Electrode assembly, battery cell and electric equipment

Abstract

The invention provides an electrode assembly, a battery cell and electric equipment, the electrode assembly comprises a first pole piece, a first tab, a first bonding member and a second bonding member, the first pole piece comprises a first composite current collector, the first composite current collector comprises a first insulating layer, a first metal layer and a second metal layer, the first metal layer and the second metal layer are arranged on the two sides of the first insulating layer in the thickness direction of the first insulating layer respectively. The first tab comprises a first main body part, a first forked part and a second forked part; the first forked part and the second forked part are connected with the first main body part; the first branch part and the first metal layer are electrically connected through a first bonding piece. And the second branch part and the second metal layer are electrically connected through a second bonding piece. The first tab and the first composite current collector can be stably connected, the electrical connection stability and consistency of the first metal layer and the second metal layer are relatively good, and the performance of the battery cell is favorably improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and more specifically, to an electrode assembly, a battery cell, and an electrical device using the same. Background Art

[0002] With the rapid development of electronic information technology, various electronic devices are also developing towards the direction of intelligence and multi-functionality, and the requirements for the safety and reliability of batteries are getting higher and higher. Setting a composite current collector in the electrode assembly can reduce the weight of the battery cell and improve the safety of the battery cell. The composite current collector includes an insulating layer and two metal layers on both sides of the insulating layer. Problems such as poor electrical connection stability are likely to occur when the two metal layers are electrically connected by welding or riveting. Summary of the Invention

[0003] The present application provides an electrode assembly, a battery cell, and an electrical device using the same, which can improve the internal electrical connection stability of the electrode assembly.

[0004] In a first aspect, the present application provides an electrode assembly, which includes a first electrode tab, a first tab ear, a first bonding member, and a second bonding member. The first electrode tab includes a first composite current collector, and the first composite current collector includes a first insulating layer, a first metal layer, and a second metal layer. The first metal layer and the second metal layer are respectively disposed on both sides of the first insulating layer along its thickness direction. The first tab ear includes a first main body portion, a first bifurcated portion, and a second bifurcated portion. The first bifurcated portion and the second bifurcated portion are both connected to the first main body portion. The first bifurcated portion is electrically connected to the first metal layer and is connected through the first bonding member. The second bifurcated portion is electrically connected to the second metal layer and is connected through the second bonding member.

[0005] In the above technical solution, by making the first electrode tab include a first composite current collector, the first composite current collector includes a first insulating layer, a first metal layer, and a second metal layer, and the first metal layer and the second metal layer are respectively disposed on both sides of the first insulating layer along its thickness direction, the weight of the first electrode tab can be reduced, and the first metal layer and the second metal layer are relatively thin, so that fewer burrs are generated during the mechanical damage process of the battery cell, which is beneficial to reducing the possibility of short circuit of the electrode assembly and improving the safety of the electrode assembly. By making the first tab ear include a first main body portion, a first bifurcated portion, and a second bifurcated portion, the first bifurcated portion and the second bifurcated portion are both connected to the first main body portion, the first bifurcated portion is electrically connected to the first metal layer and is connected through the first bonding member, and the second bifurcated portion is electrically connected to the second metal layer and is connected through the second bonding member, the first metal layer and the second metal layer can be electrically connected through the first tab ear, and the first bonding member and the second bonding member can make the connection between the first tab ear and the first composite current collector firm, and the electrical connection stability and consistency between the first metal layer and the second metal layer are good, which is beneficial to improving the performance of the battery cell. Setting the first tab ear to a bifurcated structure can facilitate the conduction between the first metal layer and the second metal layer.

[0006] In some embodiments of the present application, the first bifurcated portion is in contact with the first metal layer; and / or, the second bifurcated portion is in contact with the second metal layer.

[0007] In the above technical solution, by making the first bifurcated portion in contact with the first metal layer, the electrical connection between the first tab and the first metal layer can be achieved. By making the second bifurcated portion in contact with the second metal layer, the electrical connection between the first tab and the second metal layer can be achieved.

[0008] In some embodiments of the present application, a first protrusion is provided on the surface of the first bifurcated portion facing the first metal layer, and the first protrusion is in contact with the first metal layer; and / or, a second protrusion is provided on the surface of the second bifurcated portion facing the second metal layer, and the second protrusion is in contact with the second metal layer.

[0009] In the above technical solution, by providing a first protrusion on the surface of the first bifurcated portion facing the first metal layer and the first protrusion being in contact with the first metal layer, it is convenient for the first tab to achieve electrical connection with the first metal layer through the first protrusion, which is beneficial to improving the electrical connection reliability between the first tab and the first metal layer. By providing a second protrusion on the surface of the second bifurcated portion facing the second metal layer and the second protrusion being in contact with the second metal layer, it is convenient for the first tab to achieve electrical connection with the second metal layer through the second protrusion, which is beneficial to improving the electrical connection reliability between the first tab and the second metal layer.

[0010] In some embodiments of the present application, the first protrusion extends linearly or curvilinearly within the surface of the first bifurcated portion facing the first metal layer, the number of the first protrusions is multiple, and the multiple first protrusions cross to form a network structure; and / or, the second protrusion extends linearly or curvilinearly within the surface of the second bifurcated portion facing the second metal layer, the number of the second protrusions is multiple, and the multiple second protrusions cross to form a network structure.

[0011] In the above technical solution, by making the first protrusion extend linearly or curvilinearly within the surface of the first bifurcated portion facing the first metal layer, the number of the first protrusions is multiple, and the multiple first protrusions cross to form a network structure, the area of the first protrusion can be made larger and the distribution range can be made wider, so that the contact area between the first tab and the first metal layer is larger and the electrical connection reliability between the first tab and the first metal layer is higher. By making the second protrusion extend linearly or curvilinearly within the surface of the second bifurcated portion facing the second metal layer, the number of the second protrusions is multiple, and the multiple second protrusions cross to form a network structure, the area of the second protrusion can be made larger and the distribution range can be made wider, so that the contact area between the first tab and the second metal layer is larger and the electrical connection reliability between the first tab and the second metal layer is higher.

[0012] In some embodiments of the present application, a first groove is provided on the surface of the first bifurcated portion facing the first metal layer, and at least a portion of the first bonding member is received in the first groove; and / or, a second groove is provided on the surface of the second bifurcated portion facing the second metal layer, and at least a portion of the second bonding member is received in the second groove.

[0013] In the above technical solution, by providing a first groove on the surface of the first bifurcated portion facing the first metal layer and receiving at least a portion of the first bonding member in the first groove, the space occupied by the first bonding member in the thickness direction of the first composite current collector can be made smaller or no additional space is occupied, so that the overall thickness of the first tab, the first bonding member, and the first composite current collector is smaller, which is beneficial to reducing the thickness of the electrode assembly and making the energy density of the battery cell provided with this electrode assembly higher. By providing a second groove on the surface of the second bifurcated portion facing the second metal layer and receiving at least a portion of the second bonding member in the second groove, the space occupied by the second bonding member in the thickness direction of the first composite current collector can be made smaller or no additional space is occupied, so that the overall thickness of the first tab, the second bonding member, and the first composite current collector is smaller, which is beneficial to reducing the thickness of the electrode assembly and making the energy density of the battery cell provided with this electrode assembly higher.

[0014] In some embodiments of the present application, the first groove extends linearly or curvilinearly on the surface of the first bifurcated portion facing the first metal layer, the number of the first grooves is multiple, and the groove walls of the multiple first grooves intersect to form a network structure; and / or, the second groove extends linearly or curvilinearly on the surface of the second bifurcated portion facing the second metal layer, the number of the second grooves is multiple, and the groove walls of the multiple second grooves intersect to form a network structure.

[0015] In the above technical solution, by making the first groove extend linearly or curvilinearly on the surface of the first bifurcated portion facing the first metal layer, the number of the first grooves is multiple, and the groove walls of the multiple first grooves intersect to form a network structure, the area of the first groove can be made larger and the distribution range can be wider, so that the bonding area between the first bonding member and the first tab and the first metal layer is larger, and the connection reliability between the first tab and the first metal layer is higher. By making the second groove extend linearly or curvilinearly on the surface of the second bifurcated portion facing the second metal layer, the number of the second grooves is multiple, and the groove walls of the multiple second grooves intersect to form a network structure, the area of the second groove can be made larger and the distribution range can be wider, so that the bonding area between the second bonding member and the first tab and the first metal layer is larger, and the connection reliability between the first tab and the first metal layer is higher.

[0016] In some embodiments of the present application, a first through hole is provided on the first bifurcated portion, and at least a portion of the first bonding member is received in the first through hole; and / or, a second through hole is provided on the second bifurcated portion, and at least a portion of the second bonding member is received in the second through hole.

[0017] In the above technical solution, by providing a first through hole on the first bifurcated portion, at least a part of the first bonding member is accommodated in the first through hole, which can make the space occupied by the first bonding member in the thickness direction of the first composite current collector smaller or not occupy extra space, so that the overall thickness of the first tab, the first bonding member and the first composite current collector is smaller, which is beneficial to reducing the thickness of the electrode assembly, making the energy density of the battery cell provided with this electrode assembly higher, and the preparation process of the first through hole is simple. By providing a second through hole on the second bifurcated portion, at least a part of the second bonding member is accommodated in the second through hole, which can make the space occupied by the second bonding member in the thickness direction of the first composite current collector smaller or not occupy extra space, so that the overall thickness of the first tab, the second bonding member and the first composite current collector is smaller, which is beneficial to reducing the thickness of the electrode assembly, making the energy density of the battery cell provided with this electrode assembly higher, and the preparation process of the second through hole is simple.

[0018] In some embodiments of the present application, a plurality of first through holes are provided on the first bifurcated portion, and the plurality of first through holes are arranged in an array; and / or, a plurality of second through holes are provided on the second bifurcated portion, and the plurality of second through holes are arranged in an array.

[0019] In the above technical solution, by providing a plurality of first through holes on the first bifurcated portion, and the plurality of first through holes are arranged in an array, the area of the first through holes can be made larger and evenly distributed, the bonding area between the first bonding member and the first tab and the first metal layer is larger, and the connection reliability between the first tab and the first metal layer is higher. By providing a plurality of second through holes on the second bifurcated portion, and the plurality of second through holes are arranged in an array, the area of the second through holes can be made larger and evenly distributed, the bonding area between the second bonding member and the first tab and the first metal layer is larger, and the connection reliability between the first tab and the first metal layer is higher.

[0020] In some embodiments of the present application, the first main body portion, the first bifurcated portion and the second bifurcated portion are integrally formed.

[0021] In the above technical solution, by integrally forming the first main body portion, the first bifurcated portion and the second bifurcated portion, the structural stability of the first tab can be made higher, which is beneficial to improving the connection stability between the first metal layer and the second metal layer.

[0022] In some embodiments of the present application, the first bifurcated portion and the second bifurcated portion are connected to the same end of the first main body portion. Along the thickness direction of the first composite current collector, the projections of the first bifurcated portion and the second bifurcated portion do not overlap, so that the overall thickness of the first bifurcated portion, the first bonding member, the second bifurcated portion, the second bonding member and the first composite current collector is smaller, which is beneficial to reducing the thickness of the electrode assembly and improving the volumetric energy density of the battery cell.

[0023] In the above technical solution, by connecting the first bifurcated portion and the second bifurcated portion to the same end of the first main body portion, it is convenient for the first bifurcated portion and the second bifurcated portion to be connected to the first metal layer and the second metal layer respectively. By making the projections of the first bifurcated portion and the second bifurcated portion not overlap along the thickness direction of the first composite current collector, it is convenient for the preparation of the first bifurcated portion and the second bifurcated portion.

[0024] In some embodiments of the present application, along the width direction of the first composite current collector, the spacing distance D1 between the first bifurcated portion and the second bifurcated portion satisfies 0.5 mm ≤ D1 ≤ 3 mm.

[0025] In the above technical solution, when D1 is greater than or equal to 0.5 mm, it is convenient for the preparation of the first tab and for the first bifurcated portion to be connected to the first metal layer through the first adhesive, and for the second bifurcated portion to be connected to the second metal layer through the second adhesive; when D1 is less than or equal to 3 mm, the size of the first tab in the width direction of the first composite current collector can be reduced, the space occupied by the first tab can be reduced, which is beneficial to improving the energy density of the battery cell; therefore, when 0.5 mm ≤ D1 ≤ 3 mm, it is not only convenient for the preparation and assembly of the first tab, but also can reduce the space occupied by the first tab, which is beneficial to making the battery cell provided with this electrode assembly have a higher energy density.

[0026] In some embodiments of the present application, the first bifurcated portion and the second bifurcated portion are connected to the same end of the first main body portion, and along the thickness direction of the first composite current collector, the projections of the first bifurcated portion and the second bifurcated portion at least partially overlap.

[0027] In the above technical solution, by connecting the first bifurcated portion and the second bifurcated portion to the same end of the first main body portion, and by making the projections of the first bifurcated portion and the second bifurcated portion at least partially overlap along the thickness direction of the first composite current collector, it is convenient for the first bifurcated portion and the second bifurcated portion to be connected to the first metal layer and the second metal layer respectively.

[0028] In some embodiments of the present application, on one side along the length direction of the first composite current collector, the first metal layer is provided with a first receiving groove, and at least a part of the first bifurcated portion is disposed in the first receiving groove.

[0029] In the above technical solution, by making at least a part of the first bifurcated portion disposed in the first receiving groove, the overall thickness of the first electrode tab and the first tab can be reduced, which is beneficial to reducing the thickness of the electrode assembly and making the battery cell provided with this electrode assembly have a higher energy density.

[0030] In some embodiments of the present application, along the length direction of the first composite current collector, the spacing distance between the first bifurcated portion and the first side wall of the first accommodating groove is D2, satisfying 0.5 mm ≤ D2 ≤ 5 mm. Along the width direction of the first composite current collector, the spacing distance between the first bifurcated portion and the first side wall of the first accommodating groove is D3, satisfying 0.5 mm ≤ D3 ≤ 5 mm.

[0031] In the above technical solution, when D2 is greater than or equal to 0.5 mm and D3 is greater than or equal to 0.5 mm, it is convenient for the first bifurcated portion to be accommodated in the first accommodating groove; when D2 is less than or equal to 5 mm and D3 is less than or equal to 5 mm, the space occupied by the first accommodating groove can be made smaller, so that the area of the first metal layer is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector; therefore, when 0.5 mm ≤ D2 ≤ 5 mm and 0.5 mm ≤ D3 ≤ 5 mm, it is both convenient for the first bifurcated portion to be accommodated in the first accommodating groove and the area of the first metal layer can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector.

[0032] In some embodiments of the present application, along the width direction of the first composite current collector, the width of the first accommodating groove is W1, satisfying 5 mm ≤ W1 ≤ 7 mm.

[0033] In the above technical solution, when W1 is greater than or equal to 5 mm, it is convenient to accommodate the first bifurcated portion; when W1 is less than or equal to 7 mm, the space occupied by the first accommodating groove can be made smaller, so that the area of the first metal layer is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector; therefore, when 5 mm ≤ W1 ≤ 7 mm, it is both convenient to accommodate the first bifurcated portion and the area of the first metal layer can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector.

[0034] In some embodiments of the present application, on one side along the length direction of the first composite current collector, the second metal layer is provided with a second accommodating groove, and at least a part of the second bifurcated portion is arranged in the second accommodating groove.

[0035] In the above technical solution, by arranging at least a part of the second bifurcated portion in the second accommodating groove, the overall thickness of the first pole piece and the first pole ear can be reduced, which is beneficial to reducing the thickness of the electrode assembly and making the energy density of the battery cell provided with this electrode assembly higher.

[0036] In some embodiments of the present application, along the length direction of the first composite current collector, the spacing distance between the second bifurcated portion and the second side wall of the second accommodating groove is D4, satisfying 0.5 mm ≤ D4 ≤ 5 mm. Along the width direction of the first composite current collector, the spacing distance between the second bifurcated portion and the second side wall of the second accommodating groove is D5, satisfying 0.5 mm ≤ D5 ≤ 5 mm.

[0037] In the above technical solution, when D4 is greater than or equal to 0.5 mm and D5 is greater than or equal to 0.5 mm, it is convenient for the second bifurcated portion to be placed in the second accommodating groove; when D4 is less than or equal to 5 mm and D5 is less than or equal to 5 mm, the space occupied by the second accommodating groove can be made smaller, so that the area of the second metal layer is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector; therefore, when 0.5 mm ≤ D4 ≤ 5 mm and 0.5 mm ≤ D5 ≤ 5 mm, it is both convenient for the second bifurcated portion to be placed in the second accommodating groove and the area of the second metal layer can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector.

[0038] In some embodiments of the present application, along the width direction of the first composite current collector, the width of the second accommodating groove is W2, satisfying 5 mm ≤ W2 ≤ 7 mm.

[0039] In the above technical solution, when W2 is greater than or equal to 5 mm, it is convenient to accommodate the second bifurcated portion; when W2 is less than or equal to 7 mm, the space occupied by the second accommodating groove can be made smaller, so that the area of the second metal layer is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector; therefore, when 5 mm ≤ W1 ≤ 7 mm, it is both convenient to accommodate the second bifurcated portion and the area of the second metal layer can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector.

[0040] In some embodiments of the present application, along the thickness direction of the first composite current collector, the first accommodating groove and the second accommodating groove partially overlap or do not overlap. The first composite current collector has opposite first and second ends in its width direction. Along the width direction of the first composite current collector, the first accommodating groove has a first sub-sidewall close to the first end, and the second accommodating groove has a second sub-sidewall close to the first end. The distance S1 between the first sub-sidewall and the second sub-sidewall in the width direction of the first composite current collector satisfies 3 mm ≤ S1 ≤ 8 mm.

[0041] In the above technical solution, when S1 is greater than or equal to 3 mm, it is convenient to prepare the first accommodating groove and the second accommodating groove; when S1 is less than or equal to 8 mm, the overall space occupied by the first accommodating groove and the second accommodating groove in the width direction of the first composite current collector can be made smaller, correspondingly making the space occupied by the first tab smaller, which is beneficial to making the energy density of the battery cell provided with this electrode assembly higher and facilitating the arrangement of other components in the width direction of the first composite current collector.

[0042] In some embodiments of the present application, the first adhesive member includes conductive particles; and / or, the second adhesive member includes conductive particles.

[0043] In the above technical solution, by making the first bonding member include conductive particles, the first tab can achieve electrical connection with the first metal layer through the first bonding member, and the electrical connection reliability between the first tab and the first metal layer is higher. By making the second bonding member include conductive particles, the first tab can achieve electrical connection with the second metal layer through the second bonding member, and the electrical connection reliability between the first tab and the second metal layer is higher.

[0044] In some embodiments of the present application, the electrode assembly further includes a second electrode plate, a second tab, a third bonding member, and a fourth bonding member. The second electrode plate has a polarity opposite to that of the first electrode plate. The second electrode plate includes a second composite current collector, and the second composite current collector includes a second insulating layer, a third metal layer, and a fourth metal layer. The third metal layer and the fourth metal layer are respectively disposed on both sides of the second insulating layer along its thickness direction. The second tab includes a second main body portion, a third bifurcated portion, and a fourth bifurcated portion. Both the third bifurcated portion and the fourth bifurcated portion are connected to the second main body portion. The third bifurcated portion is electrically connected to the third metal layer and is connected through the third bonding member. The fourth bifurcated portion is electrically connected to the fourth metal layer and is connected through the fourth bonding member.

[0045] In the above technical solution, by making the second electrode plate include a second composite current collector, and the second composite current collector includes a second insulating layer, a third metal layer, and a fourth metal layer, and the third metal layer and the fourth metal layer are respectively disposed on both sides of the second insulating layer along its thickness direction, the weight of the second electrode plate can be reduced, and the third metal layer and the fourth metal layer are relatively thin, so that fewer burrs are generated during the mechanical damage process of the battery cell, which is beneficial to reducing the possibility of short circuit of the electrode assembly and improving the safety of the electrode assembly. By making the second tab include a second main body portion, a third bifurcated portion, and a fourth bifurcated portion, both the third bifurcated portion and the fourth bifurcated portion are connected to the second main body portion, the third bifurcated portion is electrically connected to the third metal layer and is connected through the third bonding member, and the fourth bifurcated portion is electrically connected to the fourth metal layer and is connected through the fourth bonding member, so that the third metal layer and the fourth metal layer can achieve electrical connection through the second tab, and the third bonding member and the fourth bonding member can make the connection between the second tab and the second composite current collector stable, and the electrical connection stability and consistency between the third metal layer and the fourth metal layer are good, which is beneficial to improving the performance of the battery cell.

[0046] In a second aspect, the present application provides a battery cell, and the battery cell includes the electrode assembly as described above.

[0047] In a third aspect, the present application provides an electrical device, and the electrical device includes the battery cell as described above, and the battery cell is used to provide electrical energy. Description of the Drawings

[0048] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings.

[0049] Figure 1 Schematic perspective view of an electrode assembly provided by some embodiments of the present application;

[0050] Figure 2 Schematic top view of a partial structure of an electrode assembly provided by some embodiments of the present application;

[0051] Figure 3 Schematic side view of a partial structure of an electrode assembly provided by some embodiments of the present application;

[0052] Figure 4 Schematic bottom view of a partial structure of an electrode assembly provided by some embodiments of the present application;

[0053] Figure 5 Schematic bottom view of a partial structure of an electrode assembly provided by some other embodiments of the present application;

[0054] Figure 6 Schematic top view of a partial structure of an electrode assembly provided by some other embodiments of the present application;

[0055] Figure 7 Schematic side view of a partial structure of an electrode assembly provided by some other embodiments of the present application;

[0056] Figure 8 Schematic side view of the first electrode tab of an electrode assembly provided by some other embodiments of the present application;

[0057] Figure 9 Schematic top view of a partial structure of an electrode assembly provided by some other embodiments of the present application;

[0058] Figure 10 Schematic top view of a partial structure of an electrode assembly provided by some other embodiments of the present application;

[0059] Figure 11 Schematic perspective view of a battery cell provided by some embodiments of the present application.

[0060] Icons: 10 - electrode assembly; 100 - first pole piece; 110 - first composite current collector; 111 - first insulating layer; 112 - first metal layer; 113 - second metal layer; 200 - first tab; 210 - first main body portion; 220 - first bifurcated portion; 221 - first protrusion; 222 - first groove; 223 - first through hole; 230 - second bifurcated portion; 310 - first adhesive; 320 - second adhesive; 400 - second pole piece; 410 - second composite current collector; 411 - second insulating layer; 412 - third metal layer; 413 - fourth metal layer; 500 - second tab; 510 - second main body portion; 520 - third bifurcated portion; 530 - fourth bifurcated portion; 610 - third adhesive; 620 - fourth adhesive; 20 - housing; X - first direction; Y - second direction; Z - third direction. Detailed implementation manners

[0061] To make the objectives, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some but not all of the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art fall within the scope of protection of this application.

[0062] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the description of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0063] The terms "first", "second", etc. in the description and claims of this application or the above drawings are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0064] Referring to "embodiments" in this application means that specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various positions in the description and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0065] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, the detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components shown in the drawings in the embodiments of this application, as well as the overall thickness, length, width and other dimensions of the integrated device are only for illustrative purposes and should not constitute any limitation to this application.

[0066] With the development of the new energy industry, batteries are gradually evolving towards higher energy density and higher power density, and the requirements for the safety and reliability of batteries are also increasing. The composite current collector is composed of an insulating layer and two metal layers located on both sides of the insulating layer. Since the mass of the insulating layer per unit volume is generally less than that of the metal layer, setting a composite current collector in the electrode assembly can reduce the weight of the electrode assembly. Compared with a single-layer metal current collector, the metal layers in the composite current collector are thinner, which can reduce the burrs during the mechanical damage of the battery cell and lower the possibility of short circuit between the positive electrode plate and the negative electrode plate, thereby improving the safety of the battery cell.

[0067] However, currently, the two metal layers of the composite current collector are generally electrically connected by welding or riveting. When connecting the two metal layers of the composite current collector by welding methods such as ultrasonic welding and laser welding, problems such as poor welding or over-welding are likely to occur. Poor welding will result in low welding strength and unstable electrical connection between the two metal layers; over-welding may penetrate the metal layer, reducing the connection area between the two metal layers, which will also cause unstable electrical connection between the two metal layers. When connecting the two metal layers of the composite current collector by riveting, the main body of the rivet is connected to one of the metal layers with a large connection area, while the end only contacts the other metal layer through several rivet points with a small connection area, resulting in poor electrical connection stability at the end and poor electrical connection consistency with the two metal layers, affecting the performance of the battery cell. Moreover, the thickness at the riveting part of the composite current collector is relatively large, which may exceed the active material layer of the electrode plate, leading to an increase in the thickness of the electrode assembly and affecting the energy density of the battery cell.

[0068] In order to improve the internal electrical connection stability of the electrode assembly, the present application provides an electrode assembly, which includes a first electrode plate, a first tab, a first bonding member, and a second bonding member. The first electrode plate includes a first composite current collector, and the first composite current collector includes a first insulating layer, a first metal layer, and a second metal layer. The first metal layer and the second metal layer are respectively arranged on both sides of the first insulating layer along its thickness direction. The first tab includes a first main body part, a first bifurcated part, and a second bifurcated part. The first bifurcated part and the second bifurcated part are both connected to the first main body part. The first bifurcated part is electrically connected to the first metal layer and connected through the first bonding member. The second bifurcated part is electrically connected to the second metal layer and connected through the second bonding member.

[0069] In the electrode assembly with such a structure, by making the first electrode tab include a first composite current collector, the first composite current collector includes a first insulating layer, a first metal layer and a second metal layer, and the first metal layer and the second metal layer are respectively arranged on both sides of the first insulating layer along its thickness direction, the weight of the first electrode tab can be reduced, and the first metal layer and the second metal layer are relatively thin, and there are fewer burrs generated during the mechanical damage process of the battery cell, which is beneficial to reducing the possibility of short circuit of the electrode assembly and improving the safety of the electrode assembly. By making the first electrode ear include a first main body portion, a first bifurcated portion and a second bifurcated portion, both the first bifurcated portion and the second bifurcated portion are connected to the first main body portion, the first bifurcated portion is electrically connected to the first metal layer and connected through a first bonding member, and the second bifurcated portion is electrically connected to the second metal layer and connected through a second bonding member, so that the first metal layer and the second metal layer can be electrically connected through the first electrode ear, and the first bonding member and the second bonding member can make the connection between the first electrode ear and the first composite current collector stable, and the electrical connection stability and consistency between the first metal layer and the second metal layer are good, which is beneficial to improving the performance of the battery cell. Setting the first electrode ear to a bifurcated structure can facilitate the conduction between the first metal layer and the second metal layer.

[0070] The battery cell provided by the embodiment of the present application can be a secondary battery or a primary battery, for example, it can be a lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, etc., and the embodiment of the present application does not limit this. The battery cell can be in a cylindrical shape, a flat shape, a cuboid shape or other shapes, etc., and the embodiment of the present application also does not limit this.

[0071] The embodiment of the present application provides an electrical device using a battery cell as a power source. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc.

[0072] See Figures 1 to 3 , Figure 1 is a schematic perspective view of an electrode assembly provided by some embodiments of the present application; Figure 2 is a schematic top view of a partial structure of an electrode assembly provided by some embodiments of the present application; Figure 3 is a schematic side view of a partial structure of an electrode assembly provided by some embodiments of the present application.

[0073] An embodiment of the present application provides an electrode assembly 10. The electrode assembly 10 includes a first electrode tab 100, a first tab 200, a first adhesive member 310, and a second adhesive member 320. The first electrode tab 100 includes a first composite current collector 110. The first composite current collector 110 includes a first insulating layer 111, a first metal layer 112, and a second metal layer 113. The first metal layer 112 and the second metal layer 113 are respectively disposed on both sides of the first insulating layer 111 along its thickness direction (the first direction X). The first tab 200 includes a first main body portion 210, a first bifurcated portion 220, and a second bifurcated portion 230. Both the first bifurcated portion 220 and the second bifurcated portion 230 are connected to the first main body portion 210. The first bifurcated portion 220 is electrically connected to the first metal layer 112 and is connected through the first adhesive member 310. The second bifurcated portion 230 is electrically connected to the second metal layer 113 and is connected through the second adhesive member 320.

[0074] By making the first electrode tab 100 include the first composite current collector 110, the first composite current collector 110 includes the first insulating layer 111, the first metal layer 112, and the second metal layer 113, and the first metal layer 112 and the second metal layer 113 are respectively disposed on both sides of the first insulating layer 111 along its thickness direction, the weight of the first electrode tab 100 can be reduced, and the first metal layer 112 and the second metal layer 113 are relatively thin, and fewer burrs are generated during the mechanical damage process of the battery cell, which is beneficial to reducing the possibility of short circuit of the electrode assembly 10 and improving the safety of the electrode assembly 10. By making the first tab 200 include the first main body portion 210, the first bifurcated portion 220, and the second bifurcated portion 230, both the first bifurcated portion 220 and the second bifurcated portion 230 are connected to the first main body portion 210, the first bifurcated portion 220 is electrically connected to the first metal layer 112 and is connected through the first adhesive member 310, and the second bifurcated portion 230 is electrically connected to the second metal layer 113 and is connected through the second adhesive member 320, the first metal layer 112 and the second metal layer 113 can be electrically connected through the first tab 200, and the first adhesive member 310 and the second adhesive member 320 can make the connection between the first tab 200 and the first composite current collector 110 firm, and the electrical connection stability and consistency between the first metal layer 112 and the second metal layer 113 are good, which is beneficial to improving the performance of the battery cell. Setting the first tab 200 to a bifurcated structure can facilitate the conduction between the first metal layer 112 and the second metal layer 113.

[0075] In some embodiments, the first insulating layer 111 can be made of a polymer material, such as plastic, rubber, etc. It can make the insulating effect of the first insulating layer 111 better and the support for the first metal layer 112 and the second metal layer 113 better.

[0076] In some embodiments, the first metal layer 112 and the second metal layer 113 can be made of aluminum, copper, etc., which can make the first metal layer 112 and the second metal layer 113 have better electrical conductivity.

[0077] In some embodiments, the first tab 200 can be made of materials such as aluminum, copper or nickel, which can make the first tab 200 have better electrical conductivity.

[0078] In some embodiments, the first adhesive member 310 and the second adhesive member 320 can include at least one of epoxy resin, polyolefin, polystyrene, polymethyl methacrylate, phenolic resin or styrene-butadiene rubber. This can make the adhesion of the first adhesive member 310 and the second adhesive member 320 stronger, so that the first tab 200 is firmly connected to the first electrode tab 100.

[0079] In some embodiments, the first bifurcated portion 220 contacts the first metal layer 112.

[0080] By making the first bifurcated portion 220 contact the first metal layer 112, the electrical connection between the first tab 200 and the first metal layer 112 can be realized.

[0081] In some embodiments, the second bifurcated portion 230 contacts the second metal layer 113.

[0082] By making the second bifurcated portion 230 contact the second metal layer 113, the electrical connection between the first tab 200 and the second metal layer 113 can be realized.

[0083] See Figure 4 , Figure 4 is a bottom view schematic diagram of a partial structure of the electrode assembly provided by some embodiments of the present application.

[0084] In some embodiments, a first protrusion 221 is provided on the surface of the first bifurcated portion 220 facing the first metal layer 112, and the first protrusion 221 contacts the first metal layer 112.

[0085] By making a first protrusion 221 be provided on the surface of the first bifurcated portion 220 facing the first metal layer 112 and the first protrusion 221 contact the first metal layer 112, it is convenient for the first tab 200 to realize electrical connection with the first metal layer 112 through the first protrusion 221, which is beneficial to improving the electrical connection reliability between the first tab 200 and the first metal layer 112.

[0086] In some embodiments, a second protrusion (not shown in the figure) is provided on the surface of the second bifurcated portion 230 facing the second metal layer 113, and the second protrusion contacts the second metal layer 113.

[0087] By arranging a second protrusion on the surface of the second bifurcated portion 230 facing the second metal layer 113, and the second protrusion is in contact with the second metal layer 113, it is convenient for the first tab 200 to achieve electrical connection with the second metal layer 113 through the second protrusion, which is beneficial to improving the electrical connection reliability between the first tab 200 and the second metal layer 113.

[0088] In some embodiments, the first protrusion 221 extends linearly or curvilinearly within the surface of the first bifurcated portion 220 facing the first metal layer 112, and the number of the first protrusions 221 is multiple, and the multiple first protrusions 221 cross to form a network structure.

[0089] By arranging the first protrusion 221 to extend linearly or curvilinearly within the surface of the first bifurcated portion 220 facing the first metal layer 112, and the number of the first protrusions 221 is multiple, and the multiple first protrusions 221 cross to form a network structure, the area of the first protrusion 221 can be made larger and the distribution range can be made wider, so that the contact area between the first tab 200 and the first metal layer 112 is larger, and the electrical connection reliability between the first tab 200 and the first metal layer 112 is higher.

[0090] In other embodiments, the number of the first protrusions 221 can also be one.

[0091] In some embodiments, the second protrusion extends linearly or curvilinearly within the surface of the second bifurcated portion 230 facing the second metal layer 113, and the number of the second protrusions is multiple, and the multiple second protrusions cross to form a network structure.

[0092] By arranging the second protrusion to extend linearly or curvilinearly within the surface of the second bifurcated portion 230 facing the second metal layer 113, and the number of the second protrusions is multiple, and the multiple second protrusions cross to form a network structure, the area of the second protrusion can be made larger and the distribution range can be made wider, so that the contact area between the first tab 200 and the second metal layer 113 is larger, and the electrical connection reliability between the first tab 200 and the second metal layer 113 is higher.

[0093] In other embodiments, the number of the second protrusions can also be one.

[0094] See Figure 5 , Figure 5 is a bottom view schematic diagram of a partial structure of an electrode assembly provided in other embodiments of the present application.

[0095] In other embodiments, a first groove 222 is provided on the surface of the first bifurcated portion 220 facing the first metal layer 112, and at least a part of the first adhesive member 310 is accommodated in the first groove 222.

[0096] By arranging a first groove 222 on the surface of the first bifurcated portion 220 facing the first metal layer 112, and at least part of the first bonding member 310 is received in the first groove 222, it is possible to make the space occupied by the first bonding member 310 in the thickness direction of the first composite current collector 110 smaller or not to occupy extra space, so that the overall thickness of the first tab 200, the first bonding member 310 and the first composite current collector 110 is smaller, which is beneficial to reducing the thickness of the electrode assembly 10 and beneficial to making the energy density of the battery cell provided with this electrode assembly 10 higher.

[0097] In some embodiments, a second groove (not shown in the figure) is arranged on the surface of the second bifurcated portion 230 facing the second metal layer 113, and at least part of the second bonding member 320 is received in the second groove.

[0098] By arranging a second groove on the surface of the second bifurcated portion 230 facing the second metal layer 113, and at least part of the second bonding member 320 is received in the second groove, it is possible to make the space occupied by the second bonding member 320 in the thickness direction of the first composite current collector 110 smaller or not to occupy extra space, so that the overall thickness of the first tab 200, the second bonding member 320 and the first composite current collector 110 is smaller, which is beneficial to reducing the thickness of the electrode assembly 10 and beneficial to making the energy density of the battery cell provided with this electrode assembly 10 higher.

[0099] In some embodiments, the first groove 222 extends linearly or curvilinearly on the surface of the first bifurcated portion 220 facing the first metal layer 112, the number of the first grooves 222 is multiple, and the groove walls of the multiple first grooves 222 intersect to form a network structure.

[0100] By making the first groove 222 extend linearly or curvilinearly on the surface of the first bifurcated portion 220 facing the first metal layer 112, the number of the first grooves 222 is multiple, and the groove walls of the multiple first grooves 222 intersect to form a network structure, it is possible to make the area of the first groove 222 larger and the distribution range wider, so that the bonding area between the first bonding member 310 and the first tab 200 and the first metal layer 112 is larger, and the connection reliability between the first tab 200 and the first metal layer 112 is higher.

[0101] In some embodiments, the second groove extends linearly or curvilinearly on the surface of the second bifurcated portion 230 facing the second metal layer 113, the number of the second grooves is multiple, and the groove walls of the multiple second grooves intersect to form a network structure.

[0102] By making the second groove extend linearly or curvilinearly in the surface of the second bifurcated portion 230 facing the second metal layer 113, and the number of the second grooves being multiple, the groove walls of the multiple second grooves intersect to form a network structure, the area of the second groove can be made larger and the distribution range can be wider, so that the bonding area between the second bonding member 320 and the first tab 200 and the first metal layer 112 is larger, and the connection reliability between the first tab 200 and the first metal layer 112 is higher.

[0103] See Figure 6 , Figure 6 is a top view schematic diagram of a partial structure of an electrode assembly provided in some other embodiments of the present application.

[0104] In some embodiments, a first through hole 223 is provided on the first bifurcated portion 220, and at least a part of the first bonding member 310 is received in the first through hole 223.

[0105] By making a first through hole 223 provided on the first bifurcated portion 220 and at least a part of the first bonding member 310 being received in the first through hole 223, the space occupied by the first bonding member 310 in the thickness direction of the first composite current collector 110 can be made smaller or no additional space is occupied, so that the overall thickness of the first tab 200, the first bonding member 310 and the first composite current collector 110 is smaller, which is beneficial to reducing the thickness of the electrode assembly 10, beneficial to making the energy density of the battery cell provided with this electrode assembly 10 higher, and the preparation process of the first through hole 223 is simple.

[0106] In some embodiments, a second through hole 231 is provided on the second bifurcated portion 230, and at least a part of the second bonding member 320 is received in the second through hole 231.

[0107] By making a second through hole 231 provided on the second bifurcated portion 230 and at least a part of the second bonding member 320 being received in the second through hole 231, the space occupied by the second bonding member 320 in the thickness direction of the first composite current collector 110 can be made smaller or no additional space is occupied, so that the overall thickness of the first tab 200, the second bonding member 320 and the first composite current collector 110 is smaller, which is beneficial to reducing the thickness of the electrode assembly 10, beneficial to making the energy density of the battery cell provided with this electrode assembly 10 higher, and the preparation process of the second through hole is simple.

[0108] In some embodiments, a plurality of first through holes 223 are provided on the first bifurcated portion 220, and the plurality of first through holes 223 are arranged in an array.

[0109] By providing a plurality of first through-holes 223 on the first bifurcated portion 220, with the plurality of first through-holes 223 arranged in an array, the area of the first through-holes 223 can be made larger and the distribution more uniform. As a result, the bonding area between the first bonding member 310 and the first tab 200 and the first metal layer 112 is larger, and the connection reliability between the first tab 200 and the first metal layer 112 is higher.

[0110] In some embodiments, a plurality of second through-holes 231 are provided on the second bifurcated portion 230, and the plurality of second through-holes 231 are arranged in an array.

[0111] By providing a plurality of second through-holes 231 on the second bifurcated portion 230, with the plurality of second through-holes 231 arranged in an array, the area of the second through-holes 231 can be made larger and the distribution more uniform. As a result, the bonding area between the second bonding member 320 and the first tab 200 and the first metal layer 112 is larger, and the connection reliability between the first tab 200 and the first metal layer 112 is higher.

[0112] In some embodiments, the first main body portion 210, the first bifurcated portion 220, and the second bifurcated portion 230 are integrally formed.

[0113] By integrally forming the first main body portion 210, the first bifurcated portion 220, and the second bifurcated portion 230, the structural stability of the first tab 200 can be made higher, which is beneficial to improving the connection stability between the first metal layer 112 and the second metal layer 113.

[0114] In other embodiments, the first main body portion 210, the first bifurcated portion 220, and the second bifurcated portion 230 can also be fixedly connected by welding, bonding, or other means.

[0115] See Figures 2 to 4 , in some embodiments, the first bifurcated portion 220 and the second bifurcated portion 230 are connected to the same end of the first main body portion 210. Along the thickness direction of the first composite current collector 110, the projections of the first bifurcated portion 220 and the second bifurcated portion 230 do not overlap, such that the overall thickness of the first bifurcated portion 220, the first bonding member 310, the second bifurcated portion 230, the second bonding member 320, and the first composite current collector 110 is smaller, which is beneficial to reducing the thickness of the electrode assembly 10 and improving the volumetric energy density of the battery cell.

[0116] By connecting the first bifurcated portion 220 and the second bifurcated portion 230 to the same end of the first main body portion 210, it is convenient for the first bifurcated portion 220 and the second bifurcated portion 230 to be respectively connected to the first metal layer 112 and the second metal layer 113. By making the projections of the first bifurcated portion 220 and the second bifurcated portion 230 not overlap along the thickness direction of the first composite current collector 110, it is convenient for the preparation of the first bifurcated portion 220 and the second bifurcated portion 230.

[0117] In some embodiments, the first bifurcated portion 220 and the second bifurcated portion 230 are connected to the same end of the first main body portion 210 along the second direction Y, and the first bifurcated portion 220 and the second bifurcated portion 230 are arranged along the third direction Z.

[0118] In some embodiments, along the width direction (the third direction Z) of the first composite current collector, the spacing distance D1 between the first bifurcated portion 220 and the second bifurcated portion 230 satisfies 0.5 mm ≤ D1 ≤ 3 mm. For example, D1 can be 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 2 mm, 2.5 mm, 3 mm, etc.

[0119] When D1 is greater than or equal to 0.5 mm, it is convenient to prepare the first tab 200, and it is convenient for the first bifurcated portion 220 to be connected to the first metal layer 112 through the first bonding member 310, and it is convenient for the second bifurcated portion 230 to be connected to the second metal layer 113 through the second bonding member 320; when D1 is less than or equal to 3 mm, the size of the first tab 200 in the width direction of the first composite current collector can be reduced, the space occupied by the first tab 200 can be reduced, which is beneficial to improving the energy density of the battery cell; therefore, when 0.5 mm ≤ D1 ≤ 3 mm, it can not only facilitate the preparation and assembly of the first tab 200, but also reduce the space occupied by the first tab 200, which is beneficial to making the energy density of the battery cell provided with this electrode assembly 10 higher.

[0120] See Figure 7 , Figure 7 is a schematic side view of a partial structure of an electrode assembly provided in some other embodiments of the present application.

[0121] In some other embodiments, the first bifurcated portion 220 and the second bifurcated portion 230 are connected to the same end of the first main body portion 210, and along the thickness direction of the first composite current collector, the projections of the first bifurcated portion 220 and the second bifurcated portion 230 at least partially overlap.

[0122] By making the first bifurcated portion 220 and the second bifurcated portion 230 connected to the same end of the first main body portion 210, and by making the projections of the first bifurcated portion 220 and the second bifurcated portion 230 at least partially overlap along the thickness direction of the first composite current collector, it is convenient for the first bifurcated portion 220 and the second bifurcated portion 230 to be respectively connected to the first metal layer 112 and the second metal layer 113.

[0123] See Figure 8 and Figure 9 , Figure 8 is a schematic side view structure diagram of the first electrode tab of an electrode assembly provided in some other embodiments of the present application; Figure 9 is a schematic top view of a partial structure of an electrode assembly provided in some other embodiments of the present application.

[0124] In some embodiments, on one side in the length direction (the second direction Y) of the first composite current collector, a first receiving groove 1121 is provided in the first metal layer 112, and at least part of the first bifurcated portion 220 is disposed in the first receiving groove 1121.

[0125] By disposing at least part of the first bifurcated portion 220 in the first receiving groove 1121, the overall thickness of the first electrode tab 100 and the first electrode ear 200 can be reduced, which is beneficial to reducing the thickness of the electrode assembly 10 and making the energy density of the battery cell provided with this electrode assembly 10 higher.

[0126] In some embodiments, at least part of the first adhesive member 310 is received in the first receiving groove 1121.

[0127] In some embodiments, along the length direction of the first composite current collector, the spacing distance D2 between the first bifurcated portion 220 and the first side wall 1121a of the first receiving groove 1121 satisfies 0.5 mm ≤ D2 ≤ 5 mm. For example, D2 can be 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, or 5 mm, etc.

[0128] Along the width direction of the first composite current collector, the spacing distance D3 between the first bifurcated portion 220 and the first side wall 1121a of the first receiving groove 1121 satisfies 0.5 mm ≤ D3 ≤ 5 mm. For example, D3 can be 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, or 5 mm, etc.

[0129] When D2 is greater than or equal to 0.5 mm and D3 is greater than or equal to 0.5 mm, it is convenient for the first bifurcated portion 220 to be received in the first receiving groove 1121; when D2 is less than or equal to 5 mm and D3 is less than or equal to 5 mm, the space occupied by the first receiving groove 1121 can be made smaller, so that the area of the first metal layer 112 is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110; therefore, when 0.5 mm ≤ D2 ≤ 5 mm and 0.5 mm ≤ D3 ≤ 5 mm, it is both convenient for the first bifurcated portion 220 to be received in the first receiving groove 1121 and the area of the first metal layer 112 can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110.

[0130] In some embodiments, along the width direction of the first composite current collector, the width of the first receiving groove 1121 is W1, satisfying 5 mm ≤ W1 ≤ 7 mm. For example, W1 can be 5 mm, 5.2 mm, 5.5 mm, 6 mm, 6.5 mm, or 7 mm, etc.

[0131] When W1 is greater than or equal to 5 mm, it is convenient to accommodate the first bifurcated portion 220; when W1 is less than or equal to 7 mm, the space occupied by the first accommodating groove 1121 can be made smaller, so that the area of the first metal layer 112 is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110; therefore, when 5 mm ≤ W1 ≤ 7 mm, it is both convenient to accommodate the first bifurcated portion 220 and the area of the first metal layer 112 can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110.

[0132] See Figure 8 and Figure 10 , Figure 10 is a top view schematic diagram of a partial structure of an electrode assembly provided in some other embodiments of the present application.

[0133] In some embodiments, on one side along the length direction of the first composite current collector, the second metal layer 113 is provided with a second accommodating groove 1131, and at least a part of the second bifurcated portion 230 is disposed in the second accommodating groove 1131.

[0134] By disposing at least a part of the second bifurcated portion 230 in the second accommodating groove 1131, the overall thickness of the first electrode tab 100 and the first electrode ear 200 can be reduced, which is beneficial to reducing the thickness of the electrode assembly 10 and making the energy density of the battery cell provided with the electrode assembly 10 higher.

[0135] In some embodiments, at least a part of the second bonding member 320 is accommodated in the second accommodating groove 1131.

[0136] In some embodiments, along the length direction of the first composite current collector, the spacing distance D4 between the second bifurcated portion 230 and the second side wall 1131a of the second accommodating groove 1131 satisfies 0.5 mm ≤ D4 ≤ 5 mm. For example, D4 can be 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm or 5 mm, etc.

[0137] Along the width direction of the first composite current collector, the spacing distance D5 between the second bifurcated portion 230 and the second side wall 1131a of the second accommodating groove 1131 satisfies 0.5 mm ≤ D5 ≤ 5 mm. For example, D5 can be 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm or 5 mm, etc.

[0138] When D4 is greater than or equal to 0.5 mm and D5 is greater than or equal to 0.5 mm, it is convenient for the second bifurcation portion 230 to be received in the second receiving groove 1131; when D4 is less than or equal to 5 mm and D5 is less than or equal to 5 mm, the space occupied by the second receiving groove 1131 can be made smaller, so that the area of the second metal layer 113 is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110; therefore, when 0.5 mm ≤ D4 ≤ 5 mm and 0.5 mm ≤ D5 ≤ 5 mm, it is both convenient for the second bifurcation portion 230 to be received in the second receiving groove 1131 and the area of the second metal layer 113 can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110.

[0139] In some embodiments, along the width direction of the first composite current collector, the width of the second receiving groove 1131 is W2, satisfying 5 mm ≤ W2 ≤ 7 mm. For example, W2 can be 5 mm, 5.2 mm, 5.5 mm, 6 mm, 6.5 mm or 7 mm, etc.

[0140] When W2 is greater than or equal to 5 mm, it is convenient to receive the second bifurcation portion 230; when W2 is less than or equal to 7 mm, the space occupied by the second receiving groove 1131 can be made smaller, so that the area of the second metal layer 113 is larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110; therefore, when 5 mm ≤ W1 ≤ 7 mm, it is both convenient to receive the second bifurcation portion 230 and the area of the second metal layer 113 can be made larger, which is beneficial to improving the current-carrying capacity of the first composite current collector 110.

[0141] See Figure 8 , in some embodiments, along the thickness direction of the first composite current collector, the first receiving groove 1121 and the second receiving groove 1131 partially overlap or do not overlap. The first composite current collector 110 has opposite first end 110a and second end 110b in its width direction. Along the width direction of the first composite current collector, the first receiving groove 1121 has a first sub-sidewall 1121b close to the first end 110a, and the second receiving groove 1131 has a second sub-sidewall 1131b close to the first end 110a. The distance S1 between the first sub-sidewall 1121b and the second sub-sidewall 1131b in the width direction of the first composite current collector satisfies 3 mm ≤ S1 ≤ 8 mm. For example, S1 can be 3 mm, 3.5 mm, 4 mm, 5.5 mm, 7 mm or 8 mm, etc.

[0142] When S1 is greater than or equal to 3 mm, it is convenient for the preparation of the first accommodating groove 1121 and the second accommodating groove 1131; when S1 is less than or equal to 8 mm, the overall space occupied by the first accommodating groove 1121 and the second accommodating groove 1131 in the width direction of the first composite current collector is relatively small, correspondingly, the space occupied by the first tab 200 is relatively small, which is beneficial to making the energy density of the battery cell provided with this electrode assembly 10 higher, and is convenient for arranging other components in the width direction of the first composite current collector.

[0143] In some embodiments, the first composite current collector 110 has a third end 110c in its length direction, the first tab 200 extends from the third end 110c of the first composite current collector 110, along the length direction of the first composite current collector, the first accommodating groove 1121 has a third sub-side wall 1121c away from the third end 110c, the second accommodating groove 1131 has a fourth sub-side wall 1131c away from the third end 110c, and the distance S2 between the third sub-side wall 1121c and the fourth sub-side wall 1131c in the length direction of the first composite current collector satisfies 0 mm ≤ S2 ≤ 2 mm. For example, S2 can be 0 mm, 0.1 mm, 0.5 mm, 0.8 mm, 1 mm or 2 mm, etc.

[0144] In other embodiments, along the thickness direction of the first composite current collector, the first accommodating groove 1121 overlaps with the second accommodating groove 1131.

[0145] It should be noted that the overlap between the first accommodating groove 1121 and the second accommodating groove 1131 is not an absolute overlap, and a certain error is allowed. For example, the error in the length direction or width direction of the first composite current collector is ±2 mm.

[0146] In some embodiments, the first adhesive 310 includes conductive particles.

[0147] By making the first adhesive 310 include conductive particles, the first tab 200 can be electrically connected to the first metal layer 112 through the first adhesive 310, and the electrical connection reliability between the first tab 200 and the first metal layer 112 is higher.

[0148] In this embodiment, the first bifurcated portion 220 may not be in contact with the first metal layer 112, and the first bifurcated portion 220 is conductively connected to the first metal layer 112 through the first adhesive 310, which can make the area of the first adhesive 310 larger and the connection between the first bifurcated portion 220 and the first metal layer 112 more stable.

[0149] In this embodiment, a part of the first bifurcated portion 220 can also be in contact with the first metal layer 112, and the other part is connected to the first metal layer 112 through the first bonding member 310, which can make the electrical connection between the first bifurcated portion 220 and the first metal layer 112 more stable and reliable.

[0150] In some embodiments, the second bonding member 320 includes conductive particles.

[0151] By making the second bonding member 320 include conductive particles, the first tab 200 can be electrically connected to the second metal layer 113 through the second bonding member 320, and the electrical connection reliability between the first tab 200 and the second metal layer 113 is higher.

[0152] In this embodiment, the second bifurcated portion 230 may not be in contact with the second metal layer 113, and the second bifurcated portion 230 is conductively connected to the second metal layer 113 through the second bonding member 320, which can make the area of the second bonding member 320 larger and the connection between the second bifurcated portion 230 and the second metal layer 113 more stable.

[0153] In this embodiment, a part of the second bifurcated portion 230 can also be in contact with the second metal layer 113, and the other part is connected to the second metal layer 113 through the second bonding member 320, which can make the electrical connection between the second bifurcated portion 230 and the second metal layer 113 more stable and reliable.

[0154] See Figure 1 and Figure 3 , in some embodiments, the electrode assembly 10 further includes a second electrode plate 400, a second tab 500, a third bonding member 610, and a fourth bonding member 620. The second electrode plate 400 has a polarity opposite to that of the first electrode plate 100. The second electrode plate 400 includes a second composite current collector 410, and the second composite current collector 410 includes a second insulating layer 411, a third metal layer 412, and a fourth metal layer 413. The third metal layer 412 and the fourth metal layer 413 are respectively disposed on both sides of the second insulating layer 411 along its thickness direction. The second tab 500 includes a second main body portion 510, a third bifurcated portion 520, and a fourth bifurcated portion 530. Both the third bifurcated portion 520 and the fourth bifurcated portion 530 are connected to the second main body portion 510. The third bifurcated portion 520 is electrically connected to the third metal layer 412 and is connected through the third bonding member 610. The fourth bifurcated portion 530 is electrically connected to the fourth metal layer 413 and is connected through the fourth bonding member 620.

[0155] By making the second electrode tab 400 include a second composite current collector 410, the second composite current collector 410 includes a second insulating layer 411, a third metal layer 412, and a fourth metal layer 413. The third metal layer 412 and the fourth metal layer 413 are respectively disposed on both sides of the second insulating layer 411 along its thickness direction, which can reduce the weight of the second electrode tab 400. Moreover, the third metal layer 412 and the fourth metal layer 413 are relatively thin, and there are fewer burrs generated during the mechanical damage process of the battery cell, which is beneficial to reducing the possibility of short circuit of the electrode assembly 10 and improving the safety of the electrode assembly 10. By making the second tab 500 include a second main body portion 510, a third bifurcated portion 520, and a fourth bifurcated portion 530, both the third bifurcated portion 520 and the fourth bifurcated portion 530 are connected to the second main body portion 510. The third bifurcated portion 520 is electrically connected to the third metal layer 412 and is connected through a third bonding member 610, and the fourth bifurcated portion 530 is electrically connected to the fourth metal layer 413 and is connected through a fourth bonding member 620, enabling the third metal layer 412 and the fourth metal layer 413 to be electrically connected through the second tab 500. Moreover, the third bonding member 610 and the fourth bonding member 620 can make the connection between the second tab 500 and the second composite current collector 410 stable, and the electrical connection stability and consistency between the third metal layer 412 and the fourth metal layer 413 are good, which is beneficial to improving the performance of the battery cell.

[0156] In some embodiments, the first electrode tab 100 is a positive electrode tab, and the second electrode tab 400 is a negative electrode tab.

[0157] In other embodiments, the first electrode tab 100 is a negative electrode tab, and the second electrode tab 400 is a positive electrode tab.

[0158] In some embodiments, the electrode assembly 10 may be a stacked structure formed by laminating a negative electrode tab, a separator, and a positive electrode tab.

[0159] In other embodiments, the electrode assembly 10 may also be a wound structure formed by winding a negative electrode tab, a separator, and a positive electrode tab.

[0160] See Figure 11 , Figure 11 which is a schematic three-dimensional structure diagram of a battery cell provided in some embodiments of the present application.

[0161] An embodiment of the present application provides a battery cell, which includes the electrode assembly 10 provided in any of the above embodiments.

[0162] In some embodiments, the battery cell includes a housing 20, and the electrode assembly 10 is disposed inside the housing 20.

[0163] In some embodiments, the housing 20 can be made of a material with high strength, such as metal materials like steel and aluminum alloy, so that the housing 20 has high stress-bearing performance, and thus it can be ensured that the housing 20 is not easily deformed or damaged due to stress or environmental changes, and further the reliability of the battery cell can be higher.

[0164] In some other embodiments, the housing 20 can also be a non-metal material with high strength, such as carbon fiber and hard plastic.

[0165] In some embodiments, the battery cell further includes an electrolyte, which is contained in the housing 20. The battery cell mainly works by the movement of metal ions between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector. The part of the positive current collector without the coated positive active material layer serves as the positive electrode tab to realize the electrical energy input or output of the positive electrode plate through the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobaltate, lithium iron phosphate, ternary material, lithium manganate, etc. The negative electrode plate includes a negative current collector and a negative active material layer, and the negative active material layer is coated on the surface of the negative current collector. The part of the negative current collector without the coated negative active material layer serves as the negative electrode tab to realize the electrical energy input or output of the negative electrode plate through the negative electrode tab. The material of the negative current collector can be copper, and the negative active material can be carbon material or silicon material, etc. The material of the separator can be polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include organic solvents, electrolyte lithium salts, etc.

[0166] An embodiment of the present application provides an electrical device, including the battery cell of any of the above solutions, and the battery cell is used to provide electrical energy for the electrical device.

[0167] The electrical device can be any of the aforementioned devices or systems applying the battery cell.

[0168] The features and properties of the electrode assembly 10 of the present application will be further described in detail below in conjunction with embodiments.

[0169] Preparation of the comparative example and the embodiment:

[0170] Comparative Example 1:

[0171] The first electrode plate includes a first composite current collector, the first composite current collector is an aluminum composite current collector, the thickness of the first metal layer is 1.5 um, the thickness of the second metal layer is 1.5 um, and the thickness of the first insulating layer is 6 um;

[0172] The first electrode tab is an aluminum electrode tab, the length of the first electrode tab is 38 mm, the width is 6 mm, and the thickness is 80 um;

[0173] The first electrode tab is arranged in a rectangle, and the surface is a plane;

[0174] The first tab and the first composite current collector are welded by ultrasonic welding;

[0175] The tensile force value between the first tab and the first composite current collector is measured to be 1 N, the resistance of the first metal layer is 5 mΩ, the resistance of the second metal layer is 5 mΩ, and the weld mark height is 100 μm.

[0176] Comparative Example 2:

[0177] The first electrode sheet includes a first composite current collector, the first composite current collector is an aluminum composite current collector, the thickness of the first metal layer is 1.5 μm, the thickness of the second metal layer is 1.5 μm, and the thickness of the first insulating layer is 6 μm;

[0178] The first tab is an aluminum tab, the length of the first tab is 38 mm, the width is 6 mm, and the thickness is 80 μm;

[0179] The first tab is arranged in a rectangle and its surface is flat;

[0180] The first tab and the first composite current collector are riveted by riveting;

[0181] The tensile force value between the first tab and the first composite current collector is measured to be 20 N, the resistance of the first metal layer is 5 mΩ, the resistance of the second metal layer is 7 mΩ, and the weld mark height is 180 μm.

[0182] Example 1:

[0183] The first electrode sheet includes a first composite current collector, the first composite current collector is an aluminum composite current collector, the thickness of the first metal layer is 1.5 μm, the thickness of the second metal layer is 1.5 μm, and the thickness of the first insulating layer is 6 μm;

[0184] The first tab is an aluminum tab, the length of the first tab is 38 mm, the width is 6 mm, and the thickness is 80 μm;

[0185] The first tab includes a first main body part, a first bifurcated part and a second bifurcated part. The width of the first bifurcated part is 3 mm and the thickness is 80 μm, the width of the second bifurcated part is 3 mm and the thickness is 80 μm, and the length of the first main body part is 26 mm;

[0186] A first groove with a reticular structure is arranged on the surface of the first bifurcated part facing the first metal layer. A first adhesive with a thickness of 10 μm is arranged between the first bifurcated part and the first metal layer, and at least part of the first adhesive is accommodated in the first groove; A second groove with a reticular structure is arranged on the surface of the second bifurcated part facing the second metal layer. A second adhesive with a thickness of 10 μm is arranged between the second bifurcated part and the second metal layer, and at least part of the second adhesive is accommodated in the second groove;

[0187] Bond the first tab and the first composite current collector by hot pressing and curing;

[0188] The measured tensile force value between the first tab and the first composite current collector is 20 N, the resistance of the first metal layer is 5 mΩ, the resistance of the second metal layer is 5 mΩ, and the height of the welding mark is 100 μm.

[0189] From the above comparative examples and embodiments, it can be seen that in this application, the first tab includes a first main body portion, a first bifurcated portion, and a second bifurcated portion, and the first bifurcated portion is connected to the first metal layer through a first bonding member, and the second bifurcated portion is connected to the second metal layer through a second bonding member. This can not only make the layer connection strength between the first tab and the first composite current collector relatively high, but also make the electrical connection stability and consistency between the first metal layer and the second metal layer better, and it occupies less space in the thickness direction of the first composite current collector, which is beneficial to improving the energy density of the battery cell.

[0190] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0191] The above are only the preferred embodiments of this application and are not used to limit this application. For those skilled in the art, this application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims

1. An electrode assembly, characterized in that, Comprising: A first electrode tab, the first electrode tab includes a first composite current collector, the first composite current collector includes a first insulating layer, a first metal layer and a second metal layer, the first metal layer and the second metal layer are respectively disposed on both sides of the first insulating layer along its thickness direction; A first tab, including a first main body portion, a first bifurcated portion and a second bifurcated portion, both the first bifurcated portion and the second bifurcated portion are connected to the first main body portion; A first bonding member, the first bifurcated portion is electrically connected to the first metal layer and is connected through the first bonding member; And A second bonding member, the second bifurcated portion is electrically connected to the second metal layer and is connected through the second bonding member.

2. The electrode assembly according to claim 1, characterized in that, The first bifurcated portion is in contact with the first metal layer; and / or, the second bifurcated portion is in contact with the second metal layer.

3. The electrode assembly according to claim 2, wherein, A first protrusion is provided on the surface of the first bifurcated portion facing the first metal layer, and the first protrusion is in contact with the first metal layer; and / or, A second protrusion is provided on the surface of the second bifurcated portion facing the second metal layer, and the second protrusion is in contact with the second metal layer.

4. The electrode assembly according to claim 3, wherein The first protrusion extends linearly or curvilinearly within the surface of the first bifurcated portion facing the first metal layer, the number of the first protrusions is multiple, and multiple first protrusions cross to form a network structure; And / or, The second protrusion extends linearly or curvilinearly within the surface of the second bifurcated portion facing the second metal layer, the number of the second protrusions is multiple, and multiple second protrusions cross to form a network structure.

5. The electrode assembly according to claim 2, characterized in that, A first groove is provided on the surface of the first bifurcated portion facing the first metal layer, and at least part of the first bonding member is received in the first groove; and / or, A second groove is provided on the surface of the second bifurcated portion facing the second metal layer, and at least part of the second bonding member is received in the second groove.

6. The electrode assembly according to claim 5, wherein The first groove extends linearly or curvilinearly within the surface of the first bifurcated portion facing the first metal layer, the number of the first grooves is multiple, and the groove walls of multiple first grooves cross to form a network structure; And / or, The second groove extends linearly or curvilinearly within the surface of the second bifurcated portion facing the second metal layer, the number of the second grooves is multiple, and the groove walls of multiple second grooves cross to form a network structure.

7. The electrode assembly according to claim 2, characterized in that, A first through hole is provided on the first bifurcated portion, and at least part of the first bonding member is received in the first through hole; and / or, A second through hole is provided on the second bifurcated portion, and at least part of the second bonding member is received in the second through hole.

8. The electrode assembly according to claim 7, wherein, Multiple first through holes are provided on the first bifurcated portion, and multiple first through holes are arranged in an array; and / or, Multiple second through holes are provided on the second bifurcated portion, and multiple second through holes are arranged in an array.

9. The electrode assembly according to claim 1, wherein The first main body portion, the first bifurcated portion and the second bifurcated portion are integrally formed.

10. The electrode assembly according to claim 1, wherein, The first bifurcated portion and the second bifurcated portion are connected to the same end of the first main body portion, and along the thickness direction of the first composite current collector, the projections of the first bifurcated portion and the second bifurcated portion do not overlap.

11. The electrode assembly according to claim 10, characterized in that, In the width direction of the first composite current collector, the spacing distance between the first bifurcated portion and the second bifurcated portion is D1, satisfying 0.5 mm ≤ D1 ≤ 3 mm.

12. The electrode assembly according to claim 1, wherein The first bifurcated portion and the second bifurcated portion are connected to the same end of the first main body portion. In the thickness direction of the first composite current collector, the projections of the first bifurcated portion and the second bifurcated portion at least partially overlap.

13. The electrode assembly according to claim 1, wherein, On one side in the length direction of the first composite current collector, the first metal layer is provided with a first accommodation groove, and at least part of the first bifurcated portion is disposed in the first accommodation groove.

14. The electrode assembly according to claim 13, wherein In the length direction of the first composite current collector, the spacing distance between the first bifurcated portion and the first side wall of the first accommodation groove is D2, satisfying 0.5 mm ≤ D2 ≤ 5 mm; In the width direction of the first composite current collector, the spacing distance between the first bifurcated portion and the first side wall of the first accommodation groove is D3, satisfying 0.5 mm ≤ D3 ≤ 5 mm.

15. The electrode assembly according to claim 13, wherein, In the width direction of the first composite current collector, the width of the first accommodation groove is W1, satisfying 5 mm ≤ W1 ≤ 7 mm.

16. The electrode assembly according to claim 13, wherein, On one side in the length direction of the first composite current collector, the second metal layer is provided with a second accommodation groove, and at least part of the second bifurcated portion is disposed in the second accommodation groove.

17. The electrode assembly according to claim 16, characterized in that, In the length direction of the first composite current collector, the spacing distance between the second bifurcated portion and the second side wall of the second accommodation groove is D4, satisfying 0.5 mm ≤ D4 ≤ 5 mm; In the width direction of the first composite current collector, the spacing distance between the second bifurcated portion and the second side wall of the second accommodation groove is D5, satisfying 0.5 mm ≤ D5 ≤ 5 mm.

18. The electrode assembly according to claim 16, wherein In the width direction of the first composite current collector, the width of the second accommodation groove is W2, satisfying 5 mm ≤ W2 ≤ 7 mm.

19. The electrode assembly according to claim 16, wherein, In the thickness direction of the first composite current collector, the first accommodation groove and the second accommodation groove partially overlap or do not overlap; The first composite current collector has opposite first and second ends in its width direction. In the width direction of the first composite current collector, the first accommodation groove has a first sub-side wall close to the first end, the second accommodation groove has a second sub-side wall close to the first end, and the distance between the first sub-side wall and the second sub-side wall in the width direction of the first composite current collector is S1, satisfying 3 mm ≤ S1 ≤ 8 mm.

20. The electrode assembly according to claim 1, wherein, The first adhesive member includes conductive particles; and / or, the second adhesive member includes conductive particles.

21. The electrode assembly according to claim 1, wherein The electrode assembly further includes: A second electrode tab, having a polarity opposite to that of the first electrode tab. The second electrode tab includes a second composite current collector, and the second composite current collector includes a second insulating layer, a third metal layer, and a fourth metal layer. The third metal layer and the fourth metal layer are respectively disposed on both sides of the second insulating layer along its thickness direction; A second tab, including a second main body portion, a third bifurcated portion, and a fourth bifurcated portion, and both the third bifurcated portion and the fourth bifurcated portion are connected to the second main body portion; A third adhesive member, the third bifurcated portion is electrically connected to the third metal layer and is connected through the third adhesive member; and The fourth bonding member, the fourth bifurcated portion and the fourth metal layer are electrically connected and connected by the fourth bonding member.

22. A battery cell, characterized in that, The battery cell includes the electrode assembly according to any one of claims 1-21.

23. An electrical device, characterized in that, The electrical device includes the battery cell according to claim 22, and the battery cell is used to provide electrical energy.

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