JP2000040496A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve leakage liquid resistance by arranging the peripheral edge part extending almost vertically downward from the bending part and having no fold-back part on a sealing plate, setting a radius of curvature of the bending part smaller than the plate thickness of the sealing plate and not more than a specific value, and compressing the peripheral edge part of a gasket between the bending part and the opening end part of a case. SOLUTION: A positive electrode ring 7 and a positive electrode mix 5 are arranged in the center of a positive electrode case 2 also serving as a positive electrode terminal, a separator 6 composed of polypropylene nonwoven fabric is placed on it, and after injecting an electrolyte, the inside surface is coated with negative electrode metallic lithium 4, a sealing plate 1 having a gasket 3 installed in the peripheral edge part is combined with the positive electrode case 2, and the opening part of the positive electrode case 2 is calked/sealed in the peripheral edge part of the gasket 3. In this case, a radius of curvature of the bending part 1a of the sealing plate 1 is set smaller than a thickness of the sealing plate to be set not more than 0.15 mm, the opening end part 16 of the sealing plate 1 is compressed inside, and the taper part is arranged, so that a packing effect of the gasket 3 by calking/sealing can be maintained even in a bad environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a sealing plate, a positive electrode case,
The present invention relates to an improvement in a sealed battery in which a power generation element is liquid-tightly sealed with a gas and a gasket.

[0002]

2. Description of the Related Art Conventionally, in sealed batteries which have been used for a long period of time, such as coin-type lithium batteries of organic electrolyte type and button-type alkaline batteries, efforts have been made to increase the internal capacity of the batteries in order to increase the capacity. Was. As a method therefor, a sealing plate having no folded portion on the periphery has been adopted (for example, Japanese Patent Application Laid-Open No. 4-341756). The peripheral edge of this seed sealing plate is bent substantially vertically downward when it is lowered by one step. Regarding the shape of the bent portion of the sealing plate, a sealing method is adopted in which the sealing is performed by giving a radius concentric with or close to the R inside the positive electrode case and caulking and increasing the contact area with the gasket. It had been. In addition, the end portion of the portion that extends substantially vertically downward without a folded portion that continues in a U-shape at the periphery is also processed into a semicircle or a rounded shape having a curvature.

FIG. 7 shows the structure of a conventional battery using a coin-shaped lithium manganese dioxide battery as an example. FIG. 7 shows an example of a conventional coin-shaped lithium manganese dioxide battery having a diameter of 2 mm.
0.0mm, 3.2mm thick coin-shaped battery (CR203
2 shows the configuration of 2). The sealing plate 11 made of stainless steel has a plate thickness of 0.25 mm, and the bent portion 11a at the one-step lower portion has a radius of curvature R = 0.35 mm.
In addition, the opening end portion 11b of the sealing plate is machined outward with R = 0.40 mm. The opening of the positive electrode case 2 also serving as a positive electrode terminal made of stainless steel is closed by the sealing plate 11 and a gasket 3 made of a polyolefin resin such as polyethylene or polypropylene. In this sealed case, a negative electrode 4 using lithium metal as an active material, a positive electrode mixture 5 obtained by mixing a conductive agent such as graphite and a binder with manganese dioxide, and press-molding, and a nonwoven fabric of polypropylene The separator 6 is accommodated. Reference numeral 7 denotes a positive electrode ring made of stainless steel. Battery assembly consists of negative electrode 4, separator 6, positive electrode 5,
After filling the inside with the non-aqueous electrolyte, the open end of the case 2 is
This is performed by caulking and sealing the portion above 1a. Thus, the periphery of the gasket 3 is compressed between the bent portion 11a of the sealing plate 11 and the opening end of the case.

[0004]

When this sealing plate is used, since there is no U-shaped folded portion on the periphery,
The strength in the radial direction is weak, and the folded portion 11a of the sealing plate escapes inward of the battery at the time of caulking and sealing, and the degree of compression of the gasket portion is reduced, and the liquid leakage resistance is disadvantageously reduced. Also, the opening end portion 11b extending perpendicularly to the peripheral edge of the gasket portion in the vertical direction also decreases due to a decrease in the strength of the opening end portion of the sealing plate if the thickness of the sealing plate is simply reduced. Therefore, it has been a cause of a decrease in liquid leakage resistance. An object of the present invention is to solve such a problem and to provide a sealed battery having excellent leakage resistance.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a power generation system comprising a sealing plate, a bottomed cylindrical positive electrode case, and a gasket interposed between the sealing plate and the case. Sealing the element, the sealing plate has a peripheral portion that does not have a folded portion that extends substantially vertically downward from a bent portion that is connected to the peripheral edge of the main surface and that is one step below the main surface, and the folded portion and the case In a sealed battery in which the peripheral edge of the gasket is compressed between the open end and the gasket, the radius of curvature of the bent portion is smaller than the thickness of the sealing plate and 0.15 mm or less, or the bent portion is C1 or less. It is characterized by chamfering. Here, it is preferable that an opening end portion of the sealing plate is compressed inward to be provided with a taper portion.

[0006] By using this sealing plate, deformation of the bent portion of the sealing plate in the battery inner diameter direction is eliminated,
The reduction in the degree of gasket compression is reduced. In addition, by compressing the opening end portion of the sealing plate, the strength of the portion is increased, and the degree of compression in the battery vertical direction can be increased. In addition, the reason why the opening end of the sealing plate is compressed inward is that if the gasket and the sealing plate are fitted together, the gasket may be damaged or the sealant applied to the gasket may be scratched when there is an edge outside the opening. This is to prevent the liquid leakage resistance from dropping. Thus, according to the present invention,
The leakage resistance of the sealed battery is improved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view showing a coin-type lithium battery according to one embodiment of the present invention. A positive electrode ring 7 and a positive electrode mixture 5 are arranged at the center of a positive electrode case 2 also serving as a positive electrode terminal, a separator 6 made of a polypropylene non-woven fabric is placed thereon, and an electrolyte is injected. The sealing plate 1 on which the lithium 4 is adhered and the gasket 3 is mounted on the periphery is combined with the positive electrode case 2, and the positive electrode case 2
The gasket 3 is hermetically sealed by caulking the opening of the gasket 2 to the periphery of the gasket 3. The positive electrode mixture 5 is obtained by mixing manganese dioxide with graphite as a conductive agent and a binder, and subjecting the mixture to pressure molding.

FIGS. 2 to 6 show various modifications of the sealing plate. FIG. 2 shows an example in which the radius of curvature of the bent portion 1a of the sealing plate 1 is smaller than the thickness of the sealing plate and 0.15 mm or less. FIG. 3 shows a bent portion 1 a of the sealing plate 1.
Is a chamfer of C1 or less. FIG. 4 shows an example in which the opening end portion 1b of the sealing plate 1 is compressed inward to provide a taper portion. FIG. 5 shows that the radius of curvature of the bent portion 1a of the sealing plate 1 is smaller than the thickness of the sealing plate and 0.15 mm or less,
This is an example in which an opening end portion 1b of the sealing plate is compressed inward and a taper portion is provided. FIG. 6 shows the bent portion 1a of the sealing plate 1,
This is an example in which a chamfer of C1 or less is formed, the opening end portion 1b is compressed inward, and a tapered portion is provided.

[0009]

Example 1 Example 1 with a thickness of 0.25 mm and a bent portion 1
A coin-type lithium battery as shown in FIG. 1 was assembled using the sealing plate having the radius of curvature a of 0.10 mm.

Example 2 The conditions were the same as in Example 1 except that the radius of curvature of the bent portion 1a of the sealing plate was 0.15 mm.

Comparative Example 1 The conditions were the same as in Example 1 except that the radius of curvature of the bent portion 1a of the sealing plate was set to 0.20 mm.

Comparative Example 2 The same conditions as in Example 1 were used except that the radius of curvature of the bent portion 1a of the sealing plate was set to 0.25 mm.

<< Embodiment 3 >> The bent portion 1a of the sealing plate is C
Except for chamfering 1, the same conditions as in Example 1 were used.

<< Comparative Example 3 >> The bent portion 1a of the sealing plate was
The conditions were the same as in Example 1, except that the chamfer was 1.5.

<< Comparative Example 4 >> The bent portion 1a of the sealing plate was
Except for chamfering No. 2, the same conditions as in Example 1 were used.

Example 4 The same conditions as in Example 1 were adopted except that the opening end portion of the sealing plate was compressed inward by 30% to 50% of the plate thickness and the angle of the taper portion was set to 30 ° or more. did.

<< Embodiment 5 >> The radius of curvature of the bent portion 1a of the sealing plate is set to 0.10 mm, and the opening end of the sealing plate is compressed inward by 30 to 50% of the plate thickness, and the angle of the taper portion is reduced. 30
The conditions were the same as in Example 1 except that the temperature was not less than the above.

<< Embodiment 6 >> The bent portion 1a of the sealing plate is
The same conditions as in Example 1 were used except that the chamfer of No. 1 was used, the opening end of the sealing plate was compressed inward by 30 to 50% of the plate thickness, and the angle of the taper portion was set to 30 ° or more.

Comparative Example 5 The same conditions as in Example 1 were used except that a conventional sealing plate was used.

The above 11 types of batteries are constituted by 100 each,
A thermal shock cycle of holding at 85 ° C. for 1 hour and then at −10 ° C. for 1 hour was performed for 360 cycles, and the leakage generation rate was examined. Table 1 shows the results.

[0021]

[Table 1]

As shown in Table 1, the folded portion 1 of the sealing plate
By setting the radius of curvature of a to 0.15 mm or less, the liquid leakage resistance is improved. However, it can be seen from the results of the liquid leakage tests of Comparative Examples 1 and 2 that when the radius of curvature of the bent portion 1a of the sealing plate exceeds 0.15 mm, the liquid leakage resistance is greatly reduced. Also, the bent portion 1a of the sealing plate
The leakage resistance is also improved by chamfering C1. From the results of the liquid leakage tests of Comparative Examples 3 and 4, it was found that the resistance to liquid leakage was reduced in the portion where the chamfer size exceeded C1. Next, in the case where the opening end portion 1b is compressed inward and a sealing plate provided with a taper portion is used, the fourth embodiment is also applicable.
As shown in the figure, an improvement in liquid leakage resistance is observed. Further, the bent portion 1a of the sealing plate having a radius of curvature smaller than the thickness of the sealing plate and processed to 0.15 mm, and the bent portion 1a of the sealing plate obtained by chamfering C1 are further opened. When the end portion 1b is compressed inward and a tapered portion is provided, as shown in Examples 5 and 6, the leakage resistance is significantly improved as compared with Comparative Example 5 using the conventional sealing plate. Understand. In the above embodiment, an example in which the present invention is applied to a coin-type lithium manganese dioxide battery has been described.However, the present invention is applicable to other coin-type lithium primary batteries, coin-type lithium secondary batteries, button-type alkaline batteries, alkaline secondary batteries, and the like. Can be similarly applied.

[0023]

As described above, according to the present invention, it is possible to provide a sealed battery excellent in liquid leakage resistance while maintaining the packing effect of the gasket by swaging and sealing under a severe thermal shock environment.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a coin-type lithium battery according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of a sealing plate in which a bent portion is rounded.

FIG. 3 is a sectional view of a principal part of a sealing plate in which a bent portion is chamfered.

FIG. 4 is a cross-sectional view of a main part of a sealing plate in which an opening end portion is compressed inward and a taper portion is provided.

FIG. 5 is a cross-sectional view of a main part of a sealing plate provided with a taper portion, in which a bent portion is rounded and an opening end portion is compressed inward.

FIG. 6 is a cross-sectional view of a principal part of a sealing plate provided with a taper portion by chamfering a bent portion and compressing an opening end portion inward.

FIG. 7 is a half sectional view of a conventional coin-shaped lithium battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing plate 1a Bending part 1b Open end 2 Positive electrode case 3 Gasket 4 Negative electrode 5 Positive electrode mixture 6 Separator 7 Positive electrode ring

Continuation of the front page (72) Inventor Susumu Yamanaka 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Mitsugu Okahaku 1006 Odaka, Kazuma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. Reference) 5H011 AA17 CC06 DD06 DD15 KK03

Claims (3)

[Claims] 1. A sealed battery in which a power generation element is sealed by a sealing plate, a bottomed cylindrical positive electrode case, and a gasket interposed between the sealing plate and the case, wherein the sealing plate is provided. But,
A peripheral portion that has no folded portion extending substantially vertically downward from a bent portion that is continuous with the peripheral edge of the main surface and that is one step lower than the main surface, the radius of curvature of the bent portion is smaller than the thickness of the sealing plate, and A sealed battery having a diameter of not more than 15 mm and a peripheral portion of the gasket being compressed between the bent portion and an opening end of the case. 2. A sealed battery in which a power generating element is sealed by a sealing plate, a bottomed cylindrical positive electrode case, and a gasket interposed between the sealing plate and the case, wherein the sealing plate is provided. But,
It has a peripheral portion that does not have a folded portion that extends substantially vertically downward from a bent portion that is one step below the main surface and that is continuous with the peripheral edge of the main surface, and the bent portion is chamfered to C1 or less. Sealed batteries. 3. The sealed battery according to claim 1, wherein an opening end portion of the sealing plate is compressed inward to provide a taper portion.