Effect of heat-treatment on electrochemical properties of Ti-Ni-Cr based hydrogen storage alloys for Ni/MH batteries

Effect of heat-treatment on electrochemical properties of Ti-Ni-Cr based hydrogen storage alloys for Ni/MH batteries were investigated. All alloys were prepared by melting the mixture of Ti, Ni, and Cr metals in arc furnace under an argon atmosphere. At first, Ni were partially substituted by Cr to form the Ti2Ni1-xCrx alloy with x = 0, 0.2, 0.4 and 0.6, and then heat-treatment was performed on the prepared Ti-Ni-Cr based alloy electrodes at 800°C for 10 hr in vacuum furnace. The hydrogen absorption-desorption characteristics in gas-solid reactions and the electrochemical properties as metal hydride (MH) electrodes were investigated Changes in the crystal structure and morphology after heat-treatment were identified from X-ray diffraction pattern (XRD). Results indicated that heat-treatment on the Ti-Ni-Cr based alloy electrodes could improve their hysteresis curve, but decrease the energy capacity of the alloy.