| 摘要 |
PROBLEM TO BE SOLVED: To provide a nickel hydrogen secondary battery arranged so that the decrease in operation voltage can be suppressed while suppressing a self discharge even after having been left over a long period of time.SOLUTION: A nickel hydrogen secondary battery 2 comprises: an outer can 10; an alkali electrolytic solution; and an electrode group 22 which is enclosed in the outer can 10 together with the alkali electrolytic solution in an airtight condition. The electrode group 22 includes a separator 28, and a positive electrode 24 and a negative electrode 26, provided that the positive and negative electrodes are superposed on each other through the separator. The alkali electrolytic solution includes NaOH as a primary component of a solute. The negative electrode 26 includes a hydrogen-absorbable alloy having a composition expressed by the following general formula: LnMgNiM(where Ln represents at least one element selected from rare earth elements and Zr; M is Al; the subscripts x, y and z satisfy the relation represented by 0≤x≤0.05, 3.3≤y≤3.6 and 0≤z≤0.50, of the rare earth elements, La is 25% or less, which is a proportion in Ln). |
