Synthesis of networked polymers by copolymerization of monoepoxy‐substituted lithium sulfonylimide and diepoxy‐substituted poly(ethylene glycol), and their properties

Networked polymers that had poly(ethylene glycol) (PEG) chains and lithium sulfonylimide salt structures were prepared by curing a mixture of poly(ethylene glycol) diglycidyl ether and lithium 3‐glycidyloxypropanesulfonyl‐trifluoromethanesulfonylimide with poly(ethylene glycol) bis(3‐aminopropyl) terminated. The obtained flexible self‐standing networked polymer films showed high thermal and mechanical stability with relatively high ionic conductivity. The room temperature ionic conductivity under a dry condition was in the range of 10^?5 ～ 10^?4 S m^?1, which is one order of magnitude higher than the corresponding networked polymers having lithium sulfonate salt structures (10^?6 ～ 10^?5 S m^?1). The film sample became swollen by immersing in propylene carbonate (PC) or PC solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The sample swollen in PC showed higher ionic conductivity (7.2 × 10^?3 S m^?1 at room temperature), and the sample swollen in 1.0 M LiTFSI/PC showed much higher ionic conductivity (8.2 × 10^?1 S m^?1 at room temperature). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation and properties of ionic‐liquid‐containing poly(ethylene glycol)‐based networked polymer films having lithium salt structures

Ionic‐liquid‐containing polymer films were prepared by swelling poly(ethylene glycol)‐based networked polymers having lithium salt structures with an ionic liquid, 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMImFSI), or with an EMImFSI solution of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). Their fundamental physical properties were investigated. The networked polymer films having lithium salt structures were prepared by curing a mixture of poly(ethylene glycol) diglycidyl ether and lithium 3‐glycidyloxypropanesulfonate or lithium 3‐(glycidyloxypropanesulfonyl)(trifluoromethanesulfonyl)imide with poly(ethylene glycol) bis(3‐aminopropyl) terminated. The obtained ionic‐liquid‐containing films were flexible and self‐standing. They showed high ionic conductivity at room temperature, 1.16–2.09 S/m for samples without LiTFSI and 0.29–0.43 S/m for those with 10 wt % LiTFSI. Their thermal decomposition temperature was above 220 °C, and melting temperature of the ionic liquid incorporated in the film was around ?16 °C. They exhibited high safety due to good nonflammability of the ionic liquid. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Novel polymer electrolytes prepared by copolymerization of ionic liquid monomers

Ionic liquid monomer couples were prepared by the neutralization of 1‐vinylimidazole with vinylsulfonic acid or 3‐sulfopropyl acrylate. These ionic liquid monomer couples were viscous liquid at room temperature and showed low glass transition temperature (Tg) at ?83 °C and ?73 °C, respectively. These monomer couples were copolymerized to prepare ion conductive polymer matrix. Thus prepared ionic liquid copolymers had no carrier ions, and they showed very low ionic conductivity of below 10^?9 S cm^?1. Equimolar amount of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to imidazolium salt unit was then added to generate carrier ions in the ionic liquid copolymers. Poly(vinylimidazolium‐co‐vinylsulfonate) containing equimolar LiTFSI showed the ionic conductivity of 4 × 10^?8 S cm^?1 at 30 °C. Advanced copolymer, poly(vinylimidazolium‐co‐3‐sulfopropyl acrylate) which has flexible spacer between the anionic charge and polymer main chain, showed the ionic conductivity of about 10^?6 S cm^?1 at 30 °C, which is 100 times higher than that of copolymer without spacer. Even an excess amount of LiTFSI was added, the ionic conductivity of the copolymer kept this conductivity. This tendency is completely different from the typical polyether systems. Copyright © 2002 John Wiley & Sons, Ltd.     

Cationic polymerization of a novel oxetane‐bearing ionic liquid structure and properties of the obtained poly(ionic liquid)

An ionic liquid, 1‐ethyl‐3‐(3‐ethyl‐3‐oxetanylmethyl)imidazolium bis(trifluoromethanesulfonyl)imide (OXImTFSI), was synthesized, and its cationic polymerization was examined. The heating of a mixture of 1‐ethylimidazole and 3‐chloromethyl‐3‐ethyloxetane at 90 °C for 48 h yielded 1‐ethyl‐3‐(3‐ethyl‐3‐oxetanylmethyl)imidazolium chloride, which was transformed to a room‐temperature ionic liquid, OXImTFSI, by ion exchange with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). This ionic liquid was polymerized using boron trifluoride ethyl ether complex as a catalyst to give polyOXImTFSI. Five percent weight loss temperature (T_d5) of polyOXImTFSI evaluated by thermal gravimetric analysis was 409 °C, indicating the high thermal stability. Glass transition temperature (T_g) of the polymer evaluated by differential scanning calorimetry was ?19 °C, indicating the high flexibility of the material. Ionic conductivity of polyOXImTFSI was determined to be 1.86 × 10^?8 S/cm at 23 °C, which was far lower than that of the OXImTFSI monomer (5.05 × 10^?4 S/cm). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2986–2990     

Ionic conductivity probed in main chain liquid crystalline azobenzene polyesters

Three main chain thermotropic liquid crystalline (LC) azobenzene polymers were synthesized using the azobenzene twin molecule (P4P) having the structure Phenylazobenzene‐tetraethyleneglycol‐Phenylazobenzene as the AA monomer and diols like diethylene glycol, tetraethylene glycol (TEG), and hexaethylene glycol as the BB comonomer. Terminal ? C(O)OMe units on P4P facilitated transesterification with diols to form polyesters. All polymers exhibited stable smectic mesophases. One of the polymers, Poly(P4PTEG) was chosen to prepare composite polymer electrolytes with LiCF₃SO₃ and ionic conductivity was measured by ac impedance spectroscopy. The polymer/0.3 Li salt complex exhibited a maximum ionic conductivity in the range of 10^?5 S cm^?1 at room temperature (25 °C), which increased to 10^?4 S cm^?1 above 65 °C. The temperature dependence of ionic conductivity was compared with the phase transitions occurring in the sample and it was observed that the glass transition had a higher influence on the ionic conductivity compared to the ordered LC phase. Reversible ionic conductivity switching was observed upon irradiation of the polymer/0.3 Li salt complex with alternate UV and visible irradiation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 629–641     

Conductive networked polymer gel electrolytes composed of poly(meth)acrylate,lithium salt,and ionic liquid

Self‐standing films of (meth)acrylate‐based polymer gel electrolytes with high ionic liquid content (80 wt %) were prepared by in situ thermally or photo induced radical copolymerization of mono‐functional and di‐functional (meth)acrylates in an ionic liquid in the presence/absence of a lithium salt. Their ionic conductivity, thermal property, mechanical property, and flammability were examined. 1‐Ethyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide (EMImTFSI) or 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) was used as the ionic liquid, and lithium bis(trifluoromethanesulfonyl)imide LiTFSI was used as the lithium salt. The obtained films were semitransparent and flexible with good to moderate thermal stability and mechanical strength with high ionic conductivity. The EMImFSI‐containing gel electrolytes showed higher ionic conductivity than the corresponding EMImTFSI‐containing gel electrolytes. The ionic conductivity in the acrylate‐based gel electrolytes was slightly increased by addition of lithium salt, while that in the corresponding methacrylate‐based electrolytes was decreased significantly. The flame test showed the ionic liquid containing networked polymer gel electrolytes to have low if any flammability and was therefore confirmed to be highly safe. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Ionic IPNs as novel candidates for highly conductive solid polymer electrolytes

Five ionic imidazolium based monomers, namely 1‐vinyl‐3‐ethylimidazolium bis(trifluoromethylsulfonyl)imide (ILM1), 1‐vinyl‐3‐(diethoxyphosphinyl)‐propylimidazolium bis(trifluoromethylsulfonyl)imide (ILM2), 1‐[2‐(2‐methyl‐acryloyloxy)‐propyl]‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (ILM3), 1‐[2‐(2‐methyl‐acryloyloxy)‐undecyl]‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (ILM4), 1‐vinyl‐3‐ethylimidazolium dicyanamide (ILM5) were prepared and used for the synthesis of linear polymeric ionic liquids (PILs), crosslinked networks with polyethyleneglycol dimethacrylate (PEGDM) and interpenetrating polymer networks (IPNs) based on polybutadiene (PB). The ionic conductivities of IPNs prepared using an in situ strategy were found to depend on the ILM nature, T_g and the ratio of the other components. Novel ionic IPNs are characterized by increased flexibility, small swelling ability in ionic liquids (ILs) along with high conductivity and preservation of mechanical stability even in a swollen state. The maximum conductivity for a pure IPN was equal to 3.6 × 10^?5 S/cm at 20 °C while for IPN swollen in [1‐Me‐3‐Etim] (CN)₂N σ reached 8.5 × 10^?3 S/cm at 20 °C or 1.4 × 10^?2 S/cm at 50 °C. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4245–4266, 2009     

Solid polymer electrolytes based on crosslinkable polyoctahedral silsesquioxanes (POSS) for room temperature lithium polymer batteries

Solid polymer electrolytes (SPE), based on polyoctahedral silsesquioxanes (POSS) as a crosslinking agent, were prepared by radical polymerization. The ionic conductivity is greatly enhanced by introduction of crosslinkable POSS with multifunctional groups. The SPE prepared with 5 wt.% crosslinking agent shows an ionic conductivity of 5.3?×?10^?4 S cm^?1 at room temperature. The content of nonvolatile plasticizer, poly(ethylene glycol) dimethyl ether, in the SPE, could be raised to 95 wt.% without any leakage. The SPE is found to be electrochemically stable up to 5.3 V. Lithium polymer cell consisting of Li/SPE/LiCoO₂ exhibits 80% of initial discharge capacity even at the rate of 0.1 C at room temperature after 20 cycles, which is a substantial improvement for practical consideration of lithium polymer batteries at room temperature.     

Star‐shaped polymers having side chain poss groups for solid polymer electrolytes; synthesis,thermal behavior,dimensional stability,and ionic conductivity

A series of organic/inorganic hybrid star‐shaped polymers were synthesized by atom transfer radical polymerization using 3‐(3,5,7,9,11,13,15‐heptacyclohexyl‐pentacyclo[9.5.1.1^3,9.1^5,15.1^7,13]‐octasiloxane‐1‐yl)propyl methacrylate (MA‐POSS) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) as monomers and octakis(2‐bromo‐2‐methylpropionoxypropyldimethylsiloxy)octasilsesquioxane as an initiator. Star‐shaped polymers with methyl methacrylate (MMA) and PEGMA moieties were also prepared for comparison purposes. Dimensionally stable freestanding film could be obtained from the hybrid star‐shaped polymer containing 26 wt % of MA‐POSS moieties although its glass transition temperature is very low, ?60.9 °C. As a result, the hybrid star‐shaped polymer electrolyte containing lithium bis(trifluoromethanesulfonyl)imide showed ionic conductivities (1.75 × 10^?5 S/cm at 30 °C), which were two orders of magnitude higher than those of the star‐shaped polymer electrolyte with MMA moieties. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Improved properties of polymer electrolyte by ionic liquid PP1.3TFSI for secondary lithium ion battery

A new kind of polymer electrolyte is prepared from N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP1.3TFSI), polyethylene oxide (PEO), and lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). IR and X-ray diffraction results demonstrate that the addition of ionic liquid decreases the crystallization of PEO. Thermal and electrochemical properties have been tested for the solid polymer electrolytes, the addition of the room temperature molten salt PP1.3TFSI to the conventional P(EO)₂₀LiTFSI polymer electrolyte leads to the improvement of the thermal stability and the ionic conductivity (x = 1.27, 2.06 × 10⁻⁴ S cm⁻¹ at room temperature), and the reasonable lithium transference number is also obtained. The Li/LiFePO₄ cell using this polymer electrolyte shows promising reversible capacity, 120 mAh g⁻¹ at room temperature and 164 mAh g⁻¹ at 55 °C.     

Synthesis of polycarbosilanes having a five‐membered cyclic carbonate structure and their application to prepare gel polymer electrolytes for lithium ion batteries

A silacyclobutane having a five‐membered cyclic carbonate structure (SBMC) was prepared, and its transition metal‐catalyzed ring‐opening polymerization at the four‐membered carbosilane unit was investigated as well as formation of carbosilane networked polymers and polymer gel electrolytes. The SBMC was synthesized by epoxidation of 1‐(4‐butenyl)‐1‐methylsilacyclobutane followed by insertion of CO₂ to the epoxide. Ring‐opening polymerization of the silacyclobutane moiety in the SBMC readily proceeded by a transition metal catalyst such as platinum divinyltetramethyldisiloxane complex. A flexible networked polymer film was obtained by copolymerization of the SBMC with a small amount of crosslinker, hexamethylene‐1,6‐bis(1‐methylsilacyclobutane) (HMBS). The copolymerization of SBMC and HMBS in 1 M LiPF₆ solution in ethylene carbonate and diethyl carbonate (3/7 v/v) gave a gel polymer electrolyte, which showed good ionic conductivity and could be applied to lithium ion batteries. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Polymer electrolyte membranes by in situ polymerization of poly(ethylene carbonate‐co‐ethylene oxide) macromonomers in blends with poly(vinylidene fluoride‐co‐hexafluoropropylene)

Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10^?6 S cm^?1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (T_g) of the ion conductive phase by ～5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10^?6 S cm^?1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the T_g of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007     

Composite poly(ethylene carbonate) electrolytes with electrospun silica nanofibers

We prepared a ternary composite polymer electrolyte from poly(ethylene carbonate) (PEC), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and non‐calcined silica nanofibers (SNFs) having 3 average diameters (300, 700, and 1000 nm). The SNF composite electrolytes were obtained as homogeneous, self‐standing membranes. The ionic conductivity of PEC/LiTFSI 100 mol% was increased by the addition of SNFs, and the thinner SNFs with average diameter 300 nm were most effective in improving the conductivity. The conductivity was of the order of 10⁻⁴ S/cm at 60°C. The lithium transference number of the SNF₃₀₀ composite was greater than 0.7. Stress‐strain curves of the composites indicated significant increases in Young's modulus and maximum stress for the PEC electrolytes. The 5% weight‐loss temperature of the composites also improved with the addition of SNF.     

Synthesis and properties of all solid polymer electrolytes based on poly(vinyl acetate‐co‐acetyl ethylene oxide acrylate)

Poly(acetyl ethylene oxide acrylate‐co‐vinyl acetate) (P(AEOA‐VAc)) was synthesized and used as a host for lithium perchlorate to prepare an all solid polymer electrolyte. Introduction of carbonyl groups into the copolymer increased ionic conductivity. All solid polymer electrolytes based on P(AEOA‐VAc) at 14.3 wt% VAc with 12wt% LiClO₄ showed conductivity as high as 1.2 × 10^?4 S cm^?1 at room temperature. The temperature dependence of the ionic conductivity followed the VTF behavior, indicating that the ion transport was related to segmental movement of the polymer. FTIR was used to investigate the effect of the carbonyl group on ionic conductivity. The interaction between the lithium salt and carbonyl groups accelerated the dissociation of the lithium salt and thus resulted in a maximum ionic conductivity at a salt concentration higher than pure PAEO‐salts system. Copyright © 2010 John Wiley & Sons, Ltd.     

Studies on poly(vinyl pyrrolidone) based solid polymer blend electrolytes complexed with various lithium salts

Solid polymer electrolytes (SPEs) with high ionic conductivity and acceptable mechanical properties are of particular interest for increasing the performance of batteries. In the present work, SPEs based on poly(ethylene oxide)/poly (vinyl pyrrolidone) (PEO/PVP) with various lithium salts were prepared by solvent casting technique. The amorphous nature of the polymer-salt complex was studied by X-ray diffraction analysis. The complexation of the prepared electrolytes was confirmed by Fourier transform infrared analysis. Ionic conductivity as a function of frequency was studied at various temperatures in the range of 303–353 K. The maximum ionic conductivity value was found to be 1.08 × 10^?5 S/cm for the film containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) at room temperature and the temperature dependent ionic conductivity values seem to obey Vogel-Tamman-Fulcher relation. Thermogravimetry was used to ascertain the thermal stability of the electrolytes. Photoluminescence measurements demonstrated that the sample having maximum ionic conductivity shows the minimum luminescence intensity. Ultra violet-visible analysis reveals that the values of the band gap energies were changed with the addition of various lithium salts. Porosity of the sample containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) was studied by Atomic force microscope.     

Imidazolium‐based poly(ionic liquid)s with poly(ethylene oxide) main chains: Effects of spacer and tail structures on ionic conductivity

Ten types of cationic glycidyl triazole polymers (GTPs) are prepared from combinations of five alkyl‐imidazolium units (methyl‐, ethyl‐, n‐propyl‐, iso‐propyl‐, and n‐butyl‐imidazoliums) and two spacers [di‐ and tri(ethylene glycol)s]. Since these poly(ionic liquid)s are prepared from the same sample of glycidyl azide polymer by postfunctionalization method, they have the same degree of polymerization. Therefore, the structure–property relationship can be discussed without influence of molecular weight difference. The samples are characterized by NMR, differential scanning calorimetry, and thermogravimetric analysis. The ionic conductivity data are obtained by impedance measurements. The GTPs with the tri(ethylene glycol) spacer and ethyl‐ and n‐butyl‐imidazolium units afford the highest anhydrous conductivity of 1.5 × 10^?5 S cm^?1 at 30 °C. Based on electrode polarization (EP) analysis, we calculate the conducting ion (carrier) concentration and mobility. We discuss the effect of the spacer and N‐alkyl tail structures on the ionic conductivity using the data obtained by EP analysis and X‐ray diffraction. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2896–2906     

Solid polymer electrolytes III: Preparation,characterization, and ionic conductivity of new gelled polymer electrolytes based on segmented,perfluoropolyether‐modified polyurethane

New segmented polyurethanes with perfluoropolyether (PFPE) and poly(ethylene oxide) blocks were synthesized from a fluorinated macrodiol mixed with poly(ethylene glycol) (PEG) in different ratios as a soft segment, 2,4‐toluene diisocyanate as a hard segment, and ethylene glycol as a chain extender. Fourier transform infrared, NMR, and thermal analysis [differential scanning calorimetry and thermogravimetric analysis (TGA)] were used to characterize the structures of these copolymers. The copolymer films were immersed in a liquid electrolyte (1 M LiClO₄/propylene carbonate) to form gel‐type electrolytes. The ionic conductivities of these polymer electrolytes were investigated through changes in the copolymer composition and content of the liquid electrolyte. The relative molar ratio of PFPE and PEG in the copolymer played an important role in the conductivity and the capacity to retain the liquid electrolyte solution. The copolymer with a 50/50 PFPE/PEG ratio, having the lowest decomposition temperature shown by TGA, exhibited the highest ionic conductivity and lowest activation energy for ion transportation. The conductivities of these systems were about 10^?3 S cm^?1 at room temperature and 10^?2 S cm^?1 at 70 °C; the films immersed in the liquid electrolyte with an increase of 70 wt % were homogenous with good mechanical properties. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 486–495, 2002; DOI 10.1002/pola.10119     

All solid polymer electrolytes based on polar side group rotation for rechargeable lithium batteries

A novel polymer matrix with a polar carbonyl group was designed and used to prepare an all‐solid polymer electrolyte in lithium rechargeable batteries. The ionic conductivity of this type of polymer electrolyte was examined. The relationship between the lithium salt concentration and ionic conductivity was investigated by Fourier transform infrared (FTIR) spectroscopy. The carbonyl groups in the polymer matrix effectively interacted with the lithium salt, which improved the ionic conductivity at a large range of temperatures. The ionic conductivity of this type of polymer electrolyte was approximately 10^?4 S cm^?1 at room temperature. The stability of the interface between electrode and electrolyte was evaluated by measuring the alternating current (AC) impedance. Copyright © 2009 John Wiley & Sons, Ltd.     

Application of polyacrylonitrile-based polymer electrolytes in rechargeable lithium batteries

Polyacrylonitrile (PAN)-based polymer electrolytes have obtained considerable attention due to their fascinating characteristics such as appreciable ionic conductivity at ambient temperatures and mechanical stability. This study is based on the system PAN–ethylene carbonate (EC)–propylene carbonate (PC)–lithium trifluoromethanesulfonate (LiCF₃SO₃). The composition 15 mol% PAN–42 mol% EC–36 mol% PC–7 mol% LiCF₃SO₃ has shown a maximum room temperature conductivity of 1.2?×?10^?3 S cm^?1. Also, it was possible to make a thin, transparent film out of that composition. Cells of the form, Li/PAN–EC–PC–LiCF₃SO₃/polypyrrole (PPy)–alkylsulfonate (AS) were investigated using cyclic voltammetry and continuous charge–discharge tests. When cycled at low scan rates, a higher capacity could be obtained and well-defined peaks were present. The appearance of peaks elucidates the fact that redox reactions occur completely. This well proves the reason for higher capacity. The average specific capacity was about 43 Ah kg^?1. Cells exhibited a charge factor close to unity during continuous charging and discharging, indicating the absence of parasitic reactions.     

Highly concentrated polycarbonate‐based solid polymer electrolytes having extraordinary electrochemical stability

Solid polymer electrolytes (SPEs) are compounds of great interest as safe and flexible alternative ionics materials, particularly suitable for energy storage devices. We study an unusual dependence on the salt concentration of the ionic conductivity in an SPE system based on poly(ethylene carbonate) (PEC). Dielectric relaxation spectroscopy reveals that the ionic conductivity of PEC/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte continues to increase with increasing salt concentration because the segmental motion of the polymer chains is enhanced by the plasticizing effect of the imide anion. Fourier transfer‐infrared (FTIR) spectroscopy suggests that this unusual phenomenon arises because of a relatively loose coordination structure having moderately aggregated ions, in contrast to polyether‐based systems. Comparative FTIR study against PEC/lithium perchlorate (LiClO₄) electrolytes suggests that weak ionic interaction between Li and TFSI ions is also important. Highly concentrated electrolytes with both reasonable conductivity and high lithium transference number (t₊) can be obtained in the PEC/LiTFSI system as a result of the unusual salt concentration dependence of the conductivity and the ionic solvation structure. The resulting concentrated PEC/LiTFSI electrolytes have extraordinary oxidation stability and prevent any Al corrosion reaction in a cyclic voltammetry. These are inherent effects of the highly concentrated salt. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2442–2447