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AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsMunehisa Ikoma, Norikatsu Akutsu, Masashi Enokido, Fumihiko Yoshii, Hideo Kaiya, Shingo Tsuda
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The tap density of nickel hydroxide powders is improved, the expansion of a positive electrode is inhibited and the energy density of the positive electrode and the cycle life characteristics are improved by specifying the shape of the nickel hydroxide powders and besides, adding to the nickel hydroxide powders at least one of Cd, Ca, Zn, Mg, Fe, Co and Mn. The nickel hydroxide active material powders contain 1-7 wt % of at least one of Cd, Ca, Zn, Mg, Fe, Co and Mn and comprise a mixture of spherical or nearly spherical particles and non-spherical particles.
A nickel hydroxide active material powder for use in making nickel positive electrodes, which is a mixture of spherical or nearly spherical particles having a particle size of about 10-30 .mu.m and non-spherical particles having a particle size of less than about 10 .mu.m which comprises a nickel hydroxide powder containing 1-7 wt % of at least one metal selected from the group consisting of cadmium, calcium, zinc, magnesium, iron, cobalt and manganese before production of positive electrodes and is an aggregate of innumerable primary particles of 0.1 .mu.m or less.
A nickel hydroxide active material for nickel positive electrodes which comprises a nickel hydroxide powder containing 1-7 wt % of at least one metal selected from the group consisting of cadmium, calcium, zinc, magnesium, iron, cobalt and manganese, is an aggregate of innumerable primary particles of 0.1 .mu.m or less, and has a void volume having a pore radius of 30 .ANG. or more of 20-70% based on total void volume.
A nickel positive electrode which comprises a three-dimensional porous body or a flat sheet which supports a nickel hydroxide active material mainly composed of nickel powder and which imparts electric conductivity wherein the nickel hydroxide active material comprises a mixture of spherical or nearly spherical particles having a particle size of about 10-30 .mu.m and non-spherical particles having a particle size of less than about 10 .mu.m which comprises a nickel hydroxide powder containing 1-7 wt % of at least one metal selected from the group consisting of cadmium, calcium, zinc, magnesium, iron, cobalt and manganese and a powder of at least one member selected from the group consisting of cobalt, cobalt oxide, zinc oxide, zinc, cadmium and cadmium oxide and is an aggregate of innumerable primary particles of 0.1 .mu.m or less.
An alkali storage battery comprising a nickel positive electrode mainly composed of nickel oxide, a negative electrode mainly composed of a hydrogen absorbing alloy capable of carrying out electrochemical hydrogen absorbing and desorbing reaction or a negative electrode mainly composed of cadmium oxide, an alkali electrolyte, a separator, a case containing these electricity generating elements and a sealing plate provided with a safety vent wherein before initial charging and discharging, said nickel positive electrode is mainly composed of a three dimensional porous body or a flat sheet which imparts electrical conductivity and supports nickel hydroxide powders comprising a mixture of spherical or nearly spherical particles having a particle size of about 10-30 .mu.m and non-spherical particles having a particle size of less than about 10 .mu.m which comprises nickel hydroxide powders containing 1-7 wt % of at least one metal selected from the group consisting of cadmium, calcium, zinc, magnesium, iron, cobalt and manganese and additionally containing a powder of at least one member selected from the group consisting of cobalt, cobalt oxide, zinc oxide, zinc, cadmium, and cadmium oxide and is an aggregate of innumerable primary particles of 0.1 .mu.m or less, the specific gravity of the alkali electrolyte is 1.23-1.4, and the amount of the electrolyte per 1 Ah of battery capacity is 1.0-2.0 cm.sup.3 /Ah.
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