Synthesis and conductivity performance of hyperbranched polymer electrolytes with terminal ionic groups

Hyperbranched polymer was synthesized from pentaerythritol (as the central core), 1,2,4‐trimellitic anhydride, and epichlorohydrin, and then hyperbranched polymer electrolytes with terminal ionic groups were prepared by the reaction of hyperbranched polymer with N‐methyl imidazole. The chemical structure, thermal behavior, and ionic conductive property of the hyperbranched polymer electrolytes were investigated by ¹H‐NMR, FTIR, differential scanning calorimetry, thermogravimetric analyzer, and complex impedance analysis, respectively. The ionic conductivity of hyperbranched polymer electrolyte was up to 2.4 × 10^?4 S cm^?1 at 30°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study on polyurethane/acrylate crosslinked gel polymer electrolytes

2,4‐Toluene diisocyanate, poly(propylene glycol), poly(ethylene glycol) (PEG) and 2‐hydroxyethyl methacrylate were used to synthesize PEG–UA (urethane acrylate) monomer. The crosslinked polymer and gel polymer electrolytes were prepared in dioxane by free radical polymerization. The swelling behaviour, thermal degradation properties, morphology and ionic conductivity of the gel polymer electrolytes were investigated. With decrease in the proportion of dioxane used, the synthesized polymer's network density increased, its affinity with a solution of 1 M LiClO₄ in propylene carbonate (PC) decreased, and more microgel which diffused in the network. At the same time, the conductivity increased and reached 4 × 10^?4 S cm^?1 at 25 °C. Copyright © 2003 Society of Chemical Industry     

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.     

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     

Effect of plasticizers in poly(vinyl alcohol)‐based hybrid solid polymer electrolytes

Hybrid solid polymer electrolyte films consisting of poly(vinyl alcohol) (PVA), poly(methyl methacrylate) (PMMA), LiBF₄, and ethylene carbonate/propylene carbonate (EC/PC) were prepared with a solvent‐casting technique. The complexation was investigated with Fourier transform infrared and X‐ray diffraction. The ionic conductivities of the electrolyte films were determined with an alternating‐current impedance technique for various temperatures in the range of 302–373 K. The maximum conductivity value, 1.2886 × 10^?3 S/cm, was observed for a PVA–PMMA–LiBF₄–EC complex. Thermogravimetry/differential thermal analysis was performed to ascertain the thermal stability of the electrolyte with the maximum conductivity value. For an examination of the cyclic and reversible performance of the film, a cyclic voltammetry study was carried out. The surface morphology of the EC‐and PC‐based electrolytes was examined with scanning electron microscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2794–2800, 2003     

Effect of reaction kinetics of polymer electrolyte on the ion‐conductive behavior for poly(oligo oxyethylene methacrylate)–LiTFSI mixtures

The effect of the reaction kinetics on the ionic conductivity for a comblike‐type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and ¹H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (T_g), spin–spin relaxation time (T₂), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH₃ showed maximum ionic conductivity, σ_i, two to three times higher in magnitude than that of the σ_i of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003     

Preparation and ionic conductive properties of all‐solid polymer electrolytes based on multiarm star block polymers

A series of star block polymers with a hyperbranched core and 26 arms are successfully synthesized by atom transfer radical polymerization of styrene (St), and poly(ethylene glycol) methyl ether methacrylate from a hyperbranched polystyrene (HBPS) multifunctional initiator. All‐solid polymer electrolytes composed of these multiarm star polymers and lithium salts are prepared. The influences of polyoxyethylene (PEO) side‐chain length, PEO content, lithium salt concentration and type, and the structure of polymer on ionic conductivity are systematically investigated. The resulting polymer electrolyte with the longest PEO side chains exhibits the best ionic conductive properties. The maximum conductivity is 0.8 × 10^?4 S cm^?1 at 25°C with EO/Li = 30. All the prepared multiarm star block polymers possess good thermal stability. The mechanical property is greatly improved owing to the existence of polystyrene blocks in the multiarm star polymer molecules, and flexible films can be obtained by solution‐casting technique. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polymer gel electrolytes prepared from P(EG‐co‐PG) and their nanocomposites using organically modified montmorillonite

Polymer gel electrolytes were prepared by thermal crosslinking reaction of a series of acrylic end‐capped poly(ethylene glycol) and poly(propylene glycol) [P(EG‐co‐PG)] having various geometries and molecular weights. Acrylic end‐capped prepolymers were prepared by the esterification of low molecular weight (M_n: 1900–5000) P(EG‐co‐PG) with acrylic acid. The linear increase in the ionic conductivity of polymer gel electrolyte films was observed with increasing temperature. The increase in the conductivity was also monitored by increasing the molecular weight of precursor polymer. Nanocomposite electrolytes were prepared by the addition of 5 wt % of organically modified layered silicate (montmorillonite) into the gel polymer electrolytes. The enhancement of the ionic conductivity as well as mechanical properties was observed in the nanocomposite systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 894–899, 2004     

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     

Morphology and ionic conductivity of thermoplastic polyurethane electrolytes

Thermoplastic polyurethane (TPU) with a mixture of soft segments [poly(ethylene glycol) (PEG) and poly(tetramethylene glycol) (PTMG)], denoted TPU‐M, was prepared as an ion‐conducting polymer electrolyte. TPUs with PEG and PTMG as soft segments were also synthesized individually as polymer electrolytes. The changes in the morphology and ion conductivity of the phase‐segregated TPU‐based polymer electrolytes as a function of the lithium perchlorate concentration were determined with differential scanning calorimetry, Fourier transform infrared spectroscopy, alternating‐current impedance, and linear sweep voltammetry measurements. Both solid and gelatinous polymer electrolytes were characterized in this study. The effect of temperature on conductivity was studied. The conductivity changes revealed the combined influence of PTMG and PEG units in TPU‐M. The swelling characteristics in a liquid electrolyte and the dimensional stability were evaluated for the three TPUs. Because of its dimensional stability and ionic conductivity, the TPU system containing both PEG and PTMG as soft segments was found to be more suitable for electrolyte applications. A room‐temperature conductivity of approximately 1 × 10^?4 was found for TPU‐M containing 50 wt % liquid electrolyte. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1154–1167, 2004     

Effect of nanofiller concentration on conductivity and dielectric properties of poly(ethylene oxide)–poly(methyl methacrylate) polymer electrolytes

This paper reports the effect of nanofiller concentration on the conductivity and dielectric properties of the poly(ethylene oxide)–poly(methyl methacrylate)–poly(ethylene glycol)–AgNO₃–Al₂O₃ polymer electrolyte system. The preparation of polymer films was done using the solution‐casting technique and characterization of the films was carried out using scanning electron microscopy, differential scanning calorimetry and ionic transport techniques. The ionic conductivity, investigated using impedance spectroscopy, was expected to show interesting behaviour at below and above the melting temperature of poly(ethylene oxide) in the polymer blend films. Complex impedance data were analysed in an alternating current conductivity and dielectric permittivity formalism in order to throw light on the transport mechanism. The effect of nanofiller concentration on conduction and relaxation processes at various temperatures was studied. © 2013 Society of Chemical Industry     

Synthesis and characterization of novel crosslinked polyurethane–acrylate electrolyte

Flexible, transparent, and crosslinked polymer films were synthesized by polymerization of PEG‐modified urethane acrylate using a simple method. A series of novel solid polymer electrolytes and gel electrolytes were prepared based on this type of polymer film. To understand the interactions among salt, solvent, and polymer, the swelling behaviors of the crosslinked polymer in pure propylene carbonate (PC) and liquid electrolyte solutions (LiClO₄/PC) were investigated. The results showed that the swelling rate in the electrolyte solution containing moderate LiClO₄ was greater than that in pure PC. Thermogravimetric analysis (TGA) also supported the interaction between the solvent and polymer. The morphology and crystallinity of the crosslinked polymer and polymer electrolytes were studied using atomic force microscopy (AFM) and wide‐angle X‐ray diffraction (WAXD) spectroscopy. The effects of the content of the electrolyte solution on the ionic conductivity of gel electrolytes were explored. The dependence of the conductivity on the amount of the electrolyte solution was nonlinear. With a different content of the plasticizer, the ionic conduction pathway of the polymer electrolytes would be changed. The best ionic conductivity of the gel electrolytes, which should have good mechanical properties, was 4 × 10^r?3 S cm^?1 at 25°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 340–348, 2003     

Blending poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile) as composite polymer electrolyte

A blend of poly(methyl methacrylate) (PMMA) and poly(styrene‐co‐acrylonitrile) (PSAN) has been evaluated as a composite polymer electrolyte by means of differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, ac impedance measurements, and linear sweep voltammetry (LSV). The blends show an interaction with the Li⁺ ions when complexed with lithium perchlorate (LiClO₄), which results in an increase in the glass‐transition temperature (T_g) of the blends. The purpose of using PSAN as another component of the blend is to improve the poor mechanical properties of PMMA‐based plasticized electrolytes. The mechanical property is further improved by introducing fumed silica as inert filler, and hence the liquid electrolyte uptake and ionic conductivity of the composite systems are increased. Room‐temperature conductivity of the order of 10^?4 S/cm has been achieved for one of the composite electrolytes made from a 1/1 blend of PSAN and PMMA containing 120% liquid electrolyte [1M LiClO₄/propylene carbonate (PC)] and 10% fumed silica. These systems also showed good compatibility with Li electrodes and sufficient electrochemical stability for safe operation in Li batteries. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1319–1328, 2001     

New highly conductive organic–inorganic hybrid electrolytes based on star-branched silica based architectures

A new type of organic–inorganic hybrid electrolyte has been developed by a sol–gel process through the reaction of cyanuric chloride with poly(oxyalkylene) diamine and 3-isocyanatepropyltriethoxysilane, followed by co-condensation of 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane. A maximum ionic conductivity of 1.0 × 10^?4 Scm^?1 at 30 °C has been achieved with the solid hybrid electrolyte. The results of solid-state NMR not only confirm the structural framework of the hybrids, but also provide a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains. The hybrid materials are blended with PVdF-HFP to form the blend hybrid membrane, followed by plasticization with various electrolyte solvents, with the purpose of increasing ionic conductivity. The plasticized blend hybrid electrolyte exhibits a maximum room temperature ionic conductivity of 8.8 × 10^?3 Scm^?1. Such a high ionic conductivity allows it as a potential candidate for applications in lithium ion batteries.     

Perfluoroalkyl‐terminated star polymer electrolyte

A perfluoroalkyl‐terminated multiarm star polymer (perfluoroalkyl‐terminated hyperbranched polyglycerol) was synthesized and characterized on the basis of perfluorooctanoyl chloride grafting on hyperbranched polyglycerol. The conductivity of a blend of the perfluoroalkyl‐terminated star polymer and linear poly(ether urethane) was studied. The results indicated that this blend had better solvating capability in salt and higher ionic conductivity. The conductivity of the blend was 2.5 × 10^?4 S cm^?1 at 60°C when the concentration of the perfluoroalkyl‐terminated hyperbranched polyglycerol was 30 wt % and the ethylene oxide (EO)/Li ratio was 4 in the blend. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 238–242, 2005     

Fabrication and characterization of PEO/PPC polymer electrolyte for lithium‐ion battery

A new poly(propylene carbonate)/poly(ethylene oxide) (PEO/PPC) polymer electrolytes (PEs) have been developed by solution‐casting technique using biodegradable PPC and PEO. The morphology, structure, and thermal properties of the PEO/PPC polymer electrolytes were investigated by scanning electron microscopy, X‐ray diffraction, and differential scanning calorimetry methods. The ionic conductivity and the electrochemical stability window of the PEO/PPC polymer electrolytes were also measured. The results showed that the T_g and the crystallinity of PEO decrease, and consequently, the ionic conductivity increases because of the addition of amorphous PPC. The PEO/50%PPC/10%LiClO₄ polymer electrolyte possesses good properties such as 6.83 × 10^?5 S cm^?1 of ionic conductivity at room temperature and 4.5 V of the electrochemical stability window. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Properties on novel PVDF‐HFP‐based composite polymer electrolyte with vinyltrimethoxylsilane‐modified ZSM‐5

A kind of novel poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP)‐based composite polymer electrolyte doped with vinyltrimethoxylsilane (DB171 silane)‐modified ZSM‐5 is prepared by phase inversion method (denoted as M‐ZSM‐5 membrane). Physical and chemical properties of M‐ZSM‐5 membrane are studied by SEM, FTIR, TG‐DSC, EIS, and LSV. The results show that thermal and electrochemical stability can reach 400°C and 5 V, respectively; temperature dependence of ionic conductivity follows Vogel–Tamman–Fulcher relation and ionic conductivity at room temperature is up to 4.2 mS/cm; the interfacial resistance reaches a stable value about 325 Ω after 5 days storage at room temperature, which suggests that it can be potentially suitable as electrolyte in polymer lithium ion battery. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

A redox‐mediator‐doped gel polymer electrolyte applied in quasi‐solid‐state supercapacitors

Methylene blue (MB) redox mediator was introduced into polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend host to prepare a gel polymer electrolyte (PVA‐PVP‐H₂SO₄‐MB) for a quasi‐solid‐state supercapacitor. The electrochemical properties of the supercapacitor with the prepared gel polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and self‐discharge measurements. With the addition of MB mediator, the ionic conductivity of gel polymer electrolyte increased by 56% up to 36.3 mS·cm^?1, and the series resistance reduced, because of the more efficient ionic conduction and higher charge transfer rate, respectively. The electrode specific capacitance of the supercapacitor with PVA‐PVP‐H₂SO₄‐MB electrolyte is 328 F·g^?1, increasing by 164% compared to that of MB‐undoped system at the same current density of 1 A·g^?1. Meanwhile, the energy density of the supercapacitor increases from 3.2 to 10.3 Wh·kg^?1. The quasi‐solid‐state supercapacitor showed excellent cyclability over 2000 charge/discharge cycles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39784.     

Physical and electrochemical properties of low molecular weight poly(ethylene glycol)‐bridged polysilsesquioxane organic–inorganic composite electrolytes via sol–gel process

A new class of ionic conducting organic/inorganic hybrid composite electrolyte with high conductivity, better electrochemical stability and mechanical behavior was prepared through the sol–gel processing between ethylene‐bridged polysilsesquioxane and poly(ethylene glycol) (PEG). The composite electrolyte with 0.05 LiClO₄ per PEG repeat unit has the best conductivity up to 10^?4 S/cm at room temperature with the transference number up to 0.48 and an electrochemical stability window as high as 5.5 V versus Li/Li⁺. Moreover, the effect of the PEG chain length on the properties of the composite electrolyte has also been studied. The interactions between ions and polymer have also been investigated for the composite electrolyte in the presence of LiClO₄ by means of FTIR, DSC, and TGA. The results indicated the interaction of Li⁺ ions with the ether oxygen of the PEG, and the formation of transient crosslinking with LiClO₄, resulting in an increase of the T_g of the composite electrolyte. The VTF‐type behavior of the ionic conductivity implied that the diffusion of the charge carriers was assisted by the segmental motions of the polymer chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2752–2758, 2007     

Preparation and performance analysis of barium titanate incorporated in corn starch‐based polymer electrolytes for electric double layer capacitor application

Polymer electrolyte membranes composing of corn starch as host polymer, lithium perchlorate (LiClO₄) as salt, and barium titanate (BaTiO₃) as composite filler are prepared using solution casting technique. Ionic conductivity is enhanced on addition of BaTiO₃ by reducing the crystallinity and increasing the amorphous phase content of the polymer electrolyte. The highest ionic conductivity of 1.28 × 10^?2 S cm^?1 is obtained for 10 wt % BaTiO₃ filler in corn starch‐LiClO₄ polymer electrolytes at 75°C. Glass transition temperature (T_g) of polymer electrolytes decreases as the amount of BaTiO₃ filler is increased, as observed in differential scanning calorimetry analysis. Scanning electron microscopy and thermogravimetric analysis are employed to characterize surface morphological and thermal properties of BaTiO₃‐based composite polymer electrolytes. The electrochemical properties of the electric double‐layer capacitor fabricating using the highest ionic conductivity polymer electrolytes is investigated using cyclic voltammetry and charge‐discharge analysis. The discharge capacitance obtained is 16.22 F g^?1. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43275.