Mg2Ni-based hydrogen storage alloys for metal hydride electrodes

Mg2-xMxNi (M=Ti, Ce; X=0, 0.1, 0.2) and MgNi1-yNy (N=Mn, Co; y=0, 0.1, 0.2) were prepared by a powder metallurgical sintering technique. The effects of the element substitutions and the ball-milling of the alloy, with or without nickel powder, on the alloy properties were investigated by X-ray diffraction, transmission electron microscopy and the Malvern particle size analyser. Three types of alloys, un-ball-milled, ball-milled without nickel powders and ball-milled with the addition of nickel powders, were used as the active material of metal hydride electrodes. Electrochemical measurements show that ball-milling the alloy with or without nickel powders is an effective method for increasing the discharge capacity and cycle life of the alloy electrode because of the changed phase structure and surface behaviour. (C) 1999 Elsevier Science S.A. All rights reserved.