JPH08162075A - Lithium battery - Google Patents

Abstract

PURPOSE: To provide a battery excellent in leakage resistance by regulating the inclination of a sealing plate opening part to the height direction of a positive electrode case before caulking and the compression ratio of a gasket to specified values. CONSTITUTION: A battery is assembled by charging a negative electrode 6, a separator 4, a positive electrode 5 and an nonaqueous electrolyte into the battery, and caulking the opening part of a positive electrode case 2 through an insulating material between the case 2 and a sealing plate 1. The inclination θof the opening part of the sealing plate 1 to the height direction of the case 2 before caulking is regulated to 0-12 deg. toward the outer diameter direction, the compression ratio of a gasket 3 between the sealing plate shoulder part 1a and the case 2 after caulking is set to 50-75%, and the compression ratio of the gasket between the sealing plate opening top end part 1b and the case 2 to 25-60%. Thus, a battery excellent in leakage resistance can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium battery in which a power generating element is liquid-tightly sealed by a positive electrode case, a sealing plate, and a gasket, and more particularly to improvement in leakage resistance.

[0002]

2. Description of the Related Art Conventionally, in an organic electrolyte type coin-type lithium battery, efforts have been made to increase the internal volume of the battery in order to increase its capacity. As one of the methods, as described in Japanese Patent Laid-Open No. 341756/1992, a sealing plate having no U-shaped folded portion on the periphery has been adopted. In a battery using this type of sealing plate, as shown in FIG. 2, the compression ratio of the gasket between the sealing plate shoulder 1a after caulking and the positive electrode case is 50 to 75.
%, The compression ratio of the gasket between the sealing plate opening front end 1b and the positive electrode case is usually caulked to be 25 to 60%.

[0003]

However, as an environmental measure required for batteries these days, it is required to improve the liquid leakage resistance in a high temperature or low temperature region. Under such a condition, the liquid leakage resistance is low. There was a problem.

The present invention solves such problems and an object thereof is to provide a lithium battery having excellent resistance to liquid leakage.

[0005]

In order to solve this problem, according to the present invention, the inclination angle θ of the sealing plate opening with respect to the height direction of the positive electrode case before caulking is 0 to 1 in the outer diameter direction.
The compression rate of the gasket between the sealing plate shoulder 1a and the positive electrode case after caulking is regulated to 2 °, and the compression rate of the gasket between the positive electrode case and the sealing plate opening front end 1b is 25 to 25%. The problem is solved by setting it to -60%.

[0006]

By using the sealing plate having the inclination angle θ as described above, it is possible to minimize the deformation of the opening of the sealing plate against the stress load when the case is crimped, and the sealing plate and the positive electrode case. A uniform pressure can be applied to the entire compressed portion of the gasket between and.

[0007]

EXAMPLES A coin type lithium manganese dioxide battery of one example of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a sealing plate which also serves as a negative electrode terminal having no U-shaped folded portion connected to the outermost periphery, and which is a gasket 3 at a portion of the sealing plate shoulder 1a.
In order to obtain a sufficient compression rate of the sealing plate shoulder 1a
Is used as a fulcrum. 2 is a positive electrode case which also serves as a positive electrode terminal, 3 is a gasket made of polyolefin resin such as polyethylene and polypropylene, 4 is a separator made of polypropylene non-woven fabric, 5 is manganese dioxide which is an active material, and conductive agent and binder such as graphite. A positive electrode 6 is formed by mixing and pressure molding, and a negative electrode 6 has a lithium metal or a lithium alloy as an active material.

The opening of the sealing plate 1 has a positive electrode case 2
In the outer diameter direction with respect to the height direction PP (shown in FIG. 2), and the inclination angle θ is 0 to 12 ° with respect to the height direction.

The battery is assembled by filling the inside of the battery with the negative electrode 6, the separator 4, the positive electrode 5 and the non-aqueous electrolyte, and
This is performed by caulking the opening of the inside of the positive electrode case 2 and the sealing plate 1 with a gasket 3 interposed as an insulator between them.

Next, (Table 1) shows a coin-type lithium manganese dioxide battery CR202 as a specific embodiment of the present invention.
5 (diameter 20.0mm, thickness 2.5mm, electric capacity 16
5 mAh), the inclination angle θ of the opening of the sealing plate is -3
~ 0 ° (-means here in the inner diameter direction), 0 to 3
Each of 50 batteries assembled using the sealing plates (Examples 1 to 6) of 3 ° to 6 °, 6 ° to 9 °, 9 ° to 12 °, and 12 ° to 15 ° was configured at 60 ° C. for 1 hour / A thermal shock cycle test at -10 ° C for 1 hour was carried out for 4 weeks, and the leakage resistance was examined. The cumulative number of leakage occurrences as a result of confirmation every week is shown in the table.

The compressibility of the gasket at this time was 50 to 75% between the sealing plate shoulder 1a and the positive electrode case, and 25 to 60% between the sealing plate opening tip 1b and the positive electrode case.

[0013]

[Table 1]

As is clear from this (Table 1), when the inclination angle θ of the opening of the sealing plate becomes 0 ° or less and 12 ° or more,
The compression ratio of the gasket between the sealing plate shoulder 1a and the positive electrode case after caulking the case is 50 to 75%, and the compression ratio of the gasket between the sealing plate opening front end 1b and the positive electrode case is 25 to 60%. Even if it does, the liquid leakage resistance decreases.

When the sealing plate according to the present embodiment is used, the angle of inclination θ of the opening of the sealing plate is restricted to 0 to 12 ° so that the gasket between the sealing plate shoulder 1a and the positive electrode case after caulking is sealed. If the compressibility is 50 to 75% and the compressibility of the gasket between the sealing plate opening front end 1b and the positive electrode case is 25 to 60%, an excellent effect of preventing liquid leakage can be obtained.

This is because the inclination angle θ of the opening of the sealing plate is 0 °.
Under the following conditions, the caulking pressure is distributed inward of the battery and the bottom surface of the positive electrode case, and conversely, when θ is 12 ° or more, the caulking pressure is distributed outside of the battery and in the bottom surface direction of the positive electrode case, respectively. It is considered that this is because pressure cannot be sufficiently transmitted to the plate opening tip portion 1b.

[0017]

As is clear from the description of the above embodiment,
The lithium battery using the sealing plate of the present invention which does not have a U-shaped folded portion at the periphery but has the vertical annular portion at the outermost periphery can provide a battery having excellent liquid leakage resistance. In the above example, the coin-type lithium manganese dioxide battery is described,
The present invention is not limited to the battery system and can be applied to other coin-type lithium primary batteries, coin-type lithium secondary batteries, and the like.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a lithium battery according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a sealing plate of the battery.

[Explanation of symbols]

 1 Sealing Plate 1a Sealing Plate Shoulder 1b Sealing Plate Opening Tip 2 Positive Electrode Case 3 Gasket 4 Separator 5 Positive Electrode 6 Negative θ Inclination Angle

Front page continuation (72) Inventor Fumio Oo 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A sealing plate having a U-shaped folded portion at its peripheral edge and a vertical annular portion at its outermost periphery, a cylindrical positive electrode case with a bottom, and a gasket interposed between the positive electrode case and the sealing plate. In a lithium battery in which a positive electrode case opening is caulked inward to seal a power generating element, the inclination angle of the sealing plate opening with respect to the height direction of the positive electrode case is 0 to 1 in the outer radial direction.
2 °, the compression ratio of the gasket between the shoulder of the sealing plate and the positive electrode case is 50 to 75%, and the compression ratio of the gasket between the front end of the opening of the sealing plate and the positive electrode case is 25 to 60%.
A lithium battery characterized by being held in.