Alkali-treatment at high temperature of the hydrogen storage alloy which wa
s used as the negative electrode of nickel/metal-hydride batteries could en
hance the cycle life. Al dissolves from the alloy surface, rare earth metal
hydroxides form on the alloy surface, while Ni and Co exist as metals near
the surface. Mn dissolves first and then deposits again as an oxide on the
alloy surface. The corrosion reaction caused by alkali-treatment of the al
loy stops at a certain stage. The above three points can be considered as t
he main factors for the long cycle life for the alkali-treated alloys. (C)
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