A secondary battery, a nickel hydrogen

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PROBLEM TO BE SOLVED : To improve the charging/discharging cycle service life by using a positive electrode containing Ni hydroxide, a negative electrode having the specific composition, a separator and an alkaline electrolyte, and satisfying at least one of conditions where the positive electrode contains oxide/hydroxide non-coprecipitating with the Ni hydroxide and the negative electrode, the separator and the alkaline electrolyte contain oxide/hydroxide other than an alkaline metal and Ni. SOLUTION : In a negative electrode, the radio of the total of the atomic number of a rear earth element and magnesium to the total of the atomic number of elements other than these is set to (1 : 3 to 1 : 3.8). A positive electrode contains oxide or hydroxide (here, except for oxide and hydroxide of alkaline metal and oxide and hydroxide of Ni) non-coprecipitating with nickel hydroxide. The oxide and the hydroxide are selected from among Nb, Gd, Er, Bi, Zn, Dy, Ho, Y, Zr, V, Cr, Yb, Mo, Al and Si. The total metal quantity in the oxide/ the hydroxide contained in a secondary battery is set to 0.1 to 2 wt.% of a hydrogen storage alloy of the negative electrode.