Abstract: A new method of surface modification on hydrogen storage alloy is investigated. The AB₅ alloy of metal hydride electrode in MH/Ni battery is treated in the mixed solution of HF and CuSO₄. The effects of HF content and copper particle deposition amount on surface modification reaction are studied. The performances of modified alloy are tested and electrochemical impedance spectroscopy (EIS) is applied to analyze the mechanism of treatment. The electrochemical testing results indicate that modified alloy has better rate capability and cycle stability. And the EIS analysis shows that surface modification increases the activity and electrical conductivity of the alloy, and greatly decreases its ohmic and electrochemical impedance, which helps to improve electrochemical properties of the battery. Therefore the modified alloy would well meet the requirement of power sources on electric vehicles.

Key words: Hydrogen storage alloy, Surface modification, EIS, Electric vehicle