Electrode assembly and electrochemical apparatus

Abstract

The present application relates to the technical field of batteries, and discloses an electrode assembly and an electrochemical apparatus. The electrode assembly comprises a battery cell body, multiple first tab units and a first welding plate, the multiple first tab units being connected to the battery cell body. Some of the first tab units are clustered to form a first tab group, and the remaining first tab units clustered to form a second tab group; along a first direction, the first welding plate has a first surface and a second surface opposite to each other, the first surface facing the battery cell body and making insulated contact with the first tab units, and the second surface facing away from the battery cell body. The first tab group is bent to abut against the second surface, and the second tab group is bent to overlap with and electrically connect to the first tab group. In the present application, the first tab group and the second tab group may be welded, with external conductive sheets, etc., on the same surface of the first welding plate in a third direction to form a staggered configuration, effectively reducing the space occupied in the first direction, reducing the volume of the electrode assembly, and helping to improve the energy density of the electrochemical apparatus.

Description

Electrode assembly and electrochemical device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on January 8, 2024, with application number 202410027106.4 and entitled “Electrode Assembly and Electrochemical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments of the present application relate to the field of battery technology, and in particular to an electrode assembly and an electrochemical device. Background Art

[0004] Electrochemical devices are used to store or release electrical energy to power electrical devices. Electrode assemblies in electrochemical devices employ a multi-tab structure, which can effectively improve charge and discharge performance. In existing technologies, multiple tabs in an electrode assembly are stacked and converged to form a tab cluster, which is then bent multiple times and extended out of the packaging. This tab cluster structure occupies a significant amount of headroom, increasing the size of the electrochemical device or reducing its energy density.

[0005] Application Contents

[0006] The embodiments of the present application provide an electrode assembly and an electrochemical device, which can solve the problem that the ends of the electrode assembly occupy a large amount of space.

[0007] A technical solution adopted in an embodiment of the present application is to provide an electrode assembly, including a battery cell body, a first tab unit, and a first transfer plate. A plurality of first tab units are connected to a first end portion of the battery cell body, wherein some of the first tab units are gathered to form a first tab group, and the remaining first tab units are gathered to form a second tab group. Along a first direction, the first transfer plate has a first surface and a second surface facing each other, the first surface facing the battery cell body and insulated from and abutting the first tab units, and the second surface facing away from the battery cell body. The first tab group is bent to abut the second surface, and the second tab group is bent to extend to one side of the second surface and electrically connected to the first transfer plate.

[0008] In the present application, by gathering the first tab units to form a first tab group and a second tab group, the space occupied in the first direction is effectively reduced, the volume of the electrode assembly is reduced, and the energy density of the electrochemical device is improved.

[0009] In some embodiments, along the first direction, the first tab group and the second tab group are at least partially overlapped after being bent.

[0010] In the above solution, the first tab group and the second tab group are directly overlapped after being bent, without the need for other processing methods, which can reduce processing costs. In addition, the overlapping arrangement can improve the stability of the connection.

[0011] In some embodiments, the number N1 of the first tab units in the first tab group and the number N2 of the first tab units in the second tab group satisfy the following: 0.2 ≤ N1 / N2 ≤ 1. By dividing the plurality of first tab units into two thinner tab groups, the head space in the first direction can be reduced, and the bending rebound stress of the first tab group and the second tab group can be reduced. This not only reduces the pulling force at the connection between the first tab group and the second tab group and the battery cell body, but also improves the fixing effect between the first tab group and the second tab group and the first transfer plate, thereby improving the stability of the connection.

[0012] In some embodiments, 0.8 ≤ N1 / N2 ≤ 1. By dividing the plurality of first tab units into a first tab group and a second tab group of approximately equal number, the difference in thickness between the first tab group and the second tab group can be minimized, making it easier to bend and stack the two tab groups. In other examples, when the free ends of the first tab group and the second tab group need to be trimmed, a structure with approximately equal thickness can reduce the difficulty of trimming the two tabs.

[0013] In some embodiments, along the second direction, the first transfer plate has a first side surface and a second side surface relative to each other, the first side surface being close to the bend of the first tab group, and the second side surface being close to the bend of the second tab group, wherein the second direction is perpendicular to the first direction; the first tab group has a first end and a second end relative to each other, the first end of the first tab group being connected to the battery cell body, and along the second direction, the distance L1 between the second end of the bent first tab group and the second side surface of the first transfer plate satisfies: 0 mm ≤ L1 ≤ K / 2, wherein K is the distance between the first side surface and the second side surface of the first transfer plate in the second direction. By controlling the distance L1 between the second end of the bent first tab group and the second side surface of the first transfer plate within an appropriate range, the bending of the first tab group can be prevented from affecting the bending of the second tab group, and sufficient contact surface between the second end of the bent first tab group and the second surface of the first transfer plate can be achieved after the bending, thereby ensuring current transmission capability.

[0014] In some embodiments, along the second direction, the battery cell body has a first main body surface and a second main body surface that are opposite to each other, the first main body surface being adjacent to the first side surface of the first transfer plate, and the second main body surface being adjacent to the second side surface of the first transfer plate; the second tab group has a first end and a second end that are opposite to each other, the first end of the second tab group being connected to the battery cell body, and along the second direction, a distance L2 between the second end of the second tab group after being bent and the first main body surface satisfies the following: 0 mm ≤ L2 ≤ K / 2. By controlling the distance L2 between the second end of the second tab group after being bent and the first main body surface within an appropriate range, the second tab group can be ensured to have sufficient contact area with the first tab group after being bent, thereby ensuring current transmission capacity between the two, and preventing the second end of the second tab group from extending beyond the first main body surface of the battery cell body, thereby occupying additional space and reducing the energy density of the electrochemical device.

[0015] In some embodiments, 0.3 mm ≤ L1 ≤ 1.5 mm; and / or, 0.1 mm ≤ L2 ≤ 1.5 mm.

[0016] In some embodiments, along the third direction, the first transfer plate has opposing third and fourth sides, wherein the first, second, and third directions are perpendicular to each other; along the third direction, a distance L3 of the third side extending beyond the first tab group satisfies the following: 0.5 mm ≤ L3 ≤ 10 mm; and / or, along the third direction, a distance L4 of the fourth side extending beyond the first tab group satisfies the following: 0.5 mm ≤ L4 ≤ 10 mm. In the third direction, the third and / or fourth sides extend beyond the first tab group by a certain distance, so that after the first transfer plate is welded to the first and second tab groups, it can also be welded to external conductive sheets, adapter sheets, or poles in the third direction, thereby reducing the space occupied along the first direction.

[0017] In some embodiments, 3 mm ≤ L3 ≤ 6 mm, and / or 3 mm ≤ L4 ≤ 6 mm. In order to reduce the difficulty and process requirements of welding the first transfer plate to external components while preventing the first transfer plate from extending beyond the first tab group by too much, the distance between the third side surface and / or the fourth side surface and the first tab group should be set moderately.

[0018] In some embodiments, the first transfer plate includes a metal plate and an insulating layer stacked along a first direction, with the insulating layer being adjacent to the battery cell body and abutting against the first and second electrode tab groups, respectively. Because the first and second electrode sheets in the battery cell body are alternately arranged and have opposite polarities, i.e., both the first and second electrode sheets are located at the first end of the battery cell body, the insulating layer is disposed between the metal plate and the first end of the battery cell body to prevent the metal plate from contacting the end of the second electrode sheet and causing a short circuit.

[0019] In some embodiments, along a first direction, the projection of the metal plate lies within the projection of the insulating layer. In some embodiments, along a second direction, the insulating layer is larger than the metal layer; and / or along a third direction, the insulating layer is larger than the metal layer, with the first, second, and third directions being perpendicular to each other. This structure prevents short circuits caused by direct contact between the metal plate and the second electrode sheet when the electrochemical device is subjected to vibration or mechanical impact during testing or use, thereby ensuring the insulating effectiveness of the insulating layer.

[0020] In some embodiments, the insulating layer includes a first adhesive layer, a thermal insulation layer, and a second adhesive layer. Along a first direction, the first adhesive layer bonds the metal plate and the thermal insulation layer, respectively, and the second adhesive layer bonds the thermal insulation layer and the first and second tab groups, respectively. With the above structure, the insulating layer can provide both insulation and bonding while also providing thermal insulation, thereby preventing the high temperature of laser welding the first and second tab groups to the metal plate in the first transfer plate from causing high-temperature failure of the first and / or second pole pieces, or from causing high-temperature shrinkage of the diaphragm, resulting in a direct contact short circuit between the first and second pole pieces.

[0021] In some embodiments, the sum of the thicknesses of the first transfer plate and the insulating layer is G, the thickness of the first tab unit is g, the number of tabs in the first tab group is n1, and the number of tabs in the second tab group is n2, where n1 ≤ n2, and G satisfies the following: 0.1 mm ≤ G ≤ n1 * g. This allows the sum of the thicknesses of the first transfer plate and the insulating layer to be controlled within a suitable range, thereby reducing the thicknesses of the first tab group, the second tab group, and the insulating plate in the first direction X of the battery cell 10.

[0022] In some embodiments, along the first direction, the first tab group and the second tab group do not overlap on the second surface after being bent. The two tab groups do not overlap on the second surface after being bent, which can further reduce head space.

[0023] In some embodiments, the bent portions of the first tab group and the second tab group are arranged along a second direction on the second surface, and the second direction is perpendicular to the first direction.

[0024] In some embodiments, the electrode assembly further includes a plurality of second pole lug units, and the plurality of second pole lug units are all connected to the first end of the battery cell body, or are all connected to the second end of the battery cell body, wherein some of the second pole lug units are gathered to form a third pole lug group, and the remaining portion of the second pole lug units are gathered to form a fourth pole lug group, and the first end and the second end of the battery cell body are arranged relative to each other in the first direction; the electrode assembly further includes a second transfer welding plate, and along the first direction, the second transfer welding plate has a relative third surface and a fourth surface, the third surface faces the battery cell body and is insulated and abutted against the second pole lug unit, and the fourth surface faces away from the battery cell body, and the third pole lug group is bent and abutted against the fourth surface, and the fourth pole lug group is bent and overlaps with the third pole lug group and is electrically connected.

[0025] The present application provides an electrochemical device, comprising the above-mentioned electrode assembly, the electrochemical device also comprising an electrode column, the electrode column being welded to a transfer plate, the projection of the electrode column not overlapping with the first electrode tab group along a first direction, and / or the projection of the electrode column not overlapping with the second electrode tab group along the first direction.

[0026] The electrode assembly of the present application includes a battery cell body, a plurality of first tab units, and a first transfer plate. The plurality of first tab units are all connected to the first end of the battery cell body, wherein some of the first tab units are gathered to form a first tab group, and the remaining first tab units are gathered to form a second tab group; along the first direction, the first transfer plate has a first surface and a second surface relative to each other, the first surface facing the battery cell body and insulated and abutting against the first tab units, the second surface facing away from the battery cell body, the first tab group abutting against the second surface after being bent, and the second tab group overlapping and electrically connected with the first tab group after being bent. Through the above-mentioned structural setting, the stacking thickness of the first tab group and the second tab group can be reduced, and the difficulty of bending them can be reduced, thereby solving the problem in the prior art that the entire first tab unit is uncontrolled when bending and the rebound stress is large, which makes it difficult to assemble the electrode assembly in the shell of the electrochemical device. In addition, the first electrode tab unit and external conductive sheets, adapter sheets or poles and other components can be welded in the third direction on the same surface of the first transfer plate, that is, the first electrode tab group and the second electrode tab group can be staggered with external components in the third direction, effectively reducing the space occupied in the first direction, reducing the volume of the electrode assembly, and helping to improve the energy density of the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions in the specific embodiments of this application, the following briefly introduces the drawings required for describing the specific embodiments. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0028] FIG1 is a schematic diagram of an electrode assembly according to an embodiment of the present application;

[0029] FIG2 is a schematic diagram of an electrode assembly from another perspective according to an embodiment of the present application;

[0030] FIG3 is a cross-sectional view of the electrode assembly along line AA in FIG2 according to an embodiment of the present application;

[0031] FIG4 is a cross-sectional view of the first transfer plate of the electrode assembly according to an embodiment of the present application taken along line BB in FIG2 ;

[0032] FIG5 is a cross-sectional view of the first transfer plate of the electrode assembly according to another embodiment of the present application taken along line BB in FIG2 ;

[0033] FIG6 is a cross-sectional view of the first transfer plate of the electrode assembly according to another embodiment of the present application taken along line BB in FIG2 .

[0034] The reference numerals in the specific embodiment are as follows: 100 - electrode assembly; 10 - battery cell body; 10a - first end; 10b - second end; 11 - First main body surface; 12-second main body surface; X-first direction; Y-second direction; Z-third direction; 13-first pole piece; 14-second pole piece; 15-diaphragm; 20-first pole lug unit; 21-first pole lug group; 21a-first end of the first pole lug group; 21b-second end of the first pole lug group; 22-second pole lug group; 22a-first end of the second pole lug group; 22b-second end of the second pole lug group; 30-first transfer plate; 31-first surface; 32-second surface; 33-first side surface; 34-second side surface; 35-third side surface; 36-fourth side surface; 37-metal plate; 38-insulating layer; 381-first adhesive layer; 382-thermal insulation layer; 383-second adhesive layer; 40-second pole lug unit; 41-third pole lug group; 42-fourth pole lug group; 50-second transfer plate. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed on" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as being "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "upper", "lower", "inside", "outside", "vertical", "horizontal", etc. used in this specification indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0036] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0037] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0038] Referring to Figures 1 to 3 , the electrode assembly 100 of the present application includes a battery cell body 10, a plurality of first tab units 20, a first transfer plate 30, and a plurality of second tab units 40. Along a first direction X, the battery cell body 10 has a first end 10a and a second end 10b disposed opposite each other. The plurality of first tab units 20 are connected to the first end 10a of the battery cell body 10, and the plurality of second tab units 40 are connected to either the first end 10a or the second end 10b of the battery cell body 10. Some of the first tab units 20 are stacked and assembled to form a first tab group 21, and the remaining first tab units 20 are stacked and assembled to form a second tab group 22. Referring to Figure 3 , along the first direction X, the first transfer plate 30 has a first surface 31 and a second surface 32 facing each other, wherein the first surface 31 faces the battery cell body 10 and is insulated from the first tab units 20. The second surface 32 faces away from the battery cell body 10 . The first tab group 21 is bent to contact the second surface 32 . The second tab group 22 is bent to overlap with the first tab group 21 in the first direction X and is electrically connected thereto.

[0039] In the present application, by adding a first transfer plate 30 and dividing the plurality of first tab units 20 into a first tab group 21 and a second tab group 22, the stacked thickness of the first tab group 21 and the second tab group 22 can be reduced, thereby reducing the difficulty of bending them. This solves the problem in the prior art of uncontrolled bending of the entire first tab unit 20 and the large rebound stress that makes it difficult to assemble the electrode assembly 100 within the housing of the electrochemical device. In the prior art, after the entire first tab unit 20 is bent, it is continued to be welded to external conductive sheets, adapter sheets, or poles in the first direction X, increasing the space occupied in the first direction X. The addition of the first transfer plate 30 in the present application allows the first tab unit 20 and external conductive sheets, adapter sheets, or poles to be welded to the same surface of the first transfer plate 30 in the third direction Z. That is, the first tab group 21 and the second tab group 22 can be staggered with external components in the third direction Z, effectively reducing the space occupied in the first direction X, reducing the volume of the electrode assembly 100, and helping to improve the energy density of the electrochemical device. Furthermore, by adding the structure of the first transfer plate 30, the first end 10a of the battery cell body 10 can be protected, preventing the first tab group 21 and the second tab group 22 from being inserted into the interior of the battery cell body 10 when subjected to external impact, causing damage to the first and second tabs 13 and 14, or even causing a short circuit and fire, thereby effectively ensuring the safety performance of the electrode assembly 100. The first direction X and the third direction Z are approximately perpendicular.

[0040] Regarding the battery cell body 10 described above, referring to Figures 1 and 2 , the battery cell body 10 has a first end 10a and a second end 10b opposite each other along a first direction X. Along a second direction Y, the battery cell body 10 has a first main surface 11 and a second main surface 12. The first main surface 11 is adjacent to the first tab group 21, and the second main surface 12 is adjacent to the second tab group 22. The first direction X, the second direction Y, and the third direction Z are substantially perpendicular to each other.

[0041] Referring to Figure 3 , the battery cell body 10 includes a plurality of first electrode sheets 13, a plurality of second electrode sheets 14, and a plurality of separators 15. The separators 15 are disposed between the first electrode sheets 13 and the second electrode sheets 14 to prevent direct contact between the first electrode sheets 13 and the second electrode sheets 14, thereby preventing a short circuit. The plurality of first electrode sheets 13, the plurality of second electrode sheets 14, and the plurality of separators 15 are stacked to form a laminated battery cell body 10; alternatively, the plurality of first electrode sheets 13, the plurality of second electrode sheets 14, and the plurality of separators 15 are stacked and wound to form a wound battery cell body 10. Each first electrode sheet 13 is electrically connected to at least one first tab unit 20, and each second electrode sheet 14 is electrically connected to at least one second tab unit 40.

[0042] In some embodiments, the number N1 of the first tab units 20 in the first tab group 21 and the number N2 of the first tab units 20 in the second tab group 22 satisfy the following: 0.2≤N1 / N2≤1. By dividing the plurality of first tab units 20 into two thinner tab groups, on the one hand, the head space in the first direction X can be reduced, and on the other hand, the bending rebound stress of the first tab group 21 and the second tab group 22 can be reduced. This not only reduces the pulling force at the connection between the first tab group 21 and the second tab group 22 and the battery cell body 10, but also improves the fixing effect between the first tab group 21 and the second tab group 22 and the first transfer plate 30, thereby improving the stability of the connection.

[0043] In some embodiments, 0.8 ≤ N1 / N2 ≤ 1. By dividing the plurality of first tab units 20 into roughly equal numbers of first tab groups 21 and second tab groups 22, the difference in thickness between the first tab groups 21 and the second tab groups 22 can be minimized, making it easier to bend and stack the first and second tab groups 21 and 22. In other examples, when the free ends of the first and second tab groups 21 and 22 need to be trimmed, having roughly equal thicknesses can reduce the difficulty of trimming the first and second tab groups.

[0044] In some embodiments, referring to FIG3 , the first tab group 21 has a first end 21 a and a second end 21 b opposite each other, wherein the first end 21 a is electrically connected to the cell body 10, and the second end 21 b is a free end and is bonded to the second surface 32 of the first transfer plate 30. The second tab group 22 has a first end 22 a and a second end 22 b opposite each other, wherein the first end 22 a is connected to the cell body 10, and the second end 22 b is a free end and is bonded to the first tab group 21.

[0045] In some embodiments, referring to FIG. 3 , the first transfer plate 30 has a first side surface 33 and a second side surface 34 opposite each other along the second direction Y. The first side surface 33 is adjacent to the bend of the first tab group 21, and the second side surface 34 is adjacent to the bend of the second tab group 22. The first main surface 11 of the battery cell body 10 is adjacent to the first side surface 33 of the first transfer plate 30, and the second main surface 12 of the battery cell body 10 is adjacent to the second side surface 34 of the first transfer plate 30.

[0046] Along the second direction Y, the distance L1 between the second end 21b of the first tab group 21 after bending and the second side surface 34 of the first transfer plate 30 satisfies the following condition: 0 mm ≤ L1 ≤ K / 2, where K is the distance between the first side surface 33 and the second side surface 34 of the first transfer plate 30 in the second direction Y. A distance L1 ≥ 0 mm indicates that the second end 21b of the first tab group 21 does not extend beyond the second side surface 34 in the second direction Y, but is instead located within the second surface 32 of the first transfer plate 30, thereby preventing the second end 21b of the first tab group 21 from affecting the bending of the second tab group 22. When the second end 21b of the first tab group 21 extends beyond the second side surface 34, L1 is a negative number. A distance L1 ≤ K / 2, meaning that the length of the second end 21b of the first tab group 21 after bending in the second direction Y is at least half the width of the first transfer plate 30, allows for a larger contact area between the bent first tab group 21 and the second surface 32 of the first transfer plate 30 to ensure current transmission.

[0047] Furthermore, the distance L1 between the bent second end 21b of the first tab group 21 and the second side surface 34 of the first transfer plate 30 satisfies the following: 0.3 mm ≤ L1 ≤ 1.5 mm. Because when the second end 21b of the first tab group 21 is flush with the second side surface 34, the second tab group 22 has a larger bend protrusion at the second side surface 34 of the first transfer plate 30, making bending of the second tab group 22 difficult and occupying more space in the first direction X and the second direction Y. To further reduce the occupied space, a certain amount of space can be reserved between the second end 21b of the first tab group 21 and the second side surface 34. As an example, the distance L1 is ≥ 0.3 mm. When the second end 21b of the first tab group 21 is within the second surface 32 of the first transfer plate 30, a larger overlap area between the first tab group 21 and the first transfer plate 30 facilitates current transmission. Therefore, a large amount of space does not need to be reserved between the second end 21b of the first tab group 21 and the second side surface 34. As an example, the distance L1 is ≤ 1.5 mm.

[0048] Continuing with Figure 3, along the second direction Y, the distance L2 between the bent second end 22b of the second tab group 22 and the first main body surface 11 satisfies the following conditions: 0 mm ≤ L2 ≤ K / 2. When the distance L2 is 0 mm, the second end 22b of the second tab group 22 is flush with the first main body surface 11 of the cell body 10 in the second direction Y, without protruding beyond the first main body surface 11. This facilitates assembly of the electrode assembly 100 with the housing of the electrochemical device. If the second end 22b of the second tab group 22 protrudes beyond the first main body surface 11, it would occupy space within the housing and reduce the energy density of the electrochemical device. When the distance L2 ≤ K / 2, meaning that the bent second end 22b of the second tab group 22 in the second direction Y is at least half the width of the first transfer plate 30, this ensures a larger contact area between the second tab group 22 and the first tab group 21, ensuring current transmission. As an example, the distance L2 satisfies the following conditions: 0.1 mm ≤ L2 ≤ 1.5 mm.

[0049] In some embodiments, referring to FIG. 2 , in the third direction Z, the first transfer plate 30 has opposing third and fourth sides 35 and 36. Along the third direction Z, the distance L3 by which the third side 35 extends beyond the first tab group 21 satisfies the following conditions: 0.5 mm ≤ L3 ≤ 10 mm; and / or, along the third direction Z, the distance L4 by which the fourth side 36 extends beyond the first tab group 21 satisfies the following conditions: 0.5 mm ≤ L4 ≤ 10 mm. In the third direction Z, the third side 35 and / or the fourth side 36 extend beyond the first tab group 21 by a certain distance, so that after the first transfer plate 30 is welded to the first and second tab groups 21 and 22, it can also be welded to external conductive sheets, adapter sheets, or poles in the third direction Z, thereby reducing the space occupied along the first direction X. When distances L3 and L4 are less than 0.5 mm, it is difficult to achieve a welded connection between the first transfer plate 30 and external components. Even if a welded connection is possible, setting the protrusion of the first transfer plate 30 too long will increase the overall weight of the electrode assembly 100 and occupy space within the electrochemical device. Excessively long distances L3 and L4 may even hinder the installation of the second tab unit 40 connected to the first end 10a of the battery cell body 10. Therefore, setting distances L3 and L4 to less than or equal to 10 mm is sufficient. Furthermore, to reduce the difficulty and process requirements of welding the first transfer plate 30 to external components while preventing the first transfer plate 30 from extending excessively beyond the first tab group 21, as some examples, distances L3 and / or L4 may satisfy the following conditions: 3 mm ≤ L3 ≤ 6 mm, and / or 3 mm ≤ L4 ≤ 6 mm.

[0050] In some embodiments, referring to FIGS. 3 and 4, the first transfer welding plate 30 includes a metal plate 37 and an insulating layer 38 stacked along the first direction X. The insulating layer 38 is close to the first end 10a of the battery cell body 10, and the insulating layer 38 abuts against the first tab group 21 and the second tab group 22 respectively. Since the first electrode tab 13 and the second electrode tab 14 in the battery cell body 10 are alternately arranged and have opposite polarities, that is, both the first electrode tab 13 and the second electrode tab 14 exist in the first end 10a of the battery cell body 10. In order to prevent the metal plate 37 from contacting the end of the second electrode tab 14 to form a short circuit, an insulating layer 38 needs to be provided between the metal plate 37 and the first end 10a of the battery cell body 10, so that the metal plate 37 forms an electrical connection with the first tab group 21 and the second tab group 22.

[0051] In some embodiments, the sum of the thicknesses of the first transfer welding plate 30 and the insulating layer 38 is G, the thickness of the first tab unit 20 is g, the number of tabs in the first tab group 21 is n1, and the number of tabs in the second tab group is n2, where n1 ≤ n2, and G satisfies: 0.1 mm ≤ G ≤ n1 * g. In this way, the sum of the thicknesses of the first transfer welding plate and the insulating layer can be controlled within a suitable range, and the thicknesses of the first tab group, the second tab group, and the insulating plate in the first direction X of the battery cell 10 can be reduced.

[0052] Specifically, taking the thickness of the first tab unit 20 as g, in the prior art solution where all the first tab units 20 are concentrated in the same area and bent before welding, the thickness of the first tab unit 20 after bending is denoted as m, and m is (n1 + n2)g; in the embodiment of the present application, the thickness of the first tab unit 20 of the first tab group 21 after the first bending is n1 * g, and the thickness of the first tab unit 20 of the second tab group 22 after the first bending is n2 * g. Since the first tab units 20 of the first tab group 21 are separated, the second thickness m2 of the tab structure after the first bending in the present application is the larger value of n1 * g and n2 * g. If n1 < n2, then the thickness m2 of the tab structure in the present application is n2 * g. It can be seen that compared with the solution where all the tabs are concentrated in the same area and bent before welding, the thickness reduction of the tab structure in the solution of the present application is W, and W = (n1 + n2)g - n2 * g = n1 * g.

[0053] In the present application, by limiting the transfer welding plate 30 and the insulating layer 38 to G ≤ n1 * g, it is possible to improve the energy density compared with the prior art. Therefore, in the present application, the multiple first tab units 20 of the tab structure are divided into the first tab group 21 and the second tab group 22, which can not only reduce the size of the tab structure by reducing the bending stress, but also reduce the head space from the stacked thickness of multiple tabs 210, truly optimizing the tab structure to improve the energy density of the battery when the battery cell 10 is applied to the battery.

[0054] As some examples, the material of the metal plate 37 is mainly aluminum, copper, nickel, titanium, copper-nickel alloy, aluminum-copper alloy, stainless steel, etc. The material of the insulating layer 38 is an electrolyte-resistant polymer adhesive, such as PP (polypropylene), PE (polyethylene), butyl rubber, acrylic adhesive, modified polyolefin, SIS rubber (thermoplastic styrene-butadiene rubber), acrylic adhesive, etc.

[0055] In some embodiments, referring to FIG5 , to ensure the insulating effect of insulating layer 38 and prevent the metal plate 37 from directly contacting the second electrode sheet 14 and causing a short circuit when the electrochemical device is subjected to vibration or mechanical impact during testing or use, the projection of metal plate 37 is located within the projection of insulating layer 38 in the first direction X. That is, along the second direction Y, the size of insulating layer 38 is larger than that of the metal layer. And / or, referring to FIG2 , along the third direction Z, the size of insulating layer 38 is larger than that of metal plate 37.

[0056] The insulating layer 38, which has both insulating and thermal insulation functions, can be a single-layer structure or a composite layer structure. In some embodiments, referring to Figures 3 and 6, the insulating layer 38 includes a first adhesive layer 381, a thermal insulation layer 382, ​​and a second adhesive layer 383. Along the first direction X, the first adhesive layer 381 bonds the metal plate 37 and the thermal insulation layer 382, ​​respectively, and the second adhesive layer 383 bonds the thermal insulation layer 382 to the first and second tab groups 21 and 22, respectively. In this embodiment, the insulating layer 38 adopts a composite structure of the thermal insulation layer 382 and the adhesive layer. This allows the insulating layer 38 to not only meet the insulation and bonding requirements but also provide thermal insulation. This prevents the high temperature of the laser welding of the first and second tab groups 21 and 22 to the metal plate 37 in the first transfer plate 30 from causing high-temperature failure of the first and / or second tabs 13 and 14, or from causing the diaphragm 15 to shrink at high temperature, resulting in a direct contact short circuit between the first and second tabs 13 and 14. The heat insulating layer 382 reduces the transfer of welding temperature, thereby ensuring the safety of the battery cell body 10 .

[0057] In some embodiments, referring to Figures 1 and 2, the electrode assembly 100 further includes a second transfer plate 50. Along a first direction X, the second transfer plate 50 has opposing third and fourth surfaces. The third surface faces the cell body 10 and is insulated and abutted against the second tab unit 40, while the fourth surface faces away from the cell body 10. Some of the second tab units 40 are gathered to form a third tab group 41, while the remaining second tab units 40 are gathered to form a fourth tab group 42. The third tab group 41 is bent to abut against the fourth surface of the second transfer plate 50. The fourth tab group 42 is bent to overlap with the third tab group 41 and are welded to form an electrical connection. It is worth noting that several second tab units 40 can be connected to the first end 10a or the second end 10b of the cell body 10, so that the electrode assembly 100 has tabs extending from the same end or from both ends.

[0058] The structural arrangement and function of the second transfer plate 50 and the third and fourth tab groups 41 and 42 in this application are roughly the same as the structural arrangement and function of the first transfer plate 30 and the first and second tab groups 21 and 22. For details, please refer to the above embodiments and will not be repeated here.

[0059] The present application also provides an embodiment of an electrochemical device, which includes a housing, a positive terminal, a negative terminal, and the electrode assembly 100 of the above embodiment. The housing is provided with a receiving cavity, and the electrode assembly 100 is received in the receiving cavity. The positive terminal is electrically connected to the first transfer plate 30 and extends outside the housing. The negative terminal is electrically connected to the second tab unit 40 or to the second transfer plate 50 and extends outside the housing. The receiving cavity is filled with an electrolyte for the electrode assembly 100 to generate an electrochemical reaction. By providing the structure of the first transfer plate 30, the connection thickness between the positive terminal and the first tab unit 20 in the first direction X can be reduced, thereby reducing the excess space of the receiving cavity occupied by the end of the electrode assembly 100 and improving the energy density of the electrochemical device. The structure and function of the electrode assembly 100 can be referred to the above embodiment and will not be repeated here.

[0060] The electrode assembly 100 of the present application includes a battery cell body 10, a plurality of first tab units 20, and a first transfer plate 30. The plurality of first tab units 20 are all connected to the first end 10a of the battery cell body 10, wherein some of the first tab units 20 are gathered to form a first tab group 21, and the remaining first tab units 20 are gathered to form a second tab group 22; along the first direction X, the first transfer plate 30 has a first surface 31 and a second surface 32 opposite to each other, the first surface 31 facing the battery cell body 10 and insulated from and abutting the first tab units 20, the second surface 32 facing away from the battery cell body 10, the first tab group 21 being bent and abutting the second surface 32, and the second tab group 22 being bent and overlapping with the first tab group 21 and electrically connected. Through the above-mentioned structural setting, the first pole ear unit 20 and external conductive sheets, adapter sheets or poles and other components can be welded on the same surface of the first transfer plate 30 in the third direction Z, that is, the first pole ear group 21 and the second pole ear group 22 can be staggered with external components in the third direction Z, effectively reducing the space occupied in the first direction X, reducing the volume of the electrode assembly 100, and helping to improve the energy density of the electrochemical device.

[0061] In some embodiments, along the first direction X, the first tab group 21 and the second tab group 22 do not overlap on the second surface 32 after being bent. The two tab groups do not overlap on the second surface 32 after being bent, which can further reduce head space.

[0062] In some embodiments, the bent portions of the first tab group 21 and the second tab group 22 are arranged along a second direction Y on the second surface 32, where the second direction is perpendicular to the first direction X. That is, the bent portions can be arranged along the second direction Y or along a third direction Z. When arranged along the second direction Y, only the bent portions of the first tab group 21 and the second tab group 22 need to be cut so that the two tab groups are staggered. This prevents the two tab groups from overlapping after bending, further improving space utilization in the first direction X.

[0063] In addition, they can also be arranged in the third direction Z, that is, the positions where the two tab groups extend are arranged along the third direction, and after being bent, they are arranged along the third direction Z on the first transfer plate 30 .

[0064] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An electrode assembly, characterized in that, Comprising: a battery cell body and a plurality of first tab units, the plurality of first tab units are all connected to a first end of the battery cell body, wherein, some of the first tab units are gathered to form a first tab group, and the remaining first tab units are gathered to form a second tab group; the electrode assembly further includes a first transfer welding plate, along a first direction, the first transfer welding plate has an opposite first surface and a second surface, the first surface faces the battery cell body and is in insulating contact with the first tab unit, the second surface faces away from the battery cell body, the first tab group is bent and abuts against the second surface, and the second tab group is bent and extends to one side of the second surface and is electrically connected to the first transfer welding plate.

2. The electrode assembly according to claim 1, wherein along the first direction, at least a part of the first tab group and the second tab group overlap after being bent.

3. The electrode assembly according to claim 1, wherein the number N1 of the first tab units in the first tab group and the number N2 of the first tab units in the second tab group satisfy: 0.2 ≤ N1 / N2 ≤ 1.

4. The electrode assembly according to claim 3, wherein 0.8 ≤ N1 / N2 ≤ 1.

5. The electrode assembly according to claim 2, wherein along a second direction, the first transfer welding plate has an opposite first side surface and a second side surface, the first side surface is close to the bending position of the first tab group, the second side surface is close to the bending position of the second tab group, wherein the second direction is perpendicular to the first direction; the first tab group has an opposite first end and a second end, the first end of the first tab group is connected to the battery cell body, along the second direction, the distance L1 between the second end of the first tab group after being bent and the second side surface of the first transfer welding plate satisfies: 0mm ≤ L1 ≤ K / 2, wherein, K is the distance between the first side surface and the second side surface of the first transfer welding plate in the second direction.

6. The electrode assembly according to claim 5, wherein along the second direction, the battery cell body has an opposite first main surface and a second main surface, the first main surface is close to the first side surface of the first transfer welding plate, the second main surface is close to the second side surface of the first transfer welding plate; the second tab group has an opposite first end and a second end, the first end of the second tab group is connected to the battery cell body, along the second direction, the distance L2 between the second end of the second tab group after being bent and the first main surface satisfies: 0mm ≤ L2 ≤ K / 2.

7. The electrode assembly according to claim 6, wherein 0.3mm ≤ L1 ≤ 1.5mm; and / or, 0.1mm ≤ L2 ≤ 1.5mm.

8. The electrode assembly according to claim 5, wherein along a third direction, the first transfer welding plate has an opposite third side surface and a fourth side surface, wherein the first direction, the second direction and the third direction are perpendicular to each other in pairs; along the third direction, the distance L3 that the third side surface exceeds the first tab group satisfies: 0.5mm ≤ L3 ≤ 10mm; and / or, Along the third direction, the distance L4 by which the fourth side surface extends beyond the first tab group satisfies: 0.5 mm ≤ L4 ≤ 10 mm.

9. The electrode assembly according to claim 8, wherein 3 mm ≤ L3 ≤ 6 mm, and / or, 3 mm ≤ L4 ≤ 6 mm.

10. The electrode assembly according to claim 1, wherein the first transfer welding plate includes a metal plate and an insulating layer stacked along the first direction, the insulating layer is close to the battery cell body, and the insulating layer is in contact with the first tab group and the second tab group respectively.

11. The electrode assembly according to claim 10, wherein along the first direction, the projection of the metal plate is located within the projection of the insulating layer.

12. The electrode assembly according to claim 10, wherein along the second direction, the size of the insulating layer is larger than the size of the metal layer; and / or, along the third direction, the size of the insulating layer is larger than the size of the metal layer, and the first direction, the second direction and the third direction are perpendicular to each other in pairs.

13. The electrode assembly according to claim 10, wherein the insulating layer includes a first adhesive layer, a heat insulating layer and a second adhesive layer. Along the first direction, the first adhesive layer adhesively connects the metal plate and the heat insulating layer respectively, and the second adhesive layer adhesively connects the heat insulating layer and the first tab group and the second tab group respectively.

14. The electrode assembly according to claim 13, wherein the sum of the thicknesses of the first transfer welding plate and the insulating layer is G, the thickness of the first tab unit is g, the number of tabs in the first tab group is n1, and the number of tabs in the second tab group is n2, where n1 ≤ n2, and G satisfies: 0.1 mm ≤ G ≤ n1 * g.

15. The electrode assembly according to any one of claims 1, 3, 4, 10, wherein along the first direction, after being bent, the first tab group and the second tab group do not overlap on the second surface.

16. The electrode assembly according to claim 15, wherein the bent portions of the first tab group and the second tab group are arranged along the second direction on the second surface, and the second direction is perpendicular to the first direction.

17. The electrode assembly according to claim 1, wherein the electrode assembly further includes a plurality of second tab units, and all of the plurality of second tab units are connected to the first end of the battery cell body or all are connected to the second end of the battery cell body. Among them, some of the second tab units are gathered to form a third tab group, and the remaining second tab units are gathered to form a fourth tab group. The first end and the second end of the battery cell body are oppositely arranged in the first direction; the electrode assembly further includes a second transfer welding plate. Along the first direction, the second transfer welding plate has an opposite third surface and a fourth surface. The third surface faces the battery cell body and is in insulating contact with the second tab unit, and the fourth surface faces away from the battery cell body. After being bent, the third tab group is in contact with the fourth surface, and the fourth tab group is electrically connected to the third tab group after being bent.

18. An electrochemical device, characterized in that, Including the electrode assembly according to any one of claims 1-14, the electrochemical device further includes a terminal post, the terminal post is welded to the transfer welding plate, and along the first direction, the projection of the terminal post does not coincide with the first tab group. And / or, along the first direction, the projection of the terminal post does not coincide with the second tab group.

Images