Designing double comb copolymer as highly lithium ionic conductive solid-state electrolyte membranes

Abstract

We present highly mechanical strength and ionic conductive solid-state electrolyte membranes based on amphiphilic double comb copolymer, i.e., poly(vinylidene chloride)-graft-poly(methyl methacrylate) (PVDC-g-PMMA) synthesized through atomic transfer radical polymerization (ATRP). Well-defined nanophase-separated amphiphilic double comb copolymers are complexed with two types of Li salts (LiTFSI and LiClO4) to form a solid-state electrolyte membrane. Compared to other types, the highest ionic conductivity of the solid-state electrolyte membranes is observed in an amphiphilic double comb copolymer with PVDC-g-PMMA/LiTFSI, due to the synergy of the dissociability of TFSI− and the hopping transport of lithium ions facilitated by PMMA chains. Moreover, the lowest activation energy (0.15 eV) and excellent ionic conductivity (1.3 × 10−3 S cm−1) are also observed in the same solid-state electrolyte membranes at room temperature.