Electrochemical Characteristics of Cobalt Oxide Electrode for Supercapacitor

Abstract

Fine cobalt oxide xerogel powder was prepared by a unique solution chemistry associated with a sol-gel process. Investigation of effect of thermal treatment on the crystalinity, particle structure, and corresponding electrochemical properties of the resulting xerogel revealed that amorphous structure of Co(OH)₂ remained up to 160°C. With an increase in the temperature above 200°C, both the surface area and pore volume decreased sharply, because the amorphous Co(OH)₂ was converted to form CoO and was subsequently oxidized to crystalline Co₃O₄. In addition, the changes in the crystallinity, and particle structure were accompanied to the chemical reaction. All things were found to influence the electrochemical properties of the resulting xerogels. A maximum capacitance of 192 F/g was obtained for the CoO_x Xerogel calcined at 150°C, which possessed highest values in both surface area and pore volume. To increase capacitance, we added PVA as a dispenser. It is better in terms of capacitance, and then it was carried out capacitance changes of CoO_x to acquire stability in cycle tester during 1000 cycle, it shows 450 F/g in average.