Hydrogen storage characteristics of Ti2Ni alloy synthesized by the electro-deoxidation technique

Abstract Ti 2 Ni alloy was synthesized in the molten CaCl 2 electrolyte by the electro-deoxidation method at 900 °C and the electrochemical hydrogen storage characteristics of the synthesized alloy was observed. The X-ray diffraction peaks indicated that stoichiometric oxides in TiO 2 –ZrO 2 –NiO mixture reduced to Ti 3 O 5 , CaTiO 3 , CaZrO 3 , Ni and Ti 2 O 3 within 5 h electro-deoxidation process. Extension of the electro-deoxidation time to 10 h caused formations of TiO and equilibrium Ti 2 Ni phase. After 24 h electro-deoxidation the target alloy with the equilibrium Ti 2 Ni phase structure and the maximum amount of the dissolved Zr in it was obtained. It was observed that the synthesized alloy had maximum discharge capacity of 200 mA h g −1 . Upon increase in the charge/discharge cycles, however, the discharge capacity decayed sharply. According to the gathered EIS data at various DODs, the rapid degradation in the electrode performance of Ti 2 Ni alloy was attributed to the developed barrier oxide layer on the electrode surface.