Capacitance studies of cobalt oxide films formed via electrochemical precipitation

Cobalt oxide films were prepared by electrochemically precipitating the hydroxide and heating it in air to form Co3O4. The resulting oxide films behave as a capacitor. The materials were studied emphasizing their use as either positive or negative electrodes in devices. The capacitance of the material was estimated at different heating temperatures and insight was gained into the charge storage mechanism. It was seen that the charge storage in cobalt oxide was similar to that of nickel oxide, although their capacitances were different. While, the material was shown to be inferior to nickel hydroxide/oxide when used as a positive electrode, it was seen to be superior as a negative. An asymmetric capacitor with NiO as a positive electrode and CO3O4 as a negative promises adequate capacitance over a large voltage window. (C) 2002 Elsevier Science B.V. All rights reserved.