JPS58225581A - Button-type air cell - Google Patents

Abstract

PURPOSE:To obtain a button-type air cell having high capacity and high reliability by restricting the ratio of the U-shaped folded part to the total height (a) of a sealing plate to a specified value. CONSTITUTION:An air hole is perforated in the bottom of a positive case, 1, and a water-repellent film and a positive catalyst layer are placed in the positive case 1. A folded part is provided in the periphery of a sealing plate 8 which contains a negative active material to which an insulating ring is attached. In a battery sealed by inwardly curling the periphery of the positive case 1 after the positive case 1 and the sealing plate 8 are attached to one another, the height (b) of the folded part of the sealing plate 8 is restricted to 2/5-1/10 of its total height (a). As the height (b) increase, influence on the copper layer contained in the sealing plate 8 increases. However, if the sealing plate 8 has no folded part (b=0), although the appearance is excellent, continuous gas generation is observed from the end of the plate 8 in a gas generation test. In addition, it is observed that the out of roundness of the plate 8 improves and the liquid leakage resistance of the battery enhances as the height (b) decreases. Therefore, the ratio (b/a) of the folded part to the total height of the plate 8 is preferred to be 2/5-1/10.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a button-type air battery.

Conventional configurations and their problems A button-type pneumatic battery is a battery that has recently been attracting attention as a power source for hearing aids. This battery uses oxygen as the positive electrode active material, zinc as the negative electrode active material, and alkaline aqueous solution as the electrolyte, and the discharge reaction is as shown in the following equation.

Zn + 1/202 → Zn.

Moreover, its capacity depends on the absolute filling amount of the negative electrode.

Therefore, in order to increase the capacity, it is important to increase the internal volume of the sealing plate that houses the negative electrode active material zinc and the electrolyte as much as possible. The thickness of the positive electrode catalyst layer of a button-type air battery is approximately the same as that of a conventional button-type battery, and therefore, it is possible to increase the height of the sealing plate by the thinner thickness. The internal volume can also be increased to about 1.5 times that of conventional batteries, such as mercury batteries.

However, as the internal volume increases, the sealing plate also becomes taller. For example, R44 type (diameter 11.6cm, height 5.4m)
For 7 batteries, the ratio of sealing plate height/sealing plate diameter is 0.3.
0, whereas that of a button-type air battery is 0.4.
It is 0. In this way, since the sealing plate becomes higher, (1
) The processing technology for finding the seal to obtain the sealing plate becomes difficult. (2) The copper layer on the inner surface of the sealing plate is unusually easily damaged. (3
) It is expensive in terms of cost. (4) There were problems such as poor roundness. For this reason, in the manufacturing method using the deep drawing method, gas is more likely to be generated from the inner surface of the sealing plate.

As a countermeasure to this problem, a sealing plate shape completely different from that of conventional button-type batteries was considered.

That is, it is a sealing plate without a folded portion. This is an attempt to further increase the internal volume by removing the folded portion.

However, since the material of the sealing plate is generally a three-layer clad plate of nickel/iron/copper, the end face of the sealing plate structure described above is exposed, and when a battery is constructed, the electrolyte may leak onto the end face of the sealing plate. It was observed that the nickel layer penetrated, and gas generation was particularly significant from the nickel layer. Gold plating and other treatments were considered to suppress this gas generation, but no significant effect could be expected.

OBJECTS OF THE INVENTION An object of the present invention is to provide a highly reliable button-type air cell with high capacity by obtaining a sealing plate that does not generate gas using conventional sealing plate manufacturing technology.

In other words, in the present invention, as shown in FIG. 1, the ratio b/a of the height b of the U-shaped folded portion to the total height a of the sealing plate is 7s-
*Regulated by AQ. When the conventional sealing plate is shaped as shown in FIG. 2, the sealing height is high as described above, making it extremely difficult to squeeze the sealing plate. Also, when looking at the inner copper layer of the sealing plate, small scratches were found during processing.

In some cases, it was confirmed that the copper layer had peeled off from the clad plate. The following table shows the above b/a: 415, 315.2
We prototyped 100 each of six types of sealing plates: 15, 115, 1/10, and 0 shown in Fig. 3, and injected a small amount of electrolyte consisting of zinc and KOH aqueous solution into the sealing plates to separate them from the copper layer. The results of observing the gas generation situation with a magnifying glass are shown below.

In addition, the X mark in the table indicates continuous gas generation,
Δ indicates continuity but gradually decreased, ○
The mark indicates only the initial stage and no continuity.

That is, it can be seen that the characteristics of the sealing plate vary significantly depending on the height b of the folded portion. From the results in the table, the height of the folded part b
The higher the value, the greater the influence on the cupronickel layer of the sealing plate. However, although the sealing plate b=Q without folding had a good appearance, continuous gas was observed from the end portion in the gas generation test. It was also found that the lower the height b of the folded portion, the better the roundness and the better the leakage resistance. Therefore,
Height of the folded part relative to the total height of the sealing plate b/a Id-2
It can be said that 75-1.%+o is preferable.

DESCRIPTION OF EMBODIMENTS Hereinafter, as an example of the present invention, R44 size (diameter 11.
This will be explained using a button-type air cell with a diameter of 6.4 m (height: 6.4 m) as an example.

FIG. 4 is a half-sectional view of the battery, and in the figure, 1 is a positive electrode case with an air hole 2 formed at the bottom. 3 is air diffusion paper,
4 is water repellent mainly made of polytetrafluoroethylene, 5 is manganese dioxide 2 acetylene black, activated carbon and poly 4
This is a positive electrode catalyst layer in which a positive electrode catalyst mixture containing fluorinated ethylene as a main component is applied to a current collector. 6 is a separator and a liquid-containing layer, 7 is an insulating ring, 8 is a sealing plate having a U-shaped folded part 8a at the edge of 71, 9 is a zinc negative electrode active material, and 1o is a protective ring made of nylon, polyethylene, etc. The main purpose of this is to prevent a short circuit between the upper end of the positive electrode case 1 and the shoulder of the sealing plate, and 011, which is fixed to the case and the sealing plate by means of adhesive, is a sticker paper.

In actual sealing, the side surface of the sealing plate 8 is compressed by the case 1 via the end d of the folded portion 8a and the insulating ring 7 to improve the degree of adhesion.

Effects of the Invention Structures using each of the sealing plates shown in FIGS. 1 to 3 were evaluated.

Due to the high height of the folded part of the sealing plate with the configuration shown in Figure 2, scratches were observed on the copper layer on the inner surface of the sealing plate during the squeezing process. There is continuous gas generation. Therefore, the seal paper blocking the air holes is peeled off by the gas, and the inside of the battery is connected to the outside. As a result, as the battery self-discharges, the open circuit voltage during storage is 1.
．． 26V, 1.370-1.469V
It becomes higher and the variation becomes larger. Therefore, it is not preferable to have a high total height of the sealing plate and a high folded portion.

The structure shown in Figure 3 has the advantage that the internal volume of the sealing plate is small because there is no folded part, but since the end face of the cladding plate is exposed, continuous gas generation phenomenon occurs when a battery is constructed, which is undesirable. .

In the sealing plate configuration shown in Figure 1, the above-mentioned problems are not observed, the binding process is easy, the initial static characteristics and storage characteristics are stable, and a highly reliable battery can be obtained. .

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of a sealing plate used in a button-type air cell according to an embodiment of the present invention, FIGS. 2 and 3 are half-sectional views of a conventional sealing plate, and FIG. 4 is a half-sectional view of a conventional sealing plate. FIG. 5 is a half-sectional view of the button-type air battery in the example, and FIG. 5 is a half-sectional view showing the sealed state. 1...Positive electrode case, 2...Air hole, 4
... Water repellent film, 5 ... Positive electrode catalyst layer, 7.
...Insulation ring, 8...Sealing plate, 8a.
...Folded part, 9...Negative electrode active material, a
...Total height of the sealing plate, b...Height of the folded part. Name of agent Patent attorney Toshio Nakao and 1 other person Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A positive electrode case with an air hole in the bottom and a water-repellent membrane and a positive electrode catalyst layer inside is fitted with a sealing plate with a folded part on the periphery and an insulating ring with a built-in negative electrode active material. The button-type air battery is a battery in which the periphery of the positive electrode case is bent inward and sealed, and the height of the folded part of the sealing plate is regulated to V5 to 1/10 of the total height of the sealing plate.