SURFACE-ANALYSIS OF FRESHLY CUT LI SAMPLES - NA-SEGREGATION AND FILM FORMING REACTION BY O2, SO2, AND LIQUID LIALCL4.3(SO2)

Freshly cut lithium metal of battery quality, which was perfectly clean due to the Auger analysis, contained about 30% sodium on its surface. This was proved both with XPS and AES thereby varying the angle of observation. With respect to these results, gas adsorption experiments were done with O2 and SO2 both on Li and on Na metal. Detailed reaction mechanisms for the respective layer formation on Li and Na are established. Further experiments were done with Li electrodes in liquid LiAlCl4.3(SO2) electrolyte. These spectra are compared with those of charged and discharged Li electrodes. Thus, information was gathered on the nature of the passive layer on Li in SO2 electrolytes. It transpired that Na is only accumulated at the surface of metallic Li, but is not directly involved in the passive layer formation.