Vinylidene Fluoride-co-hexafluoropropylene) (P Research Articles

Poly(vinylidenefluoride-co-hexafluoropropylene): An Emerging Host Material for Ion Conducting Gel Polymer Electrolyte-Cum-Separator Membrane

Secondary batteries based on ion conduction are among the most promising technology for next generation mobile and stationary storage system due to their unmatched volumetric energy density. However the multiple emerging challenges which include electrochemical stability, transport efficiency and safety issues of these secondary batteries have attracted worldwide attention. The perspective of this review is that rational design of polymeric separator which is an essential component in rechargeable batteries separating anode and cathode, and controlling number of mobile ions is crucial to overall battery performance, including lifetime, safety as well as energy and power density of battery. There is impressive progress in the exploration of separator materials. Among them, poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-co-HFP) have received great attention as polymer host due to some its splendid collective property such as its amorphous nature, high room temperature ionic conductivity, high dielectric constant and the possibility of controlling the porosity of the materials through binary and ternary polymer/solvent systems. This review focuses specifically on recent advances in P(VdF-co-HFP) based separator cum gel polymer electrolyte with detailed analysis of several embedded functional agent that are incorporated to improve ionic conductivity, mechanical robustness and thermal stability of rechargeable batteries.

An alternating multilayer architecture boosts ultrahigh energy density and high discharge efficiency in polymer composites.

Poly(vinylidene fluoride) (PVDF)-based polymers with excellent flexibility and relatively high permittivity are desirable compared to the traditional bulk ceramic in dielectric material applications. However, the low discharge efficiency (<70%) caused by the severe intrinsic dielectric loss of these polymers result in a decrease in their breakdown strength and other problems, which limit their widespread applications. To address these outstanding issues, herein, we used a stacking method to combine poly(methyl methacrylate) (PMMA) with poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) for the synthesis of a series of alternating multilayer films with different layers. Benefitting from the blocking effect of the multilayer structure and excellent insulation performance of PMMA, simultaneous improvements in the breakdown strength and discharge efficiency of the multilayer films were achieved. Compared with the pure polymer films and other multilayer films with different layers, the film with a 9-layer structure exhibited the highest energy storage density of 25.3 J cm−3 and extremely high discharge efficiency of 84% at 728 MV m−1. Moreover, the charge and discharge performance of the other multilayer films were also better than that of P(VDF-HFP). In addition, it was also found that for the multilayer composite films with the same components, the blocking effect was reinforced with an increase in the number of layers, which led to a significant improvement in the breakdown strength. We consider that the multilayer structure can correlate with the dielectric properties of different polymer materials to enhance the energy storage of composite materials, and will provide a promising route to design high dielectric performance devices.

Enhanced energy storage capability of P(VDF-HFP) nanodielectrics by HfO2 passivation layer: Preparation, performance and simulation

Flexible dielectric nanocomposites have shown great potential for electrostatic capacitors due to their excellent energy storage properties. In an effort to eliminate the disadvantages induced by the interfacial polarization of two different components in the nanocomposite, in this work, HfO2@BaTiO3 nanoparticles (HfO2@BT NPs) with core-shell structure were synthesized and used to fabricate poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))/HfO2@BT nanocomposite films via solution casting method. The passivation HfO2 layer with high resistivity and moderate dielectric permittivity could act as a buffering barrier and alleviate the dielectric mismatch between the BT nanoparticles (BT NPs) and P(VDF-HFP) matrix. The breakdown strength (Eb) and discharged energy density (Ue) of P(VDF-HFP)/HfO2@BT nanocomposites have been substantially enhanced. The nanocomposite filled with 1 wt% HfO2@BT presents a maximum Ue of 10.7 J/cm3 at 450 MV/m, which is 36% and 59% higher than that of the pristine P(VDF-HFP) and nanocomposite filled with the same BT NPs, respectively. Meanwhile, P(VDF-HFP)/HfO2@BT nanocomposites show a charge-discharge efficiency of 72%, which is superior to most of the reported values. The possible mechanism of HfO2 layer on above performance enhancements is proposed based on both experimental analysis and finite element simulation. This work demonstrates that utilizing dielectric fillers with passivation layer might be an effective way to improve the energy storage performance of the flexible dielectric nanodielectrics.

Enhancing thermal stability of P(VDF-HFP) based nanocomposites with core-shell fillers for energy storage applications

Improving thermal stability of the ceramic-polymer based nano-composited electrostatic capacitors is the key element to their practical applications in harsh environment. In this paper, Fe3O4 @BaTiO3 particles with thermal conductive core and high-k shell were prepared and used as fillers to improve the thermal stability and high temperature energy storage density of poly-(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) based composited films. Compared to the pure polymer, the films with 10 wt% fillers showed enhanced temperature stability at the range of 40–120 °C. The high-temperature (120 °C) average breakdown strength reached at 1615 kV/cm with ~170% higher than the pure P(VDF-HFP) (970 kV/cm). The discharged energy storage density (120 °C) was 1.68 J/cm3 (1750 kV/cm), which was enhanced up to 1150% comparing to that of pure P(VDF-HFP) (0.146 J/cm3 at 1300 kV/cm). The increased thermal conductivity and the Internal Barrier Layer Capacitor (IBLC) effects at the conductive-insulating interfaces contribute to the enhanced features. The results in the present work explored an effective way to prepare high temperature dielectric nanocomposites for harsh applications in energy storage field.

Significantly improved breakdown strength and energy density of tri-layered polymer nanocomposites with optimized graphene oxide

Advanced electrostatic capacitors with great energy densities are urgently needed for practical applications in high-performance energy storage devices. Herein, poly (methyl methacrylate) (PMMA) is employed as two outer layers to provide excellent insulation characteristic, while ferroelectric copolymer poly (vinylidene fluoride-co-hexafluoropropene) P(VDF-HFP) with dispersed graphene oxide (GO) as the inter layer to enhance dielectric constant (K) and electrical displacement (D). The resulting trilayered nanocomposites exhibit highest electrical displacement difference (Dmax-Drem) value of 7.17 μC cm−2 at a low filler loading of 2 wt% GO under an electrical field of 300 MV m−1. The breakdown strength (Eb) of the designed trilayered nanocomposites are prominently improved at least one order of magnitude in comparison to other configuration films such as single-layered and reversed trilayer structures, as verified by the leakage current measurements and the finite element simulations with 3D models. The trilayered nanocomposites deliver an ultrahigh energy density of 10 J cm−3 and a discharged efficiency of 77% at an applied electrical field of 300 MV m−1, which is among the best energy storage performance under the identical electric field reported so far. The potential applications of the trilayered nanocomposites for energy storage have been further demonstrated by stable performance over a 40,000 charge-discharge cycling.

Enhanced Dielectric Performance of P(VDF-HFP) Composites with Satellite–Core-Structured Fe2O3@BaTiO3 Nanofillers

Polymer dielectric materials are extensively used in electronic devices. To enhance the dielectric constant, ceramic fillers with high dielectric constant have been widely introduced into polymer matrices. However, to obtain high permittivity, a large added amount (>50 vol%) is usually needed. With the aim of improving dielectric properties with low filler content, satellite–core-structured Fe2O3@BaTiO3 (Fe2O3@BT) nanoparticles were fabricated as fillers for a poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix. The interfacial polarization effect is increased by Fe2O3 nanoparticles, and thus, composite permittivity is enhanced. Besides, the satellite–core structure prevents Fe2O3 particles from directly contacting each other, so that the dielectric loss remains relatively low. Typically, with 20 vol% Fe2O3@BT nanoparticle fillers, the permittivity of the composite is 31.7 (1 kHz), nearly 1.8 and 3.0 times that of 20 vol% BT composites and pure polymers, respectively. Nanocomposites also achieve high breakdown strength (>150 KV/mm) and low loss tangent (~0.05). Moreover, the composites exhibited excellent flexibility and maintained good dielectric properties after bending. These results demonstrate that composite films possess broad application prospects in flexible electronics.

Enhanced dielectric properties of poly(vinylidene fluoride-co-hexafluoropropylene) nanocomposites using oriented nickel nanowires

Abstract The alignment of fillers in polymer matrix plays an important role in the dielectric properties of composite materials, but there are currently limited ways to effectively control the orientation of the fillers. In this paper, nickel nanowires (Ni NWs) with natural ferromagnetism were aligned under the external magnetic field during the fabrication process of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) based nanocomposite. Subsequently, orientation effects of Ni NWs, including the in-plane, through-plane and random patterns along the electric field orientation, on the dielectric performance of P(VDF-HFP) nanocomposites were investigated. The results showed that the dielectric properties of Ni NWs-P(VDF-HFP) nanocomposites were related to the anisotropy of Ni NWs. The highest dielectric constant of polymer nanocomposites with the 1.3 vol% Ni NWs reached to 41 at 1 kHz when the orientation of nanofiber was parallel to electric field, which is 274% higher than that of unaligned one and is 513% higher than the neat polymer. In addition, the nanocomposites kept the low dielectric loss. The results can be explained by combining the percolation theory, micro capacitor model and interfacial polarization theory. The finding provides a new method to prepare the nanocomposite dielectric materials with fillers arrangement. On the other hand, it is meaningful to in-depth understand the effect of fillers arrangement on the dielectric properties of composite materials.

Effect of ionic liquids on the electrical, structural and morphological properties of P(VdF-HFP)–NaTF electrolytes

Polymer electrolytes with different ionic liquids, 1-methyl-3-propylimidazolium iodide (PMII) and 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMImTf), were prepared. Poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-HFP)) was used as polymer and sodium trifluoromethanesulfonate (NaTf) as salt. Maximum ionic conductivity for the polymer electrolyte was observed as 1.03 × 10−3 Scm−1 and 1.37 × 10−3 Scm−1 for the addition of 20 wt% of BMImTf and for 40 wt% of PMII respectively. The dielectric behaviour of the samples was studied by analysing the complex dielectric permittivity. It was observed from the XRD studies that the amorphicity of the PMII added system was greater than the system added with BMImTf. FTIR analysis confirmed the occurrence of complexation and interaction among the components. Quantity of free ion and contact ion pairs was calculated using the deconvolution of the FTIR spectrum which supported the determined ionic conductivity of the polymer electrolytes. The BMImTf-added system was identified as more thermally stable than the PMII-added system. DSC confirmed the enhancement of amorphous phase in polymer electrolyte after the addition of ionic liquid. SEM images illustrated the role of porous structures on the ionic conductivity of the films. AFM analysis of the polymer electrolytes showed that the morphological change induced by PMII was higher than BMImTf.

Characterizations of P(VDF-HFP)-BaTiO3 nanocomposite films fabricated by a spin-coating process

Abstract In this work, free-standing and flexible polymer-ceramic nanocomposite films were fabricated by a spin-coating process using poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] as matrix and BaTiO3 (BTO) nanoparticles as filler. The relationships between the properties and compositions were systematically investigated. It is experimentally found that the crystallinity and the size of crystals of the P(VDF-HFP) matrix decreases with increasing BTO content. The dielectric responses of the polymer used as matrix were determined by four dielectric processes. Both the temperature and frequency dependences of the dielectric responses obtained in the composite films are mainly determined by the polymer matrix, and the influences of the ceramic filler on the four dielectric processes of the polymer matrix were discussed.

Thermoreversible Gelation of a Vinylidene Fluoride‐Based Copolymer in Methyl Ethyl Ketone: Dynamics and Structure

Thermoreversible poly(vinylidene fluoride‐co‐hexafluoropropylene) (P(VDF‐co‐HFP)) gels are formed in an aliphatic ketone − methyl ethyl ketone (MEK) − at high concentrations (above 11 wt%). This gelation phenomenon is first investigated in terms of gelation kinetics which is found to depend strongly on both copolymer concentration and temperature. Melting temperatures Tm of P(VDF‐co‐HFP)‐based gels prepared at different concentrations, in MEK are measured by DSC. Combination of 19F Nuclear Magnetic Resonance (NMR), Small‐Angle X‐ray Scattering (SAXS), and Wide‐Angle X‐ray Scattering (WAXS) on undried/nonlyophilized gels is used to probe both the gelation mechanisms and the structure of these systems. 19F NMR experiments allow studying selectively the fluorinated copolymer. The occurrence of a polymer network‐like structure with rigid zones acting as cross‐links has been highlighted. Such a behavior is only observed in the gel state: no polymer network or rigid zones exist when the polymer–solvent system is in the liquid state. Moreover, the fraction of rigid zones as well as the fraction of elastically active chain portions increases with the copolymer concentration. The nature, of the rigid zones present within the gels are investigated by X‐ray diffraction. Rigid regions are found to display a crystalline order.

Enhanced dielectric performance of P(VDF-HFP) composites filled with Ni@polydopamine@BaTiO3 nanowires

Dielectric polymer nanocomposites have been attracting increasing attention because of their wide range of applications in electronics industry. To improve their dielectric properties, incorporating conductive fillers and ceramic fillers into the polymer matrix is considered to be an effective solution. Here, Ni nanoparticles (about 50–90 nm) were decorated onto the surface of polydopamine (PDA) coated BaTiO3 nanowires to synthesize Ni@polydopamine@BaTiO3 nanowires (Ni@PDA@BT NWs, also denoted as NPB) with different Ni loading amount. The nanowires were then added into poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix and composite films were prepared. The dielectric performance of composite films is largely enhanced owing to the microcapacitor effect and interfacial polarization effect induced by Ni nanoparticles. This enhancement can be improved by increasing the loading amount of Ni. Crystallization behavior of the films were also investigated. With 20 vol% of Ni@PDA@BT NWs added, the dielectric constant of the composite film reaches 48.4 at 1 kHz, in contrast to 29.5 for 20 vol% of BT and 10.6 for pristine P(VDF-HFP). And the dielectric loss tangent remains at a low level of 0.23 at 1 kHz. These composite films exhibit potential for applications in flexible electronic devices and electrical systems.

Polymer Electrolyte Blend Gate Dielectrics for High-Performance Ultrathin Organic Transistors: Toward Favorable Polymer Blend Miscibility and Reliability.

We report on systematic mobility enhancements in electrolyte-gated organic field-effect transistors (OFETs) by thinning down the active layer and exploiting polymer solid-state electrolyte gate insulators (SEGIs). The SEGI is composed of homogeneous poly(vinylidene fluoride- co-hexafluoropropylene) [P(VDF-HFP)] polymer solution-ion gel blends of high areal capacitance of >10 μF cm-2 at 1 Hz. By scaling up the poly(3-hexylthiophene) (P3HT) semiconducting layer by 1 order of magnitude (5-50 nm), an ultraviolet photoelectron spectroscopy examination reveals a downward vacuum-level shift generating a substantial hole injection barrier that originates from different interfacial dipole layer formations. The ultrathin (5.1 nm) P3HT FETs outperformed the other devices, exhibiting stable device characteristics with a highest field-effect mobility of >2 cm2 V-1 s-1 (effective mobility of 0.83 ± 0.05 cm2 V-1 s-1), on/off ratio of ∼106, low threshold voltage of <-0.6 V, and low gate-leakage current levels of ∼105 below the on-current levels in 10 μm channel length devices. We observed a positive threshold voltage shift in the P3HT/SEGI FETs with decreasing semiconductor thickness. The aforementioned mobility is at least 10 times greater than that of neat P(VDF-HFP) devices. The significant FET performance is attributed to a better insulator/semiconductor interface, efficient hole injection from the Au electrode resulting in a low contact resistance of <500 Ω cm, and boosted charge-carrier densities in the transistor channel. This work demonstrates an excellent approach for carrier mobility enhancement and reliability assessment in low-voltage-operated electrolyte-gated OFETs.

High-k Fluoropolymer Gate Dielectric in Electrically Stable Organic Field-Effect Transistors.

A detailed study of a high-k fluoropolymer gate dielectric material, poly(vinylidene fluoride- co-hexafluoropropylene) [P(VDF-HFP)], is presented as a guide to achieve low operational voltage and electrically stable device performance. The large dipole moment of C-F dipoles in P(VDF-HFP) is responsible for its high dielectric constant as well as its potentially ferroelectric behavior that must be minimized to avoid hysteretic current-voltage characteristics. A range of material grades and processing conditions are explored and are shown to have a significant effect on the degree of hysteresis observed in device-transfer characteristics. The percentage of HFP monomer in the P(VDF-HFP) dielectric has an effect on gate-dependent mobility induced by disorder at the semiconductor-dielectric interface. Most importantly, we present the considerations that must be made to achieve optimal performance in multiple device architectures of organic field-effect transistors when using P(VDF-HFP) as a dielectric layer.

Three different mechanisms of self-discharge behavior in poly(vinylidene fluoride-hexafluoropropylene) for dielectric energy storage

Poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) has attracted attention as a matrix material for nanodielectrics, combining the high electrical breakdown of the polymer with the high permittivity of nanoparticles for improved energy storage properties. Although a large number of published works have reported increased discharged energy density for various nanocomposites, polarization and conduction loss mechanisms are rarely investigated. The latter are closely linked to the self-discharge behavior, which is crucial for future applications. This work aims to improve knowledge about loss and self-discharge mechanisms in doctor-blade-coated P(VDF-HFP) since its role in nanodielectrics is not fully understood. Combined analysis of cyclic unipolar electric displacement–electric field (D–E) characteristics and charging–lift–discharging measurements, where the measurement tip is lifted for a specific time between charging and discharging processes, reveals three Debye processes with different relaxation times: 20, 130 and 1340 s. The fast one correlates with the intrinsic conductivity of the polymer, which is dominated by space charge at high electric fields. The other two processes appear to saturate at an electric field of 100 MV m−1 so that their contribution to permittivity drops.

Adjusting the morphology of poly(vinylidene fluoride-co-hexafluoropropylene) membranes by the VIPS process for efficient oil-rich emulsion separation

Given its excellent bulk properties and highly hydrophobic nature, poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-co-HFP), is a candidate material for the gravity-driven separation of water and oil from oil-rich emulsions. For this, highly porous membranes with a controlled large pore size are necessary. An ideal process to design such structures is the vapor-induced phase separation (VIPS) process but it has been underexplored using P(VDF-co-HFP). Here, we address this challenge by presenting and discussing the formulation/process conditions that permit to obtain the desired P(VDF-co-HFP) porous bi-continuous structure by VIPS process only. Then, the membrane is fully characterized before being applied to the separation of water-in-oil emulsions, from versatile oil-rich phases, with or without the use of surfactants, in both dead-end gravity driven process and cross-flow process. In each situation, high flux and separation efficiencies were obtained, and the membrane outperformed commercial hydrophobic poly(vinylidene fluoride) (PVDF) membranes of similar pore size/porosity in every aspect (flux, separation efficiency, mechanical sustainability). All in all, P(VDF-co-HFP) VIPS membranes appear to be ideal materials for fast and effective gravity-driven separation of oil-rich emulsions.

Cyclic stability improvement in a blended P(VdF-HFP)/P(BMA-AN-St)-based gel electrolyte by electrospinning for high voltage lithium ion batteries

The cyclic stability of traditional poly (vinylidenefluoride-co-hexafluoropropylene) (P(VdF-HFP)) and our newly developed poly (butyl methacrylate-acrylonitrile-styrene) (P(BMA-AN-St)) copolymer-based gel polymer electrolyte (GPE) must still be improved to satisfy the increasingly rigid demands of lithium ion batteries that have higher energy densities. Series ratios of P(VdF-HFP) and P(BMA-AN-St) blended membranes were prepared using an electrospinning method to compensate for the disadvantages of a single copolymer-based membrane. The results showed that the compositions of P(VdF-HFP) and P(BMA-AN-St) had sizeable effects on the physical and electrochemical characterization of GPE, in which the P4 membrane and the GPE blending ratio of P(VdF-HFP): P(BMA-AN-St) = 1: 4 had the best properties. Because the P4 membrane showed the best interconnected pore structure and highest porosity, the GPE exhibited the highest ionic conductivity, with a value of 1.4 × 10−3 S cm−1 at ambient temperature. Due to the better compatibility of the P4-based GPE with a lithium anode and its considerably electrochemical stability, the LiNi0.5Mn1.5O4/GPE/Li coin cell had an excellent cyclic performance, in which a 98% capacity retention under a 1C rate was maintained after 150 cycles compared to the coin cell that used a pure P(VdF-HFP)-based GPE that maintained 86% of its discharge capacity under the same test conditions. Furthermore, the acceptable rate characterization of the P4-based GPE was presented with a discharge capacity at a 5C rate that retained 92% of its counterpart at 1C.

Crystal Forms and Microphase Structures of Poly(vinylidene fluoride-co-hexafluoropropylene) Physically and Chemically Incorporated with Ionic Liquids

The effects of incorporating two imidazolium-type ionic liquids (ILs), 1-vinyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide (IL-TFSI) and 1-vinyl-3-butylimidazolium chloride (IL-Cl), on the crystal forms and phase microstructures of poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-co-HFP), were investigated. No change in the crystal form was observed with the incorporation of IL-TFSI because of the selective interaction between the IL and HFP moieties of the P(VDF-co-HFP) molecular chains. In contrast, the incorporation of IL-Cl induces an α-to-β crystal form transition because of the interactions between IL-Cl and the VDF moieties. Furthermore, the incorporation of IL-TFSI led to distinct phase separation of P(VDF-co-HFP), whereas a homogeneous phase structure was maintained with the incorporation of IL-Cl. Element mapping images reveal that the specific interactions of IL-TFSI with the HFP moieties induce enrichment of the HFP moieties, which results in well-defined HFP/IL-TFSI nanodomain...

Organic Ionic Plastic Crystal‐polymer Solid Electrolytes with High Ionic Conductivity and Mechanical Ability for Solid‐state Lithium Ion Batteries

AbstractSolid electrolytes (SEs) would be an ideal solution to safety concerns, miniaturization and increase of energy density; however, SEs are difficult to have high ionic conductivity and mechanical properties simultaneously. In this work, we firstly synthesize a novel class of ammonium‐based organic ionic plastic crystals (OIPCs), then prepare SE system by blending synthesized OIPC with poly(vinylidenefluoride‐co‐hexafluoropropylene) (P(VDF‐HFP)) and lithium bis(fluorosulfonyl)imide (LiFSI). Such SEs overcome most of the limitations, with attractive ionic conductivity and lithium ion transference number, excellent mechanical properties, high electrochemical stability, as well as satisfactory interfacial stability with lithium metal. In particular, Li/LiFePO4 cells employing as‐prepared SE exhibit high discharge capacity, favorable cycling and rate performance at 30 °C, which is comparable to those using liquid electrolytes. The reported SE system, combined with excellent overall performance, is expected to have great potential for application in solid‐state lithium ion batteries.

Significantly enhanced dielectric properties of P(VDF-HFP) composite films filled with core-shell BaTiO3@PANI nanoparticles

Core-shell structured BaTiO3@polyaniline (BT@PANI) nanoparticles were synthesized via surface hydroxylation and in-situ polymerization method and were embedded into Poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] matrix. The dielectric performance as well as thermal behavior of BT@PANI/P(VDF-HFP) nanocomposite films are investigated. The crystallinity increases with increasing the BT@PANI content. Compared with BT particles, the BT@PANI core-shell nanoparticles exhibit notable improvement on dielectric properties. Typically, with a filler content of 20 vol% BT@PANI, the dielectric constant of BT@PANI/P(VDF-HFP) composite film reaches 99.1 at 1 kHz, which is 6.2 times larger than that of 20 vol% BT (16.1) and 9.6 times larger than pristine P(VDF-HFP) (10.3). Enhanced permittivity is generated from the interfacial polarization and the microcapacitor effect provided by the core-shell nanoparticles. Moreover, nanocomposite film maintains a low dielectric loss of 0.21 at 1 kHz. This research offers a solution for fabricating dielectric composite with large dielectric constant and low dielectric loss, which could be beneficial for the improvement of advanced electronic devices.

Pore-controlled polymer membrane with Mn (II) ion trapping effect for high-rate performance LiMn2O4 cathode

Since Li+ ions can transport through porous channels in the separator containing liquid electrolyte, the electrochemical and structural properties of the separator needs to be improved to develop a high rate performance lithium-ion battery (LIB). In this study, a gel-type polymer membrane using poly (vinylidene fluoride-co-hexafluoropropylene) (P (VDF-HFP)) acting as a matrix and ethylene carbonate (EC) as a separator was applied for a high-performance LIB with LiMn2O4 as a cathode. The cell assembled with the porous polymer gel electrolyte membrane prepared using P (VDF-HFP) with an appropriate amount of EC exhibited an improved capacity (78.8 mAh g−1) and energy density (308.4 mWh g−1) at a current density of 720 mA g−1, and a high capacity retention (94.8%) at a current density of 240 mA g−1, compared to the cell assembled with polyethylene as a separator. The enhanced LIB performance can result from an increased Li+-ion migration between the chains in low-crystalline polymer membranes and an increased volume of the liquid electrolyte for ionic motion in the porous membrane due to an increased porosity.