HYDROGEN DESORPTION PROPERTIES AND ELECTRODE PERFORMANCES OF TI-ZR-NI-V-MN ALLOY

The measurements of the desorption pressure-composition-temperature (P -C-T) of the TixZr1-xNiyV2-y (0 less than or equal to x less than or e qual to 1, 0 less than or equal to y less than or equal to 2) alloy ha ve been investigated by means of a 3(2)-factorial design method. The r esponse surface function of hydrogen desorption between 0.01 and 10 at m was calculated by Yates' algorithm. Alloy with x = 0.35, y = 0.60 (i .e., Ti0.35Zr0.65Ni0.6V1.4) was found to possess maximum hydrogen deso rption capacity. When examined by EDAX and SEM, this alloy shows three distinguishable phases and exhibits C14 structure, The effect of subs titution of Mn and Ni for V was also studied, Alley such as Ti0.35Zr0. 65Ni1.2V0.4Mn0.4 has nearly a pure C14 structure with 89% hydrogen des orption ability. This alloy has 255 mAh/g, 231 mAh/g, and 210 mAh/g ca pacities at 25 mA/g, 50 mA/g, and 100 mA/g discharge rates, respective ly. This indicates that the substitution of Mn and Ni for V not only c an improve its hydrogen desorption ability, but also make the alloy st ructure more uniform and more suitable to be an electrode material.