Busbar and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a busbar and a battery pack. The busbar is of a double-layer plate-shaped structure and comprises a first busbar plate and a second busbar plate, and the thickness of the first busbar plate is smaller than that of the second busbar plate. The first bus board is provided with two pole positioning holes; the second bus board is provided with two pole welding holes, and the size of the pole welding holes is larger than that of the pole positioning holes; the two pole positioning holes are correspondingly formed in the two pole welding holes respectively; the first confluence plate and the second confluence plate are connected at intervals, and a heat dissipation gap is formed between the plate surfaces of the first confluence plate and the second confluence plate. According to the busbar provided by the invention, the double-layer plate-shaped structure is adopted, so that the welding problem of pseudo soldering or hole explosion can be avoided; the over-current sectional area of the busbar can be multiplied, and the temperature rise is small when a large current passes through the busbar; extra heat is prevented from being transferred into the battery cell to influence the cycle life of the battery cell, and the design requirement of a fast charging system of more than 3C is met.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a bus bar and a battery pack. Background Art

[0002] In the battery pack, adjacent battery cells are connected in series by welding the busbars to the battery cell poles.

[0003] The current bus has the following technical problems:

[0004] 1. The busbar is thicker, which will cause a gap between the busbar and the battery cell pole during laser welding, causing welding quality problems such as cold welding and hole explosion.

[0005] 2. With the increasing requirements for fast charging rates of electric vehicles, the charging current is also increasing. In order to reduce the temperature generated by large current passing through the bus, it is necessary to increase the cross-sectional area of ​​the bus. Because the thickness of the stamped bus in the existing technology can only be 2mm at most, the cross-sectional area can only be increased by increasing the width of the bus. However, the space in the width direction of the bus in the module is limited, and the width of the bus cannot be increased too much. The cross-sectional area of ​​the bus is small, and the temperature rises when a large current passes through it. The high temperature will be transmitted to the inside of the battery cell, causing the battery cell temperature to rise and affecting the cycle life of the battery cell. Therefore, the cross-sectional area of ​​the stamped bus does not meet the requirements of fast charging systems above 3C. Summary of the invention

[0006] In view of this, the present invention provides a bus and a battery pack to solve the quality problems of bus welding, the limited width of the bus, the small current cross-sectional area, the temperature rise when large current passes through, and the inability to meet the requirements of fast charging systems above 3C.

[0007] In the first aspect, the present invention provides a busbar, which is a double-layer plate structure, including a first busbar suitable for welding to the poles of the battery cells and a second busbar away from the poles of the battery cells, the thickness of the first busbar is less than the thickness of the second busbar; the first busbar is provided with two pole positioning holes for positioning welding to the poles of adjacent battery cells; the second busbar is provided with two pole welding holes, the size of the pole welding holes is larger than the size of the pole positioning holes; the two pole positioning holes are respectively arranged in the two pole welding holes; the first busbar and the second busbar are connected at an interval, and a heat dissipation gap is formed between the plate surfaces of the first busbar and the second busbar.

[0008] Beneficial effects: The busbar provided by the present invention adopts a double-layer plate structure, which includes a first busbar that is welded in contact with the battery cell pole and a second busbar that is not welded to the battery cell pole. Since the wall thickness and rigidity of the first busbar are relatively small, the laser welding head can easily press the busbar against the poles of two adjacent battery cells, tightly fitting them and avoiding welding problems such as cold welding or blown holes. The wall thickness of the second busbar is relatively large, and since the busbar is a double-layer structure design, the thickness of the second busbar that is not in contact with the battery cell pole is not restricted, which can increase the cross-sectional area of ​​the busbar exponentially, and the temperature rise when a large current passes through is small. At the same time, a heat dissipation gap is formed between the first busbar and the second busbar, and the double-layer structure also increases the heat dissipation area of ​​the busbar, preventing additional heat from being transferred to the inside of the battery cell and affecting the cycle life of the battery cell. Therefore, the busbar of the present invention can meet the design requirements of fast charging systems above 3C.

[0009] In an optional implementation, the thickness of the first busbar is T1, where T1≤1.5 mm.

[0010] In an optional implementation, the thickness of the second busbar is T2, where T2 ≥ 2 mm.

[0011] In an optional embodiment, at least one reinforcing rib is provided in the heat dissipation gap, and the reinforcing rib is connected between the first busbar and the second busbar.

[0012] In an optional embodiment, the first busbar includes a main body portion and a raised portion, the height of the heat dissipation gap corresponding to the raised portion is H1, the height of the heat dissipation gap corresponding to the main body portion is H2, and H1≠H2.

[0013] In an optional implementation, the raised portion is a protrusion facing in a direction away from the heat dissipation gap, H1>H2, 2mm≤H2≤10mm.

[0014] In an optional embodiment, the raised portion is located in the middle of the busbar, and at least two raised portions are provided. The raised portions extend to both sides of the busbar along the width direction of the busbar, and the reinforcing rib is located between two adjacent raised portions.

[0015] In an optional embodiment, a surface of the second busbar away from the heat dissipation gap is provided with a plurality of heat dissipation fins.

[0016] In an optional implementation, the height of the heat dissipation fin is H3, 1mm≤H3≤10mm.

[0017] In the second aspect, the present invention also provides a battery pack, comprising a plurality of battery cells arranged side by side, and a bus in the above technical solution, wherein the bus is arranged on the side where the poles of the battery cells are located, and the two pole positioning holes of the first bus plate of the bus are respectively welded to the poles with different polarities of two adjacent battery cells to connect the two battery cells in series.

[0018] Beneficial effect: Because the battery pack includes a bus bar, it has the same effect as the bus bar and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic structural diagram of a bus bar in a first viewing angle according to an embodiment of the present invention;

[0021] Figure 2 for Figure 1 A top view of

[0022] Figure 3 for Figure 1 The bus shown is a schematic structural diagram of a second viewing angle;

[0023] Figure 4 for Figure 3 A top view of

[0024] Figure 5 for Figure 1 The main view;

[0025] Figure 6 A schematic structural diagram of another bus bar in a first viewing angle according to an embodiment of the present invention;

[0026] Figure 7 for Figure 6 The main view;

[0027] Figure 8 for Figure 6 A top view of

[0028] Fig. 9 It is a structural schematic diagram of the busbar and battery cell assembly process;

[0029] Fig.10 It is a schematic diagram of the structure after the busbar and the battery cell are assembled;

[0030] Fig.11 for Fig.10A partial enlarged view of point A in the middle.

[0031] Description of reference numerals:

[0032] 1. Busbar; 11. First busbar; 12. Second busbar; 13. Pole positioning hole; 14. Pole welding hole; 15. Heat dissipation gap; 16. Reinforcement rib; 17. Raised portion; 18. Heat dissipation fin; 2. Battery cell; 21. Pole. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0034] In the battery module of the related technology, the busbars between the battery cells are stamped out of aluminum plates, and the thickness is generally 1mm, 1.2mm, 1.5mm and 2mm. The connection between the busbar and the pole of the battery cell is achieved by laser welding. In order to ensure that it has sufficient cross-sectional area for current flow, certain requirements and controls are required for the melting depth and width of the laser welding.

[0035] The maximum thickness of the existing stamped busbars can only be 2 mm. If it is too thick, it will be difficult for the laser welding head to press the busbar against the poles of two adjacent battery cells during laser welding, which will cause a gap between the busbar and the poles of the battery cells, causing laser welding to have welding quality problems such as cold welds and holes. If the thickness of the busbar exceeds 2 mm, the welding depth and width will also be difficult to control.

[0036] Therefore, in order to solve the above technical problems, the present invention provides a bus and a battery pack.

[0037] Combine the following Figures 1 to 11 , describing an embodiment of the present invention.

[0038] According to an embodiment of the present invention, in a first aspect, a busbar 1 is provided, which is a double-layer plate structure, including a first busbar 11 suitable for welding with the pole 21 of the battery cell 2 and a second busbar 12 away from the pole 21 of the battery cell 2, the thickness of the first busbar 11 is less than the thickness of the second busbar 12; the first busbar 11 is provided with two pole positioning holes 13 for positioning welding with the pole 21 of the adjacent battery cell 2; the second busbar 12 is provided with two pole welding holes 14, the size of the pole welding holes 14 is larger than the size of the pole positioning holes 13; the two pole positioning holes 13 are respectively arranged in the two pole welding holes 14; the first busbar 11 and the second busbar 12 are connected at an interval, and a heat dissipation gap 15 is formed between the plate surfaces of the first busbar 11 and the second busbar 12.

[0039] The busbar 1 provided by the present invention adopts a double-layer plate structure, which includes a first busbar 11 that is welded in contact with the pole 21 of the battery cell 2 and a second busbar 12 that is not welded to the pole 21 of the battery cell 2. Since the wall thickness and rigidity of the first busbar 11 are small, the laser welding head can easily press the busbar 1 onto the poles 21 of two adjacent battery cells 2, tightly fitting them to avoid welding problems such as cold welding or blowout holes. The wall thickness of the second busbar 12 is large, and since the busbar 1 is a double-layer structure design, the thickness of the second busbar 12 that is not in contact with the pole 21 of the battery cell 2 is not limited, which can multiply the cross-sectional area of ​​the busbar 1, and reduce the temperature rise when a large current passes through it. At the same time, a heat dissipation gap 15 is formed between the first busbar 11 and the second busbar 12. The double-layer plate structure also increases the heat dissipation area of ​​the busbar 1, preventing additional heat from being transferred to the inside of the battery cell 2, thereby avoiding affecting the cycle life of the battery cell 2. Therefore, the busbar 1 of the present invention can meet the design requirements of fast charging systems above 3C.

[0040] Specifically, in some embodiments, the busbar 1 of the double-layer structure may be an aluminum extruded profile. Of course, the busbar 1 may also be made of copper or other highly conductive materials.

[0041] The first busbar 11 is provided with two pole positioning holes 13 , which can be positioned with the poles 21 of two adjacent battery cells 2 .

[0042] The second busbar 12 is provided with two pole welding holes 14, which can avoid the pressure head of laser welding, and facilitate welding of the busbar 1 and the pole 21 of the battery cell 2. The two pole positioning holes 13 are respectively provided in the two pole welding holes 14, that is, the two pole positioning holes 13 are respectively located within the projection range of the two pole welding holes 14 along the thickness direction of the busbar 1. In some embodiments, the pole welding hole 14 and the pole positioning hole 13 are concentrically arranged.

[0043] In some embodiments, the thickness of the first busbar 11 is T1, where T1≤1.5 mm.

[0044] The busbar 1 in this embodiment has a thickness T1 of the first busbar 11 that is controlled within a range of less than 1.5 mm. The thickness is relatively small and the rigidity is low, so that the laser welding press head can press the first busbar 11 onto the pole 21 of the battery cell 2, avoiding welding problems such as cold solder joints or blown holes.

[0045] In some embodiments, the thickness of the second busbar 12 is T2, where T2 ≥ 2 mm.

[0046] The thickness of the second busbar 12 is controlled to be above 2 mm, which can improve the rigidity of the busbar 1 and can multiply the current cross-sectional area of ​​the busbar 1, thereby reducing the temperature rise when a large current passes through it.

[0047] In some embodiments, at least one reinforcing rib 16 is disposed in the heat dissipation gap 15 , and the reinforcing rib 16 is connected between the first busbar 11 and the second busbar 12 .

[0048] By providing at least one reinforcing rib 16 in the heat dissipation gap 15, the rigidity of the busbar 1 itself can be improved to prevent the busbar 1 from being deformed by external forces. When multiple reinforcing ribs 16 are provided, the heat dissipation gap 15 is divided into multiple cavities.

[0049] In some embodiments, a plurality of reinforcing ribs 16 are provided, the reinforcing ribs 16 extend along the width direction of the busbar 1 , and the plurality of reinforcing ribs 16 are spaced apart along the length direction of the busbar 1 .

[0050] In some embodiments, the first busbar 11 includes a main body and a raised portion 17 , the height of the heat dissipation gap 15 corresponding to the raised portion 17 is H1 , the height of the heat dissipation gap 15 corresponding to the main body is H2 , and H1 ≠ H2 .

[0051] In this embodiment, the first busbar 11 is provided with a raised portion 17 , which can be used to absorb the deformation caused by the expansion of the battery cell 2 during charging and discharging, reduce stress, and prevent fatigue cracking of the busbar 1 .

[0052] In some embodiments, the raised portion 17 is a protrusion facing away from the heat dissipation gap 15 , H1 > H2 , 2 mm ≤ H2 ≤ 10 mm.

[0053] The raised portion 17 may be raised toward the heat dissipation gap 15 or away from the heat dissipation gap 15. In this embodiment, the height of the heat dissipation gap 15 corresponding to the raised portion 17 is greater than the height of the heat dissipation gap 15 corresponding to the main body. The height H2 of the heat dissipation gap 15 corresponding to the main body is controlled within the range of 2 mm to 10 mm, which can improve the heat dissipation effect of the bus 1 and ensure that the bus 1 does not occupy too much space in the thickness direction to ensure the capacity of the battery pack.

[0054] In some embodiments, the raised portion 17 is located in the middle of the busbar 1 , and at least two raised portions 17 are provided. The raised portions 17 extend to both sides of the busbar 1 along the width direction of the busbar 1 , and the reinforcing rib 16 is located between two adjacent raised portions 17 .

[0055] By arranging the raised portion 17 in the middle of the busbar 1 and locating the reinforcing rib 16 between the two raised portions 17 , the busbar 1 can be improved in its ability to resist deformation and reduce stress, thereby preventing the busbar 1 from fatigue cracking.

[0056] In some embodiments, a surface of the second busbar 12 away from the heat dissipation gap 15 is provided with a plurality of heat dissipation fins 18 .

[0057] In this embodiment, by providing heat dissipation fins 18 on the surface of the second busbar 12 away from the heat dissipation gap 15, the heat dissipation area of ​​the busbar 1 can be further increased, preventing additional heat from being transferred to the interior of the battery cell 2 and affecting the cycle life of the battery cell 2, thereby meeting the design requirements of fast charging systems above 3C.

[0058] In some embodiments, the height of the heat dissipation fins 18 is H3, and 1 mm ≤ H3 ≤ 10 mm.

[0059] By controlling the height H3 of the heat dissipation fins 18 within a range of 1 mm to 10 mm, the manufacturing cost of the busbar 1 can be controlled while ensuring the heat dissipation effect.

[0060] In some embodiments, the heat dissipation fin 18 is located between two pole welding holes 14 .

[0061] Since the area between the two pole welding holes 14 is relatively large, the heat dissipation fins 18 are arranged between the two pole welding holes 14 , so that the structural design of the busbar 1 is more reasonable.

[0062] According to an embodiment of the present invention, in a second aspect, a battery pack is further provided, comprising a plurality of battery cells 2 arranged side by side, and a bus 1 in the above embodiment, wherein the bus 1 is arranged on the side where the pole 21 of the battery cell 2 is located, and the two pole positioning holes 13 of the first bus plate 11 of the bus 1 are respectively welded to the poles 21 of two adjacent battery cells 2 with different polarities to connect the two battery cells 2 in series.

[0063] Since the battery pack includes the bus bar 1 and has the same effect as the bus bar 1 , it will not be described in detail here.

[0064] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A busbar, characterized in that: The busbar is a double-layer plate structure, including a first busbar suitable for welding with the pole of the battery cell and a second busbar away from the pole of the battery cell, and the thickness of the first busbar is less than the thickness of the second busbar; The first busbar is provided with two pole positioning holes for positioning welding with poles of adjacent battery cells; The second busbar is provided with two pole welding holes, the size of the pole welding holes is larger than the size of the pole positioning holes; the two pole positioning holes are respectively correspondingly arranged in the two pole welding holes; The first busbar and the second busbar are connected to each other in a spaced relationship, and a heat dissipation gap is formed between the board surfaces of the first busbar and the second busbar.

2. The busbar according to claim 1, characterized in that: The thickness of the first busbar is T1, where T1≤1.5 mm.

3. The busbar according to claim 1 or 2, characterized in that: The thickness of the second busbar is T2, where T2≥2 mm.

4. The busbar according to claim 1 or 2, characterized in that: At least one reinforcing rib is provided in the heat dissipation gap, and the reinforcing rib is connected between the first busbar and the second busbar.

5. The busbar according to claim 4, characterized in that: The first busbar includes a main body and a raised portion. The height of the heat dissipation gap corresponding to the raised portion is H1, and the height of the heat dissipation gap corresponding to the main body is H2, where H1≠H2.

6. The busbar according to claim 5, characterized in that: The raised portion is a protrusion facing in a direction away from the heat dissipation gap, H1>H2, 2mm≤H2≤10mm.

7. The busbar according to claim 5, characterized in that: The raised portion is located in the middle of the busbar, and at least two of them are provided. The raised portion extends to both sides of the busbar along the width direction of the busbar, and the reinforcing rib is located between two adjacent raised portions.

8. The busbar according to claim 1 or 2, characterized in that: A plurality of heat dissipation fins are disposed on a surface of the second busbar away from the heat dissipation gap.

9. The busbar according to claim 8, characterized in that: The height of the heat dissipation fin is H3, 1mm≤H3≤10mm.

10. A battery pack, characterized in that: include: Multiple batteries are arranged side by side. The busbar according to any one of claims 1 to 9, wherein the busbar is arranged on the side where the pole of the battery cell is located, and the two pole positioning holes of the first bus plate of the busbar are respectively welded to the poles of different polarities of two adjacent battery cells to connect the two battery cells in series.

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