Chemical and Electrochemical Characterization of Polymer Gel Electrolytes Based on a Poly(alkylene oxide) Macromonomer for Application to Lithium Batteries

Abstract

Polymer gel electrolytes were prepared from a molecularly designed poly(alkylene oxide) triacrylate macromonomer and different liquid electrolytes. The cross-linking kinetics of the macromonomer in a liquid electrolyte was studied by using differential scanning calorimetry equipped with ultraviolet light irradiation system (UV-DSC). It was revealed that the photoinitiated cross-linking reaction followed the first order kinetics in terms of macromonomer concentration. The cross-linking reaction finished completely under suitable conditions of ultraviolet (UV) light strength and photoinitiator concentrations. The gel electrolytes prepared exhibited a high ionic conductivity of 3 mS/cm at room temperature and kept 1 mS/cm even at -20 °C, when 1 M LiBF 4 /γ-butyrolactone liquid electrolyte was incorporated in the gel. A linear relationship between the ionic conductivity of liquid electrolytes and that of the gel electrolytes containing the corresponding liquid electrolytes was observed, except for the case where LiPF 6 was used as an electrolyte salt. The interfacial resistances at the lithium/gel electrolyte interfaces were largely dependent on the kind of liquid electrolytes incorporated in the gels. Preliminary results of the application of the gel electrolytes to lithium and lithium-ion batteries implied high utilization of cathode material and cycleability.