Effect of Ti substitution on electrochemical properties of ZrNi alloy electrode for use in nickel-metal hydride batteries

Crystal structure and electrochemical properties of the Zri-xTixNi (0.05 <= x <= 0.5) alloys were investigated. X-ray diffraction spectra showed that the primary phase of all Zri-xTixNi alloys had the B33-type orthorhombic crystal structure, which was characteristic of ZrNi, and the unit cell volume of the primary phase linearly decreased with an increase in the x value. In the charge discharge tests with the Zr1-xTixNi alloy negative electrodes, the initial discharge curves for the alloys with x'>= 0.3 had two plateaus. Both plateau potentials negatively shifted with an increase in the x value. The initial discharge capacity for the Zr1-xTixNi alloy negative electrode was 349 mAh g(-1) at 25 mA g(-1) and 333 K, which was the highest in this study. The high-rate dischargeability and cycle performance were also improved by the partial replacement of Zr by Ti. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.