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

• Ti2Ni alloy was synthesized by the electro-deoxidation method at 900 °C.
• Ti3O5, CaTiO3, CaZrO3, Ni and Ti2O3 were reduction products after 5 h deoxidation.
• Ti2Ni phase formed after 10 h deoxidation and Zr dissolved in this phase.
• The maximum discharge capacity of the synthesized alloy was 200 mA h g−1.

Ti2Ni alloy was synthesized in the molten CaCl2 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 TiO2–ZrO2–NiO mixture reduced to Ti3O5, CaTiO3, CaZrO3, Ni and Ti2O3 within 5 h electro-deoxidation process. Extension of the electro-deoxidation time to 10 h caused formations of TiO and equilibrium Ti2Ni phase. After 24 h electro-deoxidation the target alloy with the equilibrium Ti2Ni 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 Ti2Ni alloy was attributed to the developed barrier oxide layer on the electrode surface.