MAGNETIC-RESONANCE STUDY OF WATER-ABSORPTION IN SOME PEG-LITHIUM SALTPOLYMER ELECTROLYTES

The effects of water absorption in complexes of poly(ethylene oxide) w ith lithium salts (LiClO4, LiBF4 and LiAsF6) have been studied by DSC and nuclear magnetic and electron spin resonance techniques. Measureme nts of the temperature dependence of Li-7 and H-1 relaxation times (T- 1 and T-2) allow us to examine the greater motional freedom acquired b y the Li+ ion and the chains in the hydrated complexes. Additional evi dence for the increase of the lithium mobility is provided by the cons iderable reduction in the Li-7 NMR linewidth. Increase in hydration al so increase the mobility of the free chains and may allow a volume exp ansion of the mobile segments, thus reducing the H-1 second moment. Th e ESR study performed on a copper salt-PEO complex reasserts that wate r competes favorably with the ethylene oxide unit for complexation wit h the positive ion.