PROPERTIES OF ZR(V0.25NI0.75)(2) METAL HYDRIDE AS ACTIVE ELECTRODE MATERIAL

We have investigated the Zr(VxNi1-x)(2) alloy series in the range of 0 less than or equal to x less than or equal to 0.4 and observed very p ronounced absorption and desorption properties in Zr(V0.25Ni0.75)(2). We have shown previously that Zr(V0.25Ni0.75), has a high reversible c apacity of 364 mA h g(-1) (C/30 rate) and a good electrochemical cycle stability (8%/100 cycles capacity loss, C/3 rate), However, large-sca le production of this alloy seems to be difficult, and annealing deter iorates the high capacity and the good kinetics as well. In this study we have analyzed the microstructure of the alloy and the thermodynami cs of hydride formation of the alloy electrodes. Two different phases were observed, Zr7Ni10 and Zr(V(0.33)Ni0.67)(2.3); however, both of th em are, as single phase alloys, not quite as good as their combination in Zr(V0.25Ni0.75)(2).