POSITIVE ELECTRODE ACTIVE MATERIAL FOR NICKEL HYDROGEN SECONDARY BATTERY, NICKEL HYDROGEN SECONDARY BATTERY CONTAINING POSITIVE ELECTRODE ACTIVE MATERIAL, AND EVALUATION METHOD OF POSITIVE ELECTRODE ACTIVE MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a positive electrode active material for nickel hydrogen secondary battery, capable of suppressing decrease of capacity recovery rate even in deep discharge state, and to provide a nickel hydrogen secondary battery containing the positive electrode active material.SOLUTION: A nickel hydrogen secondary battery 2 includes an electrode group 22 consisting of a separator 28, a positive electrode 24 and a negative electrode 26. The positive electrode 24 is composed of composite particles containing a compound of Co and a compound of Ni. Assuming the jump amount of X-ray absorption fine structure spectrum of the Co between 7600-7800 eV obtained by measurement using conversion electron yield method is A, and the jump amount of X-ray absorption fine structure spectrum of the Ni between 8300-8500 eV is B, the R as a ratio represented by A/B satisfies a relation of R≥0.3.SELECTED DRAWING: Figure 1