Photoelectrochemical processes on metal electrodes in nonaqueous solutions of lithium salts

The photoelectrochemical performance of lithium in a propylene carbonate solution of LiClO4 and in a mixture of propylene carbonate with dimethoxyethane, as well as in a LiAlCl4 solution in thionyl chloride, has been investigated. It has been established that when illuminating the electrodes under study, electronic photoemission takes place from the metal into a passivating film permanently existing on the lithium surface. The measurements were in part carried out with the Li electrode coated specially with a Li2O or Li2CO3 protecting film. Photoemission spectroscopy has been used as a tool for exploring the processes of both formation and change in the composition and properties of the passivating layers on the lithium electrodes. The results for the photoelectrochemistry of lithium have been compared with the analogous data obtained with electrodes made of gold and SnCd alloy in a propylene carbonate solution of LiClO4. In the two last cases, electronic photoemission from the metal into solution has been revealed.