Secondary battery and electronic device

Abstract

A secondary battery (100A), comprising an electrode assembly (10), a case (70), and a first tab assembly (50). The electrode assembly (10) comprises a first electrode sheet (20), a second electrode sheet (30), and a separator (40). The electrode assembly (10) is formed by stacking the first electrode sheet (20), the separator (40) and the second electrode sheet (30) in a first direction (Z). The first direction (Z) is the thickness direction of the electrode assembly (10). The electrode assembly (10) comprises a plurality of side surfaces (11) connected in sequence, wherein one of the side surfaces (11) is a first side surface (11A), and the other of the side surfaces (11) is a second side surface (11B). The electrode assembly (10) is accommodated in the case (70). The first tab assembly (50) comprises a plurality of first tabs (51) and one second tab (52). The plurality of first tabs (51) extend from the first side surface (11A), the plurality of first tabs (51) are separately connected to the first electrode sheet (20), and the plurality of first tabs (51) are electrically connected to each other and accommodated in the case (70). The second tab (52) extends from the second side surface (11B) in a second direction (X), one end of the second tab (52) is connected to one first electrode sheet (20), and the other end of the second tab (52) extends out of the case (70). The arrangement of the first tabs (51) and the second tab (52) can improve the energy density of the secondary battery (100A).

Description

Secondary batteries and electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202411034844.8, filed on July 30, 2024, entitled "Secondary Battery and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of energy storage technology, and in particular to a secondary battery and electronic device. Background Technology

[0003] Laminated cells are widely used in the lithium-ion battery field due to their high energy density, low internal resistance, and long lifespan. During the fabrication of laminated cells, multiple layers of tabs need to be connected to tab leads via bonding and bending. The bonding and bending areas occupy a significant amount of space at the battery head (the area where the tabs extend out of the casing is called the battery head), leading to a decrease in the battery's energy density. Summary of the Invention

[0004] In view of the above, this application provides a secondary battery that is beneficial to improving energy density.

[0005] This application provides a secondary battery, which includes an electrode assembly, a housing, and a first tab assembly. The electrode assembly includes a first electrode, a second electrode, and a separator, with the separator disposed between the first and second electrodes. The electrode assembly is formed by stacking the first electrode, the separator, and the second electrode along a first direction. The first direction is the thickness direction of the electrode assembly. The electrode assembly includes multiple sequentially connected sides, one of which is a first side and the other is a second side. The electrode assembly is housed within the housing. The first tab assembly includes multiple first tabs and one second tab. The multiple first tabs extend from the first side, are respectively connected to the first electrode, are electrically connected to each other, and are housed within the housing. The second tab extends from the second side along a second direction, one end of which is connected to a first electrode, and the other end of which extends out of the housing. The second direction is perpendicular to the first direction.

[0006] In the aforementioned secondary battery, the second tab and the second side are located at the head of the secondary battery, while the first side and multiple first tabs are separated from the head of the secondary battery. The second tab and multiple first tabs are electrically connected through the first electrode plate. The second tab does not need to be bent to extend out of the casing from the second side, thereby reducing the space waste caused by the transfer welding at the head of the secondary battery. This is beneficial to improving the space utilization rate at the head of the secondary battery, and thus improving the energy density of the secondary battery.

[0007] In some embodiments of this application, multiple first tabs are integrally disposed with the first electrode to improve the connection stability between the first tabs and the corresponding first electrode, which facilitates the reduction of internal resistance and has the advantage of simple manufacturing process.

[0008] In some embodiments of this application, the first electrode includes a first current collector and a first active material layer. At least one surface of the first current collector in a first direction is provided with the first active material layer. The first active material layer has a first groove exposing the first current collector, and one end of the second electrode tab is located within the first groove and connected to the first current collector. The second electrode tab shares space in the first direction with the first active material layer to improve the head space utilization of the secondary battery, thereby increasing the energy density of the secondary battery.

[0009] In some embodiments of this application, the first electrode includes a first current collector and a first active material layer. The first current collector includes a first region and a second region connected together. The first region is closer to a second side than the second region. The first region has no first active material layer on two surfaces in a first direction, while the second region has a first active material layer on at least one surface in the first direction. One end of the second electrode tab is connected to the first region to facilitate connection between the second electrode tab and the first current collector.

[0010] In some embodiments of this application, the second electrode tab and the first electrode plate are integrally disposed to improve the connection stability between the second electrode tab and the corresponding first electrode plate, facilitate the reduction of internal resistance, and have the advantages of simple manufacturing process.

[0011] In some embodiments of this application, the first side and the second side are arranged opposite to each other along the second direction, so that the first side and the plurality of first tabs are located at the tail of the secondary battery, which facilitates the plurality of first tabs to utilize the tail space of the secondary battery and improve the energy density of the secondary battery.

[0012] In some embodiments of this application, the first side and the second side are arranged adjacent to each other so that the first side and the plurality of first tabs are located on the side of the secondary battery, which facilitates the plurality of first tabs to utilize the side space of the secondary battery and improve the energy density of the secondary battery.

[0013] In some embodiments of this application, a plurality of first tabs are stacked along a first direction, and the plurality of first tabs are bent and disposed within the housing to reduce the space occupied by the first tabs in the second direction and improve the energy density of the secondary battery.

[0014] In some embodiments of this application, the first direction, the second direction, and the third direction are perpendicular to each other. Along the third direction, the widths of the interconnected first electrode plate and the first electrode tab are W1 and W2, respectively, with 0.1 ≤ W2 / W1 ≤ 0.5, to improve the current carrying capacity of the first electrode tab and to facilitate reserving space on the second side to accommodate another electrode tab assembly with the opposite polarity to the first electrode tab assembly, thereby reducing the risk of interference between the first electrode tab and the other electrode tab assembly.

[0015] In some embodiments of this application, the ratio of the length of each first tab extending from the first side in its extension direction to the thickness of the secondary battery in the first direction is less than or equal to 2, so that the first part and the second part formed by the convergence of multiple first tabs after one bend do not exceed the first side in the first direction, thereby improving the energy density of the secondary battery.

[0016] In some embodiments of this application, a plurality of first tabs are stacked along a first direction, and the ratio of the length of each first tab extending from the first side in its extension direction to the thickness of the secondary battery in the first direction is 0.5 to 2, so that the ends of the plurality of first tabs away from the first electrode sheet can be connected by welding.

[0017] In some embodiments of this application, the secondary battery further includes a plurality of first insulating elements, and at least one surface of the first electrode tab in a first direction is provided with a first insulating element to reduce the risk of short circuit caused by contact between the first electrode tab and the adjacent second electrode.

[0018] In some embodiments of this application, the first insulating element is an insulating coating, which includes inorganic particles and an adhesive. The adhesive includes at least one of polyvinylidene fluoride, polyacrylonitrile, sodium carboxymethyl cellulose, polyacrylic acid, polyvinyl alcohol, or polytetrafluoroethylene, and the inorganic particles include at least one of silica, boehmite, diaspore, or alumina.

[0019] In some embodiments of this application, the electrode assembly includes a first surface and a second surface, which are disposed opposite to each other along a first direction. The secondary battery also includes a second insulating member, one end of which is connected to the first surface, and the other end of which bypasses the first side surface and is connected to the second surface. The second insulating member also covers a plurality of first tabs to improve the structural stability of the plurality of first tabs on the first side surface and to improve the insulation stability between the plurality of first tabs and other structural components.

[0020] In some embodiments of this application, the first electrode includes a first current collector and a first active material layer, wherein the first current collector has the first active material layer on at least one surface in a first direction. Along the first direction, the thickness of the first current collector of the first electrode connecting the first tab and the second tab is D1, and the thickness of the first current collector of the first electrode connecting the first tab but not the second tab is D2, where D1 / D2 > 1. When D1 / D2 ≤ 1, the thickness of the first current collector of the first electrode connecting the first tab and the second tab is small, resulting in weak current carrying capacity and affecting cycle performance. By limiting D1 / D2 > 1, the cycle performance of the secondary battery is improved.

[0021] In some embodiments of this application, D1 / D2 ≤ 2.5. When D1 / D2 > 2.5, the thickness of the first current collector of the first electrode connecting the first and second tabs is relatively large, resulting in little improvement in cycle performance and a loss of energy density. By limiting D1 / D2 to ≤ 2.5, the energy density of the secondary battery can be improved.

[0022] In some embodiments of this application, the thickness of the second electrode tab is greater than that of the first electrode tab to improve the current carrying capacity of the second electrode tab, thereby improving the stability of the electrical connection between the second electrode tab and the external circuit.

[0023] In some embodiments of this application, along the first direction, the two first electrode plates located on the outermost sides of the electrode assembly are respectively the first outer electrode plate and the second outer electrode plate, and one end of the second electrode tab is connected to the first outer electrode plate or the second outer electrode plate to facilitate heat dissipation of the second electrode tab.

[0024] In some embodiments of this application, the housing is a packaging bag, and the housing includes a main body and a packaging part. Electrode assemblies and a plurality of first tabs are housed in the main body. The main body includes a first wall disposed opposite to a second side surface along a second direction. The packaging part includes a first packaging edge connected to the first wall, and second tabs extend from the first packaging edge to facilitate electrical connection with an external circuit.

[0025] In some embodiments of this application, the secondary battery further includes a second tab assembly. The second tab assembly includes multiple third tabs and one fourth tab. The multiple third tabs extend from a first side, are respectively connected to second electrodes, and are electrically connected to each other and housed within a casing. The fourth tab extends from a second side along a second direction, one end of the fourth tab is connected to a second electrode, and the other end extends out of the casing. The fourth tab and the second tab share the head space of the secondary battery, and the multiple third tabs and the multiple first tabs share the tail space of the secondary battery. The fourth tab and the multiple third tabs are electrically connected through second electrodes. The fourth tab does not need to be bent to extend from the second side of the casing, reducing space waste caused by transition welding at the head of the secondary battery, which is beneficial for improving the utilization rate of the head space of the secondary battery, thereby increasing the energy density of the secondary battery.

[0026] In some embodiments of this application, the thickness of the secondary battery along the first direction is H1, where H1≤2.5mm, to meet the size requirements of ultra-thin batteries.

[0027] Embodiments of this application also provide an electronic device, which includes any of the secondary batteries described in the above embodiments.

[0028] In the aforementioned secondary battery and electronic device, the second tab and the second side are located at the head of the secondary battery, while the first side and multiple first tabs are separated from the head of the secondary battery. The second tab and multiple first tabs are electrically connected through the first electrode plate. The second tab does not need to be bent to extend out of the casing from the second side, thereby reducing the space waste caused by the transfer welding at the head of the secondary battery. This is beneficial to improving the space utilization rate at the head of the secondary battery, and thus improving the energy density of the secondary battery. Attached Figure Description

[0029] Figure 1 is a schematic diagram of the secondary battery viewed along a first direction in one embodiment of this application.

[0030] Figure 2 is a schematic diagram of the structure of the first tab assembly of the secondary battery in one embodiment of this application.

[0031] Figure 3 is a schematic diagram of the connection between the first tab and the first electrode plate of a secondary battery in one embodiment of this application.

[0032] Figure 4 is a schematic diagram of the connection between the first tab and the first electrode plate of the secondary battery in another embodiment of this application.

[0033] Figure 5 is a schematic diagram of the connection between the first tab and the first electrode plate of the secondary battery in another embodiment of this application.

[0034] Figure 6 is a schematic diagram of the structure of the first and second outer electrodes of the secondary battery in one embodiment of this application.

[0035] Figure 7 is a schematic diagram of the structure of the second tab assembly of the secondary battery in one embodiment of this application.

[0036] Figure 8 is a schematic diagram of the secondary battery viewed along the first direction in another embodiment of this application.

[0037] Figure 9 is a schematic diagram of the secondary battery viewed along the first direction in another embodiment of this application.

[0038] Figure 10 is a schematic diagram of the structure of an electronic device in one embodiment of this application.

[0039] Key Component Symbols: Secondary Battery 100A, 100B, 100C; Electronic Device 200; Electrode Assembly 10; Side 11; First Side 11A; First End 11A1; Second End 11A2; Second Side 11B; First Reference Line O; First Surface 12; Second Surface 13; First Electrode 20; First Outer Electrode 20A; Second Outer Electrode 20B; First Current Collector 21; Second Reference Line E; First Region 211; Second Region 212; First Active Material Layer 22; First Groove 221; Second Electrode 30; Separator 40; First Tab Assembly 50; First Tab 51; First Part 51A; Second Part 51B; Second Tab 52; First Insulator 61; Second Insulator 62; Fourth Insulator 64; Housing 70; Main Body71 First wall 711 Encapsulation section 72 First encapsulation edge 721 Tab adhesive 75 Second tab assembly 80 Third tab 81 Third reference line F Fourth tab 82 First direction Z Second direction X Third direction Y

[0040] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0042] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component that is centrally located.

[0043] When one value is considered "equal" to another, it means that they are equal within a set deviation range, which is within 5%. In other words, if at least one of the two values ​​fluctuates within the set deviation range, they are considered approximately equal even if their values ​​are not equal. Similarly, when one value is considered to have a "1:1" ratio with another, it means that they are equal within a set deviation range, which is within 5%. Again, if at least one of the two values ​​fluctuates within the set deviation range, they are considered equal in ratio even if their values ​​are not equal.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The term "overlap" as used herein refers to the overlapping of the projected portions of two components or the coincidence of the projected portions of two components.

[0045] This application provides a secondary battery, which includes an electrode assembly, a housing, and a first tab assembly. The electrode assembly includes a first electrode, a second electrode, and a separator, with the separator disposed between the first and second electrodes. The electrode assembly is formed by stacking the first electrode, the separator, and the second electrode along a first direction. The first direction is the thickness direction of the electrode assembly. The electrode assembly includes multiple sequentially connected sides, one of which is a first side and the other is a second side. The electrode assembly is housed within the housing. The first tab assembly includes multiple first tabs and one second tab. The multiple first tabs extend from the first side, are respectively connected to the first electrode, are electrically connected to each other, and are housed within the housing. The second tab extends from the second side along a second direction, one end of which is connected to a first electrode, and the other end of which extends out of the housing. The second direction is perpendicular to the first direction.

[0046] In the aforementioned secondary battery, the second tab and the second side are located at the head of the secondary battery, while the first side and multiple first tabs are separated from the head of the secondary battery. The second tab and multiple first tabs are electrically connected through the first electrode plate. The second tab does not need to be bent to extend out of the casing from the second side, thereby reducing the space waste caused by the transfer welding at the head of the secondary battery. This is beneficial to improving the space utilization rate at the head of the secondary battery, and thus improving the energy density of the secondary battery.

[0047] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0048] Please refer to Figure 1. One embodiment of this application provides a secondary battery 100A. The secondary battery 100A refers to a battery that can be used again after being discharged by recharging to activate the active materials.

[0049] The secondary battery 100A includes an electrode assembly 10, a housing 70, and a first tab assembly 50. The electrode assembly 10 is used to convert chemical energy into electrical energy. The electrode assembly 10 is housed within the housing 70, which encapsulates the electrode assembly 10.

[0050] Please refer to Figures 1 and 2 together. The electrode assembly 10 includes a first electrode 20, a second electrode 30, and a separating membrane 40, with the separating membrane 40 disposed between the first electrode 20 and the second electrode 30. The electrode assembly 10 is formed by stacking the first electrode 20, the separating membrane 40, and the second electrode 30 along a first direction Z. The first direction Z is the thickness direction of the electrode assembly 10.

[0051] Viewed along the first direction Z, the electrode assembly 10 includes a plurality of sequentially connected side surfaces 11, wherein each side surface 11 is formed by the end face of the corresponding first electrode 20, the end face of the second electrode 30, and the end face of the separator 40. One side surface 11 is the first side surface 11A, and the other side surface 11 is the second side surface 11B.

[0052] The first tab assembly 50 includes a plurality of first tabs 51 and a second tab 52. The polarity of the plurality of first tabs 51 is the same as that of the second tab 52. The plurality of first tabs 51 extend from the first side 11A. The plurality of first tabs 51 are respectively connected to the first electrode plate 20, and the plurality of first tabs 51 are electrically connected to each other and housed within the housing 70. The plurality of first tabs 51 constitute a multi-tab structure of the electrode assembly 10, so that the electrode assembly 10 has low impedance and high rate charging performance.

[0053] In some embodiments, a plurality of first tabs 51 are stacked along a first direction Z to improve the stability of the connection between the plurality of first tabs 51. Specifically, the ends of the plurality of first tabs 51 away from the first electrode plate 20 are connected by welding.

[0054] It is understood that in other embodiments, the first electrode 51 is bent toward the adjacent first electrode 51, and the two adjacent first electrodes 51 are connected by welding.

[0055] The second tab 52 extends from the second side 11B along the second direction X. One end of the second tab 52 is connected to a first electrode 20, and the other end extends out of the housing 70 and is electrically connected to an external circuit, so that the plurality of first electrodes 20 in the electrode assembly 10 are electrically connected to the external circuit. The second direction X is perpendicular to the first direction Z. The position where the second tab 52 extends out of the housing 70 is at the head of the secondary battery 100A. The second tab 52 and the second side 11B are located at the head of the secondary battery 100A, and the second tab 52 does not need to be bent to extend out of the housing 70 from the second side 11B, which is beneficial to improving the utilization rate of the head space of the secondary battery 100A.

[0056] In the aforementioned secondary battery 100A, the second tab 52 and the second side 11B are located at the head of the secondary battery 100A. The first side 11A and multiple first tabs 51 are separated from the head of the secondary battery 100A. The second tab 52 and multiple first tabs 51 are electrically connected through the first electrode plate 20. The second tab 52 does not need to be bent to extend out of the housing 70 from the second side 11B, so as to reduce the space waste caused by the transfer welding at the head of the secondary battery. This is beneficial to improving the space utilization rate at the head of the secondary battery 100A, thereby improving the energy density of the secondary battery 100A.

[0057] Referring to Figure 1, in some embodiments, viewed along the first direction Z, the electrode assembly 10 includes four sequentially connected side surfaces 11, which together form an approximately rectangular shape. Optionally, the second direction X is the length direction of the electrode assembly 10, and the third direction Y is the width direction of the electrode assembly 10. The first direction Z, the second direction X, and the third direction Y are perpendicular to each other.

[0058] In some embodiments, the housing 70 is located away from the second tab 52 at the tail end of the secondary battery 100A. The first side 11A and the second side 11B are arranged opposite each other along the second direction X, so that the first side 11A and the plurality of first tabs 51 are located at the tail end of the secondary battery 100A, which facilitates the plurality of first tabs 51 to utilize the tail space of the secondary battery 100A and improve the energy density of the secondary battery 100A.

[0059] Specifically, when the casing 70 is a packaging bag, at the tail of the secondary battery 100A, the bottom wall of the packaging bag usually shrinks inward relative to the side seal of the packaging bag, resulting in wasted space. By setting multiple first tabs 51 between the electrode assembly 10 and the bottom wall of the packaging bag, the space of the bottom wall of the packaging bag shrinking inward is filled, reducing the wasted space at the tail of the secondary battery 100A and improving the energy density of the secondary battery 100A.

[0060] Please continue referring to Figure 2. In some embodiments, the first electrode 20 includes a first current collector 21 and a first active material layer 22. The first current collector 21 has the first active material layer 22 on at least one surface in the first direction Z. The first current collector 21 is used to collect current. Specifically, the first active material layer 22 is coated on the surface of the first current collector 21 by means of extrusion coating, transfer coating, spray coating, etc.

[0061] Optionally, the first current collector 21 is a metal current collector or a composite current collector.

[0062] In some embodiments, a plurality of first tabs 51 are integrally disposed with the first electrode 20 to improve the connection stability of the first tabs 51 and the corresponding first electrode 20, facilitate the reduction of internal resistance, and have the advantages of simple manufacturing process.

[0063] Specifically, in the process of manufacturing the first electrode 20, the first active material layer 22 is first coated on the first current collector 21, and an area where the first active material layer 22 is not coated is reserved at the edge of the first current collector 21 adjacent to the first side 11A. Then, the area where the first active material layer 22 is not coated is die-cut to form the first electrode tab 51.

[0064] Please refer to Figure 2. In some embodiments, multiple first tabs 51 are stacked along the first direction Z, and the multiple first tabs 51 are bent and disposed inside the housing 70 to reduce the space occupied by the first tabs 51 in the second direction X and improve the energy density of the secondary battery 100A.

[0065] Specifically, one end of a plurality of first tabs 51 is arranged at intervals along a first direction Z, and the other ends of the plurality of first tabs 51 converge to form a first part 51A and a second part 51B arranged sequentially. The first part 51A is located on one side of the first side surface 11A and is arranged opposite to the first side surface 11A along a second direction X. The second part 51B is bent away from the first side surface 11A relative to the first part 51A.

[0066] In some embodiments, the converged segments of the plurality of first tabs 51 are bent once to form a first portion 51A and a second portion 51B. Along the second direction X, the projections of the first portion 51A and the second portion 51B are both located within the projection range of the first side surface 11A, so as to reduce the space waste caused by the first tabs 51 protruding from the first side surface 11A in the first direction Z and improve the energy density of the secondary battery 100A.

[0067] Please refer to Figures 2 and 3 together. In some embodiments, along the third direction Y, the widths of the first electrode plate 20 and the first electrode tab 51 that are connected to each other are W1 and W2, respectively, with 0.1≤W2 / W1≤0.5, so as to improve the current carrying capacity of the first electrode tab 51 and facilitate the reservation of space on the second side 11B to accommodate another electrode tab assembly with the opposite polarity to the first electrode tab assembly 50, thereby reducing the risk of interference between the first electrode tab 51 and the other electrode tab assembly.

[0068] Optionally, W2 / W1 can be any one of the values ​​in the range of 0.1, 0.2, 0.3, 0.4, 0.5, and any other value within the range of W2 / W1≤0.5.

[0069] In some embodiments, the ratio of the length of each first tab 51 extending from the first side 11A in its extension direction to the thickness of the secondary battery 100A in the first direction Z is less than or equal to 2, so that the first part 51A and the second part 51B formed by the convergence of the multiple first tabs 51 after one bend do not exceed the first side 11A in the first direction Z, thereby improving the energy density of the secondary battery 100A.

[0070] Specifically, the thickness of the secondary battery 100A in the first direction Z is H1, and the length of the first tab 51 extending from the first side 11A in its extension direction is L1, where L1 / H1≤2, so that the first part 51A and the second part 51B formed by the convergence of multiple first tabs 51 after one bend do not exceed the first side 11A in the first direction Z, thereby improving the energy density of the secondary battery 100A.

[0071] Optionally, L1 / H1 can be any value within the range of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, and any other value within the range of L1 / H1≤2.

[0072] It should be noted that the lengths of the multiple first electrode tabs 51 may be the same or different. When the lengths of the multiple first electrode tabs 51 are different, L1 is the length of the longest first electrode tab 51 extending from the first side surface 11A. The length L1 of each first electrode tab 51 extending from the first side surface 11A is measured in the following way: the first electrode tab 51 is unfolded so that the thickness direction of the first electrode tab 51 is the same as the first direction Z. At this time, the extension direction of the first electrode tab 51 is the same as the second direction X. The length L1 of the first electrode tab 51 extending from the first side surface 11A in its extension direction can be obtained by measuring the length of the first electrode tab 51 in the second direction X.

[0073] It is understood that the number of bends of the converged sections of the multiple first tabs 51 is not limited to one. In other embodiments, the converged sections of the multiple first tabs 51 are bent multiple times to form multiple parts, so as to reduce the space waste caused by the first tabs 51 protruding from the first side 11A in the first direction Z and improve the energy density of the secondary battery 100A.

[0074] Optionally, the number of bends in the convergence section of the multiple first electrodes 51 can be 2, 3, 4, 5, etc.

[0075] Furthermore, a plurality of first tabs 51 are stacked along the first direction Z, and the ratio of the length of each first tab 51 extending from the first side 11A in its extending direction to the thickness of the secondary battery 100A in the first direction Z is 0.5 to 2, so that the ends of the plurality of first tabs 51 away from the first electrode 20 can be connected by welding. Specifically, 0.5≤L1 / H1≤2.

[0076] Please continue to refer to Figures 2 and 3. In some embodiments, the secondary battery 100A also includes a plurality of first insulating elements 61. At least one surface of the first electrode tab 51 in the first direction Z is provided with the first insulating element 61 to reduce the risk of short circuit caused by contact between the first electrode tab 51 and the adjacent second electrode 30.

[0077] Optionally, at least one surface of the first electrode tab 51 adjacent to the first electrode plate 20 in the first direction Z is provided with a first insulating member 61.

[0078] Optionally, the first electrode 51 has a first insulating element 61 on both surfaces in the first direction Z.

[0079] Optionally, the first insulating element 61 is an insulating coating. The insulating coating includes inorganic particles and an adhesive. The adhesive includes at least one of polyvinylidene fluoride, polyacrylonitrile, sodium carboxymethyl cellulose, polyacrylic acid, polyvinyl alcohol, or polytetrafluoroethylene. The inorganic particles may include, but are not limited to, at least one of silica (SiO2), boehmite (γ-AlOOH), diaspore (α-AlO(OH)), or alumina (Al2O3).

[0080] Referring to Figure 2, in some embodiments, the electrode assembly 10 includes a first surface 12 and a second surface 13, which are disposed opposite to each other along a first direction Z, with a plurality of side surfaces 11 located between the first surface 12 and the second surface 13. Specifically, the first surface 12 may be the surface of any one of the first electrode 20, the second electrode 30, and the separator 40 in the first direction Z. The second surface 13 may be the surface of any one of the first electrode 20, the second electrode 30, and the separator 40 in the first direction Z.

[0081] The secondary battery 100A also includes a second insulating member 62. One end of the second insulating member 62 is connected to the first surface 12, and the other end of the second insulating member 62 passes around the first side surface 11A and is connected to the second surface 13. The second insulating member 62 also covers a plurality of first tabs 51 to improve the structural stability of the plurality of first tabs 51 on the first side surface 11A, and to improve the insulation stability of the plurality of first tabs 51 with other structural members.

[0082] Please continue to refer to Figures 2 and 3. In some embodiments, multiple second tabs 52 are integrally disposed with the first electrode 20 to improve the connection stability between the second tabs 52 and the corresponding first electrode 20, facilitate the reduction of internal resistance, and have the advantages of simple manufacturing process.

[0083] Specifically, in the preparation process of the first electrode 20, the first active material layer 22 is first coated on the first current collector 21, and an area where the first active material layer 22 is not coated is reserved at the edge of the first current collector 21 adjacent to the second side 11B. Then, the area where the first active material layer 22 is not coated is die-cut to form the second electrode tab 52.

[0084] Referring to Figure 4, in some embodiments, the first active material layer 22 has a first groove 221 exposing the first current collector 21, and one end of the second tab 52 is located in the first groove 221 and connected to the first current collector 21. The second tab 52 shares the space in the first direction Z with the first active material layer 22 to improve the head space utilization of the secondary battery 100A, thereby improving the energy density of the secondary battery 100A.

[0085] Optionally, the first active material layer 22 is provided with a first groove 221 that exposes the first current collector 21 at the part near the second side surface 11B.

[0086] Optionally, the first groove 221 is formed by laser etching on the first active material layer 22.

[0087] Referring to Figure 5, in some embodiments, the first current collector 21 includes a first region 211 and a second region 212 connected together, with the first region 211 closer to the second side 11B than the second region 212. The first region 211 has no first active material layer 22 on either of its surfaces in the first direction Z, while the second region 212 has a first active material layer 22 on at least one surface in the first direction Z. One end of the second tab 52 is connected to the first region 211. The absence of the first active material layer 22 on either of the first surfaces of the first region 211 in the first direction Z facilitates connection between the second tab 52 and the first current collector 21.

[0088] Referring to Figure 2, in some embodiments, along the first direction Z, the thickness of the first current collector 21 of the first electrode 20 connecting the first tab 51 and the second tab 52 is D1, and the thickness of the first current collector 21 of the first electrode 20 connected to the first tab 51 but not connected to the second tab 52 is D2, where D1 / D2 > 1. When D1 / D2 ≤ 1, the thickness of the first current collector 21 of the first electrode 20 connecting the first tab 51 and the second tab 52 is small, resulting in weak current carrying capacity and affecting cycle performance. By limiting D1 / D2 > 1, the cycle performance of the secondary battery 100A is improved.

[0089] Furthermore, D1 / D2 ≤ 2.5. When D1 / D2 > 2.5, the thickness of the first current collector 21 of the first electrode 20 connecting the first tab 51 and the second tab 52 is relatively large, resulting in little improvement in cycle performance and a loss of energy density. By limiting D1 / D2 to ≤ 2.5, the energy density of the 100A secondary battery can be improved.

[0090] Optionally, D1 / D2 can be any one of the following values: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, and any other value within the range of 1 < D1 / D2 ≤ 2.5.

[0091] In some embodiments, the thickness of the second tab 52 is greater than the thickness of the first tab 51 to improve the current carrying capacity of the second tab 52, thereby improving the stability of the electrical connection between the second tab 52 and the external circuit.

[0092] Referring to Figure 6, in some embodiments, along the first direction Z, the two first electrode plates 20 located on the outermost sides of the electrode assembly 10 are respectively the first outer electrode plate 20A and the second outer electrode plate 20B. Along the first direction Z, the first outer electrode plate 20A is closer to the first surface 12 than the second outer electrode plate 20B, and the second outer electrode plate 20B is closer to the second surface 13 than the first outer electrode plate 20A. One end of the second electrode tab 52 is connected to either the first outer electrode plate 20A or the second outer electrode plate 20B to facilitate heat dissipation of the second electrode tab 52 and improve the safety of the secondary battery 100A.

[0093] Furthermore, during the fabrication of the electrode assembly 10, the thickness of the first current collector 21 of the first outer electrode 20A and the second outer electrode 20B is greater than the thickness of the first current collector 21 of the other first electrodes 20. This improves the structural stability of the first outer electrode 20A and the second outer electrode 20B, reducing the risk of the electrode assembly 10 being punctured and short-circuited under external force. Connecting one end of the second tab 52 to the first outer electrode 20A or the second outer electrode 20B also improves the overcurrent performance of the first current collector 21 connecting the first tab 51 and the second tab 52, which is beneficial for improving the cycle performance of the secondary battery 100A.

[0094] In some embodiments, the first electrode 20 is a positive electrode, and the first current collector 21 is made of aluminum foil. Correspondingly, the thickness of the first current collector 21 of the first outer electrode 20A and the second outer electrode 20B is greater than or equal to 10 μm.

[0095] In some embodiments, the first electrode 20 is a negative electrode, the first current collector 21 is made of copper foil, and the thickness of the first current collector 21 of the first outer electrode 20A and the second outer electrode 20B is greater than or equal to 6 μm.

[0096] Please refer to Figure 1. In some embodiments, the housing 70 is a packaging bag, and the housing 70 includes a main body 71 and an encapsulation part 72. Specifically, the main body 71 refers to the part where the encapsulation film is perforated, and the encapsulation part 72 refers to the part where the encapsulation film is folded and overlapped. The electrode assembly 10 and a plurality of first tabs 51 are accommodated in the main body 71. The main body 71 includes a first wall 711 disposed opposite to the second side 11B along the second direction X. The encapsulation part 72 includes a first encapsulation edge 721, which is connected to the first wall 711 and extends along the second direction X. The second tabs 52 extend from the first encapsulation edge 721 to facilitate electrical connection with an external circuit.

[0097] In some embodiments, the secondary battery 100A further includes tab adhesive 75, which is located on the first encapsulation edge 721 and covers the second tab 52 to improve the sealing stability of the first encapsulation edge 721.

[0098] Referring to Figures 1 and 7, in some embodiments, the secondary battery 100A further includes a second tab assembly 80. The polarity of the second tab assembly 80 is opposite to that of the first tab assembly 50. The second tab assembly includes a plurality of third tabs 81 and a fourth tab 82. The polarity of the third tabs 81 is the same as that of the fourth tab 82. The plurality of third tabs 81 extend from the first side 11A, and are respectively connected to the second electrode 30. The plurality of third tabs 81 are electrically connected to each other and housed within the housing 70. The fourth tab 82 extends from the second side 11B along the second direction X. One end of the fourth tab 82 is connected to a second electrode 30, and the other end of the fourth tab 82 extends out of the housing 70 and is electrically connected to an external circuit, so that the plurality of second electrodes 30 in the electrode assembly 10 are electrically connected to an external circuit. The fourth tab 82 and the second tab 52 share the head space of the secondary battery 100A, while multiple third tabs 81 and multiple first tabs 51 share the tail space of the secondary battery 100A. The fourth tab 82 and the multiple third tabs 81 are electrically connected through the second electrode plate 30. The fourth tab 82 does not need to be bent to extend from the second side 11B out of the housing 70, thereby reducing the space waste caused by the transfer welding at the head of the secondary battery. This helps to improve the utilization rate of the head space of the secondary battery 100A, and thus improves the energy density of the secondary battery 100A.

[0099] It is understandable that the structure of the third electrode 81 can refer to the structure of the first electrode 51, and the connection method between the third electrode 81 and the second electrode 30 can refer to the connection method between the first electrode 51 and the first electrode 20.

[0100] In some embodiments, the secondary battery 100A further includes a plurality of fourth insulating members 64, one end of which is connected to the first surface 12, and the other end of which bypasses the first side surface 11A and is connected to the second surface 13. The fourth insulating members 64 also cover a plurality of third tabs 81 to improve the structural stability of the plurality of third tabs 81 on the first side surface 11A and to improve the insulation stability of the plurality of third tabs 81 with other structural members.

[0101] Please continue referring to Figure 1. In some embodiments, when viewed along the first direction Z, the first reference line O extends along the second direction X and passes through the midpoint of the second side surface 11B in the second direction X. The first tab 51 and the third tab 81 are located on both sides of the first reference line O to reduce the risk of interference between the first tab 51 and the third tab 81.

[0102] In some embodiments, when viewed along the first direction Z, the second side 11B includes a first end 11A1 and a second end 11A2. A first tab 51 is located between the first end 11A1 and the first reference line O, and a third tab 81 is located between the second end 11A2 and the first reference line O. The second reference line E extends along the third direction Y and passes through the midpoint of the first tab 51 in the second direction X, and the third reference line F extends along the third direction Y and passes through the midpoint of the third tab 81 in the second direction X.

[0103] Along the second direction X, the distance between the second reference line E and the first reference line O is smaller than the distance between the second reference line E and the first end 11A1, so that the first tab 51 is close to the middle position of the first electrode 20, which is conducive to the uniform distribution of current in the first electrode 20, so that the first electrode 20 has a uniform current density, thereby improving the cycle performance of the secondary battery 100A.

[0104] Along the second direction X, the distance between the third reference line F and the first reference line O is smaller than the distance between the third reference line F and the second end 11A2, so that the third tab 81 is close to the middle position of the second electrode 30, which is conducive to the uniform distribution of current in the second electrode 30, so that the second electrode 30 has a uniform current density, thereby improving the cycle performance of the secondary battery 100A.

[0105] In some embodiments, the thickness of the secondary battery 100A along the first direction Z is H1, where H1 ≤ 2.5 mm, to meet the size requirements of ultra-thin batteries. Typically, ultra-thin cells have fewer electrode layers. The second tab 52 and the second side 11B are located at the head of the secondary battery 100A. The first side 11A and multiple first tabs 51 are separated from the head of the secondary battery 100A. The second tab 52 and multiple first tabs 51 are electrically connected via the first electrode 20. The second tab 52 does not need to be bent to extend from the second side 11B out of the housing 70, reducing space waste caused by transfer welding at the head of the secondary battery. This improves the head space utilization of the secondary battery 100A and enhances manufacturing yield and manufacturability.

[0106] Please refer to Figure 8. One embodiment of this application also provides a secondary battery 100B. The difference between the secondary battery 100B and the secondary battery 100A is that the positions of the first side 11A and the second side 11B are different. Correspondingly, the positions of the second electrode 52 and the third electrode 81 are also adjusted accordingly.

[0107] In some embodiments, the first side 11A and the second side 11B are arranged adjacent to each other so that the first side 11A and the plurality of first tabs 51 are located on the side of the secondary battery 100B, which facilitates the plurality of first tabs 51 to utilize the side space of the secondary battery 100B and improve the energy density of the secondary battery 100B.

[0108] Apart from the differences mentioned above, the parameters of secondary battery 100B and secondary battery 100A are roughly the same, and you can refer to the description of secondary battery 100A above.

[0109] Referring to Figure 9, an embodiment of this application also provides a secondary battery 100C. The difference between the secondary battery 100C and the secondary battery 100A lies in the shape of the electrode assembly 10. Correspondingly, the positions of the first tab assembly 50 and the second tab assembly 80 are also adapted.

[0110] In some embodiments, when viewed along the first direction Z, the electrode assembly 10 includes a plurality of sequentially connected side surfaces 11, and the plurality of side surfaces 11 are arranged to form a non-rectangular shape. Except for the second side surface 11B, the length of the first side surface 11A does not exceed the longest length of the other side surfaces 11, so that the first tab 51 is located on the short side of the electrode assembly 10, which helps to reduce the space waste generated on both sides of the first tab 51 and improve the energy density of the secondary battery 100C.

[0111] Specifically, the electrode assembly 10 includes six side surfaces 11 connected in sequence, which are arranged to form an L-shape.

[0112] It is understood that in some embodiments, the number of sides 11 can also be 3, 5, 7, 8, etc.

[0113] Apart from the differences mentioned above, the parameters of the secondary battery 100C and the secondary battery 100A are roughly the same. Please refer to the description of the secondary battery 100A above.

[0114] Referring to Figure 10, one embodiment of this application also provides an electronic device 200, which includes the secondary battery 100 in any of the above embodiments. Optionally, the electronic device 200 may be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc.

[0115] The specific implementation of the secondary battery 100 in the embodiments and comparative examples will be described below.

[0116] 1. Secondary battery energy density test:

[0117] The energy density test method for secondary batteries is to divide the energy value by the battery volume. The energy value is the product of the battery capacity and voltage. The battery volume is the product of the battery's initial length, width, and thickness, i.e., the length, width, and thickness before cycling, to reduce errors caused by thickness changes after cycling. The energy density obtained through this method is the initial energy density of the secondary battery. Battery thickness is measured using a PPG (Parallel Plate Gauge). Specifically, the battery is placed between two plates, and a certain pressure is applied, typically 650±50g. The distance between the two plates is then measured as the battery thickness.

[0118] 2. Secondary battery cycle performance test:

[0119] The battery cell was charged to 4.5V at 25℃ using a conventional 0.5C constant current, and then kept constant at 0.05C until the voltage was cut off. After resting for 5 minutes, it was discharged using a 0.5C constant current. After 1000 cycles, the capacity retention rate was calculated, which is the discharge capacity of the 1000th cycle divided by the initial capacity.

[0120] Example 1:

[0121] A secondary battery, with an initial thickness of 5.9 mm at 50% SOC, a length of 100 mm, and a width of 50 mm, is assembled as follows:

[0122] (1) Preparation of negative electrode sheet: The negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a weight percentage of 50 wt%, which is then stirred evenly. Foaming adhesive is first applied to a portion of the surface of a 6 μm thick copper foil for the negative electrode current collector. The slurry is then evenly coated onto one surface of the copper foil. Heating is used to remove the foaming adhesive, exposing a portion of the copper foil surface. The foil is then dried at 110 °C to obtain a negative electrode sheet with a single-sided coating of negative electrode active material. When preparing a double-sided coated negative electrode sheet, the above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided coating of negative electrode active material. The coated electrode sheet is then cold-pressed to a thickness of 105μm, and a first tab is die-cut on the copper foil exposed by the foam adhesive and a second tab is welded on. The first and second tabs are made of copper, and multiple first tabs are stacked along the thickness direction of the electrode assembly.

[0123] (2) Preparation of the positive electrode sheet: Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, and the mixture was stirred evenly. The slurry was uniformly coated on one surface of an aluminum foil and then dried at 90°C to obtain a positive electrode sheet with a single-sided coating of the positive active material. When preparing a double-sided coated positive electrode sheet, the above coating steps were repeated on the other surface of the aluminum foil. The coated electrode sheet was then cold-pressed to a thickness of 95 μm, and a third tab was die-cut in the blank area at the edge of the aluminum foil, and a fourth tab was welded on. The material of the third and fourth tabs was aluminum.

[0124] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0125] (4) Preparation of the isolation membrane: A 7-micron thick porous polyethylene polymer film was used as the isolation membrane.

[0126] (5) Electrode assembly preparation: The positive electrode, the separator and the negative electrode are stacked and arranged, and the convergence section of multiple first electrode tabs is bent once, and the convergence section of multiple third electrode tabs is bent once.

[0127] (6) Electrode assembly assembly: Place the punched aluminum-plastic film in the assembly fixture with the punched surface facing up, place the electrode assembly in the punch, and apply external force to press it tight. Then cover the electrode assembly with another punched aluminum-plastic film with the punched surface facing down, and heat seal the two aluminum-plastic films around their perimeter by hot pressing to obtain the assembled electrode assembly.

[0128] (7) Electrolyte injection and encapsulation: Electrolyte is injected into the assembled electrode assembly, and after vacuum encapsulation, standing, hot pressing formation, shaping and other processes, a secondary battery is obtained.

[0129] Comparative Example 1: The electrode assembly has multiple tabs on one side. After being folded, the tabs are soldered to conductive terminals and extend out of the housing. It should be noted that, except for the structure of the tabs, all other parameters of Comparative Example 1 are the same as those of Example 1.

[0130] Table 1

[0131] (Except for the parameters mentioned in Table 1, all other parameters in Examples 2-14 are the same as those in Example 1.)

[0132] As can be seen from Comparative Example 1 and Examples 1-15, by having multiple first tabs 51 extending from the first side 11A, each first tab 51 being connected to a first electrode 20, the multiple first tabs 51 being electrically connected to each other and housed within the housing 70, and a second tab 52 extending from the second side 11B along the second direction X, with one end of the second tab 52 connected to a first electrode 20 and the other end of the second tab 52 extending out of the housing 70, the energy density of the secondary battery can be improved.

[0133] As can be seen from Examples 1-6, limiting W2 / W1 to 0.5 can improve the cycle performance of the secondary battery. It should be noted that when W2 / W1 > 0.5, it will cause interference between the first tab 51 and the other tab assembly with opposite polarity, which is not conducive to welding the first tab 51 to the first electrode 20, and will also increase the risk of short circuit. Therefore, no examples with W2 / W1 > 0.5 are provided in Table 1.

[0134] As can be seen from Examples 6 and 7-10, the energy density of the secondary battery can be improved by limiting 0.5 ≤ L1 / H1 ≤ 2. It should be noted that when L1 / H1 < 0.5, multiple first tabs 51 cannot be stacked along the thickness direction of the secondary battery, that is, multiple first tabs 51 cannot be welded together. Therefore, no examples with L1 / H1 < 0.5 are provided in Table 1.

[0135] As shown in Examples 6 and 11-15, when the thickness of the first current collector 21 of the first electrode 20 connecting the first tab 51 and the second tab 52 is small, the current carrying capacity is weak, affecting the cycle performance. When the thickness of the first current collector 21 of the first electrode 20 connecting the first tab 51 and the second tab 52 is large, the improvement in cycle performance is not significant, and energy density is lost. By limiting 1 < D1 / D2 ≤ 2.5, the cycle performance and energy density of the 100A secondary battery can be improved.

[0136] In summary, in the aforementioned secondary batteries (100A, 100B, 100C), the second tab 52 and the second side 11B are located at the head of the secondary battery (100A, 100B, 100C). The first side 11A and multiple first tabs 51 are separated from the head of the secondary battery (100A, 100B, 100C). The second tab 52 and multiple first tabs 51 are electrically connected through the first electrode plate 20. The second tab 52 does not need to be bent to extend from the second side 11B out of the housing 70, thereby reducing the space waste caused by the transfer welding at the head of the secondary battery. This is beneficial to improving the space utilization rate at the head of the secondary battery (100A, 100B, 100C), and thus improving the energy density of the secondary battery (100A, 100B, 100C).

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: an electrode assembly comprising a first electrode sheet, a second electrode sheet, and a separator disposed between the first electrode sheet and the second electrode sheet, the electrode assembly being stacked by the first electrode sheet, the separator, and the second electrode sheet along a first direction, the first direction being a thickness direction of the electrode assembly, the electrode assembly comprising a plurality of side surfaces connected in sequence, one of the side surfaces being a first side surface and one of the side surfaces being a second side surface; a case in which the electrode assembly is accommodated; and a first tab assembly comprising a plurality of first tabs and a second tab, the plurality of first tabs extending from the first side surface, the plurality of first tabs being respectively connected to the first electrode sheet, the plurality of first tabs being electrically connected to each other and accommodated in the case, the second tab extending from the second side surface along a second direction, one end of the second tab being connected to one of the first electrode sheets, the other end of the second tab extending out of the case, the second direction being perpendicular to the first direction.

2. The secondary battery according to claim 1, wherein The plurality of first tabs are integrally provided with the first electrode sheet.

3. The secondary battery according to claim 1 or 2, characterized by, The first electrode sheet comprises a first current collector and a first active material layer, at least one surface of the first current collector in the first direction is provided with the first active material layer, the first active material layer is provided with a first groove exposing the first current collector, one end of the second tab is located in the first groove and connected to the first current collector.

4. The secondary battery according to claim 1 or 2, wherein The first electrode sheet comprises a first current collector and a first active material layer, the first current collector comprises a first region and a second region connected in sequence, the first region is closer to the second side surface than the second region, both surfaces of the first region in the first direction are not provided with the first active material layer, at least one surface of the second region in the first direction is provided with the first active material layer, one end of the second tab is connected to the first region.

5. The secondary battery according to claim 1 or 2, wherein The second tab is integrally provided with the first electrode sheet.

6. The secondary battery according to claim 1, wherein The first side surface and the second side surface are oppositely arranged along the second direction.

7. The secondary battery according to claim 1, wherein The first side surface and the second side surface are adjacently arranged.

8. The secondary battery according to claim 1, wherein The plurality of first tabs are stacked along the first direction, and the plurality of first tabs are folded and arranged in the case.

9. The secondary battery according to claim 1, wherein The first direction, the second direction, and a third direction are perpendicular to each other, along the third direction, the width of the first electrode sheet and the first tab connected to each other are W1 and W2 respectively, 0.1≤W2 / W1≤0.5; and / or, The ratio of the length of each first tab extending from the first side surface in the extension direction thereof to the thickness of the secondary battery in the first direction is less than or equal to 2.

10. The secondary battery according to claim 9, wherein The plurality of first tabs are stacked along the first direction, the ratio of the length of each first tab extending from the first side surface in the extension direction thereof to the thickness of the secondary battery in the first direction is 0.5 to 2.

11. The secondary battery according to claim 1, wherein The secondary battery further comprises a plurality of first insulating members, at least one surface of the first tab in the first direction is provided with the first insulating member.

12. The secondary battery according to claim 11, wherein The first insulation member is an insulation coating layer, the insulation coating layer comprises inorganic particles and a binder, the binder comprises at least one of polyvinylidene fluoride, polyacrylonitrile, sodium carboxymethyl cellulose, polyacrylic acid, polyvinyl alcohol or polytetrafluoroethylene, and the inorganic particles comprise at least one of silicon dioxide, boehmite, diaspore or aluminum oxide.

13. The secondary battery according to claim 1, wherein The electrode assembly comprises a first surface and a second surface, and the first surface and the second surface are oppositely arranged along the first direction. The secondary battery further comprises a second insulation member, one end of the second insulation member is connected to the first surface, the other end of the second insulation member passes around the first side surface and is connected to the second surface, and the second insulation member further covers the plurality of first tabs.

14. The secondary battery according to claim 1, wherein The first tab comprises a first current collector and a first active material layer, and at least one surface of the first current collector in the first direction is provided with the first active material layer. In the first direction, the thickness of the first current collector of the first tab connected to the first tab and the second tab is D1, the thickness of the first current collector of the first tab connected to the first tab and not connected to the second tab is D2, and D1 / D2>1.

15. The secondary battery according to claim 14, wherein D1 / D2≤2.

5.

16. The secondary battery according to claim 1, wherein The thickness of the second tab is greater than the thickness of the first tab.

17. The secondary battery according to claim 1, wherein In the first direction, the two first tabs located at the outermost two sides of the electrode assembly are respectively a first outer tab and a second outer tab, and one end of the second tab is connected to the first outer tab or the second outer tab.

18. The secondary battery according to claim 1, wherein The shell is a packaging bag, the shell comprises a main body part and a packaging part, the electrode assembly and the plurality of first tabs are accommodated in the main body part, the main body part comprises a first wall oppositely arranged with the second side surface along the second direction, and the packaging part comprises a first packaging edge, the first packaging edge is connected to the first wall, and the second tab extends from the first packaging edge.

19. The secondary battery according to claim 1, wherein The secondary battery further comprises a second tab assembly, the second tab assembly comprises a plurality of third tabs and a fourth tab, the plurality of third tabs extend from the first side surface, the plurality of third tabs are respectively connected to the second tabs, the plurality of third tabs are electrically connected to each other and accommodated in the shell, and one end of the fourth tab is connected to one of the second tabs, and the other end of the fourth tab extends out of the shell.

20. The secondary battery according to claim 1, wherein In the first direction, the thickness of the secondary battery is H1, and H1≤2.5mm.

21. An electronic device, comprising: The electronic device comprises the secondary battery according to any one of claims 1 to 20.

Images