JPH0757706A - Sealed battery - Google Patents

Abstract

PURPOSE:To enhance electrolyte leakage resistance by using a sealing plate in which material thickness is decreased so that the inner diameter of a vertically standing part of the outermost circumference is increased in an opening direction and holding compression ratio in the bottom of a gasket in a specified range. CONSTITUTION:A negative electrode 6, a separator 4, a positive electrode 5, and a nonaqueous electrolyte are placed in a battery, and the opening of a positive case 2 is crimped toward a sealing plate 1 which also serves as a negative terminal through an insulating gasket 3 to seal the battery. The opening of the sealing plate 1 compresses the bottom of the gasket 3 having an L-shaped cross section. Since the material thickness of the sealing plate 1 is decreased so that the inner diameter is increased in an opening direction, the force enlarging the opening is produced and drop in compression degree on the side of the gasket is prevented. The compression ratio of the bottom of the gasket is kept 30-60% after sealing. If the compression ratio is out of the range, the compression degree of the gasket is partially decreased and electrolyte leakage resistance is decreased.

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 positive electrode case, a sealing plate, and a gasket, and more particularly to a sealed battery having improved liquid leakage resistance.

[0002]

2. Description of the Related Art Conventionally, in sealed batteries which tend to be used for a long period of time such as organic electrolyte type coin type lithium batteries and button type alkaline batteries, efforts have been made to increase the battery internal volume in order to increase the capacity. It was As a method thereof, as described in JP-A-4-341756, U is applied to the periphery.
A sealing plate that does not have a folded portion connected in a letter shape has been adopted. FIG. 2 shows the structure of a conventional battery, taking a coin-type lithium manganese dioxide battery as an example. In FIG. 2, reference numeral 1 denotes a sealing plate which also serves as a negative electrode terminal and does not have a U-shaped continuous folded portion, and the thickness of the opening does not change. 2 is a positive electrode case that 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 nonwoven fabric, 5 is manganese dioxide, and a conductive agent such as graphite and a binder are mixed. A pressure-molded positive electrode, 6 is a negative electrode using lithium metal as an active material.

The battery is assembled by a negative electrode 6, a separator 4 and a positive electrode 5.
Then, the battery is filled with a non-aqueous electrolytic solution, and the opening of the positive electrode case 2 is caulked inside by interposing a gasket 3 interposed as an insulator between the positive electrode case 2 and the sealing plate 1 for sealing.

[0004]

However, when this sealing plate is used, the strength in the radial direction is weak because it does not have a folded portion connected in a U-shape at the periphery, and the opening of the sealing plate of the battery when caulking is sealed. It escaped in the inner diameter direction, and the degree of compression on the side of the gasket was reduced, and the liquid leakage resistance was reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a sealed battery having excellent liquid leakage resistance.

[0006]

In order to solve this problem, the present invention does not have a U-shaped folded portion extending along the peripheral edge, but the inner diameter of the portion perpendicular to the outermost edge increases in the direction of the opening. Use a sealing plate that reduces the plate thickness.

[0007]

By using this sealing plate, the opening of the sealing plate compresses the bottom of the gasket having an L-shaped cross section at the time of caulking and sealing, but the plate thickness decreases so that the inner diameter increases toward the opening. The opening of the sealing plate expands by receiving a force from the gasket in the outer diameter direction of the battery. Therefore, the compression degree of the gasket side portion is prevented from being lowered, and the liquid leakage resistance is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealed battery according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a sealing plate which also serves as a negative electrode terminal of the present invention in which the plate thickness is reduced so that the inner diameter increases toward the opening, and which does not have a U-shaped folded portion at the periphery.
2 is a positive electrode case which also serves as a positive electrode terminal, 3 is a gasket, 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 whose active material is lithium metal or lithium alloy.

The battery is assembled by negative electrode 6, separator 4, positive electrode 5
Then, the battery is filled with a non-aqueous electrolytic solution, and the opening of the positive electrode case 2 is caulked inside by interposing a gasket 3 interposed as an insulator between the positive electrode case 2 and the sealing plate 1 for sealing. At this time, if the compression rate after caulking and sealing of the gasket bottom portion interposed between the opening of the sealing plate and the bottom of the case is less than 30%, the degree of compression is low and the liquid leakage resistance is reduced. Further, when the compression rate of the gasket after caulking exceeds 60%, the opening of the sealing plate spreads too much in the outer diameter direction, the compressibility of the gasket at the shoulder of the sealing plate decreases, and the liquid leakage resistance decreases.

Next, as a concrete example of the present invention, a coin type lithium manganese dioxide battery CR2016 (diameter 2)
Leakage occurred as a result of conducting 50 cycles of leak test of thermal shock cycle of 85 ° C. 1 hour / −10 ° C. 1 hour with 100 batteries each of 0.0 mm, thickness 1.6 mm, electric capacity 90 mAh) Indicates the rate.

[0012]

[Table 1]

The compressibility is an average value measured at three points. High-density polypropylene was used as the gasket material. As is clear from this (Table 1), by using the sealing plate according to the present embodiment and setting the bottom compressibility of the gasket to 30 to 60%, an excellent effect of preventing liquid leakage can be obtained.

[0014]

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. In this example, the coin-type lithium manganese dioxide battery was described, but other coin-type lithium primary batteries, coin-type lithium secondary batteries,
It is also applicable to button type alkaline primary batteries, alkaline secondary batteries, and the like.

[Brief description of drawings]

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

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

[Explanation of symbols]

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

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

Claims (2)

[Claims] 1. A gasket, which does not have a U-shaped folded portion on its peripheral edge and has a bottomed cylindrical positive electrode case and a positive electrode case and a positive electrode case and a sealing plate, which has a portion perpendicular to the outermost peripheral edge. A sealed battery in which the positive electrode case opening is caulked inside and the power generation element is sealed, and the plate thickness decreases so that the inner diameter of the portion perpendicular to the outermost edge increases toward the opening. A sealed battery characterized by using a plate. 2. The compression ratio of the gasket bottom portion, which is interposed between the opening of the sealing plate and the bottom portion of the case, after caulking is 30 to 60%.
The sealed battery according to claim 1, wherein the sealed battery is held by the battery.