Preparation of a High Surface Area Nickel Electrode by Alloying and Dealloying in a ZnCl[sub 2]-NaCl Melt

An electrochemical method of preparing a high surface area nickel electrode by NiZn alloy formation and subsequent dealloying in (60-40 mol %) at 450°C was studied. A nickel electrode was kept at 0.22 V vs. Zn in where γ-NiZn alloy was formed, and then at 0.5 V where partial dealloying occurred to yield α-NiZn alloy. Scanning electron microscope observation showed that the microporous structure was formed on the surface. The roughness factor of a sample was determined to be 240 from the double layer capacitance obtained in the ac impedance measurement. Thickness, porosity, and pore size of the surface layer were estimated.