JPH10154509A - Silver oxide battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an adding quantity of conductive auxiliaries, enhance density of a positive electrode mix and the ratio of an active material, realize large capacity of a battery, and improve a self-discharge characteristic by using flake-shaped graphite having a very wide plane as the conductive auxiliaries to a positive electrode active material. SOLUTION: Fig. is a cross-sectional drawing of a silver oxide battery. A positive electrode mixture 2 on which an adding quantity of graphite is set to 2%, a negative electrode mixture 4, electrolyte and a separator 3, are filled in a prescribed procedure in a positive electrode can 1, a negative electrode can 5 and a gasket 6 which become a vessel. The edge of the positive electrode can 1 is calked, and a battery is constituted. At this point, flake-shaped graphite on which a thickness is 0.5 to 9μm and an average diameter of a plane is 50t o 150μm, is used as the conductive auxiliaries of the positive electrode mix 2. A silver oxide on which an average particle diameter is 0.1 to 5μm may be used as a main positive electrode active material. Since density of the positive electrode mixture and the ratio of an active material are high, large electric capacity can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the capacity and self-discharge characteristics of a silver oxide battery.

[0002]

2. Description of the Related Art Silver oxide, which is a main active material of a silver oxide battery, has poor electric conductivity and thus requires a conductive auxiliary. Conventionally, scale-like graphite having an average particle size of about 5 μm has been used as the above-mentioned conductive auxiliary agent, and some of them use graphite having a slightly larger particle diameter of 10 to 50 μm.
(See, for example, Japanese Patent Publication No. Sho 61-22422) Conventionally, the amount of the conductive additive to be added was about 4 to 10% by weight based on the active material. The addition amount of the conductive additive greatly affects the amount of the active ingredient per weight of the positive electrode mixture and the molding density, and the smaller the amount, the higher the molding density of the positive electrode mixture and the ratio of the amount of the active ingredient are large. .
That is, the smaller the amount of the conductive auxiliary agent, the more the active material can be filled in the same volume can. As a means for reducing the amount, methods such as enlarging the particle size of silver oxide have been adopted (for example, see JP-B-57-5342).

[0003]

As described above, in the prior art, the amount of the conductive additive cannot be sufficiently reduced, and particularly, the silver oxide has a particle size produced by a conventional method. In a certain range of 0.1 to 5 μm, there is a problem that it is necessary to add a particularly large amount of the conductive assistant. Increasing the particle size of silver oxide has the disadvantage of increasing costs.

[0004]

In order to solve the above problems, the present invention uses flaky graphite having a very wide flat surface as a conductive additive for a positive electrode active material. The addition amount is 0.5 to 3% by weight based on the positive electrode active material.
, Significantly reduced compared to the past. In the present invention, the required functions can be imparted to the silver oxide having an average particle size of 0.1 to 5 μm, which is produced by a usual method, by the above-mentioned addition amount.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, flaky graphite having a thickness of 0.5 to 9 μm and a plane average diameter of 50 to 150 μm is used as a conductive auxiliary for a positive electrode active material. The mixture is mixed until it is sufficiently uniform with the positive electrode active material to be formed, pelletized, and used as a positive electrode mixture.

[0006] Even if manganese dioxide is added as an auxiliary active material of the positive electrode, the same effectiveness is exhibited. Fill the positive electrode mixture pellets of the previous operation together with the negative electrode mixture containing granular Zn as the main active material, electrolyte solution, and separator into the positive electrode can, gasket and negative electrode can, and seal the mouth of the positive electrode can by caulking And
Completed as a battery.

The restricted range of the size and shape of the graphite of the present invention depends on the production capacity of the graphite itself. If the range exceeds this range, it becomes difficult to produce the graphite. At present, the graphite has substantial effectiveness. do not do. In terms of thickness, it is possible to produce a material having a thickness of more than 9 μm, but as the thickness increases, the amount of graphite must be increased, and in order to maintain the range of the weight ratio of the present invention. Is preferably 5 μm or less in thickness.

[0008] The proportion of graphite in the positive electrode mixture is 0.5%.
%, The processing powder adheres to the mold at the time of molding into pellets, and usually causes a phenomenon called galling of the mold, making molding difficult. When the ratio of graphite in the positive electrode mixture exceeds 3%, the difference from the prior art is reduced and the advantage of the present invention is reduced. Therefore, in the present invention, it is appropriate that the ratio of graphite in the positive electrode mixture is 0.5 to 3%.

[0009]

【Example】

(Example 1) Powder of silver oxide having a mean particle size of 0.1 to 5 µm, which is referred to as finely divided silver oxide, and having an average particle diameter of 0.1 to 5 µm, manganese dioxide as an auxiliary active material, and the above-mentioned thickness of 0.1 µm. 5-
9 μm, graphite having a plane average diameter of 50 to 150 μm was mixed using a mixer. The weight ratio of graphite to the total weight of the mixture is five levels of 0.5, 1, 2, 3, and 5. This mixed powder was molded by a molding machine at a molding pressure of about 5.5 t / cm 2 to obtain pellets having an outer diameter of 6.4 mm and a thickness of 0.8 mm.

[0010] The above-mentioned pellet and a pellet using graphite conventionally used were sandwiched between Au-plated terminals on the surface of a flat plate, and the resistance value between the terminals was measured with a contact load of 50 g. Table 1 shows the measurement results.

[0011]

[Table 1]

As a result, the unmeasurable pellets have poor current-voltage characteristics of the battery immediately after production and cannot be used. From the stage where the resistance of the pellet is several kilohms, the initial electrical characteristics of the battery are slightly low, but with the progress of discharge, silver with good conductivity is generated and the lead is easily removed, so the usable range is include. It can be seen that the pellets of the present invention are all included in the usable range.

Example 2 A silver oxide battery SR626SW of the present invention was manufactured by the following procedure. FIG. 1 is a sectional view showing the outline. Among the pellets of Example 1 described above, those having a graphite addition amount of 2% were used as the positive electrode mixture 2, and the negative electrode mixture 4,
The electrolytic solution and the separator 3 were filled in the container, the positive electrode can 1, the negative electrode can 5, and the gasket 6 according to a predetermined procedure, and the edge of the positive electrode can was caulked to obtain a battery. In the figure, the electrolyte is not indicated, but is diffused throughout the inside.

The capacity of the battery of the present invention and the capacity of a conventional battery and the capacity after storage in an environment of 60 ° C. for 20 days were compared. Table 2 shows the results. The number of tests is six each, and the values in the table are the average values.

[0015]

[Table 2]

[0016]

The silver oxide battery constructed as described above has the following features.
Since the density of the positive electrode mixture and the ratio of the active material are high, a larger electric capacity can be provided as compared with a conventional one having the same internal volume. The amount of carbon, which is a conductive additive, is related to self-discharge as shown in, for example, Japanese Patent Publication No. 61-22422, and the smaller the amount, the better the storage rate. It is clear from the examples that the present invention is more excellent in the capacity and the self-discharge characteristic than the conventional one.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an outline of a silver oxide battery according to an embodiment of the present invention.

[Explanation of symbols]

 1 Positive electrode can 2 Positive electrode mixture 3 Separator 4 Negative electrode mixture 5 Negative electrode can 6 Gasket

Continuation of the front page (72) Inventor Masahiro Ito 5-30-1, Nishitaga, Taihaku-ku, Sendai-shi, Miyagi SII Micro Parts Co., Ltd.

Claims (2)

[Claims] 1. A positive electrode mixture, a negative electrode mixture, an alkaline electrolyte,
A separator, a positive electrode can, a negative electrode can, and a gasket are main components, and the positive electrode mixture is flaky graphite having an average thickness of 0.5 to 9 μm and an average diameter on a wide surface side of 50 to 150 μm. A silver oxide battery characterized by being added and mixed in a weight ratio of 0.5 to 3% based on the weight of the silver oxide battery. 2. The silver oxide battery according to claim 1, wherein silver oxide having an average particle size of 0.1 to 5 μm is mainly used as a positive electrode active material.