PVDF-HFP Matrix Research Articles

Supramolecular polymer cross-linking gel electrolyte for highly stable quasi-solid-state lithium metal batteries

Lithium (Li) metal batteries have the advantage of high energy density, but the Li dendrites risk piercing the separator and causing a short circuit in the battery. Replacing the liquid electrolytes with gel electrolytes is considered an effective strategy to solve the issues. Herein, a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel electrolyte, improved with multifunctional supramolecular polymer (MSP), was prepared to enhance the cycling stability and energy density of quasi-solid-state Li metal batteries. The MSP addictive constructs a cross-linked network structure with PVDF-HFP matrix and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) through hydrogen bonding, improving the mechanical strength of the composite gel electrolyte (PH-10%MSP-GE) to against the growth of Li dendrites. Moreover, the pre-lithiated sulfonic acid groups, conductive polyether groups of MSP, and the attraction of TFSI– anions, promote the Li-ion transportation of the composite gel electrolyte. Finally, the Li||Li symmetric cell cycle stably for over 450 h. The Li||LiFePO4 full cell demonstrates a high energy density and excellent cycling stability for over 600 cycles, with a capacity retention rate of up to 98.7%. This work provides valuable insights into the preparation of multifunctional composite gel polymer electrolytes and competitive quasi-solid-state Li metal batteries.

Durable ceramic-reinforced fluoropolymer nanocomposite corrosion protective coatings

In this study, inorganic-organic coatings composed of titanium dioxide (TiO2) as the ceramic component and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the polymer matrix, hybridized with nano-TiO2 particles, were developed for protecting mild steel (MS) from corrosion. Prior to TiO2 coating deposition, the MS substrates were pretreated with a bioinspired sub-layer of polydopamine to improve the surface coating adhesion, followed by uniform co-deposition of PVDF-HFP with varying concentrations of embedded nano-TiO2. The inclusion of nano-TiO2 further reinforces and densifies PVDF-HFP, providing added corrosion protection. The fabricated coatings were characterized by microscopy, spectroscopy, and diffraction technique, while the corrosion protection properties were evaluated by impedance, potentiodynamic polarization, salt spray, and cyclic corrosion tests. Results showed that both the PVDF-HFP matrix and TiO2 contents had substantial effects on the coatings’ thermal stability, hydrophobicity, and surface mechanical properties. The coatings also exhibited satisfactory corrosion resistance, with increased impedance modulus to roughly sixteen orders of magnitude for the TiO2-PVDF-HFP coating containing 0.5 g/L TiO2, relative to the untreated MS substrate. This result can be attributed to the low surface energy of PVDF-HFP, coupled with the dense structure and added physical barrier of nano-TiO2. Overall, these hybrid polymer/ceramic coatings are poised to help design other highly resilient and hydrophobic surface coatings with durable protection against corrosion.

Enhanced Dielectric Constant of PVDF-HFP/BFO Composite Films for Ferroelectric Applications

We have developed multiferroic Bismuth ferrite (BiFeO3, BFO) incorporated Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer-ceramic composites through the solution casting method. The polymer-ceramic composites are fabricated by varying the composition of the BFO as a filler material ranging 5, 10, 15, 20, 25, 30, and 40 wt% into the PVDF-HFP polymer matrix. We have investigated the effect of BFO loading on the structural, morphological, spectroscopic, and dielectric properties by different characterization techniques. X-ray diffraction analysis indicates the presence of non-polar α- and polar β- phases of PVDF-HFP in the composites. Scanning electron microscope studies revealed the spherulite morphology and homogenous dispersion of BFO particles. The addition of BFO filler in PVDF-HFP matrix at various percentages has been studied to improve the polar β- phase of PVDF-HFP which may enhance ferroelectric properties. The dielectric studies at room temperature showed an increase in dielectric constant value from 9.5 (pure PVDF-HFP) to 21.08 (30% loaded BFO) at 100 Hz. It is also evident from the Fourier Transform- Infrared (FT-IR) spectra, that a maximum of 75.24% of β-fraction is observed for 30% loaded BFO composition. The enhanced properties of the fabricated materials suggest that they may be useful for polymer-ceramic capacitor applications. The results are discussed in detail.

High-Performance PVDF-HFP-PVAc-LLZTO Composite Solid-State Electrolyte for Lithium Metal Battery

Composite solid-state electrolytes are highly promising contenders for next-generation lithium-metal batteries due to their high safety, good flexibility, and compatibility with lithium metal. In this work, Poly(vinyl acetate) (PVAc) was incorporated into PVDF-HFP in order to reduce the crystallinity of the PVDF-HFP matrix, improve the ionic conductivity of the electrolyte, and greatly reduce the interfacial impedance of the electrolyte by utilizing the low-temperature flexibility, excellent amorphous nature, and strong bonding properties of PVAc. On this basis, the active filler LLZTO was introduced to further reduce the crystallinity of the PVDF-HFP matrix and provide more Li+ transport channels. The PP60-10LLZTO composite solid electrolyte has exceptional mechanical and electrochemical characteristics with a high ionic conductivity of 7.2*10−4 S cm−1 and the Li+ transference number of 0.57 at 30 °C. The assembled LFP/Li battery can be stably cycled for 450 cycles at 30 °C and 0.5C, and its capacity retention rate is as high as 89%. The strategy of constructing composite solid-state electrolytes in this paper presents new insights for designing and developing high-performance solid-state lithium metal batteries.

Synergistic coupling among Mg2B2O5, polycarbonate and N,N-dimethylformamide enhances the electrochemical performance of PVDF-HFP-based solid electrolyte

Polymer solid electrolytes (SPEs) based on the [solvate-Li+] complex structure have promising prospects in lithium metal batteries (LMBs) due to their unique ion transport mechanism. However, the solvation structure may compromise the mechanical performance and safety, hindering practical application of SPEs. In this work, a composite solid electrolyte (CSE) is designed through the organic–inorganic synergistic interaction among N,N-dimethylformamide (DMF), polycarbonate (PC), and Mg2B2O5 in poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Flame-retardant Mg2B2O5 nanowires provide non-flammability to the prepared CSEs, and the addition of PC improves the dispersion of Mg2B2O5 nanowires. Simultaneously, the organic–inorganic synergistic action of PC plasticizer and Mg2B2O5 nanowires promotes the dissociation degree of LiTFSI and reduces the crystallinity of PVDF-HFP, enabling rapid Li ion transport. Additionally, Raman spectroscopy and DFT calculations confirm the coordination between Mg atoms in Mg2B2O5 and N atoms in DMF, which exhibits Lewis base-like behavior attacking adjacent C–F and C–H bonds in PVDF-HFP while inducing dehydrofluorination of PVDF-HFP. Based on the synergistic coupling of Mg2B2O5, PC, and DMF in the PVDF-HFP matrix, the prepared CSE exhibits superior ion conductivity (9.78 × 10−4 S cm−1). The assembled Li symmetric cells cycle stably for 3900 h at a current density of 0.1 mA cm−2 without short circuit. The LFP||Li cells assembled with PDL-Mg2B2O5/PC CSEs show excellent rate capability and cycling performance, with a capacity retention of 83.3% after 1000 cycles at 0.5 C. This work provides a novel approach for the practical application of organic–inorganic synergistic CSEs in LMBs.

PVDF-HFP Based, Quasi-Solid Nanocomposite Electrolytes for Lithium Metal Batteries.

Composite polymer electrolytes are systems of choice for future solid-state lithium metal batteries (LMBs). Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is among the most interesting matrices to develop new generation quasi-solid electrolytes (QSEs). Here it is reported on nanocomposites made of PVDF-HFP and pegylated SiO2 nanoparticles. Silica-based hybrid nanofillers are obtained by grafting chains of poly(ethylene glycol) methyl ether (PEG) with different molecular weight on the surface of silica nanoparticles. The functionalized nanofiller improves the mechanical, transport and electrochemical properties of the QSEs, which show good ionic conductivity values and high resistance against dendrite penetration, ensuring boosted long and safe device operation. The most promising result is obtained by dispersing 5wt% of SiO2 functionalized with short PEG chains (PEG750, Mw = 750gmol-1) in the PVDF-HFP matrix with an ease solvent-casting procedure. It shows ionic conductivity of 0.1mScm-1 at 25°C, more than 250h resistance to stripping/plating, and impressive results during cycling tests in LMB with LiFePO4 cathode.

Preparation and Properties of Gel Polymer Electrolytes with Li1.5Al0.5Ge1.5(PO4)3 and Li6.46La3Zr1.46Ta0.54O12 by UV Curing Process.

Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolytes (GPEs) are considered a promising electrolyte candidate for polymer lithium-ion batteries (LIBs) because of their free-standing shape, versatility, security, flexibility, lightweight, reliability, and so on. However, due to problems such as low ionic conductivity, PVDF-HFP can only be used on a small scale when used as a substrate alone. To overcome the above shortcomings, GPEs were designed and synthesized by a UV curing process by adding NASICON-type Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and garnet-type Li6.46La3Zr1.46Ta0.54O12 (LLZTO) to PVDF-HFP. Experimentally, GPEs with 10% weight LLZTO in a PVDF-HFP matrix had an ionic conductivity of up to 3 × 10-4 S cm-1 at 25 °C. When assembled into LiFePO4/GPEs/Li batteries, a discharge-specific capacity of 81.5 mAh g-1 at a current density of 1 C and a capacity retention rate of 98.1% after 100 cycles at a current density of 0.2 C occurred. Therefore, GPEs added to LLZTO have a broad application prospect regarding rechargeable lithium-ion batteries.

Collegial effects of CeO2/SiC nano-fillers on dielectric, thermal, impedance and conductivity behavior of PVDF-HFP matrix for flexible energy storage applications

ABSTRACT In the current study, novel Poly(vinylidene fluoride-co-hexafluoropropylene)/Cerium oxide/Silica carbide (PVDF-HFP/CeO2/SiC) flexible polymer nanocomposites were synthesized by solution casting technique. Structural changes involved in the composite formation between nano-fillers and host polymers were analyzed by X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. SEM results confirm the homogeneous dispersion of nano-fillers (CeO2 & SiC) within the host polymer. Thermogravimetric analysis (TGA) was used to identify the thermal stability of the polymer nanocomposite with about 56% of residual residue for increased nano-fillers loading. Tauc plots confirm that the energy band gap of pristine host polymer decreased with the incorporation of nano-fillers. The dielectrics, impedance, and AC conductivity studies were investigated in temperature ranging from 50°C to 150°C and the frequency range between 50 Hz and 10 MHz measured by an impedance analyzer. As a function of nano-filler loading, the nanocomposites show a significant increase in the dielectric constant (ε′ = 272.92, 50 Hz, 50°C) with low dielectric loss (tan(δ) = 1.98, 50 Hz, 150°C) values. Impedance and the AC conductivity results suggested that addition of nano-filler decreases the impedance and improves the AC conductivity value from 1.67 × 10−4 S/m for pristine PVDF-HFP to 1.44×10−3S/m for 15% SiC. These results justify the material being efficiently applicable for flexible energy storage applications.

Dielectric and impedance spectroscopy analysis of nano-zirconia encapsulated Poly(vinylidene fluoride-hexafluoropropylene) nanocomposites

In this work, zirconia (ZrO2) nanoparticles (NPs) incorporated poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanocomposites were fabricated at varying weight ratios through solution casting approach. The structural properties of PVDF-HFP/ZrO2 nanocomposites have been investigated by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The strong interaction of ZrO2 with the PVDF-HFP matrix was observed revealing the structural modifications in the nanocomposites. The thermal degradation behavior of PVDF-HFP/ZrO2 nanocomposites was investigated by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and differential thermal analysis (DTA). Addition of ZrO2 in the PVDF-HFP matrix has greatly improved the thermal stability of the PVDF-HFP/ZrO2 nanocomposites. The dielectric properties of the PVDF-HFP/ZrO2 nanocomposites were investigated as a function of frequency and temperature. The dielectric constant was observed to be higher at low frequency and decreased abruptly on increasing the frequency. Moreover, the impedance behavior of PVDF-HFP/ZrO2 nanocomposites with different loadings was studied by plotting Nyquist plots. These results revealed that PVDF-HFP/ZrO2 nanocomposites have shown enhanced thermal, dielectric and impedance properties as compared to neat PVDF-HFP film. These significant outcomes suggest that the PVDF-HFP/ZrO2 nanocomposites hold promise as viable options for energy storage applications.

An ultrathin and flexible polymer composite film at a low fraction of reduced graphene oxide for Ku-band electromagnetic interference shielding

The development of effective electromagnetic interference (EMI) shielding materials has turned into an extremely important and urgent challenge. The current study presents an ultrathin and flexible polymer, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite thin film, at a very low loading of reduced graphene oxide (rGO) prepared by a straightforward solvent casting approach for efficient EMI shielding application. The homogenous distribution of rGO sheets throughout the polymer matrix has been verified by applying high-resolution scanning and transmission electron microscopy. To clarify the interfacial relationship between the matrix and filler as well as potential changes in phase, the PVDF-HFP/rGO (PrGO) composite films are further analyzed using X-ray diffraction, Raman spectra, Fourier transform-infrared spectra, and contact angle analysis. The PrGO composite film has a 4.2 GPa Young's modulus and a tensile strength of around 64.8 MPa. The Ku-band frequency has been implemented to evaluate PrGO composite films' EMI shielding ability. The ultrathin PrGO composite film (∼80 µm) revealed an efficient EMI shielding effectiveness (SE) of ∼18.3 dB at a meagre rGO fraction (6.75 wt.%). This efficient EMI SE from ultrathin PrGO composite films is due to the well-connected network of rGO sheets inside the PVDF-HFP matrix. This study demonstrates a scalable and effective way to design an ultrathin, lightweight, and flexible composite film for promising EMI shielding applications in the development of miniaturized electronic devices, and aerospace fields.

Electrospun polymeric nanohybrids with outstanding pollutants adsorption and electroactivity for water treatment and sensing devices

Graphene oxide (GO) and carbon nanotubes (CNTs) were loaded at different mutual ratios into poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) matrix and electrospun to construct mats that were assessed as smart sorbents for decontaminating water from methylene blue (MB) pollutant, while ensuring the additional possibility of detecting the dye amounts. The results revealed that sorption capacity enhances upon increasing GO content, which is beneficial to wettability and active area. Equilibrium adsorption of these materials is precisely predicted by the Langmuir isotherm model and the maximum capacities herein achieved, ranging from 120 to 555 mg/g depending on the formulation, are higher than those reported for similar systems. The evolution of the structure and properties of such materials as a function of dye adsorption was studied. The results reveal that MB molecules prompted the increase of electrical conductivity of the samples in a dose-dependent manner. Mats containing solely CNTs, while displaying the worst sorption performance, showed the highest electrical performances, displaying interesting changes in their electrical response as a function of the dye amount adsorbed, with a linear response and high sensitivity (309.4 µS cm−1 mg−1) in the range 0–235 µg of dye adsorbed. Beyond the possibility to monitor the presence of small amounts of MB in contaminated water and the saturation state of sorbents, this feature could even be exploited to transform waste sorbents into high-added value products, including flexible sensors for detecting low values of pressure, human motion, and so on.Graphical Multifunctional materials for dye absorption and detection, pressure sensing, fabricated by integrating GO and CNTs into PVDF-HFP matrix via electrospinning.

Multilayer asymmetric solid polymer electrolyte with modified interface for high-voltage solid-state Li metal batteries

Solid polymer electrolytes (SPEs) are promising for achieving safe solid-state Li metal batteries (SSLMBs). However, unstable electrode/electrolyte interface contact of SPEs limits their application at high voltage. To address this issue, we designed a multi-layer asymmetric SPE with a sandwich structure based on the hydroxyapatite (HAP) enhanced PVDF-HFP matrix. Two different interfacial modification layers were introduced on the anode and cathode sides. Methyl (2,2,2-trifluoromethyl) carbonate (FEMC) and tetramethylene sulfone (TMS) were selected as plasticizers in the layers, respectively, contacting the anode and cathode to reduce the reactivity of the anode interface and enhance the high-voltage compatibility of the cathode interface. Unlike usual designs, each layer of the asymmetric SPE has essentially the same composition except the plasticizers, effectively eliminating interface resistance and promoting Li+ fast migration. Consequently, the asymmetric SPE exhibits excellent ionic conductivity at room temperature (8.8 × 10−4 S cm−1), superior interfacial stability, and Li dendrite inhibition ability. In addition, LiFePO4||SPE||Li cell demonstrates a stable retention rate of over 92 % after 500 cycles at 1 C. These findings provide a new approach for implementing SSLMBs under high voltage.

Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries

Solid polymer electrolytes (SPEs) are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries. Nevertheless, the poor ionic conductivity at room temperature (RT) and low resistance to Li dendrites seriously hinder the commercialization of SPEs. Herein, we design a bifunctional flame retardant SPE by combining hydroxyapatite (HAP) nanomaterials with N-methyl pyrrolidone (NMP) in the PVDF-HFP matrix. The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of LiTFSI in the PVDF-HFP matrix. Consequently, the prepared SPE demonstrates superior ionic conductivity at RT, excellent fireproof properties, and strong resistance to Li dendrites. The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 mA cm−2, and the solid-state LiFePO4||Li cell shows excellent capacity retention of 85.3% over 600 cycles at 0.5 C.

Solvate ionic liquid-derived solid polymer electrolyte with lithium bis(oxalato) borate as a functional additive for solid-state lithium metal batteries

A novel solvate ionic liquid-derived solid polymer electrolyte was constructed for lithium metal batteries by incorporating a [Li(G4)1][TFSI] solution containing LiBOB as a functional additive into the PVDF-HFP matrix.

Dielectric and energy storage properties of surface-modified BaTi0.89Sn0.11O3@polydopamine nanoparticles embedded in a PVDF-HFP matrix.

In the most recent electronic and electric sectors, ceramic-polymer nanocomposites with high dielectric permittivity and energy density are gaining popularity. However, the main obstacle to improving the energy density in flexible nanocomposites, besides the size and morphology of the ceramic filler, is the low interfacial compatibility between the ceramic and the polymer. This paper presents an alternative solution to improve the dielectric permittivity and energy storage properties for electronic applications. Here, the poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) matrix is filled with surface-modified BaTi0.89Sn0.11O3/polydopamine nanoparticles (BTS11) nanoparticles, which is known for exhibiting multiphase transitions and reaching a maximum dielectric permittivity at room temperature. BTS11 nanoparticles were synthesized by a sol-gel/hydrothermal method at 180 °C and then functionalized by polydopamine (PDA). As a result, the nanocomposites exhibit dielectric permittivity (εr) of 46 and a low loss tangent (tan δ) of 0.017 at 1 kHz at a relatively low weight fraction of 20 wt% of BTS11@PDA. This is approximately 5 times higher than the pure PVDF-HFP polymer and advantageous for energy storage density in nanocomposites. The recovered energy storage for our composites reaches 134 mJ cm-3 at an electric field of 450 kV cm-1 with a high efficiency of 73%. Incorporating PDA-modified BTS11 particles into the PVDF-HFP matrix demonstrates highly piezo-active regions associated with BTS11 particles, significantly enhancing functional properties in the polymer nanocomposites.

Investigation on the influence of ball milling on the microstructural properties of 2D-hexagonal boron nitride towards electroadhesive applications

A light weight low power operated fabric based electroadhesive actuators were made with two dimensional hexagonal boron nitride (hBN) in PVdF-HFP polymer matrix as a dielectric and Cu/Ni fabric tape as electrodes for applications in robotics and exosuits. The properties of the dielectric layer were tuned for high load bearing capacity by inducing dangling joints in 2D hBN by the atmospheric ball milling as a factor of time. The electroadhesive actuator was optimized for a maximum load of 700 g for a DC voltage of 250 V, by changing the micro structures of 2D hBN with ball milling for different hours. The optimized load bearing capacity of the electroadhesive actuators obtained with 1 h ball milled 2D hBN incorporated PVdF-HFP matrix has been evidenced through structural and morphological studies.

In situ generated composite gel polymer electrolyte with crosslinking structure for dendrite-free and high-performance sodium metal batteries

Sodium metal batteries (SMBs) with potentially high theoretical capacity are considered as one of the most promising candidates for high energy density batteries. However, the safety problems caused by sodium dendrite seriously hinder the practical application of SMBs. Composite gel polymer electrolytes (CGPE) composed of inorganic ionic conductors and organic polymers can suppress the growth of sodium dendrites and improve the safety of SMBs. Nevertheless, the presence of incompatible interfaces between organic and inorganic components leads to low ionic conductivity and ineffective Na+ transport for CGPE. Herein we demonstrate a CGPE composed of silane-modified beta-Al2O3 powders and PVDF–HFP matrix with crosslinking structure to eliminate the incompatibility of the inorganic-organic interfaces, thereby enhancing electrochemical performance of the synthesized composite electrolyte. Experimental results show that the obtained composite electrolyte possesses a high ionic conductivity of 1.37 × 10−3 S cm−1 at 20 °C and a sodium-ion transference number up to 0.424. Moreover, the assembled sodium symmetric cell based on the obtained composite electrolyte shows an excellent cycling performance for 800 h with no obvious voltage polarization at 0.5 mA cm−2, demonstrating an effective protection for the sodium anode. Furthermore, when used as a separator in the Na3V2(PO4)3-cathode based full cell, it could deliver an excellent electrochemical performance with a high-capacity retention of 92.2% even after 1000 cycles under an average columbic efficiency up to 99.9% at 3 C. The impressive performance enhancement of the full cell implies that such a composite electrolyte design could provide an effective strategy for the construction of highly stable SMBs.

Stretchable polymer-modulated PVDF-HFP/TiO2 nanoparticles-based piezoelectric nanogenerators for energy harvesting and sensing applications

Since piezoelectric materials can convert mechanical pressure applied to them to electrical impulses and vice versa, they are unequivocally referred to as smart materials. Among such class of materials, the polymer-based piezoelectric nanocomposites are widely used to transfer mechanical energy from vibrations, human motion, mechanical loads, and other sources into electrical energy for flexible low-power devices. We devised a facile strategy of polymer modulation (5 wt%, 10 wt%, and 15 wt%) in PVDF-HFP-based nanogenerators with a fixed 10 wt% TiO2 nanofiller concentration, employing ultrasonication assisted solution casting technique. The intense vibrational peak validated the enhancement in β-phase nucleation at 1229 cm−1 in PT-10 nanocomposite film using FTIR studies. The PT-10 film had a maximum capacitance of 9.7 pF when subjected to a force of 0.5 N, attributed to the Maxwell-Wagner (MW) interfacial polarization between the TiO2 nanofiller and PVDF-HFP matrix and its dielectric saturation was in accordance with the Kalayeh-Charalambides model. The PT-10 based piezoelectric nanogenerator had the highest piezoelectric voltage responses in all the different mechanical modes (tapping, bending, and stretching motions), with a peak voltage of 9.69 V in the case of repetitive finger-tapping motions. The nanogenerator was also utilized to generate 2.22 V from human blood circulation. The polymer-modulated strategy can thus be an effective way to design and tune piezoelectric nanogenerators for powering biomedical sensors and other low-power consumer devices.

Dual In Situ Polymerization Strategy Endowing Rapid Ion Transfer Capability of Polymer Electrolyte toward Ni‐Rich‐Based Lithium Metal Batteries

Poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) is one of the most promising candidate electrolyte matrices for high energy batteries. However, the spherical skeleton structure obtained through the conventional method fails to build continuous Li ion transmission channels due to the slow volatilization of high boiling solvent, leading to inferior cycling performance, especially in a Ni-rich system. Herein, a novel strategy is presented to enrich the Li ion transfer paths and improve the Li ion migration kinetics. The tactic is to prepare cross-linked segments through the PVDF-HFP matrix by adopting free radical polymerization and Li salt induced ring-opening polymerization. Most significantly, the visualization of the structure of as-prepared electrolyte is innovatively realized with the combination of polarization microscopy, transmission electron microscopy, scanning electron microscope-energy dispersive spectroscopy, PVDF-HFP, and cross-linked network form interconnected microstructures. Therefore, poly(glycidyl methacrylate and acrylonitrile)@poly(vinylidene fluoride-hexafluoropropylene) electrolyte presents a high ionic conductivity (1.04mScm-1 at 30°C) and a stable voltage profile for a Li/Li cell after 1200h. After assembly with a LiNi0.8 Co0.15 Al0.05 O2 cathode, a high discharge specific capacity of 190.3mAhg-1 is delivered, and the capacity retention reaches 88.2% after 100 cycles. This work provides a promising method for designing high-performance polymer electrolytes for lithium metal batteries.

Synergistically Active Piezoelectrical H2 O2 Production Composite Film Achieved from a Catalytically Inert PVDF-HFP Matrix and SiO2 Fillers.

Local and decentralized H2 O2 production via a piezoelectrical process promises smart biological utilization as well as environmental benefits. However, stable, bio/environmentally safe, and easily applied H2 O2 generation materials are still lacking. Here, we report a novel flexible H2 O2 generation polymeric film composed of catalytically inert PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene)) matrix and SiO2 nanoparticle fillers. The film is bio-/environmentally benign at resting states, but effectively produces H2 O2 upon ultrasonic motivation at a production rate of 492 μmol in one hour. Experimental and simulation methods in combination indicate that the effective H2 O2 generation capabilities stem from the synergistic existence of piezoelectrical fields and the air-liquid-solid three-phase regions around the porous film. The chemical conversions are motivated by the adsorbed charges. The silicon hydroxyl groups properly stabilize the *OOH intermediate and facilitate the chemical conversions of 2e- ORR of ambient O2 . We expect the report to inspire H2 O2 piezoelectrical generation materials and promote the novel production strategies of H2 O2 as well as piezoelectrical functional materials.