JPH11273640A - Sealing plate of sealed battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing plate which can be communicated with the outside by use of a simple structure by being surely ruptured when pressure within a container becomes excessive and a method for manufacturing the same. SOLUTION: A sealing plate 2 mounted on a container 1 is constructed of a metallic plate and a groove 22 is formed in its surface along a contour surrounding a predetermined area. An swelling part 23 is formed inside the groove 22. Rupturing pressure at the groove 22 in the sealing pate 2 can be adjusted by appropriately setting the thickness of the metallic plate at the groove 22. A method for manufacturing the sealing plate 2 includes compressing the metallic plate through press working to form the groove 22 and the swelling part 23. The rupturing pressure can be adjusted easily by annealing the metallic plate. Alternatively, a recess part 21 may be formed in an area including the groove 22 and the swelling part 23 and the groove 22 and the swelling part 23 may be formed on the bottom surface of the recess part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing plate for a sealed battery and a method for manufacturing the same, and more particularly to a sealing plate having a valve function for communicating with the outside when the pressure in the battery becomes excessive, and the sealing plate for the sealing plate. Related to a manufacturing method.

[0002]

2. Description of the Related Art In order to prevent the pressure inside a sealed battery from becoming excessive, various safety valve devices mounted on a container have been proposed. For example, Japanese Utility Model Laid-Open No. 5-90809 discloses an improvement in a battery provided with a thin-wall destruction safety valve that closes an opening of an outer can for accommodating an electrode group with a sealing plate, thins part of the outer can, and is damaged by internal pressure. For this purpose, there has been proposed a device in which the outer can is made square and a part of the ridge other than the sealing portion is thinned.

In Japanese Utility Model Application Laid-Open No. 5-59745, a safety valve device in which a through hole is provided in a sealed battery container and the through hole is sealed with a metal foil is used as a conventional technology, and the breaking pressure of the metal foil is set to a low pressure. In view of the difficulty in performing the above, a concave portion having a flat surface is formed in the bottom wall of the battery container, a through hole is provided in the bottom surface of the concave portion, the diaphragm provided with the weakened portion is provided with a through hole in the flat surface of the concave portion. There has been proposed a safety valve device that is closed and placed, and spot-welded to a flat surface in the vicinity of a weakened portion thereof, and the entire periphery of the diaphragm is welded to a flat surface.

Further, Japanese Patent Application Laid-Open No. Hei 6-333548 discloses a battery case in which a battery case is sealed using a sealing plate provided with a valve body.
A battery plate in which a thin portion is provided in a battery case bottom portion or the like in the related art, a grooved thin portion is provided in the bottom portion or a battery case in which the entire bottom portion is thinned, and a lid plate having a valve hole,
Sealed by an explosion-proof sealing plate including a cap-shaped terminal plate with an exhaust hole and a valve element interposed between them and constantly closing the valve hole of the lid plate, and a groove-shaped thin wall of the battery case due to gas pressure generated in the battery There has been proposed an explosion-proof battery in which the rupture pressure of a portion or a thin bottom surface is larger than the rupture pressure of a valve body of an explosion-proof sealing plate and smaller than the pressure resistance of a battery sealing portion.

The explosion-proof sealing plate is disclosed in Japanese Patent Laid-Open No. 5-744.
In No. 34, after constructing the sealing plate for the purpose of stabilizing the breaking pressure of the sealing plate, the valve body is inflated upward from the valve hole of the sealing plate with a pressure equal to or lower than the pressure at which the thin valve body is broken. In addition, there has been proposed a method of manufacturing an explosion-proof sealing plate for a battery having a step of contacting the blade projection. Japanese Unexamined Patent Publication No. Hei 6-338305 discloses such an explosion-proof sealing plate having a special structure such as welding a flexible metal explosion-proof valve to a metal strip terminal plate so as to obtain a stable operating pressure. A board is disclosed. Further, as a method of forming a thin portion of a metal explosion-proof valve, a method of forming a C-shaped rectangular cross-section or a wedge-shaped undercut by hitting a metal stamp or the like, or locally applying a moderate load with a steel ball to form a hemisphere locally A method for forming a thin portion of the above is disclosed.

[0006] Japanese Patent Application Laid-Open No. Hei 7-130346 discloses that
Regarding the non-aqueous electrolyte secondary battery of the sealed battery, as a safety valve for releasing the internal pressure of the battery when an abnormality occurs, a support member having a through-hole, a cleaving membrane stretched to cover the through-hole of the support member, There has been proposed a configuration in which the opening shape of the through hole is a shape having a pointed head projecting inward of the through hole.

[0007]

The above-mentioned JP-A-7-130
According to No. 346, regarding the non-aqueous electrolyte secondary battery, the pressure at which the internal pressure is released is desirably as low as 5 kgf / cm ² or more, but the strength of a conventional safety valve using an aluminum thin film is high. It is described that even if a process such as forming a groove in the safety valve is performed, an internal pressure of about 30 kgf / cm ² is required until the safety valve is opened because the safety valve is opened.

In other words, at least in the field of sealed batteries, it cannot be put to practical use because it cannot be set to break at low pressure if a groove is formed in a metal plate such as aluminum. Have been. Therefore,
According to the above-described method of forming a thin portion of a metal explosion-proof valve disclosed in Japanese Patent Application Laid-Open No. Hei 6-338305, it is difficult to set so as to open (break) at a low pressure of 30 kgf / cm ² or less.

On the other hand, in the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-333548, in order to secure the strength of the battery case, the breaking pressure of the thin portion at the bottom of the case is preferably 15 kgf / cm ² or more. However, there is no specific disclosure of a technique capable of reducing the breaking pressure of the thin portion to 15 kgf / cm ² or less, and even if a groove is formed in the aluminum thin film in the above-mentioned JP-A-7-130346, the internal pressure of about 30 kgf / cm ² is reduced. Although there is an inconsistency with the statement that it is necessary, the formation of a fragile thin portion with respect to the case body should be avoided even if the thin portion breaking pressure can be set low.

In view of the above, the present invention provides a sealing plate for closing an opening of a container of a sealed battery, which has a simple structure and can be reliably broken and communicated to the outside when the pressure in the container becomes excessive. It is an object to provide a sealing plate for a rechargeable battery.

Another object of the present invention is to provide a manufacturing method capable of manufacturing a sealing plate of a sealed battery by simple means and adjusting the breaking pressure thereof easily.

[0012]

In order to solve the above-mentioned problems, a sealing plate for a sealed battery according to the present invention is a metal plate for closing an opening of a container of the sealed battery. A groove is formed on the surface of the metal plate along a contour surrounding a predetermined area, and a bulging portion bulging toward the surface side of the metal plate is formed inside the groove. It is composed. According to this sealing plate, when the internal pressure of the sealed battery becomes excessive and the pressure received at the bulging portion exceeds a predetermined pressure, the sealing plate is broken at the groove portion, and the bulging portion is opened to communicate with the external space. I do. In this sealing plate, the breaking pressure is adjusted by appropriately setting the thickness of the metal plate in the groove.

[0013] Further, the sealing plate may be provided with a recess in a region including the groove and the bulging portion on the surface of the metal plate, and the groove may be formed on a bottom surface of the recess. And a bulging portion. In this sealing plate, the breaking pressure is adjusted by appropriately setting the thickness of the metal plate in the concave portion and the groove portion.

In the sealing plate according to the first or second aspect, as in the third aspect, the metal plate is formed by compressing the metal plate to form the groove and forming the bulging portion. The plate may be annealed. In this sealing plate, the breaking pressure is adjusted by performing an annealing process and appropriately setting the thickness of the metal plate in the groove portion.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a sealing plate for a sealed battery, comprising the steps of compressing a surface of a metal plate along a contour surrounding a predetermined region. A groove is formed, and a bulging portion bulging toward the surface of the metal plate is formed inside the groove. In this manufacturing method, the breaking pressure at the groove of the sealing plate is adjusted by appropriately setting the thickness of the metal plate at the groove.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a sealing plate for a sealed battery, comprising the steps of: A recess is formed, and a groove is formed on the bottom surface of the recess along a contour surrounding the second predetermined region to form a groove, and a bulge bulging toward the front side of the metal plate inside the groove. A projection is formed. In this manufacturing method, the breaking pressure in the groove portion of the sealing plate is adjusted by appropriately setting the thickness of the metal plate in the concave portion and the groove portion in order.

In the method for manufacturing a sealing plate according to claim 4 or 5, it is preferable that the metal plate is further subjected to an annealing treatment. In this manufacturing method, the breaking pressure in the groove portion of the sealing plate, the annealing process,
It is adjusted by appropriately setting the thickness of the metal plate in the groove portion.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a sealed battery provided with a sealing plate according to one embodiment. A sealing plate 2 is fitted into an opening 1a of a metal container 1, and the container 1 and the sealing plate 2 are open. The entire periphery of the portion 1a is hermetically joined by laser welding. The container 1 of this embodiment is formed by forming a plate made of an aluminum alloy into a rectangular parallelepiped by deep drawing, and accommodates, for example, components (not shown) of a nonaqueous electrolyte battery therein.

The sealing plate 2 of this embodiment is made of an aluminum alloy, is formed in a rectangular shape so as to conform to the shape of the opening 1a of the container 1, and has a flange portion 2a formed all around.
As shown in FIG. 2, a hole 2 b is formed in the center of the sealing plate 2, and a gasket 3 is fitted into the hole 2 b and is caulked by a rivet terminal 4. Therefore, the hole 2 b is sealed by the gasket 3. In addition, both the container 1 and the sealing plate 2 may be formed of another metal material.

On the surface of the sealing plate 2, a concave portion 21 is formed in a first predetermined region defined on one side in the longitudinal direction with the hole 2b as a center. A second predetermined region is further defined on the bottom surface of the concave portion 21, and a groove 22 is formed along a contour surrounding the second predetermined region. In the present embodiment, the first and second predetermined regions, that is, the concave portion 21 and the groove 22
Are formed in an oval shape in plan view, as shown in FIG.
It has a similar shape. A bulge 23 is formed inside the groove 22 in the recess 21, which will be described later. These recesses 21 and grooves 22 are formed by compressing a base plate made of an aluminum alloy, and the base plate is annealed to adjust the breaking pressure of the sealing plate 2 at the groove 22. Hereinafter, while explaining the manufacturing process of the sealing plate 2,
The concave portion 21, the groove 22, and the bulging portion 23 will be described in detail.

FIG. 3 shows a sealing plate 2 according to an embodiment of the present invention.
Indicate the steps in the manufacturing method, and the white arrows indicate the flow of the steps. First, in the drawing process (D),
With a so-called press machine and a press device (not shown) for performing press working including a die, drawing is performed on the base plate M made of aluminum alloy, and the main body M1 of the sealing plate 2 is drawn.
, And a step is formed between a portion M2 which forms the flange portion 2a later. Subsequently, the first compression working step (C
In 1), a first predetermined region R1 set on the blank M
Is compressed by a press device. Specifically, coining (coining) is performed, and an oval-shaped concave portion 21 is formed as shown in FIGS. At this stage, the bottom surface of the concave portion 21 is formed flat and the thin plate portion 2c is formed.
It has been.

Next, in a shearing step (S), a shearing process is performed by a press device along the outer shape of the flange portion 2a, and the sealing plate 2 is punched from the blank M. In the second compression working step (C2), the sealing plate 2 is coined again by the press device, and a groove 22 is formed on the bottom surface of the concave portion 21 along the contour surrounding the second predetermined region R2. It is formed. At this time, the thin plate portion 2c of the sealing plate 2 is
1 swells toward the opening. More specifically, the sealing plate 2 is compressed by an upper die UD having an annular ridge on the lower surface and a lower die LD having a flat upper surface as shown by a two-dot chain line in FIGS. 7 and 9. At this time, since the upper portion of the thin plate portion 2c (the opening side of the concave portion 21) is not pressed by the upper mold UD, the thin plate portion 2c bulges upward in FIGS. 7 to 9, and the upper opening side is a convex portion. The lower pressure-receiving side forms a bulged portion 23 with a concave portion.
As described above, since the pressure receiving side of the bulging portion 23 is formed into a curved concave shape, the bulging portion 23 has a larger area than the flat surface of the thin plate portion 2c in FIG.

Through the above steps, the recess 21 is formed in the sealing plate 2 and the bulging portion 2 is formed inside the groove 22 on the bottom surface.
3 is formed. Thus, the sealing plate 2 in this state is
When it is attached to the, a predetermined valve function is secured by the concave portion 21, the groove 22, and the bulging portion 23. That is, since the bulging portion 23 functions as a pressure receiving portion and the sealing plate 2 has a minimum thickness at the groove 22, the internal pressure of the container 1 becomes excessive, and the pressure applied to the bulging portion 23 becomes a predetermined pressure. Is exceeded, the sealing plate 2 breaks at the groove 22 and the bulging portion 23 falls off. Thereby, the second predetermined region R2 is opened, the inside of the container 1 communicates with the external space, and the internal pressure is reduced at a stretch. The sealing plate 2 at this time
Can be adjusted by appropriately setting the thickness of the concave portion 21 (thin plate portion 2c) and appropriately setting the thickness of the sealing plate 2 in the groove 22 portion. Thus, for example, the breaking pressure could be adjusted to a low value near 9.5 kgf / cm ^2, and good experimental results were obtained as shown in the upper part of FIG. In FIG. 17, the horizontal axis represents the sample number and the vertical axis represents the measured value of the breaking pressure. Shows the measurement results of the breaking pressure of the sealing plate 2 when the annealing step (A) was performed.

The above steps (D), (C1), (S) and (C2) are all performed by pressing, and the recess 21 is formed in the sealing plate 2 by continuous processing by a pressing device (not shown). At the same time, the groove 22 is formed on the bottom surface, and the bulging portion 23 is formed inside the groove 22 along with the formation of the groove 22, so that the sealing plate 2 having a valve function is formed by a single component. be able to. Thus, a sealing plate that can function as a safety valve for a sealed battery can be provided at low cost.

In the case where the sealing plate 2 is formed only by press working as described above, there is variation in the breaking pressure of each product as shown in the upper part of the graph of FIG. This is because the groove 22 of the sealing plate 2 is hardened through two compression steps, and this variation is within an allowable range, but it is not always easy to adjust the breaking pressure to a low value. Therefore, in the present embodiment, as shown in FIG. 3, after the second compression processing step (C2), the sealing plate 2
Is subjected to a heat treatment. That is, an annealing step (A) is provided, and after being heated at a predetermined temperature, it is cooled for a predetermined time.

Thus, for example, as shown in the lower part of the graph of FIG. 17, the breaking pressure of the groove 22 of the sealing plate 2 can be easily adjusted to a low value of 6.5 kgf / cm ² on average. Moreover, the variation of the breaking pressure for each product can be suppressed to be small, and the breaking pressure is adjusted to a lower value with remarkable stability as compared with the case where the annealing step (A) is not performed (shown in the upper part of FIG. 17). be able to.

The annealing step (A) may be performed at any stage in the manufacturing process. However, if the annealing step (A) is performed after the second compression working step (C2) as shown in FIG. Adjustment of the pressure is further facilitated, and a stable product with small variation in the breaking pressure can be provided. Further, a hole 2b is formed in the sealing plate 2 before the annealing step (A).
The drilling may be performed in another step. Further, the shearing step (S) may be performed after the second compression processing step (C2) or the annealing step (A).

In the above embodiment, the compression processing is
(C1, C2), but the breaking pressure can be adjusted to a low value within an allowable range by adding the annealing step (A) even if only once. That is, regarding the compression processing, the first compression processing step (C
1) is omitted, and only the second compression processing step (C2) is performed, and the blank M (the drawing processing step (D) is added as necessary)
To a predetermined region (for example, the second predetermined region R2
The groove 22 is formed along the contour surrounding the same region as above, and the groove 22 is formed, and the groove 22 is also subjected to an annealing treatment. Can be.

On the other hand, FIG. 10 shows a process in a method for manufacturing a sealing plate according to another embodiment of the present invention, in which the first compression working process (C1) in the manufacturing process shown in FIG. The sealing plate 2 shown in FIGS. 14 to 16 is formed in two steps. Although the drawing process (D) is omitted in FIG. 10, the drawing process is performed in the same manner as the above-described manufacturing process. However, FIGS. 3 and 10
In any of the above manufacturing steps, the drawing step (D) may be omitted, and the sealing plate 2 may be formed in a flat plate shape.
In the manufacturing process of FIG. 10, coining is performed on a first predetermined region R1 set on the blank M in a step (C11) preceding the first compression working, and first, FIGS.
As shown in FIG. 7, an oval-shaped concave portion 21 is formed. Subsequently, in the step (C12) subsequent to the first compression working, the concave portion 2 is formed.
When coining is performed over the entire circumference with a predetermined width along the inner diameter of the sealing member 1, the bottom surface of the sealing plate 2 bulges toward the opening as shown in FIGS. A protrusion 23 is formed.

Next, in a shearing process (S), a shearing process is performed by a pressing device (not shown) along the outer shape of the flange portion 2a, and the sealing plate 2 is punched from the blank M. Note that, also in the present embodiment, the shearing step (S) may be performed later. Then, the process proceeds to the second compression processing step (C2), where the stamped sealing plate 2 is further coined by a press device, and as shown in FIG. 14 to FIG. The groove 22 is formed along the contour surrounding the second predetermined region R2 near the bottom of the portion 23. Along with this, the bottom surface of the sealing plate 2 further bulges toward the opening, and a step 2d is formed near the skirt of the bulge 23 as shown in FIGS. As a result, it swells further in the opening direction than the swelling portion 23 shown in FIG. Therefore, the pressure receiving area of the bulging portion 23 is expanded accordingly.
It can easily be adjusted to break at low pressure.

The sealing plate 2 thus compressed is subjected to a heat treatment, specifically, an annealing treatment in the annealing step (A) of FIG. That is, after the sealing plate 2 is heated at a predetermined temperature, it is cooled for a predetermined time. As a result, the thickness of the groove 22 of the sealing plate 2 is set by a total of three times of compression and annealing, so that the breaking pressure can be finely adjusted and the breaking pressure can be easily adjusted to a low value. And the variation among products can be kept small.

[0032]

Since the present invention is configured as described above, the following effects can be obtained. That is, in the sealing plate of the sealed battery according to claim 1, a groove is formed on the surface of the metal plate along a contour surrounding a predetermined region, and the inside of the groove is formed on the surface side of the metal plate. Since the bulging portion is formed so as to bulge, the breaking pressure in the groove portion of the sealing plate can be easily adjusted by appropriately setting the thickness of the metal plate in the groove portion. In particular, the sealing plate is inexpensive because it is composed of only a single component formed of a metal plate, and a safety valve device for a sealed battery can be provided at low cost.

Further, in the sealing plate according to the second aspect, a concave portion is formed in a region of the surface of the metal plate including the groove and the bulging portion, and the groove and the bulging portion are formed on the bottom surface of the concave portion. Since it is configured to be formed, the breaking pressure at the groove portion of the sealing plate can be more easily adjusted by appropriately setting the thickness of the metal plate in the concave portion and the groove portion.

Furthermore, in the sealing plate according to the third aspect, since the metal plate is formed so as to form a groove by compressing and annealing, the breaking pressure at the groove portion of the sealing plate is set to a low value. And can be easily adjusted.

In the method of manufacturing a sealing plate according to a fourth aspect of the present invention, a groove is formed in the metal plate by compression, and a bulging portion bulging toward the surface of the metal plate inside the groove. Since the sealing plate can be manufactured only by pressing the single part, it can be manufactured at low cost. In addition, the thickness of the metal plate in the groove can be easily set, and the breaking pressure in the groove can be easily adjusted, so that the sealing plate can be manufactured at low cost.

Further, according to the manufacturing method of the fifth aspect, the concave portion and the groove are formed in the metal plate by compression, and the bulging portion bulging toward the surface side of the metal plate inside the groove. By appropriately setting the thickness of the metal plate in the concave portion and the groove portion sequentially, the breaking pressure at the groove portion can be more easily adjusted.

In the method for manufacturing a sealing plate according to the sixth aspect, since the metal plate is subjected to an annealing treatment in addition to the above-mentioned compression processing, the breaking pressure can be more easily adjusted and the breaking pressure can be reduced. Even if it is set to a low value, a stable product with small variation can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a sealed battery provided with a sealing plate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a sealed battery provided with a sealing plate according to an embodiment of the present invention, in which a battery component is omitted.

FIG. 3 is a process chart showing a method for manufacturing a sealing plate according to an embodiment of the present invention.

FIG. 4 is a front sectional view showing a state in which a concave portion is formed in the sealing plate in one embodiment of the present invention.

FIG. 5 is a plan view showing a state in which a concave portion is formed in the sealing plate in one embodiment of the present invention.

FIG. 6 is a side sectional view showing a state in which a concave portion is formed in the sealing plate in one embodiment of the present invention.

FIG. 7 is a front sectional view showing a state in which a concave portion, a groove, and a bulging portion are formed in a sealing plate in one embodiment of the present invention.

FIG. 8 is a plan view showing a state in which a concave portion, a groove, and a bulging portion are formed in a sealing plate in one embodiment of the present invention.

FIG. 9 is a side sectional view showing a state in which a concave portion, a groove, and a bulging portion are formed in a sealing plate in one embodiment of the present invention.

FIG. 10 is a process chart showing a method for manufacturing a sealing plate according to another embodiment of the present invention.

FIG. 11 is a front sectional view showing a state in which a concave portion and a bulged portion are formed in a sealing plate in another embodiment of the present invention.

FIG. 12 is a plan view showing a state in which a concave portion and a bulged portion are formed in a sealing plate in another embodiment of the present invention.

FIG. 13 is a side sectional view showing a state in which a concave portion and a bulged portion are formed in a sealing plate in another embodiment of the present invention.

FIG. 14 is a front sectional view showing a state in which a concave portion, a groove, and a bulging portion are formed in a sealing plate in another embodiment of the present invention.

FIG. 15 is a plan view showing a state in which a concave portion, a groove, and a bulging portion are formed in a sealing plate in another embodiment of the present invention.

FIG. 16 is a side sectional view showing a state in which a concave portion, a groove, and a bulging portion are formed in a sealing plate in another embodiment of the present invention.

FIG. 17 is a graph showing a measurement result of a breaking pressure of an example in the present invention.

[Explanation of symbols]

 Reference Signs List 1 container 2 sealing plate 2a flange portion 2b hole 2c thin plate portion 3 gasket 4 rivet terminal 21 concave portion 22 groove 23 bulging portion

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruo Sugita 18-1 Kanayama, Aizuma-cho, Chiryu-shi, Aichi Prefecture Inside (72) Inventor Shoichi Mikubo 18-1 Kanayama, Aizuma-cho, Chiryu-shi, Aichi Miyama Tool Inside the corporation

Claims (6)

[Claims] 1. A metal plate for closing an opening of a container of a sealed battery, wherein a groove is formed on a surface of the metal plate along a contour surrounding a predetermined region, and inside the groove, A sealing plate for a sealed battery, wherein a swelling portion swelling is formed on a surface side of the metal plate. 2. The method according to claim 1, wherein a concave portion is formed in a region of the surface of the metal plate including the groove and the bulging portion, and the groove and the bulging portion are formed on a bottom surface of the concave portion. A sealing plate for a sealed battery according to claim 1. 3. The sealed battery according to claim 1, wherein the metal plate is compressed to form the groove, the bulge is formed, and the metal plate is annealed. Sealing plate. 4. A groove is formed on the surface of the metal plate by compression working along a contour surrounding a predetermined area, and a bulging portion bulging toward the surface side of the metal plate inside the groove. Forming a sealing plate for a sealed battery. 5. A compression process on a first predetermined region of the metal plate to form a concave portion on the surface of the metal plate, and a compression process on the bottom surface of the concave portion along a contour surrounding the second predetermined region. Forming a groove on the inside of the groove, and a bulging portion bulging toward the surface of the metal plate inside the groove. 6. The method for producing a sealing plate for a sealed battery according to claim 4, wherein the metal plate is annealed.