JP5361599B2 - Sealed battery - Google Patents

Description

  The present invention relates to a sealed battery, and in particular, an electrode group in which positive and negative electrodes are arranged via a separator and a battery case for accommodating an electrolyte, and a liquid injection hole formed in the battery case for injecting the electrolyte The present invention relates to a sealed battery provided with a sealing plug for sealing a liquid injection hole.

  Conventionally, for example, in a sealed battery for large current charge / discharge applications used as a power source for an electric vehicle, a stationary power supply device, etc., a battery case in which an electrode group in which positive and negative electrodes are arranged via a separator is infiltrated with an electrolyte. Is housed inside. As such an electrode group, a wound electrode group in which positive and negative electrodes are wound through a separator and a stacked electrode group in which positive and negative electrodes are stacked through a separator are widely known. In addition to aqueous electrolytes used in lead batteries and the like, non-aqueous electrolytes used in lithium ion secondary batteries and the like are known as electrolyte solutions.

  By the way, in general, a liquid injection hole for injecting an electrolytic solution is formed in the battery case, and a sealed battery is sealed in which the liquid injection hole is sealed with a sealing plug after the electrolytic solution is injected. Structure is adopted. As a battery having such a hermetically sealed structure, a sealing plug is placed on and joined to the upper opening of the battery case, and an electrolyte is injected through a sealing hole or a liquid injection hole formed in the battery case. After that, a sealing plug having a resin-made dense insertion step portion that matches the wall surface of the injection hole is fitted into the injection hole, and the injection hole is sealed with the sealing plug by laser welding ( For example, refer to Patent Document 1), and a sheet material is adhered or adhered so as to cover the liquid injection hole from the outside of the battery case, and is made of a metal plate-like seal so as to cover the sheet material from the outside of the battery case A sealed battery (see, for example, Patent Document 2) in which a stopper is arranged and the periphery of the sealing stopper is joined to a battery case is disclosed.

JP 2000-106156 A JP 2000-215883 A

  However, in a sealed structure such as Patent Document 1, when the liquid injection hole is sealed with the sealing plug, the bottom surface of the head (鍔) of the sealing plug abuts near the periphery of the liquid injection hole. If the electrolyte remains in the vicinity of the periphery of the liquid hole, when the electrolyte is deposited, when the sealing plug is fitted into the injection hole, the bottom surface of the head of the sealing plug hits the deposited electrolyte and seals. For example, the stopper is fitted to the injection hole while being inclined obliquely, or the vicinity of the periphery of the injection hole is pushed up by the head of the sealing plug by the thickness of the deposited electrolyte. In such a case, a gap is formed between the lower surface of the head of the sealing plug and the peripheral portion of the liquid injection hole, and a pinhole is likely to occur at the joint between the sealing plug and the liquid injection hole. There is a problem in securing the sealing property.

  On the other hand, in the sealed structure as in Patent Document 2, when the injection hole is sealed, it is covered with a sheet material, and the periphery of the injection plug is joined to the battery case using a metal plate-like sealing plug. However, there is no problem in securing the sealing property, but the battery case is provided with a liquid injection hole because the sheet material is inserted into the concave part where the liquid injection hole is formed and the liquid injection stopper is also inserted and fitted. There is a problem that the surface thickness is increased, which affects the internal capacity, and also increases the number of man-hours and parts.

  An object of the present invention is to provide a lightweight sealed battery that can ensure hermeticity and is light in light of the above case.

In order to solve the above problems, the present invention provides a sealed battery, an electrode group in which a positive electrode and a negative electrode are arranged via a separator, an electrolytic solution infiltrating the electrode group, the electrode group, and the electrolytic solution A battery case, a liquid injection hole formed in the battery case for injecting the electrolytic solution, and a plate-shaped sealing plug formed by pressing to seal the liquid injection hole. wherein the injection hole, said a recess formed on the outer surface of the battery case has a through-hole formed at a position including a central recess, both sides at the bottom of the sealing plug The tape is applied so as to avoid a portion corresponding to the through hole portion of the liquid injection hole, and the sealing plug is fitted in the concave portion of the liquid injection hole, and the upper surface of the concave portion of the liquid injection hole and the bottom of the sealing plug in close contact via the two-sided tape, the periphery of the sealing plug There the pouring is joined to the battery case of the concave peripheral edge of the hole is sealed, it is characterized.

In the present invention, the through hole portion of the liquid injection hole may be formed around the center of the recess, and the sealing plug may be a metal plate .

According to the present invention, when sealing the liquid injection hole, the double-sided tape is applied to the bottom of the sealing plug. For example, before sealing with the sealing plug, it is adhered so as to cover with the sheet material, As in the case where a plate-shaped sealing plug is arranged and the periphery of the sealing plug is joined to the battery case, the depth of the concave portion is increased by inserting the sheet material and the sealing plug into the concave portion. There is no need to increase the number of man-hours and parts, which also affects the capacity, and furthermore, it corresponds to the through-hole part of the liquid injection hole with double-sided tape between the bottom part of the sealing plug and the recessed part to be fitted. Applying and adhering so as to avoid the location can prevent the electrolyte from creeping up and evaporating, and when joining the peripheral part of the sealing plug to the peripheral part of the recess, To obtain the effect of reliably preventing the occurrence of pinholes and other bonding defects It can be.

It is an external appearance perspective view of the lithium ion battery of embodiment which can apply this invention. It is a partial expansion perspective view when the lithium ion battery of the embodiment before fitting the sealing plug into the liquid injection hole is viewed from above. It is a partial expansion perspective view when the lithium ion battery of the embodiment before fitting the sealing plug into the liquid injection hole is viewed from below.

  Hereinafter, an embodiment in which the present invention is applied to a sealed lithium ion battery will be described with reference to the drawings.

  As shown in FIG. 1, a lithium ion battery 10 (hereinafter simply referred to as a battery 10) of the present embodiment has a square battery case 1 made of aluminum or an aluminum alloy. The battery case 1 has a bottomed box-shaped battery can 1a having a rectangular (left and right horizontally long) opening formed by deep drawing an aluminum or aluminum alloy plate, and a rectangular shape obtained by press-molding an aluminum or aluminum alloy plate. The battery case 1 is formed by seam welding the outer periphery of the cover plate 1b with a YAG laser to the opening periphery of the battery can 1a.

  In the battery case 1, an electrode group (not shown) is infiltrated and accommodated in a non-aqueous electrolyte described later. The electrode group of the present embodiment is produced by winding a belt-like separator between a belt-like positive electrode and a belt-like negative electrode in a flat spiral shape, and the production procedure will be briefly described below.

(Positive electrode)
Lithium transition metal oxide (for example, lithium manganate having a spinel structure or layered rock salt structure, lithium manganate in which a part of lithium or manganese in the crystal is substituted or doped with other elements) as a positive electrode active material, and powder Then, a slurry is prepared by dispersing and mixing carbon powder as a conductive material and polyvinylidene fluoride (PVDF) as a binder in N-methyl-2-pyrrolidone (NMP) as an organic solvent. This slurry is applied to both surfaces of an aluminum foil having a thickness of 20 μm serving as a positive electrode current collector with a predetermined width, dried, pressed and integrated. Then, the positive electrode which has a positive electrode lead piece is produced by notching the slurry non-coating part (plain part) formed in the one side along the longitudinal direction of a positive electrode electrical power collector.

(Negative electrode)
A slurry is prepared by introducing and mixing a carbon material (for example, amorphous carbon) capable of releasing / occluding lithium ions as a negative electrode active material and PVDF as a binder into NMP as an organic solvent. This slurry is applied to both surfaces of a rolled copper foil having a thickness of 10 μm serving as a negative electrode current collector with a predetermined width, dried, pressed and integrated. Then, the negative electrode which has a negative electrode lead piece is produced by notching the slurry non-coating part (plain part) formed in the one side along the longitudinal direction of a negative electrode collector.

(Electrode group)
Between the positive electrode and the negative electrode, two separators made of a polyethylene microporous film are interposed, and a flat electrode group is produced by winding around a plate-shaped shaft core. In a general mass production mode, the electrode group includes a mounting portion for rotatably mounting the shaft core, a drive portion that has a motor and rotationally drives the mounting portion, a hoop-shaped positive electrode, a negative electrode, and a roll-shaped separator And a cutter that cuts the positive electrode, the negative electrode, and the separator respectively supplied from the supply unit to a predetermined length. At this time, the positive electrode lead piece and the negative electrode lead piece are wound so as to protrude from both end faces of the electrode group on opposite sides. Further, both end portions of the shaft core protrude from both end surfaces of the electrode group. In order to prevent the electrode group from unwinding, the end of the separator located at the winding end is fixed with an adhesive tape. The electrode group is accommodated in the battery case 1 by fixing both end portions of the shaft core protruding from both end surfaces of the electrode group in the battery case 1.

  A positive electrode terminal 3 made of aluminum and a negative electrode terminal 4 made of copper are provided upright at both end portions (left and right end portions in FIG. 1) of the lid plate 1b. The positive electrode terminal 3 and the negative electrode terminal 4 are respectively fastened with bolt screws to an attachment hole (not shown) formed in the lid plate 1b through an epoxy resin insulating material to avoid electrical contact with the lid plate 1b. The inside of the battery is secured by an O-ring arranged between the mounting hole and these terminals.

  The positive electrode lead piece and the negative electrode lead piece projecting from the opposite end surfaces of the electrode group are collected in the battery can 1a and welded to aluminum and copper plate-like current collecting members, respectively. The positive electrode terminal 3 and the negative electrode terminal 4 are connected via a copper conductive member.

(Injection hole sealing structure)
As shown in FIGS. 2 and 3, a liquid injection hole 5 for injecting a non-aqueous electrolyte is formed in the vicinity of the positive electrode terminal 3 of the upper lid 1b. The liquid injection hole 5 has a concave portion 5a formed on the outer surface of the upper lid 1b, and a liquid injection through hole 5b formed in the concave portion 5a. The concave portion 5a is a circular depression formed on the lid plate 1b by counterbore. For example, the depth of the concave portion 5a may be set to ½ or less of the thickness of the lid plate 1b. / 2 or more. The liquid injection through-hole 5b is a circular through-hole formed around the center of the recess 5a, and may have a diameter sufficiently smaller than that of the recess 5a.

  The liquid injection hole 5 is sealed with a sealing plug 6 made of metal (for example, the same aluminum or aluminum alloy as the cover plate 1b). The sealing plug 6 has a circular shape and is pressed. On the bottom surface of the sealing plug 6, one surface side of the double-sided tape 7 having a slightly smaller diameter than the sealing plug 6 and punched into an annular shape is attached. The double-sided tape 7 may be, for example, one in which a pressure-sensitive adhesive such as synthetic rubber is coated on both surfaces of a polypropylene base material and a release paper is disposed on the outer surface of the pressure-sensitive adhesive opposite to the base material. . In the center of the double-sided tape 7, a circular punching portion 7a is formed at a location corresponding to a position immediately above the liquid injection through hole 5b. Therefore, when the release paper is peeled off, the adhesive of double-sided tape is applied to the bottom surface of the sealing plug 6 so as to avoid the portion corresponding to the liquid injection through hole 5b.

  The sealing plug 6 is fitted into the recess 5a, and the upper surface of the recess 5a and the bottom surface of the sealing plug 6 are in close contact with each other via a double-sided tape 7. The peripheral edge of the sealing plug 6 is the periphery of the recess 5a. It is welded (joined) to the lid plate 1b.

Here, the procedure for sealing the liquid injection hole 5 with the sealing plug 6 will be briefly described as follows. Prior to sealing, the electrode group is fixed in the battery can 1a, and the positive electrode lead piece and the negative electrode lead piece are respectively connected to the positive electrode terminal 3 and the negative electrode terminal 4, and then the non-aqueous electrolyte from the injection port 5 Is injected into a predetermined amount. The non-aqueous electrolyte includes, for example, 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) as a lithium salt in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 2: 3. A dissolved one can be used.

  The release paper of the double-sided tape 7 affixed in advance to the bottom surface of the sealing plug 6 is peeled off, and the sealing plug 6 is pressed and fitted into the top surface of the recess 5a. Thereby, the upper surface of the recess 5 a and the bottom of the sealing plug 6 are in close contact with each other via the double-sided tape 7, and the upper surface of the sealing plug 6 is positioned at substantially the same height as the upper surface of the lid plate 6. Subsequently, the liquid injection hole 5a is sealed with the sealing plug 6 by welding the peripheral part of the sealing plug 6 to the cover plate 1b at the peripheral edge of the recess 5a.

(Action etc.)
Next, functions and effects of the battery 10 of the present embodiment will be described.

  As described above, the non-aqueous electrolyte is a volatile organic solvent in which an electrolyte is added. Therefore, the organic solvent is easily vaporized even at room temperature, and when it receives heat, it is actively evaporated. When the injection of the non-aqueous electrolyte from the injection port 5 is completed, the double-sided tape 7 (adhesive) applied to the bottom surface of the sealing plug 6 is applied to the upper surface of the recess 5a, so that the injection through-hole 5b Is covered with a sealing plug 6. For this reason, the non-aqueous electrolyte in the battery case 1 is evaporated by the heat generated when the peripheral edge of the sealing plug 6 is welded to the cover plate 1b at the peripheral edge of the recess 5a, and crawls up from the injection through hole 5b. No negative effect on welding.

  Moreover, in the battery 10 of this embodiment, the double-sided tape 7 by which the adhesive was apply | coated to the bottom face of the sealing plug 6 is distribute | arranged, and the recessed part 5a upper surface and the bottom of the sealing plug 6 are interposed via a double-sided tape. It is in close contact. For this reason, even after the non-aqueous electrolyte is injected, even if the non-aqueous electrolyte remains on the upper surface of the recess 5a and the electrolyte is deposited, the double-sided tape depending on the deposited electrolyte due to the insertion of the sealing plug 6 into the recess 5a. The adhesive is partially deformed and absorbed to prevent the sealing plug 6 from being inclined or pushed up. Accordingly, it is possible to prevent poor welding such as a pinhole when the peripheral edge of the sealing plug 6 is welded to the cover plate 1b at the peripheral edge of the recess 5a. Furthermore, in the battery 10 of the present embodiment, it is sufficient to set the depth of the recess 5a to the thickness of the sealing plug 6 with the double-sided tape 7 applied to the bottom surface. In comparison, the surface thickness of the cover plate 1b can be reduced, the battery can be reduced in weight, and the number of components can be reduced because the sheet material is unnecessary.

  Further, in the battery 10 of the present embodiment, the sealing plug 6 is formed by pressing, and a double-sided tape that is coated with an adhesive and punched is used. For this reason, after injecting the non-aqueous electrolyte, the release paper of the double-sided tape 7 can be peeled off, and the sealing plug 6 can be pressed and inserted into the recess 5a. Therefore, since the sealing plug 6 can be prepared in advance with the release paper arranged, it is possible to easily carry out and manage the input to the production line, and to improve the assembly of the battery. it can.

  Furthermore, in the battery 10 of the present embodiment, the double-sided tape 7 applied to the bottom surface of the sealing plug 6 is applied so as to avoid a portion corresponding to the liquid injection through hole 5b. For this reason, according to the battery 10 of this embodiment, the influence which the component contained in the adhesive of the double-sided tape 7 has on a non-aqueous electrolyte can be eliminated or reduced.

  Moreover, in the battery 10 of this embodiment, the depth of the recess 5a is set to ½ or less of the thickness of the cover plate 1b, and the sealing plug 6 is fitted in the recess 5a. For this reason, according to the battery 10 of this embodiment, weakening of the formation part of the injection hole 5 of the cover plate 1b can be prevented.

  In the present embodiment, the electrode group wound in a flat shape is exemplified, but the present invention is not limited to this, and an electrode group wound in a columnar shape or an electrode group in which positive and negative electrodes are stacked is used. Also good. In this embodiment, the rectangular battery is exemplified, but the present invention can be applied to a cylindrical battery or a flat battery, and can also be applied to a sealed battery in which an electrolytic solution is an aqueous electrolytic solution. Further, in the present embodiment, the electrode group having the axis is illustrated, but an electrode group without the axis may be used in order to reduce the battery weight. At that time, in order to increase the output volume density of the battery, the electrode group wound in a flat shape with a predetermined pressure may be crushed.

  Moreover, in this embodiment, the liquid injection through-hole 5b was formed in the center of the recessed part 5a, and the recessed part 5a and the liquid injection through-hole 5b showed the circular example, However, This invention is not restrict | limited to this, The recessed part 5a Even if the liquid injection through hole 5b is located at a position including the center (even if the liquid injection through hole 5b is formed at a position deviated with respect to the concave portion 5a), the concave portion 5a and the liquid injection through hole 5b are formed. You may have arbitrary shapes, such as a polygon.

  Furthermore, in this embodiment, although the example which used the double-sided tape 7 as an adhesive was shown, this invention is not restricted to this, You may make it apply | coat an adhesive agent directly to the bottom face of the injection stopper 7. FIG. Further, if a rubber adhesive or an acrylic adhesive that does not easily affect the electrolytic solution is used as the adhesive, the punched portion 7 a does not necessarily have to be formed on the double-sided tape 7.

  Since the present invention provides a lightweight sealed battery that can ensure hermeticity and contributes to the manufacture and sale of sealed batteries, it has industrial applicability.

DESCRIPTION OF SYMBOLS 1 Battery case 1a Battery can 1b Cover plate 5 Injection hole 5a Recessed part 5b Injection through hole (through hole part)
6 Sealing plug 7 Double-sided tape (adhesive)
7a Punching part 10 Lithium ion battery (sealed battery)

Claims (2)

An electrode group in which a positive electrode and a negative electrode are arranged via a separator;
An electrolyte solution infiltrating the electrode group;
A battery case containing the electrode group and the electrolyte;
A liquid injection hole formed in the battery case for injecting the electrolytic solution;
A plate-shaped sealing stopper formed by pressing and sealing the liquid injection hole;
With
The liquid injection hole has a concave portion formed on the outer surface of the battery case, and a through hole portion formed at a position including the center of the concave portion,
A double-sided tape is applied to the bottom of the sealing plug so as to avoid a position corresponding to the through hole portion of the liquid injection hole ,
The sealing plug is fitted in the concave portion of the liquid injection hole, and the upper surface of the concave portion of the liquid injection hole and the bottom of the sealing plug are in close contact via the double-sided tape , The peripheral edge is joined and sealed to the battery case at the peripheral edge of the recess of the liquid injection hole.
A sealed battery characterized by that.   2. The sealed battery according to claim 1, wherein the through-hole portion of the liquid injection hole is formed around the center of the recess, and the sealing plug is a metal plate.

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