The electrochemical discharge of lithium thin films, prepared in ultrahigh vacuum, has been explored in SO2-saturated CH3CN solutions. Prior surface characterization of the products of the reactions between clean lithium and O2, H2O, SO2, and various solvents, using x-ray photoelectron spectroscopy, are reviewed, as they pertain to the kind of surface chemical reactions which occur to the clean lithium surface, after its formation, and prior to its immersion into the electrolyte. The interaction of the clean surface with the backfill gases, and the gases above the solution leads to a predominately sulfite surface layer, overlaying a thin oxide/sulfide product layer. The electrochemical discharge characteristics of this surface, compared with a thin film which had seen 102–104 Langmuirs of O2 exposure, showed that the initial oxide formed in the vacuum chamber had a significant effect on both the steady-state potential achieved by the anode, as well as the time necessary to achieve that steady-state potential. Interestingly, oxide formed from pure O2 exposures had a more passivating effect on the lithium thin film, with respect to electrochemical discharge, than did comparable pre-exposure to H2O. The effect of these oxide layers is also compared with the effect of films formed on the lithium surface as a result of exposure to the electrolyte over a period of a few hours.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry