IONIC-CONDUCTIVITY AND LI-7 NMR-STUDY OF SOLID POLYMER ELECTROLYTES BASED ON POLYETHERURETHANE COPOLYMER NETWORKS

Crosslinked polyetherurethane (PEU) copolymer networks consisting of t he low molecular weight poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) segments with an aliphatic diisocyanate were synthesized and complexed with a LiClO4 salt to form solid polymer electrolytes. T he ionic conductivities of these samples were measured as a function o f PEO composition at various temperatures. And a solid Li-7 NMR relaxa tion technique was used as a means of understanding the local environm ents and dynamics of the lithium ions in the polymer electrolytes. The difference in spin-spin relaxation times (T2) between two spectral co mponents enabled to their separation, and thus we could monitor the mo bile Li+ ion concentration and its motion as a function of PEO composi tion and temperature.