The effect of temperature on the electrode properties of the directly prepared Ti3Ni2 alloy

The electrochemical properties of a new hydrogen storage alloy Ti3Ni2 have been studied in detail. The results show that the discharge capacity of Ti3Ni2 alloy reaches 384.4 mA h/g (corresponding to Ti3Ni2H3.7) at 353 K and 145.5 mA h/g (corresponding to Ti3Ni2H1.47) at 278 K. At the higher temperature (353 K), two plateaus appear on the discharge curve, and at the lower temperature (278 K) only one plateau. The kinetic property of Ti3Ni2 alloy electrode is poor. The following properties, namely the retention of charge, the activation of alloy, the kinetic property of Ti3Ni2 alloy (including the exchange current, the diffusion coefficient of hydrogen and high-rate dischargeability) can all be improved by increasing the temperature. It can be seen from X-ray diffraction analysis that two phases exist in alloy: namely the cubic Ti2NiH phase with Fe3W3C structure and the cubic TiNiH phase for the alloy cycled in alkaline solution, and the cubic Ti2NiH0.5 phase with Fe3W3C structure and the cubic TiNiH phase for the alloy hydrogenated with gaseous hydrogen.