JPH0785422B2 - Button type air battery - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a button type air battery, and more specifically, it has a long discharge duration and leaks even after being left under a load after discharge. About button type air battery without a problem.

[Technical Background of the Invention and its Problems] Various types of air batteries are known as air batteries that use oxygen in the air as a positive electrode active material, and one of them has a button-type structure. is there.

The structure of a conventional general button type air battery is as shown in FIG. That is, an air diffusion paper 3, a water repellent film 4 made of fluororesin, a positive electrode catalyst layer 5, and a separator 6 are laminated in this order on the bottom of a positive electrode case 1 having an opening on the top and an air hole 2 on the bottom. Stored and stored
On the other hand, the cap 8 also serving as a negative electrode terminal is mixed with the opening of the positive electrode case 1 through the gasket 7, and the periphery of the opening of the positive electrode case 1 is bent inward to seal the battery. Then, the space defined by the positive electrode case 1 and the cap 8 is filled with a negative electrode mixture 9 containing zinc as a negative electrode substance.

In such a button type air battery, the positive electrode case 1 and the bottom surface partially form a recess 1a so as to project downward as shown in FIG. 2 in order to enhance the structural strength of the battery itself. Is common. The air diffusion paper 3 is housed in the concave portion 1a and has a function of uniformly diffusing the air invading the inside of the cell through the air supply holes 2 into the positive electrode catalyst layer 5, and is laminated on the diffusion paper 3. It also has a function of preventing geometric deformation of the water repellent film 4 and the positive electrode catalyst layer 5 thus formed.

However, conventionally, no consideration has been given to the relationship between the diameter of the air diffusing paper 3 and the inner diameter of the recess 1a for housing the diffusing paper 3, so that the following inconvenience often occurs. That is, the water-repellent film 4 is pressed downward by the pressure applied when mixing the cap and the gas pressure generated by the discharge of the negative electrode mixture 9, and as a result, as shown in FIG. The water-repellent film 4 may enter and deform in the gap 10 between the periphery of the diffusion paper 3 and the recess 1a, and cracks may occur in the water-repellent film. At this time, the electrolytic solution leaks from the cracks of the water-repellent film 4 and wets the air diffusion paper 3.

The diffusion paper 3 wet with the electrolytic solution hinders the diffusion of air into the positive electrode catalyst layer 5, so that the activity of the positive electrode catalyst layer 5 is reduced, and the discharge characteristics of the battery itself are significantly deteriorated. Furthermore, if the battery is left under a load after the discharge, there is a problem that liquid leaks from the air supply hole 2.

The amount of the negative electrode mixture and the amount of the electrolytic solution used may be simply reduced in order to prevent liquid leakage, but in that case, the capacity of the battery is reduced, which is not preferable. Furthermore, such a method is not a solution because it deforms the water-repellent film described above.

[Object of the Invention] The present invention solves the conventional problems described above, has a long discharge duration without impairing the capacity of the battery, and prevents liquid leakage due to deformation of the water-repellent film. Button type air battery.

[Summary of the Invention] In order to achieve the above object, the inventors of the present invention have conducted intensive studies mainly focusing on the shape and structure of a button type air battery, and as a result, have found that the diameter of the air diffusion paper and the inner diameter of the recess of the positive electrode case are different from each other. In the present invention, the optimum range as will be described later was found in the dimensional relationship, and for the first time, the present invention was completed by defining the relationship between the two dimensions.

That is, the button type air battery of the present invention is a button type air battery having a positive electrode case in which an air diffusion paper, a water repellent film and a positive electrode catalyst layer are stacked and housed in this order at the bottom, The inner diameter (L) of the positive electrode case and the diameter (l) of the air diffusion paper are in a relationship of 0.5 mm ≦ (L−1) ≦ 1 mm.

Hereinafter, the present invention will be further described with reference to FIG.
FIG. 1 shows the basic structure of the button type air battery of the present invention, and the same reference numerals as those in FIG. 2 represent the same constituent elements. The feature of the present invention is that the dimensional difference (L-1) between the inner diameter L of the concave portion 1a of the positive electrode case 1 and the diameter 1 of the air diffusion paper 3 housed in the concave portion 1a is regulated within the range of 0.5 to 1 mm. The structure, shape, dimensions, etc. of the other parts are not particularly limited.

When the above-mentioned dimensional difference (L-1) exceeds 1 mm, as described above, the gas generated at the time of discharging the battery presses the water-repellent film 4 downward to generate cracks, which deteriorates the discharge characteristics and causes liquid leakage. It is not preferable because it causes Furthermore, the water repellent film 4 may be deformed and cracked by an external force applied downward when the battery is sealed.

On the other hand, when (L-1) is less than 0.5 mm, the discharge characteristics are deteriorated particularly at low resistance, and liquid leakage may occur, which is not preferable.

[Examples of the Invention] Examples 1 and 2 and Comparative Examples 1 to 4 As an example, a PR44 type button type air battery as shown in Fig. 1 was manufactured. First, the air diffusion paper 3 is housed in the concave portion 1a having an inner diameter of 9 mm formed in the bottom of the positive electrode case 1, and the water repellent film 4, which is made of fluororesin, the positive electrode catalyst layer 5, and the separator 6 are sequentially stacked on the air diffusion paper 3 and stored. did. As the positive electrode catalyst layer 5, a catalyst material obtained by mixing activated carbon and polytetrafluoroethylene powder with nickel net pressure bonded was used.

Then, using a zinc powder as a negative electrode active material, a cap 8 filled with a gelled negative electrode mixture 9 obtained by mixing the zinc powder with a gelling agent of sodium polyacrylate and an alkaline electrolyte is opened in the positive electrode case 1. Then, the button-type air battery was completed by fitting the same to the above via a gasket 7 and further bending the upper opening peripheral edge of the positive electrode case 1 inward to seal the whole.

In this manner, 10 batteries were manufactured, each having the dimension difference (L-1) between the inner diameter L of the recess 1a of the positive electrode case 1 and the diameter 1 of the air diffusion paper 3 set to the indicated length. Temperature 20
Discharge was continuously performed at 250C or an external load of 250Ω or 60Ω, and the discharge duration, discharge capacity and liquid leakage rate were measured. The values and the ratio of 60Ω discharge capacity to 250Ω discharge capacity are shown in the table. In the table, the discharge duration and the discharge capacity are the average values of the six batteries, and the liquid leakage rate is the ratio of the liquid leaked out of the ten batteries.

[Effects of the Invention] As is clear from the above description, in the button type air battery of the present invention, since the dimension of the gap between the air diffusion paper and the positive electrode case is properly set, it is of course necessary to discharge the battery when assembling the battery. Even at times, the occurrence of cracks due to the deformation of the water-repellent film is prevented,
Not only discharge characteristics with high resistance but also discharge characteristics with low resistance are excellent, and there is no risk of liquid leakage. Therefore, its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a basic structure of a button type air battery of the present invention, and FIG. 2 is a vertical sectional view showing a structure of a conventional button type air battery. 1 ... Positive electrode case, 1a ... Recessed portion, 2 ... Air supply hole, 3 ... Air diffusion paper, 4 ... Water repellent film, 5 ... Catalyst layer, 9 ... Negative electrode mixture.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Nakamura 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Ltd. (72) Inventor Hitomi Sato 3-4 Minamishinagawa, Shinagawa-ku, Tokyo No. 10 in Toshiba Battery Co., Ltd. (56) Reference JP-A-59-215679 (JP, A) Actually developed S61-79462 (JP, U)

Claims (1)

[Claims] 1. A button type air battery comprising a positive electrode case having a bottom portion in which an air diffusion paper, a water repellent film and a positive electrode catalyst layer are stacked and housed in this order, wherein the inner diameter (L of the positive electrode case around the air diffusion paper is L). ) And the diameter (1) of the air diffusion paper have a relationship of 0.5 mm ≦ (L−1) ≦ 1 mm.