Effect of surface modification by heating in argon on charge/discharge characteristics of Mg2Ni electrode

Charge/discharge characteristics of Mg,Ni electrodes were examined by focus sing attention on the influence of surface modification by heating in argon . The initial activation was significantly easier for the electrodes heated at 550 degrees C than un-heated ones. The surfaces of electrodes became po rous by the heating because of the evaporation of magnesium. A MgO layer wa s formed during the heating. The improvement of charge/discharge characteri stics by the heating was ascribed to the increase in the specific surface a rea and the porosity of the oxide film, and to the formation of MgNi2 and n ickel phases which should act as the local reaction sites for hydrogen duri ng the charge and discharge processes.