FTIR CHARACTERIZATION OF PEO+LIN(CF3SO2)(2) ELECTROLYTES

FTIR transmission spectra of thin films of polyethylene oxide (PEO) lithium trifluoromethanesulfonimide (LiN(CF3SO2)(2), LiTFSI) mixtures have been obtained for ethylene oxide/Li ratios from 64: 1 to 2: 1. Th e phase information from these spectra is compared with the reported p hase diagrams based on thermal measurements. The infrared spectrum of LiTFSI is assigned by analogy with those of related compounds. Using t he spectral subtraction technique, the effects of Li+ solvation on the PEO matrix and of ion pairing and aggregate formation on the TFSI ani on are revealed. An explanation is offered for the variation in ionic conductivity for compositions within the ''crystallinity gap''.