HYDROGEN ABSORPTION AND ELECTRODE CHARACTERISTICS OF (TI,ZR)-(NI,V,X)2+ALPHA ALLOYS

Microstructures, hydrogen absorption behavior and metal hydride electrode characteristics of (Ti0.5Zr0.5)(Ni1.3V0.7X0.2) [X = Al, Fe, Cr, Mn] alloys were studied. These multi-component alloys have the C14 Laves phase structure. Their P-C isotherms of hydrogen absorption are sloped. These alloy electrodes had the capacities of 200 to 300 mAh . g-1 at the current density of 56 mA . g-1. Among the four additive elements, manganese gave the largest discharge capacity electrode but it deteriorated quickly. On the other hand, chromium gave a long life electrode with a fairly large capacity. The outstanding feature of the chromium-containing alloy was its characteristic second phase precipitates growing throughout the alloy bulk, however, precipitates dissolved into the KOH electrolyte during charge-discharge cycles.