Development of hydrogen-absorbing alloys for nickel-metal hydride secondary batteries

Abstract The effect of the stoichiometry of Mm(Ni 0.64 Co 0.2 Mn 0.12 Al 0.04 ) x alloy on the hydrogen absorption capacity, and the reactivity of two-phase alloys in alkaline solution, were investigated. Furthermore, the electrochemical characteristics of non-stoichiometric hydrogen-absorbing alloys with a second phase were investigated. Nonstoichiometric hydrogen-absorbing alloys ( x =4.5–4.8) with boron added were found to have higher electrochemical capacities and superior electrochemical reactivities than those of stoichiometric alloys without boron added.