JPH03210765A - Manufacturing method for button batteries - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in a method for manufacturing a button-shaped battery having a positive electrode containing a metal oxide as an active material.

BACKGROUND ART FIG. 4 shows a cross-sectional shape of a conventional primary-molded positive electrode mixture, and FIG. 5 shows an example of a cross-sectional view of a conventional button-shaped battery. This will be explained below according to the drawings.

1 is a positive electrode mixture, 2 is a positive electrode case, 4 is a positive electrode ring, and 5 is a negative electrode. The button type battery uses an alkaline electrolyte, zinc as the negative electrode active material, and metal oxide as the positive electrode active material.

The manufacturing process will be briefly described below.

First, silver oxide and mercury oxide are used as positive electrode active materials.

Metal oxides such as manganese dioxide are used alone or in combination, and mixed with conductive additives such as graphite.

These mixed powders are pressure molded into a cylindrical shape (primary molding) to obtain a positive electrode mixture 1.

Next, a positive electrode ring 4 having an inverted cross section is attached to the upper edge of the positive electrode mixture 1, and further inserted into a positive electrode case 2 having a cylindrical shape with a bottom.

Positive electrode case assembled in this way 2. In order to bring the positive electrode ring 4 and the positive electrode mixture 1 into close contact with each other, secondary molding is performed under pressure. In this way, a positive electrode is constructed.

This positive electrode and a negative electrode filled with zinc are combined via a separator and sealed under pressure to assemble a button battery.

Problems to be Solved by the Invention The purpose of secondary molding the three parts, the positive electrode case, the positive electrode ring, and the positive electrode mixture described in the prior art, to bring them into close contact is to bring the three parts, the positive electrode case and the positive electrode mixture into close contact, The goal is to maintain good current collection.

For the above reasons, the positive electrode ring is originally not necessary for the electrical characteristics of the battery. Also, from a cost perspective and for simplifying the process, it would be effective if something could be done.

However, when only the positive electrode case and the positive electrode mixture are pressure molded, the following problems occur.

The problem is that particles of the positive electrode mixture occur around the circumference of the positive electrode case. FIG. 6 shows a schematic diagram of the case where only the positive electrode mixture and the positive electrode case are secondary molded.

This will be explained below according to the drawings.

1 is a positive electrode mixture, 2 is a positive electrode case, and 3 is a press mold.

FIG. 6(a) shows the initial state of pressurization, in which the pressurizing force is applied downward to the positive electrode mixture 1, and the positive electrode mixture 1 is pressed against the bottom of the positive electrode case 2. Then, a diametrical force is generated, which spreads outward and comes into close contact with the inner peripheral surface of the positive electrode case 2 .

FIG. 6(b) shows the positive electrode mixture 1 in a further pressurized state.
The zero circle edge enters the gap between the positive electrode case 2 and the pressurizing mold 3 with upward force. Particularly, the upper corner portion of the positive electrode mixture 1 is easily destroyed.

FIG. 6(C) shows the state at the end of the secondary molding, with a gap of the positive electrode mixture 1 being formed in the gap between the positive electrode case 2 and the pressurizing mold 3. In order to perform secondary molding so that no cracks are formed,
It would be better to make the clearance between the inner diameter of the positive electrode case 2 and the outer diameter of the pressurizing mold 3 zero, but this is impossible. In order to manufacture stably, the inner diameter of the positive electrode case 2 and the pressure mold 3 must be
The dimensional difference with the outer diameter must be at least 0.2- or more.

This debris may fall into the process during battery assembly and cause trouble in the process, or may become interposed between battery sealing members and cause battery leakage.

Therefore, an object of the present invention is to solve the problem of generation of paris when secondary molding a positive electrode mixture and a positive electrode case without a positive electrode ring.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention chamfers the corner of at least one end face of a positive electrode mixture that is primarily molded into a cylindrical shape, and furthermore, the dimension of the chamfer in the thickness direction However, the method is to perform secondary molding in a shape that is equal to or larger than the thickness of the positive electrode mixture that is reduced by secondary molding.

Effects According to the method of the present invention described above, since the upper corner of the positive electrode mixture is chamfered, the material at the upper corner of the positive electrode mixture is destroyed during secondary molding, causing damage to the positive electrode case and the pressurizing mold. This eliminates the possibility of the particles entering the gaps between the holes and forming a gap.

Furthermore, the chamfered part of the positive electrode mixture becomes a retention area for the positive electrode mixture that escapes upward during secondary molding, and prevents it from going further up and entering the gap between the positive electrode case and the pressurizing mold. ,
It has the effect of preventing the formation of paris.

Embodiment FIG. 1 shows an embodiment of the present invention in which a cathode mixture was prepared by using a cathode mixture that was primarily molded into a cylindrical shape and chamfered the corners of the end face.
It is a schematic diagram at the time of next molding.

1 is a positive electrode mixture, 2 is a positive electrode case, and 3 is a press mold.

As a specific example, IEC product number LR44, which has a battery outer diameter of 11.6 mm and a total battery height of 5.4 mm, will be described.

The inner diameter of the positive electrode case 2 is 11.0 mm, and the outer diameter of the secondary mold 3 is 10.50 mm.

Primary molding, weight of positive electrode mixture 1 is 650cm, outer diameter is φ10
．． 8-1 The thickness of the positive electrode mixture after the 2nd molding was fixed at 2.30 m, respectively.

Under the above conditions, the presence or absence of fringing after the secondary molding was confirmed when the thickness of the primary molding mixture 1 and the dimensions of the chamfer (thickness direction) were changed. Note that the chamfering was performed only on one end face, and the angle was 45°.

Table 1 shows the results.

(Left below) As can be seen from Table 1, when chamfering is not applied, cracks occur in all cases. If there is no outbreak of Paris.

FIG. 2 shows a cross-sectional view of a battery assembled using the chamfered positive electrode mixture of the present invention. 1 is a positive electrode mixture, 2 is a positive electrode case, and 5 is a negative electrode.

As can be seen from a comparison with the conventional battery shown in FIG. 5, there is no positive electrode ring 4.

In this example, only one end face of the primary molded positive electrode mixture was chamfered at an angle of 45°, but other chamfers may be used. FIG. 3 shows several cross-sectional shapes of chamfered positive electrode mixtures.

FIGS. 3(a) and 3(b) show cases where the corner of one end face is chamfered, and FIGS. 3(c) and 3(d) show cases where the corners of both end faces are chamfered. The cross-sectional shape of the chamfered portion may be linear or curved, but the larger the volume of the chamfered portion, the higher the anti-friction effect is.

There are two methods for chamfering: a method in which the primary mold is pressurized and pressure molded into a chamfered shape, and a method in which the positive electrode mixture that has been primarily molded into a cylindrical shape is post-processed and chamfered.
No matter which method you choose, the effect of preventing Paris remains the same. However, processability.

From the standpoint of mass production, it is preferable to process a mold and perform pressure molding all at once.

Further, the angle between the chamfer and the end face is preferably between 30° and 60°, and more preferably 45°.

Effects of the Invention As described above, according to the present invention, when secondary molding a positive electrode mixture in a positive electrode case, an effect can be obtained in that generation of paris can be prevented even without using a positive electrode ring.

Furthermore, since there is no need to use a positive electrode ring, (1) manufacturing costs are reduced.

■ Leads to process simplification.

■ Since the amount of positive electrode mixture can be increased, it is possible to increase battery capacity.

There is also this effect.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram of an embodiment of the present invention in which a positive electrode mixture is primarily molded into a cylindrical shape and the positive electrode mixture is subjected to secondary molding using a positive electrode mixture with chamfered end corners. , FIG. 2 is a cross-sectional view of a battery assembled using the chamfered positive electrode mixture of the present invention, FIG. 3 is a cross-sectional view of the chamfered positive electrode mixture of the present invention, and FIG. 4 is a cross-sectional view of a battery assembled using the chamfered positive electrode mixture of the present invention. Figure 5 is a cross-sectional view of a conventional battery without chamfering, Figure 6 is a schematic diagram of secondary molding of a positive electrode mixture and a positive electrode case without conventional chamfering. . 1... Positive electrode mixture, 2... Positive electrode case,
3... Pressure mold, 4... Positive electrode ring,
5... Negative electrode, 6... Separator, 7.
...Impregnating material, 8...Sealing gasket, 9.
...Sealing board.

Claims (2)

[Claims] (1) A step of primary molding the positive electrode mixture powder into a cylindrical shape;
In a method for manufacturing a button battery, the method includes the step of inserting the next molded positive electrode mixture into a cylindrical positive electrode case with a bottom and further secondary molding. 1. A method for producing a button-shaped battery, which comprises performing secondary molding using a chemical agent. (2) The button shape according to claim 1, wherein the dimension in the thickness direction of the chamfered portion of the primary molded positive electrode mixture is equal to or greater than the thickness dimension reduced by pressure during secondary molding. Battery manufacturing method.