Assembly method of bare battery cell and battery single body

Abstract

The present application discloses an assembly method for a bare battery cell and a battery monomer, relating to the technical field of battery manufacturing. This assembly method is used to assemble at least two bare battery cells with a top cover structure. The assembly method includes the following steps: stacking the tabs of the first bare battery cell onto the pole column; stacking the tabs of the second bare battery cell onto the tabs of the first bare battery cell so that the pole column, the tabs of the first bare battery cell, and the tabs of the second bare battery cell are stacked in sequence; integrally welding and fixing the pole column, the tabs of the first bare battery cell, and the tabs of the second bare battery cell stacked in sequence by ultrasonic welding. This assembly method can integrally weld and fix the tabs of the first and second bare battery cells and the pole column of the top cover structure by ultrasonic welding, enabling the tabs of the first bare battery cell and the tabs of the second bare battery cell to be directly fixed to the top cover structure, reducing the limitation of the current density by the jumper and its weld seam, and being beneficial to improving the energy density of the corresponding battery monomer.

Description

Technical Field

[0001] This application relates to the technical field of battery manufacturing, and particularly relates to an assembly method for a bare battery cell and a battery monomer. Background Art

[0002] During the production process of batteries such as lithium batteries and sodium batteries, usually one or more than two bare battery cells containing positive and negative electrode materials are placed into a battery housing, and then the bare battery cells and a top cover structure are respectively connected through connecting tabs, and the top cover structure is welded to the battery housing to assemble and form a battery monomer.

[0003] Among them, the energy density of the battery monomer is usually improved by improving the positive and negative electrode materials and the materials of the top cover structure, but the energy density of the battery monomer still needs to be further improved. Summary of the Invention

[0004] The main purpose of this application is to propose an assembly method for a bare battery cell, aiming to improve the energy density of the corresponding battery monomer.

[0005] To achieve the above purpose, the assembly method for a bare battery cell proposed in this application is used to assemble at least two bare battery cells with a top cover structure. The bare battery cell includes a tab, and the top cover structure includes a terminal post. The assembly method includes the following steps:

[0006] Stack the tab of the first bare battery cell on the terminal post;

[0007] Stack the tab of the second bare battery cell on the tab of the first bare battery cell, so that the terminal post, the tab of the first bare battery cell, and the tab of the second bare battery cell are stacked in sequence;

[0008] For the terminal post, the tab of the first bare battery cell, and the tab of the second bare battery cell stacked in sequence, respectively abut against the side of the terminal post facing away from the tab of the second bare battery cell and the side of the tab of the second bare battery cell facing away from the terminal post;

[0009] The step of respectively abutting against the side of the terminal post facing away from the tab of the second bare battery cell and the side of the tab of the second bare battery cell facing away from the terminal post for the terminal post, the tab of the first bare battery cell, and the tab of the second bare battery cell stacked in sequence includes:

[0010] Abut against the side of the terminal post facing away from the tab of the second bare battery cell through an ultrasonic welding base;

[0011] Abut against the side of the tab of the second bare battery cell facing away from the terminal post through an ultrasonic welding head;

[0012] The assembly method further includes the following steps:

[0013] A boss is formed at one end of the ultrasonic welding seat facing the top cover structure;

[0014] A cavity is formed on one side of the top cover structure facing away from the tab of the second bare battery cell;

[0015] The step of abutting the ultrasonic welding seat against the side of the pole column facing away from the tab of the second bare battery cell includes:

[0016] Insert the boss into the cavity and make the side wall surface of the boss abut against the side wall surface of the cavity;

[0017] The pole column, the tab of the first bare battery cell, and the tab of the second bare battery cell that are stacked in sequence are integrally welded and fixed by ultrasonic welding.

[0018] When the assembly method of the bare battery cell in the technical solution of the present application is used, the assembly method can integrally weld and fix the tab of the first bare battery cell, the tab of the second bare battery cell, and the pole column of the top cover structure by ultrasonic welding, so that the tab of the first bare battery cell and the tab of the second bare battery cell are directly fixed to the top cover structure, reducing the limitation of the current density by the connecting piece and its weld seam, which is beneficial to improving the energy density of the corresponding battery cell. In addition, the assembly method can reduce the use requirement of the connecting piece and reduce the corresponding welding process, improve the assembly efficiency, and reduce the overall manufacturing cost.

[0019] In addition, the assembly method improves the position stability of the tab of the first bare battery cell, the tab of the second bare battery cell, and the pole column of the top cover structure during the welding process by respectively abutting against the side of the pole column facing away from the tab of the second bare battery cell and the side of the tab of the second bare battery cell facing away from the pole column, which is beneficial to improving the weld quality between the tab of the first bare battery cell, the tab of the second bare battery cell, and the pole column of the top cover structure, beneficial to reducing the limitation of the weld quality on the current density, and beneficial to improving the energy density of the corresponding battery cell.

[0020] In addition, the assembly method reduces the risk of the top cover structure moving relative to the ultrasonic welding base by embedding the boss into the concave cavity and making the side wall surface of the boss abut against the side wall surface of the concave cavity, reduces the energy consumed between the ultrasonic welding base and the top cover structure, makes the welding energy more concentrated between the top cover structure and the tab, and reduces the risk of false soldering between the top cover structure and the tab. In addition, since the risk of the top cover structure moving relative to the ultrasonic welding base is reduced, the risk of the boss on the end face of the ultrasonic welding base being worn by the top cover structure is reduced, the overall service life of the ultrasonic welding base is longer, thereby reducing the replacement frequency of the ultrasonic welding base and reducing the overall use cost of the ultrasonic welding base; on the other hand, the risk of the boss being worn by the top cover structure is reduced, and the dust formed between the top cover structure and the ultrasonic welding base is reduced, which is beneficial to improving the overall quality of the corresponding battery cell.

[0021] Optionally, for the pole column, the tab of the first bare battery cell, and the tab of the second bare battery cell that are sequentially stacked, the steps of respectively abutting against the side of the pole column facing away from the tab of the second bare battery cell and the side of the tab of the second bare battery cell facing away from the pole column include:

[0022] Abutting against the side of the pole column facing away from the tab of the second bare battery cell through the ultrasonic welding base;

[0023] Abutting against the side of the tab of the second bare battery cell facing away from the pole column through the ultrasonic welding head;

[0024] The step of integrally welding and fixing the pole column, the tab of the first bare battery cell, and the tab of the second bare battery cell that are sequentially stacked through ultrasonic welding includes:

[0025] Making the vibration direction of the ultrasonic welding head parallel to the surface of the tab and intersecting the height direction of the tab.

[0026] At this time, the assembly method makes the vibration direction of the ultrasonic welding head parallel to the surface of the tab and intersects the height direction of the tab, thereby facilitating the arrangement of the ultrasonic welding head by using the space between the first bare battery cell and the second bare battery cell, increasing the movement space for the vibration of the ultrasonic welding head, and reducing the risk of the ultrasonic welding head accidentally bumping into the bare battery cell.

[0027] Optionally, the assembly method further includes the following steps:

[0028] Making the side wall surface of the boss have a first inclined wall surface section;

[0029] Making the side wall surface of the concave cavity have a second inclined wall surface section;

[0030] The step of embedding the boss into the concave cavity and making the side wall surface of the boss abut against the side wall surface of the concave cavity includes:

[0031] Make the first inclined wall surface section abut against the second inclined wall surface section, and move the ultrasonic welding seat and the top cover structure relative to each other along the surface of the top cover structure.

[0032] At this time, the assembly method is conducive to accommodating the positioning deviation between the ultrasonic welding seat and the top cover structure and improving the alignment degree between the ultrasonic welding seat and the top cover structure by making the first inclined wall surface section abut against the second inclined wall surface section and moving the ultrasonic welding seat and the top cover structure relative to each other along the surface of the top cover structure.

[0033] Optionally, the assembly method further includes the following steps:

[0034] Make the side wall surface of the boss have a first flat wall surface section;

[0035] Make the side wall surface of the cavity have a second flat wall surface section;

[0036] The step of embedding the boss into the cavity and making the side wall surface of the boss abut against the side wall surface of the cavity includes:

[0037] Make the first flat wall surface section abut against the second flat wall surface section;

[0038] The step of integrally welding and fixing the pole column, the tab of the first bare battery cell, and the tab of the second bare battery cell that are sequentially stacked includes:

[0039] Make the vibration direction of the ultrasonic welding head parallel to the surface of the tab and intersect with the height direction of the tab, and make the vibration direction of the ultrasonic welding head intersect with the first flat wall surface section.

[0040] At this time, the assembly method reduces the local pressure of the vibrating ultrasonic welding head on the boss, reduces the risk of the top of the boss being worn by the top cover structure, reduces the risk of virtual soldering caused by relative movement between the top cover structure and the ultrasonic welding seat, and reduces the risk of dust formation due to wear by making the vibration direction of the ultrasonic welding head parallel to the surface of the tab and intersect with the height direction of the tab, and making the vibration direction of the ultrasonic welding head intersect with the first flat wall surface section.

[0041] Optionally, the assembly method further includes the following steps:

[0042] Make the dimension of the root of the boss in a preset direction larger than the dimension of the mouth of the cavity in the preset direction, and the preset direction is perpendicular to the height direction of the boss.

[0043] At this time, the assembly method makes the dimension of the root of the boss in the preset direction larger than the dimension of the mouth of the concave cavity in the preset direction, so that the root of the boss can be embedded into the mouth of the concave cavity by means of elastoplastic deformation, so that an interference fit is formed between the root of the boss and the mouth of the concave cavity, improving the connection stability between the ultrasonic welding seat and the top cover structure and further reducing the risk of false soldering caused by the movement of the top cover structure relative to the ultrasonic welding seat.

[0044] Optionally, the step of embedding the boss into the concave cavity and making the side wall surface of the boss abut against the side wall surface of the concave cavity includes:

[0045] Embedding the root of the boss into the concave cavity and making the surface of the ultrasonic welding seat facing the top cover structure abut against the top cover structure.

[0046] At this time, the assembly method embeds the root of the boss into the concave cavity and makes the surface of the ultrasonic welding seat facing the top cover structure abut against the top cover structure, thereby improving the connection stability between the ultrasonic welding seat and the top cover structure and further reducing the risk of false soldering caused by the movement of the top cover structure relative to the ultrasonic welding seat.

[0047] Optionally, one end of the ultrasonic welding head facing the tab of the second bare battery cell is provided with welding teeth. The step of forming a boss at one end of the ultrasonic welding seat facing the top cover structure includes:

[0048] Making the cross-sectional area of the root of the boss larger than the cross-sectional area of the root of the welding teeth.

[0049] At this time, the assembly method makes the cross-sectional area of the root of the boss larger than the cross-sectional area of the root of the welding teeth, so that the area of the top of the boss is relatively large, further reducing the risk of the top of the boss being worn by the top cover structure, further reducing the risk of false soldering caused by the relative movement between the top cover structure and the ultrasonic welding seat, and reducing the risk of forming dust due to wear.

[0050] Optionally, the assembly method further includes the following steps:

[0051] Providing a support plate, wherein a groove is provided on the surface of the support plate, and a through hole is provided on the bottom wall of the groove;

[0052] Placing the top cover structure into the groove and making the side of the top cover structure provided with the concave cavity face the through hole.

[0053] At this time, the assembly method places the top cover structure into the groove, and makes the side of the top cover structure with the concave cavity face the through hole, so that the top cover structure can be positioned by the convex platform of the ultrasonic welding seat through the concave cavity. Since the acting force on the support plate due to welding vibration is reduced, it is beneficial to enable the support plate to have sufficient structural strength when there is a groove, and it is beneficial to improve the positioning efficiency of the top cover structure through the groove of the support plate. In addition, after the top cover structure is placed into the groove, the surface flatness between the top cover structure and the support plate is higher, which is beneficial to reducing the risk of accidental bending of the tab.

[0054] Optionally, the assembly method further includes the following steps:

[0055] Making one end of the pole column protrude from the top cover structure;

[0056] The step of forming a concave cavity on the side of the top cover structure facing away from the tab of the second bare battery cell includes:

[0057] Forming the concave cavity on the end face of the end of the pole column protruding from the top cover structure.

[0058] At this time, the assembly method forms a concave cavity on the end face of the end of the pole column protruding from the top cover structure, so that the pole column can be fixed by the convex platform of the ultrasonic welding seat through the concave cavity, thereby improving the position stability of the tab of the first bare battery cell, the tab of the second bare battery cell and the pole column of the top cover structure during the welding process, which is beneficial to improving the weld quality between the tab of the first bare battery cell, the tab of the second bare battery cell and the pole column of the top cover structure, beneficial to reducing the limitation of the weld quality on the current density, and beneficial to improving the energy density of the corresponding battery cell.

[0059] Optionally, the step of placing the top cover structure into the groove and making the side of the top cover structure with the concave cavity face the through hole includes:

[0060] Making the end of the pole column protruding from the top cover structure pass through the through hole and abut against the hole wall of the through hole.

[0061] At this time, the assembly method makes the end of the pole column protruding from the top cover structure pass through the through hole and abut against the hole wall of the through hole, which is beneficial to improving the positioning efficiency of the top cover structure through the groove of the support plate and beneficial to improving the overall assembly efficiency.

[0062] Optionally, the bare battery cell includes the tab and the cell body. The step of integrally welding and fixing the pole column, the tab of the first bare battery cell and the tab of the second bare battery cell arranged in a stacked manner by ultrasonic welding includes:

[0063] Make the width of the formed welding mark smaller than the distance from the welding mark to the cell body of one of the bare cells, and the width direction of the welding mark is consistent with the height direction of the tab.

[0064] At this time, by making the width of the formed welding mark smaller than the distance from the welding mark to the cell body of one of the bare cells, the assembly method is beneficial to reducing the influence of the vibration of ultrasonic welding on the connecting corners of the tab and the cell body, beneficial to reducing the risk that the connecting corners of the tab and the cell body are pulled and torn due to welding vibration, and beneficial to improving the overall quality of the corresponding battery cell.

[0065] The present application also provides a battery cell, which includes a battery housing, a top cover structure and at least two bare cells. The battery housing has an opening and a receiving cavity. The top cover structure is connected to the opening. The bare cells are received in the receiving cavity, and the bare cells are further assembled with the top cover structure by using the above-mentioned assembly method of the bare cells.

[0066] In the battery cell of the technical solution of the present application, the bare cells are assembled with the top cover structure by using the above-mentioned assembly method of the bare cells. The tabs of the first bare cell, the tabs of the second bare cell and the pole columns of the top cover structure can be integrally welded and fixed by ultrasonic welding, so that the tabs of the first bare cell and the tabs of the second bare cell are directly fixed to the top cover structure, reducing the limitation of the current density by the connecting piece and its weld seam, and being beneficial to improving the energy density of the corresponding battery cell. In addition, the battery cell can reduce the use requirement of the connecting piece and reduce the corresponding welding process, improve the assembly efficiency and reduce the overall manufacturing cost. Description of the Drawings

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0068] Figure 1 It is a schematic diagram of the connection between the tab of a bare cell and a connecting piece in the related art;

[0069] Figure 2 It is a schematic diagram of the welding between the tab of a bare cell and a connecting piece in the related art;

[0070] Figure 3 It is a schematic diagram of the connection between the connecting piece of a bare cell and the top cover structure in the related art;

[0071] Figure 4Schematic diagram corresponding to an embodiment of the method for assembling a bare battery cell provided in this application;

[0072] Figure 5 Schematic diagram of the connection between the tab and the top cover structure in a bottom view angle in an embodiment of this application;

[0073] Figure 6 Welding schematic diagram of the tab and the top cover structure in an embodiment of this application;

[0074] Figure 7 Partial schematic diagram of the welding of the tab and the top cover structure in an embodiment of this application;

[0075] Figure 8 Schematic diagram of the structure of an ultrasonic welding seat in an embodiment of this application;

[0076] Figure 9 Schematic diagram of the structure of an ultrasonic welding seat in another embodiment of this application;

[0077] Figure 10 Partial structure schematic diagram of the top cover structure in another embodiment of this application;

[0078] Figure 11 Top view of the welding of the tab and the top cover structure in an embodiment of this application;

[0079] Figure 12 is Figure 11 Cross-sectional view at the M-M position in;

[0080] Figure 13 is Figure 12 Partial enlarged view at the C position in;

[0081] Figure 14 Schematic diagram of the steps of an embodiment of the method for assembling a bare battery cell provided in this application;

[0082] Figure 15 Schematic diagram of the steps of another embodiment of the method for assembling a bare battery cell provided in this application.

[0083] Explanation of the reference numerals in the drawings:

[0084] 100, ultrasonic welding equipment;

[0085] 110, ultrasonic welding head; 111, welding teeth;

[0086] 120, ultrasonic welding seat; 121, boss; 122, first inclined wall surface section; 123, first flat wall surface section;

[0087] 130, support plate; 131, groove; 132, through hole; 133, limiting block;

[0088] 200. Plate to be welded; 201. Concave cavity; 202. Second inclined wall segment; 203. Second flat wall segment;

[0089] 210. Top cover structure; 211. Terminal post;

[0090] 300. Bare battery cell; 310. Tab; 311. Welding mark; 320. Cell body.

[0091] The realization of the purpose, functional features and advantages of this application will be further described in conjunction with the embodiments with reference to the accompanying drawings. Detailed implementation manners

[0092] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0093] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) involved in the embodiments of this application, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0094] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of this application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by this application.

[0095] During the production process of batteries such as lithium batteries and sodium batteries, usually one or two or more bare battery cells containing positive and negative electrode materials are placed into the battery housing, and then the bare battery cells and the top cover structure are respectively connected through connecting pieces, and the top cover structure is welded to the battery housing to assemble a battery monomer.

[0096] Among them, the energy density of a battery cell is usually improved by improving the materials of the positive and negative electrodes and the materials of the top cover structure. However, the energy density of the battery cell still needs to be further improved.

[0097] Referring to Figure 1 , Figure 2 and Figure 3 , in related technologies, an ultrasonic welding device generally includes an ultrasonic generator, a transducer, a horn, an ultrasonic welding head 110, and an ultrasonic welding base 120, where the ultrasonic welding head 110 and the ultrasonic welding base 120 are oppositely arranged. Among them, the ultrasonic welding device is also called an ultrasonic welding machine. The ultrasonic welding device converts an electric current of about 50 to 60 Hz into electric energy of about 15 kHz to 75 kHz through the ultrasonic generator; the converted high-frequency electric energy is converted into mechanical motion of the same frequency again through the transducer, and then the mechanical motion is transmitted to the ultrasonic welding head 110 through a horn and other horn devices that can change the amplitude, so as to form the vibration of the ultrasonic welding head 110; the ultrasonic welding head 110 transmits the received vibration energy to the joint of the workpiece to be welded (such as the above-mentioned tab 310 and adapter plate 220), and the vibration energy is converted into heat energy in this area by friction, so as to melt the two workpieces to be welded for welding, thereby forming a weld mark 311.

[0098] Referring to Figure 1 and Figure 3 , in related technologies, the tab 310 of the bare battery cell is usually welded to the adapter plate 220 first, and then the adapter plate 220 is welded to the top cover structure 210, and the bare battery cell, the top cover structure 210 and the battery case are assembled to form a battery cell. That is, related technologies include at least the weld between the tab 310 and the adapter plate 220, and the weld between the adapter plate 220 and the top cover structure 210. Among them, the adapter plate 220 and its weld are likely to limit the current density, resulting in a decrease in the energy density of the corresponding battery cell.

[0099] On the other hand, in related technologies, the adapter plate 220 is usually welded to the top cover structure 210 by a laser welding process. The laser welding process is likely to cause more welding slag metal particles to adhere to the surface of the adapter plate 220. Therefore, it is necessary to cover the welding slag metal particles by a dispensing process to prevent the welding slag metal particles from falling off during subsequent manufacturing or use, so as to prevent the falling welding slag metal particles from causing a battery short circuit and fire through the dispensing process.

[0100] Therefore, based on the above considerations, in order to improve the energy density of the corresponding battery cell, the present application proposes an assembly method for a bare battery cell. Among them, when the assembly method of the bare battery cell is used, it can reduce the limitation of the adapter plate and its weld on the current density, which is beneficial to improving the energy density of the corresponding battery cell.

[0101] Next, the assembly method of the bare battery cell proposed in the present application will be explained by specific embodiments.

[0102] Among them, referring to Figure 4 , Figure 5 and Figure 6 , the ultrasonic welding equipment 100 corresponding to the assembly method of the bare battery cell proposed in the present application may include an ultrasonic generator, a transducer, a horn, an ultrasonic welding head 110 and an ultrasonic welding base 120; referring to Figure 6 , the ultrasonic welding base 120 is disposed opposite to the ultrasonic welding head 110 of the ultrasonic welding equipment 100, for example, disposed opposite in the up-down direction in the figure, so that the ultrasonic welding head 110 and the ultrasonic welding base 120 can be further close to each other to compact the tab 310 and the adapter piece 220 of the bare battery cell 300, and then perform subsequent ultrasonic welding. Further, referring to Figure 7 , Figure 8 or Figure 9 , one end of the ultrasonic welding base 120 may be provided with a boss 121; referring to Figure 7 or Figure 10 , the boss 121 is used to be embedded in the cavity 201 on the top cover structure 210, and the side wall surface of the boss 121 is used to abut against the side wall surface of the cavity 201.

[0103] Referring to Figure 4 and Figure 14 , the assembly method of the bare battery cell 300 proposed in the present application is used to assemble at least two bare battery cells 300 with the top cover structure 210, wherein the bare battery cell 300 includes a tab 310 and a cell body 320, and the top cover structure 210 includes a terminal 211. It can be understood that the bare battery cell 300 having a tab 310 and a cell body 320 can be formed by processes such as winding and stacking.

[0104] Among them, the assembly method includes the following steps:

[0105] Step S100, stacking the tab 310 of the first bare battery cell 300 onto the terminal 211, which can be understood as making the thickness direction of the tab 310 consistent with the height direction of the terminal 211 and making the two abut against each other;

[0106] Step S200: Stack the tab 310 of the second bare battery cell 300 on the tab 310 of the first bare battery cell 300, so that the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 are stacked in sequence, thereby facilitating the formation of weld seams between the pole column 211 and the tab 310 of the first bare battery cell 300 and between the tab 310 of the first bare battery cell 300 and the tab 310 of the second bare battery cell 300 through the same ultrasonic welding process. Among them, the top cover structure 210 including the pole column 211 in this stage can be understood as the to-be-welded plate 200 to be welded. Stacking the tab 310 of the second bare battery cell 300 on the tab 310 of the first bare battery cell 300 can be understood as making the thickness directions of the tab 310 of the second bare battery cell 300 and the tab 310 of the first bare battery cell 300 consistent and making them abut against each other.

[0107] It can be understood that, referring to Figure 6 , each bare battery cell 300 generally includes a positive tab and a negative tab, that is, each bare battery cell 300 includes two tabs 310. Therefore, in the process of stacking the tab 310 of the second bare battery cell 300 on the tab 310 of the first bare battery cell 300, the respective tabs 310 of the first bare battery cell 300 can be correspondingly connected to the respective tabs 310 of the second bare battery cell 300, so that the arrangement direction of the cell body 320 of each bare battery cell 300 (for example, arranged along the Y direction in the figure) is perpendicular to the arrangement direction of the tab 310 of each bare battery cell 300 (for example, arranged along the X direction in the figure); correspondingly, the thickness direction of the cell body 320 can be set along the Z direction in the figure. An interval extending in the arrangement direction of the tab 310 is formed between the cell bodies 320 of the respective bare battery cells 300, for example Figure 6 the interval formed in

[0108] extends along the X direction in the figure.

[0109] In this embodiment, when the assembling method of the bare battery cell 300 is in use, the assembling method can integrally weld and fix the tab 310 of the first bare battery cell 300, the tab 310 of the second bare battery cell 300, and the pole column 211 of the top cover structure 210 by ultrasonic welding, so that the tab 310 of the first bare battery cell 300 and the tab 310 of the second bare battery cell 300 are directly fixed to the top cover structure 210, reducing the limitation of the current density by the connecting piece and its weld seams. For example, the two weld seams between the connecting piece and the tab 310 and between the connecting piece and the top cover structure 210 are changed to one weld seam between the tab 310 and the top cover structure 210, which is beneficial to improving the energy density of the corresponding battery cell. In addition, the assembling method can reduce the usage requirement of the connecting piece and reduce the corresponding welding process, improving the assembling efficiency and reducing the overall manufacturing cost.

[0110] In addition, the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 are integrally welded and fixed by ultrasonic welding. Compared with the laser welding process, ultrasonic welding can reduce the slag metal particles, reducing the risk of battery short - circuit and fire caused by the falling slag metal particles, and also reducing the requirement for the dispensing process covering the slag metal particles, thus reducing the overall manufacturing cost of the battery cell.

[0111] In some embodiments, referring to Figure 5 , the step of forming the cavity 201 on the side of the top cover structure 210 facing away from the tab 310 of the second bare battery cell 300 (the above - mentioned step S020) includes:

[0112] Forming the cavity 201 on the side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300, for example, forming the cavity 201 by means of casting, machining, etc.

[0113] In some embodiments, referring to Figure 5 , the assembling method further includes the following steps:

[0114] Making one end of the pole column 211 protrude from the top cover structure 210, for example, by making the height of the pole column 211 greater than the thickness of the top cover structure 210 and making one end face of the pole column 211 flush with one end face of the top cover structure 210;

[0115] The step of forming the cavity 201 on the side of the top cover structure 210 facing away from the tab 310 of the second bare battery cell 300 (the above - mentioned step S020) includes:

[0116] Forming the cavity 201 on the end face of the end of the pole column 211 protruding from the top cover structure 210.

[0117] In this embodiment, the assembly method forms a concave cavity 201 on the end face of the end of the pole column 211 protruding from the top cover structure 210, so that the pole column 211 can be fixed by the boss 121 of the ultrasonic welding seat 120 through the concave cavity 201, thereby improving the position stability of the tab 310 of the first bare battery cell 300, the tab 310 of the second bare battery cell 300, and the pole column 211 of the top cover structure 210 during the welding process, which is beneficial to improving the weld quality between the tab 310 of the first bare battery cell 300, the tab 310 of the second bare battery cell 300, and the pole column 211 of the top cover structure 210, beneficial to reducing the limitation of the weld quality on the current density, and beneficial to improving the energy density of the corresponding battery cell unit.

[0118] In some embodiments, referring to Figure 4 、 Figure 5 and Figure 6 , the assembly method further includes the following steps:

[0119] Provide a support plate 130, on the surface of the support plate 130 there is a groove 131, and on the bottom wall of the groove 131 there is a through hole 132; wherein, the groove 131 and the through hole 132 can be formed by casting, injection molding, machining and other methods respectively.

[0120] Place the top cover structure 210 into the groove 131, and make the side of the top cover structure 210 provided with the concave cavity 201 face the through hole 132. Specifically, a mechanism such as a robotic arm can be used for placement, or an operator can place it manually.

[0121] In this embodiment, the assembly method places the top cover structure 210 into the groove 131 and makes the side of the top cover structure 210 provided with the concave cavity 201 face the through hole 132, so that the top cover structure 210 can be positioned by the boss 121 of the ultrasonic welding seat 120 through the concave cavity 201. The acting force of the top cover structure 210 on the support plate 130 due to welding vibration is reduced, which is beneficial to enabling the support plate 130 to have sufficient structural strength when provided with the groove 131, and beneficial to improving the positioning efficiency of the top cover structure 210 through the groove 131 of the support plate 130; in addition, after the top cover structure 210 is placed into the groove 131, the surface flatness between the top cover structure 210 and the support plate 130 is higher. For example, the height of the top cover structure 210 protruding from the support plate 130 is reduced, which is beneficial to reducing the risk of accidental bending of the tab 310.

[0122] Furthermore, the above step of placing the top cover structure 210 into the groove 131 and making the side of the top cover structure 210 provided with the concave cavity 201 face the through hole 132 includes:

[0123] Make the end of the pole column 211 protruding from the top cover structure 210 (for exampleFigure 5 at the upper end thereof, wherein Figure 5 (a view from the upward perspective) passes through the through hole 132 and abuts against the hole wall of the through hole 132, which can be understood as abutting against the hole wall of the through hole 132 through the side wall of the pole column 211.

[0124] In this embodiment, the assembly method is such that one end of the pole column 211 protruding from the top cover structure 210 passes through the through hole 132 and abuts against the hole wall of the through hole 132, thereby facilitating the improvement of the positioning efficiency of the top cover structure 210 through the groove 131 of the support plate 130 and facilitating the improvement of the overall assembly efficiency.

[0125] In some embodiments, referring to Figure 4 , the assembly method may further include: providing at least one limiting block 133 on the side of the support plate 130 provided with the groove 131, the limiting block 133 being provided at the outer edge of the support plate 130, and the limiting block 133 being used to abut against the outer edge of the bare battery cell 300. Wherein, the support plate 130 and the limiting block 133 may be integrally formed, and of course, the support plate 130 and the limiting block 133 may also be connected by welding, snap connection, plug connection or the like.

[0126] In this embodiment, the limiting block 133 can fix the bare battery cell 300 by abutting against the outer edge of the bare battery cell 300, thereby improving the efficiency of placing the bare battery cell 300 on the support plate 130.

[0127] In some embodiments, referring to Figure 4 , the assembly method may further include: providing at least two limiting blocks 133 on the outer edge of the support plate 130, the limiting blocks 133 being spaced along the outer edge of the support plate 130. For example, a plurality of limiting blocks 133 may be spaced along the circumferential direction of the support plate 130.

[0128] In this embodiment, at least two limiting blocks 133 spaced along the outer edge of the support plate 130 increase the support positions for the bare battery cell 300, thereby improving the placement stability of the bare battery cell 300 on the support plate 130.

[0129] In some embodiments, referring to Figure 6 , the above assembly method further includes the following steps:

[0130] For the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence, they respectively abut against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 and one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211, so that the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 are relatively close to each other and are compacted. Among them, this step can be executed before the above step S300 (welding step).

[0131] In this embodiment, the assembly method improves the positional stability of the tab 310 of the first bare battery cell 300, the tab 310 of the second bare battery cell 300, and the pole column 211 of the top cover structure 210 during the welding process by respectively abutting against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 and one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211, which is beneficial to improving the weld quality between the tab 310 of the first bare battery cell 300, the tab 310 of the second bare battery cell 300, and the pole column 211 of the top cover structure 210, beneficial to reducing the limitation of the weld quality on the current density, and beneficial to improving the energy density of the corresponding battery cell.

[0132] In some embodiments, referring to Figure 6 and Figure 15 , for the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence, the steps of respectively abutting against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 and one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211 include:

[0133] Step S210, abut against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 through the ultrasonic welding base 120;

[0134] Step S220, abut against one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211 through the ultrasonic welding head 110;

[0135] The step (the above step S300) of integrally welding and fixing the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence by ultrasonic welding includes:

[0136] Make the vibration direction of the ultrasonic welding head 110 parallel to the surface of the tab 310 and intersect with the height direction of the tab 310. For example Figure 6 the height direction of the tab 310 is set along the Y direction in the figure, and the vibration direction of the ultrasonic welding head 110 is parallel to the X direction in the figure.

[0137] In this embodiment, the assembly method makes the vibration direction of the ultrasonic horn 110 parallel to the surface of the pole lug 310 and intersects with the height direction of the pole lug 310, so as to facilitate the arrangement of the ultrasonic horn 110 by utilizing the interval between the first bare battery cell 300 and the second bare battery cell 300, thereby increasing the vibration space of the ultrasonic horn 110 and helping to reduce the risk of the ultrasonic horn 110 accidentally hitting the bare battery cell 300.

[0138] In some embodiments, reference Figure 7 and Figure 15 , the assembly method further comprises the following steps:

[0139] Step S010, forming a boss 121 at one end of the ultrasonic welding seat 120 facing the top cover structure 210, for example, by integral casting, machining, welding connection, etc.; wherein the boss 121 can be understood as a block-shaped structure protruding from the end face of the ultrasonic welding seat 120 (for example, protruding from the upper end face of the ultrasonic welding seat 120 in the figure).

[0140] Step S020, forming a cavity 201 on the side of the top cover structure 210 facing away from the pole ear 310 of the second bare battery cell 300, for example, forming the cavity 201 by integral casting, machining, etc.; wherein the cavity 201 can be understood as a concave structure on the surface of the top cover structure 210, such as a pit, a groove, etc.

[0141] The step of abutting the pole 211 against the side of the pole ear 310 of the second bare battery cell 300 facing away from the pole ear 310 by the ultrasonic welding seat 120 includes:

[0142] The boss 121 is embedded in the cavity 201 and the side wall of the boss 121 is abutted against the side wall of the cavity 201. The side wall of the boss 121 can be understood as the side wall in the height direction of the boss 121, such as the left and right walls in the figure; the side wall of the cavity 201 can be understood as the side wall in the depth direction of the cavity 201, such as the left and right walls in the figure. In addition, this step can be included in the above step S210 (the ultrasonic welding seat 120 is used to abut the side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300).

[0143] In this embodiment, the assembly method reduces the risk of the top cover structure 210 moving relative to the ultrasonic welding base 120 by embedding the boss 121 into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201, reduces the energy consumed between the ultrasonic welding base 120 and the top cover structure 210, makes the welding energy more concentrated between the top cover structure 210 and the tab 310, and reduces the risk of poor welding between the top cover structure 210 and the tab 310. In addition, since the risk of the top cover structure 210 moving relative to the ultrasonic welding base 120 is reduced, the risk of the boss 121 on the end surface of the ultrasonic welding base 120 being worn by the top cover structure 210 is reduced, the overall service life of the ultrasonic welding base 120 is longer, thereby reducing the replacement frequency of the ultrasonic welding base 120 and reducing the overall usage cost of the ultrasonic welding base 120; on the other hand, the risk of the boss 121 being worn by the top cover structure 210 is reduced, and the dust formed between the top cover structure 210 and the ultrasonic welding base 120 is reduced, which is beneficial to improving the overall quality of the corresponding battery cell.

[0144] In some embodiments, referring to Figure 7 、 Figure 8 or Figure 9 , the above assembly method further includes the following steps:

[0145] Make the side wall surface of the boss 121 have a first inclined wall surface section 122, which can be understood as a wall surface section inclined to the height direction of the boss 121, for example, inclined to the Figure 7 vertical direction in

[0146] Make the side wall surface of the cavity 201 have a second inclined wall surface section 202, which can be understood as a wall surface section inclined to the depth direction of the cavity 201, for example, inclined to the Figure 7 vertical direction in

[0147] The step of embedding the boss 121 into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201 includes:

[0148] Bring the first inclined wall surface segment 122 into contact with the second inclined wall surface segment 202, and relatively move the ultrasonic welding seat 120 and the top cover structure 210 along the surface of the top cover structure 210. For example, the first inclined wall surface segment 122 and the second inclined wall surface segment 202 can be relatively arranged in position to facilitate the first inclined wall surface segment 122 to contact the second inclined wall surface segment 202, so as to relatively move the ultrasonic welding seat 120 and the top cover structure 210 along the surface of the top cover structure 210. It can be understood that when there is a certain deviation in the relative positions of the boss 121 and the concave cavity 201 and the deviation is small, during the process of the boss 121 being embedded in the concave cavity 201, the boss 121 can convert the movement of the boss 121 relative to the concave cavity 201 in the height direction into the movement of the top cover structure 210 perpendicular to the height direction of the boss 121, for example, converted into Figure 6 , Figure 7 the horizontal movement in Figure 7 , so as to guide the top cover structure 210 and improve the alignment degree of the ultrasonic welding seat 120 and the top cover structure 210. After the ultrasonic welding seat 120 and the top cover structure 210 are aligned, the contact between the first inclined wall surface segment 122 and the second inclined wall surface segment 202 can ensure the position stability of the ultrasonic welding seat 120 and the top cover structure 210 in the direction perpendicular to the height of the boss 121.

[0149] In this embodiment, the assembly method is conducive to accommodating the positioning deviation between the ultrasonic welding seat 120 and the top cover structure 210 and improves the alignment degree between the ultrasonic welding seat 120 and the top cover structure 210 by bringing the first inclined wall surface segment 122 into contact with the second inclined wall surface segment 202 and relatively moving the ultrasonic welding seat 120 and the top cover structure 210 along the surface of the top cover structure 210.

[0150] In some embodiments, referring to Figure 7 , the above-mentioned assembly method may include: forming a preset angle B between the end face (such as the upper end face in the figure) of the ultrasonic welding seat 120 provided with the boss 121 and the first inclined wall surface segment 122, where the preset angle B is greater than 90 degrees and less than or equal to 120 degrees, and the preset angle B can be set to angles such as 95 degrees, 105 degrees, 115 degrees, 120 degrees, etc.

[0151] In this embodiment, since the preset angle B is greater than 90 degrees and less than or equal to 120 degrees, the side wall surface of the boss 121 is relatively steep; when the size of the root of the boss 121 and the height of the boss 121 are certain, the area of the top of the boss 121 is increased, the risk of the top of the boss 121 being worn by the top cover structure 210 is reduced, the risk of virtual soldering caused by the relative movement between the top cover structure 210 and the ultrasonic welding seat 120 is reduced, and the risk of forming dust due to wear is reduced.

[0152] In some embodiments, with reference to Figure 7 and Figure 8 , the steps of making the side wall surface of the boss 121 have the first inclined wall surface section 122 include:

[0153] Forming an arc-shaped first inclined wall surface section 122, and the arc-shaped central axis of the first inclined wall surface section 122 (as shown by the dashed line in Figure 8 ) intersects the top surface of the boss 121; for example, the arc-shaped central axis of the first inclined wall surface section 122 is perpendicular to or inclined to the top surface of the boss 121; specifically, the boss 121 can be set as Figure 8 the frustum of a cone in

[0154] The steps of making the side wall surface of the cavity 201 have the second inclined wall surface section 202 include:

[0155] Forming an arc-shaped second inclined wall surface section 202, and the arc-shaped central axis of the second inclined wall surface section 202 intersects the surface of the top cover structure 210, so that the arc-shaped second inclined wall surface section 202 stably abuts against the arc-shaped first inclined wall surface section 122.

[0156] In this embodiment, the assembly method can be beneficial for guiding in more directions on the arc-shaped surface by respectively setting the first inclined wall surface section 122 and the second inclined wall surface section 202 as arcs. For example, it can be guided in the left-right direction and the front-back direction in Figure 8 respectively, which is beneficial for further improving the alignment degree between the ultrasonic welding seat 120 and the top cover structure 210.

[0157] In some embodiments, with reference to Figure 9 and Figure 10 , the above assembly method further includes the following steps:

[0158] Making the side wall surface of the boss 121 have the first flat wall surface section 123. For example, the boss 121 can be set as a frustum of a prism or a frustum of a pyramid;

[0159] Making the side wall surface of the cavity 201 have the second flat wall surface section 203. For example, the cavity 201 can be set as a prismatic cavity or a pyramidal cavity;

[0160] The steps of making the boss 121 embed into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201 include:

[0161] Making the first flat wall surface section 123 abut against the second flat wall surface section 203;

[0162] The step of integrally welding and fixing the pole column 211, the pole ear 310 of the first bare battery cell 300, and the pole ear 310 of the second bare battery cell 300 which are sequentially stacked by ultrasonic welding (the above step S300) includes:

[0163] Make the vibration direction of the ultrasonic welding head 110 parallel to the surface of the pole ear 310 and intersect with the height direction of the pole ear 310, and make the vibration direction of the ultrasonic welding head 110 intersect with the first flat wall surface section 123. Among them, the vibration direction of the ultrasonic welding head 110 refers to the X direction in the figure.

[0164] In this embodiment, the assembly method reduces the local pressure of the vibrating ultrasonic welding head 110 on the boss 121 by making the vibration direction of the ultrasonic welding head 110 parallel to the surface of the pole ear 310 and intersect with the height direction of the pole ear 310, and making the vibration direction of the ultrasonic welding head 110 intersect with the first flat wall surface section 123, reduces the risk of the top of the boss 121 being worn by the top cover structure 210, reduces the risk of virtual soldering caused by relative movement between the top cover structure 210 and the ultrasonic welding seat 120, and reduces the risk of forming dust due to wear.

[0165] In some embodiments, referring to Figure 7 and Figure 15 , the above assembly method further includes the following steps:

[0166] Make the dimension L1 of the root of the boss 121 in the preset direction greater than the dimension L2 of the mouth of the concave cavity 201 in the preset direction, where the preset direction is perpendicular to the height direction of the boss 121, for example Figure 7 in which the preset direction is parallel to the left - right direction. Among them, this step can be included in the above step S010 (forming the boss 121 at one end of the ultrasonic welding seat 120 facing the top cover structure 210) or the above step S020 (forming the concave cavity 201 on the side of the top cover structure 210 facing away from the pole ear 310 of the second bare battery cell 300), or this step is executed after step S010 and step S020.

[0167] In this embodiment, the assembly method makes the dimension L1 of the root of the boss 121 in the preset direction greater than the dimension L2 of the mouth of the concave cavity 201 in the preset direction, so that the root of the boss 121 can be embedded into the mouth of the concave cavity 201 by elastic - plastic deformation, so that an interference fit is formed between the root of the boss 121 and the mouth of the concave cavity 201, improving the connection stability between the ultrasonic welding seat 120 and the top cover structure 210, and further reducing the risk of virtual soldering caused by the relative movement of the top cover structure 210 relative to the ultrasonic welding seat 120.

[0168] In some embodiments, the steps of embedding the boss 121 into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201 include:

[0169] Embedding the root of the boss 121 into the cavity 201 and making the surface of the ultrasonic welding base 120 facing the top cover structure 210 abut against the top cover structure 210; for example, by bringing the relatively arranged ultrasonic welding head 110 and ultrasonic welding base 120 closer to each other, so as to provide a force for embedding the root of the boss 121 into the cavity 201. Among them, this step may be included in the above step S210 (abutting one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 through the ultrasonic welding base 120).

[0170] In this embodiment, this assembly method embeds the root of the boss 121 into the cavity 201 and makes the surface of the ultrasonic welding base 120 facing the top cover structure 210 abut against the top cover structure 210, thereby improving the connection stability between the ultrasonic welding base 120 and the top cover structure 210, and further reducing the risk of virtual soldering caused by the relative movement of the top cover structure 210 relative to the ultrasonic welding base 120.

[0171] In some embodiments, referring to Figure 11 , Figure 12 and Figure 13 , one end of the ultrasonic welding head 110 facing the tab 310 of the second bare battery cell 300 is provided with welding teeth 111. The steps of forming the boss 121 at one end of the ultrasonic welding base 120 facing the top cover structure 210 include:

[0172] Making the cross-sectional area of the root of the boss 121 larger than the cross-sectional area of the root of the welding teeth 111. It can be understood that the boss 121 is thicker than the welding teeth 111.

[0173] In this embodiment, the assembly method makes the cross-sectional area of the root of the boss 121 larger than the cross-sectional area of the root of the welding teeth 111, so that the area of the top of the boss 121 is relatively large, further reducing the risk of the top of the boss 121 being worn by the top cover structure 210, further reducing the risk of virtual soldering caused by the relative movement between the top cover structure 210 and the ultrasonic welding base 120, and reducing the risk of forming dust due to wear.

[0174] In some embodiments, referring to Figure 11 , the steps of integrally welding and fixing the pole column 211, the tab 310 of the first bare battery cell 300 and the tab 310 of the second bare battery cell 300 arranged in a stacked manner in sequence by ultrasonic welding (the above step S300) include:

[0175] Make the width W1 of the formed welding mark 311 less than the distance W2 from the welding mark 311 to the cell body 320 of one of the bare cells 300, where the width direction of the welding mark 311 is consistent with the height direction of the tab 310, for example, along the Figure 11 up and down directions in

[0176] In this embodiment, the assembly method can be understood that the welding position and the welding mark 311 are far from the cell body 320 by making the width W1 of the formed welding mark 311 less than the distance W2 from the welding mark 311 to the cell body 320 of one of the bare cells 300, which is beneficial to reducing the influence of the vibration of ultrasonic welding on the connecting corner of the tab 310 and the cell body 320, beneficial to reducing the risk that the connecting corner of the tab 310 and the cell body 320 is pulled and torn due to welding vibration, and beneficial to improving the overall quality of the corresponding battery cell.

[0177] In some embodiments, the step of making the width W1 of the formed welding mark 311 less than the distance W2 from the welding mark 311 to the cell body 320 of one of the bare cells 300 includes:

[0178] Make the ratio of the width W1 of the formed welding mark 311 to the distance W2 from the welding mark 311 to the cell body 320 of one of the bare cells 300 less than or equal to 0.5, which is beneficial to further reducing the risk that the connecting corner of the tab 310 and the cell body 320 is pulled and torn due to welding vibration, and beneficial to further improving the overall quality of the corresponding battery cell.

[0179] Referring to Figures 4 to 15 , in one embodiment, the assembly method of the bare cell 300 is used to assemble at least two bare cells 300 with the top cover structure 210. The bare cell 300 includes a tab 310, and the top cover structure 210 includes a pole column 211. The above assembly method includes the following steps:

[0180] Stack the tab 310 of the first bare cell 300 on the pole column 211;

[0181] Stack the tab 310 of the second bare cell 300 on the tab 310 of the first bare cell 300 so that the pole column 211, the tab 310 of the first bare cell 300, and the tab 310 of the second bare cell 300 are stacked in sequence;

[0182] Weld and fix the pole column 211, the tab 310 of the first bare cell 300, and the tab 310 of the second bare cell 300 stacked in sequence by ultrasonic welding integrally.

[0183] The assembly method further includes the following steps:

[0184] For the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence, they respectively abut against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 and one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211.

[0185] The steps of respectively abutting against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 and one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211 for the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence include:

[0186] Abut against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 through the ultrasonic welding base 120;

[0187] Abut against one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211 through the ultrasonic welding head 110;

[0188] The steps of integrally welding and fixing the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence through ultrasonic welding include:

[0189] Make the vibration direction of the ultrasonic welding head 110 parallel to the surface of the tab 310 and intersect with the height direction of the tab 310.

[0190] The steps of respectively abutting against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 and one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211 for the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are stacked in sequence include:

[0191] Abut against one side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 through the ultrasonic welding base 120;

[0192] Abut against one side of the tab 310 of the second bare battery cell 300 facing away from the pole column 211 through the ultrasonic welding head 110;

[0193] The assembling method further includes the following steps:

[0194] Form a boss 121 at one end of the ultrasonic welding base 120 facing the top cover structure 210;

[0195] Form a cavity 201 on one side of the top cover structure 210 facing away from the tab 310 of the second bare battery cell 300;

[0196] The step of abutting the ultrasonic welding base 120 against the side of the pole column 211 facing away from the tab 310 of the second bare battery cell 300 includes:

[0197] Insert the boss 121 into the cavity 201 and make the side wall surface of the boss 121 abut against the side wall surface of the cavity 201.

[0198] The assembly method further includes the following steps:

[0199] Make the side wall surface of the boss 121 have a first inclined wall surface section 122;

[0200] Make the side wall surface of the cavity 201 have a second inclined wall surface section 202;

[0201] The step of inserting the boss 121 into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201 includes:

[0202] Make the first inclined wall surface section 122 abut against the second inclined wall surface section 202, and make the ultrasonic welding base 120 and the top cover structure 210 move relative to each other along the surface of the top cover structure 210.

[0203] The assembly method further includes the following steps:

[0204] Make the side wall surface of the boss 121 have a first flat wall surface section 123;

[0205] Make the side wall surface of the cavity 201 have a second flat wall surface section 203;

[0206] The step of inserting the boss 121 into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201 includes:

[0207] Make the first flat wall surface section 123 abut against the second flat wall surface section 203;

[0208] The step of integrally welding and fixing the pole column 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 that are sequentially stacked includes:

[0209] Make the vibration direction of the ultrasonic welding head 110 parallel to the surface of the tab 310 and intersect with the height direction of the tab 310, and make the vibration direction of the ultrasonic welding head 110 intersect with the first flat wall surface section 123.

[0210] The assembly method further includes the following steps:

[0211] Make the dimension of the root of the boss 121 in the preset direction greater than the dimension of the mouth of the cavity 201 in the preset direction, and the preset direction is perpendicular to the height direction of the boss 121.

[0212] The steps of embedding the boss 121 into the cavity 201 and making the side wall surface of the boss 121 abut against the side wall surface of the cavity 201 include:

[0213] Embed the root of the boss 121 into the cavity 201, and make the surface of the ultrasonic welding seat 120 facing the top cover structure 210 abut against the top cover structure 210.

[0214] One end of the ultrasonic welding head 110 facing the tab 310 of the second bare battery cell 300 is provided with welding teeth 111. The steps of forming the boss 121 at one end of the ultrasonic welding seat 120 facing the top cover structure 210 include:

[0215] Make the cross-sectional area of the root of the boss 121 larger than the cross-sectional area of the root of the welding teeth 111.

[0216] The assembly method further includes the following steps:

[0217] Provide a support plate 130, on the surface of which there is a groove 131, and a through hole 132 is provided on the bottom wall of the groove 131;

[0218] Place the top cover structure 210 into the groove 131, and make the side of the top cover structure 210 provided with the cavity 201 face the through hole 132.

[0219] The assembly method further includes the following steps:

[0220] Make one end of the pole post 211 protrude from the top cover structure 210;

[0221] The steps of forming the cavity 201 on the side of the top cover structure 210 facing away from the tab 310 of the second bare battery cell 300 include:

[0222] Form the cavity 201 on the end face of the end of the pole post 211 protruding from the top cover structure 210.

[0223] The steps of placing the top cover structure 210 into the groove 131 and making the side of the top cover structure 210 provided with the cavity 201 face the through hole 132 include:

[0224] Make the end of the pole post 211 protruding from the top cover structure 210 pass through the through hole 132 and abut against the hole wall of the through hole 132.

[0225] The bare battery cell 300 includes a tab 310 and a battery cell body 320. The steps of integrally welding and fixing the pole post 211, the tab 310 of the first bare battery cell 300, and the tab 310 of the second bare battery cell 300 which are sequentially stacked by ultrasonic welding include:

[0226] The width of the formed welding mark 311 is made smaller than the distance from the welding mark 311 to the cell body 320 of one of the bare cells 300, and the width direction of the welding mark 311 is consistent with the height direction of the tab 310.

[0227] The present application also provides a battery cell. The battery cell includes a battery housing, the above-mentioned top cover structure 210, and at least two bare cells 300. The battery housing has an opening and a receiving cavity. The top cover structure 210 is connected to the opening, for example, by welding the edge of the top cover structure 210 to the opening; the bare cells 300 are received in the receiving cavity, and the bare cells 300 are assembled with the top cover structure 210 by using the above-mentioned assembly method of the bare cells 300.

[0228] Among them, the bare cells 300 of the battery cell are assembled with the top cover structure 210 by using the above-mentioned assembly method of the bare cells 300. The tabs 310 of the first bare cell 300, the tabs 310 of the second bare cell 300, and the pole column 211 of the top cover structure 210 can be integrally welded and fixed by ultrasonic welding, so that the tabs 310 of the first bare cell 300 and the tabs 310 of the second bare cell 300 are directly fixed to the top cover structure 210, reducing the limitation of the current density by the jumper and its weld seam, which is beneficial to improving the energy density of the corresponding battery cell. In addition, the battery cell can reduce the use requirement of the jumper and reduce the corresponding welding process, improving the assembly efficiency and reducing the overall manufacturing cost.

[0229] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural transformation made under the technical concept of the present application by using the content of the specification and drawings of the present application, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A method for assembling a bare battery cell, characterized in that: The assembly method is used to assemble at least two bare cells with a top cover structure, wherein the bare cells include a pole ear, and the top cover structure includes a pole column. The assembly method includes the following steps: Stacking the tab of the first bare cell onto the pole; The tab of the second bare cell is stacked on the tab of the first bare cell, so that the pole, the tab of the first bare cell and the tab of the second bare cell are stacked in sequence; For the pole, the pole ear of the first bare cell and the pole ear of the second bare cell stacked in sequence, the pole is respectively abutted against a side of the pole facing away from the pole ear of the second bare cell and a side of the pole ear of the second bare cell facing away from the pole; For the pole, the pole ear of the first bare cell and the pole ear of the second bare cell stacked in sequence, the steps of respectively abutting against a side of the pole facing away from the pole ear of the second bare cell and a side of the pole ear of the second bare cell facing away from the pole include: Abutting the side of the pole facing away from the pole ear of the second bare battery cell by an ultrasonic welding seat; Abutting the side of the pole ear of the second bare battery cell facing away from the pole column by using an ultrasonic welding head; The assembly method further comprises the following steps: A boss is formed at one end of the ultrasonic welding seat facing the top cover structure; A concave cavity is formed on a side of the top cover structure facing away from the pole ear of the second bare battery cell; The step of abutting the side of the pole facing away from the pole ear of the second bare cell by an ultrasonic welding seat comprises: The boss is embedded in the cavity and the side wall surface of the boss abuts against the side wall surface of the cavity; The poles, the pole lugs of the first bare cell and the pole lugs of the second bare cell which are stacked in sequence are integrally welded and fixed by ultrasonic welding.

2. The assembly method according to claim 1, characterized in that: The step of integrally welding and fixing the sequentially stacked poles, the pole lugs of the first bare cell, and the pole lugs of the second bare cell by ultrasonic welding comprises: The vibration direction of the ultrasonic horn is parallel to the surface of the pole lug and intersects with the height direction of the pole lug.

3. The assembly method according to claim 1, characterized in that: The assembly method further comprises the following steps: The side wall surface of the boss has a first inclined wall surface segment; The side wall of the cavity has a second inclined wall segment; The steps of embedding the boss into the cavity and making the side wall surface of the boss abut against the side wall surface of the cavity include: The first inclined wall segment is abutted against the second inclined wall segment, and the ultrasonic welding seat and the top cover structure are relatively moved along the surface of the top cover structure.

4. The assembly method according to any one of claims 1 to 3, characterized in that: The assembly method further comprises the following steps: The side wall surface of the boss has a first flat wall surface segment; The side wall of the cavity has a second flat wall segment; The steps of embedding the boss into the cavity and making the side wall surface of the boss abut against the side wall surface of the cavity include: making the first flat wall segment abut against the second flat wall segment; The step of integrally welding and fixing the poles, the pole lugs of the first bare cell, and the pole lugs of the second bare cell, which are stacked in sequence, by ultrasonic welding comprises: The vibration direction of the ultrasonic horn is parallel to the surface of the pole lug and intersects with the height direction of the pole lug, and the vibration direction of the ultrasonic horn intersects with the first flat wall segment.

5. The assembly method according to any one of claims 1 to 3, characterized in that: The assembly method further comprises the following steps: The size of the root of the boss in a preset direction is made larger than the size of the mouth of the cavity in the preset direction, and the preset direction is perpendicular to the height direction of the boss.

6. The assembly method according to claim 5, characterized in that: The steps of embedding the boss into the cavity and making the side wall surface of the boss abut against the side wall surface of the cavity include: The root of the boss is embedded in the cavity, and the surface of the ultrasonic welding seat facing the top cover structure is abutted against the top cover structure.

7. The assembly method according to any one of claims 1 to 3, characterized in that: The end of the ultrasonic welding head facing the pole ear of the second bare battery cell is provided with welding teeth, and the step of forming a boss on the end of the ultrasonic welding seat facing the top cover structure includes: The cross-sectional area of ​​the root of the boss is made larger than the cross-sectional area of ​​the root of the welding tooth.

8. The assembly method according to any one of claims 1 to 3, characterized in that: The assembly method further comprises the following steps: Providing a support plate, wherein a groove is provided on the surface of the support plate, and a through hole is provided on the bottom wall of the groove; The top cover structure is placed in the groove, with the side of the top cover structure provided with the concave cavity facing the through hole.

9. The assembly method according to claim 8, characterized in that: The assembly method further comprises the following steps: One end of the pole is protruded from the top cover structure; The step of forming a concave cavity on a side of the top cover structure facing away from the tab of the second bare cell comprises: The concave cavity is formed on an end surface of the pole at one end protruding from the top cover structure.

10. The assembly method according to claim 9, characterized in that: The step of placing the top cover structure into the groove and making the side of the top cover structure provided with the concave cavity face the through hole comprises: One end of the pole protruding from the top cover structure passes through the through hole and abuts against the hole wall of the through hole.

11. The assembly method according to any one of claims 1 to 3, characterized in that: The bare cell comprises the tab and the cell body, and the step of integrally welding and fixing the sequentially stacked poles, the tab of the first bare cell and the tab of the second bare cell by ultrasonic welding comprises: The width of the formed weld mark is made smaller than the distance from the weld mark to the battery cell body of one of the bare batteries, and the width direction of the weld mark is consistent with the height direction of the tab.

12. A battery cell, characterized in that: The battery cell includes a battery casing, a top cover structure and at least two bare cells, the battery casing having an opening and a receiving cavity, the top cover structure being connected to the opening, the bare cells being received in the receiving cavity, and the bare cells being assembled with the top cover structure using the bare cell assembly method as described in any one of claims 1 to 11.

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