摘要 |
A hydrogen storage alloy electrode containing, as a principal active material, a powder of hydrogen storage alloy having a CaCu5 crystal structure and represented by the formula MmNixCoyMnzMw where M is at least one element selected from aluminum (Al) and copper (Cu), x is between 3.0 and 5.2, y is between 0 and 1.2, z is between 0.1 and 0.9, w is between 0.1 and 0.9, and the sum of x, y, z and w is between 4.4 and 5.4. The hydrogen storage alloy powder particles have a surface region and a bulk region enclosed within the surface region and have a higher nickel content in the surface region than in the bulk region. The hydrogen storage alloy electrode further contains an oxide and/or hydroxide of at least one rare-earth element selected from ytterbium (Yb), samarium (Sm), erbium (Er) and gadolinium (Gd).
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