HYDROGEN ABSORBING ALLOY, NEGATIVE POLE, AND NICKEL-HYDROGEN SECONDARY BATTERY

Provided are a hydrogen storage alloy wherein elution of Co, Mn, Al, and the like elements into an alkaline electrolyte is inhibited, which has excellent corrosion resistance, and which is industrially of low cost due to a reduced Co content, an anode for a nickel-hydrogen rechargeable battery employing the alloy, and a nickel-hydrogen rechargeable battery having the anode. The hydrogen storage alloy has a CaCu crystal phase as the main phase, has a composition represented by the formula RNiCoAlMnSnM, wherein R stands for at least one element selected from lanthanoid elements including Y, and essentially includes La; M stands for at least one element such as Ti, Zr, Fe, Cu, Nb; 3.70 ≤ a ≤ 5.10, 0 < b ≤ 0.55, 0.00 ≤ c ≤ 0.45, 0.00 ≤ d < 0.20, 0.05 ≤ e ≤ 0.25, 0.00 ≤ f ≤ 0.25, 4.90 ≤ a+b+c+d+e+f ≤ 5.50, and has a structure free of a precipitated phase with a grain diameter of not less than 5.0 µm as observed in Sn- and La-mapping images at a magnification of 800x obtained by area analysis of a cross-sectional structure of the alloy with EPMA.