that confirmed and validated the addition of Ag -NP in PVDF could enhance the piezoelectric property by using NFES technique with improved crystalline phase content can be useful for a wide range of power and sensing applications like biomedical devices and energy harvesting, among others.

Study on flexible large-area Poly(vinylidene fluoride)-based piezoelectric films prepared by extrusion-casting process for sensors and microactuators - ["Zhang, Chao", "Sun, Huajun", "Zhu, Quanyao"] (MATERIALS CHEMISTRY AND PHYSICS, 2022)
Poly(vinylidene fluoride) (PVDF)-based film is a typical kind of piezoelectric films with wide applications, which is mainly prepared by the casting process. It is difficult to obtain large-area film and realize continuous fabrication. In this paper, Firstly, PVDF/PZT@105(lead zirconate titanate)/GO(graphene oxide) composite films with various GO contents were prepared via the casting process, and through comparison among the dielectric and mechanical properties, the optimum GO addition amount was determined. Subsequently, PVDF-based piezoelectric film(PVDF/PZT@105/GO)was prepared via the extrusion-casting process. Comparison between the composite films prepared by two different processes were taken. Note that the extrusion-casting process is favorable for obtaining superior properties such as higher density, dielectric constant, breakdown strength, and piezoelectric coefficient. Besides, during the exploration of the polarization technology it is found that the improvement of polariza tion field intensity tends to be is the most important factor affecting the piezoelectric properties of the film. The piezoelectric coefficient (d33) of PVDF/PZT@105/GO film prepared by the extrusioncasting process can reach 26 pC/N. Finally, the electrodeformation effect of the composite film was studied, obtaining the electromechanical strain up to 2%, which is much bigger than the piezoelectric ceramics ever been reported and can be used in the microfluidic field.

Piezoelectric-Fenton degradation and mechanism study of Fe2O3/PVDF-HFP porous film drove by flowing water - Chai, Mengnan; Tong, Wangshu; Wang, Zhihao; Chen, Zhensheng; An, Yuancheng; Zhang, Yihe (JOURNAL OF HAZARDOUS MATERIALS, 2022)
Piezocatalysis driven by a gentle force possesses broad application prospects for degrading organic pollutants, sterilisation, wound healing and tissue recovery. The flexible and industrially scalable poly(vinylidene fluoride) (PVDF) film is commonly used in piezocatalysis. However, under gentle force action, PVDF composite-based piezocatalysis is poor. Herein, a flexible porous film based on poly(vinylidene fluoride)-hexafluoro propylene (PVDF-HFP) is enhanced with Fenton fillers (alpha-Fe2O3 nanoparticles). alpha-Fe2O3 nanoparticles improve the piezoelectric catalysis performance of PVDF-HFP by the beta-phase enhancement and provide Fe3+ to react with H2O2 generated by the piezoelectric film itself, leading to an additional Fenton reaction. Meanwhile, the Fe3+/Fe2+ cycle in the Fenton process accelerates under the piezoelectric field, promoting the Fenton reaction for 6.9% degradation improvement. The study on Fe2O3/PVDF-HFP porous film with the piezo-Fenton reaction under flowing wa ter may help promote new piezocatalysis designs with high efficiency for self-powered environmental purification.

Tailoring the Output Performance of PVDF-Based Piezo-Tribo Hybridized Nanogenerators via B, N-Codoped Reduced Graphene Oxide - Rana, Shilpa; Singh, Vishal; Singh, Bharti (ACS APPLIED ELECTRONIC MATERIALS, 2022)
Recently, piezoelectric and triboelectric nanogenerators are explored extensively for harvesting energy from mechanical vibrations via piezoelectric and triboelectric effects. The output efficiency of these nanogenerators can be improved further by combining their piezoelectric and triboelectric effects to fabricate a hybrid nanogenerator. In the present work, first, piezoelectric energy harvesters are fabricated to investigate the effects of the introduction of reduced graphene oxide (rGO), singleheteroatom (N)-doped rGO, and boron/nitrogen-codoped rGO in enhancing the piezoelectric performance of a poly(vinylidene fluoride) (PVDF)-based nanogenerator. Then, the film showing the highest piezoelectric performance (i.e., PVDF/BN-rGO) is coupled with a PDMS film to fabricate a hybrid nanogenerator. In comparison to a pristine PVDF-based nanogenerator, the PVDF/BN-rGO-based piezoelectric nano generator device exhibits similar to 2 times enhancement in output voltage and similar to 6 times enhancement in piezoelectric current, whereas the hybrid nanogenerator with the corresponding composite film shows better electrical performance, producing an output voltage and current of 57.6 V and 28.8 mu A, respectively. The improved performance of the nanogenerator is ascribed to the synergistic effect of piezoelectric and triboelectric effects together with the addition of codoped rGO in the PVDF matrix, which increases the remnant polarization and dielectric property of the PVDF nanocomposite film. Finally, the output generated by the hybrid nanogenerator is used to power 15 light emitting diodes (LEDs) and a calculator. The present work has shown the importance of rGO and its derivatives for energy harvesting applications.

Enhanced Energy Harvesting Performances of Flexible Piezoelectric Nanocomposite Based on CNTs@PZT Nanofibers Network - ["Xiaofei Liu", "Jian Wang", "Zhonghui Shen", "four others (RG visible)"] (Journal of Alloys and Compounds, 2022)
Flexible organic/inorganic piezoelectric nanocomposites are highly demanded for flexible wearable electronic devices due to their excellent mechanical flexibility and high piezoelectric performance.

Ultrahigh augmentation of flexible composite-based piezoelectric energy harvesting efficiency via polymer-impregnated nanoparticles network within 3D cellulose scaffold - ["Hongjian Zhang", "Chang Kyu Jeong", "Zhonghui Shen"] (Composites Part B Engineering, 2022)
Flexible piezoelectric energy harvesters convert ambient mechanical energy into electrical energy for wearable or implantable devices and IoT applications.

An Ion Channel‐Induced Self‐Powered Flexible Pressure Sensor Based on Potentiometric Transduction Mechanism - Dandan Lei, Qixiang Zhang, Nishuang Liu, Tuoyi Su, Luoxin Wang, Ziqi Ren, Yihua Gao (Advanced Functional Materials, 2022)
Abstract Great efforts have been made to build multifunctional flexible pressure sensing devices to enable future wearable electronics. However, a green‐safe, cost‐effective, self‐powered integrated pressure sensing system remains challenging. Herein, an all‐solid‐state pressure sensing rGM (rGO/GO/PVA nanofibers/MXene) system is designed and developed based on a mechanical potentiometric transduction (MPT) mechanism, which converts mechanical stimulation into the change in the ion transport channel and encodes it into the measured potential difference between two electrodes with hydrated GO, thereby generating potential conduction behavior as well as a programmable stable voltage and current. The self‐powered rGM sensor can yield an output open‐circuit voltage of 0.58 V and a short‐circuit current density of 3.2 µA cm –2 when experiencing a steady mechanical pressure. Unlike typical pressure sensors, rGM sensors have an ultrawide det ection range (0.7 Pa–1300 kPa), high stability (maintain 95% performance after 5000 cycles), high adjustability, simple preparation method, implying that the rGM sensor can provide real‐time monitoring for human physiological signals without an external power supply, which has a wide‐range impact on medical care. This work presents a new design based on the MPT mechanism that will significantly simplify manufacturing while improving the performance of future electronic devices and smart systems.

Highly sensitive self-powered pressure and strain sensor based on crumpled MXene film for wireless human motion detection - Yule Cao, Yinben Guo, Zixi Chen, Weifeng Yang, Kerui Li, Xingyu He, Jianmin Li (Nano Energy, 2022)

Flexible tensile strain-pressure sensor with an off-axis deformation-insensitivity - Hongcheng Xu, Weihao Zheng, Yuejiao Wang, Dandan Xu, Ningjuan Zhao, Yuxin Qin, Yangbo Yuan, Zhengjie Fan, Xueli Nan, Qikai Duan, Weidong Wang, Yang Lu, Libo Gao (Nano Energy, 2022)

High sensitivity and broad linearity range pressure sensor based on hierarchical in-situ filling porous structure - Jin Xu, Huayang Li, Yiming Yin, Xin Li, Jinwei Cao, Hanfang Feng, Wandi Bao, Hao Tan, Fanyuan Xiao, Guang Zhu (npj Flexible Electronics, 2022)
Abstract Flexible piezoresistive pressure sensor with high sensitivity over a broad linearity range have been attracting tremendous attention for its applications in health monitoring, artificial intelligence, and human-machine interfaces. Herein, we report a hierarchical in-situ filling porous piezoresistive sensor (HPPS) by direct ink writing (DIW) printing and curing of carbon nanofibers (CNFs)/polydimethylsiloxane (PDMS) emulsion. Hierarchical geometry significantly increases the contact area, distributes stress to multilayered lattice and internal porous structure, resulting in a broad sensing range. Moreover, unlike conventional hollow porous structure, the CNFs networks in-situ filling porous structure generates more contact sites and conductive pathways during compression, thereby achieving high sensitivity and linearity over entire sensing range. Therefore, the optimized HPPS achieves high sensitivity (4.7 kPa −1 ) and lineari ty (coefficient of determination, R 2 = 0.998) over a broad range (0.03–1000 kPa), together with remarkable response time and repeatability. Furthermore, the applications in diverse pressure scenarios and healthcare monitoring are demonstrated.

Highly sensitive active-powering pressure sensor enabled by integration of double-rough surface hydrogel and flexible batteries - Yuan Huang, Binbin Liu, Wenyue Zhang, Gangrui Qu, Shunyu Jin, Xianbo Li, Zanxiang Nie, Hang Zhou (npj Flexible Electronics, 2022)
Abstract A conductive, elastic, and biocompatible hybrid network hydrogel was prepared by cross-linking of locust bean gum, polyvinyl alcohol, and carbon nanotubes, yielding a rough top surface and smooth bottom surface. The merging of the two pieces of hydrogel flat face to flat face forms a highly elastic hydrogel with double-rough surfaces. A piezoresistive sensor assembled with the double-rough surface hydrogel sandwiched between two carbon cloth electrodes exhibits a high sensitivity (20.5 kPa-1, 0-1kPa), a broad detection range (0.1–100 kPa) and a reliable response for 1000 cycles. The rough contact area between the hydrogels and the carbon cloth is found critical in achieving ultra-high sensitivities in the low-pressure range. Moreover, further monolithic integration of the sensor with a flexible solid-state zinc ion battery ensures the self-powering of the sensor for various human motions detection applications.

High-sensitivity self-powered temperature/pressure sensor based on flexible Bi-Te thermoelectric film and porous microconed elastomer - Yaling Wang, Wei Zhu, Yuan Deng, Pengcheng Zhu, Yuedong Yu, Shaoxiong Hu, Ruifeng Zhang (Journal of Materials Science & Technology, 2022)

Electrospun fiber-based high-performance flexible multi-level micro-structured pressure sensor: Design, development and modelling - Shuo Yang, Kai Ding, Wei Wang, Tianyi Wang, Huiling Gong, Dengkun Shu, Ze Zhou, Long Jiao, Bowen Cheng, Yonghao Ni (Chemical Engineering Journal, 2022)

Development of a flexible and highly sensitive pressure sensor based on an aramid nanofiber-reinforced bacterial cellulose nanocomposite membrane - Shiqiang Chen, Yidi Wang, Bin Fei, Haofan Long, Tao Wang, Tonghua Zhang, Lei Chen (Chemical Engineering Journal, 2022)

Flexible ionic-gel strain sensor with double network, high conductivity and high frost-resistance using electrohydrodynamic printing method - Jun Chen, Ting Wu, Libing Zhang, Chengli Tang, Haijun Song, Fengli Huang, Chuncheng Zuo (Additive Manufacturing, 2022)

The Soft-Strain Effect Enabled High-Performance Flexible Pressure Sensor and Its Application in Monitoring Pulse Waves - Yue Li, Yuan Wei, Yabao Yang, Lu Zheng, Lei Luo, Jiuwei Gao, Hanjun Jiang, Juncai Song, Manzhang Xu, Xuewen Wang, Wei Huang (Research, 2022)
Flexible and wearable pressure sensors attached to human skin are effective and convenient in accurate and real-time tracking of various physiological signals for disease diagnosis and health assessment. Conventional flexible pressure sensors are constructed using compressible dielectric or conductive layers, which are electrically sensitive to external mechanical stimulation. However, saturated deformation under large compression significantly restrains the detection range and sensitivity of such sensors. Here, we report a novel type of flexible pressure sensor to overcome the compression saturation of the sensing layer by soft-strain effect, enabling an ultra-high sensitivity of ~636 kPa −1 and a wide detection range from 0.1 kPa to 56 kPa. In addition, the cyclic loading-unloading test reveals the excellent stability of the sensor, which maintains its signal detection after 10,000 cycles of 10 kPa compression. The sensor is capable of monitoring arterial p ulse waves from both deep tissue and distal parts, such as digital arteries and dorsal pedal arteries, which can be used for blood pressure estimation by pulse transit time at the same artery branch.

Highly sensitive fabric strain sensor with double-layer conductive networks for joint rehabilitation therapy - Dongxing Lu, Yao Chu, Shiqin Liao, Wei Li, Yibing Cai, Qufu Wei, Qingqing Wang (Composites Science and Technology, 2022)

Skin-inspired flexible and high-performance MXene@polydimethylsiloxane piezoresistive pressure sensor for human motion detection - Baodeng Chen, Lin Zhang, Hongqiang Li, Xuejun Lai, Xingrong Zeng (Journal of Colloid and Interface Science, 2022)

Resilient bismuthene-graphene architecture for multifunctional energy storage and wearable ionic-type capacitive pressure sensor device - Ning Wei, Yan Li, Yuxi Tang, Yanhong Zhou, Renjie Ning, Menglin Tang, Shibin Lu, Wei Zeng, Yi Xiong (Journal of Colloid and Interface Science, 2022)

Ultra-antifreeze, ultra-stretchable, transparent, and conductive hydrogel for multi-functional flexible electronics as strain sensor and triboelectric nanogenerator - Xinhuan Dai, Yong Long, Bing Jiang, Wenbin Guo, Wei Sha, Jiangwen Wang, Zifeng Cong, Jiwei Chen, Bingjun Wang, Weiguo Hu (Nano Research, 2022)

PDMS-based conductive elastomeric composite with 3D reduced graphene oxide conductive network for flexible strain sensor - Xincheng Wang, Yaokai Tang, Shangru Cheng, Qiangmin Gao, Yingxin Yuan, Anqi Li, Shanshan Guan (Composites Part A: Applied Science and Manufacturing, 2022)

Semi-IPN ionogel based on poly (ionic liquids)/xanthan gum for highly sensitive pressure sensor - Yantong Wu, Yuanyuan Ren, Yuanyuan Liang, Yongjin Li (International Journal of Biological Macromolecules, 2022)

Highly Sensitive and Stretchable MXene/CNTs/TPU Composite Strain Sensor with Bilayer Conductive Structure for Human Motion Detection - Hui Dong, Jingchao Sun, Xingmin Liu, Xiaodan Jiang, Shaowei Lu (ACS Applied Materials & Interfaces, 2022)

Superior, Environmentally Tolerant, Flexible, and Adhesive Poly(ionic liquid) Gel as a Multifaceted Underwater Sensor - Liduo Rong, Xiaoyun Xie, Weizhong Yuan, Yang Fu (ACS Applied Materials & Interfaces, 2022)

Sensitivity-Photo-Patternable Ionic Pressure Sensor Array with a Wearable Measurement Unit - Qi Su, Chenyu Liu, Tao Xue, Qiang Zou (ACS Applied Materials & Interfaces, 2022)

Hierarchically buckled Ti3C2Tx MXene/carbon nanotubes strain sensor with improved linearity, sensitivity, and strain range for soft robotics and epidermal monitoring - Yanli Wang, Wenjing Qin, Xiaoyu Hu, Zhongsheng Liu, Zhixin Ren, Huanqi Cao, Baigang An, Xiang Zhou, Muhammad Shafiq, Shougen Yin, Zunfeng Liu (Sensors and Actuators B: Chemical, 2022)

Modified MXene-doped conductive organosilicon elastomer with high-stretchable, toughness, and self-healable for strain sensors - Zhe Wang, Kaiming Zhang, Yuetao Liu, Haoyu Zhao, Chuanhui Gao, Yumin Wu (Composite Structures, 2022)

Performance Improvement of Flexible Pressure Sensor Based on Ordered Hierarchical Structure Array - Shaohua Yang, Chengpeng Zhang, Jin Ji, Yongzhi Liu, Jilai Wang, Zhenyu Shi (Advanced Materials Technologies, 2022)
Abstract Flexible pressure sensors have been extensively explored for their widespread applications in wearable electronic devices such as medical diagnosis and motion monitoring. In this paper, a facile method is adopted to prepare the ordered hierarchical structure array and then it is applied to improve the performance of capacitive flexible pressure sensors. The results indicate that the pressure sensor based on hierarchical structure array is with high sensitivity (0.382 kPa ‐1 ), fast response and recovery time (26 and 25 ms), and its minimum detection pressure can reach 4 Pa. Besides, the sensor based on hierarchical structure array has also been successfully applied to the dynamic pulse monitoring of the neck, limb movement monitoring, and pressure monitoring in water cup grasping process, which shows high stability and reliability, demonstrating its broad application prospects. This research could provide useful guidance for t he preparation and applications of high‐performance flexible pressure sensors.

Chitosan-based double cross-linked ionic hydrogels as a strain and pressure sensor with broad strain-range and high sensitivity - Xuemei Li, Zhiwei Liu, Yongri Liang, Li-Min Wang, Ying Dan Liu (Journal of Materials Chemistry B, 2022)
An ionic conductive hydrogel P(AAm- co -AA)/CS-Fe 3+ with double cross-linked networks was prepared. The hydrogel as a flexible sensor exhibited excellent mechanical properties, self-recovery ability, sensitive sensing properties, and biosecurity.

A wide sensing range and high sensitivity flexible strain sensor based on carbon nanotubes and MXene - Bingbing Xu, Feng Ye, Ronghu Chen, Xiaogang Luo, Guangtao Chang, Ruoxin Li (Ceramics International, 2022)

Flexible piezoresistive pressure sensor based on wrinkled layers with fast response for wearable applications - Dawei Du, Xinyue Ma, Wenxing An, Shihui Yu (Measurement, 2022)

Distribution optimization of micro-cone structures in the dielectric layer of a capacitive flexible pressure sensor - Huangping Yan, Zijun Wang, Rui Zhou, Jingbo Yin, Yuanzhe Li, Yuchao Zhu (Measurement, 2022)

Significantly improved interface between PVDF-based polymer electrolyte and lithium metal via thermal-electrochemical treatment - Chuanjiao Xue, Shundong Guan, Bingkun Hu, Xinzhi Wang, Chengzhou Xin, Sijie Liu, Jinyao Yu, Kaihua Wen, Liangliang Li, Ce-Wen Nan (Energy Storage Materials, 2022)

Dielectric properties and energy storage performance of PVDF-based composites with MoS2@MXene nanofiller - Hou-Qing Wang, Jing-Wen Wang, Xin-Zhu Wang, Xin-Hua Gao, Guo-Chao Zhuang, Jian-Bao Yang, Hua Ren (Chemical Engineering Journal, 2022)

Lead-free, high-current output piezoelectric nanogenerators using three-dimensional interdigitated electrodes - Zheng Zhou, Qilong Zhang, Zhao Zhang, Haoze Kuang, Xiangxin Du, Hui Yang (Chemical Engineering Journal, 2022)

Flexible piezoelectric nanogenerator based on the Er3 + doped lead-free (Na0.5Bi0.5)TiO3-BaTiO3 piezoelectric nanofibers with strong upconversion luminescence - Zhuang Cao, Junjie Wang, Chenyang Zhang, Xiaojian Mao, Laihui Luo (Journal of Alloys and Compounds, 2022)

Improvement of piezoelectricity of (Na, K)Nb-based lead-free piezoceramics using [001]-texturing for piezoelectric energy harvesters and actuators - Su-Hwan Go, Hero Kim, Dae-Su Kim, Jae-Min Eum, Seok-June Chae, Eun-Ji Kim, Sahn Nahm (Journal of the European Ceramic Society, 2022)

A correlative study between the microstructure and electrical properties of lead-free piezoceramics (1-x)BHT-xYLG driven by the synergistic action of multiple factors - Enpei Cai, Qibin Liu (Journal of the European Ceramic Society, 2022)

Efficiency of energy harvesting and storage using a multilayer capacitor based on BaTi0.86Sn0.14O3 ferroelectric lead-free ceramics - V.D. Fokina, V.S. Bondarev, E.I. Pogoreltsev, I.N. Flerov (Ceramics International, 2022)

Hydraulic-driven piezo-activation of peroxymonosulfate for carbamazepine degradation with ultralow energy consumption - Ying Zheng, Jing Yang, Bingrou Gong, Xiaohui Zhang, Junfeng Li, Huaili Zheng, Guping Chen, Chun Zhao (Chemical Engineering Journal, 2022)

Photo-piezoelectric synergistic degradation of typical volatile organic compounds on BaTiO3 - Qin Liu, Weina Zhao, Zhimin Ao, Taicheng An (Chinese Chemical Letters, 2022)

Sonoelectrochemical degradation of ciprofloxacin in water on a Ti/BaTiO3 electrode - Babatope O. Ojo, Omotayo A. Arotiba, Nonhlangabezo Mabuba (Journal of Environmental Chemical Engineering, 2022)

Fully self-powered electrocaloric cooling/heating with triboelectric nanogenerator - Jiayu Li, Boxun Liu, Chuangjian Liang, Lingyu Wan, Wenjuan Wei, Hongqiang Gao, Mingyang Li, Yahui Li, Wangyang Ding, Hang Qu, Honggui Wen, Fang Yu, Huilu Yao, Guanlin Liu, Biaolin Peng, Xiang Lu (Nano Energy, 2022)

Electroactive polymeric nanofibrous composite to drive in situ construction of lithiophilic SEI for stable lithium metal anodes - Ai‐Long Chen, Nan Shang, Ouyang Yue, Lulu Mo, Chunyang Zhou, Weng Weei Tjiu, Feili Lai, Yue‐E Miao, Tianxi Liu (eScience, 2022)
Uncontrolled lithium dendrite growth hinders the practical application of lithium metal batteries (LMBs). Herein, we report a novel Li+ flux distributor achieved by placing an electroactive polyvinylidene fluoride/polymethyl methacrylate (PVDF/PMMA) composite nanofiber interlayer on a current collector, inducing uniform lithium deposition to mitigate the dendrite problem. Specifically, the released PMMA reacts with Li+ to form abundant C–O–Li bonds and generate in situ a stable lithiophilic PMMA-Li solid electrolyte interphase layer. Theoretical calculations reveal that polar C–F groups in the PVDF framework and lithiophilic PMMA-Li provide homo-dispersed Li+ migration pathways with low energy barriers. Consequently, uniform Li nucleation is achieved at the molecular level, resulting in ultrahigh cycling stability with dendrite-free Li deposition at 5 ​mA ​cm−2 and 5 mAh cm−2 for over 500 ​h. The PVDF/PMMA ​∼ ​Li || LiFePO4 (LFP) full cell presents an increased rate capacity of 110 mAh g−1 at 10 ​C. In addition, a soft-package battery demonstrates a high energy density of 289 ​Wh kg−1. This work provides a facile design for stable lithium metal anodes to promote the practical use of LMBs and other alkali metal batteries.

A Silicon Monoxide Lithium-Ion Battery Anode with Ultrahigh Areal Capacity - Jiang Zhong, Tao Wang, Lei Wang, Lele Peng, Shubin Fu, Meng Zhang, Jinhui Cao, Xiang Xu, Junfei Liang, Huilong Fei, Xidong Duan, Bingan Lu, Yiliu Wang, Jian Zhu, Xiangfeng Duan (Nano-Micro Letters, 2022)
Abstract Silicon monoxide (SiO) is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g −1 . The studies to date have been limited to electrodes with a relatively low mass loading (< 3.5 mg cm −2 ), which has seriously restricted the areal capacity and its potential in practical devices. Maximizing areal capacity with such high-capacity materials is critical for capitalizing their potential in practical technologies. Herein, we report a monolithic three-dimensional (3D) large-sheet holey graphene framework/SiO (LHGF/SiO) composite for high-mass-loading electrode. By specifically using large-sheet holey graphene building blocks, we construct LHGF with super-elasticity and exceptional mechanical robustness, which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass loading. Additionally, the 3D porous graphene network structure in LHGF ensures ex cellent electron and ion transport. By systematically tailoring microstructure design, we show the LHGF/SiO anode with a mass loading of 44 mg cm −2 delivers a high areal capacity of 35.4 mAh cm −2 at a current of 8.8 mA cm −2 and retains a capacity of 10.6 mAh cm −2 at 17.6 mA cm −2 , greatly exceeding those of the state-of-the-art commercial or research devices. Furthermore, we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm −2 delivers an unprecedented areal capacity up to 140.8 mAh cm −2 . The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.

Construction of Ultrathin Layered MXene-TiN Heterostructure Enabling Favorable Catalytic Ability for High-Areal-Capacity Lithium–Sulfur Batteries - Hao Wang, Zhe Cui, Shuang He, Jinqi Zhu, Wei Luo, Qian Liu, Rujia Zou (Nano-Micro Letters, 2022)
Abstract Catalysis has been regarded as an effective strategy to mitigate sluggish reaction kinetics and serious shuttle effect of Li–S batteries. Herein, a spherical structure consists of ultrathin layered Ti 3 C 2 T x -TiN heterostructures (MX-TiN) through in-situ nitridation method is reported. Through controllable nitridation, highly conductive TiN layer grew on the surface and close coupled with interior MXene to form unique 2D heterostructures. The ultrathin heterostructure with only several nanometers in thickness enables outstanding ability to shorten electrons diffusion distance during electrochemical reactions and enlarge active surface with abundant adsorptive and catalytic sites. Moreover, the (001) surface of TiN is dominated by metallic Ti–3 d states, which ensures fast transmitting electrons from high conductive MX-TiN matrix and thus guarantees efficient catalytic performance. Calculations and experiments demonstrate that polysulfides are strongly immobilized on MX-TiN, meanwhile the bidirectional reaction kinetics are catalytically enhanced by reducing the conversion barrier between liquid LiPSs and solid Li 2 S 2 /Li 2 S. As a result, the S/MX-TiN cathode achieves excellent long-term cyclability with extremely low-capacity fading rate of 0.022% over 1000 cycles and remarkable areal capacity of 8.27 mAh cm −2 at high sulfur loading and lean electrolytes. Graphical abstract

Electrostatic Interaction Tailored Anion-Rich Solvation Sheath Stabilizing High-Voltage Lithium Metal Batteries - Junru Wu, Ziyao Gao, Yao Wang, Xu Yang, Qi Liu, Dong Zhou, Xianshu Wang, Feiyu Kang, Baohua Li (Nano-Micro Letters, 2022)
Abstract Through tailoring interfacial chemistry, electrolyte engineering is a facile yet effective strategy for high-performance lithium (Li) metal batteries, where the solvation structure is critical for interfacial chemistry. Herein, the effect of electrostatic interaction on regulating an anion-rich solvation is firstly proposed. The moderate electrostatic interaction between anion and solvent promotes anion to enter the solvation sheath, inducing stable solid electrolyte interphase with fast Li + transport kinetics on the anode. This as-designed electrolyte exhibits excellent compatibility with Li metal anode (a Li deposition/stripping Coulombic efficiency of 99.3%) and high-voltage LiCoO 2 cathode. Consequently, the 50 μm-thin Li||high-loading LiCoO 2 cells achieve significantly improved cycling performance under stringent conditions of high voltage over 4.5 V, lean electrolyte, and wide temperature range (− 20 to 60 °C). This work inspires a groundbreaking strategy to manipulate the solvation structure through regulating the interactions of solvent and anion for high-performance Li metal batteries.

Improving Li-ion interfacial transport in hybrid solid electrolytes - Ming Liu, Shengnan Zhang, Ernst R. H. van Eck, Chao Wang, Swapna Ganapathy, Marnix Wagemaker (Nature Nanotechnology, 2022)

Prospects for managing end‐of‐life lithium‐ion batteries: Present and future - Xiao‐Tong Wang, Zhen‐Yi Gu, Edison Huixiang Ang, Xin‐Xin Zhao, Xing‐Long Wu, Yichun Liu (Interdisciplinary materials, 2022)
Abstract The accelerating electrification has sparked an explosion in lithium‐ion batteries (LIBs) consumption. As the lifespan declines, the substantial LIBs will flow into the recycling market and promise to spawn a giant recycling system. Nonetheless, since the lack of unified guiding standard and nontraceability, the recycling of end‐of‐life LIBs has fallen into the dilemma of low recycling rate, poor recycling efficiency, and insignificant benefits. Herein, tapping into summarizing and analyzing the current status and challenges of recycling LIBs, this outlook provides insights for the future course of full lifecycle management of LIBs, proposing gradient utilization and recycling‐target predesign strategy. Further, we acknowledge some recommendations for recycling waste LIBs and anticipate a collaborative effort to advance sustainable and reliable recycling routes.

Evaluating the effectiveness ofin situcharacterization techniques in overcoming mechanistic limitations in lithium–sulfur batteries - Sarish Rehman, Michael A. Pope, Shanwen Tao, Eric McCalla (Energy & Environmental Science, 2022)
Li–S batteries hold great promise for electric vehicles but complex reaction mechanisms during operation have, to date, prevented commercialization. In situ techniques provide insights that may overcome these limitations.

Co-intercalation-free ether electrolytes for graphitic anodes in lithium-ion batteries - Peiyuan Ma, Priyadarshini Mirmira, Peter J. Eng, Seoung‐Bum Son, Ira Bloom, Alexander S. Filatov, Chibueze V. Amanchukwu (Energy & Environmental Science, 2022)
Fluorination of ether solvents suppresses solvent co-intercalation into graphite. The fluoroether electrolytes enable a wider working temperature window of Li-ion batteries and support silicon–graphite composite anodes.

Gradient Design for High‐Energy and High‐Power Batteries - Jingyi Wu, Zhengyu Ju, Xiao Zhang, Amy C. Marschilok, Kenneth J. Takeuchi, Huanlei Wang, Esther S. Takeuchi, Guihua Yu (Advanced Materials, 2022)
Charge transport is a key process that dominates battery performance, and the microstructures of the cathode, anode, and electrolyte play a central role in guiding ion and/or electron transport inside the battery. Rational design of key battery components with varying microstructure along the charge-transport direction to realize optimal local charge-transport dynamics can compensate for reaction polarization, which accelerates electrochemical reaction kinetics. Here, the principles of charge-transport mechanisms and their decisive role in battery performance are presented, followed by a discussion of the correlation between charge-transport regulation and battery microstructure design. The design strategies of the gradient cathodes, lithium-metal anodes, and solid-state electrolytes are summarized. Future directions and perspectives of gradient design are provided at the end to enable practically accessible high-energy and high-power-density batteries.

Sulfur Reduction Reaction in Lithium–Sulfur Batteries: Mechanisms, Catalysts, and Characterization - Lei Zhou, Dmitri L. Danilov, Fen Qiao, Junfeng Wang, Haitao Li, Rüdiger‐A. Eichel, Peter H. L. Notten (Advanced Energy Materials, 2022)
Abstract Lithium–sulfur batteries are one of the most promising alternatives for advanced battery systems due to the merits of extraordinary theoretical specific energy density, abundant resources, environmental friendliness, and high safety. However, the sluggish sulfur reduction reaction (SRR) kinetics results in poor sulfur utilization, which seriously hampers the electrochemical performance of Li–S batteries. It is critical to reveal the underlying reaction mechanisms and accelerate the SRR kinetics. Herein, the critical issues of SRR in Li–S batteries are reviewed. The conversion mechanisms and reaction pathways of sulfur reduction are initially introduced to give an overview of the SRR. Subsequently, recent advances in catalyst materials that can accelerate the SRR kinetics are summarized in detail, including carbon, metal compounds, metals, and single atoms. Besides, various characterization approaches for SRR are discussed, which can be divided into three categories: electroche mical measurements, spectroscopic techniques, and theoretical calculations. Finally, the conclusion and outlook part gives a summary and proposes several key points for future investigations on the mechanisms of the SRR and catalyst activities. This review can provide cutting‐edge insights into the SRR in Li–S batteries.

Oxide‐Based Solid‐State Batteries: A Perspective on Composite Cathode Architecture - Yaoyu Ren, Timo Danner, Alexandra C. Moy, Martin Finsterbusch, Tanner Hamann, Jan Dippell, Till Fuchs, Marius Müller, Ricky Hoft, André Weber, Larry A. Curtiss, Peter Zapol, Matthew Klenk, Anh T. Ngo, Pallab Barai, Brandon C. Wood, Rongpei Shi, Liwen F. Wan, Tae Wook Heo, M. Engels (Advanced Energy Materials, 2022)
Abstract The garnet‐type phase Li 7 La 3 Zr 2 O 12 (LLZO) attracts significant attention as an oxide solid electrolyte to enable safe and robust solid‐state batteries (SSBs) with potentially high energy density. However, while significant progress has been made in demonstrating compatibility with Li metal, integrating LLZO into composite cathodes remains a challenge. The current perspective focuses on the critical issues that need to be addressed to achieve the ultimate goal of an all‐solid‐state LLZO‐based battery that delivers safety, durability, and pack‐level performance characteristics that are unobtainable with state‐of‐the‐art Li‐ion batteries. This perspective complements existing reviews of solid/solid interfaces with more emphasis on understanding numerous homo‐ and heteroionic interfaces in a pure oxide‐based SSB and the various phenomena that accompany the evolution of the chemical, electrochemical, structural, morphological, and mechanical properties of those interfaces du ring processing and operation. Finally, the insights gained from a comprehensive literature survey of LLZO–cathode interfaces are used to guide efforts for the development of LLZO‐based SSBs.

Polysiloxane‐Based Single‐Ion Conducting Polymer Blend Electrolyte Comprising Small‐Molecule Organic Carbonates for High‐Energy and High‐Power Lithium‐Metal Batteries - Hai‐Peng Liang, Maider Zarrabeitia, Zhen Chen, Sven Jovanovic, Steffen Merz, Josef Granwehr, Stefano Passerini, Dominic Bresser (Advanced Energy Materials, 2022)
Abstract Single‐ion conducting polymer electrolytes are considered particularly attractive for realizing high‐performance solid‐state lithium‐metal batteries. Herein, a polysiloxane‐based single‐ion conductor (PSiO) is investigated. The synthesis is performed via a simple thiol‐ene reaction, yielding flexible and self‐standing polymer electrolyte membranes (PSiOM) when blended with poly(vinylidene fluoride‐ co ‐hexafluoropropylene) (PVdF‐HFP). When incorporating 57 wt% of organic carbonates, these polymer membranes provide a Li + conductivity of >0.4 mS cm −1 at 20 °C and a wide electrochemical stability window of more than 4.8 V. This excellent electrochemical stability allows for the highly reversible cycling of symmetric Li||Li cells as well as high‐energy Li||LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC 622 ) and Li||LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC 811 ) cells for several hundred cycles at relatively high discharge and charge rates. Remarkably, Li||NMC 811 cells with high mass loading cathod es provide more than 76% capacity retention at a high current density of 1.44 mA cm −2 , thus rendering this polymer electrolyte suitable for high‐performance battery applications.

Mechanistic Elucidation of Electronically Conductive PEDOT:PSS Tailored Binder for a Potassium‐Ion Battery Graphite Anode: Electrochemical, Mechanical, and Thermal Safety Aspects - Daniel A. Gribble, Zheng Li, Bertan Özdoğru, Evan McCulfor, Ömer Özgür Çapraz, Vilas G. Pol (Advanced Energy Materials, 2022)
Abstract Potassium‐ion batteries (KIBs) are considered more appropriate for grid‐scale storage than lithium‐ion batteries (LIBs) due to similar operating chemistry, abundant precursors, and compatibility with low‐cost graphite anodes. However, a larger ion reduces rate capabilities and exacerbates capacity fading from volumetric expansion. Herein, conductive polymer, poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), is substituted for standard insulating polyvinylidene fluoride (PVDF). Half‐cells using carbon black (CB) in continuously conductive PEDOT:PSS/CB binder outperforms PVDF/CB by mitigating electrically isolated “dead” graphite, improving 100 cycle capacity retention at C/10 from 63 to 80%. Enhanced electrical contact with PEDOT:PSS/CB also reduces ion impedance and improves rate capabilities. Without CB however, PEDOT:PSS binder performs poorly in electrochemical studies despite promising ex situ electronic conductivity. This discrepancy is mechanistically e lucidated through identification of redox activity between PEDOT:PSS and K + which results in high impedances in the anode operating voltage window. Additionally, the impact of conducting binder on mechanical properties and thermal safety of the anode is investigated. Brittleness and poor wettability of PEDOT:PSS are identified as issues, but greater stability against reactive KC 8 reduces overall heat generation. Binder substitution offers a promising means of mitigating issues with current KIB anodes regardless of active material, and the work herein addresses issues towards further improvement.

Progress in electrolyte and interface of hard carbon and graphite anode for sodium‐ion battery - Qi Liu, Xu Rigan, Daobin Mu, Guoqiang Tan, Hongcai Gao, Ning Li, Renjie Chen, Feng Wu (Carbon Energy, 2022)
Abstract It is essential to replace lithium‐ion batteries (LIBs) from the perspective of the Earth's resources and the sustainable development of mankind. Sodium‐ion batteries (SIBs) are important candidates due to their low price and abundant storage capacity. Hard carbon (HC) and graphite have important applications in anode materials of SIBs. In this review, the research progress in electrolyte and interface between HC and graphite anode for SIBs is summarized. The properties and performance of three types of widely used electrolytes (carbonate ester, ether, and ionic liquid) with additives, as well as the formation of solid electrolyte interface (SEI), which are crucial to the reversible capacity and rate capability of HC anodes, are also discussed. In this review, the co‐intercalation performance and mechanism of solvation Na + into graphite are summarized. Besides, the faced challenges and existing problems in this field are also succinctly highlighted.

Deciphering the lithium storage chemistry in flexible carbon fiber‐based self‐supportive electrodes - Hao Yang, Tuzhi Xiong, Zhixiao Zhu, Ran Xiao, Xincheng Yao, Yongchao Huang, Muhammad‐Sadeeq Balogun (Carbon Energy, 2022)
Abstract Flexible carbon fiber cloth (CFC) is an important scaffold and/or current collector for active materials in the development of flexible self‐supportive electrode materials (SSEMs), especially in lithium‐ion batteries. However, during the intercalation of Li ions into the matrix of CFC (below 0.5 V vs. Li/Li + ), the incompatibility in the capacity of the CFC, when used directly as an anode material or as a current collector for active materials, leads to difficulty in the estimation of its actual contribution. To address this issue, we prepared Ni 5 P 4 nanosheets on CFC (denoted CFC@Ni 5 P 4 ) and investigated the contribution of CFC in the CFC@Ni 5 P 4 by comparing to the powder Ni 5 P 4 nanosheets traditionally coated on a copper foil (CuF) (denoted P‐Ni 5 P 4 ). At a current density of 0.4 mA cm −2 , the as‐prepared CFC@Ni 5 P 4 showed an areal capacity of 7.38 mAh cm −2 , which is significantly higher than that of the P‐Ni 5 P 4 electrode. More importantly, theoretical st udies revealed that the CFC has a high Li adsorption energy that contributes to the low Li‐ion diffusion energy barrier of the Ni 5 P 4 due to the strong interaction between the CFC and Ni 5 P 4 , leading to the superior Li‐ion storage performance of the CFC@Ni 5 P 4 over the pristine Ni 5 P 4 sample. This present work unveils the underlying mechanism leading to the achievement of high performance in SSEMs.

Recent advances in solid‐state metal–air batteries - Qi Sun, Lei Dai, Tingting Luo, Ling Wang, Feng Liang, Shan Liu (Carbon Energy, 2022)
Abstract Solid‐state metal–air batteries have emerged as a research hotspot due to their high energy density and high safety. Moreover, side reactions caused by infiltrated gases (O 2 , H 2 O, or CO 2 ) and safety issues caused by liquid electrolyte leakage will be eliminated radically. However, the solid‐state metal–air battery is still in its infancy, and many thorny problems still need to be solved, such as the large resistance of the metal/electrolyte interface and catalyst design. This review will summarize some important progress and key issues for solid‐state metal–air batteries, especially the lithium‐, sodium‐, and zinc‐based metal–air batteries, clarify some core issues, and forecast the future direction of the solid‐state metal–air batteries.

A novel design of 3D carbon host for stable lithium metal anode - Hang Liu, Jie Di, Ping Wang, Rui Gao, Han Tian, Pengfei Ren, Qingxi Yuan, Wanxia Huang, Ruiping Liu, Qiang Liu, Ming Feng (Carbon Energy, 2022)
Abstract Rational design of porous conductive hosts with high electrical conductivity, large surface area, and adequate interior space is desirable to suppressing dendritic lithium growth and accommodating large volume change of lithium metal anode during the Li plating/stripping process. However, due to the conductive nature of the conductive hosts, Li is easily deposited directly on the top of the hosts, which hinders it from fully functioning. To circumvent the issue, in this study, we designed a novel porous carbon host with a gradient‐pore‐size structure based on one‐dimensional (1D) carbon with different diameters. With this kind of host, stable cycling with high and stable Coulombic efficiency of ~98% is achieved at 0.5 mA cm −2 with an areal capacity of 1 mAh cm −2 over 320 cycles. In contrast, the normal three‐dimensional (3D) carbon nanotube host presents a moss‐like Li morphology with wildly fluctuating Coulombic efficiency after 100 cycles. The results reveal that the uniqu e gradient‐pore‐size structure of the 3D conductive host greatly improves the performance of lithium metal batteries.

Nature‐inspired materials and designs for flexible lithium‐ion batteries - Heng Li, Huibo Wang, Dan Chan, Zhu Xu, Kexuan Wang, Mingzheng Ge, Yanyan Zhang, Shi Chen, Yuxin Tang (Carbon Energy, 2022)
Abstract Flexible lithium‐ion batteries (FLBs) are of critical importance to the seamless power supply of flexible and wearable electronic devices. However, the simultaneous acquirements of mechanical deformability and high energy density remain a major challenge for FLBs. Through billions of years of evolutions, many plants and animals have developed unique compositional and structural characteristics, which enable them to have both high mechanical deformability and robustness to cope with the complex and stressful environment. Inspired by nature, many new materials and designs emerge recently to achieve mechanically flexible and high storage capacity of lithium‐ion batteries at the same time. Here, we summarize these novel FLBs inspired by natural and biological materials and designs. We first give a brief introduction to the fundamentals and challenges of FLBs. Then, we highlight the latest achievements based on nature inspiration, including fiber‐shaped FLBs, origami and kirigami‐d erived FLBs, and the nature‐inspired structural designs in FLBs. Finally, we discuss the current status, remaining challenges, and future opportunities for the development of FLBs. This concise yet focused review highlights current inspirations in FLBs and wishes to broaden our view of FLB materials and designs, which can be directly “borrowed” from nature.

Highly branched amylopectin binder for sulfur cathodes with enhanced performance and longevity - Luke Hencz, Hao Chen, Zhenzhen Wu, Shangshu Qian, Su Chen, Xingxing Gu, Xianhu Liu, Cheng Yan, Shanqing Zhang (Exploration, 2022)
The sulfur cathode of lithium-sulfur (Li-S) batteries suffers from inherent problems of insufficient mechanical strength and the dissolution of sulfur and polysulfides. Inspired by the extraordinarily resilient and strong binding force of the Great Wall binder, that is, the sticky rice mortar, we extracted highly branched amylopectin (HBA), the effective ingredient, as a low-cost, nontoxic and environmentally benign aqueous binder for the sulfur cathode. The HBA-based cells outperform the Li-S batteries based on the traditional polyvinyldene diflouride (PVDF) binder and a lowly branched polysaccharide binder. The improved electrochemical performance in the HBA-based cell could be attributed to two mechanisms. First, the branched structure of the HBA provides enhanced mechanical and adhesive properties, which allow for a robust electronic and ionic conductive framework to be maintained throughout the cathode after extended cycling. Second, the HBA shows enhanced polysulfide retention du e to the polymer's abundant lone-pair rich hydroxyl groups and the formation of C─S bonds between the HBA and polysulfides prohibits the shuttle effect of polysulfides. The improved mechanical properties and polysulfide retention function of the HBA binder facilitate the HBA-based Li-S battery to deliver a long cycle life of 500 cycles at 2 C while only displaying a capacity fading of 0.104% per cycle.

A functionalized separator enables dendrite‐free Zn anode via metal‐polydopamine coordination chemistry - Yanfen Liu, Shude Liu, Xuesong Xie, Zhicheng Li, Pinji Wang, Bingan Lu, Shuquan Liang, Yan Tang, Jiang Zhou (InfoMat, 2022)
Abstract Designing a multifunctional separator with abundant ion migration paths is crucial for tuning the ion transport in rocking‐chair‐type batteries. Herein, a polydopamine‐functionalized PVDF (PVDF@PDA) nanofibrous membrane is designed to serve as a separator for aqueous zinc‐ion batteries (AZIBs). The functional groups (OH and NH) in PDA facilitate the formation of ZnO and ZnN coordination bonds with Zn ions, homogenizing the Zn‐ion flux and thus enabling dendrite‐free Zn deposition. Moreover, the PVDF@PDA separator effectively inhibits the shuttling of V‐species through the formation of VO coordination bonds. As a result, the Zn/NH 4 V 4 O 10 battery with the PVDF@PDA separator exhibits enhanced cycling stability (92.3% after 1000 cycles at 5 A g −1 ) and rate capability compared to that using a glass fiber separator. This work provides a new avenue to design functionalized separators for high‐performance AZIBs. image

Air sensitivity of electrode materials in Li/Na ion batteries: Issues and strategies - Ruiwang Zhang, Sijie Yang, Haobo Li, Haobo Li, Tianyou Zhai, Huiqiao Li, Huiqiao Li (InfoMat, 2022)
Abstract With the development of electrode materials in lithium ion batteries—upgrading from LiCoO 2 and LiFePO 4 to Ni‐rich layered oxides, and the shifting of battery systems from high cost lithium ion to low cost sodium ion technology, the air sensitivity of the electrode materials has become an increasingly important issue in both production and application. Furthermore, the air sensitivity of electrode materials must be carefully considered throughout nearly all stages of their life, including material design, synthesis, production, storage, packaging, transportation, and battery assembly. Therefore, a fundamental understanding of the air degradation mechanism of electrode materials and the exploration of new methods to enhance their air stability are of great significance for the development of batteries with better performance. Herein, we provide a review of the issues related to air exposure of electrode materials in Li/Na ion batteries, including factors related to air sensiti vity, degradation mechanisms, and recent progress in improving their air stability. The merits and existing challenges of different strategies are presented, and a rational design perspective as well as general principles for evaluating air stability are proposed. image

Complex permittivity‐dependent plasma confinement‐assisted growth of asymmetric vertical graphene nanofiber membrane for high‐performance Li‐S full cells - Yongshang Zhang, Zhiheng Wu, Shaobin Wang, Neng Li, S. Ravi P. Silva, Guosheng Shao, Peng Zhang (InfoMat, 2022)
Abstract Vertical graphene (VG), possessing superior chemical, physical, and structural peculiarities, holds great promise as a building block for constructing a high‐energy density lithium‐sulfur (Li‐S) battery. Therefore, it is desirable to develop a new VG growth technique with a novel structure to enable wide applications. Herein, we devise a novel complex permittivity‐dependent plasma confinement‐assisted VG growth technique, via asymmetric growing a VG layer on one side of N‐doped carbon nanofibers for the first time, using a unique lab‐built high flux plasma‐enhanced chemical vapor deposition system, as a bifunctional nanofiber membrane to construct Li‐S batteries with low negative/positive (N/P) and electrolyte/sulfur (E/S) ratios. The unique nanofiber membrane could simultaneously protect the cathode and anode, enabling an excellent electrochemical performance with low N/P and E/S ratios in Li‐S batteries. Such a full cell delivers high gravimetric energy density and volumetri c energy density of 340 Wh kg −1 and 547 Wh L −1 , respectively, at low N/P (2:1) and E/S (4:1) ratios. Furthermore, a pouch cell achieves a high areal capacity of 7.1 mAh cm −2 at a sulfur loading of 6 mg cm −2 . This work put forward a novel pathway for the design of high‐energy density Li‐S batteries. image

A facile, scalable, high stability Lithium metal anode - Qiang Zhao, Xin Chen, Wang Hou, Beirong Ye, Yongqi Zhang, Xinhui Xia, Jinshu Wang (SusMat, 2022)
Abstract Li has garnered enormous attention for next‐generation Li metal batteries owing to its remarkable theoretical capacity. Unfortunately, as an anode, Li suffers from serious safety issues and fast capacity fading due to the formation of Li dendrites, which hinders the practical application of Li anode. Herein, a LiAlO 2 ‐PVDF composite modification layer is fabricated on the surface of Li metal to enhance its stability and electrochemical performance. Benefitting from the synergetic effects of high Li + conductivity, high Li + transference number, excellent mechanical properties, superior chemical durability, and compactness of the modification layer, the LiAlO 2 ‐PVDF@Li electrode delivers an ultra‐long lifespan and a high capacity retention rate in the LiAlO 2 ‐PVDF@Li│LiFePO 4 full cell. The proposed strategy provides a new alternative anode for Li metal batteries with high performance and scalable production.

Order‐structured solid‐state electrolytes - Jingyi Wu, Zhixiang Rao, Huanlei Wang, Yunhui Huang (SusMat, 2022)
Abstract Solid‐state electrolytes (SSEs) are recognized as attractive candidates to realize safe and high‐energy‐density lithium metal batteries (LMBs). However, the practical application of SSEs still faces challenges such as insufficient room‐temperature ionic conductivity, unsatisfactory mechanical properties, and large internal resistance. Extensive research efforts have been made to explore new electrochemistry and technologies to address those challenges. Among them, the construction of order‐structured SSEs has emerged as a promising strategy. The anisotropic behavior induced by the orientation offers SSEs with desired properties targeting specific functions, and therefore the rational design of the order‐structured SSE provides an alternative solution to achieve an ideal SSE. This review discusses the structure‐property correlation of SSEs, and then summarizes the design strategies to construct order‐structured SSEs. Finally, the current challenges and possible future research directions for order‐structured SSEs for scalable high‐energy‐density LMBs are presented.

Bronze‐Phase TiO2 as Anode Materials in Lithium and Sodium‐Ion Batteries - Suzhe Liang, Xiaoyan Wang, Ruoxuan Qi, Ya‐Jun Cheng, Yonggao Xia, Peter Müller‐Buschbaum, Xile Hu (Advanced Functional Materials, 2022)
Abstract Titanium dioxide of bronze phase (TiO 2 (B)) has attracted considerable attention as a promising alternative lithium/sodium‐ion battery anode due to its excellent operation safety, good reversible capacity, and environmental friendliness. However, several intrinsic critical drawbacks, including moderate electrochemical kinetics and unsatisfactory long cyclic stability, significantly limit its practical applications. It is crucial to develop reliable strategies to resolve these issues to advance the TiO 2 (B) based materials into practical applications in lithium/sodium‐ion batteries. In this review, both the theoretical and experimental investigations on the TiO 2 (B) based materials over the last few decades are chronically elaborated. Insights on the general and detailed evolution trends of the research on TiO 2 (B) anodes are provided. The review also points to future directions for the TiO 2 (B) anode research to advance the practical application of TiO 2 (B) anodes.

Operating Highly Stable LiCoO2 Cathodes up to 4.6 V by Using an Effective Integration of Surface Engineering and Electrolyte Solutions Selection - Tianju Fan, Kai Wang, Villa Krishna Harika, Cunsheng Liu, Amey Nimkar, Nicole Leifer, Sandipan Maiti, Judith Grinblat, Merav Nadav Tsubery, Xiaolang Liu, Meng Wang, Leimin Xu, Yuhao Lu, Yonggang Min, Netanel Shpigel, Doron Aurbach (Advanced Functional Materials, 2022)
Abstract The need for high power density cathodes for Li‐ion batteries can be fulfilled by application of a high charging voltage above 4.5 V. As lithium cobalt oxide (LCO) remains a dominant commercial cathode material, tremendous efforts are invested to increase its charging potential toward 4.6 V. Yet, the long‐term performance of high voltage LCO cathodes still remains poor. Here, an integrated approach combining the application of an aluminum fluoride coating and the use of electrolyte solutions comprising 1:1:8 mixtures of difluoroethylene:fluoroethylene carbonate:dimethyl carbonate and 1 m LiPF 6 is reported. This results in superior behavior of LCO cathodes charged at 4.6 V with high initial capacity of 223 mAh g −1 , excellent long‐term performance, and 78% capacity retention after 500 cycles. Impressive stability is also found at 450 °C with an initial capacity of 220 mAh g −1 and around 84% capacity retention after 100 cycles. Systematic post‐mortem analysis of LCO cathodes and Li anodes after prolonged cycling reveals two main degradation routes related to changes at the surface of the cathodes and formation of passivation layers on the anodes. This study demonstrates the importance of appropriate selection of electrolyte solutions and development of effective coatings for improved performance of high voltage LCO‐based Li batteries.

Uniform lithiophilic layers in 3D current collectors enable ultrastable solid electrolyte interphase for high-performance lithium metal batteries - Chi Guo, Yaqing Guo, Runming Tao, Xiaobin Liao, Kang Du, Huan Zou, Wang Zhang, Jiyuan Liang, Deyu Wang, Xiao‐Guang Sun, Shih‐Yuan Lu (Nano Energy, 2022)

Encapsulation of nano-Si into MOF glass to enhance lithium-ion battery anode performances - Jiajia Yan, Chengwei Gao, Shibin Qi, Zhenjing Jiang, Lars R. Jensen, Hongbing Zhan, Yanfei Zhang, Yuanzheng Yue (Nano Energy, 2022)
Although metal-organic framework (MOF) glasses have exhibited high potential to be applied as anode materials for lithium-ion batteries (LIBs), their electrochemical performances still need to be greatly improved to match the rapid development of green energy technologies. Silicon is a promising candidate for the next generation of LIB anode but suffers from vast volume fluctuations upon lithiation/delithiation. Here, we present a strategy to in situ grow a kind of MOF, namely, cobalt-ZIF-62 (Co(imidazole) 1.75 (benzimidazole) 0.25 ) on the surface of Si nano particles, and then to transform the thus-derived material into Si@ZIF-glass composite (SiZGC) through meltquenching. The robust hierarchical structure of the SiZGC based anode exhibits the specific capacity of ~650 mA h g -1 , which is about three times that of pure ZIF glass and about six times that of pristine ZIF crystal at 1 A g - 1 after 500 cycles. The origin of this huge enhancement is revealed by performing structural ana lyses. The ZIF glass phase can not only contribute to lithium storage, but also buffer the volume changes and prevent the aggregation of Si nano particles during lithiation/delithiation processes.

Phase Engineering of Defective Copper Selenide toward Robust Lithium–Sulfur Batteries - Dawei Yang, Mengyao Li, Xuejiao Zheng, Xu Han, Chaoqi Zhang, Jordi Jacas Biendicho, Jordi Llorca, Jiaao Wang, Hongchang Hao, Junshan Li, Graeme Henkelman, Jordi Arbiol, J.R. Morante, David Mitlin, Shulei Chou, Andreu Cabot (ACS Nano, 2022)
The shuttling of soluble lithium polysulfides (LiPS) and the sluggish Li–S conversion kinetics are two main barriers toward the practical application of lithium–sulfur batteries (LSBs). Herein, we propose the addition of copper selenide nanoparticles at the cathode to trap LiPS and accelerate the Li–S reaction kinetics. Using both computational and experimental results, we demonstrate the crystal phase and concentration of copper vacancies to control the electronic structure of the copper selenide, its affinity toward LiPS chemisorption, and its electrical conductivity. The adjustment of the defect density also allows for tuning the electrochemically active sites for the catalytic conversion of polysulfide. The optimized S/Cu1.8Se cathode efficiently promotes and stabilizes the sulfur electrochemistry, thus improving significantly the LSB performance, including an outstanding cyclability over 1000 cycles at 3 C with a capacity fading rate of just 0.029% per cycle, a superb rate capabil ity up to 5 C, and a high areal capacity of 6.07 mAh cm–2 under high sulfur loading. Overall, the present work proposes a crystal phase and defect engineering strategy toward fast and durable sulfur electrochemistry, demonstrating great potential in developing practical LSBs.

Fluorinated ether electrolyte with controlled solvation structure for high voltage lithium metal batteries - Yan Zhao, Tianhong Zhou, Timur Ashirov, Mario El Kazzi, Claudia Cancellieri, Lars P. H. Jeurgens, Jang Wook Choi, Ali Coşkun (Nature Communications, 2022)
Abstract The development of new solvents is imperative in lithium metal batteries due to the incompatibility of conventional carbonate and narrow electrochemical windows of ether-based electrolytes. Whereas the fluorinated ethers showed improved electrochemical stabilities, they can hardly solvate lithium ions. Thus, the challenge in electrolyte chemistry is to combine the high voltage stability of fluorinated ethers with high lithium ion solvation ability of ethers in a single molecule. Herein, we report a new solvent, 2,2-dimethoxy-4-(trifluoromethyl)-1,3-dioxolane (DTDL), combining a cyclic fluorinated ether with a linear ether segment to simultaneously achieve high voltage stability and tune lithium ion solvation ability and structure. High oxidation stability up to 5.5 V, large lithium ion transference number of 0.75 and stable Coulombic efficiency of 99.2% after 500 cycles proved the potential of DTDL in high-voltage lithium metal batteries. Furthermore, 20 μm thick lithium paire d LiNi 0.8 Co 0.1 Mn 0.1 O 2 full cell incorporating 2 M LiFSI-DTDL electrolyte retained 84% of the original capacity after 200 cycles at 0.5 C.

Rational design of a topological polymeric solid electrolyte for high-performance all-solid-state alkali metal batteries - Yun Su, Xiaohui Rong, Ang Gao, Yuan Liu, Jianwei Li, Minglei Mao, Xingguo Qi, Guoliang Chai, Qinghua Zhang, Liumin Suo, Lin Gu, Hong Li, Xuejie Huang, Liquan Chen, Binyuan Liu, Yong‐Sheng Hu (Nature Communications, 2022)
Abstract Poly(ethylene oxide)-based solid-state electrolytes are widely considered promising candidates for the next generation of lithium and sodium metal batteries. However, several challenges, including low oxidation resistance and low cation transference number, hinder poly(ethylene oxide)-based electrolytes for broad applications. To circumvent these issues, here, we propose the design, synthesis and application of a fluoropolymer, i.e., poly(2,2,2-trifluoroethyl methacrylate). This polymer, when introduced into a poly(ethylene oxide)-based solid electrolyte, improves the electrochemical window stability and transference number. Via multiple physicochemical and theoretical characterizations, we identify the presence of tailored supramolecular bonds and peculiar morphological structures as the main factors responsible for the improved electrochemical performances. The polymeric solid electrolyte is also investigated in full lithium and sodium metal lab-scale cells. Interestingly, w hen tested in a single-layer pouch cell configuration in combination with a Li metal negative electrode and a LiMn 0.6 Fe 0.4 PO 4 -based positive electrode, the polymeric solid-state electrolyte enables 200 cycles at 42 mA·g −1 and 70 °C with a stable discharge capacity of approximately 2.5 mAh when an external pressure of 0.28 MPa is applied.

A dual-function liquid electrolyte additive for high-energy non-aqueous lithium metal batteries - Yuji Zhang, Wu Yuan, Huiyi Li, Jinghao Chen, Danni Lei, Chengxin Wang (Nature Communications, 2022)
Abstract Engineering the formulation of non-aqueous liquid electrolytes is a viable strategy to produce high-energy lithium metal batteries. However, when the lithium metal anode is combined with a Ni-rich layered cathode, the (electro)chemical stability of both electrodes could be compromised. To circumvent this issue, we report a combination of aluminum ethoxide (0.4 wt.%) and fluoroethylene carbonate (5 vol.%) as additives in a conventional LiPF 6 -containing carbonate-based electrolyte solution. This electrolyte formulation enables the formation of mechanically robust and ionically conductive interphases on both electrodes’ surfaces. In particular, the alumina formed at the interphases prevents the formation of dendritic structures on the lithium metal anode and mitigate the stress-induced cracking and phase transformation in the Ni-rich layered cathode. By coupling a thin (i.e., about 40 μm) lithium metal anode with a high-loading (i.e., 21.5 mg cm −2 ) LiNi 0.8 Co 0.1 Mn 0.1 O 2 -based cathode in coin cell configuration and lean electrolyte conditions, the engineered electrolyte allows a specific discharge capacity retention of 80.3% after 130 cycles at 60 mA g −1 and 30 °C which results in calculated specific cell energy of about 350 Wh kg −1 .

Development of high-energy non-aqueous lithium-sulfur batteries via redox-active interlayer strategy - Byong‐June Lee, Chen Zhao, Jeong‐Hoon Yu, Tong‐Hyun Kang, Hyean‐Yeol Park, Joonhee Kang, Yongju Jung, Xiang Liu, Tianyi Li, Wenqian Xu, Xiaobing Zuo, Gui‐Liang Xu, Khalil Amine, Jong‐Sung Yu (Nature Communications, 2022)
Abstract Lithium-sulfur batteries have theoretical specific energy higher than state-of-the-art lithium-ion batteries. However, from a practical perspective, these batteries exhibit poor cycle life and low energy content owing to the polysulfides shuttling during cycling. To tackle these issues, researchers proposed the use of redox-inactive protective layers between the sulfur-containing cathode and lithium metal anode. However, these interlayers provide additional weight to the cell, thus, decreasing the practical specific energy. Here, we report the development and testing of redox-active interlayers consisting of sulfur-impregnated polar ordered mesoporous silica. Differently from redox-inactive interlayers, these redox-active interlayers enable the electrochemical reactivation of the soluble polysulfides, protect the lithium metal electrode from detrimental reactions via silica-polysulfide polar-polar interactions and increase the cell capacity. Indeed, when tested in a non-aqueou s Li-S coin cell configuration, the use of the interlayer enables an initial discharge capacity of about 8.5 mAh cm −2 (for a total sulfur mass loading of 10 mg cm −2 ) and a discharge capacity retention of about 64 % after 700 cycles at 335 mA g −1 and 25 °C.

Revealing solid electrolyte interphase formation through interface-sensitive Operando X-ray absorption spectroscopy - J. Swallow, Michael Fraser, Nis‐Julian H. Kneusels, Jodie F. Charlton, Christopher Sole, Conor Phelan, Erik Björklund, Peter Bencok, Carlos Escudero, Virginia Pérez‐Dieste, Clare P. Grey, Rebecca J. Nicholls, Robert S. Weatherup (Nature Communications, 2022)
The solid electrolyte interphase (SEI) that forms on Li-ion battery anodes is critical to their long-term performance, however observing SEI formation processes at the buried electrode-electrolyte interface is a significant challenge. Here we show that operando soft X-ray absorption spectroscopy in total electron yield mode can resolve the chemical evolution of the SEI during electrochemical formation in a Li-ion cell, with nm-scale interface sensitivity. O, F, and Si K-edge spectra, acquired as a function of potential, reveal when key reactions occur on high-capacity amorphous Si anodes cycled with and without fluoroethylene carbonate (FEC). The sequential formation of inorganic (LiF) and organic (-(C=O)O-) components is thereby revealed, and results in layering of the SEI. The addition of FEC leads to SEI formation at higher potentials which is implicated in the rapid healing of SEI defects and the improved cycling performance observed. Operando TEY-XAS offers new insights into the f ormation mechanisms of electrode-electrolyte interphases and their stability for a wide variety of electrode materials and electrolyte formulations.

On the nanoscale structural evolution of solid discharge products in lithium-sulfur batteries using operando scattering - Christian Prehal, Jean‐Marc von Mentlen, Sara Drvarič Talian, Alen Vižintin, Robert Dominko, Heinz Amenitsch, Lionel Porcar, Stefan A. Freunberger, Vanessa Wood (Nature Communications, 2022)
Abstract The inadequate understanding of the mechanisms that reversibly convert molecular sulfur (S) into lithium sulfide (Li 2 S) via soluble polysulfides (PSs) formation impedes the development of high-performance lithium-sulfur (Li-S) batteries with non-aqueous electrolyte solutions. Here, we use operando small and wide angle X-ray scattering and operando small angle neutron scattering (SANS) measurements to track the nucleation, growth and dissolution of solid deposits from atomic to sub-micron scales during real-time Li-S cell operation. In particular, stochastic modelling based on the SANS data allows quantifying the nanoscale phase evolution during battery cycling. We show that next to nano-crystalline Li 2 S the deposit comprises solid short-chain PSs particles. The analysis of the experimental data suggests that initially, Li 2 S 2 precipitates from the solution and then is partially converted via solid-state electroreduction to Li 2 S. We further demonstrate that mass transpo rt, rather than electron transport through a thin passivating film, limits the discharge capacity and rate performance in Li-S cells.

Redox-homogeneous, gel electrolyte-embedded high-mass-loading cathodes for high-energy lithium metal batteries - Jung‐Hui Kim, Ju‐Myung Kim, Seok-Kyu Cho, Nag-Young Kim, Sang‐Young Lee (Nature Communications, 2022)
Abstract Lithium metal batteries have higher theoretical energy than their Li-ion counterparts, where graphite is used at the anode. However, one of the main stumbling blocks in developing practical Li metal batteries is the lack of cathodes with high-mass-loading capable of delivering highly reversible redox reactions. To overcome this issue, here we report an electrode structure that incorporates a UV-cured non-aqueous gel electrolyte and a cathode where the LiNi 0.8 Co 0.1 Mn 0.1 O 2 active material is contained in an electron-conductive matrix produced via simultaneous electrospinning and electrospraying. This peculiar structure prevents the solvent-drying-triggered non-uniform distribution of electrode components and shortens the time for cell aging while improving the overall redox homogeneity. Moreover, the electron-conductive matrix eliminates the use of the metal current collector. When a cathode with a mass loading of 60 mg cm −2 is coupled with a 100 µm thick Li metal electr ode using additional non-aqueous fluorinated electrolyte solution in lab-scale pouch cell configuration, a specific energy and energy density of 321 Wh kg −1 and 772 Wh L −1 (based on the total mass of the cell), respectively, can be delivered in the initial cycle at 0.1 C (i.e., 1.2 mA cm −2 ) and 25 °C.

High‐Entropy Alloys to Activate the Sulfur Cathode for Lithium–Sulfur Batteries - Zhenyu Wang, Hai-Lun Ge, Sheng Liu, Guoran Li, Xueping Gao (Energy & environment materials, 2022)
Sulfur element possesses an ultrahigh theoretical specific capacity, while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products, limiting the enhancement on energy density of lithium–sulfur batteries. Herein, for the first time, Fe 0.24 Co 0.26 Ni 0.10 Cu 0.15 Mn 0.25 high‐entropy alloy is introduced as the core catalytic host to activate the electrochemical performance of the sulfur cathode for lithium–sulfur batteries. It is manifested that Fe 0.24 Co 0.26 Ni 0.10 Cu 0.15 Mn 0.25 high‐entropy alloy nanocrystallites distributed on nitrogen‐doped carbon exhibit high electrocatalytic activity toward the conversion of solid sulfur to solid discharged products across soluble intermediate lithium polysulfides. In particular, benefiting from the accelerated kinetics by high‐entropy alloy nanocrystallites and synergistic adsorption by nitrogen‐doped carbon, the cathode exhibits high reversible capacity of 1079.5 mA h g ‐cathode −1 (high utilization of 89.4%) with the whole cathode as active material, instead of sulfur element. Moreover, under both lean electrolyte (3 μL mg −1 ) and ultrahigh sulfur loading (27.0 mg cm −2 ) condition, the high discharge capacity of 868.2 mAh g ‐cathode −1 can be still achieved for the sulfur cathode. This strategy opens up a new path to explore catalytic host materials for enhancing the utilization of sulfur in the whole cathode for lithium–sulfur batteries.

Surface modification and structure constructing for improving the lithium ion transport properties of PVDF based solid electrolytes - Yujie Jiang, Chao Xu, Kang Xu, Siyu Li, Jiaxi Ni, Yifan Wang, Yingjie Liu, Jinhai Cai, Chunyan Lai (Chemical Engineering Journal, 2022)

A polydopamine-modified garnet–based polymer-in-ceramic hybrid solid electrolyte membrane for high-safety lithium metal batteries - Tadesu Hailu Mengesha, Shimelis Lemma Beshahwured, Yi–Shiuan Wu, She‐Huang Wu, Rajan Jose, Chun‐Chen Yang (Chemical Engineering Journal, 2022)

A long-life lithium-oxygen battery via a molecular quenching/mediating mechanism - Jinqiang Zhang, Yufei Zhao, Bing Sun, Yuan Xie, Anastasia Tkacheva, Feilong Qiu, Ping He, Haoshen Zhou, Kang Yan, Xin Guo, Shijian Wang, Andrew M. McDonagh, Zhangquan Peng, Jun Lü, Guoxiu Wang (Science Advances, 2022)
The advancement of lithium-oxygen (Li-O 2 ) batteries has been hindered by challenges including low discharge capacity, poor energy efficiency, severe parasitic reactions, etc. We report an Li-O 2 battery operated via a new quenching/mediating mechanism that relies on the direct chemical reactions between a versatile molecule and superoxide radical/Li 2 O 2 . The battery exhibits a 46-fold increase in discharge capacity, a low charge overpotential of 0.7 V, and an ultralong cycle life >1400 cycles. Featuring redox-active 2,2,6,6-tetramethyl-1-piperidinyloxy moieties bridged by a quenching-active perylene diimide backbone, the tailor-designed molecule acts as a redox mediator to catalyze discharge/charge reactions and serves as a reusable superoxide quencher to chemically react with superoxide species generated during battery operation. The all-in-one molecule can simultaneously tackle issues of parasitic reactions associated with superoxide radicals, singlet oxygen, high overpotenti als, and lithium corrosion. The molecular design of multifunctional additives combining various capabilities opens a new avenue for developing high-performance Li-O 2 batteries.

Decomposition of PVDF to delaminate cathode materials from end-of-life lithium-ion battery cathodes - Yi Ji, Chad T. Jafvert, Nadezhda N. Zyaykina, Fu Zhao (Journal of Cleaner Production, 2022)

How carbon coating or continuous carbon pitch matrix influence the silicon electrode/electrolyte interfaces and the performance in Li‐ion batteries - Aude Roland, Julien Fullenwarth, Jean‐Bernard Ledeuil, Hervé Martinez, Nicolas Louvain, Laure Monconduit (Battery energy, 2022)
Abstract The Si surface coating by carbon is an appealing strategy to improve both the electronic conductivity and to stabilize the solid electrolyte interphase (SEI). In the present study, the electrochemical performance comparison of three nanocrystalline silicon‐based electrodes confirms the advantage brought by the carbon presence either as coating or in a composite, to improve their performance in Li‐ion batteries (LIBs). To rationalize this behavior, a full study of the electrode/electrolyte interface was achieved through the analysis of the cumulated relative irreversible capacity and the impedance and X‐ray photoelectron spectroscopies measurements. The study highlighted that the carbon coating leads to more efficient and less resistive SEI than that formed on silicon or on the native oxide surface. The pitch carbon matrix offers the same advantages and avoids moreover the isolation of particles. The control of the Si/electrolyte interface has a crucial role in the performance of Si‐based electrodes as negative electrodes for LIB.

Mechanism of gelation in high nickel content cathode slurries for sodium-ion batteries - Samuel Roberts, Lin Chen, Brij Kishore, C.E.J. Dancer, Mark Simmons, Emma Kendrick (Journal of Colloid and Interface Science, 2022)
Sodium-ion batteries are a prospective sustainable alternative to the ubiquitous lithium-ion batteries due to the abundancy of sodium, and their cobalt free cathodes. The high nickel O3-type oxides show promising energy densities, however, a time dependency in the rheological properties of the composite electrode slurries is observed, which leads to inhomogeneous coatings being produced. A combination of electron microscopy and infra-red spectroscopy were used to monitor the O3-oxide surface changes upon exposure to air, and the effect upon the rheology and stability of the inks was investigated. Upon exposure to air, NaOH rather than Na 2 CO 3 was observed on the surfaces of the powder through FTIR and EDS. The subsequent gelation of the slurry was initiated by the NaOH and dehydrofluorination with crosslinking of PVDF was observed through the reaction product, NaF. Approximately 15% of the CF bonds in PVDF undergo this dehydrofluorination to form NaF. As observed in the relaxation ti me of fitted rheological data, the gelation undergoes a three-stage process: a dehydrofluorination stage, creating saturated structures, a crosslinking stage, resulting in the highest rate of gelation, and a final crosslinking stage. This work shows the mechanism for instability of high nickel containing powders and electrode slurries, and presents a new time dependent oscillatory rheology test that can be used to determine the process window for these unstable slurry systems.

Coupling Enhancement of a Flexible BiFeO3 Film-Based Nanogenerator for Simultaneously Scavenging Light and Vibration Energies - Xiao Han, Yun Ji, Li Wu, Yanlong Xia, Chris Bowen, Ya Yang (Nano-Micro Letters, 2022)
Abstract Coupled nanogenerators have been a research hotspot due to their ability to harvest a variety of forms of energy such as light, mechanical and thermal energy and achieve a stable direct current output. Ferroelectric films are frequently investigated for photovoltaic applications due to their unique photovoltaic properties and bandgap-independent photovoltage, while the flexoelectric effect is an electromechanical property commonly found in solid dielectrics. Here, we effectively construct a new form of coupled nanogenerator based on a flexible BiFeO 3 ferroelectric film that combines both flexoelectric and photovoltaic effects to successfully harvest both light and vibration energies. This device converts an alternating current into a direct current and achieves a 6.2% charge enhancement and a 19.3% energy enhancement to achieve a multi-dimensional "1 + 1 > 2" coupling enhancement in terms of current, charge and energy. This work proposes a new approach to the coupling of m ultiple energy harvesting mechanisms in ferroelectric nanogenerators and provides a new strategy to enhance the transduction efficiency of flexible functional devices.

Nanowires for UV–vis–IR Optoelectronic Synaptic Devices - Xue Chen, Bingkun Chen, Bei Jiang, Tengfei Gao, Gang Shang, Su‐Ting Han, Chi‐Ching Kuo, Vellaisamy A. L. Roy, Ye Zhou (Advanced Functional Materials, 2022)
Abstract Simulating biological synaptic functionalities through artificial synaptic devices opens up an innovative way to overcome the von Neumann bottleneck at the device level. Artificial optoelectronic synapses provide a non‐contact method to operate the devices and overcome the shortcomings of electrical synaptic devices. With the advantages of high photoelectric conversion efficiency, adjustable light absorption coefficient, and broad spectral range, nanowires (NWs)‐based optoelectronic synapses have attracted wide attention. Herein, to better promote the applications of nanowires‐based optoelectronic synapses for future neuromorphic systems, the functionalities of optoelectronic synaptic devices and the current progress of NWs optoelectronic synaptic devices in UV–vis–IR spectral range are introduced. Furthermore, a bridge between NWs‐based optoelectronic synaptic device and the neuromorphic system is established. Challenges for the forthcoming development of NWs optoelectronic s ynapses are also discussed. This review may offer a vision into the design and neuromorphic applications of NWs‐based optoelectronic synaptic devices.

Perovskite multifunctional logic gates via bipolar photoresponse of single photodetector - Woochul Kim, Hyeonghun Kim, Tae Jin Yoo, Jun Young Lee, Ji Young Jo, Byoung Hun Lee, Assa Aravindh Sasikala, Gun Young Jung, Yusin Pak (Nature Communications, 2022)
Abstract The explosive demand for a wide range of data processing has sparked interest towards a new logic gate platform as the existing electronic logic gates face limitations in accurate and fast computing. Accordingly, optoelectronic logic gates (OELGs) using photodiodes are of significant interest due to their broad bandwidth and fast data transmission, but complex configuration, power consumption, and low reliability issues are still inherent in these systems. Herein, we present a novel all-in-one OELG based on the bipolar spectral photoresponse characteristics of a self-powered perovskite photodetector (SPPD) having a back-to-back p + -i-n-p-p + diode structure. Five representative logic gates (“AND”, “OR”, “NAND”, “NOR”, and “NOT”) are demonstrated with only a single SPPD via the photocurrent polarity control. For practical applications, we propose a universal OELG platform of integrated 8 × 8 SPPD pixels, demonstrating the 100% accuracy in five logic gate operations irrelevant to current variation between pixels.

Integration of multiple electronic components on a microfibre towards an emerging electronic textile platform - Sunbin Hwang, Minji Kang, Aram Lee, Sukang Bae, Seoung‐Ki Lee, Sang Hyun Lee, Takhee Lee, Gunuk Wang, Tae‐Wook Kim (Nature Communications, 2022)
Electronic fibres have been considered one of the desired device platforms due to their dimensional compatibility with fabrics by weaving with yarns. However, a precise connecting process between each electronic fibre is essential to configure the desired electronic circuits or systems. Here, we present an integrated electronic fibre platform by fabricating electronic devices onto a one-dimensional microfibre substrate. Electronic components such as transistors, inverters, ring oscillators, and thermocouples are integrated together onto the outer surface of a fibre substrate with precise semiconductor and electrode patterns. Our results show that electronic components can be integrated on a single fibre with reliable operation. We evaluate the electronic properties of the chip on the fibre as a multifunctional electronic textile platform by testing their switching and data processing, as well as sensing or transducing units for detecting optical/thermal signals. The demonstration of th e electronic fibre suggests significant proof of concepts for the realization of high performance with wearable electronic textile systems.

A robust vertical nanoscaffold for recyclable, paintable, and flexible light-emitting devices - Yifan Yao, Yu‐Sheng Chen, Kuidong Wang, Nicholas Turetta, Stefania Vitale, Bin Han, Hanlin Wang, Lei Zhang, Paolo Samorı́ (Science Advances, 2022)
Organic light-emitting devices are key components for emerging optoand nanoelectronics applications including health monitoring and smart displays. Here, we report a foldable inverted polymer light-emitting diode (iPLED) based on a self-suspended asymmetrical vertical nanoscaffold replacing the conventional sandwich-like structured LEDs. Our empty vertical-yet-open nanoscaffold exhibits excellent mechanical robustness, proven by unaltered leakage current when applying 1000 cycles of 40-kilopascal pressure loading/unloading, sonication, and folding, with the corresponding iPLEDs displaying a brightness as high as 2300 candela per square meter. By using photolithography and brush painting, arbitrary emitting patterns can be generated via a noninvasive and mask-free process with individual pixel resolution of 10 μm. Our vertical nanoscaffold iPLED can be supported on flexible polyimide foils and be recycled multiple times by washing and refilling with a different conjugated polymer capabl e of emitting light of different color. This technology combines the traits required for the next generation of high-resolution flexible displays and multifunctional optoelectronics.

Quantum point defects in 2D materials - the QPOD database - Fabian Bertoldo, Sajid Ali, Simone Manti, Kristian S. Thygesen (npj Computational Materials, 2022)
Abstract Atomically thin two-dimensional (2D) materials are ideal host systems for quantum defects as they offer easier characterisation, manipulation and read-out of defect states as compared to bulk defects. Here we introduce the Quantum Point Defect (QPOD) database with more than 1900 defect systems comprising various charge states of 503 intrinsic point defects (vacancies and antisites) in 82 different 2D semiconductors and insulators. The Atomic Simulation Recipes (ASR) workflow framework was used to perform density functional theory (DFT) calculations of defect formation energies, charge transition levels, Fermi level positions, equilibrium defect and carrier concentrations, transition dipole moments, hyperfine coupling, and zero-field splitting. Excited states and photoluminescence spectra were calculated for selected high-spin defects. In this paper we describe the calculations and workflow behind the QPOD database, present an overview of its content, and discuss some general t rends and correlations in the data. We analyse the degree of defect tolerance as well as intrinsic dopability of the host materials and identify promising defects for quantum technological applications. The database is freely available and can be browsed via a web-app interlinked with the Computational 2D Materials Database (C2DB).

Enhancement in structural, morphological, and optical properties of copper oxide for optoelectronic device applications - Shahroz Saleem, Abdullah Hasan Jabbar, Muhammad Hasnain Jameel, Azka Rehman, Zahraa H. Kareem, Ali Hashim Abbas, Zunaira Ghaffar, Saba Abdul Razzaq, Rami Adel Pashameah, Eman Alzahrani, Eng‐Poh Ng, S.M. Sapuan (Nanotechnology Reviews, 2022)
Abstract In this study, copper oxide (CuO) specimens were successfully prepared by the hydrothermal process at altered calcination temperatures; 350, 450, and 550°C. The synthesized samples were analyzed through X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman, Fourier-transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy to analyze the impact of calcination temperature on the structural, morphological, vibration spectra, functional group, and optical properties of CuO for optoelectronic device applications. XRD confirms the pure single-phase monoclinic structure of synthesized samples with no impurity phases and has good crystallinity with the development in calcination temperature. The average crystalline size, lattice constant, and porosity were found in the range of 3.98–5.06 nm; a = 3.4357 Å, b = 3.9902 Å, c = 4.8977 Å – a = 3.0573 Å, b = 3.9573 Å, c = 4.6892 Å; and 3.37–1.03%, respectively. SEM exhibited a variation in morphology by increasing c alcination temperature. Raman spectra revealed that the CuO sample calcinated at 550°C with a stone-like shape having a large grain size of 3.25 μm exhibited that Raman peak intensity and the multiphonon band became stronger and sharper and exhibited higher intensity compared to the samples calcinated at 350 and 450°C. FTIR spectra confirmed that these synthesized specimens exhibited the peaks associated with the typical stretching vibrations of the Cu–O bond between 400 and 500 cm −1 exhibiting the formation of CuO. The energy bandgap was slightly reduced from 1.61 to 1.43 eV with the increase in the calcination temperature. The optical studies revealed that the calcination temperature of 550°C improves the optical properties of CuO by tuning its optical bandgap. The modified structural, morphological, and optical characteristics of the prepared CuO samples make them an appropriate candidate for optoelectronic device applications.

Lanthanide-doped inorganic halide perovskites (CsPbX3): novel properties and emerging applications - Santosh Kachhap, Sachin Singh, Sachin Singh, Sunil Kumar Singh, Sunil Kumar Singh, Sunil Kumar Singh (Journal of Materials Chemistry C, 2022)
Inorganic halide perovskites (IHPs) have provoked intense research efforts because of their superior stability, excellent optoelectronic properties, cost-effectiveness, and striking optoelectronic applications.

The complex optical index of PbS nanocrystal thin films and their use for short wave infrared sensor design - Bilal Chehaibou, Eva Izquierdo, Audrey Chu, Claire Abadie, Mariarosa Cavallo, Adrien Khalili, Tung Huu Dang, Charlie Gréboval, Xiang Xu, Sandrine Ithurria, Grégory Vincent, Bruno Gallas, Gabriel Mugny, Arthur Arnaud, Emmanuel Lhuillier, Christophe Delerue (Nanoscale, 2022)
As nanocrystals (NCs) gain maturity, they become central building blocks for optoelectronics in devices such as solar cells and, more recently, infrared focal plane arrays. Now that the proof of concept of these devices has been established, their optimization requires a deeper understanding of their electronic and optical features to engineer their optoelectronic properties accurately. Though PbS NCs have been extensively investigated, the complex optical index of PbS NC thin films remains mostly unknown. Some previous works have unveiled the optical index for this type of material optimized for solar cells (excitonic peak at 940 nm), but longer wavelengths remain scarce and surface chemistry effects, which are known to be of central importance for layer doping, are simply unexplored. Here, we conduct a systematic investigation of the complex optical index of PbS NC thin films using broadband spectrally resolved ellipsometry. The obtained results are then compared with simulations com bining tight-binding (TB) modeling at the NC level and the Bruggeman model to expand the results to the film scale. While TB calculation gives the NC optical indices, we extract the key NC film parameters such as the NC volume fraction and ligand indices by fitting the Bruggeman formula to ellipsometry measurements. We also bring evidence that this joint modeling method can be conducted without the need for ellipsometry data while preserving the main feature of the experimental results. Finally, the unveiled optical indices are used to model the absorption of short-wave infrared diode stacks based on PbS NCs and are relevant for state-of-the-art devices. Our electromagnetic modeling shows that the absorption within the contact is now a major limitation of the current device operated at the telecom wavelength.

Density functional theory studies of the structural, optoelectronic, bond stiffness and lattice dynamical properties of double perovskite oxides M2YVO6 (M= Mg, Sr): Promising candidates for optoelectronic applications - Muhammad Iqbal Hussain, R.M. Arif Khalil (Materials Science in Semiconductor Processing, 2022)

Experimental and Theoretical Studies on Optical Properties of Tetra(Imidazole) of Palladium (II) Phthalocyanine - A. Timoumi, Davoud Dastan, Bassem Jamoussi, K. Essalah, Omar Alsalmi, N. Bouguila, H. Abassi, Radhouane Chakroun, Zhicheng Shi, Ştefan Ţălu (Molecules, 2022)
In this work, the optical properties of tetra(imidazole) of palladium phthalocyanine (PdPc(Im)4) in solution form and thin films on glass and fluorine-doped tin oxide (FTO) substrates were investigated via the thermal evaporation technique. The optical band gap was evaluated by ultraviolet–visible spectroscopy (UV-Vis). The energy band gap values were determined based on the Tauc graph. In addition, time-dependent density functional theory (TD-DFT) was used to simulate the UV-Vis absorption spectrum of the (PdPc(Im)4) molecule in the Dimethyl Sulfoxide (DMSO) solution phase. A good correlation was found between the DFT results and the experimental optical results. The band gap values between the experimental and DFT-simulated values are presented. The energy band gap of (PdPc(Im)4) obtained from the DFT calculations showed that it can be efficiently regulated. Frontier molecular orbitals and molecular electrostatic potentials were also proposed in this work. The surface study of the la yers deposited on FTO was considered by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the results demonstrated good homogeneity covering the entire surface. The SEM image showed a homogeneous distribution of the grains with some spherical or rod-shaped structures and no agglomeration structures. This work rendered a strategy for regulating the energy band gap and compared the experimental observations obtained with theoretical studies, which provides a fundamental insight into the optical band for optoelectronic and thin-film solar cells.

Future prospects and recent developments of polyvinylidene fluoride (PVDF) piezoelectric polymer; fabrication methods, structure, and electro-mechanical properties - Mohammadpourfazeli S, Arash S, Ansari A, Yang S, Mallick K, Bagherzadeh R. (RSC Advances, 2023)
remote sensors, the structural and biological communities have emphasized scavenging mechanical energy by functional materials, which exhibit piezoelectricity. Piezoelectric materials have received a lot of attention in past decades. Piezoelectric nanogenerators can eﬀectively convert mechanical energy into electrical energy suitable for low-powered electronic devices. Among piezoelectric materials, PVDF and its copolymers have been extensively studied in a diverse range of applications dealing with recent improvements in ﬂexibility, long-term stability, ease of processing, biocompatibility, and piezoelectric

Self-poled piezoelectric polymer composites via melt-state energy implantation - Huang ZX, Li LW, Huang YZ, Rao WX, Jiang HW, Wang J, Zhang HH, He HZ, Qu JP. (Nature Communications, 2023)
may cost more energy than it can harvest14,15. Thus, from the sustainable development viewpoint, fabricating piezoelectric materials without the requirement of electrical-poling attracted attention. Received: 4 July 2023 Accepted: 17 January 2024 Check for updates 1National Engineering Research Center of Novel Equipment for Polymer Processing, Key Laboratory of Polymer Processing Engineering, Ministry of Education, Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, Department of Mechanical and Automotive Engineering, South China University of Technology, 510641 Guangzhou, China. 2These authors contributed equally: Zhao-Xia Huang, Lan-Wei Li.

High-performance piezoelectric nanogenerators based on hierarchical ZnO@CF/PVDF composite film for self-powered meteorological sensor (Journal of Materials Chemistry A, 2023)
A high-performance piezoelectric sensor was fabricated for the real-time monitoring of meteorological wind and rainfall. A vertically aligned zinc oxide nanowires (ZnO NWs)@chopped short carbon ﬁber (CF)/ distributing nail-raked ZnO@CF in a PVDF matrix by a hydrothermal method and a simple spin-coating method. The crystal structure and morphology were characterized. Vertically aligned and uniform arrays of hexagonal ZnO NWs were grown on the CF surface. The eﬀects of the content of incorporated nailraked ZnO@CF on the mechanical and electrical performance of ZnO@CF/PVDF were studied systematically. The maximum tensile strength of the ZnO@CF/PVDF composite ﬁlm reached a value of 77.4 MPa with a content of 4.0 wt% of ZnO@CF. The output voltage and current of a ZnO@CF/PVDF composite ﬁlm PNG also achieved maximum values of 14.91 V and 1.25 mA with a composite of the same ZnO@CF content. The maximum output power of the ZnO@CF/PVDF composite ﬁlm PNG is about 7.9 mW with an external load of 1 0 MU. The ZnO@CF/PVDF composite ﬁlm PNG could charge a capacitor and could instantly drive small electronic devices when the capacitor discharged, and the ZnO@CF/PVDF composite PNG could distinguish wind speed or the falling frequency of water drops. Besides, its excellent washability, durability for over 50 000 cycles and stability after 12 months mean the asprepared ZnO@CF/PVDF composite ﬁlm could possibly be used as a meteorological sensor for the realtime monitoring of meteorological conditions for self-driving automobiles. Chinese Academy of Sciences in 2018. Currently, she is doing postdoctoral research work (2022–2024) at Shanxi Bethune Hospital and she is an assistant Professor in the Micro-Nano System Research Center of focus mainly on exible piezoelectric sensors or nanogenerators, smart piezoelectric ber sensors, carbon

PVDF‐Based Flexible Piezoelectric Tactile Sensors: Review (Crystal Research and Technology, 2023)
Abstract With the advent of the intelligence era, flexible piezoelectric tactile sensors are the key components for sensing information and sending signals. The performance parameters of piezoelectric sensors are closely related to the selection of piezoelectric materials. Compared with conventional piezoelectric materials, polyvinylidene fluoride (PVDF) has significant advantages in flexibility, stretchability, chemical stability, electromechanical conversion, ease of use, and acoustic propagation impedance. As a result, PVDF has become a popular topic of research. This paper introduces the working principle of piezoelectric materials and flexible piezoelectric sensors based on PVDF materials and details the research progress of different materials based on PVDF for the preparation of flexible piezoelectric tactile sensors, such as: PVDF and its copolymers for the preparation of flexible piezoelectric sensors and PVDF doped with other functional materials for the preparation of flexib le piezoelectric sensors. In this paper, the advantages and disadvantages of different materials and the development prospects of PVDF flexible piezoelectric sensors are summarized to provide some insights for high‐performance flexible PVDF piezoelectric sensors.

Development of high-sensitive piezoelectric nanogenerators of all-organic PVDF multilayer nanofibrous membrane with innovative 3D structure via electrohydrodynamic processes (Journal of Polymer Research, 2023)
Poly(vinylidene fluoride) (PVDF) electrospun nanofibrous membranes (NFMs) have good piezoelectric properties compared to other polymer materials due to their electroactive phase. However, there is a limit to the content of the electroactive phase (FEA) in PVDF, which restricts the further improvement of PVDF NFMs' piezoelectric properties. This research prepared PVDF multilayer nanofibrous membranes (MNFMs) with a novel 3D structure by assembling electrospun PVDF nanofibers and electrospraying PVDF microspheres. The various properties of PVDF microspheres and PVDF MNFMs, including their crystalline structure, morphology, and piezoelectric properties, were discussed in detail. The addition of PVDF microspheres to PVDF NFMs hardly changed the FEA in PVDF MNFMs. However, the piezoelectric properties of PVDF MNFMs significantly increased compared to those of PVDF NFMs. PVDF MNFMs demonstrate good piezoelectric sensitivity and can detect the stress force as small as 0.25 N and finger tappin g. The maximum output voltage of PVDF MNFMs was 112 mV, achieved when applying a force of 0.25 N at a frequency of 110 Hz. This value is three times higher than that of PVDF NFMs.

Optimizing Piezoelectric Coefficient in PVDF Fibers: Key Strategies for Energy Harvesting and Smart Textiles - Sunija Sukumaran, Piotr K. Szewczyk, Joanna Knapczyk‐Korczak, Urszula Stachewicz (Advanced Electronic Materials, 2023)
Abstract With the advancement in smart electronic devices and self‐powered devices, the demand for piezoelectric polymers has found potential research interest. Among these, electrospun polyvinylidene fluoride (PVDF) fibers have gained attention for energy harvesting due to their flexibility and higher piezoelectric coefficient. In the current work, various methods are compared to enhance PVDF's piezoelectric properties, including different solvents (DMAc, DMF), conductive filler (rGO), and annealing as post‐treatment. The results indicate that PVDF/rGO fibers in DMAc solvent exhibit the highest β phase fraction and crystallinity. Moreover, for the first time, the piezoelectric properties of PVDF/rGO electrospun single fiber is presented using high voltage switching spectroscopy piezoelectric force microscopy (HVSS‐PFM). The highest piezoelectric coefficient (d 33 ) is measured for PVDF/DMAc‐rGO composite fibers. Notably, PVDF/rGO in DMAc solvent significantly improves the piezoelectri c coefficient, leading to a remarkable fourfold increase in power density compared to pure PVDF, making it a promising material for energy harvesting applications.

Highly sensitive self-powered piezoelectric poly(vinylidene fluoride)-based nanofibrous mat containing microporous metal–organic framework nanostructures for energy harvesting applications (Applied Physics A, 2023)
Developing highly sensitive flexible piezoelectric sensor for wearable electronic devices have received considerable attention due to their promising application in physiological monitoring. Therefore, many research studies are conducted to enhance the piezoelectric response of poly(vinylidene fluoride) (PVDF)-based membrane. In this work, we present a novel flexible piezoelectric PVDF-based sensor with high-pressure sensitivity induced by the incorporation of microporous metal-organic framework (MOF) particles. Scanning electron microscopy images indicated the formation of uniform and bead-free PVDF/MOF nanofibrous composite with an average diameter of 173-241 nm. In this design, the microporous MOF crystals extremely enhanced the polar beta-phase content of PVDF nanofibers by 20% without significant loss in its flexibility and synergistically promoted the piezoelectric performance of PVDF-based sensor. The PVDF nanofibers containing 1 wt% MOF crystals showed a peak-to-peak voltage of 3.84 V under an applied force of 2.5 N, which was superior to that of pristine PVDF nanofibers by 32%. Furthermore, the practical application of the developed PVDF/MOF nanofiber-based piezoelectric sensor was demonstrated for detecting human activities, showing a maximum output voltage of 2.08 V (for finger tapping), 5.92 V (for hand punching), and 20.66 V (for heel strike). The self-powered and highly sensitive PVDF/MOF nanofiber-based piezoelectric sensor also exhibits excellent long-term working stability with no obvious responsivity attenuation. The results of this work provide new insights for the development of next-generation piezoelectric sensors and energy harvesting systems.Graphical abstractA novel flexible piezoelectric PVDF-based nanogenerator with high-pressure sensitivity induced by the incorporation of microporous MOF particles. The piezoelectric response of the developed PVDF/MOF nanogenerator indicated superior output voltage and sensitivity than most of the reported PVDF-based nanogenerators.

Review of Piezoelectric Properties and Power Output of PVDF and Copolymer-Based Piezoelectric Nanogenerators - Bhadwal N, Ben Mrad R, Behdinan K. (Nanomaterials, 2023)
The highest energy conversion efﬁciencies are typically shown by lead-containing piezoelectric materials, but the harmful environmental impacts of lead and its toxicity limit future use. At the bulk scale, lead-based piezoelectric materials have signiﬁcantly higher piezoelectric properties when compared to lead-free piezoelectric materials. However, at the nanoscale, the piezoelectric properties of lead-free piezoelectric material can be signiﬁcantly larger than the bulk scale. The piezoelectric properties of Poly(vinylidene ﬂuoride) (PVDF) and Poly(vinylidene ﬂuoride-co-triﬂuoroethylene) (PVDF-TrFE) lead-free piezoelectric nanomaterials are reviewed and their suitability for use in piezoelectric nanogenerators (PENGs) is determined. The impact of different PVDF/PVDF-TrFE composite structures on power output is explained. Strategies to improve the power output are given. Overall, this review ﬁnds that PVDF/PVDF-TrFE can have signiﬁcantly increased piezoelectric properties at the nanosc ale. However, these values are still lower than lead-free ceramics at the nanoscale. If the sole goal in developing a lead-free PENG is to maximize output power, lead-free ceramics at the nanoscale should be considered. However, lead-free ceramics are brittle, and thus encapsulation of lead-free ceramics in PVDF is a way to increase the ﬂexibility of these PENGs. PVDF/PVDF-TrFE offers the advantage of being nontoxic and biocompatible, which is useful for many applications.

Defected poly(vinylidene fluoride) with enhanced piezoelectricity via liquid crystal small molecules doping (Applied Physics Letters, 2023)
A poly(vinylidene fluoride)-based composite film with higher piezoelectric properties was prepared by the solvent mixing method of adding liquid crystal small molecules to create defects among polyvinylidene fluoride (PVDF) molecular chains. The composite obtained by simple uniaxial stretching and thermal polarization exhibits higher piezoelectric properties (d33 = 29.0 pC/N) than neat PVDF (d33 = 24.3 pC/N). The defects reduce the grain size of PVDF to some extent, thus reducing the coercivity field of PVDF from 64.6 to 58.1 MV/m. This strategy could endow PVDF with higher piezoelectric coefficient and lower polarization field, which is attractive for piezoelectric applications.

Nonlinear-optical piezoelectric electrospun nanofibers (Materials Research Bulletin, 2023)
This paper presents a nonlinear optical piezoelectric electrospun nanocomposite of polyvinylidene fluoride (PVDF) nanofibers with embedded nanomaterial of poly {1-[p-(3'-carboxy-4'- hydroxyphenylazo) benzenesulfonamido]-1, 2-ethandiyl} (PCBS). PCBS of different weight ratios are added in-situ to the synthesized PVDF nanofibers. The generated nanofibers mats have been proved to possess both properties of piezoelectric response and nonlinear optical conversion due to the presence of both PVDF and PCBS, respectively. Innovatively, embedding PCBS within the PVDF nanofibers increases the piezoelectric response of the nanocomposite, compared to the case of neat PVDF nanofibers, at certain optimum weight concentrations of PCBS. This has been proved by different piezoelectric measurements at different applied forces and vibration frequencies, along with d33 coefficient measurements and supported by FTIR analysis of beta-sheets. Our results support the evidence of the coupling between the polar ized diploes of PCBS and PVDF, which can enhance the overall piezoelectric response. Furthermore, the synthesized nanocomposite shows an optical second harmonic generation (SHG) at optimum concentration of added PCBS within the PVDF nanofibers of around 1 wt.%. The synthesized nonlinear optical nanocomposite of PVDF/PCBS can be multi-functionalized sensors/transducer membranes for biomedical and sensing applications.

Large-scale fabrication and performance improvement of polyvinylidene fluoride piezoelectric composite films (Ceramics International, 2023)
Sensing applications such as wearable electronics, electronic skin, and soft robotics using flexible piezoelectric films have received extensive attention. In this study, we fabricate large-scale 0-3 type composite films of pol-yvinylidene fluoride (PVDF)-doped modified lead zirconate titanate (PZT) particles (PZT@UP) through an extrusion-casting process to enhance piezoelectric properties and explain the piezoelectric performance mech-anism. The introduction of PZT@UP particles improved the dielectric permittivity of the composite films and promoted the polarization of PVDF, which positively affected the piezoelectric properties of PVDF/PZT@UP films. The composite film with 25 wt% PZT@UP possessed an excellent piezoelectric coefficient (d33) of 29 pC/N, which was 93% higher than that of neat PVDF (15 pC/N). Moreover, the addition of PZT@UP particles effec-tively inhibited the movement of PVDF molecular chains and improved the mechanical modulus stability of the composite films. The la w of electrostrictive effect of the PVDF/PZT@UP composite films is clarified from the aspects of the movement of PVDF molecular chains, the principle of electric field distribution, and the con-struction of the internal electric field. Further, the similarities and differences between the piezoelectric and electrostrictive mechanisms of the PVDF/PZT@UP composite films are summarized. The extrusion-casting process combined with modified fillers shows promising potential in improving wear and tear of and elec-tricity generation from PVDF-based composite films, leading to a profound impact on the development of large-scale fabrication of piezoelectric sensors.

Enhanced piezoelectric nanogenerator made of electrospun PVDF and P(VDF-TrFE) nanowebs with the addition of TrFE comonomers (Journal of Materials Science Materials in Electronics, 2023)
Poly(vinylidene fluoride) (PVDF), a representative piezoelectric and ferroelectric polymer has been widely used as a nanogenerator for piezoelectric energy harvesting and as a sensor. Although the alpha-phase is generally dominant in PVDF, it has poor piezoelectric property. To improve the piezoelectric performance of PVDF, the alpha-phase was converted into the beta-phase through stretching using electrospinning. In addition, it exhibited higher piezoelectric performance when a comonomer is added to PVDF, like a PVDF-based copolymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)). Accordingly, the effect of the comonomer TrFE on the beta-phase conformation and piezoelectric performance was investigated in a nanogenerator that prepared a nanoweb with similar fiber diameters by electrospinning PVDF and P(VDF-TrFE). The microstructure of the nanoweb was investigated using scanning electron microscopy (SEM), and the crystal phase change was confirmed using an X-ray diffractio n (XRD) and Fourier transform-infrared spectroscopy (FT-IR). It was confirmed that the presence of TrFE changed the interaction between atoms and formed a significant amount of beta-phase, reaching the maximum beta-phase at P(VDF-TrFE) 70/30. Piezoelectric tests showed excellent electrical characteristics of 8 V and 2.29 mu W.

Effects of Porosity on Piezoelectric Characteristics of Polyvinylidene Fluoride Films for Biomedical Applications - Kloster JT, Danley MJ, Lai VK, Zhao P. (BME Frontiers, 2023)
simple to produce [10]. PVDF also has applications in the biomedical industry as a flow sensor for measuring the flow rate of blood in the portal vein during liver transplant surgery [11]. Patients who suffer from liver cirrhosis often develop portosystemic shunts that divert blood flow away from the portal vein due to hypertension in the liver. Upon receiving a new liver, this reduced blood flow may lead to continued liver damage. Alternatively, if the patient receives a partial liver, an overflow of blood can similarly cause damage. Therefore, it is crucial to monitor and control the flow of blood through the portal

Effect of chemical defects on electrostriction-enhanced piezoelectric property of poly(vinylidene fluoride) via high-power ultrasonication - Rui, Guanchun; Allahyarov, Elshad; Zhang, Honghu; Li, Ruipeng; Zhang, Shihai; Taylor, Philip L.; Zhu, Lei (NANO ENERGY, 2023)
Among all ferroelectric polymers, poly(vinylidene fluoride) (PVDF)-based polymers exhibit the best piezoelectric properties and thus are promising for sensors, actuators, and energy harvesters in flexible/wearable electronics and soft robotics. Despite decades of research effort, the structure-property relationship is still unclear for ferroelectric polymers, and their piezoelectric performance is often limited to similar to 30 pC/N. In this study, we report the effects of chemical defects [i.e., the head-to-head and tail-to-tail (HHTT) sequence] and high-power ultrasonication on the piezoelectric performance of PVDF. Two PVDF homopolymers with different HHTT contents were studied. The PVDF with a lower HHTT content (4.3 %) exhibited a higher melting temperature (T-m, denoted as HMT), whereas that with a higher HHTT content (5.9 %) exhibited a lower T-m (denoted as LMT). In addition to the primary crystals (PCs) and the isotropic amorphous fraction, wide-angle X-ray diffraction also su ggested the presence of the oriented amorphous fraction (OAF) and secondary crystals (SCs), which are important in enhancing the piezoelectricity for PVDF. Intriguingly, the LMT PVDF exhibited higher piezoelectric performance than the HMT PVDF, because it had a higher OAF/SC content. In addition, high-power ultrasonication was shown to effectively break relaxor-like SCs off from the PCs, further enhancing the piezoelectric performance. That is, the inverse piezoelectric coefficient d(31) reached as high as 76.2 pm/V at 65 degrees C for the ultrasonicated LMT PVDF. The insight from this study will enable us to design better piezoelectric PVDF polymers for practical electromechanical applications.

Enhanced piezoelectric response using TiO2/MoS2 heterostructure nanofillers in PVDF based nanogenerators - Bhatt, Abhinav; Singh, Vishal; Bamola, Priyanka; Aswal, Deepali; Rawat, Saurabh; Rana, Shilpa; Dwivedi, Charu; Singh, Bharti; Sharma, Himani (JOURNAL OF ALLOYS AND COMPOUNDS, 2023)
Polymers like Polyvinylidene fluoride (PVDF) having intrinsic piezoelectric property have been used in fabrication of piezoelectric nanogenerators (PNG) to harness electrical energy at nanoscale level. With advancements, Transition metal dichalcogenides (TMDC) and its composites as nanofillers have been re-ported to enhance the piezoelectric response of PVDF. In context to this, present work includes enhancing the piezoelectric response of PVDF based thin flexible nanogenerators, with 2D MoS2/1D TiO2 hetero-structure as nanofillers. Further, the piezoelectric responses of different (MoS2/TiO2 heterostructure based PVDF, MoS2/PVDF and TiO2/PVDF) nanogenerators is carried out and compared with pristine PVDF nano -generator. It was found that 2D MoS2/1D TiO2 heterostructure based nanogenerators have proven to be the best among other nanogenerators due to enhancement of & beta; phase in PVDF matrix. The FTIR spectroscopy evidently revealed the & beta; phase content in PVDF matrix enhances after incorporation of these nanofillers. Amongst all these fabricated nanogenerators the enhancement in & beta; phase content of the synthesized 2D MoS2/1D TiO2 heterostructure based nanogenerators was highest-71 %. Also, MoS2/TiO2 heterostructure based PVDF nanogenerator generated the maximum peak to peak open circuit voltage (PpOV)-17.4 V, short circuit current (ScC)-0.54 & mu;A and an instantaneous power density of 55.6 & mu;W/cm2.& COPY; 2023 Elsevier B.V. All rights reserved.

Simulation Guided Coaxial Electrospinning of Polyvinylidene Fluoride Hollow Fibers with Tailored Piezoelectric Performance - Shao, Zhuzhu; Zhang, Xuan; Song, Zihan; Liu, Jingfeng; Liu, Xingang; Zhang, Chuhong (SMALL, 2023)
Electrospun polyvinylidene fluoride (PVDF) piezoelectric fibers have high potential applicability in mechanical energy harvesting and self-powered sensing owing to their high electromechanical coupling capabilities. Strategies for tailoring fiber morphology have been the primary focus for realizing enhanced piezoelectric output. However, the relationship between piezoelectric performance and fiber structure remains unclear. This study fabricates PVDF hollow fibers through coaxial electrospinning, whose wall thickness can be tuned by changing the internal solution concentration. Simulation analysis demonstrates an increased effective deformation of the hollow fiber as enlarging inner diameter, resulting in enhanced piezoelectric output, which is in excellent agreement with the experimental results. This study is the first to unravel the influence mechanism of morphology regulation of a PVDF hollow fiber on its piezoelectric performance from both simulation and experimental aspects. The optimal PVDF hollow fiber piezoelectric energy harvester (PEH) delivers a piezoelectric output voltage of 32.6 V, approximate to 3 times that of the solid PVDF fiber PEH. Furthermore, the electrical output of hollow fiber PEH can be stably stored in secondary energy storage systems to power microelectronics. This study highlights an efficient approach for reconciling the simulation and tailoring the fiber PEH morphology for enhanced performances for future self-powered systems.

Enhanced Piezoelectric Properties of Poly(Vinylidene Fluoride)/Lead Zirconate Titanate (PVDF/PZT) Fiber Films Fabricated by Electrospinning - ["Yuan, ChongXiao", "Zhang, Chao", "Yang, Cheng", "Wu, Fuling", "Xiao, Shibing", "Sun, Huajun"] (JOURNAL OF ELECTRONIC MATERIALS, 2023)
Flexible wearable sensing devices are in great demand for self-powered systems. In this study, we fabricated fiber films of poly(vinylidene fluoride) (PVDF) matrix embedded with modified lead zirconate titanate nanoparticles (PZT NPs) using the electrospinning process. Each fiber film was cut into small pieces of 2 x 2 cm(2), and pairs of pieces were pressed with a hot-pressing method. Modified PZT NPs with a high piezoelectric coefficient were embedded in PVDF fibers as a piezoelectric-reinforcing phase, which promoted the formation of the polar & beta; phase in PVDF. The embedded PZT NPs affected the distribution of the polarized electric field and formed a local electric field between two PZT NPs, which promoted the polarization of PVDF, thereby enhancing the piezoelectric properties of PVDF/PZT NPs fiber films. The piezoelectric coefficient (d(33)) of the PVDF/PZT NPs fiber films embedding 4 wt.% PZT NPs showed the most significant enhancement, from 12 pC/N for neat PVDF to 21 pC/N , which is an approximately 75% improvement. The results of this work demonstrate the great potential application of piezoelectric composite fiber films in flexible wearable sensing devices.

Enhanced neuronal differentiation by dynamic piezoelectric stimulation - Pinho, Tiffany S.; Silva, Deolinda; Ribeiro, Jorge Cibrao; Marote, Ana; Lima, Rui; Batista, Salete J.; Melo, Rita; Ribeiro, Clarisse; Cunha, Cristiana B.; Moreira, Irina S.; Lanceros-Mendez, Senentxu; Salgado, Antonio J. (JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A, 2023)
Electroactive smart materials play an important role for tissue regenerative applications. Poly(vinylidene fluoride) (PVDF) is a specific subtype of piezoelectric electroactive material that generates electrical potential upon mechanical stimulation. This work focuses on the application of piezoelectric PVDF films for neural differentiation. Human neural precursor cells (hNPCs) are cultured on piezoelectric poled and non-poled beta-PVDF films with or without a pre-coating step of poly-d-lysine and laminin (PDL/L). Subsequently, hNPCs differentiation into the neuronal lineage is assessed (MAP2(+) and DCX+) under static or dynamic (piezoelectric stimulation) culture conditions. The results demonstrate that poled and coated beta-PVDF films induce neuronal differentiation under static culture conditions which is further enhanced with mechanical stimulation. In silico calculations of the electrostatic potential of different domains of laminin, highlight the high polarity of those domains, w hich shows a clear preference to interact with the varying surface electric field of the piezoelectric material under mechanical stimulation. These interactions might explain the higher neuronal differentiation induced by poled beta-PVDF films pre-coated with PDL/L under dynamic conditions. Our results suggest that electromechanical stimuli, such as the ones induced by piezoelectric beta-PVDF films, are suitable to promote neuronal differentiation and hold great promise for the development of neuroregenerative therapies.

Electrospun PVDF-based piezoelectric nanofibers: materials, structures, and applications - Zhang M, Liu C, Li B, Shen Y, Wang H, Ji K, Mao X, Wei L, Sun R, Zhou F. (Fibers, 2023)
Polyvinylidene ﬂuoride (PVDF) has been considered as a promising piezoelectric material for advanced sensing and energy storage systems because of its high dielectric constant and good electroactive response. Electrospinning is a straightforward, low cost, and scalable technology that can be used to create PVDFbased nanoﬁbers with outstanding piezoelectric characteristics. Herein, we summarize the state-of-the-art progress on the use of ﬁller doping and structural design to enhance the output performance of electrospun PVDF-based piezoelectric ﬁber ﬁlms. We divide the ﬁllers into single ﬁller and double ﬁllers and make comments on the eﬀects of various dopant materials on the performance and the underlying

High efficiently degradation of organic pollutants via low-speed water flow activation of Cu2O@MoS2/PVDF modified pipeline with piezocatalysis performance - Wang, Jingxue; Liang, Yanting; Wang, Zichen; Huo, Bingjie; Liu, Chao; Chen, Xiaxia; Xu, Hongwei; Li, Dongmei; Zhu, Zhaoyou; Wang, Yinglong; Meng, Fanqing (CHEMICAL ENGINEERING JOURNAL, 2023)
Using water flow energy in the environment for water treatment is a feasible solution to alleviate energy shortages and environmental pollution. This work prepared a Cu2O@MoS2/PVDF modified pipeline with superior piezoelectric properties for norfloxacin (NOR) degradation. The piezoelectric coefficient d(33) of Cu2O@MoS2/PVDF increased by 27.7 % compared with PVDF. The piezoelectric current response test demonstrated that Cu2O@MoS2/PVDF had a higher current response than PVDF. FTIR showed that the presence of Cu2O@MoS2 significantly increased the piezoelectric beta-phase content of PVDF. The Cu2O@MoS2/PVDF pipeline exhibited the best degradation efficiency of 99.3 % within 40 min when the flow rate reached 1.389 L min(-1). center dot O-2(-) and (OH)-O-center dot have been shown to play an important role in NOR degradation and the possible degradation mechanism and pathways of NOR were proposed. This work provides a promising method for the efficient and green treatment of organic pollut ants in water by using water flow energy and has practical application significance.

Development of highly flexible PVDF-TiO2 nanocomposites for piezoelectric nanogenerator applications - Kulkarni, Nikhil Dilip; Kumari, Poonam (MATERIALS RESEARCH BULLETIN, 2023)
Polyvinylidene fluoride (PVDF) thin films have a wide prospect in energy harvesting applications due to flexible design and presence of electroactive phase. Despite massive work in this domain, commercial applications are very rare since PVDF based thin films have low piezoresponse. In this paper, the piezoelectric output voltage of the PVDF films is further enhanced by loading Titanium dioxide (TiO2) nanofillers into the viscous PVDF solution using solvent casting approach. Tensile strength, elastic modulus, and storage modulus of PVDF-TiO2 nano -composite films showed significant enhancement compared to pure PVDF. PVDF-TiO2 films showed about 143% increment in dielectric constant (e) and 214% increment in AC conductivity (sigma ac) than pure PVDF. PVDF-TiO2 films showed significant increment in remnant polarization (Pr) values which is indicating enhanced piezo-electric performance. The piezoelectric output voltage of TiO2 reinforced nanocomposite films also showed significant improv ement.

Flexible piezoelectric PVDF/TPU nanofibrous membranes produced by solution blow spinning - Le, Bao; Omran, Nada; Hassanin, Ahmed H.; Kandas, Ishac; Gamal, Mohammed; Shehata, Nader; Shyha, Islam (JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, 2023)
Poly (vinylidene fluoride) (PVDF) nanofibers have been applied in producing piezoelectric membranes for energy harvesting in wearable devices under strenuous service conditions due to its outstanding properties such as piezoelectricity, flexibility, stability, and biocompatibility. Therefore, a processing technique with mass production capability and generating the highest possible piezoelectric properties of PVDF nanofibers is required. To achieve such requirements, this study presented a novel flexible piezoelectric membrane based on PVDF/TPU nanofibers using solution blow spinning (SBS). The addition of TPU into PVDF has been proven to increase the flexibility of the polymeric membranes. The pro-duced membranes showed high piezoelectric response and sensitivity compared to other PVDF-based membranes in the literature especially at 5wt.% TPU concentration, owing to its small nanofiber diameter, high b fraction, and inducing reorientation of electric dipoles. The addition of TPU also significantly enhanced tensile strength and elasticity of the produced membranes. Based on those, this work has shown a promising method to pro-duce high elastic-piezoelectric nanofibrous membrane using SBS.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Electrospinning behavior and piezoelectric property of PVDF/PEDOT:PSS composite web by PEDOT:PSS addition - Lim, Jihwan; Choi, Sejin; Kim, Han Seong (POLYMERS FOR ADVANCED TECHNOLOGIES, 2023)
Poly(vinylidene fluoride) (PVDF) is a representative piezoelectric polymer with a high piezoelectric constant, which has been applied and studied in various fields because of its flexibility. PVDF has various crystallization phases, and the crystallization phase of the fabricated fibers is significantly influenced by the solution characteristics and additives during the electrospinning process. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a conductive polymer that can improve piezoelectric performance by acting as an electron path when combined with a piezoelectric polymer; however, the electrospinning behavior depends on the solution properties. The characteristics of composite solutions with PEDOT:PSS added to PVDF were investigated, and the changes in electrospinning behavior and morphology were analyzed accordingly. We also evaluated the crystallinity of the PVDF in the deposited fibers using Fourier-transform infrared (FTIR) spectroscopy and X-ray diffract ion (XRD) analysis. As the PEDOT:PSS content increased, the radius of the jet decreased, the deposition area decreased, the fiber diameter tended to increase, and the crystallinity of the beta phase decreased. Changes in the piezoelectric performance of the PVDF/PEDOT composite webs with various PEDOT:PSS contents were investigated and analyzed. Based on the results of this study, ceramic-based materials can be replaced with improved polymer-based piezoelectric elements, thus accelerating the adoption of wearable piezoelectric devices.

Power enhancement of piezoelectric energy harvester using ZnOnf-PDMS composite with PVDF filler - Khatun, Hiramoni; Pamu, Dobbidi; Balmuchu, Shashi Priya; Singh, Ningthoujam Somorjit; Sarma, Utpal (SENSORS AND ACTUATORS A-PHYSICAL, 2023)
This work aims to fabricate a piezoelectric energy harvester using Polydimethylsiloxane (PDMS) with Zinc Oxide nanoflower (ZnOnf) and Poly(vinylidene fluoride) (PVDF). ZnOnf is synthesised via the hydrothermal method by varying the reaction time. The long nanoflowers resulting from the reaction time of 2 h are utilized to prepare the piezoelectric composite. Two energy harvesters are fabricated: ZnOnf-PDMS (ZP) and ZnOnf-PVDF-PDMS (ZPP), to harvest mechanical energy. The incorporation of PVDF into the ZnOnf-PDMS composite enhances the active polar beta-phase of PVDF, leading to improved piezoelectric activity. The output voltage of the piezoelectric harvesters is measured under various impact forces applied using a self-designed impact force setup. The addition of PVDF to the ZnOnf-PDMS composite results in an increase in the dielectric constant and, consequently, in the energy harvester's output. Thus, at an applied impact force of 2.64 N, the output power harvested is 11.4 mu W for Z P, and is amplified to 14.27 mu W for ZPP. Furthermore, the incorporation of PVDF enhances the thermal stability and delays the decomposition temperature of the energy harvester.

Flexible Self-Powered Friction Piezoelectric Sensor Based on Structured PVDF-Based Composite Nanofiber Membranes - Zhang, Mengdi; Tan, Zifang; Zhang, Qingling; Shen, Yutong; Mao, Xue; Wei, Liang; Sun, Runjun; Zhou, Fenglei; Liu, Chengkun (ACS APPLIED MATERIALS & INTERFACES, 2023)
Withthe rapid development of the economy and technology, intelligentwearable devices have gradually entered public life. Flexible sensors,as the main component of wearable devices, have been widely concerned.However, traditional flexible sensors need an external power supply,lacking flexibility and sustainable power supply. In this study, structuredpoly(vinylidene fluoride) (PVDF)-based composite nanofiber membranesdoped with different mass fractions of MXene and zinc oxide (ZnO)were prepared by electrospinning and were then assembled to flexibleself-powered friction piezoelectric sensors. The addition of MXeneand ZnO endowed PVDF nanofiber membranes with better piezoelectricproperties. The structured PVDF/MXene-PVDF/ZnO (PM/PZ) nanofiber membraneswith a double-layer structure, interpenetrating structure, or core-shellstructure could further enhance the piezoelectric properties of PVDF-basednanofiber membranes through the synergistic effects of filler dopingand structural design. In pa rticular, the output voltage of the self-poweredfriction piezoelectric sensor made of a core-shell PM/PZ nanofibermembrane showed a good linear relationship with the applied pressureand could produce a good piezoelectric response to the bending deformationcaused by human motion.

Clamping of ferroelectric PVDF to enhance the electromechanical performance of a 1-3 PMN-PT/PVDF piezoelectric composite - Xia, Weimin; Pan, Hong; Zhang, Huihui; Wang, Rong; Xing, Junhong; Zhang, Xiaofang; Zhang, Zhicheng (CERAMICS INTERNATIONAL, 2023)
A group of 1-3 type piezoelectric Pb (Mg1/3Nb2/3)O3-PbTiO3/polyvinylidene fluoride (PMN-PT/PVDF) composite sheets are prepared using a complex two-step hot-pressing method. Then the molecular structure model of piezoelectric materials and an inverse piezoelectric simulation of the composites are performed to express the horizontal compression, indicating the clamping activity of ferroelectric PVDF on PMN-PT. As such, this com-posite sheet possesses a high dielectric permittivity (epsilon r) of 560 at 100 Hz for its compacted connecting of two phases. After polarization, a very large piezoelectric coefficient (d33) of 1125 pC/N and a considerable electromechanical coupling factor (kt) of 0.43 is obtained in PMN-PT/PVDF sheet with a proper aspect ratio of 1.4 and a thickness of 2.1 mm, further indicating that promoting effect of PVDF matrix on the strain in Z-direction of PMN-PT. The result shows that ferroelectric PVDF serving as polymer matrix favors the electromechanical coupling effe ct, and may provide a prospect of the potential application of PMN-PT/PVDF composite in sensor or transistor for matrix ultrasonic probes.

Regulation of TiO2 @PVDF piezoelectric nanofiber membranes on osteogenic differentiation of mesenchymal stem cells - Liu, Jing; Cheng, Yaya; Wang, Haoyu; Yang, Dingyi; Liu, Cunshun; Dou, Weixin; Jiang, Xue; Deng, Hongzhang; Yang, Rusen (NANO ENERGY, 2023)
Bioactive piezoelectric materials with similar properties as natural bone tissue with piezoelectricity have been explored for bone repair. Polyvinylidene fluoride (PVDF) is among the most studied piezoelectric polymers and has been manifested to promote osteogenic differentiation. Unfortunately, in the practical application of bone repair, bioactive materials as implants have faced poor electrical signal stability and poor modulation of bone regeneration, which have seriously hindered their further development. Here, we fabricated a composite piezoelectric fibrous membrane with titanium dioxide (TiO2) nanoparticles and PVDF (TiO2 @PVDF) for cellular osteogenic differentiation. The expression quantity of the gene osteocalcin (OCN) with the piezoelectric fibrous membrane was 49 times and 6 times higher than the expression quantity of OCN with the control group and with the pure polyvinylidene fluoride (PVDF), respectively. Moreover, the membrane with 0.3 wt% TiO2 (P-0.3TN) generated high surface potential and significantly promoted cell adhesion and proliferation through electromechanical stimulation early in osteogenic differentiation. Alkaline phosphatase (ALP) activity was increased up to 2-fold by stimulation of electrical and mechanical signals through piezoelectric fibers, effectively inducing osteogenic differentiation at the early stage. The proposed mechanism of regulating osteogenic differentiation behavior by the surface potential of TiO2 @PVDF piezoelectric fiber composite membrane provides guidance for designing electroactive materials to promote osteogenic differentiation and bone regeneration and remodeling.

Recent Progress on Structure Manipulation of Poly(vinylidene fluoride)-Based Ferroelectric Polymers for Enhanced Piezoelectricity and Applications - Zhang, Liwei; Li, Shuangfeng; Zhu, Zhiwen; Rui, Guanchun; Du, Bin; Chen, Dazhu; Huang, Yan-Fei; Zhu, Lei (ADVANCED FUNCTIONAL MATERIALS, 2023)
Poly(vinylidene fluoride) (PVDF)-based polymers demonstrate great potential for applications in flexible and wearable electronics but show low piezoelectric coefficients (e.g., -d(33) < 30 pC N-1). The effective improvement for the piezoelectricity of PVDF is achieved by manipulating its semicrystalline structures. However, there is still a debate about which component is the primary contributor to piezoelectricity. Therefore, current methods to improve the piezoelectricity of PVDF can be classified into modulations of the amorphous phase, the crystalline region, and the crystalline-amorphous interface. Here, the basic principles and measurements of piezoelectric coefficients for soft polymers are first discussed. Then, three different categories of structural modulations are reviewed. In each category, the physical understanding and strategies to improve the piezoelectric performance of PVDF are discussed. In particular, the crucial role of the oriented amorphous fraction at the cryst alline-amorphous interface in determining the piezoelectricity of PVDF is emphasized. At last, the future development of high performance piezoelectric polymers is outlooked.

Interface-engineered composite nanofibers for boosting piezoelectric outputs of polymeric nanogenerators - Lian, Wangwei; Zhang, Mengxia; Wang, Jie; Wu, Chenchen; Lamnawar, Khalid; Maazouz, Abderrahim; Lu, Bo; Dong, Binbin; Liu, Chuntai (MATERIALS LETTERS, 2023)
Polymeric piezoelectric nanogenerators (PENGs) hold great promise for flexible energy harvesters and selfpowered sensors. However, achieving high piezoelectricity in inherently piezoelectric polymers while maintaining their flexibility remains a challenge. Herein, we propose a simple yet effective approach to fabricate flexible and cost-effective PENGs based on interface-engineered composite nanofibers of poly(vinylidene fluoride) (PVDF)/carbon nanotubes (CNTs) using electrospinning. Our strategy involves the incorporation of a tailormade interfacial coupling agent, maleic anhydride grafted PVDF (PVDF-g-MA), onto PVDF/CNTs interfaces. This mild interface-engineering strategy not only promotes interfacial interactions within composites but also stabilizes electrospinning flow jets, yielding defect-free nanofibers. More importantly, the interfacial anchoring of PVDF-g-MA molecules promotes the preferential crystallization of electroactive & beta;-phase within PVDF matrix. By incorporatin g a small quantity of PVDF-g-MA (up to 1.0 wt%), our approach significantly enhances piezoelectric outputs while preserving flexibility. This eliminates the need for excessive nanofiller usage that can sacrifice the flexibility associated with conventional methods. Remarkably, the resulting composite nanofiber-based PENGs exhibit excellent piezoelectric performance, generating high output voltages (10.6 V) and remarkable power density (3.15 & mu;W/cm2) under tiny force stimuli. Our findings open new avenues for efficient and scalable fabrication of polymeric piezoelectric nanogenerators for flexible and wearable energy harvesting and selfpowered sensing applications.

Boosting Piezoelectricity by 3D Printing PVDF-MoS2 Composite as a Conformal and High-Sensitivity Piezoelectric Sensor - Islam, Md. Nurul; Rupom, Rifat Hasan; Adhikari, Pashupati R.; Demchuk, Zoriana; Popov, Ivan; Sokolov, Alexei P.; Wu, H. Felix; Advincula, Rigoberto C.; Dahotre, Narendra; Jiang, Yijie; Choi, Wonbong (ADVANCED FUNCTIONAL MATERIALS, 2023)
Additively manufactured flexible and high-performance piezoelectric devices are highly desirable for sensing and energy harvesting of 3D conformal structures. Herein, the study reports a significantly enhanced piezoelectricity in polyvinylidene fluoride (PVDF) achieved through the in situ dipole alignment of PVDF within PVDF-2D molybdenum disulfide (2D MoS2) composite by 3D printing. The shear stress-induced dipole poling of PVDF and 2D MoS2 alignment are harnessed during 3D printing to boost piezoelectricity without requiring a post-poling process. The results show a remarkable, more than the eight-fold increment in the piezoelectric coefficient (d(33)) for 3D printed PVDF-8wt.% MoS2 composite over cast neat PVDF. The underlying mechanism of piezoelectric property enhancement is attributed to the increased volume fraction of & beta; phase in PVDF, filler fraction, heterogeneous strain distribution around PVDF-MoS2 interfaces, and strain transfer to the nanofillers as confirmed by micr ostructural analysis and finite element simulation. These results provide a promising route to design and fabricate high-performance 3D piezoelectric devices via 3D printing for next-generation sensors and mechanical-electronic conformal devices.

The Effects of Additive Manufacturing and Electric Poling Techniques on Poly(Vinylidene Fluoride) Materials: Towards Fully Three-Dimensional Printed Functional Materials - Fan, Jinsheng (2023)

Supersonically sprayed PVDF and ZnO flowers with built-in nanocuboids for wearable piezoelectric nanogenerators - Bhavana Joshi, Jaewoo Seol, Edmund Samuel, Woojin Lim, Chan-Woo Park, Ali Aldalbahi, Mohamed H. El‐Newehy, Sam S. Yoon (Nano Energy, 2023)

A review on electrospun PVDF-based nanocomposites: Recent trends and developments in energy harvesting and sensing applications - Sreelakshmi Moozhiyil Purushothaman, Maïté Fernandes Tronco, K. Bicy, Isabelle Royaud, Marc Ponçot, Nandakumar Kalarikkal, Sabu Thomas, Didier Rouxel (Polymer, 2023)

High performance composition-tailored PVDF triboelectric nanogenerator enabled by low temperature-induced phase transition - Daniel Tze Kheng Ong, Jason Soon Chye Koay, Moh Terng Sim, Kean C. Aw, T. Nakajima, BingHui Chen, Swee Tiam Tan, Wee Chen Gan (Nano Energy, 2023)

Optimization of PVDF nanocomposite based flexible piezoelectric tactile sensors: A comparative investigation - M. Arjun Hari, Subash Cherumannil Karumuthil, Lintu Rajan (Sensors and Actuators A Physical, 2023)

Interfacial Engineering of PVDF‐TrFE toward Higher Piezoelectric, Ferroelectric, and Dielectric Performance for Sensing and Energy Harvesting Applications - ["Hamed Abdolmaleki", "Astri Bjørnetun Haugen", "Kristian Birk Buhl", "Kim Daasbjerg", "Shweta Agarwala"] (Advanced Science, 2023)
Abstract The electrical properties of pristine fluoropolymers are inferior due to their low polar crystalline phase content and rigid dipoles that tend to retain their fixed moment and orientation. Several strategies, such as electrospinning, electrohydrodynamic pulling, and template‐assisted growing, have been proven to enhance the electrical properties of fluoropolymers; however, these techniques are mostly very hard to scale‐up and expensive. Here, a facile interfacial engineering approach based on amine‐functionalized graphene oxide (AGO) is proposed to manipulate the intermolecular interactions in poly(vinylidenefluoride‐trifluoroethylene) (PVDF‐TrFE) to induce β ‐phase formation, enlarge the lamellae dimensions, and align the micro‐dipoles. The coexistence of primary amine and hydroxyl groups on AGO nanosheets offers strong hydrogen bonding with fluorine atoms, which facilitates domain alignment, resulting in an exceptional remnant polarization of 11.3 µC cm −2 . PVDF‐TrFE films

Improved Energy Harvesting Ability of Single-Layer Binary Fiber Nanocomposite Membrane for Multifunctional Wearable Hybrid Piezoelectric and Triboelectric Nanogenerator and Self-Powered Sensors - ["An Huang", "Yiwei Zhu", "Shuqiang Peng", "Bin Tan", "Xiangfang Peng"] (ACS Nano, 2023)
While wearable self-powered electronic devices have shown promising improvements, substantial challenges persist in enhancing their electrical output and structural performance. In this work, a working mechanism involving simultaneous piezoelectric and triboelectric conversion within a monolayer-structured membrane is proposed. Single-layer binary fiber nanocomposite membranes (SBFNMs) (PVDF/CNT X @PAN/CNT X, DPCPC X ) with two distinct interpenetrating nanocomposite fibers were created through co-electrospinning, incorporating multiwalled carbon nanotubes (CNTs) into polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN), respectively. The resulting membrane demonstrated an exceptional synergistic effect of piezoelectricity and triboelectricity along with a high machine-to-electric conversion capability. The addition of CNTs increased the PVDF β-phase and the PAN planar zigzag conformation. As a result, the DPCPC 0.5 -SBFNMs-based piezoelectric nanogenerator exhibited excellent el

Robust and Flexible Piezoelectric Lead-Free Zn-BCZT/PVDF-HFP Nanogenerators for Wearable Energy Harvesting - ["Amina Ben Ayed", "Ayda Bouhamed", "Hanen Nouri", "N. Abdelmoula", "H. Khemakhem", "Olfa Kanoun"] (ACS Applied Electronic Materials, 2023)
Herein, flexible piezoelectric nanogenerators were fabricated based on polymer composites containing synthesized lead-free piezoceramics Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT) and zinc-doped BCZT (Zn-BCZT). Polyvinylidene fluorideco -hexafluoropropylene (PVDF-HFP)-based composites were prepared through the solution casting method. The morphology and microstructure were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The distributions of crystallinity and β-phase fractions were also studied. Impedance measurements illustrate the accumulation of space charge in the high-frequency range and the existence of a non-Debye relaxation. The results show that a 10 wt % Zn-BCZT/PVDF-HFP nanogenerator can generate a maximum peak-to-peak output voltage of 3.3 V and a power of 2.13 μW for a load resistance of 1 MΩ under mechanical shaking. This nanogenerator can successfully harvest a good output voltage of up to

Modulation of Electrical Characteristics of Polymer–Ceramic–Graphene Hybrid Composite for Piezoelectric Energy Harvesting - ["Sakti Prasanna Muduli", "Loree Lipsa", "Abhisek Choudhary", "Shailendra Rajput", "Sabyasachi Parida"] (ACS Applied Electronic Materials, 2023)
The use of lead-based ceramics to enhance the piezoelectricity of poly(vinylidene fluoride) (PVDF) is the primary challenge toward nontoxic flexible piezoelectric devices. 0.67BiFeO 3 -0.33BaTiO 3 (BF33BT) is one of the lead-free piezoceramics with high-temperature stability and comparable piezoelectric characteristics to existing lead-based piezoceramics. The work represents PVDF–BF33BT two-phase and PVDF–BF33BT–graphene oxide (GO) three-phase composites with detailed analysis of the dielectric, ferroelectric, and piezoelectric characterizations. Solvent-casting followed by the hot-pressing technique improves the electroactive β-phase of ≥60% in the composites. With BF33BT and GO loading, the dielectric constant and loss tangent increase; however, there is an abrupt rise at the threshold GO concentration of 0.08 wt %. The three-phase composite with 40 wt % BF33BT and 0.08 wt % GO records a dielectric constant of 303 and a loss tangent of 0.68. The harvester out of the same composition

A self-powered piezoelectric Poly(vinyl alcohol)/Polyvinylidene fluoride fiber membrane with alternating multilayer porous structure for energy harvesting and wearable sensors - Yaru Yu, Xiaowen Zhao, Huaiguo Ge, Lin Ye (Composites Science and Technology, 2023)

Bioinspired PVDF Piezoelectric Generator for Harvesting Multi‐Frequency Sound Energy - ["Bangyan Duan", "Kefan Wu", "Xiaoyang Chen", "Jinyan Ni", "Xin Ma", "Weishuai Meng", "Kwok Ho Lam", "Ping Yu"] (Advanced Electronic Materials, 2023)
Abstract With the rapid development of micro‐energy harvesting technology, noise has great potential as a new type of micro‐energy source by developing a high‐performance acoustic energy harvester (AEH). Nevertheless, the challenges of harvesting energy from noise are low acoustic energy density, multi‐frequency mixed sound, and unstable sound pressure. Piezoelectric‐based AEHs are proposed as a solution, but most reported devices need to work at a certain frequency and very high sound pressure, and exhibit the disadvantages of being bulky and heavy when using an extra sound‐pressure amplifier. Here, the eardrum and cochlea bioinspired polyvinylidene fluoride (PVDF) piezoelectric generator which is lightweight, compact, has a simple structure and is low‐cost, harvests multi‐frequency sound energy. Although using the commercial pure PVDF membrane, the prepared AEH still presents a high acoustoelectric conversion performance with an output power of 8.45 µW and an acoustic sensitivity of

3D printing of PVDF-based piezoelectric nanogenerator from programmable metamaterial design: Promising strategy for flexible electronic skin - Haoran Pei, Jingjing Jing, Yinghong Chen, Jiajun Guo, Ning Chen (Nano Energy, 2023)

Heterojunction Engineering Enhanced Self‐Polarization of PVDF/CsPbBr3/Ti3C2Tx Composite Fiber for Ultra‐High Voltage Piezoelectric Nanogenerator - ["You Xue", "Tao Yang", "Yapeng Zheng", "Kang Wang", "Enhui Wang", "Hongyang Wang", "Laipan Zhu", "Zhentao Du"] (Advanced Science, 2023)
Abstract Piezoelectric nanogenerator (PENG) for practical application is constrained by low output and difficult polarization. In this work, a kind of flexible PENG with high output and self‐polarization is fabricated by constructing CsPbBr 3 –Ti 3 C 2 T x heterojunctions in PVDF fiber. The polarized charges rapidly migrate to the electrodes from the Ti 3 C 2 T x nanosheets by forming heterojunctions, achieving the maximum utilization of polarized charges and leading to enhanced piezoelectric output macroscopically. Optimally, PVDF/4wt%CsPbBr 3 /0.6wt%Ti 3 C 2 T x ‐PENG exhibits an excellent voltage output of 160 V under self‐polarization conditions, which is higher than other self‐polarized PENG previously. Further, the working principle and self‐polarization mechanism are uncovered by calculating the interfacial charge and electric field using first‐principles calculation. In addition, PVDF/4wt%CsPbBr 3 /0.6wt%Ti 3 C 2 T x ‐PENG exhibits better water and thermal stability attributed

Synergistic Enhancement of Photocatalytic CO2 Reduction by Built‐in Electric Field/Piezoelectric Effect and Surface Plasmon Resonance via PVDF/CdS/Ag Heterostructure - ["Zijun Wei", "Tuo Ji", "Xuemei Zhou", "Jiawei Guo", "Xin Yu", "Hong Liu", "Jingang Wang"] (Small, 2023)
Abstract Photocatalytic reduction of CO 2 using solar energy is an effective means to achieve carbon neutrality. However, the photocatalytic efficiency still requires improvements. In this study, polyvinylidene fluoride (PVDF) ferroelectric/piezoelectric nanofiber membranes are prepared by electrospinning. Cadmium sulfide (CdS) nanosheets are assembled in situ on the surface of PVDF based on coordination between F − and Cd 2+ , and then Ag nanoparticles are deposited on CdS. Because of the synergistic effect between localized surface plasmon resonance of Ag nanoparticles and the built‐in electric field of PVDF, the CO 2 photocatalytic reduction efficiency using PVDF/CdS/Ag under visible light irradiation is significantly higher than that of any combination of CdS, CdS/Ag, or PVDF/CdS. Under micro‐vibration to simulate air flow, the CO 2 reduction efficiency of PVDF/CdS/Ag is three times higher than that under static conditions, reaching 240.4 µmol g −1 h −1 . The piezoelectric effect c

PU/PVDF blend nanofiber film with enhanced mechanical and piezoelectric performance for development of stable nanogenerators - Zikui Bai, Zhiyuan Yao, Guangmin Wu, Kaiwu Liu, Dezhan Ye, Yongzhen Tao, Shili Xiao, Dongzhi Chen (Sensors and Actuators A Physical, 2023)

Mechanical energy harvesting and self-powered electronic applications of textile-based piezoelectric nanogenerators: A systematic review - ["Satyaranjan Bairagi", "Shahid Ul Islam", "Mohammad Shahadat", "Daniel M. Mulvihill", "S. Wazed Ali"] (Nano Energy, 2023)
Environmental pollution resulting from fossil fuel consumption and the limited lifespan of batteries has shifted the focus of energy research towards the adoption of green renewable technologies. On the other hand, there is a growing potential for small, wearable, portable electronic devices. Therefore, considering the pollution caused by fossil fuels, the drawbacks of chemical batteries, and the potential applications of small-scale wearables and portable electronic devices, the development of a more effective lightweight power source is essential. In this context, piezoelectric energy harvesting technology has attracted keen attention. Piezoelectric energy harvesting technology is a process that converts mechanical energy into electrical energy and vice-versa. Piezoelectric energy harvesters can be fabricated in various ways, including through solution casting, electrospinning, melt spinning, and solution spinning techniques. Solution and melt-spun filaments can be used to develop wo

From synthesis to application: High-quality flexible piezoelectric sensors fabricated from tetragonal BaTiO3/ P(VDF-TrFE) composites - ["Sepide Taleb", "Miguel Badillo", "Francisco Javier Flores‐Ruiz", "Mónica Acuautla"] (Sensors and Actuators A Physical, 2023)
In this work, a simple process for fabrication of piezoelectric BaTiO3 /P(VDFTrFE) composites from synthesis to its application as a wearable piezoelectric sensor is presented. Addition of 10 wt% synthesized tetragonal BaTiO3 particles (200 nm in diameter) enhanced the mechanical and piezoelectric properties of P(VDF-TrFE) better than commercial cubic phase particles (<100 nm in diameter). Although P(VDF-TrFE) and tetragonal BaTiO3 have opposite piezoelectric coefficients, BaTiO3 improved the performance of the final piezoelectric sensor by modifying the distribution of stress in the P(VDF-TrFE) matrix, reducing the viscosity, and causing the mechanical reinforcement of the composite films. This requires the uniform distribution of particles in the polymer matrix, which was succeeded by prior surface modification of the particles. Inverse piezoelectric properties of BaTiO3 /P(VDF-TrFE) composites were enhanced by obtaining a higher polarization (Pr = 6.18 µC/cm2) and dielectric constan

Scalable, flexible BaTiO3/PVDF piezocomposites prepared via supersonic spraying for use in energy harvesting and integrated energy storage devices - Taegun Kim, Bhavana Joshi, Woojin Lim, Edmund Samuel, Ali Aldalbahi, Govindasami Periyasami, Hae‐Seok Lee, Seongpil An (Nano Energy, 2023)

Highly piezoelectric, biodegradable, and flexible amino acid nanofibers for medical applications - ["Meysam T. Chorsi", "Thinh T. Le", "Feng Lin", "Tra Vinikoor", "Ritopa Das", "James F. Stevens", "Caitlyn Mundrane", "Jinyoung Park"] (Science Advances, 2023)
Amino acid crystals are an attractive piezoelectric material as they have an ultrahigh piezoelectric coefficient and have an appealing safety profile for medical implant applications. Unfortunately, solvent-cast films made from glycine crystals are brittle, quickly dissolve in body fluid, and lack crystal orientation control, reducing the overall piezoelectric effect. Here, we present a material processing strategy to create biodegradable, flexible, and piezoelectric nanofibers of glycine crystals embedded inside polycaprolactone (PCL). The glycine-PCL nanofiber film exhibits stable piezoelectric performance with a high ultrasound output of 334 kPa [under 0.15 voltage root-mean-square (Vrms)], which outperforms the state-of-the-art biodegradable transducers. We use this material to fabricate a biodegradable ultrasound transducer for facilitating the delivery of chemotherapeutic drug to the brain. The device remarkably enhances the animal survival time (twofold) in mice-bearing orthotop

Cesium Lead Halide Perovskite Decorated Polyvinylidene Fluoride Nanofibers for Wearable Piezoelectric Nanogenerator Yarns - ["Siying Wu", "Fatemeh Zabihi", "Rou Yi Yeap", "Mohammad Reza Yousefi Darestani", "Addie Bahi", "Zeyu Wan", "Shengyuan Yang", "Peyman Servati"] (ACS Nano, 2023)
High Resolution Image Download MS PowerPoint Slide Piezoelectric nanogenerators (PENGs) provide a viable solution to convert the mechanical energy generated by body movement to electricity. One-dimensional yarns offer a platform for flexible wearable textile PENGs, which can conform to body for comfort and efficient energy harvesting. In this context, we report a flexible piezoelectric yarn, assembled by one-step cocentric deposition of cesium lead halide perovskite decorated polyvinylidene fluoride (PVDF) nanofibers, on a stainless-steel yarn. Perovskite crystals were formed in situ during electrospinning. Our work demonstrates a nanofiber morphology in which perovskite crystals spread over the nanofiber, leading to a rough surface, and complementing piezoelectric nanocomposite formation with PVDF for superior stress excitation. We investigated how the halide anions of perovskite affect the piezoelectric performance of PENG yarns by comparing CsPbBr 3 and CsPbI 2 Br. Effects of the pe

Paper-based piezoelectric sensors with an irregular porous structure constructed by scraping of 3D BaTiO3 particles/Poly(vinylidene fluoride) for micro pressure and human motion sensing - Chenxu Yu, Jiwen Xu, Ling Yang, Hua Wang, Taoliang Li, Yashuai Ye, Guanghui Rao (Sensors and Actuators A Physical, 2023)

Coral-like BaTiO3-Filled Polymeric Composites as Piezoelectric Nanogenerators for Movement Sensing - ["Yuhang Du", "Gang Jian", "Chen Zhang", "Fengwei Wang"] (Polymers, 2023)
Piezoelectric nanogenerators have prospective uses for generating mechanical energy and powering electronic devices due to their high output and flexible behavior. In this research, the synthesis of the three-dimensional coral-like BaTiO3 (CBT) and its filling into a polyvinylidene fluoride (PVDF) matrix to obtain composites with excellent energy harvesting properties are reported. The CBT-based PENG has a 163 V voltage and a 16.7 µA current at a frequency of 4 Hz with 50 N compression. Simulations show that the high local stresses in the CBT coral branch structure are the main reason for the improved performance. The piezoelectric nanogenerator showed good durability at 5000 cycles, and 50 commercial light-emitting diodes were turned on. The piezoelectric nanogenerator generates a voltage of 4.68–12 V to capture the energy generated by the ball falling from different heights and a voltage of ≈0.55 V to capture the mechanical energy of the ball’s movement as it passes. This study sugge

A Piezoelectric‐Driven Electrochromic/Electrofluorochromic Dual‐Modal Display Device - ["Yingchao Zhang", "Xiaoteng Jia", "Bolun Sun", "Ruonan Huang", "Ce Wang", "Danming Chao"] (Small, 2023)
Electrochromic (EC) reflective displays offer great advantages in delivering information and providing visual data, but are limited in dark environments. Reflective/emissive dual-modal displays capable of electrochemically-induced color and fluorescence change simultaneously are highly desirable, especially possessing rapid response speed as well as long-term durability. Herein, an electroactive fluorescent ionic liquid based on triphenylamine and imidazole (EFIL-TPA) has been synthesized for reflective/emissive dual-modal display. The resultant device exhibits outstanding electrochromic/electrofluorochromic (EC/EFC) performance with low driving voltage (below 1.0 V), fast switching speed (0.57-1.8 s), and remarkable cycling durability (91% retention for 10 000 cycles). A piezoelectric nanogenerator (PENG) driven EC/EFC integrated system is fabricated to harvest energy from human motion and visually drive the color/fluorescence change for human motion indication in both bright and dark

Synthesis and Characterization of Core–Double-Shell-Structured PVDF-grafted-BaTiO3/P(VDF-co-HFP) Nanocomposite Films - ["Fatima Ezzahra Bouharras", "Salima Atlas", "S. Capaccioli", "M. Labardi", "Abdelghani Hajlane", "Bruno Améduri", "Mustapha Raihane"] (Polymers, 2023)
Core–double-shell-structured nanocomposite films consisting of polyvinylidene fluoride-grafted-barium titanate (PVDF-g-BT) incorporated into a P(VDF-co-hexafluoropropylene (HFP)) copolymer matrix were produced via a solution mixing method for energy storage applications. The resulting films were thoroughly investigated via spectroscopic, thermal, and morphological analyses. Thermogravimetric data provided an enhancement of the thermal stability, while differential scanning calorimetry indicated an increase in the crystallinity of the films after the addition of PVDF-g-BT. Moreover, broadband dielectric spectroscopy revealed three dielectric processes, namely, glass–rubber relaxation (αa), relaxation associated with the polymer crystalline phase (αc), and slower relaxation in the nanocomposites resulting from the accumulation of charge on the interface between the PVDF-g-BT filler and the P(VDF-co-HFP) matrix. The dependence of the dielectric constant from the composition was analyzed,

The β Form in PVDF Nanocomposites with Carbon Nanotubes: Structural Features and Properties - ["María L. Cerrada", "Javier Arranz‐Andrés", "Alicia Caballero-González", "Enrique Blázquez‐Blázquez", "Ernesto Pérez"] (Polymers, 2023)
Different amounts of carbon nanotubes (CNT) have been incorporated in materials based on poly(vinylidene fluoride) (PVDF) by solvent blending followed by their further precipitation. Final processing was performed by compression molding. The morphological aspects and crystalline characteristics have been examined, additionally exploring in these nanocomposites the common routes described in the pristine PVDF to induce the β polymorph. This polar β phase has been found to be promoted by the simple inclusion of CNT. Therefore, coexistence of the α and β lattices occurs for the analyzed materials. The real-time variable-temperature X-ray diffraction measurements with synchrotron radiation at a wide angle have undoubtedly allowed us to observe the presence of the two polymorphs and determine the melting temperature of both crystalline modifications. Furthermore, the CNT plays a nucleating role in the PVDF crystallization, and also acts as reinforcement, increasing the stiffness of the nano

A Coupled Electro-Mechanical Homogenization-Based Model for PVDF-Based Piezo-Composites Considering α → β Phase Transition and Interfacial Damage - ["Fateh Enouar Mamache", "Amar Mesbah", "Fahmi Zaïri", "Iurii Vozniak"] (Polymers, 2023)
Polyvinylidene fluoride or polyvinylidene difluoride (PVDF) is a piezoelectric semi-crystalline polymer whose electro-mechanical properties may be modulated via strain-induced α → β phase transition and the incorporation of polarized inorganic particles. The present work focuses on the constitutive representation of PVDF-based piezo-composites developed within the continuum-based micromechanical framework and considering the combined effects of particle reinforcement, α → β phase transition, and debonding along the interface between the PVDF matrix and the particles under increasing deformation. The micromechanics-based model is applied to available experimental data of PVDF filled with various concentrations of barium titanate (BaTiO3) particles. After its identification and predictability verification, the model is used to provide a better understanding of the separate and synergistic effects of BaTiO3 particle reinforcement and the micromechanical deformation processes on the electr

Fast and versatile electrostatic disc microprinting for piezoelectric elements - ["Xuemu Li", "Zhuomin Zhang", "Zehua Peng", "Xiaodong Yan", "Ying Hong", "Shiyuan Liu", "Weikang Lin", "Shan Yao"] (Nature Communications, 2023)
Abstract Nanoparticles, films, and patterns are three critical piezoelectric elements with widespread applications in sensing, actuations, catalysis and energy harvesting. High productivity and large-area fabrication of these functional elements is still a significant challenge, let alone the control of their structures and feature sizes on various substrates. Here, we report a fast and versatile electrostatic disc microprinting, enabled by triggering the instability of liquid-air interface of inks. The printing process allows for fabricating lead zirconate titanate free-standing nanoparticles, films, and micro-patterns. The as-fabricated lead zirconate titanate films exhibit a high piezoelectric strain constant of 560 pm V −1 , one to two times higher than the state-of-the-art. The multiplexed tip jetting mode and the large layer-by-layer depositing area can translate into depositing speeds up to 10 9 μm 3 s −1 , one order of magnitude faster than current techniques. Printing diversif

Fabrication of CuO-NP-Doped PVDF Composites Based Electrospun Triboelectric Nanogenerators for Wearable and Biomedical Applications - ["Bindhu Amrutha", "Prasad Gajula", "Sathiyanathan Ponnan", "Mohammad Shamim Reza", "Hongdoo Kim", "Madhvesh Pathak", "Arun Anand Prabu"] (Polymers, 2023)
A flexible and portable triboelectric nanogenerator (TENG) based on electrospun polyvinylidene fluoride (PVDF) doped with copper oxide (CuO) nanoparticles (NPs, 2, 4, 6, 8, and 10 wt.-% w.r.t. PVDF content) was fabricated. The structural and crystalline properties of the as-prepared PVDF-CuO composite membranes were characterized using SEM, FTIR, and XRD. To fabricate the TENG device, the PVDF-CuO was considered a tribo-negative film and the polyurethane (PU) a counter-positive film. The output voltage of the TENG was analyzed using a custom-made dynamic pressure setup, under a constant load of 1.0 kgf and 1.0 Hz frequency. The neat PVDF/PU showed only 1.7 V, which further increased up to 7.5 V when increasing the CuO contents from 2 to 8 wt.-%. A decrease in output voltage to 3.9 V was observed for 10 wt.-% CuO. Based on the above results, further measurements were carried out using the optimal sample (8 wt.-% CuO). Its output voltage performance was evaluated as a function of varying

Dielectric Characterization of Core-Shell Structured Poly(vinylidene fluoride)-grafted-BaTiO3 Nanocomposites - ["Fatima Ezzahra Bouharras", "M. Labardi", "E. Tombari", "S. Capaccioli", "Mustapha Raihane", "Bruno Améduri"] (Polymers, 2023)
-BT) core-shell structured nanocomposites obtained from Reversible Addition Fragmentation chain Transfer (RAFT) polymerization of VDF were investigated by Broadband Dielectric Spectroscopy (BDS). The dielectric constant increased along with the BT content, about +50% by addition of 15 vol% of BT, which was around 40% more than expected from predictions using the usual dielectric modeling methods for composite materials, to be ascribed to the effect of the interfacial core-shell structure. The known dielectric relaxations for PVDF were observed for the neat polymer as well as for its nanocomposites, not affected by the presence of nanoparticles. A relaxation process at higher temperatures was found, due to interfacial polarization at the amorphous-crystalline interface, due to the high crystallinity of materials produced by RAFT. Isochronal BDS spectra were exploited to detect the primary relaxation of the amorphous fraction. Thermal analysis demonstrated a very broad endotherm at tempe

β-Phase Enhancement of Force Spun Composite Nanofibers for Sensing Applications - ["Renato Wenceslao Aguirre-Corona", "Karina Del Ángel-Sánchez", "Nicolás A. Ulloa-Castillo", "Juan Jose Rodriguez", "Daniel Olvera-Trejo", "Imperio Anel Perales-Martínez", "Óscar Martínez-Romero", "Alex Elı́as-Zúñiga"] (Polymers, 2023)
In this study, a piezoelectric harvesting device was developed using polyvinylidene fluoride (PVDF) nanofibers reinforced with either BaTiO3 nanoparticles or graphene powder. BaTiO3 nanoparticles were synthesized through the sol-gel method with an average size of approximately 32 nm. The PVDF nanofibers, along with the nanoparticle composites in an acetone-N,N-dimethylformamide mixture, were produced using a centrifugal Forcespinning™ machine, resulting in a heterogeneous arrangement of fiber meshes, with an average diameter of 1.6 μm. Experimental tests revealed that the electrical performance of the fabricated harvester reached a maximum value of 35.8 Voc, demonstrating the potential of BaTiO3/ PVDF-based piezoelectric devices for designing wearable applications such as body-sensing and energy-harvesting devices.

Enhancing tissue regeneration with self-healing elastic piezoelectricity for sustainable implants - ["Bankole I. Oladapo", "Qi Zhao"] (Nano Energy, 2023)
This study explores an innovative energy harvesting technique for biomedical implants in alignment with the United Nations Sustainable Development Goals, focusing on good health and well-being (Goal 3). The study promotes sustainable healthcare solutions by analysing mechanically deformed materials, surface charges, and electric fields. This review research delves into the advancements and potential of piezoelectric materials and their integration with other energy-harvesting technologies, such as thermoelectrics, to create innovative hybrid systems for sustainable energy production and biomedical applications. The study highlights the development of stretchable, self-healing, and biodegradable piezoelectric materials enabled by nano-fillers, structural engineering, and various fabrication techniques. Integrating piezoelectric and thermoelectric materials in hybrid Energy Harvesters (EH) has led to devices capable of simultaneously harnessing thermal and mechanical energy, ensuring con

Enhancement of Energy Storage Performance of PMMA/PVDF Composites by Changing the Crystalline Phase through Heat Treatment - ["Changhai Zhang", "Xu Tong", "Zeyang Liu", "Yue Zhang", "Tiandong Zhang", "Chao Tang", "Xianli Liu", "Qingguo Chi"] (Polymers, 2023)
In today’s contemporary civilization, there is a growing need for clean energy focused on preserving the environment; thus, dielectric capacitors are crucial equipment in energy conversion. On the other hand, the energy storage performance of commercial BOPP (Biaxially Oriented Polypropylene) dielectric capacitors is relatively poor; hence, enhancing their performance has drawn the attention of an increasing number of researchers. This study used heat treatment to boost the performance of the composite made from PMAA and PVDF, combined in various ratios with good compatibility. The impacts of varying percentages of PMMA-doped PMMA/PVDF mixes and heat treatment at varying temperatures were systematically explored for their influence on the attributes of the blends. After some time, the blended composite’s breakdown strength improves from 389 kV/mm to 729.42 kV/mm at a processing temperature of 120 °C. Consequently, the energy storage density is 21.12 J/cm3, and the discharge efficiency

Flexible BaTiO3-PDMS Capacitive Pressure Sensor of High Sensitivity with Gradient Micro-Structure by Laser Engraving and Molding - ["Jiayi Li", "Shangbi Chen", "Jingyu Zhou", "Lei Tang", "Chenkai Jiang", "Dawei Zhang", "Bin Sheng"] (Polymers, 2023)
The significant potential of flexible sensors in various fields such as human health, soft robotics, human–machine interaction, and electronic skin has garnered considerable attention. Capacitive pressure sensor is popular given their mechanical flexibility, high sensitivity, and signal stability. Enhancing the performance of capacitive sensors can be achieved through the utilization of gradient structures and high dielectric constant media. This study introduced a novel dielectric layer, employing the BaTiO3-PDMS material with a gradient micro-cones architecture (GMCA). The capacitive sensor was constructed by incorporating a dielectric layer GMCA, which was fabricated using laser engraved acrylic (PMMA) molds and flexible copper-foil/polyimide-tape electrodes. To examine its functionality, the prepared sensor was subjected to a pressure range of 0–50 KPa. Consequently, this sensor exhibited a remarkable sensitivity of up to 1.69 KPa−1 within the pressure range of 0–50 KPa, while main

High-performance piezoelectric nanogenerators based on Cs2Ag0.3Na0.7InCl6 double perovskites with high polarity induced by Zr/Te codoping - ["Xiangcong He", "Jinju Zheng", "Tao Yang", "Deliu Ou", "Chris Bowen", "Songhan Shi", "Qiaochu Chen", "Hui Fu"] (Nano Energy, 2023)
High-performance piezoelectric nanogenerators (PENGs) based on Zr/Te codoped Cs2Ag0.3Na0.7InCl6 double perovskites (ZTCDPs) are reported. The devices delivered an excellent piezoelectric output, with a maximum open-circuit voltage and shortcircuit current density of 67 V and 18 μA·cm-2, respectively. Moreover, they exhibited significant potential toward the applications of wearable energy harvesters, motion sensors, and self-powered DC devices. 3 Abstract 1 Piezoelectric nanogenerators (PENGs), which operate based on mechanical-to2 electrical energy conversion, have been widely explored for exciting applications in 3 modern devices such as wearable electronics, self-powered sensors, and energy 4 harvesters. Herein, we report on high-performance PENGs based on Cs2Ag0.3Na0.7InCl6 5 double perovskite (CDP) within a polyvinylidene fluoride (PVDF) matrix, which 6 exhibit enhanced polarity due to rationally designed Zr/Te codoping. As a proof of 7 concept, the resultant PENGs based on Zr/Te codoped CDP@PVDF deliver an 8 excellent piezoelectric output, with a maximum open-circuit voltage and short-circuit 9 current density of 67 V and 18 μA·cm-2. This level of performance is ~19 and ~12 times 10 higher than PVDF-based PENGs with no CDP, and ~2 and ~4 times higher than 11 CDP@PVDF-based PENGs without doping or with single Te doping, and ~1 and ~2 12 times higher than CDP@PVDF-based PENGs with single Zr doping, respectively. 13 Moreover, the as-assembled PENGs exhibit impressive potential in wearable energy 14 harvesters, motion sensors, and DC-power devices with robust stability, underscoring 15 their bright future toward practical applications. 16 17

Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling - ["Zhuomin Zhang", "Xuemu Li", "Zehua Peng", "Xiaodong Yan", "Shiyuan Liu", "Ying Hong", "Shan Yao", "Xiaote Xu"] (Nature Communications, 2023)
Abstract Piezoelectric biomaterials have attracted great attention owing to the recent recognition of the impact of piezoelectricity on biological systems and their potential applications in implantable sensors, actuators, and energy harvesters. However, their practical use is hindered by the weak piezoelectric effect caused by the random polarization of biomaterials and the challenges of large-scale alignment of domains. Here, we present an active self-assembly strategy to tailor piezoelectric biomaterial thin films. The nanoconfinement-induced homogeneous nucleation overcomes the interfacial dependency and allows the electric field applied in-situ to align crystal grains across the entire film. The β-glycine films exhibit an enhanced piezoelectric strain coefficient of 11.2 pm V −1 and an exceptional piezoelectric voltage coefficient of 252 × 10 −3 Vm N −1 . Of particular significance is that the nanoconfinement effect greatly improves the thermostability before melting (192 °C). Thi

Enhancing the Piezoelectric Properties of 3D Printed PVDF Using Concurrent Torsional Shear Strain - ["Pu Han", "Alireza Tofangchi", "Derek Carr", "Sihan Zhang", "Keng Hsu"] (Polymers, 2023)
Extrusion-based polymer 3D printing induces shear strains within the material, influencing its rheological and mechanical properties. In materials like polyvinylidene difluoride (PVDF), these strains stretch polymer chains, leading to increased crystallinity and improved piezoelectric properties. This study demonstrates a 400% enhancement in the piezoelectric property of extrusion-printed PVDF by introducing additional shear strains during the printing process. The continuous torsional shear strains, imposed via a rotating extrusion nozzle, results in additional crystalline β-phases, directly impacting the piezoelectric behavior of the printed parts. The effect of the nozzle's rotational speed on the amount of β-phase formation is characterized using FTIR. This research introduces a new direction in the development of polymer and composite 3D printing, where in-process shear strains are used to control the alignment of polymer chains and/or in-fill phases and the overall properties of

Elucidating the Piezoelectric, Ferroelectric, and Dielectric Performance of Lead-Free KNN/PVDF and Its Copolymer-Based Flexible Composite Films - ["Alekhika Tripathy", "Nirmal Prashanth Maria Joseph Raj", "Sang‐Jae Kim", "Ananthakumar Ramadoss"] (ACS Applied Electronic Materials, 2023)
Ecofriendly, reliable, and high-performance piezoelectric materials are drawing huge interest in resolving the environmental problems arising due to consumption of fossil fuel energy. Among the lead-free ferroelectrics, potassium sodium niobate (KNN, (K,Na)NbO 3 ) is one of the most promising piezoelectric ceramics that can replace Pb(Zr,Ti)O 3 . In the present work, the piezoelectric performance of KNN incorporated in poly(vinylidene fluoride) (PVDF) and its copolymers, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), has been compared. The films were fabricated by a solution casting method and were further polarized by a corona poling technique. The results confirmed that the nanocomposite film with 8 wt % KNN filler in PVDF-TrFE (PTK8) exhibited the highest F (β) value, maximum remnant polarization, and dielectric constant value than other nanocomposites. The relative β-phase contents in PTK8, PHK8, and PK8 composite

The tribo-piezoelectric microscopic coupling mechanism of ferroelectric polymers and the synchronous online monitoring of load distribution/roller speed for intelligent bearings - Lizhou Li, Xiaoli Wang, Yanqiang Hu, Zhihao Li, Zirui Zhao, Gao Zheng (Nano Energy, 2023)

Effect of Fe3O4 Nanoparticles Modified by Citric and Oleic Acids on the Physicochemical and Magnetic Properties of Hybrid Electrospun P(VDF-TrFE) Scaffolds - ["Vladimir V. Botvin", "Anastasia Fetisova", "Yulia R. Mukhortova", "Dmitry V. Wagner", "С. О. Казанцев", "Maria A. Surmeneva", "Andréi L. Kholkin", "Roman A. Surmenev"] (Polymers, 2023)
This study considers a fabrication of magnetoactive scaffolds based on a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) and 5, 10, and 15 wt.% of magnetite (Fe3O4) nanoparticles modified with citric (CA) and oleic (OA) acids by solution electrospinning. The synthesized Fe3O4-CA and Fe3O4-OA nanoparticles are similar in particle size and phase composition, but differ in zeta potential values and magnetic properties. Pure P(VDF-TrFE) scaffolds as well as composites with Fe3O4-CA and Fe3O4-OA nanoparticles demonstrate beads-free 1 μm fibers. According to scanning electron (SEM) and transmission electron (TEM) microscopy, fabricated P(VDF-TrFE) scaffolds filled with CA-modified Fe3O4 nanoparticles have a more homogeneous distribution of magnetic filler due to both the high stabilization ability of CA molecules and the affinity of Fe3O4-CA nanoparticles to the solvent used and P(VDF-TrFE) functional groups. The phase composition of pure and composite scaffolds includes

Elevating the performance of nanoporous bismuth selenide incorporated arch-shaped triboelectric nanogenerator by implementing piezo-tribo coupling effect: harvesting biomechanical energy and low scale energy sensing applications - ["Debmalya Sarkar", "Namrata Das", "Md. Minarul Saikh", "Shubham Roy", "Sumana Paul", "Nur Amin Hoque", "Ruma Basu", "Sukhen Das"] (Advanced Composites and Hybrid Materials, 2023)
With the increasing demand of environmental friendly and unlimited power supplies, the use of triboelectric nanogenerator (TENG) also increases due to its high mechanical energy to electrical energy conversion ability. Herein, an arch shaped, self-powered, and wearable piezoelectric thin film with bismuth selenide based triboelectric nanogenerator, named as PBTNG, is fabricated with the help of nanoporous bismuth selenide (Bi2Se3) incorporated poly(vinyldene fluoride) (PVDF) composite piezoelectric thin film (PBi). The mechanism of the PBTNG device is induced by piezo-tribo coupling effect. Furthermore, the surface area and distribution of pore size of Bi2Se3 have been measured from Brunnauer–Emmett–Teller (BET) analysis and also described by basal spacing, which helps in increment of β-crystalline phase of the thin film. The density functional theory (DFT) has been performed to find out the electrical band gap and density of states of Bi2Se3 nanoparticles. The interaction of nanoparti cle with PVDF monomer and electrical properties of β-phase has been investigated with DFT calculations as well. The fabricated triboelectric device exhibits outstanding output performance with a maximum power density of 2.03 Wm−2 under continuous finger impartation and can illuminate light-emitting diodes (LEDs) under heel pressing and periodic finger tapping. Additionally, the wearable PBTNG device traps the biomechanical energy from different body movements like heel pressing, feet tapping, blood flow, single finger tapping, etc., and converts them into electrical energy easily. Furthermore, single electrode bismuth selenide based triboelectric nanogenerator, named as SBTNG exhibits high sensitivity value (20.2 V/kPa) at low pressure region (< 0.5 kPa) which helps in electricity generation from small scale mechanical energies such as writing on the device, mouse clicking, keyboard striking, external CD drive running, etc. Thus, self-powered and wearable energy harvester can be used in daily life as a substitute of batteries. Excellent output performance of PBTNG has been achieved from biomechanical and small scale mechanical energy, elevated by piezo-tribo coupling effect.

Characterizing piezoelectric properties of PVDF film under extreme loadings - ["Yao Yu", "Jialin Li", "Zihao Xie", "Xiaobo Gong", "Guangjun Gao", "Jia-Bin Wang", "Jian Li"] (Smart Materials and Structures, 2023)
Abstract Polyvinylidene fluoride (PVDF) as a polymer has been proven to be an effective piezoelectric sensor with advantages of good flexibility, high mechanical strength, and high chemical resistance. Numerous studies have focused on the response of PVDF film at high strain rates, but few on low strain rate response, and the response of PVDF film at different strain rates is unknown. To address these limitations, we examine the piezoelectric properties of PVDF film at extreme high and low loading rates. We design quasi-static compression and dynamic split Hopkinson pressure bar (SHPB) test setups to examine the response of PVDF film. Quasi-static compression test results show that PVDF films have good repeatability and linearity. The charge shift phenomenon is observed at quasi-static loading conditions, and the charge shift rate is found to be related to the gain coefficient of charge amplifier. Next, SHPB tests are performed and results show that PVDF film can well capture the propa

Investigation of 2D-Ti3C2TX-Loaded PVDF Composites for a High-Performance Flexible Piezoelectric Energy Harvester and Wearable Sensor - ["Bibekananda Nayak", "Sharmistha Anwar", "Sharmistha Anwar", "Amritendu Roy", "Shahid Anwar", "Shahid Anwar"] (ACS Applied Electronic Materials, 2023)
Flexible piezoelectric generators have attracted a great deal of attention recently for their promising applications in mechanical energy harvesting and portable electronic devices. The significant properties of 2D MXene (Ti 3 C 2 T X ) inspired us to develop a nanocomposite with poly(vinylidene fluoride) (PVDF) by varying the Ti 3 C 2 T X filler using tape casting techniques. The structural and microstructural properties of the composite film were examined through X-ray diffraction and field-emission scanning electron microscopy. FTIR studies revealed that an increase in the electroactive phase from 73 to 82% was observed by adding the Ti 3 C 2 T X filler into the PVDF matrix. The frequency-dependent dielectric constant, dielectric loss, and RT impedance spectra were studied. The leakage current density and ferroelectric behavior of the Ti 3 C 2 T X -added PDVF composite films showed significant results as compared to the pure PVDF film. A bipolar strain with an electric field (S–E) c

Stretchable piezoelectric biocrystal thin films - ["Jun Li", "Corey Carlos", "Hao Zhou", "Jiajie Sui", "Yikai Wang", "Zulmari Silva‐Pedraza", "Fan Yang", "Yutao Dong"] (Nature Communications, 2023)
Stretchability is an essential property for wearable devices to match varying strains when interfacing with soft tissues or organs. While piezoelectricity has broad application potentials as tactile sensors, artificial skins, or nanogenerators, enabling tissue-comparable stretchability is a main roadblock due to the intrinsic rigidity and hardness of the crystalline phase. Here, an amino acid-based piezoelectric biocrystal thin film that offers tissue-compatible omnidirectional stretchability with unimpaired piezoelectricity is reported. The stretchability was enabled by a truss-like microstructure that was self-assembled under controlled molecule-solvent interaction and interface tension. Through the open and close of truss meshes, this large scale biocrystal microstructure was able to endure up to 40% tensile strain along different directions while retained both structural integrity and piezoelectric performance. Built on this structure, a tissue-compatible stretchable piezoelectric

Self-Polarized P(VDF-TrFE)/Carbon Black Composite Piezoelectric Thin Film - ["Lavanya Muthusamy", "Balaadithya Uppalapati", "Samee Azad", "Manav Bava", "Goutam Koley"] (Polymers, 2023)
Self-polarized energy harvesting materials have seen increasing research interest in recent years owing to their simple fabrication method and versatile application potential. In this study, we systematically investigated self-polarized P(VDF-TrFE)/carbon black (CB) composite thin films synthesized on flexible substrates, with the CB content varying from 0 to 0.6 wt.% in P(VDF-TrFE). The presence of -OH functional groups on carbon black significantly enhances its crystallinity, dipolar orientation, and piezoelectric performance. Multiple characterization techniques were used to investigate the crystalline quality, chemical structure, and morphology of the composite P(VDF-TrFE)/CB films, which indicated no significant changes in these parameters. However, some increase in surface roughness was observed when the CB content increased. With the application of an external force, the piezoelectrically generated voltage was found to systematically increase with higher CB content, reaching a m

Three-Dimensional Printable Flexible Piezoelectric Composites with Energy Harvesting Features - ["Mihaela Aradoaei", "Romeo Cristian Ciobanu", "Cristina Schreiner", "Marius Valerian Paulet", "Alina Ruxandra Caramitu", "Jana Pintea", "M. Baibarac"] (Polymers, 2023)
The purpose of this work was to obtain an elastic composite material from polymer powders (polyurethane and polypropylene) with the addition of BaTiO3 until 35% with tailored dielectric and piezoelectric features. The filament extruded from the composite material was very elastic but had good features to be used for 3D printing applications. It was technically demonstrated that the 3D thermal deposition of composite filament with 35% BaTiO3 was a convenient process for achieving tailored architectures to be used as devices with functionality as piezoelectric sensors. Finally, the functionality of such 3D printable flexible piezoelectric devices with energy harvesting features was demonstrated, which can be used in various biomedical devices (as wearable electronics or intelligent prosthesis), generating enough energy to make such devices completely autonomous only by exploiting body movements at variable low frequencies.

Full and In Situ Printing of Nanogenerators that Are Based on an Inherently Viscous Piezoelectric Polymer: An Effort to Minimize “Coffee Ring Effect” and Nonprinting Operations - ["Yunnan Fang", "Haiyang Zou", "Song Peng", "Gaoya Dong", "Manos M. Tentzeris"] (ACS Applied Electronic Materials, 2023)
High Resolution Image Download MS PowerPoint Slide Among various printing technologies for fabrication of electronic devices, microplotter printing and inkjet printing provide the best printing resolution. For inkjet printing, which is compatible with only low-viscosity inks, the “coffee ring effect” and time-/labor-consuming nonprinting operations are among the most that impose challenges to its applications for rapid and large-scale fabrication of electronic devices. When printing a flexible electronic device that tends to bend spontaneously, relocating an unfinished/undried workpiece for post-printing treatments usually causes ink diffusion, resulting in deteriorated printing resolution, nonuniformity, and defects. Taking the printing of a poly(vinylidene fluoride)- (PVDF-) based flexible nanogenerator as an example, this work utilized a high-viscosity compatible microplotter printer and a concentrated/viscous PVDF ink (which minimized the “coffee ring effect)” and an in situ fabric

Development of a piezo biosensor for pathogen-specific biopolymer detection using a self-assembly barium titanate/polyvinylidene fluoride composite material - Mariko Takeda, Hayato Yoshino, Haruna Yamazaki, Takamichi Hirata, Takashi Kuroiwa, Chie Nakajima, Yasuhiko Suzuki, Fumio Munakata (Sensors and Actuators A Physical, 2023)

The Contribution of BaTiO3 to the Stability Improvement of Ethylene–Propylene–Diene Rubber: Part II—Doped Filler - ["Traian Zaharescu", "Alina Dumitru", "Tünde Borbáth", "Ioana Alexandra Ionescu", "Istvan Borbáth", "Tiberiu Francisc Boros"] (Polymers, 2023)
The thermal and radiation stabilities of the formulations based on ethylene–propylene–diene rubber (EPDM), which contain barium titanate (BaTiO3) doped with lanthanum and cerium oxides, were investigated by chemiluminescence and mechanical testing. The contributions of these doped fillers are related to the surface interaction between the structural defects (doping atoms, i.e., lanthanum and cerium) implanted in the filler lattice and the molecular fragments formed during the progress of degradation. These composite materials present extended durabilities with respect to the references; the oxidation periods are a minimum of three times longer than the corresponding times for pristine polymers. This behavior is associated with the scavenging activity of dopants. Mechanical testing has demonstrated the contributions of doped filler to the improvement of tensile strength and elongation at break by the restructuration of the polymer phase. Scanning electron microscopy images revealed the

3D vertically aligned microchannel structure to enhance piezoelectric energy harvesting performance of PZT/PVDF&CNTs piezoelectric composites (Journal of Materiomics, 2023)
Piezoelectric energy harvesters (PEHs) have attracted significant attention with the ability of converting mechanical energy into electrical energy and power the self-powered microelectronic components. Generally, material's superior energy harvesting performance is closely related to its high transduction coefficient (d33×g33), which is dependent on higher piezoelectric coefficient d33 and lower dielectric constant εr of materials. However, the high d33 and low εr are difficult to be simultaneously achieved in piezoelectric ceramics. Herein, lead zirconate titanate (PZT) based piezoelectric composites with vertically aligned microchannel structure are constructed by phase-inversion method. The polyvinylidene fluoride (PVDF) and carbon nanotubes (CNTs) are mixed as fillers to fabricate PZT/PVDF&CNTs composites. The unique structure and uniformly distributed CNTs network enhance the polarization and thus improve the d33. The PVDF filler effectively reduce the εr. As a consequence, the e xcellent piezoelectric coefficient (d33 = 595 pC/N) and relatively low dielectric constant (εr = 1603) were obtained in PZT/PVDF&CNTs composites, which generated an ultra-high d33×g33 of 24,942 × 10−15 m2/N. Therefore, the PZT/PVDF&CNTs piezoelectric composites achieve excellent energy harvesting performance (output voltage: 66 V, short current: 39.22 μA, and power density: 1.25 μW/mm2). Our strategy effectively boosts the performance of piezoelectric-polymer composites, which has certain guiding significance for design of energy harvesters.

Properties and Potential Application of Lead-Free (BaZr0.2Ti0.8O3) and Lead-Based (PbZr0.52Ti0.48O3) Flexible Thick Films (Crystals, 2023)
For the last several decades, energy harvesters based on piezoelectricity from mechanical vibration have emerged as very promising devices that are being explored extensively for their functionality in energy technologies. In this paper, a series of flexible lead-free BaZr0.2Ti0.8O3 (BZT)/PVDF and lead-based PbZr0.52Ti0.48O3 (PZT)/PVDF piezocomposites with variable filler content up to 50 vol% were prepared by a hot pressing method. The structure and morphology of the BZT and PZT powders, as well as the distribution of the piezo-active filler in the obtained flexible films were characterized by XRD and SEM analysis. In addition, the remnant polarization (Pr) and leakage current were also investigated to evaluate the breakdown strength in both types of flexible films. The calculations of storage energies and output voltage obtained for the investigated materials revealed an increasing trend with an increasing amount of BZT and PZT active phases. The maximum storage energy of 0.42 J/cm3 (and energy efficiency of 40.7 %) was obtained for the PZT–PVDF (40–60) films, while the maximum output voltage of about 10 V (~10 μA) was obtained for the PZT–PVDF (50–50) flexible film. In addition, a comparison between the properties of the lead-based and lead-free flexible films, as well as the potential use of these films as energy storage and energy harvesting systems were analyzed.

Dramatically improved piezo-photocatalytic activity in PVDF@Bi2MoO6/BiOBr composite films via constructing built-in polarization field in heterojunctions - Ming Liu; Aikun Liu; Hongjian Zhang; three others (RG visible) (Journal of Alloys and Compounds, 2023)

Dramatically enhanced energy harvesting capability in sandwich-structure modulated piezoelectric nanocomposites - ["Hongjian Zhang", "Yiqun Wu", "Wenting Jin", "two others (RG visible)"] (Materials Science in Semiconductor Processing, 2023)
Piezoelectric energy harvesting devices offer great potential for diverse electronic applications.

Flexible Battery‐Free Wireless Sensor Array Based on Functional Gradient‐Structured Wood for Pressure and Temperature Monitoring - Gaoqiang Zhang, Peng Li, Xue Wang, Yushu Xia, Jin Yang (Advanced Functional Materials, 2023)
Abstract Approximately 4.5% to 7.0% of hospitalized patients suffer from pressure ulcers. Mitigating risks for pressure ulcers through sensors remains a challenge and a high requirement. A simple, low‐cost, battery‐free, multi‐parameter passive wireless flexible sensor (MPWFS) for all‐around pressure and temperature monitoring to prevent pressure ulcers is developed. The pressure sensing unit is fabricated with functional gradient‐structured balsa wood and has high sensitivity of 0.34 kPa −1 with a wide detection range of 0–20 kPa. The temperature sensing unit, which is 0.4 mm × 0.2 mm, is embedded in the surface of the pressure sensing unit, enabling temperature monitoring with a resolution of 0.1 °C. The flexible Radio Frequency energy‐harvesting unit, data acquisition, and processing, as well as Bluetooth‐Low‐Energy wireless transmission, are integrated within a 20 mm × 20 mm unit. It acquires continuous temperature and pressure da ta without a battery at any position more than 1 m away from the power transmitter. Moreover, the combination of the sensor array design with a mobile terminal provides the MPWFS's various benefits, including tracking changes in the supine posture, warning about pressure ulcers, and monitoring falls out of bed. This study presents a new method for long‐term bedridden patient care.

Wireless, Flexible, Ionic, Perspiration‐Rate Sensor System with Long‐Time and High Sweat Volume Functions Toward Early‐Stage, Real‐Time Detection of Dehydration (Adv. Funct. Mater. 44/2023) - Satoko Honda, Ryuki Tanaka, Guren Matsumura, Naruhito Seimiya, Kuniharu Takei (Advanced Functional Materials, 2023)

Machine learning assisted hybrid transduction nanocomposite based flexible pressure sensor matrix for human gait analysis - Nadeem Tariq Beigh, Faizan Tariq Beigh, Dhiman Mallick (Nano Energy, 2023)

Waterproof conductive fiber with microcracked synergistic conductive layer for high-performance tunable wearable strain sensor - Shiyin Yang, Wenke Yang, Rui Yin, Hu Liu, Hongling Sun, Caofeng Pan, Chuntai Liu, Changyu Shen (Chemical Engineering Journal, 2023)

High-strength MXene sheets through interlayer hydrogen bonding for self-healing flexible pressure sensor - Yongfa Cheng, Yimei Xie, Honghao Cao, Li Li, Zunyu Liu, Shuwen Yan, Yanan Ma, Weijie Liu, Yang Yue, Jianbo Wang, Yihua Gao, Luying Li (Chemical Engineering Journal, 2023)

A P(VDF-TrFE) nanofiber composites based multilayer structured dual-functional flexible sensor for advanced pressure-humidity sensing - Kaiqi Guo, Song Gao, Yang Li, Junli Yin, Wenjing Yue, Songfang Zhao, Chunwei Zhang, Jianwen Liu, Shouliang Li, Shixiang Wu, Hao Kan (Chemical Engineering Journal, 2023)

A sparse-dense hierarchical structured conductive elastomer composites for highly sensitive and stretchable strain sensor - Jun Wang, Jing Lin, Kelin Pan, Kaibang Zhang, Hebai Zhang, Jin Dong, Dechao Hu, Zhixin Jia, Jianyi Luo (Chemical Engineering Journal, 2023)