Abstract
The subject of this study is for AB2 C14 Laves CrFeMnTiVZr alloy. By modulating the individual elements, tens of alloys with both non-equal and equal molar contents, including a 7-element CoCrFeMnTiVZr alloy, were designed. The aim of this study is to investigate the individual effect of each composed element on the discharge capacity and cycle life of nickel-metal hydride cell. Bulk alloys were arc-melted in a water-cooled Cu-mold in vacuum, crushed, 325-mesh screened, activated to eliminate the poisoned surface of the alloy particles, slurry blending with PTFE, and then compressed into a negative electrode. A counterpart, nickel oxyhydroxide positive electrode, was also made. Nickel-metal hydride cells were home-made with a negative electrode and a nickel oxyhydroxide positive electrode by use of 30 wt% KOH solution as electrolyte. An automatic charge-discharge system was used to record voltage, current, and time by setting the charge-discharge condition, and to calculate the discharge capacity and cycle life of the cells. The alloy composition influences many important characteristics of cells such as the charge-discharge ability, thermodynamic properties, oxidation and corrosion resistance, micronization of particles, discharge kinetics, catalytic properties, the ability of hydrogen recombination, and cycle life. Preliminary results show that the best cell discharge is the Fe1.5 (CrFe1.5MnTiVZr) alloy, and its maximum discharge capacity reaches 143.34 mAh/g. Cell with best cycle life in this experiment is that of Mn0 (CrFeTiVZr) alloy with the 30-cycle discharge capacity remaining 50% of its maximum capacity. The cell made of 7-element CoCrFeMnTiVZr alloy has higher discharge ability than those of the 6-element equal and non-equal molar alloys have.