Matsushita Electric Industrial Co., Ltd.

Sachiko Sugihara

Akira Miura

Hiroshi Yoshizawa

Yoshiaki Nitta

Akira Ohta

A non-pollution zinc-alkaline battery excellent in storage stability can be obtained by using, in formulation for negative electrode, a zinc alloy which contains at least one element selected from the group consisting of bismuth, lithium, calcium and aluminum which is free from mercury, lead, cadmium, indium and thallium is used as an active material and yttrium hydroxide or yttrium oxide optimized in a starting material therefor, particle size and weight loss on heat decomposition as an inorganic inhibitor. The storage stability of the battery can be further improved by adding to the above formulation for a negative electrode a proper amount of a surfactant having a polyethylene oxide group in hydrophilic group and a perfluoroalkyl group in oleophilic group as an organic inhibitor.

Manufacturing of zinc-alkaline batteries

A non-pollution zinc-alkaline battery excellent in storage stability can be obtained by using, in formulation for negative electrode, a zinc alloy which contains at least one element selected from the group consisting of bismuth, lithium, calcium and aluminum which is free from mercury, lead, cadmium, indium and thallium is used as an active material and gallium hydroxide or gallium oxide optimized in a starting material therefor, particle size and weight loss on heat decomposition as an inorganic inhibitor. The storage stability of the battery can be further improved by adding to the above formulation for a negative electrode a proper amount of a surfactant having a polyethylene oxide group in a hydrophilic group and a perfluoroalkyl group in oleophilic group as an organic inhibitor.

Method of manufacturing zinc-alkaline batteries

The present invention provides a method of manufacturing a mercury-free zinc-alkaline battery giving no environmental pollution and having an excellent shelf stability which comprises a corrosion-resistant zinc alloy as an anode active material, an indium compound having appropriate properties, an aqueous alkaline solution as an electrolyte and optionally a fluorine-containing surfactant having the specified chemical structure. The indium compound is indium hydroxide or indium sulfide prepared by neutralizing an aqueous solution of an indium salt. The surfactant has a hydrophilic part of a polyethylene oxide and an oleophilic part of a fluoroalkyl group. The zinc alloy contains a proper amount of at least one of the group of indium, lead, bismuth, lithium, calcium and aluminum. The indium hydroxide or indium sulfide is present in an amount of 0.005 to 0.5 wt % and the surfactant in an amount of 0.001 to 0.1 wt %, based on the weight of the zinc alloy, respectively. Furthermore, the indium hydroxide and indium sulfide in a powder form contain 60 wt % or more of particles having a particle size of 0.5 to 8 .mu.m. The indium hydroxide has a weight loss of 18 to 30 wt % when thermally decomposed at up to 900.degree. C. and a powdery X-ray diffraction pattern having peaks at 4.71.+-.0.10 .ANG., 3.98.+-.0.02 .ANG., 3.57.+-.0.10 .ANG. and 2.66.+-.0.02 .ANG..

The present invention provides a zinc-alkaline battery giving no environmental pollution and having an excellent shelf stability, which comprises a zinc alloy as an anode active material and an aqueous alkaline solution as an electrolyte, and manganese dioxide, silver oxide and oxygen as cathode active materials, the anode constituting the battery together with the cathode and the alkaline electrolyte being in a gel form and containing 0.001 to 0.1 wt % based on the weight of the zinc alloy of a surfactant as an organic inhibitor represented by the formula of

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Higashiosaka, Japan

Sachiko Sugihara