JPH08241699A - Button type alkaline battery - Google Patents

Abstract

PURPOSE: To enlarge the capacity of a negative electrode case and enhance the resistance against liquid leakage by making the negative electrode case in a cup form to contain zinc as negative electrode active material, folding back the end of the case outward in a U-shape, and thereby forming an opening in a specified shape. CONSTITUTION: A negative electrode case 1 in a cup form is equipped with an opening 1a by folding back outward so that a U-section is obtained, and using a reproducing die, deformation and swelling-out are made so that the inside diameter (b) of the central part of the case 1 becomes greater than the inside diameter (a) of the opening 1a. The case 1 is filled with zinc 4 as negative electrode and an electrolyte of alkali aqueous solution, and a gasket 2 having an L-section is fitted in the opening la, and the gap between the contacting surfaces of the gasket and case 1 is filled with a seal material so that a liquid-tight construction is accomplished. Finally this case 1 and a positive electrode case 3 are fitted together while the gasket 2 is interposed. This constitution allows enlargement of the capacity of the case 1 and enhancement of the resistance against liquid leakage. It is preferable that the outside diameter (d) of the central part of the case 1 is equal to or greater than the outside diameter (c) of the opening 1a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved button type alkaline battery using zinc as a negative electrode active material and an alkaline aqueous solution as an electrolytic solution, and more particularly to an improved button type air zinc battery.

[0002]

2. Description of the Related Art Button-type zinc-air batteries are small hearing aids,
Used in small pagers. Compared to other button-shaped batteries of the same size, zinc, which is the negative electrode active material, can be additionally filled, so that the electric capacity is large. In particular, the button-type zinc-air battery used for small hearing aids is R44 (outer diameter 11.6 mm x thickness 5.4 mm), which is about 2.1 times as much electricity as the mercury battery used for the same purpose. Has capacity. However, a small hearing aid with a large current consumption has a battery life as short as one week or less even if it is a button type zinc-air battery, and improvement of this performance has been desired.

A conventional example of the button type zinc-air battery is shown in FIG.
Described in. Reference numeral 1 denotes a negative electrode case, which is composed of a clad or a plating material made of a plurality of metal materials such that the inner surface side is a copper layer and the outer surface side is a nickel layer. Negative electrode case 1
Is processed into a cup shape having an opening 1a having a U-shaped cross section that is folded outward by pressing. The opening 1a having a U-shaped cross section has a button shape as a means for tightly adhering the extension of the copper layer on the inner surface of the sealing plate (negative electrode case) 1 to the resin gasket 2 in order to prevent electric leakage in a liquid-tight manner. It is the most commonly used means of button type alkaline batteries including zinc-air batteries. Reference numeral 3 in the drawing denotes a positive electrode case in which the negative electrode case 1 is liquid-tightly fitted and accommodated via a gasket 2.

However, as can be seen from FIG. 4, since the material of the negative electrode case 1 is duplicated on the side wall of the battery, the negative electrode zinc 4
There is a drawback that the volume for storing the is reduced. In the figure, 5 is an air hole, 6 is a diffusion paper, 7 is an air electrode, 8 is a water repellent film, and 9 is a separator.

Although efforts to reduce the material thickness of the negative electrode case 1, the gasket 2 and the positive electrode case 3 have been continued from the past in order to increase the volume for accommodating the negative electrode zinc 4, the negative electrode case 1 and the positive electrode case Material thickness of 3 is 0.1m
m or less, and the thickness of the gasket 2 is 0.15 m
It is very difficult to reduce the thickness to less than m in terms of parts processing.

In order to solve this problem and secure the capacity of the negative electrode case 1 as large as possible, a method shown in FIG. 5 was considered. The battery shown in FIG. 5 has a shape in which the opening 1 a of the negative electrode case 1 has no folded portion. In this negative electrode case 1, since the battery side wall is made of a single layer material, R4
When compared with the 4 size button type zinc-air batteries, the negative electrode case volume is increased by about 10% as compared with the battery of FIG. Incidentally, FIG.
The same members as those of the conventional example battery are denoted by the same reference numerals, and detailed description thereof is omitted.

[0007]

FIG. 6 is an enlarged view of the portion A in FIG. 5, and as shown in FIG. 6, the opening 1a of the negative electrode case 1 having no folded portion has copper 10a and stainless steel 10b. , Nickel 10c are exposed on the inner surface of the bottom of the gasket 2 having an L-shaped cross section.

When the battery is constructed, a negative electrode case 1 is filled with negative electrode zinc 4 as a negative electrode active material and an electrolytic solution. Since the surface of the particles of the negative electrode zinc 4 is coated with mercury to prevent corrosion, the surface of the copper 10a is also amalgamated by the mercury when the negative electrode case 1 is filled, and the negative electrode zinc 4 and the surface of the copper 10a have the same potential.

However, since the stainless steel 10b and the nickel 10c which are not amalgamated are exposed at the end of the negative electrode case 1, when the electrolytic solution in the battery enters and adheres, a potential difference with zinc occurs and the end of the negative electrode case 1 becomes The electrolytic solution decomposes to generate hydrogen gas.

As a result, the internal pressure of the button-type zinc-air battery rises, and the air hole 5 opened at the bottom of the positive electrode case 3.
And the boundary between the negative electrode case 1 and the gasket 2, the positive electrode case 3
The electrolyte is extruded from the boundary between the gasket 2 and the gasket 2 to cause leakage. As a countermeasure against this, an attempt was made to fill the space between the gasket 2 and the negative electrode case 1 with a resin sealing material 11 to prevent the invasion of the electrolytic solution during battery construction. But it is impossible to prevent it completely. In the initial stage of battery construction, even if the invasion of the electrolytic solution can be prevented, it gradually invades during storage of the battery, and during storage of the battery, some batteries may leak significantly.

The present invention has a stable liquid leakage resistance shown in the cross-sectional view of FIG. 4, and further has a button-shaped air zinc having a large capacity negative electrode case 1 which can be filled with the negative electrode zinc 4 shown in the cross-sectional view of FIG. The purpose is to provide a battery.

[0012]

In order to achieve this object, the button type alkaline battery of the present invention uses zinc as a negative electrode active material and an alkaline aqueous solution as an electrolytic solution, and mainly contains the negative electrode active material therein. A button-type alkaline battery in which a cup-shaped negative electrode case is liquid-tightly fitted into the positive electrode case through a gasket arranged in an opening having a U-shaped cross section formed by folding the end portion outward. Therefore, the relationship between the inner diameter dimension a of the opening and the inner diameter dimension b of the central portion of the negative electrode case is a <b.

The relationship between the outer diameter dimension c of the opening and the outer diameter dimension d of the central portion of the negative electrode case is preferably c≤d.

[0014]

By adopting this structure, the internal volume of the negative electrode case is approximately 8 in the R44 size compared to the negative electrode case 1 in FIG.
% Volume becomes large, and excellent liquid leakage resistance performance can be obtained.

[0015]

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

First, with reference to FIGS. 2 and 3, an example of manufacturing the negative electrode case used in this embodiment will be described.

Reference numeral 1 in the drawing denotes a negative electrode case. First, as shown in FIG. 2, an opening 1 having a U-shaped cross section is formed by a conventional method.
Press-mold into a cup shape with a. Next, in the process shown in FIG. 3, the outer peripheral portion of the negative electrode case 1 is fixed with a mold 21, and the negative electrode case 1 is remolded with a press mold 23 sandwiching an elastic body 22 such as urethane rubber. That is, the elastic body 22 sandwiched between the upper and lower press dies 23a and 23b forming the press die 23 is deformed and bulges outward when being pressed,
A negative electrode case 1 is obtained in which the inner diameter b of the central portion is larger than the inner diameter a of the opening. In this example, the outer diameter dimension c of the opening 1a of the negative electrode case and the outer diameter dimension d of the central portion of the negative electrode case 1 were formed to be the same.

Reference numeral 24 denotes upper and lower press dies 23a, 23.
a spring interposed between the upper and lower press dies 23a, 2
3b is returned to a predetermined position before pressing, the elastic body 22 has the same diameter as the press die 23, and the press die 23 can be taken out from the negative electrode case 1.

FIG. 1 is a cross-sectional view of a button type zinc-air battery of the present invention using the negative electrode case 1, and the construction method thereof will be described.

Reference numeral 3 in the drawing is a positive electrode case, and an air hole 5 is opened at the bottom. A diffusion paper 6 is placed on the bottom surface of the positive electrode case 3, and the diffusion paper 6 is used for the purpose of sufficiently diffusing oxygen in the air into the air electrode 7.
A non-woven fabric that is porous and mainly composed of a cellulosic material is generally used.

Next, a water repellent film 8 of polytetrafluoroethylene (PTFE) having micropores of 0.1 to 1 μm is punched out to have a diameter substantially the same as the inner diameter of the positive electrode case 3 and placed on the diffusion paper 6.

The air electrode 7 is placed on the water-repellent film 8. The air electrode 7 has a metal screen serving as a positive electrode current collector, a catalytic material such as manganese oxide and activated carbon, and the like. A conductive material such as acetylene black is mixed with PTFE dispersion, applied, dried, and punched to have the same diameter as the inner diameter of the positive electrode case 3 and placed on the water-repellent film 8.

A separator 9 is made of an ion-permeable material such as polypropylene microporous membrane or cellulose, and is used for the purpose of separating the negative electrode zinc 4 and the air electrode 7. is there.

The negative electrode case 1 is made of a resin such as nylon 66. A gasket 2 having an L-shaped cross section is fitted in an opening 1a having a U-shaped cross section, and the negative electrode zinc 4 and potassium hydroxide or sodium hydroxide are used. Is filled with the electrolyte solution. The contact surface between the gasket 2 and the negative electrode case 1 is filled with a sealing material such as sulfonated polyethylene or butyl rubber to be liquid-tight. Finally, the negative electrode case 1 and the positive electrode case 3 filled with various battery power generation materials are fitted together via a gasket 2, and the opening of the positive electrode case 3 is bent inward by a mold to form a button-shaped air zinc. The battery is completed.

Next, an invention product A according to the present embodiment, a battery B shown in FIG. 4 and a battery C shown in FIG. 5 were prototyped as R44 size button type zinc air batteries, and their electric capacities under continuous discharge of 620Ω were obtained. And a leakage resistance accelerated test under an environment of 45 ° C. and a humidity of 90% were performed for comparison. The results are shown in Table 1.

[0026]

[Table 1]

As shown in (Table 1), by adopting the constitution of the present invention, it was possible to obtain a button-type zinc-air battery having excellent leakage resistance and large electric capacity.

[0028]

As described above, according to the present invention, the opening portion of the negative electrode case has a folded portion having a U-shaped cross section formed by folding the end portion outward and is formed in a cup shape. By using the negative electrode case in which the inner diameter a of the opening of the negative electrode case and the inner diameter b of the central portion of the negative electrode case are a <b, a button type alkaline battery having a large electric capacity and excellent liquid leakage resistance is obtained. In particular, a button type zinc air battery can be obtained.

[Brief description of drawings]

FIG. 1 is a half cutaway sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a negative electrode case in the middle of a pressing process for manufacturing the negative electrode case of the present invention.

FIG. 3 is a sectional view of a pressing process for manufacturing the negative electrode case of the present invention.

FIG. 4 is a half cutaway view of an example of a conventional button type zinc-air battery.

FIG. 5 is a half cutaway view of another example of a conventional button type zinc-air battery.

FIG. 6 is an enlarged cross-sectional view of part A of FIG.

[Explanation of symbols]

 1 Negative electrode case 1a Opening 2 Gasket 3 Positive electrode case 4 Negative electrode zinc 5 Air hole 6 Diffusing paper 7 Air electrode 8 Water repellent film 9 Separator a Negative electrode case inner diameter dimension b Negative electrode case inner diameter dimension

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

Claims (2)

[Claims] 1. A cross section U formed by using zinc as a negative electrode active material, an alkaline aqueous solution as an electrolytic solution, and folding an end of a cup-shaped negative electrode case mainly accommodating the negative electrode active material outwardly. What is claimed is: 1. A button type alkaline battery which is liquid-tightly fitted in a positive electrode case through a gasket arranged in a V-shaped opening, wherein an inner diameter dimension a of the opening portion and an inner diameter dimension b of the central portion of the negative electrode case. A button-type alkaline battery with a relationship of a <b. 2. The button type alkaline battery according to claim 1, wherein the relationship between the outer diameter dimension c of the opening and the outer diameter dimension d of the central portion of the negative electrode case is c ≦ d.