SURFACE OF LITHIUM ELECTRODES PREPARED IN AR+CO2 GAS

The surfaces of lithium electrodes prepared in Ar(80%) +CO2(20%) mixed gas and pure Ar gas have been investigated by X-ray photoelectronspec troscopy (XPS) and a polarization microscope. Electrodes prepared by c utting lithium in the mixed gas do not show a voltage delay at the beg inning of discharge in 1 M LiClO4/propylene carbonate. All parts of th e lithium surface prepared in the mixed gas have clear grain boundarie s after dissolution during discharge. By contrast, anodic dissolution of the lithium surface prepared in pure Ar gas occurs partially and mo st of the surface is passivated. XPS studies suggest that the growth o f a dense Li2CO2 layer on the outer surface of the lithium with storag e time is responsible for the voltage delay.