JP2015185225A - Hermetically sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hermetically sealed battery having high safety in which a safety valve can surely function even when deformation of a can is little.SOLUTION: By using a liquid injection port sealing tap using only resin which is molten at a predetermined temperature or more is used as a second safety valve mechanism, or metal coated with the resin as a seal layer, when a battery falls into a runaway state and thus the temperature increases, the resin of the liquid injection port sealing tap functioning as the second safety valve is molten a gap occurs between a liquid injection port and the liquid injection port sealing tap, and gas is discharged from the gap to the outside, whereby a battery case can be prevented from bursting.

Description

  The present invention relates to a sealed battery having a sealing plug attached to an injection port for electrolyte injection provided on a lid that closes an upper surface of an opening of a battery case, and relates to a technique for improving safety by the sealing plug.

  Patent Documents 1 and 2 disclose a sealed battery in which an electrode body, an electrolytic solution, and the like are accommodated in a battery case in which an upper surface opening of a battery can is closed with a lid. In this sealed battery, an electrolytic solution is injected into the battery can through a liquid injection hole provided in the lid, and then a sealing plug is fitted into the liquid injection hole so that the upper peripheral edge of the sealing plug is connected to the liquid injection hole. The liquid injection hole is sealed with a sealing plug by seam welding to the peripheral edge of the upper end using a laser or the like.

  On the other hand, in Patent Documents 3 and 4, a safety valve is formed on the lid of the battery can or on the side surface of the battery case, which breaks when the pressure in the battery case becomes larger than a threshold value. When the pressure of the battery case exceeds the threshold value, the cleavage groove is cleaved by deformation of the battery case, so that gas or the like in the battery case can be released to the outside, and the battery case can be prevented from being ruptured.

JP 2000-106156 A JP 2002-358948 A JP 2007-080598 A Japanese Patent No. 4166028

  However, when rigidity is required for the battery can in the housing design, deformation of the can is restricted, and there is a possibility that the tearing function due to can deformation cannot be performed. The present invention solves the above-described problem, and provides a highly safe sealed battery in which a safety valve functions reliably even when the can is hardly deformed.

  The sealed battery of the present invention that has achieved the above object uses a liquid injection port seal that uses only a resin that melts at a predetermined temperature or more as a second safety valve mechanism, or uses a metal coated with the resin as a seal layer. A stopper is used.

  With the above configuration, when the battery goes into a runaway state and becomes high temperature, the resin of the injection port sealing plug that functions as the second safety valve melts, and between the injection port and the injection port sealing plug By generating a gap and releasing gas from the gap, it is possible to escape to the outside and prevent the battery case from rupturing.

  According to the present invention, even when the deformation of the can is small, the safety valve operates reliably, and a sealed battery with high safety can be provided.

Vertical front view of a sealed battery according to the present invention Disassembled perspective view of sealed battery Enlarged view showing the cross section of the sealing plug and liquid injection hole The figure which shows the modification of the resin sealing plug The figure which shows the modification which used the resin film sealing stopper

  As shown in FIGS. 1 and 2, the sealed battery according to the present invention includes a bottomed rectangular tube-shaped battery can 1 having a horizontally long opening on the upper surface, an electrode body 2 housed in the battery can 1, and a non- It includes a water electrolyte, a horizontally long lid 3 that closes and seals the upper surface of the battery can 1, and a plastic insulator 5 that is disposed inside the lid 3. The battery can 1 has a left-right width dimension of 29.0 mm, a vertical height dimension of 46.0 mm, and a front-rear thickness dimension of 4.2 mm. A battery case 6 is formed by the battery can 1 and the lid 3.

  As shown in FIG. 1, the electrode body 2 is produced by winding it in a spiral shape with a strip-shaped separator interposed between the strip-shaped positive electrode and the strip-shaped negative electrode. The electrode body 2 has a flat shape shown in FIG. 2 in a wound state. In the positive electrode, a positive electrode active material layer containing a positive electrode active material such as lithium cobaltate is formed on both sides of a belt-like positive electrode current collector. As shown in FIGS. 1 and 2, the positive electrode current collector is formed into a thin plate shape. The positive electrode current collecting lead 10 is derived.

In the negative electrode, negative electrode active material layers containing a negative electrode active material such as graphite are formed on both sides of a strip-shaped negative electrode current collector, and a thin plate-shaped negative electrode current collector lead 11 is led out from the negative electrode current collector. The separator is made of a microporous thin film such as polyethylene resin. The non-aqueous electrolyte was prepared by dissolving LiPF ₆ in a solvent obtained by mixing ethylene carbonate and methyl ethyl carbonate.

  The battery can 1 is a deep drawn product of a plate material such as an aluminum alloy. The lid 3 is a press-molded product of a plate material such as an aluminum alloy, and the outer peripheral edge of the lid 3 is seam welded to the peripheral edge of the opening of the battery can 1 with a laser or the like. Thereby, the battery case 6 is formed. As shown in FIG. 1, a negative electrode terminal 15 is attached to the center of the lid 3 through an upper insulating packing 12 and a lower insulating plate 13 in a penetrating manner. Near the right end of the lid 3 in the left-right direction, a liquid injection hole 16 for injecting the electrolyte into the battery can 1 is formed in a vertically penetrating manner. The liquid injection hole 16 is closed by press-fitting a sealing plug 17.

  Connected to the lower end of the negative electrode terminal 15 is a lead body 19 made of a horizontally long thin plate on the inner surface of the lid 3. The lead body 19 extends to the opposite side of the liquid injection hole 16 and is insulated from the lid 3 by the insulating plate 13. The negative electrode current collector lead 11 is welded to the lower surface of the lead body 19. The positive electrode current collecting lead 10 is welded to the space between the insulating plate 13 and the liquid injection hole 16 on the back surface of the lid 3. Thus, the positive electrode current collecting lead 10 is conducted to the lid 3 and the battery can 1, and the lid 3 and the battery can 1 are charged to the positive electrode potential. A cleaving vent 20 is formed near one end of the lid 3 in the left-right direction (near the left end in FIG. 2). The cleaving vent 20 is cleaved to release the battery internal pressure when the battery internal pressure rises abnormally. The cleavage vent 20 may be provided in the battery can 1 instead of the lid.

  As shown in FIG. 3, the sealing plug 17 is a columnar head 22 that is welded to the peripheral edge of the upper end of the liquid injection hole 16 and a columnar shape that extends downward from the center of the lower surface 22 c of the head 22. And a shaft portion 23. The lower surface 22c of the head portion 22 of the sealing plug 17 is a horizontal plane perpendicular to the axial center (vertical direction) of the sealing plug 17, and is substantially parallel to the upper surface 22d of the sealing plug 17. It has become. The outer diameter dimension of the head portion 22 is larger than the outer diameter dimension of the shaft portion 23. The top and bottom thickness dimension of the head 22 is 0.5 mm.

  The material of the sealing plug 17 is preferably a resin having a melting point of 100 to 150 ° C. As the resin material, polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), and the like are preferable. Alternatively, it may be made of a metal whose surface is coated with the resin.

  The liquid injection hole 16 has a cylindrical surface-shaped fitting recess 26 into which the head portion 22 of the sealing plug 17 is fitted, and a cylindrical surface shape into which the shaft portion 23 of the sealing plug 17 is press-fitted (inserted). And an insertion portion 27. The inner peripheral surface of the fitting recess 26 is a tapered inner surface 26a that extends in a direction perpendicular to the upper surface 3a of the lid 3 and a tapered surface that is connected to the lower end of the vertical inner surface portion 26a and is constricted. It has an inner surface portion 26b and a receiving surface portion 26c connected to the lower end of the tapered inner surface portion 26b and receiving the lower surface 22c of the head portion 22 of the sealing plug 17. The upper surface 3 a of the lid 3 constitutes a surface that is the outer surface of the battery case 6 and forms the periphery of the liquid injection hole 16.

  The receiving surface portion 26 c of the liquid injection hole 16 is a horizontal plane that is perpendicular to the axial center (vertical direction) of the liquid injection hole 16. The vertical dimension L2 of the vertical inner surface portion 26a of the fitting recess 26 of the liquid injection hole 16 is 0.3 mm. The top and bottom thickness dimension of the lid 3 is 0.8 mm, and the top and bottom dimension of the fitting portion 27 of the liquid injection hole 16 is 0.3 mm. The receiving surface portion 26c of the liquid injection hole 16 has a width L1 of 0.3 mm from the inner edge on the fitting portion 27 side to the outer edge on the tapered inner surface portion 26b side.

  The outer peripheral surface of the head portion 22 of the sealing plug 17 is connected to the lower surface 22c, the columnar vertical outer surface portion 22a facing the vertical inner surface portion 26a of the liquid injection hole 16, and the lower end of the vertical outer surface portion 22a. The liquid injection hole 16 has a tapered outer surface portion 22b having a tapered surface facing the tapered inner surface portion 26b. The lower surface 22c is connected to the lower end of the tapered outer surface portion 22b.

  The outer diameter size of the vertical outer surface portion 22 a of the sealing plug 17 is slightly smaller than the inner diameter size of the vertical inner surface portion 26 a of the liquid injection hole 16. There is a slight gap between the tapered outer surface portion 22 b of the sealing plug 17 and the tapered inner surface portion 26 b of the liquid injection hole 16. The vertical dimension L3 of the vertical outer surface portion 22a of the sealing plug 17 is 0.3 mm.

  The inclination angle d1 of the tapered inner surface portion 26b with respect to the receiving surface portion 26c of the liquid injection hole 16 is 45 °. The inclination angle of the tapered outer surface portion 22b of the head portion 22 of the sealing plug 17 is set equal to the inclination angle d1 of the tapered inner surface portion 26b of the liquid injection hole 16. The tapered outer surface portion 22b of the sealing plug 17 is formed by C chamfering of C0.15 to C0.25.

  The outer peripheral surface of the shaft portion 23 of the sealing plug 17 is connected to the columnar vertical surface portion 23a formed in the direction perpendicular to the upper surface of the lid 3 and the lower end of the vertical surface portion 23a, and the tapered surface is constricted. And a guide surface portion 23b formed in a shape. The guide surface portion 23 b guides the shaft portion 23 of the sealing plug 17 to the fitting portion 27 of the liquid injection hole 16 when the sealing plug 17 is fitted into the liquid injection hole 16.

  The inner diameter dimension of the fitting part 27 of the liquid injection hole 16 is set to be equal to or slightly smaller than the outer dimension of the shaft part 23 of the sealing plug 17 before press-fitting. When the sealing plug 17 is press-fitted into the liquid injection hole 16, the lower portion of the shaft portion 23 of the sealing plug 17 protrudes below the liquid injection hole 16 as shown in FIG. 1.

  When assembling the battery, the negative electrode terminal 15, the insulating packing 12, the insulating plate 13, and the lead body 19 are attached to the lid 3 as described above. And after accommodating the electrode body 2 and the insulator 5 in the battery can 1, the negative electrode current collection lead 11 is welded to the lead body 19, and the positive electrode current collection lead 10 is welded to the lid 3 as described above. Next, after the lid 3 is seam welded to the periphery of the opening of the battery can 1, the inside of the battery can 1 is vacuum-reduced and a nonaqueous electrolyte is injected from the liquid injection hole 16.

  After the completion of the injection, the sealing plug 17 is inserted into the liquid injection hole 16, and the shaft portion 23 of the sealing plug 17 is press-fitted into the fitting portion 27 of the liquid injection hole 16. It is sealed in the state where it was closed with.

  The sealing plug 17 may be provided at any part of the battery case 6, and may be provided, for example, on the bottom surface or side surface of the battery can 1.

  When the temperature of the battery rises due to a runaway or the like, the sealing plug 17 melts a part of the sealing plug when the temperature becomes higher than the melting point of the resin material, and a gap is formed to release the gas generated inside to the outside. It functions as a safety valve.

  In this embodiment, the resin sealing plug having the shape shown in FIG. 3 is used, but the resin sealing plug having the shape shown in FIG. 4 may be used. Further, as a sealing plug provided with a resin film on the metal surface, one having the shape shown in FIG. 5 may be used.

1 Battery can
2 Electrode body 3 Lid
6 Battery case 10 Positive current collecting lead 11 Negative current collecting lead 12 Insulating packing 13 Insulating plate 15 Negative electrode terminal 16 Injection hole
17 Sealing stopper
19 Lead body 20 Cleavage vent 22 Head
22a Vertical outer surface
22b Taper outer surface
22c bottom
23 Shaft
23a Vertical surface
23b Guide surface
26 Fitting recess
26a Vertical inner surface
26b Taper inner surface
26c Receiving surface part
27 Insertion part

Claims (5)

In a sealed battery in which the liquid injection hole is sealed by injecting an electrolytic solution into the battery case from the liquid injection hole provided in the battery case and then press-fitting a sealing plug into the liquid injection hole.
The battery case is provided with a first safety valve,
The sealed plug functions as a second safety valve and has at least a part of a resin that melts at a predetermined temperature or higher. The sealed battery according to claim 1, wherein the sealing plug is made of a resin that melts at a predetermined temperature or higher. The sealed battery according to claim 1, wherein the sealing plug is provided with a resin that melts at a predetermined temperature or more on a surface of a metal part. The sealed battery according to claim 1, wherein the resin has a melting point of 100 ° C. to 150 ° C. The sealed battery according to claim 4, wherein the resin includes at least one selected from polyethylene, polypropylene, and polyvinylidene fluoride.

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