In this focus review, alternating copolymers of carbon dioxide with epoxides have been synthesized and studied as novel ion-conductive polymers. The Li salt electrolytes of poly(ethylene carbonate) (PEC) and of other polycarbonates having different side groups exhibited remarkable ion-conductive properties including the following: increased conductivity with increasingly higher salt concentrations, very high values for the Li+ transference number, and good electrochemical stability. The Li-ion conductivity of a highly concentrated PEC-LiFSI electrolyte was estimated to be greater than 10−4 S cm−1, and excellent battery performance was demonstrated at room temperature.
