Identification of Surface Films Formed on Lithium in Dimethoxyethane and Tetrahydrofuran Solutions

Surface films formed on lithium metal in dimethoxyethane (DME) and tetrahydrofuran (THF) solutions of , , and were analyzed using FTIR, SIMS, and XPS spectroscopies. The films formed in both solvents were found to contain lithium alkoxides. The main reaction products detected with FTIR were in DME, and in THF. SIMS measurements are consistent with this finding. Reaction mechanisms are discussed. When the water concentration in these systems is 0.01 M or greater, is formed on the lithium surface and appears to be a major component in the surface films. XPS measurements gave evidence for simultaneous salt reduction on the lithium surface in addition to the solvent reactions.