Hydrogen storage alloy

Abstract

Hydrogen storage alloy has a composition expressed by a general formula (La a Nd b “A” c “D” d ) 1-w Mg w Ni x Al y “T” z , where “A”, “D” and “T” represent at least one element selected from a group consisting of Sm and Gd, a group consisting of Pr, Eu, etc., and a group of consisting of V, Nb, etc., respectively; subscripts a, b, c and d satisfy relationship shown by a≧0, b≧0, c>0, 0.1>d≧0, and a+b+c+d=1; and subscripts w, x, y and z fall in a range shown by 0<w≦0.25, 0.05≦y≦0.35, 0≦z≦0.5, and 3.15≦x+y+z≦3.35.

1 . Hydrogen storage alloy comprising:
 a composition expressed by a general formula:
   (La a Nd b “A” c “D” d ) 1-w Mg w Ni x Al y “T” z    
   where “A” represents at least one element selected from a group consisting of Sm and Gd;   “D” represents at least one element selected from a group consisting of Pr, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Zr, Hf, Ca and Y;   “T” represents at least one element selected from a group consisting of V, Nb, Ta, Mo, Mn, Fe, Co, Zn, In, Cu, Si, P and B;   subscripts a, b, c and d satisfy relationship expressed by a≧0, b≧0, c>0, 0.1>d≧0, and a+b+c+d=1; and   subscripts w, x, y and z fall in a range shown by 0<w≦0.25, 0.05≦y≦0.35, 0≦z≦0.5, and 3.15≦x+y+z≧3.35.   
     
     
         2 . The hydrogen storage alloy according to  claim 1 , wherein
 the subscripts a, b and c satisfy relationship expressed by c>a+b.   
     
     
         3 . The hydrogen storage alloy according to  claim 2 , wherein
 the subscripts a and b satisfy relationship expressed by a≧b.   
     
     
         4 . The hydrogen storage alloy according to  claim 3 , wherein the subscript d is 0.02 or less. 
     
     
         5 . The hydrogen storage alloy according to  claim 4 , wherein
 the “T” contains at least one element other than Co and Cu.