Hydrogen-absorbing alloy for battery and secondary nickel-metal hydride

Abstract

There is provided a hydrogen-absorbing alloy for battery comprising a rapidly-quenched alloy having the composition represented by a general formula ANi.sub.a M.sub.b M'.sub.c T.sub.d (where, A is composed of La, Ce, Pr, Nd and Y, an amount of La content in A is 50-99 wt %, an amount of Ce content is 1-30 wt %, an amount of Pr content is 0-10 wt %, an amount of Nd content is 0-10 wt % and an amount of Y content is 0-10 wt %; M is at least one element selected from Co, Fe and Cu; M' is at least one element selected from Mn and Al; T is at least one element selected from B, Si, S, Cr, Ga, Ge, Mo, Ru, Rh, Pd, Ag, In, Sn, Sb, Bi, P, V, Nb, Ta and W; and a, b, c and d are atomic ratios and satisfy 3.2.ltoreq.a.ltoreq.4.0, 0.4.ltoreq.b.ltoreq.1.0, 0.3.ltoreq.c.ltoreq.0.8, 0.ltoreq.d.ltoreq.0.2, 4.9.ltoreq.a+b+c+d.ltoreq.5.4), characterized in that a hydrogen equilibrium pressure when the number of hydrogen atoms absorbed by one atom of the alloy at a temperature of 60.degree. C. is 0.4 is 0.05-0.6 atm. With the above arrangement, a hydrogen-absorbing alloy capable of realizing a small decrease in capacity under the low-temperature area and high-temperature area, a large electrode capacity in a wide temperature range, and a long life, and a secondary nickel-metal hydride battery using this alloy can be obtained.