Battery cell and battery module

Abstract

To firmly join a tab and an object to be joined to each other.SOLUTION: A battery cell 100A includes a positive electrode tab 110A. The positive electrode tab 110A includes a first base 111A, a first upper end portion 112A whose thickness decreases as it moves away from the first base portion 111A, and a first upper protrusion 114A located between the first base 111A and the first upper end 112A and protruding outward from the first base 111A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery cell and a battery module. [Background technology]

[0002] In recent years, various battery cells having battery elements such as lithium ion secondary batteries have been developed. The battery elements are sealed in an exterior material. Tabs such as a positive electrode tab and a negative electrode tab protrude from the exterior material.

[0003] An example of a battery cell tab is described in Patent Document 1. Both ends of the tab in the width direction are tapered.

[0004] Patent Document 2 describes an example of a battery cell tab. This tab has a copper strip and a nickel plating layer covering the copper strip. The thickness of the nickel plating layer is partially thicker at both ends in the width direction of the copper strip.

[0005] Patent Document 3 describes an example of a method for manufacturing a battery cell tab, in which a drawn wire is rolled by a rolling roll to form a tab.

[0006] An example of laser welding is described in Patent Document 4. In this method, two members are placed facing each other with a gap between them, and then the two members are joined to each other by laser welding. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2013-243015 A [Patent Document 2] JP 2016-134297 A [Patent Document 3] JP 2008-204902 A [Patent Document 4] Japanese Patent Application Publication No. 59-133985 Summary of the Invention [Problem to be solved by the invention]

[0008] A tab of a battery cell may be joined to a joining object such as another tab or a bus bar by laser welding. In this case, as described in Patent Document 4, for example, a laser may be irradiated to the tab and the joining object while the tab and the joining object are opposed to each other with a gap therebetween in order to firmly join the tab and the joining object. However, simply opposing the tab and the joining object may make it difficult to form an appropriate gap between the tab and the joining object.

[0009] One example of an object of the present invention is to firmly join a tab and an object to be joined to each other. Other objects of the present invention will become apparent from the description of this specification. [Means for solving the problem]

[0010] One aspect of the present invention is as follows. [1] With tabs, The tab has a base, an end portion whose thickness decreases with increasing distance from the base, and a protrusion located between the base and the end portion and protruding outward from the base. [2] The battery cell according to [1], wherein the tab further has another protrusion extending outward from the base toward the opposite side of the protrusion. [3] [1] or [2], and at least one other battery cell having at least one other tab; Equipped with the protrusion and the at least one other tab contact each other; the base and the at least one other tab are joined to each other via a gap. [4] With tabs, The tab of the battery cell has a base portion to be joined to an object to be joined, and a protrusion portion that protrudes outward from the base portion and comes into contact with the object to be joined. [5] The battery cell according to [4], wherein the tab further has another protrusion extending outward from the base toward the opposite side of the protrusion. [6] [4] or [5], and At least one other battery cell having at least one other tab as a joining target; A battery module comprising: Effect of the Invention

[0011] According to the above-described aspect of the present invention, the tab and the object to be joined can be firmly joined to each other. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a plan view of a portion of the battery module according to the first embodiment. [Diagram 2] 2 is a cross-sectional view along the line AA′ of FIG. 1. [Diagram 3] 13A and 13B are diagrams for explaining bonding between a positive electrode tab and a conductor. [Figure 4] 13 is a cross-sectional view of a joint between a plurality of positive electrode tabs and a plurality of negative electrode tabs in a battery module according to a modified example. FIG. [Diagram 5] 5A to 5C are diagrams illustrating an example of a method for producing a positive electrode tab according to the first embodiment. [Figure 6] 11 is a cross-sectional view of a joint between a positive electrode tab and a negative electrode tab in a battery module according to Embodiment 2. FIG. [Figure 7] 11 is a cross-sectional view of a joint between a positive electrode tab and a negative electrode tab in a battery module according to Embodiment 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings. In all the drawings, similar components are given similar reference numerals and descriptions thereof will be omitted as appropriate.

[0014] FIG. 1 is a plan view of a portion of a battery module 10A according to the first embodiment.

[0015] In FIG. 1, the X direction, Y direction, and Z direction are indicated for the purpose of explanation. The white circle with a black dot indicating the Z direction indicates that an arrow indicating the Z direction extends from the back of the page to the front. The X direction, Y direction, and Z direction are the front-rear direction, left-right direction, and up-down direction of the battery module 10A, respectively. The X direction, Y direction, and Z direction are mutually perpendicular. The arrow indicating the X direction, the arrow indicating the Y direction, and the arrow indicating the Z direction indicate the front direction, left direction, and up-down direction of the battery module 10A, respectively. However, the relationship between the X direction, the Y direction, the Z direction, and the front-rear direction, left-right direction, and up-down direction of the battery module 10A is not limited to the above-mentioned example.

[0016] Hereinafter, where necessary, a plane perpendicular to the X direction will be referred to as a YZ plane. Hereinafter, where necessary, a plane perpendicular to the Y direction will be referred to as a ZX plane. Hereinafter, where necessary, a plane perpendicular to the Z direction will be referred to as an XY plane.

[0017] The battery module 10A includes a plurality of battery cells 100A. The plurality of battery cells 100A are stacked substantially parallel to the Y direction. Each battery cell 100A includes a battery element 102, an exterior material 104, a positive electrode tab 110A, and a negative electrode tab 120A.

[0018] The battery element 102 has a substantially rectangular parallelepiped shape. The longitudinal direction of the battery element 102 is substantially parallel to the X direction. The lateral direction of the battery element 102 is substantially parallel to the Z direction. The thickness direction of the battery element 102 is substantially parallel to the Y direction. In one example, the battery element 102 includes a plurality of positive electrodes and a plurality of negative electrodes (not shown) alternately stacked in the Y direction, and a separator (not shown) located between the positive electrodes and the negative electrodes adjacent to each other in the Y direction. However, the structure of the battery element 102 is not limited to this example.

[0019] The exterior material 104 seals the battery element 102. The exterior material 104 includes, for example, a laminate film.

[0020] The positive electrode tab 110A is pulled out from the exterior material 104 at one of the front end and rear end of the battery cell 100A. The tip of the positive electrode tab 110A is bent substantially parallel to the Y direction. The positive electrode tab 110A is electrically connected to a positive electrode (not shown) of the battery element 102. The positive electrode tab 110A is made of a metal such as aluminum.

[0021] The negative electrode tab 120A is pulled out from the exterior material 104 at the other of the front end and rear end of the battery cell 100A. The tip of the negative electrode tab 120A is bent substantially parallel to the Y direction. The negative electrode tab 120A is electrically connected to a negative electrode (not shown) of the battery element 102. The negative electrode tab 120A is made of a metal such as copper.

[0022] In the first embodiment, the multiple battery cells 100A are connected in series. Specifically, at the front or rear of the battery cells 100A adjacent to each other in the Y direction, the tip of the positive electrode tab 110A of one battery cell 100A and the tip of the negative electrode tab 120A of the other battery cell 100A are overlapped and joined to each other approximately parallel to the X direction. The joints of the tip of the positive electrode tab 110A and the tip of the negative electrode tab 120A are alternately provided at the front and rear of the battery module 10A. In the example shown in FIG. 1, at the joint at the front of the battery module 10A, the negative electrode tab 120A is located in front of the positive electrode tab 110A. At the joint at the rear of the battery module 10A, the positive electrode tab 110A is located behind the negative electrode tab 120A.

[0023] Fig. 2 is a cross-sectional view taken along the line AA' in Fig. 1. In Fig. 2, a white circle with a black dot indicating the Y direction indicates that an arrow indicating the Y direction extends from the back of the page to the front.

[0024] Hereinafter, the AA' cross sections of the positive electrode tab 110A and the negative electrode tab 120A will be described. That is, a cross section perpendicular to the Y direction of the joint portion of the tip of the positive electrode tab 110A and the tip of the negative electrode tab 120A will be described. The cross section of the tip of the positive electrode tab 110A is substantially the same as the AA' cross section in other cross sections perpendicular to the extension direction of the positive electrode tab 110A. Similarly, the cross section of the tip of the negative electrode tab 120A is substantially the same as the AA' cross section in other cross sections perpendicular to the extension direction of the negative electrode tab 120A.

[0025] The positive electrode tab 110A includes a first base portion 111A, a first upper end portion 112A, a first lower end portion 113A, a pair of first upper protrusions 114A, and a pair of first lower protrusions 115A.

[0026] The thickness of the first base portion 111A in the X direction is substantially constant regardless of the position in the Z direction. The front and rear surfaces of the first base portion 111A are substantially parallel to the YZ plane. The thickness T1 of the first base portion 111A in the X direction is, for example, not less than 0.15 mm and not more than 1.0 mm.

[0027] The first upper end 112A has a substantially tapered shape. Specifically, the thickness of the first upper end 112A in the X direction decreases as it moves upward from the first base 111A. In the example shown in FIG. 2, the front surface of the first upper end 112A is inclined toward the rear as it moves upward. The rear surface of the first upper end 112A is inclined toward the front as it moves upward. In this case, the first upper end 112A can be easily sealed by the exterior material 104 compared to a case in which the thickness of the first upper end 112A in the X direction is substantially constant regardless of the position in the Z direction. Therefore, in the first embodiment, the sealing property of the exterior material 104 can be improved compared to a case in which the thickness of the first upper end 112A in the X direction is substantially constant regardless of the position in the Z direction.

[0028] The first lower end 113A has a substantially tapered shape. Specifically, the thickness of the first lower end 113A in the X direction decreases as it moves downward from the first base 111A. In the example shown in FIG. 2, the front surface of the first lower end 113A is inclined toward the rear as it moves downward. The rear surface of the first lower end 113A is inclined toward the front as it moves downward. In this case, the first lower end 113A can be easily sealed by the exterior material 104 compared to a case in which the thickness of the first lower end 113A in the X direction is substantially constant regardless of the position in the Z direction. Therefore, in the first embodiment, the sealing property of the exterior material 104 can be improved compared to a case in which the thickness of the first lower end 113A in the X direction is substantially constant regardless of the position in the Z direction.

[0029] 2, the cross-sectional shapes of the first upper end 112A and the first lower end 113A are substantially symmetrical. However, the cross-sectional shapes of the first upper end 112A and the first lower end 113A may be asymmetrical. Alternatively, the width in the X direction of one of the first upper end 112A and the first lower end 113A may be substantially constant regardless of the position in the Z direction.

[0030] The pair of first upper protrusions 114A are located between the first base 111A and the first upper end 112A in the Z direction. The pair of first upper protrusions 114A protrude outward in the X direction from the first base 111A. Specifically, the front first upper protrusion 114A protrudes forward from the front surface of the first base 111A. The front first upper protrusion 114A is curved convexly toward the front. The rear first upper protrusion 114A protrudes rearward from the rear surface of the first base 111A. The rear first upper protrusion 114A is curved convexly toward the rear. The maximum thickness T2 in the X direction of the portion where the pair of first upper protrusions 114A are provided in the positive electrode tab 110A is, for example, T1+10 μm or more and T1+200 μm or less, preferably T1+30 μm or more and T1+100 μm or less.

[0031] The cross-sectional shape of each of the first upper protrusions 114A is not limited to this example. For example, in the example shown in Fig. 2, the cross-sectional shapes of the pair of first upper protrusions 114A are substantially symmetrical. However, the cross-sectional shapes of the pair of first upper protrusions 114A may be asymmetrical.

[0032] The pair of first lower protrusions 115A are located between the first base 111A and the first lower end 113A in the Z direction. The pair of first lower protrusions 115A protrude outward in the X direction from the first base 111A. Specifically, the front first lower protrusion 115A protrudes forward from the front surface of the first base 111A. The front first lower protrusion 115A is curved forward in a convex manner. The rear first lower protrusion 115A protrudes rearward from the rear surface of the first base 111A. The rear first lower protrusion 115A is curved backward in a convex manner. The maximum thickness in the X direction of the portion of the positive electrode tab 110A where the pair of first lower protrusions 115A are provided may be equal to or different from the maximum thickness T2 described above.

[0033] The cross-sectional shape of each of the first lower protrusions 115A is not limited to this example. For example, in the example shown in Fig. 2, the cross-sectional shapes of the pair of first lower protrusions 115A are substantially symmetrical. However, the cross-sectional shapes of the pair of first lower protrusions 115A may be asymmetrical.

[0034] The height Δ in the X direction of the front end of the first upper protrusion 114A relative to the front surface of the first base 111A is, for example, more than 0 and 250 μm or less. The height in the X direction of the rear end of the rear first upper protrusion 114A relative to the rear surface of the first base 111A may be equal to or different from the height Δ. The height in the X direction of the front end of the front first lower protrusion 115A relative to the front surface of the first base 111A may be equal to or different from the height Δ. The height in the X direction of the rear end of the rear first lower protrusion 115A relative to the rear surface of the first base 111A may be equal to or different from the height Δ.

[0035] The difference T2-T1 between the maximum thickness T2 in the X direction of the portion of the positive electrode tab 110A where the pair of first upper protrusions 114A are provided and the thickness T1 in the X direction of the first base 111A is, for example, more than 0 and not more than 200 μm, preferably more than 0 and not more than 100 μm. The difference between the thickness in the X direction of the portion of the positive electrode tab 110A where the pair of first lower protrusions 115A are provided and the thickness T1 in the X direction of the first base 111A may be equal to or different from the difference T2-T1.

[0036] The negative electrode tab 120A, like the positive electrode tab 110A, includes a second base 121A, a second upper end 122A, a second lower end 123A, a pair of second upper protrusions 124A, and a pair of second lower protrusions 125A. In the first embodiment, the cross-sectional shape of the negative electrode tab 120A is substantially the same as that of the positive electrode tab 110A. However, the cross-sectional shape of the negative electrode tab 120A may be different from that of the positive electrode tab 110A.

[0037] The first base portion 111A and the second base portion 121A are joined to each other by a molten portion 130A. The molten portion 130A is formed by laser welding. In this laser welding, a laser is irradiated from the front of the negative electrode tab 120A toward the front surface of the negative electrode tab 120A. Therefore, the laser irradiated portion of the negative electrode tab 120A and the laser irradiated portion of the positive electrode tab 110A are melted to form the molten portion 130A.

[0038] In the first embodiment, the first upper protrusion 114A on the front side and the second upper protrusion 124A on the rear side are in contact with each other. Similarly, the first lower protrusion 115A on the front side and the second lower protrusion 125A on the rear side are in contact with each other. Therefore, a gap 150A is formed between the front surface of the first base 111A and the rear surface of the second base 121A. In the gap 150A, a part of the fusion zone 130A spreads approximately parallel to the YZ plane. Therefore, compared to the case where the front surface of the first base 111A and the rear surface of the second base 121A are in contact with each other, the fusion zone 130A can be increased in the amount of the fusion zone 130A spread in the gap 150A, by which the joining area of ​​the fusion zone 130A between the front surface of the first base 111A and the rear surface of the second base 121A can be increased. Therefore, in the first embodiment, the first base portion 111A and the second base portion 121A can be joined to each other more firmly than when the front surface of the first base portion 111A and the rear surface of the second base portion 121A are in contact with each other.

[0039] In the first embodiment, the width of the gap 150A in the X direction can be adjusted by the height in the X direction of the front first upper protrusion 114A and the front first lower protrusion 115A relative to the front surface of the first base 111A, and the height in the X direction of the rear second upper protrusion 124A and the rear second lower protrusion 125A relative to the rear surface of the second base 121A. Therefore, by adjusting the height of these protrusions, the width of the gap 150A in the X direction can be set to a width appropriate for laser welding.

[0040] In the first embodiment, the pair of first upper protrusions 114A protrude in opposite directions in the Y direction. The same is true for the pair of first lower protrusions 115A, the pair of second upper protrusions 124A, and the pair of second lower protrusions 125A. Therefore, even if the positions of the positive electrode tab 110A and the negative electrode tab 120A are interchanged in the X direction, a gap can be formed between the rear surface of the first base 111A and the front surface of the second base 121A. Depending on the battery module 10A, the positive electrode tab 110A may be disposed in front of the negative electrode tab 120A at the joint between the positive electrode tab 110A and the negative electrode tab 120A. Therefore, according to the positive electrode tab 110A and the negative electrode tab 120A according to the first embodiment, the first base 111A and the second base 121A can be firmly joined to each other regardless of the arrangement of the positive electrode tab 110A and the negative electrode tab 120A in the X direction. This improves the ease of assembly of the battery module 10A.

[0041] In the first embodiment, the protrusions of the positive electrode tab 110A are provided on both sides in the Z direction of the first base 111A. Therefore, compared to a case in which a protrusion is provided on only one of both sides in the Z direction of the first base 111A, the width in the X direction of the gap 150A between the positive electrode tab 110A and the negative electrode tab 120A can be set stably. However, the protrusions may be provided on only one side in the Z direction of the first base 111A. The same applies to the protrusions of the negative electrode tab 120A.

[0042] The cross-sectional shapes of the positive electrode tab 110A and the negative electrode tab 120A are not limited to the example shown in FIG.

[0043] For example, the rear surface of the positive electrode tab 110A and the front surface of the negative electrode tab 120A may be approximately parallel to the YZ plane. In this case, the first upper protrusion 114A and the first lower protrusion 115A may be provided only on the front surface of the positive electrode tab 110A. That is, the first upper protrusion 114A and the first lower protrusion 115A may be provided only on the surface of the positive electrode tab 110A facing the negative electrode tab 120A. In contrast, the second upper protrusion 124A and the second lower protrusion 125A may be provided only on the rear surface of the negative electrode tab 120A. That is, the second upper protrusion 124A and the second lower protrusion 125A may be provided only on the surface of the negative electrode tab 120A facing the positive electrode tab 110A. Even in this case, a gap 150A can be formed between the front surface of the first base 111A and the rear surface of the second base 121A.

[0044] Alternatively, one of the positive electrode tab 110A and the negative electrode tab 120A may not have a protrusion. In this example, the protrusion is provided on the front surface of the positive electrode tab 110A or the rear surface of the negative electrode tab 120A. In other words, the protrusion is provided on one of the surface of the positive electrode tab 110A facing the negative electrode tab 120A and the surface of the negative electrode tab 120A facing the positive electrode tab 110A. Even in this case, a gap 150A can be formed between the front surface of the first base 111A and the rear surface of the second base 121A.

[0045] FIG. 3 is a diagram for explaining the joining of the positive electrode tab 110A and the conductor 200. As shown in FIG.

[0046] In the example shown in Fig. 2, the negative electrode tab 120A is the joining target of the positive electrode tab 110A. However, the joining target of the positive electrode tab 110A is not limited to the negative electrode tab 120A. For example, as shown in Fig. 3, the joining target of the positive electrode tab 110A may be a conductor 200 that is approximately parallel to the YZ plane. An example of the conductor 200 is a bus bar that connects the battery module 10A to an external battery module (not shown).

[0047] In the example shown in FIG. 3, the first upper protrusion 114A and the first lower protrusion 115A on the side where the conductor 200 is located are in contact with the conductor 200. Therefore, a gap 250A is formed between the mutually opposing surfaces of the first base 111A and the conductor 200. In other words, the first base 111A and the conductor 200 are opposed to each other via the gap 250A. Therefore, as described with reference to FIG. 2, the first base 111A and the conductor 200 can be firmly joined to each other by laser welding, compared to the case where the first base 111A and the conductor 200 are in contact with each other.

[0048] 3 has been described regarding the joining of the positive electrode tab 110A and the conductor 200. The matters described with reference to FIG.

[0049] 4 is a cross-sectional view of a joint between a plurality of positive electrode tabs 110A and a plurality of negative electrode tabs 120A in a battery module 10A1 according to a modified example. The battery module 10A1 according to the modified example is similar to the battery module 10A according to the embodiment, except for the following points.

[0050] In the modified example, a plurality of positive electrode tabs 110A drawn from a plurality of battery cells 100A connected in parallel and a plurality of negative electrode tabs 120A drawn from a plurality of other battery cells 100A connected in parallel are joined to each other. In the example shown in Fig. 4, two positive electrode tabs 110A drawn from two battery cells 100A connected in parallel and two negative electrode tabs 120A drawn from two other battery cells 100A connected in parallel are joined to each other by a fusion portion 130A1. However, three or more positive electrode tabs 110A and three or more negative electrode tabs 120A may be joined to each other.

[0051] Each positive electrode tab 110A includes a pair of first upper protrusions 114A and a pair of first lower protrusions 115A. Each negative electrode tab 120A includes a pair of second upper protrusions 124A and a pair of second lower protrusions 125A. The protrusions are in contact with each other between adjacent tabs in the Y direction. Therefore, a gap is formed between the mutually facing surfaces of adjacent tabs in the Y direction. Therefore, as described in the first embodiment, the tabs adjacent in the Y direction can be firmly joined to each other, compared to the case where the mutually facing surfaces of adjacent tabs in the Y direction are in contact with each other.

[0052] 5 is a diagram for explaining an example of a manufacturing method of the positive electrode tab 110A according to the first embodiment. In FIG. 5, an arrow indicating the Z direction indicates the vertical upward direction. The X direction is one of the horizontal directions perpendicular to the Z direction. The Y direction is one of the horizontal directions perpendicular to both the Z direction and the X direction. In FIG. 5, the positive electrode workpiece 110 is shown in a see-through manner for the sake of explanation.

[0053] The positive electrode tab 110A is formed by rolling the positive electrode workpiece 110. In this rolling, a pair of first rollers 502 and a pair of second rollers 504 arranged on both sides of a predetermined central space 510 in the X direction are used. Each of the first rollers 502 and each of the second rollers 504 rotates around a rotation axis substantially parallel to the X direction. The pair of first rollers 502 face each other in the Z direction via a first tapered space 512. The width of the first tapered space 512 in the Z direction decreases as it moves away from the central space 510 in the X direction. The pair of second rollers 504 face each other in the Z direction via a second tapered space 514. The width of the second tapered space 514 in the Z direction decreases as it moves away from the central space 510 in the X direction.

[0054] The positive electrode workpiece 110 passes through the central space 510, the first tapered space 512, and the second tapered space 514 approximately parallel to the Y direction. The portion of the positive electrode workpiece 110 that passes through the central space 510 is formed in the first base portion 111A. The portion of the positive electrode workpiece 110 that passes through the first tapered space 512 is formed in one of the first upper end portion 112A and the first lower end portion 113A in a manner that substantially conforms to the shape of the first tapered space 512. The portion of the positive electrode workpiece 110 that passes through the second tapered space 514 is formed in the other of the first upper end portion 112A and the first lower end portion 113A in a manner that substantially conforms to the shape of the second tapered space 514.

[0055] In the example shown in FIG. 5, when one end of the positive electrode workpiece 110 in the X direction is compressed by the pair of first rollers 502, the material constituting the one end of the positive electrode workpiece 110 in the X direction is pushed toward the central space 510. As a result, a portion of the positive electrode workpiece 110 located between the central space 510 and the first tapered space 512 locally protrudes in the Z direction. Therefore, one of the pair of first upper protrusions 114A and the pair of first lower protrusions 115A is formed. When the other end of the positive electrode workpiece 110 in the X direction is also compressed by the pair of second rollers 504, the material constituting the other end of the positive electrode workpiece 110 in the X direction is pushed toward the central space 510. Therefore, for the same reason as described above, the other of the pair of first upper protrusions 114A and the pair of first lower protrusions 115A is formed.

[0056] The method for manufacturing the positive electrode tab 110A has been described with reference to Fig. 5. The method for manufacturing the negative electrode tab 120A can be the same as the method for manufacturing the positive electrode tab 110A.

[0057] 6 is a cross-sectional view of a joint between a positive electrode tab 110B and a negative electrode tab 120B in a battery module 10B according to embodiment 2. The battery module 10B according to embodiment 2 is similar to the battery module 10A according to embodiment 1 except for the following points.

[0058] The positive electrode tab 110B according to the second embodiment has a first base 111B, a pair of first upper protrusions 114B, and a pair of first lower protrusions 115B. The pair of first upper protrusions 114B are provided on the upper end of the first base 111B. The pair of first upper protrusions 114B protrude outward in the X direction from the first base 111B. The pair of first lower protrusions 115B are provided on the lower end of the first base 111B. The pair of first lower protrusions 115B protrude outward in the X direction from the first base 111B.

[0059] The negative electrode tab 120B according to the second embodiment has a second base 121B, a pair of second upper protrusions 124B, and a pair of second lower protrusions 125B. The pair of second upper protrusions 124B are provided on the upper end of the second base 121B. The pair of second lower protrusions 125B protrude outward in the X direction from the second base 121B. The pair of second lower protrusions 125B are provided on the lower end of the second base 121B. The pair of second lower protrusions 125B protrude outward in the X direction from the second base 121B.

[0060] In the second embodiment, similarly to the first embodiment, the first upper protrusion 114B on the front side and the second upper protrusion 124B on the rear side are in contact with each other. Similarly, the first lower protrusion 115B on the front side and the second lower protrusion 125B on the rear side are in contact with each other. Therefore, a gap 150B is formed between the front surface of the first base 111B and the rear surface of the second base 121B. In the gap 150B, a part of the molten part 130B spreads approximately parallel to the YZ plane. Therefore, as described in the first embodiment, the first base 111B and the second base 121B can be firmly joined to each other, compared to the case where the front surface of the first base 111B and the rear surface of the second base 121B are in contact with each other.

[0061] 7 is a cross-sectional view of a joint between a positive electrode tab 110C and a negative electrode tab 120C in a battery module 10C according to embodiment 3. The battery module 10C according to embodiment 2 is similar to the battery module 10A according to embodiment 1 except for the following points.

[0062] The positive electrode tab 110C according to the third embodiment has a first base 111C, a first upper end 112C, a first lower end 113C, a first upper protrusion 114C, and a first lower protrusion 115C. The rear surfaces of the first base 111C, the first upper end 112C, and the first lower end 113C are substantially parallel to the YZ plane and are substantially flush with each other. The first upper protrusion 114C is located between the first base 111C and the first upper end 112C in the Z direction. The first upper protrusion 114C protrudes forward from the front surface of the first base 111C. The first lower protrusion 115C is located between the first base 111C and the first lower end 113C in the Z direction. The first lower protrusion 115C protrudes forward from the front surface of the first base 111C.

[0063] The negative electrode tab 120C according to the third embodiment has a second base 121C, a second upper end 122C, a second lower end 123C, a second upper protrusion 124C, and a second lower protrusion 125C. The front surfaces of the second base 121C, the second upper end 122C, and the second lower end 123C are substantially parallel to the YZ plane and are substantially flush with each other. The second upper protrusion 124C is located between the second base 121C and the second upper end 122C in the Z direction. The second upper protrusion 124C protrudes rearward from the rear surface of the second base 121C. The second lower protrusion 125C is located between the second base 121C and the second lower end 123C in the Z direction. The second lower protrusion 125C protrudes rearward from the rear surface of the second base 121C.

[0064] In the third embodiment, the first upper protrusion 114C and the second upper protrusion 124C are in contact with each other, as in the first embodiment. Similarly, the first lower protrusion 115C and the second lower protrusion 125C are in contact with each other. Therefore, a gap 150C is formed between the front surface of the first base 111C and the rear surface of the second base 121C. In the gap 150C, a portion of the molten part 130C spreads approximately parallel to the YZ plane. Therefore, as described in the first embodiment, the first base 111C and the second base 121C can be firmly joined to each other, compared to the case where the front surface of the first base 111C and the rear surface of the second base 121C are in contact with each other. As shown in FIG. 7, even if the rear surface of the positive electrode tab 110C and the front surface of the negative electrode tab 120C are flat, the gap 150C can be formed by the first upper protrusion 114C, the first lower protrusion 115C, the second upper protrusion 124C, and the second lower protrusion 125C.

[0065] Although the embodiment and modified examples of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. [Explanation of symbols]

[0066] 10A, 10A1, 10B, 10C Battery Module 100A battery cell 102 Battery elements 104 Exterior materials 110 Positive electrode work 110A, 110B, 110C Positive tab 111A, 111B, 111C 1st base 112A,112C 1st upper end 113A,113C 1st lower end 114A, 114B, 114C 1st upper protrusion 115A, 115B, 115C 1st lower protrusion 120A, 120B, 120C Negative tab 121A, 121B, 121C 2nd base 122A, 122C 2nd upper end 123A, 123C 2nd lower end 124A, 124B, 124C 2nd upper protrusion 125A, 125B, 125C 2nd lower protrusion 130A, 130A1, 130B, 130C fusion zone 150A, 150B, 150C Gap 200 Conductor 250A Gap 502 First Roller 504 Second Roller 510 Central space 512 First tapered space 514 Second Tapered Space

Claims

1. With tabs, The battery cell, wherein the tab has a base, an end portion whose thickness decreases as it moves away from the base, and a protrusion located between the base and the end portion and protruding outward from the base.

2. The battery cell according to claim 1 , wherein the tab further has another protrusion extending outward from the base toward the opposite side of the protrusion.

3. The battery cell according to claim 1 or 2; at least one other battery cell having at least one other tab; Equipped with The battery module, wherein the base and the at least one other tab are joined to each other with the protrusion and the at least one other tab in contact with each other.

4. With tabs, The tab has a base portion that is joined to an object to be joined, and a protrusion portion that protrudes outward from the base portion and comes into contact with the object to be joined.

5. The battery cell according to claim 4 , wherein the tab further has another protrusion extending outward from the base portion on the opposite side to the protrusion.

6. The battery cell according to claim 4 or 5; at least one other battery cell having at least one other tab as the joining target; A battery module comprising:

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