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 ZrxNiy 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 Zr7Ni10, Zr8Ni21 and Zr9Ni11 are studied, resulting that the main secondary phase responsible for the properties improvement is the Zr8Ni21 alloy. The electrochemical characteristics of the individual secondary phases Z(7)Ni(10), Zr8Ni21 and Zr9Ni11 are also investigated. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.