Ion-conductive properties of propylene carbonate/propylene oxide copolymers

Abstract

Solid polymer electrolytes (SPEs) have been expected as solid-state electrolytes in electrochemical applications. However, ionic conductivity of SPEs are lower than that of common liquid and gel electrolytes. In this study, random and block copolymers were synthesized from CO2 and propylene oxide, and the ion conductive properties of block copolymers that consist of a polypropylene oxide central block connected to poly(propylene carbonate)(PPC) segments at both ends were investigated. We used three types of random copolymers containing different amount of ether units and one block copolymer. SPE samples were prepared by adding 20-100 mol% LiTFSI to the polymers. All copolymers showed a lower glass transition temperature and higher ion conductivity than those of PPC electrolytes. On the other hand, the random copolymers showed a lower ion conductivity than that of the block copolymer.