Nickel-metal hydride storage battery

The present invention is to provide a nickel-metal hydride storage battery comprising a positive electrode (1) mainly composed of nickel hydroxide, a negative electrode (2) mainly composed of a hydrogen storage alloy powder electrochemically absorbing and desorbing hydrogen. a separator (3) and an alkaline electrolyte, wherein zinc and rare earth element are contained in at least one selected from the group consisting of the positive electrode, the separator and the electrolyte. Hence, the charge efficiency of nickel hydroxide can be improved at a high ambient temperature, and furthermore, the deterioration of the negative electrode due to oxidation can be suppressed, thereby enabling a provision of a nickel-metal hydride storage battery with a longer cycle life.