Battery cell, battery device, and electric device
Patent Information
- Application Number
- CN202510472406.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-15
- Publication Date
- 2026-10-23
AI Technical Summary
[0038]上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
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Figure CN122968374A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery technology, and in particular to a battery cell, a battery device, and an electrical device. Background Technology
[0002] In recent years, with the rapid development of new energy technologies, new energy vehicles have been increasingly widely used and are gradually replacing traditional fuel vehicles, becoming one of the mainstream modes of transportation. As the power source of new energy vehicles, the power battery is one of their core components; therefore, the safety performance of the power battery has become a key focus of attention.
[0003] In the development of battery technology, improving the reliability of individual battery cells is a key research direction. Summary of the Invention
[0004] This application provides a battery cell, a battery device, and an electrical device that can improve the reliability of the battery cell.
[0005] In a first aspect, embodiments of this application provide a battery cell, which includes a housing and an electrode assembly disposed in the housing. The electrode assembly includes a negative electrode and a positive electrode. The positive and negative electrode are wound together. The electrode assembly includes a flat region and a corner region. The positive electrode includes a positive current collector and a positive active material layer disposed on the surface of the positive current collector. The positive current collector includes a positive electrode substrate and a first conductive electron layer disposed at least on the concave surface of the positive electrode substrate. At least a portion of the first conductive electron layer is located in the corner region, and at least a portion of the positive active material layer is disposed on the concave surface of the positive electrode substrate and covers the first conductive electron layer.
[0006] In the above scheme, by setting a first conductive layer on at least the concave surface of the positive electrode substrate, and at least a portion of the first conductive layer is located in the corner region, the first conductive layer can not only improve the conductivity of the positive electrode sheet, but also reduce the proportion of the positive active material layer on the concave surface of the positive electrode substrate in the corner region, thereby reducing the lithium plating phenomenon in the corner region of the electrode assembly and improving the reliability of the battery cell.
[0007] In some embodiments, the positive current collector further includes a second conductive layer disposed on the surface of the positive electrode substrate, wherein the dimension of the first conductive layer along a first direction is greater than the dimension of the second conductive layer along the first direction, the first direction being the thickness direction of the positive electrode substrate, and at least a portion of the second conductive layer is located in a flat region.
[0008] In the above scheme, the thickness of the first conductive layer is greater than the thickness of the second conductive layer, and the density of the positive electrode active material in the corner region is lower than that in the straight region, which can reduce lithium plating in the corner region of the electrode assembly. Moreover, by setting at least part of the second conductive layer in the straight region, the conductivity of the positive electrode can be further increased.
[0009] In some embodiments, the second conductive layer is disposed on the concave surface of the positive electrode substrate, and the first conductive layer and the second conductive layer are respectively arranged along a second direction, which is the length direction of the positive electrode substrate.
[0010] In the above scheme, by placing the first conductive layer and the second conductive layer on the same side of the positive electrode substrate, the process preparation is facilitated and the production efficiency is improved.
[0011] In some embodiments, the second conductive layer includes a first conductive portion and a second conductive portion. The first conductive portion is disposed on the concave surface of the positive electrode substrate. The first conductive layer and the first conductive portion are respectively arranged along a second direction, which is the length direction of the positive electrode substrate. The second conductive portion is disposed on the convex surface of the positive electrode substrate.
[0012] In the above scheme, by providing a first conductive part and a second conductive part on the concave surface and the convex surface of the positive electrode substrate respectively, the conductivity of the positive electrode sheet is further increased.
[0013] In some embodiments, the second conductive portion covers the entire surface of the convex outer surface of the positive electrode substrate.
[0014] In the above scheme, by providing a second conductive part on the entire convex surface of the positive electrode substrate, the conductivity of the positive electrode sheet is further improved.
[0015] In some embodiments, the material of the first conductive layer is the same as the material of the second conductive layer.
[0016] In the above scheme, by setting the materials of the first conductive layer and the second conductive layer to be the same, the process difficulty and cost can be reduced.
[0017] In some embodiments, the dimension of the second conductive layer along the first direction is D1, and D1 satisfies the following condition: 0.5μm≤D1≤5μm.
[0018] In the above scheme, by limiting the thickness of the second conductive layer to a suitable range, the conductivity of the positive electrode sheet can be improved without taking up too much space of the positive electrode active material layer.
[0019] In some embodiments, D1 satisfies the following condition: 0.5μm≤D1≤3μm.
[0020] In the above scheme, by further reducing the thickness range of the second conductive electronic layer, the impact on the positive electrode active material layer can be further reduced, that is, the impact on the energy density of the battery cell can be reduced.
[0021] In some embodiments, the material of the first conductive layer includes at least one of conductive carbon black, acetylene black, conductive carbon fiber, carbon nanotubes or graphene, which does not produce side reactions, does not have an adverse effect on the electrode assembly, and has good conductivity and light weight.
[0022] In some embodiments, the dimension of the first conductive electronic layer along the first direction is D2, and the dimension of the positive electrode sheet along the first direction is D3. D2 and D3 satisfy the following condition: 0.1≤D2 / D3≤0.7, where the first direction is the thickness direction of the positive electrode substrate.
[0023] In the above scheme, by limiting the thickness ratio of the first conductive layer to the positive electrode sheet within a suitable range, the conductivity of the positive electrode sheet can be improved and the lithium plating phenomenon can be reduced, without occupying too much space of the positive electrode active material layer.
[0024] In some embodiments, D2 and D3 satisfy the following condition: 0.25 ≤ D2 / D3 ≤ 0.4.
[0025] In the above scheme, by further limiting the thickness ratio range of the first conductive layer and the positive electrode sheet, the conductivity of the positive electrode sheet is further improved, the lithium plating phenomenon is reduced, and the impact on the positive electrode active material layer is further reduced, that is, the impact on the energy density of the battery cell is reduced.
[0026] In some embodiments, the dimension of the first conductive electronic layer along the second direction is L, where the second direction is the length direction of the positive electrode substrate, and L satisfies the following condition: 5mm≤L≤100mm.
[0027] In the above scheme, by limiting the length of the first conductive electronic layer to a suitable range, it is possible to ensure to a certain extent that the first conductive electronic layer can reduce the lithium plating phenomenon in the corner area of the electrode assembly.
[0028] In some embodiments, L satisfies the following condition: 10mm≤L≤20mm.
[0029] In the above scheme, by further reducing the length range of the first conductive electron layer, the lithium plating phenomenon in the corner area of the electrode assembly can be further reduced, and the impact on the energy density of the battery cell can be reduced.
[0030] In some embodiments, the side of the positive electrode active material layer facing the winding center of the electrode assembly is a flat surface.
[0031] In the above scheme, by setting the side of the positive electrode active material layer facing the winding center of the electrode assembly as a flat surface, the thickness variation of the positive electrode active material layer is reduced, so that lithium ions are more evenly distributed during the insertion / extraction process.
[0032] In some embodiments, the positive electrode active material layer includes a first positive electrode active portion and a second positive electrode active portion. The first positive electrode active portion is disposed on the concave surface of the positive electrode substrate and covers the first conductive electronic layer, and the second positive electrode active portion is disposed on the convex surface of the positive electrode substrate.
[0033] In the above scheme, by coating the inner concave surface and outer convex surface of the positive electrode substrate with active material, the energy density of the battery cell can be improved.
[0034] In some embodiments, the corner region includes multiple positive electrode corner portions of the positive electrode sheet, and at least two positive electrode corner portions are provided with a first conductive electron layer.
[0035] In the above scheme, by setting a first conductive electron layer at at least two positive electrode corners, the lithium plating phenomenon in the corner region can be further reduced.
[0036] Secondly, embodiments of this application also provide a battery device, including the battery cell provided in any of the above embodiments.
[0037] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery device, which is used to provide electrical energy.
[0038] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description
[0039] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0040] Figure 1 This is a schematic diagram of the vehicle structure according to some embodiments of this application;
[0041] Figure 2 Exploded views of battery devices according to some embodiments of this application;
[0042] Figure 3 This is a schematic diagram of the structure of a battery module according to some embodiments of this application;
[0043] Figure 4 This is an exploded structural diagram of a battery cell according to some embodiments of this application;
[0044] Figure 5These are schematic diagrams of the structure of electrode assemblies according to some embodiments of this application;
[0045] Figure 6 This is a partial structural schematic diagram of the corner region of the electrode assembly in some embodiments of this application;
[0046] Figure 7 This is a cross-sectional schematic diagram of the positive current collector in some embodiments of this application;
[0047] Figure 8 This is a cross-sectional schematic diagram of the positive current collector in some other embodiments of this application;
[0048] Figure 9 This is a cross-sectional schematic diagram of the positive current collector according to some embodiments of this application;
[0049] Figure 10 This is a cross-sectional schematic diagram of the positive electrode sheet in some embodiments of this application;
[0050] Figure 11 This is a partial structural schematic diagram of the corner region of the electrode assembly in some other embodiments of this application;
[0051] Figure 12 This is a partial structural schematic diagram of the corner region of the inner ring area of the electrode assembly in some embodiments of this application.
[0052] Explanation of reference numerals in the attached figures:
[0053] 1000, Vehicle; 100, Battery unit; 200, Controller; 300, Motor; 10, Top cover; 30, Housing; 400, Battery module; 20, Battery cell; 22, Housing; 21, End cap; 23, Electrode assembly; 26, Electrode terminal; 40, Negative electrode; 50, Positive electrode; 51, Positive current collector; 51a, Concave surface; 51b, Convex surface; 511, Positive electrode substrate; 512, First conductive layer; 513, Second conductive layer; 514, First conductive part; 515, Second conductive part; 52, Positive active material layer; 521, First positive active part; 522, Second positive active part; 61, Flat area; 62, Corner area; 621, Positive corner part; 70, Separator; X, First direction; Y, Second direction. Detailed Implementation
[0054] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.
[0055] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.
[0056] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.
[0057] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0058] In this application, the battery cell may include a lithium-ion secondary battery cell, a lithium-ion primary battery cell, a lithium-sulfur battery cell, a sodium-lithium-ion battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, etc., and the embodiments of this application are not limited to this. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, cuboid / square battery cells, and pouch battery cells, and the embodiments of this application are not limited to this.
[0059] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.
[0060] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.
[0061] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.
[0062] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.
[0063] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.
[0064] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.
[0065] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.
[0066] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.
[0067] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.
[0068] Please refer to Figure 2 , Figure 2 This is an exploded view of the apparatus provided in some embodiments of this application. The battery device 100 includes a battery housing and battery cells 20. In some embodiments, the battery housing may include a top cover 10 and a housing 30, with the top cover 10 and housing 30 covering each other, and the top cover 10 and housing 30 together defining a receiving cavity for receiving the battery cells 20. The housing 30 may be a hollow structure with one end open, and the top cover 10 may be a plate-like structure, with the top cover 10 covering the open side of the housing 30 so that the top cover 10 and housing 30 together define the receiving cavity; the top cover 10 and housing 30 may also be hollow structures with one side open, with the open side of the top cover 10 covering the open side of the housing 30. Of course, the battery housing formed by the top cover 10 and housing 30 can be of various shapes, such as a cylinder, a cuboid, etc.
[0069] Figure 3 This is a schematic diagram of the structure of a battery module according to some embodiments of this application. In the battery device 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole assembly of multiple battery cells 20 is housed in a housing. Of course, the battery device 100 can also be in the form of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module 400, and then multiple battery modules 400 are connected in series, parallel, or in a mixed manner to form a whole and housed in a housing. The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component for realizing the electrical connection between multiple battery cells 20.
[0070] Each battery cell 20 can be a secondary battery cell or a primary battery cell; it can also be a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.
[0071] Figure 4This is an exploded structural diagram of a battery cell according to some embodiments of this application. The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit it. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is less prone to deformation under pressure and impact, enabling the battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 26 can be provided on the end cap 21. The electrode terminals 26 can be used to electrically connect with the electrode assembly 23 for outputting or inputting electrical energy into the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application does not impose special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.
[0072] In wound-type battery cells, the electrode assembly exhibits a situation where the radius of the positive electrode is larger than that of the adjacent negative electrode in the corner region. Furthermore, in the area where the concave surface of the positive electrode faces the convex surface of the negative electrode, the arc length of the positive electrode in the corner region is greater than that of the negative electrode. This results in a situation where CB < 1 in the corner region, leading to insufficient lithium intercalation capability of the negative electrode. Lithium ions extracted from the positive electrode cannot quickly and completely embed into the negative electrode. Instead, lithium ions at the interface between the negative electrode and the electrolyte directly gain electrons and undergo lithium deposition on the surface of the negative electrode. This lithium deposition causes capacity decay in the battery cell, leading to safety issues such as internal short circuits and reducing the reliability of the battery cell.
[0073] To address the aforementioned technical problems, this application provides a battery cell comprising a housing and an electrode assembly disposed within the housing. The electrode assembly includes a negative electrode and a positive electrode. The positive and negative electrode are wound together. The electrode assembly includes a flat region and a corner region. The positive electrode includes a positive current collector and a positive active material layer disposed on the surface of the positive current collector. The positive current collector includes a positive electrode substrate and a first conductive layer disposed at least on the concave surface of the positive electrode substrate. At least a portion of the first conductive layer is located in the corner region, and at least a portion of the positive active material layer is disposed on the concave surface of the positive electrode substrate and covers the first conductive layer.
[0074] In the above scheme, by setting a first conductive layer on at least the concave surface of the positive electrode substrate, and at least a portion of the first conductive layer is located in the corner region, the first conductive layer can not only improve the conductivity of the positive electrode sheet, but also reduce the proportion of the positive active material layer on the concave surface of the positive electrode substrate in the corner region, thereby reducing the lithium plating phenomenon in the corner region of the electrode assembly and improving the reliability of the battery cell.
[0075] Figure 5 These are schematic diagrams of the structure of electrode assemblies according to some embodiments of this application; Figure 6 This is a partial structural schematic diagram of the corner region of the electrode assembly in some embodiments of this application; Figure 7 This is a cross-sectional schematic diagram of the positive current collector in some embodiments of this application.
[0076] Please refer to the following: Figures 5-7 In a first aspect, embodiments of this application provide a battery cell 20, which includes a housing 22 and an electrode assembly 23 disposed in the housing 22. The electrode assembly 23 includes a negative electrode 40 and a positive electrode 50. The positive electrode 50 and the negative electrode 40 are wound together. The electrode assembly 23 includes a straight region 61 and a corner region 62. The positive electrode 50 includes a positive current collector 51 and a positive active material layer 52 disposed on the surface of the positive current collector 51. The positive current collector 51 includes a positive electrode substrate 511 and a first conductive layer 512 disposed at least on the concave surface 51a of the positive electrode substrate 511. At least a portion of the first conductive layer 512 is located in the corner region 62, and at least a portion of the positive active material layer 52 is disposed on the concave surface 51a of the positive electrode substrate 511 and covers the first conductive layer 512.
[0077] Under normal circumstances, during the charging and discharging process of a lithium-ion battery, lithium ions are transported in the electrolyte through chemical reactions between the positive and negative electrodes. However, if the radius of curvature of the bent portion of the electrode assembly 23 is small and stress is concentrated, the active material layer of the bent portion is prone to detachment, exposing the current collector. Lithium ions in the electrolyte will then accumulate on the surface of the negative electrode, exceeding its surface capacity. At this point, lithium ions will begin to precipitate on the negative electrode surface, forming a layer of solid metallic lithium, a phenomenon known as lithium plating.
[0078] A separator 70 can be placed between the positive electrode 50 and the negative electrode 40. The main function of the separator 70 is to prevent direct electron flow between the two electrodes while allowing particle transport. The separator 70 is a thin film that prevents short circuits between the positive and negative electrodes, ensuring normal battery operation. Specifically, the separator 70 is an electronic insulator that blocks direct electron flow between the positive and negative electrodes, thus preventing internal circuit short circuits, direct energy dissipation, and premature battery failure. Although the separator 70 blocks electron flow, it allows ion transport between the positive and negative electrodes. This is because the battery's operating principle involves the movement of ions in the electrolyte, from the positive electrode through the electrolyte to the negative electrode to complete the electrochemical reaction. The separator 70 provides a channel for ion transport between the positive and negative electrodes, promoting the battery's charging and discharging process.
[0079] The negative electrode 40, the separator 70, and the positive electrode 50 can be stacked sequentially and then formed into a wound electrode assembly 23 through a winding process. The winding structure is a multi-turn structure, with the innermost turns being the inner ring region and the outermost turns being the outer ring region. It should be noted that the convex surface 51b faces the outer ring region, and the concave surface 51a faces the inner ring region.
[0080] The positive electrode substrate 511 can be made of pure aluminum foil or metal polymer composite aluminum foil, the first conductive layer 512 can be made of carbon material or other conductive material, and the positive electrode active material layer 52 can be made of transition metal oxide or phosphate.
[0081] Analyzing the principle of lithium deposition on electrodes, thermodynamically, the capacity of the positive electrode 50 is greater than that of the negative electrode 40. The negative electrode 40 has insufficient lithium intercalation capability, meaning the lithium extracted from the positive electrode 50 cannot be completely embedded into the negative electrode 40, leading to lithium deposition on the surface. Analysis of the reason for the low CB value (CB1) at the corner of electrode assembly 23: The concave surface 51a of the positive electrode 50 at the corner of the wound electrode assembly 23 corresponds to the convex surface 51b of the negative electrode 40. Therefore, the arc length L1 of the positive electrode 50 in the corner region 62 is greater than the corresponding arc length L2 of the negative electrode 40. Assuming the designed CB value at the corner region 62 of electrode assembly 23 is CB0, then at the corner... Therefore, CB1 < CB0. When CB1 < 1, there is a theoretical risk of lithium plating. Therefore, it is necessary to increase CB0 at the corner to make... A value greater than 1 theoretically prevents lithium deposition. This solution reduces the areal density of the active material in the positive electrode 50 on the concave surface 51a of the corner region 62, increasing the CB0 at the corner to achieve the theoretically non-lithium deposition effect. The CB value (Cell Balance) is a key parameter in lithium battery design, used to describe the margin of the negative electrode capacity relative to the positive electrode capacity under the same stage and conditions.
[0082] In the above scheme, by providing a first conductive layer 512 at least on the concave surface 51a of the positive electrode substrate 511, and at least a portion of the first conductive layer 512 is located in the corner region 62, the first conductive layer 512 can not only improve the conductivity of the positive electrode sheet 50, but also reduce the proportion of the positive active material layer 52 on the concave surface 51a of the positive electrode substrate 511 in the corner region 62, thereby reducing the lithium plating phenomenon in the corner region 62 of the electrode assembly 23 and improving the reliability of the battery cell 20.
[0083] Figure 8 This is a cross-sectional schematic diagram of the positive current collector in some other embodiments of this application.
[0084] like Figure 8 As shown, in some embodiments, the positive current collector 51 further includes a second conductive layer 513 disposed on the surface of the positive electrode substrate 511. The size of the first conductive layer 512 along the first direction X is larger than the size of the second conductive layer 513 along the first direction X. The first direction X is the thickness direction of the positive electrode substrate 511. At least a portion of the second conductive layer 513 is located in the flat region 61.
[0085] The second conductive layer 513 can be provided only on the concave surface 51a or the convex surface 51b of the positive electrode substrate 511, or the second conductive layer 513 can be provided on both the concave surface 51a and the convex surface 51b of the positive electrode substrate 511. The second conductive layer 513 can be located only in the flat region 61, or the second conductive layer 513 can be provided in both the flat region 61 and the corner region 62.
[0086] In the above scheme, the thickness of the first conductive layer 512 is greater than the thickness of the second conductive layer 513, and the density of the positive electrode active material in the corner region 62 is lower than that in the straight region 61, which can reduce the lithium plating phenomenon in the corner region 62 of the electrode assembly 23. Moreover, by disposing at least a portion of the second conductive layer 513 in the straight region 61, the conductivity of the positive electrode 50 can be further increased.
[0087] In some embodiments, the second conductive layer 513 is disposed on the concave surface 51a of the positive electrode substrate 511, and the first conductive layer 512 and the second conductive layer 513 are respectively arranged along the second direction Y, where the second direction Y is the length direction of the positive electrode substrate 511.
[0088] The first conductive layer 512 and the second conductive layer 513 can be continuously arranged along the first direction X, with the first conductive layer 512 located in the corner region 62 and the second conductive layer 513 located in the straight region 61.
[0089] In the above scheme, by placing the first conductive layer 512 and the second conductive layer 513 on the same side of the positive electrode substrate 511, the process preparation is facilitated and the production efficiency is improved.
[0090] Figure 9 This is a cross-sectional schematic diagram of the positive current collector in some embodiments of this application.
[0091] like Figure 9 As shown, in some embodiments, the second conductive sublayer 513 includes a first conductive portion 514 and a second conductive portion 515. The first conductive portion 514 is disposed on the concave surface 51a of the positive electrode substrate 511. The first conductive sublayer 512 and the first conductive portion 514 are respectively arranged along the second direction Y, where the second direction Y is the length direction of the positive electrode substrate 511. The second conductive portion 515 is disposed on the convex surface 51b of the positive electrode substrate 511.
[0092] The first conductive layer 512 and the first conductive part 514 can be continuously disposed along the first direction X, with the first conductive layer 512 located in the corner region 62 and the first conductive part 514 located in the straight region 61.
[0093] The second conductive portion 515 can cover the entire convex surface 51b of the positive electrode substrate 511. Part of the second conductive portion 515 is located in the corner region 62, and another part is located in the straight region 61.
[0094] In the above scheme, by providing a first conductive part 514 and a second conductive part 515 on the concave surface 51a and the convex surface 51b of the positive electrode substrate 511 respectively, the conductivity of the positive electrode sheet 50 is further increased.
[0095] In some embodiments, the second conductive portion 515 covers the entire surface of the outer convex surface 51b of the positive electrode substrate 511.
[0096] In the above scheme, by providing a second conductive part 515 on the entire convex surface 51b of the positive electrode substrate 511, the conductivity of the positive electrode sheet 50 is further improved.
[0097] In some embodiments, the material of the first conductive layer 512 is the same as the material of the second conductive layer 513.
[0098] In the above scheme, by setting the materials of the first conductive layer 512 and the second conductive layer 513 to be the same, the process difficulty and cost can be reduced.
[0099] In some embodiments, the second conductive sublayer 513 has a dimension D1 along the first direction X, and D1 satisfies the following condition: 0.5μm≤D1≤5μm.
[0100] The dimension D1 of the second conductive sublayer 513 along the first direction X can be any value from 0.5μm to 5μm. For example, the dimension of the second conductive sublayer 513 along the first direction X can be 0.5μm, 1μm, 2μm, 3μm, 4μm or 5μm.
[0101] In the above scheme, by limiting the thickness of the second conductive layer 513 to a suitable range, the conductivity of the positive electrode 50 can be improved without occupying too much space of the positive electrode active material layer 52.
[0102] In some embodiments, D1 satisfies the following condition: 0.5μm≤D1≤3μm.
[0103] The dimension D1 of the second conductive sublayer 513 along the first direction X can be any value between 0.5 μm and 3 μm. For example, the dimension of the second conductive sublayer 513 along the first direction X can be 0.5 μm, 0.6 μm, 0.8 μm, 1.2 μm, 2.5 μm, or 3 μm.
[0104] In the above scheme, by further reducing the thickness range of the second conductive electronic layer 513, the impact on the positive electrode active material layer 52 can be further reduced, that is, the impact on the energy density of the battery cell 20 can be reduced.
[0105] In some embodiments, the material of the first conductive layer 512 includes at least one of conductive carbon black, acetylene black, conductive carbon fiber, carbon nanotubes, or graphene.
[0106] The first conductive electronic layer 512 may also include an adhesive to improve the adhesion between the first conductive electronic layer 512 and the positive electrode substrate 511.
[0107] Conductive carbon black has a small particle size and a large specific surface area, making it easy to mix with adhesives. Acetylene black has good electrical conductivity, maintains structural integrity at high temperatures, and exhibits good stability. Conductive carbon fiber has good mechanical properties, and the interwoven fibers form a conductive network, reducing contact resistance. Carbon nanotubes have good electrical conductivity and are lightweight. Graphene can rapidly dissipate heat during charging and discharging, reducing local temperature rise and suppressing the volume expansion of active materials.
[0108] In the above scheme, by using at least one of conductive carbon black, acetylene black, conductive carbon fiber, carbon nanotube or graphene as the material of the first conductive layer 512, no side reactions will be generated, no adverse effects will be produced on the electrode assembly 23, and the conductivity is good and the weight is light.
[0109] Figure 10 This is a cross-sectional schematic diagram of the positive electrode sheet in some embodiments of this application.
[0110] like Figure 10 As shown, in some embodiments, the dimension of the first conductive electronic layer 512 along the first direction X is D2, and the dimension of the positive electrode 50 along the first direction X is D3. D2 and D3 satisfy the following condition: 0.1≤D2 / D3≤0.7, where the first direction X is the thickness direction of the positive electrode substrate 511.
[0111] The dimension of the first conductive layer 512 along the first direction X is the thickness of the first conductive layer 512, and the length of the positive electrode 50 along the first direction X is the thickness of the positive electrode 50. The ratio D2 / D3 of the dimension of the first conductive layer 512 along the first direction X to the dimension of the positive electrode 50 along the first direction X can be any value between 0.1 and 0.7. For example, the ratio D2 / D3 of the dimension of the first conductive layer 512 along the first direction X to the dimension of the positive electrode 50 along the first direction X can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7.
[0112] In the above scheme, by limiting the thickness ratio of the first conductive layer 512 to the positive electrode 50 within a suitable range, the conductivity of the positive electrode 50 can be improved and the lithium plating phenomenon can be reduced, without occupying too much space of the positive active material layer 52.
[0113] In some embodiments, D2 and D3 satisfy the following condition: 0.25 ≤ D2 / D3 ≤ 0.4.
[0114] The ratio D2 / D3 of the dimension of the first conductive layer 512 along the first direction X to the dimension of the positive electrode 50 along the first direction X can be any value between 0.25 and 0.4. For example, the ratio D2 / D3 of the first conductive layer 512 along the first direction X to the dimension of the positive electrode 50 along the first direction X can be 0.25, 0.27, 0.29, 0.32, 0.35, 0.38, or 0.4.
[0115] In the above scheme, by further limiting the thickness ratio range of the first conductive layer 512 and the positive electrode 50, the conductivity of the positive electrode 50 is further improved, the lithium plating phenomenon is reduced, and the impact on the positive active material layer 52 is further reduced, that is, the impact on the energy density of the battery cell 20 is reduced.
[0116] In some embodiments, the dimension of the first conductive layer 512 along the second direction Y is L, where the second direction Y is the length direction of the positive electrode substrate 511, and L satisfies the following condition: 5mm≤L≤100mm.
[0117] The dimension L of the first conductive layer 512 along the second direction Y is the length of the first conductive layer 512. The dimension L of the first conductive layer 512 along the second direction Y can be any value in the range of 5mm-100mm. For example, the dimension L of the first conductive layer 512 along the second direction Y can be 5mm, 10mm, or 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, or 100mm.
[0118] In the above scheme, by limiting the length of the first conductive layer 512 to a suitable range, it can be ensured to a certain extent that the first conductive layer 512 can reduce the lithium plating phenomenon in the corner region 62 of the electrode assembly 23.
[0119] In some embodiments, L satisfies the following condition: 10mm≤L≤20mm.
[0120] The dimension L of the first conductive layer 512 along the second direction Y is the length of the first conductive layer 512. The dimension L of the first conductive layer 512 along the second direction Y can be any value in the range of 5mm-100mm. For example, the dimension L of the first conductive layer 512 along the second direction Y can be 5mm, 10mm, or 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, or 100mm.
[0121] In the above scheme, by further reducing the length range of the first conductive electron layer 512, the lithium plating phenomenon in the corner region 62 of the electrode assembly 23 can be further reduced, and the impact on the energy density of the battery cell 20 can be reduced.
[0122] In some embodiments, the side of the positive electrode active material layer 52 facing the winding center of the electrode assembly 23 is a flat surface.
[0123] A positive electrode active material is coated on the concave surface 51a of the positive electrode substrate 511, and the positive electrode active material layer 52 formed after curing has a flat surface on the side opposite to the positive electrode sheet 50. That is, the total thickness of the first conductive electronic layer 512 and the positive electrode active material layer 52 above it is equal to the total thickness of the first conductive part 514 and the positive electrode active material layer 52 above it.
[0124] In the above scheme, by setting the side of the positive electrode active material layer 52 facing the winding center of the electrode assembly 23 as a flat surface, the thickness variation of the positive electrode active material layer 52 is reduced, so that lithium ions are more evenly distributed during the insertion / extraction process.
[0125] In some embodiments, the positive electrode active material layer 52 includes a first positive electrode active portion 521 and a second positive electrode active portion 522. The first positive electrode active portion 521 is disposed on the concave surface 51a of the positive electrode substrate 511 and covers the first conductive electronic layer 512. The second positive electrode active portion 522 is disposed on the convex surface 51b of the positive electrode substrate 511.
[0126] In other words, by coating both surfaces of the positive electrode substrate 511 with positive electrode active material, the energy density of the battery cell 20 can be improved by coating both the concave surface 51a and the convex surface 51b of the positive electrode substrate 511 with active material.
[0127] Figure 11This is a partial structural schematic diagram of the corner region of the electrode assembly in some other embodiments of this application; Figure 12 This is a partial structural schematic diagram of the corner region of the inner ring area of the electrode assembly in some embodiments of this application.
[0128] Please refer to the following: Figure 11 and Figure 12 In some embodiments, the corner region 62 includes a plurality of positive electrode corner portions 621 of the positive electrode plate 50, and at least two positive electrode corner portions 621 are provided with a first conductive electron layer 512.
[0129] For example, the first conductive layer 512 can be provided at the two innermost positive electrode corners 621, or at all positive electrode corners 621. It is understood that since the radius of the positive electrode corners 621 in the outer region is larger than that in the inner region, the spacing between two adjacent first conductive layers 512 gradually increases along the second direction Y of the positive electrode sheet 50, from the inner region to the outer region.
[0130] In the above scheme, by providing a first conductive layer 512 at at least two positive electrode corners 621, the lithium plating phenomenon in the corner region 62 can be further reduced.
[0131] Secondly, embodiments of this application also provide a battery device, including the battery cell 20 provided in any of the above embodiments.
[0132] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery device, which is used to provide electrical energy.
[0133] According to some embodiments of this application, this application provides a battery cell 20, which includes a housing 22 and an electrode assembly 23 disposed in the housing 22. The electrode assembly 23 includes a negative electrode 40 and a positive electrode 50. The positive electrode 50 and the negative electrode 40 are wound together. The electrode assembly 23 includes a straight region 61 and a corner region 62. The positive electrode 50 includes a positive current collector 51 and a positive active material layer 52 disposed on the surface of the positive current collector 51. The positive current collector 51 includes a positive electrode substrate 511 and a first conductive layer 512 disposed at least on the concave surface 51a of the positive electrode substrate 511. At least a portion of the first conductive layer 512 is located in the corner region 62, and at least a portion of the positive active material layer 52 is disposed on the concave surface 51a of the positive electrode substrate 511 and covers the first conductive layer 512. The positive current collector 51 also includes a second conductive layer 513 disposed on the surface of the positive electrode substrate 511. The size of the first conductive layer 512 along the first direction X is larger than the size of the second conductive layer 513 along the first direction X. The first direction X is the thickness direction of the positive electrode substrate 511. At least a portion of the second conductive layer 513 is located in the flat region 61.
[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A battery cell, characterized in that, Includes a housing and an electrode assembly disposed within the housing, the electrode assembly comprising: Negative electrode plate; A positive electrode sheet and a negative electrode sheet are wound together. The electrode assembly includes a flat region and a corner region. The positive electrode sheet includes a positive current collector and a positive active material layer disposed on the surface of the positive current collector. The positive current collector includes a positive electrode substrate and a first conductive layer disposed at least on the concave surface of the positive electrode substrate. At least a portion of the first conductive layer is located in the corner region, and at least a portion of the positive active material layer is disposed on the concave surface of the positive electrode substrate and covers the first conductive layer.
2. The battery cell according to claim 1, characterized in that, The positive current collector further includes a second conductive layer disposed on the surface of the positive electrode substrate. The dimension of the first conductive layer along a first direction is greater than the dimension of the second conductive layer along the first direction. The first direction is the thickness direction of the positive electrode substrate. At least a portion of the second conductive layer is located in the flat region.
3. The battery cell according to claim 2, characterized in that, The second conductive layer is disposed on the concave surface of the positive electrode substrate, and the first conductive layer and the second conductive layer are respectively arranged along the second direction, which is the length direction of the positive electrode substrate.
4. The battery cell according to claim 2, characterized in that, The second conductive sublayer includes a first conductive portion and a second conductive portion. The first conductive portion is disposed on the concave surface of the positive electrode substrate. The first conductive sublayer and the first conductive portion are respectively arranged along a second direction, which is the length direction of the positive electrode substrate. The second conductive portion is disposed on the convex surface of the positive electrode substrate.
5. The battery cell according to claim 4, characterized in that, The second conductive portion covers the entire surface of the convex outer surface of the positive electrode substrate.
6. The battery cell according to claim 2, characterized in that, The material of the first conductive sublayer is the same as the material of the second conductive sublayer.
7. The battery cell according to claim 2, characterized in that, The second conductive sublayer has a dimension D1 along the first direction, and D1 satisfies the following condition: 0.5μm≤D1≤5μm.
8. The battery cell according to claim 7, characterized in that, The D1 satisfies the following condition: 0.5μm≤D1≤3μm.
9. The battery cell according to any one of claims 1-8, characterized in that, The material of the first conductive layer includes at least one of conductive carbon black, acetylene black, conductive carbon fiber, carbon nanotubes, or graphene.
10. The battery cell according to any one of claims 1-9, characterized in that, The dimension of the first conductive layer along the first direction is D2, and the dimension of the positive electrode sheet along the first direction is D3. The D2 and D3 satisfy the following condition: 0.1≤D2 / D3≤0.7, where the first direction is the thickness direction of the positive electrode substrate.
11. The battery cell according to claim 10, characterized in that, The condition that D2 and D3 satisfy the following condition: 0.25≤D2 / D3≤0.
4.
12. The battery cell according to any one of claims 1-11, characterized in that, The dimension of the first conductive layer along the second direction is L, where the second direction is the length direction of the positive electrode substrate, and L satisfies the following condition: 5mm≤L≤100mm.
13. The battery cell according to claim 12, characterized in that, The L satisfies the following condition: 10mm≤L≤20mm.
14. The battery cell according to any one of claims 1-13, characterized in that, The side of the positive electrode active material layer facing the winding center of the electrode assembly is flat.
15. The battery cell according to any one of claims 1-14, characterized in that, The positive electrode active material layer includes a first positive electrode active portion and a second positive electrode active portion. The first positive electrode active portion is disposed on the concave surface of the positive electrode substrate and covers the first conductive layer. The second positive electrode active portion is disposed on the convex surface of the positive electrode substrate.
16. The battery cell according to any one of claims 1-15, characterized in that, The corner region includes multiple positive electrode corners of the positive electrode sheet, and at least two of the positive electrode corners are provided with the first conductive electron layer.
17. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-16.
18. An electrical appliance, characterized in that, Includes the battery device according to claim 17, the battery device being used to provide electrical energy.