Busbar and welding method thereof, battery pack

Abstract

The present application provides a busbar and a welding method thereof, and a battery pack, and relates to the field of battery technology. The busbar of the present application includes: a busbar body, an air hole and an exhaust channel; the air hole penetrates the busbar body along the thickness direction of the busbar body and is arranged in the welding area of ​​the busbar body; the exhaust channel is arranged on the welding surface of the busbar body, one end of the exhaust channel is connected to the air hole, and the other end extends out of the welding area, so that the welding area of ​​the busbar body is connected to the outside world during the welding process. In addition, the cleanliness of the welding surface of the busbar body and the pole is ensured during the welding process. At the same time, the air pressure of the air flow can be changed during the welding process, which plays a role in buffering and reducing the pressure, so as to avoid that as the welding area of ​​the busbar and the pole continues to increase, the air pressure of the matching gap between the pole and the busbar body in the unwelded area is too large, resulting in excessive air pressure during the final welding, causing the busbar body to deform, affecting the welding effect, and improving the safety of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a bus bar and a welding method thereof, and a battery pack. Background Art

[0002] In electric vehicles and energy storage systems, the battery pack is the core energy storage unit. Inside the battery pack, the bus is an important component used to connect multiple battery cells or battery packs, carrying the role of transmitting and distributing electrical energy.

[0003] When the existing busbar is laser welded to the battery cell, there must be an assembly gap between the busbar and the pole of the battery cell. Under the action of laser heat, welding slag splashes in the welding area. The welding slag is scattered between the busbar and the pole of the battery cell, which not only affects the welding quality and causes problems such as cold welding, but also causes insufficient current between the busbar and the pole of the battery cell, which will cause the temperature of this area to rise during the charging and discharging process, reducing the safety of the battery. Summary of the invention

[0004] The purpose of the present application is to provide a busbar and a welding method thereof, and a battery pack, so as to solve the technical problem that the existing busbar structure reduces the safety of the battery.

[0005] To achieve the above purpose, the technical solution adopted in this application is:

[0006] In the first aspect, the present application provides a busbar for welding and connecting to the pole of a battery cell, comprising: a busbar body, an air hole and an exhaust channel; the air hole penetrates the busbar body along the thickness direction of the busbar body and is arranged in the welding area of ​​the busbar body; the exhaust channel is arranged on the welding surface of the busbar body, one end of the exhaust channel is connected to the air hole, and the other end extends out of the welding area, so as to connect the welding area of ​​the busbar body with the outside world during the welding process.

[0007] In one or more embodiments, the exhaust channel is a groove structure formed on the welding surface of the busbar body, wherein the groove width of the exhaust channel is d 1 , meet: 0.5mm≤d 1 ≤2mm; the groove depth of the exhaust channel is t 1 , the maximum thickness of the busbar body is t 0 , satisfying: 0.1≤t 1 / t 0 ≤0.5, and / or, the pore diameter is 0.3mm~1.0mm.

[0008] In one or more embodiments, further comprising:

[0009] The buffer groove is arranged in the non-welding area of ​​the bus body. The buffer groove is a groove structure formed on the welding surface of the bus body. The end of the exhaust channel away from the air hole is connected to the buffer groove. The groove width of the buffer groove is greater than the groove width of the exhaust channel.

[0010] In one or more embodiments, the length of the bus body is at least such that its two ends in the length direction are connected to the poles on different sides of two adjacent battery cells, and the buffer groove at least partially covers the explosion-proof valve of the battery cell, and a transition groove is formed at the connection between the exhaust channel and the buffer groove, and the transition groove is arranged in a manner that the groove width gradually increases from the exhaust channel to the buffer groove.

[0011] In one or more embodiments, the depth of the buffer groove is t 2 , the maximum thickness of the busbar body is t 0 , satisfying: 0.1≤t 2 / t 0 ≤0.5; and / or, the minimum distance L between the edge of the buffer groove and the edge of the busbar body satisfies: 1mm≤L≤3mm.

[0012] In one or more embodiments, the orthographic projection area of ​​the busbar body covering the explosion-proof valve is S 1 , the orthographic projection area of ​​the explosion-proof valve is S, satisfying: 0.25≤S 1 / S≤0.5, and / or, the angle β between the side of the busbar body and the horizontal direction of the explosion-proof valve satisfies: 10°≤β≤45°.

[0013] In one or more embodiments, the buffer groove is provided with a notch in the area covering the explosion-proof valve, and the notch is arranged in a manner of gradually decreasing width from the buffer groove to the side wall edge of the bus body, and the notch is connected to the outside at the side wall edge of the bus body; the side wall of the bus body is provided with an avoidance groove, which is an arc-shaped groove formed by being recessed from the outer wall of the bus body to the inside, and the avoidance groove is arranged between the exhaust channel and the buffer groove.

[0014] In one or more embodiments, the end of the exhaust channel away from the air hole extends to the side wall of the bus body and communicates with the outside, and the length of the bus body is at least such that both ends of its length direction connect the poles on the same side of two adjacent battery cells.

[0015] In a second aspect, the present application provides a busbar welding method, wherein the busbar described in any one of the first aspects is welded to a pole of a battery cell, comprising the following steps:

[0016] Placing the busbar discharge between the poles of two adjacent battery cells;

[0017] Use seals to wrap the non-welded areas of the busbar;

[0018] The welding area where the busbar is connected to the pole is welded, and at the same time, an air blowing device is used to blow air towards the air hole; during the welding process, the welding path is from one side of the exhaust channel in a clockwise or counterclockwise direction around the air hole to the other side of the exhaust channel, and finally the exhaust channel is closed to form a closed loop of the welding path.

[0019] In a third aspect, the present application further provides a battery pack, comprising: a plurality of battery cells and a bus as described in any one of the first aspects, wherein the bus is connected to poles on different sides of two adjacent battery cells, and / or the bus is connected to poles on the same side of two adjacent battery cells.

[0020] Based on the above technical solution, the busbar and its welding method, and battery pack provided by the present application have at least the following beneficial technical effects:

[0021] The bus provided in the embodiment of the present application is used for welding connection with the pole of the battery cell, and includes: a bus body, an air hole and an exhaust channel; the air hole penetrates the bus body along the thickness direction of the bus body and is arranged in the welding area of ​​the bus body; the exhaust channel is arranged on the welding surface of the bus body, one end of the exhaust channel is connected to the air hole, and the other end extends out of the welding area, so that the welding area of ​​the bus body is connected to the outside during the welding process. Furthermore, during the welding process, when the bus body and the pole are welded by laser, a blowing device can be used to blow air at the air hole at the same time. Since the air hole is located in the welding area of ​​the bus body, the generated welding spatter and welding slag are diffused to the outside of the welding area under the action of the air flow, ensuring the cleanliness of the welding surface of the bus body and the pole. At the same time, since the exhaust channel connects the pores with the outside of the welding area, the air flow pressure can be changed during the welding process, which plays a role in reducing the air pressure, avoiding excessive air pressure in the gap between the unwelded area of ​​the pole and the bus body as the welding area of ​​the bus and the pole continues to increase, thereby avoiding deformation of the bus, improving the welding effect, and improving the safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of a busbar according to an embodiment of the present application.

[0024] Figure 2 It is a three-dimensional structural schematic diagram of a welding surface perspective of a busbar of an embodiment provided in the present application.

[0025] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0026] Figure 4 It is a bottom view schematic diagram of a busbar according to an embodiment provided in the present application.

[0027] Figure 5 yes Figure 4 Enlarged view of point B in .

[0028] Figure 6 It is a three-dimensional structural schematic diagram of the welding surface perspective of a busbar of another embodiment provided in the present application.

[0029] Figure 7 It is a schematic diagram of the top view structure of the battery pack provided in this application.

[0030] Figure 8 It is a schematic diagram of the three-dimensional structure of the battery pack provided in this application.

[0031] Fig. 9 It is a perspective structural schematic diagram of the battery pack provided in this application.

[0032] Fig.10 It is a schematic diagram of the explosion structure of the battery pack provided in this application.

[0033] In the figure: 1-battery cell; 2-explosion-proof valve; 3-pole; 4-support frame; 5-insulating pad; 10-bus body; 11-air hole; 12-exhaust channel; 13-buffer groove; 14-transition groove; 15-avoidance groove; 16-notch; 17-protrusion; 20-oblique bus; 30-straight bus; 40-positive and negative bus. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0036] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0038] In the bus structure of the related technology, when a battery cell experiences thermal runaway, on the one hand, a large amount of conductive medium ejected from the battery cell will be scattered and accumulated on the bus and in its vicinity. For example, the conductive medium will accumulate between adjacent bus bars or between the bus bar and the metal box cover of the battery cell. Since the bus bar is still connected to the battery cell during thermal runaway, a thermal runaway electrical short circuit will occur. On the other hand, the battery cell that triggers thermal runaway will generate a large amount of heat, and its own temperature will increase significantly, accompanied by a voltage drop. At this time, the normal battery cell connected in series with it will conduct heat through the bus, resulting in a large amount of heat being transferred from the runaway battery cell to the normal battery cell via the bus, ultimately causing the thermal runaway to spread to the adjacent battery cells. In addition, when the existing bus is laser welded to the pole, there must be an assembly gap between the bus and the pole. Under the action of laser heat, welding slag will splash in the welding area. The welding slag will be scattered between the welding surfaces of the bus and the pole, which will not only affect the welding quality and cause cold welding problems, but also cause insufficient current between the bus and the pole, which will cause the temperature in this area to rise during the charging and discharging process, reducing the safety of the battery.

[0039] Based on the above considerations, in order to solve the technical problem that the existing busbar structure reduces the safety of the battery, the present application provides a busbar for welding and connecting with the pole of the battery cell, including: a busbar body, an air hole and an exhaust channel; the air hole penetrates the busbar body along the thickness direction of the busbar body and is arranged in the welding area of ​​the busbar body; the exhaust channel is arranged on the welding surface of the busbar body, one end of the exhaust channel is connected to the air hole, and the other end extends out of the welding area, so that the welding area of ​​the busbar body is connected to the outside world during the welding process.

[0040] In the technical solution of the embodiment of the present application, during the welding process, when the busbar body and the pole are welded by laser, a blowing device can be used to blow air at the air hole at the same time. Since the air hole is located in the welding area of ​​the busbar body, the generated welding spatter and welding slag are diffused to the outside of the welding area under the action of the air flow, ensuring the cleanliness of the welding surface of the busbar body and the pole. At the same time, since the exhaust channel connects the air hole with the outside of the welding area, the air pressure of the air flow can be changed during the welding process, which plays a role in reducing the air pressure, avoiding that as the welding area of ​​the busbar and the pole continues to increase, the air pressure in the matching gap between the pole and the busbar body is too high, resulting in excessive air pressure during the final welding, avoiding deformation of the busbar body, improving the welding effect, and improving the safety of the battery.

[0041] The busbar of the present application may be applicable to power batteries, energy storage batteries, electronic devices or mechanical devices.

[0042] The battery pack disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0043] The technical solution of the present application is described in detail below in conjunction with the accompanying drawings.

[0044] Please also read Figure 1 , Figure 2 and Figure 6 , Figure 1 and Figure 2 FIG. 1 shows an oblique busbar structure of an embodiment. Figure 6 Another embodiment of a straight-across bus structure is shown. The embodiment of the present application provides a bus for welding and connecting to the pole 3 of the battery cell 1, including: a bus body 10, an air hole 11 and an exhaust channel 12; the air hole 11 penetrates the bus body 10 along the thickness direction of the bus body 10 and is arranged in the welding area of ​​the bus body 10; the exhaust channel 12 is arranged on the welding surface of the bus body 10, one end of the exhaust channel 12 is connected to the air hole 11, and the other end extends out of the welding area, so that the welding area of ​​the bus body 10 is connected to the outside during the welding process.

[0045] Among them, the bus body 10 is used to connect with the pole 3 in the battery cell 1, so that the battery cells 1 form a series or parallel relationship. The bus body and the pole 3 are connected by laser welding. The pore 11 can be a through hole that penetrates the bus body 10 along the thickness direction of the bus body 10. The position of the pore 11 is located in the welding area of ​​the bus body 10, and it can be understood that the welding area of ​​the bus body 10 and the pole 3 surrounds the pore 11. The exhaust channel 12 can be a groove-shaped structure formed inwardly on the welding surface of the bus body 10. The exhaust channel 12 is used to connect the welding area of ​​the bus body 10 with the outside world, wherein the outside world can be understood as the outside of the welding area, that is, it can be a non-welding area of ​​the bus body 10, or it can be an outer area of ​​the bus body 10.

[0046] In the technical solution of the embodiment of the present application, during the welding process, when the busbar body 10 and the pole 3 are welded by laser, a blowing device can be used to blow air at the air hole 11 at the same time. Since the air hole 11 is located in the welding area of ​​the busbar body 10, the generated welding spatter and welding slag are diffused to the outside of the welding area under the action of the airflow, ensuring the cleanliness of the welding surface of the busbar body 10 and the pole 3. At the same time, since the exhaust channel 12 connects the air hole 11 with the outside of the welding area, the air pressure of the airflow can be changed during the welding process, playing a role of buffering and reducing pressure, avoiding that as the welding area of ​​the busbar and the pole 3 continues to increase, the air pressure in the matching gap between the pole 3 and the busbar body 10 in the unwelded area is too high, resulting in excessive air pressure during the final welding, causing deformation of the busbar body 10, affecting the welding effect, and the busbar structure of the present application improves the safety of the battery. At the same time, the setting of the air hole 11 facilitates the monitoring of the welding quality between the bus and the pole 3. After the welding is completed, the visual recognition system can be used to monitor whether there is a gap between the edges of the air hole and the pole 3. If there is a large gap, it means that the laser welding process has failed and the welding area of ​​the two has not been fused, and further processing is required.

[0047] Please refer to Figure 2 and Figure 3 In some embodiments, the exhaust channel 12 is a groove structure formed on the welding surface of the busbar body 10, wherein the groove width of the exhaust channel 12 is d 1 , meet: 0.5mm≤d 1 ≤2mm; the groove depth of the exhaust channel 12 is t 1 , the maximum thickness of the busbar body 10 is t 0 , satisfying: 0.1≤t 1 / t 0 ≤0.5.

[0048] The width of the exhaust channel 12 is d 1It can be 0.5mm, 0.7mm, 0.9mm, 1.1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, 2mm. The maximum thickness of the busbar body 10 can be the thickness of the area where the air holes 11, the exhaust channel 12 and other components are not provided. 1 / t 0 It can be 0.1, 0.2, 0.3, 0.4, 0.5.

[0049] In the technical solution of the embodiment of the present application, by setting the groove width and groove depth of the exhaust channel 12 within the above-mentioned range, on the one hand, the exhaust channel 12 plays a role in changing the pressure of the blowing air flow and buffering the pressure drop, thereby avoiding deformation of the bus body 10 caused by excessive pressure; on the other hand, the bus body 10 can also ensure the flow area.

[0050] In some embodiments, the diameter of the pore 11 is 0.3 mm to 1.0 mm, wherein the diameter of the pore 11 can be 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, or 1 mm.

[0051] In the technical solution of the embodiment of the present application, through the above arrangement, the air hole 11 can blow air to the welding area through the blowing device to ensure the cleanliness of the welding surface of the busbar body 10 and the pole 3. At the same time, the flow area of ​​the busbar body 10 is guaranteed.

[0052] In some embodiments, the two ends of the busbar are connected to the poles 3 of different battery cells 1. Therefore, the welding areas at both ends of the busbar are provided with air holes 11 and exhaust channels 12 connected to the air holes 11. Figure 2 or Figure 6 shown.

[0053] Please refer to Figure 2 and Figure 3 In some embodiments, the bus further includes: a buffer groove 13, which is disposed in a non-welding area of ​​the bus body 10, and the buffer groove 13 is a groove structure formed on the welding surface of the bus body 10, and the end of the exhaust channel 12 away from the air hole 11 is connected to the buffer groove 13, and the groove width of the buffer groove 13 is greater than the groove width of the exhaust channel 12.

[0054] In the technical solution of the embodiment of the present application, the buffer groove 13 is connected to the exhaust channel 12, and the groove width of the buffer groove 13 is greater than the groove width of the exhaust channel 12. When laser welding is performed, after the airflow moves from the exhaust channel 12 to the buffer groove 13, the air pressure decreases, which plays a role in reducing the pressure and relieving the blowing pressure.

[0055] Please refer to Figure 1 and Figure 2In some embodiments, the length of the busbar body 10 is at least such that both ends of its length direction are connected to the poles 3 on different sides of two adjacent battery cells 1, and the buffer groove 13 at least partially covers the explosion-proof valve 2 of the battery cell 1, and a transition groove 14 is formed at the connection between the exhaust channel 12 and the buffer groove 13, and the transition groove 14 is arranged in a manner that the groove width gradually increases from the exhaust channel 12 to the buffer groove 13. Figure 7 , Figure 8 and Fig. 9 As shown, in this embodiment, the busbar body 10 is connected diagonally across the poles 3 on different sides of two adjacent battery cells 1. The two ends of the buffer groove 13 can be connected to the exhaust channels 12 located at the two ends of the busbar. That is to say, in this embodiment, the buffer groove 13 is arranged in the middle of the busbar body 10 and extends to both ends along the length direction. One end of the exhaust channel 12 is connected to the air hole 11, and the other end is connected to the buffer groove 13. The exhaust channel 12 extends along the length direction, so that a structure with exhaust channels 12 at both ends and a buffer groove 13 in the middle is formed on the side of the busbar body 10 facing the pole 3.

[0056] In the technical solution of the embodiment of the present application, the buffer tank 13 can not only reduce the pressure and relieve the blowing pressure during the welding process, but also because the buffer tank 13 at least partially covers the explosion-proof valve 2 of the battery cell 1. When the battery cell 1 has thermal runaway, the high-temperature and high-pressure gas mixed with the unmelted high-temperature material will be ejected from the explosion-proof valve 2 instantly, and the temperature of the cross-bus will rise instantly, and part of the high-pressure gas flow will enter the buffer tank 13. Fig. 9 As shown in the airflow direction, the high-pressure airflow flows from the middle position of the buffer groove 13 to the two end positions. When flowing through the transition groove 14, the airflow path is sharply reduced, and a backflow phenomenon occurs. After the backflow, it meets the middle reverse airflow, resulting in an increase in the internal air pressure of the buffer groove 13. The temperature and pressure of the buffer groove 13 are relatively large compared to the two ends, and the groove wall of the buffer groove 13 can block the leakage of the airflow, further increasing the pressure in the buffer groove 13. Under the action of high temperature and high pressure, the position of the busbar buffer groove 13 will fuse and break, and then disconnect the battery cell in thermal runaway from the normal battery cell pole connected in series, thereby blocking the risk of electrical short circuit and heat conduction. At the same time, the groove structure design of the buffer groove 13 can also store a certain amount of thermal runaway eruption material, causing it to fuse locally, avoiding the thermal runaway spread of normal battery cells caused by the accumulation of thermal runaway eruption materials. In order to ensure that the busbar overlaps with the explosion-proof valve 2, the busbar body 10 is wide and thin. While ensuring the flow area, it is also easy to break at the position of the buffer groove 13 when thermal runaway occurs, thereby improving the safety of the battery.

[0057] Please refer to Figure 3 In some embodiments, the depth of the buffer groove 13 is t 2 , the maximum thickness of the busbar body 10 is t0 , satisfying: 0.1≤t 2 / t 0 ≤0.5. Among them, t 2 / t 0 The depth of the buffer groove 13 can be consistent with the depth of the exhaust channel 12 .

[0058] In some embodiments, the minimum distance L between the edge of the buffer groove 13 and the edge of the busbar body 10 satisfies: 1 mm≤L≤3 mm, where L can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

[0059] In the technical solution of the embodiment of the present application, the above-mentioned setting is adopted so that the buffer tank 13 can not only reduce the pressure and relieve the blowing pressure, but also break in time when thermal runaway occurs to prevent the spread of thermal runaway, while ensuring the flow area of ​​the bus.

[0060] Please refer to Fig. 9 The orthographic projection area of ​​the busbar body 10 covering the explosion-proof valve 2 is S 1 , the orthographic projection area of ​​explosion-proof valve 2 is S, satisfying: 0.25≤S 1 / S≤0.5. Among them, S 1 / S can be 0.25, 0.3, 0.35, 0.4, 0.45, 0.5.

[0061] Please refer to Figure 7 In some embodiments, the angle β between the side of the busbar body 10 and the explosion-proof valve 2 in the horizontal direction satisfies: 10°≤β≤45°. β can be 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°.

[0062] In the technical solution of the embodiment of the present application, through the above-mentioned setting, the buffer tank 13 can receive the high-temperature airflow of the explosion-proof valve 2 due to thermal runaway, and break it in time to avoid the spread of thermal runaway, and at the same time, the buffer tank 13 can have the function of reducing pressure and relieving the blowing pressure.

[0063] Please refer to Figure 2 , Figure 4 and Figure 5 The buffer groove 13 is provided with a notch 16 in the area covering the explosion-proof valve 2. The notch 16 is arranged in a manner of gradually decreasing width from the buffer groove 13 to the side wall edge of the bus body 10, and the notch 16 is connected to the outside at the side wall edge of the bus body 10.

[0064] The notch 16 is in a trumpet shape with a larger inner portion and a smaller outer portion.

[0065] In the technical solution of the embodiment of the present application, when thermal runaway occurs, the thermal runaway high-pressure airflow formed in the buffer tank 13 impacts the outside, and the pressure increases when flowing through the notch 16 area. In addition, under high temperature environment, the busbar made of aluminum is weak in strength, so the busbar will first crack at the notch 16. This is conducive to busbar rupture, and then disconnecting the battery cell in thermal runaway from the normal battery cell pole connected in series, thereby blocking the existing electrical short circuit and heat conduction risks, and improving the safety of the battery.

[0066] In some embodiments, the cross section of the notch 16 is a trapezoidal structure. In some embodiments, the two sides of the notch 16 are symmetrically arranged about the edge of the busbar body 10. Figure 4 and Figure 5 As shown, the distance h between the vertices of the two side edges of the notch 16 extending outward and the edge of the busbar body 10 is 0.5-2 mm, and the angle θ of the notch 16 is 10-30°. Thus, the notch 16 can ensure that cracking can occur during thermal runaway, and can also serve as an exhaust channel for thermal runaway airflow.

[0067] Please refer to Figure 2 and Figure 3 In some embodiments, a side wall of the bus body 10 is provided with an avoidance groove 15 , which is an arc-shaped groove formed by being recessed inward from the outer wall of the bus body 10 , and the avoidance groove 15 is provided between the exhaust channel 12 and the buffer groove 13 .

[0068] In the technical solution of the embodiment of the present application, the above-mentioned setting is adopted to meet the electrical safety avoidance area between adjacent busbars, such as the oblique busbar 20 connecting the poles 3 on different sides of two adjacent battery cells 1 and the straight busbar 30 connecting the poles 3 on the same side of two adjacent battery cells 1. At the same time, the avoidance groove 15 is arranged between the exhaust channel 12 and the buffer groove 13 to avoid the overlap of the recessed area of ​​the avoidance groove 15 with the buffer groove 13, and to avoid the cross section of the buffer groove 13 being too small, thereby affecting the flow capacity of the overall busbar. The avoidance groove 15 also has the function of absorbing the expansion of the battery cell 1. When the battery cell 1 expands in the thickness direction, after the oblique busbar 20 is welded with the poles of the two series-connected battery cells, the two ends are completely fixed. When the thickness of the battery cell 1 changes, the inward recessed area of ​​the avoidance groove 15 at both ends of the busbar will be deformed due to its relatively weak strength in the thickness direction, thereby absorbing the dimensional expansion in the thickness direction.

[0069] In some embodiments, due to the distance requirements of the poles 3 of adjacent battery cells 1, in order to meet the design of the creepage distance of the electrical appliance, the distance between the avoidance groove 15 and the adjacent straight-across busbar 30 or the positive and negative busbar 40 needs to be greater than or equal to 9.5 mm. Among them, the distance between the avoidance groove 15 and the adjacent straight-across busbar 30 or the positive and negative busbar 40 is the minimum distance between the arc-shaped avoidance groove 15 and the straight-across busbar 30 or the positive and negative busbar 40.

[0070] like Figure 6 As shown, in some embodiments, the end of the exhaust channel 12 away from the air hole 11 extends to the side wall of the busbar body 10 and is connected to the outside, and the length of the busbar body 10 is at least such that both ends of its length direction are connected to the poles 3 on the same side of two adjacent battery cells 1. Figure 7 , Figure 8 and Fig. 9 As shown, the busbar directly crosses the poles 3 on the same side of two adjacent battery cells 1 to connect.

[0071] In the technical solution of the embodiment of the present application, since the exhaust channel 12 extends to the side wall of the bus body 10 and is connected to the outside, the air flow pressure can be changed during the welding process, which plays a role in buffering the pressure reduction, thereby avoiding the situation where the air flow pressure in the gap between the unwelded area of ​​the pole and the bus body is too high as the welding area between the bus and the pole continues to increase, resulting in excessive air pressure during the final welding, causing deformation of the bus body 10 and affecting the welding effect. The straight-across bus of the present application improves the safety of the battery.

[0072] In some embodiments, Figure 6 As shown, a protrusion 17 is provided in the middle of the busbar body 10, and the protrusion 17 is formed by a concave surface of one side of the busbar body 10 toward the other side. Through the above arrangement, the straight-span busbar can absorb the expansion change of the battery cell thickness when the thickness of the battery cell 1 changes.

[0073] In some embodiments, Figure 6 In the straight-across bus 30 shown, a notch 16 can be provided in the non-overlapping area between the straight-across bus 30 and the pole 3. On the one hand, the notch 16 is provided in the non-overlapping area to avoid affecting the flow area of ​​the straight-across bus 30. On the other hand, the notch 16 is conducive to timely breaking when thermal runaway occurs, thereby disconnecting the battery cell in thermal runaway from the normal battery cell pole connected in series, thereby blocking the existing electrical short circuit and heat conduction risks, and improving the safety of the battery.

[0074] The busbar of the present application may be an oblique busbar 20 with two ends connected to poles 3 on different sides of two adjacent battery cells 1 , or may be a straight busbar 30 with two ends connected to poles 3 on the same side of two adjacent battery cells 1 .

[0075] On the other hand, the present application provides a busbar welding method, which welds the busbar to the pole 3 of the battery cell 1, wherein the busbar can be an oblique busbar 20 or a straight busbar 30. The method comprises the following steps:

[0076] The busbar discharge is placed between the poles 3 of two adjacent battery cells 1;

[0077] Use seals to wrap the non-welded areas of the busbar;

[0078] The welding area where the busbar is connected to the pole 3 is welded, and at the same time, an air blowing device is used to blow air toward the air hole 11; during the welding process, the welding path is from one side of the exhaust channel 12 in a clockwise or counterclockwise direction around the air hole 11 to the other side of the exhaust channel 12, and finally the exhaust channel 12 is closed to form a closed loop of the welding path.

[0079] Among them, the sealing member can be a sealing foam, and the sealing foam of the laser equipment is adhered and compressed to the non-welding area around the bus, and the laser beam is irradiated on the welding area between the bus and the pole 3. At the same time, the blowing device of the laser welding equipment is aimed at the air hole 11 for blowing. The welding path is from one side of the exhaust channel 12 along the clockwise or counterclockwise direction around the air hole 11 to the other side of the exhaust channel 12 for welding, and finally the exhaust channel 12 is closed to form a closed loop of the welding path to ensure that during the welding process, fine welding slag is discharged with the air hole and the exhaust channel 12, while ensuring the flow.

[0080] On the other hand, Figure 7 , Figure 8 , Fig. 9 and Fig.10 As shown, the present application also provides a battery pack, comprising: a plurality of battery cells 1 and the busbar, wherein the busbar is connected to the poles 3 on different sides of two adjacent battery cells 1, and / or the busbar is connected to the poles 3 on the same side of two adjacent battery cells 1. When connecting the poles 3 on different sides of two adjacent battery cells 1, an oblique busbar 20 is used, and when connecting the poles 3 on the same side of two adjacent battery cells 1, a straight busbar 30 is used. In some embodiments, please refer to Fig.10 The battery pack also includes a positive and negative bus bar 40, which are respectively connected to the poles 3 at the head end and the tail end.

[0081] In some embodiments, please refer to Fig.10The battery pack further includes a support frame 4, which is arranged on the pole side of the plurality of battery cells 1. The support frame 4 is provided with an opening for avoiding the pole. After the support frame 4 is installed on the pole side of the battery cell 1, the oblique busbar 20, the straight busbar 30 and the positive and negative busbars 40 are respectively welded to the pole 3. The support frame 4 can play the role of an integrated busbar.

[0082] In some embodiments, please refer to Fig.10 The battery pack further includes an insulating pad 5, which is disposed on the large surface side of two adjacent battery cells 1 and is used for heat insulation between the two adjacent battery cells 1 to prevent heat spread between the two adjacent battery cells during thermal runaway.

[0083] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A busbar, used for welding connection with a pole (3) of a battery cell (1), characterized in that: include: Busbar body (10); An air hole (11) penetrates the busbar body (10) along the thickness direction of the busbar body (10) and is provided in a welding area of ​​the busbar body (10); An exhaust channel (12) is provided on the welding surface of the busbar body (10); the exhaust channel (12) is a groove structure formed on the welding surface of the busbar body (10); one end of the exhaust channel (12) is connected to the air hole (11), and the other end extends out of the welding area, so that the welding area of ​​the busbar body (10) is connected to the outside during the welding process.

2. The busbar according to claim 1, characterized in that: The groove width of the exhaust channel (12) is d1, which satisfies: 0.5 mm ≤ d1 ≤ 2 mm; the groove depth of the exhaust channel (12) is t1, and the maximum thickness of the busbar body (10) is t0, which satisfies: 0.1 ≤ t1 / t0 ≤ 0.

5. The pores (11) have a diameter of 0.3 mm to 1.0 mm.

3. The busbar according to claim 1 or 2, characterized in that: Also includes: A buffer groove (13) is provided in a non-welding area of ​​the busbar body (10); the buffer groove (13) is a groove structure formed on the welding surface of the busbar body (10); an end of the exhaust channel (12) away from the air hole (11) is connected to the buffer groove (13); and a groove width of the buffer groove (13) is greater than a groove width of the exhaust channel (12).

4. The busbar according to claim 3, characterized in that: The length of the busbar body (10) is at least such that both ends of its length direction are connected to poles (3) on different sides of two adjacent battery cells (1), and the buffer groove (13) at least partially covers the explosion-proof valve (2) of the battery cell (1). A transition groove (14) is formed at the connection between the exhaust channel (12) and the buffer groove (13), and the transition groove (14) is arranged in a manner in which the groove width gradually increases in a direction from the exhaust channel (12) to the buffer groove (13).

5. The busbar according to claim 4, characterized in that: The groove depth of the buffer groove (13) is t2, the maximum thickness of the busbar body (10) is t0, and the following conditions are satisfied: 0.1≤t2 / t0≤0.5; and / or, The minimum distance L between the edge of the buffer groove (13) and the edge of the busbar body (10) satisfies the following: 1 mm ≤ L ≤ 3 mm.

6. The busbar according to claim 5, characterized in that: The orthographic projection area of ​​the area where the busbar body (10) covers the explosion-proof valve (2) is S1, and the orthographic projection area of ​​the explosion-proof valve (2) is S, satisfying: 0.25≤S1 / S≤0.5, and / or, The included angle β between the side of the busbar body (10) and the explosion-proof valve (2) in the horizontal direction satisfies: 10°≤β≤45°.

7. The busbar according to claim 6, characterized in that: The buffer groove (13) is provided with a notch (16) in the area covering the explosion-proof valve (2), the notch (16) is arranged in a manner of gradually decreasing width from the buffer groove (13) to the side wall edge of the busbar body (10), and the notch (16) is connected to the outside at the side wall edge of the busbar body (10); The side wall of the busbar body (10) is provided with an escape groove (15), the escape groove (15) being an arc-shaped groove formed by being recessed inward from the outer wall of the busbar body (10), and the escape groove (15) is provided between the exhaust passage (12) and the buffer groove (13).

8. The busbar according to claim 1 or 2, characterized in that: The exhaust passage (12) extends from the end of the air hole (11) to the side wall of the busbar body (10) and is in communication with the outside. The length of the busbar body (10) is at least such that both ends in its length direction are connected to the poles (3) on the same side of two adjacent battery cells (1).

9. A busbar welding method, characterized in that: The busbar according to any one of claims 1 to 8 and the pole (3) of the battery cell (1) are welded and connected, comprising the following steps: Placing the busbar discharge between the poles (3) of two adjacent battery cells (1); A seal is used to wrap the non-welding area of ​​the busbar; The welding area where the busbar is connected to the pole (3) is welded, and at the same time, an air blowing device is used to blow air towards the air hole (11); wherein during the welding process, the welding path is from one side of the exhaust channel (12) to the other side of the exhaust channel (12) in a clockwise or counterclockwise direction around the air hole (11), and finally the exhaust channel (12) is closed, so that the welding path forms a closed loop.

10. A battery pack comprising: A plurality of battery cells (1) and a busbar as claimed in any one of claims 1 to 8, wherein the busbar is connected to poles (3) on different sides of two adjacent battery cells (1), and / or the busbar is connected to poles (3) on the same side of two adjacent battery cells (1).

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