Santoku Corporation

Akiyasu Ota

Takayuki Otsuki

Yasunori Yanagi

Toshio Irie

Hydrogen storage alloy powder, an anode, and a nickel-hydrogen rechargeable battery are provided, which are excellent in low-temperature characteristics and both in initial activity and cycle life at the same time, which properties are trading-off in conventional nickel-hydrogen rechargeable batteries. The alloy powder has a composition represented by formula (1) RMgNiAlM(R: rare earth elements including Sc and Y, or the like; 0.005&#x2266;a&#x2266;0.40, 3.00&#x2266;b&#x2266;4.50, 0&#x2266;c&#x2266;0.50, 0&#x2266;d&#x2266;1.00, 3.00&#x2266;b+c+d&#x2266;4.50), and has an arithmetical mean roughness (Ra) of the powder particle outer surface of not less than 2 &#x3bc;m, or a crushing strength of not higher than 35,000 gf/mm.

Hydrogen absorption alloy powder, negative electrode, and nickel-hydrogen secondary cell

Provided are hydrogen storage alloy powder capable of providing a nickel-hydrogen rechargeable battery with simultaneous excellence in initial activity, discharge capacity, and cycle characteristics, which are otherwise in a trade-off relationship, an anode for a nickel-hydrogen rechargeable battery as well as a nickel-hydrogen rechargeable battery employing the same. The hydrogen storage alloy has a particular composition represented by formula (1), RMgNiAlM, and has at its outermost surface a Mg-rich/Ni-poor region having a composition with a Mg molar ratio higher than that in formula (1) and a Ni molar ratio lower than that in formula (1), and has inside a Mg/Ni-containing region having a composition with a Mg molar ratio lower than and a Ni molar ratio higher than those in the Mg-rich/Ni-poor region.

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Kobe, Japan

Akiyasu Ota