HIGH IONIC-CONDUCTIVITY OF NEW POLYMER ELECTROLYTES BASED ON HIGH-MOLECULAR-WEIGHT POLYETHER COMB POLYMERS

High molecular weight polyether comb polymers, poly[ethylene oxide-co- 2-(2-methoxyethoxy)ethyl glycidyl ether] P(EO/MEEGE), have been used a s matrixes of polymer electrolytes. The high molecular weight (>10(6)) polymers give self-standing and elastic polymer electrolyte films wit hout chemically cross-linked structures at room temperature, when comp lexed with electrolyte salts. With increasing the composition of MEEGE in the copolymers, the degree of crystallinity of the polymer electro lytes decreases, and the ionic conductivity appreciably increases. The increase in the conductivity cannot be explained only by the crystall inity decrease, the increase in the number of highly mobile ether side chains with the increase in MEEGE composition contributes to achievin g the high conductivity. The fast ion transport would be realized in c ooperation with the fast side chain motion. The polymer electrolytes c omplexed with lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) exhib it higher conductivity than those complexed with a conventional salt, lithium perchlorate. The polymer electrolytes, P(EO/MEEGE) containing 9 mol% of MEEGE complexed with LiTFSI, exhibit high ionic conductiviti es of 10(-4) S cm(-1) at 30 degrees C and 10(-3) S cm(-1) at 80 degree s C. An electrochemically stable potential window, established by soli d state cyclic voltammetry using microelectrodes, is at least 4V from the Li/Li+ potential. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.