Battery module

Abstract

The invention provides a battery module. A battery module is provided with: a plurality of battery cells stacked on each other; an electrode lead protruding from the battery cell; and a bus bar which is electrically joined to the electrode leads via a welding portion formed across the ends of the plurality of electrode leads on a surface where the ends of the plurality of electrode leads approach each other.

Description

Technical Field

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

[0002] The battery module disclosed in Japanese Patent No. 7062162 below includes a plurality of battery cells stacked one on another and a bus bar assembly electrically connected to electrode leads of the plurality of battery cells. In this battery module, ends of two electrode leads are gathered on the bus bar assembly and joined by welding or the like. Summary of the invention

[0003] However, when welding the end portions of a plurality of electrode leads to a bus bar, it is preferable to weld the plurality of electrode leads simultaneously from the viewpoint of reducing the number of man-hours.

[0004] However, in the case of a battery module disclosed in Japanese Patent No. 7062162, when the ends of two electrode leads are welded simultaneously while being stacked up and down, the output of the welding machine is increased, which increases the cost.

[0005] The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a battery module capable of simultaneously achieving a reduction in man-hours and a reduction in cost in welding portions between a bus bar and a plurality of electrode leads.

[0006] The battery module of the first scheme comprises: a plurality of battery cells stacked on each other; electrode leads protruding from the battery cells; and a bus bar electrically joined to the electrode leads via a welding portion, the welding portion being formed on a surface where the ends of the plurality of electrode leads are close to each other, spanning the ends of the plurality of electrode leads.

[0007] In the battery module of the first aspect,

[0008] It has a plurality of battery cells stacked on top of each other.

[0009] The electrode leads protruding from each battery cell are electrically joined to the bus bar via a welding portion. Here, a welding portion joining the electrode leads and the bus bar is formed across the ends of the electrode leads on the surface of the bus bar where the ends of the electrode leads are close to each other.

[0010] Thus, a plurality of electrode leads can be simultaneously joined to the busbar side via a common welding portion, and the number of welding operations can be reduced. In addition, since the welding portion is formed across the ends of a plurality of electrode leads, the output of the welding machine can be lowered compared to a structure in which the ends of a plurality of electrode leads are welded by overlapping each other up and down along the joining direction, and the cost of welding can be reduced.

[0011] In addition, “the ends of the plurality of electrode leads are close to each other” mentioned here is a broad concept including both a state in which the ends of the plurality of electrode leads are in contact with each other and a state in which the ends of the plurality of electrode leads are separated from each other and close to each other.

[0012] The battery module of the second embodiment is a battery module of the first embodiment.

[0013] The welded portion is formed in a dot shape when viewed from the joining direction of the welded portion.

[0014] In the battery module of the second embodiment, the welded portion is formed in a point shape when viewed from the joining direction of the welded portion. Therefore, a plurality of electrode leads can be simultaneously joined to the busbar side via the point-shaped welded portion based on laser welding or the like. As a result, the range of the welded portion can be reduced, deformation of the base material and weld burn marks caused by welding heat can be suppressed, and the number of man-hours for finishing processing can be reduced.

[0015] The battery module of the third aspect is, in the first aspect or the second aspect,

[0016] The weld portion includes a heat input portion in which heat input in the joining direction is higher than that of other portions, formed in at least one of the electrode lead and the bus bar.

[0017] In the battery module of the third aspect, regarding the weld, a heat input portion having a higher heat input property in the joining direction than other portions is formed on at least one of the electrode lead and the bus bar. As a result, the heat input portion can deepen the penetration of the base material of the weld, and the joining can be stabilized.

[0018] The battery module of the fourth embodiment is a battery module of the third embodiment.

[0019] The heat input portion is formed by surface processing to increase the surface area of ​​the welded portion.

[0020] In the battery module of the fourth aspect, the surface area of ​​the weld is increased by surface processing of the heat input portion, thereby improving the heat input in the joining direction. This can deepen the penetration of the base material of the weld and stabilize the joining.

[0021] The battery module of the fifth embodiment is the battery module of the third embodiment.

[0022] The heat input portion is formed by surface processing in which a black material is applied to the weld portion.

[0023] In the battery module of the fifth aspect, the heat input to the welding part is improved by coating the welding part with black material by surface processing of the heat input part. This can deepen the penetration of the base material of the welding part and stabilize the welding.

[0024] As described above, in the battery module of the present invention, it is possible to simultaneously achieve a reduction in man-hours and a reduction in cost in the welding portions between the bus bar and the plurality of electrode leads. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0026] Figure 1 It is a schematic plan view showing a main part of a vehicle to which the battery pack according to the embodiment is applied.

[0027] Figure 2 It is a schematic perspective view of a battery module according to an embodiment.

[0028] Figure 3 It is a plan view of the battery module according to the embodiment with the upper cover of the module case removed.

[0029] Figure 4 This is a schematic diagram of battery cells housed in a battery module as viewed from the thickness direction.

[0030] Figure 5 It is a schematic plan view partially enlarged to show a state where a plurality of battery cells are accommodated in a module case.

[0031] Fig. 6A FIG. 1 is an enlarged view showing a welding portion joining a plurality of electrode leads and a bus bar. Figure 5 Enlarged main view observed from direction A.

[0032] Figure 6B It is shown along Fig. 6A An enlarged cross-sectional view of the cross section cut along line BB.

[0033] Fig. 7A is an example of a heat input portion formed in a welded portion, and Figure 6B Corresponding enlarged cross-section.

[0034] Figure 7B is an example of a heat input portion formed in a welded portion, and Figure 6B Corresponding enlarged cross-section.

[0035] Figure 7C is an example of a heat input portion formed in a welded portion, and Figure 6B Corresponding enlarged cross-section.

[0036] Fig.7D is an example of a heat input portion formed in a welded portion, and Figure 6B Corresponding enlarged cross-section.

[0037] Fig. 7E is an example of a heat input portion formed in a welded portion, and Figure 6B Corresponding enlarged cross-section. DETAILED DESCRIPTION

[0038] Below, refer to Figures 1 to 6B , describing an embodiment of the present invention.

[0039] Overall structure of vehicle 100

[0040] Figure 1 1 is a schematic top 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 a battery electric vehicle (BEV) having a battery pack 10 mounted on a chassis. In addition, 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-rear direction, and the left side in the vehicle width direction. When the front-rear, left-right, up-down directions are used for description, unless otherwise specified, the front-rear direction in the vehicle front-rear direction, the left-right direction in the vehicle width direction, and the up-down direction in the vehicle vertical direction are indicated.

[0041] In the vehicle 100 of the present embodiment, as an example, a DC / DC converter 102, an electric compressor 104, and a positive temperature coefficient (PTC) heater 106 are arranged 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 charger 114 are arranged on the vehicle rear side relative to the battery pack 10.

[0042] 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.

[0043] A charging port 116 is provided at 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 , electric power can be stored in the battery pack 10 via the on-vehicle charger 114 .

[0044] In addition, the configuration and structure of each component constituting the vehicle 100 are not limited to the above-mentioned structure. For example, it can also be applied to a hybrid electric vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. In addition, in the present embodiment, a rear-wheel drive vehicle with a motor 108 mounted at the rear of the vehicle is provided, but it is not limited thereto, and it can also be a front-wheel drive vehicle with a motor 108 mounted at the front of the vehicle, and a pair of motors 108 can also be mounted at the front and rear of the vehicle. Furthermore, it can also be a vehicle with a hub motor on each wheel.

[0045] 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, on the right side of the vehicle 100, five battery modules 11 are arranged in the vehicle front-rear direction, and on the left side of the vehicle 100, five battery modules 11 are arranged in the vehicle front-rear direction. In addition, each battery module 11 is electrically connected.

[0046] Figure 2 1 is a schematic three-dimensional diagram of the battery module 11. Figure 2 As shown, the battery module 11 includes a module housing 16 forming an outer shell. The module housing 16 is formed into a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal 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 extruded material by laser welding or the like.

[0047] 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. A flexible printed circuit board 21 described later is connected to the connector 14. 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 ).

[0048] The battery module 11 has a length MW in the vehicle width direction of, for example, 350 mm to 600 mm, a length ML in the vehicle front-rear direction of, for example, 150 mm to 250 mm, and a height MH in the vehicle vertical direction of, for example, 80 mm to 110 mm.

[0049] 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 arranged (stacked) state inside the module case 16. In this embodiment, 24 battery cells 20 are arranged in the vehicle front-rear direction and bonded to each other.

[0050] In addition, for easy understanding, Figures 3 to 6A In each of the figures, the direction indicated by the arrow W is the width direction of the battery cell 20, the direction indicated by the arrow H is the height direction (vertical direction) of the battery cell 20, and the direction indicated by the arrow D is the thickness direction of the battery cell 20.

[0051] 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 .

[0052] A flexible printed circuit (FPC) 21 is arranged on the battery cell 20. The flexible printed circuit 21 is formed in a strip shape with the vehicle width direction as the longitudinal direction. Thermistors 23 are provided at both ends of the flexible printed circuit 21. The thermistor 23 is a structure that is not bonded to the battery cell 20 and is pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0053] 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 the arrangement direction of the battery cells 20 is set as the thickness direction, and the buffer material is arranged between adjacent battery cells 20. In this embodiment, as an example, the buffer material is arranged at both ends in the longitudinal direction and the central part in the longitudinal direction of the module case 16.

[0054] Figure 4 2 is a schematic diagram of a battery cell 20 housed in a battery module 11 as viewed from the thickness direction D. Figure 4 As shown, the battery cell 20 is formed into a rectangular plate shape with the width direction W as the length direction, and is provided with a battery case 22 forming an outer shell. Inside the battery case 22, an electrode body 40 is accommodated. The electrode body 40 is composed of a positive electrode as an electrode, a negative electrode as an electrode, and a separator. In this embodiment, the battery case 22 is composed of a laminate film, and the electrode body 40 is sealed by the laminate film.

[0055] Regarding the battery case 22, embossing is performed on at least one side in the thickness direction of the battery case 22. By performing the embossing, a concave housing portion 221 for internally accommodating the electrode body 40 and an outer end portion 223 provided on the outer side of the housing portion 221 are formed on the side. In addition, the battery case 22 can adopt both a single cup type embossing structure in which 1 place is embossed and a double cup type embossing structure in which 2 places are embossed. In the present embodiment, the battery case 22 is a single cup embossing structure with a drawing depth of about 8 mm to 10 mm. Therefore, regarding the battery case 22, the first side surface 22A on one side in the thickness direction is an embossed surface to which embossing is performed, and the second side surface 22B (refer to Figure 5 ) is a non-embossed surface that has not been embossed.

[0056] The upper end of the battery case 22 in the width direction is bent, and the corners are chamfered to form a substantially trapezoidal shape. In addition, the upper end of the battery case 22 is bent, and a fixing band 24 is wound around the upper end of the battery case 22 in the width direction.

[0057] Here, the battery cell 20 includes an electrode lead 26 protruding from the end of the battery case 22. The electrode lead 26 is 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 lower than 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 wiring outside the battery module 11 via the bus bar 30. In welding the electrode lead 26 and the bus bar 30, a known welding method can be appropriately used, but in one example of the present embodiment, the electrode lead 26 and the bus bar 30 are joined by laser welding.

[0058] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, the length CW2 of the region containing the electrode body is, for example, 500 mm to 520 mm, and the height CH of the battery cell 20 is, for example, 80 mm to 110 mm. In addition, the thickness of the battery cell 20 is 7.0 mm to 9.0 mm, and the height TH of the electrode lead (terminal) 26 is 40 mm to 50 mm.

[0059] Figure 51 is a schematic plan view partially enlarged to show a state where a plurality of battery cells 20 are accommodated in a module case 16. As shown in the figure, the other ends of the electrode leads 26 protrude from the ends of the plurality of battery cells 20 stacked on each other in the width direction W in the module case 16. In addition, a plate-shaped bus bar 30 is disposed on each of one side and the other side in the width direction W of the battery cell 20.

[0060] In addition, Figure 5 In the figure, for convenience of explanation, a space is provided between the battery cells 20. However, in reality, the stacked battery cells 20 are mutually restrained via a buffer material or directly in contact with each other while a predetermined restraining pressure is applied in the stacking direction (thickness direction D).

[0061] 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 slot-shaped through hole 32 that penetrates the bus bar 30 in the plate thickness direction.

[0062] 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.

[0063] The bus bar 30 has a plurality of through holes 32 formed therein, and the electrode leads 26 protruding from the plurality of battery cells 20 are inserted through the 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 5 , the electrode leads 26 protruding from the two battery cells 20 are shown to be joined to the bus bar 30 via the welding portion 50. Figure 5 As shown in FIG. 1 , the two electrode leads 26 are respectively inserted into the through holes 32 formed in the bus bar 30. Furthermore, the front end portions 261 of the two electrode leads 26 are folded back toward the bus bar 30 in a direction approaching each other. Thus, the ends of the two electrode leads 26 are arranged close to each other on the surface of the bus bar 30. Furthermore, the ends 261 of the two electrode leads 26 are joined to the bus bar 30 via the welding portion 50.

[0064] In the example shown in the figure, the ends of the two electrode leads 26 are close to each other in a state of being separated from each other, but the ends of the two electrode leads 26 may be in contact with each other.

[0065] Fig. 6A is from Figure 5 An enlarged front view of the welding portion 50 as viewed in the direction of arrow A. Figure 6B It is shown along Fig. 6A FIG. 5 is an enlarged cross-sectional view of a cross section of the welding portion 50 cut along line BB.

[0066] like Fig. 6A as well as Figure 6B As shown, on the surface of the bus bar 30 where the ends of the two electrode leads 26 are close to each other, a welded portion 50 is formed across the ends of the two electrode leads 26. Thus, the ends 261 of the two electrode leads 26 are simultaneously joined with the plate thickness direction of the bus bar 30 being the joining direction. In addition, the welded portion 50 is formed by spot welding using a laser, so it is formed in a circular spot shape when viewed from the joining direction of the welded portion 50 (plate thickness direction of the bus bar 30).

[0067] In the present embodiment, the ends 261 of the two electrode leads 26 are arranged to face each other in the thickness direction D of the battery cell 20 , and a plurality of welded portions 50 are formed along a center line C1 between the ends 261 .

[0068] Here, regarding the weld 50, a heat input portion 60 having a higher heat input property in the joining direction than other portions is formed on at least one of the electrode lead 26 and the bus bar 30. As an example, the heat input portion 60 is formed by processing the surface of at least one of the electrode lead 26 and the bus bar 30. When the heat input property of the weld 50 is increased by the heat input portion 60, the penetration of the base material of the weld 50 is deepened, and the joining of the electrode lead 26 and the bus bar 30 can be stabilized.

[0069] Reference 7A to 7E , an example of the heat input portion 60 is described. Here, a plurality of examples of forming the heat input portion 60 by processing the surface of the electrode lead 26 are listed for description. However, the structure of each heat input portion 60 may be provided in the bus bar 30, or may be provided in both the electrode lead 26 and the bus bar 30. In addition, each figure shows the state before the welding portion 50 is formed on the electrode lead 26 and the bus bar 30 as the base material, and the welding range is represented by the area P surrounded by the double-dashed line.

[0070] exist FIG. 7A to FIG. 7D In the illustrated example, the heat input portion 60 is formed by surface processing to increase the surface area of ​​the weld portion 50 .

[0071] Fig. 7A The first heat input portion 60A shown has an inclined surface 61 formed at the end 261 of the electrode lead 26, thereby increasing the surface area of ​​the weld portion 50. In addition, by forming the inclined surface 61, the plate thickness of the end 261 of the electrode lead 26 becomes thinner toward the center side of the weld range P. As a result, the heat input property of the center side of the weld portion 50 can be increased compared to the peripheral side, and the bonding strength can be effectively improved.

[0072] Figure 7BThe second heat input portion 60B shown has a step portion 62 formed at the end portion 261 of the electrode lead 26, thereby increasing the surface area of ​​the weld portion 50. In addition, by forming the step portion 62, the plate thickness of the end portion 261 of the electrode lead 26 near the center side of the weld range P is thinner than the plate thickness on the peripheral side. As a result, the heat input property of the center side of the weld portion 50 can be increased compared to the peripheral side, and the bonding strength can be effectively improved.

[0073] about Figure 7C In the third heat input portion 60C shown, the end portion 261 of the electrode lead 26 is roughened compared to other portions, thereby increasing the surface area of ​​the weld portion 50 .

[0074] In addition, the end portion 261 of the electrode lead 26 is alternately formed with a convex portion 64 protruding along the surface of the busbar 30 and a concave portion 65 retreating relative to the convex portion 64, and the convex portion 64 and the concave portion 65 of the two electrode leads 26 are arranged in a manner that the convex portion 64 and the concave portion 65 are engaged with each other, thereby forming Fig.7D The fifth heat input portion 60E shown in FIG. In the heat input portion 60E, for example, a welding range P is provided at a position where the convex portion 64 and the concave portion 65 meet, so that the facing area (surface area) of the end portions 261 can be increased.

[0075] On the other hand, regarding Fig. 7E The fourth heat input portion 60D shown is formed by surface processing by applying a black material 68 to the end portion 261 (weld portion 50) of the electrode lead 26. The black material 68 absorbs laser light, thereby increasing the heat input of the weld portion 50 and promoting melting of the base material.

[0076] Function and effect

[0077] As described above, the battery module 11 of the embodiment includes a plurality of battery cells 20 stacked on each other. In addition, the electrode lead 26 protruding from each battery cell 20 is electrically joined to the bus bar 30 via a welding portion 50. Here, on the surface of the bus bar 30 where the ends 261 of the plurality of electrode leads 26 are close to each other, a welding portion 50 for joining the electrode lead 26 and the bus bar 30 is formed across the ends 261 of the plurality of electrode leads 26. Thus, the plurality of electrode leads 26 can be simultaneously joined to the bus bar 30 side via a common welding portion 50, and the number of welding operations can be reduced. In addition, since the welding portion 50 is formed across the ends 261 of the plurality of electrode leads 26, the output of the welding machine can be made low compared to a structure in which the ends of the plurality of electrode leads are welded by overlapping each other up and down along the joining direction, and the cost of welding can be reduced.

[0078] In the present embodiment, the welded portion 50 is formed in a dotted shape when viewed from the joining direction of the welded portion 50. Therefore, a plurality of electrode leads 26 can be simultaneously joined to the bus bar 30 side via the dotted welded portions by laser welding or the like. Thus, the range of the welded portion 50 can be reduced, deformation of the base material due to welding heat and weld burn marks can be suppressed, and the number of man-hours for finishing processing can be reduced.

[0079] In this embodiment, if 7A to 7E As shown, regarding the weld 50, a heat input portion 60 having a higher heat input property in the joining direction than other portions is formed in at least one of the electrode lead 26 and the bus bar 30. As a result, the heat input portion 60 can deepen the penetration of the base material of the weld 50, and the joining can be stabilized.

[0080] exist FIG. 7A to FIG. 7D In the example shown, the surface area of ​​the weld 50 is increased by surface processing of the heat input portion 60 (60A to 60D), thereby improving the heat input in the joining direction. This can deepen the penetration of the base material of the weld 50 and stabilize the joining.

[0081] On the other hand, Fig. 7E In the example shown, the heat input property in the joining direction is improved by applying black material 68 to the weld 50 by surface processing of the heat input portion 60E. This can deepen the penetration of the base material of the weld 50 and stabilize the joining.

[0082] Although one embodiment and one modification have been described above, the present invention can be implemented with various modifications without departing from the gist of the invention. The scope of rights of the present invention is of course not limited to the above-described embodiment.

[0083] For example, in the above embodiment, the ends of two electrode leads are simultaneously joined, but the present invention is not limited thereto. The ends of three or more electrode leads 26 may be brought close to each other on the surface of the bus bar, and a weld may be formed across these ends.

Claims

1. A battery module comprising: A plurality of battery cells stacked on top of each other; an electrode lead protruding from the battery cell; and The bus bar is electrically joined to the electrode lead via a welding portion, and the welding portion is formed across the ends of the plurality of electrode leads on a surface where the ends of the plurality of electrode leads are close to each other.

2. The battery module according to claim 1, wherein: The welded portion is formed in a dot shape when viewed from the joining direction of the welded portion.

3. The battery module according to claim 1 or 2, wherein: The weld portion includes a heat input portion in which heat input in the joining direction is higher than that of other portions, in at least one of the electrode lead and the bus bar.

4. The battery module according to claim 3, wherein: The heat input portion is formed by surface processing to increase the surface area of ​​the welded portion.

5. The battery module according to claim 3, wherein: The heat input portion is formed by surface processing in which a black material is applied to the weld portion.

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