HYDROGEN STORAGE ALLOY, ELECTRODE, NICKEL-METAL HYDRIDE RECHARGEABLE BATTERY AND METHOD FOR PRODUCING HYDROGEN STORAGE ALLOY

摘要

A hydrogen storage alloy with at least two phases containing La, Ni, and Y or a heavy rare earth element, including a first phase having a composition represented by the general formula R1_aR2_bR3_cNi_dR4_e (wherein R1 is at least one element essentially containing La, R2 is at least one element selected from the group consisting of Y and a heavy rare earth element, R3 is Ca and/or Mg, R4 is at least one element selected from the group consisting of Co, Mn and Al, and a, b, c, d and e are numerical values that satisfy the numerical expressions a+b+c=1, 0≦b≦0.3, 0≦c≦0.4, 3.0d+e4.0, and 0≦e≦1) and a second phase having a higher concentration of Y or a heavy rare earth element than that of the first phase, and is dispersed in the first phase.