JP2007035343A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery excellent in sealing performance at an inlet for liquid electrolyte. <P>SOLUTION: An inlet for liquid electrolyte 2 formed in a battery outer case or a battery header 1 made of aluminum or an aluminum alloy has a large diameter 2a and a small diameter 2b which communicate with each other via a step 2c. A first sealing body 3 covering the small diameter 2b is connected to the step 2c, and a second sealing body 4 closing an opening is connected to the large diameter. <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 having a feature in a sealing portion that seals an electrolyte solution injection port after injecting an electrolyte solution.

  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 electrode active materials that dope and de-dope lithium ions are secondary batteries that have a larger energy density per volume or mass than conventional nickel cadmium and lead batteries. As a 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 battery header equipped with an electrode with different polarities insulated by an insulating member and sealing the fitting part between the battery outer container and the battery header, a predetermined amount of electrolyte is injected from the electrolyte inlet. Then, a sealing body is attached to the electrolyte solution injection port and welded by laser welding or the like to seal the solution injection port.

  FIG. 2 is a diagram for explaining a sealing step of an electrolyte injection port of a conventional sealed battery, and FIG. 2 (a) is an illustration showing only a cut state before the sealing body is inserted into the injection port. FIG. 2 and FIG. 2B are explanatory views showing a state in which the sealing body is inserted into the liquid injection port and welded.

  The sealing body 7 is inserted into the electrolyte injection port 2 including the electrolyte injection port large-diameter portion 2a and the electrolyte injection port small-diameter portion 2b of the battery header 1 of the sealed battery into which the electrolyte solution has been injected. Then, when the laser beam 6 is irradiated to the fitting portion between the sealing body 7 and the battery header 1, the metal of the laser beam irradiation portion is dissolved, and the laser beam irradiation portion of the battery header 1 or the battery outer container provided with the liquid injection port 2. The internal temperature of the battery rises due to the heat generation of the battery, and leakage of the electrolyte 8 from the boundary between the injection port 2 and the sealing body 7 occurs due to an increase in the internal pressure, and the electrolyte 8 adheres to the laser light irradiation part A sealing failure sometimes occurred.

  In Patent Document 1, an elastic body such as rubber is attached to the inside of the electrolyte solution inlet, a metal seal body is attached to the outside, and the outer metal seal body is attached to the wall surface of the electrolyte solution inlet. Welded sealed batteries have been proposed. However, the sealing body made of an elastic body such as rubber is sealed due to insufficient leakage of the electrolyte from the inside of the battery which has been softened by the heat applied during welding and the internal pressure has increased, and the metal sealing body is insufficiently welded. There was a possibility of failure.

JP 2000-268811 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sealed battery in which a sealing body is attached to an electrolyte injection port and sealed, so that the electrolyte does not leak due to heat applied at the time of sealing and a welding failure does not occur. There is to do.

  In order to solve the above-described problems, the sealed battery of the present invention includes an outer large-diameter portion and an inner portion where an electrolyte injection port provided in a battery outer container or a battery header made of aluminum or an aluminum alloy is connected via a stepped portion. The first sealing body that covers the small-diameter portion is connected to the stepped portion, and the second sealing body that closes the opening portion is connected to the large-diameter portion. Further, the first sealing body is preferably a clad material of nickel and aluminum, resistance welding is good for connection to the step portion of the first sealing body, and the second sealing body is preferably aluminum or aluminum alloy, Laser welding is preferable for connection to the large-diameter portion of the second sealing body.

  The sealed battery of the present invention has a small-diameter portion and a large-diameter portion formed in the electrolyte injection port through a step portion, and the first sealing body made of a clad material of nickel and aluminum or the like is resistance-welded to the step portion. After the connection, the second sealing body made of aluminum or the like was attached to the large-diameter portion, and heat-welded by laser welding to connect and seal, so the pressure inside the battery outer container increased during heat-sealing with laser light. As a result, there is no leakage of the electrolyte solution from the electrolyte solution injection port, so that no pinhole or the like is generated when the electrolyte solution injection port is sealed, and a sealed battery having excellent sealing characteristics can be provided.

  In the sealed battery of the present invention, after the electrolyte solution is injected, the first sealing body is attached to the injection port, and the pressure in the battery outer container increases due to the heat applied to the electrolyte solution during laser welding. It has been found that the injection port can be completely sealed by temporarily preventing leakage of the electrolytic solution and then mounting and welding the second sealing body.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a sealed battery of the present invention, FIG. 1A is a perspective view illustrating a sealed battery, and FIG. 1B is a plan view of the sealed battery. 1 (c) is a cross-sectional view illustrating a sealing step of the liquid injection port, and FIG. 1 (d) is a cross-sectional view of the electrolyte solution injection port portion of FIG. 1 (b) cut along line AA. is there.

  In the sealed battery of the present invention, after the battery element is housed in the battery can, the opening of the battery can is sealed with the battery header 1, and the battery header 1 has an electrode terminal at the center and an electrolyte solution injection. It has a liquid port 2.

  The electrolyte solution injection port 2 provided on the metal plate of the battery header 1 has an electrolyte solution injection port portion of the battery header on the outside of the battery outer casing through the step portion 2c as shown in FIG. The large-diameter portion 2a having a large diameter and the small-diameter portion 2b having a small diameter facing the inside of the battery outer container are configured. The first sealing body 3 is made of, for example, a disk or square plate of a clad material of nickel and aluminum, and is mounted so as to cover the small-diameter portion 2b on the step portion 2c of the liquid injection port as shown in FIG. For example, it is pressed by resistance welding electrode 5 and connected by resistance welding.

  The material of the first sealing body 3 may be any material that can be in close contact with aluminum or aluminum alloy, which is the material of the liquid injection step portion such as aluminum, aluminum alloy, stainless steel and aluminum clad material. As a connection method, other connection methods such as ultrasonic welding can be used in addition to resistance welding which is simple in terms of equipment.

  By connecting the first sealing body to the liquid injection port step portion, the liquid injection port is temporarily sealed, and leakage of the electrolytic solution inside the battery outer container to the outside is prevented. The first sealing body 3 is a flat member having an outer diameter larger than the inner diameter of the small-diameter portion 2b so that the electrolyte injection port can be reliably sealed in the small-diameter portion 2b. Moreover, it is desirable to determine the thickness of the first sealing body 3 so that the second sealing body 4 does not protrude upward or the protruding amount becomes small when the second sealing body 4 is mounted.

  After the connection of the first sealing body to the stepped portion 2c, as shown in FIG. 1 (d), the second sealing body 4 made of aluminum or an aluminum alloy is fitted to the liquid injection port large-diameter portion 2a to inject the liquid. The mouth 2 and the second sealing body 4 are completely sealed by laser welding. Due to the heat generated during laser welding, the inside of the battery outer casing is also thermally affected and becomes high temperature, and the internal pressure rises, but it is sealed by the first sealing body connected to the liquid injection step portion 2c. Therefore, the internal electrolyte solution or the like is not leaked, the electrolyte solution does not adhere to the welded portion, and stable laser welding without a defective portion can be performed.

  The first sealing body temporarily seals the liquid injection port in order to prevent leakage of the electrolyte generated due to the internal temperature rising due to the heat generated during laser welding and the internal pressure increase. Is. In order to prevent minute leakage of the electrolytic solution due to long-term use, the second sealing body is completely sealed by laser welding of the second sealing body.

  After the battery element is housed in a battery outer container made of an aluminum alloy (A3003) having a width of 30 mm, a height of 48 mm, and a thickness of 5 mm, as shown in FIG. A battery header 1 made of an aluminum alloy (A3003) having a thickness of 1.0 mm provided with a liquid injection port 2 having a through-hole with a diameter of 1.0 mm with a small-diameter portion 2b at a center of 0 mm in depth and 0.5 mm. Fit into container and seal by laser welding.

  A solution prepared by dissolving lithium hexafluorophosphate as an electrolytic solution and a mixed solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) as an electrolyte was injected from the injection port 2, and then 2.0 mm long and 2.0 mm wide. A first sealing body made of nickel and aluminum clad material having a thickness of 0.2 mm is placed on the step part 2c of the injection port so as to completely close the small-diameter part 2b, and energized while being pressed with an electrode rod for resistance welding. Welding was performed.

  Thereafter, a second sealing body made of an aluminum disc having a diameter of 3.0 mm and a thickness of 0.3 mm was fitted into the injection port large-diameter portion 2a, and the injection port and the second sealing body were sealed by laser welding. . About 1000 produced lithium ion batteries, when the sealing defect 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 body was changed. As shown in FIG. 2, a sealing body 7 having a diameter of a flange portion of 3.0 mm and a protruding portion having a thickness of 0.5 mm having a diameter of 1.0 mm was press-fitted into the liquid injection port 2 and laser welding was performed. About 1000 produced lithium ion batteries, when the sealing defect after laser welding was confirmed, the welding defect by five 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 inlet. Sectional drawing explaining a stop process, FIG.1 (d) is sectional drawing which cut | disconnected the part of the electrolyte injection hole of FIG.1 (b) by the AA line. The figure explaining the sealing process of the electrolyte solution injection port of the conventional sealed battery, FIG.2 (a) is explanatory drawing which showed the state before inserting a sealing body in a liquid injection port by a cut end, FIG.2 (b) ) Is an explanatory view of a state in which the sealing body is inserted into the liquid injection port and welded.

Explanation of symbols

1 Battery Header 2 (Electrolytic Solution) Injection Port 2a (Injection Port) Large Diameter Portion 2b (Injection Port) Small Diameter Portion 2c (Injection Port) Stepped Part 3 First Sealing Body 4 Second Sealing Body 5 Resistance Welding Electrode 6 Laser light 7 Sealing body 8 Electrolyte

Claims (2)

  An electrolyte injection port provided in a battery outer container or battery header made of aluminum or an aluminum alloy has an outer large-diameter portion and an inner small-diameter portion connected via a step portion, and the small-diameter portion is formed in the step portion. A sealed battery characterized in that a first sealing body that covers a portion is connected, and a second sealing body that closes an opening is connected to the large-diameter portion.   The first sealing body is made of a clad material of nickel and aluminum, connected to the step portion by resistance welding, the second sealing body is made of aluminum or an aluminum alloy, and is connected to the large diameter portion by laser welding. The sealed battery according to claim 1.

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