EFFECTS OF TiO2 ADDITIVE ON ELECTROCHEMICAL HYDROGEN STORAGE PROPERTIES OF NANOCRYSTALLINE /AMORPHOUS Mg2Ni INTERMETALLIC ALLOY

Mg2Ni alloy and Mg2Ni–x wt% TiO2 (x = 3, 5 and 10 wt %) composites are prepared by mechanical alloying. The produced alloy and composites are characterized as the particles with nanocrystalline/amorphous structure. The effects of TiO2 on hydrogen storage properties are investigated using anodic polarization and electrochemical impedance spectroscopy. It is demonstrated that the initial discharge capacity and exchange current density of hydrogen are increased by adding 5wt% TiO2, while the cycle stability and bulk hydrogen diffusivity don’t change. It is found that the charge transfer resistance of Mg2Ni–5wt% TiO2 composite is lower than that of Mg2Ni alloy. On the other hand, the hydrogen oxidation during the discharge process proceeds more easily on the electrode surface containing TiO2 additive.