Electrochemical characterization of AB2 alloys used for negative electrodes in Ni/MH batteries

The hydrogen storage AB 2 -type and AB 5 -type alloys have been successfully used as components of the negative electrode of Ni/MH batteries, in replacement of the previously employed cadmium electrode. In previous works on AB 2 -type ZrCrNi alloy prepared by arc furnace it was shown that the as-melted material had better electrochemical characteristics as compared to the annealed one. This effect was ascribed to the presence of secondary phases Zr x Ni y formed during solidification of the melt. In this work the electrochemical characteristics of ball milled mixtures of annealed ZrCrNi alloy with powders of the phases Zr 7 Ni 10 , Zr 8 Ni 21 and Zr 9 Ni 11 are studied, resulting that the main secondary phase responsible for the properties improvement is the Zr 8 Ni 21 alloy. The electrochemical characteristics of the individual secondary phases Z 7 Ni 10 , Zr 8 Ni 21 and Zr 9 Ni 11 are also investigated.