JP2007066600A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery not generating contact failure caused by electrolyte leakage by heat applied for sealing in the sealed battery fitting a sealing plug to a pouring hole of an electrolyte to seal the hole. <P>SOLUTION: A sealing plug 1 having a flange part 11 from which a cylindrical projection part 12 stands up is fit to the pouring hole 7 of the electrolyte having a step part 71 installed in a battery can 5 made of an aluminum alloy or in a cover 2 for sealing a battery can opening part, and then the fitting part is sealed by welding to form the sealed battery, and the sealing plug having the cylindrical projection part 12 or a projection part 41 on at least one peripheral surface of the flange part 11 is used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealed battery, and more particularly to a sealed battery such as a lithium ion battery characterized by a sealing plug that seals an electrolyte injection hole after injecting an 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? Attach a lid with an electrode with different polarities insulated by an insulating member, seal the fitting part between the battery outer container and the lid, and then inject a predetermined amount of electrolyte from the electrolyte injection hole. The electrolyte injection hole is sealed with a sealing plug and welded by laser welding or the like to seal the injection hole.

  3A and 3B are explanatory views of the injection hole sealing step of the conventional sealed battery, FIG. 3A is a plan view of the sealing plug, and FIG. 3B is 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.

  The sealing plug 1 is inserted into the electrolyte 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 the fitting portion between the sealing plug 1 and the lid 2 is inserted. When the laser beam is irradiated, the metal in the laser beam irradiation part is dissolved, and the temperature inside the battery rises due to the heat generated in the lid 2 provided with the injection hole 7 or the laser beam irradiation part of the battery can. Leakage from the boundary between the electrolyte injection hole 7 and the sealing plug 1 occurred, and sealing failure sometimes occurred due to adhesion of the electrolytic solution to the laser weld 3.

  In Patent Document 1, an elastic body such as rubber is attached to the inside of the electrolyte injection hole, a metal sealing plug is attached to the outside, and the outer metal sealing plug is attached to the electrolyte injection hole. A sealed battery welded to a wall surface has been proposed. However, a sealing plug made of an elastic body such as rubber leaks from the inside of the battery, which is softened by heat applied during welding and the internal pressure is increased, and 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 hermetic battery in which a sealing plug is attached to an electrolyte injection hole and sealed to prevent welding failure due to leakage of the electrolyte due to heat applied at the time of sealing. It is to provide a type battery.

  In order to solve the above-mentioned problems, a sealed battery of the present invention has a cylindrical shape in an electrolyte injection hole provided with a step provided on a battery can made of an aluminum alloy or a lid for sealing the opening of the battery can. In a sealed battery in which a sealing plug having a flange portion in which a protrusion is planted is attached and sealed by welding, an outer peripheral surface is provided on at least one outer peripheral surface of the cylindrical protrusion of the sealing plug or the flange portion. It has the convex part which goes around.

  According to the sealed battery of the present invention, when the sealing plug is attached to the electrolyte injection hole, the convex portion provided in the sealing plug is crushed by press-fitting and bites into the injection hole to maintain airtightness. Sometimes it is possible to prevent leakage of the electrolyte from the inside of the battery can, and it is possible to perform stable laser welding without laser welding failure due to electrolyte adhesion, and the sealed battery with little sealing failure and less affected by heat Can provide.

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

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

  The sealed battery of the present invention is such that the battery element 5 is housed in the battery can 5 and then the opening of the battery can 5 is sealed with the lid 2, and the lid 2 has the electrode terminal 6 at the center. An electrolyte solution injection hole 7 is provided.

  The electrolyte 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 liquid injection hole step portion 71 and a substantially cylindrical projection portion 12 that has a thin tip that fits in the electrolyte injection hole 7, and is formed on the outer peripheral surface of the projection portion 12. A convex portion 41 is provided.

  After injecting the electrolytic solution from the electrolytic solution injection hole 7, the sealing plug 1 having the convex portion 41 on the outer peripheral surface of the protrusion 12 is press-fitted into the injection hole 7. When the sealing plug 1 is press-fitted, since the outer diameter of the convex portion 41 of the protruding portion of the sealing plug 1 is formed larger than the inner diameter of the liquid injection hole 7, the convex portion is crushed and bites into the liquid injection hole 7. Form a sealed state. Laser welding is then performed.

  Since the liquid injection hole 7 and the sealing plug 1 form a sealed state, the electrolyte does not leak and stable laser welding can be performed. In order to form a sealed state before laser welding with the liquid injection hole 7 and the sealing plug 1, in addition to using the sealing plug 1 having a convex portion on the protrusion, sealing having a convex portion on the outer periphery of the flange portion The stopper 1 can also be used.

  FIG. 2 is an explanatory view of another injection hole sealing step of the sealed battery of the present invention, FIG. 2 (a) is a plan view of the sealing plug, and FIG. 2 (b) is the injection hole sealing. It is sectional drawing explaining a stop process, FIG.2 (c) is sectional drawing after sealing of a liquid injection hole. The electrolyte injection hole 7 has a stepped portion 71 on a plate-like member constituting the lid 2 and is stepped. The sealing plug 1 is formed of a flange portion 11 that fits in the liquid injection hole step portion 71 and a substantially cylindrical projection portion 12 that has a thin tip that fits in the liquid injection hole 7, and protrudes from the outer peripheral surface of the flange portion 11. A portion 42 is provided.

  After injecting the electrolytic solution from the electrolytic solution injection hole 7, the sealing plug 1 having a convex portion on the outer peripheral surface of the flange portion is press-fitted into the injection hole 7. When the sealing plug 1 is press-fitted, since the outer diameter of the convex portion of the flange portion of the sealing plug 1 is slightly larger than the inner diameter of the step portion of the liquid injection hole 7, the convex portion is crushed and the liquid injection hole 7 digs into the stepped portion to form a sealed state.

  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. It has a substantially cylindrical projection having a height of 0.5 mm, a height of 0.7 mm from the center of the flange portion 11 and a diameter of 1.2 mm, and a diameter on the outer periphery of 0.8 mm from the upper surface of the flange portion 11 of the protrusion 12 The sealing plug 1 provided with a convex portion having a 1.34 mm cross-sectional substantially semicircular shape was press-fitted into the liquid injection hole 7 and resistance welding was performed. When the sealing plug 1 is press-fitted into the liquid injection hole 7, the convex portion 41 is crushed to form a sealed state, 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. About 500 produced lithium ion batteries, when the sealing defect after laser welding was test | inspected, 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 sealing plug was changed. As shown in FIG. 2, the diameter of the step portion 71 is 2.0 mm, the depth is 0.5 mm, and the through hole having a diameter of 1.3 mm is formed in the center. .5 mm, a substantially cylindrical projection 12 having a height of 0.7 mm from the center of the flange 11 and a diameter of 1.2 mm, and a cross section having a diameter of 2.20 mm on the outer periphery of 0.1 mm from the upper surface of the flange 11 The sealing plug 1 provided with a substantially semi-circular convex portion 42 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 defect after laser welding was test | inspected, 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 portion 11 is formed 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 defect after laser welding was test | inspected, the welding defect by three pinholes generate | occur | produced.

FIG. 1 (a) is a perspective view for explaining a sealed battery, FIG. 1 (b) is a plan view of the sealed battery, and FIG. 1 (c) is a liquid injection hole sealing. Sectional drawing explaining a process, FIG.1 (d) is sectional drawing which cut | disconnected the electrolyte solution injection hole part of FIG.1 (b) by the AA line. FIG. 2A is a plan view of a sealing plug, and FIG. 2B is a cross-sectional view illustrating the injection hole sealing step. Fig. 2 (c) is a cross-sectional view after sealing the injection hole. FIG. 3A is a plan view of a sealing plug, and FIG. 3B is an explanatory view of a state before the sealing plug is inserted into the injection hole. FIG. 3 (c) is an explanatory view showing a state in which the sealing plug is inserted into the injection hole and welded.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing plug 11 Flange part 12 Protrusion part 2 Cover body 3 Laser welding part 41 (Protrusion part) Convex part 42 (Flange part) Convex part 5 Battery can 6 Electrode terminal 7 Injection hole 71 (Injection hole) Step part

Claims (1)

  Sealing provided with a flange portion in which a cylindrical protrusion is planted in an electrolyte injection hole provided with a step portion provided on a battery can made of an aluminum alloy or a lid for sealing the opening portion of the battery can A sealed battery fitted with a stopper and welded and sealed, wherein the outer periphery of at least one of a cylindrical protrusion or a flange of the sealing stopper has a convex portion that circulates around the outer periphery. battery.

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