Battery module

Abstract

The utility model 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 utility model relates to a battery module. Background Art

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

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

[0004] However, in the battery module disclosed in Japanese Patent No. 7062162 as described above, when welding the ends of two electrode leads simultaneously with the upper and lower ones overlapping, the cost increases due to the high output of the welding machine.

[0005] In consideration of the above circumstances, an object of the present utility model is to obtain a battery module capable of simultaneously reducing man-hours and cost in the welded portions of the bus bar and a plurality of electrode leads.

[0006] The battery module according to the first aspect includes: 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 welded portion, and the welded portion for joining the electrode leads and the bus bar is formed across the ends of the plurality of electrode leads on a surface of the bus bar where the ends of the plurality of electrode leads are close to each other.

[0007] In the battery module according to the first aspect,

[0008] a plurality of battery cells stacked on each other are provided.

[0009] In addition, the electrode leads protruding from the respective battery cells are electrically joined to the bus bar via the welded portion. Here, on the surface of the bus bar where the ends of the plurality of electrode leads are close to each other, the welded portion for joining the electrode leads and the bus bar is formed across the ends of the plurality of electrode leads.

[0010] Thereby, a plurality of electrode leads can be joined to the bus bar side simultaneously via the common welded portion, and the man-hours for welding can be reduced. In addition, since the welded portion is formed across the ends of the plurality of electrode leads, compared with the structure in which the ends of the plurality of electrode leads are welded with the upper and lower ones overlapping along the joining direction, the output of the welding machine can be made low output, and the cost for welding can be reduced.

[0011] In addition, the term "the ends of a plurality of electrode leads are close to each other" as used herein refers to a broad concept that includes both the state where the ends of a plurality of electrode leads are in contact with each other and the state where the ends of a plurality of electrode leads are separated from each other and close to each other.

[0012] In the battery module of the second embodiment, in the first embodiment,

[0013] When viewed from the joining direction of the welding portion, the welding portion is formed in a dot shape.

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

[0015] In the battery module of the third embodiment, in the first embodiment or the second embodiment,

[0016] Regarding the welding portion, on at least one of the electrode lead and the bus bar, a heat input portion is formed in which the heat input property in the joining direction is improved compared to other portions.

[0017] In the battery module of the third embodiment, regarding the welding portion, on at least one of the electrode lead and the bus bar, a heat input portion is formed in which the heat input property in the joining direction is improved compared to other portions. As a result, the penetration depth of the base material of the welding portion can be increased through the heat input portion, and the joining can be stabilized.

[0018] In the battery module of the fourth embodiment, in the third embodiment,

[0019] The heat input portion is formed by surface processing that increases the surface area of the welding portion.

[0020] In the battery module of the fourth embodiment, regarding the welding portion, the surface area of the welding portion is increased by surface processing using the heat input portion, thereby improving the heat input property in the joining direction. As a result, the penetration depth of the base material of the welding portion can be increased, and the joining can be stabilized.

[0021] In the battery module of the fifth embodiment, in the third embodiment,

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

[0023] In the battery module of the fifth embodiment, regarding the welding portion, a black material is applied to the welding portion by surface processing using the heat input portion, thereby improving the heat input property in the joining direction. As a result, the penetration depth of the base material of the welding portion can be increased, and the joining can be stabilized.

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

[0025] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present utility model will be described with reference to the drawings, in which like reference numerals denote like elements, wherein:

[0026] Figure 1 is a schematic top view of a main part of a vehicle equipped with a battery pack according to an application embodiment.

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

[0028] Figure 3 is a top view of a state in which the upper cover of the module housing of the battery module according to the embodiment is removed.

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

[0030] Figure 5 is a schematic top view showing a state in which a plurality of battery cells are housed in the module housing, partially enlarged.

[0031] Figure 6A is an enlarged front view as viewed from the A direction showing the welding portion where a plurality of electrode leads and a bus bar are joined. Figure 5 of.

[0032] Figure 6B is a schematic view showing Figure 6A a magnified cross-sectional view of a cross-section cut along the B-B line of.

[0033] Figure 7A is a magnified cross-sectional view corresponding to and showing an example of a heat input portion formed in the welding portion. Figure 6B of.

[0034] Figure 7B is a magnified cross-sectional view corresponding to and showing an example of a heat input portion formed in the welding portion. Figure 6B of.

[0035] Figure 7C is a magnified cross-sectional view corresponding to and showing an example of a heat input portion formed in the welding portion. Figure 6B of.

[0036] Figure 7D is a magnified cross-sectional view corresponding to and showing an example of a heat input portion formed in the welding portion. Figure 6B of.

[0037] Figure 7E is an enlarged cross-sectional view showing an example of a heat input portion formed at a welded portion and corresponding to Figure 6B the following. DETAILED DESCRIPTION

[0038] Hereinafter, with reference to Figures 1 to 6B , an embodiment of the present invention will be described.

[0039] Overall Structure of Vehicle 100

[0040] Figure 1 is a schematic top view showing the main part of a vehicle 100 to which a battery pack 10 of an application embodiment is applied. As Figure 1 shown, the vehicle 100 is a battery electric vehicle (BEV) having a battery pack 10 mounted on a chassis. In addition, the arrows UP, FR, and LH in each figure respectively indicate the upper side in the vehicle up-down direction, the front side in the vehicle front-rear direction, and the left side in the vehicle width direction. When the directions of front, rear, left, right, up, and down are used for description, unless otherwise specified, the front and rear in the vehicle front-rear direction, the left and right in the vehicle width direction, and the up and down in the vehicle up-down 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 of the battery pack 10. In addition, a motor 108, a gearbox 110, an inverter 112, and a charger 114 are arranged on the vehicle rear side of the battery pack 10.

[0042] Regarding the direct current output from the battery pack 10, after the voltage is adjusted by the DC / DC converter 102, it is supplied to the electric compressor 104, the PTC heater 106, the inverter 112, etc. In addition, by supplying power to the motor 108 via the inverter 112, the rear wheels rotate to make the vehicle 100 travel.

[0043] A charging port 116 is provided on the right side portion in the rear part of the vehicle 100. By connecting a charging plug of an external charging device (not shown) to the charging port 116, power can be stored in the battery pack 10 via the in-vehicle charger 114.

[0044] In addition, the arrangement, structure, etc. of each component constituting the vehicle 100 are not limited to the above-described structure. For example, it can also be applied to a hybrid electric vehicle (HV) equipped with an engine or a plug-in hybrid electric vehicle (PHEV). In addition, in the present embodiment, it is assumed that the vehicle is rear-wheel drive with the motor 108 mounted on the rear of the vehicle, but it is not limited thereto. It can also be a front-wheel drive vehicle with the motor 108 mounted on the front of the vehicle, or a pair of motors 108 can be mounted on the front and rear of the vehicle. Furthermore, it can also be a vehicle equipped with in-wheel motors 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, 5 battery modules 11 are arranged in the vehicle front-rear direction, and on the left side of the vehicle 100, 5 battery modules 11 are arranged in the vehicle front-rear direction. In addition, each battery module 11 is electrically connected.

[0046] Figure 2 is a schematic perspective view of the battery module 11. As Figure 2 shown, the battery module 11 includes a module case 16 that forms an outer shell. The module case 16 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the length direction. In addition, the module case 16 is formed of aluminum alloy. For example, the module case 16 is formed by joining aluminum die-castings to both ends of an extruded material of aluminum alloy by laser welding or the like.

[0047] At both ends in the vehicle width direction of the battery module 11, a pair of voltage terminals 12 and connectors 14 are respectively provided. A flexible printed circuit board 21 described later is connected to the connector 14. In addition, busbars 30 (refer to Figure 4 ) are welded to both ends in the vehicle width direction of the battery module 11.

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

[0049] Figure 3 is a top view of the battery module 11 with the upper cover removed. As Figure 3 shown, inside the module case 16, battery cells 20 serving as batteries are housed. As an example, a plurality of battery cells 20 are housed in an arranged (stacked) state inside the module case 16. In the present embodiment, 24 battery cells 20 are arranged and bonded to each other in the vehicle front-rear direction.

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

[0051] The width direction of the battery case 22 described later is the same as the width direction W of the battery cell 20. The height direction of the battery case 22 is the same as the height direction H of the battery cell 20. The thickness direction of the battery case 22 is the same as the thickness direction D of the battery cell 20.

[0052] A flexible printed circuit (FPC) 21 is disposed on the battery cell 20. The flexible printed substrate 21 is formed in a strip shape with the vehicle width direction as the length direction. At both ends of the flexible printed substrate 21, thermistors 23 are respectively provided. The thermistors 23 are structured such that they are not adhered to the battery cell 20 and are pressed toward the battery cell 20 side by the upper cover of the battery module 11.

[0053] In addition, inside the module case 16, one or more buffer materials (not shown) are accommodated. For example, the buffer material is an elastically deformable thin plate-like member. With the arrangement direction of the battery cells 20 as the thickness direction, the buffer material is disposed between adjacent battery cells 20. In the present embodiment, as an example, buffer materials are disposed at both end portions in the length direction and the central portion in the length direction of the module case 16.

[0054] Figure 4 is a schematic view of the battery cell 20 accommodated in the battery module 11 as viewed from the thickness direction D. As Figure 4 shown, the battery cell 20 is formed in a long rectangular plate shape with the width direction W as the length direction, and includes 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 laminated. In the present embodiment, the battery case 22 is made of a laminated film, and the electrode body 40 is sealed by the laminated 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, on the side surface, a concave housing portion 221 for housing the electrode body 40 inside and an outer end portion 223 provided outside the housing portion 221 are formed. In addition, the battery case 22 can adopt both a single-cup embossing structure with one embossing and a double-cup embossing structure with two embossings. In the present embodiment, the battery case 22 has 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 on which embossing is performed, and the second side surface 22B (refer to Figure 5 ) on the other side in the thickness direction is a non-embossed surface on which no embossing is performed.

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

[0057] Here, the battery cell 20 includes electrode leads 26 protruding from the end portion of the battery case 22. The electrode leads 26 are respectively provided at both end portions in the width direction of the battery cell. In the present embodiment, as an example, the electrode leads 26 are provided at a position biased downward from the center in 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 portion in the width direction of the battery case 22 and is electrically joined to the bus bar 30 via a welding portion 50 (refer to Figure 5 ). The electrode lead 26 is connected to the wiring outside the battery module 11 via the bus bar 30. For the welding of the electrode lead 26 and the bus bar 30, a known welding method can be appropriately adopted. However, in an 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 housing 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 5It is a schematic top view showing a state in which a plurality of battery cells 20 are housed in the module housing 16 with partial enlargement. As shown in this figure, inside the module housing 16, the other ends of the electrode leads 26 protrude from the ends in the width direction W of the plurality of battery cells 20 stacked on top of each other. In addition, plate-shaped bus bars 30 are arranged on one side and the other side in the width direction W of the battery cell 20 respectively.

[0060] In addition, in Figure 5 For ease of explanation, a gap is provided between the battery cells 20. However, in reality, the plurality of stacked battery cells 20 are in contact with each other via a buffer material or directly, and are mutually constrained in a state where a predetermined constraint pressure is applied along the stacking direction (thickness direction D).

[0061] The bus bar 30 has the width direction W of the battery cell 20 as the plate thickness direction and extends along the stacking direction (thickness direction D) of the battery cell 20. In addition, in the bus bar 30, a slot-shaped through hole 32 penetrating the bus bar 30 in the plate thickness direction is formed.

[0062] The other ends of the electrode leads 26 protruding from the ends in the width direction W of the battery cell 20 are inserted into the through holes 32 of the bus bar 30. In addition, the end portions 261 protruding from the through holes 32 are folded back toward the bus bar 30 side and overlap the surface of the bus bar 30.

[0063] A plurality of through holes 32 are formed in the bus bar 30, 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. In Figure 5 shows a state in which the electrode leads 26 protruding from two battery cells 20 are joined to the bus bar 30 via a welding portion 50. As Figure 5 shown, the two electrode leads 26 are respectively inserted through the through holes 32 formed in the bus bar 30. Moreover, the front end portions 261 of the two electrode leads 26 are folded back toward the bus bar 30 side in directions approaching each other. Thus, on the surface of the bus bar 30, the end portions of the two electrode leads 26 are disposed close to each other. Moreover, the end portions 261 of the two electrode leads 26 are joined to the bus bar 30 via the welding portion 50.

[0064] In addition, in the illustrated example, the end portions of the two electrode leads 26 approach each other in a separated state, but the end portions of the two electrode leads 26 may also be in contact with each other.

[0065] Figure 6A is a magnified front view of the welding portion 50 observed from the arrow A direction of Figure 5 . Figure 6B is a magnified sectional view showing a section of the welding portion 50 cut along the B - B line of Figure 6A .

[0066] As Figure 6A and Figure 6B shown, on the surface of the bus bar 30 where the ends of the two electrode leads 26 are close to each other, a welding 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 as the joining direction. In addition, since the welding portion 50 is formed by spot welding using a laser, it is formed in a circular dot shape when viewed from the joining direction (the plate thickness direction of the bus bar 30) of the welding portion 50.

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

[0068] Here, regarding the welding portion 50, a heat input portion 60 having a heat input property in the joining direction higher than that of 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 welding portion 50 is improved by the heat input portion 60, the penetration depth of the base material of the welding portion 50 is increased, and the joining of the electrode lead 26 and the bus bar 30 can be stabilized.

[0069] Refer to Figures 7A to 7E , and examples of the heat input portion 60 will be described. Here, a plurality of examples in which the heat input portion 60 is formed by processing the surface of the electrode lead 26 will be described. However, the structure of each heat input portion 60 may be provided on the bus bar 30, or may be provided on 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 materials, and the welding range is indicated by the region P surrounded by a double-dot chain line.

[0070] In Figures 7A to 7D the example shown, the heat input portion 60 is formed by surface processing that increases the surface area of the welding portion 50.

[0071] Figure 7A The first heat input portion 60A shown in

[0072] Figure 7B forms an inclined surface 61 at the end 261 of the electrode lead 26 to increase the surface area of the welding 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 welding range P. Thus, the heat input property on the center side of the welding portion 50 can be increased compared to the outer peripheral side, and the joining strength can be efficiently increased.The second heat input portion 60B shown forms a stepped portion 62 at the end portion 261 of the electrode lead 26, increasing the surface area of the welding portion 50. Further, by forming the stepped portion 62, the plate thickness of the end portion 261 of the electrode lead 26 closer to the center side of the welding range P is thinner than that of the outer peripheral side. Thereby, the heat input property of the center side of the welding portion 50 can be improved more than that of the outer peripheral side, and the bonding strength can be efficiently improved.

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

[0074] Further, convex portions 64 protruding along the surface of the bus bar 30 and concave portions 65 recessed relative to the convex portions 64 are alternately formed at the end portion 261 of the electrode lead 26, and are arranged such that the convex portions 64 and the concave portions 65 of the two electrode leads 26 are engaged with each other, thereby forming Figure 7D the fifth heat input portion 60E shown. In this heat input portion 60E, for example, the welding range P is set at the position where the convex portions 64 and the concave portions 65 are engaged with each other, so that the facing area (surface area) between the end portions 261 can be increased.

[0075] On the other hand, regarding Figure 7E the fourth heat input portion 60D shown, a heat input portion 60 is formed by surface processing of applying a black material 68 to the end portion 261 (welding portion 50) of the electrode lead 26. Thereby, the black material 68 absorbs the laser, the heat input property of the welding portion 50 can be improved, and the melting of the base material can be promoted.

[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. Further, the electrode leads 26 protruding from each battery cell 20 are electrically bonded to the bus bar 30 via the welding portion 50. Here, on the surface of the bus bar 30 where the end portions 261 of the plurality of electrode leads 26 are close to each other, the welding portion 50 that bonds the electrode lead 26 and the bus bar 30 is formed across the end portions 261 of the plurality of electrode leads 26. Thereby, a plurality of electrode leads 26 can be simultaneously bonded to the bus bar 30 side via the common welding portion 50, and the number of welding steps can be reduced. Further, since the welding portion 50 is formed across the end portions 261 of the plurality of electrode leads 26, compared with a structure in which the end portions of a plurality of electrode leads are welded while being vertically overlapped along the bonding direction, the output of the welding machine can be made a low output, and cost reduction of welding can be achieved.

[0078] In the present embodiment, the welding portion 50 is formed in a dot shape when viewed from the joining direction of the welding portion 50. Therefore, a plurality of electrode leads 26 can be simultaneously joined to the bus bar 30 side via the dot-shaped welding portion based on laser welding or the like. As a result, the range of the welding portion 50 can be reduced, deformation of the base material and welding burn marks caused by welding heat can be suppressed, and the man-hours of the finishing process can be reduced.

[0079] In the present embodiment, as Figures 7A to 7E shown, with respect to the welding portion 50, a heat input portion 60 having a heat input property in the joining direction higher than that of other portions is formed on at least one of the electrode lead 26 and the bus bar 30. As a result, the penetration depth of the base material of the welding portion 50 can be increased by the heat input portion 60, and the joining can be stabilized.

[0080] In Figures 7A to 7D the example shown, with respect to the welding portion 50, the surface area of the welding portion 50 is increased by surface processing of the heat input portion 60 (60A to 60D), and the heat input property in the joining direction is improved. As a result, the penetration depth of the base material of the welding portion 50 can be increased, and the joining can be stabilized.

[0081] On the other hand, in Figure 7E one example shown, with respect to the welding portion 50, a black material 68 is applied to the welding portion 50 by surface processing of the heat input portion 60E, and the heat input property in the joining direction is improved. As a result, the penetration depth of the base material of the welding portion 50 can be increased, and the joining can be stabilized.

[0082] As described above, one embodiment and one modification example have been described, but the present utility model can be implemented with various changes without departing from its gist. The scope of rights of the present utility model is of course not limited to the above-described embodiment.

[0083] For example, in the above-described embodiment, the ends of two electrode leads are joined simultaneously, but it is not limited thereto. Three or more electrode leads 26 may be brought close to each other on the surface of the bus bar, and a welding portion may be formed so as to straddle these ends.

Claims

1. A battery module, characterized in that: have: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The heat input portion is formed by surface processing in which a black material is applied to the weld portion.

Images