Battery cell, method of manufacturing the same, battery device, and electric device

Abstract

This application belongs to the field of battery technology, specifically disclosing a battery cell, its preparation method, a battery device, and an electrical device. The battery cell includes a positive electrode sheet, which includes a positive electrode film layer. The positive electrode film layer includes a first main region and an edge region. The first main region includes a positive electrode active material, and the edge region includes a positive electrode active material and a porous material. The areal density of the first main region is greater than the areal density of the edge region. The design provided in this application is beneficial for improving the cycle life of the battery.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to a battery cell and its preparation method, a battery device, and an electrical device. Background Technology

[0002] With the development of new energy technologies, batteries are being used more and more widely, such as in mobile phones, laptops, electric vehicles, electric cars, energy storage devices, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. This places increasingly higher demands on battery performance. Summary of the Invention

[0003] This application provides a battery cell, a method for preparing the same, a battery device, and an electrical device. This battery cell is beneficial for improving the cycle life of the battery.

[0004] In one aspect, this application provides a battery cell, including a positive electrode, a separator, and a negative electrode stacked together;

[0005] The aforementioned positive electrode includes a positive current collector and a positive electrode film layer located on at least one side surface of the aforementioned positive current collector;

[0006] The aforementioned positive electrode film layer includes a first main region and an edge region;

[0007] The aforementioned first main body region includes the positive electrode active material;

[0008] The aforementioned edge region includes both positive electrode active material and porous material;

[0009] The surface density of the first main body region is greater than the surface density of the edge region.

[0010] The positive electrode film layer of this application includes a main region and an edge region. The difference between the main region and the edge region includes: the edge region includes porous material, and the areal density of the edge region is lower than that of the main region. The porous material in the edge region facilitates the absorption of electrolyte, ensuring sufficient electrolyte storage at the edge of the positive electrode film layer, thus mitigating the battery cycle life degradation problem caused by obstructed metal ion transport paths at the edge of the positive electrode film layer. Simultaneously, the lower areal density of the edge region compared to the main region means that the mass of positive active material per unit area in the edge region is less than that per unit area in the main region. This design helps reduce the probability of bulging at the edge of the positive electrode film layer, thereby improving the uniformity of current distribution during charging and discharging and ultimately increasing the battery's cycle life.

[0011] In some embodiments, the aforementioned separator includes a coating disposed toward the aforementioned positive electrode film layer;

[0012] The coating includes a second main area and an edge area.

[0013] The orthographic projection of the edge region of the aforementioned positive electrode film onto the aforementioned coating at least partially overlaps with the edge region of the aforementioned coating.

[0014] The edge region of the above coating includes porous material.

[0015] This application selects to simultaneously provide porous materials on the edge region of the positive electrode film and the edge region of the separator coating, so that sufficient electrolyte can be stored at the edge position of the positive electrode film, thereby further improving the cycle life of the battery.

[0016] In some embodiments, the average pore size of the above-mentioned porous material is 50 nm to 10 μm;

[0017] and / or;

[0018] The specific surface area of ​​the above porous material is 20 m². 2 / g~110m 2 / g.

[0019] The average pore size or specific surface area of ​​the porous material in this application meets the above-mentioned numerical range, which facilitates the absorption of electrolyte and full wetting of the porous material.

[0020] In some embodiments, the porous material includes one or more of montmorillonite, diatomite, and vermiculite.

[0021] The porous materials listed in this application contain interconnected or closed pores, which facilitates the storage of electrolyte. Furthermore, the porous materials expand in volume after absorbing electrolyte, reducing the distance between the edge region of the positive electrode film and the edge region of the separator coating. This increases the electrolyte wetting path, which is beneficial for the electrolyte to diffuse and wet at different locations within the electrode, thereby improving the cycle life of the battery.

[0022] In some embodiments, the mass percentage content of the porous material in the edge region of the positive electrode film is 0.1% to 1.0%.

[0023] This application selects a porous material with a mass percentage content of 0.1% to 1.0%, which facilitates the absorption and storage of electrolyte while minimizing the impact on the positive electrode active material and other components in the positive electrode film.

[0024] In some embodiments, the edge region of the positive electrode film extends along a first direction with the first main body region and is arranged in a second direction;

[0025] The first direction mentioned above intersects with the second direction mentioned above;

[0026] Along the second direction described above, the edge region of the positive electrode film layer includes an A surface and a B surface disposed opposite to each other, and the distance between the A surface and the B surface is T1;

[0027] Along the second direction described above, the first main body area includes a C-surface and a D-surface disposed opposite to each other, and the distance between the C-surface and the D-surface is T2;

[0028] Satisfy: T1:T2=(1~3):20.

[0029] In some embodiments, the edge region of the positive electrode film extends along a first direction with the first main body region and is arranged in a second direction;

[0030] The first direction mentioned above intersects with the second direction mentioned above;

[0031] Along the second direction, the edge region of the positive electrode film layer includes an A surface and a B surface disposed opposite to each other, the B surface being close to the first main body region, and the distance between the A surface and the B surface being T1;

[0032] The region formed by extending from the aforementioned surface B to the 0.1×T1 position is denoted as the first sub-edge region, and the region formed by extending from the aforementioned surface A to the 0.1×T1 position is denoted as the second sub-edge region.

[0033] In the first sub-edge region of the above-mentioned positive electrode film layer, the mass percentage content of the above-mentioned porous material is w1;

[0034] In the second sub-edge region of the above-mentioned positive electrode film layer, the mass percentage content of the above-mentioned porous material is w2;

[0035] The condition w1 is greater than w2.

[0036] This application designs a first sub-edge region of the positive electrode film layer located close to the first main body region, and a second sub-edge region of the positive electrode film layer located far from the first main body region. The first sub-edge region contains a higher percentage of porous material by mass compared to the second sub-edge region. This design not only facilitates the storage of sufficient electrolyte at the edge of the positive electrode film layer, but also facilitates the flow of electrolyte from the edge to the main body region of the positive electrode film layer. This further ensures that the electrolyte is evenly distributed at different locations on the positive electrode sheet, so that the entire electrode sheet is fully and effectively wetted, thereby further improving the cycle life of the battery.

[0037] In some embodiments, the edge region of the positive electrode film extends along a first direction with the first main body region and is arranged in a second direction;

[0038] The first direction mentioned above intersects with the second direction mentioned above;

[0039] Along the second direction, the edge region of the positive electrode film layer includes a first sub-edge positive electrode film layer and a second sub-edge positive electrode film layer; the first sub-edge positive electrode film layer and the second sub-edge positive electrode film layer are located on the same side of the first main body region;

[0040] Along the second direction, the first sub-edge positive electrode film layer includes a B-side and an M-side, the B-side being close to the first main body region, and the distance between the B-side and the M-side being t11;

[0041] Along the second direction, the second sub-edge positive electrode film layer includes an A-plane and an N-plane, and the distance between the A-plane and the N-plane is t12; satisfying t11:t12=(0.5~1):(0.5~1);

[0042] In the aforementioned first sub-edge positive electrode film layer, the mass percentage content w1 of the aforementioned porous material is 0.5% to 1%;

[0043] In the aforementioned second sub-edge positive electrode film layer, the mass percentage content w2 of the aforementioned porous material is 0.1% to 0.3%.

[0044] In some embodiments, the areal density A1 of the first main region of the above-mentioned positive electrode film layer is 200 mg / 1540.25 mm². 2 ~400mg / 1540.25mm 2 ;

[0045] and / or;

[0046] The areal density A2 of the edge region of the aforementioned positive electrode film is 170 mg / 1540.25 mm². 2 ~380mg / 1540.25mm 2 .

[0047] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer located on at least one side surface of the negative current collector;

[0048] The aforementioned negative electrode film layer includes a third main region and an edge thinning region;

[0049] The orthogonal projection of the edge thinning region of the aforementioned negative electrode film onto the aforementioned positive electrode film overlaps at least partially with the edge region of the aforementioned positive electrode film.

[0050] This application describes a negative electrode film layer including a third main region and an edge thinning region. This design effectively reduces the probability of bulging at the edge of the negative electrode film layer and improves the cycle life of the battery by improving the uniformity of current distribution during charging and discharging.

[0051] The second aspect of this application is to provide a method for preparing the battery cell described in the first aspect, including the preparation of a positive electrode sheet, the process of which is as follows:

[0052] Provide the first positive electrode slurry: including positive electrode active materials;

[0053] Provide a second positive electrode slurry: including positive electrode active materials and porous materials;

[0054] A first positive electrode slurry is coated on at least one side surface of a positive current collector moving along a first direction to form a first main positive electrode film layer, and a second positive electrode slurry is coated to form an edge positive electrode film layer, wherein the edge positive electrode film layer and the first main positive electrode film layer are arranged in a second direction.

[0055] The first direction mentioned above intersects with the second direction mentioned above;

[0056] The coating thickness of the first main positive electrode film layer is greater than the coating thickness of the edge positive electrode film layer.

[0057] In some embodiments, the coating thickness of the first main positive electrode film layer is h1, and the coating thickness of the edge positive electrode film layer is h2.

[0058] The following conditions must be met: h1 / h2 = 1.01 to 1.15.

[0059] In some embodiments, the aforementioned edge positive electrode film layer includes an E-surface that is attached to the aforementioned positive electrode current collector, and an F-surface that is disposed opposite to the aforementioned E-surface;

[0060] Along the second direction mentioned above, the F surface is an inclined surface that gradually approaches the E surface mentioned above;

[0061] The average distance between the E-plane and the F-plane is the coating thickness h2 of the edge positive electrode film.

[0062] A third aspect of this application is to provide a battery device comprising the battery cell described in the first aspect or the battery cell prepared by the preparation method described in the second aspect.

[0063] A fourth aspect of this application is to provide an electrical device that includes the battery device described in the third aspect.

[0064] 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

[0065] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0066] Figure 1 This is a schematic diagram of the battery structure of some embodiments of this application;

[0067] Figure 2 This is an exploded structural diagram of a battery according to some embodiments of this application;

[0068] Figure 3 This is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0069] Figure 4 This is a schematic diagram of the battery pack structure according to some embodiments of this application;

[0070] Figure 5 This is a schematic diagram of the structure of a secondary battery according to some embodiments of this application;

[0071] Figure 6 This is a schematic diagram of the structure of the positive electrode sheet in some embodiments of this application;

[0072] Figure 7 is a schematic diagram of the structure of the positive electrode film layer in some embodiments of this application; wherein... Figure 7A , Figure 7B and Figure 7C The diagram illustrates the different positional relationships between the main region and the edge region in the positive electrode film layer;

[0073] Figure 8 This is a structural schematic diagram showing the positional relationship between the positive electrode and the insulating member in some embodiments of this application;

[0074] Figure 9 is a schematic diagram of another structure of the positive electrode sheet in some embodiments of this application, wherein, Figure 9A The diagram illustrates the structure of the positive electrode sheet during the coating process and after the battery is formed. Figure 9B , Figure 9C and Figure 9D The diagram illustrates the different positional relationships between the main region and the edge region in the positive electrode film layer;

[0075] Figure 10 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application;

[0076] Figure 11 This is a schematic diagram showing the positional relationship between the positive and negative electrode plates in some embodiments of this application;

[0077] Figure 12This is a schematic diagram of the structure of the positive electrode sheet during the coating process of some embodiments of this application.

[0078] The reference numerals in the detailed embodiments are as follows:

[0079] 10000, vehicles;

[0080] 1000, Battery; 2000, Controller; 3000, Motor;

[0081] 100. Battery cell;

[0082] 200. Box body; 210. First part; 220. Second part;

[0083] 10. Secondary batteries;

[0084] 101. Housing; 102. Electrode assembly; 103. Cover plate;

[0085] 1. Negative electrode sheet; 11. Negative electrode current collector; 12. Negative electrode film; 12a. Third main body region; 12b. Edge thinning region;

[0086] 2. Positive electrode sheet; 21. Positive current collector; 22. Positive electrode film; 22a. First main region; 22b. Edge region of positive electrode film; 22b1. First sub-edge region; 22b2. Second sub-edge region;

[0087] 22bb, first sub-edge positive electrode film layer; 22ba, second sub-edge positive electrode film layer;

[0088] 22a', First main cathode film layer; 22b', Edge cathode film layer;

[0089] 3. Isolation component; 31. Coating; 31a. Second main body area; 31b. Edge area of ​​coating;

[0090] First direction: The direction of extension or length of the electrode, also referring to the y-axis direction;

[0091] The second direction: the width direction of the electrode, also referring to the x-axis direction of the coordinate system;

[0092] The third direction: the z-axis of the coordinate system, or the thickness direction or stacking direction of the electrode. Detailed Implementation

[0093] The following detailed description, with appropriate reference to the accompanying drawings, discloses the battery cell and its preparation method, as well as embodiments of the battery device and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0094] 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 also 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 "a–b" 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.

[0095] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0096] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0097] 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.

[0098] 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.

[0099] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0100] Unless otherwise specified, in this application, the terms "first," "second," etc., 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.

[0101] Unless otherwise specified, in this application, the term "multiple" means two or more (including two), similarly, "multiple sets" means two or more (including two sets), and "multiple pieces" means two or more (including two pieces).

[0102] Unless otherwise specified, 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 used 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.

[0103] Batteries, with their advantages of high energy density, long cycle life, and safety and reliability, have been widely used in various products. In recent years, with the significant increase in demand for batteries as an energy source, higher requirements have been placed on battery performance, such as cycle life.

[0104] In the coating process of battery fabrication, an active material layer is formed on the surface of the current collector. Because the coating at the edges of the current collector is difficult to control, a bulging phenomenon occurs at the edges of the active material layer after battery formation. This means the thickness at the edges of the active material layer is greater than the thickness in the middle region. This phenomenon easily leads to uneven current distribution during charging and discharging, resulting in polarization. To alleviate this phenomenon, existing technologies disclose thinning the edges of the active material layer during battery fabrication to make the edge thickness less than the middle region thickness. However, this design introduces new technical problems: the distance between the edges of adjacent active material layers is greater than the distance between the middle regions of adjacent active material layers. The edges of the active material layer are prone to insufficient electrolyte wetting, leading to various problems. For example, in lithium-ion batteries, this can obstruct the lithium-ion transport path at the edges of the active material layer, causing severe polarization and increased impedance, subsequently resulting in purple spots and lithium plating. This further accelerates electrolyte consumption, speeds up localized aging within the battery, degrades battery cycle performance, and ultimately affects battery life.

[0105] Based on the above considerations, in order to improve the cycle life of the battery, this application conducted relevant experimental research and obtained a battery cell and its preparation method, battery device and power consumption device.

[0106] First, this application discloses a battery cell, which includes a positive electrode, a separator, and a negative electrode stacked together.

[0107] The aforementioned positive electrode includes a positive current collector and a positive electrode film layer located on at least one side surface of the aforementioned positive current collector;

[0108] The aforementioned positive electrode film layer includes a first main region and an edge region;

[0109] The aforementioned first main body region includes the positive electrode active material;

[0110] The aforementioned edge region includes both positive electrode active material and porous material;

[0111] The surface density of the first main body region is greater than the surface density of the edge region.

[0112] The positive electrode film layer of this application includes a main region and an edge region. The difference between the main region and the edge region includes: the edge region includes porous material, and the areal density of the edge region is lower than that of the main region. The porous material in the edge region facilitates the absorption of electrolyte, ensuring sufficient electrolyte storage at the edge of the positive electrode film layer, thus mitigating the battery cycle life degradation problem caused by obstructed metal ion transport paths at the edge of the positive electrode film layer. Simultaneously, the lower areal density of the edge region compared to the main region means that the mass of positive active material per unit area in the edge region is less than that per unit area in the main region. This design helps reduce the probability of bulging at the edge of the positive electrode film layer, thereby improving the uniformity of current distribution during charging and discharging and ultimately increasing the battery's cycle life.

[0113] Therefore, the battery cell provided in this application is beneficial to improving the cycle life of the battery, thereby increasing the user experience.

[0114] Electrode assembly

[0115] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0116] Battery device

[0117] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0118] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0119] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0120] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0121] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0122] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0123] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0124] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0125] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0126] The battery cell of this application may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte composed of the aforementioned battery cell. The outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, aluminum shell, steel shell, etc. The outer packaging of the battery cell can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, including but not limited to polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0127] This application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a square-structured secondary battery 10.

[0128] According to some embodiments of this application, reference is made to Figure 2The outer packaging may include a housing 101 and a cover plate 103. The housing 101 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 101 has an opening communicating with the receiving cavity, and the cover plate 103 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 102 by a winding process or a stacking process. The electrode assembly 102 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 102. The secondary battery 10 may contain one or more electrode assemblies 102, which can be selected by those skilled in the art according to specific practical needs.

[0129] The electrode assembly 102 provided in this application is beneficial to improving the performance of a battery cell when applied in a battery cell. The battery cell can be used as a power source for an electrical device or as an energy storage unit for an electrical device. The electrical device is used in the power field, such as mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited to the above fields.

[0130] For ease of explanation, some embodiments of this application are illustrated using a vehicle as an example of an electrical device.

[0131] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a vehicle 10000 provided in some embodiments of this application. The vehicle 10000 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 1000 is disposed inside the vehicle 10000, and the battery 10000 can be located at the bottom, front, or rear of the vehicle 10000. The battery 10000 can be used to power the vehicle 10000; for example, the battery 10000 can serve as the operating power source for the vehicle 10000. The vehicle 10000 may also include a controller 2000 and a motor 3000. The controller 2000 is used to control the battery 10000 to supply power to the motor 3000, for example, to meet the power needs of the vehicle 10000 during startup, navigation, and driving.

[0132] In some embodiments of this application, the battery 1000 can not only serve as the operating power source for the vehicle 10000, but also as the driving power source for the vehicle 10000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 10000.

[0133] Please refer to Figure 4 , Figure 4This is an exploded view of a battery 1000 provided in some embodiments of this application. The battery 1000 includes a housing 200 and a battery cell 100. A conventional battery cell includes a primary battery or a secondary battery. This application specifically protects a secondary battery 10. The battery cell 100 is housed within the housing 200. The housing 200 provides space for the battery cell 100, and the housing 200 can adopt various structures.

[0134] In some embodiments, the housing 200 may include a first portion 210 and a second portion 220, which overlap each other, and together define a receiving space for accommodating the battery cell 100. The second portion 220 may be a hollow structure with one open end, and the first portion 210 may be a plate-like structure, with the first portion 210 covering the open side of the second portion 220 so that the first portion 210 and the second portion 220 together define the receiving space; alternatively, the first portion 210 and the second portion 220 may both be hollow structures with one open side, with the open side of the first portion 210 covering the open side of the second portion 220. Of course, the housing 200 formed by the first portion 210 and the second portion 220 may be of various shapes, such as a cylinder, a cuboid, etc.

[0135] In battery 1000, there can be multiple battery cells 100, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 100 are connected in both series and parallel configurations. Multiple battery cells 100 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 100 is housed within housing 200. Alternatively, battery 1000 can also be composed of multiple battery cells 100 first connected in series, parallel, or in a mixed manner to form battery modules, and then these modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within housing 200. Battery 1000 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 100.

[0136] battery cell

[0137] This application discloses a battery cell in some embodiments, the battery cell including a positive electrode, a separator and a negative electrode stacked together; the positive electrode film includes a first main region and an edge region; the first main region includes a positive electrode active material; the edge region includes a positive electrode active material and a porous material; the areal density of the first main region is greater than the areal density of the edge region.

[0138] The battery cell in this application can be a rechargeable battery, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used. The battery cell 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 does not limit this to any particular type. In specific embodiments, this application mainly uses a lithium-ion battery as an example to illustrate the technical solution of this application.

[0139] The positive electrode 2, separator 3, and negative electrode 1 of this application can be formed into a secondary battery using a winding or stacking process. Specifically, this application... Figure 5 The diagram illustrates a secondary battery 10 formed using a winding method, combined with... Figure 5 It is known that a negative electrode 1 or a positive electrode 2 is placed between two adjacent separators 3, and the negative electrode 1 and the positive electrode 2 are alternately arranged along the stacking direction (coordinate axis z direction). The number and size of the negative electrode 1 and / or the positive electrode 2 can be selected according to the actual situation, and will not be elaborated in this application. Furthermore, this application... Figure 5 Only one winding method is shown in the illustration. Other stacking or winding methods are within the scope of protection of this application.

[0140] like Figure 6 The diagram illustrates that the positive electrode 2 includes a positive current collector 21 and a positive electrode film 22 located on at least one side surface of the positive current collector 21. Figure 6 The illustration shows a positive electrode film 22 disposed on either side of the surface of the positive current collector 21. The positive electrode film 22 can also be located on both sides of the positive current collector 21. The formation of the positive electrode film 22 on the surface of the positive current collector 21 includes any method conventional in the art, such as coating, deposition, etc. The structure of the negative electrode sheet is the same as that of the positive electrode sheet, and will not be described in detail here. Coating includes any one or more of roll coating, extrusion coating, blade coating, and gravure coating. Deposition includes any one or more of physical deposition and chemical deposition.

[0141] The positive electrode film layer 22 of this application includes a first main body region 22a and an edge region 22b of the positive electrode film layer. The first main body region 22a refers to the positive electrode film layer region corresponding to the large surface of the battery cell, and the edge region 22b of the positive electrode film layer refers to the region corresponding to the side of the first main body region 22a, as shown in Figure 7. Figure 7A , 7B Figure 7C illustrates several different positional relationships between the first main body region 22a and the edge region 22b of the positive electrode film layer. Figure 7 is only a simplified illustration, and other positional relationships are also within the scope of protection of this application.

[0142] The porous material of this application refers to a material containing interconnected or closed pores forming a network structure. This porous material facilitates the absorption of electrolyte so that sufficient electrolyte is stored at the edge of the positive electrode film, thereby alleviating the problem of battery cycle life degradation caused by the obstruction of the metal ion transport path at the edge of the positive electrode film.

[0143] The areal density in this application refers to the mass of material per unit area. The formula for calculating areal density is: Areal density = Weight of a single film layer / Area of ​​a single film layer. The weight of a single film layer can be obtained by direct weighing, and the area of ​​a single film layer can be obtained using the area calculation formula based on the shape of the film layer. In this application, the areal density of the edge region is lower than that of the main body region. This means that the mass of positive electrode active material per unit area in the edge region is less than the mass of positive electrode active material per unit area in the main body region. This design helps reduce the probability of bulging at the edge of the positive electrode film layer, thereby improving the uniformity of current distribution during charging and discharging and thus increasing the battery's cycle life.

[0144] Meanwhile, this application is in Figure 5 The paper describes the specific positional relationship between the negative electrode 1, the positive electrode 2, and the separator 3. Based on the CB value (the ratio of the negative electrode capacity to the positive electrode capacity on the opposite side) and the calculation formula: CB value = negative electrode active material specific capacity × negative electrode areal density × negative electrode active material content / positive electrode active material specific capacity × positive electrode areal density × positive electrode active material content, since the areal density of the edge region of the positive electrode film is less than that of the first main body region, that is, the areal density of the edge region of the positive electrode film is smaller. When applied to the above CB value calculation formula, under the premise that other variables remain unchanged, the CB value increases. Therefore, the design method provided in this application is also conducive to improving the CB value of the battery at the edge position, so that the probability of lithium plating at the edge position of the battery is effectively reduced in the harsh environment where the electrolyte dries up at the edge position, and the cycle life of the battery is further improved.

[0145] In some embodiments, such as Figure 8 The aforementioned separator 3 includes a coating 31 disposed toward the aforementioned positive electrode film layer 22; the coating 31 includes a second main region 31a and an edge region 31b of the coating, and the orthographic projection of the edge region 22b of the positive electrode film layer onto the coating 31 at least partially overlaps with the edge region 31b of the coating; the edge region 31b of the coating includes a porous material. Figure 8 The diagram only shows one edge region of the coating 31 of the separator 3; in reality, the edge region 31b of the coating on the other side also exists.

[0146] This application is in Figure 8The diagram illustrates the positive electrode film layer 22 described in 7C, and the edge region 31b of the coating corresponds to the edge region 22b of the positive electrode film layer. That is, the orthographic projection of the edge region 22b of the positive electrode film layer onto the coating 31 at least partially overlaps with the edge region 31b of the coating. This at least partial overlap includes complete overlap, and this application primarily describes a complete overlap design in subsequent specific embodiments. This application further selects that the edge region 31b of the coating is provided with a porous material, which is the same as the porous material contained in the edge region 22b of the positive electrode film layer, for example, to achieve the same function, but the specific type may be the same or different.

[0147] This application selects to simultaneously provide porous materials on the edge region 22b of the positive electrode film layer and the edge region 31b of the coating of the separator 3, so that sufficient electrolyte can be stored at the edge position of the positive electrode film layer, thereby further improving the cycle life of the battery.

[0148] In some embodiments, the average pore size of the porous material is 50 nm to 10 μm;

[0149] In some embodiments, the specific surface area of ​​the porous material is 20 m². 2 / g~110m 2 / g;

[0150] In some embodiments, the median particle size Dv50 of the porous material is 10 μm to 50 μm.

[0151] The average pore size in this application refers to the average pore size contained in various pore structures within the porous material. The average pore size of the porous material in this application is 50 nm to 10 μm, meaning that most of the pores in the porous material are macropores, which facilitate the storage of electrolyte.

[0152] In these embodiments, this application discloses that the average pore size of the porous material is any one of 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, and 10μm, or any one of the above range values.

[0153] The method for determining the average pore size of porous materials in this application includes any conventional method in the art, such as nitrogen adsorption-desorption analyzers and mercury porosimeter analyzers. Specifically, an ASAP2460 physical adsorption analyzer is used. The dried and degassed material sample is placed in liquid nitrogen, and the amount of nitrogen adsorbed is measured by adjusting different test pressures. Adsorption and desorption isotherms are then plotted. The pore shape is determined based on the shape of the hysteresis loop, and the pore distribution is calculated according to different pore models. The pore size distribution curve is fitted using the BJH model to obtain the average pore size.

[0154] The specific surface area in this application refers to the total area per unit mass of material. The specific surface area of ​​the porous material in this application is 20 m². 2 / g~110m 2 / g, which facilitates the absorption of electrolyte and allows for thorough wetting of the electrolyte.

[0155] In these embodiments, this application discloses a porous material with a specific surface area of ​​20 m². 2 / g、30m 2 / g、40m 2 / g, 50m 2 / g、60m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g, 100m 2 / g、110m 2 Any one of / g or any one of the above range values.

[0156] The method for determining the specific surface area of ​​porous materials in this application includes any conventional method in the art, such as the nitrogen adsorption specific surface area analysis method according to GB / T19587-2004, and the calculation of the specific surface area of ​​the porous material using the BET (Brunauer Emmett Teller) method. The testing instrument can be a TRISTAR II 3020 specific surface area and porosity analyzer from Micromeritics, USA.

[0157] The median particle size Dv50 in this application refers to the particle size at which 50% of the volume is larger than Dv50 and 50% of the volume is smaller than Dv50. It is also known as the median diameter and is commonly used to represent the average particle size. The median particle size of the porous material in this application needs to match the median particle size of the positive electrode active material; the two should not differ significantly. This ensures that the porous material, while effectively adsorbing and storing electrolyte, has minimal impact on the positive electrode active material and other components in the positive electrode film.

[0158] In these embodiments, this application discloses that the median particle size Dv50 of the porous material is any one of 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or any one of the above range values.

[0159] In these embodiments, this application selects to determine the particle size distribution by laser diffraction particle size analysis, specifically by referring to standard GB / T19077-2016 to obtain the particle size distribution map, and then calculates it.

[0160] In some embodiments, the porous material includes one or more of montmorillonite, diatomite, and vermiculite.

[0161] The montmorillonite in this application refers to a layered mineral composed of extremely fine aluminosilicate particles. The interior of this layered mineral contains interconnected or closed pores, which facilitates the storage of electrolyte. Furthermore, after absorbing electrolyte, montmorillonite expands in volume, reducing the distance between the edge region 22b of the positive electrode film and the edge region 31b of the coating of the separator 3. This increases the electrolyte wetting path, which is beneficial for the diffusion and wetting of electrolyte at different locations within the electrode, thereby improving the cycle life of the battery.

[0162] The diatomite in this application is a siliceous rock, and the vermiculite in this application is a layered magnesium-containing aluminum silicate. The diatomite and vermiculite in this application have similar properties to the montmorillonite mentioned above, that is, they are convenient for storing electrolyte and can also expand in volume after absorbing electrolyte. Therefore, any one or more of the diatomite and vermiculite provided in this application are also beneficial to the diffusion and wetting of electrolyte in different positions within the electrode, thereby improving the cycle life of the battery.

[0163] In some embodiments, the mass percentage content of the porous material in the edge region of the positive electrode film is 0.1% to 1.0%.

[0164] The mass percentage content of porous material in the edge region of the positive electrode film in this application refers to the amount added during the preparation process. Since the porous material is stable, the mass change rate is negligible. This application selects a mass percentage content of porous material of 0.1% to 1.0%, which facilitates the absorption and storage of electrolyte while minimizing the impact on the positive electrode active material and other components in the positive electrode film.

[0165] In these embodiments, this application discloses that in the edge region of the aforementioned positive electrode film layer, the mass percentage content of the aforementioned porous material is any one of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any one of the ranges of both of the aforementioned values.

[0166] In some embodiments of this application, the above-mentioned options are selected. Figure 7CThe schematic diagram of the positive electrode film layer 22 will be explained in detail, and further combined with Figure 9A , Figure 9B It is known that the edge region 22b of the positive electrode film extends along the first main body region 22a in the first direction and is arranged in the second direction; in these embodiments of this application, the first direction refers to the y-axis, which also refers to the length direction or extension direction of the positive electrode 2, and the second direction refers to the x-axis, which also refers to the width direction of the positive electrode 2. This application further discloses that the x-axis intersects and is perpendicular to the y-axis. Figure 9A The diagram illustrates two edge regions 22b of the positive electrode film, located on either side of the first main body region 22a along the second direction. The shape and size of these two edge regions 22b are consistent. This design facilitates both film fabrication and electrolyte wetting of the film. Figure 9B Along the second direction (x-axis), the edge region 22b of the positive electrode film includes an A-surface and a B-surface disposed opposite to each other. The B-surface is close to the first main body region 22a. The distance between the A-surface and the B-surface is T1, which also refers to the width of the edge region 22b of the positive electrode film in the second direction. Along the second direction (x-axis), the first main body region 22a includes an C-surface and a D-surface disposed opposite to each other. The distance between the C-surface and the D-surface is T2, and... Figure 9B In this context, "B" can refer to both "C" and "D," and the letter symbols used in the accompanying drawings are merely illustrative. Furthermore, the width of the edge region 22b of the positive electrode film and the width of the first main body region 22a of the positive electrode film satisfy: T1:T2 = (1~3):20. Figure 9B In the schematic diagram of the positive electrode film layer, along the second direction, the ratio between the width T1 of the edge region 22b of the positive electrode film layer on one side of the first main body region 22a, the width T2 of the first main body region 22a, and the width T1 of the edge region 22b of the positive electrode film layer on the other side of the first main body region 22a is: T1:T2:T1 = (1~3):20:(1~3). That is, after disclosing the width values ​​of the positive electrode film layer along the second direction in this application, the positional relationship between the edge region 22b and the first main body region 22a of the positive electrode film layer can be determined according to the above proportional relationship.

[0167] In some embodiments of this application, the above-mentioned options are selected. Figure 7C The schematic diagram of the positive electrode film layer 22 will be explained in detail, and further combined with Figure 9A , 9CIt is known that the edge region 22b of the positive electrode film extends along the first main body region 22a in the first direction and is arranged in the second direction; in these embodiments of this application, the first direction refers to the y-axis, which also refers to the length direction or extension direction of the positive electrode 2, and the second direction refers to the x-axis, which also refers to the width direction of the positive electrode 2. This application further discloses that the x-axis intersects and is perpendicular to the y-axis. Figure 9A The diagram illustrates two edge regions 22b of the positive electrode film, located on either side of the first main body region 22a along the second direction. The shape and size of these two edge regions 22b of the positive electrode film are consistent. (Combined with...) Figure 9C Along the second direction (x-axis direction), the edge region 22b of the positive electrode film layer includes an A-surface and a B-surface disposed opposite each other. The B-surface is close to the first main body region 22a. The distance between the A-surface and the B-surface is T1. The region formed extending from the B-surface to a position of 0.1×T1 is denoted as the first sub-edge region 22b1, and the region formed extending from the A-surface to a position of 0.1×T1 is denoted as the second sub-edge region 22b2. As described above, the edge region 22b of the positive electrode film layer contains porous material. In the first sub-edge region 22b1 of the positive electrode film layer, the mass percentage content of the porous material is w1; in the second sub-edge region 22b2 of the positive electrode film layer, the mass percentage content of the porous material is w2; satisfying w1 greater than w2. This application... Figure 9C The diagram illustrates that the first sub-edge region 22b1 of the positive electrode film is located close to the first main body region 22a, while the second sub-edge region 22b2 of the positive electrode film is located away from the first main body region 22a. The first sub-edge region 22b1 contains a higher percentage of porous material by mass compared to the second sub-edge region 22b2. This design not only facilitates the storage of sufficient electrolyte at the edge of the positive electrode film but also facilitates the flow of electrolyte from the edge to the main body region of the positive electrode film. This further ensures that the electrolyte is evenly distributed at different locations on the positive electrode sheet, allowing the entire electrode sheet to be fully and effectively wetted, thereby further improving the cycle life of the battery.

[0168] In some embodiments of this application, the above-mentioned options are selected. Figure 7C The schematic diagram of the positive electrode film layer 22 will be explained in detail, and further combined with Figure 9A , Figure 9D It is known that the edge region 22b of the positive electrode film extends along the first main body region 22a in the first direction and is arranged in the second direction; in these embodiments of this application, the first direction refers to the y-axis, which also refers to the length direction or extension direction of the positive electrode 2, and the second direction refers to the x-axis, which also refers to the width direction of the positive electrode 2. This application further discloses that the x-axis intersects and is perpendicular to the y-axis. Figure 9AThe diagram illustrates two edge regions 22b of the positive electrode film, located on either side of the first main body region 22a along the second direction. The shape and size of these two edge regions 22b of the positive electrode film are consistent. (Combined with...) Figure 9D Along the second direction, the edge region 22b of the aforementioned positive electrode film layer includes a first sub-edge positive electrode film layer 22bb and a second sub-edge positive electrode film layer 22ba; along the second direction, the first sub-edge positive electrode film layer 22bb includes a B-plane and an M-plane, the distance between the B-plane and the M-plane being t11; along the second direction, the second sub-edge positive electrode film layer 22ba includes an A-plane and an N-plane, the distance between the A-plane and the N-plane being t12; as described above, t11 and t12 refer to the width values ​​of each sub-edge positive electrode film layer in the second direction. Figure 9D The above-mentioned N-plane and M-plane are shown to be the same plane, but represented by different symbols. At the same time, the above-mentioned N-plane and M-plane can also be different planes. Correspondingly, the edge region 22b of the positive electrode film layer includes three or more sub-edge positive electrode film layers. The figures in this application are only for illustration and do not represent any actual meaning.

[0169] This application focuses on describing an edge region 22b of the positive electrode film layer comprising two sub-edge positive electrode films, namely a first sub-edge positive electrode film layer 22bb and a second sub-edge positive electrode film layer 22ba. The ratio between the width t11 of the first sub-edge positive electrode film layer 22bb in the second direction and the width t12 of the second sub-edge positive electrode film layer 22ba in the second direction satisfies t11:t12 = (0.5~1):(0.5~1). As described above, the edge region 22b of the positive electrode film layer contains porous material. In the first sub-edge positive electrode film layer 22bb, the mass percentage content w1 of the porous material is 0.5%~1%; in the second sub-edge positive electrode film layer 22ba, the mass percentage content w2 of the porous material is 0.1%~0.3%. This application provides a detailed structure of the edge region of the positive electrode film layer, which will be further elaborated in subsequent specific embodiments.

[0170] In some embodiments, the areal density A1 of the first main body region is 200 mg / 1540.25 mm. 2 ~400mg / 1540.25mm 2 .

[0171] In some embodiments, the areal density A2 of the edge region of the above-mentioned positive electrode film is 170 mg / 1540.25 mm². 2 ~380mg / 1540.25mm 2 .

[0172] The above embodiments describe the specific values ​​of the areal density of the main region and the edge region of the positive electrode film. The subsequent specific embodiments elaborate on the impact of different areal density design methods on the battery performance of this application.

[0173] In some embodiments, combined with Figure 10 It is understood that the aforementioned negative electrode sheet 1 includes a negative current collector 11 and a negative electrode film layer 12 located on at least one side surface of the aforementioned negative current collector 11; the negative electrode film layer 12 includes a third main body region 12a and an edge thinning region 12b; the meaning of the third main body region 12a in this application is the same as that of the first main body region 22a of the aforementioned positive electrode film layer 22 and the second main body region 31a of the separator 3, and their positions also correspond. Specifically, the orthographic projection of the edge thinning region 12b of the aforementioned negative electrode film layer 12 onto the aforementioned positive electrode film layer 22 at least partially overlaps with the edge region 22b of the aforementioned positive electrode film layer, as shown in the figure. Figure 11 It is illustrated that at least partial overlap here includes complete overlap, and this application is mainly described in the form of a complete overlap design in the following specific embodiments.

[0174] This application is in Figure 10 The negative electrode film 12 is described as including a third main body region 12a and an edge thinning region 12b. This design can effectively reduce the probability of bulging at the edge of the negative electrode film and improve the cycle life of the battery by improving the uniformity of current distribution during charging and discharging.

[0175] This application is in Figure 11 The paper describes the specific positional relationship between the negative electrode 1, the positive electrode 2, and the separator 3. Based on the CB value (the ratio of the negative electrode capacity to the positive electrode capacity on the opposite side) and the calculation formula: CB value = negative electrode active material specific capacity × negative electrode areal density × negative electrode active material content / positive electrode active material specific capacity × positive electrode areal density × positive electrode active material content, since the areal density of the edge region of the positive electrode film is less than that of the first main body region, that is, the areal density of the edge region of the positive electrode film is smaller. When applied to the above CB value calculation formula, under the premise that other variables remain unchanged, the CB value increases. Therefore, the design method provided in this application is also conducive to improving the CB value of the battery at the edge position. Thus, even in the harsh environment of electrolyte drying at the edge position, the lithium plating probability at the edge position of the battery is effectively reduced, further improving the cycle life of the battery.

[0176] Preparation method of positive electrode sheet

[0177] Some embodiments of this application disclose a method for preparing a positive electrode sheet, including the following process:

[0178] Provide the first positive electrode slurry: including positive electrode active materials;

[0179] Provide a second positive electrode slurry: including positive electrode active materials and porous materials;

[0180] A first positive electrode slurry is coated on at least one side surface of a positive current collector moving along a first direction to form a first main positive electrode film layer, and a second positive electrode slurry is coated to form an edge positive electrode film layer. The edge positive electrode film layer and the first main positive electrode film layer are arranged in a second direction; the first direction intersects the second direction. The coating thickness of the first main positive electrode film layer is greater than the coating thickness of the edge positive electrode film layer.

[0181] like Figure 12 To illustrate, a first positive electrode slurry is coated on both sides of the positive electrode current collector 21 moving along the first direction (coordinate axis y-direction) to form a first main positive electrode film layer 22a'. Here, the first main positive electrode film layer 22a' is the same as described above. Figure 9A Corresponding to the first main body region 22a of the positive electrode film layer 22, simultaneously, a second positive electrode slurry is coated on both sides of the positive electrode current collector 11 moving along the first direction (coordinate axis y direction) to form an edge positive electrode film layer 22b', where the edge positive electrode film layer 22b' is the same as described above. Figure 9A Corresponding to the edge region 22b of the positive electrode film layer, and in this application, during coating, the coating thickness of the first main positive electrode film layer 22a' is greater than the coating thickness of the aforementioned edge positive electrode film layer 22b'. Here, the coating thickness refers to the distance between the upper and lower end faces of the positive electrode film layer disposed opposite each other along the z-axis. As mentioned above, since the coating at the edge position of the current collector is difficult to control, after the battery is formed, a bulging phenomenon will occur at the edge position of the film layer. For example, the thickness of the edge region of the positive electrode film layer is greater than the thickness of the middle main region. This phenomenon can easily lead to uneven current distribution during the charging and discharging process of the battery, thus forming polarization. To alleviate this phenomenon, this application selects the coating thickness of the first main positive electrode film layer 22a' to be greater than the coating thickness of the aforementioned edge positive electrode film layer 22b', which is equivalent to thinning the edge region 22b of the positive electrode film layer. Meanwhile, the edge positive electrode film layer 22b' of this application contains porous material compared to the first main positive electrode film layer 22a'. As mentioned above, the porous material of this application undergoes volume expansion after absorbing electrolyte, that is, the edge positive electrode film layer 22b' undergoes volume expansion. Figure 9A The area enclosed by the dashed lines corresponds to Figure 12 The edge positive electrode film layer 22b' is formed by the volume expansion of the edge positive electrode film layer 22b' after absorbing electrolyte. Figure 9A The schematic diagram shows the edge region 22b of the positive electrode film. Figure 9AThis diagram illustrates one possible structure where the edge positive electrode film layer 22b' undergoes volume expansion. In a single battery cell, after the edge positive electrode film layer 22b' expands in volume, the distance between the edge regions 22b of adjacent positive electrode film layers decreases. Furthermore, the edge positive electrode film layer 22b' absorbs and stores sufficient electrolyte, increasing the electrolyte's wetting path and mitigating the battery cycle life degradation problem caused by obstructed metal ion transport paths at the edge of the positive electrode film layer.

[0182] In some embodiments, the coating thickness of the first main positive electrode film layer 22a' is h1, and the coating thickness of the edge positive electrode film layer 22b' is h2; satisfying: h1 / h2=1.01~1.15.

[0183] The coating thickness in this application refers to the distance between the upper and lower end faces of the positive electrode film layer along the z-axis, specifically the average value of the distance between the upper and lower end faces of the positive electrode film layer. This application... Figure 12 The diagram illustrates the coating thickness h1 of the first main positive electrode film layer 22a' and the coating thickness h2 of the edge positive electrode film layer 22b'. The coating thickness can be obtained using conventional measurement methods in the art, such as micrometers and scanning electron microscopes, when preparing the positive electrode sheet.

[0184] In these embodiments, this application discloses that the ratio between the coating thickness h1 of the first main positive electrode film layer 22a' and the coating thickness h2 of the aforementioned edge positive electrode film layer 22b' is any one of 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, and 1.15 or any one of the aforementioned range values.

[0185] In some embodiments, combined with Figure 12 It can be seen that the aforementioned edge positive electrode film layer 22b' includes an E-surface that is attached to the aforementioned positive electrode current collector 21, and an F-surface that is opposite to the E-surface; along the second direction, the F-surface is an inclined surface that gradually approaches the aforementioned E-surface; the coating thickness h2 of the edge positive electrode film layer 22b' in this application refers to an average value, that is, it is obtained by summing the distances between the E-surface and the F-surface at different positions using a mathematical function and then averaging them. Figure 12 The h2 shown in the diagram only represents the coating thickness at that location. The actual average coating thickness needs to be obtained by summing the values ​​using the mathematical function described above and then averaging them. This mathematical function can refer to any function conventional in this field, and it can be calculated to obtain a value that conforms to... Figure 12 The average coating thickness of the schematic structure.

[0186] In the above description of the positive electrode film, this application discloses... Figure 9A and9C As illustrated, the edge region 22b of the positive electrode film layer includes a first sub-edge region 22b1 disposed close to the first body 22a and a second sub-edge region 22b2 disposed away from the first body 22a, and the mass percentage content of porous material in the first sub-edge region 22b1 is greater than the mass percentage content of porous material in the second sub-edge region 22b2.

[0187] At the same time, this application further... Figure 9A and Figure 9D The diagram illustrates that the edge region 22b of the positive electrode film layer includes a first sub-edge positive electrode film layer 22bb and a second sub-edge positive electrode film layer 22ba, and the mass percentage content of porous material in the first sub-edge positive electrode film layer 22bb, which is located closer to the first main body region 22a, is greater than the mass percentage content of porous material in the second sub-edge positive electrode film layer 22ba, which is located further away from the first main body region 22a.

[0188] In preparing the edge positive electrode film 22b' of the above-mentioned positive electrode film layer, this application can divide the edge positive electrode film layer 22b' into different sub-edge positive electrode film layers, and then coat each different sub-edge positive electrode film layer with an electrode slurry containing a different content of porous material. The advantage of this design is that it not only facilitates the storage of sufficient electrolyte at the edge position of the positive electrode film layer, but also allows the electrolyte at the edge position to flow to the main body area of ​​the positive electrode film layer, further enabling the electrolyte at different positions of the positive electrode sheet to be evenly dispersed, so that the entire electrode sheet is fully and effectively wetted, thereby further improving the cycle life of the battery.

[0189] [Positive electrode plate]

[0190] According to some embodiments of this application, as described above, the positive electrode sheet includes a current collector and a positive electrode film layer located on at least one side surface of the current collector. The positive electrode film layer contains a positive electrode active material. The structures of the main body region and the edge region of the positive electrode film layer in this application are as described above, and the biggest difference between the components contained in the main body region and the edge region lies in the porous material; other components may be the same or different.

[0191] According to some embodiments of this application, when the positive electrode sheet is applied to a lithium-ion battery, the positive electrode active material includes, but is not limited to, one or more combinations of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium olivine-structured lithium phosphate; wherein, the structural formula of the olivine-structured lithium phosphate is: LiFe 1-x-y Mn x M yPO4, 0≤x≤1, 0≤y<1, 0≤x+y≤1, M contains one or more of the transition metal elements or non-transition metal elements other than Fe and Mn, and M further contains any one or more of Cr, Mg, Ti, Al, Zn, W, Nb, and Zr.

[0192] This application specifically includes, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 CO 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 CO 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 CO 0.15 Al 0.05 Any one or more of O2, LiFePO4 (LFP), and LiMnPO4.

[0193] According to some embodiments of this application, when the positive electrode sheet is applied to a sodium-ion battery, the positive electrode active material includes, but is not limited to, at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. Specifically, in the sodium transition metal oxide, the transition metal can be any one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and the sodium transition metal oxide is, for example, Na. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≤ 1. Polyanionic compounds include sodium vanadium trifluorophosphate (Na3V2(PO4)2F3), sodium vanadium fluorophosphate (NaVPO4F), sodium vanadium phosphate (Na3V2(PO4)3), Na4Fe3(PO4)2P2O7, and NaFePO4, among any one or more of these. Prussian blue compounds are Na... x M1M2(CN)6, wherein M1 and M2 are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, and 0 < x ≤ 2.

[0194] According to some embodiments of this application, the positive electrode film layer also includes conductive agents, binders, etc. Conductive agents include, but are not limited to, any one or more of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Binders include, but are not limited to, any one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc. The positive electrode current collector in this application is as described above, and will not be repeated here.

[0195] The positive current collector of this application can be a metal foil or a composite current collector. The metal foil can be an aluminum foil, and the composite current collector can include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material, such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, on a polymer material substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0196] The method of forming the positive electrode film layer in this application includes mixing the above-mentioned raw materials with a solvent (such as N-methylpyrrolidone) in a certain mass ratio to form a positive electrode slurry, uniformly coating the positive electrode slurry on both sides of the current collector; controlling a certain single-sided coating weight; and after drying, compacting it to a certain compaction density using a cold press to obtain a positive electrode sheet containing the positive electrode film layer.

[0197] [Negative electrode plate]

[0198] The negative electrode of this application includes a current collector and a negative electrode film layer located on one or both surfaces of the current collector. Generally, the negative electrode film layer is located on both surfaces of the current collector, and is formed by methods such as coating or deposition. In this application, both sides will be used as examples.

[0199] This application discloses in some embodiments that the negative electrode film layer includes a negative electrode active material, which comprises one or more of carbonaceous materials, silicon-based materials, silicon-carbon composite materials, tin-based materials and their alloys. The carbonaceous materials in this application include one or more combinations of artificial graphite, natural graphite, soft carbon, and hard carbon. Among them, artificial graphite, natural graphite, soft carbon, and hard carbon include any form of material conventional in the art, and include any manufacturer and model conventional in the art. The silicon-based materials in this application include one or two of silicon-oxygen materials or silicon-carbon materials, or silicon-carbon composites. The tin-based materials and their alloys in this application include, but are not limited to, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, etc. Furthermore, this application is not limited to these materials; other conventional materials that can be used as negative electrode active materials for lithium-ion batteries or sodium-ion batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0200] In some embodiments, this application discloses that the conductive agent includes one or more of dot-shaped conductive agents, linear conductive agents, and planar conductive agents. The dot-shaped conductive agent includes one or more of conductive carbon black (Super P or Super S), acetylene black, conductive graphite (KS-6 or KS-15 or SFG-6 or SFG-15), and Ketjen black. The linear conductive agent includes one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers. The planar conductive agent includes, but is not limited to, graphene.

[0201] This application discloses in some embodiments that the negative electrode film layer includes a binder and a dispersant. The binder includes, but is not limited to, polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, polyethylene oxide, polyacrylic acid, polyacrylamide, sodium alginate, styrene-butadiene rubber (SBR), etc. The dispersant also includes any type conventional in the art, such as cellulose and its salts, specifically including, but not limited to, methylcellulose, carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.

[0202] The negative electrode current collector of this application can be a metal foil or a composite current collector. The metal foil can be a copper foil, and the composite current collector can include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material, such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, or silver alloys, on a polymer material substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0203] The method of forming the negative electrode film layer in this application includes mixing the above-mentioned raw materials with a solvent (such as deionized water) in a certain mass ratio to form a negative electrode slurry, defoaming the negative electrode slurry, uniformly coating the negative electrode slurry on both sides of the negative electrode current collector; controlling the coating weight on one side; drying, and compacting it to a certain compaction density using a cold press to obtain a negative electrode sheet containing a negative electrode film layer.

[0204] [Isolation Component]

[0205] Some embodiments of this application disclose isolation elements. This application does not have any particular restrictions on the type of isolation element, and any known porous structure isolation element with good chemical and mechanical stability can be selected.

[0206] In some embodiments, the separator includes a substrate material layer and a coating disposed on the surface of the substrate material layer; the substrate material of the substrate material layer includes one or more of polyethylene, polypropylene, poly(p-phenylene terephthalamide), polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, and polyamide; the coating includes an inorganic coating and / or an organic coating. The substrate material layer has good permeability to metal ions, which is beneficial to the migration of metal ions; the coating disposed on the surface of the substrate material layer can further improve the mechanical properties of the separator. Further, the inorganic coating includes a ceramic coating, and the ceramic particles in the ceramic coating include one or more of SiO2, Al2O3, AlOOH, CaO, TiO2, MgO, ZnO, ZrO2, Mg(OH)2, and BaSO4. The ceramic coating of this application plays an insulating role, reducing the probability of short circuit due to puncture of the separator. That is, this application uses a separator containing a ceramic coating, which firstly reduces the probability of short circuit, and even if a short circuit occurs, the current collector designed in this application can quickly cut off the short circuit to improve safety.

[0207] In some embodiments, the organic coating includes an organic polymer coating, wherein the polymer material of the organic polymer coating includes one or more of polyethylene (PE), polypropylene (PP), poly(p-phenylene terephthalamide) (PPTA), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polyimide (PI), and polyamide (PA). The polymer coating may be made of the same or different material as the substrate material layer, and the thicknesses of the polymer coating and the substrate material layer may be different; furthermore, the thickness of the polymer coating is less than the thickness of the substrate material layer.

[0208] In other embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0209] At the same time, as described above regarding individual battery cells, such as Figure 8 The separator 3 is illustrated as follows: it includes a coating 31 disposed towards the positive electrode film layer 22; the coating 31 includes a second main body region 31a and an edge region 31b of the coating, and the orthographic projection of the edge region 22b of the positive electrode film layer onto the coating 31 at least partially overlaps with the edge region 31b of the coating; the edge region 31b of the coating includes a porous material. In subsequent specific embodiments, this application describes that the orthographic projection of the edge region 22b of the positive electrode film layer onto the coating 31 completely overlaps with the edge region 31b of the coating. Furthermore, to ensure the separator effectively isolates the positive and negative electrodes, the orthographic projection area of ​​the edge region 31b of the coating onto the coating 31 is larger than the orthographic projection area of ​​the edge region 22b of the positive electrode film layer onto the coating 31. The specific dimensions of the orthographic projection area of ​​the edge region 31b of the coating onto the coating 31 need to be described based on the actual battery design, and this application does not impose any limitations on this.

[0210] [Electrolytes]

[0211] Electrolytes are disclosed in some embodiments of this application. The electrolyte in this application can be liquid, solid, or gel-like. Solid state refers to a solid electrolyte, liquid state to a liquid electrolyte, and gel-like state to a gel electrolyte. The lithium-ion battery of this application uses a liquid electrolyte, i.e., an electrolyte solution. This electrolyte solution contains an electrolyte salt and an organic solvent. The electrolyte salt can be any type conventional in the art, including, but not limited to, inorganic metal salts such as RClO4, RAsF6, RPF6, RBF4, RSbF6, RSO3F, RN(FSO2)2, etc.; fluorinated organometallic salts such as RCF3SO3, RN(FSO2)(CF3SO2), RN(CF3SO2)2, RN(C2F5SO2)2, cyclic 1,3-hexafluoropropane disulfonylimide lithium, cyclic 1,2-tetrafluoroethane disulfonylimide lithium, RN(CF3SO2)(C4F9S O2), RC(CF3SO2)3, RPF4(CF3)2, RPF4(C2F5)2, RPF4(CF3SO2)2, RPF4(C2F5SO2)2, RBF2(CF3)2, RBF2(C2F5)2, RBF2(CF3SO2)2, RBF2(C2F5SO2)2, etc.; and metal salts containing dicarboxylic acid complexes, such as lithium bis(oxalate)borate, lithium difluorooxalate borate, lithium tri(oxalate)phosphate, lithium difluorobis(oxalate)phosphate, lithium tetrafluoro(oxalate)phosphate, etc. Here, the metal and R include lithium ions or sodium ions.

[0212] According to some embodiments of this application, the concentration of the electrolyte salt in the electrolyte is 0.1 mol / L to 4 mol / L. In these embodiments, this application discloses that the concentration of the electrolyte salt is any one of 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.5 mol / L, 3.8 mol / L, and 4 mol / L, or any one of the above ranges.

[0213] As described above, the organic solvent comprises one or more of carboxylic acid esters, carbonates, and ethers. Specifically, the carboxylic acid esters comprise one or more of ethyl acetate (EA), methyl acetate (MA), ethyl propionate (EP), propyl acetate (PA), methyl propionate (MP), methyl butyrate (MB), ethyl butyrate (EB), and 1,4-butyrolactone (GBL); the carbonates comprise one or more of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), and fluoroethylene carbonate (FEC). The ethers comprise at least one of tetrahydrofuran, dimethyl tetrahydrofuran, tetrahydropyran, dimethyl tetrahydropyran, 1,2-dimethoxyethane, dipropylene glycol dimethyl ether, or dimethyl phthalate. The organic solvents of this application further include one or two of nitrile solvents and sulfone solvents. The nitrile solvents include one or more of acetonitrile (AN), glutaronitrile (GLN), and adiponitrile (ADN). The sulfone solvents include at least one or a combination of two of sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0214] According to some embodiments of this application, the electrolyte further comprises a film-forming stabilizer, which includes a positive electrode film-forming stabilizer and a negative electrode film-forming stabilizer. The positive electrode film-forming stabilizer comprises carbonate additives and / or sulfate additives. The carbonate additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC), and dioctyl carbonate (CC). The sulfate additives include cyclic sulfonate additives and / or sulfated hydrocarbon ester additives; further, the cyclic sulfonate additives include one or more of 1,3-propanesulfonate lactone (PS), propenesulfonate lactone (PES), and 3-fluoro-1,3-propanesulfonate lactone (FPS); the sulfated hydrocarbon ester additives include one or more of vinyl sulfate (DTD), diethyl sulfate (DES), and dimethyl sulfate (DMS). The negative electrode film-forming stabilizer comprises one or more of the following: boron lithium salt or sodium salt, phosphorus-containing lithium salt or sodium salt, and sulfur-containing lithium salt or sodium salt. The boron-containing lithium salt or sodium salt includes one or more of lithium tetrafluoroborate or sodium (LiBF4, NaBF4), lithium bis(oxalate)borate or sodium (LiBOB, NaBOB), and lithium bis(oxalate)borate or sodium (LiDFOB, NaDFOB). The phosphorus-containing lithium salt or sodium salt includes one or more of lithium difluorophosphate or sodium (LiPO2F2, NaPO2F2), lithium fluorophosphate or sodium (Li2PO3F, Na2PO3F), and lithium phosphate or sodium (Li3PO4, Na3PO4). The sulfur-containing lithium salt or sodium salt includes one or more of lithium fluorosulfonate or sodium (LiFSO3, NaFSO3), lithium sulfate or sodium (Li2SO4, Na2SO4), and lithium aminosulfonate or sodium (LiSO3NH2, NaSO3NH2).

[0215] In some embodiments, the electrolyte further includes an ionic liquid additive, wherein the cation of the ionic liquid additive comprises any one or more of nitrogen-containing ions and phosphorus-containing ions, and the anion of the ionic liquid additive comprises any one or more of halide ions, phosphate ions, borate ions, and sulfonamide anions.

[0216] In this application, the electrolyte serves as the carrier for ion transport in the battery, acting as a conduit for ions between the positive and negative electrodes. The type of electrolyte affects battery safety. Ionic liquid additives refer to salts added to the electrolyte in relatively small amounts, composed entirely of cations and anions, and existing in a liquid state at or near room temperature (25℃ ± 5℃). Ionic liquid additives possess high thermal stability and low volatility. Furthermore, they can enhance the stability of the negative electrode active material by forming a solid electrolyte interphase (SEI) film and improving its stability, thereby improving battery safety.

[0217] In some embodiments, the cation of the ionic liquid additive comprises 1-butyl-3-methylimidazolium ([Bmin]). + ), 1-benzyl-3-methylimidazolium ([Bzmin)) + ), 3-methyl-1-ethoxycarbonylmethylimidazolium ([Etmim) + ), 1-alkyl-3-methylimidazolium ([Cnmim) + ), 1-[(trimethylsilyl)methyl]benzotriazineonium ([SiMBIM) + N-alkyl-N-methylpiperidinium ([CnC1pip)) + ), 5-aza-onium-spiro[4.4]nonane([AS[mn]) + ), trihexyl(tetradecyl)phosphine ion ([Tf₂N) + ), tetrabutylphosphine ion ([Pnnnn) + ), n-Butyl-N-methylpyrrolidone ([Pyr 14 ] + One or more of the following, optionally tetrabutylphosphine ion or n-butyl-N-methylpyrrolidineonium.

[0218] In some embodiments, the anion of the ionic liquid additive includes chloride ions ([Cl-)). - ), bromide ions ([Br]) - ), iodide ions ([I) - ), hexafluorophosphate ([PF6]) - Tetrafluoroborate ([BF4]) - ), dicyandiamide anion ([N(CN)2)) - ), bis(fluorosulfonyl)imine anion ([FSI) - ), bis(trifluoromethanesulfonyl)imide ([TFSI) - One or more of the following, selected as hexafluorophosphate or bis(fluorosulfonyl)imine anions.

[0219] In some embodiments, the ionic liquid additive includes one or more of tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imine, n-butyl-N-methylpyrrolidine hexafluorophosphate, n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imine, 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imine, 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine, and 1-benzyl-3-methylimidazolium bis(fluorosulfonyl)imine, optionally tetrabutylphosphine hexafluorophosphate, tetrabutylphosphine bis(fluorosulfonyl)imine, n-butyl-N-methylpyrrolidine hexafluorophosphate, and n-butyl-N-methylpyrrolidine bis(fluorosulfonyl)imine.

[0220] The following will focus on the battery cell of this application with reference to specific embodiments.

[0221] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0222] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0223] This application may employ conventional inorganic chemistry techniques within the art. In the following examples, efforts have been made to ensure the accuracy of the figures used (including quantities, temperatures, reaction times, etc.), but some experimental errors and biases should be considered. Temperatures (in degrees Celsius) used in the following examples are expressed in °C, and pressures are at or near atmospheric pressure. All reagents were purchased from AR-grade suppliers, and all reactions were carried out under argon protection. Unless otherwise stated, all reagents were obtained commercially.

[0224] Experimental materials:

[0225] Positive electrode active materials, negative electrode active materials, porous fillers, etc. are all commercially available.

[0226] The performance parameters of the porous packing are shown in Table 1:

[0227] Table 1. Performance parameters of porous packing

[0228] Serial Number Average aperture Specific surface area Dv50 1-1 (Montmorillonite) 75nm <![CDATA[50m 2 / g]]> 20μm 1-2 (diatomaceous earth) 102nm <![CDATA[43m 2 / g]]> 45μm 1-3 (vermiculite) 54nm <![CDATA[78m 2 / g]]> 30μm

[0229] Preparation Example 1-1

[0230] A method for preparing a positive electrode sheet is provided, wherein the structure of the positive electrode sheet is as follows: Figure 9A The diagram shows that the porous material content in the edge region is uniformly distributed; the preparation process is as follows:

[0231] S1. Provide the first positive electrode slurry: 0.4Li2MnO3·0.6LiNi 0.5Mn 0.5 O2, conductive agent SP, and binder PVDF (polyvinylidene fluoride) are mixed in a weight ratio of 94:4:2, and solvent N-methylpyrrolidone is added. The mixture is stirred and mixed thoroughly to obtain the first positive electrode slurry. This first positive electrode slurry is used to make the first main positive electrode film layer.

[0232] S2, Provide the second positive electrode slurry: 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5 O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and montmorillonite (1-1 in Table 1) are mixed in a weight ratio of 93.5:4:2:0.5. Solvent N-methylpyrrolidone is added and the mixture is stirred and mixed thoroughly to obtain a second positive electrode slurry. This second positive electrode slurry is used to make an edge positive electrode film layer.

[0233] S3. A first positive electrode slurry is coated on both sides of the positive electrode current collector moving along the first direction to form a first main positive electrode film layer. A second positive electrode slurry is coated on the same side of the positive electrode current collector and on both sides of the first main positive electrode film layer to form an edge positive electrode film layer. The average coating thickness of the first main positive electrode film layer is h1, and the average coating thickness of the edge positive electrode film layer is h2. h1 / h2 = 1.1.

[0234] Furthermore, the coating width of the first main positive electrode film layer in the second direction is T2, and the coating width of the edge positive electrode film layers on both sides of the first main positive electrode film layer in the second direction is T1, where T1:T2=2:20, that is, the coating width T1 of the edge positive electrode film layer in the second direction is 10% of the coating width T2 of the first main positive electrode film layer in the second direction.

[0235] Preparation Examples 1-2

[0236] A method for preparing a positive electrode sheet is provided, which differs from the method in that:

[0237] S2, Provide the second positive electrode slurry: 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5 O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and vermiculite (1-3 in Table 1) were mixed in a weight ratio of 93.9:4:2:0.1; other aspects remained the same as in preparation example 1-1.

[0238] Preparation Examples 1-3

[0239] A method for preparing a positive electrode sheet is provided, which differs from the method in that:

[0240] S2, Provide the second positive electrode slurry: 0.4Li2MnO3·0.6LiNi 0.5 Mn0.5 O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and diatomaceous earth (1-2 in Table 1) were mixed in a weight ratio of 93:4:2:1; other aspects remained the same as in preparation example 1-1.

[0241] Comparative Preparation Example 1

[0242] A method for preparing a positive electrode sheet is provided, which differs from Preparation Example 1-1 in that the second positive electrode slurry does not contain porous materials, and the composition of the second positive electrode slurry is the same as that of the first positive electrode slurry. All other aspects are the same as in Preparation Example 1-1.

[0243] Comparative Preparation Example 2

[0244] A method for preparing a positive electrode sheet is provided, wherein the structure of the positive electrode sheet is as follows: Figure 6 This is to illustrate that no difference in coating thickness is set at the edge of the positive electrode film layer, and no porous filler is added, while other aspects remain the same as in preparation example 1-1.

[0245] Preparation Example 2-1

[0246] A method for preparing a positive electrode sheet is provided, which differs from the method in that:

[0247] S3. The ratio between the average coating thickness h1 of the first main positive electrode film layer and the average coating thickness h2 of the edge positive electrode film layer: h1 / h2=1.01;

[0248] The ratio between the coating width T1 of the edge positive electrode film on both sides of the first main positive electrode film in the second direction and the coating width T2 of the first main positive electrode film in the second direction is: T1:T2 = 1:20, that is, the coating width T1 of the edge positive electrode film in the second direction is 5% of the coating width T2 of the first main positive electrode film in the second direction. Other aspects are the same as in preparation example 1-1.

[0249] Preparation Example 2-2

[0250] A method for preparing a positive electrode sheet is provided, which differs from the method in that:

[0251] S3. The ratio between the average coating thickness h1 of the first main positive electrode film layer and the average coating thickness h2 of the edge positive electrode film layer: h1 / h2 = 1.15;

[0252] The ratio between the coating width T1 of the edge positive electrode film on both sides of the first main positive electrode film in the second direction and the coating width T2 of the first main positive electrode film in the second direction is: T1:T2 = 3:20, that is, the coating width T1 of the edge positive electrode film in the second direction is 15% of the coating width T2 of the first main positive electrode film in the second direction. Other aspects are the same as in preparation example 1-1.

[0253] Preparation Examples 2-3

[0254] A method for preparing a positive electrode sheet is provided, which differs from the method in that:

[0255] S3. The ratio between the average coating thickness h1 of the first main positive electrode film layer and the average coating thickness h2 of the edge positive electrode film layer: h1 / h2 = 1.1;

[0256] The ratio between the coating width T1 of the edge positive electrode film on both sides of the first main positive electrode film in the second direction and the coating width T2 of the first main positive electrode film in the second direction is: T1:T2 = 4:20, that is, the coating width T1 of the edge positive electrode film in the second direction is 20% of the coating width T2 of the first main positive electrode film in the second direction. Other aspects are the same as in preparation example 1-1.

[0257] Preparation Example 3-1

[0258] A method for preparing a positive electrode sheet is provided, wherein the structure of the positive electrode sheet is as follows: Figure 9D The diagram illustrates the content gradient distribution of porous material in the edge region; the preparation process is as follows:

[0259] S1. Provide the first positive electrode slurry: 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5 O2, conductive agent SP, and binder PVDF (polyvinylidene fluoride) are mixed in a weight ratio of 94:4:2, and solvent N-methylpyrrolidone is added. The mixture is stirred and mixed thoroughly to obtain the first positive electrode slurry. This first positive electrode slurry is used to make the first main positive electrode film layer.

[0260] S2. Providing a second positive electrode slurry: The second positive electrode slurry includes a second A sub-positive electrode slurry and a second B sub-positive electrode slurry, wherein the second A sub-positive electrode slurry comprises 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5 O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and montmorillonite (1-1 in Table 1) are mixed in a weight ratio of 93.2:4:2:0.8. This second B-sub cathode slurry includes 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and montmorillonite (1-1 in Table 1) were mixed in a weight ratio of 93.8:4:2:0.2;

[0261] S3. A first positive electrode slurry is coated on both sides of the positive electrode current collector moving along the first direction to form a first main positive electrode film layer. A second A sub-positive electrode slurry is coated on the same side of the positive electrode current collector and on both sides of the first main positive electrode film layer to form a first sub-edge positive electrode film layer. A second B sub-positive electrode slurry is coated to form a second sub-edge positive electrode film layer. The ratio between the coating width t11 of the first sub-edge positive electrode film layer in the second direction and the coating width t12 of the second sub-edge positive electrode film layer in the second direction is t11:t12 = 1:1.

[0262] Furthermore, the coating width of the first main positive electrode film layer in the second direction is T2, and the coating width of the edge positive electrode film layers on both sides of the first main positive electrode film layer in the second direction is T1, T1:T2=2:20, that is, the coating width T1 of the edge positive electrode film layer in the second direction is 10% of the coating width T2 of the first main positive electrode film layer in the second direction.

[0263] Meanwhile, the average coating thickness of the first main positive electrode film is h1, and the average coating thickness of the edge positive electrode film is h2; h1 / h2 = 1.1. Other aspects remain the same as in Preparation Example 1-1.

[0264] Preparation Example 3-2

[0265] A method for preparing a positive electrode sheet is provided, wherein the structure of the positive electrode sheet is as follows: Figure 9D The illustration shows the content gradient distribution of porous material in the edge region; the difference between this preparation example and preparation example 3-1 is that the second positive electrode slurry includes a second A sub-positive electrode slurry and a second B sub-positive electrode slurry, and the second A sub-positive electrode slurry includes 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5 O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and montmorillonite (1-1 in Table 1) are mixed in a weight ratio of 93.8:4:2:0.2. This second B-sub cathode slurry includes 0.4Li2MnO3·0.6LiNi 0.5 Mn 0.5 O2, conductive agent SP, binder PVDF (polyvinylidene fluoride), and montmorillonite (1-1 in Table 1) were mixed in a weight ratio of 93.2:4:2:0.8; all other aspects remained the same as in preparation example 3-1.

[0266] The parameters of each positive electrode are listed in Table 2 below.

[0267] Table 2-1 Parameter List of Positive Electrode

[0268]

[0269] Table 2-2 Parameter List of Positive Electrode

[0270]

[0271] Example 1-1

[0272] A method for preparing a battery cell is provided, and the schematic diagram of the electrode structure of the battery cell is shown below. Figure 11 Indication.

[0273] The preparation method of the above-mentioned battery cell includes the following preparation process:

[0274] Provided is the positive electrode sheet prepared in Example 1-1.

[0275] Preparation of negative electrode sheet:

[0276] Artificial graphite, conductive agent SP, stabilizer carboxymethyl cellulose, and binder SBR are dispersed in deionized water at a mass ratio of 95:1.0:1.5:2.5 to form a negative electrode slurry. The negative electrode slurry is then uniformly coated onto the surface of a copper foil. The edges of the negative electrode film coating also have thinning zones. The structure is as follows: Figure 10 The diagram illustrates the process of drying using a nine-section drying oven with temperature settings of 100℃ / 100℃ / 95℃ / 85℃ / 85℃ / 80℃ / 80℃ / 80℃ / 60℃, followed by compaction using a cold press.

[0277] Provide isolation components:

[0278] A porous polyethylene (PE) membrane with a thickness of 13 μm is used as the separator.

[0279] Electrolyte provided:

[0280] In an argon atmosphere glove box with a water content of <10ppm, EC (ethylene carbonate), PC (polycarbonate), and DMC (dimethyl carbonate) were mixed in a weight ratio of EC:PC:DMC = 3:3:3. Then, LiPF6, VC, DTD, and PS were added and stirred until homogeneous to obtain an electrolyte. The concentration of LiPF6 in the lithium-ion battery electrolyte was 1 mol / L, and the mass percentages of VC, DTD, and PS were 3%, 1%, and 1%, respectively.

[0281] Assemble individual battery cells:

[0282] The positive electrode, separator, and negative electrode are wound in sequence, as follows: Figure 5The diagram illustrates how the separator is positioned between the positive and negative electrodes to provide isolation, and how these electrodes are assembled to form a wound bare cell. The wound bare cell is then placed in an outer packaging shell, dried, and injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a single battery cell is obtained.

[0283] Examples 1-2

[0284] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Examples 1-2, and other aspects are the same as in Examples 1-1.

[0285] Examples 1-3

[0286] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Examples 1-3, and other aspects are the same as in Examples 1-1.

[0287] Comparative Example 1

[0288] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Comparative Preparation Example 1, and is otherwise identical to that in Examples 1-1.

[0289] Comparative Example 2

[0290] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Comparative Preparation Example 2, and is otherwise identical to that in Examples 1-1.

[0291] Example 2-1

[0292] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Preparation Example 2-1, and other aspects are the same as in Example 1-1.

[0293] Example 2-2

[0294] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Preparation Example 2-2, and other aspects are the same as in Example 1-1.

[0295] Example 2-3

[0296] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Examples 2-3, and other aspects are the same as in Examples 1-1.

[0297] Example 3-1

[0298] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Preparation Example 3-1, and other aspects are the same as in Example 1-1.

[0299] Example 3-2

[0300] A method for preparing a battery cell is provided, wherein the battery cell uses the positive electrode sheet prepared in Preparation Example 3-2, and other aspects are the same as in Example 1-1.

[0301] Example 4

[0302] A method for preparing a battery cell is provided. The separator of the battery cell includes: using a porous polyethylene (PE) membrane with a thickness of 13 μm as a base membrane, forming an organic polymer coating (PE) on both sides of the base membrane, wherein the edge region of the organic polymer coating contains 0.5% by mass of porous material (1-1 in Table 1); the orthographic projection of the edge region of the positive electrode film layer on the above coating completely overlaps with the edge region of the coating, and other aspects remain the same as in Example 1-1.

[0303] Example 5

[0304] A method for preparing a battery cell is provided, wherein the edge region of the negative electrode sheet of the battery cell is not thinned, that is, the coating thickness of the main body region and the edge region of the negative electrode film is the same, and other aspects are the same as those in Example 1-1.

[0305] The performance of the batteries prepared according to the above embodiments and comparative examples is tested as follows:

[0306] (1) The surface density of the positive electrode film:

[0307] During the preparation of the positive electrode film, the surface density of the edge region and the main region of the positive electrode film can be obtained according to the formula: surface density = weight of a single film layer / area of ​​a single film layer.

[0308] For a single battery cell, at 25°C, the battery is fully charged (charged to 4.4V at a constant current of 1 / 3C). The battery is then disassembled to remove the positive electrode sheet. The positive current collector and the positive electrode film are cut using a cryo-focused ion beam to obtain the positive electrode film. The positive electrode film is then finely sliced ​​at different width positions (second direction) using a cryo-focused ion beam (FIB) to obtain the areal density of the edge region and the main region of the positive electrode film. The weight and area of ​​each different region are tested, and the areal density is calculated using the above-mentioned formula.

[0309] (2) Battery CB value:

[0310] The CB value of a battery, also known as the Cell Balance value, is calculated as follows:

[0311]

[0312] The specific capacity of the positive / negative electrode active materials needs to be determined through coin cell testing. The testing procedure is as follows:

[0313] (2.1) Making a button cell battery:

[0314] a. Solution preparation and stirring: Take a clean container and add N-methylpyrrolidone, of which 170g of N-methylpyrrolidone is prepared for the positive electrode slurry and 150g of N-methylpyrrolidone is prepared for the negative electrode slurry; place the container with the weighed N-methylpyrrolidone solvent into a high-speed stirring rack and fix it, and stir at 600rpm for 1h.

[0315] b. Additives and stirring: Weigh out 6g of PVDF and 6g of SP for the positive electrode solvent; weigh out 9g of PVDF and 2.7g of SP for the negative electrode solvent; adjust the speed to 600rpm; first, slowly add PVDF to the container, adjust to 2200rpm, and after the PVDF is completely dissolved (15-20min), reduce the speed to 600rpm and add SP, adjust the speed to 2200rpm and stir until the slurry is free of particles and smooth and bright (40-50min); after the SP and PVDF solutions are stirred until they are free of particles, remove them, weigh them and put them into a degassing machine (16min), cover the degassing machine, set the program, and start the degassing machine until it ends. The positive and negative electrode solutions are now prepared and sealed and stored in a dry room for later use.

[0316] c. Addition and stirring of main powder: Weigh 6.0g of positive electrode solution, then add 3.20g of positive electrode active material (0.4Li2MnO3·0.6LiNi). 0.5 Mn 0.5 Weigh 4.92g of negative electrode solution, add 4.58g of negative electrode active material (artificial graphite), cover the container, and place it in the mixer along with the clamp. Set the mixing process to 900rpm for pre-stirring for 60s; then stir at 2200rpm for 8-13min.

[0317] d. Coating and drying: Spray ethanol evenly on a clean and flat glass plate, attach a wrinkle-free Al / Cu current collector foil to the surface, place the glass plate with the current collector on an automatic coating machine and clamp it. Mark the order number and name in the blank space at the top with a Marking Note. Spread the slurry evenly on the front end of the current collector, place the doctor blade at the front end of the slurry, and turn on the coating machine to make the doctor blade scrape at a uniform speed of 3cm / s to ensure no air bubbles, a smooth surface, and a mirror finish. Let the film air dry naturally for 1-2 minutes, and then put the coated film together with the glass plate into a 100℃ forced-air drying oven. The drying time is controlled at 2 hours.

[0318] e. Cold pressing of electrode sheets: The compaction density is controlled to be 2.1 g / cm³ for the positive electrode film. 3 The negative electrode film thickness is 1.5 g / cm³. 3 ;

[0319] f. Punching, weighing, and baking: Punch with the current collector facing upwards, apply force at a uniform speed, and quickly press down the pressure bar to punch out small round discs with a diameter of 14mm. Release the pressure bar, change the position of the disc, and continue punching. Punch at least 6 discs for each sample. Then, place the discs into a lint-free paper bag with tweezers. Finally, clean the punching machine with lint-free paper soaked in alcohol. Place a lint-free paper in the center of the weighing platform, gently pick up the discs with tweezers, place them on the weighing platform, and weigh them. Place the weighed discs into a vacuum drying oven.

[0320] g. Electrode Fabrication: Remove the vacuum-baked electrode sheets, pack them in a PE bag, and place them in the glove box transition chamber. Place the prepared positive and negative electrode shells, nickel foam, separator film, lint-free paper, and tweezers into the glove box transition chamber. In the glove box, lay the negative electrode shell flat on a sheet of lint-free paper, and place a nickel mesh inside the negative electrode shell with the convex side facing up. Use a brush to remove the surface oxide film from the prepared lithium sheet, and then place it on the nickel mesh with the brushed side facing up. Inject electrolyte into the positive and negative electrodes respectively, using a 2.5ml medical syringe to add 5-7 drops of electrolyte. Add electrolyte and then place the separator on the lithium sheet, ensuring it is concentric with the negative electrode shell, nickel foam, and lithium sheet. Place the electrode in the center of the separator, one side only, with the active material facing down. Finally, smoothly cover it with the positive electrode shell. For the clasp sealing: place the battery with the negative electrode on top in the groove of the sealing machine, placing a piece of lint-free paper on top. Use insulated tweezers to remove the clasp from the sealing machine, place it in the corresponding lint-free paper bag, remove it from the glove box, and place it in a constant temperature room to stand for 5 hours. The positive electrode clasp is made in the same way.

[0321] (2.2) Capacity test:

[0322] Place the coin cell on the test capacity channel to confirm the positive and negative charging and discharging process:

[0323] Positive electrode charge / discharge process:

[0324] After standing for 3 hours, charge at a constant current of 0.1C to the cutoff voltage of 4.5V, and charge at a constant voltage of 4.5V until the current drops from 0.1C to 0.05A. Then discharge at a constant current of 0.1C to 2.5V. The amount of electricity discharged by constant current discharge divided by the weight of the positive electrode active material is the discharge capacity.

[0325] Negative electrode charging and discharging process:

[0326] After standing for 5 hours, discharge at a constant current of 0.05C with a cutoff voltage of 0.005V. After standing for 30 minutes, discharge at a constant current of 0.05A to 0V. After standing for 30 minutes, discharge at a constant current of 0.01A to 0V. After standing for 5 hours, charge at a current of 0.1C with a cutoff voltage of 2.5V. The discharge capacity of the negative electrode material is the amount of charge released during the discharge process divided by the weight of the negative electrode active material.

[0327] (3) Expansion rate of the edge region of the positive electrode film:

[0328] In the initial state, the thickness of the positive electrode film edge region of a single battery cell is h2 (the thickness after cold pressing);

[0329] At 25℃, the battery is fully charged (charged to 4.4V at a constant current of 1 / 3C). The battery is disassembled and the positive electrode is removed. The positive electrode sample is finely sliced ​​at different width positions (second direction) of the positive electrode film using cryo-focused ion beam (FIB) (generally, the thickness of the positive electrode film edge region at 5 different positions in the width direction is obtained) to obtain the average thickness of the positive electrode film edge region, which is h2'. Then, the expansion rate of the positive electrode film edge region = (h2'-h2) / h2×100%.

[0330] Table 3-1 Battery Performance List

[0331]

[0332]

[0333] As can be seen from the preparation examples and comparative examples, this application adds porous material to the edge region of the positive electrode film layer, causing the edge region of the positive electrode film layer to expand in volume, thereby reducing the distance between the edge regions of adjacent positive electrode film layers. At the same time, since the areal density of the edge region of the positive electrode film layer is less than the areal density of the first main body region, the CB value of the battery at the edge position is also increased.

[0334] (4) Test the capacity retention rate of the battery after 500 cycles at 25°C:

[0335] Under constant temperature of 25℃, the capacitor is charged to 4.4V with a constant current of 1C, then charged to 0.05C with a constant voltage of 4.4V, and then discharged to 2.5V with a constant current of 1C. The discharge specific capacity of the first cycle (Cd1) is obtained. This charging and discharging process is repeated until the 500th cycle, and the discharge specific capacity after 500 cycles is denoted as Cdn.

[0336] Capacity retention (%) = Discharge specific capacity after 500 cycles (Cdn) / Discharge specific capacity in the first cycle (Cd1).

[0337] (5) Determination and analysis of lithium deposition on the surface of the negative electrode after the battery has been cycled 500 times at 25°C:

[0338] After cycling the battery 500 times according to the above cycling method, the battery was disassembled and the positive and negative electrode plates were further separated. The lithium deposition on the surface of the negative electrode plate was observed using a scanning electron microscope, especially the surface lithium deposition in the edge area of ​​the negative electrode plate.

[0339] The judgment criteria are shown in the table below;

[0340] Table 3-2 Determination of Lithium Deposition Levels on the Surface of Negative Electrode Sheets

[0341]

[0342] Table 3-3 Battery Performance List

[0343]

[0344]

[0345] As can be seen from the embodiments of this application, this application adds porous material to the edge region of the positive electrode film layer. Compared with the design method of the comparative example without adding porous material, the design method provided by this application is beneficial to improving the cycle life of the battery. At the same time, it can also reduce the probability of lithium plating on the electrode.

[0346] Further, in conjunction with Examples 1-1, 2-1 to 2-3, it can be seen that the coating width and coating thickness of the positive electrode film edge region affect the cycle life of the battery. Generally speaking, within a certain range, increasing the coating width and coating thickness of the positive electrode film edge region is beneficial to increasing the cycle life of the battery, but it also brings the risk of increased lithium plating probability. The design method provided in this application is beneficial to controlling the above-mentioned lithium plating probability.

[0347] As can be seen from Examples 1-1, 3-1 and 3-2, the positive electrode active material is further divided into sections in the edge region of the positive electrode film to make different regions contain different amounts of porous material. This design method is beneficial to further increase the cycle life of the battery.

[0348] As can be seen from Examples 1-1 and 4, this application selects to simultaneously provide porous materials on the edge region of the positive electrode film and the edge region of the coating of the separator, so that sufficient electrolyte can be stored at the edge position of the positive electrode film, thereby further improving the cycle life of the battery.

[0349] As can be seen from Examples 1-1 and 5, although the negative electrode film layer can be increased to a certain extent by not thinning it, the cycle life of the battery is actually reduced. This may be because the non-thinning method has brought some side effects.

[0350] In summary, the design method provided in this application is beneficial to improving the cycle life of the battery.

[0351] 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 single battery cell, characterized in that: This includes a stacked positive electrode, a separator, and a negative electrode; The positive electrode includes a positive current collector and a positive film layer located on at least one side surface of the positive current collector; The positive electrode film layer includes a first main region and an edge region; The first main body region includes a first positive electrode active material; The edge region includes a second positive electrode active material and a porous material; the porous material includes any one or more of montmorillonite, diatomaceous earth, and vermiculite; The surface density of the first main body region is greater than the surface density of the edge region; The mass percentage content of the first positive electrode active material in the first main body region is greater than the mass percentage content of the second positive electrode active material in the edge region; The separator includes a coating disposed toward the positive electrode film layer; The coating includes a second main area and an edge area. The orthographic projection of the edge region of the positive electrode film onto the coating at least partially overlaps with the edge region of the coating. The edge region of the coating comprises porous material.

2. The battery cell according to claim 1, characterized in that: The average pore size of the porous material is 50 nm to 10 μm. and / or; The specific surface area of ​​the porous material is 20m². 2 / g~110m 2 / g.

3. The battery cell according to claim 1, characterized in that: In the edge region of the positive electrode film, the mass percentage content of the porous material is 0.1% to 1.0%.

4. The battery cell according to claim 1, characterized in that: The edge region of the positive electrode film extends along the first main body region in a first direction and is arranged in a second direction; The first direction intersects with the second direction; Along the second direction, the edge region of the positive electrode film layer includes an A surface and a B surface disposed opposite to each other, and the distance between the A surface and the B surface is T1; Along the second direction, the first main body area includes a C-surface and a D-surface disposed opposite each other, and the distance between the C-surface and the D-surface is T2; The following condition is met: T1:T2 = (1~3):

20.

5. The battery cell according to claim 1, characterized in that: The edge region of the positive electrode film extends along the first main body region in a first direction and is arranged in a second direction; The first direction intersects with the second direction; Along the second direction, the edge region of the positive electrode film layer includes an A surface and a B surface disposed opposite to each other, the B surface being close to the first main body region, and the distance between the A surface and the B surface being T1; The region formed by extending from surface B to the 0.1×T1 position is denoted as the first sub-edge region, and the region formed by extending from surface A to the 0.1×T1 position is denoted as the second sub-edge region. In the first sub-edge region of the positive electrode film layer, the mass percentage content of the porous material is w1; In the second sub-edge region of the positive electrode film, the mass percentage content of the porous material is w2; The condition w1 is greater than w2.

6. The battery cell according to claim 1, characterized in that: The edge region of the positive electrode film extends along the first main body region in a first direction and is arranged in a second direction; The first direction intersects with the second direction; Along the second direction, the edge region of the positive electrode film layer includes a first sub-edge positive electrode film layer and a second sub-edge positive electrode film layer; the first sub-edge positive electrode film layer and the second sub-edge positive electrode film layer are located on the same side of the first main body region; Along the second direction, the first sub-edge positive electrode film layer includes a B-side and an M-side, the B-side being close to the first main body region, and the distance between the B-side and the M-side being t11; Along the second direction, the second sub-edge positive electrode film layer includes an A-plane and an N-plane, and the distance between the A-plane and the N-plane is t12; satisfying t11:t12=(0.5~1):(0.5~1); In the first sub-edge positive electrode film layer, the mass percentage content w1 of the porous material is 0.5%~1%; In the second sub-edge positive electrode film layer, the mass percentage content w2 of the porous material is 0.1%~0.3%.

7. The battery cell according to claim 1, characterized in that: The areal density A1 of the first main region of the positive electrode film is 200 mg / 1540.25 mm². 2 ~400mg / 1540.25mm 2 ; and / or; The areal density A2 of the edge region of the positive electrode film is 170 mg / 1540.25 mm. 2 ~380mg / 1540.25mm 2 .

8. The battery cell according to claim 1, characterized in that: The negative electrode sheet includes a negative current collector and a negative electrode film layer located on at least one side surface of the negative current collector; The negative electrode film layer includes a third main region and an edge thinning region; The orthogonal projection of the edge thinning region of the negative electrode film onto the positive electrode film at least partially overlaps with the edge region of the positive electrode film.

9. A method for preparing a battery cell according to claim 1, characterized in that: The process includes preparing the positive electrode sheet, as follows: Provide the first positive electrode slurry: including positive electrode active materials; Provide a second positive electrode slurry: including positive electrode active materials and porous materials; A first positive electrode slurry is coated on at least one side surface of a positive current collector moving along a first direction to form a first main positive electrode film layer, and a second positive electrode slurry is coated to form an edge positive electrode film layer, wherein the edge positive electrode film layer and the first main positive electrode film layer are arranged in a second direction. The first direction intersects with the second direction; The coating thickness of the first main positive electrode film is greater than the coating thickness of the edge positive electrode film.

10. The preparation method according to claim 9, characterized in that: The coating thickness of the first main positive electrode film layer is h1, and the coating thickness of the edge positive electrode film layer is h2; The following conditions must be met: h1 / h2 = 1.01~1.

15.

11. The preparation method according to claim 9 or 10, characterized in that: The edge positive electrode film layer includes an E-surface that is attached to the positive electrode current collector and an F-surface that is opposite to the E-surface; Along the second direction, the F surface is an inclined surface that gradually approaches the E surface; The average distance between the E-plane and the F-plane is the coating thickness h2 of the edge positive electrode film.

12. A battery device, characterized in that: Includes the battery cell according to any one of claims 1 to 8 or the battery cell prepared by any one of claims 9 to 11.

13. An electrical device, characterized in that: Includes the battery device as described in claim 12.

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