Hydrogen absorption characteristics and electrochemical properties of Ti substituted Zr-based AB(2) alloys

The hydrogen absorption characteristics of Zr1-xTixCrNi alloys, with x rang ing between 0.1 and 0.4, were studied by volumetric and electrochemical tec hniques in order to determine their possible application as the negative el ectrode in nickel/metal-hydride rechargeable batteries. Electrodes of alloy powders mixed with different compacting additives were tested with respect to charge and discharge cycles in KOH solution. The effects of the electro de-compacting additive, discharge rate and temperature on the electrode dis charge capacity were also investigated. The results obtained show that: (i) at 80 degreesC the equilibrium pressures of Zr1-xTixCrNi alloys with x = 0 .1 are 2.6 times higher than those for the unsubstituted ZrCrNi alloy, whil e maintaining a good hydrogen storage capacity; (ii) the Zr0.9Ti0.1CrNi all oy electrodes exhibit the highest discharge capacities and the best perform ances during fast charge-discharge cycling; (iii) the Ti substituted alloy electrodes using copper powder as compacting material show faster activatio n, while carbon-Teflon compacted electrodes exhibit the best cycle life beh avior; (iv) for all Ti substituted alloy electrodes the discharge capacitie s increase with temperature. (C) 2001 International Association for Hydroge n Energy. Published by Elsevier Science Ltd. All rights reserved.