A battery cell, a method for manufacturing the same, a battery device, and a power-using device

Abstract

This application provides a battery cell, its preparation method, a battery device, and an electrical device, belonging to the field of battery technology. The negative electrode film layer of the battery cell includes a first edge region, a main body region, and a second edge region distributed sequentially along the width direction. The surface layer of the main body region has an OI value of 5.6~33.1 under X-ray diffraction, and the first edge region and / or the second edge region have an OI value of 0.1~1.2 under X-ray diffraction. This application increases the floating resistance of the bottom binder and lengthens the floating path of the bottom binder by arranging most of the negative electrode active materials in at least the surface layer of the main body region laterally, thereby reducing the amount of binder floating. At the same time, by arranging most of the negative electrode active materials in the first edge region and / or the second edge region longitudinally, this not only prevents the binder from floating to the edge, but also shortens the ion transport path in the edge region of the negative electrode sheet, improves the dynamics of the negative electrode sheet edge, and reduces lithium plating in the edge region.

Description

Technical Field

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

[0002] In recent years, with the increasingly widespread application of lithium-ion batteries, they have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. Due to the significant development of lithium-ion batteries, higher requirements have been placed on their energy density, cycle performance, and safety performance. Furthermore, due to the increasingly limited selection of positive electrode active materials, high-nickel positive electrode active materials are considered the best choice to meet high energy density requirements.

[0003] During the drying process of the negative electrode sheet, the solvent in the negative electrode slurry easily carries away the binder during evaporation, causing the binder to float and accumulate at the edges. This results in uneven distribution of the binder in the negative electrode film layer, ultimately leading to a negative electrode sheet with abundant binder on the surface and edges, while the lower layers have less binder. Binder floating not only affects production efficiency but also causes problems such as hindered electron and ion transport, localized stress concentration, and deterioration of adhesion, severely restricting the battery's fast-charging performance. Edge binder accumulation leads to poor dynamics at the edges of the negative electrode sheet, causing temperature increases during cycling and facilitating lithium plating, thus affecting the battery's cycle performance. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell and a method for preparing the same, a battery device and an electrical device, which can improve the problems of binder floating and edge enrichment, thereby improving the fast charging performance and cycle performance of the battery cell.

[0005] To achieve the above objectives, a first aspect of this application provides a battery cell comprising a negative electrode sheet, the negative electrode sheet comprising a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode film layer comprising a first edge region, a main body region and a second edge region sequentially distributed along the width direction, wherein at least the surface layer of the main body region has a CO004 / C110 ratio of 5.6 to 33.1 under X-ray diffraction, and the first edge region and / or the second edge region have a CO004 / C110 ratio of 0.1 to 1.2 under X-ray diffraction.

[0006] Therefore, the battery cell of this application, by ensuring that the C004 / C110 ratio in at least the surface layer of the intermediate main region is within the aforementioned range under X-ray diffraction, allows a majority of the negative electrode active materials in at least the surface layer of the intermediate main region to be arranged laterally or tending to be laterally parallel to the current collector surface, thereby forming a barrier, increasing the resistance to the buoyancy of the underlying binder, lengthening the buoyancy path of the underlying binder, and thus reducing the amount of binder buoyant. Simultaneously, by ensuring that the C004 / C110 ratio in the first edge region and / or the second edge region is within the aforementioned range under X-ray diffraction, allows a majority of the negative electrode active materials in the first edge region and / or the second edge region to be arranged longitudinally or tending to be longitudinally perpendicular to the current collector surface. This not only prevents the binder from floating to the edges but also shortens the ion transport path in the edge region of the negative electrode sheet, improves the kinetics of the negative electrode sheet edge, and reduces lithium plating in the edge region. The fast-charging performance and cycle performance of the battery cell of this application are simultaneously improved.

[0007] In any embodiment, the width ratio of the main body region to the width ratio of the first edge region is 5 to 40, and / or the width ratio of the main body region to the width ratio of the second edge region is 5 to 40. By ensuring that the width ratio of the main body region to the width ratio of the first edge region, and / or the width ratio of the main body region to the width ratio of the second edge region, is within the above range, this application can reduce the amount of adhesive floating up and prevent the adhesive from floating to the edge, thereby simultaneously improving the fast charging performance and cycle performance of the battery cell.

[0008] In any embodiment, the density ratio of the main region to the density ratio of the first edge region is 0.05 to 2, and / or the density ratio of the main region to the density ratio of the second edge region is 0.05 to 2.

[0009] In any embodiment, the width of the first edge region and / or the second edge region is 5 mm to 40 mm. This application, by making the C004 / C110 ratio of the first edge region and / or the second edge region with the above-mentioned width in the negative electrode sheet 0.1 to 1.2 under X-ray diffraction, can effectively prevent the binder from floating to the edge, improve the dynamics of the negative electrode sheet edge, and reduce lithium plating in the edge region.

[0010] In any embodiment, the aspect ratio of the negative electrode active material is 1.2 to 4.8. This application selects negative electrode active materials with aspect ratios within the above range, which are generally sheet-like or fibrous. This allows the negative electrode active material to form a denser barrier when arranged laterally, increasing the resistance to the bottom binder's buoyancy and extending the bottom binder's buoyancy path, thereby reducing the amount of binder buoyed. Furthermore, it allows the negative electrode active material to form a larger blocking surface when arranged longitudinally, better preventing the binder from floating to the edges, improving the dynamics at the edge of the negative electrode sheet, and reducing lithium plating in the edge region.

[0011] In any embodiment, the negative electrode active material may be in the form of sheets or fibers, and / or the negative electrode active material may include at least one of carbon materials, silicon-based materials, metal oxides and metal sulfides.

[0012] In any embodiment, the surface adhesive floating amount in the main body area is 0.1% to 40%, and the surface adhesive floating amount ratio = (surface adhesive content - bottom adhesive content) / bottom adhesive content, and / or; the edge adhesive enrichment amount in the first edge area is 0.1% to 40%, and the edge adhesive enrichment amount in the second edge area is 0.1% to 40%, and the edge adhesive enrichment amount ratio = (edge ​​adhesive content - bottom adhesive content) / bottom adhesive content.

[0013] In any embodiment, the main body region includes at least two film layers. Along the thickness direction of the negative electrode film layer, the density of the at least two film layers decreases in a gradient, and the density of the film layer closer to the negative electrode current collector is greater than the density of the film layer farther away from the negative electrode current collector. On the one hand, by making the density of the film layer closer to the negative electrode current collector in the main body region higher, the negative electrode active material in the film layer closer to the negative electrode current collector can be arranged more densely. This not only increases the contact area between the binder and the negative electrode active material, resulting in more binding sites for the binder and the negative electrode active material, but also helps to improve the compaction density of the negative electrode sheet, thereby providing high energy density. On the other hand, by making the density of the film layer farther away from the negative electrode current collector in the main body region lower, the negative electrode active material in the film layer farther away from the negative electrode current collector can be arranged more loosely, thereby forming transverse channels parallel to the surface of the current collector after drying. These transverse channels are beneficial for improving the liquid retention capacity during liquid creep and circulation.

[0014] In any embodiment, the density ratio of any two adjacent membrane layers in at least two membrane layers is 1.05 to 1.3.

[0015] In any embodiment, the main body region includes a first film layer and a second film layer. The first film layer is bonded to the negative electrode current collector, and the second film layer is bonded to the first film layer. The ratio of C004 / C110 of both the first film layer and the second film layer is 5.6 to 33.1 under X-ray diffraction, and the density of the first film layer is greater than that of the second film layer. This application achieves this by ensuring that the C004 / C110 ratio of the first and second films in the main body region is within the aforementioned range under X-ray diffraction, and that the density of the first film is greater than that of the second film. In both films, most of the negative electrode active materials are arranged laterally or tend to be laterally aligned, thus forming a barrier, increasing the resistance to the bottom binder's buoyancy, and extending the bottom binder's buoyancy path. The higher density of the first film near the negative electrode current collector allows for a more compact arrangement of the negative electrode active materials, increasing the contact area between the binder and the negative electrode active materials, thus increasing the number of binding sites and improving the compaction density of the negative electrode sheet, thereby providing high energy density. Conversely, the lower density of the second film away from the negative electrode current collector allows for a looser arrangement of the negative electrode active materials, resulting in the formation of transverse channels parallel to the current collector surface after drying. These transverse channels improve the liquid retention capacity during liquid creep and circulation.

[0016] In any embodiment, the thickness ratio of the second film layer to the first film layer is 0.01 to 50, and / or; the density ratio of the second film layer to the first edge region is greater than or equal to 0.01 and less than 1.5, and / or; the density ratio of the second film layer to the second edge region is greater than or equal to 0.01 and less than 1.5, and / or; the density ratio of the first film layer to the first edge region is 1 to 1.5, and / or; the density ratio of the first film layer to the second edge region is 1 to 1.5.

[0017] In any embodiment, the main body region includes a first film layer and a second film layer. The first film layer is bonded to the negative electrode current collector, and the second film layer is bonded to the first film layer. The CO004 / C110 ratio of the first film layer under X-ray diffraction is 0.1 to 1.2, and the CO004 / C110 ratio of the second film layer under X-ray diffraction is 5.6 to 33.1. This application ensures that the CO004 / C110 ratios of the first and second film layers in the main body region are both within the above ranges. In the first film layer near the negative electrode current collector, most of the negative electrode active materials are arranged longitudinally or tend to be longitudinally aligned. This facilitates a denser arrangement of the negative electrode active materials in the first film layer, increasing the compaction density of the negative electrode sheet and thus providing a high energy density. In the second film layer, most of the negative electrode active materials are arranged laterally or tend to be laterally aligned, thereby forming a barrier, increasing the buoyancy resistance of the underlying binder, and extending the buoyancy path of the underlying binder.

[0018] In any embodiment, the density of the first film layer is greater than the density of the second film layer, and / or; the thickness ratio of the second film layer to the first film layer is 0.3 to 50, and / or; the density ratio of the second film layer to the first edge region is 0.05 to 1.5, and / or; the density ratio of the second film layer to the second edge region is 0.05 to 1.5, and / or; the density ratio of the first edge region to the first film layer is 1 to 1.5, and / or; the density ratio of the second edge region to the first film layer is 1 to 1.5.

[0019] The second aspect of this application provides a method for preparing a battery cell, comprising: dividing at least one side of a negative electrode current collector into a first edge portion, a main body portion, and a second edge portion along the width direction; disposing of a first slurry in the first edge portion and the second edge portion; and disposing of a second slurry in the main body portion to obtain a negative electrode precursor; placing the negative electrode precursor in a magnetic field environment for magnetic field induction treatment, wherein the magnetic field direction in the magnetic field environment where the first slurry is located makes an angle of 60° to 120° with the negative electrode current collector, and the magnetic field direction in the magnetic field environment where the second slurry is located makes an angle of -30° to 30° with the negative electrode current collector; and performing drying and cold pressing treatment after completing the magnetic field induction treatment.

[0020] Therefore, the battery cell preparation method of this application, by placing the first slurry and the second slurry in a magnetic field environment for magnetic field induction treatment, and setting the angle between the magnetic field direction of the first slurry and the negative electrode current collector in the magnetic field environment to be 60°~120° and the angle between the magnetic field direction of the second slurry and the negative electrode current collector in the magnetic field environment to be -30°~30°, can induce the negative electrode active materials in the first slurry and the second slurry to oriented, so that most of the negative electrode active materials in the middle main body are arranged laterally or tending to be laterally parallel to the surface of the current collector, thereby forming a barrier, increasing the floating resistance of the bottom binder, lengthening the floating path of the bottom binder, and thus reducing the amount of binder floating; at the same time, most of the negative electrode active materials in the first edge part and / or the second edge part are arranged longitudinally or tending to be longitudinally perpendicular to the surface of the current collector, which can not only prevent the binder from floating to the edge, but also shorten the ion transport path in the edge region of the negative electrode sheet, improve the dynamics of the negative electrode sheet edge, and reduce lithium deposition in the edge region. The fast charging performance and cycle performance of the battery cell of this application are improved simultaneously.

[0021] The third aspect of this application provides a method for preparing a battery cell, comprising: dividing at least one side of a negative electrode current collector into a first edge portion, a main body portion, and a second edge portion along the width direction; setting a first slurry in the first edge portion and the second edge portion to obtain a first negative electrode precursor; placing the first negative electrode precursor in a magnetic field environment for magnetic field induction treatment, wherein the magnetic field direction of the magnetic field environment in which the first slurry is located makes an angle of 60° to 120° with the negative electrode current collector; and drying to obtain a second negative electrode precursor; then sequentially setting at least two types of negative electrode slurry in the main body portion of the second negative electrode precursor; after setting each type of negative electrode slurry, placing it in or not placing it in a magnetic field environment for magnetic field induction treatment; drying and then setting another type of negative electrode slurry, until all negative electrode film layers are set and dried; and at least the negative electrode slurry set on the surface layer is placed in a magnetic field environment in which the magnetic field direction makes an angle of -30° to 30° with the negative electrode current collector for magnetic field induction treatment.

[0022] Therefore, the battery cell preparation method of this application, by placing the first slurry and the negative electrode slurry in a magnetic field environment for magnetic field induction treatment, and setting the angle between the magnetic field direction of the magnetic field environment where the first slurry is located and the negative electrode current collector to be 60°~120°, and the angle between the magnetic field direction of the magnetic field environment where the negative electrode slurry at least located on the surface is located and the negative electrode current collector to be -30°~30°, can induce the negative electrode active materials in the first slurry and at least the negative electrode slurry on the surface to oriented, so that most of the negative electrode active materials in the middle main area at least the surface are arranged laterally or tend to be laterally parallel to the surface of the current collector, thereby forming a barrier, increasing the floating resistance of the bottom binder, extending the floating path of the bottom binder, and thus reducing the amount of binder floating; at the same time, it causes most of the negative electrode active materials in the first edge part and / or the second edge part to be arranged longitudinally or tend to be longitudinally perpendicular to the surface of the current collector, which can not only prevent the binder from floating to the edge, but also shorten the ion transport path in the edge region of the negative electrode sheet, improve the dynamics of the negative electrode sheet edge, and reduce lithium deposition in the edge region. The fast charging performance and cycle performance of the battery cells in this application are improved simultaneously.

[0023] A fourth aspect of this application provides a battery comprising the battery cell described in the above embodiments or a battery cell prepared according to the preparation method of the battery cell described in the above embodiments.

[0024] The fifth aspect of this application provides an electrical device comprising a battery cell or a battery device as described in the above embodiments, wherein the battery cell or battery device is used to provide electrical energy. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the negative electrode sheet of this application.

[0026] Figure 2This is a schematic diagram of the first type of negative electrode sheet in this application.

[0027] Figure 3 This is a schematic diagram of the second type of negative electrode sheet in this application.

[0028] Figure 4 This is a schematic diagram of the third type of negative electrode sheet in this application.

[0029] Figure 5 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0030] Figure 6 yes Figure 5 An exploded view of a battery cell according to one embodiment of this application is shown.

[0031] Figure 7 This is a schematic diagram of a battery module according to one embodiment of this application.

[0032] Figure 8 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0033] Figure 9 yes Figure 8 An exploded view of a battery pack according to one embodiment of this application is shown.

[0034] Figure 10 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to one embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover plate; 54 Negative electrode sheet; 541 Negative current collector; 542 Negative electrode film; 543 First edge region; 544 Main body region; 5441 First film; 5442 Second film; 545 Second edge region. Detailed Implementation

[0037] The following detailed description, with appropriate reference to the accompanying drawings, discloses a battery cell, its preparation method, a battery device, and an electrical device according to this application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known facts and repetitive descriptions of 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 the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0038] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0040] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0041] 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.

[0042] The fabrication process of the negative electrode sheet in a battery device is a crucial step affecting battery performance. The microstructure of the negative electrode sheet, such as binder flotation and edge enrichment, directly influences the transport of electrons and ions within it. Currently, the following wet coating process is commonly used in the fabrication of negative electrode sheets for battery devices: preparation of active material slurry → coating → drying → rolling. During the drying process of the negative electrode sheet, especially near the first transition point (the junction where the upper layer of the electrode sheet is dried but the lower layer is not), the upper solvent of the active material layer evaporates first, and the lower solvent rises rapidly. The solvent in the negative electrode slurry easily carries the binder during the rising process, causing the binder to float. Similarly, near the second transition point (the junction where the edge of the electrode sheet is dried but the middle is not), the edge solvent of the active material layer evaporates first, and the lower solvent moves towards the edge. The negative electrode slurry easily carries the binder during the movement towards the edge, resulting in binder enrichment at the edge. This leads to uneven distribution of the binder in the negative electrode film layer, and the final negative electrode sheet exhibits a state where the surface and edges are rich in binder while the bottom layer has less binder.

[0043] During the drying process of electrode sheets, the adhesive flotation and edge enrichment lead to adhesive enrichment on the surface and edges of the electrode sheets. After cold pressing, the surface and edges of the electrode sheets tend to become dense. Firstly, the dense electrode sheet surface makes electrolyte wetting difficult, seriously affecting the production efficiency of the battery device. Secondly, the low porosity of the electrode sheet surface leads to problems such as difficulty for ions and electrons to shuttle in the electrode sheet, local stress concentration, and deterioration of adhesion, thus severely restricting the fast-charging performance of the battery. Thirdly, the enrichment of edge adhesive leads to poor dynamics at the edge of the negative electrode sheet, and the temperature rise during cycling makes lithium plating more likely, which in turn affects the cycle performance of the battery.

[0044] Based on this, this application proposes a battery cell and its preparation method, a battery device and an electrical device. The following provides a more detailed description of this application and optional embodiments.

[0045] Please see Figure 1 This application provides a battery cell, which includes a negative electrode sheet 54. The negative electrode sheet 54 includes a negative electrode current collector 541 and a negative electrode film layer 542 disposed on at least one surface of the negative electrode current collector 541. The negative electrode film layer 542 includes a negative electrode active material. The negative electrode film layer 542 includes a first edge region 543, a main region 544 and a second edge region 545 distributed sequentially along the width direction. The main region 544 has at least a surface layer with a CO004 / C110 ratio of 5.6 to 33.1 under X-ray diffraction. The first edge region 543 and / or the second edge region 545 have a CO004 / C110 ratio of 0.1 to 1.2 under X-ray diffraction.

[0046] The first edge region 543 and / or the second edge region 545 refer to the edge regions at both ends of the negative electrode film layer 542 along the width direction, and the main body region 544 refers to the middle region of the negative electrode film layer 542 along the width direction.

[0047] Optionally, the first edge region 543 and / or the second edge region 545 are thinning regions.

[0048] Optionally, the main area 544 can be rectangular.

[0049] Optionally, the negative electrode film layer 542 is divided into a first edge region 543, a main body region 544, and a second edge region 545, which are distributed sequentially along the width direction.

[0050] The surface layer of the main body region 544 refers to the surface area of ​​the main body region 544 that is far away from the negative electrode current collector. It is close to the separator in the battery cell, and the thickness ratio of the surface area to the non-surface area is 0.01~50. The non-surface area is the area located between the surface area and the negative electrode current collector.

[0051] The ratio of C004 / C110 of the surface layer of the main region 544 under X-ray diffraction is the OI value of the surface layer of the main region 544. The OI value of the surface layer of the main region 544 can be obtained by X-ray diffractometer. According to the general rules of X-ray diffraction analysis and the method for determining the lattice parameters of negative electrode active materials JIS K 0131-1996 and JB / T4220-2011, the X-ray diffraction pattern of the surface layer of the main region 544 is obtained, and the OI value of the surface layer of the main region 544 is calculated according to the formula OI=C004 / C110, where C004 is the peak area of ​​the characteristic diffraction peak of the surface layer of the main region 544, and C110 is the peak area of ​​the characteristic diffraction peak of the surface layer of the main region 544.

[0052] The ratio of C004 / C110 under X-ray diffraction for the first edge region 543 and / or the second edge region 545 is the OI value of the first edge region 543 and / or the second edge region 545. The OI value of the first edge region 543 and / or the second edge region 545 can be obtained by an X-ray diffractometer, and the specific method is the same as the test method for the OI value of the surface layer of the main body region 544 described above.

[0053] As an example, the C004 / C110 ratio of at least the surface layer in the main body region 544 under X-ray diffraction can be 5.6, 8, 10, 15, 20, 25, 30 or 33.1, the C004 / C110 ratio of the first edge region 543 under X-ray diffraction can be 0.1, 0.2, 0.5, 0.8, 1 or 1.2, and the C004 / C110 ratio of the second edge region 545 under X-ray diffraction can be 0.1, 0.2, 0.5, 0.8, 1 or 1.2.

[0054] It should be noted that the C004 / C110 ratio of the first edge region 543 and the second edge region 545 under X-ray diffraction can be the same or different. For example, the C004 / C110 ratio of the first edge region 543 and the second edge region 545 under X-ray diffraction can both be 0.1, 0.5, or 1.2; or the C004 / C110 ratio of the first edge region 543 under X-ray diffraction can be 0.2, and the C004 / C110 ratio of the second edge region 545 under X-ray diffraction can be 0.5; or the C004 / C110 ratio of the first edge region 543 under X-ray diffraction can be 0.5, and the C004 / C110 ratio of the second edge region 545 under X-ray diffraction can be 1.2; or the C004 / C110 ratio of the first edge region 543 under X-ray diffraction can be 0.1, and the C004 / C110 ratio of the second edge region 545 under X-ray diffraction can be 1.

[0055] Optionally, the C004 / C110 ratio of at least the surface layer in the main region 544 is 5.6 to 12 under X-ray diffraction.

[0056] Optionally, the ratio of C004 / C110 in the first edge region 543 and / or the second edge region 545 under X-ray diffraction is 0.3 to 1.1.

[0057] The battery cell of this application achieves a C004 / C110 ratio within the aforementioned range in at least the surface layer of the intermediate main body region 544 under X-ray diffraction. This results in a majority of the negative electrode active materials in the surface layer of the intermediate main body region 544 being arranged laterally or tending to be laterally parallel to the current collector surface, thereby forming a barrier, increasing the resistance to the buoyancy of the underlying binder, lengthening the buoyancy path of the underlying binder, and thus reducing the amount of binder buoyant. Simultaneously, by ensuring that the C004 / C110 ratio in the first edge region 543 and / or the second edge region 545 is within the aforementioned range under X-ray diffraction, a majority of the negative electrode active materials in the first edge region 543 and / or the second edge region 545 are arranged longitudinally or tending to be longitudinally perpendicular to the current collector surface. This not only prevents the binder from floating to the edges but also shortens the ion transport path in the edge region of the negative electrode sheet 54, improving the kinetics of the negative electrode sheet 54 edge and reducing lithium plating in the edge region. The fast-charging performance and cycle performance of the battery cell of this application are simultaneously improved.

[0058] In some embodiments, the width ratio of the main body region 544 to the width ratio of the first edge region 543 is 5 to 40, and / or the width ratio of the main body region 544 to the width ratio of the second edge region 545 is 5 to 40.

[0059] The width of the main body region 544 refers to the dimension of the main body region 544 along the width direction of the negative electrode plate 54, the width of the first edge region 543 refers to the dimension of the first edge region 543 along the width direction of the negative electrode plate 54, and the width of the second edge region 545 refers to the dimension of the second edge region 543 along the width direction of the negative electrode plate 54.

[0060] As an example, the ratio of the width of the main body area 544 to the width of the first edge area 543 can be 5, 10, 15, 20, 25, 30, 35 or 40, and the ratio of the width of the main body area 544 to the width of the second edge area 545 can be 5, 10, 15, 20, 25, 30, 35 or 40.

[0061] This application, by ensuring that the ratio of the width of the main body region 544 to the width of the first edge region 543, and / or the ratio of the width of the main body region 544 to the width of the second edge region 545, is within the aforementioned range, can both reduce the amount of adhesive floating and prevent the adhesive from floating to the edge, thereby simultaneously improving the fast charging performance and cycle performance of the battery cell.

[0062] In some embodiments, the density ratio of the main body region 544 to the density ratio of the first edge region 543 is 0.05 to 2, and / or the density ratio of the main body region 544 to the density ratio of the second edge region 545 is 0.05 to 2.

[0063] As an example, the density ratio of the main body region 544 to the density ratio of the first edge region 543 can be 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8 or 2, and the density ratio of the main body region 544 to the density ratio of the second edge region 545 can be 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8 or 2.

[0064] The density of the main body region 544, the density of the first edge region 543, and the density of the second edge region 545 can be calculated by obtaining powder from different film layers using the Surface and Interface Cutting Analysis System (SAICAS) or by manual powder scraping.

[0065] In some embodiments, the width of the first edge region 543 and / or the second edge region 545 is 5mm to 40mm.

[0066] As an example, the width of the first edge region 543 can be 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm or 40mm, and the width of the second edge region 545 can be 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm or 40mm.

[0067] It should be noted that the widths of the first edge region 543 and the second edge region 545 can be the same or different. For example, the widths of the first edge region 543 and the second edge region 545 can both be 5mm, 20mm, or 40mm; or the width of the first edge region 543 can be 5mm and the width of the second edge region 545 can be 10mm; or the width of the first edge region 543 can be 20mm and the width of the second edge region 545 can be 25mm; or the width of the first edge region 543 can be 35mm and the width of the second edge region 545 can be 40mm.

[0068] This application achieves a C004 / C110 ratio of 0.1 to 1.2 under X-ray diffraction by making the first edge region 543 and / or the second edge region 545 of the aforementioned width range in the negative electrode 54, thereby effectively preventing the binder from floating to the edge, improving the dynamics of the edge of the negative electrode 54, and reducing lithium deposition in the edge region.

[0069] In some embodiments, the aspect ratio of the negative electrode active material is 1.2 to 4.8.

[0070] Negative electrode active materials with an aspect ratio of 1.2 to 4.8 are generally in the form of sheets or fibers. For sheet-like negative electrode active materials, the aspect ratio is the ratio of the diameter or length of the sheet-like negative electrode active material in the planar direction to the dimension in the thickness direction. For fibrous negative electrode active materials, the aspect ratio is the ratio of the fiber length to the fiber diameter.

[0071] The aspect ratio of the negative electrode active material can be measured by observing its morphology using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and statistically calculating the aspect ratio distribution.

[0072] As an example, the aspect ratio of the negative electrode active material can be 1.2, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 4.8.

[0073] This application selects negative electrode active materials with aspect ratios within the aforementioned range, which are generally in the form of sheets or fibers. On the one hand, this allows the negative electrode active materials to form a denser barrier when arranged laterally, increasing the resistance to the bottom binder's buoyancy and extending the bottom binder's buoyancy path, thereby reducing the amount of binder buoyancy. On the other hand, this allows the negative electrode active materials to form a larger blocking surface when arranged longitudinally, better preventing the binder from floating to the edge, improving the dynamics of the negative electrode sheet 54 edge, and reducing lithium plating in the edge region.

[0074] In some embodiments, the negative electrode active material includes a sheet-like or fibrous shape, and / or the negative electrode active material includes at least one of carbon materials, silicon-based materials, metal oxides, and metal sulfides.

[0075] Optionally, the carbon material includes graphite, which includes natural graphite.

[0076] Optionally, the negative electrode film layer may also include a conductive agent, including graphene and / or carbon nanofibers.

[0077] In some embodiments, the surface adhesive floating amount of the main body region 544 is 0.1% to 40%, and the surface adhesive floating amount ratio = (surface adhesive content - bottom adhesive content) / bottom adhesive content, and / or; the edge adhesive enrichment amount of the first edge region 543 is 0.1% to 40%, and the edge adhesive enrichment amount of the second edge region 545 is 0.1% to 40%, and the edge adhesive enrichment amount ratio = (edge ​​adhesive content - bottom adhesive content) / bottom adhesive content.

[0078] The surface binder content refers to the mass percentage of binder in the surface layer (far from the current collector) of the negative electrode film with a thickness of 10μm to 30μm.

[0079] The content of the bottom binder refers to the mass percentage of the binder in the bottom layer (near the current collector) of the negative electrode film layer with a thickness of 10μm to 30μm.

[0080] Edge binder content refers to the mass percentage of binder in the edge of the negative electrode film layer with a thickness of 10μm to 30μm.

[0081] As an example, the percentage of surface adhesive floating in the main body region 544 can be 0.1%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, the percentage of edge adhesive enrichment in the first edge region 543 can be 0.1%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, and the percentage of edge adhesive enrichment in the second edge region 545 can be 0.1%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0082] Optionally, the surface adhesive floating amount of the main body region 544 is 0.1% to 30%, the edge adhesive enrichment amount of the first edge region 543 is 0.1% to 30%, and the edge adhesive enrichment amount of the second edge region 545 is 0.1% to 30%.

[0083] Optionally, the surface adhesive floating amount of the main body region 544 is 0.1% to 20%, the edge adhesive enrichment amount of the first edge region 543 is 0.1% to 20%, and the edge adhesive enrichment amount of the second edge region 545 is 0.1% to 20%.

[0084] Optionally, the surface adhesive floating amount of the main body region 544 is 0.1% to 10%, the edge adhesive enrichment amount of the first edge region 543 is 0.1% to 10%, and the edge adhesive enrichment amount of the second edge region 545 is 0.1% to 10%.

[0085] Optionally, the surface adhesive in the main body region 544 has a floating amount of 5% to 10%, the edge adhesive in the first edge region 543 has a rich amount of 5% to 10%, and the edge adhesive in the second edge region 545 has a rich amount of 5% to 10%.

[0086] The percentage of surface adhesive floating and the percentage of edge adhesive enrichment can be determined by the following methods: obtain powder of film layers with thicknesses of 10μm to 30μm in different regions using a surface and interface cutting analysis system (SAICAS) or manual powder scraping, and test the surface adhesive content and edge adhesive content by thermogravimetric analysis (TG). The percentage of surface adhesive floating = (surface adhesive content - bottom adhesive content) / bottom adhesive content, and the percentage of edge adhesive enrichment = (edge ​​adhesive content - bottom adhesive content) / bottom adhesive content.

[0087] In some embodiments, the main body region 544 includes at least two film layers, and the density of the at least two film layers decreases in a gradient along the thickness direction of the negative electrode film layer 542, and the density of the film layer closer to the negative electrode current collector 541 is greater than the density of the film layer farther away from the negative electrode current collector 541.

[0088] The at least two film layers in the main body region 544 refer to multiple film layers arranged sequentially along the thickness direction of the negative electrode film layer 542. This application does not limit the number of film layers in the main body region 544, for example, it can be two, three, four or five layers.

[0089] The density of at least two film layers decreasing in a gradient means that the density of the multilayer film layers decreases in a gradient along the thickness direction of the negative electrode film layer 542. The density inside each film layer can also decrease in a gradient or remain unchanged.

[0090] For example, when the main body region 544 includes two membrane layers, namely a first membrane layer and a second membrane layer, the first membrane layer is bonded to the negative electrode current collector 541, the second membrane layer is bonded to the first membrane layer, and the density of the first membrane layer is greater than the density of the second membrane layer.

[0091] When the negative electrode film layer 542 includes three film layers, namely a first film layer, a second film layer and a third film layer, the first film layer is bonded to the negative electrode current collector 541, the second film layer is bonded to the first film layer, and the third film layer is bonded to the second film layer. The density of the first film layer is greater than the density of the second film layer, and the density of the second film layer is greater than the density of the third film layer.

[0092] When the negative electrode film layer 542 includes four film layers, namely a first film layer, a second film layer, a third film layer and a fourth film layer, the first film layer is bonded to the negative electrode current collector 541, the second film layer is bonded to the first film layer, the third film layer is bonded to the second film layer, and the fourth film layer is bonded to the third film layer. The density of the first film layer is greater than the density of the second film layer, the density of the second film layer is greater than the density of the third film layer, and the density of the third film layer is greater than the density of the fourth film layer.

[0093] On the one hand, by making the membrane layer in the main region 544 closer to the negative electrode current collector 541 denser, the negative electrode active material in the membrane layer closer to the negative electrode current collector 541 can be arranged more compactly. This not only increases the contact area between the binder and the negative electrode active material, resulting in more binding sites for the binder and the negative electrode active material, but also helps to increase the compaction density of the negative electrode sheet 54, thereby providing high energy density. On the other hand, by making the membrane layer in the main region 544 farther from the negative electrode current collector 541 less dense, the negative electrode active material in the membrane layer farther from the negative electrode current collector 541 can be arranged more loosely, thereby forming transverse channels parallel to the surface of the current collector after drying. The transverse channels help to improve the liquid retention capacity during liquid creep and circulation.

[0094] In some embodiments, the density ratio of any two adjacent membrane layers in at least two membrane layers is 1.05 to 1.3.

[0095] As an example, the density ratio of any two adjacent membrane layers in at least two membrane layers can be 1.05, 1.1, 1.2 or 1.3.

[0096] In some implementations, please refer to Figure 2 The main body region includes a first film layer 5441 and a second film layer 5442. The first film layer 5441 is bonded to the negative electrode current collector, and the second film layer 5442 is bonded to the first film layer 5441. The C004 / C110 ratio of the first film layer 5441 and the second film layer 5442 under X-ray diffraction is 5.6~33.1. The density of the first film layer 5441 is greater than the density of the second film layer 5442.

[0097] The first membrane layer 5441 is a membrane structure that is close to the negative electrode current collector and contains negative electrode active material.

[0098] The second membrane layer 5442 is a membrane structure that is far from the negative electrode current collector and contains the negative electrode active material.

[0099] As an example, the C004 / C110 ratio of the first film layer 5441 under X-ray diffraction can be 5.6, 8, 10, 15, 20, 25, 30 or 33.1, and the C004 / C110 ratio of the second film layer 5442 under X-ray diffraction can be 5.6, 8, 10, 15, 20, 25, 30 or 33.1.

[0100] It should be noted that the C004 / C110 ratio of the first film layer 5441 and the second film layer 5442 under X-ray diffraction can be the same or different. For example, the C004 / C110 ratio of the first film layer 5441 and the second film layer 5442 under X-ray diffraction can both be 5.6, 20, or 33.1; or the C004 / C110 ratio of the first film layer 5441 under X-ray diffraction can be 5.6, and the C004 / C110 ratio of the second film layer 5442 under X-ray diffraction can be 6; or the C004 / C110 ratio of the first film layer 5441 under X-ray diffraction can be 10, and the C004 / C110 ratio of the second film layer 5442 under X-ray diffraction can be 15; or the C004 / C110 ratio of the first film layer 5441 under X-ray diffraction can be 30, and the C004 / C110 ratio of the second film layer 5442 under X-ray diffraction can be 33.1.

[0101] This application achieves this by ensuring that the C004 / C110 ratio of the first film layer 5441 and the second film layer 5442 in the main body region is within the aforementioned range under X-ray diffraction, and that the density of the first film layer 5441 is greater than that of the second film layer 5442. Furthermore, most of the negative electrode active materials in the first film layer 5441 and the second film layer 5442 are arranged laterally or tend to be laterally aligned, thereby forming a barrier, increasing the buoyancy resistance of the underlying binder, and extending the buoyancy path of the underlying binder. The higher density of the first film layer 5441 near the negative electrode current collector allows for better buoyancy near the negative electrode current collector. The denser arrangement of the negative electrode active material in the fluid membrane layer not only increases the contact area between the binder and the negative electrode active material, resulting in more binding sites, but also helps to increase the compaction density of the negative electrode sheet, thereby providing high energy density. Meanwhile, the lower density of the second membrane layer 5442, which is far from the negative electrode current collector, allows the negative electrode active material in the membrane layer far from the negative electrode current collector to be arranged more loosely, thus forming transverse channels parallel to the surface of the current collector after drying. These transverse channels help to improve the liquid retention capacity during liquid creep and circulation.

[0102] Additionally, please see Figure 3The main body region includes a first film layer 5441 and a second film layer 5442. The first film layer 5441 is bonded to the negative electrode current collector, and the second film layer 5442 is bonded to the first film layer 5441. The C004 / C110 ratio of the first film layer 5441 and the second film layer 5442 under X-ray diffraction is 5.6~33.1. The density of the first film layer 5441 is the same as that of the second film layer 5442.

[0103] In some embodiments, the thickness ratio of the second film layer 5442 to the first film layer 5441 is 0.01 to 50, and / or; the density ratio of the second film layer 5442 to the first edge region 543 is greater than or equal to 0.01 and less than 1.5, and / or; the density ratio of the second film layer 5442 to the second edge region 545 is greater than or equal to 0.01 and less than 1.5, and / or; the density ratio of the first film layer 5441 to the first edge region 543 is 1 to 1.5, and / or; the density ratio of the first film layer 5441 to the second edge region 545 is 1 to 1.5.

[0104] As an example, the thickness ratio of the second film layer 5442 to the first film layer 5441 can be 0.01, 0.1, 0.5, 1, 2, 5, 10, 20, 30, 40 or 50; the density ratio of the second film layer 5442 to the first edge region 543 can be 0.01, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8 or 2; the density ratio of the second film layer 5442 to the second edge region 545 can be 0.01, 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8 or 2; the density ratio of the first film layer 5441 to the first edge region 543 can be 1, 1.1, 1.2, 1.3, 1.4 or 1.5; and the density ratio of the first film layer 5441 to the second edge region 545 can be 1, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0105] In some implementations, please refer to Figure 4 The main body region includes a first film layer 5441 and a second film layer 5442. The first film layer 5441 is bonded to the negative electrode current collector, and the second film layer 5442 is bonded to the first film layer 5441. The C004 / C110 ratio of the first film layer 5441 under X-ray diffraction is 0.1~1.2, and the C004 / C110 ratio of the second film layer 5442 under X-ray diffraction is 5.6~33.1.

[0106] As an example, the C004 / C110 ratio of the first film layer 5441 under X-ray diffraction can be 0.1, 0.2, 0.5, 0.8, 1 or 1.2, and the C004 / C110 ratio of the second film layer 5442 under X-ray diffraction can be 5.6, 8, 10, 15, 20, 25, 30 or 33.1.

[0107] This application ensures that the C004 / C110 ratio of the first film layer 5441 and the second film layer 5442 in the main body region is within the aforementioned range under X-ray diffraction. In the first film layer 5441 near the negative electrode current collector, most of the negative electrode active materials are arranged longitudinally or tend to be arranged longitudinally. This is beneficial for making the negative electrode active materials in the first film layer 5441 more compact, increasing the compaction density of the negative electrode sheet, thereby providing high energy density. In the second film layer 5442, most of the negative electrode active materials are arranged laterally or tend to be arranged laterally, thereby forming a barrier, increasing the floating resistance of the bottom binder, and extending the floating path of the bottom binder.

[0108] In some embodiments, the density of the first film layer 5441 is greater than the density of the second film layer 5442, and / or; the thickness ratio of the second film layer 5442 to the first film layer 5441 is 0.3 to 50, and / or; the density ratio of the second film layer 5442 to the first edge region 543 is 0.05 to 1.5, and / or; the density ratio of the second film layer 5442 to the second edge region 545 is 0.05 to 1.5, and / or; the density ratio of the first edge region 543 to the first film layer 5441 is 1 to 1.5, and / or; the density ratio of the second edge region 545 to the first film layer 5441 is 1 to 1.5.

[0109] As an example, the thickness ratio of the second film layer 5442 to the first film layer 5441 can be 0.3, 0.5, 1, 2, 5, 10, 20, 30, 40 or 50; the density ratio of the second film layer 5442 to the first edge region 543 can be 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2 or 1.5; the density ratio of the second film layer 5442 to the second edge region 545 can be 0.05, 0.1, 0.2, 0.5, 0.8, 1, 1.2 or 1.5; the density ratio of the first edge region 543 to the first film layer 5441 can be 1, 1.1, 1.2, 1.3, 1.4 or 1.5; and the density ratio of the second edge region 545 to the first film layer 5441 can be 1, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0110] This application also provides a method for preparing a battery cell, comprising: dividing at least one side of a negative electrode current collector into a first edge portion, a main body portion, and a second edge portion along the width direction; distributing a first slurry in the first edge portion and the second edge portion; distributing a second slurry in the main body portion to obtain a negative electrode precursor; placing the negative electrode precursor in a magnetic field environment for magnetic field induction treatment, wherein the magnetic field direction in the magnetic field environment where the first slurry is located makes an angle of 60° to 120° with the negative electrode current collector, and the magnetic field direction in the magnetic field environment where the second slurry is located makes an angle of -30° to 30° with the negative electrode current collector; and performing drying and cold pressing treatment after completing the magnetic field induction treatment.

[0111] Magnetic field-induced treatment is an advanced technology that modulates the microstructure and properties of materials by applying an external magnetic field. Its core lies in utilizing the interaction between the magnetic field and matter (such as magnetization force and Lorentz force) to directionally guide the arrangement of atoms, molecules, or particles, thereby optimizing the physical, chemical, or functional properties of the material. When the first and second slurries are placed in a magnetic field environment for magnetic field-induced treatment, the atomic orbital angular momentum of the negative electrode active material changes under the influence of the external magnetic field, causing it to acquire a magnetic moment opposite to the direction of the external magnetic field. Specifically, the negative electrode active material in the first slurry acquires a magnetic moment perpendicular to the negative electrode current collector, causing the orientation of the negative electrode active material to predominantly tend to be perpendicular to the negative electrode current collector, resulting in a decrease in the OI value. Conversely, the negative electrode active material in the second slurry acquires a magnetic moment parallel to the negative electrode current collector, causing the orientation of the negative electrode active material to predominantly tend to be parallel to the negative electrode current collector, resulting in an increase in the OI value.

[0112] In magnetic field induced processing, the angle between the direction of the magnetic field and the negative electrode current collector refers to the geometric angle between the direction of the magnetic field and the plane of the negative electrode current collector.

[0113] Optionally, the angle between the magnetic field direction in the magnetic field environment where the first slurry is located and the negative electrode current collector is 80°~100°.

[0114] Optionally, the magnetic field direction in the magnetic field environment where the second slurry is located makes an angle of -10° to 10° with the negative electrode current collector.

[0115] Optionally, the magnetic field strength is 3000 Gs to 15000 Gs, and the processing time is 5 s to 25 s.

[0116] Optionally, the magnetic field strength is 8000 Gs to 15000 Gs.

[0117] Optionally, the viscosity of the first slurry is 3000 mPa·s to 15000 mPa·s, and / or the viscosity of the second slurry is 3000 mPa·s to 15000 mPa·s.

[0118] It should be noted that the battery cell preparation method of this application is applicable to a scheme in which the C004 / C110 ratio of all film layers in the main region is 5.6 to 33.1 under X-ray diffraction, that is, applicable to a scheme in which most of the negative electrode active materials in all film layers in the main region are arranged laterally or tend to be laterally.

[0119] The magnetic field induction treatment of the negative electrode precursor can be performed in one or two steps. In a one-step process, the negative electrode precursor is directly placed in the magnetic field environment, with different magnetic field directions in different regions. Specifically, the angle between the magnetic field direction of the first slurry and the negative electrode current collector is 60°~120°, while the angle between the magnetic field direction of the second slurry and the negative electrode current collector is -30°~30°. In a two-step process, only the first slurry is placed in the first magnetic field environment with an angle of 60°~120° between the magnetic field direction and the negative electrode current collector. In the process, after the magnetic field induction treatment of the first slurry is completed, the second slurry is placed in a second magnetic field environment with an angle of -30° to 30° between the magnetic field direction and the negative electrode current collector to complete the magnetic field induction treatment of the second slurry. The order of the magnetic field induction treatment of the first slurry and the second slurry can be interchanged. That is, the second slurry can be placed in the second magnetic field environment with an angle of -30° to 30° between the magnetic field direction and the negative electrode current collector to complete the magnetic field induction treatment of the second slurry first, and then the first slurry can be placed in the first magnetic field environment with an angle of 60° to 120° between the magnetic field direction and the negative electrode current collector to complete the magnetic field induction treatment of the first slurry.

[0120] The method for preparing the battery cell of this application involves placing a first slurry and a second slurry in a magnetic field environment for magnetic induction treatment. The angle between the magnetic field direction of the first slurry and the negative electrode current collector is set to 60°~120°, and the angle between the magnetic field direction of the second slurry and the negative electrode current collector is set to -30°~30°. This induces the directional alignment of the negative electrode active materials in the first and second slurries, resulting in a majority of the negative electrode active materials in the central body being arranged laterally or tending to be laterally aligned parallel to the current collector surface. This forms a barrier, increasing the resistance to the bottom binder's buoyancy and lengthening the buoyancy path of the bottom binder, thereby reducing the amount of binder that floats. Simultaneously, it causes a majority of the negative electrode active materials in the first edge portion and / or the second edge portion to be arranged longitudinally or tending to be longitudinally aligned perpendicular to the current collector surface. This not only prevents the binder from floating to the edge but also shortens the ion transport path in the edge region of the negative electrode sheet, improving the kinetics of the negative electrode sheet edge and reducing lithium deposition in the edge region. The fast-charging performance and cycle performance of the battery cell of this application are simultaneously improved.

[0121] This application also provides a method for preparing a battery cell, comprising: dividing at least one side of a negative electrode current collector into a first edge portion, a main body portion, and a second edge portion along the width direction; setting a first slurry in the first edge portion and the second edge portion to obtain a first negative electrode precursor; placing the first negative electrode precursor in a magnetic field environment for magnetic field induction treatment, wherein the magnetic field direction of the magnetic field environment in which the first slurry is located makes an angle of 60° to 120° with the negative electrode current collector; and drying to obtain a second negative electrode precursor; then sequentially setting at least two types of negative electrode slurry in the main body portion of the second negative electrode precursor; after setting each type of negative electrode slurry, placing it in or not placing it in a magnetic field environment for magnetic field induction treatment; drying and then setting another type of negative electrode slurry, until all negative electrode film layers are set and dried; and at least the negative electrode slurry set on the surface layer is placed in a magnetic field environment in which the magnetic field direction makes an angle of -30° to 30° with the negative electrode current collector for magnetic field induction treatment.

[0122] Optionally, the angle between the magnetic field direction in the magnetic field environment where the first slurry is located and the negative electrode current collector is 80°~100°.

[0123] Optionally, at least one negative electrode slurry is located in a magnetic field environment where the angle between the magnetic field direction and the negative electrode current collector is -10° to 10°.

[0124] Optionally, the magnetic field strength is 3000 Gs to 15000 Gs, and the processing time is 5 s to 25 s.

[0125] Optionally, the magnetic field strength is 8000 Gs to 15000 Gs.

[0126] Optionally, the viscosity of the first slurry is 3000 mPa·s to 15000 mPa·s, and / or the viscosity of the second slurry is 3000 mPa·s to 15000 mPa·s.

[0127] Optionally, after each negative electrode slurry is prepared, it is placed in a magnetic field environment for magnetic field induction treatment.

[0128] It should be noted that the battery cell preparation method of this application is applicable to a scheme in which the C004 / C110 ratio in at least the surface layer of the main body region is 5.6 to 33.1 under X-ray diffraction. That is, it is applicable to a scheme in which most of the negative electrode active materials in at least the surface layer of the main body region are arranged laterally or tend to be laterally. It is also applicable to the case where there is more than one type of second slurry, that is, the second slurry may include different slurries coated on the main body in multiple times.

[0129] The following will explain the configuration of the negative electrode slurry in the main body, categorized by case:

[0130] For example, when the main body needs to be equipped with two types of negative electrode slurry, after obtaining the second negative electrode precursor, the following situation occurs:

[0131] The first method involves placing the first type of negative electrode slurry on the bottom layer of the main body of the second negative electrode precursor, and then subjecting it to magnetic field induction treatment in a magnetic field environment with the magnetic field direction at an angle of -30° to 30° with the negative electrode current collector. After drying, a first film layer is obtained. Then, the second type of negative electrode slurry is placed on the surface of the first film layer, and the film layer is subject to magnetic field induction treatment in a magnetic field environment with the magnetic field direction at an angle of -30° to 30° with the negative electrode current collector. After drying, the film is cold-pressed to obtain the negative electrode sheet.

[0132] The second method involves first placing the first type of negative electrode slurry on the bottom layer of the main body of the second negative electrode precursor, drying it to obtain the first film layer, then placing the second type of negative electrode slurry on the surface of the first film layer, placing it in a magnetic field environment with the magnetic field direction at an angle of -30° to 30° with the negative electrode current collector for magnetic field induction treatment, drying it, and then cold pressing it to obtain the negative electrode sheet.

[0133] The third method involves first placing the first type of negative electrode slurry on the bottom layer of the main body of the second negative electrode precursor, then placing it in a magnetic field environment with a magnetic field direction at an angle of 60° to 120° to the negative electrode current collector for magnetic field induction treatment, and drying it to obtain the first film layer. Then, the second type of negative electrode slurry is placed on the surface of the first film layer, and placed in a magnetic field environment with a magnetic field direction at an angle of -30° to 30° to the negative electrode current collector for magnetic field induction treatment, and drying it before cold pressing to obtain the negative electrode sheet.

[0134] Therefore, the battery cell preparation method of this application, by placing the first slurry and the negative electrode slurry in a magnetic field environment for magnetic field induction treatment, and setting the angle between the magnetic field direction of the magnetic field environment where the first slurry is located and the negative electrode current collector to be 60°~120°, and the angle between the magnetic field direction of the magnetic field environment where the negative electrode slurry at least located on the surface is located and the negative electrode current collector to be -30°~30°, can induce the negative electrode active materials in the first slurry and at least the negative electrode slurry on the surface to oriented, so that most of the negative electrode active materials in the middle main area at least the surface are arranged laterally or tend to be laterally parallel to the surface of the current collector, thereby forming a barrier, increasing the floating resistance of the bottom binder, extending the floating path of the bottom binder, and thus reducing the amount of binder floating; at the same time, it causes most of the negative electrode active materials in the first edge part and / or the second edge part to be arranged longitudinally or tend to be longitudinally perpendicular to the surface of the current collector, which can not only prevent the binder from floating to the edge, but also shorten the ion transport path in the edge region of the negative electrode sheet, improve the dynamics of the negative electrode sheet edge, and reduce lithium deposition in the edge region. The fast charging performance and cycle performance of the battery cells in this application are improved simultaneously.

[0135] In addition, the following description, with appropriate reference to the accompanying drawings, describes a battery cell, its preparation method, battery device, and power-consuming device according to this application.

[0136] [Battery cell]

[0137] This application does not impose any particular restrictions on the type of battery cell; for example, the battery cell can be a lithium-ion battery, etc.

[0138] Typically, a battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0139] This application does not impose any particular limitation on the type of electrolyte, which can be selected according to actual needs. For example, the electrolyte can be selected from at least one of solid electrolytes and liquid electrolytes (i.e., electrolyte solutions).

[0140] [Positive electrode plate]

[0141] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0142] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0143] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0144] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0145] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material for a lithium-ion battery may include materials with the general formula Li. a Ni b Co c M d O e A fOne or more of lithium transition metal oxides and their modified compounds. 0.8 ≤ a ≤ 1.2, 0.5 ≤ b < 1, 0 < c < 1, 0 < d < 1, 1 ≤ e ≤ 2, 0 ≤ f ≤ 1, M is selected from one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is selected from one or more of N, F, S, and Cl.

[0146] In some embodiments, by way of example, the positive electrode active material for a lithium-ion battery may include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM 523 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM 811 ), LiNi 0.85 Co 0.15 Al 0.05 O2, LiFePO4, and LiMnPO4, or one or more of them.

[0147] In this application, the modified compounds of the above positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active materials.

[0148] As an optional technical solution of this application, the polyanionic compound may be Li 1+x Mn 1-y A y P <� 1-z R z O4; where x is any value within the range of -0.100 to 0.100, y is any value within the range of 0.001 to 0.500, z is any value within the range of 0.001 to 0.100, A includes one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and R includes one or more elements of B, S, Si, and N;

[0149] As an optional technical solution of this application, the polyanionic compound may be Li a A e Mn1-f B f P 1-g C g O 4-n D n where A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from B, S, Si, and N; D includes one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1, e is selected from the range of 0.001 to 0.1, f is selected from the range of 0.001 to 0.5, g is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, and the second positive electrode active material is electrically neutral.

[0150] During the charge and discharge process of the battery, the insertion and extraction of Li will occur along with consumption, and the molar content of Li is different when the battery is discharged to different states. In the listing of the positive electrode materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode material is applied to the battery system, after charge and discharge cycles, the molar content of Li will change.

[0151] In the listing of the positive electrode materials in this application, the molar content of O is only the theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will show fluctuations.

[0152] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer formed on at least a part of the surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can adopt the positive electrode active materials known in the art for sodium ion batteries. As an example, the positive electrode active material can include at least one of the following materials: polyanion compounds, sodium transition metal oxides, Prussian blue compounds, and their respective modified compounds. However, this application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more.

[0153] As an optional technical solution of this application, the polyanionic compound can be Na 4+x R 3-y P 4-m O 15 / C; where 0 < x < 0.5, 0 < y ≤ 0.5, 0 < m ≤ 0.2, and R includes at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Cr, Nb, Mo, In, Ga, Sn, Hf, Ta, W, and Pb.

[0154] As an optional technical approach in this application, the polyanionic compound can be Na... x-a A a V y-b M b (PO4) 2-2c (DO4) 2c F z-d Q d Wherein, element A represents an alkali metal element that substitutes for element Na, element M represents a metal element that substitutes for element V, element D represents a dopant element that substitutes for element P, and element Q represents a dopant element that substitutes for element F. Element D includes at least one of Si and S, and element Q includes at least one of Cl and O; 3.5 ≤ x ≤ 4.5, 0 ≤ a ≤ 0.15x, 0.8 ≤ y ≤ 1.1, 0 ≤ b ≤ 0.3y, 0 ≤ c ≤ 0.15, 0.8 ≤ z ≤ 1.1, 0 ≤ d ≤ 0.2z. Optionally, element A includes at least one of K and Li; element M includes at least one of Fe, Cr, Al, Sc, Ga, In, Ti, Zr, Mn, Zn, Ni, Cu, and Co.

[0155] As an optional technical solution in this application, the polyanionic compound can be a compound containing sodium ions, transition metal ions, or a tetrahedral (YO4) structure. n- A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The price state.

[0156] Polyanionic compounds can also contain sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds containing anionic units and halide anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The valence state; the halogen can be at least one of F, Cl and Br.

[0157] Polyanionic compounds can also be sodium-containing tetrahedral (YO4) compounds. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, n represents the valence state of V; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, m represents (ZO) y) m+ The valence state; the halogen can be at least one of F, Cl and Br.

[0158] Polyanionic compounds include, for example, NaFePO4, Na3V2(PO4)3, NaM'PO4F (where M' is one or more of V, Fe, Mn, and Ni), and Na3(VO y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0159] As an optional technical solution in this application, in the sodium transition metal oxide, the transition metal can be at least one selected from Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, the sodium transition metal oxide is Na. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, 0 <x≤1。

[0160] As an optional technical solution in this application, Prussian blue compounds may be those containing sodium ions, transition metal ions, and cyanide ions (CN). - A class of compounds. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds include, for example, Na. a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0 <a≤2,0<b<1,0<c<1。

[0161] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0162] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0163] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0164] [Negative electrode plate]

[0165] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector.

[0166] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0167] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0168] In some embodiments, the negative electrode film layer includes a negative electrode active material. The negative electrode active material may be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0169] In some embodiments, the negative electrode film layer may optionally include an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0170] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0171] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0172] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0173] In other embodiments, the current collector of the negative electrode sheet typically includes a current collector body and a base coating. The base coating can be disposed on at least one side of the current collector body. The base coating basically does not contain negative electrode active material, and may include a small amount of carbon material. However, the carbon material forms a thin coating and cannot function as a negative electrode active material. In this embodiment, the negative electrode sheet can be an electrode sheet without a negative electrode active material layer. For a negative electrode sheet without a negative electrode active material layer, when the current collector of the negative electrode sheet does not contain a base coating, the film layer can be disposed on the surface of at least one side of the current collector; when the current collector of the negative electrode sheet includes a base coating, the film layer can be disposed on the surface of the base coating away from the current collector.

[0174] In some embodiments, the film layer may further include a binder for fixing the additive to the negative electrode sheet. The type of binder is not particularly limited, and those skilled in the art can choose flexibly according to actual needs.

[0175] [Electrolytes]

[0176] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0177] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0178] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0179] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0180] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0181] [Isolation membrane]

[0182] In some embodiments, the battery cell also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0183] In some 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.

[0184] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0185] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0186] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0187] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 5 The example shown is a square-structured battery cell 5.

[0188] In some implementations, refer to Figure 6The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0189] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0190] Figure 7 This is battery module 4, used as an example. (See reference...) Figure 7 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0191] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0192] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0193] Figure 8 and Figure 9 This is battery pack 1 as an example. (See reference...) Figure 8 and Figure 9 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0194] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery pack provided in this application. The battery cell, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, 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.

[0195] As the electrical device, a single battery cell, a battery module, or a battery pack can be selected according to its usage requirements.

[0196] Figure 10 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, a battery pack or battery module can be used.

[0197] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0198] Example

[0199] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0200] The relevant parameters of the negative electrode film layers of Examples 1-10 and Comparative Examples 1-5 are shown in Table 1 below.

[0201] Table 1. Relevant parameters of the negative electrode film layers in Examples 1-10 and Comparative Examples 1-5

[0202]

[0203] In Examples 1-10 and Comparative Examples 1-5, the negative electrode active material was graphite with an aspect ratio of 2.3. The graphite in the first film layer was high-density graphite with a compaction density of 1.7 g / cm³. 3 The graphite in the second film layer is ordinary graphite, with a compacted density of 1.5 g / cm³. 3 .

[0204] The C004 / C110 ratio (OI value) of the first film layer, the second film layer, the first edge region, and the second edge region under X-ray diffraction was determined by the following method:

[0205] The first film layer, second film layer, first edge region, and second edge region of the negative electrode film layers of Examples 1-10 and Comparative Examples 1-5 were tested using an X-ray diffractometer. The X-ray diffractometer model was Bruker D8 Discover, and the testing standard was JIS K 0131-1996. The OI values ​​of the first film layer, second film layer, first edge region, and second edge region of the negative electrode film layer were calculated according to the formula OI = C004 / C110, where C004 is the peak area of ​​the 004 characteristic diffraction peak, and C110 is the peak area of ​​the 110 characteristic diffraction peak.

[0206] The preparation method of the battery cell in Examples 1-7 of this application includes the following steps:

[0207] S1. Preparation of positive electrode sheet

[0208] Ternary NCM, conductive carbon SP, and polyvinylidene fluoride were mixed at a mass ratio of 97:2:1, and then N-methylpyrrolidone solvent was added. After thorough mixing, a positive electrode slurry was prepared. The positive electrode slurry was then prepared at a concentration of ~15 mg / cm³. 2 The single-sided weight is coated on both sides of the positive electrode current collector aluminum foil, and then dried, cold-pressed and cut to obtain the positive electrode sheet.

[0209] S2, Preparation of negative electrode sheet

[0210] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion, and a second edge portion along its width direction. The first negative electrode slurry is applied to the first edge portion and the second edge portion. The second negative electrode slurry is first coated on the main body portion, and then the third negative electrode slurry is coated on the surface of the second negative electrode slurry to obtain a negative electrode precursor. The negative electrode precursor is placed in a magnetic field environment for magnetic field induction treatment. The magnetic field direction of the magnetic field environment in which the first negative electrode slurry is located makes an angle of 90° with the negative electrode current collector, while the magnetic field directions of the magnetic field environments in which the second and third negative electrode slurries are located make an angle of 0° with the negative electrode current collector. After the magnetic field induction treatment is completed, the materials are dried, cold-pressed, trimmed, cut, and slit to produce a negative electrode sheet for a lithium-ion battery.

[0211] In Examples 1 and 4-7, the magnetic field strength of the second and third negative electrode slurries was 15000 GS, and the processing time was 15 s; in Example 2, the magnetic field strength of the second and third negative electrode slurries was 10000 GS, and the processing time was 5 s; in Example 3, the magnetic field strength of the second and third negative electrode slurries was 15000 GS, and the processing time was 25 s; in Examples 1-3 and 6-7, the magnetic field strength of the first negative electrode slurry was 15000 GS, and the processing time was 15 s; in Example 4, the magnetic field strength of the first negative electrode slurry was 15000 GS, and the processing time was 25 s; and in Example 5, the magnetic field strength of the first negative electrode slurry was 10000 GS, and the processing time was 5 s.

[0212] S3. Preparation of the isolation membrane

[0213] A polyethylene film with a thickness of 10 μm was used as the separator.

[0214] S4. Preparation of electrolyte

[0215] In an argon-atmospheric glove box with a water content of <10 ppm, ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. LiPF6 was then dissolved in the mixture to obtain an electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0216] S5, Assembly

[0217] The above-mentioned positive electrode, separator, and negative electrode are stacked in sequence to obtain a stacked cell; the cell is placed in an outer packaging, the electrolyte prepared above is added, and after processes such as encapsulation, standing, formation, and aging, a battery cell is obtained.

[0218] The method for preparing the negative electrode sheet of the battery cell in Example 8 of this application is as follows, and the other steps are the same as the method for preparing the battery cell in Examples 1 to 7.

[0219] S2, Preparation of negative electrode sheet

[0220] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water were uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector was sequentially divided into a first edge portion, a main body portion, and a second edge portion along its width. The first negative electrode slurry was coated onto the first edge portion and the second edge portion. The mixture was then placed in a magnetic field environment with a magnetic field direction at a 90° angle to the negative electrode current collector for magnetic field induction treatment, followed by drying. The second negative electrode precursor is then obtained; the second negative electrode slurry is then coated on the bottom layer of the main body of the second negative electrode precursor, and it is placed in a magnetic field environment with a magnetic field direction at a 90° angle to the negative electrode current collector for magnetic field induction treatment. After drying, the first film layer is obtained. Then, the third negative electrode slurry is placed on the surface of the first film layer, and it is placed in a magnetic field environment with a magnetic field direction at a 90° angle to the negative electrode current collector for magnetic field induction treatment. After drying, it is cold-pressed, trimmed, cut, and slit to produce the negative electrode sheet of the lithium-ion battery.

[0221] In Example 8, the magnetic field strength of the second negative electrode slurry was 10000GS and the processing time was 6s; the magnetic field strength of the third negative electrode slurry was 15000GS and the processing time was 15s; and the magnetic field strength of the first negative electrode slurry was 15000GS and the processing time was 15s.

[0222] The method for preparing the negative electrode sheet of the battery cell in Example 9 of this application is as follows, and the other steps are the same as the method for preparing the battery cell in Examples 1 to 7.

[0223] S2, Preparation of negative electrode sheet

[0224] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water were uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector was sequentially divided into a first edge portion, a main body portion, and a second edge portion along its width. The first negative electrode slurry was coated onto the first edge portion and the second edge portion. The mixture was then placed in a magnetic field environment with a magnetic field direction at a 90° angle to the negative electrode current collector for magnetic field induction treatment, followed by drying. The second negative electrode precursor is then obtained; the second negative electrode slurry is then coated on the bottom layer of the main body of the second negative electrode precursor, and it is placed in a magnetic field environment with a magnetic field direction of 90° and the negative electrode current collector for magnetic field induction treatment. After drying, the first film layer is obtained. Then, the third negative electrode slurry is placed on the surface of the first film layer, and it is placed in a magnetic field environment with a magnetic field direction of 0° and the negative electrode current collector for magnetic field induction treatment. After drying, it is cold pressed, trimmed, cut, and slit to produce the negative electrode sheet of the lithium-ion battery.

[0225] In Example 9, the magnetic field strength of the third negative electrode slurry was 15000GS, and the processing time was 15s; the magnetic field strength of the first negative electrode slurry and the second negative electrode slurry was 15000GS, and the processing time was 15s.

[0226] The method for preparing the negative electrode sheet of the battery cell in Example 10 of this application is as follows, and the other steps are the same as the method for preparing the battery cell in Examples 1 to 7.

[0227] S2, Preparation of negative electrode sheet

[0228] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry and a second negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion, and a second edge portion along its width direction. The first negative electrode slurry is applied to the first edge portion and the second edge portion, and the second negative electrode slurry is coated on the main body portion to obtain a negative electrode precursor. The negative electrode precursor is placed in a magnetic field environment for magnetic field induction treatment. The magnetic field direction of the first negative electrode slurry in the magnetic field environment is at an angle of 90° with the negative electrode current collector, and the magnetic field direction of the second negative electrode slurry in the magnetic field environment is at an angle of 0° with the negative electrode current collector. After the magnetic field induction treatment is completed, the material is dried, cold-pressed, trimmed, cut, and slit to produce a negative electrode sheet for a lithium-ion battery.

[0229] In Example 10, the magnetic field strength of the second negative electrode slurry was 15000GS and the processing time was 15s; the magnetic field strength of the first negative electrode slurry was 15000GS and the processing time was 15s.

[0230] The method for preparing the negative electrode sheet of the battery cell in Comparative Example 1 of this application is as follows, and the other steps are the same as the preparation methods of the battery cells in Examples 1 to 7.

[0231] S2, Preparation of negative electrode sheet

[0232] The negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare the first negative electrode slurry, the second negative electrode slurry and the third negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion and a second edge portion along the width direction. The first negative electrode slurry is applied to the first edge portion and the second edge portion. The second negative electrode slurry is first coated on the main body portion and then the third negative electrode slurry is coated on the surface of the second negative electrode slurry. After drying, the negative electrode sheet of the lithium-ion battery is produced by cold pressing, edge cutting, sheet cutting and slitting.

[0233] The method for preparing the negative electrode sheet of the battery cell in Comparative Example 2 of this application is as follows, and the other steps are the same as the method for preparing the battery cell in Examples 1 to 7.

[0234] S2, Preparation of negative electrode sheet

[0235] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion, and a second edge portion along the width direction. The first negative electrode slurry is applied to the first edge portion and the second edge portion. The second negative electrode slurry is first coated on the main body portion, and then the third negative electrode slurry is coated on the surface of the second negative electrode slurry to obtain a negative electrode precursor. The negative electrode precursor is placed in a magnetic field environment for magnetic field induction treatment. The angle between the magnetic field direction and the negative electrode current collector is 0°. After the magnetic field induction treatment is completed, the precursor is dried, cold-pressed, trimmed, cut, and slit to produce a negative electrode sheet for a lithium-ion battery.

[0236] In Comparative Example 2, the magnetic field strength of the first, second, and third negative electrode slurries was 15000 GS, and the processing time was 15 s.

[0237] The method for preparing the negative electrode sheet of the battery cell in Comparative Example 3 of this application is as follows, and the other steps are the same as the method for preparing the battery cell in Examples 1 to 7.

[0238] S2, Preparation of negative electrode sheet

[0239] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion, and a second edge portion along the width direction. The first negative electrode slurry is applied to the first edge portion and the second edge portion. The second negative electrode slurry is first coated on the main body portion, and then the third negative electrode slurry is coated on the surface of the second negative electrode slurry to obtain a negative electrode precursor. The negative electrode precursor is placed in a magnetic field environment for magnetic field induction treatment. The angle between the magnetic field direction and the negative electrode current collector is 90°. After the magnetic field induction treatment is completed, the precursor is dried, cold-pressed, trimmed, cut, and slit to produce a negative electrode sheet for a lithium-ion battery.

[0240] In Comparative Example 3, the magnetic field strength of the first, second, and third negative electrode slurries was 15000 GS, and the processing time was 15 s.

[0241] The method for preparing the negative electrode sheet of the battery cell in Comparative Example 4 of this application is as follows, and the other steps are the same as the preparation methods of the battery cells in Examples 1 to 7.

[0242] S2, Preparation of negative electrode sheet

[0243] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion, and a second edge portion along its width direction. The first negative electrode slurry is coated on the first edge portion and the second edge portion. The first negative electrode slurry is then placed in a magnetic field environment with a magnetic field direction at a 90° angle to the negative electrode current collector for magnetic field induction treatment. After drying, a second negative electrode precursor is obtained. The second negative electrode slurry and the third negative electrode slurry are then coated on the bottom layer of the main body portion of the second negative electrode precursor. After drying, the precursor is cold-pressed, trimmed, cut, and slit to produce a negative electrode sheet for a lithium-ion battery.

[0244] In Comparative Example 4, the magnetic field strength of the first negative electrode slurry was 15000GS, and the processing time was 15s.

[0245] The method for preparing the negative electrode sheet of the battery cell in Comparative Example 5 of this application is as follows, and the other steps are the same as the method for preparing the battery cell in Examples 1 to 7.

[0246] S2, Preparation of negative electrode sheet

[0247] A negative electrode active material, conductive carbon SP, styrene-butadiene rubber, carboxymethyl cellulose, and solvent water are uniformly mixed in a mass ratio of 97:1:1:1:100 to prepare a first negative electrode slurry, a second negative electrode slurry, and a third negative electrode slurry. At least one side of the negative electrode current collector is divided into a first edge portion, a main body portion, and a second edge portion along the width direction. The first negative electrode slurry is coated on the first edge portion and the second edge portion, and after drying, a second negative electrode precursor is obtained. The second negative electrode slurry and the third negative electrode slurry are then coated on the bottom layer of the main body portion of the second negative electrode precursor. The precursor is then placed in a magnetic field environment with a magnetic field direction at an angle of 0° to the negative electrode current collector for magnetic field induction treatment. After drying, the precursor is cold-pressed, trimmed, cut, and slit to produce a negative electrode sheet for a lithium-ion battery.

[0248] In Comparative Example 5, the magnetic field strength of the second and third negative electrode slurries was 15000GS, and the processing time was 15s.

[0249] In addition, the percentage of surface adhesive floating, percentage of edge adhesive enrichment, adhesion force of the electrode after cold pressing, and fast charging performance and cycle performance of the battery cells of Examples 1-10 and Comparative Examples 1-5 were measured, and the results are shown in Table 2.

[0250] The testing method is as follows:

[0251] 1. The percentage of surface adhesive floating on the negative electrode sheet and the percentage of edge adhesive enrichment.

[0252] Powder of a 20 μm thick film layer was obtained using a surface and interface cutting analysis system (SAICAS) or manual powder scraping. The surface adhesive content and edge adhesive content were tested by thermogravimetric analysis (TG). The percentage of surface adhesive floating was calculated as (surface adhesive content - bottom adhesive content) / bottom adhesive content, and the percentage of edge adhesive enrichment was calculated as (edge ​​adhesive content - bottom adhesive content) / bottom adhesive content.

[0253] 2. Adhesion of electrode sheets after cold pressing

[0254] Take a long strip sample and stick it to the patch with double-sided tape. Tear off a portion and measure it with a tensile testing machine. The lower gripper of the tensile testing machine holds the iron sheet below the torn part, and the upper gripper holds the electrode sheet of the torn part. Measure the tensile curve to obtain the cohesive force.

[0255] 3. Fast charging performance

[0256] Using 4C charging, the charging time from 10% to 70% SOC was measured.

[0257] 4. Cyclic performance

[0258] First, use a 1 / 3C rate to charge and discharge the battery to determine its discharge capacity. Then, charge the battery to the upper limit voltage using a 0.5C rate, and then discharge it to the cutoff voltage using a 1C rate to complete one cycle. Repeat this cycle for 1000 cycles and compare the discharge capacity at this point with the initial discharge capacity. The capacity retention rate after 1000 cycles is calculated as: discharge capacity after 1000 cycles / initial discharge capacity * 100%.

[0259] Table 2. The percentage of surface binder floating, the percentage of edge binder enrichment, the adhesion force of the electrode after cold pressing, and the fast charging performance and cycle performance of the battery cells for the negative electrode sheets of Examples 1-10 and Comparative Examples 1-5.

[0260]

[0261] As shown in Examples 1-10, when the C004 / C110 ratio of at least part of the main body region under X-ray diffraction is 5.6-33.1, the C004 / C110 ratio of the first edge region and the second edge region under X-ray diffraction is 0.1-1.2, the width ratio of the main body region to the width ratio of the first edge region is 5-40, and the width ratio of the main body region to the width ratio of the second edge region is 5-40, the surface adhesive floating amount of the negative electrode sheet is 5.1%-38.3%, the edge adhesive enrichment amount is 6.3%-32.5%, the electrode sheet adhesion force after cold pressing is 17.5 N / m-23.8 N / m, the charging time of the battery cell from 10% to 70% SOC is 10.1 min-13.5 min, and the capacity retention rate after 1000 cycles is 92.9%-97.2%.

[0262] As can be seen from the comparison of Examples 1 to 3, when the ratio of C004 / C110 in the first edge region and the second edge region under X-ray diffraction is 0.37, as the ratio of C004 / C110 in the first film layer and the second film layer in the main body region increases, the proportion of the surface adhesive floating on the negative electrode sheet decreases, the adhesion of the electrode sheet increases after cold pressing, and the charging time of the battery cell from 10% to 70% SOC increases or decreases.

[0263] As can be seen from the comparison of Examples 1, 4 to 6, when the ratio of C004 / C110 of the first film layer and the second film layer under X-ray diffraction is 11.9, the proportion of edge binder enrichment of the negative electrode sheet increases as the ratio of C004 / C110 of the first edge region and the second edge region under X-ray diffraction increases.

[0264] Comparing Comparative Example 1 and Example 1, it can be seen that the negative electrode slurry of Comparative Example 1 was not magnetized. The surface binder floating amount of the negative electrode sheet of Comparative Example 1 was as high as 41.4%, the edge binder enrichment amount was as high as 44.3%, the electrode adhesion force after cold pressing was 17.3 N / m, the charging time from 10% to 70% SOC of the battery cell was 15.7 min, and the capacity retention rate after 1000 cycles was 91.2%. The surface binder floating amount, edge binder enrichment amount, and battery cell adhesion rate of Comparative Example 1 were significantly higher than those of the negative electrode sheet of Comparative Example 1. The charging time for the battery cell from 10% to 70% SOC is higher than that of Example 1. The adhesion strength of the cold-pressed electrode and the 1000-cycle capacity retention rate of the battery cell in Comparative Example 1 are lower than those in Example 1. This indicates that the present application enables most of the negative electrode active materials in the intermediate main body region, at least in the surface layer, to be arranged laterally or tending to be laterally parallel to the surface of the current collector, and enables most of the negative electrode active materials in the first edge region and / or the second edge region to be arranged longitudinally or tending to be longitudinally perpendicular to the surface of the current collector, thereby improving the fast charging performance and cycle performance of the battery cell.

[0265] Comparing Comparative Example 2 and Example 1, it can be seen that the C004 / C110 ratio of the first film layer, the second film layer, the first edge region, and the second edge region of Comparative Example 2 is 11.9 under X-ray diffraction. This means that most of the negative electrode active materials in the central main region and the edge region of Comparative Example 2 are arranged laterally or tend to be laterally parallel to the current collector surface. The edge binder enrichment ratio of the negative electrode sheet of Comparative Example 2 is as high as 49.7%. The charging time from 10% to 70% SOC of the battery cell is 13.5 min, and the 1000-cycle capacity retention rate is 92.2%. The edge binder enrichment ratio of the negative electrode sheet of Comparative Example 2 and the charging time from 10% to 70% SOC of the battery cell are both higher than those of Example 1. The 1000-cycle capacity retention rate of the battery cell of Comparative Example 2 is lower than that of Example 1. This indicates that the binder of Comparative Example 2 is enriched towards the edge, which affects the dynamics of the negative electrode edge and may lead to lithium plating in the edge region.

[0266] Comparing Comparative Example 3 and Example 1, it can be seen that the C004 / C110 ratio of the first film layer, the second film layer, the first edge region, and the second edge region of Comparative Example 3 is 0.37 under X-ray diffraction. This means that most of the negative electrode active materials in the central main region and the edge region of Comparative Example 3 are arranged vertically or tend to be vertically perpendicular to the current collector surface. The surface binder floating amount of the negative electrode sheet of Comparative Example 3 is as high as 48.5%, and the electrode adhesion force after cold pressing is 15.9 N / m. The state of charge (SOC) of the battery cell ranges from 10% to 70%. The charging time was 14.8 minutes, and the capacity retention rate after 1000 cycles was 91.4%. The percentage of surface adhesive floating on the negative electrode sheet in Comparative Example 3 and the charging time from 10% to 70% SOC of the battery cell were both higher than those in Example 1. The adhesion force of the cold-pressed electrode sheet and the capacity retention rate after 1000 cycles of the battery cell in Comparative Example 3 were both lower than those in Example 1. This indicates that the adhesive in Comparative Example 3 floats to the surface, affecting the dynamics of the surface layer of the negative electrode sheet and severely restricting the fast charging performance and cycle performance of the battery cell.

[0267] Comparing Comparative Example 4 and Example 1, it can be seen that the first and second film layers of Comparative Example 4 were not magnetized before drying. The surface binder floating amount of the negative electrode sheet of Comparative Example 4 was as high as 42.1%, the electrode adhesion force after cold pressing was 17.2 N / m, the charging time of the battery cell from 10% to 70% SOC was 15.3 min, and the capacity retention rate of 1000 cycles was 21.9%. The surface binder floating amount of the negative electrode sheet of Comparative Example 4 and the charging time of the battery cell from 10% to 70% SOC were both higher than those of Example 1. The electrode adhesion force after cold pressing and the capacity retention rate of the battery cell of Comparative Example 4 were both lower than those of Example 1. This indicates that the binder of Comparative Example 4 floats to the surface, affecting the dynamics of the surface layer of the negative electrode sheet and severely restricting the fast charging performance and cycle performance of the battery cell.

[0268] Comparing Comparative Example 5 and Example 1, it can be seen that the first and second edge regions of Comparative Example 5 were not magnetized before drying. The edge binder enrichment ratio of the negative electrode sheet of Comparative Example 5 was as high as 43.4%, the charging time of the battery cell from 10% to 70% SOC was 13.7 min, and the capacity retention rate of 1000 cycles was 92.5%. The edge binder enrichment ratio of the negative electrode sheet of Comparative Example 5 and the charging time of the battery cell from 10% to 70% SOC were both higher than those of Example 1. The capacity retention rate of the battery cell of Comparative Example 5 was lower than that of Example 1. This indicates that the binder of Comparative Example 5 is enriched at the edge, which affects the dynamics of the edge of the negative electrode sheet and may lead to lithium deposition in the edge region.

[0269] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized in that, The battery cell includes a negative electrode sheet, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer includes a negative electrode active material, the negative electrode film layer includes a first edge region, a main body region and a second edge region distributed sequentially along the width direction, the main body region has a CO004 / C110 ratio of at least the surface layer of which is 5.6 to 33.1 under X-ray diffraction, and the first edge region and / or the second edge region has a CO004 / C110 ratio of 0.1 to 1.2 under X-ray diffraction.

2. The battery cell according to claim 1, characterized in that, The ratio of the width of the main body area to the width of the first edge area is 5 to 40, and / or; The ratio of the width of the main body area to the width of the second edge area is 5 to 40.

3. The battery cell according to claim 1, characterized in that, The density ratio of the main region to the density of the first edge region is 0.05~2, and / or; The density ratio of the main region to the density of the second edge region is 0.05~2.

4. The battery cell according to claim 1, characterized in that, The width of the first edge region and / or the second edge region is 5mm to 40mm.

5. The battery cell according to claim 1, characterized in that, The aspect ratio of the negative electrode active material is 1.2 to 4.

8.

6. The battery cell according to claim 1, characterized in that, The negative electrode active material may be in the form of sheets or fibers, and / or; The negative electrode active material includes at least one of carbon materials, silicon-based materials, metal oxides, and metal sulfides.

7. The battery cell according to claim 1, characterized in that, The surface adhesive content in the main body area is 0.1% to 40%, and the surface adhesive content is calculated as (surface adhesive content - bottom adhesive content) / bottom adhesive content, and / or; The edge adhesive enrichment ratio in the first edge region is 0.1%~40%, and the edge adhesive enrichment ratio in the second edge region is 0.1%~40%. The edge adhesive enrichment ratio = (edge ​​adhesive content - bottom adhesive content) / bottom adhesive content.

8. The battery cell according to claim 1, characterized in that, The main body region includes at least two film layers. Along the thickness direction of the negative electrode film layer, the density of the at least two film layers decreases in a gradient, and the density of the film layer closer to the negative electrode current collector is greater than the density of the film layer farther away from the negative electrode current collector.

9. The battery cell according to claim 8, characterized in that, The density ratio of any two adjacent membrane layers in the at least two membrane layers is 1.05 to 1.

3.

10. The battery cell according to claim 1, characterized in that, The main body region includes a first film layer and a second film layer. The first film layer is bonded to the negative electrode current collector, and the second film layer is bonded to the first film layer. The C004 / C110 ratio of the first film layer and the second film layer under X-ray diffraction is both 5.6~33.1, and the density of the first film layer is greater than that of the second film layer.

11. The battery cell according to claim 10, characterized in that, The thickness ratio of the second film layer to the first film layer is 0.01~50, and / or; The density ratio of the second film layer to the first edge region is greater than or equal to 0.01 and less than 1.5, and / or; The density ratio of the second film layer to the second edge region is greater than or equal to 0.01 and less than 1.5, and / or; The density ratio of the first film layer to the first edge region is 1 to 1.5, and / or; The density ratio of the first film layer to the second edge region is 1 to 1.

5.

12. The battery cell according to claim 1, characterized in that, The main body region includes a first film layer and a second film layer. The first film layer is bonded to the negative electrode current collector, and the second film layer is bonded to the first film layer. The ratio of CO004 to CO110 of the first film layer under X-ray diffraction is 0.1 to 1.2, and the ratio of CO004 to CO110 of the second film layer under X-ray diffraction is 5.6 to 33.

1.

13. The battery cell according to claim 12, characterized in that, The density of the first film layer is greater than the density of the second film layer, and / or; The thickness ratio of the second film layer to the first film layer is 0.3 to 50, and / or; The density ratio of the second film layer to the first edge region is 0.05~1.5, and / or; The density ratio of the second film layer to the second edge region is 0.05~1.5, and / or; The density ratio of the first edge region to the first film layer is 1 to 1.5, and / or; The density ratio of the second edge region to the first film layer is 1 to 1.

5.

14. A method for preparing a battery cell according to any one of claims 1 to 13, characterized in that, The method for preparing the battery cell includes: dividing at least one side of the negative electrode current collector into a first edge portion, a main body portion, and a second edge portion along the width direction; setting a first slurry in the first edge portion and the second edge portion; and setting a second slurry in the main body portion to obtain a negative electrode precursor; placing the negative electrode precursor in a magnetic field environment for magnetic field induction treatment, wherein the magnetic field direction in the magnetic field environment where the first slurry is located makes an angle of 60°~120° with the negative electrode current collector, and the magnetic field direction in the magnetic field environment where the second slurry is located makes an angle of -30°~30° with the negative electrode current collector; and after completing the magnetic field induction treatment, performing drying and cold pressing treatment.

15. A method for preparing a battery cell according to any one of claims 1 to 13, characterized in that, The method for preparing the battery cell includes: dividing at least one side of the negative electrode current collector into a first edge portion, a main body portion, and a second edge portion along the width direction; setting a first slurry on the first edge portion and the second edge portion to obtain a first negative electrode precursor; placing the first negative electrode precursor in a magnetic field environment for magnetic field induction treatment, wherein the magnetic field direction of the magnetic field environment in which the first slurry is located makes an angle of 60° to 120° with the negative electrode current collector; and drying to obtain a second negative electrode precursor; then setting at least two types of negative electrode slurry sequentially on the main body portion of the second negative electrode precursor; after setting each type of negative electrode slurry, placing it in or not placing it in a magnetic field environment for magnetic field induction treatment; drying and then setting another type of negative electrode slurry, until all negative electrode film layers are set and dried; and at least the negative electrode slurry set on the surface layer is placed in a magnetic field environment in which the magnetic field direction makes an angle of -30° to 30° with the negative electrode current collector for magnetic field induction treatment.

16. A battery device, characterized in that, The battery device includes a battery cell as described in any one of claims 1 to 13 or a battery cell prepared by a method according to claim 14 or 15.

17. An electrical appliance, characterized in that, The electrical device includes a battery cell as described in any one of claims 1 to 13 or a battery device as described in claim 16, wherein the battery cell or the battery device is used to provide electrical energy.

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