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AssigneeMitsui Mining & Smelting Cp., Ltd.
InventorsDaisuke Mukai, Shigeki Nakayama, Kiyotaka Yasuda, Shinya Kagei, Hidetoshi Inoue
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A hydrogen storage alloy is provided which has an extremely low Co content, and can maintain the drain (power) performance (especially pulse discharge characteristics), activity (degree of activity), and life performance at high levels. The hydrogen storage alloy is manufactured by weighing and mixing every material for the hydrogen storage alloy so as to provide an alloy composition represented by the general formula MmNiaMnbAlcCod or MmNiaMnbAlcCodFee, and controlling the manufacturing method and manufacturing conditions so that both the a-axis length and the c-axis length of the crystal lattice are in a predetermined range. Although it is sufficient if the a-axis length of the crystal lattice is 499 pm or more and the c-axis length is 405 pm or more, by further specifying the a-axis length and c-axis length depending on the values of ABx, a hydrogen storage alloy having high durability can be provided.
A low Co hydrogen storage alloy having a CaCu5-type crystal structure that can be represented by the general formula MmNiaMnbAlcCod, wherein Mm is a Misch metal, 4.0≦a≦4.7, 0.3≦b≦0.65, 0.2≦c≦0.5, 0<d≦0.35, 5.2≦a+b+c+d≦5.5, wherein the a-axis length of the crystal lattice of said CaCu5-type crystal structure is 499 pm or more, and the c-axis length is 405 pm or more.
A low Co hydrogen storage alloy having a CaCu5-type crystal structure that can be represented by the general formula MmNiaMnbAlcCodFee, wherein Mm is a Misch metal, 4.0≦a≦4.7, 0.3≦b≦0.65, 0.2≦c≦0.5, 0<d≦0.35, 0<e≦0.11, 5.2≦a+b+c+d+e≦5.5, wherein the a-axis length of the crystal lattice of said CaCu5-type crystal structure is 499 pm or more, and the c-axis length is 405 pm or more.
Dependencies are inferred from the claim text.