JPH0547363A - Sealed secondary battery - Google Patents

Abstract

PURPOSE:To easily manufacture a safety valve section with high reliability by providing a curved space section communicated to the space of an electrode plate group at the connection section around films storing the electrode plate group, and forming a small hole penetrating the films on the space section. CONSTITUTION:A positive electrode plate 1, an electrolyte 2, and a negative electrode plate 3 are arranged on the same plane, the surface and the back face are covered by films 4, 4', and the periphery is connected. A curved space section 7 interlocked with a space 6 stored with an electrode plate group is formed on part of a connection section 5, and silicone oil 8 is injected into the space section 7. A small hole 9 penetrating the films 4, 4' is provided on the space section 7, and a safety valve section is formed. No oil is retained at the small hole 9 portion, thus the discharge of gas is stabilized, the films 4, 4' are closely stuck under negative pressure, and the closing property is improved. When the length and width of curves of the space sections 6, 7 and the position of the small hole 9 are changed, the valve opening pressure can be adjusted. A battery with a high-reliability safety valve can be manufactured with high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed secondary battery, and more particularly to a structure of a safety valve portion formed at a joint portion of a film containing an electrode plate group.

[0002]

2. Description of the Related Art In recent years, with the spread of small devices such as portable devices, the secondary battery serving as a power source for these devices has become thin and lightweight. As a structure of a thin sealed secondary battery, for example, there is one described in Japanese Patent Application No. 63-188505. In this case, since the battery thickness is thin, it is not possible to take a sufficient space like a large-sized sealed secondary battery, so that the conventional structure of the safety valve portion using the rubber cap cannot be adopted. For this reason, a structure as described in Japanese Patent Application No. 62-133665 has been proposed for a thin sealed secondary battery. The method is a structure that has a gas discharge path formed in a convex shape by leaving a part of the joint part of the outer peripheral part of the two film sheets, which is the battery case accommodating the electrode plate group, as an unwelded part. Another synthetic resin reinforcement material is attached so as to cross the outer surface of the welded portion in order to secure the obstruction of the gas discharge path, but this method increases the process of attaching the synthetic resin reinforcement material. There is a possibility that the productivity will be deteriorated and that the valve opening pressure of the safety valve portion will be high due to the attachment of the synthetic resin reinforcing material.

Further, as described in Japanese Patent Application No. 174265/1988, the peripheral portions of two film sheets, which serve as a battery case accommodating an electrode plate group, are joined to each other, and a small hole is provided on one side of the sheet. , There is one in which the required valve opening pressure of the safety valve portion is obtained by discontinuously joining the inner surface side of the periphery and by appropriately selecting the position of the discontinuous joining portion. As a method of providing a small hole, it is difficult to control the processing so that the outer surface of one film sheet is not damaged from the outer surface of one film sheet after joining two film sheets. Even if an attempt is made to join the other film sheet after providing the small holes, there is a possibility that the small holes and the discontinuous joining portion are likely to be misaligned and the operation reliability of the safety valve portion is deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and improves the productivity of manufacturing the safety valve portion, lowers the valve opening pressure of the safety valve portion, and improves the operation reliability. It is an object to provide an improved sealed secondary battery.

[0005]

The sealed secondary battery according to the present invention comprises:
A bay-shaped space that communicates with the space where the electrode plates are stored is provided.
The bay-shaped space portion is characterized by having a safety valve portion having small holes or slits penetrating from one film outer surface to the other film outer surface, and the positive electrode, the electrolyte and the negative electrode are on the same plane as the electrode plate group. It is suitable for a thin sealed secondary battery as arranged, and is characterized in that the bay-shaped space is filled with oil.

[0006]

The bay-shaped space portion can be easily manufactured by collectively welding at the time of forming a joint around the film, and a small hole penetrating from the outer surface of one film to the outer surface of the other film in the bay-shaped space portion or The slit can be easily manufactured by providing the bay-shaped space portion and then penetrating it at a predetermined position with a needle. Further, since the small holes or slits penetrate from one film outer surface to the other film outer surface, the film around the small holes or slits is easily opened, and when the bay-shaped space is filled with oil, Unlike the conventional single-sided small holes, the small holes or slits that penetrate do not allow oil to stay in the small holes or slits, so that gas discharge is stable and at the time of negative pressure, one film adheres to the other film. The occlusion property becomes good. The valve opening pressure can be easily set by changing the length or width of the bay opening at the boundary between the space where the electrode group is housed and the bay-shaped space, or by changing the position of the small hole or slit. Since the bay-shaped space portion and the small holes or slits can be accurately positioned, a highly reliable safety valve portion can be formed.

[0007]

EXAMPLE An example of the present invention will be described. 1 is a front view showing an embodiment of the sealed secondary battery of the present invention, FIG. 2 is an enlarged sectional view taken along the line AA in FIG. 1, and FIG. 3 is taken along the line BB in FIG. It is an expanded sectional view. The positive electrode plate 1, the electrolyte 2, and the negative electrode plate 3 are covered with films 4 and 4'from the front and back surfaces of an electrode plate group arranged on the same plane.
The area around is joined. Part of the joint 5 has a bay-shaped space 7 communicating with the space 6 in which the electrode plate group is housed,
Silicone oil 8 is injected into the bay-shaped space 7, and a safety valve portion is formed by forming a small hole 9 penetrating from the outer surface of one film 4 to the outer surface of the other film 4 ′ in the bay-shaped space 7. ing. The films 4 and 4'are laminated films having a three-layer structure composed of a polyethylene terephthalate layer / aluminum layer / polypropylene layer in this order from the outer surface side, and the polypropylene layers on the inner surface side are welded to each other.

The size of the battery in this embodiment is 85 m in length.
m, width 54 mm, thickness 1 mm.

In the production, the positive and negative electrode current collectors are attached to the film 4'using an adhesive, the active material is applied and dried on the current collectors, and the positive electrode plate 1 and the negative electrode are formed. The plate 3 is prepared, and the electrolyte 2 is placed between the positive electrode plate 1 and the negative electrode plate 3 to form a plate group on the same plane. Then
Film 4 and 4'covered from above the electrode plate group with film 4.
One of the four sides is bonded by heating and pressing at 220 ° C. for 5 seconds with a heat sealer, leaving a part where the bay-shaped space 7 is formed. Next, a predetermined amount of silicone oil 8 is injected from the bay mouth 10 of the bay-shaped space portion 7, and a penetrating and penetrating from the outer surface of one film 4 to the outer surface of the other film 4'in the bay-shaped space portion 7 with a needle of 1 mm After forming the small hole 9 to form the safety valve portion, the remaining three sides of the four sides around the films 4 and 4'are heated and pressed at 220 ° C. for 5 seconds by a heat sealer and weld-bonded to each other to form a sealed secondary battery. To make.

The sealed secondary battery obtained does not show a decrease in capacity after 100 times of charging and discharging, and has sufficient airtightness even when dropped from a position of 1 m in height. The valve opening pressure of the part could be opened at a low pressure of 20 mmHg.

[0011]

As described above, the present invention can provide a sealed secondary battery having a highly reliable safety valve satisfying a predetermined low valve opening pressure level simply and with high productivity. it can.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view taken along the line AA in FIG.

FIG. 3 is an enlarged cross-sectional view taken along the line BB in FIG.

[Explanation of symbols]

1 is a positive electrode plate, 2 is an electrolyte, 3 is a negative electrode plate, 4, 4'is a film, 5 is a joint part, 6 is a space for accommodating a group of electrode plates, 7 is a bay-shaped space part, 8 is silicone oil, 9 Is a small hole, 10 is a bay mouth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Wada 1-1-1 Nishishinjuku, Shinjuku-ku, Tokyo Shin-Kindo Electric Co., Ltd. (72) Inventor Akio Komaki 2-chome, Nishishinjuku, Shinjuku-ku, Tokyo No. 1 Shinshin Todo Denki Co., Ltd. (72) Inventor Yoshinori Hasuda 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Keiji Akudo 1-chome, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A bay-shaped space portion communicating with a space in which the electrode plate group is housed is provided at a part of a joint portion around the film housing the electrode plate group, and the bay-shaped space portion is formed from one outer surface of the film. A sealed secondary battery having a safety valve portion having a small hole or a slit penetrating to the outer surface of the other film. 2. The electrode plate group has a structure in which a positive electrode, an electrolyte and a negative electrode are arranged on the same plane.
The sealed secondary battery described. 3. The sealed secondary battery according to claim 1, wherein the bay-shaped space is filled with oil.