JPS60189161A - Flat battery - Google Patents

Abstract

PURPOSE:To obtain a very stable flat-type battery with high capacity by providing a groove corresponding to the thickness of the separator right over a stage section formed on the middle area of the inner surface of the negative can. CONSTITUTION:A groove 14 corresponding to the thickness of a separator 11 is formed on the inner circumference surface of a negative can 7 located right over its stage section 7c. When a negative mixture 12 and electrolyte 13 are placed in the negative can 7 and then the separator 11 is installed over the mixture 12 and the electrolyte 13, the separator 11 encroaches upon the groove 14 thereby being supported. As a result, even when a pushing jig is moved upward after the separator 11 is pushed into the separator 11, the separator 11 does not follow the pushing jig. Therefore, sufficient compressive force is maintained thereby preventing any ions from passing through the periphery 11a of the separator 11. Accordingly it is possible to maintain a high capacity by preventing any short circuits between a positive active material 10 and a negative active material 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flat battery used in small devices such as wristwatches, calculators, and cameras.

An example of a conventional battery of this type will be explained with reference to FIG.

FIG. 1 is a vertical cross-sectional half-sectional view of a conventional flat battery. The battery case of this battery is composed of a cup-shaped anode can 1 and a cap-shaped cathode can 2 that is assembled into the anode can 1 via a gasket 3. Inside this battery case, a cathode active material 5 and an anode active material 6 impregnated with an electrolytic solution and facing each other with a separator 4 in between are enclosed.

In a battery having such a configuration, the gasket 13 provided between the anode can 1 and the cathode can 2 is connected to the anode can 1.
The periphery of the upper opening 1a of the gasket 3 is compressed by crimping inward, and the compression reaction force of the casket 3 brings the gasket 3 into close contact with the anode can 1 or the cathode can 2 to prevent liquid leakage. Therefore, in order to improve the leakage resistance of this battery, it was necessary to increase the thickness of the gasket 3 and increase the compression reaction force of the gasket 3.

However, when the thickness of the gasket 3 is increased, the volume occupied by the gasket 3 relative to the total battery volume increases, and in order to supply the same discharge capacity without reducing the capacity of the contents, it is necessary to increase the battery gauge itself. It was needed.

In addition, when the amount of compression of the gasket 3 is increased in order to improve leakage resistance, the force that compresses the gasket 3 moves the negative electrode can 20 force part 2a inward, increasing the internal pressure of the battery can. At the same time, this increases the creep deterioration rate of the gasket 3, making the compression reaction force stronger and causing liquid leakage.

In order to eliminate the drawbacks of the above-mentioned conventional example, the inventors have already proposed a flat battery as shown in Figure 2, which does not use anything similar to a conventional gasket and has a higher capacity and improved leakage resistance. This is the time when it is being done.

Next, FIG. 2 will be explained.

In Fig. 2, 7 is a cathode can made of metal with a mouth-like cross-sectional shape, and consists of a bottomed part 7a and a cylindrical rising part 7b rising vertically above the outer periphery of the bottomed part 7a. It is configured. A stepped portion 7c is provided in the middle of the inner wall of the rising portion 7b, and the surface of the rising portion 7b is coated with an insulating film 7d. Reference numeral 8 denotes an anode can made of a metal material and having a mouth-shaped cross section, and is generally composed of an upper plane 8a and a cylindrical part 8b bent vertically downward from the outer periphery of the upper plane 8a. Then, by shrink-fitting the cylindrical portion 8b of the anode can 80 to the outer peripheral surface of the rising portion 7b of the cathode can 7, the can 8.7 is inserted through the insulating coating 7d.
The comrades are electrically isolated and watertightly sorbed.

9 is a cathode active material impregnated with an electrolytic solution, and 1o is a tablet-shaped anode active material. Reference numeral 11 has an outer peripheral portion 11a separated from the cathode active material 9 and the anode active material 10 by a separator placed on the stepped portion 7c of the cathode can 70 to prevent electrical short circuits.

In this way, the flat battery shown in Figure 2 eliminates the need for a gasket because the gasket is not compressed by the tip of the anode can stand on the curled part of the cathode can, and therefore the content is almost equal to that of the gasket. Since the product can be increased, it is possible to increase the capacity, and since the cans are sealed together over almost the entire surface of the rising part 7b and the cylindrical part 8b, through the insulation coating 7d, by shrink fitting. , the adhesion strength is increased and the leakage resistance is also improved.

However, during the experiment with the battery structure shown in Figure 2 above, it was found that the intended purpose was fully satisfied in terms of leakage resistance.
'I got good results, but sometimes I got a battery with low capacity.

The inventors of the present invention focused on the above results and conducted repeated research to investigate the cause. As shown in FIG. Next, the separator 11 is placed, the anode active material 10 is placed on top of the separator 11, and the anode can 8 is shrink-fitted to the cathode can 7 to form a battery. It may stop at 1 in the middle of the round (・), and in that state, place the anode active material 10 and place the anode can 8.
If it is shrink-fitted into the cathode can 7, the total thickness will increase, and the compressive force of the separator outer periphery 11a through the anode active material 10 will be insufficient, and the cathode mixture 1 will be compressed at the separator outer periphery 11a.
It has been found that ions in the electrolyte 13 and the anode active material 10 pass through to the anode active material 10 and cause a short circuit, resulting in a decrease in capacity.

Furthermore, as shown in FIGS. 4(a) and 4(b), when the separator 11 is inserted, when the central part of the separator 11 comes into contact with the electrolytic solution 13, it absorbs the electrolytic solution 13 and expands, so that the separator 11 does not curl. At this time, the separator 11 is not located at the center of the cathode can 7, and the separator outer periphery 1
It has also been found that due to the narrower holding width λ of 1a, passage of the electrolyte 13 to the anode active material IO at the separator outer peripheral portion tia cannot be blocked, causing a short circuit and a decrease in capacity.

In order to solve these problems, we conducted further experimental research, and as a result, we were able to obtain a flat battery with the above battery structure that is resistant to leakage and has a more stable and higher capacity.

The gist of the above invention is as described in the claims of the above patent.

Hereinafter, embodiments of the flat battery of the present invention will be described with reference to the drawings.

Note that the same parts as in FIG. 2 are designated by the same reference numerals (description will be omitted).

FIG. 5 is a vertical cross-sectional half-mounted view of the flat battery of the present invention. In FIG. 5, reference numeral 14 denotes a convex groove corresponding to the thickness of the separator 11, which is partially provided on the circumference of the inner wall directly above the stepped portion 7c of the cathode can 70.

By providing the convex groove 14 corresponding to the thickness of the separator 11 on the inner wall directly above the stepped portion 7c of the cathode can 70, the cathode can 7 can be assembled into When inserting the agent 12 and the electrolyte 13 and inserting the separator 11 thereon, if the separator 1 is pushed to the position where it should be placed (above the step 7C), the separator outer periphery 11a corresponds to the thickness of the separator 11. The separator 1 enters and is held in the convex groove 14 having a width A, and even if the pushing jig for the separator 11 rises after pushing is completed, the separator 1
1 gets stuck in the pushing jig and the ko-shichi that comes up disappears. Therefore, air is not trapped under the separator 11, and even after assembly is completed, the total thickness does not increase and the compressive force of the separator outer circumference 11a is sufficiently maintained, so ions do not pass through the separator outer circumference 11a and the anode is activated. A short circuit between the material 10 and the cathode active material 9 does not occur, and high capacity can be maintained.

Furthermore, even if the central part of the separator comes into contact with the electrolytic solution 13 and expands, and a curling force is generated in the separator 11, the groove part 14 prevents deformation, so the separator 11 is kept flat, and the separator 11 is moved to the cathode can 7. Since it does not shift from the center of the separator, the holding width of the separator outer circumferential portion 11a on the stepped portion 7C of the cathode can 70 is secured, the electrolytic solution 13 does not pass through to the anode active material 10, no short circuit occurs, and the capacity is increased. can be kept.

@Figure 7 is a detailed diagram of a main part of another embodiment of the present invention. 7th
In the figure, reference numeral 15 denotes a concave groove corresponding to the thickness of the separator 11 provided all around the inner wall immediately above the stepped portion 7C of the cathode can 70.

By providing the concave groove portion 15 all around the circumference in FIG. 7, the entire circumference of the separator outer circumferential portion 11a is held in the concave groove portion 15 during assembly, so that the effect described in FIG. 6 becomes more reliable. .

As described in detail above, according to the present invention, it is possible to provide an extremely stable flat battery with a high capacity without impairing leakage resistance.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional half-cut view of a conventional flat battery, FIG. 2 is a vertical cross-sectional half-cut diagram of a flat battery having the basic structure of the flat battery of the present invention, and FIGS. 3 and 4 are FIG. 5 is a detailed view of the main part of the separator assembly of the flat battery shown in FIG. 5, a vertical cross-sectional half-sectional view of the flat battery of the present invention, and FIG. , Figure 7 is the 6th
FIG. 7 is a detailed view of a main part of another example of the groove shown in the figure. 1.8... Anode can, 2,7... Cathode can, 5.10.
...Anode active material, 6,9...Cathode active material, 4゜11
・@Middle sehalator, 7a, 8a...bottomed part, 7b. 8b...Cylindrical part, 7c...Step part, 7d...Insulating coating, 11a...Separator outer periphery, 12...Cathode mixture, 13...Electrolyte solution, 14.15. ...Groove II Figure 1 (D-Mashi υf city t To-ichi' c!-:: (self proboscis=)4
．． '+,i'+ Agency Director General Manabu Shiga, 14 Nori Electric Oil 3, Supplementary 11 Person 4? +Ii+I': Number of inventions increased by instruction 11 ゛・Spontaneous 5, sleeve 11 None 6, subject of sleeve 11

Claims (1)

[Claims] A cathode can has a white cross-sectional shape, has a stepped part in the middle of the inner wall of its cylindrical rising part, and coats the surface of the raised part with an insulating film, and a cathode can has a white cross-sectional shape and has a stepped part in the middle of the inner wall of the raised part. An anode can shrink-fitted to the outer peripheral surface of the upright part of the cathode can, and a separator T whose outer peripheral part is placed on the stepped part, thereby enclosing and sealing the divided cathode active material and anode active material. 1. A flat type battery, characterized in that a groove portion corresponding to the thickness of the separator is provided on the inner wall directly above the stepped portion provided in the middle of the inner wall of the cathode can.