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This study investigates the structural effects on the cross-plane thermal conductivity of Li4Ti5O12-based anode active material. Three structures are investigated: a basic structure consisting of LiBr/LiCl/Li4Ti5O12, polyvinylidene difluoride, and Super P (sample #1); a structure without Li4Ti5O12 (sample #2); and a structure without LiBr/LiCl (sample #3). Despite its high porosity level (77%), sample #1 exhibits higher thermal conductivity than sample #3 (64% porosity) in both air and vacuum conditions, potentially due to the extra structural bonding provided by LiBr/LiCl. The observed difference in cross-plane thermal conductivity between air and vacuum conditions provides insights into the configuration of the anode's active material in the heat transfer direction. The lower limit corresponds to the parallel thermal circuit configuration of active material and air, which is the product of the sample's porosity and thermal conductivity of air. Our analysis suggests that in sample #2, the anode's active material and air inside the pores demonstrate a more serial configuration, while in sample #3, they exhibit a more parallel configuration in the heat transfer direction. However, the thermal conductivity difference observed for sample #1 falls below the theoretical lower bound indicating significant thermal radiation within the pores. Furthermore, the in-plane thermal conductivity is predominantly controlled by the copper foil. Sample #2 exhibits the lowest in-plane thermal conductivity. This is attributed to the severe oxidization of the copper foil by LiBr/LiCl, which is confirmed by structure characterization. [ABSTRACT FROM AUTHOR]

We investigated the relationship between porosity and flexoelectricity for aluminum (Al)/polyvinylidene fluoride (PVDF) composites. Neat PVDF, composites of micron aluminum (μAl)/PVDF, and composites of nano aluminum (nAl)/PVDF were 3D printed, and the flexoelectric response was measured using a cantilever beam test setup. Voids (up to 72.4 mm3) were incorporated into the samples by decreasing the infill percent of the 3D printed material. We found that increasing the porosity via millimeter scale voids incorporated into the infill pattern decreased the average effective flexoelectric coefficient relative to the near full-density (100% infill) control samples. This contrasts with other studies that have shown increasing micron scale porosity increases the flexoelectric coefficient. In addition, we measured higher flexoelectric responses for nAl/PVDF than μAl/PVDF as well as for samples printed by the Hyrel 3D SR printer as opposed to the Ender 3 V2 printer. These results indicate that charge generation due to flexoelectricity can be altered by changing parameters such as porosity, particle size of inclusions, or manufacturing method. Smaller voids and fine particles can induce larger strain gradients than larger inhomogeneities, leading to increased flexoelectric coefficients. A competing effect is that more porosity leads to less materials, which can decrease the flexoelectric coefficient. [ABSTRACT FROM AUTHOR]

Additive incorporation into polymers can enhance properties, such as the dielectric constant and thermal conductivity. The improved properties of polymer composites have largely been attributed to aggregate and network formation, but the influence of material texture requires clarification. Herein, the relationship between the texture of composite materials and thermal conductivity was investigated based on the fractal nature of composites consisting of polyvinylidene fluoride (PVDF) with β-Si3N4 (SN) as a high-thermal-conductivity filler. The SN particle groups were found to contribute to the formation of thermal conduction paths in the composite material and, thus, improve the thermal conductivity. The characteristics of the particle group clusters involved in SN particle percolation were elucidated by analyzing the interactions between multiple particles as a function of the amount of each fractal dimension. In addition, based on the statistical relationships obtained from the multifractal analysis, the strengths of the interactions between particles during thermal conduction path formation were estimated. Overall, the texture of the SN/PVDF material was characterized by local particle group formation (self-assembly) and subsequent global particle group network construction (self-organization), depending on the amount of SN added. These results suggest that multifractal dimensions can be used as material design indices for the texture of polymer composites. [ABSTRACT FROM AUTHOR]

The limited improvement in discharge energy density (Ue) of polyvinylidene fluoride (PVDF) nanocomposites filled with low-dielectric-constant (εr) nanosheets has been addressed by using a superspreading layering strategy. The integration of highly aligned boron nitride nanosheets (BNNS) and well-dispersed BaTiO3@PEG (BT@PEG) nanoparticles into the PVDF matrix results in a significant enhancement, increasing Eb and εr by 52% and 64%, respectively, and achieving an Ue of up to 20.12 J cm−3. [ABSTRACT FROM AUTHOR]

Aluminum hydride (AlH3) is considered as one of the most promising high-energy hydrogen-storage fuels. Various studies have been conducted to improve its thermostability and compatibility with polar plasticizers. As frequently reported, polyvinylidene difluoride (PVDF) has inherent advantages as a coating agent of AlH3 to improve its stability and compatibility. However, its optimal content and the interaction mechanisms with AlH3 are still not clear. In this study, AlH3 crystals coated with different contents of PVDF have been prepared and their thermochemical properties have been analyzed by using VST and DSC/TG techniques. In addition, the effect of PVDF on decomposition reaction pathways of AlH3 and AlH3@Al2O3 have been investigated using RMD simulations. It has been found that if the content of PVDF is less than 8%, it may enhance the stability of AlH3. However, once the content is over 20%, the decomposition of AlH3 would be promoted. In addition, even if PVDF can inhibit the initial dehydrogenation of AlH3 during the induction period, once the fast exothermic reactions initiate, the corresponding energy barriers would be lowered with faster H2 release. [ABSTRACT FROM AUTHOR]

In this study, a piezoelectric nanogenerator (PENG) based on multilayer composite fiber had good and stable piezoelectric output performance, which could realize biomechanical energy collection and human movement monitoring. The polyvinylidene fluoride‐hexafluoryl propylene (P(VDF‐HFP)) composite fiber doped with MXene was used as a promising piezoelectric functional layer (MPFP). By electrospinning, P(VDF‐HFP) composite fiber was constructed by alternating electrospinning with polyurethane (TPU) nanofibers layer by layer. The adoption of MXene as a functional filler promoted the transformation of P(VDF‐HFP) from α to piezoelectric β‐crystal, the piezoelectric β‐crystal content of P(VDF‐HFP) increased, and the dielectric properties and polarization levels were enhanced. At the same time, the multi‐layer structure design improved the piezoelectric sensitivity and mechanical properties of the composite fiber, and the composite fiber was more flexible and had longer tensile strain. With excellent dielectric and mechanical properties, 3MPFP/TPU/3MPFP/TPU multilayer composite fibers showed piezoelectric sensitivity of 10.88 V/kPa. Under the action of palm pressing, the PENG generated an open circuit voltage of 25 V, and the voltage signal of the device under different motion forms had specific characteristics such as peak value, frequency, and shape, which could be used to realize the analysis of human motion forms. This study provided an efficient, simple, and creative new idea for the application of flexible energy storage electronic devices, PENGs, and piezoelectric sensors. [ABSTRACT FROM AUTHOR]

Though polyvinylidene fluoride (PVDF) is widely‐used binder for conventional lithium‐sulfur (Li–S) batteries, it still encounters challenges of severe electrode fracture involved by drastic volume change upon repeating cycling, and lack of extended‐functions like trapping dissolved polysulfides and smoothing Li+ transfer. Herein, a methodology of grafting sulfophilic hydrogen‐bond donor and lithiophilic hydrogen‐bond acceptor to the polymer binder (named as PIL), function as gear teethes and tooth spaces, is reported. When cracks occur, the engaged gears driven by dynamic hydrogen bonds are separated, which are spontaneously reformed owing to the automatic meshing of gears, and thus accelerate the healing of cracks. At the molecular level, the synergetic effect of sulfophilic hydrogen‐bond donor and lithiophilic hydrogen‐bond acceptor enables polysulfides immobilization through "push‐pull effect", facilitating the subsequent redox kinetics. Accordingly, the cross‐link network of hydrogen bonds endows the elaborated designed polymer binder with strong adhesive strength and rapid Li+ migration. Attributed to these beneficial properties, the PIL‐based sulfur cathode exhibits excellent rate performance and superior cycling durability (an ultralow capacity fading rate of 0.062% per cycle over 800 cycles at 2 C). Even with high sulfur loading of 9.27 mg cm−2, a high areal capacity of 8.71 mAh cm−2 can be achieved, verifying its potential application. [ABSTRACT FROM AUTHOR]

To separate the oil/water mixtures, polyvinylidene fluoride (PVDF) nanofiber mats were produced using electrospinning. Additionally, PVDF films were made using the solvent evaporation method, and the effectiveness of their separation was evaluated against that of nanofiber mats. By choosing oxygen‐functionalized graphene (with HNO3) as a nano reinforcement, the hydrophobic properties of the PVDF materials made using both techniques were transformed into hydrophilic ones. It has been determined how the characteristics of the solution (viscosity, conductivity, molecular weight, surface tension, and contact angle) relate to the diameter of the nanofiber. Fourier transform infrared spectroscopy‐attenuated total reflection (FT‐IR/ATR), x‐rays diffraction (XRD), scanning electron microscope, thermogravimetric analyses (TGA)/DTG, and differential scanning calorimetric (DSC) have been used to study the chemical and crystal structures, morphology, and thermal behavior of PVDF materials. The addition of oxygen‐functionalized graphene was found to cause a peak in the PVDF composites' FT‐IR/ATR spectrum, roughly in the wavenumber 1400 cm−1, which was identified as the C‐OH bending vibration. Together with the shift in peak strengths, the lack of a discernible shift in the PVDF peak location in the XRD patterns indicates that the addition of oxygen‐functionalized graphene has caused a phase transition in the PVDF in the semi‐crystal structure. Surface hydrophobicity has also been measured using contact angle measurements. The addition of oxygen‐functionalized graphene has been seen to decrease the PVDF's contact angle, resulting in the development of a hydrophilic characteristic. These PVDF‐based materials' oil/water separation capabilities have also been evaluated. PVDF composite films were not as effective as PVDF nanofiber mats with oxygen‐functionalized graphene in the studies to separate the oil/water mixtures. The permeate flux value was determined to be 240 Lm−2 h−1, and the oil/water separation efficiency of nanofibers containing 10% (m/m) PVDF534000 combined with oxygen‐functional graphene was found to be 99%. [ABSTRACT FROM AUTHOR]

Thin composite films hold great promise for microwave devices for microwave absorption. This work mainly focuses on the investigation of the microwave absorption and mechanical studies of a composite thin film of activated carbon and manganese ferrite as conductive fillers within a polyvinylidene fluoride (PVDF) matrix. The production of activated carbon was successfully accomplished using a pyrolysis technique. Composite films consisting of polyvinylidene fluoride (PVDF) and activated carbon‐manganese ferrite were fabricated using a solution blending method. The composite films maintained a consistent concentration of activated carbon at 5 wt%. The characterization of the materials was conducted using scanning electron microscopy and X‐ray diffraction. The composite consists of 3 wt% of MnFe2O4 and 5 wt% Activated carbon/PVDF showed exceptional absorption properties and achieved a minimum reflection loss of around −38 dB at a frequency of 8–12 GHz at a thickness of 2 mm. Significantly, the composite film exhibited a greater tensile strength than the PVDF film. The results of our study highlighted the enhanced microwave absorption and economical manufacturing technique for producing composite films. These films exhibit promising microwave‐absorbing properties in stealth applications. Highlights: A facile strategy to fabricate thin film PVDF composites was proposed.Novel activated carbon was synthesized to enhance the conductivity.Achieved reflection loss of around −38 dB at a frequency of 8–12 GHz.Synergistic effects of fillers enhanced dielectric and magnetic losses.Exhibited efficient mechanical performance and microwave absorption. [ABSTRACT FROM AUTHOR]

Promoting safer and more cost‐effective lithium‐ion battery manufacturing practices, while also advancing recycling initiatives, is intrinsically tied to reducing reliance on fluorinated polymers like polyvinylidene difluoride (PVDF) as binders and minimizing the use of hazardous and expensive solvents such as N‐methyl pyrrolidone (NMP). In pursuit of this objective, olefin‐ and rubber‐based polymers have been investigated as promising alternatives for binder materials in high‐energy Ni‐rich LiNixCoyMnzO2 (NCM, x≥0.8) cathodes for lithium‐ion batteries (LIBs). Alternative binders such as polyisobutylene (PIB), poly(styrene‐butadiene‐styrene) (SBS), nitrile butadiene rubber (NBR), and its hydrogenated version (HNBR) offer versatile solutions. These polymers can be dissolved in industrial solvents, such as toluene, and have been further processed into homogeneous cathode slurries, thus facilitating the manufacturing of high‐energy Ni‐rich NCM cathodes for lithium‐ion batteries. The evaluation of NCM811 cathodes obtained from PIB, SBS, NBR, and HNBR has involved a thorough assessment of their physical and chemical properties, electrochemical performance, and production expenses, compared with NCM811 cathodes based on PVDF. Notably, cathodes employing PIB and HNBR have exhibited outstanding qualities, showcasing high specific capacity and remarkable electrochemical stability akin to PVDF‐based counterparts. Furthermore, the alternative binders′ superior adhesion, elasticity, and thermal stability have facilitated obtaining uniform and mechanically stable cathode films. Furthermore, using toluene, with its low vapor pressure, has significantly reduced energy costs associated with drying processes, thereby enhancing the overall cost‐effectiveness of the NCM811 cathodes. [ABSTRACT FROM AUTHOR]

This study examines the polyvinylidene fluoride (PVDF) ultrafiltration membrane impregnated with the copper acetate monohydrate/nickel chloride/thiourea (CuNit) nanoparticle through its physical properties, chemical properties, water flux, humic rejection, and antifouling properties against peat water. The ultrafiltration membrane was fabricated via phase inversion by blending CuNit nanoparticles (1, 3, and 5 wt/wt PVDF %) and PVDF (16 wt %) in N‐Methyl‐2‐pyrrolidone (NMP, 42 wt %) as the solvent. The humic rejection and fouling test are conducted using peat water collected from the Beladin water treatment plant. As a result, M03, which has 1 wt/wt PVDF % of CuNit nanoparticle, gives a better result of pure water flux, humic rejection, and fouling recovery rate with a value of 82 L/m2 h, 93 %, and 40 % compared to pristine PVDF membrane. The fouling of M03 recorded a low total rate of fouling (76 %) that is caused by high reversible fouling and low irreversible fouling with a value of 0.16 and 0.59, respectively, compared to the pristine PVDF membrane. In conclusion, due to the agglomeration that occurs in the further addition of CuNit nanoparticles, coating or encapsulation must be done to improve the stability of nanoparticles and reduce the leach‐out problem as well as provide a good distribution between the nanoparticle and casting solution during the membrane fabrication. [ABSTRACT FROM AUTHOR]

With the rapid advancement in sensor technologies, triboelectric nanogenerators (TENGs) have emerged as a promising sustainable power source for intelligent electronics. Herein, fabricated a novel 3‐aminopropyltriethoxysilane (core) and 2,2‐bis(hydroxymethyl)butyric acid (monomer)‐based hyperbranched polyester by facile single‐step polycondensation technique generation 2 (Si‐HBP‐G2). Further, a new class of polyvinylidene fluoride (PVDF) and different weight percentages (0, 5, 10, 15, and 20 wt%) of Si‐HBP‐G2 hybrid fiber blends are prepared by traditional electrospinning technique. The as‐prepared Si‐HBP‐G2 and its blends are well characterized using SEM/EDS, FTIR, NMR, and XRD studies. The influence of Si‐HBP‐G2 content on triboelectric performance in terms of the open circuit potential (VOC) and short circuit current (ISC) is evaluated using aluminum (Al) as a counter electrode. Among them, 15 wt% of Si‐HBP‐G2/PVDF hybrid fiber mat (PG2‐15) exhibits superior electrical performance. Which is almost increased 5.9 times (22–130 V) of VOC and 4.9 times (0.71–3.5 µA) of ISC than PVDF fiber mate. These results reveal the significance of Si‐HBP‐G2 in the triboelectric performance. The optimized TENG device (PG2‐15/Al‐TENG) exhibits a peak power density of 0.2 Wm−2 at 100 MΩ external load. Finally, the PG2‐15/Al‐TENG practically demonstrates real‐time application energy harvesting applications such as powering 100 LEDs and a stopwatch. [ABSTRACT FROM AUTHOR]

In the present study, the possibility of recovering water in a car wash station was presented. The resistance of automotive coatings to washing water recovered at 50% and 70% from wastewater generated at car wash was tested. Wastewater treatment was carried out by ultrafiltration (UF) using tubular polyvinylidene fluoride (PVDF) membranes (100 and 200 kDa) manufactured by the PCI company. The membranes retained oil contamination, suspended solids, and over 60% of surfactants. For comparison, the 0.5% Turbo Active Green solution, used at professional car washes, was also applied in paint resistance studies. The tested solutions washed the painted surfaces of samples taken from car doors for 8 days. The resistance of automotive coatings to washing solutions was assessed by measuring gloss, Log Haze, RIQ, and Rspec parameters. Scratch resistance was also assessed. The results obtained in the current study indicated that the use of water recovered from wastewater did not deteriorate the quality of the car paint coating. [ABSTRACT FROM AUTHOR]

In this study, by combining the polymers of polyvinylidene fluoride (PVDF) and 10,12-pentacosadinoic acid and adding the zinc oxide (ZnO) nanoparticles to their solution, three component composite nanofibers were electrospun and their thermo-chromic reversibility were investigated. Different amounts of ZnO nanoparticles based on the weight of PVDF were added to the mixture of PVDF/PDA (polydiacetylene) polymers and composite nanofibers were produced by electrospinning method. Adding ZnO to the electrospinning solvent affects nanofibers structural morphology and helps formation of beads in the electrospun nanofibers in comparison with that of PVDF/PDA sample. The crystal structure of the samples and the chemical changes in the structure of the polymers indicate that the addition of ZnO nanoparticles increases the stability of the nanofiber structure against heat and chromic change. Samples containing more than 2% ZnO with different UV irradiation times were reversible up to 140 °C. The best thermo-chromic reversibility of the PVDF/PDA/ZnO composite nanofibers could be obtained by sample containing 3% ZnO nanoparticles where the minimum irreversible temperature with an UV irradiation time of 5 min for this sample is 170 °C. [ABSTRACT FROM AUTHOR]

Thick electrodes represent an effective approach for augmenting energy density of batteries. However, their increased thickness invariably leads to longer electron and ion transport distance, limiting the utilization of active material and hindering practical application. Herein, an electron‐conducting‐enhanced and ion‐conducting‐enhanced strategy is presented for fabricating ultrahigh loading electrodes via constructing an interlaced 3D network. Carbon nanotubes (CNTs) serve as extended electron pathways. Different from the polyvinylidene fluoride binder which needs to be dissolved into molecules for preparing electrode, polytetrafluoroethylene (PTFE), however, exists as a separate phase inside the electrode, thus can become the extended pathways for electrolyte elongating due to its strong affinity to organic electrolyte. Note that based on the synergistic effect between CNT and PTFE, the latter can exhibit a form of long‐distance extension fibers rather than agglomeration. Finally, a LiFePO4 electrode with a record‐high loading of 141 mg cm−2 is successfully prepared. This electrode exhibits outstanding area capacity (20.7 mAh cm−2 at 0.2 C) and cycling stability with impressive energy density of 224 Wh kg−1 and 517 Wh L−1 in a full cell (graphite anode). The findings present a novel strategy for achieving high energy density in lithium‐ion batteries using existing material systems. [ABSTRACT FROM AUTHOR]

The blast pressure acting on the borehole wall is the basis of the dynamic analysis of rock blasting. The history of blast-induced borehole wall pressure (BWP) is difficult to measure owing to the complex interaction between the blasting load and the borehole wall, and the limitations of the general test system. In this work, the complete history of BWP under air-deck charge was measured for the first time, and the stress-response process was analyzed. PVDF (polyvinylidene fluoride) gages and a charge mode for the test circuit were employed. To improve the testing accuracy, the matching relationships among the parallel capacitor, the equivalent capacitance of PVDF gages, and the parasitic capacitance of the coaxial cable were effectively addressed. The experimental data within the span of 0–0.65 m from the explosive cartridge center show that there are two obvious peaks in the complete history of BWP, the first is a μs-level air shockwave load, followed by a ms-level explosion gas load. The peak of BWP is dominated by the peak of explosion gas (Pg) within the scope of about 0–0.35 m from the explosive cartridge center, while is mainly determined by the peak of air shockwave (Ps) in a farther range. The specific impulse distribution suggests that the explosion energy is mainly consumed in the area within the range of about 0–0.25 m from the explosive cartridge center. The strain rate in the borehole wall induced by air shockwave demonstrates a dynamic response (range of 131.9 ~ 2922.6 s−1), while indicating a quasi-dynamic loading (range of 0.1 ~ 2.1 s−1) when induced by the explosion gas. The findings contribute to expanding the understanding of the stress characteristics of the air shock wave and explosion gas and provide accurate initial loads for numerical simulation related to rock blasting of non-fluid–solid coupling. Highlights: The complete history of borehole wall pressure under air-deck charge was accurately measured by solving the capacitance matching in the test circuit for charge mode. The entire stress response process of the borehole wall rock is revealed. The specific impulse distribution of air shock wave and explosion gas along the borehole axis is obtained. The stress characteristics of borehole wall induced by air shockwave and explosion gas are compared. [ABSTRACT FROM AUTHOR]

Flexible sensors are in great demand in the field of wearable electronics because of their good softness, stretchability, breathability and structural elasticity. Besides, polyvinylidene fluoride (PVDF) and its copolymers have been considered as promising piezoelectric materials for advanced sensing and excellent biocompatibility. Electrospinning is simple, low cost, and scalable technology that can be used to fabricate PVDF-based nanofibers applied in long-term monitoring or human–computer interaction. In this paper, we initially presented the basic process for preparing PVDF nanofibers, followed by a systematic elaboration on extended electrospinning techniques to facilitate more in-depth research on PVDF-based nanofibers. Then, the enhancements methods were summarized, complemented by some reinforcing mechanisms, novel structures and some solutions for filler agglomeration. Furthermore, the latest applications as wearable sensors were introduced. Potential difficulties, problems and perspectives are also discussed. We hope that this article can help researchers better understand this field and push it to a higher level. [ABSTRACT FROM AUTHOR]

This study proposes a greener approach for electrode preparation using cyrene, a bio‐derived and fully biodegradable green solvent, as a potential N‐methyl‐2‐pyrrolidone substitute for fabricating high‐performance nickel–manganese–cobalt oxide (NMC88) lithium‐ion battery cathodes by screen‐printing method. This study also investigates the replacement of the polyvinylidene fluoride (PVDF) binder with Arkema Kynar HSV1810 homopolymer, a crucial substitution for enabling the effective utilization of cyrene, addressing the solvent inadequacy associated with PVDF dissolution. Alongside the ink formulation, the electrode preparation process is optimized by investigating current collector surface treatments using plasma, ultraviolet, and citric acid to enhance substrate wetting, leading to improved printability, adhesion, and cathode layer performance. Cyrene‐based screen‐printed NMC cathodes are analyzed using various characterization techniques, including microscopy, optical profilometry, scanning electron microscopy, adhesion tests, and electrochemical performance tests for assembled batteries. The results demonstrate that cyrene‐based slurries exhibit improved wettability and adhesion on substrates/current collectors when surface treatments are applied. Furthermore, the electrochemical performance of cells based on surface‐treated NMC88 electrodes prepared with cyrene shows adequate cycling performance and rate capability. As a proof of concept, the study presents an alternative green and sustainable approach for electrode preparation in screen‐printed Li‐ion batteries using cyrene. [ABSTRACT FROM AUTHOR]

The binder plays a crucial role in binding the solid electrode components and fixing them to the current collector, ensuring good contact and transformation. The high‐energy‐density cathode poses several challenges for the Polyvinylidene fluoride (PVDF) binder, such as high electrode potential, mass loading, and binding force. Although various new binders are proposed to optimize the electrochemical performance of cathode, the design focus and mechanisms often lack universality. This study introduces a design strategy for the cathode binder from the perspective of molecular structure design. The performance of the binder is optimized by adjusting the soft‐hard and hydrophilic‐hydrophobic balances of the polymer, and the effectiveness of this strategy is verified in the LiCoO2 (LCO) system. The optimized copolymer binder improves the cycling stability of the LCO electrode under high load and low binder content conditions and even achieves stable operation at a high charging voltage of 4.6 V. The mechanism for improving the performance of LCO electrodes is that the optimized binder stabilizes the electrode structure, the active material particle structure, and the active material interface. This design strategy provides a valuable reference for customizing cathode binders. [ABSTRACT FROM AUTHOR]

The interface issue concerning lithium dendrite formation between the separator and electrode remains a significant impediment to the further advancement of lithium‐ion batteries (LIB). Due to the inadequate interface compatibility between the conventional polyolefin separator and the electrode, there is a propensity for lithium dendrite growth. In this work, the surface of the polyethylene (PE) separator is coated with polyvinylidene fluoride (PVDF) gel using a simple phase transformation method, resulting in the preparation of a composite separator consisting of PE and PVDF. The results demonstrate an enhanced interface compatibility following the introduction of the gel layer, with a polarization voltage as low as 0.14 V observed after 250 h of cycling. Additionally, the ionic conductivity of the PE/PVDF composite separator (1.77 mS cm−1) is enhanced, attributed to the incorporation of F functional group in PVDF gel, which could facilitate the formation of a rapid ion transport pathway through the interaction between F functional group and Li+. After the introduction of the gel layer, the discharge capacity of the battery after 250 cycles measures ~1.28 mAh, with a mere 27% decay in capacity. This study presents a novel concept for the design of composite separator in LIB. [ABSTRACT FROM AUTHOR]

Silicon (Si) anode is of considerable interest in Li‐ion batteries due to its high theoretical capacity (4200 mAh g−1), abundant reserves in the earth, and environmentally friendly nature. Although Si anode has significant advantages, the electrode is prone to cracks due to large volume changes in its structure during discharge cycles in Li‐ion batteries. Rapid capacity degradation occurs as a result of deterioration of the structural integrity of the electrode. Although binders are known to contribute to improving the electrochemical performance of anode materials, polyvinylidene fluoride (PVdF) used in commercial Li‐ion batteries cannot maintain the mechanical stability of the Si anode during cycles due to weak Van der Waals interactions, which also dissolves in the flammable, explosive and volatile solvent N‐Methyl‐2‐pyrrolidone (NMP). In this study, low cost, sustainable and environmentally green psyllium gum (PG) was extracted from psyllium husk and tested for the first time as a water‐soluble binder for Si anode. According to galvanostatic charge/discharge tests, the Si‐PG anode exhibits a capacity of 1415 mAh g−1 after 100 cycles at a voltage range of 0.01–1.5 V and current density of C/2, which is almost 3 times higher than the Si‐PVdF anode (494 mAh g−1). [ABSTRACT FROM AUTHOR]

In this work, we designed a novel polyvinylidene fluoride (PVDF)@DNA solid polymer electrolyte, wherein DNA, as a plasticizer-like additive, reduced the crystallinity of the solid polymer electrolyte and improved its ionic conductivity. At the same time, due to its Lewis acid effect, DNA promotes the dissociation of lithium salts when interacting with lithium salt anions and can also fix the anions, creating more free lithium ions in the electrolyte and thus improving its ionic conductivity. However, owing to hydrogen bonding between DNA and PVDF, excess DNA occupies the lone pairs of electrons of the fluorine atoms on the PVDF molecular chains, affecting the conduction of lithium ions and the conductivity of the solid electrolyte. Hence, in this study, we investigated the effects of adding different DNA amounts to solid polymer electrolytes. The results show that 1% DNA addition resulted in the best improvement in the electrochemical performance of the electrolyte, demonstrating a high ionic conductivity of 3.74 × 10−5 S/cm (25 °C). The initial capacity reached 120 mAh/g; moreover, after 500 cycles, the all-solid-state batteries exhibited a capacity retention of approximately 71%, showing an outstanding cycling performance. [ABSTRACT FROM AUTHOR]

Although the high‐energy Ni‐rich layered cathodes suffer from undesirable surface reactions with the electrolyte, the polyvinylidene fluoride (PVDF) binder has a limitation on surface stabilization because of its weak affinity and low adhesion/cohesion. Here, it is demonstrated that the novel fluorine‐free and hydroxyl‐rich siloxane nanohybrid (SNH) binder can enhance the electrochemical performances of LiNi0.8Mn0.1Co0.1O2 cathode (NCM811) via successful surface stabilization. The high silanol content in the SNH binder enhances the affinity to both NCM811 and conductive agent, facilitating uniform electron/ion pathways with high mass loading, improved shear thinning, and superior mechanical properties. Moreover, the fluorine‐free organic‐inorganic hybrid structure prevents the dissolution of transition metals, active material structural changes, and electrolyte interaction, leading to greatly enhanced cyclability of the SNH‐based NCM811 electrode (≈81.9% in half‐cell; ≈87.82% in full‐cell after 200 cycles) compared to PVDF‐based NCM811 electrode (≈58.8% in half‐cell; ≈61.24% in full‐cell after 200 cycles). Various analyses also indicate that the application of the fluorine‐free SNH binder successfully stabilizes both the surface and bulk structure of the NCM811 cathode during charge/discharge. The binder design represents a straightforward yet highly effective approach to achieving remarkably prolonged cyclability in lithium‐ion batteries, surpassing the performance of other fluorine‐based or polymer‐based binders. [ABSTRACT FROM AUTHOR]

Designing composite gate dielectrics tailored by incorporating inorganic perovskite nanofillers into a polymer matrix to develop flexible low‐voltage transistors can be challenging because homogeneous dispersion of nanomaterials in the matrix is difficult to achieve; thus, degradation of the electrically insulating properties of nanocomposite layers is often observed. In this study, nanocomposite dielectrics are presented that consist of 2D Ba5Ta4O15 nanosheets (BTO NSs) for the first time. Perovskite BTO is introduced using the Langmuir–Blodgett method to construct a precise and pinhole‐free interface for the homogeneous assembly of 2D nanosheets. Its high k value and ferroelectric properties, which arise from the perovskite structure, can be harnessed to achieve attractive polarization and remarkable electronic properties. The 2D BTO NSs can also be utilized as phase crystallization fillers to enhance the ferroelectric properties of polyvinylidene fluoride (PVDF). Additionally, the multilayer PVDF/perovskite nanosheet hybrid dielectric, which reaches an unprecedentedly high dielectric constant of 22.4, exhibits effective dielectric relaxation related to the interfacial induced ferroelectric polarization and decisive negative‐capacitance response. [ABSTRACT FROM AUTHOR]

The notch effect of semicrystalline PVDF was investigated using U- and V-notch geometries with different depths, and tensile tests were performed at 23 °C using the DIC technique and FEA. Both unnotched and notched dumbbell-shaped specimens were subjected to tensile loading with the DIC technique to obtain mechanical curves and strain maps. The experimental data were compared to a numerical model, analyzing both global mechanical curves and local strain maps around the notch region to assess the accuracy of the simulations. The results demonstrated that the geometry and depth of the notch influence the mechanical behavior of PVDF, presenting a decrease in load and displacement compared to unnotched specimens. This aspect was corroborated by strain maps, which showed the increase in the local strain around the notch tip. For FEA, the global analysis indicated a good correlation with experimental results, and the local analysis demonstrated a reasonable agreement in strain map results within 0.5 mm of the notch neighborhood. Overall, the DIC technique and FEA provided a reliable evaluation of notch behavior on the PVDF used as pressure sheaths with reasonable precision. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have been widely applied in electronic communication, transportation, aerospace, and other fields, among which separators are vital for their electrochemical stability and safety. Electrospun polyvinylidene fluoride (PVDF)-based separators have a large specific surface area, high porosity, and remarkable thermal stability, which significantly enhances the electrochemistry and safety of LIBs. First, this paper reviewed recent research hotspots and processes of electrospun PVDF-based LIB separators; then, their pivotal parameters influencing morphology, structures, and properties of separators, especially in the process of electrospinning solution preparation, electrospinning process, and post-treatment methods were summarized. Finally, the challenges of PVDF-based LIB separators were proposed and discussed, which paved the way for the application of electrospun PVDF-based separators in LIBs and the development of LIBs with high electrochemistry and security. [ABSTRACT FROM AUTHOR]

As surface wear is one of the major failure mechanisms in many applications that include polymer gears, lifetime prediction of polymer gears often requires time-consuming and expensive experimental testing. This study introduces a contact mechanics model for the surface wear prediction of polymer gears. The developed model, which is based on an iterative numerical procedure, employs a boundary element method (BEM) in conjunction with Archard's wear equation to predict wear depth on contacting tooth surfaces. The wear coefficients, necessary for the model development, have been determined experimentally for Polyoxymethylene (POM) and Polyvinylidene fluoride (PVDF) polymer gear samples by employing an abrasive wear model by the VDI 2736 guidelines for polymer gear design. To fully describe the complex changes in contact topography as the gears wear, the prediction model employs Winkler's surface formulation used for the computation of the contact pressure distribution and Weber's model for the computation of wear-induced changes in stiffness components as well as the alterations in the load-sharing factors with corresponding effects on the normal load distribution. The developed contact mechanics model has been validated through experimental testing of steel/polymer engagements after an arbitrary number of load cycles. Based on the comparison of the simulated and experimental results, it can be concluded that the developed model can be used to predict the surface wear of polymer gears, therefore reducing the need to perform experimental testing. One of the major benefits of the developed model is the possibility of assessing and visualizing the numerous contact parameters that simultaneously affect the wear behavior, which can be used to determine the wear patterns of contacting tooth surfaces after a certain number of load cycles, i.e., different lifetime stages of polymer gears. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvesters (PEHs) developed from electrospun polyvinylidene fluoride (PVDF) fibers offer flexibility and superior piezoelectric output, making them promising for self‐powered systems and sensors. Nonetheless, the electromechanical conversion efficiency of conventional electrospun PVDF fibers is impeded by their limited pressure‐strain range. Herein, elastic porous PVDF microspheres are introduced in‐situ via electrospinning to craft a piezoelectric membrane with higher compressive strain. The PVDF microspheres are uniformly embedded between the fibers in a sandwich fashion, and their dimension is easily tunable by varying spinning solution's concentration. Moreover, the micropores on the PVDF microspheres created by removing pre‐mixed SiO2 template not only elevates the β crystal content of PVDF to 82.19%, but also improves the compressibility, significantly boosting the piezoelectric output. The microsphere alloyed PVDF PEH delivers a piezoelectric output of 33.0 V and a power density of 8 μW/cm2, over 5.8 times that of conventional electrospun PVDF membrane, and can consistently charge lithium‐ion batteries. Our research unveils a novel strategic path to modify fiber structured PEHs, advancing their applications in self‐powered systems. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) with pyroelectric properties has demonstrated great potential in sensors, actuators and structural health monitoring. However, the low content of β phase and the secondary pyroelectricity induced by thermal expansion limit its pyroelectric performances for a broader range of applications. In this work, graphene nanoplatelets (GNP) that have excellent physical properties are added to PVDF to improve the matrix's pyroelectric properties. To fully take advantage of the reinforcements, PVDF composite films with functionally graded (FG) distribution of GNP fillers are prepared. The pyroelectric properties of the FG films that are subjected to different scenarios are experimentally tested and analyzed. Combining experiments and finite element simulation, the secondary pyroelectricity of the multi‐layered FG films is particularly investigated for the first time. Compared to uniform dispersion, FG distribution of the GNP has an obvious effect on the pyroelectric performances of the PVDF composites. The increase in the number of layers and the thickness of the outer layers is beneficial for the improvement of the pyroelectric performances. The FG films with higher GNP concentration in the outer layer exhibit more favorable pyroelectricity. The parametric study is envisaged to provide guidelines for the design and optimization of the FG‐GNP/PVDF composites with improved pyroelectric performances. Highlights: FG‐GNP is favorable for pyroelectricity and stability of PVDF composite films.GNP/PVDF composite films with more layers demonstrate superior pyroelectricity.Attributes of layers have significant effects on pyroelectric responses.Effects of factors associated with secondary pyroelectricity are quantitatively identified. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries compatible with a wide temperature range and long cycle lifespan show great application prospects but are greatly limited by the unstable electrode‐electrolyte interfaces and mismatched electrolytes. This report presents the pathway of succinamic acid (SA) additive‐induced built‐in trimodal molecular interaction for constructing sustainable aqueous zinc batteries. As confirmed, such trimodal molecular interaction falls into the following patterns: the binding state of the H─F bond between SA and polyvinylidene fluoride (PVDF) binder, the micellar aggregation state in aqueous electrolyte, and the spontaneous adsorption state at Zn anode–electrolyte interface. Benefiting from the above synergistic effect, the Zn electrode shows a highly reversible deposition/stripping behavior over the wide temperature range (−10–50 °C) when paired with the optimized electrolyte. Specially, an impressive 3530 h‐cycle lifespan of the Zn symmetrical cell is achieved at the conditions of 1 mA cm−2 and 1 mAh cm−2. Beyond that, significantly improved storage capability and cycle performance are demonstrated in both aqueous Zn‐MnO2 and Zn‐I2 batteries. Given the good balance between the working temperature range, ionic conductivity, and Zn2+ transfer number of this trace molecule‐mediated electrolyte, this design paradigm provides new insights into developing advanced aqueous batteries, including but not limited to zinc‐based systems. [ABSTRACT FROM AUTHOR]

The growing concern about thermal conductivity and electromagnetic shielding m electronic equipment has promoted the development of interfacial film materials. In this work, polyvinylidene fluoride (PVDF)/graphene composite films with different graphene contents were fabricated by high-energy ball milling, cold isostatic pressing, scraping and coating, successively. High-energy ball milling is beneficial to the dispersion of graphene powder, while cold isostatic pressing can greatly enhance thermal conductivity and mechanical strength by reducing the voids in the film and increasing the contact area of graphene sheets. The thermal conductivity, tensile strength and electromagnetic shielding properties of the films were carefully investigated and compared. It was demonstrated that the thermal conductivity increased from 0.19 W·m-1·K-1 for pure PVDF to 103.9 W·m-1·K-1 for the composite film with PVDF:graphene=l:3. Meanwhile the electromagnetic shielding efficiency can reach 36.55 dB. The prepared PVDF/ graphene composite films exhibit outstanding overall performance and have the potential for practical applications. [ABSTRACT FROM AUTHOR]

The utilization of piezoelectric nanogenerator (PENG) based on halide perovskite materials has demonstrated significant promise for energy harvesting applications. However, the challenge of synthesizing halide perovskite materials with both high output performance and stability using a straightforward process persists as a substantial obstacle. Herein, we present the fabrication of CsPbI3 nanorods (NRs) exhibiting highly uniform orientation within polyvinylidene fluoride (PVDF) fibers through a simple texture engineering approach, marking the instance of enhancing PENG performance in this manner. The resultant composite fibers showcase a short-circuit current density (Isc) of 0.78 μA cm-2 and an open-circuit voltage (Voc) of 81 V, representing a 2.5 fold increase compared to the previously reported highest value achieved without the electric poling process. This outstanding output performance is ascribed to the orientation of CsPbI3 NRs facilitated by texture engineering and dipole poling via the self-polarization effect. Additionally, the PENG exhibits exceptional thermal and water stability, rendering it suitable for deployment in diverse and challenging environmental conditions. Our findings underscore the significant potential of textured CsPbI3 NRs composite fibers for powering low-power consumer electronics, including commercial LEDs and electronic watches. [ABSTRACT FROM AUTHOR]

Among smart materials, piezoelectric polymeric materials have a relatively high electrical response to mechanical stimuli, and diacetylenes are highly sensitive to color-changing materials. In this study, by combining the polymers of polyvinylidene fluoride (PVDF) and 10,12-pentacosadinoic acid and adding 1, 2, 3, 6, 9, 12, 15 and 18% zinc oxide (ZnO) nanoparticles to their solution, three component composite nanofibers were electrospun and their piezoelectric property were investigated. The results show that the presence of zinc oxide caused the formation of beads in the structure, but it caused a decrease of about 45%-60% in the average diameter of the samples compared to the PVDF/PDA samples. In these samples, in the best case, the piezoelectric property showed a maximum increase of about 12 times compared to the PVDF/PDA sample. According to the other results of various tests, the sample containing up to 3% ZnO enhances the piezoelectric performance of the PVDF/PDA dual response nanofibrous piezoelectric-chromic sensors. [ABSTRACT FROM AUTHOR]

Different composition of mixed matrix membranes comprising Polyvinylidene fluoride (PVDF) as base polymer, Polyvinylpyrrolidone and Montmorillonite clay as additive was fabricated by phase inversion technique using N, N-Dimethylacetamide as a solvent. Furnished membrane samples were characterized by X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) for phase identification, functional group analysis, thermal stability, determination of surface morphology and textural features which show that PVP and MMT successfully modified PVDF membrane and resulted in PVDF/PVP/MMT mixed matrix membrane. Different membrane characteristics such as pure water flux, water content, porosity, shrinkage ratio, fouling recovery ratio and solute rejection were studied and calculated. The contemporary membrane (PPM5) having 5 wt. % of MMT represented the increase in pure water flux, porosity, and fouling recovery ratio from 13.8 Lm−2h−1, 33% and 52% to 19.8 Lm−2h−1, 85%, and 87%, respectively. The PPM5 also shows a reduction in shrinkage ratio from 19% to 7% and improved hydrophilicity which results in a solute rejection factor of 83% and 87% for Pb(II) and Cd(II), respectively, in comparison to other fabricated membranes. These membranes provide an economical and effective solution for wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, a mechanically flexible structure, a cuboctahedral metal‐organic polyhedra (MOP) Cu24[5‐(octyloxy) isophthalic acid]24 Cu (II) paddlewheel clusters coordinated with (5‐(octyloxy) isophthalate), resulting in significantly enhanced hydrolytic stability are prepared. It should be noted that CuMOP‐1 exhibits evenly and symmetrically distributed non‐polar long alkyl chains and polar hydroxy groups, facilitating self‐assembly into higher‐order structures reminiscent of amphiphiles. Furthermore, the resultant CuMOP‐1 undergoes a phase change at 150–160 °C as confirmed temperature‐dependent Raman spectroscopy (RS), thermogravimetric analysis and Differential Scanning Calorimetry (TGA‐DSC). The possible use of Cu‐MOP‐1 for capturing mechanical energy is demonstrated by creating a flexible hybrid piezoelectric‐triboelectric nanogenerator (HP‐TENG). The resultant CuMOP‐1@ Polyvinylidene fluoride(PVDF) membrane‐based HP‐TENG demonstrates enhanced triboelectric output voltage of 547.5 V, current density of 15.16 µAcm−2, and power density of 2.8 mWcm−2 due to its increased surface charge density and a substantial rise in the dielectric constant. Furthermore, the amphiphiles and phase change in CuMOP‐1 lead to ∽73% increase in voltage and 60% in current density of HP‐TENG in high‐temperature (140 °C) environments. HP‐TENG also exhibits exceptional temperature‐ and pressure‐sensing abilities, with sensitivities of 1.81 V°C−1 and 7.12 V°kPa−1, respectively, showcasing its feasibility over a wide range of temperatures and pressures. [ABSTRACT FROM AUTHOR]

A pressing need for high‐capacity anode materials beyond graphite is evident, aiming to enhance the energy density of Li‐ion batteries (LIBs). A Li‐ion/Li metal hybrid anode holds remarkable potential for high energy density through additional Li plating, while benefiting from graphite's stable intercalation chemistry. However, limited comprehension of the hybrid anode has led to improper utilization of both chemistries, causing their degradation. Herein, this study reports an effective hybrid anode design considering material properties, the ratio of intercalation‐to‐plating capacity, and Li‐ion transport phenomena on the surface. Mesocarbon microbeads (MCMB) possesses desirable properties for additional Li plating based on its spherical shape, lithiophilic functional group, and sufficient interparticle space, alongside stable intercalation‐based storage capability. Balancing the ratio of intercalation‐to‐plating capacity is also crucial, as excessive Li plating occurs on the top surface of the anode, eventually deactivating the intercalation chemistry by obstructing upper pores. To address this issue, electrospun polyvinylidene fluoride (PVDF) is introduced to prevent Li metal accumulation on the upper surface, leveraging its non‐conductive, polar nature, and high dielectric constant. By implementing these strategies, a LiNi0.8Co0.15Al0.05O2 (NCA)‐paired pouch cell delivers an outstanding energy density of 1101.0 Wh L−1, highlighting its potential as an advanced post‐LIBs with practical feasibility. [ABSTRACT FROM AUTHOR]

Obtaining a polymer nanocomposite with optimum viscoelastic, thermal, and biocompatibility properties is the main objective when designing nanocomposite systems with potential applications in tissue engineering. For this purpose, a blend of Polycaprolactone (PCL) and Polyvinylidene fluoride (PVDF) in an 85/15 weight ratio, along with a nanocomposite reinforced by nanohydroxyapatite (nHA) particles, is fabricated using a solution casting method in a mold. The impact of nHA content on crystallinity, viscoelastic properties, thermal stability, and the properties–structure relationship of nanocomposites is evaluated using scanning electron microscopy (SEM). Dynamic mechanical thermal (DMTA) analysis is used to determine the William–Landel–Ferry (WLF) constants and the effect of nHA on the nanocomposite's viscoelastic behavior. The PCL/15PVDF/0.5 wt% nHA exhibits the maximum thermal stability (40% residual char value) and 95% increase in storage modulus at 90 °C (rubbery region) in comparison with PCL/15PVDF blend. Water contact angle (WCA) and biocompatibility tests are conducted on the PCL/15PVDF blend and nanocomposite scaffolds to design appropriate nanocomposite systems with potential applications in tissue engineering. The high hydrophilic properties are assigned to PCL/15PVDF/0.5 wt% nHA with a WCA of 67.5°. Finally, in vitro cell culture confirmed 0.5 wt% nHA significantly improves cell adhesion and cytotoxicity with MG‐63 cells. [ABSTRACT FROM AUTHOR]

This study fabricated piezoelectric fibers of polyvinylidene fluoride (PVDF) with graphene using near-field electrospinning (NFES) technology. A uniform experimental design table U * 7 7 4 was applied, considering weight percentage (1–13 wt%), the distance between needle and disk collector (2.1–3.9 mm), and applied voltage (14.5–17.5 kV). We optimized the parameters using electrical property measurements and the Kriging response surface method. Adding 13 wt% graphene significantly improved electrical conductivity, increasing from 17.7 µS/cm for pure PVDF to 187.5 µS/cm. The fiber diameter decreased from 21.4 µm in PVDF/1% graphene to 9.1 µm in PVDF/13% graphene. Adding 5 wt% graphene increased the β-phase content by 6.9%, reaching 65.4% compared to pure PVDF fibers. Material characteristics were investigated using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), contact angle measurements, and tensile testing. Optimal parameters included 3.47 wt% graphene, yielding 15.82 mV voltage at 5 Hz and 5 N force (2.04 times pure PVDF). Force testing showed a sensitivity (S) of 7.67 log(mV/N). Fibers were attached to electrodes for piezoelectric sensor applications. The results affirmed enhanced electrical conductivity, piezoelectric performance, and mechanical strength. The optimized piezoelectric sensor could be applied to measure physiological signals, such as attaching it to the throat under different conditions to measure the output voltage. The force-to-voltage conversion facilitated subsequent analysis. [ABSTRACT FROM AUTHOR]

The rapid development of piezoelectric sensors has been studied extensively, owing to their good flexibility, wearability, high sensitivity and low cost. However, some inorganic materials with good piezoelectricity cannot make sensors flexible, and the organic materials with good flexibility have a weak output electrical signal and low strength. In order to explore and optimize the preparation technology of piezoelectric sensors, a BaTiO3@polyacrylonitrile (PAN)/poly(vinylidene fluoride) (PVDF) nanofibrous composite membrane (NCM) was prepared by cross-electrospinning technology and the central combination design (CCD) method. The morphology, structure, hydrophobicity, mechanical properties and piezoelectricity of the BaTiO3@PAN/PVDF NCMs were investigated. The BaTiO3@PAN/PVDF NCMs had the better hydrophobicity and mechanical properties compared with the pure PAN/PVDF NCM. The 5BaTiO3@PAN/PVDF NCM designed by CCD had a more uniform fiber diameter, and a more stable output voltage with a 46% improvement. With the help of cross-electrospinning technology and the CCD method, the NCM will be outstanding for the development of fabricating flexible wearable piezoelectric sensors. [ABSTRACT FROM AUTHOR]

In this study, a highly efficient, sensitive, and lightweight piezoelectric nanogenerator (PENG) is developed using graphene nanoribbons (GNRs) incorporated into the polyvinylidene fluoride (PVDF) matrix. Unzipping multi‐walled carbon nanotubes is an effective and scalable strategy for synthesizing graphene nanoribbons. The synthesized GNRs are employed to prepare nanometer‐scale piezoelectric polymer composite films showing higher piezoelectric performance than neat PVDF. The impact of GNR concentration in the PVDF matrix on the electroactive phase content and piezoelectric properties of the composites is systematically investigated. X‐ray diffraction (XRD) and Fourier‐transformed infrared spectroscopy (FT‐IR) analysis demonstrate an increase in the electroactive β and γ phases of PVDF by incorporating GNRs in the composites. With the optimized concentration of GNRs (1 wt%), the fabricated piezoelectric device can generate open‐circuit voltage and an output power density of 26 V and 16.52 µWcm2, respectively. It is also found that the PVDF‐GNR 1 nanogenerator can be used to generate electrical power by converting mechanical energy from different human activities such as wrist bending, palm tapping, and toe tapping. The findings indicate that (PVDF‐GNR 1) PENG can be applied in self‐powered portable and wearable electronic devices. [ABSTRACT FROM AUTHOR]

In this work, a new type of composite nanoparticles, 'pearl chain', was developed by linking titanium dioxide and silicon dioxide by polyacrylic acid polymer chains, and the prepared TiO2-PAA-SiO2 composite nanoparticles were analysed by SEM, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis, zeta potential, x-ray diffraction, etc. The success of this work was verified by the successful linking of TiO2-PAA-SiO2 composite nanoparticles.TiO2-PAA-SiO2 composite nanoparticles were analysed to verify the successful attachment of pearl chains. The obtained TiO2-PAA-SiO2 were subsequently blended in different ratios to prepare polyvinylidene fluoride (PVDF) ultrafiltration membranes. The membrane performance was tested by porosity and water contact angle measurements, scanning electron microscopy, as well as experiments using bovine serum proteins and MTBE interception. The results showed that when a certain amount of TiO2-PAA-SiO2 was added, the surface wettability, porosity and permeability of the prepared modified composite membranes were significantly improved, and the BSA adsorption rate was increased from 71.59% to 80.86%, and the retention rate of MTBE was increased by 77%, in addition to showing a better anti-pollution effect (FRR: 91.07%). It was finally concluded that the prepared membranes embedded with 1.0 wt.% TiO2-PAA-SiO2 nanofillers showed good overall filtration performance, better contamination resistance and remarkable durability. The present work successfully demonstrated the feasibility of using polyacrylic acid chemical chains to connect nanoparticles with different functions to prevent particle loss and substantially enhance membrane performance, which is valuable for bridging connection of composite nanoparticles and exploring the development of high-performance ultrafiltration membranes. [ABSTRACT FROM AUTHOR]

The crystal structure has a great influence on the dielectric and piezoelectric performance of poly(vinylidene fluoride) (PVDF). In this work, we prepared PVDF films with two typical crystalline phases (α and β). In situ Kelvin probe force microscopy (KPFM) and Piezoelectric force microscopy (PFM) were employed to investigate the responses of different PVDF crystalline phases to charge mobility, polarization, and piezoelectric properties. We used a homemade Kelvin probe force microscope (KPFM) to inject charges into the two crystalline phases to investigate the differences in the response of different crystalline phases of PVDF to electrical excitation on a microscopic scale. It was found that the α-phase has a lower charge injection barrier and is more susceptible to charge injection and that the α-phase is accompanied by a faster charge dissipation rate, which makes it easier to accumulate charge at the interface between the α-phase and β-phase PVDF. Moreover, the PFM polarization manipulation showed no change in the amplitude and phase diagram of the α-phase under ±10 V bias. In contrast, the β-phase showed a clear polarization reversal phenomenon and a significant increase in piezoelectric amplitude, which is consistent with its polar intrinsic properties. This study provides valuable insights into the multiphase contributions and a reference for designing advanced PVDF dielectrics. [ABSTRACT FROM AUTHOR]

In this study, novel polymer nanocomposite films based on polyvinylidene fluoride/polyacrylonitrile/zirconium dioxide (PVDF/PAN/ZrO2) were prepared using a solution casting technique. The structural modifications and morphological properties were analyzed by x‐ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). The obtained results verified the filler‐polymer interactions and uniform dispersion of the ZrO2 filler in the host polymers (PVDF and PAN). Thermal stability of up to 46% leftover residue for 30% ZrO2 nano‐filler loading in the blend polymer nanocomposite was analyzed by thermogravimetric analysis (TGA). The dielectric properties such as dielectric constant and dielectric loss values and impedance, Q‐factor, and AC conductivity were analyzed using an impedance analyzer. The decrement in impedance with increasing nano‐filler content with improved dielectric, thermal, Q‐factor, energy density and conductivity properties signifies the prepared novel PVDF/PAN/ZrO2 polymer nanocomposite as an effective material for flexible electronics applications. [ABSTRACT FROM AUTHOR]

The increased demand for high energy‐density batteries led to using lithium metal (Li) anode. However, safety issues associated with Li anode encouraged the researchers to use less reactive and safer electrolytes with higher electrochemical stability. High ionic conductivity (σ), wider electrochemical stability window, and higher mechanical strength alongside the ability to self‐heal possible structural damages were at the center of focus for developing efficient solid electrolytes. In this regard, we developed a group of solid polymer electrolytes (SPEs) with high σ and electrochemical stability. In this regard, bottle brush polyethylene glycol (bbPEG) was synthesized using a chain transfer reaction. Polynipaam (PNIPAAM) blocks were also incorporated into the structure to prepare a block copolymer based on PNIPAM‐bbPEG‐PNIMAM represented by the ABA structure. The block copolymer was then blended with polyvinylidene fluoride (PVDF) with the block copolymer to PVDF weight ratio of 7:2% and 25% bis(trifluoromethane) sulfonamide (TFSI) salt was added and the final mixture was UV‐cured. The results indicated that the final SPE possessed high ionic conductivity with a relatively high lithium‐ion transference number (tLi+$$ {t}_{Li+} $$) of 0.416 and the σ of 1.265 × 10−5 S/cm at 25°C. [ABSTRACT FROM AUTHOR]

Soft molecule‐based ferroelectrics with unique structural flexibility hold a promise for versatile applications of non‐volatile memory, imaging and photovoltaic devices. Except for few polymers (e.g., polyvinylidene fluoride, PVDF), it is challenging to exploit soft ferroelectric crystals toward free‐standing flexible photoactive devices. We here report a multiaxial soft molecule‐based ferroelectric, (n‐PA)2PbCl4 (1, where n‐PA+ is n‐pentylammonium), of which spontaneous polarization can be reversibly switched in both crystal and powder forms. Strikingly, single crystals of 1 have unusual structural flexibility and bendability, achieving the self‐standing bending with a bending radius of ~0.22 mm. Besides, the pyroelectric activities are also preserved for these single crystals after several bending cycles. Further, the bendable crystal‐based photodetector of 1 allows broadband photoactivities via the photo‐pyroelectric effect, covering a wide range from 405 to 940 nm spectral region, breaking through the limit of optical absorption bandgap. As the first study of bendable free‐standing photo‐pyroelectric detectors in ferroelectric crystals, our work sheds light on the assembly of flexible smart photoelectric devices. [ABSTRACT FROM AUTHOR]

Some studies have outlined the use of 3D-printed polyvinylidene fluoride (PVDF) composite-based solid intramedullary (IM) pins with tunable mechanical (tensile, compressive, flexural, and torsional) properties for orthopedic applications. But hitherto little has been reported on the effect of meta-structure induced in 3D-printed IM pins for canines from the mechanical properties' viewpoint. This study highlights the design, fabrication, and testing to mimic actual loading conditions in the canine femur bone on novel IM pin with meta-structure employed in different length zones (30%, 40%, and 50% of total gauge length) prepared by fused filament fabrication (FFF) of PVDF composite. The IM pin (of length 150 mm) has square threads (pitch 2 mm) at the distal end (ɸ7 mm, up to 60 mm in length), and V threads (pitch 1.5 mm) at the proximal end (ɸ6 mm, up to 30 mm in length). The IM pin was fabricated at the best setting (of the FFF process) suggested by the multifactor optimization (at nozzle temperature (Nt) 235°C, printing speed (Ps) 60 mm/s, and raster angle (RA) 45°). The result suggests that for the solid IM pins prepared at the optimized settings the observed elongation, peak load (PL), and break load (BL) during tensile and compressive loading were 4.83 mm, 968.40 N, 958.20 N, and 14.19 mm, 412.80 N, 371.52 N respectively. Whereas for 50% meta-structure the observed elongation, PL, and BL during tensile and compressive loading were 14.49 mm, 405.49 N, 90.20 N, and 13.23 mm, 243.20 N, 218.88 N respectively. For both tensile and compression loading (in this case study), better elongation was noticed for the FFF-based IM pin with 50% meta-structure and hence recommended for implantation in the canine femur bone. The results are also supported by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) based surface characteristics of the fracture sites. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are currently one of the most important energy storage devices for various applications. However, it remains a great challenge to achieve both high energy density and high-power density while reducing the production costs. Cells with three-dimensional electrodes realized by laser ablation are proven to have enhanced electrochemical performance compared to those with conventional two-dimensional electrodes, especially at fast charging/discharging. Nevertheless, laser structuring of electrodes is still limited in terms of achievable processing speed, and the upscaling of the laser structuring process is of great importance to gain a high technology readiness level. In the presented research, the impact of different laser structuring strategies on the electro-chemical performance was investigated on aqueous processed Li(Ni0.6Mn0.2Co0.2)O2 cathodes with acid addition during the slurry mixing process. Rate capability analyses of cells with laser structured aqueous processed electrodes exhibited enhanced performance with capacity increases of up to 60 mAh/g at high current density, while a 65% decrease in ionic resistance was observed for cells with laser structured electrodes. In addition, pouch cells with laser structured acid-added electrodes maintained 29–38% higher cell capacity after 500 cycles and their end-of-life was extended by a factor of about 4 in contrast to the reference cells with two-dimensional electrodes containing common organic solvent processed polyvinylidene fluoride binder. [ABSTRACT FROM AUTHOR]

This research aimed to synthesize polyvinyl fluoride membranes and coat them with tannic acid (TA) nanoparticles and polyethylene glycol (PEG) additives so that the membrane's removal efficacy for humic acid (HA) pollutant from agricultural wastewater was investigated. Thus, six membranes with PEG:TA ratios of 0:0, 1:0, 0:1, 1:1, 4:1, and 1:4 were synthesized. Then, the membranes' characteristics were identified by FTIR-ATR, FESEM, and AFM analysis, and HA's particle size and zeta potential were also investigated. Based on optimizing effective parameters, the operating pressure of 1.5 bar and HA concentration of 80 ppm were selected as optimal values. The membrane with PEG:TA = 4:1, as the optimally modified membrane, had a pure water flux of 446.03 L/m2.h, effluent flux of 72.43 L/m2.h, and pollutant removal rate of 86.62% at pH = 7 after 60 min had passed. These values for the pristine membrane (PEG:TA = 0:0) were 265.64 L/m2.h, 89.39 L/m2.h, and 75.59%, respectively. The results showed that although the effluent flux was lower in the optimized modified membrane than in the pristine membrane, HA removal percentage was increased. [ABSTRACT FROM AUTHOR]

High‐voltage LiCoO2 (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li‐ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high‐voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li‐PVDF) coating under air atmosphere. Benefitting from the good film‐forming and strong adhesion ability of Li‐PVDF, the thus‐obtained LiF layer is uniform, dense, and conformal; therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high‐voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF‐modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g−1 at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high‐voltage LCO cathodes reported so far. [ABSTRACT FROM AUTHOR]

The binder, a critical electrode component, significantly influences lithium‐ion batteries (LIB) performance, yet remains an under‐researched area. The widespread use of polyvinylidene fluoride (PVDF) as a commercial binder is challenged by its surging cost, attributed to limited production and increased demand, highlighting the necessity for alternatives. Here, we synthesize poly (trifluoroethyl methacrylate) (PTFEMA), a polymer with a molecular weight in the million range, through a straightforward radical solution polymerization method, aiming to use it as a cathode binder for LIBs. PTFEMA demonstrate good stability across the typical operating temperatures and voltages, along with robust adhesion to the current collector. Moreover, the PTFEMA outperforms PVDF in terms of electrolyte affinity and lithium‐ion conductivity, thereby achieving capacity and stability comparable to those of its PVDF counterparts. This investigation confirms the homopolymer form of PTFEMA as a compelling alternative to PVDF, representing a valuable exploration of binder technology for LIBs. [ABSTRACT FROM AUTHOR]