STUDIES ON ELECTROLESS COBALT COATINGS FOR MICROENCAPSULATION OF HYDROGEN STORAGE ALLOYS

LaNi4.27Sn0.24 alloy was mieroencapsulated with cobalt by electroless deposition from an alkaline hypophosphite bath. Discharge curves of th e encapsulated alloy indicate an additional contribution to the capaci ty arising from the cobalt on the surface. Studies on cobalt thin film s reveal the presence of adsorbed hydrogen in cobalt. The amount of hy drogen adsorbed was observed to increase with time of cathodic polariz ation and to reach a maximum. Polarization techniques have been used t o characterize the cobalt-plated alloy as a function of state of charg e. The equilibrium potential of the microencapsulated electrode at low hydrogen concentration is determined by the potential of the cobalt c oating on the surface.