Effect of Ni containing surface phases on the electrode characteristics of Ti1.0Mn1.0V0.5

Abstract

The Ti1.0Mn1.0V0.5 alloy is hardly electrochemically hydrogenated in the KOH solution due to the poor charge transfer characteristics. The Ti1.0Mn1.0V0.5 alloy was sintered with nickel powder in vacuum at 900 degrees C for 10 min for the surface modification by which the alloy could be electrochemically hydrogenated successfully. It was found that TiNi phase was formed during sintering from the X-ray and SEM (EDS) analysis. Because the reversible hydrogen storage capacity of TiNi is so small, the theoretical capacity of the electrode decreases with the formation of TiNi phase. By comparing the exchange current densities of the electrodes which were sintered with different ratios of nickel and TiNi powders, it was found that the electrochemical catalytic effect of TiNi was greater than that of nickel. By sintering the electrode with LaNi4.7Al0.3 alloy powder which can absorb hydrogen, more discharge capacity was obtained. This surface modification process will give more flexibility in the alloy design of the anode material for Ni-MH battery by utilizing electrochemically inactive hydrides. (C) 1997 Elsevier Science S.A.