Novel polymeric ionic liquid membranes as solid polymer electrolytes with high ionic conductivity at moderate temperature

Abstract

A series of guanidinium polymeric ionic liquid (PIL) electrolyte membranes combining different anions, such as BF 4 −, PF 6 −, ClO 4 − and N(CF 3SO 2) 2 −, were synthesized through copolymerization and anion exchange reaction as new promising solid polymer electrolytes. The chemical structures of the PILs were characterized by 1H NMR and ATR–FT IR spectra, and their thermal properties, ionic conductivity and electrochemical stability were evaluated, respectively. The PILs present different decomposition temperature and glass transition temperature ( T g), and their thermal properties strongly depend on the sort of anions. The 1g2-MA-BF 4 possesses the better thermal stability and it decomposes at 353 °C. The 1g2-MA-TFSI shows the lower T g and it is below −60 °C. The ionic conductivity of the PIL electrolytes depends on the lithium salts used and its content. The best ionic conductivity of the PILs electrolyte 1g2-MA-BF 4/LiBF 4 (30 wt%) was 1.35 × 10 −4 S cm −1 at 30 °C.