JPS63195957A - Alkaline battery - Google Patents

Abstract

PURPOSE:To obtain an alkaline battery having long storage life even if low amalgamated zinc negative electrode is used by making exist cobalt or cobalt alloy on the surface, in contact with a negative active material, of a negative current collector. CONSTITUTION:Cobalt or cobalt alloy is made to exist on the surface, where is in contact with a negative active material, of a negative current collector. The part, in contact with the negative active material, of the negative current collector is made of copper or brass, and the mercury on the surface of the negative current collector diffuses inward during storage and the mercury concen tration on the surface of the current collector is lowered. The evolution of hydrogen gas caused by a local cell produced between the current collector and the negative zinc, and the evolution of hydrogen gas caused by the lack of the mercury content on the surface of the negative zinc, which is produced by the transfer of mercury from the zinc to the current collector, and the dissolu tion of the zinc into an alkaline electrolyte are prevented. Thereby, an alkaline battery having long storage life and capable of using low amalgamated zinc can be obtained.

Description

Detailed Description of the Invention a Field of Application of Rakudo The present invention uses zinc or zinc alloy as a negative electrode active material, and various depolarizers such as manganese dioxide, silver oxide, mercury oxide, nickel hydroxide, oxygen, etc. as a positive electrode active material.

This invention relates to improvements in various alkaline batteries that use aqueous alkaline solutions as electrolytes.

A common problem with conventional alkaline batteries is hydrogen gas generation due to local batteries that occur between the copper or brass that makes up the contact surface of the negative electrode active material of the negative electrode body and the negative electrode active material zinc. Hydrogen gas generated by corrosion increases the gas pressure inside the battery, which poses the risk of electrolyte leakage and, in extreme cases, rupture.Also, the negative electrode zinc self-depletes, causing the battery capacity to increase. Because of the large drop in the lid, conventional methods have been attempted in which the copper or brass of the negative electrode current collector is frozen with gold (4) mercury in the presence of an alkaline aqueous solution. Mercury has a high hydrogen overvoltage, and when it comes into contact with copper or brass, it quickly diffuses to the surface and forms a uniform diffusion layer, so immediately after freezing, it does not form a local battery with the zinc negative electrode and hydrogen gas is generated. It can be prevented. However, during storage after freezing, the mercury that covered the negative electrode current collector gradually diffuses deep into the copper or brass, and as the mercury t on the surface of the negative electrode current collector decreases and the storage period becomes longer, the above Similarly, it formed a local battery and had the disadvantage of increasing hydrogen gas generation. However, since the negative electrode active material zinc or zinc alloy is used with a hydrated surface, some of the mercury on the negative electrode surface migrates to the negative electrode current collector, causing the above-mentioned ice-treated negative electrode current collector surface to This has the effect of slightly compensating for the decrease in mercury t, and when the conventionally used zinc negative electrode with a freezing rate of ~10% is used, hydrogen gas generation is suppressed for six months to one year when stored at 36°C. was. However, in recent years, in order to reduce pollution, there has been an increasing social need to reduce the amount of mercury contained in batteries, and efforts have been made to reduce the amount of mercury that hydrates the surface of the zinc or zinc alloy of the negative electrode active material. , hydration rate 3
．． Zinc negative electrodes with a density of 0 to 2.0 cm have already been put into practical use, but with zinc negative electrodes with such a low hydration rate, only a small amount of mercury transfers from the negative electrode surface to the negative electrode current collector surface, and the current collector is sufficiently absorbed. The decrease in the mercury layer after storage cannot be compensated for, and the zinc on the negative electrode surface dissolves in the alkaline electrolyte, resulting in hydrogen gas generation due to this corrosion and the formation of local batteries between the current collector and the negative electrode zinc. Due to the generation of gas, the battery deteriorated after about half a year when stored at 36°C, resulting in a decrease in discharge performance.

Problems to be Solved by the Invention As mentioned above, in the conventional method, during long-term storage, hydrogen gas is generated between the negative electrode current collector and negative electrode zinc by the local S battery, and negative electrode zinc is added to the alkaline IJ electrolyte. Due to the generation of hydrogen gas due to the dissolution of the battery, the battery was significantly deformed and its capacity decreased, resulting in problems with reliability and battery performance after storage.

The present invention solves the above-mentioned problem by treating the negative electrode assembly with cobalt (Go) or a cobalt alloy to prevent mercury from diffusing into the current collector. The purpose of this invention is to provide an alkaline battery that has long-term reliability, no problems in storage, and has excellent discharge performance even when a zinc negative electrode is used.

Means for Solving the Problems In order to solve this problem, the present invention uses zinc or a zinc alloy for the negative electrode active material and caustic potash for the electrolyte.

Alkaline aqueous solution containing caustic soda as the main ingredient, manganese dioxide, silver oxide, and mercury oxide as positive electrode active materials.

G
It is characterized by the presence of cobalt alloy or cobalt alloy.

Function In the present invention, since the material of the part of the negative electrode current collector that comes into contact with the negative electrode active material is made of copper or brass, mercury on the surface of the negative electrode current collector will diffuse into the inside of the current collector during long-term storage. death,
The mercury concentration on the current collector surface decreases, and hydrogen gas is generated by a local battery between the copper or brass current collector and the negative electrode zinc, and the mercury on the negative electrode zinc surface migrates to the current collector surface. The lack of mercury on the zinc surface and the generation of hydrogen gas due to the dissolution of zinc in the alkaline electrolyte were solved by coating the current collector with Go or cobalt alloy in advance, resulting in excellent storage properties even after long-term storage. This resulted in an alkaline battery that can use a zinc negative electrode with a low hydration rate.

When mercury is present on the surface of the copper or copper alloy brass that constitutes the negative electrode current collector, the mercury gradually diffuses into the current collector as it is stored. However, co or In,
Pb, C(1, Tl, Sn, Ga, Bi.

N1. By pre-existing a cobalt alloy containing one or more selected from Mug on the surface of the current collector, C
o or because the cobalt alloy has a high affinity for mercury, the mercury present on the GO or the cobalt alloy is retained in the CO or cobalt alloy layer and hardly diffuses into the interior of the current collector; A uniform mercury layer is always maintained on the surface of the current collector, no local batteries are formed between the current collector and the negative electrode giant, and hydrogen gas generation by the local batteries is suppressed.

Furthermore, since a high concentration of mercury is always retained on the surface of the current collector, there is no migration of mercury from the surface of the negative electrode active material zinc hydrate or glazed zinc alloy to the current collector, and the negative electrode active material water Corrosion caused by dissolution of zinc in the alkaline electrolyte is also suppressed even if the conversion rate is 3 or less.

As described above, the present invention prevents the occurrence of local batteries during long-term storage by making CO or a cobalt alloy exist on the surface of the negative electrode 49 and preventing the diffusion of mercury into the current collector. Alkali'1 with excellent storability in terms of conversion rate
This is the realization of a pond.

Example Next, embodiments of the present invention will be described with reference to the drawings.

Indium such as cobalt sulfate or cobalt sulfate and indium sulfate is added to a 10i11t aqueous solution of caustic potassium.

Pb, C(1, Tl, an, G&, Bi, )
ii. Dissolve 5 g of any of the sulfates, drop it onto the copper surface of the negative electrode current collector described below, wash with water after 6 minutes, dry it, and prepare a 0.3μ thick Co or various types of Co as shown in the table below. cobalt alloy! − was formed. A 10% by weight aqueous solution of caustic potash is again dropped on the inner surface of this current collector, and then metallic mercury is poured in an amount of 0.2 yag per 11 copper surface areas of the negative electrode current collector, and this is washed with water. Then, the mixture was replaced with acetone and then dried to create a negative electrode current collector in which the Co or cobalt alloy layer was frozen. Furthermore, as a conventional example, a current collector treated with only mercury without a Go or cobalt alloy layer was also created using the above method.

Using these negative electrode assemblies, a button-deaf alkaline manganese battery as shown in the drawing was fabricated. In the figure, 1 is a negative electrode assembly that also serves as a negative electrode terminal, and is made of stainless steel and steel plywood clad material, with copper on the inside. is alms. , 2 is a sealing gasket made of polyamide resin that insulates the positive and negative electrodes and seals the opening. 3 is a cylindrical gold 144 case with a bottom, which is made of iron plated with nickel on the entire surface, and at the inner bottom of the case is mixed powder 4 of manganese dioxide and graphite formed into a tablet shape, which is coated with iron and nickel. It is press-fitted together with the plated positive electrode ring 5. 6 is a separator made of a microporous polypropylene membrane. Ryo is an electrolyte-impregnated material made of vinylon nonwoven fabric. 8 is a negative electrode, in which an electrolytic solution in which a 40% by weight aqueous solution of caustic potash is saturated with zinc oxide is gelled with sodium polyacrylate, and 0.0% In is added to the gel.
The frozen zinc alloy powder is obtained by freezing zinc alloy powder containing 6% by weight and 0.02% by weight of p'b at a freezing rate of 2% by weight. The prototype battery has a diameter of 11.6 meshes,
The height was 5,411EI, and when depositing the heconalt alloy on the copper surface of the negative electrode current collector, the amount of each metal other than Go constituting the cobalt alloy was 40% by weight and 8t% of the deposited amount. .

The following table shows the discharge performance of the prototype battery after 6 and 12 months of storage at 36°C and the change in total battery height compared to the initial state. The discharge performance was expressed as the discharge duration when discharging at 510Ω at 20°C with a final voltage of 0.9V.

(Left below) As seen in this table, in the conventional example (No. 1), 3
Even after 6 months of storage at 6°C, the total height of the battery slightly changed and expanded, and the discharge time was also slightly shorter than in the example. 3 more
After 12 months of storage at 6°C, the total height of the battery had changed so much that blisters could be easily detected by visual inspection, and the discharge time had also significantly deteriorated. However, Co or cobalt alloy was present on the surface of the negative electrode current collector (No, 2 to N
0.16), there is no change in the total battery height even after 12 months of storage at 35°C, and the discharge performance is also stable.

As described above, the present invention prevents the generation of hydrogen gas after long-term storage by treating the surface of the negative electrode current collector with a mercury alloy, thereby realizing an alkaline battery with excellent practical performance even with a zinc negative electrode with a low rate of flux. This is what I did.

In addition, in the example, the thickness of Go or cobalt alloy attached to the negative electrode current collector was 0.3 μm, but it was 0.06 μm.
It has been confirmed that if it is 0.1 μ or more, it is effective, and if it is 0.1 μ or more, it has almost the same effect as the example. However, if the thickness of Co or cobalt alloy exceeds 2μ, the adhesive layer may peel off, so it is desirable that the thickness be 0.1μ to 1.0μ. In addition, when attaching a cobalt alloy to the copper surface of the negative electrode current collector, in the example, the weight of the metals other than Co constituting the cobalt alloy described separately is 40 weights and 11 tons of adhesion 1 haze.
Although it was unified so that it was 50 weight i%, it has the same effect as the example. Further, although CO or a cobalt alloy is present and a mercury layer is applied after washing with water and drying, it is also possible to hydrate the film as it is without washing with water or drying. Furthermore, although steel was used as the material for the negative electrode current collector in the examples, the same effect can be obtained using brass. In the examples, button-type alkaline batteries were explained, but other alkaline batteries such as silver oxide batteries and mercury batteries in which copper or brass is used as the negative electrode current collector and zinc or zinc alloy is used as the negative electrode active material/electrode are also applicable. But it has the same effect.

Effects of the Invention As described above, according to the present invention, an alkaline battery with excellent long-term storage performance can be provided even when a zinc negative electrode with a low rate of reduction is used.

[Brief explanation of the drawing]

The drawing is a sectional side view of a main part of a button-type alkaline manganese pond according to an embodiment of the present invention. 4...Positive electrode, 6...Separator, 7.
...Liquid-containing material, 8...Negative electrode.

Claims (2)

[Claims] (1) As the negative electrode active material, use zinc or a zinc alloy with an aqueous conversion rate of 3% or less, use an alkaline aqueous solution as the electrolyte, and pre-exist cobalt or a cobalt alloy on at least the surface of the negative electrode current collector that is in contact with the negative electrode active material. An alkaline battery characterized by: (2) Cobalt alloy has Co as its main component, indium,
The alkaline battery according to claim 1, characterized in that it contains one or more selected from the group of lead, cadmium, thallium, tin, gallium, bismuth, nickel, and silver.