JPH07109776B2 - Button type air battery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a button type air battery, and more particularly to a dimensional relationship between the thickness of an air diffusion paper and the depth of a recess for storing the air diffusion paper.

Configuration of Conventional Example and its Problems The configuration of a typical conventional button type air battery is as shown in FIG. That is, the air supply hole 2 is provided in the bottom of the positive electrode case 1, the air diffusion paper 3 is arranged in the recess of the bottom of the case, and the fluororesin water repellent film 4, the positive electrode catalyst layer 5, and the separator 6 are sequentially stacked thereon. It is housed and the positive electrode side assembly is completed.

On the other hand, in the negative electrode side assembly, a sealing plate 8 having an insulating sealing ring 7 attached to its periphery is filled with zinc hydride powder as a negative electrode active material 9 together with an alkaline electrolyte.

The positive electrode case 1 is obtained by fitting the positive electrode assembly and the negative electrode assembly together.
The opening side of is bent inward to form one button-type air battery.

The air diffusion paper here is used for uniformly diffusing air entering from the air supply hole 2 of the positive electrode case into the positive electrode catalyst layer and for preventing deformation of the fluororesin water repellent film and the positive electrode catalyst layer. It was being done. Therefore, it has been considered that the thickness of the air diffusion paper is preferably equivalent to the depth of the concave portion at the bottom of the positive electrode case in terms of battery performance.

However, due to the expansion of the negative electrode active material due to the discharge, the water-repellent film is pushed toward the air diffusion paper side, and the electrolytic solution consisting of the alkaline aqueous solution is also pushed, passing through the positive electrode catalyst layer and the water repellent film, and wetting the air diffusion paper. Will end up. The air diffusion paper wet with the electrolytic solution prevents diffusion of air entering from the air supply hole 2 opened at the bottom of the positive electrode case into the positive electrode catalyst layer, and reduces the active points of the positive electrode catalyst layer. As a result, there is a problem that the battery discharge performance is significantly deteriorated, and furthermore, if the battery is left with a load still connected after the discharge, liquid leakage occurs from the air supply hole.

OBJECT OF THE INVENTION The present invention solves the problems of the conventional example, prevents the electrolytic solution from passing through the water-repellent film, does not deteriorate the activation ability of the positive electrode catalyst layer for a long period of time, and discharges. The purpose is to prevent liquid leakage from the air supply hole even if the device is left with the load still connected.

In order to achieve the above-mentioned object, the present invention has a thickness of the air diffusion paper.
The dimensional relationship between h ₁ and the depth h ₂ of its recess is 0.05 mm ≦
The feature is that h ₂ −h ₁ ≦ 0.2 mm.

According to the present invention as described above, even when the electrolytic solution is pressurized by the gas pressure generated by the discharge of the negative electrode active material, the electrolytic solution is prevented from passing through the water-repellent film, and the positive electrode catalyst layer is kept active for a long time. It is possible to eliminate the liquid leakage from the air supply hole even if the battery is left without being deteriorated and the load is still connected after the discharge.

In order to prevent the occurrence of leakage in this type of battery,
Although the method of reducing the negative electrode active material and the electrolytic solution is simple, but since the battery capacity is unnecessarily reduced, the present inventors have used the same battery size, the thickness of the air diffusion paper, and the recess for storing the diffusion paper. By examining the dimensional relationship of the depth of
The inventors invented a method for extracting the maximum capacity.

Description of Embodiments Hereinafter, an embodiment of the present invention will be described with reference to FIG.
The R44 type will be described.

First, the air supply hole 2 is provided at the bottom of the positive electrode case 1, and the air diffusion paper 3 is arranged in the recess 10 for accommodating the air diffusion paper at the bottom.
The fluororesin water-repellent film 4 is placed on it. Then, a positive electrode catalyst layer 5 filled with a catalyst material in which activated carbon, acetylene black, and polyterafluoroethylene as a binder are mixed is arranged on the nickel net. Finally, the separator 6 is inserted into the positive electrode case 1 to complete the positive electrode side assembly.

The depth h ₂ of the recess 10 of the positive electrode case 1, the larger the h _2, the volume is reduced to be filled in the negative electrode active material.

Table 1 shows the relationship between h ₂ and the negative electrode volume when the sealing plate thickness is 0.25 mm, the side thickness of the sealing ring 7 is 0.4 mm, and the positive electrode case 1 has a thickness of 0.3 mm.

In order to maximize the volume of the negative electrode, the smaller h ₂ is, the better. However, in forming the recess, the positive electrode case plate thickness is important for case processing.

In other words, it is known that it is difficult for mass production to make h ₂ shallower than the thickness of the case.

Since the positive electrode case is generally used with a plate thickness of 0.2 to 0.3 mm, the depth h ₂ of the recess of the positive electrode case must be considered to be 0.2 to 0.3 mm.

Increasing the plate thickness to 0.3 mm or more is meaningless because it results in unnecessarily reducing the battery volume.

Therefore, in the range of 0.2 ≤ h ₂ ≤ 0.3 mm, the thickness of the air diffusion paper is set to h ₁ and the relationship between h ₁ and the depth h _{2 of the} recess is shown in Table-
It was examined as in 2.

Figure 3 shows the results of trial production of 18 types of batteries shown in Table-2 using R44 size batteries and continuous discharge of 250Ω at a temperature of 20 ° C. It should be noted that the discharge duration is an average value of n = 6 and the leakage rate is n =
It is an average value of 10.

h ₂ dimensional relationships -h ₁ has 0.05mm or 0.2mm or less preferably from the top of the anti-leak.

The thickness h ₁ of the air diffusion paper 3 and the recess 10 at the bottom of the positive electrode case 1.
When the difference from the depth h ₂ is less than 0.05 mm, the water repellent film 4 is pushed toward the air diffusion paper 3 side by the expansion of the negative electrode active material 9 due to the discharge, and the electrolytic solution is also pushed and passes through the water repellent film 4. Then, the air diffusing paper 3 is impregnated, the discharge performance is deteriorated, and liquid leakage occurs from the air supply hole 2.

When h ₂ −h ₁ > 0.2 mm, the water-repellent film 4 is deformed at the time of sealing, and cracks are easily formed in the circumferential circle of the case step, and after discharging, air is supplied if left unloaded. Leakage occurs from the holes.

The negative electrode assembly is the same as the above-mentioned insulating sealing ring 7.
Then, the sealing plate 8 having the peripheral edge fitted with was filled with zinc hydride, which is the negative electrode active material 9, together with the alkaline electrolyte to complete the process.

EFFECTS OF THE INVENTION As is clear from the above results, according to the present invention, leakage of liquid due to discharge can be suppressed and the maximum battery capacity in the same size can be secured.

[Brief description of drawings]

FIG. 1 is a half sectional view of a button type air battery in a conventional example,
FIG. 2 is a half sectional view of a button type air battery in an embodiment of the present invention, and FIG. 3 is a dimensional difference between the depth h _{2 of the} recess and the thickness h _{1 of the} diffusion paper, discharge duration and leakage rate. It is a figure which shows the relationship of. 1 ... Positive electrode case, 2 ... Air supply hole, 3 ... Air diffusion paper, 4 ... Water repellent film, 5 ... Catalyst layer, 6 ... Separator,
7 ...... insulating sealing ring, 8 ...... sealing plate, 9 ...... anode active material, 10 ...... air diffusion paper storage recess, h ₁ ...... diffusion sheet thickness, h ₂ ...... depth of the recess.

Claims (1)

[Claims] 1. A positive electrode case having an air supply hole at the bottom and a concave portion for accommodating the air diffusion paper, the air diffusion paper,
An air battery in which a water-repellent film and a positive electrode catalyst layer are sequentially stacked and accommodated, and the dimensional relationship between the thickness h ₁ of the air diffusion paper and the depth h _{2 of the} recess is 0.05 ≦ h ₂ −h ₁ ≦ 0.2 mm. And button type air battery.