Battery cell welding method, welding system and battery cell

Abstract

The invention relates to a battery cell welding method and system and a battery cell, and the battery cell welding method comprises the steps that to-be-welded edges of the battery cell and the primary welding direction and the secondary welding direction of the to-be-welded edges are determined, and any two adjacent to-be-welded edges form an intersection area; the to-be-welded edge is subjected to primary welding according to the primary welding direction, the to-be-welded edge is subjected to secondary welding according to the secondary welding direction, the primary welding direction is opposite to the secondary welding direction, and both the primary welding direction and the secondary welding direction cover the intersection area. According to the battery cell welding method, the welding system and the welding seam, the primary welding position is remelted through secondary welding, the compactness of the welding position is improved, the number of air holes in the welding position is reduced, and the sealing performance between the aluminum shell and the end cover is improved; and moreover, pits in secondary welding between the end cover and the aluminum shell are avoided, and the sealing performance between the aluminum shell and the end cover is further improved.

Description

Technical Field

[0001] The present application relates to the field of battery core welding, and in particular to a blade battery core welding method, a welding system and a battery core. Background Art

[0002] With the development of vehicle technology and battery technology, batteries are increasingly used in vehicles. Batteries include several cells, which include a cell body and an end cap. The aluminum shell of the cell body and the end cap need to be welded, so the aluminum shell and the end cap need to be welded around. The welding process of the prior art easily leads to poor welding between the aluminum shell and the end cap, and helium leakage is likely to occur, resulting in poor cell quality. Summary of the invention

[0003] Based on this, the present application provides a battery cell welding method, a welding system and a battery cell to improve the welding sealing performance between the aluminum shell and the end cover.

[0004] In one aspect, a battery core welding method is provided, the battery core welding method comprising:

[0005] Determine the edges to be welded of the battery core and determine the primary welding direction and the secondary welding direction of the edges to be welded, and any two adjacent edges to be welded form an intersection area;

[0006] The edge to be welded is welded once in the primary welding direction, and welded twice in the secondary welding direction. The primary welding direction is opposite to the secondary welding direction. Both the primary welding and the secondary welding cover the intersection area.

[0007] In one embodiment, the performing of primary welding on the edge to be welded according to the primary welding direction, and performing of secondary welding on the edge to be welded according to the secondary welding direction, comprises:

[0008] Performing path planning for the edge to be welded according to the primary welding direction and the secondary welding direction to form a welding path, and determining welding parameters corresponding to the welding path;

[0009] The primary welding and the secondary welding are performed on the edge to be welded according to the welding path and the corresponding welding parameters.

[0010] In one embodiment, the side to be welded is a long side, and the step of welding the side to be welded once according to the primary welding direction includes:

[0011] Perform path planning on the long side in accordance with the first welding direction to form a first long-side welding path, and obtain the welding parameters corresponding to the first long-side welding path, where the first long-side welding path covers the welding area of the long side;

[0012] Perform the first welding on the long side in accordance with the first long-side welding path and its corresponding welding parameters.

[0013] In one embodiment, the performing second welding on the to-be-welded side in accordance with the second welding direction includes:

[0014] Perform path planning on the long side in accordance with the second welding direction to form a second long-side welding path, and obtain the welding parameters corresponding to the second long-side welding path, where the second long-side welding path covers the intersection area of the long side and its adjacent side;

[0015] Perform the second welding on the long side in accordance with the second long-side welding path and its corresponding welding parameters.

[0016] In one embodiment, the to-be-welded side is a short side, and the performing first welding on the to-be-welded side in accordance with the first welding direction and performing second welding on the to-be-welded side in accordance with the second welding direction include:

[0017] Perform path planning on the short side in accordance with the first welding direction to form a first short-side welding path, and obtain the welding parameters corresponding to the first short-side welding path;

[0018] Perform path planning on the short side in accordance with the second welding direction to form a second short-side welding path, and obtain the welding parameters corresponding to the second short-side welding path;

[0019] Perform the first welding on the short side in accordance with the first short-side welding path and its corresponding welding parameters, and perform the second welding on the short side in accordance with the second short-side welding path and its corresponding welding parameters; both the first short-side welding path and the second short-side welding path cover the intersection area of the short side and its adjacent side or cover the welding area of the short side.

[0020] In one embodiment, the first long-side welding path, the first short-side welding path, and the second short-side welding path each include an acceleration path, an intermediate welding path, and a deceleration path arranged in sequence, the second long-side welding path includes an acceleration path, an intermediate welding path, a transition path, and a deceleration path arranged in sequence, and the transition path is a power attenuation path.

[0021] In one embodiment, the battery cell includes four edges to be welded connected end to end, and the battery cell welding method further includes:

[0022] Welding the four ends of the edges to be welded in sequence in a clockwise or counterclockwise direction;

[0023] The primary welding direction of any of the edges to be welded is connected end to end.

[0024] In one embodiment, before performing a primary welding on the edge to be welded according to the primary welding direction and performing a secondary welding on the edge to be welded according to the secondary welding direction, the battery core welding method further includes:

[0025] The defocus modes of the primary welding and the secondary welding are set so that the primary welding and the secondary welding are in a negative defocus mode.

[0026] In another aspect, an electric core welding system is provided, the electric core welding system comprising:

[0027] A control module, used to determine the edge to be welded of the battery cell, determine the primary welding direction and the secondary welding direction of the edge to be welded, and determine the intersection area formed by any two adjacent edges to be welded;

[0028] The welding module is used to perform a primary welding on the edge to be welded according to the primary welding direction, and to perform a secondary welding on the edge to be welded according to the secondary welding direction. The primary welding direction is opposite to the secondary welding direction, and both the primary welding and the secondary welding cover the intersection area.

[0029] On the other hand, a battery cell is provided, wherein a weld is formed by welding based on the battery cell welding method, or a weld is formed by welding based on the battery cell welding system.

[0030] The above technical solution of the present application has the following advantages compared with the prior art:

[0031] The battery cell welding method of the present application remelts the primary welding point through secondary welding, thereby improving the density of the welding point, making the overlap position smooth, reducing the number of pores at the welding point, and improving the sealing performance between the aluminum shell and the end cover. The weld has a round, smooth appearance and good quality. Moreover, the primary welding direction is opposite to the secondary welding direction, thereby avoiding the appearance of pits in the secondary welding between the end cover and the aluminum shell, and further improving the sealing performance between the aluminum shell and the end cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments 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 any creative work.

[0033] Figure 1 is a first method flow chart of the battery core welding method provided in an embodiment of the present application;

[0034] Figure 2 is a second method flow chart of the battery core welding method provided in an embodiment of the present application;

[0035] Figure 3 It is a schematic structural diagram of the edges to be welded of the end cover and the aluminum shell provided in an embodiment of the present application;

[0036] Figure 4 It is a schematic diagram of the distribution of metallographic structure collection points of the weld between the end cover and the aluminum shell provided in the embodiment of the present application;

[0037] Figure 5 It is a welding path diagram of the edges to be welded between the end cover and the aluminum shell provided in an embodiment of the present application;

[0038] Figure 6 is a relationship diagram between position and speed of the welding path of the end cover and the long side of the aluminum shell provided in an embodiment of the present application;

[0039] Figure 7 is a relationship diagram between position and speed of a welding path between an end cover and a short side of an aluminum shell provided in an embodiment of the present application;

[0040] Figure 8 is a schematic structural diagram of a welding module of a welding system provided in an embodiment of the present application;

[0041] Fig. 9 It is a metallographic structure diagram of the weld between the end cover and the aluminum shell provided in the embodiment of the present application.

[0042] Description of the Figures in the Specification:

[0043] 1. Laser; 2. Welding copper nozzle; 3. Dust removal device. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of 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.

[0045] Embodiment 1

[0046] Reference Figure 1As shown, Figure 1 A first method flow chart of the battery core welding method provided in an embodiment of the present application.

[0047] The battery core welding method comprises the following steps:

[0048] S101, determining the edges to be welded of the battery cell and determining the primary welding direction and the secondary welding direction of the edges to be welded, and any two adjacent edges to be welded form an intersection area;

[0049] To weld the aluminum shell and the end cover of the battery cell using the battery cell welding method of the present application, firstly, the side of the battery cell to be welded is determined, such as Figure 3 As shown, there are four edges to be welded between the aluminum shell and the end cover of the battery cell, namely, two long edges (a, c) and two short edges (b, d). Specifically, any two adjacent edges to be welded intersect, and the intersection of the two edges to be welded forms an intersection area, namely, the intersection area where the long edge and the short edge intersect. In addition, the primary welding direction and the secondary welding direction must be determined so that the edges to be welded can be welded according to the primary welding direction and the secondary welding direction.

[0050] S102, performing a primary welding on the edge to be welded according to a primary welding direction, and performing a secondary welding on the edge to be welded according to a secondary welding direction, wherein the primary welding direction is opposite to the secondary welding direction, and both the primary welding and the secondary welding cover the intersection area.

[0051] After determining the edge to be welded and the welding direction, the edge to be welded is welded. The present application performs two weldings on the edge to be welded, i.e., the first welding and the second welding, so as to perform the second welding on the basis of the first welding, remelt the first welded position between the aluminum shell and the end cover, improve the density of the weld, reduce the number of pores in the weld, so as to improve the sealing performance between the aluminum shell and the end cover. In addition, the welding directions of the first welding and the second welding are opposite, such as Figure 3 As shown, the primary welding is performed along the direction from D to A, and the secondary welding is performed along the direction from A to D. In this way, no pit will appear at the starting point of the secondary welding between the end cover and the aluminum shell. The pit will easily lead to poor welding between the end cover and the aluminum shell, and helium leakage detection phenomenon. The welding direction of the primary welding is called the primary welding direction, and the welding direction of the secondary welding is called the secondary welding direction. Among them, the primary welding and the secondary welding both cover the intersection area, and the intersection area is the intersection area of ​​any two adjacent edges to be welded among the four welding edges, that is, the four corners formed by the end cover and the aluminum shell. The four corners are where a large number of pores are likely to exist. Therefore, the four corners are remelted by secondary welding to reduce the amount of gas at the four corners, thereby improving the sealing performance between the aluminum shell and the end cover. According to the battery cell welding method of the present application, for example Figure 4 Weld the edges to be welded as shown. Figure 4The weld metallographic structure analysis is performed at positions 1, 2, 3, 4, 5, 6, 7 and 8. Positions 1-4 are the positions on the long side, and positions 5-8 are the positions of the intersection area (rounded corner positions). The metallographic structure analysis results are as follows: Fig. 9 As shown by Fig. 9 It can be seen that the straight edges of the four edges to be welded have the same penetration depth as the R corner, the welding quality meets the requirements, and the helium test is passed, which can prove that the battery cell welding method of the present application can improve the density of the weld, reduce the number of pores, improve the sealing performance, and thus improve the quality of the battery cell.

[0052] The battery cell welding method of the present application remelts the primary welding point through secondary welding, thereby improving the density of the welding point, making the overlap position smooth, reducing the number of pores at the welding point, and improving the sealing performance between the aluminum shell and the end cover. The weld has a round, smooth appearance and good quality. Moreover, the primary welding direction is opposite to the secondary welding direction, thereby avoiding the appearance of pits in the secondary welding between the end cover and the aluminum shell, and further improving the sealing performance between the aluminum shell and the end cover.

[0053] In one embodiment, performing a primary welding on the edge to be welded according to a primary welding direction, and performing a secondary welding on the edge to be welded according to a secondary welding direction, comprises:

[0054] Performing path planning for the edge to be welded according to the primary welding direction and the secondary welding direction to form a welding path, and determining welding parameters corresponding to the welding path;

[0055] Specifically, before welding the edge to be welded, it is necessary to perform path planning for the edge to be welded according to the welding direction, so as to weld the end cover and the aluminum shell according to the optimal path and improve welding efficiency. That is, the path planning is performed for the edge to be welded according to the primary welding direction and the secondary welding direction to form a welding path. In addition, after the welding path is determined, the process parameters of the welding path are set, that is, the welding parameters corresponding to the welding path are determined, so as to weld the end cover and the aluminum shell according to the welding path and the welding parameters.

[0056] The edges to be welded are subjected to primary welding and secondary welding according to the welding path and its corresponding welding parameters.

[0057] Specifically, a welding path is formed by planning the path of the welding edge according to the primary welding direction and the secondary welding direction, and after the welding parameters of the welding path are determined, the welding edge is welded once and twice according to the determined welding path and welding parameters, so as to weld the end cover and the aluminum shell together. The two welding processes in opposite directions improve the sealing performance between the end cover and the aluminum shell and improve the quality of the battery cell.

[0058] In one embodiment, the side to be welded is a long side, and the side to be welded is welded once according to a welding direction:

[0059] Performing path planning on the long side according to the primary welding direction to form a long side primary welding path, and obtaining welding parameters corresponding to the long side primary welding path, wherein the long side primary welding path covers the welding area of ​​the long side;

[0060] Specifically, the side to be welded is divided into a long side and a short side. When the side to be welded is a long side and is welded once, the path planning for the long side's welding is performed according to the long side's welding direction, so as to weld the long side of the end cover and the aluminum shell once according to the optimal path, thereby improving the welding efficiency. The long side's welding direction is defined as the first direction, such as Figure 5 In addition, after determining the long side primary welding path, the process parameters of the long side primary welding path are set, that is, the welding parameters corresponding to the long side primary welding path are determined, so as to weld the long sides of the end cover and the aluminum shell once according to the long side primary welding path and its corresponding welding parameters.

[0061] The long side is welded once according to the long side primary welding path and its corresponding welding parameters.

[0062] Specifically, after determining the long side primary welding path and its corresponding welding parameters, the long side can be welded once according to the long side primary welding path and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together.

[0063] In one embodiment, performing secondary welding on the edge to be welded according to the secondary welding direction includes:

[0064] Performing path planning on the long side to form a secondary welding path for the long side, and obtaining welding parameters corresponding to the secondary welding path for the long side, wherein the secondary welding path for the long side covers an intersection area between the long side and its adjacent side;

[0065] Specifically, the side to be welded is divided into a long side and a short side. When the side to be welded is a long side and is welded for the second time, the path planning for the second time welding of the long side is performed according to the second time welding direction of the long side, so as to perform the second time welding of the long side of the end cover and the aluminum shell according to the optimal path, thereby improving the welding efficiency. The second time welding direction of the long side is defined as the second direction, such as Figure 5The second direction is the opposite direction of the first direction, that is, the long side is reflow welded. In addition, after the secondary welding path of the long side is determined, the process parameters of the secondary welding path of the long side are set, that is, the welding parameters corresponding to the secondary welding path of the long side are determined, so as to perform secondary welding on the long side of the end cover and the aluminum shell according to the secondary welding path of the long side and its corresponding welding parameters. Among them, the secondary welding path of the long side only needs to cover the intersection area of ​​the long side and its adjacent side, that is, the secondary welding path of the long side does not need to cover the entire length of the long side to improve the production cycle.

[0066] The long side is welded for the second time according to the long side secondary welding path and its corresponding welding parameters.

[0067] Specifically, after determining the secondary welding path of the long side and its corresponding welding parameters, the long side can be welded for the second time according to the secondary welding path of the long side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. The two welding processes in opposite directions improve the sealing performance between the end cover and the aluminum shell and improve the quality of the battery cell.

[0068] In one embodiment, the side to be welded is a short side, a primary welding is performed on the side to be welded according to a primary welding direction, and a secondary welding is performed on the side to be welded according to a secondary welding direction, including:

[0069] Performing path planning for the short side according to the primary welding direction to form a short side primary welding path, and obtaining welding parameters corresponding to the short side primary welding path;

[0070] Specifically, the side to be welded is divided into a long side and a short side. When the side to be welded is a short side and is welded once, a path is planned for the short side according to the short side's primary welding direction to form a short side primary welding path, so as to weld the short side of the end cover and the aluminum shell according to the optimal path to improve welding efficiency. The primary welding direction of the short side is defined as the third direction, such as Figure 5 In addition, after the short side primary welding path is determined, the process parameters of the short side primary welding path are set, that is, the welding parameters corresponding to the short side primary welding path are determined, so as to weld the short side of the end cover and the aluminum shell once according to the short side primary welding path and its corresponding welding parameters.

[0071] Performing path planning for the short side according to the secondary welding direction to form a short side secondary welding path, and obtaining welding parameters corresponding to the short side secondary welding path;

[0072] Specifically, the side to be welded is divided into a long side and a short side. When the side to be welded is a short side and is subjected to secondary welding, a path is planned for the short side according to the secondary welding direction of the short side to form a short side secondary welding path, so as to weld the short side of the end cover and the aluminum shell according to the optimal path to improve welding efficiency. The secondary welding direction of the short side is defined as the fourth direction, such as Figure 5 As shown, the fourth direction is opposite to the third direction. In addition, after the short side secondary welding path is determined, the process parameters of the short side secondary welding path are set, that is, the welding parameters corresponding to the short side secondary welding path are determined, so as to perform secondary welding on the short side of the end cover and the aluminum shell according to the short side secondary welding path and its corresponding welding parameters. Among them, since the welding length of the short side is short, the secondary welding of the short side can directly weld the full length of the short side, that is, the short side primary welding path and the short side secondary welding path both cover the entire welding area of ​​the short side.

[0073] The short side is welded once according to the primary welding path of the short side and its corresponding welding parameters, and the short side is welded twice according to the secondary welding path of the short side and its corresponding welding parameters; the primary welding path of the short side and the secondary welding path of the short side both cover the intersection area between the short side and its adjacent side or cover the welding area of ​​the short side.

[0074] Specifically, after determining the primary welding path of the short side and its corresponding welding parameters, and determining the secondary welding path of the short side and its corresponding welding parameters, the short side is welded once according to the primary welding path of the short side and its corresponding welding parameters; and the short side is welded twice according to the secondary welding path of the short side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. The two welding processes in opposite directions improve the sealing performance between the end cover and the aluminum shell and improve the quality of the battery cell. Among them, when the length of the short side is appropriate, the secondary welding path of the short side can cover the intersection area of ​​the short side and its adjacent side.

[0075] In one embodiment, the long side primary welding path, the short side primary welding path and the short side secondary welding path all include an acceleration path, an intermediate welding path and a deceleration path arranged in sequence, and the long side secondary welding path includes an acceleration path, an intermediate welding path, a transition path and a deceleration path arranged in sequence, and the transition path is a power attenuation path.

[0076] Specifically, Figure 5 , Figure 6 and Figure 7As shown, the long side primary welding path, the short side primary welding path and the short side secondary welding path all include three welding paths, namely, an acceleration path, an intermediate welding path and a deceleration path. The acceleration path, the intermediate welding path and the deceleration path are arranged in sequence according to the welding direction. The acceleration path is the path for accelerating the laser module when the laser is not turned on, the intermediate welding path is the path for the laser module to weld the end cover and the aluminum shell, and the deceleration path is the path for decelerating the laser module when the laser is turned off. In addition, the long side secondary welding path includes not only the acceleration path, the intermediate welding path and the deceleration path, but also a transition path, which is arranged between the intermediate welding path and the deceleration path. Therefore, the long side secondary welding path includes the acceleration path, the intermediate welding path, the transition path and the deceleration path arranged in sequence according to the welding direction. Among them, the transition path is the power attenuation path of the laser module. In this path, the power of the laser module gradually decays to zero to improve the pits formed by the laser module at the welding position and avoid the sealing failure caused by poor welding.

[0077] In one embodiment, the battery cell includes four edges to be welded connected end to end, and the battery cell welding method further includes:

[0078] Weld four ends of the welded edges in sequence in a clockwise or counterclockwise direction;

[0079] Specifically, Figure 3 As shown, the end cap and the aluminum shell of the battery cell include four edges to be welded, and the four edges to be welded are connected end to end. When welding the four edges, it is necessary to weld them in one direction, such as welding the four edges to be welded in a clockwise direction, or welding the four edges to be welded in a counterclockwise direction, so as to facilitate path planning and improve production cycle time, and further improve welding efficiency. After one edge to be welded is welded, the end cap and the aluminum shell are driven to rotate by a corresponding mechanism to facilitate welding the next edge to be welded.

[0080] The primary welding direction of any edge to be welded is end to end.

[0081] Specifically, the four edges to be welded are welded in turn in a counterclockwise or clockwise direction, and the welding direction of any edge to be welded is connected end to end, that is, the welding direction of the edges to be welded is also uniformly in a counterclockwise or clockwise direction, so as to facilitate path planning and improve production rhythm. Figure 3As shown, taking the counterclockwise direction as an example, the four edges to be welded, a, b, c, and d, are welded in a counterclockwise direction, and the four edges to be welded are welded in a counterclockwise direction. In addition, according to the welding method of the present application, A and C are welded four times in total, and B and D are welded three times in total. By using the same welding direction, the number of welds at the four corners of A, B, C, and D can be relatively uniform, so that the sealing ability of the welding points of the battery cell is relatively uniform.

[0082] In one embodiment, before performing a primary welding on the edge to be welded according to a primary welding direction and performing a secondary welding on the edge to be welded according to a secondary welding direction, the battery core welding method further comprises:

[0083] The defocus modes of the primary welding and the secondary welding are set so that the primary welding and the secondary welding are in a negative defocus mode.

[0084] Specifically, laser welding includes two modes: positive defocus and negative defocus. The laser welding of the present application adopts the negative defocus mode. Positive defocus means that the focus of the laser module is higher than the surface of the workpiece, and negative defocus means that the focus of the laser module is lower than the surface of the workpiece. Therefore, the present application sets the defocus mode so that both the primary welding and the secondary welding are in the negative defocus mode, and sets the defocus amount. Furthermore, the four corners of the end cover and the aluminum shell of the present application are rounded corners. Therefore, there is a change in the defocus amount when the laser module passes through the rounded corner. In order to ensure the welding quality at the rounded corner, the present application adopts the negative defocus mode, that is, the focus of the laser module is lower than the surface of the workpiece. Therefore, when the laser module passes through the rounded corner, the part to be welded at the rounded corner gradually moves away from the surface of the workpiece, that is, the part to be welded at the rounded corner gradually approaches the focus, and the laser energy of the laser module increases, which can ensure the welding quality of the laser module at the rounded corner. If the positive defocus method is used, when the laser module passes through the fillet, the part to be welded at the fillet gradually moves away from the workpiece surface, and the part to be welded at the fillet gradually moves away from the focus, then the laser energy at the part to be welded at the fillet gradually decreases, which will lead to poor welding at the part to be welded at the fillet, which will increase the number of pores and increase the probability of failing the helium test. Therefore, in the negative defocus mode, the distance between the focus and the workpiece surface must be greater than the radius of the fillet to ensure the welding quality and sealing performance. In addition, the focus position can be adjusted by adjusting the Z direction between the laser module and the edge to be welded.

[0085] Embodiment 2

[0086] Reference Figure 2 As shown, Figure 2 This is a flow chart of the second method of the battery core welding method provided in the embodiment of the present application. Figure 2 In the method shown, Figure 1 For the same or similar contents in the method shown, please refer to Figure 1The description in the method will not be repeated here.

[0087] S201, setting the defocus mode of the primary welding and the secondary welding so that the primary welding and the secondary welding are in a negative defocus mode;

[0088] The present application sets the defocus mode so that both the primary welding and the secondary welding are in a negative defocus mode, and sets the defocus amount so that the distance between the focus and the workpiece surface is greater than the radius of the fillet.

[0089] S202, determining a primary welding direction of a first long side as a first direction;

[0090] The edges to be welded are divided into two long edges and two short edges, namely, the first long edge, the first short edge, the second long edge and the second short edge. The first long edge is Figure 3 The first short side of the side to be welded is Figure 3 The second longest side of the side to be welded is Figure 3 The side to be welded c in the figure has the second shortest side. Figure 3 Therefore, the primary welding direction of the first long side is first determined, and the primary welding direction of the first long side is defined as the first direction, such as Figure 5 Welding direction of the long side shown.

[0091] S203, performing path planning for the first long side according to the first direction to form a first long side primary welding path, and obtaining welding parameters corresponding to the first long side primary welding path;

[0092] The path of the first long side is planned according to the primary welding direction of the first long side, so as to perform a primary welding on the end cover and the first long side of the aluminum shell according to the optimal path, thereby improving the welding efficiency. In addition, after the primary welding path of the first long side is determined, the process parameters of the primary welding path of the first long side are set, that is, the welding parameters corresponding to the primary welding path of the first long side are determined, so as to perform a primary welding on the end cover and the first long side of the aluminum shell according to the primary welding path of the first long side and its corresponding welding parameters.

[0093] S204, performing a primary welding on the first long side according to a primary welding path of the first long side and corresponding welding parameters;

[0094] After determining the primary welding path of the first long side and its corresponding welding parameters, the first long side is welded once according to the primary welding path of the first long side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the primary welding path of the first long side is X1, X2, X3, X4, and the welding parameters are as follows: Figure 6As shown. The first long side one-time welding path includes an acceleration path, an intermediate welding path and a deceleration path. The acceleration path of the first long side one-time welding path is the X1-X2 segment, the intermediate welding path of the first long side one-time welding path is the X2-X3 segment, the laser module starts to emit light from X2, the welding speed is v, and the deceleration path of the first long side one-time welding path is the X3-X4 segment. The laser module stops emitting light from X3 and starts to decelerate according to the gradient, and the speed drops to zero at X4.

[0095] S205, determining that the secondary welding direction of the first long side is a second direction, where the second direction is the opposite direction of the first direction;

[0096] like Figure 5 As shown, after the first welding of the first long side is completed, the first long side is subjected to secondary welding. First, the secondary welding direction of the first long side is determined to be the second direction, and the second direction is the opposite direction of the first direction, that is, the first long side is subjected to reflow welding.

[0097] S206, performing path planning for the first long side according to the second direction to form a secondary welding path for the first long side, and obtaining welding parameters corresponding to the secondary welding path for the first long side;

[0098] The path of the first long side is planned according to the secondary welding direction of the first long side, so as to perform secondary welding on the end cover and the first long side of the aluminum shell according to the optimal path, thereby improving welding efficiency. In addition, after determining the secondary welding path of the first long side, the process parameters of the secondary welding path of the first long side are set, that is, the welding parameters corresponding to the secondary welding path of the first long side are determined, so as to perform secondary welding on the end cover and the first long side of the aluminum shell according to the secondary welding path of the first long side and its corresponding welding parameters.

[0099] S207, performing secondary welding on the first long side according to the secondary welding path of the first long side and its corresponding welding parameters;

[0100] After determining the secondary welding path of the first long side and its corresponding welding parameters, the first long side is subjected to secondary welding according to the secondary welding path of the first long side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the secondary welding path of the first long side is X4, X3, X5, X6, X7, and the welding parameters are as follows Figure 6As shown. The secondary welding path of the first long side includes an acceleration path, an intermediate welding path, a transition path and a deceleration path. The acceleration path of the secondary welding path of the first long side is the X4-X3 segment, the intermediate welding path of the secondary welding path of the first long side is the X3-X5 segment, the laser module starts to emit light from X3, the welding speed is v, the transition path of the secondary welding path of the first long side is the X5-X6 segment, the power of the laser module starts to decay according to the gradient from X5, and the power drops to zero at X6, and the light stops emitting. The deceleration path of the secondary welding path of the first long side is the X6-X7 segment, the laser module starts to decelerate according to the gradient from X6, and the speed drops to zero at X7.

[0101] S208, determining the primary welding direction of the first short side as the third direction;

[0102] like Figure 5 As shown, after the secondary welding of the first long side is completed, the first short side is welded once, and firstly, the primary welding direction of the first short side is determined to be the third direction, which is perpendicular to the first direction.

[0103] S209, performing path planning for the first short side according to the third direction to form a first short side primary welding path, and obtaining welding parameters corresponding to the first short side primary welding path;

[0104] The path of the first short side is planned according to the primary welding direction of the first short side, so as to perform a primary welding on the end cover and the first short side of the aluminum shell according to the optimal path, thereby improving the welding efficiency. In addition, after the primary welding path of the first short side is determined, the process parameters of the primary welding path of the first short side are set, that is, the welding parameters corresponding to the primary welding path of the first short side are determined, so as to perform a primary welding on the end cover and the first short side of the aluminum shell according to the primary welding path of the first short side and its corresponding welding parameters.

[0105] S210, performing a primary welding on the first short side according to a primary welding path of the first short side and corresponding welding parameters;

[0106] After determining the primary welding path of the first short side and its corresponding welding parameters, the first short side is welded once according to the primary welding path of the first short side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the primary welding path of the first short side is Y1, Y2, Y3, Y4, and the welding parameters are as follows Figure 7The first short side welding path includes an acceleration path, an intermediate welding path and a deceleration path. The acceleration path of the first short side welding path is the Y1-Y2 segment, the intermediate welding path of the first short side welding path is the Y2-Y3 segment, the laser module starts to emit light from Y2, the welding speed is v, and the deceleration path of the first short side welding path is the Y3-Y4 segment. The laser module stops emitting light from Y3 and starts to decelerate according to the gradient, and the speed drops to zero at Y4.

[0107] S211, determining that the secondary welding direction of the first short side is a fourth direction, where the fourth direction is the opposite direction of the third direction;

[0108] like Figure 5 As shown, after the first welding of the first short side is completed, the first short side is subjected to secondary welding. First, the secondary welding direction of the first short side is determined to be the fourth direction, which is the opposite direction of the third direction, that is, the first short side is subjected to reflow welding.

[0109] S212, performing path planning on the first short side according to the fourth direction to form a first short side secondary welding path, and acquiring welding parameters corresponding to the first short side secondary welding path;

[0110] The path of the first short side is planned according to the secondary welding direction of the first short side, so as to perform secondary welding on the end cover and the first short side of the aluminum shell according to the optimal path, thereby improving welding efficiency. In addition, after the secondary welding path of the first short side is determined, the process parameters of the secondary welding path of the first short side are set, that is, the welding parameters corresponding to the secondary welding path of the first short side are determined, so as to perform secondary welding on the end cover and the first short side of the aluminum shell according to the secondary welding path of the first short side and its corresponding welding parameters.

[0111] S213, performing secondary welding on the first short side according to the secondary welding path of the first short side and its corresponding welding parameters.

[0112] After determining the secondary welding path of the first short side and its corresponding welding parameters, the first short side is subjected to secondary welding according to the secondary welding path of the first short side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the secondary welding path of the first short side is Y4, Y3, Y2, Y1, and the welding parameters are as follows Figure 7 The secondary welding path of the first short side includes an acceleration path, an intermediate welding path and a deceleration path. The acceleration path of the secondary welding path of the first short side is the Y4-Y3 segment, the intermediate welding path of the secondary welding path of the first short side is the Y3-Y2 segment, the laser module starts to emit light from Y3, the welding speed is v, and the deceleration path of the secondary welding path of the first short side is the Y2-Y1 segment. The laser module stops emitting light from Y2 and starts to decelerate according to the gradient, and the speed drops to zero at Y1.

[0113] S214, determining the primary welding direction of the second long side as the second direction;

[0114] like Figure 5 As shown, after the secondary welding of the first short side is completed, the second long side is welded once, and firstly, the primary welding direction of the first long side is determined to be the second direction.

[0115] S215, performing path planning for the second long side according to the second direction to form a primary welding path for the second long side, and obtaining welding parameters corresponding to the primary welding path for the second long side;

[0116] The path planning for the primary welding of the second long side is performed according to the primary welding direction of the second long side, so as to perform the primary welding of the end cover and the second long side of the aluminum shell according to the optimal path, thereby improving the welding efficiency. In addition, after the primary welding path of the second long side is determined, the process parameters of the primary welding path of the second long side are then set, that is, the welding parameters corresponding to the primary welding path of the second long side are determined, so as to perform the primary welding of the end cover and the second long side of the aluminum shell according to the primary welding path of the second long side and its corresponding welding parameters.

[0117] S216, performing a primary welding on the second long side according to the primary welding path of the second long side and its corresponding welding parameters;

[0118] After determining the first welding path of the second long side and its corresponding welding parameters, the second long side is welded once according to the first welding path of the second long side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the primary welding path of the second long side is U1, U2, U3, U4, and the welding parameters are as follows Figure 6 As shown. The first welding path of the second long side includes an acceleration path, an intermediate welding path and a deceleration path. The acceleration path of the first welding path of the second long side is the U1-U2 segment, the intermediate welding path of the first welding path of the second long side is the U2-U3 segment, the laser module starts to emit light from U2, the welding speed is v, and the deceleration path of the first welding path of the second long side is the U3-U4 segment. The laser module stops emitting light from U3 and starts to decelerate according to the gradient, and the speed drops to zero at U4.

[0119] S217, determining the secondary welding direction of the second long side as the first direction;

[0120] like Figure 5 As shown, after the first welding of the second long side is completed, the second long side is welded for the second time, and firstly, the secondary welding direction of the second long side is determined to be the first direction.

[0121] S218, performing path planning for the second long side according to the first direction to form a secondary welding path for the second long side, and acquiring welding parameters corresponding to the secondary welding path for the second long side;

[0122] The path of the second long side is planned according to the secondary welding direction of the second long side, so as to perform secondary welding on the second long side of the end cover and the aluminum shell according to the optimal path, thereby improving welding efficiency. In addition, after the secondary welding path of the second long side is determined, the process parameters of the secondary welding path of the second long side are set, that is, the welding parameters corresponding to the secondary welding path of the second long side are determined, so as to perform secondary welding on the second long side of the end cover and the aluminum shell according to the secondary welding path of the second long side and its corresponding welding parameters.

[0123] S219, performing secondary welding on the second long side according to the secondary welding path of the second long side and its corresponding welding parameters;

[0124] After determining the secondary welding path of the second long side and its corresponding welding parameters, the second long side is subjected to secondary welding according to the secondary welding path of the second long side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the secondary welding paths of the second long side are U4, U3, U5, U6, and U7, and the welding parameters are as follows: Figure 6 As shown. The secondary welding path of the second long side includes an acceleration path, an intermediate welding path, a transition path and a deceleration path. The acceleration path of the secondary welding path of the second long side is the U4-U3 segment, the intermediate welding path of the secondary welding path of the second long side is the U3-U5 segment, the laser module starts to emit light from U3, the welding speed is v, the transition path of the secondary welding path of the second long side is the U5-U6 segment, the power of the laser module starts to decay according to the gradient from U5, and the power drops to zero at U6, and the light emission stops. The deceleration path of the secondary welding path of the second long side is the U6-U7 segment, the laser module starts to decelerate according to the gradient from U6, and the speed drops to zero at U7.

[0125] S220, determining the primary welding direction of the second short side as a fourth direction;

[0126] like Figure 5 As shown, after the secondary welding of the second long side is completed, the second short side is welded once, and firstly, the primary welding direction of the second short side is determined to be the fourth direction.

[0127] S221, performing path planning for the second short side according to the fourth direction to form a primary welding path for the second short side, and obtaining welding parameters corresponding to the primary welding path for the second short side;

[0128] The path planning for the primary welding of the second short side is performed according to the primary welding direction of the second short side, so as to perform the primary welding of the end cover and the second short side of the aluminum shell according to the optimal path, thereby improving the welding efficiency. In addition, after the primary welding path of the second short side is determined, the process parameters of the primary welding path of the second short side are then set, that is, the welding parameters corresponding to the primary welding path of the second short side are determined, so as to perform the primary welding of the end cover and the second short side of the aluminum shell according to the primary welding path of the second short side and its corresponding welding parameters.

[0129] S222, performing a primary welding on the second short side according to the primary welding path of the second short side and its corresponding welding parameters;

[0130] After determining the primary welding path of the second short side and its corresponding welding parameters, the second short side is welded once according to the primary welding path of the second short side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the primary welding path of the second short side is V1, V2, V3, V4, and the welding parameters are as follows Figure 7 As shown. The first welding path of the second short side includes an acceleration path, an intermediate welding path and a deceleration path. The acceleration path of the first welding path of the second short side is the V1-V2 segment, the intermediate welding path of the first welding path of the second short side is the V2-V3 segment, the laser module starts to emit light from V2, the welding speed is v, and the deceleration path of the first welding path of the second short side is the V3-V4 segment. The laser module stops emitting light from V3 and starts to decelerate according to the gradient, and the speed drops to zero at V4.

[0131] S223, determining that the secondary welding direction of the second short side is the third direction;

[0132] like Figure 5 As shown, after the first welding of the second short side is completed, the second short side is subjected to a second welding. First, the secondary welding direction of the second short side is determined to be the third direction, that is, the second short side is subjected to a reflow welding.

[0133] S224, performing path planning for the second short side according to the third direction to form a secondary welding path for the second short side, and acquiring welding parameters corresponding to the secondary welding path for the second short side;

[0134] The secondary welding path of the second short side is planned according to the secondary welding direction of the second short side, so as to perform secondary welding on the second short side of the end cover and the aluminum shell according to the optimal path, thereby improving welding efficiency. In addition, after the secondary welding path of the second short side is determined, the process parameters of the secondary welding path of the second short side are set, that is, the welding parameters corresponding to the secondary welding path of the second short side are determined, so as to perform secondary welding on the second short side of the end cover and the aluminum shell according to the secondary welding path of the second short side and its corresponding welding parameters.

[0135] S225, performing secondary welding on the second short side according to the secondary welding path of the second short side and its corresponding welding parameters.

[0136] After determining the secondary welding path of the second short side and its corresponding welding parameters, the second short side is subjected to secondary welding according to the secondary welding path of the second short side and its corresponding welding parameters, so as to weld the end cover and the aluminum shell together. Figure 5 As shown, the secondary welding path of the second short side is V4, V3, V2, V1, and the welding parameters are as follows Figure 7 The secondary welding path of the second short side includes an acceleration path, an intermediate welding path and a deceleration path. The acceleration path of the secondary welding path of the second short side is the V4-V3 segment, the intermediate welding path of the secondary welding path of the second short side is the V3-V2 segment, the laser module starts to emit light from V3, the welding speed is v, and the deceleration path of the secondary welding path of the second short side is the V2-V1 segment. The laser module stops emitting light from V2 and starts to decelerate according to the gradient, and the speed drops to zero at V1.

[0137] S226, welding is completed.

[0138] After the four edges to be welded, that is, the two long edges and the two short edges are welded, the welding of the end cover and the aluminum shell at this location is completed, and the welding of the end cover and the aluminum shell at the next location can be continued.

[0139] It should be understood that although Figure 1-2 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1-2 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0140] Embodiment 3

[0141] The electric core welding system of this embodiment includes:

[0142] A control module is used to determine the edge to be welded of the battery cell, determine the primary welding direction and the secondary welding direction of the edge to be welded, and determine the intersection area formed by any two adjacent edges to be welded;

[0143] When welding between the aluminum shell and the end cover of the battery cell using the battery cell welding system of the present application, the four sides to be welded of the battery cell, i.e., two long sides and two short sides, must first be determined. This can be programmed through a control module, or the control module includes an image unit, which automatically identifies the four sides to be welded through the image unit, and automatically identifies the intersection area of ​​two sides to be welded through the image unit, i.e., the intersection area where the long side and the short side intersect. In addition, the primary welding direction and the secondary welding direction must be determined through a control module or program, so that the sides to be welded can be welded according to the primary welding direction and the secondary welding direction.

[0144] The welding module performs primary welding on the edge to be welded according to a primary welding direction, and performs secondary welding on the edge to be welded according to a secondary welding direction. The primary welding direction is opposite to the secondary welding direction, and both the primary welding and the secondary welding cover the intersection area.

[0145] After the control module determines the edge to be welded, the primary welding direction and the secondary welding direction, the welding module performs a primary welding on the edge to be welded according to the primary welding direction, and performs a secondary welding on the edge to be welded according to the secondary welding direction, so as to remelt the position where the first welding was done between the aluminum shell and the end cover, improve the density of the weld, reduce the number of pores at the weld, so as to improve the sealing performance between the aluminum shell and the end cover.

[0146] In one embodiment, the welding system further includes a laser module, the welding module includes a welding copper nozzle, and the laser of the laser module is transmitted to the welding copper nozzle to perform primary welding or secondary welding on the battery cell through the welding copper nozzle.

[0147] The welding system of the present application adopts a laser module to weld the edges to be welded between the end cover and the aluminum cover by laser. Figure 8 As shown, the welding module includes a welding copper nozzle 2, and the laser 1 of the laser module is transmitted to the welding copper nozzle 2 through a laser transmission line, so as to weld the edge to be welded between the end cover and the aluminum shell through the welding copper nozzle 2. Among them, a dust removal device 3 is provided on the welding copper nozzle 2, and the dust removal device 3 is used to absorb the dust generated during the welding process through negative pressure to improve the welding quality. In addition, the laser module uses two laser beams, the two laser beams are coaxial, and the laser power of the laser beam located in the center is less than the laser power of the laser beam located in the outer ring, so as to form an inverted cone molten pool, which is conducive to gas discharge and improves the welding effect. The welding copper nozzle 2 is moved by the X, Y, and Z servo drive mechanism to perform welding according to the welding path. The moving speed and laser power of the welding copper nozzle 2 are controlled by PLC.

[0148] For the specific limitations of the battery cell welding system, reference may be made to the limitations on the method in the foregoing text, which will not be elaborated herein. Each module in the above battery cell welding system can be implemented in whole or in part by software, hardware, and their combination. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory of the computer device in the form of software, so as to facilitate the processor to call and execute the operations corresponding to each of the above modules.

[0149] Embodiment 4

[0150] This embodiment provides a battery cell, including a weld formed by using the battery cell welding method or the battery cell welding system. Specifically, the edges to be welded between the end cap and the aluminum shell are welded by using the battery cell welding method or the battery cell welding system to form a weld. The primary weld is remelted by secondary welding, which improves the density of the weld, reduces the number of weld pores, and improves the sealing performance between the aluminum shell and the end cap. Moreover, the appearance of pits in the secondary welding between the end cap and the aluminum shell is avoided, further improving the sealing performance between the aluminum shell and the end cap.

[0151] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0152] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A battery core welding method, characterized in that: The battery core welding method comprises: Determine the edges to be welded of the battery core and determine the primary welding direction and the secondary welding direction of the edges to be welded, and any two adjacent edges to be welded form an intersection area; The edge to be welded is welded once in the primary welding direction, and welded twice in the secondary welding direction. The primary welding direction is opposite to the secondary welding direction. Both the primary welding and the secondary welding cover the intersection area.

2. The battery core welding method according to claim 1, characterized in that: The performing of primary welding on the edge to be welded according to the primary welding direction, and performing secondary welding on the edge to be welded according to the secondary welding direction, comprises: Performing path planning for the edge to be welded according to the primary welding direction and the secondary welding direction to form a welding path, and determining welding parameters corresponding to the welding path; The primary welding and the secondary welding are performed on the edge to be welded according to the welding path and the corresponding welding parameters.

3. The battery core welding method according to claim 2, characterized in that: The side to be welded is a long side, and welding the side to be welded once according to the primary welding direction comprises: Performing path planning on the long side according to the primary welding direction to form a long side primary welding path, and acquiring the welding parameters corresponding to the long side primary welding path, wherein the long side primary welding path covers the welding area of ​​the long side; The long side is welded once according to the long side primary welding path and the corresponding welding parameters.

4. The battery core welding method according to claim 3, characterized in that: The secondary welding of the edge to be welded according to the secondary welding direction comprises: Performing path planning on the long side according to the secondary welding direction to form a long side secondary welding path, and acquiring the welding parameters corresponding to the long side secondary welding path, wherein the long side secondary welding path covers an intersection area between the long side and its adjacent side; The secondary welding is performed on the long side according to the long side secondary welding path and the corresponding welding parameters.

5. The battery core welding method according to claim 4, characterized in that: The side to be welded is a short side, and the side to be welded is welded once according to the primary welding direction, and the side to be welded is welded twice according to the secondary welding direction, including: Performing path planning on the short side according to the primary welding direction to form a short side primary welding path, and acquiring the welding parameters corresponding to the short side primary welding path; Performing path planning on the short side according to the secondary welding direction to form a short side secondary welding path, and acquiring the welding parameters corresponding to the short side secondary welding path; The short side is welded once according to the short side primary welding path and the corresponding welding parameters, and the short side is welded twice according to the short side secondary welding path and the corresponding welding parameters; the short side primary welding path and the short side secondary welding path both cover the intersection area between the short side and its adjacent side or cover the welding area of ​​the short side.

6. The battery core welding method according to claim 5, characterized in that: The long side primary welding path, the short side primary welding path and the short side secondary welding path all include an acceleration path, an intermediate welding path and a deceleration path arranged in sequence; the long side secondary welding path includes an acceleration path, an intermediate welding path, a transition path and a deceleration path arranged in sequence; and the transition path is a power attenuation path.

7. The battery core welding method according to claim 1, characterized in that: The battery core comprises four edges to be welded connected end to end, and the battery core welding method further comprises: Welding the four ends of the edges to be welded in sequence in a clockwise or counterclockwise direction; The primary welding direction of any of the edges to be welded is connected end to end.

8. The battery core welding method according to claim 1, characterized in that: Before performing a primary welding on the edge to be welded according to the primary welding direction and performing a secondary welding on the edge to be welded according to the secondary welding direction, the battery core welding method further comprises: The defocus modes of the primary welding and the secondary welding are set so that the primary welding and the secondary welding are in a negative defocus mode.

9. An electric core welding system for implementing the electric core welding method according to any one of claims 1 to 8, characterized in that: The electric core welding system comprises: A control module, used to determine the edge to be welded of the battery cell, determine the primary welding direction and the secondary welding direction of the edge to be welded, and determine the intersection area formed by any two adjacent edges to be welded; The welding module is used to perform a primary welding on the edge to be welded according to the primary welding direction, and to perform a secondary welding on the edge to be welded according to the secondary welding direction. The primary welding direction is opposite to the secondary welding direction, and both the primary welding and the secondary welding cover the intersection area.

10. A battery cell, characterized in that: A weld formed by welding using the electric core welding method according to any one of claims 1 to 8, or a weld formed by welding using the electric core welding system according to claim 9.

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