Electrochemical Properties of Organic Disulfide/Thiolate Redox Couples

The redox behavior, kinetic reversibility, chemical reversibility and stability, and the specific adsorption or chemisorption at electrode surfaces of a diverse group of organodisulfide cathode materials have been studied by potential‐sweep and potential‐step methods. The number of electrons involved in the redox reaction and the diffusion coefficients of the organodisulfide species in electrolyte solutions were determined with a rotating disk electrode in conjunction with chronocoulometry/chronoamperometry. Observations indicated that the overall, stoichiometric reaction of these redox couples is where represents an organic moiety. These reactions are chemically reversible, yet kinetically hindered, especially at ambient temperatures. The microscopic reversibility of the redox couples promises the possibility of constructing secondary energy conversion systems based on these materials. The slow electrode kinetics, however, indicates that the introduction of electrocatalysts to assist the electrode reaction may be effective in improving battery performance. The negligible adsorption of these materials at platinum electrodes, in addition, implies that the electrode kinetics can be formulated by simple electrodic equations without consideration of surface coverage.