JPS62143366A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To aim at reduction in an amalgamating rate without entailing any deterioration in corrosion resistance and discharge capacity of a negative zinc as well as to form such a zinc alkaline battery that is excellent in integral performance, by using a zinc alloy containing the specified quantity of more than one kind among indium, strontium and aluminum, calcium, magnesium, respectively. CONSTITUTION:A zinc alloy containing 0.05-0.5wt% of indium, 0.005-0.2wt% of strontium and 0.005-0.2wt% of more than one kind among aluminum, calcium and magnesium is used for a negative active material. Thus, various zinc alloys adding various elements to zinc base metal are produced, melted, sprayed by compressed air, and pulverized, then sieved in a grain size range of 50-150 mesh. Next, powder is projected into a 10wt% aqueous solution of caustic potash, mercury of the specified quantity is dropped while stirring it and amalgamated. Afterward, washing it with water, and substitution takes place with acetone and dried up, thus amalgamated zinc alloy powder is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention utilizes zinc as a negative active material, alkaline aqueous solution as an electrolyte, manganese dioxide, silver oxide, mercury oxide, oxygen, and nickel hydroxide as positive electrode active materials. The present invention relates to improvements in negative electrodes for zinc-alkaline batteries using, etc.

Conventional technology fltlF As a common discovery point of zinc-alkaline batteries, 1 during storage
Corrosion caused by the electrolyte of 'l 11 sub-X) can be mentioned.

Conventionally, about 5 to IO weight % of mercury is added to subtense t1),
It has been adopted as an industrial method to suppress the amount of mercury contained in batteries in order to reduce pollution. There is a growing social need to reduce corrosion, and research is being carried out. For example, alloy powders containing lead, cadmium, indium, gallium, etc.
A method has been proposed to improve 1 and reduce the ratio. These corrosion-inhibiting effects are due to the combined effect of multiple additive elements in addition to the effect of the JIT element. Zinc alloys and the like have been proposed as promising systems.

All of these can be expected to have a certain degree of corrosion resistance, and a certain degree of reduction in the water resistance can be expected, but it is necessary to search for an alloy system with even better corrosion resistance.

In addition, with the aim of improving manganese dry batteries, we have developed an F+
There is a proposal that the anti-corrosion effect is great if it is used for IE.

Problems to be Solved by the Invention Among the above proposals, in addition to indium, Fe, Cd, Cr, Pb, Ca, and H are used as elements in the zinc alloy.
g.

Bi, Sb, t\I, Ag, Mg, si, Ni, M
The description includes cases in which one or more types of impurities or additives such as n are included. It is not clear whether the element is added as an impurity or as an effective element, and it is not even clear which element is effective for corrosion prevention, and the appropriate amount of addition is unknown.

There is no mention of anything other than lead.

It remains a future challenge to study the effects of the combination of these elements in sub-jf) alkaline batteries and to find an effective alloy composition.

The present invention reduces the water ratio without deteriorating the corrosion resistance and discharge performance of negative electrode zinc, and improves discharge performance, storage stability, and low pollution.
The purpose of the present invention is to provide a zinc-alkaline battery that is resistant to leakage and has excellent overall performance.

Means for Solving the Problems The present invention provides an electrolyte containing caustic potash, an alkali aqueous solution containing caustic soda as a main component, f'I (box active material containing zinc,
Positive electrode active materials include 1-himanganese diacid, 1-arsenic acid, and oxygen.

Nitrogen is used as the negative electrode of so-called zinc-alkaline batteries that use mercury oxide, etc. > is the main component, and indium is 0°005 ~
0.5% by weight, strondium 0.005-0.2f
fiM%, aluminum, calcium.

The present invention is characterized in that a zinc alloy containing 0.005 to 0.2% by weight of one or more types of magnesium is used as the negative electrode active material.

The present invention conducted experiments focusing on Sr as an additive element to zinc alloys, and found that 1) alloys in which Sr was added alone either lacked corrosion protection 11 or had a large combined effect with the additive elements;
In particular, it was discovered and completed that when the above-mentioned elements are combined and contained in appropriate amounts, an extremely remarkable composite anti-corrosion effect can be obtained.

Action The anti-corrosion effect of the addition of each element and the combined effect of these elements are unclear as in Action Mechanism 1, or are speculated as follows. First, since Sr has a high affinity for mercury, Sr is thought to have the effect of facilitating uniform hydration when hydrating the surface of a zinc alloy. Furthermore, it has the effect of smoothing the surface of the sub-jf) alloy powder, which is pulverized by spraying molten zinc alloy, by eliminating wrinkles. Because Sr has an electrical potential that is electrically less noble than zinc, it is easier to eat it than zinc. A sufficient anticorrosive effect cannot be obtained with the addition of Ji alone. In addition, in has traditionally been known as an additive element with a large corrosion-preventing effect, and it increases the hydrogen overvoltage of zinc alloys, and since it is easily compatible with mercury, it is effective in making the surface condition uniform through hydration. It is also expected to play a role in maintaining a high mercury concentration on the surface by fixing mercury on the surface and crystal grains. Also A1. Since both Ca and Mg have low frl affinity for mercury, they suppress the diffusion of mercury into the interior of the zinc alloy to maintain the mercury concentration on the surface, and the zinc alloy powder obtained by the injection method as well as Sr. It has the effect of smoothing the surface and reducing surface roughness. However, like Sr, it has a base electric charge (et), so adding it alone will not provide a sufficient anticorrosion effect, and adding too much will actually result in less corrosion protection.

As mentioned above, each additive element is considered to have a different effect. However, when elements other than 1n are added alone, the anticorrosive effect is poor, but by adding the elements in combination according to the present invention, a zinc alloy can be obtained that has corrosion resistance far superior to that obtained by adding 4'' of 1n alone. It will be done. This is because each of the aforementioned elements has advantages over each other.

By complementing each other's weaknesses, adding a small amount of mercury can
) The hydrogen overvoltage on the surface of alloy t5) is maintained for a long period of time, and the surface condition, I2I! It is thought that this is due to the bundling that uniformly heats the surface M and further reduces the surface M. The present invention thereby realizes a corrosion-resistant negative electrode with a low water conversion rate, and a low-pollution negative electrode with excellent discharge performance and storability.
It is necessary to use alkaline batteries.

This will be explained in detail in the example 131 below.

Example Processing of purity 99.997'; 1) Various zinc alloys were prepared by adding various elements shown in the following table to the base metal,
It is melted at 0℃ and sprayed with compressed air to form a 50%
The particles were sieved to a particle size range of ~150 mesh. Next, the above powder was poured into a 10% by weight aqueous solution of caustic potash,
A predetermined amount of mercury was added dropwise while stirring, and the mixture was left to cool for a while. Thereafter, it was washed with water, substituted with acetone, and dried to produce a frozen zinc alloy powder.

Further, hydrated zinc alloy powder or hydrated zinc alloy powder other than the examples of the present invention were also prepared in the same manner as comparative examples.

Using these hydrated powders, the button-shaped silver oxide battery shown in the figure was manufactured. In the figure, ■ is a sealing plate made of stainless steel, and its inner surface is coated with copper plating 1'. 2. An electrolytic solution containing a 40% by weight aqueous solution of fragile potassium saturated with zinc oxide is gelled with carboxymethyl cellulose, and in this gel there is a hydroxide! ;) It is a zinc negative electrode in which alloy powder is dispersed. 3 is a cellulose-based liquid retaining material, 4 is a separator made of porous polypropylene, 5 is a positive electrode made of a mixture of silver oxide and graphite and pressure molded, 6 is a positive electrode ring made of nickel-plated iron, and 7 is stainless steel. This is a positive electrode can made of aluminum, and its inner and outer surfaces are nickel plated (not shown). 8
is a polypropylene 91 gasket, which is compressed between the positive electrode can and the sealing plate by bending the positive electrode can.

The prototype battery has a diameter of 11-G nun, a height of 5 mm,
4 nun, and the weight of the hydrated powder of the negative electrode is I 93
The amount of mercury added was 2% by weight based on the zinc alloy powder.

The following table shows the composition of the zinc alloy of the prototype battery, and the changes in discharge performance and total battery height after storage at 60°C for one month. The discharge performance was expressed by the discharge duration when discharging at 510Ω at 20° C. with a final voltage of 0.9V.

In addition, after leaving the battery for 2 months at a temperature of 60° C. and a humidity of 90-6, the state of leakage was visually determined, and the number of leaking batteries was also indicated.

In this table, the change in the total battery height is stable after the battery is sealed due to the stress relationship between the components of each battery 11. However, in batteries where a large amount of hydrogen gas is generated due to corrosion of the zinc negative electrode, there is a tendency for the total battery height to increase due to an increase in battery internal pressure that counters the above-mentioned power to reduce the electric height. becomes stronger.Thus, by storage?fff
i+[! Increasing the corrosion resistance of zinc negative electrodes by increasing or decreasing the total height
I can do lli sukokichi. In addition, in batteries with insufficient corrosion resistance 11, the total height of the battery increases, the leakage resistance deteriorates due to an increase in battery internal pressure, zinc is consumed due to corrosion, and an oxide film forms on the zinc surface. The discharge performance is significantly deteriorated due to inhibition of the discharge reaction due to the presence of hydrogen gas, and the discharge duration largely depends on the corrosion resistance of the negative electrode.

Now, in the table, the comparison ρI(!:t) of the present invention, and the case where an additive element is added alone among No. 1 to 8 listed above (
Compared to No. 1.2, 3.4.5, when two elements are added (No. 6.7.8), the corrosion resistance and discharge performance of the negative electrode are somewhat improved. ! -Kashi In, S
Examples of the present invention (No. 10. II,
12.15.16.1? , 20.21.23.24
゜25, 26.27.28.29.30>, corrosion resistance and discharge performance are even better than in the above comparative example.
The combined effect of the added elements is clearly shown. - When the crab element coexists and there is an excess or deficiency in the crab content (No,
9, 13.14.18.19.22.31.32) are not much different from the comparative example, and the combined effect is poor.

As mentioned above, the present invention includes In, Sr, AI, Ca,
Mg in a suitable combination, for example (No, 27.28.
29.30), a zinc alloy coexisting with an appropriate content as shown in f'1. By using it in tl, we succeeded in lowering the hydration rate, and the content of each element was 0.00 for In.
5-05% by weight, Sr or 0.005-f), 2ffl
Amount %, l\1. One or more fl of Ca, Mg
It is appropriate that + be 0.005 to 0.2% by weight.

As described above, the present invention achieves 1. They discovered that the corrosion resistance of the sub-t1) alloy used in the ', + peaks was improved by 11%, and by determining the appropriate content, they realized an Elfti+ alnoly battery with low pollution and excellent practical performance. In addition, in the example, a battery using a zinc hydrate negative electrode was explained, but in an open air battery or a sealed zinc-alkaline battery equipped with a hydrogen absorption mechanism, the permissible amount of hydrogen gas generated is relatively small. Therefore, when applying the present invention to such cases, it is possible to reduce the water rate even further, and in some cases, it can be carried out with the water being made anhydrous.

Effects of the Invention As described above, the present invention can reduce the hydration rate of negative (MoA j1), and reduce the pollution of A)F+Alnoly battery by 1! It is extremely effective.

[Brief explanation of drawings]

The figure is a partially sectional side view of a button-shaped silver oxide battery used in an example of the present invention. 2...Zinc negative (ton 1,1...leverator, 5...acid 1hijl i'rIton.

Claims (1)

[Claims] 0.005 to 0.5% by weight of indium, 0.005 to 0.2% by weight of strontium, and 0.005 to 0.5% of at least one of aluminum, calcium, and magnesium.
A zinc alkaline battery using a zinc alloy containing 2% by weight as the negative electrode active material.