Pole piece manufacturing method, battery cell, battery device, and electric device

Abstract

The application provides a pole piece manufacturing method, a battery monomer, a battery device and an electric equipment, and belongs to the battery field. The first polarity pole piece of the battery monomer comprises a pole piece main body and a tab, at least one side of an insulating base film of the pole piece main body is provided with a metal layer, a primer layer and an active material layer which are stacked along a first direction and sequentially away from the insulating base film, the first direction is the thickness direction of the insulating base film; the active material layer has two side edges which are oppositely arranged along a second direction, the second direction is perpendicular to the first direction; the primer layer is provided with the tab on at least one side along the second direction, the tab is connected with the metal layer and exceeds the insulating base film from one end of the primer layer away from the primer layer along the second direction; the primer layer comprises a film layer and two protruding parts, the film layer is arranged on the surface of the metal layer away from the insulating base film, the two protruding parts are arranged on the surface of the film layer away from the insulating base film and are spaced apart along the second direction, and the two protruding parts correspond to the two side edges one by one. The scheme can improve the cycle performance and cycle life of the battery monomer.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for manufacturing an electrode, a battery cell, a battery device, and an electrical device. Background Technology

[0002] Energy conservation and emission reduction are crucial for sustainable social development. Batteries, with their ability to store or release energy as needed, are widely used in various electrical devices and energy storage systems, and are an important component in promoting energy transition and sustainable development. For the new energy industry, battery technology is a critical factor in its development.

[0003] The electrode design in a battery cell is crucial to its cycle performance and cycle life. Therefore, how to improve the electrodes in a battery cell to enhance its cycle performance and cycle life is a problem worthy of attention. Summary of the Invention

[0004] This application aims to at least address one of the technical problems existing in the background art. Therefore, one object of this application is to provide an electrode manufacturing method, a battery cell, a battery device, and an electrical appliance to improve the cycle performance and cycle life of the battery cell.

[0005] An embodiment of the first aspect of this application provides a battery cell including a first polar electrode. The first polar electrode includes an electrode body and a tab. The electrode body includes an insulating base film, a metal layer, a base coating layer, and an active material layer. At least one side of the insulating base film is provided with a metal layer, a base coating layer, and an active material layer stacked along a first direction and sequentially away from the insulating base film. The first direction is the thickness direction of the insulating base film. The active material layer has two sides disposed opposite to each other along a second direction, which is perpendicular to the first direction. The tab is connected to the metal layer. At least one side of the base coating layer along the second direction is provided with a tab, and one end of the tab away from the base coating layer along the second direction extends beyond the insulating base film. The base coating layer includes a film layer and two protrusions. The film layer is disposed on the surface of the metal layer away from the insulating base film. The two protrusions are disposed on the surface of the film layer away from the insulating base film and are spaced apart along the second direction. The two protrusions correspond one-to-one with the two sides. The orthographic projection of each side along the first direction onto the base coating layer falls within the corresponding protrusion.

[0006] In the technical solution of this application embodiment, the bottom coating layer of the first polar electrode sheet located between the metal layer and the active material layer includes a film layer and two protrusions. The two protrusions are located between the film layer and the active material layer, and the orthographic projection of each side of the bottom coating layer along the first direction falls within the corresponding protrusion, thereby thickening the edge regions on both sides of the bottom coating layer along the second direction. Thus, the thickness of the edge regions corresponding to the sides of the active material layer is greater than the thickness of the middle region of the bottom coating layer. This reduces the powder shedding phenomenon at the edge regions of the active material layer during the cold pressing process and reduces the risk of interface peeling between the metal layer and the insulating base film, thereby improving the cycle performance and cycle life of the battery cell.

[0007] In some embodiments, the film layer includes a first region and two second regions, the two second regions being connected to both sides of the first region along a second direction, the two second regions corresponding one-to-one with two protrusions, each of the two second regions being stacked with the corresponding protrusion along a first direction to form an edge coating region, and at least a portion of the thickness of the edge coating region being greater than the thickness of the first region.

[0008] In some embodiments, the thickness of the first region is equal everywhere and is a first thickness T1, and the thickness of at least the portion of the edge coating area adjacent to the first region is equal everywhere and is a second thickness T2, where T2 > T1.

[0009] This embodiment does not thicken the intermediate region. While solving the problems of active material layer falling off near the edge of the tab and cross-sectional peeling of the metal layer and insulating base film at the edge of the electrode, the material used for the base coating can be reduced.

[0010] In some embodiments, the side of the edge coating area closer to the first region in the second direction is the first side, and the side farther from the first region is the second side; the thickness of the edge coating area remains unchanged along the direction from the first side to the second side; 0.5μm≤T1≤5μm, 0.5μm≤T2≤5μm.

[0011] Using this technical solution, it is easier to control the thickness of the slurry coating during the coating process to ensure that the thickness of the entire edge coating area is consistent, and the process is simpler to implement.

[0012] In some embodiments, 1μm≤T1≤2μm, 1.2μm≤T2≤3.5μm. By using the above ranges, this embodiment can balance the cycle performance and energy density of the battery cell.

[0013] In some embodiments, the side of the edge coating area closer to the first region in the second direction is the first side, and the side farther from the first region is the second side; along the direction from the first side to the second side, the thickness of at least the portion of the edge coating area adjacent to the first region gradually increases.

[0014] With this technical solution, the thickness of the base coating is gradually transitioned from the first area to the edge coating area, rather than abruptly. This helps to avoid stress concentration at locations where the thickness changes abruptly.

[0015] In some embodiments, the surface of the first region away from the insulating base film is a first surface, and the protrusion has a first arc surface; along the direction from the first side to the second side, the first arc surface bends and extends from the first surface in a direction that gradually moves away from the insulating base film.

[0016] With this technical solution, the thickness of the base coating changes more gradually from the first area to the edge coating area, which helps to further reduce stress concentration.

[0017] In some embodiments, the surface of the metal layer facing away from the insulating base film is a second surface, and the edge coating area has a second arc surface; the side of the edge coating area closer to the first region in a second direction is a first side, and the side farther from the first region is a second side. Along the direction from the first side to the second side, the second arc surface bends and extends towards the second surface in a direction gradually closer to the insulating base film. This technical solution reduces the requirements for the coating process and decreases stress concentration.

[0018] In some embodiments, the base coating includes a conductive agent, and the conductive agent in the edge coating area includes at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, and carbon nanofibers.

[0019] This technical solution helps to improve the conductivity of the edge coating area, reduces the temperature rise of the edge area of ​​the bottom coating during the charge and discharge cycle of the battery cell, and further reduces the risk of edge area detachment of the active material layer.

[0020] In some embodiments, the base coating includes a conductive agent; the mass percentage of the conductive agent in the edge coating area is W1 based on the mass of the edge coating area; the mass percentage of the conductive agent in the first area is W2 based on the mass of the first area; 20% ≤ W1 - W2 ≤ 40%.

[0021] This embodiment allows for a regional design of the mass percentage of conductive agent in the base coating to meet the different performance requirements of the edge coating area and the first area.

[0022] In some embodiments, the base coating includes a conductive agent, and the conductive agent in the edge coating region includes carbon nanotubes; based on the mass of the edge coating region, the mass percentage of carbon nanotubes in the edge coating region is W3, where W3 ≥ 0.7 wt%. Using the above range helps to significantly improve the conductivity of the edge coating region, thereby further mitigating the impact of temperature rise in the edge region of the base coating during cycling on the shedding of the active material layer.

[0023] In some embodiments, the dimension of the protrusion along the second direction is L1, the dimension of the metal layer along the second direction is OL, and 20%≤L1 / OL≤30%.

[0024] This embodiment ensures that the width of the thickened portion of the edge coating area is within a suitable range as a proportion of the width of the entire metal layer, thereby balancing the cycle performance and cycle life of the battery cell with the energy density of the battery cell.

[0025] In some embodiments, an insulating layer is provided on the side of the metal layer facing away from the insulating base film, and at least a portion of the insulating layer is located between the base coating layer and the end of the tab facing the active material layer. By providing the insulating layer, the risk of short circuits caused by metal contact between the tab and the active material layer can be reduced.

[0026] In some embodiments, the base coating extends beyond both sides in the second direction. This technique reduces the risk of the active material layer adhering to the metal surface while also relaxing the requirements for process precision.

[0027] In some embodiments, a portion of the insulating layer is disposed on the surface of the undercoat layer facing away from the insulating substrate film, and the insulating layer is connected to the active material layer. This technical solution increases the bonding strength of the insulating layer on the electrode.

[0028] An embodiment of the second aspect of this application provides a battery device that includes the battery cell described in the above embodiments.

[0029] An embodiment of the third aspect of this application provides an electrical device that includes the battery device described in the above embodiments, the battery device being used to provide electrical energy.

[0030] An embodiment of the fourth aspect of this application provides a method for manufacturing an electrode sheet, used to manufacture a first polar electrode sheet of a battery cell in the above embodiments. The electrode sheet manufacturing method includes: Provide insulating base film; A metal layer is formed on the surface of the insulating base film; A primer slurry is applied to the surface of the metal layer away from the insulating base film to form a primer layer; wherein the primer layer is stacked with the metal layer along a first direction, and the primer layer includes a film layer and two protrusions. The film layer is disposed on the surface of the metal layer away from the insulating base film, and the two protrusions are disposed on the surface of the film layer away from the insulating base film and are spaced apart along a second direction. The first direction is the thickness direction of the insulating base film and is perpendicular to the second direction. An active slurry is coated on the surface of the base coating away from the insulating substrate to form an active material layer; wherein the active material layer has two sides disposed opposite to each other along a second direction, and the orthographic projection of each side along the first direction onto the base coating falls within a corresponding protrusion. Connect at least one end of the metal layer along the second direction to the tab.

[0031] In some embodiments, coating a primer slurry on the surface of the metal layer away from the insulating base film to form a primer coating layer includes: coating the primer slurry on the surface of the metal layer away from the insulating base film using a microgravure coating process, and forming a primer coating layer after drying.

[0032] This technical solution facilitates the formation of a dense base coating, which reduces the possibility of missed areas at the edges of the base coating.

[0033] 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

[0034] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0035] Figure 1 This is a schematic diagram of the vehicle structure according to some embodiments of this application; Figure 2 This is an exploded view of the battery device according to some embodiments of this application; Figure 3 This is an exploded structural diagram of a battery cell according to some embodiments of this application; Figure 4 This is a schematic diagram of the first polarity electrode sheet in some embodiments of this application; Figure 5 For along Figure 4 Schematic diagram of the cross section of line AA; Figure 6 This is a schematic diagram of the first polarity electrode in some other embodiments of this application; Figure 7 For along Figure 6 Schematic diagram of the cross section of the middle BB line; Figure 8 This is a cross-sectional schematic diagram of the first polarity electrode in some embodiments of this application; Figure 9 This is a cross-sectional schematic diagram of the first polarity electrode in some embodiments of this application; Figure 10 This is a cross-sectional schematic diagram of the first polarity electrode sheet in some modified embodiments of this application; Figure 11 This is a schematic flowchart of an electrode manufacturing method according to some embodiments of this application; Figure 12 This is a schematic diagram of a scanning electron microscope according to Embodiment 1 of this application; Figure 13 This is a schematic diagram of the scanning electron microscope used in Comparative Example 1 of this application; Figure 14 This is a schematic diagram of the retention rate of 800 cycles for Embodiment 1, Comparative Example 1, and Comparative Example 2 of this application.

[0036] Explanation of reference numerals in the attached figures: 1000 vehicles; Battery unit 100, controller 200, motor 300; Battery cell assembly 10, battery cell 11, housing 110, electrode assembly 120, main body 121, tab 122, end cap 130, electrode terminal 131; Box 20, first box 21, second box 22; First polar electrode 30, electrode body 31, insulating base film 311, metal layer 312, second surface 3121, base coating 313, film layer 3131, protrusion 3132, first region 3133, edge coating area 3134, first arc surface 3135, second arc surface 3136, active material layer 314, insulating layer 315, electrode tab 32, welded part 321. Detailed Implementation

[0037] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0038] 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 pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0039] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0040] In this document, the term "embodiment" means that a particular 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 separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0042] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0043] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0044] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "linking", and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components.

[0045] In this application, the term "parallel" includes not only absolute parallelism but also approximate parallelism as commonly understood in engineering; similarly, "perpendicular" also includes not only absolute perpendicularity but also approximate perpendicularity as commonly understood in engineering. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0046] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0048] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0049] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0050] Currently, the application of rechargeable batteries is becoming increasingly widespread, judging from market trends. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in various electronic devices, such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application areas of rechargeable batteries continue to expand, the market demand is also constantly increasing.

[0051] Traditional battery cells typically have electrodes consisting of a current collector and an active material layer. The active material layer is coated on the surface of the current collector, while the current collector without the active material layer protrudes from the current collector with the active material layer. The current collector without the active material layer serves as a tab for output or input current.

[0052] In some related technologies, the electrode of a battery cell also includes an insulating base film. A metal layer (i.e., a current collector) is formed by depositing metal material onto the surface of the insulating base film using physical vapor deposition. In this method, to enable the electrode to connect to the electrode terminals of the battery cell for current transmission, the tab is connected to the metal layer and extends beyond the insulating base film to prevent the insulating base film from blocking the connection between the tab and the electrode terminals. The preparation process of this electrode is as follows: a metal layer is formed on the surface of the insulating base film to obtain a composite current collector; active materials, conductive agents, binders, and any other components are dispersed in a solvent to form an active slurry; the active slurry is coated onto the metal layer, and after drying, cold pressing, and other processes, the electrode is obtained. In practical applications, it has been found that the cycle performance and cycle life of this battery cell do not meet the requirements.

[0053] By disassembling and studying the problematic battery cells, it was found that the active material layer was chipping near the edge of the tab, and there was also delamination at the interface between the metal layer and the insulating base film near the tab.

[0054] Analysis reveals that the modulus of the active material and conductive agent is higher than that of the binder and metal layer. The active slurry contains large-diameter hard particles, which, as rigid inclusions, are not easily deformed, while the binder has a higher deformability. Therefore, the difference in deformability between the hard particles and the binder is significant. During cold pressing, the binder is forced to flow under pressure, creating a relative slippage tendency between the binder and the hard particles. This generates shear stress at the interfaces between the hard particles and the binder, as well as at the interfaces with the metal layer. This shear stress is perpendicular to the thickness direction of the electrode. In other words, stress concentration forms around the hard particles. When the binder cannot absorb this stress concentration through its own plastic deformation, cracks will initiate around the hard particles.

[0055] According to the Poisson effect, a material will expand in the planar direction when subjected to pressure. However, the Poisson ratios of the insulating base film, the metal layer, and the active material layer are different. This causes inconsistent expansion of each layer in the planar direction during cold pressing, which in turn causes peel stress (also known as tensile stress) at the interface of each layer. The peel stress is parallel to the thickness direction of the electrode.

[0056] It should be understood that during cold pressing, the material in the central region of the active material layer is constrained by the surrounding material. This constraint limits the drastic deformation of the central material, allowing the shear stress generated by the hard particles under pressure to be effectively distributed and dissipated by the surrounding material. However, the edge region of the active material layer has a free boundary. During cold pressing, one side of the material in the edge region lacks constraint, and the shear stress cannot be uniformly transmitted in the edge region. This means that the shear stress in the edge region is more likely to exceed the bonding strength between the hard particles and the binder interface and the metal layer interface, making it easier for cracks to initiate around the hard particles in the edge region. Because one side of the material in the edge region lacks constraint, the cracks generated in the edge region can rapidly propagate along the free boundary and, under the tensile stress caused by the Poisson effect, rapidly propagate along the thickness direction of the electrode to the interface between the active material layer and the metal layer. The cracks then penetrate the thickness of the active material layer, leading to powder shedding in the edge region. Even if cracks initiate around the hard particles in the central region of the active material layer, the constraint of the surrounding material greatly reduces the resistance to crack propagation, thus confining the cracks to a small area around the particles.

[0057] For similar reasons, during cold pressing, the lateral expansion of the electrode's central region due to the Poisson effect is restricted by the surrounding material, while the edge region can expand freely outwards. This leads to severe relative slippage between adjacent layers at the edge, resulting in higher peel stress in the edge region. Since the interface between the metal layer and the insulating base film is a weak adsorption interface, the peel stress easily exceeds the bonding strength between the insulating base film and the metal layer, thus causing interface cracking at the electrode edge.

[0058] In summary, during the cold pressing process, larger hard particles create point-like or line-like stress concentrations on the metal layer surface. The free edge effect causes shear stress and peeling stress to reach their maximum in the edge region of the active material layer, making the edge region of the active material layer more prone to powdering and interlayer delamination during cold pressing. Due to the interfacial delamination between the metal layer and the insulating base film at the electrode edge, electrolyte seeps into the space between the metal layer and the insulating base film, causing corrosion of the metal layer at the electrode edge and leading to increased local resistance. This easily triggers more active material layer shedding at the electrode edge during charge-discharge cycles, exacerbating the edge region delamination phenomenon and ultimately inducing a decrease in the cycle performance and cycle life of the battery cell.

[0059] Based on the above considerations, this application improves the electrode of the above-mentioned battery cell by setting at least one of the positive electrode and the negative electrode to include a bottom coating layer. The bottom coating layer is located between the metal layer and the active material layer, and the thickness of at least a portion of the two sides of the bottom coating layer along its width direction is designed to be greater than the thickness of the middle region of the bottom coating layer, so that the bottom coating layer protrudes at the positions corresponding to the two sides of the active material layer.

[0060] In such a battery cell, the edge region of the bottom coating is thickened, which makes the buffer layer between the edge region of the active material layer and the metal layer thicker. This smooths out the strain gradient, reduces stress concentration, and thus reduces the powder shedding phenomenon in the edge region of the active material layer during the cold pressing process. It also reduces the risk of peeling off the interface between the metal layer and the insulating base film, thereby effectively improving the cycle performance and cycle life of the battery cell.

[0061] The battery device provided in this application can be used, but is not limited to, in electrical equipment or energy storage devices such as vehicles, ships, or aircraft. A power system comprising the battery cells and battery device provided in this application can be used to construct such electrical equipment or energy storage device.

[0062] The energy storage device utilizing a battery as a power system in this application embodiment can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems, etc. The energy storage device can store electrical energy as needed and output it at appropriate times. For example, the energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours. The energy storage device provided in this application embodiment can be used in any power system that requires energy storage.

[0063] In some embodiments, the energy storage device is an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0064] In some embodiments, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet. Each battery cluster may include multiple battery units connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, these clusters are connected in parallel to increase the capacity of the energy storage device.

[0065] In this application embodiment, the electrical devices using battery devices as power sources can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0066] It should be understood that the technical solutions described in the embodiments of this application are not limited to the battery devices and electrical equipment described above, but can also be applied to all battery devices including housings and electrical equipment using battery devices. However, for the sake of brevity, the following embodiments are all illustrated using electric vehicles as examples.

[0067] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 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 provided 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.

[0068] 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.

[0069] Figure 2 A schematic diagram of the structure of a battery device 100 according to an embodiment of this application is shown. Figure 2 As shown, the battery device 100 mentioned in the embodiments of this application may include one or more battery cell assemblies 10 for providing voltage and capacity. The battery cell assembly 10 may include multiple battery cells 11, which are connected in series, parallel, or mixed connection via a busbar.

[0070] In some embodiments, the battery cell assembly 10 is typically formed by arranging a plurality of battery cells 11.

[0071] As an example, the battery cell assembly 10 can be a battery module, which is formed by arranging and fixing multiple battery cells 11 together to form an independent module. As an example, the battery module can be formed by bundling multiple battery cells 11 together with cable ties.

[0072] In some embodiments, such as Figure 2As shown, the battery device 100 can be a battery pack, which includes a housing 20 and one or more individual battery cells 10, with the individual battery cells 10 housed within the housing 20. The housing 20 can be a simple three-dimensional structure such as a single cuboid, cylinder, or sphere, or a complex three-dimensional structure composed of combinations of simple cuboids, cylinders, or spheres. The material of the housing 20 can be an alloy such as aluminum alloy or iron alloy, a polymer such as polycarbonate or polyisocyanurate foam, or a composite material such as glass fiber and epoxy resin.

[0073] As an example, the battery cell assembly 10 can be a battery module, and the battery cell assembly 10 can be housed in the housing 20 by fixing the battery module in the housing 20.

[0074] As an example, the battery cell assembly 10 can also be housed in the housing 20 by directly fixing multiple battery cells 11 to the housing 20.

[0075] As an example, the housing 20 may include a first housing 21 and a second housing 22. The first housing 21 and the second housing 22 are fastened together to form a closed space inside the housing 20 to house the battery cell assembly 10. Here, "closed" refers to covering or closing, and can be either non-sealed or sealed to prevent liquids or other foreign objects from affecting the charging or discharging of the battery cell 11. The first housing 21 may be a top cover or a bottom plate.

[0076] As an example, the housing 20 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that the interior of the housing 20 forms an enclosed space to house the battery cell assembly 10.

[0077] In some embodiments, the housing 20 may be part of the vehicle's chassis structure. For example, a portion of the housing 20 may be at least a portion of the vehicle's floor, or a portion of the housing 20 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0078] The battery cell 11 provided in the embodiments of this application can be a secondary battery. A secondary battery refers to a battery cell 11 that can be used again after being discharged by recharging to activate the active material.

[0079] The battery cell 11 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application embodiment is not limited to this. As an example, the battery cell 11 can be a cylindrical battery cell, a prismatic battery cell, or a battery cell 11 of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells, etc., and this application has no particular limitation.

[0080] Figure 3 An exploded view of a battery cell according to some embodiments of this application is shown. Figure 3 As shown, the battery cell 11 provided in the embodiments of this application includes a casing, an electrode assembly 120, and an electrolyte. The electrode assembly 120 is a component in the battery cell 11 where an electrochemical reaction occurs. The electrode assembly 120 and the electrolyte are housed within the casing. As an example, the electrolyte may be liquid or gel-like.

[0081] As an example, the outer casing can be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the outer casing can be a sealed structure or a non-sealed structure. As an example, when the outer casing is a non-sealed structure, the outer casing serves to protect the electrode assembly 120, and a sealing bag is also included between the outer casing and the electrode assembly 120. The sealing bag is used to encapsulate the electrode assembly 120 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the outer casing is a sealed structure, it is used to encapsulate the electrode assembly 120 and the electrolyte, etc.

[0082] As an example, the housing includes a housing 110 and an end cap 130. The housing 110 has an opening, and the end cap 130 closes to the opening of the housing 110. The housing 110 and the end cap 130 together enclose a mounting cavity, which provides mounting space for components such as the electrode assembly 120.

[0083] End cap 130 refers to a component that covers the opening of housing 110 to isolate the internal environment of battery cell 11 from the external environment. The shape of end cap 130 can be adapted to the shape of housing 110 to fit it. Optionally, end cap 130 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 130 is not easily deformed under pressure or impact, giving battery cell 11 higher structural strength and improved safety performance. Functional components such as electrode terminals 131 can be provided on end cap 130. Electrode terminals 131 can be used for electrical connection with electrode assembly 120 to output or input electrical energy to battery cell 11.

[0084] As an example, the end cap 130 may also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 11 reaches a threshold. The end cap 130 can also be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0085] The housing 110 is a component used to cooperate with the end cap 130 to form the internal environment of the battery cell 11, wherein the formed internal environment can accommodate the electrode assembly 120, electrolyte, and other components. The housing 110 and the end cap 130 can be independent components, with an opening on the housing 110 and the end cap 130 closing the opening to form the internal environment of the battery cell 11. Alternatively, the end cap 130 and the housing 110 can be integrated. Specifically, the end cap 130 and the housing 110 can form a common connecting surface before other components are inserted into the housing, and the end cap 130 closes the housing 110 when it is necessary to encapsulate the interior of the housing 110. The housing 110 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 110 can be determined according to the specific shape and size of the electrode assembly 120. The material of the housing 110 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment does not impose any special limitations on this.

[0086] The housing 110 may be open at one end or open at both ends. In some examples, the housing 110 may be a structure with an opening on one side, with one end cap 130 covering the housing 110. In other examples, the housing 110 may be a structure with openings on both sides, with two end caps 130 covering the two openings of the housing 110 respectively.

[0087] Electrode assembly 120 is a component in the battery cell 11 where electrochemical reactions occur. The housing 110 may contain one or more electrode assemblies 120. Electrode assembly 120 may include a main body 121 and tabs 122, with the tabs 122 extending from the main body 121 and protruding from the end of the main body 121. Electrode assembly 120 includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell 11, active ions (e.g., lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, disposed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through. Tabs 122 may include positive and negative tabs, which may be located at either end of the main body 121 or at one end of the main body 121.

[0088] Both the positive electrode and the negative electrode include an electrode body 31 and at least one tab extending from the edge of the electrode body. The electrode body of the positive electrode and the electrode body of the negative electrode are stacked together to form a main body 121. Multiple tabs of the positive electrode are stacked together to form a positive electrode tab portion, and multiple tabs of the negative electrode are stacked together to form a negative electrode tab portion.

[0089] The electrode assembly 120 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0090] In some embodiments, the electrode assembly 120 is a wound structure. For example, the positive electrode, the separator, and the negative electrode are wound into a cylindrical wound structure and then flattened to obtain a flat electrode assembly 120.

[0091] In some embodiments, the electrode assembly 120 has a stacked structure. As an example, multiple positive and negative electrode sheets can be provided, with multiple positive and multiple negative electrode sheets alternately stacked. As an example, multiple positive electrode sheets can be provided, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments. As an example, both positive and negative electrode sheets are folded to form multiple stacked folded segments. As an example, multiple spacers can be provided, each disposed between any adjacent positive or negative electrode sheets. As an example, spacers can be continuously provided, disposed between any adjacent positive or negative electrode sheets by folding or winding.

[0092] In some embodiments, the electrode assembly 120 may be cylindrical, flat, or polygonal in shape.

[0093] Figure 4 This is a schematic diagram of the first polarity electrode sheet in some embodiments of this application. Figure 5 For along Figure 4 A schematic diagram of the cross-section of line AA. Please refer to [link / reference]. Figure 4 and Figure 5 The battery cell 11 provided in this application embodiment includes a first polar electrode 30, which includes an electrode body 31 and a tab 32. The electrode body 31 includes an insulating base film 311, a metal layer 312, a base coating layer 313, and an active material layer 314. At least one side of the insulating base film 311 is provided with a metal layer 312, a base coating layer 313, and an active material layer 314 stacked along a first direction and sequentially away from the insulating base film 311. The first direction is the thickness direction of the insulating base film 311. The active material layer 314 has two sides disposed opposite to each other along a second direction, which is perpendicular to the first direction. The tab 32 is connected to the metal layer 312; the base coating layer 313 is provided with a tab 32 along at least one side along the second direction, and the end of the tab 32 facing away from the base coating layer 313 along the second direction extends beyond the insulating base film 311.

[0094] The base coating 313 includes a film layer 3131 and two protrusions 3132. The film layer 3131 is disposed on the surface of the metal layer 312 away from the insulating base film 311. The two protrusions 3132 are disposed on the surface of the film layer 3131 away from the insulating base film 311 and are spaced apart along the second direction. The two protrusions 3132 correspond one-to-one with the two sides. The orthographic projection of each side along the first direction onto the base coating 313 falls within the corresponding protrusion 3132.

[0095] The first polarity electrode 30 can be either a positive electrode or a negative electrode. Taking the first polarity electrode 30 as a positive electrode as an example, the electrode body 31 of the positive electrode includes an insulating base film 311, a metal layer 312 (i.e., a positive current collector), a base coating layer 313, and an active material layer 314 (i.e., a positive active material layer). The material of the metal layer 312 of the positive electrode can be aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.

[0096] As an example, the positive electrode active material layer includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0097] Taking the first polarity electrode 30 as the negative electrode as an example, the electrode body 31 of the negative electrode includes an insulating base film 311, a metal layer 312 (i.e., the negative electrode current collector), a base coating layer 313, and an active material layer 314 (i.e., the negative electrode active material layer). The material of the metal layer 312 of the negative electrode can be copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.

[0098] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cell 11. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cell 11 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0099] An active material layer 314 is disposed on the surface of the base coating layer 313 facing away from the metal layer 312. The active material layer 314 has two surfaces disposed opposite to each other along a first direction, and the side of the active material layer 314 refers to the surface of the active material layer 314 between the two surfaces.

[0100] The insulating base film 311 is made of a polymer material, such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc. The insulating base film 311 is a long strip-shaped sheet extending along its length or longitudinal direction, and the thickness direction of the insulating base film 311 is perpendicular to its length and width directions. In the accompanying drawings of this application, the length direction of the insulating base film 311 can be referred to as the X direction, the width direction as the Y direction, and the thickness direction (i.e., the first direction) as the Z direction. The second direction is parallel to the width direction of the insulating base film 311.

[0101] In some embodiments, a metal layer 312, a base coating layer 313, and an active material layer 314 are sequentially disposed on one side of the insulating base film 311 in a direction away from the surface of the insulating base film 311, with the metal layer 312 located between the base coating layer 313 and the insulating base film 311. In some embodiments, such as Figure 5 As shown, a metal layer 312, a base layer 313, and an active material layer 314 are sequentially disposed on both sides of the insulating base film 311 in a direction away from the surface of the insulating base film 311, with the insulating base film 311 located between the two metal layers 312.

[0102] The metal material can be formed on the surface of the insulating base film 311 by at least one of vapor deposition and electroless plating to form a metal layer 312. Specifically, the vapor deposition method can be physical vapor deposition (PVD), such as thermal evaporation deposition. Therefore, the metal layer 312 will not extend beyond the edge of the insulating base film 311. The metal material can be deposited on the entire surface of the insulating base film 311, meaning the metal layer 312 can completely cover the surface of the insulating base film 311; or, the metal material can be deposited on a portion of the surface of the insulating base film 311, meaning the metal layer 312 covers a portion of the insulating base film 311.

[0103] A base coating 313 is disposed on the surface of the metal layer 312 facing away from the insulating base film 311. As an example, the base coating 313 includes a conductive agent and an adhesive. In some embodiments, the base coating 313 can completely cover the surface of the metal layer 312. In this example, the metal layer 312 has two surfaces opposite each other in its own thickness direction and an outer peripheral side surface located between the two surfaces. The tab 32 can be fixedly connected to the outer peripheral side surface of the metal layer 312. In some embodiments, the base coating 313 can cover a portion of the surface of the metal layer 312. In this example, the surface of the metal layer 312 has a coated area and an empty foil area. The base coating 313 is disposed in the coated area, and the empty foil area is not coated with the base coating. The tab 32 can be fixedly connected to the empty foil area by welding, bonding, or other methods.

[0104] The base coating 313 is configured to include a film layer 3131 and two protrusions 3132, the two protrusions 3132 being spaced apart along a second direction and corresponding one-to-one with the two side edges. Figure 5 In the middle, the protrusion 3132 on the left corresponds to the left side of the active material layer 314, and the protrusion 3132 on the right corresponds to the right side of the active material layer 314. It should be noted that... Figure 5The dashed line M shown is only used to indicate the interface between the film layer 3131 and the two protrusions 3132; in reality, the base coating layer 313 does not have this dashed line M structure. Thus, the base coating layer 313, corresponding to the side of the active material layer 314, has protrusions 3132 that extend beyond the film layer 3131. In other words, the base coating layer 313 protrudes beyond other locations along the side of the active material layer 314. In other words, the base coating layer 313 thickens along both edges in the second direction.

[0105] The tab 32 is a conductive structure used to achieve electrical connection and current conduction, and the tab 32 can be made of metal. At least one tab 32 is connected to at least one end of the electrode body 31 along its width direction (i.e., the second direction), or multiple tabs 32 are connected to at least one end of the electrode body 31 along the second direction, and the multiple tabs 32 are arranged at intervals along the length direction of the electrode body 31. Figure 6 This is a schematic diagram of the first polarity electrode sheet in some embodiments of this application. Figure 7 For along Figure 6 A schematic diagram of the cross-section of the BB line. See also: [link to example]. Figure 6 and Figure 7 The electrode body 31 has multiple tabs 32 connected to one end along its width direction, and the multiple tabs 32 are spaced apart along the length direction of the electrode body 31. For example, please refer to Figure 4 and Figure 5 The electrode body 31 has multiple tabs 32 connected to each end along its width direction.

[0106] Each metal layer 312 is connected to a tab 32. As an example, a metal layer 312 is provided on one side of the insulating base film 311, and correspondingly, the tab 32 is connected to one metal layer 312. As an example, a metal layer 312 is provided on both sides of the insulating base film 311, and correspondingly, each of the two metal layers 312 is connected to a tab 32.

[0107] In this embodiment, a base coating 313 located between the metal layer 312 and the active material layer 314 includes a film layer 3131 and two protrusions 3132. The two protrusions 3132 are located between the film layer 3131 and the active material layer 314, and the orthographic projection of each side of the base coating 313 along a first direction falls within the corresponding protrusion 3132, thereby thickening the base coating 313 at both edges along a second direction. Thus, the thickness of the edge region corresponding to the side of the active material layer 314 is greater than the thickness of the middle region of the base coating 313.

[0108] On the one hand, because the particle size of the base coating 313 is relatively small (10 nm to 50 nm), it can act as a buffer compared to the active material layer 314, which has larger hard particles. The technical solution of this embodiment is equivalent to increasing the thickness of the buffer layer between the edge region of the active material layer 314 and the metal layer 312. This increases the deformation distance between the edge region of the active material layer 314 and the metal layer 312, thus smoothing the strain gradient, reducing stress concentration, and lowering the risk of shear stress exceeding the interfacial bonding strength between adjacent layers.

[0109] On the other hand, by thickening the edges of the base coating 313, the base coating 313 corresponding to the edge region of the active material layer 314 provides more material to dissipate fracture energy. When cracks initiate around the hard particles in the edge region, the edge region of the base coating 313 can absorb more fracture energy, resulting in greater resistance to crack propagation. This effectively inhibits the rapid propagation of cracks along the free boundary in the edge region and effectively inhibits the rapid propagation of cracks through the thickness of the active material layer 314 towards the current collector.

[0110] With the combined effects of the above two aspects, the technical solution of this embodiment can not only reduce the powder shedding phenomenon in the edge area of ​​the active material layer 314 during the cold pressing process, but also reduce the risk of interface peeling between the metal layer 312 and the insulating base film 311.

[0111] As described above, by reducing the risk of interface peeling between the metal layer 312 and the insulating base film 311, the risk of electrolyte seepage into the space between the metal layer 312 and the insulating base film 311 can be mitigated. Simultaneously, by thickening the edges of the undercoating layer 313, the current-carrying cross-section at the edges of the undercoating layer 313 is increased. Therefore, during the charge-discharge cycle of the battery cell 11, the temperature rise at the edge region of the undercoating layer 313 is significantly reduced, effectively suppressing the aggravating effect of high temperature on electrolyte decomposition. This significantly reduces or even eliminates corrosion at the edge of the metal layer 312 during charge-discharge cycles, thus reducing the risk of further detachment of the edge region of the active material layer 314 induced by corrosion of the metal layer 312 during charge-discharge cycles.

[0112] In summary, by mitigating the powder shedding phenomenon at the edge region of the active material layer 314 during the cold pressing process and reducing the risk of the edge region of the active material layer 314 falling off during charge-discharge cycles, the cycle performance and cycle life of the battery cell 11 can be improved.

[0113] According to some embodiments of this application, the film layer 3131 may include a first region 3133 and two second regions. The two second regions are connected to both sides of the first region 3133 along a second direction. The two second regions correspond one-to-one with two protrusions 3132. Each of the two second regions is stacked with the corresponding protrusion 3132 along a first direction to form an edge coating region 3134. The thickness of at least a portion of the edge coating region 3134 is greater than the thickness of the first region 3133.

[0114] exist Figure 5 In this embodiment, the second region located to the left of the first region 3133 is stacked with the protrusion 3132 on the left to form the left edge coating region 3134, and the second region located to the right of the first region 3133 is stacked with the protrusion 3132 on the right to form the right edge coating region 3134. In this embodiment, the first region 3133 corresponds to the middle region of the base coating 313, and the edge coating region 3134 corresponds to the edge region of the base coating 313 in the second direction.

[0115] The statement "at least a portion of the thickness of the edge coating area 3134 is greater than the thickness of the first region 3133" can be understood as meaning that the thickness of the entire edge coating area 3134 is greater than the thickness of the first region 3133, i.e., the minimum thickness of the edge coating area 3134 is greater than the maximum thickness of the first region 3133. Alternatively, it can be understood as meaning that the thickness of a portion of the edge coating area 3134 is greater than the thickness of the first region 3133, i.e., the minimum thickness of the edge coating area 3134 is less than the thickness of the first region 3133. The thickness of each layer, such as the insulating base film 311, the metal layer 312, the base coating layer 313, and the active material layer 314, refers to its dimension in the first direction. The thickness of each layer can be measured using a micrometer or a ten-thousand-meter, for example, using a Mitutoyo 293-100 ten-thousand-meter with an accuracy of 0.1 μm.

[0116] Using this technical solution, at least a portion of the edge region of the base coating 313 is thickened to exceed the thickness of the middle region. In this embodiment, the portion of the active material layer 314 coated on the first region 3133 can also be regarded as the thickened region of the active material layer 314.

[0117] It is understood that the surface of the edge coating area 3134 facing away from the insulating base film 311 can be a plane, an arc surface, an inclined surface, or a combination thereof.

[0118] Figure 8 This is a cross-sectional schematic diagram of the first polarity electrode in some other embodiments of this application. Figure 9 This is a cross-sectional schematic diagram of the positive electrode sheet according to some embodiments of this application. Please refer to [link to relevant documentation] for some embodiments of this application. Figure 8 and Figure 9The thickness of the first region 3133 can be equal everywhere and is a first thickness T1. The thickness of at least the portion of the edge coating region 3134 adjacent to the first region 3133 is equal everywhere and is a second thickness T2, where T2 > T1.

[0119] In other words, the first region 3133 has a uniform thickness, and both the surface of the first region 3133 facing the insulating base film 311 and the surface of the first region 3133 away from the insulating base film 311 are planar; along the direction away from the first region 3133, the thickness of the edge coating region 3134 remains constant at least initially. The statement that "the thickness of at least the portion of the edge coating region 3134 adjacent to the first region 3133 is everywhere equal and is the second thickness T2" can be understood as the thickness of the portion of the edge coating region 3134 adjacent to the first region 3133 being greater than the thickness of the first region 3133, such as... Figure 9 As shown; it can also be understood that the thickness of the entire edge coating area 3134 is greater than the thickness of the first area 3133, such as Figure 8 As shown. In this embodiment, a step is formed between the surface of the edge coating area 3134 and the surface of the first region 3133 facing away from the metal layer 312.

[0120] In this embodiment, the middle region of the base coating 313 is formed as a flat region, with no thickening at any point in the middle region. This allows for the use of less material in the base coating 313 while still addressing the issues of the active material layer 314 peeling off near the edge of the tab 32 and the interface delamination between the metal layer 312 and the insulating base film 311 at the edge of the electrode.

[0121] According to some embodiments of this application, such as Figure 8 As shown, the edge coating area 3134 is designated as the first side on the side closer to the first region 3133 in the second direction, and the side farther from the first region 3133 is designated as the second side. The thickness of the edge coating area 3134 can remain constant along the direction from the first side to the second side. T1 and T2 can satisfy the following ranges: 0.5μm≤T1≤5μm, 0.5μm≤T2≤5μm.

[0122] Figure 8 The edge coating area 3134 shown has a first side on the right and a second side on the left. The thickness of the edge coating area 3134 remains constant from right to left. That is, the thickness of the edge coating area 3134 is T2 at all points, making the overall thickness of the edge coating area 3134 greater than the thickness of the first region 3133. In this embodiment, the edge coating area 3134 is also a flat region.

[0123] For example, T1 and T2 can be a range of 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm or any two of them, as long as T2 > T1.

[0124] In this embodiment, the entire edge coating area 3134 has a uniform thickness. Compared to technical solutions where the thickness of the edge coating area 3134 gradually increases from the first side to the second side, this embodiment uses more material in the edge coating area 3134. This is beneficial for further increasing the fracture energy that the edge coating area 3134 can absorb, thereby further increasing the crack propagation resistance. Moreover, it is easier to control the slurry coating thickness during the coating process to ensure that the thickness of the entire edge coating area 3134 is uniform, which simplifies the process.

[0125] According to some embodiments of this application, 1μm ≤ T1 ≤ 2μm, 1.2μm ≤ T2 ≤ 3.5μm. As an example, T1 is 1μm and T2 is 1.2μm. As an example, T1 is 2μm and T2 is 3μm or 3.5μm. As an example, T1 is 1μm and T2 is 3.5μm. In this embodiment, 0.2μm ≤ T2 - T1 ≤ 2.5μm.

[0126] By adopting the above-mentioned range, on the one hand, the lower limit of the thickness of the base coating 313 is 1 μm, which is conducive to the continuous and dense coverage of the metal layer 312 by the base coating 313, so that the active material layer 314 is reliably disposed on the metal layer 312 through the base coating 313, and this also helps the base coating 313 to effectively play a buffering role. On the other hand, the upper limit of the thickness of the middle region of the base coating 313 is 2 μm, and the upper limit of the thickness of the edge region is 3.5 μm. This helps to prevent the base coating 313 from being too thick, resulting in an excessive proportion of inactive material in the first polar electrode, so that the battery cell 11 can have a better energy density. Thus, this embodiment can balance the cycle performance and energy density of the battery cell 11.

[0127] Figure 10 This is a cross-sectional schematic diagram of the positive electrode sheet according to some modified embodiments of this application. According to some embodiments of this application, the side of the edge coating region 3134 closer to the first region 3133 in the second direction is designated as the first side, and the side farther from the first region 3133 is designated as the second side. Please refer to... Figure 10 Along the direction from the first side to the second side, the thickness of at least the portion of the edge coating area 3134 adjacent to the first region 3133 can gradually increase.

[0128] That is, along the direction from the first side to the second side, the thickness of the edge coating area 3134 gradually increases at least initially. In some embodiments, such as Figure 10As shown, the thickness of the edge coating area 3134 increases from the first side (right side) to the second side (left side). In this example, the surface of the edge coating area 3134 facing away from the insulating base film 311 is an arc-shaped surface or an inclined surface. In some embodiments, such as Figure 5 As shown, along the direction from the first side to the second side, the thickness of the edge coating area 3134 gradually increases first and then remains constant. In this example, the surface of the edge coating area 3134 facing away from the insulating base film 311 is composed of a combination of an arc-shaped surface / inclined surface and a plane.

[0129] With this technical solution, at the connection between the first region 3133 (i.e., the middle region of the base coating 313) and the edge coating region 3134 (i.e., the edge region of the base coating 313), the thickness of the base coating 313 is gradually transitioned rather than abruptly changed, which helps to avoid stress concentration at the location of abrupt thickness change.

[0130] In some embodiments, the thickness of at least a portion of the edge coating area 3134 may increase linearly along the direction from the first side to the second side. In this example, the surface of the edge coating area 3134 facing away from the insulating base film 311 includes an inclined surface that extends obliquely away from the insulating base film 311 along the direction from the first side to the second side.

[0131] According to some embodiments of this application, the surface of the first region 3133 facing away from the insulating base film 311 is a first surface, and the protrusion 3132 may have a first arc surface 3135. Along the direction from the first side to the second side, the first arc surface 3135 bends and extends from the first surface in a direction gradually away from the insulating base film 311.

[0132] In this embodiment, the thickness of at least a portion of the edge coating area 3134 can increase non-linearly along the direction from the first side to the second side. The end of the first arc surface 3135 near the metal layer 312 is connected to the first surface.

[0133] Compared with the technical solution where the thickness of at least part of the edge coating area 3134 increases linearly, in this embodiment the thickness change of the base coating 313 from the first region 3133 to the edge coating area 3134 is more gradual, which is beneficial to further reduce stress concentration.

[0134] Please refer to some embodiments of this application. Figure 9 The surface of the metal layer 312 facing away from the insulating base film 311 is the second surface 3121, and the edge coating area 3134 may have a second arc surface 3136. Along the direction from the first side to the second side, the second arc surface 3136 bends and extends towards the second surface 3121 in a direction that gradually approaches the insulating base film 311.

[0135] In other words, the thickness of the edge coating area 3134 at the end opposite to the first region 3133 along the second direction gradually decreases to 0 μm in the direction from the first side to the second side. As an example, such as Figure 9 As shown, the surface of the edge coating area 3134 includes a plane and a second arcuate surface 3136. From the first region 3133 to the edge coating area 3134, the first surface, the plane, and the second arcuate surface 3136 are sequentially connected. As an example, the edge coating area 3134 includes a first arcuate surface 3135, a plane, and a second arcuate surface 3136. From the first region 3133 to the edge coating area 3134, the first surface, the first arcuate surface 3135, the plane, and the second arcuate surface 3136 are sequentially connected.

[0136] Understandably, in technical solutions where the end of the edge coating area 3134 facing away from the first region 3133 is at a right angle, higher requirements are placed on the coating process control. In this embodiment, the edge coating area 3134 is designed such that, due to the surface tension of the base coating slurry during the coating process, the end facing away from the first region 3133 is more likely to be curved, thus reducing the requirements on the coating process and reducing stress concentration.

[0137] According to some embodiments of this application, the base coating 313 includes a conductive agent, and the conductive agent in the edge coating area 3134 includes at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, and carbon nanofibers.

[0138] Conductive agents refer to substances that possess electrical conductivity. For example, conductive carbon black includes at least one of conductive carbon black SuperP, acetylene black AB, and Ketjen black KB; optionally, conductive carbon black includes at least one of conductive carbon black SuperP and Ketjen black KB. SuperP is a type of conductive carbon black. The carbon nanotubes of this application refer to carbon allotropes, which are hollow tube structures with a diameter of up to several hundred nanometers formed by rolling single or multiple layers of graphene sheets at a certain helical angle. The tube wall of this hollow tube structure includes one or more cylindrical layers of carbon atoms.

[0139] The material of the first region 3133 may be the same as or different from the material of the edge coating region 3134. In some embodiments, the material composition and mass ratio of each component of the first region 3133 and the material composition of the edge coating region 3134 are the same. In some embodiments, the material composition of the first region 3133 and the material composition of the edge coating region 3134 are the same, but the mass ratio of each component is different.

[0140] This technical solution is beneficial to improving the conductivity of the edge coating area 3134, thereby reducing the internal resistance of the edge coating area 3134. This further reduces the temperature rise of the edge area of ​​the bottom coating 313 during the charge and discharge cycle of the battery cell 11, and further reduces the risk of the edge area of ​​the active material layer 314 falling off during the charge and discharge cycle due to corrosion of the edge area of ​​the metal layer 312 near the tab. This has a positive effect on improving the cycle performance and cycle life of the battery cell 11.

[0141] In embodiments where the conductive agent in the edge coating region 3134 includes graphene and / or carbon nanotubes, the superior flexibility of graphene and the high strength of carbon nanotubes are beneficial to improving the fatigue resistance of the composite current collector composed of the insulating base film 311 and the metal layer 312, which can have a positive effect on reducing the peeling between the metal layer 312 and the insulating base film 311.

[0142] According to some embodiments of this application, the base coating 313 includes a conductive agent. Based on the mass of the edge coating region 3134, the mass percentage of the conductive agent in the edge coating region 3134 is W1. Based on the mass of the first region 3133, the mass percentage of the conductive agent in the first region 3133 is W2. W1 and W2 can satisfy: 20wt% ≤ W1 - W2 ≤ 40wt%.

[0143] In this embodiment, at least the mass ratio of each component in the first region 3133 is different from the mass ratio of each component in the edge coating region 3134. The conductive agent in the first region 3133 may also include at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, and carbon nanofibers. Exemplarily, W1-W2 can be a range of 20wt%, 22.5wt%, 25wt%, 27.5wt%, 30wt%, 32.5wt%, 35wt%, 37.5wt%, 40wt%, or any two of these. Provided that W1-W2∈[20wt%, 40wt%], W1 and W2 can take any values. For example, the value range of W1 can be 25wt%~60wt%, and the value range of W2 can be 5wt%~20wt%.

[0144] The mass percentage of conductive agent in the edge coating area 3134 and the mass percentage of conductive agent in the first region 3133 have meanings known in the art and can be tested using equipment and methods known in the art. For example, the battery cell 11 is discharged to 0% SOC, disassembled to obtain the first polar electrode 30, and then tested using N... The active material layer 314 is dissolved or scraped off using methylpyrrolidone (NMP), and then weighed. After removing the active material layer 314, the base coating layer 313 is exposed. The thickness variation of the base coating layer 313 is observed, and the thickness of the base coating layer 313 at various points is measured using a micrometer. This distinguishes the first region 3133 and the edge coating region 3134. The edge coating region 3134 is scraped off, weighed, and then dissolved in water. The insoluble particles are collected as the conductive agent in the edge coating region 3134, and weighed. The content of conductive agent per unit area is obtained, and the percentage of the conductive agent content in the edge coating area 3134 is calculated as the mass percentage of the conductive agent in the edge coating area 3134. The first region 3133 is scraped off, weighed, and the first region 3133 is dissolved in water. The insoluble particles are collected as the conductive agent in the first region 3133. The content of conductive agent per unit area is obtained by weighing, and the percentage of the conductive agent content in the first region 3133 is calculated as the mass percentage of the conductive agent in the first region 3133.

[0145] In this embodiment, W1 is greater than W2, and the conductivity of the edge coating area 3134 is better than that of the first region 3133. In this way, while reducing the risk of edge region detachment of the active material layer 314 during charge-discharge cycles, the mass percentage of conductive agent in the first region 3133 is relatively low, resulting in higher flexibility and lower brittleness of the first region 3133. This helps to reduce the possibility of powder shedding and cracking in the first region 3133 during long cycles.

[0146] According to some embodiments of this application, the base coating 313 includes a conductive agent, and the conductive agent in the edge coating region 3134 includes carbon nanotubes. Based on the mass of the edge coating region 3134, the mass percentage of carbon nanotubes in the edge coating region 3134 is W3, and W3 can be configured to satisfy: W3 ≥ 0.7 wt%.

[0147] In some embodiments, the value of W3 can range from 0.7wt% to 2wt%. For example, W3 can be a range consisting of 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, or any two of these.

[0148] Carbon nanotubes are one-dimensional conductive agents with excellent electrical conductivity. In this embodiment, the mass percentage of carbon nanotubes is not less than 0.7 wt%, which helps to significantly improve the conductivity of the edge coating area 3134, thereby further reducing the temperature rise of the edge region of the base coating 313 during cycling and reducing the risk of edge region detachment of the active material layer 314 during long cycling.

[0149] According to some embodiments of this application, the dimension of the protrusion along the second direction is L1, and the dimension of the metal layer 312 along the second direction is OL. L1 and OL can be configured to satisfy: 20% ≤ L1 / OL ≤ 30%.

[0150] The dimension of the metal layer 312 along the second direction can be understood as the width of the metal layer 312. The width of the metal layer 312 and the dimension of the protrusion along the second direction can be measured using a micrometer or a ten-thousand-meter, for example, using a Mitutoyo 293-100 ten-thousand-meter with an accuracy of 0.1 μm. Exemplarily, L1 / OL can be a range of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any two of these.

[0151] In some embodiments, such as Figure 8 As shown, the thickness of the edge coating area 3134 remains constant from the first side to the second side, meaning the edge coating area 3134 is a flat region, and its thickness is T2. In this example, the dimension of the protrusion along the second direction is equal to the dimension of the edge coating area 3134 along the second direction (i.e., the width of the edge coating area 3134). As an example, the dimensions of both the metal layer 312 and the insulating base film 311 along the second direction are 136.4 mm, i.e., OL = 136.4 mm. In this example, as... Figure 8 As shown, the edge coating area 3134 has a uniform thickness and the dimension of the edge coating area 3134 along the second direction is 37mm, i.e., L1=37mm. The first region 3133 has a uniform thickness and the dimension of the first region 3133 along the second direction is L2, L2=50mm.

[0152] This technical solution addresses two key issues. First, L1 / OL ≥ 20% ensures that the thickened portion of the edge coating area 3134 does not constitute an excessively small proportion of the width of the entire metal layer 312, effectively resolving the problem of powder shedding and interlayer delamination at the edges of the active material layer 314. Second, L1 / OL ≤ 30% ensures that the thickened portion of the edge coating area 3134 does not constitute an excessively large proportion of the width of the entire metal layer 312, preventing the edge coating area 3134 from encroaching on the space of the active material layer 314 and allowing the battery cell 11 to achieve a better energy density. This embodiment achieves a suitable proportion of the width of the thickened portion of the edge coating area 3134 to the width of the entire metal layer 312, thus balancing the cycle performance and cycle life of the battery cell 11 with its energy density.

[0153] According to some embodiments of this application, an insulating layer 315 may also be provided on the side of the metal layer 312 facing away from the insulating base film 311, and at least a portion of the insulating layer 315 is located between the base coating layer 313 and the end of the tab 32 facing the active material layer 314.

[0154] Insulating layer 315 can be made of AT11 (boehmite), a ceramic material, and insulating layer 315 has excellent insulating properties. In some examples, such as... Figure 5 , Figure 7 and Figure 8 As shown, the entire insulating layer 315 is located between the active material layer 314 and the end of the tab 32 facing the base coating 313. In some examples, such as Figure 10 As shown, a portion of the insulating layer 315 is stacked with the electrode tab along the first direction. As an example, in... Figure 10 In this process, the end of the tab 32 facing the active material layer 314 is stacked on the surface of the metal layer 312 away from the insulating base film 311, and the tab 32 and the metal layer 312 are welded together through the welding part 321. Part of the insulating layer 315 is located on the surface of the tab 32 away from the metal layer 312 to cover the welding part 321. This helps to prevent the welding slag generated during the welding process from contacting the active material layer 314.

[0155] By providing an insulating layer 315, the risk of short circuits caused by metal contact between the tab and the active material layer 314 can be reduced.

[0156] According to some embodiments of this application, the base coating 313 may be configured to extend beyond the two sides in a second direction.

[0157] In other words, the orthographic projection of the active material layer 314 along the first direction onto the surface of the metal layer 312 falls within the orthographic projection of the base coating layer 313 along the first direction onto the surface of the metal layer 312. The dimension L3 of the base coating layer 313 in the second direction is greater than the dimension L4 of the active material layer 314 in the second direction. The distance by which the base coating layer 313 extends beyond the side of the active material layer 314 (i.e., (L3-L4) / 2) can be designed according to requirements; for example, (L3-L4) / 2 can be 1 mm. Where L3 > L4 > L2.

[0158] It is understandable that when the two sides of the base coating layer 313 along the second direction correspond one-to-one with the two sides of the active material layer 314 and are aligned, the base coating layer 313 does not extend beyond the two sides of the active material layer 314 in the second direction. This places high precision requirements on the coating process. Due to process errors, the active material layer 314 may be coated onto the surface of the metal layer 312. In this embodiment, by making the base coating layer 313 extend beyond the two sides of the active material layer 314 in the second direction, there is still a margin of base coating layer 313 on both sides of the active material layer 314 along the second direction, which can tolerate process errors. In this way, the risk of the active material layer 314 being coated onto the surface of the metal layer 312 is reduced, while also relaxing the process precision requirements.

[0159] According to some embodiments of this application, in an embodiment where the base coating 313 extends beyond the two sides of the active material layer 314 along the second direction, a portion of the insulating layer 315 may be disposed on the surface of the base coating 313 away from the insulating base film 311, and the insulating layer 315 is connected to the active material layer 314.

[0160] In some embodiments, such as Figure 5 As shown, the edge coating area 3134 is perpendicular to the first area 3133 at one end, and the insulating layer 315 can be shaped like a "┌" along the first direction. That is, the insulating layer 315 includes a first insulating portion and a second insulating portion connected by a bend. The first insulating portion is located on one side of the base coating 313 along the second direction, and the second insulating portion is located on the surface of the edge coating area 3134 not covered by the active material layer 314, and the second insulating portion is connected to the side of the active material layer 314. In some embodiments, such as Figure 9 As shown, the edge coating area 3134 is arc-shaped at one end away from the first area 3133 along the second direction. Correspondingly, the insulating layer 315 is crescent-shaped and covers the surface of the edge coating area 3134 that is not covered by the active material layer 314.

[0161] This technical solution ensures that the insulating layer 315 is fixedly connected to the active material layer 314, thereby increasing the bonding strength of the insulating layer 315 on the first polarity electrode and reducing the possibility of the insulating layer 315 falling off due to the vibration of the battery cell 11, so that the insulating layer 315 can reliably perform its insulating function.

[0162] An embodiment of the second aspect of this application provides a battery device, such as... Figure 2 As shown, it includes the battery cell 11 in the above embodiments.

[0163] It is understood that the battery device provided in this application, by using any of the aforementioned battery cells 11, has all the beneficial effects of the aforementioned battery cells 11, which will not be elaborated here.

[0164] An embodiment of the third aspect of this application provides an electrical device that includes the battery device described in the above embodiments, the battery device being used to provide electrical energy.

[0165] The electrical equipment includes vehicles (such as cars, electric vehicles, ships, spacecraft, etc.), display devices (such as mobile phones, tablets, laptops, etc.), electric toys, power tools, etc. It is understood that the electrical equipment provided in this application, because it uses any of the above-mentioned battery cells 11, has all the beneficial effects of the battery cells 11, which will not be elaborated here.

[0166] An embodiment of the fourth aspect of this application provides an energy storage device, which includes the battery device described in the above embodiments, the battery device being used for energy storage.

[0167] Energy storage devices can include, but are not limited to, centralized energy storage devices (such as containerized energy storage devices), distributed energy storage devices, mobile energy storage devices, wearable energy storage devices, and so on.

[0168] It is understood that the energy storage device provided in this application, by using any of the aforementioned battery cells 11, has all the beneficial effects of the aforementioned battery cells 11, which will not be elaborated here.

[0169] Figure 11 This is a schematic flowchart illustrating the electrode manufacturing method of some embodiments of this application. Please refer to... Figure 11 This application provides an electrode manufacturing method for manufacturing the first polar electrode of a battery cell in any of the above embodiments. The electrode manufacturing method includes steps S10 to S50.

[0170] S10 provides an insulating base film.

[0171] S20 forms a metal layer on the surface of the insulating base film.

[0172] S30, a primer slurry is applied to the surface of the metal layer away from the insulating base film to form a primer layer; wherein the primer layer and the metal layer are stacked along a first direction, and the primer layer includes a film layer and two protrusions, the film layer is disposed on the surface of the metal layer away from the insulating base film, and the two protrusions are disposed on the surface of the film layer away from the insulating base film and are spaced apart along a second direction, the first direction being the thickness direction of the insulating base film and perpendicular to the second direction.

[0173] S40, an active slurry is coated on the surface of the base coating away from the insulating base film to form an active material layer; wherein the active material layer has two sides disposed opposite to each other along a second direction, and the orthogonal projection of each side along the first direction onto the base coating falls within a corresponding protrusion.

[0174] S50, at least one end of the metal layer along the second direction is connected to the tab.

[0175] The electrode manufacturing method of this embodiment can be used to manufacture both positive and negative electrode sheets. The insulating base film is a long strip-shaped sheet extending along its length or longitudinal direction, and the insulating base film has two opposing surfaces along its thickness direction.

[0176] Step S20 yields the composite current collector. The fabrication method used in step S20 can be vapor deposition, electroless plating, etc. The thickness of the metal layer can be less than the thickness of the insulating base film; for example, the thickness of the insulating base film is 1 μm to 20 μm, and the thickness of the metal layer is 0.1 μm to 10 μm. In step S20, the metal layer can be formed on the entire surface of the insulating base film, or only on a portion of the surface of the insulating base film. When the first polarity electrode is a positive electrode, the material of the metal layer can be aluminum or an aluminum alloy. When the first polarity electrode is a negative electrode, the material of the metal layer can be copper or a copper alloy.

[0177] In step S30, a primer slurry is prepared by mixing a conductive agent and a binder. This primer slurry is then applied to the surface of the metal layer facing away from the insulating base film. The thickness of the primer slurry at at least a portion of the two edges along the width direction of the metal layer is greater than the thickness in the middle region of the metal layer. The layer is then dried to obtain a base coating. The resulting base coating has protrusions at both ends along its width direction that extend beyond the middle region of the base coating. Alternatively, the primer slurry can be applied to the entire surface of the metal layer facing away from the insulating base film, or only a portion of the surface may be coated.

[0178] In step S40, the active material, conductive agent, binder, and solvent are mixed to prepare an active slurry. The active slurry is then coated onto the surface of the base layer away from the insulating substrate and dried to obtain an active material layer. The two sides of the active material layer formed in this way correspond one-to-one with the two protrusions of the base layer along its width.

[0179] The first polar electrode prepared by the method of this embodiment includes a composite current collector and an active material layer. The composite current collector includes an insulating base film and a metal layer disposed on at least one side of the insulating base film. The active material layer is disposed on the side of the metal layer facing away from the insulating base film, and a base coating is disposed between the metal layer and the active material layer. The base coating is thickened at both edges along its width direction. This can reduce the powder shedding phenomenon at the edge region of the active material layer during the cold pressing process and reduce the risk of the edge region of the active material layer falling off during charge-discharge cycles.

[0180] In some embodiments, in step S30, the coating thickness of the primer slurry at both ends of the metal layer along its width direction can be consistent and greater than the coating thickness of the primer slurry in the middle region of the base coating layer. The resulting base coating layer includes a first region and two edge coating regions, the two edge coating regions connecting the two sides of the first region along a second direction. Furthermore, the thickness of the edge coating regions remains constant from the end closer to the first region to the end farther from the first region. Figure 5 As shown.

[0181] In some embodiments, in step S30, the coating thickness of the primer slurry is uniform in the middle region of the metal layer, and gradually increases on both sides of the middle region of the metal layer towards the edge of the metal layer in its width direction. The resulting primer layer includes a first region and two edge coating regions, which are connected to both sides of the first region along a second direction. Furthermore, the thickness of the edge coating regions gradually increases from the end closer to the first region to the end farther from the first region, such as... Figure 8 As shown.

[0182] In some embodiments, the manufacturing method used in step S30 can be any one of slot extrusion coating, transfer coating, gravure coating, and microgravure coating, and the appropriate coating method can be selected according to actual needs or the thickness of the base layer.

[0183] In some embodiments, the material composition and mass ratio of each component in the first region and the two edge coating regions can be different. For example, the base coating includes a conductive agent, and the mass percentage of the conductive agent in the edge coating region is W1 based on the mass of the edge coating region; the mass percentage of the conductive agent in the first region is W2 based on the mass of the first region; 20% ≤ W1 - W2 ≤ 40%. In this embodiment, step S30 can be specifically implemented as follows: mixing the conductive agent and binder to prepare a first base coating slurry and a second base coating slurry; applying the first base coating slurry to the middle region of the surface of the metal layer away from the insulating base film using a slot extrusion coating process; and applying the second base coating slurry to the two edge regions of the surface of the metal layer away from the insulating base film. For example, the coating die head can be provided with three flow channels, arranged sequentially along the width direction of the composite current collector. The middle flow channel can be used to spray the first base coating slurry, and the other two can be used to spray the second base coating slurry, thus producing a base coating with different materials in different regions in a single coating process.

[0184] In some embodiments, the material composition and mass ratio of each component in the first region and the two edge coating regions can be the same. In this embodiment, the fabrication method used in step S30 can be gravure coating or microgravure coating.

[0185] As an example, step S30 can be implemented by applying a primer slurry to the surface of the metal layer away from the insulating base film using a gravure coating process, and then drying it to form a primer layer. In this example, a gravure coating machine is used to coat the primer slurry onto the surface of the metal layer.

[0186] As an example, the specific implementation process of step S30 can be as follows: a base coating slurry is applied to the surface of the metal layer away from the insulating base film using a micro-gravure coating process, and the base coating layer is formed after drying.

[0187] In this example, a microgravure coating machine is used to coat the base coat onto the surface of the metal layer.

[0188] It is understandable that the microgravure coating process utilizes the reverse coating principle to achieve coating. The reverse coating principle means that the rotation direction of the microgravure roller in the microgravure coating machine is opposite to the rotation direction of the pressure roller and the belt travel direction of the substrate (i.e., the composite current collector). In this way, during the coating process, the microgravure roller can also scrape and smooth the base coating slurry, allowing it to be coated more evenly onto the metal layer surface. This facilitates dense coating, forming a dense base layer. This reduces the possibility of missed coating at the edges of the base layer, ensuring that the thickness of the base layer meets design requirements. This ensures that the improved base layer effectively solves the problems caused by the active material layer peeling off along the width direction of the first polar electrode and the interface delamination between the metal layer and the insulating base film at the electrode edge.

[0189] In some embodiments, the manufacturing method used in step S40 can be any of the following: slot extrusion coating, transfer coating, gravure coating, and microgravure coating. The appropriate coating method can be selected according to actual needs or the thickness of the base coating.

[0190] In some embodiments, if step S30 involves coating the entire surface of the metal layer away from the insulating substrate with a primer, then step S50 can involve fixing the tab to the outer peripheral side of the metal layer. The connection method used in step S50 can be any of welding, bonding, etc.

[0191] In some embodiments, if step S30 involves coating the surface portion of the metal layer away from the insulating base film with a primer, step S50 may involve stacking and connecting the tab to the area of ​​the metal layer not coated with the primer.

[0192] In some embodiments, the electrode manufacturing method may further include step S60 before step S50.

[0193] S60, an insulating slurry is prepared by mixing insulating material and adhesive, and the insulating slurry is applied to at least one side of the metal layer away from the insulating base film and along the width direction of the active material layer, and then dried to obtain an insulating layer.

[0194] 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.

[0195] Example To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0196] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0197] Example 1 (1) Preparation of positive electrode Aluminum alloy was deposited onto both sides of a 2μm thick insulating substrate film using physical vapor deposition (PVD) to form a 1μm thick metal layer that completely covers the insulating substrate film, resulting in a composite current collector. The width of both the composite current collector and the metal layer is 136.4 mm.

[0198] 60 wt% conductive carbon black, 35 wt% styrene-butadiene rubber, and 5 wt% sodium carboxymethyl cellulose were dissolved in deionized water and mixed thoroughly to obtain a primer slurry. The primer slurry was applied to the surface of the metal layer away from the insulating substrate using a microgravure coating process. After drying, a base coating layer was formed. The dried base coating layer includes a first region and two edge coating regions. The two edge coating regions are connected to the first region on both sides along the width direction Y of the composite current collector. The thickness of the first region is uniform and 1 μm. From the side closer to the first region to the side away from the first region, the thickness of the edge coating regions gradually increases from 1 μm to 3.5 μm. The width of the first region is 50 mm, and the width of the edge coating regions is 37 mm. The material composition and ratio of the first region and the edge coating regions are the same. The edge coating area includes a second region and a protrusion stacked along the thickness direction Z of the composite current collector. The second region is located between the protrusion and the composite current collector. The second region and the first region are connected at one end along the width direction of the composite current collector to form a film layer. The film layer has a flat structure, and the protrusion protrudes away from the composite current collector relative to the film layer.

[0199] The positive electrode active material, binder polyvinylidene fluoride, conductive agent acetylene black, and dispersant polyvinylpyrrolidone (PVP) were mixed in a mass ratio of 96.5:2:1:0.5. Then, N-methylpyrrolidone (NMP) solvent was added and stirred to form a positive electrode slurry. The positive electrode slurry was coated onto the surface of the undercoating layer away from the insulating base film and then dried to form the active material layer.

[0200] An insulating slurry is prepared by dissolving a certain proportion of insulating material AT11 and adhesive (such as PVDF or polyacrylic acid) in a suitable solvent (such as NMP or water) and stirring it evenly. The insulating slurry is then coated on the surface of the metal layer away from the insulating base film and on one side of the active material layer along the width direction of the composite current collector. After drying, an insulating layer is formed.

[0201] After cold pressing and slitting, the tabs are then welded to the area of ​​the metal layer that is not coated with the base layer and is close to the insulating layer through a roll welding process to obtain the positive electrode sheet. Multiple tabs are connected to both ends of the metal layer along the width direction Y of the composite current collector, and the multiple tabs are spaced apart along the length direction X of the composite current collector.

[0202] (2) Preparation of negative electrode The active material is artificial graphite, the conductive agent is conductive carbon black, the binder is styrene-butadiene rubber (SBR), and the thickener is sodium carboxymethyl cellulose (CMC). Na) is dissolved in deionized water at a weight ratio of 96.2:0.8:0.8:1.2 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is coated evenly on both sides of the negative electrode current collector copper foil once or multiple times, and then dried, cold-pressed and cut to obtain a negative electrode sheet.

[0203] (3) Separating membrane Polypropylene film is used as the separator.

[0204] (4) Preparation of electrolyte In an argon atmosphere glove box with a water content of <10ppm, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) organic solvents were mixed evenly at a volume ratio of 1:1. 12.5% ​​LiPF6 lithium salt was added and dissolved in the organic solvent and stirred evenly.

[0205] (5) Preparation of battery cells The positive electrode, separator, and negative electrode are stacked and wound in sequence, with the separator acting as a separator between the positive and negative electrodes, to obtain a wound electrode assembly. The electrode assembly is placed in a housing, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a battery cell is obtained.

[0206] Example 2 The preparation method of Example 2 is basically the same as that of Example 1, except that a certain ratio of conductive material and binder (such as styrene-butadiene rubber) is dissolved in an appropriate solvent (such as NMP or water) and stirred evenly to form a primer slurry. The conductive material includes carbon nanotubes and other conductive materials (such as acetylene black, graphene, etc.), and the mass percentage of carbon nanotubes is 0.7 wt% based on the mass of the primer coating.

[0207] Comparative Example 1 The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the thickness of the entire base coating is uniform, that is, the base coating has a flat structure and the thickness of the base coating is 1 μm.

[0208] Comparative Example 2 The preparation method of Comparative Example 2 is basically the same as that of Example 2, except that the mass percentage of carbon nanotubes is 0.6 wt%.

[0209] Test methods (1) Delamination of the interface between the metal layer and the insulating base film after charge-discharge cycles of a single battery cell The battery cell was cycled through 400 charge-discharge cycles to ensure complete discharge, and the positive electrode sheet was obtained from the disassembly. The positive electrode sheet was unfolded and cut, with the cut surface parallel to the YZ plane. The thickness of the undercoating was measured using a Mitutoyo 293-100 micrometer. The positive electrode sheet was cut at the 3μm thick undercoating layer, with the cut surface parallel to the XZ plane. The cut surface at the 3μm thick undercoating layer was analyzed by polishing cross-sectional morphology (CP) and scanned by electron microscopy (SEM) to obtain an image.

[0210] (2) Temperature of the edge of the base coating along its width direction during charge-discharge cycles A temperature sensor is built into the casing of the battery cell, positioned near the tab on the bottom coating. The battery cell is discharged at a constant current of 5C at a constant temperature of 25°C. The temperature of the bottom coating near the tab is measured using the temperature sensor and recorded as T1. The battery cell is then charged at a constant current of 1D0 at a constant temperature of 25°C until the voltage reaches 3.65V. It is then charged at a constant voltage of 3.65V until the current is less than or equal to 0.05D0. After resting for 5 minutes, it is discharged at a constant current of 1C until the voltage reaches 2V. This constitutes one charge-discharge cycle. The battery cell is cycled 100 times, and the temperature of the bottom coating near the tab is measured using the temperature sensor and recorded as T2.

[0211] (3) Cyclic performance test The sodium-ion battery cell prepared above was charged at a constant current of 0.5C to the upper limit cutoff voltage of 3.65V, then charged at a constant voltage of 3.65V until the current ≤0.05C, allowed to stand for 5 minutes, and then discharged at 0.5C to 1.5V. The resulting capacity was recorded as the initial capacity C0. The above steps were repeated for the battery cell prepared above, and the discharge capacity Cn of the battery after the nth cycle was recorded. The battery cell capacity retention rate after each cycle was calculated as Cn / C0 × 100%. A curve was obtained by plotting the battery cell capacity retention rate on the ordinate and the corresponding number of cycles on the abscissa to obtain the battery cell capacity retention rate versus the number of cycles.

[0212] Test Results Table 1: Temperature test results of Example 2 and Comparative Example 2

[0213] Figure 12 This is a schematic diagram of the scanning electron microscope used in Embodiment 1 of this application. Figure 13 This is a schematic diagram of the scanning electron microscope used in Comparative Example 1 of this application. Figure 14 This diagram illustrates the retention rate after 800 cycles for Embodiment 1, Comparative Example 1, and Comparative Example 2 of this application. Combining Embodiment 1, Comparative Example 1, and Comparative Example 2, from... Figure 12 , Figure 13 and Figure 14 As can be seen, compared to Comparative Examples 1 and 2, Example 1, by setting a base coating layer between the metal layer and the active material layer, includes a film layer and two protrusions. The two protrusions are located between the film layer and the active material layer, and the orthographic projection of each side of the base coating layer along the first direction falls within the corresponding protrusion, thus thickening the base coating layer along both sides of the second direction. This reduces the risk of delamination at the interface between the metal layer and the insulating base film, thereby reducing the risk of the edge region of the active material layer detaching during charge-discharge cycles, and thus improving the cycle performance and cycle life of the battery cell.

[0214] As shown in Table 1, in combination with Example 2 and Comparative Example 2, compared with Comparative Example 2, Example 2, by setting the mass percentage of carbon nanotubes in the edge coating area to 0.7wt%, is beneficial to improve the conductivity of the edge coating area, thereby reducing the internal resistance of the edge coating area. This can reduce the temperature rise of the edge area of ​​the bottom coating during the charge and discharge cycle of the battery cell.

[0215] 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 first polarity electrode; the first polarity electrode includes: The electrode body includes an insulating base film, a metal layer, a base coating layer, and an active material layer. At least one side of the insulating base film is provided with the metal layer, the base coating layer, and the active material layer stacked along a first direction and sequentially away from the insulating base film. The first direction is the thickness direction of the insulating base film. The active material layer has two sides disposed opposite to each other along a second direction, which is perpendicular to the first direction. A tab is connected to the metal layer; the tab is provided on at least one side of the base coating along the second direction, and one end of the tab opposite to the base coating along the second direction extends beyond the insulating base film; The base coating includes a film layer and two protrusions. The film layer is disposed on the surface of the metal layer away from the insulating base film. The two protrusions are disposed on the surface of the film layer away from the insulating base film and are spaced apart along the second direction. The two protrusions correspond one-to-one with the two side edges. The orthographic projection of each side edge along the first direction onto the base coating falls within the corresponding protrusion.

2. The battery cell according to claim 1, characterized in that, The film layer includes a first region and two second regions. The two second regions are connected to both sides of the first region along the second direction. The two second regions correspond one-to-one with the two protrusions. Each of the two second regions is stacked with the corresponding protrusion along the first direction to form an edge coating area. The thickness of at least a portion of the edge coating area is greater than the thickness of the first region.

3. The battery cell according to claim 2, characterized in that, The thickness of the first region is equal everywhere and is a first thickness T1, and the thickness of at least the portion of the edge coating area adjacent to the first region is equal everywhere and is a second thickness T2, where T2 > T1.

4. The battery cell according to claim 3, characterized in that, The edge coating area is defined as a first side on the side closer to the first region in the second direction and a second side on the side farther from the first region; the thickness of the edge coating area remains constant along the direction from the first side to the second side; 0.5μm≤T1≤5μm, 0.5μm≤T2≤5μm.

5. The battery cell according to claim 4, characterized in that, 1μm≤T1≤2μm, 1.2μm≤T2≤3.5μm.

6. The battery cell according to claim 2, characterized in that, The edge coating area is defined as a first side on the side closer to the first region and a second side on the side farther from the first region in the second direction; along the direction from the first side to the second side, the thickness of at least the portion of the edge coating area adjacent to the first region gradually increases.

7. The battery cell according to claim 6, characterized in that, The surface of the first region facing away from the insulating base film is a first surface, and the protrusion has a first arc surface; along the direction from the first side to the second side, the first arc surface bends and extends from the first surface in a direction gradually away from the insulating base film.

8. The battery cell according to any one of claims 2 to 7, characterized in that, The surface of the metal layer facing away from the insulating base film is the second surface, and the edge coating area has a second arc surface; the side of the edge coating area closer to the first region in the second direction is the first side, and the side farther from the first region is the second side. Along the direction from the first side to the second side, the second arc surface bends and extends towards the second surface in a direction that gradually approaches the insulating base film.

9. The battery cell according to any one of claims 2 to 7, characterized in that, The base coating includes a conductive agent, and the conductive agent in the edge coating area includes at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, and carbon nanofibers.

10. The battery cell according to any one of claims 2 to 7, characterized in that, The base coating includes a conductive agent; based on the mass of the edge coating area, the mass percentage of the conductive agent in the edge coating area is W1; based on the mass of the first area, the mass percentage of the conductive agent in the first area is W2; 20wt%≤W1-W2≤40wt%.

11. The battery cell according to any one of claims 2 to 7, characterized in that, The base coating includes a conductive agent, and the conductive agent in the edge coating area includes carbon nanotubes; based on the mass of the edge coating area, the mass percentage of carbon nanotubes in the edge coating area is W3, where W3 ≥ 0.7 wt%.

12. The battery cell according to any one of claims 1 to 7, characterized in that, The protrusion has a dimension of L1 along the second direction, and the metal layer has a dimension of OL along the second direction, with 20% ≤ L1 / OL ≤ 30%.

13. The battery cell according to any one of claims 1 to 7, characterized in that, An insulating layer is provided on the side of the metal layer facing away from the insulating base film, and at least a portion of the insulating layer is located between the base coating layer and the end of the tab facing the active material layer.

14. The battery cell according to claim 13, characterized in that, The base coating extends beyond the two sides in the second direction.

15. The battery cell according to claim 14, characterized in that, A portion of the insulating layer is disposed on the surface of the base coating layer opposite to the insulating base film, and the insulating layer is connected to the active material layer.

16. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-15.

17. An electrical appliance, characterized in that, Includes the battery device as described in claim 16, the battery device being used to provide electrical energy.

18. A method for manufacturing an electrode sheet, used to manufacture the first polar electrode sheet of a battery cell according to any one of claims 1-15, characterized in that, include: Provide insulating base film; A metal layer is formed on the surface of the insulating base film; A primer slurry is coated on the surface of the metal layer away from the insulating base film to form a primer layer; wherein the primer layer is stacked with the metal layer along a first direction, and the primer layer includes a film layer and two protrusions, the film layer is disposed on the surface of the metal layer away from the insulating base film, and the two protrusions are disposed on the surface of the film layer away from the insulating base film and spaced apart along a second direction, the first direction being the thickness direction of the insulating base film and perpendicular to the second direction; An active slurry is coated on the surface of the base coating away from the insulating base film to form an active material layer; wherein the active material layer has two sides disposed opposite to each other along the second direction, and the orthographic projection of each of the two sides along the first direction onto the base coating falls within a corresponding protrusion. At least one end of the metal layer along the second direction is connected to the tab.

19. The electrode manufacturing method according to claim 18, characterized in that, The step of coating the surface of the metal layer opposite to the insulating base film with a primer slurry to form a primer layer includes: A primer slurry is applied to the surface of the metal layer opposite to the insulating base film using a micro-gravure coating process, and the primer layer is formed after drying.

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