The application of EQCM to the study of the electrochemical behavior of propylene carbonate solutions

The electrochemical behavior of gold electrodes in propylene carbonate (PC) solutions was investigated using an electrochemical quartz crystal microbalance (EQCM). The solutions studied included uncontaminated LiAsF₆ and LiPF₆ solutions, and CO₂ and H₂O-containing LiAsF₆ solutions. Surface film formation on the electrodes in these solutions was investigated during a potential scan from the open-circuit potential (OCV) to 0.5 V vs. Li Li⁺ and during potential steps from the OCV to various lower potentials. The data obtained from the EQCM experiments were analyzed with the help of the results of previous spectroelectrochemical studies of several surface species formed on noble metal electrodes in these solutions. Analysis of the EQCM data enabled the definition of potential domains in which salt anion, solvent or contaminant reduction are dominant. Using this technique it was also possible to follow the dissolution processes of surface species and hydration of hygroscopic surface film compounds in water-contaminated solutions. The results obtained are in good agreement with previous spectroelectrochemical studies of these systems.