The Use of EQCM for the Study of Nonactive Metal Electrodes in Propylene Carbonate-LiAsF₆ Solutions

The electrochemical behavior of gold electrodes in propylene carbonate (PC)-LiAsF₆ solutions was studied using an electrochemical quartz crystal microbalance (EQCM). When polarized to low potentials, these electrodes develop surface films containing species similar to those formed on lithium in these solutions. Such surface films were precipitated on the electrodes in two different experiments using linear sweep voltammetry and potential steps. EQCM is discussed as a tool for determining the molecular weight of the species precipitated on the electrode surface. In parallel, the same electrodes were explored using impedance spectroscopy. It was found that the frequency changes (Af) due to the mass accumulation on the electrodes during the electrochemical processes could be correlated with the surface film thickness calculated from impedance spectroscopy. Several different surface film formation processes could be identified. The EQCM data could be nicely correlated to previous spectroscopic studies.