EFFECTS OF TiO۲ ADDITIVE ON ELECTROCHEMICAL HYDROGEN STORAGE PROPERTIES OF NANOCRYSTALLINE /AMORPHOUS Mg۲Ni INTERMETALLIC ALLOY

Abstract: Mg۲Ni alloy and Mg۲Ni–x wt% TiO۲ (x = ۳, ۵ and ۱۰ wt %) composites are prepared by mechanical alloying. The produced alloy and composites are characterized as the particles with nanocrystalline/amorphous structure. The effects of TiO۲ 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 ۵wt% TiO۲, while the cycle stability and bulk hydrogen diffusivity don’t change. It is found that the charge transfer resistance of Mg۲Ni–۵wt% TiO۲ composite is lower than that of Mg۲Ni alloy. On the other hand, the hydrogen oxidation during the discharge process proceeds more easily on the electrode surface containing TiO۲ additive.