JPH09199187A - Button type air-zinc battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an air electrode and a separator from being stretched to a negative electrode and conduct a stable large-current discharge by invariably pressing the air electrode with a pressing member having a flat face and an inverted T-shaped cross section. SOLUTION: The opening section of a positive electrode case 8 is mechanically caulked inward and sealed via an insulating gasket 3 to prevent the leakage of a built-in electrolyte in this button type air-zinc battery. Since an air electrode 5 is invariably pressed by a pressing member 11, the air electrode 5 and a separator 4 can be prevented from being stretched to a negative electrode 2 side by the caulking pressing force when the battery is sealed. Such problems can be resolved that the electrolyte permeates between the catalyst layer of the air electrode 5 and a water-repellent film when the battery is stored and discharged and the discharge maintaining voltage is reduce in a large- current discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a button type zinc-air battery, and more particularly to preventing the air electrode thereof from protruding to the negative electrode side.

[0002]

2. Description of the Related Art A button-type zinc-air battery is a battery developed as an alternative power source for a mercury battery. It uses oxygen instead of mercury oxide for its positive electrode. It has low mercury, is environmentally friendly, has a large electric capacity and is lightweight Due to the characteristics described above, the demand for the power source for hearing aids and pagers is rapidly increasing. Further, further growth is expected in the future due to miniaturization and portable electronic devices.

The zinc-air battery is a battery using oxygen in the air as the positive electrode active material and zinc as the negative electrode active material. The structure of a button type zinc-air battery is shown in FIG.

Reference numeral 1 is a negative electrode case, 2 is a negative electrode made of zinc and an alkaline electrolyte, 3 is a ring-shaped insulating gasket, 4 is positive, and a separator for preventing short between the negative electrodes and 5 is air. It is composed of a catalyst layer and a water repellent film at the pole. 6 is a water-repellent film for preventing oxygen supply to the air electrode 5 and leakage of the electrolyte solution to the outside of the battery, 7 is an air diffusion paper for uniformly diffusing air, and 8 is a positive electrode case, Air diffusion paper 7 on the bottom
Has a convex portion so that the air diffusion function is not deteriorated by being compressed. Reference numeral 9 is an air hole provided on the bottom surface of the positive electrode case, and 10 is a sealing paper for sealing the air hole 9 when not in use to block the ingress of air and prevent deterioration of the battery due to self-discharge. is there.

[0005]

In this button type zinc-air battery, in order to prevent leakage of the built-in electrolyte, the opening of the positive electrode case 8 is mechanically caulked and sealed inward through an insulating gasket. It is closed and closed. At the time of this caulking sealing, a mechanical load is applied to the bottom surface of the gasket and the air electrode 5
Also, a force acts such that the separator 4 projects toward the negative electrode 2 side. Therefore, when the battery is stored and discharged, the electrolytic solution permeates between the catalyst layer and the water repellent film of the air electrode 5 to reduce the reaction area of the air electrode, making it impossible to discharge a large amount of current and decreasing the discharge sustaining voltage. Was given.

The present invention is intended to solve such a problem by preventing the above-mentioned air electrode 5 and separator 4 from protruding to the negative electrode 2, and thereby the catalyst layer of the air electrode 5 during battery storage and discharge. It is an object of the present invention to provide a button-type zinc-air battery capable of preventing a reaction area of an air electrode from decreasing due to permeation of an electrolytic solution between a water-repellent film and a water-repellent film and enabling stable large-current discharge.

[0007]

In order to achieve the above object, the present invention is configured such that the air electrode 5 is constantly pressurized by a pressure member having a flat surface and having an inverted T-shaped cross section. is there.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION With the above structure, the air electrode 5 is constantly pressed by the pressure member, so that the air electrode 5 and the separator 4 are stretched toward the negative electrode 2 side due to the caulking pressure when the battery is sealed. It is possible to prevent the action of taking out. Therefore, it is possible to solve the problem that the electrolyte sustaining solution permeates between the catalyst layer of the air electrode 5 and the water repellent film during storage and discharge of the battery and the discharge sustaining voltage decreases during high current discharge.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

A button type zinc air battery PR1662 (diameter 16.0 mm, height 6.2 mm) was used. FIG. 1 shows the structure of a button type zinc-air battery of the present invention. Reference numeral 11 is a pressing member having an inverted T-shaped cross section, and urethane foam was used in the battery of this example. The flat surface 11a has a diameter of 8.0 mm and a thickness of 1.0 mm, and the cylindrical portion 11b has a diameter of 1.0 mm and a height of 4.2 mm. The porosity is 50%.

Next, using the battery of the present invention and the comparative battery shown in FIG. 2, a discharge test of 20 mA continuous discharge as a large current discharge and 4 mA as a small current discharge at a temperature of 20 ° C. and a humidity of 60% was carried out with an initial battery. went. In addition, temperature 20 ℃, humidity 60
The same discharge test was performed on the battery stored in the environment of 1% for 1 month.

The results are shown in FIGS. Fig. 3 shows the result of the large current discharge in the initial stage, Fig. 4 shows the result of the small current discharge in the early stage, Fig. 5 shows the result of the large current discharge after one month storage, and Fig. 6 shows the result of the small current discharge after one month discharge. is there.

As is apparent from FIGS. 3 and 4, the battery of the present invention initially maintained a small current discharge characteristic equivalent to that of the comparative battery, and at the time of large current discharge, the comparative battery had a sustain voltage in the middle discharging stage. In contrast, the battery of the present invention does not have a voltage drop until the end of discharge. This is because the air electrode 5 and the separator 4 were prevented from protruding to the negative electrode by disposing the pressure member in the negative electrode.
This is because the electrolytic solution was prevented from penetrating between the catalyst layer and the water-repellent film and reducing the reaction area of the air electrode. As confirmation, the battery was disassembled and observed between the catalyst layer of the air electrode 5 and the water-repellent film before and after the discharge. There wasn't.
Further, after the end of discharge, in the comparative battery, the electrolytic solution penetrated between the catalyst layer of the air electrode 5 and the water-repellent film, whereas in the battery of the present invention, penetration of the electrolytic solution was not observed.

Further, as apparent from FIGS. 5 and 6,
After being stored for 1 month, the battery of the present invention maintained the same small current discharge characteristics as the comparative battery, and the sustain voltage of the comparative battery decreased from the initial discharge in the large current discharge, whereas The voltage of the battery does not decrease until the end of discharge. This is due to the same effect as in the initial case. As a confirmation, the battery was disassembled before and after the discharge, and the space between the catalyst layer of the air electrode 5 and the water repellent film was observed. While the electrolytic solution permeated during the period, no permeation of the electrolytic solution was observed before and after discharging in the battery of the present invention.

In the embodiment of the present invention, urethane foam is used as the pressing member having an inverted T-shaped cross section, but the same effect can be obtained even when brass is used as the pressing member.

[0016]

As described above, according to the present invention, the cross-section reverse T
By disposing the letter-shaped pressure member, the air electrode 5 and the separator 4 are prevented from protruding toward the negative electrode 2 side, and the catalyst layer and the water repellent film of the air electrode 5 can be formed during battery storage and discharge. It is possible to prevent the electrolytic solution from penetrating in the meantime, solve the problem that the discharge sustaining voltage is lowered, and obtain a button-type zinc-air battery that exhibits excellent discharge characteristics in both large current and small current discharge.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a button type zinc-air battery of the present invention.

FIG. 2 is a sectional view showing the structure of a conventional button-type zinc-air battery.

FIG. 3 is a diagram showing a discharge curve during initial high-current discharge.

FIG. 4 is a diagram showing a discharge curve during initial small-current discharge.

[Fig. 5] Discharge curve during high-current discharge after storage for 1 month
Figure showing

[Fig. 6] Discharge curve during small current discharge after storage for 1 month
Figure showing

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode case 2 Negative electrode 3 Gasket 4 Separator 5 Air electrode 6 Water repellent film 7 Air diffusion paper 8 Positive electrode case 9 Air holes 10 Seal paper 11 Pressure member with inverted T-shaped cross section 11a Pressurization Flat surface of member 11b Cylindrical part of pressure member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumio Oo 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A button-air zinc battery having an air electrode using oxygen as an active material, a zinc negative electrode housed in a sealing plate, a separator and an alkaline electrolyte interposed between both electrodes.
A button type zinc-air battery in which the air electrode is pressed by a pressing member having an inverted T-shaped cross section having a flat surface. 2. A button type air zinc battery, wherein the pressing member having an inverted T-shaped cross section according to claim 1 is made of a material such as urethane foam and brass that is stable in the negative electrode active material.