Bare battery cell assembly method and battery cell

Abstract

The present application discloses an assembly method of a bare cell and a battery cell, and relates to the technical field of battery manufacturing. The assembly method is used to assemble at least two bare cells with a top cover structure, and the assembly method includes the following steps: stacking the pole lug of the first bare cell on the pole column; stacking the pole lug of the second bare cell on the pole lug of the first bare cell, so that the pole column, the pole lug of the first bare cell and the pole lug of the second bare cell are stacked in sequence; the pole column, the pole lug of the first bare cell and the pole lug of the second bare cell stacked in sequence are welded and fixed as a whole by ultrasonic welding. The assembly method can weld and fix the pole lugs of the first and second bare cells and the pole column of the top cover structure as a whole by ultrasonic welding, so that the pole lugs of the first bare cell and the pole lugs of the second bare cell are directly fixed to the top cover structure, reducing the limitation of the adapter and its weld on the current density, which is conducive to improving the energy density of the corresponding battery cell.

Description

Technical Field

[0001] The present application relates to the technical field of battery manufacturing, and in particular to an assembly method of a bare battery cell and a battery cell. Background Art

[0002] In the production process of lithium batteries, sodium batteries and other types of batteries, one or more bare cells containing positive and negative electrode materials are usually placed in a battery casing, and then the bare cells and the top cover structure are respectively connected through adapters, and the top cover structure is welded to the battery casing to assemble into a battery cell.

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

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

[0005] To achieve the above-mentioned purpose, the bare cell assembly method proposed in the present application is used to assemble at least two bare cells with a top cover structure, wherein the bare cell includes a tab, and the top cover structure includes a pole, and 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.

[0006] When the bare cell assembly method in the technical solution of the present application is used, the assembly method can weld and fix the pole lug of the first bare cell, the pole lug of the second bare cell and the pole column of the top cover structure as a whole through ultrasonic welding, so that the pole lug of the first bare cell and the pole lug of the second bare cell are directly fixed to the top cover structure, reducing the limitation of the adapter and its weld on the current density, which is conducive to improving the energy density of the corresponding battery cell. In addition, the assembly method can reduce the need for the use of adapters and reduce the corresponding welding process, improve assembly efficiency, and reduce overall manufacturing costs.

[0007] In addition, the assembly method improves the positional stability of the pole lug of the first bare cell, the pole lug of the second bare cell and the pole lug of the top cover structure during the welding process by respectively abutting the side of the pole lug facing away from the second bare cell and the side of the pole lug facing away from the pole lug, which is beneficial to improving the weld quality between the pole lug of the first bare cell, the pole lug of the second bare cell and the pole lug of the top cover structure, reducing the limitation of the weld quality on the current density, and improving the energy density of the corresponding battery cell.

[0008] In addition, the assembly method reduces the risk of the top cover structure moving relative to the ultrasonic welding seat by embedding the boss into the cavity and making the side wall of the boss abut against the side wall of the cavity, reduces the energy consumed between the ultrasonic welding seat and the top cover structure, and makes the welding energy more concentrated between the top cover structure and the pole ear, reducing the risk of a cold weld between the top cover structure and the pole ear. In addition, since the risk of the top cover structure moving relative to the ultrasonic welding seat is reduced, the risk of the boss on the end face of the ultrasonic welding seat being worn by the top cover structure is reduced, and the overall service life of the ultrasonic welding seat is longer, thereby reducing the replacement frequency of the ultrasonic welding seat and reducing the overall use cost of the ultrasonic welding seat; 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 seat is reduced, which is beneficial to improving the overall quality of the corresponding battery cell.

[0009] Optionally, 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 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.

[0010] At this time, the assembly method makes the vibration direction of the ultrasonic welding head parallel to the surface of the pole ear and intersect with the height direction of the pole ear, which is beneficial to utilize the space between the first bare battery cell and the second bare battery cell to arrange the ultrasonic welding head, thereby increasing the vibration space of the ultrasonic welding head and helping to reduce the risk of the ultrasonic welding head accidentally hitting the bare battery cell.

[0011] Optionally, 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.

[0012] At this time, the assembly method is beneficial to accommodate the positioning deviation between the ultrasonic welding seat and the top cover structure by making the first inclined wall segment abut against the second inclined wall segment, and making the ultrasonic welding seat and the top cover structure move relative to each other along the surface of the top cover structure, thereby improving the alignment degree between the ultrasonic welding seat and the top cover structure.

[0013] Optionally, 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.

[0014] At this time, the assembly method reduces the local pressure of the vibrating ultrasonic horn on the boss by making the vibration direction of the ultrasonic horn parallel to the surface of the pole lug and intersecting with the height direction of the pole lug, and makes the vibration direction of the ultrasonic horn intersect with the first flat wall segment, thereby reducing the risk of the top of the boss being worn by the top cover structure, reducing the risk of cold welding due to relative movement between the top cover structure and the ultrasonic welding seat, and reducing the risk of dust formation due to wear.

[0015] Optionally, 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.

[0016] At this time, the assembly method makes the size of the root of the boss in the preset direction larger than the size of the mouth of the cavity in the preset direction, so that the root of the boss can be embedded in the mouth of the cavity by elastic-plastic deformation, so that the root of the boss and the mouth of the cavity form an interference fit, thereby improving the connection stability between the ultrasonic welding seat and the top cover structure, and further reducing the risk of cold welding caused by the movement of the top cover structure relative to the ultrasonic welding seat.

[0017] Optionally, 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 comprises: 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.

[0018] At this time, the assembly method improves the connection stability between the ultrasonic welding seat and the top cover structure by embedding the root of the boss into the concave cavity and making the ultrasonic welding seat abut the top cover structure toward the surface of the top cover structure, thereby further reducing the risk of poor welding caused by the movement of the top cover structure relative to the ultrasonic welding seat.

[0019] Optionally, a welding tooth is provided at one end of the ultrasonic welding head facing the pole ear of the second bare battery cell, and the step of forming a boss at one end of the ultrasonic welding seat facing the top cover structure comprises: 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.

[0020] 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 tooth, 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 relative movement between the top cover structure and the ultrasonic welding seat to cause a cold weld, and reducing the risk of dust formation due to wear.

[0021] Optionally, 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.

[0022] At this time, the assembly method is to place the top cover structure into the groove, and make the side of the top cover structure with the cavity face the through hole, so that the top cover structure can be positioned by the boss of the ultrasonic welding seat through the cavity. The force acting on the support plate due to the welding vibration of the top cover structure is reduced, which is beneficial for the support plate to have sufficient structural strength when the groove is provided, and is beneficial for improving the positioning efficiency of the top cover structure through the groove of the support plate; in addition, after the top cover structure is placed in the groove, the surface flatness between the top cover structure and the support plate is higher, which is beneficial to reduce the risk of accidental bending of the tab.

[0023] Optionally, 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.

[0024] At this time, the assembly method forms a cavity on the end face of one end of the pole protruding from the top cover structure, so that the pole can be fixed by the boss of the ultrasonic welding seat through the cavity, thereby improving the position stability of the pole ear of the first bare battery cell, the pole ear of the second bare battery cell and the pole of the top cover structure during the welding process, which is beneficial to improving the weld quality between the pole ear of the first bare battery cell, the pole ear of the second bare battery cell and the pole of the top cover structure, helping to reduce the limitation of the weld quality on the current density, and helping to improve the energy density of the corresponding battery cell.

[0025] Optionally, the step of placing the top cover structure into the groove and making a 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.

[0026] At this time, the assembly method is to make one end of the pole 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 improve the positioning efficiency of the top cover structure through the groove of the support plate and improve the overall assembly efficiency.

[0027] Optionally, the bare cell includes 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.

[0028] At this time, the assembly method helps reduce the impact of ultrasonic welding vibration on the connecting corners of the tab and the cell body by making the width of the formed weld mark smaller than the distance from the weld mark to the cell body of one of the bare cells, helps reduce the risk of the connecting corners of the tab and the cell body being pulled and torn due to welding vibration, and helps improve the overall quality of the corresponding battery cell.

[0029] The present application also proposes a battery cell, which includes a battery casing, a top cover structure and at least two bare cells, wherein the battery casing has an opening and a accommodating cavity, the top cover structure is connected to the opening, the bare cells are accommodated in the accommodating cavity, and the bare cells are further assembled with the top cover structure using the above-mentioned bare cell assembly method.

[0030] The bare cell of the battery cell in the technical solution of the present application is assembled with the top cover structure using the above-mentioned bare cell assembly method, and the pole lug of the first bare cell, the pole lug of the second bare cell and the pole column of the top cover structure can be welded and fixed integrally by ultrasonic welding, so that the pole lug of the first bare cell and the pole lug of the second bare cell are directly fixed to the top cover structure, reducing the limitation of the adapter and its weld on the current density, which is conducive to improving the energy density of the corresponding battery cell. In addition, the battery cell can reduce the need for the use of the adapter and reduce the corresponding welding process, improve the assembly efficiency, and reduce the overall manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0032] Figure 1It is a schematic diagram of the connection between the tab and the adapter of the bare battery cell in the related art; Figure 2 It is a schematic diagram of welding the tab and the adapter of a bare battery cell in the related art; Figure 3 It is a schematic diagram of the connection between the adapter and the top cover structure of the bare battery cell in the related art; Figure 4 This is an assembly schematic diagram corresponding to an embodiment of an assembly method for a bare cell provided in the present application; Figure 5 This is a schematic diagram of the connection between the tab and the top cover structure in an embodiment of the present application at a bottom-up angle; Figure 6 This is a schematic diagram of welding the tab and the top cover structure of a bare battery cell in one embodiment of the present application; Figure 7 It is a partial schematic diagram of welding of the electrode tab and the top cover structure in one embodiment of the present application; Figure 8 This is a schematic diagram of the structure of an ultrasonic welding base in one embodiment of the present application; Fig. 9 This is a schematic diagram of the structure of an ultrasonic welding base in another embodiment of the present application; Fig.10 This is a schematic diagram of a partial structure of a top cover structure in another embodiment of the present application; Fig.11 A top view of the welding of the electrode tab and the top cover structure in one embodiment of the present application; Fig.12 for Fig.11 Cross-sectional view at the middle MM position; Fig.13 for Fig.12 A partial enlarged view of point C in the middle; Fig.14 A schematic diagram of the steps of an embodiment of a bare cell assembly method provided in the present application; Fig.15 A schematic diagram of the steps of another embodiment of the bare cell assembly method provided in the present application.

[0033] Description of Figure Numbers: 100. Ultrasonic welding equipment; 110. Ultrasonic welding head; 111. Welding teeth; 120, ultrasonic welding seat; 121, boss; 122, first inclined wall section; 123, first flat wall section; 130, support plate; 131, groove; 132, through hole; 133, limit block; 200, plate to be welded; 201, concave cavity; 202, second inclined wall segment; 203, second flat wall segment; 210, top cover structure; 211, pole; 300, bare battery cell; 310, tab; 311, weld mark; 320, battery cell body.

[0034] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0037] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0038] In the production process of lithium batteries, sodium batteries and other types of batteries, one or more bare cells containing positive and negative electrode materials are usually placed in a battery casing, and then the bare cells and the top cover structure are respectively connected through adapters, and the top cover structure is welded to the battery casing to assemble into a battery cell.

[0039] Among them, the energy density of battery cells is usually improved by improving the positive and negative electrode materials and the materials of the top cover structure, but the energy density of battery cells still needs to be further improved.

[0040] Reference Figure 1 , Figure 2 and Figure 3The ultrasonic welding equipment in the related art generally includes an ultrasonic generator, a transducer, an amplitude changing device, an ultrasonic welding head 110 and an ultrasonic welding seat 120, wherein the ultrasonic welding head 110 and the ultrasonic welding seat 120 are arranged opposite to each other. The ultrasonic welding equipment is also called an ultrasonic welding machine, which converts a current of about 50 to 60 Hz into electric energy of about 15 kHz to 75 kHz through an ultrasonic generator; the high-frequency electric energy obtained by the conversion is converted into mechanical motion of the same frequency again through a transducer, and then the mechanical motion is transmitted to the ultrasonic welding head 110 through a set of amplitude changing devices such as an amplitude changing rod that can change the amplitude, thereby forming 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 pole ear 310 and adapter 220), and the vibration energy is converted into heat energy in this area by friction, thereby melting the two workpieces to be welded and welding, thereby forming a weld mark 311.

[0041] Reference Figure 1 and Figure 3 In the related art, the tab 310 of the bare cell is usually welded to the adapter sheet 220, and then the adapter sheet 220 is welded to the top cover structure 210, and the bare cell, the top cover structure 210 and the battery housing are assembled to form a battery cell. That is, the related art at least includes a weld between the tab 310 and the adapter sheet 220, and a weld between the adapter sheet 220 and the top cover structure 210, wherein the adapter sheet 220 and its weld are easy to limit the current density, thereby reducing the energy density of the corresponding battery cell.

[0042] On the other hand, in the related art, the adapter plate 220 is usually welded to the top cover structure 210 by a laser welding process. The laser welding process easily causes a large number of welding slag metal particles to adhere to the surface of the adapter plate 220. Therefore, the welding slag metal particles need to be covered by a glue dispensing process to prevent the welding slag metal particles from falling off during subsequent manufacturing or use. The glue dispensing process can prevent the fallen welding slag metal particles from causing a battery short circuit and fire.

[0043] Therefore, based on the above considerations, in order to improve the energy density of the corresponding battery cell, the present application proposes a bare cell assembly method. When used, the bare cell assembly method can reduce the limitation of the adapter and its weld on the current density, so as to improve the energy density of the corresponding battery cell.

[0044] Next, the assembly method of the bare battery cell proposed in the present application is explained with a specific implementation method.

[0045] Among them, refer to Figure 4 , Figure 5 and Figure 6The ultrasonic welding device 100 corresponding to the bare cell assembly method proposed in the present application may include an ultrasonic generator, a transducer, an amplitude varying device, an ultrasonic welding head 110 and an ultrasonic welding seat 120; Figure 6 The ultrasonic welding seat 120 is arranged relative to the ultrasonic welding head 110 of the ultrasonic welding device 100, for example, in the up-down direction in the figure, so that the ultrasonic welding head 110 and the ultrasonic welding seat 120 are further approached to each other to compact the tab 310 and the adapter 220 of the bare battery cell 300, and then perform subsequent ultrasonic welding. Figure 7 , Figure 8 or Fig. 9 , a boss 121 may be provided at one end of the ultrasonic welding seat 120; Figure 7 or Fig.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 .

[0046] Reference Figure 4 and Fig.14 The assembly method of the bare cell 300 proposed in the present application is used to assemble at least two bare cells 300 with a top cover structure 210, wherein the bare cell 300 includes a tab 310 and a cell body 320, and the top cover structure 210 includes a pole 211. It is understandable that the bare cell 300 having the tab 310 and the cell body 320 can be formed by winding, lamination, and other processes.

[0047] The assembly method comprises the following steps: Step S100, stacking the tab 310 of the first bare cell 300 onto the pole 211, which can be understood as making the thickness direction of the tab 310 consistent with the height direction of the pole 211 and making the two abut against each other; Step S200, stacking the pole lug 310 of the second bare cell 300 onto the pole lug 310 of the first bare cell 300, so that the pole column 211, the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare cell 300 are stacked in sequence, so as to facilitate forming a weld between the pole column 211 and the pole lug 310 of the first bare cell 300, and between the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare 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 plate 200 to be welded. Among them, stacking the pole ear 310 of the second bare battery cell 300 on the pole ear 310 of the first bare battery cell 300 can be understood as making the thickness direction of the pole ear 310 of the second bare battery cell 300 consistent with the thickness direction of the pole ear 310 of the first bare battery cell 300, and making the two abut against each other.

[0048] It is understandable that, referring to Figure 6 , each bare battery cell 300 generally includes a positive electrode ear and a negative electrode ear, that is, each bare battery cell 300 includes two electrode ears 310. Therefore, in the process of stacking the electrode ears 310 of the second bare battery cell 300 on the electrode ears 310 of the first bare battery cell 300, each electrode ear 310 of the first bare battery cell 300 can be connected correspondingly with each electrode ear 310 of the second bare battery cell 300, so that the arrangement direction of the battery 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 electrode ears 310 of each bare battery cell 300 (for example, arranged along the X direction in the figure); correspondingly, the thickness direction of the battery body 320 can be set along the Z direction in the figure. A gap extending along the arrangement direction of the electrode ears 310 is formed between the battery bodies 320 of each bare battery cell 300, for example Figure 6 The space formed therein extends along the X direction in the figure.

[0049] In step S300, the pole column 211, the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare cell 300 which are stacked in sequence are integrally welded and fixed by ultrasonic welding. It can be understood that in the same ultrasonic welding process, a weld is formed between the pole column 211 and the pole lug 310 of the first bare cell 300, and between the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare cell 300; it can be understood that the weld between the pole column 211 and the pole lug 310 of the first bare cell 300, and between the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare cell 300 is formed by synchronous melting and synchronous solidification.

[0050] In this embodiment, when the assembly method of the bare cell 300 is used, the assembly method can weld and fix the pole lug 310 of the first bare cell 300, the pole lug 310 of the second bare cell 300 and the pole column 211 of the top cover structure 210 as a whole by ultrasonic welding, so that the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare cell 300 are directly fixed to the top cover structure 210, reducing the limitation of the adapter and its weld on the current density, for example, from the two welds between the adapter and the pole lug 310 and between the adapter and the top cover structure 210 to one weld between the pole lug 310 and the top cover structure 210, which is conducive to improving the energy density of the corresponding battery cell. In addition, the assembly method can reduce the need for the use of the adapter and reduce the corresponding welding process, improve the assembly efficiency, and reduce the overall manufacturing cost.

[0051] In addition, the pole 211, the pole lug 310 of the first bare battery cell 300 and the pole lug 310 of the second bare battery cell 300 are welded together and fixed by ultrasonic welding. Compared with the laser welding process, ultrasonic welding can reduce welding slag metal particles, reduce the risk of battery short circuit and fire caused by detached welding slag metal particles, and reduce the need for glue dispensing process to cover the welding slag metal particles, thereby reducing the overall manufacturing cost of the battery cell.

[0052] In some embodiments, reference Figure 5 The step of forming a 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: A cavity 201 is formed on a side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300 , for example, the cavity 201 is formed by casting, machining, or the like.

[0053] In some embodiments, reference Figure 5 , the assembly method further comprises the following steps: One end of the pole 211 is protruded from the top cover structure 210, for example, by making the height of the pole 211 greater than the thickness of the top cover structure 210, and making one end surface of the pole 211 flush with one end surface of the top cover structure 210; The step of forming a cavity 201 on a 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: A cavity 201 is formed on an end surface of the pole 211 that protrudes from the top cover structure 210 .

[0054] In this embodiment, the assembly method forms a cavity 201 on the end face of one end of the pole 211 protruding from the top cover structure 210, so that the pole 211 can be fixed by the boss 121 of the ultrasonic welding seat 120 through the cavity 201, thereby improving the position stability of the pole lug 310 of the first bare battery cell 300, the pole lug 310 of the second bare battery cell 300 and the pole 211 of the top cover structure 210 during the welding process, which is beneficial to improving the weld quality between the pole lug 310 of the first bare battery cell 300, the pole lug 310 of the second bare battery cell 300 and the pole 211 of the top cover structure 210, which is beneficial to reducing the limitation of the weld quality on the current density, and is beneficial to improving the energy density of the corresponding battery cell.

[0055] In some embodiments, reference Figure 4 , Figure 5 and Figure 6 , the assembly method further comprises the following steps: A support plate 130 is provided, a groove 131 is provided on the surface of the support plate 130, and a through hole 132 is provided on the bottom wall of the groove 131; wherein the groove 131 and the through hole 132 can be formed by casting, injection molding, machining, etc., respectively.

[0056] The top cover structure 210 is placed in the groove 131, and the side of the top cover structure 210 with the cavity 201 faces the through hole 132. Specifically, the placement can be performed by a mechanism such as a robot arm, or by manual placement by an operator.

[0057] In this embodiment, the assembly method is to place the top cover structure 210 into the groove 131, and make the side of the top cover structure 210 with the 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 cavity 201. The top cover structure 210 is reduced in force on the support plate 130 due to welding vibration, which is beneficial for the support plate 130 to have sufficient structural strength when the groove 131 is provided, and is beneficial for 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 in 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 for reducing the risk of accidental bending of the pole ear 310.

[0058] Furthermore, the above-mentioned step of placing the top cover structure 210 into the groove 131 and making the side of the top cover structure 210 with the cavity 201 facing the through hole 132 includes: The pole 211 protrudes from one end of the top cover structure 210 (for example Figure 5 The upper end of Figure 5 The pole 211 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 211.

[0059] In this embodiment, the assembly method is to improve the positioning efficiency of the top cover structure 210 through the groove 131 of the support plate 130 by allowing one end of the pole 211 protruding from the top cover structure 210 to pass through the through hole 132 and abut against the hole wall of the through hole 132, thereby helping to improve the overall assembly efficiency.

[0060] In some embodiments, reference Figure 4The assembly method may further include: providing at least one stopper 133 on one side of the support plate 130 provided with the groove 131, the stopper 133 being provided at the outer edge of the support plate 130, and the stopper 133 being used to abut against the outer edge of the bare battery cell 300. The support plate 130 and the stopper 133 may be provided as an integral part, and of course the support plate 130 and the stopper 133 may also be connected by welding, clamping, plugging, etc.

[0061] 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 .

[0062] In some embodiments, reference Figure 4 The assembly method may further include: providing at least two limit blocks 133 on the outer edge of the support plate 130 , and the limit blocks 133 are arranged at intervals along the outer edge of the support plate 130 , for example, multiple limit blocks 133 may be arranged at intervals along the circumference of the support plate 130 .

[0063] In this embodiment, at least two limit blocks 133 spaced apart along the outer edge of the support plate 130 increase the support position for the bare cell 300 , thereby improving the placement stability of the bare cell 300 on the support plate 130 .

[0064] In some embodiments, reference Figure 6 , the above-mentioned assembly method further comprises the following steps: For the pole 211, the pole ear 310 of the first bare cell 300 and the pole ear 310 of the second bare cell 300 stacked in sequence, the pole 211 is respectively abutted against the side of the pole ear 310 of the second bare cell 300 and the side of the pole ear 310 of the second bare cell 300 is abutted against the pole 211, so that the pole 211, the pole ear 310 of the first bare cell 300 and the pole ear 310 of the second bare cell 300 are relatively close and compacted. This step can be performed before the above step S300 (welding step).

[0065] In this embodiment, the assembly method improves the positional stability of the pole lug 310 of the first bare cell 300, the pole lug 310 of the second bare cell 300, and the pole 211 of the top cover structure 210 during the welding process by respectively abutting the pole 211 on one side of the pole lug 310 of the second bare cell 300 and the pole lug 310 of the second bare cell 300, which is beneficial to improving the weld quality between the pole lug 310 of the first bare cell 300, the pole lug 310 of the second bare cell 300, and the pole 211 of the top cover structure 210, reducing the limitation of the weld quality on the current density, and improving the energy density of the corresponding battery cell.

[0066] In some embodiments, reference Figure 6 as well as Fig.15 For the pole 211, the pole ear 310 of the first bare cell 300 and the pole ear 310 of the second bare cell 300 stacked in sequence, the steps of respectively abutting against the side of the pole 211 facing away from the pole ear 310 of the second bare cell 300 and the side of the pole ear 310 of the second bare cell 300 facing away from the pole 211 include: Step S210, using the ultrasonic welding seat 120 to abut against the side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300; Step S220, using the ultrasonic welding head 110 to abut against the side of the pole ear 310 of the second bare battery cell 300 that faces away from the pole 211; The step of integrally welding and fixing the pole column 211, the pole tab 310 of the first bare cell 300 and the pole tab 310 of the second bare cell 300 stacked in sequence by ultrasonic welding (the above-mentioned step S300) includes: The vibration direction of the ultrasonic horn 110 is parallel to the surface of the pole lug 310 and intersects with the height direction of the pole lug 310, for example Figure 6 The height direction of the middle pole ear 310 is arranged along the Y direction in the figure, and the vibration direction of the ultrasonic horn 110 is arranged parallel to the X direction in the figure.

[0067] 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, thereby facilitating 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 facilitating reducing the risk of the ultrasonic horn 110 accidentally hitting the bare battery cell 300.

[0068] In some embodiments, reference Figure 7 and Fig.15 , the assembly method further comprises the following steps: 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).

[0069] 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.

[0070] 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: 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).

[0071] In this embodiment, the assembly method reduces the risk of the top cover structure 210 moving relative to the ultrasonic welding seat 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, thereby reducing the energy consumed between the ultrasonic welding seat 120 and the top cover structure 210, so that the welding energy is more concentrated between the top cover structure 210 and the pole lug 310, and reducing the risk of a cold weld between the top cover structure 210 and the pole lug 310. In addition, since the risk of the top cover structure 210 moving relative to the ultrasonic welding seat 120 is reduced, the risk of the boss 121 on the end surface of the ultrasonic welding seat 120 being worn by the top cover structure 210 is reduced, and the overall service life of the ultrasonic welding seat 120 is longer, thereby reducing the replacement frequency of the ultrasonic welding seat 120 and reducing the overall use cost of the ultrasonic welding seat 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 seat 120 is reduced, which is conducive to improving the overall quality of the corresponding battery cell.

[0072] In some embodiments, reference Figure 7 , Figure 8 or Fig. 9 , the above-mentioned assembly method further comprises the following steps: The side wall of the boss 121 has a first inclined wall segment 122. The first inclined wall segment 122 can be understood as a wall segment inclined in the height direction of the boss 121, for example, inclined in the height direction of the boss 121. Figure 7 wherein, the entire side wall surface of the boss 121 may be inclined, or a portion of the side wall surface of the boss 121 may be inclined, and this embodiment is not limited thereto.

[0073] The side wall of the cavity 201 has a second inclined wall segment 202. The second inclined wall segment 202 can be understood as a wall segment inclined in the depth direction of the cavity 201, for example, inclined in the depth direction of the cavity 201. Figure 7 wherein, the entire side wall surface of the concave cavity 201 may be inclined, or a portion of the side wall surface of the concave cavity 201 may be inclined, and this embodiment is not limited thereto.

[0074] 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: The first inclined wall section 122 is abutted against the second inclined wall section 202, and the ultrasonic welding seat 120 and the top cover structure 210 are relatively moved along the surface of the top cover structure 210. For example, the first inclined wall section 122 and the second inclined wall section 202 can be arranged relative to each other in position, so that the first inclined wall section 122 abuts against the second inclined wall section 202, so that the ultrasonic welding seat 120 and the top cover structure 210 are relatively moved along the surface of the top cover structure 210. It can be understood that, in the case where there is a certain deviation between the relative positions of the boss 121 and the cavity 201 and the deviation is small, during the process of the boss 121 being embedded in the cavity 201, the boss 121 can, through the mutual abutment between the first inclined wall section 122 and the second inclined wall section 202, convert the movement of the boss 121 along the height direction relative to the cavity 201 into the movement of the top cover structure 210 perpendicular to the height direction of the boss 121, for example, into Figure 6 , Figure 7 The ultrasonic welding seat 120 and the top cover structure 210 are moved in the horizontal direction, thereby guiding the top cover structure 210, and improving the alignment degree between 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 abutment between the first inclined wall section 122 and the second inclined wall section 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.

[0075] In this embodiment, the assembly method is facilitated to accommodate the positioning deviation between the ultrasonic welding seat 120 and the top cover structure 210 by making the first inclined wall segment 122 abut against the second inclined wall segment 202, and making the ultrasonic welding seat 120 and the top cover structure 210 move relative to each other along the surface of the top cover structure 210, thereby improving the alignment degree between the ultrasonic welding seat 120 and the top cover structure 210.

[0076] In some embodiments, reference Figure 7The above-mentioned assembly method may include: making a preset angle B between the end face of the ultrasonic welding seat 120 with the boss 121 (for example, the upper end face in the figure) and the first inclined wall section 122, and the preset angle B is greater than 90 degrees and less than or equal to 120 degrees, wherein the preset angle B can be set to 95 degrees, 105 degrees, 115 degrees, 120 degrees, etc.

[0077] In this embodiment, the preset angle B is greater than 90 degrees and less than or equal to 120 degrees, so that the side wall surface of the boss 121 is relatively steep; when the root size of the boss 121 and the height of the boss 121 are constant, 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 relative movement between the top cover structure 210 and the ultrasonic welding seat 120 to cause a cold weld is reduced, and the risk of dust formation due to wear is reduced.

[0078] In some embodiments, reference Figure 7 and Figure 8 The step of making the side wall surface of the boss 121 have the first inclined wall surface section 122 includes: The arc-shaped first inclined wall segment 122 is formed, and the arc-shaped central axis of the first inclined wall segment 122 (refer to Figure 8 The first inclined wall segment 122 has an arc-shaped central axis that is perpendicular to the top surface of the boss 121 or inclined to the top surface of the boss 121. Specifically, the boss 121 may be set as Figure 8 The cone in the middle.

[0079] The step of providing the side wall surface of the cavity 201 with a second inclined wall surface segment 202 comprises: An arc-shaped second inclined wall segment 202 is formed, and the arc-shaped central axis of the second inclined wall segment 202 intersects with the surface of the top cover structure 210 , so that the arc-shaped second inclined wall segment 202 is stably abutted against the arc-shaped first inclined wall segment 122 .

[0080] In this embodiment, the assembly method can be used to facilitate guiding in more directions of the arc surface by setting the first inclined wall segment 122 and the second inclined wall segment 202 to be arc-shaped. For example, Figure 8 Guiding in the left-right direction and the front-back direction is beneficial to further improve the alignment degree between the ultrasonic welding seat 120 and the top cover structure 210.

[0081] In some embodiments, reference Fig. 9 and Fig.10 , the above-mentioned assembly method further comprises the following steps: The side wall surface of the boss 121 has a first flat wall surface section 123. For example, the boss 121 can be set as a prism or a pyramid. The side wall surface of the cavity 201 has a second flat wall surface segment 203. For example, the cavity 201 can be set as a prismatic cavity or a pyramidal cavity. 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: Make the first flat wall segment 123 abut against the second flat wall segment 203; The step of integrally welding and fixing the pole column 211, the pole tab 310 of the first bare cell 300 and the pole tab 310 of the second bare cell 300 stacked in sequence by ultrasonic welding (the above-mentioned step S300) comprises: The vibration direction of the ultrasonic horn 110 is parallel to the surface of the pole lug 310 and intersects with the height direction of the pole lug 310, and the vibration direction of the ultrasonic horn 110 intersects with the first flat wall section 123. The vibration direction of the ultrasonic horn 110 refers to the X direction in the figure.

[0082] In this embodiment, the assembly method reduces the local pressure of the vibrating ultrasonic horn 110 on the boss 121 by making the vibration direction of the ultrasonic horn 110 parallel to the surface of the pole lug 310 and intersecting at the height direction of the pole lug 310, and makes the vibration direction of the ultrasonic horn 110 intersect at the first flat wall section 123, thereby reducing the risk of the top of the boss 121 being worn by the top cover structure 210, reducing the risk of relative movement between the top cover structure 210 and the ultrasonic welding seat 120 to cause a cold weld, and reducing the risk of dust formation due to wear.

[0083] In some embodiments, reference Figure 7 and Fig.15 , the above-mentioned assembly method further comprises the following steps: The dimension L1 of the root of the boss 121 in a preset direction is made larger than the dimension L2 of the mouth of the cavity 201 in a preset direction, wherein the preset direction is perpendicular to the height direction of the boss 121, for example Figure 7 The preset direction is parallel to the left-right direction. This step may be included in the above step S010 (forming a boss 121 at one end of the ultrasonic welding seat 120 facing the top cover structure 210) or the above step S020 (forming a cavity 201 at one side of the top cover structure 210 facing away from the pole ear 310 of the second bare battery cell 300), or this step may be performed after step S010 and step S020.

[0084] In this embodiment, the assembly method makes the dimension L1 of the root of the boss 121 in the preset direction larger than the dimension L2 of the mouth of the cavity 201 in the preset direction, so that the root of the boss 121 can be embedded in the mouth of the cavity 201 by utilizing elastic-plastic deformation, thereby forming an interference fit between the root of the boss 121 and the mouth of the cavity 201, thereby improving the connection stability between the ultrasonic welding seat 120 and the top cover structure 210, and further reducing the risk of a cold weld caused by the movement of the top cover structure 210 relative to the ultrasonic welding seat 120.

[0085] In some embodiments, the step of embedding the boss 121 into the cavity 201 and causing the side wall surface of the boss 121 to abut against the side wall surface of the cavity 201 includes: The root of the boss 121 is embedded in the cavity 201, and the surface of the ultrasonic welding seat 120 facing the top cover structure 210 is abutted against the top cover structure 210; for example, the relatively close proximity of the ultrasonic welding head 110 and the ultrasonic welding seat 120 can provide a force to embed the root of the boss 121 into the cavity 201. This step can be included in the above step S210 (the ultrasonic welding seat 120 abuts against the side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300).

[0086] In this embodiment, the assembly method improves the connection stability between the ultrasonic welding seat 120 and the top cover structure 210 by embedding the root of the boss 121 into the cavity 201 and making the ultrasonic welding seat 120 abut against the top cover structure 210 toward the surface of the top cover structure 210, thereby further reducing the risk of a cold weld caused by the top cover structure 210 moving relative to the ultrasonic welding seat 120.

[0087] In some embodiments, reference Fig.11 , Fig.12 and Fig.13 The ultrasonic welding head 110 is provided with a welding tooth 111 at one end of the pole ear 310 of the second bare battery cell 300, and the step of forming a boss 121 at one end of the ultrasonic welding seat 120 facing the top cover structure 210 includes: The cross-sectional area of ​​the root of the boss 121 is larger than the cross-sectional area of ​​the root of the welding tooth 111 , which can be understood as the boss 121 being thicker than the welding tooth 111 .

[0088] 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 tooth 111, so that the area of ​​the top of the boss 121 is relatively large, thereby further reducing the risk of the top of the boss 121 being worn by the top cover structure 210, further reducing the risk of relative movement between the top cover structure 210 and the ultrasonic welding seat 120 to cause a cold weld, and reducing the risk of dust formation due to wear.

[0089] In some embodiments, reference Fig.11 The step of welding and fixing the pole column 211, the pole tab 310 of the first bare cell 300 and the pole tab 310 of the second bare cell 300 stacked in sequence by ultrasonic welding (the above-mentioned step S300) includes: The width W1 of the formed weld mark 311 is smaller than the distance W2 from the weld mark 311 to the cell body 320 of one of the bare cells 300, wherein the width direction of the weld mark 311 is consistent with the height direction of the tab 310, for example, respectively along Fig.11 The up and down directions in .

[0090] In this embodiment, the assembly method makes the width W1 of the formed weld mark 311 smaller than the distance W2 from the weld mark 311 to the battery body 320 of one of the bare battery cells 300. It can be understood that the welding position and the weld mark 311 are farther away from the battery body 320, which is beneficial to reduce the impact of ultrasonic welding vibration on the connection corners of the tab 310 and the battery body 320, and is beneficial to reduce the risk of the connection corners of the tab 310 and the battery body 320 being pulled and torn due to welding vibration, which is beneficial to improve the overall quality of the corresponding battery cell.

[0091] In some embodiments, the step of making the width W1 of the formed weld mark 311 smaller than the distance W2 from the weld mark 311 to the cell body 320 of one of the bare cells 300 includes: The ratio of the width W1 of the formed weld mark 311 to the distance W2 from the weld mark 311 to the cell body 320 of one of the bare cells 300 is less than or equal to 0.5, thereby helping to further reduce the risk of the connection corners of the tab 310 and the cell body 320 being pulled and torn due to welding vibration, and helping to further improve the overall quality of the corresponding battery cell.

[0092] Reference 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 a top cover structure 210, the bare cell 300 includes a tab 310, and the top cover structure 210 includes a pole 211, and the assembly method includes the following steps: Stacking the tab 310 of the first bare battery cell 300 onto the pole 211; The tab 310 of the second bare cell 300 is stacked on the tab 310 of the first bare cell 300, so that the pole 211, the tab 310 of the first bare cell 300 and the tab 310 of the second bare cell 300 are stacked in sequence; The pole column 211, the pole tab 310 of the first bare cell 300 and the pole tab 310 of the second bare cell 300 which are stacked in sequence are integrally welded and fixed by ultrasonic welding.

[0093] The assembly method further comprises the following steps: For the pole 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 stacked in sequence, the side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300 and the side of the pole ear 310 of the second bare battery cell 300 facing away from the pole 211 are respectively abutted.

[0094] For the pole 211, the pole ear 310 of the first bare cell 300 and the pole ear 310 of the second bare cell 300 stacked in sequence, the steps of respectively abutting against the side of the pole 211 facing away from the pole ear 310 of the second bare cell 300 and the side of the pole ear 310 of the second bare cell 300 facing away from the pole 211 include: The ultrasonic welding seat 120 abuts against the side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300; The ultrasonic welding head 110 is used to abut against the side of the pole ear 310 of the second bare battery cell 300 facing away from the pole 211; The step of integrally welding and fixing the pole column 211, the pole tab 310 of the first bare cell 300 and the pole tab 310 of the second bare cell 300 stacked in sequence by ultrasonic welding includes: The vibration direction of the ultrasonic horn 110 is parallel to the surface of the electrode tab 310 and intersects with the height direction of the electrode tab 310 .

[0095] For the pole 211, the pole ear 310 of the first bare cell 300 and the pole ear 310 of the second bare cell 300 stacked in sequence, the steps of respectively abutting against the side of the pole 211 facing away from the pole ear 310 of the second bare cell 300 and the side of the pole ear 310 of the second bare cell 300 facing away from the pole 211 include: The ultrasonic welding seat 120 abuts against the side of the pole 211 facing away from the pole ear 310 of the second bare battery cell 300; The ultrasonic welding head 110 is used to abut against the side of the pole ear 310 of the second bare battery cell 300 facing away from the pole 211; The assembly method further comprises the following steps: A boss 121 is formed at one end of the ultrasonic welding seat 120 facing the top cover structure 210; A cavity 201 is formed on a side of the top cover structure 210 facing away from the tab 310 of the second bare battery cell 300; 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: The boss 121 is inserted into the cavity 201 and the side wall surface of the boss 121 abuts against the side wall surface of the cavity 201 .

[0096] The assembly method further comprises the following steps: The side wall surface of the boss 121 has a first inclined wall surface section 122; The side wall surface of the cavity 201 has a second inclined wall surface section 202; 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: The first inclined wall segment 122 is abutted against the second inclined wall segment 202 , and the ultrasonic welding seat 120 and the top cover structure 210 are relatively moved along the surface of the top cover structure 210 .

[0097] The assembly method further comprises the following steps: The side wall surface of the boss 121 has a first flat wall surface section 123; The side wall surface of the cavity 201 has a second flat wall surface section 203; 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: Make the first flat wall segment 123 abut against the second flat wall segment 203; The step of integrally welding and fixing the pole column 211, the pole tab 310 of the first bare cell 300 and the pole tab 310 of the second bare cell 300 which are stacked in sequence by ultrasonic welding comprises: The vibration direction of the ultrasonic horn 110 is parallel to the surface of the pole lug 310 and intersects with the height direction of the pole lug 310 , and the vibration direction of the ultrasonic horn 110 intersects with the first flat wall segment 123 .

[0098] The assembly method further comprises the following steps: The size of the root of the boss 121 in a preset direction is made larger than the size 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 .

[0099] 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: The root of the boss 121 is embedded in the cavity 201 , and the surface of the ultrasonic welding seat 120 facing the top cover structure 210 is abutted against the top cover structure 210 .

[0100] The ultrasonic welding head 110 is provided with a welding tooth 111 at one end of the pole ear 310 of the second bare battery cell 300, and the step of forming a boss 121 at one end of the ultrasonic welding seat 120 facing the top cover structure 210 includes: The cross-sectional area of ​​the root of the boss 121 is larger than the cross-sectional area of ​​the root of the welding tooth 111 .

[0101] The assembly method further comprises the following steps: A support plate 130 is provided, a groove 131 is provided on the surface of the support plate 130, and a through hole 132 is provided on the bottom wall of the groove 131; The top cover structure 210 is placed into the groove 131 , with the side of the top cover structure 210 where the cavity 201 is disposed facing the through hole 132 .

[0102] The assembly method further comprises the following steps: One end of the pole 211 is protruded from the top cover structure 210; The step of forming a cavity 201 on a side of the top cover structure 210 facing away from the tab 310 of the second bare battery cell 300 includes: A cavity 201 is formed on an end surface of the pole 211 that protrudes from the top cover structure 210 .

[0103] The steps of placing the top cover structure 210 into the groove 131 and making the side of the top cover structure 210 with the cavity 201 facing the through hole 132 include: One end of the pole 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 .

[0104] The bare cell 300 includes a tab 310 and a cell body 320. The step of welding and fixing the sequentially stacked poles 211, the tab 310 of the first bare cell 300, and the tab 310 of the second bare cell 300 integrally by ultrasonic welding includes: The width of the formed weld mark 311 is made smaller than the distance from the weld mark 311 to the cell body 320 of one of the bare cells 300 , and the width direction of the weld mark 311 is consistent with the height direction of the tab 310 .

[0105] The present application also proposes a battery cell, which includes a battery casing, the above-mentioned top cover structure 210 and at least two bare cells 300. The battery casing 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 cell 300 is received in the receiving cavity, and the bare cell 300 is assembled with the top cover structure 210 using the above-mentioned assembly method of the bare cell 300.

[0106] Among them, the bare cell 300 of the battery cell is assembled with the top cover structure 210 using the above-mentioned bare cell 300 assembly method, and the pole lug 310 of the first bare cell 300, the pole lug 310 of the second bare cell 300 and the pole 211 of the top cover structure 210 can be welded and fixed as a whole by ultrasonic welding, so that the pole lug 310 of the first bare cell 300 and the pole lug 310 of the second bare cell 300 are directly fixed to the top cover structure 210, reducing the limitation of the adapter and its weld on the current density, which is conducive to improving the energy density of the corresponding battery cell. In addition, the battery cell can reduce the need for the use of the adapter and reduce the corresponding welding process, improve the assembly efficiency, and reduce the overall manufacturing cost.

[0107] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structural changes made by using the contents of the present application specification and drawings under the technical concept of the present application, or directly / indirectly applied in other related technical fields are 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 that faces away from the pole ear of the second bare battery cell through 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 battery 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: 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 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 step of embedding the boss into the cavity and causing the side wall surface of the boss to abut against the side wall surface of the cavity comprises: 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 step of embedding the boss into the cavity and causing the side wall surface of the boss to abut against the side wall surface of the cavity comprises: 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 step of embedding the boss into the cavity and causing the side wall surface of the boss to abut against the side wall surface of the cavity comprises: 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 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 group described in any one of claims 1 to 11.

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