Gel Polymer Electrolyte with Anion‐Trapping Boron Moieties via One‐Step Synthesis for Symmetrical Supercapacitors

A novel gel polymer electrolyte (GPE) which is based on new synthesized boron‐containing monomer, benzyl methacrylate, 1 m LiClO₄/N,N‐dimethylformamidel liquid electrolyte solution is prepared through a one‐step synthesis method. The boron‐containing GPE (B‐GPE) not only displays excellent mechanical behavior, favorable thermal stability, but also exhibits an outstanding ionic conductivity of 2.33 mS cm^?1 at room temperature owing to the presence of anion‐trapping boron sites. The lithium ion transference in this gel polymer film at ambient temperature is 0.60. Furthermore, the symmetrical supercapacitor which is fabricated with B‐GPE as electrolyte and reduced graphene oxide as electrode demonstrates a broad potential window of 2.3 V. The specific capacitance of symmetrical B‐GPE supercapacitors retains 90% after 3000 charge–discharge cycles at current density of 1 A g^?1.     

Preparation of rechargeable lithium batteries with poly(methyl methacrylate) based gel polymer electrolyte by <Emphasis Type="Italic">in situ</Emphasis>γ-ray irradiation-induced polymerization

An admixture of commercial liquid electrolyte (LB302, 1 M solution of LiPF₆ in 1:1 EC/DEC) and methyl methacrylate (MMA) was enclosed in CR2032 cells. The assembled cells were then -ray-irradiated using configurations of half cells and full cells. Through this in situ irradiation polymerization process, we obtained rechargeable lithium ion cells with poly(methyl methacrylate) (PMMA) based gel polymer electrolytes (GPE). Galvanostatic cycling, AC impedance spectroscopy, and cyclic voltammetry were employed to investigate the electrochemical properties of the cells and the gel polymer electrolyte. This PMMA-based gel polymer electrolyte was found to exhibit a high ionic conductivity (at least 10^–3 S cm^–1) at room temperature. Due to a significant increase in the charge transfer resistance between the GPE and the cathode, the cell impedance of a PMMA-based lithium ion cell is greater than that of a liquid-electrolyte-based cell. The discharge capacity of a LiNi_0.8Co_0.2O₂/GPE/graphite is approximately 145 mAh g^–1 for the first cycle and decreases to123 mAh g^–1 after 20 cycles. In addition, a large initial cell impedance (LICI) was observed in the irradiated positive half cell. In this paper, we propose a possible mechanism related to the detachment of the PMMA layer from the lithium electrode. This detachment of the PMMA layer from the lithium electrode has not been explicitly discussed previously.     

A novel electrospun TPU/PVdF porous fibrous polymer electrolyte for lithium ion batteries

Novel blend-based gel polymer electrolyte (GPE) films of thermoplastic polyurethane (TPU) and poly(vinylidene fluoride) (PVdF) (denoted as TPU/PVdF) have been prepared by electrospinning. The electrospun thermoplastic polyurethane-co-poly (vinylidene fluoride) membranes were activated with a 1M solution of LiClO₄ in EC/PC and showed a high ionic conductivity about 1.6 mS cm⁻¹ at room temperature. The electrochemical stability is at 5.0 V versus Li⁺/Li, making them suitable for practical applications in lithium cells. Cycling tests of Li/GPE/LiFePO4 cells showed the suitability of the electrospun membranes made of TPU/PVdF (80/20, w/w) for applications in lithium rechargeable batteries. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Semi-interpenetrating gel polymer electrolyte based on PVDF-HFP for lithium ion batteries

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolyte (GPE) is considered one of the promising candidate electrolytes in the polymer lithium ion battery (LIB) because of its free standing, shape versatility, security, flexibility, lightweight, reliability, and so on. However, the pristine PVDF-HFP GPE cannot still meet the requirement of large-scale LIBs and other electrochemical devices due to its relatively low ionic conductivity and deterioration of mechanical strength caused by the incorporation of organic liquid electrolyte into the polymer matrix as well as high cost. In order to overcome above deficiencies of PVDF-HFP based GPE, ultraviolet (UV)-curable semi-interpenetrating polymer network is designed and synthesized through UV-irradiation technique, and the as-prepared semi-interpenetrating matrix is constituted by pentaerythritol tetracrylate polymer network and PVDF-HFP. The ionic conductivity of the optimized GPE is as high as 5 × 10⁻⁴ S/cm and electrochemical window is up to 4.8 V at room temperature. Especially, the LIB prepared by GPE shows the high initial discharge specific capacity of 151 mAh/g at 0.5 C and good rate capability. Therefore, the semi-interpenetrating GPE based on PVDF-HFP exhibits a promising prospect for the application of rechargeable LIBs.     

Solid Composite Polymer Electrolytes with High Cation Transference Number

This work presents the electrochemical and structural study of the dual modified composite LiBOB-based polymer electrolyte. Modification has been carried out by calix[6]pyrrole (CP) anion trap and nanosize silica filler. The main advantage of the use of LiBOB salt is the high ionic conductivity at near-ambient temperatures and low solid-electrolyte interphase (SEI) resistance. The conductivity of LiBOB:PEO₂₀:CP_0.125 with SiO₂ is slightly lower than 10⁻⁵ Scm⁻¹ at 30 °C, a value higher by about two orders of magnitude than that of the semi-crystalline LiCF₃SO₃ (LiTf)-PEO system. At 75 to 90 °C the bulk ionic conductivity of modified LiBOB polymer electrolyte approaches 1 mScm⁻¹. The transference number of dual-modified LiBOB-polymer electrolyte is about 0.8 at 75 °C. Cyclic voltammetry tests showed a wide electrochemical stability window of the composite polymer electrolyte. The peak power of Li/MoO^xS_y cell with the polymer electrolyte film containing CP and SiO₂ reaches 2.2 mW/cm ² and 3.0 mW/cm ² at 90 and 110 °C, respectively.     

Chemically Modified Polyvinyl Butyral Polymer Membrane as a Gel Electrolyte for Lithium Ion Battery Applications

A novel porous membrane of chemically modified polyvinyl butyral (mPVB), with improved thermal properties and chemical stability for lithium ion battery applications, is successfully synthesized by utilizing the chain extension reaction of the OH units from PVB. The porous mPVB membranes are obtained via the tape casting and phase inversion method. The corresponding gel polymer electrolyte (GPE) is achieved by immersing the as‐prepared membranes in the liquid electrolyte. The electrochemical performances of the GPE show that the mPVB membranes have the features of good uniformity, high porosity ( ≈ 90%), great thermal stability, and high mechanical strength. Moreover, the GPE exhibits good chemical stability, a wide electrochemical window, as well as high ionic conductivity ( ≈ 1.21 × 10^?3 S cm^?1). A test of a Li/GPE/LiFePO₄ battery cell shows a capacity of 147.7 mAh g^?1 and excellent cycling stability, demonstrating the great potential of the mPVB‐based GPE for lithium ion battery applications.     

Enhanced mechanical strength and conductivity of PVFM based membrane and its supporting polymer electrolytes

Polyvinyl formal based polymer electrolyte membranes are prepared via the optimized phase inversion method with poly(ethylene oxide) (PEO) blending. The physical properties of blend membranes and the electrochemical properties of corresponding gel polymer electrolytes (GPEs) are characterized by field emission scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, mechanical strength test, electrolyte uptake test, AC impedance spectroscopy, cyclic voltammetry, and galvanostatic charge–discharge test. The comparative study shows that the appearance of PEO obviously enhances the tensile strength of membranes and the ionic conductivity of corresponding GPEs. When the weight ratio of PEO is 30%, the tensile strength of membrane achieves 12.81 MPa, and its GPE shows high ionic conductivity of 2.20 × 10⁻³ S cm⁻¹, wide electrochemical stable window of 1.9–5.7 V (vs. Li/Li⁺), and good compatibility with LiFePO₄ electrode. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41839.     

Lithium Ion-conducting Blend Polymer Electrolyte Based on PVA–PAN Doped with Lithium Nitrate

A new blend polymer electrolyte based on poly(vinyl alcohol) and polyacrylonitrile doped with lithium nitrate (LiNO₃) has been prepared and characterized. The complexation of blend polymer (92.5 PVA:7.5 PAN) with LiNO₃ has been studied using X-ray diffraction and Fourier transform infrared spectroscopy. Differential scanning calorimetry thermograms show a decrease in glass transition temperature with the addition of salt. The maximum ionic conductivity of the blend polymer electrolyte is 1.5 × 10^?3 Scm^?1 for 15 wt% LiNO₃ doped–92.5 PVA:7.5 PAN electrolyte. The conductivity values obey Arrhenius equation. Ionic transference number measurement reveals that the conducting species are predominantly ions.     

Polymerized ionic liquids with guanidinium cations as host for gel polymer electrolytes in lithium metal batteries

Polymerized ionic liquids (PILs) having guanidinium cations with different counter‐anions, such as PF₆^? and N(CF₃SO₂)₂^? (TFSI^?), were synthesized by copolymerization of a guanidinium ionic liquid monomer with methyl acrylate followed by an anion exchange reaction. Furthermore, incorporating a guanidinium ionic liquid, LiTFSI salt and nano‐size SiO₂, a quaternary gel polymer electrolyte based on one of the PILs as the polymer host was prepared. The quaternary gel polymer electrolyte was chemically stable even at a higher temperature of 80 °C in contact with the lithium anode. In particular, the electrolyte exhibited high lithium ion conductivity, wide electrochemical stability window and good lithium stripping/plating performance. Li/LiFePO₄ batteries with the quaternary gel polymer electrolyte at 80 °C had capacities of 140 and 130 mA h g^?1 respectively at 0.1 and 0.2 C current rates. Copyright © 2011 Society of Chemical Industry     

Non-woven fabric supported poly(acrylonitrile-vinyl acetate) gel electrolyte for lithium ion battery use

This paper reported on a new gel polymer electrolyte (GPE) based on polyethylene (PE) non-woven fabric supported poly(acrylonitrile-vinyl acetate) (P(AN-VAc)/PE) membrane for lithium ion battery use. The preparation and performances of the P(AN-VAc)/PE membrane and its GPE based on 1 M LiPF₆ in dimethyl carbonate/diethylene carbonate/ethylene carbonate (1:1:1 in volume) were investigated with a comparison of the unsupported P(AN-VAc) membrane. It is found that the P(AN-VAc)/PE membrane shows better mechanical strength and pore structure for electrolyte uptake than the P(AN-VAc) membrane, and subsequently the GPE based on P(AN-VAc)/PE exhibits higher ionic conductivity and electrochemical stability on cathode than the GPE based on P(AN-VAc). With the support of the non-woven fabric, the ionic conductivity of the GPE at room temperature increases from 1.4 to 3.8 mS cm⁻¹, the oxidation decomposition potential of the GPE on a stainless steel is improved from 5.0 to 5.6 V (vs. Li/Li⁺). The mesocarbon microbeads (MCMB)/LiMn₂O₄ battery using P(AN-VAc)/PE as separator retains 94% of its initial discharge capacity after 100 cycles at C/2 rate, showing that the P(AN-VAc)/PE membrane is a possible alternative to the expensive separator for current liquid lithium ion battery.     

Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids

New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)₂₀LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy⁺/Li⁺ = 1.0), the ionic conductivity reaches the value of 6.9 × 10⁻⁴ S/cm at 40 °C. The lithium ion transference numbers obtained from polarization measurements at 40 °C were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI.     

Application of polymer gel electrolyte with graphite powder in quasi‐solid‐state dye‐sensitized solar cells

A polymer gel electrolyte with ionic conductivity of 5.11 mS cm⁻¹ was prepared by using poly (acrylonitrile‐co‐styrene) as polymer matrix, acetonitrile and tetrahydrofuran as binary organic mixture solvent, NaI + I₂ as electrolyte, graphite powder and 1‐methylimidazole as additives. The components ratio of the polymer gel electrolyte was optimized, and the influence of the components and temperature on the ionic conductivity of the polymer gel electrolyte and photoelectronic properties of dye sensitized solar cell were investigated. On the basis of the polymer gel electrolyte with the optimized conditions, a quasi‐solid‐state dye‐sensitized solar cell was fabricated and its light‐ to‐electricity energy conversion efficiency of 3.25% was achieved under irradiation of 100 mW cm⁻². POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation and properties of gel‐filled PVDF separators for lithium ion cells

Polyether gel‐filled poly(vinylidene fluoride) separators (GF‐PVDF separators) were prepared by means of thermal crosslinking of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GF‐PVDF and their corresponding gel polymer electrolyte (GPE) were characterized by SEM, DSC, and electrochemical methods. It was found a relatively better GPE could be got when the filled polyether content no more than 60 wt % and its ion conductivity could reach 1.3 × 10^?3 S cm^?1. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 4.6 V (vs. Li/Li⁺). The coulombic efficiency could reach 94% after 100 cycles for the cells using such GPE. The results reveal that the composite polymer electrolyte qualifies as a potential application in lithium cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44473.     

Morphology,crystallinity, and electrochemical properties of in situ formed poly(ethylene oxide)/TiO2 nanocomposite polymer electrolytes

A method to produce nanocomposite polymer electrolytes consisting of poly(ethylene oxide) (PEO) as the polymer matrix, lithium tetrafluoroborate (LiBF₄) as the lithium salt, and TiO₂ as the inert ceramic filler is described. The ceramic filler, TiO₂, was synthesized in situ by a sol–gel process. The morphology and crystallinity of the nanocomposite polymer electrolytes were examined by scanning electron microscopy and differential scanning calorimetry, respectively. The electrochemical properties of interest to battery applications, such as ionic conductivity, Li⁺ transference number, and stability window were investigated. The room‐temperature ionic conductivity of these polymer electrolytes was an order of magnitude higher than that of the TiO₂ free sample. A high Li⁺ transference number of 0.51 was recorded, and the nanocomposite electrolyte was found to be electrochemically stable up to 4.5 V versus Li⁺/Li. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2815–2822, 2003     

Effective influences of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIMTFSI) ionic liquid on the ion transport properties of micro-porous zinc-ion conducting poly (vinyl chloride) /poly (ethyl methacrylate) blend-based polymer electrolytes

A series of new gel polymer electrolytes (GPEs) based on different concentrations of a hydrophobic ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIMTFSI) entrapped in an optimized typical composition of polymer blend-salt matrix [poly(vinyl chloride) (PVC) (30 wt%) / poly(ethyl methacrylate) (PEMA) (70 wt%) : 30 wt% zinc triflate Zn(CF₃SO₃)₂] has been prepared using facile solution casting technique. The AC impedance analysis has revealed the occurrence of the maximum ionic conductivity of 1.10 × 10^?4 Scm^?1 at room temperature (301 K) exhibited by the PVC/PEMA- Zn(OTf)₂ system containing 80 wt% ionic liquid. The addition of EMIMTFSI into the optimized PVC/PEMA- Zn(OTf)₂ system in different weight percentages enhances the number of free zinc ions thereby leading to enrichment of ionic conductivity. The structural and complexation behaviour of the as prepared polymer gel electrolytes was substantiated by subjecting these electrolyte films to X-ray diffraction (XRD) and Attenuated total reflectance - Fourier transformed infrared (ATR-FTIR) investigations. The wider electrochemical stability window ~ 3.23 V and a reasonable cationic transference number (t_Zn ²⁺) of 0.63 have been attained for the polymer gel electrolyte film containing higher loading of (80 wt%) ionic liquid. The development of the amorphous phase of these gel polymer electrolyte membranes with increasing ionic liquid content was observed from scanning electron microscopic (SEM) analysis. The results of the current work divulge the assurance of developing GPEs based on ionic liquids for prospective application in zinc battery systems.     

Effect of surface modified porous inorganic-organic hybrid polyphosphazene nanotubes on the properties of polyethylene oxide based solid polymer electrolytes

2-(2-methyloxyethoxy)ethanol modified poly (cyclotriphosphazene-co-4,4′-sufonyldiphenol) (PZS) nanotubes were synthesized and solid composite polymer electrolytes based on the surface modified polyphosphazene nanotubes added to PEO/LiClO₄ model system were prepared. Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) were used to investigate the characteristics of the composite polymer electrolytes (CPE). The ionic conductivity, lithium ion transference number and electrochemical stability window can be enhanced after the addition of surface modified PZS nanotubes. The electrochemical investigation shows that the solid composite polymer electrolytes incorporated with PZS nanotubes have higher ionic conductivity and lithium ion transference number than the filler SiO₂. Maximum ionic conductivity values of 4.95 × 10⁻⁵ S cm⁻¹ at ambient temperature and 1.64 × 10⁻³ S cm⁻¹ at 80 °C with 10 wt % content of surface modified PZS nanotubes were obtained and the lithium ion transference number was 0.41. The good chemical properties of the solid state composite polymer electrolytes suggested that the inorganic-organic hybrid polyphosphazene nanotubes had a promising use as fillers in solid composite polymer electrolytes and the PEO₁₀-LiClO₄-PZS nanotubes solid composite polymer electrolyte can be used as a candidate material for lithium polymer batteries.     

Study on preparation and properties of gel polymer electrolytes based on comb-like copolymer matrix of poly(ethylene glycol) monomethylether grafted carboxylated butadiene-acrylonitrile rubber

A novel kind of gel polymer electrolytes (GPE) based on comb-like copolymers of poly(ethylene glycol) monomethylether (mPEG) grafted carboxylated butadiene-acrylonitrile rubber (XNBR) were prepared by introducing ionic liquids and LiClO₄ into polymer framework. FTIR spectra confirmed the grafting of mPEG to XNBR as side chains, and the content of grafted mPEG were calculated from the integral area of related peaks in ¹ H NMR spectra. Such grafted copolymer based GPE with ionic liquids as solvent showed higher ionic conductivity and reached a maximum ionic conductivity of 1.64?×?10^?3?S/cm (30?°C) in the experimental range, because the copolymers performed better polymer chain flexibility, which could be concluded from the decrease of T _g and crystallinity through DSC analysis. The generated GPE exhibited high electrochemical stability and the unit cell of LiFePO₄/GPE/Li could be cycled at room temperature.     

Room-Temperature Solid-State Lithium Metal Batteries Using Metal Organic Framework Composited Comb-Like Methoxy Poly(ethylene glycol) Acrylate Solid Polymer Electrolytes

Solid polymer electrolyte with good thermal stability and flexibility is an excellent candidate for solid-state lithium metal batteries, while its low ionic conductivity caused by high crystallinity limits its application at ambient temperature. Here a metal organic framework (zeolitic imidazolate framework-8, ZIF-8) composited comb-like methoxy poly(ethylene glycol) acrylate polymer electrolyte (MCPE) with high ionic conductivity (9.96 × 10⁻⁵ S cm⁻¹ at 30 °C) is prepared by an in situ UV polymerization method. The as-prepared MCPE exhibits improved mechanical property due to the introduction of porous ZIF-8 nanofillers, which is beneficial to suppress the growth of lithium dendrites. Consequently, the LiFePO₄||MCPE||Li cells show a high capacity of 116 mAh g⁻¹ at 30 °C and 0.5 C, and maintain 89.4% of initial capacity after 150 cycles with the average Coulombic efficiency of 99.9%. These results demonstrate that the MCPE shows great potential in solid-state lithium metal batteries near room temperature.     

Preparation and properties of poly(ethylene oxide) gel filled polypropylene separators and their corresponding gel polymer electrolytes for Li-ion batteries

Poly(ethylene oxide) (PEO) filled polypropylene separators (GFPSs) are designed by means of thermal cross-linking of entrapped poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GFPS and their corresponding gel polymer electrolytes (GPE) are characterized by DSC, SEM, contact angle and electrochemical methods. It is found the stability of liquid electrolyte uptake in GPE could be improved obviously. For the GPE prepared from GFPS with filled polyether content of 14.3 wt%, the ionic conductivity could reach 1.12 × 10⁻³ S cm⁻¹ while the electrochemically stable window reach 5.0 V (vs. Li/Li⁺). These primary results show great promise of this simple method to prepare GPE for practical application in lithium ion batteries.     

Synthesis and electrochemical properties of lithium methacrylate-based self-doped gel polymer electrolytes

In this study, a strategy for synthesizing lithium methacrylate (LiMA)-based self-doped gel polymer electrolytes was described and the electrochemical properties were investigated by impedance spectroscopy and linear sweep voltammetry. LiMA was found to dissolve in ethylene carbonate (EC)/diethyl carbonate (DEC) (3/7, v/v) solvent after complexing with boron trifluoride (BF₃). This was achieved by lowering the ionic interactions between the methacrylic anion and lithium cation. As a result, gel polymer electrolytes consisting of BF₃-LiMA complexes and poly(ethylene glycol) diacrylate were successfully synthesized by radical polymerization in an EC/DEC liquid electrolyte. The FT-IR and AC impedance measurements revealed that the incorporation of BF₃ into the gel polymer electrolytes increases the solubility of LiMA and the ionic conductivity by enhancing the ion disassociations. Despite the self-doped nature of the LiMA salt, an ionic conductivity value of 3.0 × 10⁻⁵ S cm⁻¹ was achieved at 25 °C in the gel polymer electrolyte with 49 wt% of polymer content. Furthermore, linear sweep voltammetry measurements showed that the electrochemical stability of the gel polymer electrolyte was around 5.0 V at 25 °C.