XPS ANALYSIS FOR THE LITHIUM SURFACE IMMERSED IN TETRAHYDROFURAN CONTAINING VARIOUS SALTS

The lithium surface immersed in tetrahydrofuran (THF) containing various salts was analyzed by X-ray Photoelectron Spectroscopy. The lithium surface was covered with the native film which consists of Li2CO3, Li2O, and LiOH. During the immersion of lithium in the LiBF4 or LIClO(4)/THF electrolytes, the chemical compositions of the native film changed to LiF (or LiCl) and organic compounds. The formation of these compounds depends on the kind of salt. The properties of the surface film on lithium was changed by the formation of LiF (or LiCl). When most of lithium compounds consisting the native film are converted to LiF (or LiCl), the electrolyte permeate easily and touch to the lithium metal directly. Finally, organic compounds were formed in the surface film as a result of the direct reaction with the lithium metal.