An Electrochemical Route for Making Porous Nickel Oxide Electrochemical Capacitors

Porous nickel oxide films were prepared by electrochemically precipitating nickel hydroxide and heating the hydroxide in air at 300 C. The resulting nickel oxide films behave as an electrochemical capacitor with a specific capacitance of 59 F/g electrode material. These nickel oxide films maintain high utilization at high rates of discharge (i.e., high power density) and have excellent cycle life. Porous cobalt oxide films were also synthesized. Although the specific capacitances of these films are approximately one-fifth that of the nickel oxide films, the results demonstrate the versatility of fabricating a wide range of porous metal oxide films using this electrochemical route for use in capacitor applications. Electrochemical capacitors have generated wide interest in recent years for use in high power applications (e.g., in a hybrid electric vehicle, where they are expected to work in conjunction with a conventional battery).