JP2002373711A - Button type air-zinc battery and its method of manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a button type air-zinc battery enhancing leak preventive characteristics when it is stored for a long period. SOLUTION: The button type air-zinc battery has a cup-shaped positive electrode can serving also as a positive electrode current collector, a positive electrode catalyst layer, a cap-shaped negative electrode current collector with folded ends, a negative electrode working material, and a ring-shaped gasket. The outside diameter A of the portion of the battery where the catalyst layer is located, the outside diameter B of the battery at the lowermost end position of the negative electrode current collector, the outside diameter C of the negative electrode current collector at the end folding position of the negative electrode current collector, the outside diameter D of the negative electrode current collector at the folded end position of the negative electrode current collector, the wall thickness m of the gasket at the C position, and the wall thickness n of the gasket at the D position meet the relationships: A>B; C>D; and m=n. The leak preventive characteristic of the battery can thus be enhanced without causing deflection of the positive electrode catalyst layer. The battery can be manufactured by sealing it using a crimper shaped so that a portion below a round part R corresponding to a calked part is tapered or rounded, and so that the inside diameter of its middle part is smaller than the inside diameter of its lower end part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a button-type zinc-air battery having improved long-term storage characteristics.

[0002]

2. Description of the Related Art In a zinc-air battery, since oxygen in the atmosphere is used as a positive electrode active material, there is no need to pack the positive electrode active material into the battery. For batteries of the same size, more zinc is used as the negative electrode active material. Packing is possible, and there is an advantage that a large capacity can be obtained as compared with an alkaline manganese battery or a silver oxide battery.

The general structure of a zinc-air battery will be briefly described below. That is, the zinc-air battery was formed by sequentially laminating an air diffusion layer, a water-repellent layer, and a cathode catalyst layer on the bottom of a cathode can having an air hole, and loading a gelled zinc anode on the cathode catalyst layer via a separator. The negative electrode can is placed, and the positive electrode can and the negative electrode can are fitted to each other by crimping the positive electrode can inward through an insulating gasket, thereby forming a sealed port.

[0004] By the way, in the conventional button type battery, a method of increasing the crimp pressure or increasing the compression ratio of the packing after crimping is generally used in order to enhance the liquid leakage resistance during long-term storage. Such storage leakage countermeasures
It is applied to button type alkaline batteries and button type silver oxide batteries.

However, in the case of the same button-type battery, in the case of a button-type air zinc battery, when the crimping is performed in such a manner as to increase the crimp pressure and the packing compression ratio, the positive electrode catalyst layer (air electrode) is warped, thereby causing the zinc And the discharge characteristics are deteriorated, and the rate of occurrence of over-discharge leakage is increased. For this reason, the upper limit of the crimp pressure is restricted, and there has been a problem that a sufficient crimp pressure cannot be applied.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems and has been made in a button-type zinc-air battery to prevent leakage of liquid during long-term storage while preventing deformation of the air electrode due to crimping. The purpose is to improve the characteristics.

[0007]

That is, the present invention provides a cap-shaped negative electrode current collector having a cathode catalyst layer for reducing oxygen in a cup-shaped positive electrode can also serving as a positive electrode current collector and having an end turned back. In a button-type zinc-air battery having a structure in which a negative electrode active material is loaded in a body and a ring-shaped gasket is interposed between the positive electrode can and the negative electrode current collector, the two are insulated from each other. Is the outer diameter of the battery at the portion where A is located, B is the outer diameter of the battery at the lowermost position of the negative electrode current collector, C is the outer diameter of the negative electrode current collector at the end folded position of the negative electrode current collector, A> B, C> D, m = n, where D is the outer diameter of the negative electrode current collector at the position, m is the gasket thickness at the C position, and n is the gasket thickness at the D position. Features.

The above dimensions A, B, C, D, m,
n is shown in FIG. Further, the present invention relates to the method of manufacturing the button-type zinc-air battery, wherein the lower portion of the curved portion R corresponding to the caulking portion is tapered or R-shaped, and the inner diameter of the intermediate portion is smaller than the inner diameter of the lower end portion. The battery is sealed using a crimper having the following shape.

Conventionally, the crimper used was a straight type having the same inner diameter from the lower end to the vicinity of the curved portion R. However, in the present invention, such a portion is formed into a tapered shape or an R portion is provided so that the catalyst at the time of crimping can be formed. The sealing strength is enhanced by preventing warpage of the layer and utilizing repulsion caused by deformation of the cap-shaped negative electrode current collector. As a result, it was found that the relationship of A> B, C> D was established among A, B, C, and D of the above dimensions, and in that case, the rate of occurrence of liquid leakage during long-term storage was reduced.

Conventionally, the thickness of the gasket is increased to increase the compressive force. In this case, the gasket thicknesses m and n tend to satisfy m <n. It was found that the leakage resistance was improved by increasing the sealing strength without depending on the gasket and by reducing the thickness of the gasket so that m = n.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A button-type zinc-air battery PR44P (diameter 11.54 mm, total height 5.25 mm) shown in FIG. 1 was produced.
That is, a catalyst layer (air electrode) 5, a water-repellent film 6, and a diffusion paper 7 for taking in oxygen in the atmosphere into a positive electrode can 2 having an air hole 8 are provided, and a negative electrode current collector ( The negative electrode gel 9 housed in the negative electrode cap 3 is placed. The negative electrode gel is obtained by gelling an electrolytic solution and zinc powder using a gelling agent, and contains 1% mercury and 500 ppm lead as an alloy as a zinc powder, and has a particle size of 100 to 300 μm. Using. The electrolyte used was a 30% by weight aqueous solution of potassium hydroxide, and the gelling agent was polyacrylic acid. The mixing ratio of the electrolyte and the zinc powder is 250 g of the electrolyte with respect to 1 kg of the zinc powder. The filling rate of the negative electrode gel in the negative electrode container is such that the theoretical volume when all of the zinc in the negative electrode gel reacts with zinc oxide by discharging becomes 98% of the volume of the negative electrode container. Next, the crimp type used for sealing the sealing portion of the zinc-air battery will be described.

FIG. 3 is an explanatory vertical cross-sectional view of a crimp type.
According to the shape of the M portion in FIG. 3, the crimp type is classified into three types: a straight type A type, a tapered type B type, and a two-step R type C type. In the case of type A, the inner diameter of part a and c
The inner diameter of the part is the same, both are 11.52 mm, and the size of the part a is 11.52 mm in the type B, but the dimension of the part c is 11.42 mm
Thus, a taper is formed. The shape of the c-shaped part is
It is 11.52 mm and the dimension of the c portion is 11.37 mm, and R is provided in this c portion, so that R is formed in two steps as a whole.

The crimper insertion opening in the battery to be sealed is indicated by the lower line. When the battery is inserted from here and the crimper is pushed downward from above the battery, the caliber becomes narrow at the R portion of the shoulder, and the sealing portion of the positive electrode can is pressed inward and crimped. The conventional crimp type is the A type, but in the present invention, the B type and the C type are used.

(Example 1) Tape-crimp type (b type)
The battery was crimped at a crimp pressure of 220 kgf. When crimping is performed with the crimp-type R portion positioned at the sealing portion of the positive electrode can, the portion a is located at a position about 2/3 of the total height from the bottom surface of the positive electrode can, and the outer diameter of the positive electrode can to that portion is crimped. The inside diameter of the a part of the mold is regulated to 11.52 mm. Since the portion from above corresponds to a crimp-shaped M portion (tapered shape), a taper is formed in the positive electrode can, and further, R
The part comes and the end of the positive electrode can is crimped inward. As described above, when the crimp mold is removed after the sealing is crimped, the finished dimensions of the battery become as shown in FIG.
Was 11.54 mm, B was 11.54 mm, C was 10.76 mm, and D was 10.74 mm.

Example 2 The above-mentioned battery was crimped using a two-stage R crimp type (C type) with a crimp pressure of 220 kgf. In this case, although the crimp-type tapered portion M of the first embodiment is a straight line but a curved line, the substantial tightening effect is almost the same. When the crimp type is removed after crimping, as shown in Table 1, the finished dimensions of the battery are 11.54 mm for A in FIG. 2, 11.50 mm for B, 10.78 mm for C,
D was 10.72 mm.

(Conventional example) The above-described battery was crimped using a straight type crimp type (a type) with a crimp pressure of 220 kgf. Packing thickness is 0.325mm.
As shown in Table 1, the finished dimensions of the battery are as follows.
1.54 mm, B is 11.54 mm, C is 10.74 mm, and D is 10.74 mm.

(Comparative Example 1) As in the conventional example, a straight type crimp type (a type) was used, and the crimp pressure was 260 kgf.
The above battery was crimped. Packing thickness is
0.325mm. The finished dimensions of the battery are as shown in Table 1.

(Comparative Example 2) As in the conventional example, a straight type crimp type (a type) was used, and the crimp pressure was 220 kgf.
The above battery was crimped. Packing thickness is
0.275mm. The finished dimensions of the battery are as shown in Table 1.

(Comparative Example 3) Tape-crimp type (b type)
The battery was crimped at a crimp pressure of 180 kgf. Packing thickness is 0.275mm. The finished dimensions of the battery are as shown in Table 1.

Comparative Example 4 The above battery was crimped using a two-stage R-crimp type (C type) at a crimp pressure of 180 kgf. Packing thickness is 0.275mm. The finished dimensions of the battery are as shown in Table 1.

200 batteries of each of the above Examples, Comparative Examples and Conventional Examples were manufactured and subjected to an overdischarge leakage test. First, 100
250Ω in an environment with a temperature of 25 ° C and a relative humidity of 85%
Was discharged under the same load, and the battery was discharged under the same conditions for an additional 100 hours after the operating voltage reached 0.9 V, and the number of leaked batteries at that time was examined. The rate of occurrence (%) is shown in Table 2 as the rate of occurrence of overdischarge leakage.

Next, for another 100 pieces, the temperature was 60 ° C.
The batteries were stored for 60 days in a high-temperature and high-humidity environment with a relative humidity of 93% and visually inspected to determine the number of batteries that had leaked. Incidence(%)
Is shown in Table 2 as a high-temperature storage leak rate.

[0023]

[Table 1]

[0024]

[Table 2]

(Results of Battery Performance Evaluation) In the conventional example, A = B,
Since C = D and m = n, and the repulsive force of the cap does not work, the packing compression cannot be increased and the long-term storage liquid leakage characteristics are poor. In Example 1, since the taper type crimper was used, A> B, and the negative electrode cap 3 was deformed into a C shape, and C> D. Also, in the second embodiment, a two-stage R-type crimper is used, so that A> B and C> D
It became.

However, in Comparative Example 1, since the crimp pressure was higher than in the conventional example and the example, the warpage of the air electrode 5 was increased, and over-discharge leakage occurred. In addition, since the packing having the same thickness as that of the conventional example was used, the repulsion of the packing did not work effectively, and the liquid leakage resistance during long-term storage was poor. Therefore, it can be seen that increasing the crimp pressure does not necessarily improve the leakage resistance characteristics for long-term storage.

In Comparative Example 2, the packing was made thinner, so that the storage characteristics were somewhat improved as compared with the conventional example, but liquid leakage occurred. In this case, since the straight type crimper was used, the negative electrode cap was not deformed, and C> D was not satisfied, so that the repulsive force of the packing did not work.

In Comparative Example 3, a taper type crimper was used. However, since the crimping pressure was reduced, the deformation of the negative electrode cap was small, and C = D. As a result, there was no spread to the outside of the cap reverse. Compression weakened. That is, it was found that the storage leakage characteristics were lower than those of other crimping methods and methods of increasing the pressing force. Comparative Example 4 also used a two-stage R-type crimper, but it was also found that the crimp pressure was similarly low, so that the storage leakage characteristics were not good.

From the above, simply increasing the crimp pressure as a measure against liquid leakage has no effect, and A> B, C> D, m
= N, and it was found that the crimper had to be improved for that.

[0030]

According to the present invention, in a button-type zinc-air battery, the leakage resistance during long-term storage can be improved while preventing the positive electrode catalyst layer from being deformed.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a button-type zinc-air battery according to one embodiment of the present invention.

FIG. 2 shows dimension values A, B, C, D, m, and n according to the present invention.
FIG.

FIG. 3 is a diagram illustrating a crimper used in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gasket, 2 ... Positive electrode can, 3 ... Cap-shaped negative electrode current collector, 4 ... Separator, 5 ... Positive catalyst layer, 6 ... Water-repellent film, 7
... diffusion paper, 8 ... air holes, 9 ... negative electrode gel.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuichi Kikuma 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation F-term (reference) 5H011 AA17 CC06 DD15 DD26 FF03 GG02 KK01 KK03 KK04 5H032 AA01 AS03 AS11 BB10 CC01 CC04 CC11 HH01 HH04 HH06

Claims (3)

[Claims] 1. A negative electrode active material is loaded on a cap-shaped negative electrode current collector having a positive electrode catalyst layer for reducing oxygen in a cup-shaped positive electrode can also serving as a positive electrode current collector and having an end turned back. In a button-type air-zinc battery having a structure in which a ring-shaped gasket is interposed between the positive electrode can and the negative electrode current collector so that both are insulated, the outer diameter of the battery where the catalyst layer is located is reduced. A, the outer diameter of the battery at the lowermost position of the negative electrode current collector is B, the outer diameter of the negative electrode current collector at the end turning position of the negative electrode current collector is C, and the outer diameter of the negative electrode current collector at the turning end position of the negative electrode current collector is D, when the gasket thickness at the C position is m and the gasket thickness at the D position is n, A> B, C> D,
A button-type zinc-air battery, wherein m = n. 2. A method for sealing a battery using a crimper having a tapered or R-shaped portion below a curved portion R corresponding to a caulking portion and having a middle portion inner diameter smaller than a lower end portion inner diameter. The method for producing a button-type zinc-air battery according to claim 1. 3. The method according to claim 2, wherein the clip pressure is 220 kgf.