JP2019125511A - Sealed battery - Google Patents

Abstract

To provide a sealed battery with high strength at the buttocks and reduced electrical resistance.SOLUTION: A sealed battery disclosed herein includes a battery case, an electrode body, an external terminal 460, and an internal terminal. The internal terminal includes a pedestal portion, a shaft portion, and a flange portion 430 that protrudes from a through hole of the external terminal 460 and is crimped to a peripheral portion surrounding the through hole of the external terminal 460. The flange portion 430 formed into an oval shape including a strength guaranteeing portion 432 having a perfect circular shape in a plan view, and a peripheral portion 434 provided on the periphery of a part of the strength guaranteeing portion 432 and welded to the external terminal 460. The peripheral portion 434 is provided in a conduction path between the strength guaranteeing portion 432 and the connection terminal 670 for external connection.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sealed battery.

  In Patent Documents 1 and 2, a battery case provided with a lid, an electrode body accommodated inside the battery case, an external terminal to which a connection terminal for external connection is connected, and one end are inside the battery case. A sealed battery is disclosed, comprising: an internal terminal connected to the electrode body, the other end being drawn out of the battery case, and electrically connected to the external terminal. Here, the lid and the external terminal each have a through hole. The internal terminal includes a pedestal and a cylindrical shaft projecting from the pedestal. The shaft portion is inserted from the inside of the battery case into the through-hole of the lid and the through-hole of the external terminal, and the tip portion protruding to the outside of the battery case is pushed out from the center to the outer periphery by caulking. It is deformed. Then, the tip end portion of the deformed shaft portion annularly covers the through hole of the external terminal, and a perfectly circular flange portion (crimped portion) is formed. Thus, the lid and the external terminal are fixed in a state of being sandwiched between the collar and the pedestal, and the external terminal, the internal terminal, and the battery case are integrally assembled. Further, Patent Document 1 describes that, after the above-mentioned assembly, the conduction between the internal terminal and the external terminal is secured by laser welding a partial peripheral edge of the flange portion with the external terminal.

JP, 2017-84585, A JP, 2009-259524, A

  By the way, a sealed battery may be mounted on a movable body such as a vehicle, for example, for use as a driving power source or storage of regenerative energy. In a sealed battery mounted on a moving body, force is applied to the buttocks from all directions by external vibration or impact. For this reason, the buttocks are required to have strength against inputs. According to the findings of the present inventors, as shown in the graph of FIG. 9, the strength of the buttocks tends to be stronger as the diameter of the buttocks in plan view is larger. In other words, the larger the perfect circle of the buttocks in plan view, the less the deformation occurs even if vibration or impact is applied from the outside, and the resistance to mechanical stress tends to be higher. However, if the buttocks and the external terminal are welded to ensure conduction, the heat of welding causes the material to be blunt and softened. As a result, as shown in the graph of FIG. 10, there is a problem that the hardness (Hv) is lowered at the welded portion (welded portion) compared to the non-welded portion (non-welded portion). is there.

  This can be a particular problem when welding is applied to a part of the periphery of a truly circular ridge. FIG. 11 is a plan view schematically showing the vicinity of an electrode external terminal according to a conventional example. As shown in FIG. 11, when a weld is formed by welding a part of the periphery of a perfect circular ridge, the diameter W of the strength guaranteeing part effective for securing the strength is a little smaller than the entire ridge, It will be necessary to secure strength with a diameter smaller than the actual outline of the buttocks. On the other hand, since the area of the lid is also limited, there is a need for a technique for efficiently securing the strength of the buttocks and enhancing the resistance to external vibration and the like. Further, from the viewpoint of improving battery performance, for example, input / output characteristics, it has been required to further reduce the electrical resistance between the internal terminal and the external terminal.

  This invention is created in view of the said subject, and the intensity | strength of a collar part is high, and an object of this invention is to provide the sealed type battery by which the electrical resistance was reduced.

  According to the present invention, a battery case having a through hole, an electrode body accommodated inside the battery case, an external terminal having a through hole, to which a connection terminal for external connection is connected, and one end of the battery case And an internal terminal electrically connected to the electrode body in the inside and electrically connected to the external terminal at the other end outside the battery case. The internal terminal comprises: a pedestal portion positioned inside the battery case; a shaft portion projecting from the pedestal portion and passing through the through hole of the battery case and the through hole of the external terminal; A collar portion provided at an end opposite to the side where the pedestal portion is located, protruding outward from the through hole of the external terminal, and crimped to a peripheral edge portion surrounding the through hole of the external terminal; Equipped with The flange portion is formed in an oval shape having, in a plan view, a strength ensuring portion having a perfect circle shape, and an edge portion provided on the periphery of a portion of the strength ensuring portion and welded to the external terminal. It is done. The peripheral portion is provided in a conduction path between the strength guaranteeing portion and the connection terminal for external connection.

  According to the above configuration, it is possible to widely secure the strength guaranteeing portion effective for securing the strength with respect to the entire area of the buttocks. Therefore, the strength against external vibration and impact can be efficiently enhanced. Moreover, conduction with the external terminal can be secured at the peripheral portion. In addition, by providing the peripheral portion in the conduction path between the strength guaranteeing portion and the connection terminal for external connection, the electrical conductivity can be improved and the electrical resistance can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a fragmentary sectional view which shows the sealed type battery which concerns on one Embodiment typically. It is a disassembled perspective view which shows typically the vicinity of the positive electrode current collection terminal before crimping process. It is the elements on larger scale which show the vicinity of a buttocks typically. It is a top view which shows the vicinity of a positive electrode current collection terminal typically. It is sectional drawing which shows typically the shape of the axial part before caulking processing. It is a top view which shows typically the shape of the ridge part formed by caulking. It is a perspective view which shows typically the modification of the axial part before caulking processing. It is the graph which showed the evaluation result of resistance in a test example. It is a graph which shows the relationship between the diameter of a crimping part, and a deformation amount (strength). It is the graph which compared the hardness of the buttocks. It is a top view which shows typically the vicinity of the electrode external terminal which concerns on a prior art example.

  Hereinafter, an embodiment of a sealed battery proposed here will be described with reference to the drawings. The matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be understood as the design matters of those skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field. Moreover, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show the same effect | action. In addition, dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships.

  FIG. 1 is a partial cross-sectional view of a sealed battery 10 according to the present embodiment. FIG. 2 is an exploded perspective view schematically showing the vicinity of the positive electrode current collector terminal 40 before caulking. FIG. 3 is a partially enlarged view schematically showing the vicinity of the ridge portion 430. As shown in FIG. FIG. 4 is a plan view schematically showing the vicinity of the positive electrode current collector terminal 40. The sealed battery 10 according to the present embodiment is a square battery. The shape of the sealed battery 10 is not limited to a square, and may be, for example, a cylindrical shape. The sealed battery 10 includes a battery case 20, an electrode body 30, an electrolyte (not shown), internal terminals 420 and 820, external terminals 460 and 860, a gasket 50, and an insulator 60. The sealed battery 10 is, for example, a secondary battery that can be repeatedly charged and discharged.

  The battery case 20 is formed in a flat and bottomed rectangular parallelepiped shape. The battery case 20 includes a battery case main body 21 having an opening 21A opened upward, and a lid 22 closing the opening 21A. The outer shape of the battery case main body 21 is a rectangular cylinder with a bottom. The outer shape of the lid 22 is a substantially rectangular shape that conforms to the shape of the opening 21A. The lid 22 is fitted into the opening 21 A of the battery case body 21. The seam 25 between the outer edge of the lid 22 and the periphery of the opening 21A of the battery case body 21 is laser welded. The lid 22 is fixed to the battery case body 21 by this.

  The material of the battery case 20 (specifically, the battery case body 21 and the lid 22) may be the same as that used conventionally, and is not particularly limited. From the viewpoint of heat dissipation and the like, the battery case 20 is preferably mainly made of a lightweight and thermally conductive metal material, such as aluminum or stainless steel (SUS). The lid 22 is provided with a terminal lead-out hole (through hole) 242 for the positive electrode and a terminal lead-out hole (through hole) 244 for the negative electrode which will be described later. The lid 22 is provided with a positive electrode external terminal 460 and a negative electrode external terminal 860 which will be described later.

  The electrode body 30 is housed inside the battery case 20. The electrode body 30 is a wound electrode body (wound electrode body) in the present embodiment. The material and member itself which comprise the electrode body 30 may be the same as before, and there is no restriction | limiting in particular. The electrode assembly 30 of this embodiment includes a positive electrode sheet 32 in which a positive electrode active material layer is fixed on a strip-shaped positive electrode current collector (for example, aluminum foil), and a negative electrode active on a strip-like negative electrode collector (for example, copper foil) A negative electrode sheet 34 having a material layer is stacked in a state in which the separator sheet 36 is interposed and wound in the long side direction. Examples of the positive electrode active material include lithium transition metal oxides. Examples of the negative electrode active material include carbon materials such as graphite. Examples of the separator sheet 36 include porous resin sheets such as polyethylene and polypropylene.

The electrolyte may be the same as in the prior art and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (non-aqueous electrolytic solution) containing a non-aqueous solvent and a support salt. The non-aqueous solvent is, for example, carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC). Supporting salt is, for example, a fluorine-containing lithium salt such as LiPF _6.

  The positive electrode current collector terminal 40 is connected to the positive electrode sheet 32. The positive electrode current collector terminal 40 penetrates the positive electrode terminal lead hole 242 provided on one end side (right end side in FIG. 1) of the lid 22 in the long side direction, and from the inside to the outside of the battery case 20. It is pulled out. The positive electrode current collecting terminal 40 is configured by electrically connecting a positive electrode internal terminal 420 located mainly inside the battery case 20 and a positive electrode external terminal 460 located outside the battery case 20. The positive electrode current collection terminal 40 (that is, the positive electrode internal terminal 420 and the positive electrode external terminal 460) is made of a conductive material such as copper or aluminum.

  The negative electrode current collector terminal 80 is connected to the negative electrode sheet 34 as in the case of the positive electrode side. The negative electrode current collector terminal 80 penetrates the terminal lead hole 244 for the negative electrode provided on one end side (left end in FIG. 1) of the lid 22 in the long side direction, and is drawn from the inside of the battery case 20 to the outside. It is done. Similar to the positive electrode side, the negative electrode current collection terminal 80 is configured by electrically connecting the negative electrode internal terminal 820 and the negative electrode external terminal 860. In addition, although the terminal structure which concerns on this embodiment below is demonstrated in detail at the positive electrode side, typically, the negative electrode side is equipped with the terminal structure of the same shape as the positive electrode side.

  The positive electrode internal terminal 420 includes a lead portion 422, a pedestal portion 424, and a shaft portion 426. The lower end 422 </ b> A of the positive electrode internal terminal 420 is joined to the positive electrode sheet 32 and is electrically connected to the positive electrode sheet 32. The lead portion 422 extends substantially perpendicularly to the lid 22 from the lower end 422A. The pedestal portion 424 is connected to the upper end of the lead portion 422, is bent substantially at right angles from the upper end of the lead portion 422, and extends from the back side to the front side in FIG. The pedestal portion 424 is in the form of a flat plate that extends outward from the outer shape of the terminal lead-out hole 242. The pedestal 424 extends substantially parallel to the inner surface of the lid 22. The shaft portion 426 extends substantially perpendicularly (in the vertical direction in FIGS. 1 to 3) from the central portion of the plate surface of the pedestal portion 424 toward the lid 22. The shank 426 is configured as a rivet. The shaft portion 426 is inserted through the positive electrode terminal lead-out hole 242 provided in the lid 22 and the through hole (rivet hole) 462 A of the positive electrode external terminal 460. In addition, in FIG. 3, the shape of the axial part 426 before caulking processing is represented by the dashed-two dotted line. The tip of the shaft portion 426 is pushed out by caulking. A collar 430 is formed at the tip of the crimped shaft 426. The shape of the collar 430 will be described in detail later. The collar portion 430 is caulked and fixed around the through hole 462A of the positive electrode external terminal 460. As a result, the positive electrode internal terminal 420 and the positive electrode external terminal 460 are joined (fastened).

  The positive electrode external terminal 460 is disposed on the outside of the battery case 20. The positive electrode external terminal 460 has a first connection portion 462 and a second connection portion 464 extending from the first connection portion 462. The first connection portion 462 has a through hole 462A through which the shaft portion 426 before caulking can be inserted. The through holes 462A are formed at positions corresponding to the terminal lead holes 242 for the positive electrode. The through hole 462 </ b> A has an inner diameter that allows fitting of the shaft portion 426 of the positive electrode internal terminal 420. The second connection portion 464 extends from the first connection portion 462 along the long side direction of the lid 22. The second connection portion 464 is bent in a crank shape in a direction away from the battery case 20. The second connection portion 464 is formed with a bolt insertion hole 464A through which the shaft portion 674 of the terminal bolt 670 can be inserted. In the present embodiment, the terminal bolt 670 is a connection terminal for external connection, and is, for example, a portion to which a bus bar is attached when configuring a battery pack. The second connection portion 464 is an example of a conduction path extending from the through hole 462A to the terminal bolt 670. The terminal bolt 670 protrudes upward from the second connection portion 464 by the shaft portion 674 passing through the bolt insertion hole 464A. The positive electrode external terminal 460 and the terminal bolt 670 are connected by tightening a fixing nut (not shown).

  The gasket 50 is disposed inside the battery case 20. The gasket 50 is a member that insulates the lid 22 of the battery case 20 and the shaft portion 426 of the positive electrode internal terminal 420. The gasket 50 is in the form of a flat plate extending substantially in parallel with the inner surface of the lid 22. The gasket 50 has a through hole 52 and a hollow cylindrical tubular portion 54 provided along the periphery of the through hole 52 in the center thereof. The through hole 52 is formed to be able to insert the shaft portion 426 before caulking. The cylindrical portion 54 is inserted into the terminal lead-out hole 242 of the lid 22 and has a function of preventing direct contact between the lid 22 and the shaft portion 426 of the positive electrode internal terminal 420. The cylindrical portion 54 is arranged such that the outer peripheral surface thereof is in contact with the inner peripheral surface of the through hole 462A, and the inner peripheral surface is in contact with the outer peripheral surface of the shaft portion 674 of the positive electrode internal terminal 420. In the gasket 50, a portion surrounding the through hole 462 A is crimped between the lid 22 and the pedestal portion 424 of the positive electrode internal terminal 420 and compressed in the axial direction of the shaft portion 674. As a result, the battery case 20 and the positive electrode internal terminal 420 are insulated, and the terminal lead hole 242 of the lid 22 is sealed (sealed). The gasket 50 has a resistance to the used electrolyte and an electrical insulating property, and is made of an elastically deformable resin material. Examples of such a resin material include fluorinated resins such as perfluoroalkoxy fluorine resin (PFA), and polyphenylene sulfide resin (PPS).

  The insulator 60 is disposed outside the battery case 20. The insulator 60 is a member that insulates the positive electrode external terminal 460 and the lid 22 of the battery case 20. The insulator 60 has an attachment portion 620 and an extension portion 640. The mounting portion 620 has a concave shape extending along the outer surface of the lid 22. The first connection portion 462 of the positive electrode external terminal 460 is placed on this concave recess. Through holes 622 are formed in the mounting portion 620 at positions corresponding to the terminal lead holes 242 for the positive electrode. The through hole 622 has an inner diameter that allows fitting of the shaft portion 426 of the positive electrode internal terminal 420. In the insulator 60, the portion surrounding the through hole 622 is sandwiched between the lid 22 and the positive electrode external terminal 460 by caulking, and is compressed in the axial direction of the shaft portion 674. The extension portion 640 extends between the second connection portion 464 of the positive electrode external terminal 460 and the lid 22. The extension 640 has a rectangular bolt receiving hole 642 capable of receiving the head 672 of the terminal bolt 670. By inserting the head portion 672 into the bolt receiving hole 642, the rotation is limited and the rotation is prevented. The insulator 60 has electrical insulation and is made of a resin material that can be elastically deformed. Examples of such resin materials include polyphenylene sulfide resin (PPS) and aliphatic polyamide.

  The sealed battery 10 disclosed herein has a rib portion 430 formed by caulking on the tip of the shaft portion 426 of the positive electrode internal terminal 420. As shown in FIG. 4, in plan view, the collar 430 has an asymmetrical elliptical shape. The collar portion 430 is formed in an oval shape having a pointed end and a blunt end provided at a position opposite to the pointed end in the long side direction of the lid 22. The collar portion 430 has a strength guaranteeing portion 432 and a peripheral portion 434 provided on the periphery of a part of the strength guaranteeing portion 432.

  Strength guarantee portion 432 has a perfect circular shape in plan view. Strength guarantee portion 432 has a substantially uniform thickness. The overall shape of the strength ensuring portion 432 is a substantially cylindrical shape. The center of the true circle shape of the strength guaranteeing portion 432 is located coaxially with the center of the shaft portion 426. The strength guaranteeing portion 432 is a portion which is not welded to the positive electrode external terminal 460, in other words, a portion which is not hampered by heat at the time of welding. In the strength guaranteeing section 432, the strength of the heel portion 430 can be maintained high. In the present embodiment, it is possible to use the strength guaranteeing portion 432 up to the full outer shape of the collar portion 430, and the diameter W1 of the strength guaranteeing portion 432 is secured large compared to, for example, patent documents 1 and 2. Therefore, the flange 430 exhibits high resistance to mechanical stress such as vibration or impact applied from the left and right direction (x direction), front and back direction (y direction), and vertical direction (z direction). it can.

  The peripheral portion 434 is located outside the strength guaranteeing portion 432 having a perfect circular shape in a plan view. The peripheral portion 434 constitutes a pointed portion of the ridge portion 430. The peripheral portion 434 is a portion welded to the positive electrode external terminal 460 by laser welding or the like. The peripheral portion 434 is provided, for example, in a range of about 1/10 to 1/3 of the entire peripheral edge of the strength guaranteeing portion 432. The peripheral portion 434 is a portion that ensures conduction with the positive electrode external terminal 460. At least a portion (preferably, the tip end portion) of the peripheral portion 434 is provided in the conduction path between the strength guaranteeing portion 432 and the terminal bolt 670. In the present embodiment, at least a portion (preferably, the tip end portion) of the peripheral portion 434 is provided closer to the second connection portion 464 and the terminal bolt 670 than the strength ensuring portion 432. By this, the electrical conductivity between the positive electrode internal terminal 420 and the terminal bolt 670 can be improved, and the electrical resistance can be reduced.

  The collar portion 430 having such a shape is formed by caulking. For example, first, the positive electrode internal terminal 420 having the shaft portion 426 is prepared. The shaft portion 426 shown by a two-dot chain line in FIG. 3 has a shape before caulking. The end of the shaft 426 away from the pedestal 424 has an asymmetrical shape. As one example, FIG. 5 schematically shows the cross-sectional shape of the shaft portion 426 before caulking. The shaft portion 426 has a different diameter R at the tip, and in this case, 3/4 of the tip of the shaft portion 426 is R0.5, and 1/4 is R0.1. It is biased to one side (left side in FIG. 5). Next, the shaft portion 426 of the positive electrode internal terminal 420 is penetrated sequentially from the inside of the battery case 20 to the gasket 50, the lid 22, the insulator 60 and the positive electrode external terminal 460 to project outside the lid 22. . Then, the portion protruding from the lid 22 is crimped so that a compressive force is applied in the axial direction of the shaft portion 426, and the gasket 50, the lid 22, the insulator 60, and the positive electrode external terminal 460 are crimped and fixed. .

  By this caulking process, a collar portion 430 is formed at the tip of the shaft portion 426 of the positive electrode internal terminal 420. As one example, FIG. 6 schematically shows the shape of the collar portion 430. As shown in FIG. The collar portion 430 is formed by caulking the shaft portion 426 of FIG. Here, the side with less caulking material (in other words, the side with the large tip R, the right side in FIGS. 5 and 6) is formed at the blunt end, and the side with a large amount of caulking material (in other words, the side with the small tip R) The left side of 5 and 6) is formed at the tip, and a generally oval shaped wedge portion 430 is realized. Then, a perfect circular portion shown by a broken line portion constitutes the strength guaranteeing portion 432, and a portion protruding from the perfect circle portion constitutes the peripheral portion 434.

  The shape of the tip of the shaft portion 426 before caulking is not limited to the shape as shown in FIG. For example, FIG. 7 is a perspective view schematically showing a modification of the shaft portion 426 before caulking. By forming the end of the shaft portion 426 to be inclined obliquely upward from one side to the other side in this manner, as in the case of FIG. 6, an ovoid shaped collar portion 430 is formed as a whole. Can.

  Next, the peripheral portion 434 is irradiated with laser light to laser weld the peripheral portion 434 and the positive electrode external terminal 460. The laser welding may be performed simultaneously (with one laser beam irradiation) on the positive electrode side and the negative electrode side. In the present embodiment, the laser welded peripheral portion 434 is provided on the side closer to the second connection portion 464 and the terminal bolt 670. For this reason, even when the positive electrode side and the negative electrode side are simultaneously laser welded, the incident angle of the laser can be set small. As a result, the occurrence of processing defects due to the reflection of laser light can be suppressed to a low level. This can increase the yield and improve the productivity.

  As described above, the sealed battery 10 according to the present embodiment is the brim portion 430 formed by caulking, and includes the strength guaranteeing portion 432 having a perfect circular shape and the peripheral portion 434 provided on the periphery of a part thereof. , And has an ovoid-shaped butt portion 430. By forming the collar portion 430 in such a shape, the strength guaranteeing portion 432 effective for securing strength can be widely secured in the collar portion 430 of the limited space. Therefore, the strength of the flange portion 430 against external vibration and impact can be efficiently enhanced. In addition, by providing the peripheral portion 434 between the strength guaranteeing portion 432 and the terminal bolt 670, the electrical resistance can be further reduced, and the battery performance can be improved.

  The inventors of the present invention experimentally evaluated the effects of the sealed battery 10. In this test example, as shown in FIG. 8, an evaluation battery was produced in which the position of the peripheral edge portion of the buttocks was made different from A to C with respect to the true circular strength guaranteeing portion. That is, in the sealed battery of C, the peripheral edge portion is provided between the strength guaranteeing portion and the terminal bolt in the long side direction of the lid. In the sealed battery of B, the peripheral portion and the strength guaranteeing portion are provided side by side in the long side direction of the lid. In the sealed battery of A, the peripheral edge portion is provided on the side away from the terminal bolt in the long side direction of the lid. The configuration of the evaluation battery is the same except that the arrangement of the oval end portion of the collar portion 430 is different. And the electrical resistance R between the positive electrode internal terminal 420 and the positive electrode external terminal 460 was measured about the said battery for evaluation. The results are shown as relative values in FIG.

  As shown in FIG. 8, by providing the peripheral portion 428 in the middle of the conduction path from the strength guaranteeing section 432 to the terminal bolt 670, the electrical conductivity between the positive electrode internal terminal 420 and the terminal bolt 670 is improved. , Could reduce the electrical resistance.

  Although the present invention has been described above by the preferred embodiments, such descriptions are not restrictive and, of course, various modifications are possible.

DESCRIPTION OF SYMBOLS 10 Sealed type battery 20 Battery case 22 Lid 30 Electrode body 50 Gasket 60 Insulator 242 Positive terminal side lead hole 420 Positive electrode internal terminal 430 Flange portion 432 Strength guarantee portion 434 Peripheral portion 460 Positive electrode external terminal

Claims (1)

A battery case having a through hole;
An electrode body housed inside the battery case;
An external terminal having a through hole and to which a connection terminal for external connection is connected;
An internal terminal having one end electrically connected to the electrode body inside the battery case and the other end electrically connected to the external terminal outside the battery case;
A sealed battery comprising:
The internal terminal is
A pedestal located inside the battery case;
A shaft portion which protrudes from the pedestal portion and passes through the through hole of the battery case and the through hole of the external terminal;
It is provided at the end opposite to the side where the pedestal of the shaft portion is located, is protruded to the outside from the through hole of the external terminal, and is crimped to a peripheral portion surrounding the through hole of the external terminal With buttocks,
Equipped with
The flange portion is formed in an oval shape having, in a plan view, a strength ensuring portion having a perfect circle shape, and an edge portion provided on the periphery of a part of the strength ensuring portion and welded to the external terminal. Has been
The peripheral portion is provided in a conduction path between the strength guaranteeing portion and the connection terminal for external connection.
Sealed battery.

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