Busbar, battery module and busbar welding process
By designing the first groove, welding area and raised structure on the busbar of the battery module, the seal ring failure problem caused by excessive welding heat in the battery module is solved, and a stronger welding strength and a lower seal ring failure probability are achieved.
Patent Information
- Application Number
- CN202510344394.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-06-20
AI Technical Summary
In the battery module, as the capacity of the battery cell increases, the bus thickness also increases, resulting in an increase in welding heat, which can easily lead to failure of the seal ring, which in turn causes liquid leakage and insulation failure of the battery cell.
A busbar is designed, and when welding with the pole column, the welding area is arranged on the first side of the busbar and the welding area is arranged on the second side, so that the welding area is opposite to the groove bottom of the first groove, forming a first gap to reduce heat conduction, and further enlarge the welding depth and reduce heat transfer through the design of the projection structure and the second groove.
It effectively reduces the heat transferred by the busbar to the pole column, reduces the chance of sealing ring failure, and increases the welding strength between the busbar and the pole column, so that the busbar can be suitable for large-capacity battery cells.
Smart Images
Figure CN120184530A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of batteries, and in particular to a bus bar, a battery module and a bus bar welding process. Background Art
[0002] In a battery module, battery cells are often connected in series and parallel through a bus bar. The bus bar is fixed on the pole of the battery cell through a laser welding process to achieve the conductive connection between the bus bar and the battery cell.
[0003] In order to meet the charging and discharging requirements of large current in the battery module, the capacity of the battery cell is getting larger and larger, and the thickness of the bus bar is also getting thicker. After increasing the thickness of the bus bar, it is necessary to increase the laser welding energy, which will increase the welding heat generated during laser welding.
[0004] The pole and the battery cover plate are often sealed and insulated through a rubber sealing ring. When welding the pole and the bus bar, if the welding heat is too high, it is easy to cause the rubber sealing ring to fail, and then lead to problems such as battery cell leakage and insulation failure.
[0005] Therefore, it is urgent to propose a bus bar, a battery module and a bus bar welding process to solve the above technical problems. Summary of the Invention
[0006] The first object of the present invention is to provide a bus bar, which can reduce the heat transferred from the bus bar to the pole when welded to the pole, and can also improve the welding strength between the bus bar and the pole.
[0007] To achieve this purpose, the present invention adopts the following technical solutions:
[0008] A bus bar for welding with the pole of a battery. The bus bar includes a first side and a second side arranged opposite to each other. The first side is configured to face the pole, and a first groove is provided on the first side. A welding area is provided on the second side, and the welding area is opposite to the bottom of the first groove. The welding equipment can weld the bus bar and the pole through the welding area.
[0009] Optionally, the first groove is an open groove.
[0010] Optionally, the width L at the notch of the first groove is 1.8 mm - 5.2 mm;
[0011] And / or, the depth H of the first groove is 0.08 mm - 0.65 mm.
[0012] Optionally, a second groove is provided in the welding area, and the bottom of the second groove is arranged opposite to the bottom of the first groove. The welding equipment can weld in the second groove.
[0013] Optionally, the width of the second groove is K;
[0014] K ≥ 1 mm;
[0015] and / or, K ≤ 4 mm.
[0016] Optionally, the inner wall of the second groove is perpendicular to the bottom of the second groove.
[0017] Optionally, a convex structure is further provided on the first side, and the convex structure is configured to be clamped between the surface of the first side and the pole column.
[0018] Optionally, the convex structure includes a plurality of protruding portions arranged at intervals, and along the extending direction of the first groove, the plurality of protruding portions are distributed on both sides of the first groove.
[0019] Optionally, the positive projection of the side of the protruding portion facing away from the second side on the surface of the second side is dot-shaped or linear.
[0020] Optionally, the size T of the convex structure protruding from the surface of the first side is 0.05 mm - 0.55 mm.
[0021] The second object of the present invention is to provide a battery module, which has a lower probability of battery cell leakage and insulation failure problems, and has a larger charge and discharge current.
[0022] To achieve this purpose, the present invention adopts the following technical solutions:
[0023] The battery module includes the above-mentioned busbar.
[0024] The third object of the present invention is to provide a busbar welding process, when welding the busbar and the pole column, the heat transferred from the busbar to the pole column is less, and the welding penetration depth between the busbar and the pole column is deeper.
[0025] To achieve this purpose, the present invention adopts the following technical solutions:
[0026] The busbar welding process includes the following steps:
[0027] S1. Prepare a first groove on the first side of the busbar, delimit a welding area on the second side of the busbar, and make the bottom of the first groove face the welding area;
[0028] S2. Orient the first side towards the pole column and place the busbar on the pole column;
[0029] S3. Perform laser welding in the welding area to fix the busbar on the pole column.
[0030] The beneficial effects of the present invention:
[0031] The busbar provided by the present invention is provided with a first groove on the first side facing the pole column, and a welding area is provided on the second side opposite to the first side, so that the welding area is arranged directly opposite to the bottom of the first groove. When welding the busbar and the pole column, the design of the first groove forms a first gap between the busbar and the pole column, which can reduce the heat conduction between the busbar and the pole column. It can be seen that under the same laser welding energy, this busbar can reduce the welding heat transferred from the busbar to the pole column, and further reduce the heat transferred from the pole column to the sealing ring, reducing the probability of sealing ring failure.
[0032] Secondly, since the heat transferred from the busbar to the pole column is reduced, when welding in the welding area, the welding heat will be concentrated in the welding area first, making it easier for the busbar in the welding area to be penetrated. After the welding area is penetrated, due to the keyhole effect of laser welding, the welding laser is more likely to act on the pole column, which can increase the penetration depth on the pole column and improve the welding strength between the pole column and the busbar. It can be seen that when welding this busbar and the pole column, although the heat received by the pole column is reduced, the welding strength between the pole column and the busbar is improved, increasing the feasibility of increasing the thickness of the busbar, making this busbar applicable to large-capacity battery cells. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 is the first schematic structural diagram of the busbar provided by Embodiment 1 of the present invention;
[0034] Figure 2 is the second schematic structural diagram of the busbar provided by Embodiment 1 of the present invention;
[0035] Figure 3 is the cross-sectional structural diagram of the busbar and the pole column before welding provided by Embodiment 1 of the present invention;
[0036] Figure 4 is the cross-sectional structural diagram of the busbar and the pole column after welding provided by Embodiment 1 of the present invention;
[0037] Figure 5 is the metallographic diagram of the busbar and the pole column after welding in the prior art;
[0038] Figure 6 is the metallographic diagram of the busbar and the pole column after welding provided by Embodiment 1 of the present invention (when the size of the protruding part protruding from the first side surface is 0.3 mm);
[0039] Figure 7 is the metallographic diagram of the busbar and the pole column after welding when the size of the protruding part protruding from the first side surface is 0.6 mm;
[0040] Figure 8 is the metallographic diagram of the busbar and the pole column after welding under two working conditions of not opening the second groove and opening the second groove;
[0041] Figure 9 is a coordinate graph of the width of the second groove and the minimum thickness of the bus bar;
[0042] Figure 10 is a schematic structural diagram of the battery module provided in the first embodiment of the present invention;
[0043] Figure 11 is Figure 3 a partial enlarged view of part A in
[0044] Figure 12 is a schematic structural diagram of the bus bar provided in the second embodiment of the present invention.
[0045] In the figure:
[0046] 1. Bus bar; 2. Battery cell; 21. Terminal; 11. First side; 111. First groove; 112. Protrusion structure; 1121. Protruding part; 12. Second side; 121. Welding area; 1211. Second groove; 13. First gap; 14. Second gap; 15. Connecting gap; 16. Molten pool. Detailed implementation manners
[0047] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention are shown in the drawings, rather than all structures.
[0048] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.
[0049] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above and over", and "on the top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below and under", and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.
[0050] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "right", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.
[0051] Embodiment 1
[0052] This embodiment provides a bus bar. When it is welded to the pole column, it can reduce the heat transferred from the bus bar to the pole column, and can also improve the welding strength between the bus bar and the pole column.
[0053] Specifically, as Figures 1 to 3 shown, this bus bar is used for welding with the pole column 21 of the battery. The bus bar includes a first side 11 and a second side 12 which are oppositely arranged. The first side 11 is configured to face the pole column 21. The first side 11 is provided with a first groove 111, and the second side 12 is provided with a welding area 121. The welding area 121 is directly opposite to the bottom of the first groove 111. The welding equipment can weld the bus bar and the pole column 21 through the welding area 121.
[0054] By providing the first groove 111 on the first side 11 facing the pole column 21 and providing the welding area 121 on the second side 12 opposite to the first side 11, and making the welding area 121 directly opposite to the bottom of the first groove 111, when welding the bus bar and the pole column 21, the design of the first groove 111 forms a first gap 13 between the bus bar and the pole column 21, thereby being able to reduce the heat conduction amount between the bus bar and the pole column 21. It can be seen that under the same laser welding energy, this bus bar can reduce the welding heat transferred from the bus bar to the pole column 21, and further reduce the heat transferred from the pole column 21 to the sealing ring, reducing the probability of the sealing ring failure.
[0055] On the other hand, since the heat transferred from the bus bar to the pole column 21 is reduced, when welding in the welding area 121, the welding heat will first concentrate in the welding area 121, making the bus bar in the welding area 121 easier to be welded through. After the welding area 121 is welded through, due to the keyhole effect of laser welding, the welding laser is more likely to act on the pole column 21, thereby being able to increase the penetration depth on the pole column 21 and improve the welding strength between the pole column 21 and the bus bar. It can be seen that when welding this bus bar and the pole column 21, although the heat received by the pole column 21 is reduced, the welding strength between the pole column 21 and the bus bar is improved, improving the feasibility of increasing the thickness of the bus bar, so that this bus bar can be applied to large-capacity battery cells 2.
[0056] On the other hand, in the current art, it is generally believed that when welding the bus bar and the pole 21, the bus bar should be closely attached to the pole 21 to eliminate the gap therebetween. Because when there is a gap between them, the molten pool 16 is likely to flow towards the gap, making the flow direction of the molten pool 16 uncontrollable. Eventually, due to the fact that the molten pool 16 cannot be concentrated at the welding position, welding defects will occur.
[0057] In this embodiment, a first groove 111 is provided on the first side 11 of the bus bar (i.e., the side of the bus bar facing the pole 21). After placing the bus bar on the pole 21, a first gap 13 is formed between the first side 11 and the pole 21, and the welding area 121 on the second side 12 of the bus bar faces the bottom of the first groove 111, that is, the welding area 121 faces the first gap 13. Therefore, when the welding equipment welds at the welding area 121, the molten pool 16 can flow along the extending direction of the first groove 111. That is to say, the molten pool 16 can flow along the extending direction of the first gap 13 without flowing to other areas. It can be seen that this design of making the bottom of the first groove 111 face the welding area 121 improves the controllability of the flow direction of the molten pool 16, enables the molten pool 16 to be concentrated at the first gap 13, and solves the problem of poor welding between the bus bar and the pole 21.
[0058] Currently, in the art, it is generally believed that the contact area between the bus bar and the pole 21 is the current-carrying area therebetween. However, in fact, the bus bar is usually made of aluminum material. After the battery module is used for a period of time, a dense aluminum oxide film layer will be formed on the surface of the bus bar. Aluminum oxide is an insulating ceramic material, which greatly reduces the conductivity of the bonding surface between the bus bar and the pole 21. Eventually, the bus bar and the pole 21 can only conduct electricity through the weld seam therebetween. Therefore, the weld width at the bonding position between the bus bar and the pole 21 is the key to determining the current-carrying capacity therebetween. That is to say, ultimately, the melt width at the bonding position between the bus bar and the pole 21 determines the current-carrying capacity between the bus bar and the pole 21.
[0059] To increase the above-mentioned melt width, as Figure 3 、 Figure 4 and Figure 11 shown, the first groove 111 is an open groove, that is, the width L at the notch of the first groove 111 is the largest. When welding the bus bar and the pole 21, the molten pool 16 fills the first gap 13 and infiltrates into the pole 21 along the D1 direction. Eventually, a structure is formed where the width of the molten pool 16 at the notch of the first groove 111 is the largest, that is, the width of the molten pool 16 at the bonding position between the first side 11 and the pole 21 is the largest. When the molten pool 16 forms a weld seam, the weld width at the bonding position between the first side 11 and the pole 21 is the largest, thereby achieving the effect of improving the current-carrying capacity between the bus bar and the pole 21.
[0060] Optionally, as Figure 1 、Figure 3 and Figure 4 As shown in Figure 4 , the first side 11 is further provided with a convex structure 112, which is configured to be clamped between the surface of the first side 11 and the pole 21. The convex structure 112 forms a second gap 14 between the first side 11 and the pole 21, and significantly reduces the contact area between the bus bar and the pole 21. When welding the bus bar and the pole 21, the welding heat transferred from the bus bar to the pole 21 can be significantly reduced, thereby reducing the heat transferred from the pole 21 to the sealing ring, achieving the effect of significantly reducing the failure probability of the sealing ring.
[0061] Furthermore, the convex structure 112 includes a plurality of protruding portions 1121 arranged at intervals, thereby forming a plurality of mutually spaced second gaps 14 between the bus bar and the pole 21. Along the extending direction of the first groove 111, the plurality of protruding portions 1121 are distributed on both sides of the first groove 111, so that the first gap 13 can communicate with the adjacent second gap 14 (hereinafter referred to as the communicating gap 15 for short). Therefore, during welding, the molten pool 16 in the first gap 13 can slightly flow towards the communicating gap 15, and the protruding portions 1121 adjacent to the first gap 13 can block the molten pool 16 in the communicating gap 15 from flowing into other second gaps 14 (that is, can retain the molten pool 16 in the first gap 13 and the communicating gap 15). It can be seen that this design can not only further increase the weld width at the contact position between the bus bar and the pole 21, but also achieve controllability of the flow direction of the molten pool 16. It should be noted that in this embodiment, the first groove 111 is circular. The distribution of the plurality of protruding portions 1121 on both sides of the first groove 111 means that the plurality of protruding portions 1121 are distributed on the inner and outer sides of the first groove 111. Of course, in other embodiments, the first groove 111 can also be linear or wavy. At this time, the distribution of the plurality of protruding portions 1121 on both sides of the first groove 111 means that the plurality of protruding portions 1121 are distributed on the opposite sides of the first groove 111; the first groove 111 can also be square or triangular, etc. At this time, the distribution of the plurality of protruding portions 1121 on both sides of the first groove 111 means that the plurality of protruding portions 1121 are distributed on the inner and outer sides of the first groove 111. It should be noted that the number of the protruding portions 1121 can be ten, twenty, or forty, etc., as long as the plurality of protruding portions 1121 can stably support the bus bar.
[0062] Optionally, the orthographic projection of the side of the protruding portion 1121 facing away from the second side 12 on the surface of the second side 12 is dot-shaped, such as Figure 1As shown in the figure, the protruding portion 1121 is generally a pyramid-shaped structure, and the sharp angle of the pyramid-shaped protruding portion 1121 faces away from the first side 11, so that the sharp angle of the pyramid-shaped protruding portion 1121 abuts against the terminal post 21. Compared with the prior art in which the bus bar is in close contact with the terminal post 21 (at this time, the bus bar and the terminal post 21 are in surface contact), in this embodiment, a point-contact form between the bus bar and the terminal post 21 is achieved, which can not only greatly reduce the heat transfer amount between the bus bar and the terminal post 21, but also greatly reduce the heat transfer speed between the bus bar and the terminal post 21, thus solving the problem of heat-induced failure of the sealing ring. It should be noted that in other embodiments, the protruding structure 112 can also be an annular protrusion. At this time, although the bus bar and the terminal post 21 are in surface contact, compared with the close contact between the bus bar and the terminal post 21, the design of the protruding structure 112 can still reduce the contact area between the bus bar and the terminal post 21 and form a second gap 14 between the bus bar and the terminal post 21.
[0063] Furthermore, as Figure 11 shown, the size T of the protruding portion 1121 (i.e., the protruding structure 112) protruding from the surface of the first side 11 is 0.05 mm - 0.55 mm. Exemplarily, the size T of the protruding portion 1121 protruding from the surface of the first side 11 can be 0.05 mm, 0.1 mm, 0.25 mm, 0.3 mm, 0.5 mm or 0.55 mm, etc., and T is preferably 0.1 mm - 0.5 mm. If the size T of the protruding portion 1121 protruding from the surface of the first side 11 is less than 0.05 mm, the second gap 14 is too small, which will greatly reduce the molten pool 16 flowing into the communication gap 15 from the first gap 13, and is not conducive to increasing the weld width at the contact position between the bus bar and the terminal post 21. If the size T of the protruding portion 1121 protruding from the surface of the first side 11 is greater than 0.55 mm, the second gap 14 is too large, which will greatly shorten the weld depth and is not conducive to improving the welding stability between the bus bar and the terminal post 21.
[0064] As Figure 5 shown, when the bus bar is in close contact with the terminal post 21, that is, when there is no gap between the bus bar and the terminal post 21, the maximum weld width between the bus bar and the terminal post 21 is 0.86 mm, and the maximum weld depth is 0.75 mm. As Figure 6 shown, when the size of the protruding portion 1121 protruding from the surface of the first side 11 is 0.3 mm, the maximum weld width between the bus bar and the terminal post 21 is 1.05 mm, and the maximum weld depth is 0.95 mm. It can be seen that when there is a gap between the bus bar and the terminal post 21, both the maximum weld width and the maximum weld depth are significantly increased. As Figure 7As shown, when the size of the protruding portion 1121 protruding from the first side 11 surface is 0.6 mm, the maximum fusion width between the bus bar and the pole 21 is 1.61 mm, and the maximum fusion depth is 0.72 mm. It can be seen that when the size of the protruding portion 1121 protruding from the first side 11 surface is too large, although the maximum fusion width can be increased, the maximum fusion depth is significantly shortened, and even the maximum fusion depth at this time is less than 0.75 mm (the maximum fusion depth when there is no gap between the bus bar and the pole 21).
[0065] Optionally, as Figures 2 to 4 shown, the welding area 121 is provided with a second groove 1211. The bottom of the second groove 1211 is arranged opposite to the bottom of the first groove 111, and the extension trajectory of the second groove 1211 is the same as that of the first groove 111. The welding equipment can weld in the second groove 1211. Designing the second groove 1211 can achieve the effect of further increasing the welding fusion depth. Specifically, under the same laser welding parameters, if there is no second groove 1211, the molten pool 16 is likely to spread out and flow around from the welding position, causing the welding heat to disperse on the second side 12; after the second groove 1211 is opened on the second side 12, at the initial stage of welding, the inner wall and the bottom of the second groove 1211 are gradually melted to form the molten pool 16. The molten pool 16 is restricted in the second groove 1211, which can make the welding heat transfer more to the first side 11 and the pole 21, achieving the effect of further increasing the fusion depth. Figure 8 The metallographic structure comparison diagram is shown. The left side is the weld metallographic structure when the second groove 1211 is not opened on the second side 12, and the right side is the metallographic structure when the second groove 1211 is opened on the second side 12. It can be seen that the fusion depth when the second groove 1211 is provided on the second side 12 is significantly greater than that when there is no second groove 1211.
[0066] Furthermore, the inner wall of the second groove 1211 is perpendicular to the bottom of the second groove 1211. Therefore, the inner wall of the second groove 1211 can guide the molten pool 16 in the second groove 1211, guiding the molten pool 16 to flow towards the first side 11 and the pole 21, and preventing the molten pool 16 from spreading around on the second side 12 surface due to overflowing the second groove 1211. It can be seen that this design achieves the effect of further improving the transfer of welding heat to the first side 11 and the pole 21, and thus can further increase the fusion depth. In addition, this design can reduce the preparation difficulty of the second groove 1211. A common milling cutter in the field can be used to mill the second groove 1211 on the second side 12, which has the effects of reducing the production difficulty and the production cost.
[0067] Optionally, as Figure 3As shown, the width of the second groove 1211 is K, where K ≤ 4 mm. Exemplarily, K can be 4 mm, 3 mm, 3.5 mm, 2.5 mm, etc. Since the second groove 1211 is disposed opposite to the first groove 111, the position where the second groove 1211 is provided is the minimum thickness position of the bus bar. After welding, the height of the solder in the second groove 1211 determines the size of the minimum thickness of the bus bar. When K ≤ 4 mm, the welding laser will be reflected multiple times at multiple positions on the inner wall and the bottom of the second groove 1211, causing the edge area of the second groove 1211 on the second side 12 surface to melt. The molten aluminum liquid fills into the second groove 1211, thereby increasing the height of the solder in the second groove 1211 to increase the minimum thickness of the bus bar and improving the overcurrent capacity of the minimum thickness area of the bus bar. If K is greater than 4 mm, the welding laser will directly act on the bottom of the second groove 1211 and will not be reflected multiple times in the second groove 1211. Furthermore, the edge area of the second groove 1211 on the second side 12 surface will not undergo a melting phenomenon, and the effect of increasing the minimum thickness of the bus bar cannot be achieved.
[0068] Figure 9 The coordinate diagram showing the width of the second groove 1211 (i.e., the value of K) and the minimum thickness of the bus bar is presented. When the width of the second groove 1211 is 1 mm, after the bus bar is welded to the pole 21, the minimum thickness of the bus bar is 2.509 mm, and when the width of the second groove 1211 is 1 mm, the minimum thickness of the bus bar is the largest. When the width of the second groove 1211 increases, the minimum thickness of the bus bar gradually decreases. When the width of the second groove 1211 reaches 3 mm, the minimum thickness of the bus bar is 1.43 mm. Usually, in actual production, making the width of the second groove 1211 be 1 mm can meet the conventional use requirements. However, if it is necessary to increase the weld width, the width of the second groove 1211 can be appropriately increased to meet the welding of laser welding equipment with a larger spot size, but the maximum width of the second groove 1211 should not exceed 4 mm, otherwise the effect of increasing the minimum thickness of the bus bar cannot be achieved.
[0069] Optionally, K ≥ 1 mm. Exemplarily, K can be 1 mm, 1.5 mm, 2 mm, etc. When K is less than 1 mm, it is necessary to make the laser welding equipment have very high welding trajectory accuracy. Otherwise, the welding laser cannot enter the second groove 1211 and will instead irradiate the surface of the second side 12, greatly reducing the welding accuracy and increasing the welding cost. In this embodiment, 1 mm ≤ K ≤ 4 mm. Of course, in other implementation schemes, either K ≤ 4 mm or K ≥ 1 mm can be selected according to the actual production and use conditions.
[0070] Optionally, as Figure 11As shown, the width L at the notch of the first groove 111 is 1.8 mm - 5.2 mm. Exemplarily, the width L at the notch of the first groove 111 can be 1.8 mm, 2 mm, 3 mm, 4.5 mm, 5 mm, 5.2 mm, etc. Among them, it is preferably 2 mm - 5 mm for L. If the width L at the notch of the first groove 111 is less than 1.8 mm, the maximum fusion width between the bus bar and the pole 21 cannot meet the process requirements; if the width L at the notch of the first groove 111 is greater than 5.2 mm, too much aluminum liquid in the second groove 1211 will flow into the second gap 14, which will ultimately reduce the minimum thickness of the bus bar, and then reduce the overcurrent capacity at the position of the minimum thickness of the bus bar.
[0071] Optionally, the depth H of the first groove 111 is 0.08 mm - 0.65 mm. Exemplarily, the depth H of the first groove 111 can be 0.08 mm, 0.1 mm, 0.25 mm, 0.3 mm, 0.6 mm, 0.65 mm, etc. Among them, it is preferably 0.1 mm - 0.6 mm for H. If the depth H of the first groove 111 is less than 0.08 mm, with the same laser welding energy, the penetration depth will be shortened; if the depth H of the first groove 111 is greater than 0.65 mm, the volume of aluminum material will be reduced, and then the volume of the molten pool 16 will be reduced, which will shorten the penetration depth and reduce the fusion width.
[0072] In this embodiment, the width L at the notch of the first groove 111 is 1.8 mm - 5.2 mm, and the depth H of the first groove 111 is 0.08 mm - 0.65 mm. Of course, in other embodiments, either the width range at the notch of the first groove 111 or the depth range of the first groove 111 can be restricted.
[0073] This embodiment also provides a battery module, as Figure 10 shown, the battery module includes a plurality of battery cells 2 and the above-mentioned bus bar 1. The first side 11 of the bus bar 1 is fixedly connected to the pole 21 of the battery cell 2 through a laser welding process to achieve the series connection and / or parallel connection of multiple battery cells 2. The battery module adopts the above-mentioned bus bar 1. When welding the bus bar 1 and the pole 21, less welding energy can be used to improve the welding strength between the two, so the probability of liquid leakage and insulation failure of the battery cell 2 caused by the heat of the sealing ring sleeved on the pole 21 can be reduced, and when the charge and discharge current of the battery module is increased and the thickness of the bus bar 1 is increased, there is still a high welding strength between the bus bar 1 and the pole 21.
[0074] This embodiment also provides a bus bar welding process, including the following steps:
[0075] S1. Prepare a first groove 111 on the first side 11 of the busbar, demarcate a welding area 121 on the second side 12 of the busbar, and make the bottom of the first groove 111 face the welding area 121;
[0076] S2. Orient the first side 11 towards the pole 21 and place the busbar on the pole 21;
[0077] S3. Perform laser welding in the welding area 121 to fix the busbar on the pole 21.
[0078] The first groove 111 prepared on the first side 11 forms a first gap 13 between the busbar and the pole 21. Further, during laser welding, the heat conduction between the busbar and the pole 21 can be reduced, and the probability of seal ring failure can be decreased. Also, since the heat transferred from the busbar to the pole 21 is reduced, when welding in the welding area 121, the welding heat will first concentrate in the welding area 121, making it easier for the busbar in the welding area 121 to be penetrated. After the welding area 121 is penetrated, due to the keyhole effect of laser welding, the welding laser can more easily act on the pole 21, thereby increasing the penetration depth on the pole 21 and improving the welding strength between the pole 21 and the busbar. In addition, the design of making the bottom of the first groove 111 face the welding area 121 can also improve the controllability of the flow direction of the molten pool 16, making the molten pool 16 concentrate at the first gap 13, solving the problem of poor welding between the busbar and the pole 21.
[0079] Further, in step S1, mill a second groove 1211 in the welding area 121, make the bottom of the second groove 1211 face the bottom of the first groove 111, and make the extension trajectory of the second groove 1211 the same as that of the first groove 111. In step S3, perform laser welding in the second groove 1211 to further increase the welding penetration depth.
[0080] Further, in step S1, prepare a raised structure 112 on the first side 11 by embossing. In step S2, when placing the busbar on the pole 21, make the raised structure 112 support between the busbar and the pole 21, so as to greatly reduce the contact area between the busbar and the pole 21. When welding the busbar and the pole 21, the welding heat transferred from the busbar to the pole 21 can be greatly reduced, and further the heat transferred from the pole 21 to the seal ring can be reduced, achieving the effect of greatly reducing the probability of seal ring failure.
[0081] Embodiment 2
[0082] This embodiment provides a busbar. The following mainly describes the differences between this embodiment and the previous embodiments, and the same parts will not be elaborated.
[0083] The positive projection of the side of the protruding portion 1121 facing away from the second side 12 on the surface of the second side 12 is linear, such as Figure 12As shown, the protrusion 1121 is generally in the shape of a rice grain, and the long axis of the rice-grain-shaped protrusion 1121 is parallel to the surface of the first side 11. Thus, a line-contact form between the bus bar and the pole 21 can be achieved, which can not only greatly reduce the heat transfer amount between the bus bar and the pole 21, but also greatly reduce the heat transfer speed between the bus bar and the pole 21, solving the problem of heat-induced failure of the sealing ring.
[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the embodiments of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.
Claims
1. A busbar, which is used for welding with a battery pole, characterized in that: The busbar comprises a first side (11) and a second side (12) which are arranged opposite to each other, the first side (11) being configured to be arranged toward the pole (21), the first side (11) being provided with a first groove (111), the second side (12) being provided with a welding area (121), the welding area (121) being directly opposite to the bottom of the first groove (111), and a welding device can weld the busbar and the pole (21) through the welding area (121).
2. The busbar according to claim 1, characterized in that: The first groove (111) is an open groove.
3. The busbar according to claim 1, characterized in that: The width L of the first groove (111) at the notch is 1.8 mm to 5.2 mm; And / or, the depth H of the first groove (111) is 0.08 mm-0.65 mm.
4. The busbar according to any one of claims 1 to 3, characterized in that: The welding area (121) is provided with a second groove (1211), the groove bottom of the second groove (1211) is arranged opposite to the groove bottom of the first groove (111), and the welding equipment can weld in the second groove (1211).
5. The busbar according to claim 4, characterized in that: The width of the second groove (1211) is K; K≥1mm; And / or, K≤4mm.
6. The busbar according to claim 4, characterized in that: The inner wall of the second groove (1211) is perpendicular to the bottom of the second groove (1211).
7. The busbar according to any one of claims 1 to 3, characterized in that: The first side (11) is further provided with a protruding structure (112), and the protruding structure (112) is configured to be sandwiched between the surface of the first side (11) and the pole (21).
8. The busbar according to claim 7, characterized in that: The protruding structure (112) comprises a plurality of protruding portions (1121) arranged at intervals, and along the extension direction of the first groove (111), the plurality of protruding portions (1121) are distributed on both sides of the first groove (111).
9. The busbar according to claim 8, characterized in that: The orthographic projection of the side of the protrusion (1121) facing away from the second side (12) on the surface of the second side (12) is in the shape of a point or a line.
10. The busbar according to claim 7, characterized in that: The dimension T of the protruding structure (112) protruding from the surface of the first side (11) is 0.05 mm-0.55 mm.
11. A battery module, characterized in that: Comprising the busbar (1) as claimed in any one of claims 1 to 10.
12. A busbar welding process, characterized in that: The following steps are involved: S1. Preparing a first groove (111) on the first side (11) of the busbar (1), defining a welding area (121) on the second side (12) of the busbar (1), so that the bottom of the first groove (111) faces the welding area (121); S2, facing the first side (11) toward the pole (21), and placing the busbar (1) on the pole (21); S3, performing laser welding in the welding area (121) to fix the busbar (1) on the pole (21).