IMPROVEMENT OF ACTIVATION BEHAVIOR OF AB(2)-TYPE LAVES PHASE HYDROGENABSORBING ALLOY ELECTRODES BY ADDITION OF LA COMPOUNDS

Influence of several La compounds added to AB2 type of Laves phase hyd rogen absorbing alloy on electrode properties was investigated. The ad dition of La(OH)3 improved charge efficiency in the initial charge-dis charge cycles, bringing about higher discharge capacity, while the add ition of La2O3 and LaF3 showed small effect, It was considered that hy drogen was absorbed preferentially at the interface between the precip itated La compounds and the alloy, Since the La(OH)3 could cover the a lloy surface uniformly, the charge efficiency was fairly improved. How ever, LaF3 could not precipitate into the crack or gap of the alloy, r esulting in smaller effect on the charge efficiency. In the case of La (OH)3, the alloy was self-pulverized even in the first cycle, causing high charge efficiency and high discharge capacity from the earlier cy cles.