Hydrogen storage characteristics of Ti sub(2)Ni alloy synthesized by the electro-deoxidation technique

Ti sub(2)Ni alloy was synthesized in the molten CaCl sub(2) electrolyte by the electro-deoxidation method at 900 [degrees]C and the electrochemical hydrogen storage characteristics of the synthesized alloy was observed. The X-ray diffraction peaks indicated that stoichiometric oxides in TiO sub(2)-ZrO sub(2)-NiO mixture reduced to Ti sub(3)O sub(5), CaTiO sub(3), CaZrO sub(3), Ni and Ti sub(2)O sub(3) within 5 h electro-deoxidation process. Extension of the electro-deoxidation time to 10 h caused formations of TiO and equilibrium Ti sub(2)Ni phase. After 24 h electro-deoxidation the target alloy with the equilibrium Ti sub(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 super(-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 sub(2)Ni alloy was attributed to the developed barrier oxide layer on the electrode surface.