Polymer Electrolytes Containing Solvate Ionic Liquids: A New Approach To Achieve High Ionic Conductivity, Thermal Stability, and a Wide Potential Window

Abstract

We describe here the electrochemical properties and battery performance of polymer electrolytes composed of ABA-triblock copolymers and Li-glyme solvate ionic liquids (SILs), which consist of the [Li(glyme)] + complex cation and bis(trifluoromethanesulfoly)amide ([TFSA] − ) anion, to simultaneously achieve high ionic conductivity, thermal stability, and a wide potential window. Three different block copolymers, consisting of a SILincompatible A segment (polystyrene, PSt) and SILcompatible B segments (poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO), and poly(butyl acrylate) (PBA)) were synthesized. The SILs were solidified with the copolymers through physical cross-linking by the selfassembly of the PSt segment. The thermal and electrochemical properties of the polymer electrolytes were significantly affected by the stability of the [Li(glyme)] + complex in the block copolymer B segments, and the preservation of the SILs contributed to their thermal stabilities and oxidation stabilities greater than 4 V vs Li/Li + . Pulsed-field gradient spin−echo nuclear magnetic resonance measurements of the polymer electrolytes and molecular dynamics simulation indicate that the [Li(glyme)] + complex cation is unstable in the PEO matrix because of the competitive coordination of the PEO chain and glyme with Li + . On the other hand, the complex structure of [Li(glyme)] + is stable in the PMMA-and PBA-based polymer electrolytes because of the weak interaction between Li + and the polymer chains. By use of the PMMA-and PBA-based polymer electrolytes, 4-V class Li batteries with a LiCoO 2 cathode and a Li metal anode could be operated stably at 60°C; in contrast, this was not possible using the PEO-based electrolyte.

Self‐Healing Micellar Ion Gels Based on Multiple Hydrogen Bonding

“…For this reason, physically crosslinked ion gels based on ABA triblock copolymers, formed by the association of A endblocks bridged by IL‐philic B midblocks, are very attractive materials . To date, ion gels based on ABA triblock copolymers have been applied to the dielectrics of double‐layer transistors, electrochromic devices, soft actuators, and the gel electrolytes of lithium‐ion batteries …”

Stretchable, Transparent, and Thermally Stable Triboelectric Nanogenerators Based on Solvent‐Free Ion‐Conducting Elastomer Electrodes

“…Since the there is no liquid solvent, it is quite stable in air, showing neither weight loss nor the decay of its conductivity and mechanical properties. Nevertheless, the stretchability for most solid‐state polyelectrolyte is limited, and the report of stretchable ion‐conducting elastomers (ICEs) is rare 45…”

Self-assembly synthesis of solid polymer electrolyte with carbonate terminated poly(ethylene glycol) matrix and its application for solid state lithium battery

“…Consequently, many effort s have been dedicated to improve ionic conductivity of PEG based PEs. Designing novel polymers, e.g., synthesis of block copolymers containing both a conductive segment and an insulating rigid segment [5,6] , cross-linking [7][8][9] , grafting PEG chains onto rigid polymer backbone [10] , and designing single ion conducting polymer [11,12] have been reported. Blending suitable additives such as ionic liquid [6] , graphene [13] , ceramic and polymeric nanoparticles [14][15][16][17][18][19] are also useful to increase ionic conductivity of PEG based PEs.…”

“…Designing novel polymers, e.g., synthesis of block copolymers containing both a conductive segment and an insulating rigid segment [5,6] , cross-linking [7][8][9] , grafting PEG chains onto rigid polymer backbone [10] , and designing single ion conducting polymer [11,12] have been reported. Blending suitable additives such as ionic liquid [6] , graphene [13] , ceramic and polymeric nanoparticles [14][15][16][17][18][19] are also useful to increase ionic conductivity of PEG based PEs. Besides PEG based PEs, polycarbonate is another potential candidate [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] , and in comparison the carbonate group possesses high dielectric constant and does not chelate with lithium ion as tightly as the ethylene oxide unit in PEG [25] .…”