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, 3.0 d + e 4.0, 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.