Primearth Ev Energy Co., Ltd.

Yuki Sakito

Hiroyuki Sakamoto

Shinichiro Ito

Katsumi Kashiwagi

Suguru Muraki

A nickel-metal hydride battery is provided with a positive electrode and a negative electrode including hydrogen absorbing alloys. The hydrogen absorbing alloys of the negative electrode include a first hydrogen absorbing alloy and a second hydrogen absorbing alloy having a higher hydrogen equilibrium dissociation pressure than the first hydrogen absorbing alloy. Each hydrogen absorbing alloy includes an element A having high affinity for hydrogen and an element B having low affinity for hydrogen. The ratio of a substance amount of the element B to a substance amount of the element A is greater in the second hydrogen absorbing alloy than the first hydrogen absorbing alloy.

Nickel-metal hydride battery

A nickel-hydrogen storage battery includes a positive electrode, a negative electrode using an ABbased hydrogen-absorbing alloy, and a separator arranged between the positive and negative electrodes. The ABbased hydrogen-absorbing alloy includes an A element, which is a constituent element of a misch metal, and a B element, which includes nickel and cobalt. The ratio of the amount of substance of the B element to that of the A element is 5.2 or more and 5.4 or less. The ratio of the amount of substance of cobalt to that of the A element is 0.15 or more and 0.4 or less. The liquid retention volume (V) and the true volume (V) of the separator, the theoretical capacity of the negative electrode (C), and the theoretical capacity of the positive electrode (C) satisfy the following expression.2.0&#x2266;1/2&#xd7;1/2&#x2266;3.1

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Toyohashi, Japan

Yuki Sakito