Gel Polymer Electrolyte Films Research Articles

Investigation on the properties of PVDF matrix composite porous gel polymer electrolyte doped with lithium silicon gel

Gel polymer electrolytes are safer because they do not contain liquid phase components. On this basis, the introduction of inorganic fillers effectively overcame the problem of low ionic conductivity of polymer electrolyte at room temperature, and the constructed composite polymer electrolyte (CPEs) combined the advantages of inorganic fillers and polymer segments. In this paper, lithium silicon gel SiO2(Li+) was prepared by in-situ polymerization and sol-gel method, and doped in PVDF composite porous gel polymer electrolyte film prepared by immersion precipitation method. The electrochemical properties and surface topography of lithium iron phosphate were investigated by mounting a bonded lithium iron phosphate quasisolid lithium-ion battery. The experimental results show that the solid electrolyte film modified by SiO2(Li+) has good electrochemical and a certain reference value.

Flexible gel polymer electrolyte comprising high flash point solvent adiponitrile with ethylene carbonate as co-solvent for sodium-ion batteries

Due to the unique properties like high flash point, low vapor pressure and high electrochemical stability, the adiponitrile (ADN) as co-solvent with ethylene carbonate (EC) is proposed as an electrolyte solvent for sodium-ion batteries (NIBs). Here, we report a flexible thick film of a gel polymer electrolyte (GPE) containing a Na-salt (sodium triflate), dissolved in a mixture of ADN:EC, entrapped in poly(vinylidene fluoride-co-hexafluoropropylene) for use in NIBs. The structural/morphological studies of the GPE film are performed by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. The electrolyte offers excellent performance characteristics with high ionic conductivity (σRT ∼ 4.6 × 10−3 S cm−1) and Na+-transport number (tNa+ ∼ 0.77), wide electrochemical potential range (∼5.0 V vs. Na/Na+) at room temperature, and sufficient thermal stability (up to ∼120 °C), making the GPE-film attractive for sodium-ion storage. The Na-stripping/plating measurements for a long duration show excellent reversibility of the electrolyte with Na-electrodes, revealing low and stable polarization. The sodium-ion half-cell (Na0.44MnO2/GPE/Na-metal) shows prominent charge–discharge cycling stability, with a discharge capacity of ∼85.5 mAh g−1 at a current rate of 0.1C, and good rate capability up to 1C. The GPE-film has also been tested in a full sodium ion-cell fabricated with sodiated bismuth powder and Na0.44MnO2 as anode and cathode materials, respectively. The full cell offers discharge capacity of ∼55.7 mAh g−1 at 0.1C with stable cycling performance. The results indicate that the GPE film has potential applications as high performance electrolyte for Na-storage.

Structural, thermal, and electrochemical studies of biodegradable gel polymer electrolyte for electric double layer capacitor

A quasi-solid-state supercapacitor is fabricated using a biodegradable gel polymer electrolyte (GPE), and graphene nano-platelets (GNPs) capacitive electrodes. The GPE film comprises biodegradable polymer cellulose acetate (CA), ionic liquid, 1-ethyl-3-methylimidazolium thiocyanate (EMImSCN) and dopant salt potassium thiocyanate (KSCN). The polymeric gel films are prepared using the standard “solution cast technique” and characterized by using X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermogravemetric analysis (TGA), Impedance spectroscopy, and Linear sweep voltammetry techniques. The synthesized GPE exhibits maximum room temperature ionic conductivity ∼1.2 x 10−3 S cm−1 and an electrochemical stability window of ∼2.4 V. The electrical double layer capacitor (EDLC) is configured by sandwiching the GPE film between two graphene nanoplatelets (GNPs) electrodes. The performance of the EDLC cell is evaluated in terms of specific capacitance, rate, and pulse power by using cyclic voltammetry, and electrochemical impedance measurement techniques.

A gel polymer electrolyte film based on chitosan derivative and ionic liquid for the LiFePO4 cathode solid Li metal battery

Solid electrolytes can improve the safety of Li metal batteries. However, the performance of solid electrolyte is still not satisfactory due to its poor high-temperature stability, low ionic conductivity, and poor interface stability/compatibility with electrodes. By combining chitosan-based polymer substrates with ionic liquids, we designed and synthesized two types of solid gel polymer electrolyte (SGPE, i.e., HA-BF4 and HA-TFSI) films. The optimal SGPE film (i.e., HA-BF4-80) exhibited good high-temperature stability (270 °C), high ionic conductivity (2.03 × 10−3 S cm−1 at 35 °C), and excellent interface stability/compatibility with electrodes. It had a wide electrochemical window of 4.60 V and high Li+ transport number of 0.54. With LiFePO4 as the cathode, the HA-BF4-80 SGPE film as solid electrolyte, and the Li metal as anode, the Li|HA-BF4-80|LiFePO4 displayed a higher specific capacity of 152 mAh g−1 and excellent cycle performance with a capacity retention of 82% even after 100 cycles underscoring the significant potential applications of HA-BF4-80 SGPE film in solid lithium metal batteries. This work would have an important value in the design and development of the high-performance SGPE films.

Poly(poly[ethylene glycol] methyl ether methacrylate)/graphene oxide nanocomposite gel polymer electrolytes prepared by controlled and conventional radical polymerizations for lithium ion batteries

Nanocomposite gel polymer electrolyte (GPE) films based on poly(poly[ethylene glycol] methyl ether methacrylate)/graphene oxide (GO) (P[PEGMA-GO]) have been prepared by in situ conventional free radical polymerization (FRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization as controlled radical polymerization (CRP) using 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) as RAFT agent. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that prepared nanocomposite films had amorphous structure and also, thermogravimetric analysis (TGA) showed appropriate thermal stability of samples. GPEs prepared via FRP showed slight higher ionic conductivity that GPEs prepared via RAFT polymerization. In both synthetic approaches, an optimum GO amount of 0.3 wt. % was obtained considering ionic conductivity. At ambient temperature, P(PEGMA-GO) with 0.3 wt. % GO prepared via FRP indicated the highest ionic conductivity of 4.05 × 10−3 S cm−1, a satisfactory lithium ion transference number (t+) of 0.6, and the excellent interface compatibility with electrodes. The lithium ion battery with P(PEGMA-GO0.3%) as GPE also exhibited electrochemical stability window up to 4.6 V vs. Li/Li+, a high charge-discharge capacity of 179 mAh g−1 at 0.1 C, and capacity retention of 91% after 100 cycles.

Electrochemical and AC Conductivity Studies of PVA based Gel Polymer Electrolytes for Silver Ion Batteries

An effort has been made to synthesize PVA based gel polymer electrolyte films by means of solution casting technique doped with silver ion in different concentration of polymer and salt (80:20, 70:30 and 60:40 wt.%). The resulting PVA and CH3COOAg gel polymer electrolyte (GPE) material came to be analyzed through various characterization methods for instance XRD, FTIR and UV-Vis spectrophotometry. The analysis of FTIR and XRD confirmed the polymer and salt complexation. The ionic conductivity for prepared GPE was evaluated by means of AC impedance studies at room temperature. The highest value of ionic conductivity found for PVA: CH3COOAg (30 wt.%) system was found to be 1.422 × 10-5 S cm-1. The optical and cyclic voltammetric analysis have been examined and excellent cyclic, reversible performance was observed for the electrolyte PVA:CH3COOAg (70:30 wt.%) up to 10 cycles.

Lithium- gel polymer electrolyte composite anode with large electrolyte-lithium interface for solid-state battery

Solid-state lithium metal battery have great advantages in energy density and safety, but their interface problems limit the rate performance and cycle performance, leaving it still far from practical. Here, aiming at the problems of the interface, we prepared a Lithium-gel polymer electrolyte (Li-GPE) composite anode by coiling and cutting the Stacked Gel polymer electrolyte film and lithium foil. The Li-GPE composite anode has a lithium-GPE vertical alternating array structure and this structure can provide a continuous lithium ion transmission channel when the volume changes caused by lithium stripping or plating. In addition, the structure has a large lithium-electrolyte interface, which can reduce local current density and interface resistance when current passes through the anode, and making the stripping and plating of lithium more uniform. Electrochemical tests show that the LG composite anode has excellent rate performance and large capacity cycling performance. LG composite anode can be cycled stably for 800 cycles at a large capacity of 5mAh cm−2, and the assembled LG-LFP solid-state full cell can cycle stably for more than 800 times at a high rate of 5 C. LG composite anode with large interface provides a new approach for the practical application of solid-state lithium battery.

High-Energy-Density Carbon Supercapacitors Incorporating a Plastic-Crystal-Based Nonaqueous Redox-Active Gel Polymer Electrolyte

Addition of redox additives in electrolytes to enhance the electrochemical activity at electrode–electrolyte interfaces is one of the prime approaches these days to develop high-energy-density supercapacitors. Here, we report an investigation on a quasi-solid-state supercapacitor, fabricated with a nonaqueous, gel polymer electrolyte (GPE) based on a mixture of a plastic crystal succinonitrile and an ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl) imide, added with a redox additive hydroquinone (HQ), immobilized in a polymer poly(vinylidine fluoride-co-hexafluoropropylene). The HQ-incorporated GPE is observed to be a freestanding, easily processible, and reusable film, showing excellent flexibility and thermal stability up to ∼100 °C. The high ionic conductivity (∼4.2 mS cm–1) and wide electrochemical stability window (∼5.0 V) through linear sweep voltammetry measurements make the optimum composition of GPE a potential electrolyte for high-energy-density supercapacitors. The symmetric supercapacitor coin cells have been fabricated with peanut shell-derived porous carbon electrodes separated by GPE films. The electrochemical activity due to the presence of HQ at carbon electrode–GPE interfaces introduces additional pseudocapacitance over the double-layer capacitance, leading to enhanced overall specific capacitance (289 F g–1), and hence corresponds to the high specific energy (∼40 Wh kg–1) and maximum power (∼20 kW kg–1). The capacitor cell shows prolonged cyclic profile up to ∼10 000 charge–discharge cycles with ca. 85–93% Coulombic efficiency.

Enhancing the electrochemical performance of a flexible solid-state supercapacitor using a gel polymer electrolyte

The development of high-performance polymer electrolytes will be a crucial research target for flexible solid-state supercapacitors (FSSCs). In this study, a flexible gel polymer electrolyte (GPE) was fabricated to enhance flexible solid-state supercapacitor (FSSC) performance and electrochemical stability. 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfony)imide was used as ionic liquid (IL), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as a host polymer with Li1.5Al0.33Sc0.17Ge1.5(PO4)3 (LASGP) serving as ceramic filler to fabricate the GPE films. Scanning electron microscope (SEM) image confirmed that a homogeneous uniform phase with a smooth surface was formed as the ionic liquid was added into the host polymer solution. X-ray diffraction (XRD) patterns show that the PVDF-HFP blend has a semi-crystalline structure while its amorphous nature extended with the increasing amount of IL and LASGP ceramic fillers. The GPE film was used as the electrolyte and separator, due to its high ionic conductivity (7.8×10-2 S cm−1) and excellent thermal stability up to 346 ℃. The FSSC cell with LASGP ceramic filler exhibits a high specific capacitance (115.45 F g−1) with a specific energy density of 27.10 Wh kg−1 at 1 mA. These results indicate that a GPE film with an activated carbon electrode could be a candidate for FSSC applications.

Performance enhancement of Na+ ion conducting porous gel polymer electrolyte using NaAlO2 active filler

In this paper, we report the enhanced electrochemical characteristic performance of porous gel polymer electrolyte, due to dispersion of sodium aluminate (NaAlO2) active fillers in it. The salt solution consisting of, sodium perchlorate (NaClO4) dissolved in binary mixture of ethylene carbonate and propylene carbonate (EC:PC) was entrapped in poly(vinylidinefluoride-co-hexafluoropropylene) (PVdF-HFP) polymer matrix to obtain the micro-porous sodium ion conducting gel polymer electrolyte films by using the phase inversion technique. Small loading of the active NaAlO2 fillers in gel polymer electrolyte results in significantly improved ionic conductivity (σmax=0.68 mS cm−1 at room temperature), Na+ ion transference number (tNa+∼ 0.45) and electrochemical stability window (ESW ∼ 4.1 V). Dielectric studies have been performed to explore the ion dynamics in the electrolyte system. The Na-S prototype battery delivers maximum discharge capacities of ∼ 210, 139 and 51 mA h g−1 at drain currents of 0.10, 0.25 and 0.50 mA cm-2, respectively. The optimized electrolyte composition with high liquid retention, conductivity and transport properties can be utilized for upcoming sodium batteries operating at room temperature.

A high performance flexible gel polymer electrolyte incorporated with suberonitrile as additive for quasi-solid carbon supercapacitor

We report a novel composition of a free-standing, flexible gel polymer electrolyte (GPE) film comprising a polymer poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), immobilizing a solution of lithium bis(trifluoromethane sulfonyl)imide in suberonitrile for use in quasi-solid-state carbon supercapacitor. Physicochemical properties, characterized by SEM, X-ray diffraction, FTIR, and TGA/DSC along with its high ionic conductivity (σRT ~1.2 × 10−3 S cm−1) and wide electrochemical stability window (~4.23 V versus Ag) make the GPE a potential electrolyte/separator for supercapacitors. Quasi-solid-state symmetrical supercapacitor has been assembled using the suberonitrile-based-GPE and activated carbon electrodes derived from a waste-biomass (pinecone). The supercapacitors are tested by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge. The capacitor offers specific capacitance of 220–230 F g−1, which corresponds to high specific energy and power (27–32 Wh kg−1and 12.5–13.5 kW kg−1, respectively). The device shows excellent cyclic performance for ~20000 charge-discharge cycles with ~10% initial fading and a safe performance over a wide temperature range.

Dielectrics and battery studies on flexible nanocomposite gel polymer electrolyte membranes for sodium batteries

In the present study, electrochemical impedance analysis in terms of electrical conductivity, dielectric permittivity, and electrical modulus has been carried out of prepared sodium ion-conducting nanocomposite gel polymer electrolyte. To study ion conduction behavior, frequency-dependent AC conductivity has also been analyzed. Dielectric constant (e′) and dielectric loss (e′′) as a function of frequency with different nanofiller SiO2 concentrations as well as at different temperatures ranging from 303 to 333 K have been discussed. The low-frequency region showed high values of dielectric constant due to polarization at the electrode–electrolyte interface. Frequency-dependent real (M′) and imaginary part (M′′) of modulus reveal large capacitance associated with it at lower frequency whereas dispersion (conductivity relaxation) at a higher frequency. The tangent loss (tan δ) of the electrolyte systems has been determined for different frequencies and concentrations of fumed silica nanoparticles. The high conducting nanocomposite gel polymer membrane exhibited an electrochemical stability window of ≈ 3.3 V which is sufficient to apply this material as a separator for electrochemical device application. The conductivity, dielectric, modulus, and electrochemical stability studies reveal that sodium ion-conducting nanocomposite gel polymer electrolytes offer good electrochemical properties and are suitable for application in any electrochemical/power conversion device. The optimized flexible nanocomposite gel polymer electrolyte films have been used in a prototype sodium battery, which shows a stable open-circuit potential of ~ 2.1 V and a significant first specific discharge capacity of ~ 500 mAh g−1 at a drain current of 14 mA g−1.

Tripropyl Chitosan Iodide-Based Gel Polymer Electrolyte as Quasi Solid-State Dye Sensitized Solar Cells

Electrolyte as one of the major components in dye sensitized solar cells (DSSCs) plays an important role in dye regeneration and as the inner charge carrier transport between electrodes. Gel polymer electrolyte is a potential alternative to liquid electrolytes which suffer of leakage and solvent evaporation. In this present research, functionalization of chitosan by the quaternization reaction of chitosan with iodopropane forming tripropyl chitosan iodide is proposed for the preparation of gel polymer electrolyte. Tripropyl chitosan iodide was characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Four different polymer electrolytes were tested at different compositions in presence of iodide/triiodide redox salt and imidazolium ionic liquid in DSSCs configurations. The results show that the gel polymer electrolyte containing the tripropyl chitosan iodide in presence of 1-propyl-3-methylimidazolium iodide ionic liquid showed better performance with power conversion efficiency of 0.415% as compared to the gel polymer electrolyte film without ionic liquid with power conversion efficiency of 0.075%. The results shown the synergistic effects of the polycationic tripropyl chitosan iodide with the ionic liquid 1-propyl-3-methylimidazolium iodide on the photovoltaic performance.

Organic-inorganic multi-scale enhanced interfacial engineering of sulfide solid electrolyte in Li-S battery

The developing sulfide solid electrolyte is a promising way to overcome shuttle effect of polysulfide in the traditional liquid Li-S battery. However, an air stable sulfide solid electrolyte and competitive solid–solid interface structure must be constructed firstly. Herein, we have designed an organic–inorganic multi-scale composite electrolytes to overcome the interfacial issues of solid state Li-S batteries (SSLSBs). The organic–inorganic composite electrolyte consists of a gel polymer electrolyte (GPE) and an oxygen doped inorganic sulfide solid electrolyte. The O doped sulfide solid electrolyte improves its chemical stability and suppresses the lithium dendrites. A thin GPE film protects the crystal structural stability during cycles and greatly enhances the performance of O doped sulfide solid electrolyte due to the GPE not only constructs soft interface contact between S cathode and solid electrolyte, but also builds lithium ion transport paths by ionic liquid between them. Those SSLSBs display a very good cycling performance with the specific capacity of 1023 mAh/g after 50 cycles at 60 °C and 541 mAh/g after 150 cycles at 30 °C under same rate of 0.1 C. This study demonstrates that the development of advanced solid-state Li-S battery needs to fully integrate a number of technical advantages.

Gel polymer electrolyte based on PVDF-HFP:PMMA incorporated with propylene carbonate (PC) and diethyl carbonate (DEC) plasticizers : electrical, morphology, structural and electrochemical properties

To overcome the drawbacks of organic solvent−based liquid electrolytes and a solid polymer electrolyte as a separator in lithium polymer battery, in the recent study gel polymer electrolyte (GPE) using poly(vinylidene fluoride− hexafluropropylene) (PVDF−HFP) and poly (methyl methacrylate) (PMMA) as host polymers, lithium perchlorate (LiClO4) salt as conducting species and propylene carbonate (PC) and diethyl carbonate (DEC) plasticizers as an organic solvent has been prepared. The solution casting technique has been adopted to fabricate gel polymer electrolyte (GPE). The prepared GPE films were analyzed using different experimental techniques to discover the properties of GPE. The ionic conductivity of GPE films has been carried out using electrochemical impedance spectroscopic technique. The maximum ionic conductivity of 3.97E-4 S cm−1 has been obtained for GPE having 60 wt% PC:DEC. As an evidence of change in ionic conductivity, structural characterization has been analyzed using FTIR and SEM where, FTIR spectra reveal complex formation taking place between polymers, salt, and plasticizers and SEM micrograph shows a change in surface morphology with a change in plasticizers amount. Dielectric analysis has been also carried out in terms of dielectric constant () and dielectric loss (). Cyclic voltammetry (CV) has been applied to find electrochemical stability window.

Solid-state supercapacitor with impressive performance characteristics, assembled using redox-mediated gel polymer electrolyte

A solid-state supercapacitor is assembled using redox-mediated gel polymer as the electrolyte and separator and coconut shell–derived, steam-activated carbon as the electrodes. The gel polymer electrolyte (GPE) is based on poly(vinyl alcohol) (PVA)-potassium hydroxide (KOH)-hydroquinone (HQ), and is obtained using solution casting technique. Amorphous nature of the GPE is confirmed from XRD studies and the complex formation in the GPE is confirmed from FTIR spectral analysis. The GPE films are electrochemically characterized using impedance analysis, cyclic voltammetry and galvanostatic charge/discharge test. Self-discharge studies of the assembled supercapacitor are also carried out. Higher ionic conductivity around 53 mS cm−1 and superior flexibility serve as the main advantages of this redox-mediated GPE. The electrode-specific capacitance of the supercapacitor is found to be as high as 326.53 F g−1 with a capacity retention of 84.2% after being subjected 1000 charge-discharge cycles at a current density of 0.8 A g−1. The assembled supercapacitors are found to offer quite high energy density and power density around 33.15 Wh kg−1 and 689.58 W kg−1, respectively. These types of redox-mediated, flexible, gel polymer electrolytes are desirable for designing high power solid-state supercapacitors for energy storage applications.

Biopolymer-based carboxylated chitosan hydrogel film crosslinked by HCl as gel polymer electrolyte for all-solid-sate supercapacitors

Gel polymer electrolyte for flexible energy storage devices such as supercapacitors and rechargeable batteries attracts widespread attentions. Herein, we fabricate a flexible, transparent, and eco-friendly gel polymer electrolyte film based on biodegradable polymer of the carboxylated chitosan via phase separation of carboxylated chitosan hydrogel in hydrochloric acid. HCl is the key chemical for crosslinking of film forming, and the process is simple, rapid and non-polluting. The obtained carboxylated chitosan hydrogel film with excellent flexibility exhibits a highest electrolyte uptake rate of 742.0 wt%, and a highest ionic conductivity of 8.69 × 10−2 S cm−1. A symmetric all-solid-state supercapacitors using carbon cloth as current collectors, activated carbon film as electrodes, and carboxylated chitosan hydrogel film as a gel polymer electrolyte shows a high specific capacitance of 45.9 F g−1 at 0.5 A g−1, and the maximum energy density of 5.2 Wh kg−1 at a power density of 226.6 W kg−1. To our knowledge, this is the first time that carboxylated chitosan hydrogel film being used as gel polymer electrolyte for supercapacitors electrolyte. The good results indicate that the carboxylated chitosan as a new gel polymer electrolyte material has great potential in practical applications of all-solid-state, flexible, and portable energy storage devices.

Sodium ion conducting gel polymer electrolyte using poly(vinylidene fluoride hexafluoropropylene)

Gel polymer electrolyte (GPE) films using polyvinylidene fluoride – hexafluoropropylene (PVdF – HFP) matrix were prepared for aim to achieve good sodium-ion conductivity at room temperature. GPE of PVF-HFP were formed by microporous PVDF-HFP membranes filled and swollen in different liquid electrolytes: GPEs were formed by microporous PVDF-HFP membranes filled and swollen in different liquid electrolytes: NaClO4, NaPF6 and NaTFSI salts dissolved in mixtures of carbonate solvents (propylene carbonate (PC), fluoroethylenecarbonate (FEC)) or ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide and 1-butyl-3-methyl bis(trifluoromethanesulfonyl)imide). The effect of different electrolytes on the structure and morphology, electrolyte absorption and sodium ionic conductivity of activated membrane were investigated. GPEs showed “sponge-like” structure with high porosity of 80–85% and large pore size. The ionic conductivity of GPEs reached 1–2 mS.cm−1 at room temperature. Sodium intercalation into Na0.44MnO2 electrode was performed in coin-cell type by using GPEs as conduction media. Cycling data of sodium cell using PVdF-HFP/NaClO4 1 M-PC:2%FEC exhibited an excellent stable specific capacity of 100 mAh.g−1 at room temperature.

Plastic crystal-incorporated magnesium ion conducting gel polymer electrolyte for battery application

Studies on a novel composition of magnesium ion conducting gel polymer electrolyte (GPE), comprising a solution of Mg-salt, magnesium trifluoromethanesulfonate (Mg-triflate or \(\hbox {Mg(Tf)}_{2})\) in a plastic crystal succinonitrile (SN), entrapped in a host polymer poly(vinylidenefluoride–hexafluoropropylene) (PVdF–HFP) was reported. Small amount of an ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) was added to stabilize the GPE composition. The electrolyte possesses excellent dimensional integrity in the form of free-standing thick film, which offers the ionic conductivity of \(4 \times 10^{-3} \hbox { S } \hbox {cm}^{-1}\) at room temperature \({\sim }26{^{\circ }}\hbox {C}\). The electrochemical potential window of the electrolyte, observed from the linear sweep voltammetry, is determined to be \({\sim }4.1 \hbox { V}\). The magnesium ion conduction in the GPE film is confirmed from cyclic voltammetry, electrochemical impedance spectroscopy and dc polarization techniques. Different structural, thermal and electrochemical studies demonstrate the promising characteristics of the polymer film, suitable as electrolyte in rechargeable magnesium batteries. The potential of the GPE as electrolyte/separator was ascertained by fabricating a prototype magnesium battery of the configuration Mg:graphite composite \(\hbox {anode}/\hbox {GPE}/\hbox {MnO}_{2}\)-cathode. The specific discharge capacity of \(40 \hbox { mAh g}^{-1}\) (with respect to the \(\hbox {MnO}_{2}\) cathode material) was obtained at the first discharge. The cell shows charge–discharge performance for eight cycles with a substantial fading in capacity.

High Performance Poly(vinyl alcohol)-Based Li-Ion Conducting Gel Polymer Electrolyte Films for Electric Double-Layer Capacitors.

With 1-methyl-2-pyrrolidinone (NMP) as the solvent, the biodegradable gel polymer electrolyte films are prepared based on poly(vinyl alcohol) (PVA), lithium bis(trifluoromethane)sulfonimide (LiTFSI), and 1-ethyl-3 methylimidazoliumbis(trifluoromethylsulfonyl)imide (EMITFSI) by means of solution casting. The films are characterized to evaluate their structural and electrochemical performance. The 60PVA-40LiTFSI + 10 wt.% EMITFSI system exhibits excellent mechanical properties and a high ionic transference number (0.995), indicating primary ionic conduction in the film. In addition, because of the flexibility of polymer chain segments, its relaxation time is as low as 5.30 × 10−7 s. Accordingly, a high ionic conductivity (3.6 × 10−3 S cm−1) and a wide electrochemical stability window (~5 V) are obtained. The electric double-layer capacitor (EDLC) based on this electrolyte system shows a specific capacitance of 101 F g−1 and an energy density of 10.3 W h kg−1, even after 1000 charge-discharge cycles at a current density of 0.4 A g−1 under a charging voltage of 2 V. All these excellent properties imply that the NMP-soluble 60PVA-40LiTFSI + 10 wt.% EMITFSI gel polymer electrolyte could be a promising electrolyte candidate for electrochemical device applications.