JP2020095872A - Cell - Google Patents

Abstract

To provide a cell in which interference between a collector terminal and other member is less likely to occur.SOLUTION: A cell 10 includes a wound electrode body 30, a battery case 20, an insulator film 38, a collector terminal 40 and an external terminal 70. The wound electrode body 30 has a collector foil laminate part 33 where a collector foil is laminated at the end in the winding axis direction. The collector terminal 40 includes an external terminal connection part 41 electrically connected with the external terminal 70, a flat part 44 joined to the collector foil laminate part 33, and an extension part 45 extending from the flat part 44. In the cross-sectional view, the extension part 45 is bent in a direction separating from the wound electrode body 30 so that the angle formed with the flat part 44 will be 170-176 degrees, and has a radius part 45R at the terminal part of a surface on the side facing the insulator film 38.SELECTED DRAWING: Figure 2

Description

The present invention relates to batteries.

Patent Document 1 discloses a wound electrode body having a pair of electrodes (a positive electrode and a negative electrode), a battery case accommodating the wound electrode body, and an inner wall of the battery case and the wound electrode body. A battery including an insulating film that separates the battery case from the wound electrode body, and a collector terminal electrically connected to the electrode inside the battery case is disclosed. Each electrode includes a current collecting foil having a thickness of about several μm to several tens of μm, and a mixture layer formed on the current collecting foil and containing an active material. In Patent Document 1, a flat plate-shaped current collecting terminal is welded to an end portion of the current collecting foil in the winding axis direction, and the electrode and the current collecting terminal are electrically connected. Note that Patent Documents 2 to 4 can be cited as other conventional techniques.

JP, 2005-041589, A JP, 2013-093160, A JP, 2007-299536, A JP-A-2007-134957

By the way, when the battery is used, vibration or shock may be applied to the battery from the outside. As a result, inside the battery, for example, the wound electrode body may oscillate around the welded and joined portion as a fulcrum. As a result, the lower end of the current collector terminal may interfere with the wound electrode body, and the current collector foil may be damaged. Also, if the lower end of the current collector terminal is bent vertically in a direction away from the wound electrode body in order to avoid interference with the wound electrode body, for example, when the electrode body is housed in a battery case, the current collector terminal is There is a risk that the lower end of the may interfere with the insulating film and damage the insulating film.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery in which interference between a current collecting terminal and other members does not easily occur.

According to the present invention, a wound electrode body including an electrode having a current collector foil and a mixture layer formed on the current collector foil, and a battery case having a terminal extraction hole and accommodating the wound electrode body. An insulating film disposed between the inner wall of the battery case and the wound electrode body to separate the battery case and the wound electrode body, and electrically connected to the electrode inside the battery case. And a current collecting terminal that is inserted into the terminal drawing hole and is drawn to the outside of the battery case, and an external terminal that is arranged outside the battery case and is electrically connected to the current collecting terminal. And a battery including: The wound electrode body has a collector foil laminated portion in which the collector foil is laminated at an end portion in the winding axis direction. The current collector terminal is an external terminal connection portion that is electrically connected to the external terminal, a flat portion that extends from the external terminal connection portion, and that is joined to the current collector foil laminate portion, and a flat portion. And an extending portion that extends. In a cross-sectional view, the extending portion is bent in a direction away from the wound electrode body so that an angle formed with the flat portion is 170 degrees or more and 176 degrees or less, and on the side facing the insulating film. It has a rounded portion at the end of the surface.

In the present invention, the extending portion of the collector terminal is bent at a predetermined angle in the direction away from the wound electrode body. This makes it difficult for the extending portion of the collector terminal and the wound electrode body to interfere with each other even when vibration or impact is applied to the battery. Therefore, damage to the collector foil can be suppressed. Further, in the present invention, the extending portion of the collector terminal has the rounded portion at the end portion of the surface facing the insulating film. This makes it difficult for the extending portion of the collector terminal and the insulating film to interfere with each other. Therefore, for example, insertability into the battery case at the time of manufacturing the battery can be improved, and damage to the insulating film can be suppressed.

It is a partially broken view which shows the battery which concerns on one Embodiment typically. It is the II-II sectional view taken on the line of FIG. It is an exploded perspective view which shows typically the wound electrode body which concerns on one Embodiment. It is a partially expanded view which shows typically the vicinity of the extension part of a negative electrode current collector terminal.

An embodiment of the battery proposed here will be described below with reference to the drawings. Note that matters other than matters particularly referred to in the present specification and matters necessary for carrying out the present invention can be understood as design matters for a person skilled in the art based on conventional technology in the field. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the field.

In the present specification, the term “battery” is a term that refers to all electricity storage devices that can take out electrical energy, and is a concept that includes primary batteries and secondary batteries. In addition, the term "secondary battery" is a term that refers to all electricity storage devices that can be repeatedly charged and discharged, and includes so-called storage batteries (so-called chemical batteries) such as lithium-ion secondary batteries and nickel-hydrogen batteries, and electric double layer capacitors. And the like (so-called physical battery).

FIG. 1 is a partially cutaway view of the battery 10. 2 is a sectional view taken along the line II-II in FIG. In the following description, the symbols F, Rr, L, R, U, and D in the drawings represent front, rear, left, right, up, and down, respectively, and the symbols X, Y, and Z in the drawings represent , Front-rear direction, left-right direction, and up-down direction, respectively. However, this is only a direction for convenience of description, and does not limit the installation form of the battery 10.

The battery 10 according to this embodiment is a lithium-ion secondary battery. The battery 10 includes a battery case 20, a wound electrode body 30, an electrolyte (not shown), an insulating film 38, a negative electrode current collector terminal 40, a negative electrode external terminal 70, a positive electrode current collector terminal 80, and a positive electrode external terminal 90. And are equipped with. The negative electrode current collector terminal 40 and the negative electrode external terminal 70 are electrically connected to each other to form a negative electrode terminal. In the present embodiment, the negative electrode current collector terminal 40 is an example of a current collector terminal, and the negative electrode external terminal 70 is an example of an external terminal. Further, the positive electrode current collector terminal 80 and the positive electrode external terminal 90 are electrically connected to each other to form a positive electrode terminal.

The battery case 20 is formed in a flat and bottomed rectangular parallelepiped shape. The battery case 20 includes a battery case body 21 having an opening 21A that is opened upward, and a lid 22 that closes the opening 21A. The outer shape of the battery case body 21 is a rectangular cylinder with a bottom. The battery case body 21 has a bottom surface 21B, a pair of wide surfaces 21W, and a pair of narrow surfaces 21N interposed between the pair of wide surfaces 21W. The bottom surface 21B faces the opening 21A. The pair of wide surfaces 21W extends upward from the front end and the rear end of the bottom surface 21B. The pair of wide surfaces 21W are arranged substantially parallel to each other along the front-rear direction X. The pair of narrow surfaces 21N extends upward from the left end and the right end of the bottom surface 21B. The pair of narrow surfaces 21N are arranged substantially parallel to each other in the left-right direction Y. The outer shape of the lid 22 is a substantially rectangular shape that matches the shape of the opening 21A. The lid 22 is fitted into the opening 21A of the battery case body 21. The seam 25 between the outer edge of the lid 22 and the peripheral edge of the opening 21A of the battery case body 21 is laser-welded. The lid 22 is fixed to the battery case body 21. The battery case 20 is sealed.

The material of the battery case 20 (specifically, the battery case body 21 and the lid 22) may be the same as that conventionally used, and is not particularly limited. From the viewpoint of heat dissipation and the like, the battery case 20 may be made of a lightweight and highly heat-conductive metal material, for example, aluminum or stainless steel (SUS). A terminal lead-out hole (through hole) H1 for the negative electrode and a terminal lead-out hole (through hole) H2 for the positive electrode are provided at both ends of the lid body 22 in the left-right direction Y, respectively. A negative electrode external terminal 70 and a positive electrode external terminal 90 are attached to the lid 22.

FIG. 3 is an exploded perspective view schematically showing the wound electrode body 30. The wound electrode body 30 is housed inside the battery case 20, that is, in a space surrounded by the battery case body 21 and the lid 22. The material and members forming the wound electrode body 30 may be the same as conventional ones and are not particularly limited. The wound electrode body 30 is configured by stacking a strip-shaped negative electrode sheet 32 and a strip-shaped positive electrode sheet 34 with a separator sheet 36 interposed therebetween and winding the wound sheet around a winding axis W. In addition, in this embodiment, the winding axis W direction corresponds to the left-right direction Y. The separator sheet 36 is, for example, a porous resin sheet such as polyethylene or polypropylene.

The negative electrode sheet 32 has a strip-shaped negative electrode current collector foil 32A, and a negative electrode mixture layer 32B fixed onto the negative electrode current collector foil 32A. The negative electrode current collector foil 32A is made of a conductive metal such as copper, a copper alloy, or nickel. The negative electrode current collector foil 32A is, for example, a copper foil. The negative electrode mixture layer 32B contains a negative electrode active material (for example, a carbon material such as graphite). The negative electrode mixture layer 32B is formed in a strip shape along one long side of the strip-shaped negative electrode current collector foil 32A with a width shorter than that of the negative electrode current collector foil 32A. At one end (right end in FIG. 3) of the wound electrode body 30 in the winding axis W direction, the negative electrode current collector foil 32A of the negative electrode sheet 32 extends to the right of the positive electrode sheet 34. At the right end of the wound electrode body 30, a negative electrode current collector foil laminated portion 33 in which a plurality of negative electrode current collector foils 32A extending rightward are stacked by winding is arranged. In the present embodiment, the negative electrode sheet 32 is an example of an electrode, and the negative electrode current collector foil laminated portion 33 is an example of a current collector foil laminated portion.

The positive electrode sheet 34 has a strip-shaped positive electrode current collector foil 34A and a positive electrode mixture layer 34B fixed on the positive electrode current collector foil 34A. The positive electrode current collector foil 34A is made of a conductive metal such as aluminum. The positive electrode current collector foil 34A is, for example, an aluminum foil. The positive electrode mixture layer 34B contains a positive electrode active material (for example, lithium transition metal composite oxide). The positive electrode mixture layer 34B is formed in a strip shape along one long side of the strip-shaped positive electrode collector foil 34A with a width shorter than that of the positive electrode collector foil 34A. At one end (left end in FIG. 3) of the wound electrode body 30 in the winding axis W direction, the positive electrode current collector foil 34A of the positive electrode sheet 34 extends to the left of the negative electrode sheet 32. At the left end of the wound electrode body 30, there is formed a positive electrode current collector foil laminated portion 35 in which a positive electrode current collector foil 34A extending to the left is stacked in multiple layers by winding.

As shown in FIG. 2, when viewed in the left-right direction Y, the negative electrode current collector foil stacking portions 33 are gathered together in the stacking direction (the front-back direction X in FIG. 2) orthogonal to the winding axis W direction of the wound electrode body 30. It has a thin portion 33M that is crushed and compressed, and a thick portion 33E that is relatively thicker than the thin portion 33M. The thin portion 33M is sandwiched between two thick portions 33E in the vertical direction Z. The thin portion 33M is formed in the central portion M when the wound electrode body 30 is divided into three parts in the vertical direction Z. As a result, the negative electrode current collector foil 32A is less likely to be broken, and the durability of the negative electrode terminal structure can be improved. In the present embodiment, the length of the thin portion 33M is longer than the total length of the length of the second lead portion 44 and the length of the extending portion 45 of the negative electrode current collector terminal 40 described below in the vertical direction. Although not particularly limited, the average thickness (average length in the front-rear direction X) t1 of the thin portion 33M may be approximately 0.2 to 2 mm, for example 0.5 to 0.7 mm. The maximum thickness (maximum length in the front-rear direction X) t2 of the thick portion 33E may be larger than t1 and may be approximately 3 to 30 mm, for example 8 to 12 mm. The negative electrode current collector terminal 40 is joined to one surface (the front surface in FIG. 2) of the thin portion 33M.

The electrolyte may be the same as the conventional one and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (non-aqueous electrolyte solution) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent is, for example, carbonate such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF ₆ .

The insulating film 38 is arranged between the inner wall of the battery case body 21 and the wound electrode body 30. The insulating film 38 is for isolating the battery case body 21 and the wound electrode body 30 from each other. The insulating film 38 is formed in a flat and bottomed bag shape. The insulating film 38 has an upper end opening that opens upward. The wound electrode body 30 is housed in the insulating film 38 through the upper end opening thereof. The insulating film 38 surrounds the wound electrode body 30 below, front and back, and left and right. The material of the insulating film 38 may be the same as the conventional one and is not particularly limited. The insulating film 38 is a film made of a resin material such as polyethylene or polypropylene. The insulating film 38 is housed in the battery case body 21 with the wound electrode body 30 held therein.

The negative electrode current collector terminal 40 is mainly located inside the battery case 20. The negative electrode current collector terminal 40 is electrically connected to the negative electrode current collector foil laminated portion 33 inside the battery case 20. The negative electrode current collector terminal 40 is inserted through the terminal lead-out hole H1 for the negative electrode and drawn out from the inside of the battery case 20 to the outside. The negative electrode current collector terminal 40 is fixed to the lid 22 while being insulated via the resin gasket 50 and the insulator 60. The negative electrode current collector terminal 40 is electrically connected to the negative electrode external terminal 70 for external connection outside the battery case 20. The negative electrode current collector terminal 40 constitutes a conduction path that electrically connects the negative electrode current collector foil laminated portion 33 and the negative electrode external terminal 70. The negative electrode current collector terminal 40 is made of a conductive metal such as copper, copper alloy, or nickel. The material of the negative electrode current collector terminal 40 may be the same as that of the negative electrode current collector foil 32A. The negative electrode current collector terminal 40 may be made of a material having a higher Young's modulus and higher rigidity than the positive electrode current collector terminal 80. The negative electrode current collector terminal 40 may be formed from a single metal plate by bending, for example, or may be formed by combining a plurality of metal members and integrating them.

As shown in FIGS. 1 and 2, the negative electrode current collector terminal 40 includes a pedestal portion 41, a first lead portion 42, a crank portion 43, a second lead portion 44, and an extending portion 45. In this embodiment, at least the first lead portion 42, the crank portion 43, the second lead portion 44, and the extending portion 45 are integrally punched out by press-punching a single metal plate. Although not particularly limited, the average thickness tm (not shown) of the metal plate may be approximately 1 mm or less, typically 0.5 to 1 mm, for example 0.6 mm. In the present embodiment, the first lead portion 42, the second lead portion 44, the crank portion 43, and the extending portion 45 have the same average thickness tm as the metal plate.

The pedestal portion 41 is arranged along the inner surface of the lid body 22. The pedestal portion 41 is in the shape of a rectangular flat plate that is wider on the outer peripheral side than the outer shape of the terminal extraction hole H1. The upper surface of the pedestal portion 41 faces the lid body 22 via the gasket 50. A rivet portion 41R is provided on the upper surface of the pedestal portion 41. The rivet portion 41R projects above the lid body 22. The rivet portion 41R has a shaft portion that is inserted into the terminal lead-out hole H1 of the battery case 20, and a rivet portion that is spread by crimping and crimped to the lid 22. The pedestal portion 41 is joined (fastened) to the negative electrode external terminal 70 by caulking. As a result, the negative electrode current collector terminal 40 is electrically connected to the negative electrode external terminal 70. In the present embodiment, the pedestal portion 41 is an example of the external terminal connection portion.

The first lead portion 42 is connected to the lower end of the pedestal portion 41. The first lead portion 42 is bent at a substantially right angle from the front end of the pedestal portion 41 and extends downward. The first lead portion 42 extends along the wide surface 21W of the battery case body 21. The first lead portion 42 extends toward the bottom surface 21B. The first lead portion 42 extends substantially perpendicular to the lid body 22. The first lead portion 42 has a flat plate shape with a uniform thickness. The crank portion 43 is bent in a crank shape from the lower end of the first lead portion 42 toward the rear in FIG. 2 and extends downward. The crank portion 43 is bent from the lower end of the first lead portion 42 so as to follow the outer shape of the negative electrode current collector foil laminated portion 33. The crank portion 43 connects the lower end of the first lead portion 42 and the upper end of the second lead portion 44.

The second lead portion 44 is connected to the lower end of the crank portion 43. The second lead portion 44 extends downward along the wide surface 21W of the battery case body 21. The second lead portion 44 extends toward the bottom surface 21B. The second lead portion 44 extends substantially perpendicular to the lid body 22. The second lead portion 44 has a flat plate shape with a uniform thickness. One side surface (the rear surface in FIG. 2) of the second lead portion 44 faces the wound electrode body 30. Specifically, it faces the thin portion 33M of the negative electrode current collector foil laminated portion 33. The thin portion 33M of the negative electrode current collector foil laminated portion 33 is welded and joined to the surface of the second lead portion 44 on the side facing the wound electrode body 30 to form the nugget N. Resistance welding is used to form the nugget N, for example. As a result, the negative electrode current collector terminal 40 is electrically connected to the negative electrode current collector foil laminated portion 33 via the nugget N. In the present embodiment, the second lead portion 44 is an example of a flat portion.

FIG. 4 is a partially enlarged view schematically showing the vicinity of the extending portion 45. The extending portion 45 is connected to the lower end of the second lead portion 44. One side surface (the rear surface in FIG. 2) of the extending portion 45 faces the thin portion 33M of the negative electrode current collector foil stacking portion 33. The other side surface (the front surface in FIG. 2) of the extending portion 45 faces the insulating film 38. The negative electrode current collector foil laminated portion 33 is not welded to the extending portion 45. In a cross-sectional view, the extending portion 45 is bent from the bending start point B so that the angle (bending angle) θ formed by the second lead portion 44 is 170 degrees or more and 176 degrees or less. The extending portion 45 is warped in the direction away from the wound electrode body 30 (forward and downward in FIG. 4 ). The extending portion 45 extends in a direction approaching the insulating film 38 (front of FIG. 4 ). The tip (for example, the end 45E) of the extension portion 45 faces outward. Although not particularly limited, the vertical length of the extending portion 45 in the vertical direction Z may be approximately 1 mm or less, for example, 0.5 to 1 mm.

The distance (gap) dx from the end 45E of the extending portion 45 to the thin portion 33M of the negative electrode current collector foil stacking portion 33 in the front-rear direction X is the maximum thickness t2 of the thick portion 33E minus the average thickness t1 of the thin portion 33M. It is preferable that the difference is smaller than the difference (t2-t1)/2. With this value, even if the extending portion 45 is bent, the extending portion 45 is prevented from jumping out of the thick portion 33E when viewed in the left-right direction Y. Therefore, the extending portion 45 and the insulating film 38 are less likely to contact each other. Although not particularly limited, the distance dx may be approximately 1 mm or less, typically 0.5 mm or less, for example, 0.25 to 0.5 mm. The distance dx may be smaller than the average thickness tm of the second lead portion 44, and may be 0.4 to 0.9 times the average thickness tm of the second lead portion 44, for example.

The extending portion 45 has a rounded portion 45R at the end portion (the lower end portion in FIG. 4) of the surface on the side facing the insulating film 38. In other words, the extending portion 45 has the rounded portion 45R at the end portion of the surface opposite to the side facing the wound electrode body 30. The rounded portion 45R is rounded so that a sharp edge is not formed on the surface facing the insulating film 38. The rounded portion 45R is curved (sagging) so as to hang down. For example, press punching is used to form the rounded portion 45R. Although not particularly limited, the radius of curvature of the rounded portion 45R may be approximately 0.1 to 0.3 mm, for example, 0.15 to 0.2 mm. Although not particularly limited, the length dz from the end 45D of the rounded portion 45R to the end 45E of the extending portion 45 may be approximately 0.5 mm or less, for example, 0.1 to 0.2 mm.

The negative electrode external terminal 70 is arranged outside the battery case 20. The negative electrode external terminal 70 has a Z-shaped metal fitting 72 and a terminal bolt 76. The Z-shaped metal fitting 72 and the terminal bolt 76 are connected by tightening a fixing nut (not shown). The Z-shaped metal fitting 72 is electrically connected to the negative electrode current collector terminal 40 by caulking. The terminal bolt 76 projects upward. The terminal bolt 76 is a connection terminal for external connection, and is a portion to which a bus bar is attached when, for example, a plurality of batteries 10 are combined to form an assembled battery.

The positive electrode current collector terminal 80 is mainly located inside the battery case 20. The positive electrode current collector terminal 80 is electrically connected to the positive electrode current collector foil laminated portion 35 inside the battery case 20. The positive electrode collector terminal 80 is inserted through the terminal lead-out hole H2 for the positive electrode and drawn out from the inside of the battery case 20 to the outside. The positive electrode current collector terminal 80 is fixed to the lid 22 while being insulated via the gasket 50 made of resin and the insulator 60. The positive electrode current collector terminal 80 is electrically connected to the positive electrode external terminal 90 for external connection outside the battery case 20. The positive electrode current collector terminal 80 constitutes a conduction path that electrically connects the positive electrode current collector foil laminated portion 35 and the positive electrode external terminal 90. The positive electrode current collector terminal 80 is made of a conductive metal such as aluminum or nickel. The material of the negative electrode current collector terminal 40 may be the same as that of the negative electrode current collector foil 32A. The structure of the positive electrode terminal is not particularly limited. The structure of the positive electrode terminal may be the same as the structure of the negative electrode terminal described above except that, for example, the material (metal type) of the collector foil or the collector terminal is different.

As described above, in the battery 10, at least the rigid collector terminal (negative electrode collector terminal 40) is bent at a predetermined angle in the direction in which the extending portion 45 moves away from the wound electrode body 30. This makes it difficult for the extending portion 45 and the wound electrode body 30 to interfere with each other even when vibration or impact is applied to the battery 10. Therefore, damage to the negative electrode current collector foil 32A can be suppressed. Further, in the battery 10, the rounded portion 45R is provided at the end portion of the surface of the extending portion 45 that faces the insulating film 38. This makes it difficult for the extending portion 45 and the insulating film 38 to interfere with each other. Therefore, for example, the insertability into the battery case body 21 at the time of manufacturing the battery can be improved, and the damage of the insulating film 38 can be suppressed.

Examples of the present invention will be described below, but the present invention is not intended to be limited to the specific examples.

The present inventors experimentally evaluated the above-mentioned effects. Specifically, first, a wound electrode body (Examples 1 and 2) to which a negative electrode current collector terminal made of copper having an extending portion as shown in Table 1 was attached was prepared. In addition, as Comparative Example 1, a wound electrode body using a copper negative electrode current collector terminal having no extending portion was prepared. Further, as Comparative Example 2, the same negative electrode collector as in Example 1 except that the end portion of the surface on the side facing the wound electrode body, in other words, the side surface on the opposite side of Examples 1 and 2 is provided with a rounded portion. A wound electrode body using an electric terminal was prepared. Next, a battery was constructed using each wound electrode body. Then, (1) insertability into a battery case during battery production, and (2) between the negative electrode current collector terminal and the wound electrode body when a large vibration is gradually applied to the battery by using a vibration tester. The buffer was evaluated.

As a result of the above evaluation, in Examples 1 and 2, the insertability into the battery case body was improved as compared with Comparative Example 2. Further, in Examples 1 and 2, compared with Comparative Example 1 using the conventional negative electrode current collector terminal, the extended portion and the wound electrode body were less likely to interfere with each other even when a large vibration was applied to the battery. The above results show the significance of the technology disclosed herein.

Although the present invention has been described above with reference to the preferred embodiment, such description is not a limitation and, of course, various modifications can be made.

10 Lithium Ion Secondary Battery 20 Battery Case 30 Winding Electrode Body 33 Negative Electrode Current Collector Foil Laminate (Current Foil Laminate)
40 Negative electrode current collector terminal (current collector terminal)
41 Pedestal part (external terminal connection part)
44 Second lead part (flat part)
45 Extension part 45R are part 70 Negative electrode external terminal (external terminal)

Claims (1)

A wound electrode body including an electrode having a collector foil and a mixture layer formed on the collector foil,
A battery case having a terminal lead-out hole and accommodating the wound electrode body;
An insulating film that is disposed between the inner wall of the battery case and the wound electrode body and separates the battery case from the wound electrode body,
A collector terminal that is electrically connected to the electrode inside the battery case, and is drawn out of the battery case through the terminal drawing hole.
A battery provided with an external terminal arranged outside the battery case and electrically connected to the current collecting terminal,
The wound electrode body has a collector foil laminated portion in which the collector foil is laminated at an end portion in the winding axis direction,
The collector terminal is
An external terminal connecting portion electrically connected to the external terminal,
A flat portion extending from the external terminal connecting portion and joined to the current collector foil laminated portion,
An extending portion extending from the flat portion,
In the cross-sectional view, the extending portion is bent in a direction away from the wound electrode body so that an angle formed with the flat portion is 170 degrees or more and 176 degrees or less, and on the side facing the insulating film. Has a rounded portion at the end of the surface,
battery.

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