Busbar and battery pack

Abstract

The application relates to the technical field of batteries and discloses a busbar and a battery pack. The busbar is a double-layer plate structure and comprises a first busbar plate and a second busbar plate, the thickness of the first busbar plate is smaller than that of the second busbar plate; the first busbar plate is provided with two pole post positioning holes; the second busbar plate is provided with two pole post welding holes, the size of the pole post welding holes is larger than that of the pole post positioning holes; the two pole post positioning holes are correspondingly arranged in the two pole post welding holes; the first busbar plate and the second busbar plate are connected at intervals, and a heat dissipation gap is formed between the plate surfaces of the first busbar plate and the second busbar plate. The busbar provided by the application adopts a double-layer plate structure, can avoid the welding problems of virtual welding or hole blasting, can multiply the overcurrent cross-sectional area of the busbar, has a small temperature rise when passing a large current, can prevent additional heat from being transferred to the battery cell, can affect the cycle life of the battery cell, and can meet the design requirements of a 3C or above fast-charging system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to busbars and battery packs. BACKGROUND

[0002] In the battery pack, the adjacent battery cells are welded through the busbar and the pole of the battery cell to realize the series connection between the battery cells.

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

[0004] 1. The thickness of the busbar is large, which will cause a gap between the busbar and the pole of the battery cell during laser welding, resulting in virtual welding and hole blasting welding quality problems of the laser welding.

[0005] 2. With the increasing demand for fast charging rate of electric vehicles, the charging current is also increasing. In order to reduce the temperature generated by the large current passing through the busbar, the overcurrent cross-sectional area of the busbar needs to be increased. Because the thickness of the stamping formed busbar in the prior art can only be 2mm, the overcurrent area can only be increased by increasing the width of the busbar. However, the space in the width direction of the busbar in the module is limited, and the width of the busbar cannot be increased too much. The overcurrent cross-sectional area of the busbar is small, and the temperature rise is high when passing through a large current. The high temperature will be conducted to the inside of the battery cell, causing the temperature of the battery cell to rise, affecting the cycle life of the battery cell. Therefore, the overcurrent cross-sectional area of the stamping formed busbar cannot meet the requirements of the fast charging system above 3C. SUMMARY

[0006] Therefore, the present application provides a busbar and a battery pack to solve the problems of welding quality of the busbar, limited width of the busbar, small overcurrent cross-sectional area, high temperature rise when passing through a large current, and inability to meet the requirements of the fast charging system above 3C.

[0007] In a first aspect, the present application provides a busbar, which is a double-layer plate structure, comprising a first busbar plate adapted to be welded with the pole of the battery cell and a second busbar plate away from the pole of the battery cell, the thickness of the first busbar plate being smaller than the thickness of the second busbar plate; the first busbar plate is provided with two pole positioning holes for positioning and welding with the poles of the adjacent battery cells; the second busbar plate is provided with two pole welding holes, the size of the pole welding hole being larger than the size of the pole positioning hole; the two pole positioning holes are respectively arranged in the two pole welding holes; the first busbar plate and the second busbar plate are connected at intervals, and the plate surfaces of the first busbar plate and the second busbar plate form a heat dissipation gap.

[0008] Beneficial Effects: The busbar provided by this invention adopts a double-layer plate structure, consisting of a first busbar welded to the battery cell terminals and a second busbar not welded to the battery cell terminals. Because the first busbar has a smaller wall thickness and lower rigidity, the laser welding head can easily press the busbar onto the terminals of two adjacent battery cells, ensuring a tight fit and avoiding welding problems such as incomplete soldering or pore formation. The second busbar has a larger wall thickness, and due to the double-layer structure design, the thickness of the second busbar, which is not in contact with the battery cell terminals, is not limited. This significantly increases the current-carrying cross-sectional area of ​​the busbar, resulting in a smaller temperature rise when carrying high currents. Simultaneously, a heat dissipation gap is formed between the first and second busbars, and the double-layer structure also increases the heat dissipation area of ​​the busbar, preventing additional heat from being transferred to the battery cell and affecting its cycle life. Therefore, the busbar of this invention can meet the design requirements of fast charging systems above 3C.

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

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

[0011] In one 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 one optional embodiment, the first busbar includes a 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 body portion is H2, and H1≠H2.

[0013] In one alternative embodiment, the raised portion is a protrusion facing away from the heat dissipation gap, where H1 > H2 and 2mm ≤ H2 ≤ 10mm.

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

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

[0016] In one alternative implementation, the height of the heat dissipation fins is H3, where 1mm ≤ H3 ≤ 10mm.

[0017] Secondly, the present invention also provides a battery pack, including a plurality of battery cells arranged side by side, and a busbar as described in the above technical solution. The busbar is located on the side where the terminals of the battery cells are located. The two terminal positioning holes of the first busbar plate are respectively welded to the terminals of two adjacent battery cells with opposite polarities, so as to connect the two battery cells in series.

[0018] Beneficial effects: Since the battery pack includes a busbar, it has the same effect as a busbar, which will not be elaborated here. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a busbar structure from a first-view perspective, according to an embodiment of the present invention.

[0021] Figure 2 for Figure 1 Top view;

[0022] Figure 3 for Figure 1 The diagram shown is a structural schematic of the busbar from a second-view perspective.

[0023] Figure 4 for Figure 3 Top view;

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

[0025] Figure 6 This is a schematic diagram of another busbar structure from a first-view perspective according to an embodiment of the present invention;

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

[0027] Figure 8 for Figure 6 Top view;

[0028] Figure 9 This is a structural diagram illustrating the assembly process of the busbar and battery cell.

[0029] Figure 10 This is a schematic diagram of the structure after the busbar and battery cells are assembled.

[0030] Figure 11 for Figure 10A magnified view of a portion of point A in the middle.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Busbar; 11. First busbar; 12. Second busbar; 13. Terminal positioning hole; 14. Terminal welding hole; 15. Heat dissipation gap; 16. Reinforcing rib; 17. Raised part; 18. Heat dissipation fins; 2. Battery cell; 21. Terminal. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the battery modules of related technologies, the busbars between the cells are formed by stamping aluminum plates, with standard thicknesses of 1mm, 1.2mm, 1.5mm and 2mm. The connection between the busbars and the terminals of the cells is achieved by laser welding. To ensure that the busbars have sufficient current-carrying cross-sectional area, the depth and width of the laser welding need to be subject to certain requirements and control.

[0035] The maximum thickness of existing stamped busbars can only be 2mm. If it is too thick, it will be difficult for the laser welding head to press the busbar onto the terminals of two adjacent cells during laser welding. This will result in gaps between the busbar and the terminals of the cells, causing welding quality problems such as incomplete welds and pores. If the busbar thickness exceeds 2mm, it will also be difficult to control the weld penetration and weld width.

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

[0037] The following is combined Figures 1 to 11 The following describes embodiments of the present invention.

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

[0039] The busbar 1 provided by this invention adopts a double-layer plate structure, consisting of a first busbar 11 that is welded to the terminal 21 of the battery cell 2, and a second busbar 12 that is not welded to the terminal 21 of the battery cell 2. Because the first busbar 11 has a smaller wall thickness and lower rigidity, the laser welding head can easily press the busbar 1 onto the terminal 21 of two adjacent battery cells 2, ensuring a tight fit and avoiding welding problems such as incomplete welds or pinholes. The second busbar 12 has a larger wall thickness, and because the busbar 1 has a double-layer structure design, the thickness of the second busbar 12, which is not in contact with the terminal 21 of the battery cell 2, is not limited. This can significantly increase the current-carrying cross-sectional area of ​​the busbar 1, resulting in a smaller temperature rise when carrying large currents. Meanwhile, 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 and 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 double-layer busbar 1 can be made of extruded aluminum profile. Of course, the busbar 1 can 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 the two adjacent cells 2.

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

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

[0044] In this embodiment, the thickness T1 of the first busbar 11 is controlled to be less than 1.5mm. The small thickness and low rigidity allow the laser welding head to press the first busbar 11 onto the terminal post 21 of the battery cell 2, avoiding welding problems such as incomplete soldering or bursting.

[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 2mm, which can improve the rigidity of the busbar 1 and increase the current-carrying cross-sectional area of ​​the busbar 1 by several times, resulting in a small temperature rise when carrying a large current.

[0047] In some embodiments, at least one reinforcing rib 16 is provided 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 within the heat dissipation gap 15, the rigidity of the busbar 1 itself can be improved, preventing the busbar 1 from deforming under 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 body portion 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 body portion 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, where H1 > H2 and 2mm ≤ H2 ≤ 10mm.

[0053] The raised portion 17 can protrude towards the heat dissipation gap 15 or protrude 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 portion. The height H2 of the heat dissipation gap 15 corresponding to the main body portion is controlled within the range of 2mm to 10mm, which can improve the heat dissipation effect of the busbar 1, while ensuring that the busbar 1 does not occupy too much space in the thickness direction, so as 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 are provided. The raised portion 17 extends along the width direction of the busbar 1 to both sides of the busbar 1, and the reinforcing rib 16 is located between two adjacent raised portions 17.

[0055] By placing the raised portion 17 in the middle of the busbar 1 and the reinforcing rib 16 between the two raised portions 17, the busbar 1's ability to resist deformation and reduce stress can be improved, thus preventing fatigue cracking of the busbar 1.

[0056] In some embodiments, the 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 inside of the battery cell 2 and affecting the cycle life of the battery cell 2, thus meeting the design requirements of fast charging systems above 3C.

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

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

[0060] In some embodiments, the heat dissipation fins 18 are 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 placed between the two pole welding holes 14, making the structural design of the busbar 1 more reasonable.

[0062] According to an embodiment of the present invention, in a second aspect, a battery pack is also provided, including a plurality of battery cells 2 arranged side by side, and a busbar 1 as described in the above embodiment. The busbar 1 is located on the side where the terminal posts 21 of the battery cells 2 are located. The two terminal post positioning holes 13 of the first busbar plate 11 of the busbar 1 are respectively welded to the terminal posts 21 of two adjacent battery cells 2 with opposite polarities, so as to connect the two battery cells 2 in series.

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

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

Claims

1. A busbar, characterized in that, The busbar has a double-layer plate structure, including a first busbar suitable for welding to the terminal post of the battery cell and a second busbar away from the terminal post of the battery cell. The thickness of the first busbar is less than the thickness of the second busbar. The thickness of the first busbar is T1, T1≤1.5mm; the thickness of the second busbar is T2, T2≥2mm. The first busbar is provided with two electrode positioning holes for positioning and welding with the electrode posts of adjacent battery cells. The second busbar is provided with two electrode welding holes, the size of which is larger than the size of the electrode positioning hole; the two electrode positioning holes are respectively provided in the two electrode welding holes; The first busbar and the second busbar are connected at intervals, and a heat dissipation gap is formed between the surfaces of the first busbar and the second busbar; 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; The first busbar includes a body and a raised portion. The raised portion is a protrusion facing away from the heat dissipation gap. 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 body is H2. H1 > H2, and 2mm ≤ H2 ≤ 10mm.

2. The busbar according to claim 1, 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 along the width direction of the busbar to both sides of the busbar, and the reinforcing rib is located between two adjacent raised portions.

3. The busbar according to claim 1, characterized in that, The surface of the second busbar away from the heat dissipation gap is provided with a number of heat dissipation fins.

4. The busbar according to claim 3, characterized in that, The height of the heat dissipation fins is H3, where 1mm ≤ H3 ≤ 10mm.

5. A battery pack, characterized in that, include: Multiple battery cells arranged side by side, The busbar according to any one of claims 1 to 4, wherein the busbar is disposed on the side where the terminal post of the battery cell is located, and the two terminal post positioning holes of the first busbar plate of the busbar are respectively welded to the terminal posts of two adjacent battery cells with opposite polarities, so as to connect the two battery cells in series.

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