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 Art]

[0002] In recent years, various battery modules including a plurality of battery cells have been developed. Each battery cell includes a battery element, an exterior member that seals the battery element, and a positive electrode tab and a negative electrode tab drawn out from the exterior member.

[0003] Patent Document 1 describes an example of a battery module. In this battery module, positive electrode tabs of a single battery cell or a plurality of battery cells connected in parallel are joined to negative electrode tabs of a single other battery cell or a plurality of other battery cells connected in parallel by laser welding. [Prior Art Literature] [Patent Literature]

[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, a positive electrode tab of at least one battery cell may be joined to a 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 of the region where the joined portion of 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 a battery module. Other objects of the present invention will become apparent from the description of the present specification. [Means for Solving the Problem]

[0007] One aspect of the present invention is as follows: [1] At least one positive tab, A negative electrode tab having an overlapping portion that overlaps with the at least one positive electrode tab, and a joint portion located in the overlapping portion and joined to the at least one positive electrode tab, Equipped with, A battery module in which the aforementioned joint portion is positioned offset from the center of the overlapping portion. [2] The battery module according to [1], wherein the joint is 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 other joints positioned offset from the joint. [4] At least one positive tab and A negative electrode tab having an overlapping portion that overlaps with the at least one positive electrode tab, and a plurality of joining portions located in the overlapping portion, joined to the at least one positive electrode tab, and staggered from each other, A battery module equipped with the following features. [5] The battery module according to [4], wherein none of the portions of the plurality of junctions overlap each other at the interface between the at least one positive electrode tab and the at least one negative electrode tab. [6] The battery module according to [5], wherein at least a portion of the plurality of junctions overlap 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-described embodiment of the present invention, the productivity of battery modules can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a battery module according to an embodiment. [Figure 2] This is a top view of the front portion of a part of a battery module according to the embodiment. [Figure 3] This is a front view of the tip of the positive electrode tab and the tip of the negative electrode tab according to the embodiment. [Figure 4] This is a cross-sectional view AA' in Figure 3. [Figure 5] This is a diagram illustrating the joint and other joints according to the embodiment. [Figure 6] This is a top view of the front portion of a part of the battery module involved in the modification. [Modes for carrying out the invention]

[0010] Embodiments and modified examples of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

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

[0012] In each drawing, for the purpose of description, arrows indicating the X direction, Y direction, and Z direction are shown. The X direction indicates the front-rear direction of the battery module 10. Hereinafter, unless otherwise specified, the tip end side of the arrow indicating the X direction is defined as the rear side of the battery module 10. Hereinafter, unless otherwise specified, the base end side of the arrow indicating the X direction is defined as the front side of the battery module 10. The Y direction is orthogonal to the X direction. The Y direction indicates the left-right direction of the battery module 10. Hereinafter, unless otherwise specified, the tip end side of the arrow indicating the Y direction is defined as the left side of the battery module 10. Hereinafter, unless otherwise specified, the base end side of the arrow indicating the Y direction is defined as the right side of the battery module 10. The Z direction is orthogonal to both the X direction and the Y direction. The Z direction indicates the up-down direction of the battery module 10. Hereinafter, unless otherwise specified, the tip end side of the arrow indicating the Z direction is defined as the upper side of the battery module 10. Hereinafter, unless otherwise specified, the base end side of the arrow indicating the Z direction is defined as the lower side of the battery module 10. However, the relationship between the X, Y, and Z directions and the front-rear, left-right, and up-down directions of the battery module 10 is not limited to the above-described example. These relationships vary depending on the actual arrangement of the battery module 10.

[0013] The battery module 10 will be described with reference to FIG. 1.

[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 has a plurality of battery cells 100 connected in parallel. In the example shown in FIG. 1, each parallel cell group 100G has two battery cells 100 connected in parallel. However, each parallel cell group 100G may have 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 substantially parallel to the X direction. The lateral direction of each battery cell 100 is substantially parallel to the Z direction. The thickness direction of each battery cell 100 is substantially 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 member 102 seals battery elements and an electrolytic solution which are not shown in the drawings. The battery elements include, for example, a plurality of positive electrodes and a plurality of negative electrodes that are alternately stacked in the Y direction, and separators positioned between the positive electrodes and the negative electrodes adjacent in the Y direction. However, the structure of the battery elements is not limited to this example.

[0016] The positive electrode tab 112 and the negative electrode tab 114 are led out from mutually opposite sides of the exterior member 102 in the X direction. In the region sealed by the exterior member 102, the positive electrode tab 112 is electrically connected to the aforementioned positive electrodes. The positive electrode tab 112 is made of, for example, aluminum. The negative electrode tab 114 is made of, for example, copper. In the region sealed by the exterior member 102, the negative electrode tab 114 is electrically connected to the aforementioned negative electrodes.

[0017] In the example shown in FIG. 1, a plurality of parallel cell groups 100G are connected in series. Specifically, the plurality of positive electrode tabs 112 led out from the plurality of battery cells 100 included in each parallel cell group 100G are oriented toward the same side in the X direction. Similarly, the plurality of negative electrode tabs 114 led out from the plurality of battery cells 100 included in each parallel cell group 100G are oriented toward the same side in the X direction. The plurality of positive electrode tabs 112 and the plurality of negative electrode tabs 114 led out from one of the parallel cell groups 100G adjacent in the Y direction, and the plurality of positive electrode tabs 112 and the plurality of negative electrode tabs 114 led out from the other of the parallel cell groups 100G adjacent in the Y direction, are oriented toward mutually opposite sides in the X direction. Parallel cell groups 100G adjacent in the Y direction have a tab group 110. The tab group 110 is positioned in front of or behind the parallel cell groups 100G adjacent in the Y direction. The tab group 110 includes the plurality of positive electrode tabs 112 led out from one of the parallel cell groups 100G adjacent in the Y direction, and the plurality of negative electrode tabs 114 led out 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] Multiple tab groups 110 located in front of the battery module 10 and multiple tab groups 110 located behind the battery module 10 are arranged alternately in the Y direction. For example, in the example shown in Figure 1, the leftmost parallel cell group 100G and the second parallel cell group 100G from the left have tab groups 110 located in front of these parallel cell groups 100G. Also, the second parallel cell group 100G from the left and the third parallel cell group 100G from the left have tab groups 110 located behind these parallel cell groups 100G.

[0019] Figure 2 is a top view of the front portion of a part of the battery module 10 according to the embodiment. Figure 3 is a front view of the tip of the positive electrode tab 112 and the tip of the negative electrode tab 114 according to the embodiment. Figure 4 is a cross-sectional view AA' of Figure 3. In Figures 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 of the page towards the front, and the lower side of the battery module 10 from the front of the page towards the back. In Figure 3, the white circle with an X indicating the X direction indicates the rear side of the battery module 10 from the front of the page towards the back, and the front side of the battery module 10 from the back of the page towards the front.

[0020] Referring to Figure 2, the tip of the positive electrode tab 112 and the tip of the negative electrode tab 114 will be described.

[0021] Figure 2 illustrates two adjacent parallel cell groups 100G in the Y direction. Two positive electrode tabs 112 extend forward from the two battery cells 100 included in the right-hand parallel cell group 100G. Viewed from above, the tips of these two positive electrode tabs 112 are bent to the left. Two negative electrode tabs 114 extend forward from the two battery cells 100 included in the left-hand parallel cell group 100G. Viewed from above, the tips of these two negative electrode tabs 114 are bent to the right.

[0022] The tips of the two positive electrode tabs 112 and the tips of the two negative electrode tabs 114 shown in Figure 2 have an overlapping portion OL. In the overlapping portion OL, the tips of the two positive electrode tabs 112 and the tips of the two negative electrode tabs 114 overlap in the X direction. In the example shown in Figure 2, the tips of the negative electrode tabs 114 are located in front of the tips of the positive electrode tabs 112. However, the tips of the positive electrode tabs 112 may also be located in front of the tips of the negative electrode tabs 114.

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

[0024] Figure 2 illustrates a virtual center line CL. Viewed from above, the virtual center line CL passes through the center of the overlapping section OL in the Y direction, parallel to the X direction. In the example shown in Figure 2, viewed from above, the joint JC is positioned offset to the right of the virtual center line CL. To increase the bonding strength of the positive electrode tab 112 and the negative electrode tab 114, another joint may be formed in the overlapping section OL offset in the Y direction from the joint JC. In the example shown in Figure 2, viewed from above, this other joint can be formed in the left portion of the overlapping section OL from the joint JC. In the example shown in Figure 2, the left side of the joint JC is opposite to the direction of offset from the virtual center line CL of the joint JC when viewed from above. Therefore, in the example shown in Figure 2, the width in the Y direction of the portion of the overlapping section OL where this other joint is formed can be increased compared to the case where the joint JC is located at the center of the overlapping section OL in the Y direction. For this reason, in this embodiment, the robustness of the area of ​​the portion of the overlapping section OL where this other joint is formed can be improved. Therefore, in this embodiment, the productivity of the battery module 10 can be improved.

[0025] Furthermore, when viewed from above, the joint JC may be positioned offset to the left of the virtual centerline CL. In this case as well, as described above, the width in the Y direction of the portion of the overlapping portion OL where the other joints are formed can be increased compared to the case where the joint JC is located at the center of the overlapping portion OL in the Y direction. Therefore, in this example as well, 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 virtual centerline CL can be, for example, 1 / 4 or more of the Y-direction width of the overlapping portion OL. In this case, the Y-direction width of the portion of the overlapping portion OL where the other joints are formed can be increased compared to when the distance is less than that value. Therefore, it becomes easier to form the other joints 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 virtual centerline CL is not particularly limited, as long as the entire joint JC is located within the overlapping section OL. For example, when viewed from above, if the joint JC is located to the right of the virtual centerline CL, the joint JC can be shifted to the right of the virtual centerline CL, as long as the right end of the joint JC is not located to the right of the right end of the overlapping section OL. That is, in this example, when viewed from above, the right end of the joint JC is either aligned with the right end of the overlapping section OL or located to the left of the right end of the overlapping section OL. When viewed from above, if the joint JC is located to the left of the virtual centerline CL, the joint JC can be shifted to the left of the virtual centerline CL, as long as the left end of the joint JC is not located to the left of the left end of the overlapping section OL. That is, in this example, when viewed from above, the left end of the joint JC is either aligned with the left end of the overlapping section OL or located to the right of the left end of the overlapping section OL.

[0028] Referring to Figure 3, the tip of the positive electrode tab 112 and the tip of the negative electrode tab 114 will be described.

[0029] As shown in Figure 3, the joint JC is formed by wobbling welding. In the example shown in Figure 3, the joint JC is formed by moving the laser in a direction substantially parallel to the Z direction, superimposed with a substantially circular or substantially elliptical resonant motion, when viewed from the front. However, the shape of the wobbling weld of the joint JC is not limited to this example. When the joint JC is formed by wobbling welding, the reliability of the joint at the tip of the positive electrode tab 112 and the tip of the negative electrode tab 114 can be improved compared to when the joint JC is simply a linear shape extending substantially parallel to the Z direction when viewed from the front. However, when viewed from the front, the joint JC may simply be a linear shape extending substantially parallel to the Z direction.

[0030] Referring to Figure 4, the tip of the positive electrode tab 112 and the tip of the negative electrode tab 114 will be described.

[0031] In the example shown in Figure 4, a laser is irradiated from the positive electrode tab 112 toward the negative electrode tab 114 to form a joint JC. The joint JC is formed by laser melting. It is preferable that no intermetallic compounds are formed at the interface between the positive electrode tab 112 and the negative electrode tab 114 and the vicinity thereof in the joint JC, between the components contained in the positive electrode tab 112 and the components contained in the negative electrode tab 114.

[0032] Figure 5 is a diagram illustrating the joint JC and other joints JC' according to the embodiment.

[0033] In the example shown in Figure 5, similar to the example shown in Figure 2, when viewed from above, the joint JC is positioned to the right of the virtual center line CL shown in Figure 2. There are times when it is desirable to increase the bonding strength of the positive electrode tab 112 and the negative electrode tab 114 due to various factors. In this case, it is necessary to re-bond the tips of the positive electrode tab 112 and the negative electrode tab 114. In the example shown in Figure 5, the tips of the positive electrode tab 112 and the negative electrode tab 114 are re-bonded by forming another joint JC'. When viewed from above, the other joint JC' is positioned to the left of joint JC. That is, when viewed from above, the other joint JC' is located on the opposite side of the direction of displacement from the virtual center line CL of joint JC.

[0034] In the example shown in Figure 5, joint JC and the other joint JC' are relatively close in the Y direction. Joint JC and the other joint JC' can be placed close together, for example, as long as neither part of 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 part of joint JC nor the other joint JC' overlaps at the interface between the positive electrode tab 112 and the negative electrode tab 114, parts of joint JC and the other joint JC' may overlap in a region different from the interface between the positive electrode tab 112 and the negative electrode tab 114. In the example shown in Figure 5, at the rearmost positive electrode tab 112, the left end of joint JC and the right end of the other joint JC' overlap each other. On the other hand, in the example shown in Figure 5, neither part of joint JC nor the other joint JC' overlaps each other at the interface between the positive electrode tab 112 and the negative electrode tab 114. Therefore, the formation of intermetallic compounds at the interface between the positive electrode tab 112 and the negative electrode tab 114 of joint JC and other joint JC', and in the vicinity thereof, can be suppressed.

[0035] In the example shown in Figure 5, the overlapping section OL has two joints: joint JC and another joint JC'. However, the number of joints provided in the overlapping section OL is not limited to two; there may be three or more. Furthermore, one of the multiple joints may be located at the center of the overlapping section OL in the Y direction.

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

[0037] In the example shown in Figure 6, one battery cell 100 is connected in series with another single battery cell 100. Specifically, the positive electrode tab 112 is extended forward from the right-hand battery cell 100 shown in Figure 6. The negative electrode tab 114 is extended forward from the left-hand battery cell 100 shown in Figure 6. Viewed from above, the tip of the positive electrode tab 112 shown in Figure 6 is bent to the left. Viewed from above, the tip of the negative electrode tab 114 shown in Figure 6 is bent to the left.

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

[0039] Viewed from above, the joint JC is positioned offset to the right of the virtual center line CL. Therefore, compared to the case where the joint JC is located at the center of the overlap OL when viewed from above, as in the embodiment, it is easier to form other joints to the left of joint JC. Therefore, in the modified example as well, 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 offset to the left of the virtual center line CL.

[0040] The embodiments and modifications of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted. [Explanation of symbols]

[0041] 10,10A Battery Module 100 battery cells 100G parallel cell group 102 Exterior materials 110 tab groups 112 Positive Tab 114 Negative Electrode Tab CL virtual centerline JC junction JC' Other joints Office Lady overlapping section

Claims

1. A step of joining the at least one positive electrode tab and the at least one negative electrode tab by wobbling welding to at least one positive electrode tab of a battery cell included in a plurality of battery cells stacked in a predetermined stacking direction and at least one negative electrode tab of another battery cell included in the plurality of battery cells, at a position offset from the center in the direction parallel to the stacking direction of the overlapping portion of the at least one positive electrode tab and the at least one negative electrode tab, A step of rejoining the at least one positive electrode tab and the at least one negative electrode tab by wobbling welding to form another joint at a position offset from the joint in a direction parallel to the stacking direction, A method for manufacturing a battery module, comprising:

2. A method for manufacturing a battery module according to claim 1, wherein at the interface between the at least one positive electrode tab and the at least one negative electrode tab, neither portion of the joint nor the other joint overlaps with the other.

3. A method for manufacturing a battery module according to claim 1 or 2, wherein the joint and a portion of the other joints are overlapped in a region different from the interface of the at least one positive electrode tab and the at least one negative electrode tab.

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