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 photoelectronspectroscopy (XPS) and a polarization microscope. Electrodes prepared by cutting lithium in the mixed gas do not show a voltage delay at the beginning of discharge in 1 M LiClO4/propylene carbonate. All parts of the lithium surface prepared in the mixed gas have clear grain boundaries after dissolution during discharge. By contrast, anodic dissolution of the lithium surface prepared in pure Ar gas occurs partially and most of the surface is passivated. XPS studies suggest that the growth of a dense Li2CO2 layer on the outer surface of the lithium with storage time is responsible for the voltage delay.