Electrochemical study of Co(II)/Co(III) on different electrode materials for energy storage in redox flow cells

摘要

The development of redox flow cells has been carried out through the use of several redox couples which oxidize and reduce to store electrical energy. Some problems encountered in redox cells include: low solubility of redox couples, slow kinetics, low stability of electrode materials and high toxicity of electroactive species. In this paper, Co(III)/Co(II) has been investigated as a possible electroactive material because of its high oxidizing power and the relatively low toxicity of Co(III). The electrochemical study of Co(III)/Co(II) was carried out on different electrode materials such as glassy carbon, Au, Pt, Pb and stainless steel. Results show that the high oxidizing power of Co(III) does not enable to observe its reduction reaction in the aforementioned electrode materials possibly due to electrode surface corrosion and/or water oxidation. However, the electrolysis of Co(III) with a Pb electrode shows that the system is reversible and forms PbO_2 on the electrode surface.