JP4290633B2 - Sealed battery - Google Patents

Description

  The present invention relates to a sealed battery, and more particularly, to a sealed battery with good sealing characteristics characterized by a sealed portion in which an electrolytic solution injection port is sealed after an electrolytic solution is injected.

Portable electronic devices are becoming smaller and lighter and have advanced functions. As a result, batteries for power supplies used in these electronic devices are required to be small, light and large in capacity per volume.
Lithium ion batteries using positive and negative active materials doped and dedoped with lithium ions have a higher energy density per volume or mass than conventional nickel cadmium and lead batteries. As a secondary battery, it is used as a power source for small electronic devices.

A lithium ion battery is manufactured by winding a positive electrode and a negative electrode through a separator, or a battery element in which a positive electrode and a negative electrode are stacked in a metal battery outer container. Is attached with a lid provided with an electrode having different polarities insulated by an insulating member to seal the meeting portion between the battery outer container and the lid.
Next, after a predetermined amount of electrolytic solution is injected from the electrolytic solution injection port, a sealing body is attached to the electrolytic solution injection port and welded by laser welding or the like to be integrated and sealed.
When welding with laser welding, etc., the battery internal pressure increases due to the heat of welding, resulting in the electrolyte being injected from the electrolyte injection port, or the injected electrolyte being attached, resulting in insufficient welding and poor sealing Sometimes occurred.

FIG. 4 is a diagram for explaining a conventional electrolytic solution pouring method and a sealing step.
4A is a perspective view, and FIGS. 4B to 4D are enlarged views of the cross section of the electrolyte injection port.
When the electrolytic solution 10 is injected from the electrolytic solution injection port 5 to the sealed battery 1 as shown in FIG. 4B, the electrolytic solution adheres to the electrolytic solution injection port 5 and its peripheral portion, Alternatively, when the sealing body 15 is press-fitted as shown in FIG. 4 (C), and the laser 9 is irradiated to the meeting part of the sealing body 11 and the battery header 3 as shown in FIG. 4 (D), FIG. A pinhole is generated by the electrolytic solution 10 ejected when the sealing body 11 shown in FIG. 1 is injected, or a product decomposed by the laser irradiation, or an ejection 12 of the electrolytic solution is generated by an increase in internal pressure caused by a temperature rise due to laser irradiation. Sealing failure sometimes occurred.

Therefore, in order to prevent the sealing body from falling off when the pressure inside the battery outer container rises, the elastic body is used as a sealing body for the electrolyte solution inlet, and the surface of the battery outer container or the surface of the battery outer container is used. A sealed battery in which a sealing lid is attached by laser welding has been proposed (for example, Patent Document 1).
However, the sealing body made of an elastic material such as rubber is not sealed properly because the electrolyte is ejected from the inside of the battery which has been softened by the heat applied during welding and the internal pressure is increased, and the sealing lid is insufficiently welded. Could occur.
JP-A-11-273638

  The present invention provides a sealed battery in which a sealing body is attached to an electrolyte solution injection port and sealed so that welding failure does not occur due to the injection of the electrolyte due to heat applied at the time of sealing. Is an issue.

The problem of the present invention is that, in a sealed battery, an electrolyte injection port provided on the wall surface or battery header of the battery outer container is provided on the outer side of the battery outer container that communicates with the small diameter part facing the inner side of the battery outer container. A metal first sealing body is inserted into the small diameter portion, and both sides of the central portion or the side facing the inside of the battery outer container are thinner than the surroundings. This can be solved by a sealed battery in which the second sealing body is welded and sealed.
The small diameter part and the large diameter part of the electrolyte solution injection port are the above-described sealed type battery which communicates with each other through a step part.

  The sealed battery of the present invention has a small diameter portion and a large diameter portion formed in the electrolyte injection port, and after the metal first sealing body is mounted on the small diameter portion, the second sealing body is mounted on the large diameter portion. Therefore, since there is no discharge of the electrolyte from the electrolyte injection port due to a rise in pressure inside the battery outer container at the time of thermal fusion by laser welding, sealing the electrolyte injection port In this case, no pinhole or the like is generated, and a sealed battery having excellent sealing characteristics can be obtained.

  The present invention inserts a sealing body into an electrolytic solution injection port provided on the can wall surface of the battery outer container or an electrolytic solution injection port provided on a battery header attached to the opening of the battery outer container. It is an object of the present invention to provide a sealed battery in which a sealing failure of an electrolyte solution injection port that occurs when a meeting portion with a wall surface of the electrolyte solution injection port is welded is prevented. That is, after mounting the metal first sealing body, by mounting and welding the second sealing body, the pressure in the battery outer container rises due to the heat applied at the time of welding, and the electrolyte is ejected. It has been found that it is possible to prevent this.

  A sealed battery in which an elastic body such as rubber is attached to the inside of the electrolyte injection hole, a metal sealing body is attached to the outside, and the outer metal sealing body is welded to the wall of the electrolyte injection hole However, it is known that an elastic body such as rubber attached to the electrolyte injection port reliably prevents the electrolyte from being ejected when the internal pressure increases due to the temperature increase caused by the heat applied during welding. Although it was difficult, as in the present invention, the electrolyte injection hole was formed from a small diameter part facing the inside of the battery outer container and a large diameter part facing the outer side of the battery outer container, and the small diameter part was made of metal. After sealing the small diameter part by inserting the first sealing body made of metal, the second sealing body is attached to the large diameter part, welded and sealed, so that the electrolyte is ejected due to an increase in internal pressure due to heating during welding. It provides a sealed battery that reliably prevents, has good sealing characteristics, and is free from contamination by the electrolyte in the sealing process. .

The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a sealed battery according to the present invention.
FIG. 1A is a perspective view illustrating a sealed battery. FIG. 1B is a plan view of the sealed battery as viewed from above, and FIG. 1C is a cross-sectional view taken along line AA ′ in FIG. FIG.
In the sealed battery 1 of the present invention, after the battery element is stored in the battery outer container 2, the battery header 3 is attached to the opening of the battery outer container 2, and the battery header 3 has the electrode terminal 4 at the center. And an electrolyte solution injection port 5.

The electrolyte solution injection port 5 includes a small-diameter portion 5a on the inner side of the battery outer casing 2 and a large-diameter portion 5b on the outer side, and the small-diameter portion 5a and the large-diameter portion 5b communicate with each other through a step portion 5c.
A metal first sealing body 6 is inserted and sealed in the small diameter portion 5a, and a second sealing body 7 is inserted in the large diameter portion 5b. In addition, the meeting portion between the second sealing body 7 and the battery header 3 is securely sealed by forming a fused portion 8 melt-sealed by laser irradiation.

The first sealing body 6 is made of metal and may be either the same material as the material of the battery outer container or a different material.
In addition, the first sealing body 6 has a spherical or cylindrical member having an outer diameter larger than the inner diameter of the small diameter portion 5a so that the electrolyte injection port can be reliably sealed in the small diameter portion 5a. Used.
Further, when the first sealing body 6 is inserted into the small-diameter portion 5a and sealed, it is preferable to determine the size so that the first sealing body 6 does not protrude upward or the amount of protrusion is small.

  Since the small diameter portion 5a and the large diameter portion 5b of the electrolyte solution injection port 5 are joined by the step portion 5c, when the second sealing body 7 is attached to the large diameter portion 5b and the laser 9 is irradiated, The straightly traveling laser 9 is blocked by the step portion 5c, and the small diameter portion 5a or the first sealing body 6 is not irradiated with the laser, and the heating of the electrolyte solution by the laser irradiation can be prevented.

FIG. 2 is a diagram for explaining an embodiment of the present invention. FIG. 2 (A) is a cross-sectional view showing an example of an electrolyte injection port, and FIG. 2 (B) is a plan view of a second sealing body attached to the electrolyte injection port of FIG. 2 (A). FIG. 2C is a cross-sectional view of another example of the electrolyte solution injection port.
The small-diameter portion 5a of the electrolyte solution injection port 5 shown in FIG. 2 (A) is connected to the large-diameter portion 5b facing outward through a step portion 5c.
The first sealing body 6 attached to the small-diameter portion 5a is formed by press-fitting a spherical body or the like from above to seal the small-diameter portion 5a, but the first sealing body 6 is made larger than the diameter of the small-diameter portion 5a. Has been. Moreover, since the wall surface is hardened by work hardening at the time of formation of the small diameter portion 5a, when the first sealing body 6 made of the same metal material as the material forming the small diameter portion is press-fitted, the first sealing body 6 is deformed and held on the wall surface of the small-diameter portion 5a having a large hardness and is securely sealed.

Further, as shown in FIGS. 2A and 2B, the second sealing body 7 attached to the large-diameter portion 5b has circular concave portions 7a and 7b at the central portion. It is thinner than the surroundings.
Thereby, it is possible to prevent mutual interference between the first sealing body and the second sealing body while maintaining sufficient sealing characteristics, and at the same time, the amount of protrusion of the second sealing body from the outer surface of the battery outer container. Can be small.

The recess formed in the second sealing body can achieve the purpose even if it is formed only on the inner surface side that may collide with the first sealing body 6, but when mounting the second sealing body 7, Since it is necessary to always attach the surface on which the concave portion is formed to be on the stepped portion side, it is preferable to form symmetrical concave portions on both sides in order to easily and reliably realize the assembly process.
By using a member formed with concave surfaces on both sides and in point-symmetric positions as the second sealing body, a step of directing a specific surface toward the stepped portion during assembly can be omitted.

FIG. 2C is a view for explaining another embodiment of the present invention. The first sealing body 6 made of a spherical body is press-fitted from the upper portion of the small diameter portion 5a and sealed. The small diameter portion 5a is formed with a tapered portion 5d having a larger diameter toward the upper portion.
The tapered portion 5d is not limited to the one having a uniform inclined surface as shown in FIG. 2C, and may be formed from a plurality of inclined surfaces having different inclinations. good. Further, the tapered portion 5d may be connected to the cylindrical portion at the lower portion thereof.

  Moreover, since the wall surface of the small diameter part 5a is hardened by work hardening at the time of processing the small diameter part 5a, when the first sealing body 6 is press-fitted, the first sealing body is deformed by the wall surface and the small diameter part Can be realized. When the tapered portion 5d is formed in the small diameter portion 5a, the first sealing body 6 that is sufficiently larger than the minimum diameter of the lower portion of the tapered portion 5d can be used. As a result, when the first sealing body 6 is press-fitted, it is possible to prevent the first sealing body 6 from dropping from the lower end portion of the small diameter portion 5a even if abnormal conditions or the like occur in the press-fitting. Furthermore, since the amount of the first sealing body that is press-fitted into the small-diameter portion can be increased because the tapered portion exists, the amount of protrusion of the first sealing body 6 to the upper portion of the small-diameter portion can be reduced. It becomes possible, and it becomes possible to increase the degree of freedom in the sealing step, such as increasing the thickness of the second sealing body.

FIG. 3 is a diagram for explaining an example of a method for forming an electrolyte injection hole, and is a cross-sectional view for explaining a process for forming an electrolyte injection hole on a metal plate of a battery header.
FIG. 3A is a diagram for explaining a process of forming a large diameter portion, and a large diameter portion 5b and a stepped portion 5c are formed by a spot facing jig 13 at a predetermined position of a metal plate 3 for forming a battery header. Then, as shown in FIG. 3B, when the small diameter portion 5a is formed by the hole forming jig 14 and the tapered portion is formed above the small diameter portion 5a, the taper is formed after the small diameter portion 5a is formed. It can be formed by a jig.
Examples of the present invention will be described below to explain the present invention.

The battery outer case of an aluminum lithium ion battery having a width of 34 mm, a height of 50 mm, and a thickness of 4 mm has a small diameter portion on the side of the battery outer container of 0.6 mm in diameter and a length or depth of 0.5 mm. An electrolyte injection hole was formed in which a planar step portion having a diameter of 2 mm and a depth of 0.5 mm on the outer surface side of the container was coupled.
Using a mixed solvent in which diethyl carbonate (DEC) and ethylene carbonate (EC) were mixed at a volume ratio of 5: 3 (volume ratio) as a solvent, an electrolytic solution containing lithium hexafluorophosphate as an electrolyte was injected from the injection port. .

After the injection, a spherical body made of aluminum having a diameter of 0.7 mm is press-fitted into the small-diameter portion, and then the diameter of 2 mm, the thickness of 0.5 mm, and both sides of the center are inserted into the large-diameter portion of the electrolyte injection port. After attaching a second sealing member made of aluminum in which a recess having a depth of 0.2 mm and an equal diameter of 1.2 mm is attached, a laser is irradiated to the meeting portion between the second sealing member and the electrolyte injection port. And sealed.
Regarding the 500 lithium ion batteries produced, it was confirmed whether or not the pinholes were formed in the sealing portion by laser welding, and no pinholes were generated.

Comparative Example 1
A sealed battery was fabricated in the same manner as in Example 1 except that an EPMA rubber sealing body having a diameter of 1 mm and a length of 0.5 mm was attached to the small diameter portion as the first sealing body.
When the pinhole of the sealing part was confirmed about the produced 500 lithium ion battery, the pinhole had arisen about one.

  In the sealed battery of the present invention, the electrolyte injection hole is formed with a small diameter portion and a large diameter portion, and a metal first sealing body is attached to the small diameter portion and sealed, and then the second sealing body is formed on the large diameter portion. Was attached and heat-sealed by laser welding, so at the time of heat-sealing by laser, there was no ejection of the electrolyte from the electrolyte injection port, and a pinhole or the like was generated when the electrolyte injection port was sealed There is no such thing and the thing with the outstanding sealing characteristic can be obtained.

FIG. 1 is a diagram illustrating an example of a sealed battery according to the present invention. FIG. 2 is a diagram for explaining an embodiment of the present invention. FIG. 3 is a diagram for explaining an example of a method for forming an electrolytic solution injection port. FIG. 4 is a diagram for explaining a conventional electrolytic solution pouring method and a sealing step.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sealed battery, 2 ... Battery exterior container, 3 ... Battery header, 4 ... Electrode terminal, 5 ... Electrolyte injection port, 5a ... Small diameter part, 5b ... Large diameter part, 5c ... Step part, 5d ... Tapered part , 6 ... 1st sealing body, 7 ... 2nd sealing body, 7a, 7b ... Recessed part, 8 ... Fusion part, 9 ... Laser, 10 ... Electrolytic solution, 11 ... Sealing body, 12 ... Ejection of electrolytic solution, 13 ... Counterbore jig, 14 ... hole forming jig

Claims (2)

In a sealed battery, the electrolyte injection hole provided on the wall of the battery outer container or the battery header has a small diameter portion facing the inside of the battery outer container, and a large diameter portion facing the outer side of the battery outer container communicating with the small diameter portion. A first sealing body made of metal is inserted into the small diameter portion, and a second sealing body having a smaller thickness than the surroundings on both sides of the central portion or the inside of the battery outer container is inserted in the large diameter portion. A sealed battery, which is welded and sealed. 2. The sealed battery according to claim 1, wherein the small-diameter portion and the large-diameter portion of the electrolyte solution injection port communicate with each other through a step portion.

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