Battery module manufacturing method

Abstract

To improve the productivity of a battery module.SOLUTION: A battery module 10 includes a positive electrode tab 112 and a negative electrode tab 114. The positive electrode tab 112 and the negative electrode tab 114 have an overlapping portion OL and a joint portion JC. At the overlapping portion OL, the positive electrode tab 112 and the negative electrode tab 114 overlap. The joint portion JC is located at the overlapping portion OL. At the joint portion JC, the positive electrode tab 112 and the negative electrode tab 114 are joined. The joint portion JC is positioned offset from the center of the overlapping portion OL.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In recent years, various battery modules have been developed that include multiple battery cells. Each battery cell includes a battery element, an exterior material that seals the battery element, and a positive electrode tab and a negative electrode tab that are pulled out from the exterior material.

[0003] Patent Document 1 describes an example of a battery module in which the positive electrode tab of a single battery cell or a plurality of battery cells connected in parallel is joined by laser welding to the negative electrode tabs of a single battery cell or a plurality of other battery cells connected in parallel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2006 / 109610 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, as described in Patent Document 1, the positive electrode tab of at least one battery cell may be joined to the negative electrode tab of at least one other battery cell. However, simply joining the positive electrode tab and the negative electrode tab may make it difficult to improve the robustness of the area where the joint between the positive electrode tab and the negative electrode tab is formed. Therefore, simply joining the positive electrode tab and the negative electrode tab may make it difficult to improve the productivity of the battery module.

[0006] An example of an object of the present invention is to improve the productivity of battery modules. Other objects of the present invention will become apparent from the description of this specification. [Means for solving the problem]

[0007] One aspect of the present invention is as follows. [1] at least one positive electrode tab; at least one negative electrode tab having an overlapping portion overlapping the at least one positive electrode tab and a joining portion located in the overlapping portion and joined to the at least one positive electrode tab; Equipped with the joint portion is disposed offset from the center of the overlapping portion. [2] The battery module according to [1], wherein the joints are formed by wobbling welding. [3] The battery module according to [1] or [2], wherein the at least one positive electrode tab and the at least one negative electrode tab have another joint portion disposed offset from the joint portion. [4] at least one positive electrode tab; at least one negative electrode tab having an overlapping portion overlapping the at least one positive electrode tab and a plurality of joining portions located in the overlapping portion and joined to the at least one positive electrode tab, the joining portions being shifted from one another; A battery module comprising: [5] [4] The battery module according to [4], wherein none of the plurality of joints overlaps with each other at the interface between the at least one positive electrode tab and the at least one negative electrode tab. [6] [5] The battery module according to [5], wherein at least a portion of the plurality of joints overlaps with each other in a region different from the interface of the at least one positive electrode tab and the at least one negative electrode tab. [Effects of the Invention]

[0008] According to the above aspect of the present invention, the productivity of battery modules can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a battery module according to an embodiment. [Figure 2] FIG. 2 is a top view of a front portion of a part of a battery module according to an embodiment. [Figure 3] FIG. 2 is a front view of the tip portion of a positive electrode tab and the tip portion of a negative electrode tab according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along the line AA′ of FIG. [Figure 5] 10A and 10B are diagrams for explaining the joint portion according to the embodiment and other joint portions. [Figure 6] FIG. 10 is a top view of a front portion of a battery module according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted as appropriate.

[0011] FIG. 1 is a perspective view of a battery module 10 according to an embodiment.

[0012] For ease of explanation, arrows indicating the X, Y, and Z directions are shown in each figure. The X direction indicates the front-to-rear direction of the battery module 10. Unless otherwise specified, the tip of an arrow indicating the X direction will refer to the rear side of the battery module 10. Unless otherwise specified, the base end of an arrow indicating the X direction will refer to the front side of the battery module 10. The Y direction is perpendicular to the X direction. The Y direction indicates the left-to-right direction of the battery module 10. Unless otherwise specified, the tip of an arrow indicating the Y direction will refer to the left side of the battery module 10. Unless otherwise specified, the base end of an arrow indicating the Y direction will refer to the right side of the battery module 10. The Z direction is perpendicular to both the X and Y directions. The Z direction indicates the up-down direction of the battery module 10. Unless otherwise specified, the tip of an arrow indicating the Z direction will refer to the upper side of the battery module 10. Unless otherwise specified, the base end of an arrow indicating the Z direction will refer to the lower side of the battery module 10. However, the relationship between the X direction, Y direction, and Z direction and the front-rear direction, left-right direction, and up-down direction of the battery module 10 is not limited to the above example. These relationships will vary depending on the actual arrangement of the battery module 10.

[0013] The battery module 10 will be described with reference to FIG.

[0014] The battery module 10 includes a plurality of parallel cell groups 100G. The plurality of parallel cell groups 100G are stacked in the Y direction. Each parallel cell group 100G includes a plurality of battery cells 100 connected in parallel. In the example shown in FIG. 1, each parallel cell group 100G includes two battery cells 100 connected in parallel. However, each parallel cell group 100G may include three or more battery cells 100 connected in parallel. The plurality of battery cells 100 included in each parallel cell group 100G are stacked in the Y direction. The longitudinal direction of each battery cell 100 is approximately parallel to the X direction. The lateral direction of each battery cell 100 is approximately parallel to the Z direction. The thickness direction of each battery cell 100 is approximately parallel to the Y direction. However, the structure of each battery cell 100 is not limited to this example. Each battery cell 100 includes an exterior material 102, a positive electrode tab 112, and a negative electrode tab 114.

[0015] The exterior material 102 seals a battery element (not shown) and an electrolyte solution. The battery element includes, for example, a plurality of positive electrodes and a plurality of negative electrodes alternately stacked in the Y direction, and a separator positioned between the positive electrodes and negative electrodes adjacent to each other in the Y direction. However, the structure of the battery element is not limited to this example.

[0016] The positive electrode tab 112 and the negative electrode tab 114 are drawn out from opposite sides of the exterior packaging material 102 in the X direction. The positive electrode tab 112 is electrically connected to the positive electrode described above within the area sealed by the exterior packaging material 102. The positive electrode tab 112 is made of, for example, aluminum. The negative electrode tab 114 is made of, for example, copper. The negative electrode tab 114 is electrically connected to the negative electrode described above within the area sealed by the exterior packaging material 102.

[0017] In the example shown in FIG. 1 , multiple parallel cell groups 100G are connected in series. Specifically, multiple positive electrode tabs 112 drawn from multiple battery cells 100 included in each parallel cell group 100G are oriented toward the same side in the X direction. Similarly, multiple negative electrode tabs 114 drawn from multiple battery cells 100 included in each parallel cell group 100G are oriented toward the same side in the X direction. Multiple positive electrode tabs 112 and multiple negative electrode tabs 114 drawn from one of the parallel cell groups 100G adjacent in the Y direction are oriented toward opposite sides in the X direction. Parallel cell groups 100G adjacent in the Y direction each have a tab group 110. The tab group 110 is located in front of or behind the parallel cell groups 100G adjacent in the Y direction. The tab group 110 includes a plurality of positive electrode tabs 112 drawn from one of the parallel cell groups 100G adjacent in the Y direction, and a plurality of negative electrode tabs 114 drawn from the other of the parallel cell groups 100G adjacent in the Y direction. In the tab group 110, the plurality of positive electrode tabs 112 and the plurality of negative electrode tabs 114 are joined to each other.

[0018] The plurality of tab groups 110 located in front of the battery module 10 and the plurality of tab groups 110 located in the rear of the battery module 10 are arranged alternately in the Y direction. For example, in the example shown in Fig. 1 , the leftmost parallel cell group 100G and the second-most parallel cell group 100G from the left have tab groups 110 located in front of these parallel cell groups 100G. In addition, the second-most parallel cell group 100G and the third-most parallel cell group 100G from the left have tab groups 110 located behind these parallel cell groups 100G.

[0019] FIG. 2 is a top view of the front portion of a portion of a battery module 10 according to an embodiment. FIG. 3 is a front view of the tip portion of a positive electrode tab 112 and the tip portion of a negative electrode tab 114 according to an embodiment. FIG. 4 is a cross-sectional view taken along the line AA' in FIG. 3. In FIGS. 2 and 4, the white circle with a black dot indicating the Z direction indicates the upper side of the battery module 10 from the back to the front of the page, and the lower side of the battery module 10 from the front to the back of the page. In FIG. 3, the white circle with an X indicating the X direction indicates the rear side of the battery module 10 from the front to the back of the page, and the front side of the battery module 10 from the back to the front of the page.

[0020] The tip portion of the positive electrode tab 112 and the tip portion of the negative electrode tab 114 will be described with reference to FIG.

[0021] 2 exemplarily shows two parallel cell groups 100G adjacent to each other in the Y direction. Two positive electrode tabs 112 extend forward from the two battery cells 100 included in the right-side parallel cell group 100G. When viewed from above, the tips of the two positive electrode tabs 112 are bent toward the left. Two negative electrode tabs 114 extend forward from the two battery cells 100 included in the left-side parallel cell group 100G. When viewed from above, the tips of the two negative electrode tabs 114 are bent toward the right.

[0022] The tip portions of the two positive electrode tabs 112 shown in FIG. 2 and the tip portions of the two negative electrode tabs 114 shown in FIG. 2 have an overlapping portion OL. At the overlapping portion OL, the tip portions of the two positive electrode tabs 112 and the tip portions of the two negative electrode tabs 114 overlap in the X direction. In the example shown in FIG. 2, the tip portion of the negative electrode tab 114 is located in front of the tip portion of the positive electrode tab 112. However, the tip portion of the positive electrode tab 112 may also be located in front of the tip portion of the negative electrode tab 114.

[0023] The tip ends of the two positive electrode tabs 112 shown in Fig. 2 and the tip ends of the two negative electrode tabs 114 shown in Fig. 2 have a joint JC. The joint JC is located at the overlapping portion OL. At the joint JC, the tip ends of the two positive electrode tabs 112 and the tip ends of the two negative electrode tabs 114 are joined to each other.

[0024] FIG. 2 illustrates an imaginary center line CL. When viewed from above, the imaginary center line CL passes through the center of the overlapping portion OL in the Y direction parallel to the X direction. In the example shown in FIG. 2, when viewed from above, the joint JC is positioned offset to the right from the imaginary center line CL. To increase the bonding strength between the positive electrode tab 112 and the negative electrode tab 114, another joint may be formed in a portion of the overlapping portion OL offset in the Y direction from the joint JC. In the example shown in FIG. 2, when viewed from above, the other joint can be formed in a portion of the overlapping portion OL to the left of the joint JC. In the example shown in FIG. 2, the left side of the joint JC is on the opposite side of the direction of offset of the joint JC from the imaginary center line CL when viewed from above. Therefore, in the example shown in FIG. 2, the width in the Y direction of the portion of the overlapping portion OL where the other joint is formed can be wider than when the joint JC is positioned at the center of the overlapping portion OL in the Y direction. Therefore, in the embodiment, the robustness of the area of ​​the portion of the overlapping portion OL where the other joint is formed can be improved. Therefore, in the embodiment, the productivity of the battery module 10 can be improved.

[0025] When viewed from above, the joint JC may be positioned offset to the left of the imaginary center line CL. Even in this case, as described above, the width of the portion of the overlapping portion OL where the other joints are formed can be made wider in the Y direction compared to when the joint JC is positioned at the center of the overlapping portion OL in the Y direction. Therefore, even in this example, the productivity of the battery module 10 can be improved.

[0026] When viewed from above, the distance in the Y direction between the joint JC and the imaginary center line CL can be, for example, at least ¼ of the width of the overlapping portion OL in the Y direction. In this case, the width in the Y direction of the portion of the overlapping portion OL where the other joint described above is formed can be made wider than when the distance is less than this value. This makes it easier to form the other joint described above in that portion of the overlapping portion OL.

[0027] When viewed from above, the upper limit of the distance in the Y direction between the joint JC and the imaginary center line CL is not particularly limited, as long as the entire joint JC is located at the overlapping portion OL. For example, when viewed from above, if the joint JC is located to the right of the imaginary center line CL, the joint JC can be shifted to the right from the imaginary center line CL as long as the right end of the joint JC is not located to the right of the right end of the overlapping portion OL. That is, in this example, when viewed from above, the right end of the joint JC is aligned with the right end of the overlapping portion OL or is located to the left of the right end of the overlapping portion OL. When viewed from above, if the joint JC is located to the left of the imaginary center line CL, the joint JC can be shifted to the left from the imaginary center line CL as long as the left end of the joint JC is not located to the left of the left end of the overlapping portion OL. That is, in this example, when viewed from above, the left end of the joint JC is aligned with the left end of the overlapping portion OL or is located to the right of the left end of the overlapping portion OL.

[0028] The tip portion of the positive electrode tab 112 and the tip portion of the negative electrode tab 114 will be described with reference to FIG.

[0029] As shown in FIG. 3, the joint JC is formed by wobbling welding. In the example shown in FIG. 3, the joint JC is formed by moving the laser in a direction substantially parallel to the Z direction, as viewed from the front, while superimposing a substantially circular or substantially elliptical resonant motion. However, the shape of the wobbling welding of the joint JC is not limited to this example. When the joint JC is formed by wobbling welding, the reliability of the joint between the tip end of the positive electrode tab 112 and the tip end of the negative electrode tab 114 can be improved compared to when the joint JC has a linear shape extending substantially parallel to the Z direction, as viewed from the front. However, the joint JC may also have a linear shape extending substantially parallel to the Z direction, as viewed from the front.

[0030] The tip portion of the positive electrode tab 112 and the tip portion of the negative electrode tab 114 will be described with reference to FIG.

[0031] 4, a laser is irradiated from the positive electrode tab 112 toward the negative electrode tab 114 to form the joint JC. The joint JC is formed by melting during laser welding. It is preferable that an intermetallic compound between the components contained in the positive electrode tab 112 and the components contained in the negative electrode tab 114 is not formed at the interface between the positive electrode tab 112 and the negative electrode tab 114 at the joint JC and in the vicinity thereof.

[0032] FIG. 5 is a diagram for explaining the joint JC according to the embodiment and another joint JC'.

[0033] In the example shown in FIG. 5, similar to the example shown in FIG. 2, the joint JC is positioned to the right of the imaginary center line CL shown in FIG. 2 when viewed from above. There are various reasons why it may be necessary to increase the joint strength between the positive electrode tab 112 and the negative electrode tab 114. In this case, it is necessary to rejoin the tip end of the positive electrode tab 112 and the tip end of the negative electrode tab 114. In the example shown in FIG. 5, another joint JC' is formed to rejoin the tip end of the positive electrode tab 112 and the tip end of the negative electrode tab 114. When viewed from above, the other joint JC' is positioned to the left of the joint JC. In other words, the other joint JC' is located on the opposite side of the direction of deviation from the imaginary center line CL of the joint JC when viewed from above.

[0034] In the example shown in FIG. 5 , the joint JC and the other joint JC′ are relatively close to each other in the Y direction. The joint JC and the other joint JC′ can be close to each other, for example, as long as neither of the joint JC nor the other joint JC′ overlaps at the interface between the positive electrode tab 112 and the negative electrode tab 114. That is, as long as neither of the joint JC nor the other joint JC′ overlaps at the interface between the positive electrode tab 112 and the negative electrode tab 114, the joint JC and the other joint JC′ may partially overlap in a region other than the interface between the positive electrode tab 112 and the negative electrode tab 114. In the example shown in FIG. 5 , in the positive electrode tab 112 located furthest to the rear, the left end portion of the joint JC and the right end portion of the other joint JC′ overlap each other. On the other hand, in the example shown in FIG. 5 , none of the joint JC nor the other joint JC′ overlap each other at the interface between the positive electrode tab 112 and the negative electrode tab 114. Therefore, it is possible to suppress the generation of intermetallic compounds at the interface between the positive electrode tab 112 and the negative electrode tab 114 at the joint JC and the other joint JC' and in the vicinity thereof.

[0035] 5, two joints, a joint JC and another joint JC', are provided in the overlapping portion OL. However, the number of joints provided in the overlapping portion OL is not limited to two and may be three or more. Furthermore, one of the multiple joints may be located at the center of the overlapping portion OL in the Y direction.

[0036] 6 is a top view of a front portion of a battery module 10A according to a modified example. The battery module 10A according to the modified example is similar to the battery module 10 according to the embodiment, except for the following points.

[0037] In the example shown in Fig. 6, a single battery cell 100 and another single battery cell 100 are connected in series. Specifically, a positive electrode tab 112 extends forward from the battery cell 100 on the right side shown in Fig. 6. A negative electrode tab 114 extends forward from the battery cell 100 on the left side shown in Fig. 6. When viewed from above, the tip of the positive electrode tab 112 shown in Fig. 6 is bent toward the left. When viewed from above, the tip of the negative electrode tab 114 shown in Fig. 6 is bent toward the left.

[0038] The tip end of the positive electrode tab 112 shown in FIG. 6 and the tip end of the negative electrode tab 114 shown in FIG. 6 have an overlapping portion OL and a joint JC. At the overlapping portion OL, the tip end of the positive electrode tab 112 and the tip end of the negative electrode tab 114 overlap in the X direction. The joint JC is located at the overlapping portion OL. At the joint JC, the tip end of the positive electrode tab 112 and the tip end of the negative electrode tab 114 are joined to each other.

[0039] When viewed from above, the joint JC is positioned to the right of the imaginary center line CL. Therefore, as in the embodiment, it is easier to form other joints to the left of the joint JC compared to when the joint JC is located at the center of the overlapping portion OL when viewed from above. Therefore, in the modified example, the productivity of the battery module 10A can be improved, as in the embodiment. Note that, when viewed from above, the joint JC may be positioned to the left of the imaginary center line CL.

[0040] Although the embodiments and modifications 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]

[0041] 10,10A battery module 100 battery cells 100G parallel cell group 102 Exterior materials 110 Tabs 112 Positive electrode tab 114 Negative electrode tab CL Virtual center line JC junction JC´ other joints OL overlapping part

Claims

1. forming a joint by wobbling welding at least one positive electrode tab of a battery cell and at least one negative electrode tab of another battery cell to join the at least one positive electrode tab and the at least one negative electrode tab; forming another joint in the at least one positive electrode tab and the at least one negative electrode tab by wobbling welding to rejoin the at least one positive electrode tab and the at least one negative electrode tab; A manufacturing method of a battery module comprising:

2. The method for manufacturing a battery module according to claim 1 , wherein at an interface between the at least one positive electrode tab and the at least one negative electrode tab, any portion of the joint portion and any portion of the other joint portion do not overlap each other.

3. The method for manufacturing a battery module according to claim 2 , wherein the joint portion and the other joint portion are brought into close proximity at an interface between the at least one positive electrode tab and the at least one negative electrode tab.

4. 4. The method for manufacturing a battery module according to claim 1, wherein a portion of the joint portion and a portion of the other joint portion overlap each other in a region different from an interface between the at least one positive electrode tab and the at least one negative electrode tab.

5. forming a joint by wobbling welding at least one positive electrode tab of a battery cell and at least one negative electrode tab of another battery cell to join the at least one positive electrode tab and the at least one negative electrode tab; a step of forming another joint portion in the at least one positive electrode tab and the at least one negative electrode tab by wobbling welding to rejoin the at least one positive electrode tab and the at least one negative electrode tab when it is desired to increase the joint strength between the at least one positive electrode tab and the at least one negative electrode tab; A manufacturing method of a battery module comprising:

6. 6. The method for manufacturing a battery module according to claim 5, wherein when the other joint portion is formed, any portion of the joint portion and the other joint portion do not overlap each other at an interface between the at least one positive electrode tab and the at least one negative electrode tab.

7. The method for manufacturing a battery module according to claim 6 , wherein the joint portion and the other joint portion are brought into close proximity at an interface between the at least one positive electrode tab and the at least one negative electrode tab.

8. 8. The method for manufacturing a battery module according to claim 5, wherein, when the other joint portion is formed, the joint portion and the other joint portion are partially overlapped with each other in a region different from an interface between the at least one positive electrode tab and the at least one negative electrode tab.

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