Battery module

Abstract

The utility model relates to a battery module, which is provided with a plurality of battery units stacked with one another, an electrode lead protruding from the battery cell; a bus bar having an overlapping portion overlapping an end portion of the electrode lead, the bus bar being electrically bonded to the electrode lead at the overlapping portion by a welding portion; and a heat input part formed at a position overlapping the welding part on at least one of the electrode lead and the bus bar, the heat input property of the heat input part in the bonding direction being higher than that of other parts. According to the battery module disclosed by the utility model, the bonding strength during welding can be stable at the welding parts of the bonding buses and the electrode leads.

Description

Technical Field

[0001] The utility model relates to a battery module. Background Art

[0002] A battery module is known in which a plurality of battery cells are stacked one on another to form a battery group. In such a battery module, electrode leads extending from the plurality of battery cells are electrically connected to bus bars.

[0003] In addition, in electric power equipment, as a method of electrically connecting an electrode lead and a bus bar, a joining method by welding is known (for example, Patent Document 1).

[0004] Patent Document 1: Japanese Patent No. 03313062

[0005] In a battery module formed by stacking a plurality of battery cells, as described above, the electrode leads extending from the plurality of battery cells are electrically connected to the bus bar. Therefore, stress may be generated at the weld between the electrode lead and the bus bar due to the expansion of the battery cells when the battery module expands. In order to prevent the electrode lead from being separated from the bus bar, it is desirable to stabilize the joint strength during welding. Utility Model Content

[0006] The present invention takes the above-mentioned facts into consideration, and an object of the present invention is to obtain a battery module capable of stabilizing the joint strength during welding at a welding portion where a bus bar and an electrode lead are joined.

[0007] A battery module of the first type comprises: a plurality of battery cells stacked on each other; electrode leads protruding from the battery cells; a bus bar having an overlapping portion overlapping with an end portion of the electrode lead, the bus bar being electrically joined to the electrode lead via a welding portion at the overlapping portion; and a heat input portion formed at a position overlapping with the welding portion on at least one of the electrode lead and the bus bar, the heat input property of the heat input portion in the joining direction being higher than that of other portions.

[0008] In the battery module of the first embodiment, there are a plurality of battery cells stacked on each other. In addition, the electrode leads protruding from each battery cell are electrically joined to the busbar via a welding portion. Here, in the first embodiment, a heat input portion is formed on at least one of the electrode lead and the busbar at a position overlapping with the welding portion. In the heat input portion, the heat input of the welding portion in the joining direction is higher than that of other portions. Thus, when the electrode leads extending from a plurality of battery cells are welded to the busbar by laser welding or the like, the heat input to the base material can be increased, thereby stabilizing the joining strength of the welding portion.

[0009] A battery module according to a second aspect is the battery module according to the first aspect, wherein the heat input portion is formed of a thin-walled portion having a plate thickness thinner than other portions.

[0010] In the battery module of the second embodiment, by forming a thin-walled portion having a plate thickness thinner than other portions at a position overlapping with the weld portion, a heat input portion of the weld portion having a higher heat input in the joining direction than other portions can be formed. Thus, when welding electrode leads extending from a plurality of battery cells to a bus bar by laser welding or the like, heat input to the base material can be increased, and the joining strength of the weld portion can be stabilized.

[0011] A battery module of a third embodiment is that in the second embodiment, the thin-walled portion constitutes a groove portion extending linearly on at least one of the electrode lead and the bus bar; and a plurality of welding portions are formed along the groove portion in a point-like manner when viewed from the joining direction.

[0012] In the battery module of the third type, the thin-walled portion constituting the heat input portion forms a groove portion extending linearly on at least one of the electrode lead and the busbar. In addition, along the groove portion extending linearly, a plurality of welds are formed in a point-shaped manner when viewed from the joining direction. In this way, the thin-walled portion formed by the linear groove portion can correspond to a plurality of welds when the electrode lead is joined to the busbar by a point-shaped weld portion formed by laser welding or the like. As a result, the joining strength of the plurality of welds can be stabilized by easy processing, thereby improving productivity.

[0013] A battery module according to a fourth aspect is the battery module according to the third aspect, wherein the groove has a V-shaped cross-sectional shape.

[0014] In the battery module of the fourth embodiment, by setting the cross-sectional shape of the groove portion to a V-shape, when the electrode leads extending from the plurality of battery cells are welded to the busbar by laser welding or the like, the penetration of the base material can be deepened toward the center of the weld portion. This can more effectively stabilize the bonding strength of the weld portion.

[0015] A battery module according to a fifth aspect is the battery module according to the third aspect, wherein the groove portion has a concave curved cross-sectional shape.

[0016] In the battery module of the fifth embodiment, by setting the cross-sectional shape of the groove portion to a concave curved surface, when the electrode leads extending from the plurality of battery cells are welded to the busbar by laser welding or the like, the penetration of the base material can be deepened toward the center of the weld portion. In addition, the surface area of ​​the groove portion is further increased, and the heat input can be efficiently improved. As a result, the bonding strength of the weld portion can be more effectively stabilized.

[0017] As described above, in the battery module of the present invention, it is possible to stabilize the joining strength during welding at the welded portion where the bus bar and the electrode lead are joined. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a schematic plan view showing a main part of a vehicle to which the battery pack according to the embodiment is applied.

[0019] Figure 2 It is a three-dimensional schematic diagram of a battery module involved in the embodiment.

[0020] Figure 3 FIG. 1 is a top view of a battery module according to an embodiment, in a state where an upper cover of a module case is removed.

[0021] Figure 4 A schematic diagram showing a battery cell housed in a battery module as viewed from the thickness direction.

[0022] Figure 5 The diagram is a partially enlarged top view of a state where a plurality of battery cells are accommodated in a module case.

[0023] Fig. 6A and Figure 6B This is an enlarged view of the welded portion where the electrode lead and the busbar are joined. Fig. 6A For Figure 5 The main view of the A direction, Figure 6B To indicate the Fig. 6A An enlarged cross-sectional view of the cross section taken along line BB.

[0024] Fig. 7A , Figure 7B , Figure 7C , Fig.7D and Fig. 7E An example of a heat input portion formed in a weld is shown. Figure 6B The corresponding enlarged cross section. DETAILED DESCRIPTION

[0025] The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0026] First, the overall structure of vehicle 100 will be described.

[0027] Figure 1 1 is a schematic plan view showing the main parts of a vehicle 100 to which the battery pack 10 according to the embodiment is applied. Figure 1 As shown, the vehicle 100 is an electric vehicle (BEV) equipped with a battery pack 10 under the floor. In addition, the arrows UP, FR, and LH in each figure respectively indicate the upper side in the vehicle vertical direction, the front side in the vehicle front-back direction, and the left side in the vehicle width direction. When the front-back, left-right, up-down directions are used for explanation, unless otherwise specified, they indicate the front-back in the vehicle front-back direction, the left-right in the vehicle width direction, and the up-down in the vehicle vertical direction.

[0028] As an example, the vehicle 100 of this embodiment has a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 disposed on the vehicle front side relative to the battery pack 10. In addition, a motor 108, a gear box 110, an inverter 112, and a vehicle charger 114 are disposed on the vehicle rear side relative to the battery pack 10.

[0029] The DC current output from battery pack 10 is supplied to electric compressor 104, PTC heater 106, inverter 112, etc. after the voltage is adjusted by DC / DC converter 102. In addition, by supplying power to motor 108 via inverter 112, the rear wheels rotate and vehicle 100 travels.

[0030] A charging port 116 is provided on the right side of the rear portion of the vehicle 100 . By connecting a charging plug of an external charging device (not shown) to the charging port 116 , electricity can be stored in the battery pack 10 via the on-vehicle charger 114 .

[0031] In addition, the configuration and structure of each component constituting the vehicle 100 are not limited to the above-mentioned configuration. For example, it can also be applied to a hybrid vehicle (HV: Hybrid Vehicle) or a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle) equipped with an engine. In addition, in the present embodiment, the motor 108 is mounted on the rear of the vehicle. However, it is not limited to this. It can also be a front-wheel drive vehicle with the motor 108 mounted on the front of the vehicle, or it can be a pair of motors 108 mounted on the front and rear of the vehicle. In addition, it can also be a vehicle with an in-wheel motor on each wheel.

[0032] Here, the battery pack 10 is configured to include a plurality of battery modules 11. In the present embodiment, as an example, 10 battery modules 11 are provided. Specifically, five battery modules 11 are arranged in the vehicle front-rear direction on the right side of the vehicle 100, and five battery modules 11 are arranged in the vehicle front-rear direction on the left side of the vehicle 100. In addition, each battery module 11 is electrically connected.

[0033] Figure 2 FIG. 1 is a three-dimensional schematic diagram of a battery module 11. Figure 2 As shown, the battery module 11 has a module housing 16 constituting an outer shell. The module housing 16 is formed into a substantially rectangular parallelepiped shape with the vehicle width direction as the long side direction. In addition, the module housing 16 is formed of an aluminum alloy. For example, the module housing 16 is formed by joining aluminum die castings at both ends of an aluminum alloy extrusion by laser welding or the like.

[0034] A pair of voltage terminals 12 and a connector 14 are provided at both ends of the battery module 11 in the vehicle width direction. The connector 14 is connected to a flexible printed circuit board 21 described later. In addition, bus bars 30 (see FIG. 1 ) are welded to both ends of the battery module 11 in the vehicle width direction. Figure 4 ).

[0035] The battery module 11 has a length MW in the vehicle width direction of, for example, 350 to 600 mm, a length ML in the vehicle front-rear direction of, for example, 150 to 250 mm, and a height MH in the vehicle vertical direction of, for example, 80 to 110 mm.

[0036] Figure 3 FIG. 1 is a top view of the battery module 11 with the upper cover removed. Figure 3 As shown, a battery cell 20 as a battery is housed inside the module case 16. As an example, a plurality of battery cells 20 are housed in an aligned (stacked) state inside the module case 16. In this embodiment, 24 battery cells 20 are aligned in the vehicle front-rear direction and bonded to each other.

[0037] In order to make the explanation easier to understand, Figures 3 to 6B In each of the figures, the direction indicated by the arrow W is set as the width direction of the battery cell 20, the direction indicated by the arrow H is set as the height direction (up and down direction) of the battery cell 20, and the direction indicated by the arrow D is set as the thickness direction of the battery cell 20.

[0038] The width direction of the battery case 22 described below coincides with the width direction W of the battery cell 20 . The height direction of the battery case 22 coincides with the height direction H of the battery cell 20 . The thickness direction of the battery case 22 coincides with the thickness direction D of the battery cell 20 .

[0039] A flexible printed circuit (FPC) 21 is disposed on the battery cell 20. The flexible printed circuit 21 is formed in a strip shape with the vehicle width direction as the long side direction, and thermistors 23 are provided at both ends of the flexible printed circuit 21. The thermistor 23 is not bonded to the battery cell 20, but is pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0040] In addition, one or more buffer materials (not shown) are accommodated inside the module case 16. For example, the buffer material is a thin plate-shaped member that can be elastically deformed, and is arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, the buffer material is arranged at both ends and the center of the module case 16 in the long side direction.

[0041] Figure 4Schematic diagram of the battery cell 20 contained in the battery module 11 as viewed from the thickness direction D. Figure 4 As shown, the battery cell 20 is formed into a long rectangular plate with the width direction W as the long side direction, and has a battery case 22 constituting an outer shell. An electrode body 40 is accommodated inside the battery case 22. The electrode body 40 is composed of a positive electrode as an electrode, a negative electrode as an electrode, and a separator stacked. In this embodiment, the battery case 22 is composed of a composite film, and the electrode body 40 is sealed by the composite film.

[0042] The battery case 22 is embossed on at least one side in the thickness direction of the battery case 22. By implementing the embossing, a concave receiving portion 221 for internally receiving the electrode body 40 and an outer end portion 223 provided on the outer side of the receiving portion 221 are formed on the side. In addition, the battery case 22 can adopt both a single cup embossing structure with 1 embossing location and a double cup embossing structure with 2 embossing locations. In the present embodiment, the single cup embossing structure is a drawing depth of about 8 to 10 mm. Therefore, the first side portion 22A on one side in the thickness direction of the battery case 22 is an embossed surface that forms a receiving space inside the battery cell 20. In addition, the second side portion 22B on the other side in the thickness direction of the battery case 22 (refer to Figure 5 ) is a flat non-embossed surface that has not been embossed.

[0043] The upper end of the battery case 22 in the height direction is bent and the corners are chamfered to form a substantially trapezoidal shape. The upper end of the battery case 22 is also bent and a fixing band 24 is wound around the upper end of the battery case 22 in the width direction.

[0044] Here, the battery cell 20 has an electrode lead 26 protruding from the end of the battery case 22. The electrode lead 26 is respectively provided at both ends of the battery cell in the width direction. In the present embodiment, as an example, the electrode lead 26 is provided at a position offset downward from the center of the height direction H of the battery cell 20. One end of the electrode lead 26 is connected to the electrode body 40 inside the battery case 22. The other end of the electrode lead 26 protrudes from the end of the battery case 22 in the width direction and is connected to the electrode body 40 via a welding portion 50 (see Figure 5 ) is electrically joined to the bus bar 30. The electrode lead 26 is connected to the external wiring of the battery module 11 via the bus bar 30. The electrode lead 26 and the bus bar 30 can be welded to each other using a known welding method as appropriate. In one example of the present embodiment, the electrode lead 26 and the bus bar 30 are joined to each other by laser welding.

[0045] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530-600 mm, 600-700 mm, 700-800 mm, 800-900 mm, or 1000 mm or more, the length CW2 of the area accommodating the electrode body is, for example, 500-520 mm, 600-700 mm, 700-800 mm, 800-900 mm, or 1000 mm or more, and the height CH of the battery cell 20 is, for example, 80-110 mm, 110-140 mm. In addition, the thickness of the battery cell 20 is 5.0-7.0 mm, 7.0-9.0 mm, or 9.0-11.0 mm, and the height TH of the electrode lead (terminal) 26 is 40-50 mm, 50-60 mm, or 60-70 mm.

[0046] Figure 5 The schematic diagram of a partially enlarged top view of a state where a plurality of battery cells 20 are accommodated in a module case 16. As shown in the figure, in the module case 16, the other end of the electrode lead 26 protrudes from the end of the plurality of battery cells 20 stacked on each other in the width direction W. In addition, a plate-shaped bus bar 30 is disposed on one side and the other side of the battery cell 20 in the width direction W, respectively.

[0047] in addition, Figure 5 For the sake of convenience, only one battery cell 20 is shown inside the battery case 16 , but in reality, a plurality of stacked battery cells 20 are mutually constrained by being applied with a predetermined constraining pressure along the stacking direction (thickness direction D) via a buffer material or directly connected.

[0048] The bus bar 30 extends along the stacking direction (thickness direction D) of the battery cells 20 with the width direction W of the battery cells 20 as the plate thickness direction. The bus bar 30 has a groove-shaped through hole 32 penetrating the bus bar 30 in the plate thickness direction.

[0049] The other end of the electrode lead 26 protruding from the end of the battery cell 20 in the width direction W is inserted into the through hole 32 of the bus bar 30. The end 261 protruding from the through hole 32 is folded back toward the bus bar 30 and overlapped on the surface of the bus bar 30.

[0050] On the busbar 30 along the extension direction of the busbar 30 (in Figure 5 A plurality of through holes 32 are formed in the thickness direction (D), and the electrode leads 26 protruding from the plurality of battery cells 20 are inserted through these through holes 32 and joined to the bus bar 30. Thus, the plurality of battery cells 20 are electrically connected via the bus bar 30. Figure 5As shown, the electrode lead 26 is inserted into the through hole 32 formed in the bus bar 30. In addition, the end 261 of the electrode lead 26 is folded back toward the bus bar 30. As a result, an overlapping portion 30A where the end 261 of the electrode lead 26 overlaps is formed on the surface of the bus bar 30. The electrode lead 26 is joined to the bus bar 30 via the welding portion 50 at the overlapping portion 30A.

[0051] Fig. 6A For Figure 5 An enlarged front view of the weld portion 50 as viewed in the direction of arrow A. Figure 6B It means along Fig. 6A FIG. 1 is an enlarged cross-sectional view of a cross section of the welding portion 50 cut along line BB.

[0052] like Fig. 6A and Figure 6B As shown, the weld portion 50 is formed at the end portion 261 of the electrode lead 26 at the overlapped portion 30A of the busbar 30 where the end portion 261 of the electrode lead 26 overlaps. In addition, at the end portion 261 of the electrode lead 26, a heat input portion 60 is formed at a position overlapping with the weld portion 50 on the surface constituting the processed surface of the weld portion 50. The heat input portion 60 is a region of the end portion 261 of the electrode lead 26 to which surface processing is performed in order to improve heat input compared to other portions.

[0053] The “heat input property” referred to here refers to the ease with which heat (heat input) can be transferred to the weld portion (base material) during welding.

[0054] In this embodiment, the surface of the end portion 261 of the electrode lead 26 is Fig. 6A A heat input portion 60 is formed in a linear region extending in the height direction H).

[0055] The welded portion 50 can be formed, for example, by laser welding or arc welding. In one example of the present embodiment, the welded portion 50 is formed by spot welding using a laser. Therefore, the welded portion 50 is formed in a circular spot shape when viewed from the joining direction (the plate thickness direction of the busbar 30). When the electrode lead 26 and the busbar 30 are joined, a plurality of welded portions 50 are formed along the heat input portion 60 formed in the linear region.

[0056] When the heat input property of the weld portion 50 is improved by the heat input portion 60 , the base material of the weld portion 50 melts deeper, and the joining between the electrode lead 26 and the bus bar 30 can be stabilized.

[0057] Reference Figure 7A to Figure 7EHere, examples of the heat input portion 60 are described. Here, a plurality of examples of forming the heat input portion 60 by processing the surface of the electrode lead 26 are described, but a structure in which each heat input portion 60 is provided on the bus bar 30 may be adopted, and a structure in which both the electrode lead 26 and the bus bar 30 are provided may be adopted.

[0058] In addition, each figure shows a state before the welded portion 50 is formed on the electrode lead 26 and the bus bar 30 as base materials, and the welding range is indicated by a region P surrounded by a two-dot chain line.

[0059] exist FIG. 7A to FIG. 7D In the illustrated example, the heat input portion 60 is structured so as to improve heat input performance by performing surface processing to increase the surface area of ​​the processed surface of the weld portion 50 .

[0060] Fig. 7A The first heat input portion 60A shown is formed by forming a linear groove portion 61 extending in the width direction of the electrode lead 26 at the end portion 261 of the electrode lead 26. The groove portion 61 increases the surface area of ​​the processed surface of the weld portion 50, and the heat input property is improved. In addition, the groove portion 61 forms a thin-walled portion with a plate thickness thinner than other portions. In this regard, the heat input property is also improved.

[0061] The cross-sectional shape of the groove portion 61 constituting the first heat input portion 60A is V-shaped. Therefore, the plate thickness of the end portion 261 of the electrode lead 26 becomes thinner toward the center side of the welding range P. As a result, the heat input property of the center side of the welding portion 50 is higher than that of the outer peripheral side, and the penetration of the base material becomes deeper on the center side. As a result, the bonding strength can be effectively improved.

[0062] Figure 7B The second heat input portion 60B shown is formed by forming a linear groove portion 62 at the end portion 261 of the electrode lead 26. The groove portion 62 increases the surface area of ​​the processed surface of the weld portion 50, and the heat input performance is improved. In addition, the groove portion 61 forms a thin-walled portion with a plate thickness thinner than other portions. In this regard, the heat input performance is also improved.

[0063] The cross-sectional shape of the groove portion 62 constituting the second heat input portion 60B is a concave curved surface. In other words, the cross-sectional shape of the groove portion 62 can also be called a U-shape. Therefore, the point that the plate thickness of the end portion 261 of the electrode lead 26 becomes thinner toward the center side of the welding range P is the same as the first heat input portion 60A. As a result, the heat input property on the center side of the weld 50 is higher than that on the peripheral side, and the penetration of the base material on the center side becomes deeper. As a result, the joining strength can be effectively improved. In addition, by making the cross-sectional shape of the groove portion 62 a concave curved surface, the surface area is increased compared to the V-shaped cross section, so that even on the peripheral side of the weld 50, the penetration depth of the base material can be deepened.

[0064] Figure 7C The third heat input portion 60C shown makes the surface of the end portion 261 of the electrode lead 26 rougher than other portions, thereby increasing the surface area of ​​the weld portion 50 .

[0065] Fig.7D The fourth heat input portion 60D shown is composed of a through hole 63 provided at the end portion 261 of the electrode lead 26. The diameter of the through hole 63 is set to be smaller than the diameter of the point-shaped weld portion 50. The surface area of ​​the weld portion is increased by utilizing the inner side surface of the through hole 63. As a result, the heat input property in the joining direction of the weld portion 50 is improved compared to other parts. In addition, according to the shape of the through hole 63, the heat input property can be effectively improved toward the center side of the weld portion 50, and the penetration of the base material on the center side of the weld portion 50 becomes deeper. As a result, the joining strength can be effectively improved.

[0066] Fig. 7E The fifth heat input portion 60E is formed by surface processing by coating the surface of the end portion 261 of the electrode lead 26 with a black material 68. The black material 68 absorbs laser light, thereby increasing the heat input of the weld 50 and deepening the penetration of the base material.

[0067] The functions and effects of the implementation method are described below.

[0068] As described above, in the battery module 11 involved in the embodiment, a plurality of battery cells 20 stacked on each other are provided. In addition, the electrode lead 26 protruding from each battery cell 20 is electrically joined to the bus bar 30 via the welding portion 50. Here, in the present embodiment, a heat input portion 60 is formed on the electrode lead 26 at a position overlapping with the welding portion 50. In the heat input portion 60, the heat input property of the welding portion 50 in the joining direction is improved compared to other parts. Thus, when the electrode lead 26 extending from the plurality of battery cells 20 is welded to the bus bar 30 by laser welding or the like, the heat input property to the base material can be improved, and the joining strength of the welding portion can be stabilized. As a result, the stress generated in the welding portion 50 between the electrode lead 26 and the bus bar 30 due to the expansion of the battery cell 20 generated when the battery module 11 expands can be suppressed, so that the electrode lead 26 is detached from the bus bar 30.

[0069] For example, Fig. 7A and Figure 7B As shown, the heat input portion 60 can be formed of a thin-walled portion having a plate thickness thinner than other portions. By forming a thin-walled portion (grooves 61, 62) having a plate thickness thinner than other portions at a position overlapping with the weld portion 50, the heat input property of the weld portion 50 in the joining direction is improved compared to other portions, and the joining strength of the weld portion 50 can be stabilized.

[0070] In addition, if Fig. 7A and Figure 7BAs shown in the figure, when the heat input portion 60 is formed by a thin-walled portion having a thinner plate thickness than other portions, the grooves 61 and 62 extending in a straight line may be formed. Furthermore, a plurality of welds 50 may be formed along the grooves 61 and 62 extending in a straight line so as to be dot-shaped when viewed from the joining direction. In this case, the thin-walled portion formed by the straight-line grooves 61 and 62 can correspond to a plurality of welds 50 when the electrode lead 26 is joined to the bus bar 30 by the dot-shaped welds 50 formed by laser welding or the like. Thus, the joining strength of the plurality of welds 50 can be stabilized by easy processing, thereby improving productivity.

[0071] In addition, if Fig. 7A By making the cross-sectional shape of the groove 61 V-shaped as shown in the figure, the penetration of the base material can be deepened toward the center of the weld 50. This can more effectively stabilize the joining strength of the weld 50.

[0072] In addition, if Figure 7B By making the cross-sectional shape of the groove 62 concave, the surface area can be increased without increasing the groove width except for the point where the base material is melted deeper toward the center of the weld, and the heat input can be efficiently improved. Thus, the bonding strength of the weld 50 can be more effectively stabilized.

[0073] In addition, if Figure 7C As shown, the heat input portion 60 may also be formed by roughening the surface of the electrode lead at a position overlapping with the weld portion 50. By roughening the surface of the electrode lead 26, the surface area of ​​the weld portion can be increased, and the heat input of the weld portion in the joining direction can be improved compared to other portions. This can effectively stabilize the joining strength of the weld portion 50.

[0074] In addition, if Fig.7D As shown, the heat input portion 60 may also be formed by providing a through hole 63 having a diameter smaller than the point diameter of the weld portion 50 at the end portion 261 of the electrode lead 26. The surface area of ​​the weld portion is increased by the inner side surface of the through hole 63, and the heat input property can be improved toward the center side of the weld portion 50 by the shape of the through hole 63. Therefore, the heat input property of the weld portion can be improved, and the penetration of the base material can be deepened toward the center of the weld portion 50. As a result, the bonding strength of the weld portion 50 can be more effectively stabilized.

[0075] In addition, if Fig. 7E As shown, the heat input portion 60 may also be formed by coating the surface of the end portion 261 of the electrode lead 26 with a black material 68 to improve the heat input property and stabilize the bonding strength of the weld portion 50 .

[0076] In addition, Figure 7A to Figure 7EIn the heat input portion 60 ( 60A to 60E) shown, the width of the heat input portion 60 may be set smaller than the width of the weld portion 50 in order to suppress a decrease in the mechanical strength of the end portion 261 of the electrode lead 26 .

[0077] In addition, Figure 7A to Figure 7E In the heat input portion 60 (60A to 60E) shown, the heat input portion 60 is formed by surface processing that can be visually seen from the processed surface of the weld portion 50. Therefore, the heat input portion can easily align the position of the electrode lead 26 relative to the bus bar 30, etc. In addition, when the heat input portion 60 is formed on both the electrode lead 26 and the bus bar 30, the length of the heat input portion on the bus bar in the width direction can also be formed to be longer than the width of the electrode lead 26. Therefore, by configuring the heat input portion 60 so that both sides can be visually seen when viewed from the joining direction, the position of the electrode lead relative to the bus bar 30 can be further easily aligned.

Claims

1. A battery module, characterized in that: have: A plurality of battery cells stacked on top of each other; electrode leads protruding from the battery cell; A bus bar having an overlapping portion overlapping with an end portion of the electrode lead, wherein the bus bar is electrically connected to the electrode lead via a welding portion at the overlapping portion; and A heat input portion is formed at a position overlapping the weld portion on at least one of the electrode lead and the bus bar, and is composed of a thin-walled portion having a plate thickness thinner than other portions.

2. The battery module according to claim 1, characterized in that: The thin-walled portion constitutes a groove portion extending linearly on at least one of the electrode lead and the bus bar; A plurality of the welding portions are formed along the groove portion in a dotted shape when viewed from the joining direction.

3. The battery module according to claim 2, characterized in that: The groove portion has a V-shaped cross-sectional shape.

4. The battery module according to claim 2, characterized in that: The groove portion has a concave curved cross-sectional shape.

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