ENHANCEMENT OF THE IONIC-CONDUCTIVITY AND THE AMORPHOUS STATE OF SOLID POLYMER ELECTROLYTES FOR RECHARGEABLE LITHIUM BATTERIES

Complexes of LiCF3SO3 and a polymer obtained by polymerization of trie thylene glycol dimethacrylate (TRGDMA) and its copolymerization with a crylonitrile (AN) at molar ratios of 0.67, 2.0 and 4.0, both in the pr esence of poly(ethylene glycol) dimethylether as a plasticizer, provid es a.c. conductivities in the range between 10(-5) and 10(-4) S/cm at ambient temperature. An increase of conductivities has been found at g rowing ratios of AN:TRGDMA from 0 to 2.0 and molar ratios of ethylene oxide (EO) units:LiCF3SO3 ranging from 12 to about 26. The conductivit y is nearly independent of the content of AN at EO:Li+ = 52. Impedance measurements of cells modified with these solid electrolytes show tha t the electrochemical behaviour of the composite lithium/PEO-lithium s alt-complex is determined by the properties of the phase boundary meta l/solid electrolyte. The mechanical stability of the polymer, acting s imultaneously as a separator between the active electrodes, determines the cycle life.