Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Patent
1986-11-26
1988-04-05
Walton, Donald L.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
429229, 429230, H01M 440
Patent
active
047358769
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an improvement for a zinc-alkaline battery using zinc as an anode active material, aqueous alkaline solution as an electrolyte, and manganese dioxide, silver oxide, mercury oxide, oxygen, or the like as a cathode active material. More particularly, it relates to a zinc-alkaline battery which has enable reduction of the amounts of mercury to be used for amalgamation of the anode zinc surface by using for the anode a zinc alloy containing indium (In), aluminum (Al), lead (Pb), and cadmium (Cd) in a specified combination.
BACKGROUND ART
A problem common to zinc-alkaline batteries is the corrosion of the anode zinc caused by the electrolyte. Namely, zinc is so reactive in an alkali electrolyte as reacting with the electrolyte during long term storage, thereby undergoing self-corrosion in accordance with the following equation:
Hydrogen gas generated from the corrosion causes a gas pressure in the battery to elevate, which has the danger of causing leakage of electrolyte, bursting and the like. Accordingly, it has been hithertofore adopted as an industrial technique to use amalgamated zinc powder which is made by adding about 5 to 10% by weight of mercury to zinc, to increase the hydrogen overvoltage and to suppress corrosion to a practically allowable level. In recent years, however, there has been an increasing social demand to decrease the amount of mercury contained in a battery in order to lower environmental pollution, and various studies have been conducted. For example, methods have been proposed, which use zinc alloy powder formed by adding Pb, gallium, In etc. having a high hydrogen over-voltage into zinc to improve the corrosion resistance and to decrease the mercury concentration rate. Although these methods are effective in corrosion inhibition, they have an adverse effect in that their heavy load discharge performance is deteriorated due to the decrease of mercury concentration rate. Though the reasons why the deterioration of heavy road discharge performance occurs at the decreased mercury concentration rate in these proposed methods are not clear, they are presumably because the anode surface becomes covered with the discharge product of the zinc alloy anode, so that the smooth supply of hydroxide ions onto the zinc surface necessary for a discharge reaction is prevented. Thus, there is a need for a zinc anode of low mercury concentration rate which is excellent in both corrosion resistance and heavy load discharge performance.
Further, it has been proposed, mainly with the view of improving manganese dry batteries, that a good corrosion inhibitory effect can be obtained by using for an anode a zinc alloy formed by adding In to zinc or zinc alloy [Japanese Patent Application Kokoku (Post-Exam. Publn.) No. 3204/58]. Though the description of the above proposal includes the cases wherein besides In, one or more elements selected from Pb, Cd, Al, Mg, iron, chromium, calcium, mercury, bismuth, antimony, silver, silicon, nickel, manganese etc. are added to zinc as an impurity or as an additive, it does not state clearly whether the above-mentioned various elements are each contained as an impurity or added as an effective additive except for the effectiveness of In and Pb used in combination as an additive element. Further, it neither states which element is effective for corrosion inhibition, nor shows the suitable amount to be added except those for In and Pb. Thus, no investigation has ever been made on the effect of combined use of these elements, particularly for a zinc-alkali battery, to find an effective zinc alloy composition.
DISCLOSURE OF THE INVENTION
The object of this invention is to obtain a zinc-alkaline battery of low pollution and of excellent overall performance including discharge performance, storage property and prevention of alkaline leakage by using for the anode a zinc alloy containing In, Al, Mg, Pb and Cd in a specified combination, thereby decreasing the amalgamation rate without causing the deterioration of the discharge per
REFERENCES:
patent: 4376810 (1983-03-01), Takeda et al.
patent: 4500614 (1985-02-01), Nagamine et al.
Miura Akira
Ohira Tsukasa
Okazaki Ryoji
Takata Kanji
Matsushita Electric - Industrial Co., Ltd.
Mitsui Mining & Smelting Co. Ltd.
Walton Donald L.
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