JP2008147069A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery without generating welding failure by electrolyte leakage caused by heat applied when an electrolyte pouring hole is sealed by fitting a sealing plug to the electrolyte pouring hole in the sealed battery. <P>SOLUTION: In the sealed battery fitting the sealing plug 1 having a flange part 11 formed by inserting a cylindrical projection part 12 to the pouring hole 7 of an electrolyte having a step part 71 formed in a battery can made of an aluminum alloy or a cover 2 for sealing an opening part of the battery can, and sealing the pouring hole by welding, the sealing plug having a collar part 41 on the outer circumferential surface of the flange part 11 is used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rectangular sealed battery, and more particularly to a sealed battery such as a lithium ion battery characterized by a sealing plug that seals a liquid injection hole after injecting the electrolyte.

  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 electrode active materials and negative electrode active materials doped and dedoped with lithium ions have a higher energy density per volume or mass than conventional nickel cadmium batteries and lead batteries. As a secondary battery, it is used as a power source for small electronic devices.

  A lithium ion battery is a battery element 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. What is a battery outer container? After attaching a lid body having an electrode in which electrodes of different polarities are insulated by an insulating member and sealing the fitting portion between the battery outer container and the lid body, a predetermined amount of electrolyte solution is poured from the electrolyte injection hole. The liquid injection hole is sealed, a sealing plug is attached to the liquid injection hole, and welding is performed by laser welding or the like to seal the liquid injection hole.

  3A and 3B are diagrams for explaining a filling hole sealing step of a conventional sealed battery, FIG. 3A is a plan view of the sealing plug, and FIG. 3B is a diagram illustrating the insertion of the sealing plug into the injection hole. FIG. 3C is an explanatory diagram of a state before the sealing is performed, and FIG. 3C is an explanatory diagram of a state in which the sealing plug is inserted into the liquid injection hole and welded.

  The sealing plug 1 is inserted into the injection hole 7 provided with the step portion 71 of the lid 2 of the sealed battery into which the electrolytic solution has been injected, and laser light is applied to the fitting portion between the sealing plug 1 and the lid 2. When irradiated, the metal of the irradiated portion is dissolved by the irradiation of the laser beam, the temperature inside the battery rises due to the heat generated by the lid 2 provided with the liquid injection hole 7 or the laser beam irradiated portion of the battery can, and the internal pressure As a result, the electrolyte leaks from the boundary between the injection hole 7 and the sealing plug 1, and the sealing failure may occur due to the adhesion of the electrolyte to the laser weld 3.

  In Patent Document 1, an elastic body such as rubber is attached to the inside of the liquid injection hole, a metal sealing plug is attached to the outside, and the outer metal sealing plug is connected to the wall surface of the electrolyte injection hole. Welded sealed batteries have been proposed. However, the sealing plug made of an elastic material such as rubber is softened by heat applied during welding, and the electrolyte leaks from the inside of the battery where the internal pressure is increased, so that welding of the metal sealing plug becomes insufficient. There is a possibility that sealing failure may occur.

JP 2000-268811 A

  An object of the present invention is to provide a sealed battery in which a sealing plug is attached to a liquid injection hole and sealed to prevent welding failure due to leakage of electrolyte due to heat applied at the time of sealing. It is to provide.

  In order to solve the above-mentioned problems, a sealed battery of the present invention has a cylindrical protrusion in a liquid injection hole provided with a step formed on a battery can made of an aluminum alloy or a lid for sealing the opening of the battery can. Is planted in the lower part, and a sealing plug having a flange part having a flange part formed on the outer peripheral surface of the upper end is attached and welded and sealed.

  According to the sealed battery of the present invention, the creeping distance from the sealing portion to the liquid injection port is increased, and the thermal influence on the inside of the battery is reduced, so that leakage of the electrolyte from the inside of the battery can is prevented during laser welding. Therefore, it is possible to perform stable laser welding without laser welding defects due to adhesion of an electrolytic solution, and a sealed battery with few sealing defects can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram for explaining a sealed battery according to the present invention, FIG. 1 (a) is a perspective view for explaining the sealed battery, and FIG. 1 (b) is a plan view of the sealed battery. (C) is sectional drawing explaining the sealing process of a liquid injection hole, FIG.1 (d) is sectional drawing which cut | disconnected the liquid injection hole part of FIG.1 (b) by the AA line.

  In the sealed battery of the present invention, after the battery element is housed in the battery can 5, the opening of the battery can 5 is sealed with the lid 2, and the lid 2 has the electrode terminal 6 in the center and the note. A liquid hole 7 is provided.

  The liquid injection hole 7 has a stepped portion 71 on a plate-like member constituting the lid 2 and has a stepped shape. The liquid injection hole 7 having the stepped portion 71 is formed by pressing or the like. The sealing plug 1 is formed of a flange portion 11 that fits in the step portion 71 of the liquid injection hole at the upper portion and a substantially cylindrical projection portion 12 that has a thin tip that fits in the liquid injection hole 7 at the lower portion. A flange 41 is provided on the outer peripheral surface.

  After injecting the electrolytic solution from the electrolytic solution injection hole 7, the sealing plug 1 having the flange 41 on the outer peripheral surface of the upper portion of the flange portion 11 is press-fitted into the injection hole 7. When press-fitting the sealing plug 1, the flange 41 is disposed on the lid 2 because the outer diameter of the flange 41 of the sealing plug 1 is formed larger than the diameter of the step 71. Thereafter, laser welding is performed.

  By laser welding the end face of the flange 41 and the lid 2, the creeping distance between the laser welded portion 3 and the liquid injection hole 7 is long, the thermal effect on the electrolyte is reduced, and the electrolyte leaks out. This makes it possible to perform stable laser welding.

  2A and 2B are diagrams for explaining another sealing step for the liquid injection hole of the sealed battery of the present invention. FIG. 2A is a plan view of the sealing plug, and FIG. It is sectional drawing explaining a sealing process, FIG.2 (c) is sectional drawing after sealing of a liquid injection hole. The electrolyte injection hole 7 has a stepped portion 71 at the bottom of the plate-like member constituting the lid 2 and has a shallow cut portion 72 at the top, and has a stepped shape. The sealing plug 1 has a flange portion 11 that fits in the step portion 71 of the liquid injection hole at the top, and a flange portion 41 at the upper peripheral edge of the flange portion 11, and a substantially circular shape with a thin tip that fits in the liquid injection hole 7 at the bottom. It has a columnar protrusion 12.

  After injecting the electrolytic solution from the electrolytic solution injection hole 7, the sealing plug 1 having the flange 41 on the outer peripheral surface of the flange portion 11 is press-fitted into the injection hole 7. The sealing plug 1 and the lid 2 form the same plane by being accommodated in the notch 72 corresponding to the outer shape of the flange 41.

  After the battery element is housed in a battery can made of an aluminum alloy (A3003) having a width of 30 mm, a height of 48 mm, and a thickness of 4 mm, as shown in FIG. 1, the step 71 has a diameter of 2.0 mm and a depth of 0.5 mm. A lid 2 made of an aluminum alloy (A3003) having a thickness of 1 mm provided with a liquid injection hole 7 having a through-hole having a diameter of 1.3 mm is fitted into a battery can, welded and sealed. A solution prepared by dissolving lithium hexafluorophosphate as an electrolyte in a mixed solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) as an electrolyte was injected from the injection hole 7, and then the flange portion 11 had a diameter of 2.0 mm and a thickness. 0.5 mm in length, 0.3 mm in width of the flange from the flange 11, 0.2 mm in thickness, 0.7 mm in height from the center of the flange 11, and a substantially cylindrical protrusion having a diameter of 1.2 mm The sealing plug 1 is press-fitted into the liquid injection hole 7, and the contact portion between the liquid injection hole 7 and the sealing plug 1 is welded by resistance welding. Thereafter, laser welding was performed on the end surface of the flange portion 41 of the sealing plug 1. About 500 produced lithium ion batteries, when the sealing state after laser welding was confirmed, there was no generation | occurrence | production of a defect.

  A lithium ion battery was produced in the same manner as in Example 1 except that the structure of the lid 2 was changed. As shown in FIG. 2, the stepped portion 71 of the lid body 2 has a diameter of 2.0 mm, a depth of 0.5 mm, and a through hole having a diameter of 1.2 mm at the center, and further a diameter of 2.6 mm and a depth of 0.2 mm. The lid body 2 having the notch 72 has a diameter of 2.6 mm including the flange portion of the flange portion 11, a thickness of 0.2 mm of the flange portion, a height of 0.7 mm from the center of the flange portion 11, and a diameter of 1.2 mm. The sealing plug 1 having the substantially cylindrical protrusion 12 was press-fitted into the liquid injection hole 7, resistance welding was performed, and then laser welding was performed. About 500 produced lithium ion batteries, when the sealing state after laser welding was confirmed, there was no generation | occurrence | production of a defect.

(Comparative example)
A lithium ion battery was produced in the same manner as in Example 1 except that the structure of the sealing plug was changed. As shown in FIG. 3, the diameter 2 of the flange 11 is set in the liquid injection hole 7 having a diameter of 2.0 mm and a depth of 0.5 mm of the stepped portion 71 and a through hole having a diameter of 1.2 mm in the center. A sealing plug 1 having a thickness of 0 mm and a thickness of 0.5 mm was pressed into the liquid injection hole 7 and laser welding was performed. About 500 produced lithium ion batteries, when the sealing state after laser welding was confirmed, the welding defect by three pinholes generate | occur | produced.

FIG. 1A is a perspective view illustrating a sealed battery, FIG. 1B is a plan view of the sealed battery, and FIG. 1C is a sealing of a liquid injection hole. Sectional drawing explaining a stop process, FIG.1 (d) is sectional drawing which cut | disconnected the injection hole part of FIG.1 (b) by the AA line. The figure explaining the sealing process of the other injection hole of the sealed battery of this invention, FIG. 2 (a) is a top view of a sealing stopper, FIG.2 (b) demonstrates the sealing process of an injection hole. Sectional drawing and FIG.2 (c) are sectional drawings after sealing a liquid injection hole. FIG. 3 (a) is a plan view of a sealing plug, and FIG. 3 (b) is a state before the sealing plug is inserted into the liquid injection hole. Explanatory drawing and FIG.3 (c) are explanatory drawings of the state which inserted the sealing stopper in the injection hole and welded.

Explanation of symbols

1 Sealing stopper
2 Lid 3 Laser welding part 5 Battery can 6 Electrode terminal 7 Injection hole
11 Flange portion 12 Projection portion 41 (Flange portion) ridge portion 71 (injection hole) step portion 72 (injection hole) notch

Claims (1)

  A cylindrical projection is planted at the bottom in the electrolyte injection hole provided with a step provided on a battery can made of an aluminum alloy or a lid for sealing the battery can opening, and the outer peripheral surface of the upper end A sealed battery, wherein a sealing plug in which a flange portion having a flange portion is formed is attached and welded and sealed.

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