HYDROGEN STORAGE ALLOY POWDER AND NICKEL HYDROGEN SECONDARY BATTERY USING THIS HYDROGEN STORAGE ALLOY POWDER

摘要

This nickel hydrogen secondary battery 2 is provided with: an outer casing can 10; and an electrode group 22 that is contained within the outer casing can 10 together with an alkaline electrolyte solution in a hermetically sealed state. The electrode group 22 is composed of a positive electrode 24 and a negative electrode 26, which are superposed on each other with a separator 28 being interposed therebetween. The negative electrode 26 contains a hydrogen storage alloy powder that is an aggregate of hydrogen storage alloy particles. If M is the average particle diameter of the hydrogen storage alloy particles, P is the particle diameter equal to 1/2 of M, and Q is the particle diameter equal to 1/3 of M, the content of the particles having particle diameters of P or less is less than 20% by mass of the whole hydrogen storage alloy powder, and the content of the particles having particle diameters of Q or less is less than 10% by mass of the whole hydrogen storage alloy powder.