Effect of Anions on Lithium Ion Conduction in Poly(ethylene carbonate)-based Polymer Electrolytes

Poly(ethylene carbonate)-based polymer electrolytes with lithium salts (LiX; X = TFSI, ClO 4 , BF 4 and PF 6 ) were prepared, and their lithium transference numbers ( t + ) were measured to make comparison between different anion radius and salt concentrations. The LiTFSI electrolytes had the highest t + and Li-ion conductivities of all samples at 80°C; these values increased with increasing salt concentration. According to the results of FT-IR measurements for all concentrated samples, the changes of band fraction, which divide at around 1720 cm −1 for carbonyl groups interact, with Li + (C=O — Li + ), are strongly related to the mobility of Li + ions.