POLY(ETHYLENE OXIDE)/POLY(2-VINYLPYRIDINE)/LITHIUM PERCHLORATE BLENDS AS SOLID POLYMER ELECTROLYTES - COMPOSITION PROPERTY STRUCTURE INTERRELATIONSHIP

Poly(ethylene oxide) (MW 600,000)/poly(2-vinylpyridine) (MW 200,000)/LiClO4 blends have been prepared by the solution blending process. The ionic conductivities of the blends containing lower weight fractions (15, 17.5, 20, and 22.5%) of poly(2-vinylpyridine) initially increases as the salt content is increased, reaches a maximum at an ethylene oxide/Li+ mole ratio of 10 and decreases as the salt content is further increased. Blends, which have higher weight fractions of poly(2-vinylpyridine) (25 and 35%) display different electric behavior, i.e., the ionic conductivity continously increased as the salt content is increased to an ethylene oxide/Li+ mole ratio of 2. Thermal, Li-7 solid-state NMR and semiempirical MNDO molecular orbital studies indicate that this contrasting behavior may be explained by the structure and ratios of the solvates (mixed solvate or homosolvate) of LiClO4 present in the blends. (C) 1995 John Wiley and Sons, Inc.