JPS60230355A - Manufacture of coin type lithium battery - Google Patents

Abstract

PURPOSE:To eliminate flow out of sealant to the outside of battery to prevent appearance defect by specifying coating length of sealant applied to the inner surface of straight part standing from the bottom of a case which also serves as a positive terminal. CONSTITUTION:A coin type lithium battery consists of a case 1 which also serves as positive terminal, a positive mix 5, a separator 6, a sealing plate 2 in which lithium plate 3 is pressed, and a gasket 4. Coating length of sealant 7 such as pitch or high polymer applied on the inner surface of straight part standing from the bottom of the case 1 is limited to 50-70% of height of the case. The case 1 is sealed with the gasket 4 interposed between the case and the sealing plate 2. Flow out of the sealant 7 to the outside of the battery caused by increase in internal pressure can be prevented without decrease in leakage resistance. Therefore, troubles such as appearance defect and contact defect are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a coin-shaped lithium battery in which a sealant is applied to the rising inner circumferential surface of a metal case that also serves as a positive terminal facing a gasket. The structure of the conventional example and its problems The vertical cross-sectional view of a typical conventional coin-shaped lithium battery is shown in the first part.
As shown in the figure. In the figure, 1 is a metal case that also serves as a positive electrode terminal, 2 is a sealing plate that also serves as a negative electrode terminal, and lithium 3, which is a negative electrode active material, is pressed onto the inner wall of the sealing plate. 04 is a gasket generally made of polypropylene, etc.; 6 is a positive electrode forming mixture containing manganese dioxide or carbon fluoride as an active material, and 6 is a separator made of polypropylene impregnated with a non-aqueous electrolyte. The periphery of the sealing plate 2, which also serves as a negative electrode terminal, is tightened via the gasket 4 to provide a hermetically sealed seal.

Conventionally, coin-shaped lithium batteries have been studied in various ways to improve their leakage resistance, but among them,
By applying pitch, a polymer sealant 7, etc. to the surface of the metal case 1, which also serves as the positive electrode terminal, facing the gasket, the leakage resistance has been greatly improved. But on the other hand,
Due to the internal pressure of the battery rising due to the pressurized seal, or due to the internal pressure of the battery increasing during high-temperature storage, the sealant at the opening end of the case may leak out of the battery, causing defects in the battery's appearance. Also, when it is incorporated into electronic equipment, especially electronic wristwatches, it has the disadvantage of causing poor contact between the terminal and the battery.

Purpose of the Invention The present invention solves the conventional problems as described above, prevents the sealant from flowing out of the battery due to an increase in the internal pressure of the battery, and
The purpose of this invention is to prevent defects in the appearance of batteries caused by sealants and problems such as poor contact between terminals and batteries when incorporated into electronic wristwatches that use batteries.

Structure of the Invention In order to achieve the above-mentioned object, the present invention applies a sealant applied from the bottom surface to the rising inner peripheral surface of a metal case that also serves as a positive electrode terminal for a length of 50 to 70% of the case height. It is characterized by the fact that it only needs to be applied. By manufacturing a battery with the above configuration, it is possible to prevent the sealant from leaking out of the battery.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 2 shows the state in which the sealant is applied to the rising inner peripheral surface of the metal case which also serves as the positive electrode terminal according to the embodiment of the present invention, and Fig. 3 shows the state in which the sealant is applied in the conventional manner. This is what is shown. Conventionally, as shown in FIG. 3, the sealant was applied up to the tip of the case opening, which resulted in good leakage resistance, but the above-mentioned problems occurred. In the present invention, the leakage resistance performance is maintained at the same level as the conventional one, and the structure is such that no sealant is present inside the case opening tip.
It prevents the sealant from leaking out of the battery due to an increase in internal pressure of the battery, eliminates problems such as defects in the appearance of the battery caused by the sealant and contact resistance between the battery and the terminals, and improves quality. Stable batteries can be manufactured.

In order to confirm the effects of the present invention, we investigated the application position of the sealant applied to the rising inner circumferential surface of the metal case that also serves as the positive electrode terminal, and the results are shown below. The height of the metal case is 2.0 m, and the sealant applied to the inner peripheral surface of the rising part of the metal case is a pinch mixed with non-drying mineral oil, and the application position is A - 0.2 + m from the bottom of the metal case. , B
・-0,6+m, C・l, Omn.

D.-1, 4mm, E-1, 8mm'ij. This is based on the height of the metal case, A...10%, B...30%, C...60 inches, and D...70 inches from the bottom of the case.

E: Corresponds to the 90% position. Batteries A and B were manufactured using metal cases coated with these sealants.

The following table shows the results of a comparison of leakage resistance and sealant leakage to the outside of the battery for batteries C, D, and E, and battery F manufactured by applying sealant to the tip of the conventional metal case opening. Ta.

The battery tested here had an outer diameter of 20 mm and a total height of 2.
A size of 0M was used. The test contents are as follows.

(1) Number of batteries with leakage after being left at a temperature of 60°C for 100 days and number of batteries with sealant leaking outside the battery.

? ) The number of batteries with leakage after 30 days of high temperature (60°C), -low temperature (-10°C) cycle test (MILSTD 202D-1oeC) and the number of batteries in which the sealant leaked to the outside of the battery. The number of batteries tested was 100 each.

Effects of the Invention As is clear from the above results, the position of the sealant applied to the inner circumferential surface of the rising part of the metal case, which also serves as the positive electrode terminal, of the present invention is adjusted from the bottom of the case to the height of the case, from 50 to 70 degrees of the height of the case. By applying the sealant to a length of 1.5%, the leakage resistance is on the same level as in the past, and it is highly effective in preventing the sealant from leaking out of the battery.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a typical conventional coin-type lithium battery, FIG. 2 is a vertical cross-sectional view showing the application state of the sealant on the metal case in an embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view of a conventional coin-type lithium battery. FIG. 3 is a longitudinal cross-sectional view showing the application state of the adhesive. 1... Metal case, 2... Sealing plate, 3...
...Negative electrode active material, 4...Gasket, 7.
...Sealant. Name of agent: Patent attorney Toshio Nakao (1st person)
FA 29 Figure 3

Claims (1)

[Claims] This is a coin-type lithium battery manufacturing method in which a sealant is applied to the rising inner circumferential surface of the metal case, which also serves as the positive electrode terminal, and a gasket attached to the periphery of the sealing plate is inserted into this part. A method for manufacturing a coin-shaped lithium battery, characterized in that a sealant is applied to the inner circumferential surface by a length of 50 to To of the height of the case.