JP3625608B2 - Sealing method of sealed battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a sealing method for a sealed battery, and more particularly to a sealing method for a sealed battery that does not leak from a caulked portion.
[0002]
[Prior art]
The sealed battery is manufactured by putting an electrode or an electrolyte in an outer can and then hermetically sealing the opening with a sealing plate. The opening of the outer can is caulked with the outer can and the sealed can and the sealing plate, and a gasket is sandwiched between the outer can and the outer can. The sealing method in which the outer can is caulked and hermetically sealed, for example, has an advantage that the outer can can be efficiently sealed as compared with a sealing method in which the periphery of the sealing plate is laser-welded to the opening of the outer can.
[0003]
It is important for the sealing method by caulking to have a structure in which the outer can and the sealing plate are hermetically sealed to prevent leakage. For this reason, various investigations and improvements have been made, such as selecting a sealant and improving the shape of the gasket, but the actual situation is that ideal leakage resistance is not obtained. In order to obtain sufficient liquid leakage resistance, various improvements have been made, such as increasing the accuracy of the sealing shape. However, even with this method, sufficiently satisfactory leakage resistance is not realized.
[0004]
In particular, the method of caulking and sealing the outer can is a spring back of the outer can that has been deformed by being pressed by a sealing mold, and has a property that the liquid leakage property is deteriorated. Considering the spring back, if the outer can is strongly deformed with the sealing mold, there is a problem that an extra impact is applied to the gasket. In the method of caulking and sealing the outer can, the gasket is sandwiched between the outer can and the sealing plate to seal it hermetically, so that damage to the gasket deteriorates leakage resistance.
[0005]
As a method for improving such defects, a method has been developed in which a sealing mold presses and crimps an outer can twice or more (Japanese Patent Laid-Open No. 59-224046). The sealing method described in this publication takes into account the spring back of the outer can and presses and crimps the outer can with a sealing mold twice or more.
[0006]
[Problems to be solved by the invention]
The sealing method in which the sealing mold caulks the outer can multiple times to reduce the spring back can improve the leakage resistance compared to the method in which the sealing mold caulks the outer can once. However, this sealing method has a drawback in that it is difficult to efficiently mass-produce and the productivity is lowered because the outer can is caulked by stroking the sealing mold a plurality of times.
[0007]
The present invention has succeeded in improving the leakage resistance in a very simple manner, and an important object of the present invention is to improve the leakage resistance, and in addition, the sealed battery can be sealed efficiently in a short time. It is to provide a sealing method.
[0008]
[Means for Solving the Problems]
The sealing method of the present invention is an improvement of a method in which a metal plate outer can 1 is caulked, a gasket 7 is sandwiched between the sealing plate 6 and the outer can 1, and the opening of the outer can 1 is hermetically sealed with the sealing plate 6. It is a thing. In the sealing method of the present invention, the caulking operation is not performed a plurality of times, but at the position where the caulking die 12 of the sealing die 8 is crushing the outer can 1 most thinly during the sealing operation, It is characterized by holding for at least 2 seconds.
[0009]
Furthermore, in the sealing method of claim 2 of the present invention, in the sealing operation in which the sealing die 8 caulks the outer can 1, the moving speed at which the caulking die 12 descends while caulking the outer can 1 is more than 20 mm / second. Slow down.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify the sealing method for embodying the technical idea of the present invention, and the present invention does not specify the sealing method as described below.
[0011]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0012]
FIG. 1 shows a button battery which is a sealed battery sealed by the sealing method of the present invention. In this sealed battery, an electrode group 5 in which a separator 4 is disposed between a positive electrode plate 2 and a negative electrode plate 3 and an electrolytic solution are placed in an outer can 1, and an opening of the outer can 1 is then sealed with a sealing plate 6. Is hermetically sealed.
[0013]
The outer can 1 and the sealing plate 6 are metal plates, and the outer can 1 is caulked, and the gasket 7 is sandwiched between the outer can 1 and the sealing plate 6 to hermetically seal the opening. The gasket 7 is sandwiched between the outer can 1 and the sealing plate 6 and elastically deformed, and is hermetically sealed and sealed to the outer can 1 and the sealing plate 6. Further, the gasket 7 also functions to insulate the outer can 1 as a positive electrode from the sealing plate 6 as a negative electrode.
[0014]
The sealed battery shown in FIG. 1 is sealed by caulking the outer can 1 with a sealing mold 8 shown in FIGS. The sealing mold 8 in this figure includes a lower mold 8A and an upper mold 8B. The lower mold 8A includes a fixed mold 9 and a peripheral wall mold 10 disposed around the fixed mold 9 so as to be movable in the vertical direction. The peripheral wall mold 10 is elastically pushed up by a spring 13. The upper mold 8 </ b> B includes a central mold 11 that presses the upper surface of the sealing plate 6, and a crimping mold 12 that is disposed around the central mold 11. The central mold 11 is connected to the caulking mold 12 via a spring 14 so as to be movable in the vertical direction. The caulking die 12 is connected to a cylinder and is pushed down by the cylinder. The caulking die 12 has a caulking surface 12A that is curved on the inner surface of the lower end so that the upper end edge of the outer can 1 can be bent inward. The central mold 11 is disposed inside the caulking surface 12A.
[0015]
The mold shown in these figures is sealed by caulking the outer can in the following steps.
(1) As shown in FIG. 2, the peripheral wall mold 10 of the lower mold 8 </ b> A is pushed up by a spring 13 and is positioned higher than the fixed mold 9. Set 1 In the outer can 1, an electrode group 5, an electrolytic solution, and a gasket 7 are placed, and a sealing plate 6 is placed at a fixed position on the gasket 7.
[0016]
(2) As shown in FIG. 3, when the caulking die 12 is pushed by the cylinder and starts to descend, the caulking die 12 is pushed and the peripheral wall die 10 of the lower die 8A is lowered. Since the central mold 11 is connected to the caulking mold 12 by a spring 14, when the caulking mold 12 is lowered, the central mold 11 is also lowered. When the center mold 11 is lowered to a position where the upper surface of the sealing plate 6 is pressed, the center mold 11 does not descend. However, since the center die 11 is connected to the caulking die 12 by the spring 14, the upper surface of the sealing plate 6 is elastically pressed when the caulking die 12 is lowered. Therefore, when the caulking die 12 is lowered, the center die 11 presses the upper surface of the sealing plate 6. The sealing plate 6 to be pressed elastically presses the lower surface of the gasket 7 against the bottom surface of the outer can 1 so that the gasket 7 and the bottom surface of the outer can 1 are tightly adhered.
[0017]
(3) As shown in FIG. 4, when the caulking die 12 is further lowered, the upper edge of the outer can 1 is bent inward along the caulking surface 12 </ b> A of the caulking die 12. The descending caulking die 12 is gradually lowered while lowering the peripheral wall die 10, and the upper end edge of the outer can 1 is bent and caulked by the caulking surface 12A. If it will be in this state, since the center of the sealing board 6 will protrude rather than the upper end edge of the crimped exterior can 1, the lower surface of the center metal mold | die 11 is pushed up rather than the crimping surface 12A.
[0018]
(4) As shown in FIG. 5, after the opening of the outer can 1 is caulked, the upper mold 8B is raised, and the sealed sealed battery is taken out from the lower mold 8A.
[0019]
FIG. 6 shows the lowering speed of the upper mold 8B that is lowered in the above process. When the caulking die 12 is lowered, until the center die 11 presses the upper surface of the sealing plate 6 or until the caulking surface 12A of the caulking die 12 starts to bend the upper end portion of the outer can 1. Almost no load. For this reason, the caulking die 12 is lowered to this position at a high speed from a to b in FIG. When the center mold 11 presses the upper surface of the sealing plate 6 and the caulking mold 12 bends the upper end of the outer can 1 inward, the lowering speed of the caulking mold 12 is reduced. This is because the descending speed at this time affects the caulking state of the outer can 1. In FIG. 6, the descending speed of the caulking die 12 is decreased from b to c.
[0020]
FIG. 7 shows the sealing dimension with respect to the speed at which the caulking mold 12 descends while caulking the outer can 1, that is, the descending speed until the caulking mold 12 descends from b to c in FIG. 6. However, the sealing dimension is a dimension from the bottom surface of the outer can 1 to the upper end of the outer can 1 as shown by an arrow D in FIG. When the spring back of the outer can 1 is increased, the sealing dimension is increased. Therefore, when the sealing dimension is small, the spring back is small, which indicates that the sealing is more reliably performed. The sealing dimension in this figure was measured with 0.2 seconds as the time during which the caulking mold descended most and the outer can was crushed most thinly. This figure clearly shows that when the lowering speed of the caulking mold is made slower than 20 mm / second, the sealing dimension is reduced and the sealing can be surely performed. Accordingly, the caulking die 12 is lowered at a speed that is preferably slower than 20 mm / second, more preferably slower than 10 mm / second.
[0021]
Further, FIG. 8 shows that when the caulking die 12 holds the outer can 1 in the position where the outer can 1 is most thinly crushed, if the time from c to d in FIG. 6 is increased, the sealing dimension becomes smaller and more reliably. Indicates that it can be sealed. In this figure, however, the speed at which the caulking mold descends while caulking the outer can was measured as 10 mm / sec. This figure shows that when the caulking die is held at the position where the outer can is most thinly crushed for longer than 0.1 seconds, the sealing size becomes smaller and the outer can is more reliably sealed. Indicates that Therefore, in the sealing method of the present invention, the time during which the outer can 1 is crushed most thinly with the caulking die 12 is longer than 0.1 seconds, more preferably longer than 0.2 seconds.
[0022]
【Example】
[Example]
300 sealed batteries having the structure shown in FIG. 1 were manufactured under the following conditions. However, the prototype battery was manufactured by setting the descent speed of the caulking mold and the holding time as follows in FIG.
Caulking mold lowering speed between a and b ... 60 mm / sec. Caching mold lowering speed between b and c ... Caching mold holding time between 5 mm / sec and cd ... 0.3 sec de Ascending speed of crimping die ... 60mm / sec. [0023]
[Comparative Example 1]
300 sealed batteries having the structure shown in FIG. 1 were manufactured under the following conditions. However, the prototype battery was manufactured by setting the descent speed of the caulking mold and the holding time as follows in FIG.
Descent speed of caulking mold between a and b ... 60 mm / sec. descent speed of caulking mold between b and c ... Retention time of caulking mold between 60 mm / sec and cd ... Caching between 0 sec and d Mold ascending speed: 60 mm / sec. [0024]
[Comparative Example 2]
Furthermore, although the same caulking method as the sealing method of Comparative Example 1 was used, 300 comparative batteries were prototyped with the caulking frequency set to two.
[0025]
The leakage resistance test of the battery sealed by the above method was measured under the following conditions (1) and (2).
(1) Number of leaking batteries after being left at 60 ° C. for 200 days (2) Number of leaking batteries after a cycle test of 60 ° C. to −20 ° C. for 100 days in one cycle every day
As a result of the liquid leakage resistance test, the number of liquid leaks in the batteries of Examples and Comparative Examples 1 and 2 was as follows.
Number of leaks in the test of the battery of the example (1) ………… 0/300 pieces Number of leaks of the test in the battery of the example (2) ………… 0/300
Number of liquid leaks in test (1) of battery of Comparative Example 1 ... 1/300 pieces Number of liquid leaks in test (2) of battery of Comparative Example 1 ... 3/300 pieces
Number of leaks in test (1) of battery of comparative example 2 ... 0/300 Number of leaks of test in battery of comparative example 2 (2) ... 2/300
As described above, 300 batteries sealed by the sealing method of the present invention were produced on a trial basis, and none of the batteries leaked in the environments (1) and (2). On the other hand, the battery of Comparative Example 1, that is, the battery prototyped by the method in which the caulking mold is not held at the position where the outer can is crushed thinnest, is 300 in the test of (1), and one is leaked. However, in the test of (2), three of the 300 leaked. Furthermore, the battery of Comparative Example 2, that is, the battery in which the outer can was crimped twice and sealed, did not leak in 300 pieces in the test of (1), but in the test of (2), 2 pieces of 300 pieces were leaked. Leaked.
[0030]
【The invention's effect】
The sealing method of the sealed battery of the present invention has an advantage that the leakage of the manufactured battery can be extremely reduced by an extremely simple method. Furthermore, in addition to this feature, the sealing method of the present invention also realizes a feature that can efficiently seal the outer can in a short time. This is because the sealing method of the present invention does not need to be caulked by a sealing mold repeatedly in a plurality of times as in the prior art, and can be reliably sealed by a single caulking operation. In particular, the sealing method of the present invention realizes the performance that can significantly improve the liquid leakage characteristics by a very simple method of extending the thinnest crushing time of the outer can with a sealing mold by only 0.1 seconds. Is done. For this reason, the feature which can seal an exterior can in an ideal state is realized, extending the time which seals one exterior can almost.
Furthermore, according to the sealing method of claim 2 of the present invention, since the moving speed at which the sealing die is clamped while pressing the outer can is made slower than 20 mm / second, a further excellent liquid leakage characteristic can be realized. is there.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a sealed battery that is sealed by a sealing method according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a process for sealing a sealed battery by caulking an outer can. FIG. FIG. 4 is a cross-sectional view showing the process of sealing the sealed battery by caulking the outer can. FIG. 5 is a cross-sectional view showing the process of sealing the sealed battery by caulking the outer can. FIG. 7 is a graph showing the relationship between the position of the sealing mold and the elapsed time in the steps shown in FIG. 2 to FIG. 5. FIG. 7 is a graph showing the relationship between the descent speed of the sealing mold and the sealing dimension. Graph showing the relationship between retention time and sealing dimensions when the outer can is crushed thinnest
DESCRIPTION OF SYMBOLS 1 ... Exterior can 2 ... Positive electrode plate 3 ... Negative electrode plate 4 ... Separator 5 ... Electrode group 6 ... Sealing plate 7 ... Gasket 8 ... Sealing die 8A ... Lower die 8B ... Upper die 9 ... Fixed die 10 ... Perimeter wall die Mold 11 ... Center mold 12 ... Caulking mold 12A ... Caulking surface 13 ... Spring 14 ... Spring

Claims (2)

The metal plate outer can (1) is caulked with the sealing die (8) caulking die (12 ), and the gasket (7) is sandwiched between the sealing plate (6) and the outer can (1), and the sealing plate ( 6) Sealing the sealed battery in which the opening of the outer can (1) is hermetically sealed , and the upper edge of the outer can (1) is folded inward at the caulking surface (12A) of the caulking mold (12). In the sealing method to bend and squeeze ,
During the sealing operation, the sealing mold (8) is held at the position where the outer can (1) is most thinly crushed, and is held for 0.1 second or longer to reduce the spring back of the outer can (1). Sealing method for sealed battery. In the sealing work in which the sealing mold (8) caulks the outer can (1),
2. The spring back of the outer can (1) is reduced by reducing the moving speed of the caulking mold (12) descending while caulking the outer can (1) to be lower than 20 mm / second. Sealing method for sealed battery.

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