Chemical and electrochemical characterization of polymer gel electrolytes based on a poly(alkylene oxide) macromonomer for application to lithium batteries

Polymer gel electrolytes were prepared from a molecularly designed poly(alk ylene oxide) triacrylate macromonomer and different liquid electrolytes. Th e cross-linking kinetics of the macromonomer in a liquid electrolyte was st udied 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 macrom onomer concentration. The cross-linking reaction Finished completely under suitable conditions of ultraviolet (UV) light strength and photoinitiator c oncentrations. The gel electrolytes prepared exhibited a high ionic conduct ivity of 3 mS/cm at room temperature and kept 1 mS/cm even at -20 degrees C , when 1 M LiBF4/gamma-buty-rolactone liquid electrolyte was incorporated i n the gel. A linear relationship between the ionic conductivity of liquid e lectrolytes and that of the gel electrolytes containing the corresponding l iquid electrolytes was observed, except for the case where LiPF6 was used a s an electrolyte salt. The interfacial resistances at the lithium/gel elect rolyte interfaces were largely dependent on the kind of liquid electrolytes incorporated in the gels. Preliminary results of the application of the ge l electrolytes to lithium and lithium-ion batteries implied high utilizatio n of cathode material and cycleability. (C) 2000 The Electrochemical Societ y. S0013-4651 (99)09-069-2. All rights reserved.