JPH07335227A - Alkaline battery - Google Patents

Abstract

PURPOSE:To improve for the deterioration of discharging property after preserving battery, and materialize stable shelf life and discharging property by restricting the concentration of potassium hydroxide aqueous solution being the alkaline electrolyte in a battery after constitution of a battery. CONSTITUTION:A positive electrode coupling agent 2 consisting of manganese dioxide and a graphite material is put in a metallic case 1, and a separator 3 is inserted, and then a gel-shaped negative electrode 4 is injected into the separator 3. Next, a negative electrode collector 6 united with a resin plug 5 and a bottom plate 7 is plugged into a gel-shaped negative electrode to form an element battery. In this case, using potassium hydroxide aqueous solution where lead oxide is added to an electrolyte, the concentration of the potassium hydroxide electrolyte in the battery after constitution of the battery is changed to 32.0, 34.0, 36.0, 38.0, 40.0, 42.0, and 44.0wt.%. Hereby, stable shelf life and discharging property can be materialized by reducing the deterioration of the shelf like of the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery, and more particularly to improvement of an alkaline electrolyte containing potassium hydroxide as a main component.

[0002]

2. Description of the Related Art In order to secure storage characteristics, which is one of the important characteristics of alkaline batteries, various conditions are taken into consideration, and today, 30-40% by weight is generally used as an alkaline electrolyte in the production of alkaline batteries. % Potassium hydroxide aqueous solution is used. (For example, Japanese Patent Publication No. 3-66781)

[0003]

Zinc, which is the negative electrode active material for alkaline batteries, is oxidized and passivated during storage, so that the discharge characteristics after storage of the battery deteriorate. Therefore, in order to suppress the passivation of zinc and ensure the storage characteristics of the battery, generally, a potassium hydroxide aqueous solution of 30 to 40% by weight is used as an alkaline electrolyte at the time of production,
A zinc fluoride powder in which the zinc surface was amalgamated with mercury was used. However, with the recent increase in environmental conservation movements, it has been necessary to eliminate mercury contained in zinc powder, which is the negative electrode of batteries. When mercury, which has an effect of suppressing passivation of zinc, is removed from the zinc powder, the zinc powder is passivated, which causes a phenomenon that the storage characteristics of the battery are deteriorated.

An object of the present invention is to provide an alkaline battery having excellent discharge characteristics even after storage by regulating the concentration of an aqueous solution of potassium hydroxide which is an alkaline electrolyte in the battery after the battery is constructed. And

[0005]

According to the present invention, there is provided a negative electrode containing zinc as an active material, a positive electrode containing manganese dioxide as an active material, and an electrolytic solution containing an alkaline aqueous solution containing potassium hydroxide as a main component. And the weight concentration ratio of potassium hydroxide to water in the electrolytic solution in the battery after the battery is formed is 3
It is set from 6.0: 64.0 to 42.0: 58.0.

[0006]

The present invention improves the deterioration of the discharge characteristics after storage of the battery by regulating the concentration of potassium hydroxide which is the alkaline electrolyte in the battery after the battery is constructed.

In order to obtain excellent discharge characteristics, it is important to use an alkaline electrolyte having a high specific electric conductivity. When an aqueous solution of potassium hydroxide is used as the electrolytic solution, it exhibits the highest specific conductivity when the alkali concentration is about 30% by weight, and the specific conductivity is low at both higher and lower alkali concentrations. Become. Therefore, the concentration of the aqueous potassium hydroxide solution used in the alkaline battery is optimally about 30% by weight, which is the alkaline concentration that maximizes the specific conductivity, in terms of discharge characteristics. On the other hand, in order to secure the storage characteristics of the battery, it is necessary to suppress the passivation of zinc. It is necessary to suppress the passivation of zinc by making the alkali concentration higher than the alkali concentration having the highest specific conductivity. Thus, it is important that the optimum concentration of the aqueous potassium hydroxide solution is different for each of the discharge characteristic and the storage characteristic and that both characteristics are satisfied.

The alkaline concentration of the alkaline electrolyte is lowered by being ion-adsorbed and neutralized by manganese dioxide which is a positive electrode active material and polyacrylic acid which is a gelling agent. For example, as shown in (Table 1),

[0009]

[Table 1]

Analysis of the potassium hydroxide concentration of the aqueous solution after adding electrolytic manganese dioxide to a fixed amount of potassium hydroxide aqueous solution shows that the greater the amount of electrolytic manganese dioxide added, the greater the decrease in potassium hydroxide concentration. This shows that the potassium hydroxide aqueous solution concentration after the battery is constructed changes to the low concentration side, and the alkaline electrolyte concentration in the battery after the battery is constructed depends on the electrolysis when the battery is constructed. It can be seen that it is determined by the liquid volume and the amount of substances such as manganese dioxide and gelling agent that reduce the concentration of the electrolyte. Therefore, it is understood that regulating the alkali concentration after the constitution is more effective in securing the characteristics of the battery than regulating the concentration of the electrolyte solution before the constitution of the battery.

Conventionally, a potassium hydroxide aqueous solution of 30 to 40% by weight has been generally used as an alkaline electrolyte at the time of manufacture, but the potassium hydroxide concentration after the battery is constructed as described above decreases. Therefore, the upper limit of the alkali concentration is less than 36.0% by weight. In the case of using zinc fluoride powder added with mercury as the negative electrode zinc, mercury suppresses the passivation of zinc powder even if an aqueous potassium hydroxide solution of 30 to 40 wt% is used as the alkaline electrolyte at the time of production. Therefore, sufficient storage characteristics could be secured, but the storage characteristics are deteriorated with the unconstrained zinc. Therefore, as a result of diligent examination of the concentration of the alkaline electrolyte after forming the battery, when the potassium hydroxide concentration is 36.0% by weight or more, the passivation of the zinc powder is suppressed and the storage properties are excellent. I found out.

On the other hand, if the potassium hydroxide concentration is higher than 42.0% by weight, the specific electric conductivity of the electrolytic solution is lowered, and the camera and strobe discharge characteristics, which are the features of alkaline batteries, are deteriorated, which is not preferable.

[0013]

EXAMPLE FIG. 1 is a half sectional view of a cylindrical alkaline battery LR6 used in an example of the present invention.

A positive electrode mixture 2 made of manganese dioxide and a graphite material is put in a metal case 1, a separator 3 is inserted, and then a gelled negative electrode 4 is injected into the separator 3. Resin sealing body 5
The negative electrode current collector 6 in which the bottom plate 7 and the bottom plate 7 are integrated is inserted into the gelled negative electrode to form a unit cell.

The concentration of the potassium hydroxide electrolyte in the battery after the battery was constructed by using an aqueous solution of potassium hydroxide in which zinc oxide was added to the electrolyte was 32.0, 34.0, 36.0,
We made AA alkaline batteries with 38.0, 40.0, 42.0, and 44.0% by weight, and the initial and 60 ℃
For a month storage battery, a 3.9Ω continuous discharge test (final voltage 0.9V) was performed. The test results are shown in (Table 2).

[0016]

[Table 2]

It has been found that the storage characteristics are excellent when the alkali concentration after forming the battery in this way is 36.0% by weight or more.

Next, the AA alkaline battery prepared above was used for 1.8 Ω (15
Second ON / 45 second OFF) Intermittent discharge test (end voltage 0.9
V) was performed. The test results are shown in (Table 3).

[0019]

[Table 3]

From these results, it was found that if the alkali concentration after the battery was constructed was 42.0% by weight or less, a discharge performance almost equal to 36.0% by weight, which was excellent in storage characteristics, could be obtained.

As described above, by setting the concentration of potassium hydroxide in the battery after the battery is formed to 36.0% by weight to 42.0% by weight, excellent storage characteristics can be secured. The electrolytic solution is mainly composed of potassium hydroxide, and even if it contains zinc ions by adding alkali metal ions such as sodium and lithium or zinc oxide, the same preservation as described above is performed. It was found that an excellent effect was obtained.

[0022]

As described above, by using the present invention, it is possible to improve the deterioration of the storage characteristics of the battery and provide an alkaline battery having stable storage characteristics and discharge characteristics.

[Brief description of drawings]

FIG. 1 is an AA alkaline battery L according to an embodiment of the present invention.
Longitudinal section of R6

[Explanation of symbols]

 1 Metal Case 2 Positive Electrode Mixture 3 Separator 4 Negative Electrode 5 Resin Sealing Body 6 Negative Current Collector 7 Bottom Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Asaoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A battery comprising a negative electrode containing zinc as an active material, a positive electrode containing manganese dioxide as an active material, and an electrolytic solution containing an alkaline aqueous solution containing potassium hydroxide as a main component. The weight concentration% ratio of potassium hydroxide to water in the electrolytic solution in the battery of No. 4 was 36.0: 64.0 to 42.
Alkaline battery that is 0: 58.0.