JP2011076784A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery wherein a welded portion of a sealing plug has improved strength. <P>SOLUTION: The sealed battery includes containers (1, 20) storing a battery power generating element group, a recessed portion (42) formed as a depression where part of the wall of a container cover (1) falls inside the containers, and having an opening (43) in the bottom face to fill electrolyte thereinto, and a liquid plug (2) having a plug portion (6) inserted into the opening (43) and a flange portion (5) placed in the recessed portion (42), the sealing plug (2) sealing the opening (43) with the peripheral edge of the flange portion (5) welded to the side periphery of the recessed portion (42). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealed battery.

  In recent years, lithium ion secondary batteries having a high energy density (Wh / kg) have been developed as power sources for portable electronic devices and electric vehicles, and among them, a square secondary having a high volume energy density (Wh / L). Batteries are attracting attention (see, for example, Patent Documents 1 and 2).

  The batteries described in Patent Documents 1 and 2 are sealed batteries, and after injecting an electrolyte into the battery from a liquid inlet provided on the lid of the sealed battery, an injection stopper is inserted into the liquid inlet. It is sealed. At that time, the fitting portion of the liquid inlet and the liquid stopper are laser welded.

JP 2008-10264 A JP 2007-323860 A

  By the way, in order to improve the strength of the laser welded portion, it is necessary to deepen the penetration. However, if the penetration is deepened, the inside of the lid may be melted. Therefore, when the lid is thin, the penetration must be shallow, the strength of the welded portion is weak, and the pressure resistance of the battery is reduced.

  The sealed battery according to the present invention is a container in which a battery power generation element group is housed, and a recess in which a part of the wall of the container falls into the inside of the container, and an opening for injecting an electrolyte into the bottom surface thereof. A sealing plug having a recessed portion provided, a stopper portion inserted into the opening and a flange portion placed in the recess, and opening the opening by welding the periphery of the flange portion and the side periphery of the recess Is sealed with a sealing plug.

  ADVANTAGE OF THE INVENTION According to this invention, the strength improvement of the welding part of a sealing plug can be aimed at in the sealed battery which welds a sealing plug to a container and seals the opening for electrolyte injection.

It is a perspective view which shows the external appearance of a sealed battery, (a) shows the cover side of a battery, (b) shows the back surface side of a battery. It is a disassembled perspective view which shows the internal structure of a sealed battery. It is a figure explaining the structure of the winding group. It is sectional drawing which shows the injection stopper 2 and the recessed part 4, (a) shows the state before laser welding, (b) shows after laser welding. It is a figure which shows an example of the structure of the injection stopper in the conventional sealed battery, (a) is sectional drawing before welding, (b) is sectional drawing after welding. It is sectional drawing which shows a 1st modification, (a) shows before welding, (b) shows after welding. It is a figure which shows the structure which suppresses the amount of protrusions of extra scale in the 1st modification, (a) shows before welding, (b) shows after welding. It is a figure which shows the 2nd modification. It is sectional drawing explaining arrangement | positioning of the liquid injection stopper.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an external appearance of a sealed battery according to the present embodiment, where (a) shows a lid side (referred to herein as the front side) of the battery, and (b) shows a back side of the battery. . The sealed battery has a battery power generation element group sealed in a container, and the container is constituted by the can 20 and the lid 1 shown in FIG. The container has a flat, substantially rectangular parallelepiped shape. The shallow bottom can 20 has a flat bottomed rectangular tube, and a battery power generation element group is accommodated in the can 20. By attaching the lid 1 to the opening of the can 20 by welding, the container is sealed.

  A can 20 having a substantially rectangular parallelepiped shape has a negative electrode terminal 23 disposed on one side surface in the longitudinal direction and a positive electrode terminal 22 disposed on the opposite side surface. The positive terminal 22 and the negative terminal 23 are fixed to the can 20 via an insulating resin 24. One side surface of the can 20 in a direction orthogonal to the longitudinal direction is provided with a cleavage valve 21 that operates when the internal pressure in the battery container increases. A recess 4 is formed in the vicinity of the positive terminal 22 of the lid 1. An opening 43 is formed inside the recess 4, and the opening 43 is sealed with the liquid injection stopper 2.

  FIG. 2 is an exploded perspective view showing an internal configuration of the sealed battery shown in FIG. The can 20 is a shallow container having a rectangular bottom surface, and the rectangular opening is sealed by the lid 1. Inside the can 20, the winding group 15 that is a battery power generation element group, the insulating sheet 16 </ b> A disposed between the winding group 15 and the lid 1, and the winding group 15 and the can 20 are disposed. And an insulating sheet 16B.

  As shown in FIG. 3, the wound group 15 includes a positive electrode foil 14 having a positive electrode material 11 coated on both surfaces and a negative electrode foil 13 having a negative electrode material 12 coated on both surfaces. The separator 10 is sandwiched between the positive foil 14 and the negative foil 13, and a wound group 15 is formed by winding them in a flat shape. That is, the wound group 15 wound in a spiral shape is flat along the winding axis.

  Returning to FIG. 2, a positive electrode uncoated portion 19 and a negative electrode uncoated portion 25 are formed on both sides in the longitudinal direction of the flat wound group 15. A positive electrode abutment plate 17 and a positive electrode current collector plate 18 are disposed on both the front and back sides of the positive electrode uncoated portion 19, and the current collector portion on the positive electrode side is formed by joining and integrating them by ultrasonic bonding. . Similarly, a negative electrode abutment plate 26 and a negative electrode current collector plate 27 are arranged on both the front and back sides of the negative electrode side uncoated portion 25, and these are joined together by ultrasonic bonding so that the current collector on the negative electrode side is integrated. Part is formed.

  The lid 1 is formed with a recess 4 in which an opening 43 for injecting an electrolytic solution is formed. The opening 43 of the recess 4 is sealed by the injection plug 2 after injecting the electrolytic solution. The liquid injection stopper 2 is disposed in the recess 4 and is laser welded. On the lid 1, the concave portion 4 is formed at a position facing the positive electrode holding plate 17 (that is, the positive electrode side current collecting portion) of the winding group 15. The can 20 and the lid 1 are sealed by laser welding.

  FIG. 4 is a cross-sectional view showing the liquid injection stopper 2 and the recess 4 in detail. FIG. 4A is a sectional view showing a state before laser welding, and FIG. 4B is a sectional view after laser welding. The recess 4 is formed by deep drawing the lid 1 made of a metal plate. The recess 4 has a first-stage recess 41 and a second-stage recess 42. The opening 43 for injecting the electrolytic solution is formed in the bottom surface portion of the second-stage recess 42. As a material of the lid 1, for example, an aluminum alloy of JIS standard A3003 is used.

  The liquid injection plug 2 includes a plug portion 6 that is inserted into the opening 43 and a flange portion 5 that is placed on the second-stage recess 42. The liquid injection stopper 2 is formed of the same material (JIS standard A3003) as the lid 1. Here, the thickness t <b> 2 of the flange portion 5 is set to the same dimension as the depth of the second-stage recess 42. As a result, the top surface of the liquid injection stopper 2 and the bottom surface of the first-stage recess 41 are substantially flush with each other. When laser welding the injection plug 2, the fitting portion 3, which is a side surface portion of the recess 42, and the flange portion 5 of the injection plug 2 are butt welded by laser welding, as shown in FIG. A weld 7 is formed. As a result, the opening 43 of the recess 4 is sealed by the liquid injection stopper 2.

  FIG. 5 shows a structure of a liquid injection stopper in a conventional sealed battery as a comparative example. Fig.5 (a) is sectional drawing before welding, FIG.5 (b) is sectional drawing after welding. Conventionally, a recess 1a having a depth t3 is processed in the lid 1 by cold forging, and an opening 43 as a liquid injection port is formed in the recess 1a. Then, the butted surfaces of the fitting portion 3 and the flange portion 5 of the concave portion 1a are laser-welded as shown in FIG. The thickness of the flange portion 5 of the liquid filling tap 2 is the same as the depth t3 of the recess 1a.

  The thickness t1 of the lid 1 is generally set to be thin, and may be set to about t1 = 0.5 mm, for example. Here, in order to prevent spatter from entering the inside of the battery by through welding, if welding is attempted under the condition that the welded portion 7 does not melt to the inside of the battery container, the thickness t1 of the lid 1 is 0.5 mm. The thickness of the butted surfaces (= depth t3 of the recess 1a) needs to be suppressed to about 0.25 mm. That is, in the case of the conventional structure, the butt face having a thickness of 0.25 mm is welded.

  On the other hand, in the case of the present embodiment, the depth t2 of the recess 42 on which the flange portion 5 is placed is made equal to the thickness t1 = 0.5 mm of the lid 1, so that the thickness of the butt surface is zero. .5 mm, and the welding strength is doubled. Since the bottom thickness of the recess 42 formed by the deep drawing process is the thickness t1 (= 0.5 mm) of the lid 1, even if the entire butt surface having a thickness of 0.5 mm is welded, There is no risk of melting up to the inside of the battery case.

  Thus, in this Embodiment, since the recessed part 42 is formed by deep drawing, the thickness of the flange part 5 can be made equal to the thickness of the lid | cover 1, and the improvement of welding strength can be aimed at. Further, the depth of the concave portion 42 and the thickness t2 of the flange portion 5 can be set larger than the thickness t1 of the lid 1 to increase the welding strength. As a result, the welding strength can be further improved while preventing the inner side of the battery container from being melted.

  FIG. 6 is a cross-sectional view showing a first modification of the present embodiment, where (a) shows before welding and (b) shows after welding. The first modification is different from the configuration shown in FIG. 4 described above in that the deep drawing is performed in one stage. That is, the recess 41 is formed by deep drawing. The depth t2 of the recess 41 is the same as the thickness t1 of the lid 1. The thickness of the flange portion 5 placed on the recess 41 is also t2. Moreover, the thickness of the bottom part of the recessed part 41 is also t1 similarly to the case of FIG. In this case, the flange portion 5 is butt welded to the fitting portion 3 that is the side surface of the recess 41 (see FIG. 6B). Also in the case of the first modification, as in the above-described embodiment, the thickness of the abutting surface can be the same as the thickness t1 of the lid 1 or larger than t1, and the welding strength should be twice or more that of the conventional one. Can do.

  By the way, when the level | step difference of deep drawing is one step, as shown in FIG.6 (b), the surplus of the welding part 7 arises, and the upper end of the welding part 7 protrudes outside the surface of the lid | cover 1. FIG. . For example, when such a surplus of the welded portion 7 protrudes greatly from the surface, in the configuration in which the battery is cooled by air-cooling in parallel with the surface of the lid 1, the cooling air flow may be hindered. . In the case of such an air cooling structure, the structure shown in FIG. 4, that is, a structure having two stages of deep drawing is more advantageous. That is, by providing the first-stage recess 42, it is possible to prevent the surplus of the welded portion 7 from protruding beyond the surface of the lid 1, and the surplus of welding inhibits the flow of cooling air. It can be set as a structure without.

  Even if the recess 4 has one stage, it is possible to keep the amount of protrusion of the extra scale small by adopting the configuration shown in FIG. In the example shown in FIG. 7A, the depth dimension t2 of the recess 41 is set to be larger than the thickness t1 of the flange portion 5 (here, the same thickness t1 as that of the lid 1). Therefore, even when the thickness of the butting surface is set to be the same as the thickness t 1 of the lid 1, the upper surface of the liquid filling tap 2 is recessed with respect to the surface of the lid 1. As a result, the amount of protrusion of the welded portion 7 can be suppressed.

  FIG. 8 is a diagram illustrating a second modification. In the embodiment described above, the lid 1 is deep-drawn to form a recess for placing the flange portion 5, but in the example shown in FIG. 8, the through-hole 1 b is formed in the lid 1, and the through-hole 1 b It has a structure in which a plate member 100 in which an opening 100a is formed is fixed to the back surface (surface inside the container) of the formed lid 1 by welding or the like. The plate member 100 is fixed to the lid 1 so that the opening 100a faces the through hole 1b. As a result, a recess 41 is formed in the lid 1, and an opening 100 a is formed in the approximate center of the bottom surface of the recess 41. The opening 100a is an opening for injecting an electrolytic solution. After the electrolytic solution is injected, the liquid injection plug 2 is mounted so that the plug portion 6 is inserted into the opening 100a, and the flange portion 5 and the lid 1 are butt welded by laser welding (see FIG. 8B).

  Thus, the separate plate member 100 in which the opening 100a is formed may be fixed to the back surface of the lid to form the recess 41. And the welding strength of the flange part 5 can be made into a sufficient magnitude | size by making the depth of the recessed part 41 comparable as the thickness of the lid | cover 1. FIG. Further, by setting the thickness of the plate member 100 to be approximately the same as the thickness of the lid 1, it is possible to prevent welding from penetrating into the container.

  Next, the arrangement of the liquid injection stopper 2 will be described with reference to FIG. As shown in FIG. 1, the sealed battery according to the present embodiment has a flat, substantially rectangular parallelepiped shape. The container is composed of a can 20 and a lid 1. The can 20, which is a flat bottomed rectangular tube, includes a rectangular bottom surface and four side surfaces standing from the bottom surface. On the other hand, the lid 1 is provided so as to close the rectangular opening of the can 20. FIG. 9 is a cross-sectional view showing a part including the recessed portion 4 of the sealed battery, and is a cross section taken in the battery longitudinal direction.

  A wound group 15 is accommodated in the can 20. An insulating cover 16 </ b> B is provided between the bottom surface of the can 20 and the wound group 15, and an insulating cover 16 </ b> A is provided between the lid 1 and the wound group 15. As described above, at the positive electrode side end portion of the wound group 15, the positive electrode backing plate 17, the positive electrode uncoated portion 19 and the positive electrode current collector plate 18 are integrated by ultrasonic bonding, and the positive electrode side current collector portion is integrated. It is composed. The positive electrode current collector plate 18 is laser-welded to a positive electrode terminal 22 provided on the bottom surface of the can 20. An insulating resin 24 is provided between the can 20 and the positive electrode terminal 22.

  An opening 43 formed in the lid 1 as a liquid injection port is disposed in a region of the lid 1 facing the positive electrode abutting plate 17. The thickness dimension of the integrated positive electrode side current collector is smaller than the thickness dimension of the wound group 15 main body. Therefore, an empty space is formed between the positive electrode plate 17 and the lid 1 in the battery container. In the present embodiment, in the region of the lid 1 that faces the empty space, a concave portion 4 that is recessed so as to drop into the inside of the battery is formed, and the bottom surface of the second-stage concave portion 42 that constitutes the concave portion 4. An opening 43 was formed in the substrate. And the opening 43 was sealed with the liquid injection stopper 2 by butt-welding the side peripheral part of the recessed part 42, and the edge part of the flange part 5. FIG. Thus, since the recessed part 4 was arrange | positioned using an empty space, the recessed part 4 for the injection stopper 2 can be formed, without increasing battery thickness.

  As described above, in the sealed battery according to the present embodiment, a part of the wall portion of the container in which the battery power generation element group is accommodated is recessed so as to fall into the inside of the container, thereby forming the recess 42. An opening 43 for injecting an electrolytic solution is provided on the bottom surface of 42. And the opening 43 was sealed by welding the periphery of the flange part 5 of the injection stopper 2 with the fitting part 3 which is a side periphery of the recessed part 42. FIG. Since the depth of the recess 42 can be set to be large regardless of the thickness of the lid 1 as a container, the thickness of the butted surface of the welded portion can be made thicker than before, and sufficient welding strength can be ensured. it can.

  In addition, by forming the recesses 41 and 42 by drawing the container wall, the recesses can be easily formed, and the cost can be reduced.

  Further, as shown in FIG. 7, the depth dimension t2 of the recess 41 is larger than the thickness dimension t1 of the flange portion 5, and the welded portion (welded portion) between the peripheral edge of the flange portion 5 and the side periphery of the recess 41 is provided. By setting the value 7) so that it does not protrude beyond the outer surface of the container, the weld 7 can be prevented from obstructing the flow of air-cooled air.

  Similarly, as shown in FIG. 4, the recess 4 is a two-stage recess having a first recess 41 and a second recess 42 formed inside the first recess 41, By setting the depth of the recessed portion 41 to such a depth that the welded portion (welded portion 7) between the peripheral edge of the flange portion 5 and the side periphery of the recessed portion 41 does not protrude from the outer surface of the container, the welded portion 7 is set. Can prevent the flow of air-cooled air.

  Further, in a sealed battery in which the container has a flat rectangular parallelepiped shape, the concave portion 4 is formed in the wall portion facing the current collecting portion of the flat battery power generation element group, thereby preventing an increase in the battery appearance size. can do.

  Each of the embodiments described above may be used alone or in combination. This is because the effects of the respective embodiments can be achieved independently or synergistically. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired. For example, in the above-described embodiment, a flat sealed battery has been described as an example. However, a closed battery having a structure in which a liquid stopper is welded to a container wall portion can be similarly applied. This is particularly effective when the container wall is thin.

  1: lid, 1a, 4, 41, 42: recess, 1b: through hole, 2: liquid injection stopper, 3: fitting part, 5: flange part, 6: stopper part, 7: welded part, 15: wound Group, 17: positive electrode plate, 18: positive electrode current collector plate, 20: can, 26 negative electrode plate, 27: negative electrode current collector plate, 43, 100a: opening, 100: plate member

Claims (6)

A container for storing battery power generation elements;
A recess in which a part of the wall portion of the container falls into the inside of the container, and a recess provided with an opening for injecting an electrolyte on the bottom surface thereof;
A sealing plug having a plug portion inserted into the opening and a flange portion placed in the recess,
The sealed battery is characterized in that the opening is sealed by the sealing plug by welding a peripheral edge of the flange portion and a side periphery of the concave portion. The sealed battery according to claim 1,
The sealed battery is characterized in that the recess is formed by drawing a container wall. The sealed battery according to claim 1 or 2,
The depth dimension of the concave portion is larger than the thickness dimension of the flange portion, and the welding portion between the peripheral edge of the flange portion and the side periphery of the concave portion does not protrude beyond the outer surface of the container. A sealed battery characterized by being set. The sealed battery according to claim 2,
The recess is a two-stage recess having a first recess and a second recess formed inside the first recess,
The second recess has the opening formed on the bottom surface, the flange portion is placed, and the periphery of the flange portion and the recess side periphery are welded,
The depth of the first recess is set to such a depth that the welded portion between the peripheral edge of the flange portion and the peripheral side of the recess does not protrude beyond the outer surface of the container. battery. The sealed battery according to any one of claims 1 to 4, wherein a depth dimension of the concave portion on which the flange portion is placed is set larger than a thickness dimension of the wall portion of the container. A sealed battery. The sealed battery according to any one of claims 1 to 5, wherein the battery power generation element group includes a wound group wound in a flat shape along a winding axis, and both ends of the wound group. A flat battery power generation element group provided with a current collector having a thickness direction dimension smaller than that of the wound group,
The sealed battery, wherein the container in which the flat battery power generation element group is accommodated has a flat rectangular parallelepiped shape, and the concave portion is formed in a wall portion facing the current collecting portion.

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