Hydrogen storage alloy for nickel-metal hydride battery

Hydrogen storage alloy for a nickel-metal hydride battery is characterized in that the composition expression of the alloy is RE1-x-wSmwAxNiyCouMz, wherein x is more than 0 and smaller than 0.35, y is more than 2.8 and smaller than 4.5, z is more than 0 and smaller than 0.5, u is more than 0 and smaller than 0.1, w is more than 0.1 and smaller than 0.8, x+w is more than 0.2 and smaller than 0.8, and y+u+z is more than 3.3 and smaller than 4.8. RE is a rare earth element, and contains one or more of Sc, Y, La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Eb and Lu, A is base metal or alkaline-earth metals, and contains one or more of K, Ca, Na, Mg and Li, M is a transition metal element or main group elements III and IV, and contains one or more of V, Cr, Mn, Fe, Cu, Zn, Zr, Nb, Mo, Tc, Ag, Al, B, C and Si. The hydrogen storage alloy is subjected to thermal treatment under inert protective atmosphere so as to form a crystal structure with superlattices, an axis C in lattice parameters is 0.4-5nm, a domain interface vertical to a crystalline grain axis C is a phase-reversal domain, the sizes of crystal grains are 3-10nm along the length of the axis C. The crystal grains with the structure account for 50%-95% of the alloy. The thermal treatment temperature is 600 DEG C-1000 DEG C, and the thermal preservation time is 5h-48h.