Ab5-type hydrogen storage alloys are the most promising materials used as the anode in commercial Ni-MH secondary battery. It is very important for electrode materials to have a wider operation temperature range. The component Al is the dominant element to control the electrochemical behavior of the AB5-type alloys at elevated temperature. With the increase of the amount of Al the discharge capacity decreases and the retention of discharge capacity increases with increasing temperature. It is mainly due to the formation of stable and dense surface oxide film Al2Oa, which inhibits the electrode corrosion and the further oxidation underneath the surface films.
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