JPH08339785A - Sealed battery - Google Patents

Abstract

PURPOSE: To improve fluid leakage resistance of a sealed battery b providing a protrusion of concentrical circumference in a flange part of a hat-shaped seal port plate, and compressing a gasket in a part corresponding to the protrusion by a prescribed compressing rate. CONSTITUTION: In the case of performing a seal in assembling a battery, a concentrically circular protrusion 1a is provided in a flange part of a seal port plate 1, to seal by calking a gasket interposed between the protrusion 1a and a positive electrode case 2. Here a compressing rate, when it is less than 25%, is insufficient to lack fluid leakage resistance. When the compressing rate exceeds 75%, the gasket 3 is broken in the protrusion part 1a, to sometimes causes remarkably decreasing the fluid leakage resistance. Accordingly, by setting the compressing rate of the gasket to 25 to 75%, a packing effect of the gasket by a calking seal can be maintained for a long time, so as to enable the fluid leakage resistance to improve.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, organic electrolyte type coin type lithium batteries and button type alkaline batteries have been demanded to be small and thin in accordance with the miniaturization of equipment used. As a conventional battery, a sealing plate or a hat-shaped sealing plate having a U-shaped folded portion on the periphery has been adopted. The structure of a conventional battery is shown in FIGS. 2 and 3, taking a coin type lithium manganese dioxide battery as an example.

In FIG. 2, reference numeral 1 is a sealing plate having a U-shaped folded portion which doubles as a negative electrode terminal. 2 is a positive electrode case that also serves as a positive electrode terminal, 3 is a gasket made of polyolefin synthetic resin such as polyethylene and polypropylene, 4
Is a separator made of polypropylene nonwoven fabric, 5 is a positive electrode which is pressure-molded after mixing manganese dioxide with a conductive agent such as graphite and a binder, and 6 is a negative electrode using lithium metal as an active material.

To assemble the battery, the negative electrode 6, the separator 4, the positive electrode 5 and the non-aqueous electrolyte are filled in the battery case, and the opening of the positive electrode case 2 is interposed as an insulator between both the positive electrode case 2 and the sealing plate 1. It is carried out by caulking the inside through the gasket 3 and sealing. FIG. 3 is the same as the structure of FIG. 2 except that a hat-shaped sealing plate is used.

[0005]

However, when a sealing plate having a U-shaped folded portion connected to the periphery is used as shown in FIG.
Not only is it difficult to press the folded portion that is continuous in the shape of a letter, but even if it is processed, the processing accuracy is reduced, and since there is no dimensional stability, liquid leakage resistance is reduced.

When the hat-shaped sealing plate is used, the battery can be easily thinned. However, when the positive electrode case is folded and the gasket is compressed at the time of sealing, the liquid leakage resistance is poor because the compression positions are concentrated in the positive electrode case opening.

[0007]

In order to solve the above problems, the present invention uses a hat-shaped sealing plate having concentric projections on the collar.

[0008]

By using such a sealing plate, at the time of caulking and sealing, a part of the gasket having a high compressibility is provided corresponding to the two circumferentially protruding portions of the flange of the sealing plate and the positive case opening. Can be provided, and the leakage resistance of the battery can be improved.

[0009]

EXAMPLE A sealed battery of an example of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 denotes the hat shape of the present invention,
A sealing plate having concentric protrusions 1a on the collar portion, 2 is a positive electrode case also serving as a positive electrode terminal, 3 is a gasket, 4 is a separator made of polypropylene nonwoven fabric, 5 is manganese dioxide, and a conductive agent such as graphite and A positive electrode 6 is pressure-molded after mixing with a binder, and 6 is a negative electrode using lithium metal as an active material. The battery is assembled by negative electrode 6, separator 4, positive electrode 5
And filling the inside of the battery case with a non-aqueous electrolytic solution, and caulking the opening of the positive electrode case 2 through the gasket 3 interposed as an insulator between the case 2 and the sealing plate 1 to seal the opening. Done by.

At this time, the portion of the gasket interposed between the protrusion provided on the flange portion of the sealing plate and the positive electrode case has a compression ratio after caulking and sealing (assuming the thickness before compression is 100).
5% to 75% is suitable. Gasket compressibility is 25
If it is less than%, the degree of compression is not sufficient and the liquid leakage resistance of the battery decreases. Also, the compression ratio after crimping the gasket is 7
If it exceeds 5%, the gasket compressed at the time of sealing may be cut by the protrusion provided on the flange of the sealing plate, resulting in a short circuit or a significant decrease in liquid leakage resistance. Therefore, the compressibility of the portion of the gasket corresponding to the protrusion 1a is preferably 25 to 75%.

Next, as a concrete example of the present invention, a coin type lithium manganese dioxide battery CR2012 (diameter 20.
Batteries of Examples 1 to 5 were prepared by changing the gasket compressibility of the sealing plate protrusion with a battery having a thickness of 0 mm, a thickness of 1.2 mm and an electric capacity of 55 mAh. In addition, batteries formed by using the conventional sealing plate were set as Comparative Examples 1 and 2. Comparative Example 1 has a U on the periphery.
A battery is constructed by using a sealing plate having a folded portion continuous in a letter shape, and Comparative Example 2 is a battery by using a hat-shaped sealing plate. The leak occurrence rate after 50 cycles of the leak test of a thermal shock cycle in which 100 batteries of each battery were configured and kept at 85 ° C. for 1 hour and at −10 ° C. for 1 hour is shown in (Table 1).

[0013]

[Table 1]

High-density polypropylene was used as the material of the gasket. As is clear from this (Table 1),
By using the sealing plate according to this example and crimping the gasket interposed between the concentric protrusions provided on the flange portion of the sealing plate and the positive electrode case to a compressibility of 25 to 75% after sealing, leakage is prevented. An excellent effect of preventing liquid is obtained.

Further, this effect is obtained by using the sealing plate of the present invention, and by using a gasket made of a polymer material on the periphery of the sealing plate,
The same can be obtained for a battery constructed by using a directly molded product.

[0016]

As is apparent from the above description of the embodiments, according to the sealed battery using the sealing plate of the present invention, it is possible to realize the compressed state in which the gasket packing effect by the caulking sealing can be maintained for a long period of time. It is possible to provide a battery having excellent liquid leakage resistance.

Although the coin type lithium manganese dioxide battery is described in the above embodiment, other coin type lithium primary batteries, coin type lithium secondary batteries, button type alkaline primary batteries, alkaline secondary batteries, etc. It is also applicable to.

[Brief description of drawings]

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

FIG. 2 is a half sectional view of a conventional sealed lithium battery.

FIG. 3 is a half sectional view of another sealed lithium battery of the conventional example.

FIG. 4 is a top view and a side view showing the sealing plate of the present invention.

[Explanation of symbols]

 1 Sealing Plate 1a Protrusion 2 Positive Electrode Case 3 Gasket 4 Separator 5 Positive Electrode 6 Negative Electrode

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shusuke Oguro 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A sealed battery in which a power generating element is sealed by a battery case, a sealing plate for sealing the opening of the case, and a gasket interposed between the case and the sealing plate, wherein the sealing plate is A sealed battery having a hat-like shape and concentric projections on the collar portion. 2. In the battery after sealing, the compressibility of the gasket corresponding to the concentric circular protrusions provided on the flange portion of the sealing plate is in the range of 25 to 75%. The sealed battery described. 3. The sealed battery according to claim 1, wherein a gasket made of polymer resin is integrally formed on the periphery of the sealing plate.