Cylindrical battery cell, battery device, and electric device

Abstract

The application relates to a cylindrical battery monomer, a battery device and a power utilization device, the cylindrical battery monomer comprising a shell and an electrode assembly, the electrode assembly comprising a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer, the outer diameter of the shell being greater than or equal to 28 mm; the negative electrode active material layer comprising a carbon-based material and a silicon-based material, the carbon-based material comprising a graphite material, the mass content of silicon elements in the negative electrode active material layer being greater than or equal to 0.5% based on the mass of the negative electrode active material layer; the positive electrode active material layer comprising a lithium-containing transition metal oxide, the lithium-containing transition metal oxide comprising single-crystal particles, and the average particle size of the lithium-containing transition metal oxide being 1.5-7.5 mu m. The application can improve the energy density, cycle performance and dynamic performance of the cylindrical battery monomer.

Description

[0001] This application claims priority to PCT International Application PCT / CN2026 / 092380, filed on April 22, 2026, entitled “Cylindrical Battery Cell, Battery Device and Power Consumption Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to a cylindrical battery cell, a battery device, and an electrical device. Background Technology

[0003] Battery cells, especially cylindrical battery cells, are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, and power tools.

[0004] With the development of applications for cylindrical battery cells, the performance of cylindrical battery cells, such as energy density, kinetic performance, and cycle performance under fast charging, needs to be further improved. Summary of the Invention

[0005] This application provides a cylindrical battery cell, a battery device, and an electrical device, which can simultaneously improve the energy density, dynamic performance, and cycle performance under fast charging of the cylindrical battery cell.

[0006] In a first aspect, this application proposes a cylindrical battery cell, comprising a casing and an electrode assembly disposed within the casing. The electrode assembly includes a positive electrode and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector. The negative electrode includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector. The outer diameter of the casing is greater than or equal to 28 mm. The negative active material layer includes a negative active material, which includes carbon-based materials and silicon-based materials. The carbon-based material includes graphite. Based on the mass of the negative active material layer, the mass content of silicon in the negative active material layer is greater than or equal to 0.5%. The positive active material layer includes a lithium-containing transition metal oxide, which includes single-crystal particles. Based on the total number of lithium-containing transition metal oxide particles being 100%, the number of single-crystal particles accounts for 80% to 100%, and the average particle size of the lithium-containing transition metal oxide is 1.5 μm to 7.5 μm.

[0007] In this embodiment, the outer diameter of the casing is relatively large, which can provide more storage space for the positive and negative electrode active materials. Under the above casing size, the positive electrode active material layer includes lithium-containing transition metal oxide. The specific capacity of lithium-containing transition metal oxide is relatively high, which is beneficial to improving the positive electrode capacity. Silicon-based materials are introduced into the negative electrode active material layer. The amount of silicon-based materials added is not too low, so that the mass content of silicon element is greater than or equal to 0.5%, which improves the negative electrode capacity. This allows lithium ions extracted from the positive electrode active material layer to be embedded in the negative electrode active material layer, so that the positive electrode capacity can be fully utilized, thereby improving the energy density of the cylindrical battery cell. During the charging process of a cylindrical battery cell, silicon-based materials exhibit a volume expansion effect. As the mass content of silicon increases, the volume expansion of the negative electrode active material layer intensifies, leading to increased compression of the internal film layer of the electrode assembly. This can cause cracking of lithium-containing transition metal oxide particles, exacerbating interfacial side reactions and reducing cycle and kinetic performance. Furthermore, with a larger outer diameter of the casing, the compression of the electrode assembly inside the casing intensifies, further aggravating the degree of side reactions within the system. Therefore, the embodiments of this application introduce graphite material into the negative electrode active material layer. Graphite material has a small volume expansion and excellent structural stability, which can reduce the overall volume expansion of the negative electrode active material layer to a certain extent, thereby reducing the compression of the internal film layer of the electrode assembly, reducing internal stress, alleviating the damage caused by stress to the positive electrode sheet, and reducing the risk of cracking of lithium-containing transition metal oxides. In another aspect of the embodiments of this application, lithium-containing transition metal oxides include micron-sized single crystal particles. The single crystal particles have excellent structural stability, and even if the positive electrode active material layer is subjected to a certain degree of extrusion, the lithium-containing transition metal oxides are not easy to crack, thereby improving interface stability and improving cycle life under fast charging. However, the micron-sized single-crystal structure results in a long solid-phase transport path for lithium ions, leading to poor kinetic performance and hindering cycling under fast charging conditions. Therefore, the volume average particle size of the lithium-containing transition metal oxide in the embodiments of this application is not too large, thereby shortening the solid-phase transport path for lithium ions. At the same time, the particle size is not too small, so that the active surface area is not too high, thereby reducing surface side reactions and improving the kinetic performance and cycle life of cylindrical battery cells under fast charging conditions.

[0008] In summary, the negative electrode active material layer of the embodiments of this application includes graphite material and silicon-based material, and the positive electrode active material layer includes lithium-containing transition metal oxide, which includes a single crystal structure. By synergistically controlling the average particle size of the lithium-containing transition metal oxide, it is possible to effectively improve the energy density, kinetic performance and cycle performance under fast charging of cylindrical battery cells.

[0009] In some embodiments, based on the mass of the negative electrode active material layer, the mass content of silicon element is 0.5% to 20%, optionally 1% to 15%, optionally 1% to 10%, optionally 2% to 8%.

[0010] When the mass content of silicon is within the above range, its combination with materials such as graphite can further improve the energy density, cycle performance, and kinetic performance of cylindrical battery cells.

[0011] In some implementations, based on a total number of lithium transition metal oxide particles of 100%, the number of single crystal particles accounts for 80% to 100%. When the number of single crystal particles is within the above range, the structural stability of the lithium transition metal oxide can be further improved, thereby improving the cycle life under fast charging.

[0012] In some implementations, the mass content of graphite material is 55% to 96% based on the mass of the negative electrode active material layer.

[0013] The combination of graphite and silicon-based materials with the aforementioned mass content helps to reduce the overall volume expansion of the negative electrode active material layer, thereby improving the cycle performance and kinetic performance of the cylindrical battery cell.

[0014] In some embodiments, the graphite material includes one or more of natural graphite and artificial graphite; alternatively, the graphite material includes both natural and artificial graphite.

[0015] The combination of the aforementioned graphite and silicon-based materials helps to reduce the overall volume expansion of the negative electrode active material layer, thereby improving the cycle performance and kinetic performance of the cylindrical battery cell.

[0016] In some implementations, the mass content of natural graphite is 1% to 40% based on the mass of the negative electrode active material layer.

[0017] Within the aforementioned mass content range, natural graphite, when combined with silicon-based materials, can reduce the overall expansion of the negative electrode sheet; moreover, the mass content of natural graphite will not be too high, which can reduce the side reactions on the surface of natural graphite and improve the cycle life and dynamic performance of cylindrical battery cells.

[0018] In some embodiments, the average particle size of the lithium transition metal oxide is 3 μm to 5 μm.

[0019] When the volume average particle size of lithium-containing transition metal oxides is within the above range, it is beneficial to balance kinetic performance and cycle performance.

[0020] In some embodiments, based on the mass of the negative electrode active material layer, the mass content of the silicon-based material is 1% to 40%, optionally 2% to 30%.

[0021] When the mass content of silicon-based materials is within the above range, their combination with graphite materials can further improve the energy density, cycle life, and kinetic performance of cylindrical battery cells.

[0022] In some embodiments, the silicon-based material includes one or more of silicon-carbon materials, elemental silicon, silicon oxide, silicon-nitrogen composites, and silicon alloys. Optionally, the silicon-based material includes silicon-carbon materials.

[0023] The combination of the aforementioned silicon-based materials and graphite materials can further improve the energy density, cycle life, and kinetic performance of cylindrical battery cells.

[0024] In some embodiments, the average particle size of the silicon-based material is 1 μm to 12 μm.

[0025] When the average particle size of silicon-based materials is within the above range, the volume expansion of silicon-based materials will not be too high, and the degree of side reaction with electrolyte will not be excessive, which is beneficial to balancing the cycle performance and kinetic performance of cylindrical battery cells.

[0026] In some embodiments, the carbon-based material also includes one or more of hard carbon and soft carbon.

[0027] In some embodiments, the average particle size of the carbon-based material is 10 μm to 18 μm.

[0028] When the average particle size of carbon-based materials is within the above range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life of cylindrical battery cells.

[0029] In some embodiments, the average particle size of the negative electrode active material is 5 μm to 18 μm.

[0030] When the average particle size of the negative electrode active material is within the above range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life of the cylindrical battery cell.

[0031] In some embodiments, the negative electrode active material layer is a single-layer film. A single-layer negative electrode active material layer is beneficial for improving the kinetic performance of the negative electrode active material layer.

[0032] In some embodiments, the negative electrode active material layer includes a first film layer and a second film layer stacked together, the first film layer being located between the negative electrode current collector and the second film layer, the second film layer comprising a silicon-based material, and the first film layer and the second film layer each independently comprising a graphite material.

[0033] The negative electrode active material layer includes multiple film layers, which is beneficial to improving the cycle performance of the negative electrode active material layer.

[0034] In some embodiments, the thickness ratio of the second film layer to the first film layer is 0.125 to 1, optionally 0.125 to 0.25. When the thickness ratio of the second film layer to the first film layer is within the above range, it is beneficial to reduce the overall volume expansion of the negative electrode sheet and improve the cycle life and kinetic performance of the cylindrical battery cell.

[0035] In some embodiments, the thickness of the first film layer is 40 μm to 55 μm; the relatively thick thickness of the first film layer is beneficial to improving energy density and improving the cycle life and kinetic performance of the cylindrical battery cell.

[0036] In some embodiments, the thickness of the second film layer is 5 μm to 20 μm; the relatively thin thickness of the second film layer is beneficial to reducing the overall volume expansion of the negative electrode sheet and improving the cycle life and dynamic performance of the cylindrical battery cell.

[0037] In some embodiments, the thickness of the negative electrode active material layer is between 45 μm and 75 μm. When the thickness of the negative electrode active material layer is within this range, it can simultaneously improve the energy density, cycle life, and kinetic performance of the cylindrical battery cell.

[0038] In some embodiments, the compaction density of the first film layer is greater than that of the second film layer. The difference in compaction density between the first and second film layers is beneficial for constructing more porous structures, increasing the wettability of the electrolyte to the second film layer, improving the migration rate of active ions, reducing the risk of lithium plating, and improving the cycle life of the cylindrical battery cell.

[0039] In some embodiments, the compaction density of the negative electrode active material layer is 1 g / cm³. 3 Up to 1.65 g / cm 3 .

[0040] When the compaction density of the negative electrode active material layer is within the above range, the risk of performance degradation due to stress accumulation is reduced while maximizing energy density, effectively balancing the energy density, cycle life, and kinetic performance of cylindrical battery cells.

[0041] In some embodiments, based on the mass of the negative electrode active material layer, the silicon content is 0.5% to 5% by mass, and the compaction density of the negative electrode active material layer is 1.3 g / cm³. 3 Up to 1.65 g / cm 3 The combination of the aforementioned silicon content and the compaction density of the negative electrode active material layer can effectively improve the energy density, cycle life, and kinetic performance of cylindrical battery cells.

[0042] In some embodiments, based on the mass of the negative electrode active material layer, the silicon content is greater than 5% and less than or equal to 10%, and the compaction density of the negative electrode active material layer is 1.2 g / cm³. 3 Up to 1.55 g / cm 3 The combination of the aforementioned silicon content and the compaction density of the negative electrode active material layer can effectively improve the energy density, cycle life, and kinetic performance of cylindrical battery cells.

[0043] In some embodiments, based on the mass of the negative electrode active material layer, the silicon content is greater than 10% and less than or equal to 20%, and the compaction density of the negative electrode active material layer is 1 g / cm³. 3 Up to 1.45 g / cm 3 The combination of the aforementioned silicon content and the compaction density of the negative electrode active material layer effectively improves the energy density, cycle life, and kinetic performance of cylindrical battery cells.

[0044] In some embodiments, the one-sided density of the negative electrode active material layer is 85 mg / 1540.25 mm². 2 Up to 180 mg / 1540.25 mm 2 The option is 110mg / 1540.25mm. 2 Up to 180 mg / 1540.25 mm 2 The option is 125mg / 1540.25mm. 2 Up to 145 mg / 1540.25 mm 2 .

[0045] When the unilateral density of the negative electrode active material layer is within the above range, the negative electrode capacity will not be too low, and the lithium-ion transport path will not be too long, effectively balancing the energy density, cycle performance, and kinetic performance of the cylindrical battery cell.

[0046] In some embodiments, the lithium-containing transition metal oxide includes a non-lithium metal element, including nickel, with a molar percentage of nickel of 0.80 to 0.95, optionally 0.80 to 0.93, based on the total molar amount of the non-lithium metal element.

[0047] When the molar percentage of nickel is within the above range, the specific capacity of the positive electrode active material is relatively high; when combined with an appropriate amount of silicon in the negative electrode, it can effectively improve the energy density of the battery cell. Moreover, the molar percentage of nickel will not be too high, which can reduce the risk of nickel and other metal elements dissolving and damaging the interface film on the negative electrode surface, and improve the cycle life of the battery cell.

[0048] In some embodiments, lithium-containing transition metal oxides include those with the general formula Li aNi b Co c M d O e A f At least one of the compounds and their modified compounds, 0.8≤a≤1.2, 0.80≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl. The aforementioned materials result in a high specific capacity for the positive electrode active material; when combined with an appropriate amount of silicon in the negative electrode, they can effectively improve the energy density of the battery cell; moreover, the molar proportion of nickel is not too high, which can reduce the risk of nickel and other metal elements dissolving and damaging the interface film on the negative electrode surface, thereby improving the cycle life of the battery cell.

[0049] In some embodiments, the compaction density of the positive electrode active material layer is 3.1 g / cm³. 3 Up to 3.6 g / cm 3 The option is 3.3 g / cm³. 3 Up to 3.5g / cm 3 .

[0050] When the compaction density of the positive electrode active material layer is within the above range, the compaction density of the positive electrode active material layer is controlled to an excellent window. While maximizing the energy density, the risk of performance degradation caused by stress accumulation is reduced, which can effectively balance the energy density, cycle life and dynamic performance of cylindrical battery cells.

[0051] In some embodiments, the unilateral surface density of the positive electrode active material layer is 155 mg / 1540.25 mm². 2 Up to 320mg / 1540.25mm 2 The option is 220mg / 1540.25mm. 2 Up to 280mg / 1540.25mm 2 .

[0052] When the unilateral density of the positive electrode active material layer is within the above range, the positive electrode capacity will not be too low, and the lithium-ion transport path will not be too long, effectively balancing the energy density, cycle life, and kinetic performance of the cylindrical battery cell.

[0053] In some embodiments, the electrode assembly has a wound structure. While the wound structure is advantageous for increasing the capacity of a cylindrical battery cell, its high internal stress can easily lead to the crushing of the positive electrode active material. However, when combined with a negative electrode active material layer comprising graphite and silicon-based materials, and a positive electrode active material layer comprising a single-crystal lithium-containing transition metal oxide, and by synergistically controlling the average particle size of the lithium-containing transition metal oxide, it can effectively improve the energy density, cycle performance, cycle life, and kinetic performance of the cylindrical battery cell.

[0054] In some embodiments, the outer diameter of the casing is between 28 mm and 80 mm. Dimensions within this range, combined with the relevant parameters of the negative and positive electrodes, are beneficial for further improving the energy density, cycle life, and kinetic performance of the cylindrical battery cell.

[0055] Secondly, this application proposes a battery device comprising a plurality of cylindrical battery cells according to any embodiment of the first aspect of this application.

[0056] Thirdly, this application proposes an electrical device, which includes the battery device according to any embodiment of the second aspect of this application. Attached Figure Description

[0057] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0058] Figure 1 A schematic diagram of the vehicle structure provided for some embodiments of this application.

[0059] Figure 2 This is an exploded schematic diagram of a battery pack provided for some embodiments of this application.

[0060] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0061] Figure 4 This is a schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of this application.

[0062] Figure 5 This is an exploded view of a cylindrical battery cell provided for some embodiments of this application.

[0063] Figure 6 This is a schematic diagram of the negative electrode of a cylindrical battery cell provided in some embodiments of this application.

[0064] Figure 7 This is a schematic diagram of the negative electrode of a cylindrical battery cell provided in some other embodiments of this application.

[0065] The accompanying drawings may not be drawn to scale.

[0066] The annotations in the attached figures are explained as follows: X, axial direction; Y, radial direction; 1. Vehicle; 2. Battery pack; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Storage space; 6. Battery module; 7. Cylindrical battery cell; 10. Electrode assembly; 111. First electrode tab; 112. Second electrode tab; 12. Main body; 13. Negative electrode sheet; 131. Negative electrode current collector; 132. Negative electrode active material layer; 1321. First film layer; 1322. Second film layer; 20. Outer shell; 21. Housing; 211. End wall; 212. Side wall; 22. End cap; 30. Electrode terminal; 40. Current collector. Detailed Implementation

[0067] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the cylindrical battery cell, battery assembly, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically 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.

[0068] 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.

[0069] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0070] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0071] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means 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.

[0072] In this application, the term "implementation" means that a specific feature, structure, or characteristic described in connection with an implementation may be included in at least one implementation of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same implementation, nor is it a separate or alternative implementation mutually exclusive with other implementations.

[0073] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0074] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0075] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0076] In this application, "multiple" means two or more (including two).

[0077] In this embodiment of the application, the cylindrical battery cell can be a secondary battery, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used.

[0078] The battery device mentioned in the embodiments of this application refers to a single physical module comprising one or more cylindrical battery cells to provide higher voltage and capacity.

[0079] Compared to carbon-based materials such as graphite, silicon-based materials have a higher theoretical specific capacity, which can improve the negative electrode capacity. To increase the energy density of cylindrical battery cells, silicon-based materials are introduced into the negative electrode. However, with increasing amounts of silicon-based materials, a significant volume expansion effect occurs during charging, causing substantial overall volume expansion of the negative electrode. This leads to excessive compression between the film layers within the electrode assembly, increasing internal stress within the cylindrical battery cell. This increases the risk of cracking and exposing new interfaces in the positive electrode active material, exacerbating side reactions and reducing the cycle performance of the battery cell. Under fast charging conditions, the degree of side reactions is further aggravated, and as these reactions continue, they may increase the resistance to ion transport at the interface, reducing kinetic performance.

[0080] In pursuit of higher energy density, cylindrical battery cells are typically larger in size. For example, the outer diameter of the casing of a cylindrical battery cell is larger. With these dimensions, the internal stress of the cylindrical battery cell increases further, which further reduces the cycle performance and kinetic performance of the battery cell.

[0081] In view of the above problems, this application proposes a cylindrical battery cell with a large casing size. The negative electrode active material layer of this application includes graphite material and silicon-based material, and the positive electrode active material layer includes lithium-containing transition metal oxide. The lithium-containing transition metal oxide includes single crystal particles, and the average particle size of the lithium-containing transition metal oxide is synergistically controlled, which can effectively improve the energy density, kinetic performance and cycle performance under fast charging of the cylindrical battery cell.

[0082] The cylindrical battery cells described in this application are applicable to battery devices and electrical devices that use battery devices.

[0083] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of this application do not impose special limitations on the above-mentioned electrical devices.

[0084] For ease of explanation, the following implementation method uses a vehicle as an example of an electrical device.

[0085] like Figure 1 As shown, a battery device is installed inside the vehicle 1. The battery device can be located at the bottom, front, or rear of the vehicle 1. The battery device can be used to power the vehicle 1; for example, the battery device can serve as the operating power source for the vehicle 1.

[0086] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control the battery device to supply power to motor 4, for example, for the power needs of vehicle 1 during starting, navigation and driving.

[0087] In some embodiments of this application, the battery device can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0088] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple cylindrical battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0089] In some implementations, a battery cell assembly is typically formed by arranging multiple cylindrical battery cells.

[0090] As an example, a battery cell assembly can be a battery module, which consists of multiple cylindrical battery cells arranged and fixed together to form a single module. As another example, a battery module can be formed by bundling multiple cylindrical battery cells together with cable ties.

[0091] In some implementations, the battery device may be a battery pack 2, for example... Figure 1 In the vehicle 1, a battery pack 2 is installed inside.

[0092] The battery pack 2 includes a housing and one or more battery cell assemblies, which are housed within the housing.

[0093] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0094] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple cylindrical battery cells to the housing.

[0095] like Figure 2 As shown, the battery pack 2 includes a housing 5 and cylindrical battery cells ( Figure 2 (Not shown), the cylindrical battery cells are housed inside the casing 5.

[0096] The housing 5 is used to accommodate cylindrical battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a receiving space 5c for accommodating the cylindrical battery cells. The second housing portion 5b may be a hollow structure with an opening on one side, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the opening side of the second housing portion 5b to form a housing 5 with the receiving space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with an opening on one side, with the opening side of the first housing portion 5a covering the opening side of the second housing portion 5b to form a housing 5 with the receiving space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0097] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0098] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0099] In battery pack 2, there can be one or more cylindrical battery cells. If there are multiple cylindrical battery cells, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple cylindrical battery cells are connected in both series and parallel configurations. Multiple cylindrical battery cells can be directly connected in series, parallel, or in a mixed configuration and then housed in the housing 5. Alternatively, multiple cylindrical battery cells can first be connected in series, parallel, or in a mixed configuration to form battery modules 6, and then multiple battery modules 6 can be connected in series, parallel, or in a mixed configuration to form a whole and housed in the housing 5.

[0100] A cylindrical battery cell can be the smallest unit that makes up a battery device.

[0101] In some implementations, the battery device may be an energy storage device.

[0102] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical devices during peak hours.

[0103] In some implementations, energy storage devices include energy storage containers, energy storage cabinets, etc.

[0104] In some implementations, such as Figure 3 As shown, there are multiple cylindrical battery cells 7. These multiple cylindrical battery cells 7 are first connected in series, parallel, or in a mixed manner to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or in a mixed manner to form a whole, which is housed in the casing.

[0105] Multiple cylindrical battery cells 7 in battery module 6 can be electrically connected through busbars to achieve parallel, series, or mixed connection of multiple cylindrical battery cells 7 in battery module 6. There can be one or more busbars, each used to electrically connect at least two cylindrical battery cells 7.

[0106] like Figure 4 and Figure 5 As shown, in some embodiments, the cylindrical battery cell 7 includes an electrode assembly 10 and a housing 20, with the electrode assembly 10 housed within the housing 20.

[0107] The outer casing 20 is a hollow structure, forming an internal space for accommodating the electrode assembly 10 and the electrolyte. The outer casing 20 of the cylindrical battery cell 7 is cylindrical.

[0108] The outer casing 20 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this application embodiment does not impose any special limitations on this. Optionally, the inner wall of the outer casing 20 may also include an insulating layer, which can separate the outer casing 20 from the electrode assembly 10. The material of the insulating layer can be selected from materials commonly used in the art, and is not particularly limited here.

[0109] The electrode assembly 10 housed within the housing 20 may be one or more.

[0110] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening and the end cap 22 closing the opening.

[0111] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the cylindrical battery cell 7. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0112] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the cylindrical battery cell 7.

[0113] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 and the housing 21 can be the same or different.

[0114] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0115] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and an end cap 22 is provided and covers the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0116] In some embodiments, the housing 21 includes a sidewall 212 and an endwall 211 connected to the sidewall 212. The endwall 211 and the end cap 22 are opposite each other along the axial direction of the cylindrical battery cell 7. The end cap 22 is sealed to the sidewall 212. The sidewall 212 is disposed around the electrode assembly 10.

[0117] In some embodiments, end wall 211 and side wall 212 may have the same polarity.

[0118] In some embodiments, the end wall 211 and the side wall 212 may be integrally formed, that is, the housing 21 is a one-piece component. Of course, the end wall 211 and the side wall 212 may also be two separate components, which are then connected together by welding, riveting, bonding or other methods.

[0119] From the external shape of the electrode assembly 10, the electrode assembly 10 includes a main body 12, a first tab 111, and a second tab 112. The first tab 111 and the second tab 112 have opposite polarities and protrude from the main body 12. The first tab 111 is the portion of the first electrode sheet without an active material layer, and the second tab 112 is the portion of the second electrode sheet without an active material layer. The first tab 111 and the second tab 112 are used to draw current from the main body 12. One of the first tab 111 and the second tab 112 is a positive tab, and the other is a negative tab.

[0120] Taking the first tab 111 as the negative electrode tab and the second tab 112 as the positive electrode tab as an example, the portion of the negative electrode current collector in the negative electrode sheet that is not coated with an active material layer can be the negative electrode tab, and the active material coated on the negative electrode current collector in the negative electrode sheet constitutes the negative electrode active material layer. The negative electrode active material layer and the portion of the negative electrode current collector coated with active material can be part of the main body 12. Similarly, the portion of the positive electrode current collector in the positive electrode sheet that is not coated with an active material layer can be the positive electrode tab, and the active material coated on the positive electrode current collector in the positive electrode sheet constitutes the positive electrode active material layer. The positive electrode active material layer and the portion of the positive electrode current collector coated with active material can be part of the main body 12.

[0121] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out portion and a second electrode lead-out portion, the first electrode lead-out portion being electrically connected to a first tab 111, and the second electrode lead-out portion being electrically connected to a second tab 112.

[0122] In the axial direction of the main body 12, the first electrode lead-out portion and the second electrode lead-out portion may also be located on both sides of the electrode assembly 10, or the first electrode lead-out portion and the second electrode lead-out portion may be located on the same side of the electrode assembly 10. For example, the second electrode lead-out portion includes an electrode terminal 30 insulated on the end wall 211, and the first electrode lead-out portion is the end wall 211.

[0123] The first tab 111 and the second tab 112 can extend from the same side of the main body 12, or they can extend from opposite sides respectively.

[0124] The first electrode tab 111 and the second electrode tab 112 may be respectively disposed on both sides of the main body 12 along the axial direction. In other words, the first electrode tab 111 and the second electrode tab 112 are respectively disposed at both ends of the electrode assembly 10 along the axial direction.

[0125] Optionally, the first tab 111 is wound multiple times around the central axis of the electrode assembly 10, and the first tab 111 includes multiple tab layers. After winding, the first tab 111 is generally cylindrical, with gaps between adjacent tab layers. In this embodiment, the first tab 111 can be processed to reduce the gaps between tab layers, facilitating connection between the first tab 111 and other conductive structures. For example, in this embodiment, the first tab 111 can be flattened to gather and aggregate the ends of the first tab 111 away from the main body 12; the flattening process forms a dense end face at the end of the first tab 111 away from the main body 12, reducing the gaps between tab layers and facilitating connection between the first tab 111 and other conductive structures. Alternatively, in this embodiment, conductive material can be filled between adjacent tab layers to reduce the gaps between tab layers.

[0126] Optionally, the second tab 112 is wound around the central axis of the electrode assembly 10 multiple times, and the second tab 112 includes multiple tab layers. Exemplarily, the second tab 112 is also flattened to reduce the gaps between the tab layers of the second tab 112.

[0127] The first tab 111 is electrically connected to the end cap 22. The first tab 111 can be directly electrically connected to the end cap 22, or it can be indirectly electrically connected to the end cap 22 through other conductive structures. The end cap 22 is electrically connected to the end wall 211.

[0128] The second tab 112 is electrically connected to the electrode terminal 30 of the cylindrical battery cell 7, and the electrode terminal 30 is insulated from the end wall 211. The second tab 112 can be directly electrically connected to the electrode terminal 30, or it can be indirectly electrically connected to the electrode terminal 30 through other conductive structures.

[0129] In some embodiments, the second tab 112 can be directly connected to the electrode terminal 30, for example, by welding, abutting, or other means. Alternatively, the second tab 112 can also be indirectly connected to the electrode terminal 30 via other conductive components (e.g., current collector 40) to achieve electrical connection between the second tab 112 and the electrode terminal 30.

[0130] The electrode terminal 30 is insulated from the end wall 211. Therefore, the electrode terminal 30 and the end wall 211 can have different polarities and can serve as different output poles.

[0131] The end wall 211 may be provided with an electrode lead-out hole. The electrode terminal 30 is insulated on the end wall 211 and installed in the electrode lead-out hole. The electrode lead-out hole facilitates the lead-out of the electrical energy of the electrode assembly 10 to the outside of the housing 21.

[0132] The central axis of the electrode assembly 10 is a virtual straight line. The central axis of the electrode assembly 10 can pass through the electrode lead-out hole or be offset from the electrode lead-out hole. This application does not limit this.

[0133] The electrode terminal 30 can be fixed to the end wall 211. The electrode terminal 30 can be fixed as a whole to the outside of the end wall 211, or it can extend into the inside of the housing 20 through the electrode lead-out hole.

[0134] When the first tab 111 is the negative tab and the second tab 112 is the positive tab, the end wall 211 is the negative output terminal of the cylindrical battery cell 7, and the electrode terminal 30 is the positive output terminal of the cylindrical battery cell 7.

[0135] Electrode assembly 10 is the component in the cylindrical battery cell 7 where the electrochemical reaction occurs.

[0136] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of the cylindrical battery cell 7, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. Optionally, the electrode assembly 10 also includes a separator disposed between the positive and negative electrodes, which can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0137] In some embodiments, the positive electrode can be a positive electrode sheet, which can include a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, the positive active material layer including a positive active material.

[0138] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0139] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, titanium, silver-surfaced aluminum, or stainless steel can be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0140] As an example, the positive electrode active material may include at least one of the following materials: phosphate, lithium-containing transition metal oxide, and their respective modified compounds; optionally, the positive electrode active material may include lithium-containing transition metal oxide and their respective modified compounds, which is beneficial to improving the energy density of the battery cell. However, this application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material layer of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more.

[0141] Examples of phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0142] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not have a positive electrode active material layer. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0143] In some embodiments, the positive electrode active material layer may optionally include a positive electrode conductive agent. This application does not impose particular limitations on the type of positive electrode conductive agent. As an example, the positive electrode conductive agent includes at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent in the positive electrode active material layer is ≤5 wt%.

[0144] In some embodiments, the positive electrode active material layer may optionally include a positive electrode binder. This application does not impose particular limitations on the type of positive electrode binder. As an example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. In some embodiments, the mass percentage of the positive electrode binder in the positive electrode active material layer is ≤5 wt%.

[0145] The positive electrode active material layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent may include, but is not limited to, N-methylpyrrolidone (NMP).

[0146] In some embodiments, the negative electrode can be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

[0147] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0148] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material base layer (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0149] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in cylindrical battery cells 7. As an example, the negative electrode active material may include at least one of the following materials: carbon-based materials (e.g., carbon-based materials include at least one of artificial graphite, natural graphite, soft carbon, and hard carbon), silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active material layers in batteries may also be used. These negative electrode active material layers may be used alone or in combination of two or more.

[0150] In some embodiments, the negative electrode active material layer may optionally include a negative electrode conductive agent. This application does not impose particular limitations on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent in the negative electrode active material layer is ≤5 wt%.

[0151] In some embodiments, the negative electrode active material layer may optionally include a negative electrode binder. This application does not impose particular limitations on the type of negative electrode binder. As an example, the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage of the negative electrode binder in the negative electrode active material layer is ≤5 wt%.

[0152] In some embodiments, the negative electrode active material layer may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, the mass percentage of other additives in the negative electrode active material layer is ≤2 wt%.

[0153] In some implementations, the material of the positive current collector may include aluminum, and the material of the negative current collector may include copper.

[0154] In some embodiments, the separator includes a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0155] The embodiments of this application do not have any particular restrictions on the type of separator membrane, and any known porous structure separator membrane with good chemical and mechanical stability can be selected.

[0156] In some embodiments, the material of the separator may include one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may 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 may be the same or different, without particular limitation.

[0157] In some embodiments, the separator may include a porous base membrane and a coating disposed on at least one side of the porous base membrane, the coating may include at least one of inorganic particles or organic polymers.

[0158] Porous base membranes may include one or more of polyethylene and polypropylene.

[0159] Inorganic particles possess good heat resistance, which can improve the overall heat resistance of the separator. Within the operating voltage range of the cylindrical battery cell, inorganic particles will not undergo oxidation and reduction reactions with metal dendrites. In other words, inorganic particles are configured to not undergo oxidation and reduction reactions with alkali metals and / or alkaline earth metals at the nominal voltage of the cylindrical battery cell.

[0160] In some embodiments, the inorganic particles include one or more of boehmite γ-AlOOH, aluminum oxide Al2O3, aluminum hydroxide Al(OH)3, barium sulfate BaSO4, magnesium oxide MgO, magnesium hydroxide Mg(OH)2, calcium oxide CaO, cerium oxide CeO2, zirconium titanate SrTiO3, barium titanate BaTiO3, and magnesium fluoride MgF2.

[0161] In some embodiments, the organic polymer includes one or more of fluoropolymers or polyacrylic acid polymers. Specifically, the fluoropolymers include one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and tetrafluoroethylene-hexafluoropropylene copolymer. The polyacrylic acid polymers include one or more of polyacrylic acid and fluorinated acrylate resins.

[0162] In some embodiments, the cylindrical battery cell 7 also includes an electrolyte.

[0163] During the charging and discharging process of the cylindrical battery cell 7, active ions repeatedly insert and extract between the positive and negative electrode plates, while the electrolyte acts as a conductor for these active ions. This application does not impose any particular restrictions on the type of electrolyte; it can be selected according to actual needs.

[0164] Electrolytes consist of electrolyte salts and solvents. The types of electrolyte salts and solvents are not specifically limited and can be selected according to actual needs.

[0165] As an example, the electrolyte salt may include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0166] As an example, the solvent may include, but is not limited to, one or more of the following: ethylene carbonate EC, propylene carbonate PC, methyl ethyl carbonate EMC, diethyl carbonate DEC, dimethyl carbonate DMC, dipropyl carbonate DPC, methyl propyl carbonate MPC, ethyl propyl carbonate EPC, butylene carbonate BC, fluoroethylene carbonate FEC, methyl formate MF, methyl acetate MA, ethyl acetate EA, propyl acetate PA, methyl propionate MP, ethyl propionate EP, propyl propionate PP, methyl butyrate MB, ethyl butyrate EB, 1,4-butyrolactone GBL, sulfolane SF, dimethyl sulfone MSM, methyl ethyl sulfone EMS, and diethyl sulfone ESE.

[0167] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0168] For example, the additives include at least one of the following: cyclic carbonate compounds containing unsaturated bonds, sulfate compounds, sulfite compounds, sulfonyl lactone compounds, disulfonic acid compounds, nitrile compounds, aromatic compounds, isocyanate compounds, phosphonitrile compounds, acid anhydrides, cyclic acid anhydride compounds, phosphite compounds, phosphate compounds, borate esters, and carboxylic acid esters.

[0169] like Figures 4 to 6 As shown, in some embodiments, the electrode assembly 10 can be a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0170] In some embodiments, the cylindrical battery cell 7 includes a housing 20, an electrode assembly 10, and an electrolyte. The electrode assembly 10 is disposed within the housing 20 and includes a positive electrode and a negative electrode 13. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector. The negative electrode 13 includes a negative electrode current collector 131 and a negative electrode active material layer 132 disposed on at least one side of the negative electrode current collector 131, wherein, The outer diameter of the outer casing 20 is greater than or equal to 28 mm; The negative electrode active material layer 132 comprises carbon-based materials and silicon-based materials. The carbon-based materials include graphite. Based on the mass of the negative electrode active material layer 132, the mass content of silicon in the negative electrode active material layer 132 is greater than or equal to 0.5%. The positive electrode active material layer includes lithium-containing transition metal oxide, which includes single crystal particles with an average particle size of 1.5 μm to 7.5 μm.

[0171] The cylindrical battery cell 7 has a cylindrical or near-cylindrical shape and its internal cavity is a cylindrical or near-cylindrical cavity; the radial direction Y of the cylindrical battery cell 7 is perpendicular to the axial direction X. Figure 4 Y1 shown in the figure represents the outer diameter of the outer casing 20; The outer diameter of the outer shell 20 is relatively large, which can provide more storage space for the positive and negative electrode active materials; Under the aforementioned shell size 20, the positive electrode active material layer of this application embodiment includes a lithium-containing transition metal oxide. The specific capacity of the lithium-containing transition metal oxide is relatively high, which is beneficial to improving the positive electrode capacity. A silicon-based material is introduced into the negative electrode active material layer. The amount of silicon-based material added is not too low, so that the mass content of silicon element is greater than or equal to 0.5%, thereby improving the negative electrode capacity. This allows lithium ions extracted from the positive electrode active material layer to be embedded in the negative electrode active material layer, so that the positive electrode capacity can be fully utilized, thereby improving the energy density of the cylindrical battery cell 7. During the charging process of the cylindrical battery cell 7, the silicon-based material exhibits a volume expansion effect. As the mass content of silicon increases, the volume expansion of the negative electrode active material layer 132 intensifies, leading to increased compression of the internal film layer of the electrode assembly 10. This can cause cracking of lithium-containing transition metal oxide particles, exacerbating interfacial side reactions and reducing cycle and kinetic performance. Furthermore, with a larger outer diameter of the outer shell 20, the compression of the electrode assembly 10 within the shell 20 intensifies, further aggravating the side reactions within the system. Under fast charging conditions, the degree of side reactions within the system is further aggravated. Therefore, in this embodiment, graphite material is introduced into the negative electrode active material layer. Graphite material has a small volume expansion and excellent structural stability, which can reduce the overall volume expansion of the negative electrode active material layer 132 to a certain extent, thereby reducing the compression of the internal film layer of the electrode assembly 10, reducing internal stress, alleviating the damage caused by stress to the positive electrode sheet, and reducing the risk of cracking of lithium-containing transition metal oxides. In another aspect of this application, the lithium-containing transition metal oxide includes micron-sized single-crystal particles. The single-crystal particles have excellent structural stability, and even if the positive electrode active material layer is subjected to a certain degree of extrusion, the lithium-containing transition metal oxide is not easy to crack, thereby improving interface stability and improving cycle life under fast charging. However, the micron-sized single-crystal structure results in a long solid-phase transport path for lithium ions, leading to poor kinetic performance and hindering cycling. Therefore, the volume-average particle size of the lithium-containing transition metal oxide in this embodiment is not too large, thereby shortening the solid-phase transport path for lithium ions; and the particle size of the lithium-containing transition metal oxide is not too small, so that the active surface area is not too high, thereby reducing surface side reactions and improving the cycling performance and kinetic performance of the cylindrical battery cell 7 under fast charging.

[0172] In summary, the negative electrode active material layer of the embodiments of this application includes graphite material and silicon-based material, and the positive electrode active material layer includes lithium-containing transition metal oxide, which includes a single crystal structure. By synergistically controlling the average particle size of the lithium-containing transition metal oxide, it is possible to effectively improve the energy density, kinetic performance and cycle performance under fast charging of the cylindrical battery cell 7.

[0173] Especially when the electrode assembly 10 is a wound structure, the positive electrode sheet, the negative electrode sheet 13 and the separator are wound into the electrode assembly 10. During the charging process of the cylindrical battery cell 7, the volume expansion of the negative electrode sheet 13 will cause the internal stress of the electrode assembly 10 to be too high, which will further increase the risk of the active material being squeezed and cracked. By adding an appropriate amount of silicon and introducing graphite material, especially natural graphite, into the negative electrode active material layer 132, it is possible to effectively improve the energy density, dynamic performance and cycle performance under fast charging of the cylindrical battery cell 7.

[0174] In some embodiments, the outer diameter of the housing 20 is greater than or equal to 28 mm.

[0175] When the size of the casing 20 is too small, the amount of positive and negative electrode active materials that can be accommodated inside the casing 20 is small, resulting in a relatively low energy density of the cylindrical battery cell 7.

[0176] The size of the casing 20 is within the above range, which is conducive to increasing the amount of positive and negative electrode active materials added inside the casing 20, thereby improving the energy density of the cylindrical battery cell 7. The size of the casing 20, combined with the mass content of silicon element, the lithium-containing transition metal oxide including single crystal structure, and the synergistic control of the average particle size of the lithium-containing transition metal oxide of single crystal structure, can effectively improve the energy density, cycle performance and kinetic performance of the cylindrical battery cell 7.

[0177] Optionally, the outer diameter of the housing 20 is 28 mm to 80 mm. For example, the outer diameter of the housing 20 is 28 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, or any range of two of the above values.

[0178] The dimensions of the casing 20 are within the aforementioned range, which is beneficial for further improving the energy density, cycle life, and dynamic performance of the cylindrical battery cell 7.

[0179] [Negative electrode plate 13] In some embodiments, the silicon content in the negative electrode active material layer 132 is greater than or equal to 0.5% by mass, based on the mass of the negative electrode active material layer 132.

[0180] When the silicon content is too low, the negative electrode capacity is too low, making it impossible to increase the energy density of the cylindrical battery cell 7. With the silicon content within the aforementioned range, on the one hand, the silicon content will not be too low, which can increase the negative electrode capacity and the energy density of the cylindrical battery cell 7; on the other hand, the silicon content will not be too high, which, when combined with graphite materials such as natural graphite, can reduce the expansion of the negative electrode sheet 13 along its own thickness direction, reduce the risk of lithium-containing transition metal oxides being squeezed and cracked, and improve the cycle performance of the cylindrical battery cell 7.

[0181] For example, based on the mass of the negative electrode active material layer 132, the mass content of silicon in the negative electrode active material layer 132 is 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 8%, 10%, 12%, 15%, 18%, 20%, or a range of any two of the above values. Optionally, based on the mass of the negative electrode active material layer 132, the mass content of silicon is 0.5% to 20%, optionally 1% to 15%, optionally 1% to 10%, optionally 2% to 8%.

[0182] When the mass content of silicon is within the above range, its combination with materials such as graphite can further improve the energy density, cycle performance, and kinetic performance of the cylindrical battery cell 7.

[0183] In some embodiments, based on the mass of the negative electrode active material layer 132, the mass content of the silicon-based material is 1% to 40%, optionally 2% to 30%. Exemplarily, based on the mass of the negative electrode active material layer 132, the mass content of the silicon-based material is 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or a range of any two of the above values.

[0184] When the mass content of silicon-based materials is within the above range, it is possible to further improve the energy density, cycle life, and kinetic performance of the cylindrical battery cell 7.

[0185] In some embodiments, the silicon-based material includes one or more of silicon-carbon materials, elemental silicon, silicon oxide, silicon-nitrogen composites, and silicon alloys.

[0186] The aforementioned silicon-based material has a high specific capacity, which can improve the negative electrode capacity. When combined with graphite material, it can reduce the overall volume expansion of the negative electrode sheet 13 and improve the cycle life of the cylindrical battery cell 7.

[0187] Optionally, the silicon-based material includes silicon-carbon materials, such as porous carbon structures and nano-silicon disposed within the porous carbon structures. This material has a smaller volume effect, which can reduce the volume expansion of the negative electrode 13, weaken the internal stress of the inner ring of the electrode assembly 10, alleviate stress damage to the positive electrode, and improve the cycle life of the cylindrical battery cell 7.

[0188] Optionally, the silicon-based material includes silicon oxide, which has weak surface activity and few side reactions, thus improving the cycle life of the cylindrical battery cell 7.

[0189] In some implementations, the graphite material content is 55% to 96% based on the mass of the negative electrode active material layer, for example, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, or any combination of two of the above values.

[0190] Graphite materials have a smaller volume expansion. The combination of graphite materials and silicon-based materials helps to reduce the overall volume expansion of the negative electrode active material layer 132, thereby improving the cycle performance and kinetic performance of the cylindrical battery cell 7.

[0191] For example, graphite materials include one or more of natural graphite and artificial graphite.

[0192] Artificial graphite has relatively weak surface activity and a weaker degree of side reaction with electrolyte, which can further improve the cycle life of cylindrical battery cells 7.

[0193] Optionally, the graphite material includes natural graphite. Natural graphite has a spherical or near-spherical structure and exhibits slip properties. Natural graphite can provide expansion space for the silicon-based material through slippage, thereby mitigating the overall expansion of the negative electrode 13 and improving the cycle life and kinetic performance of the cylindrical battery cell 7.

[0194] In some implementations, the mass content of natural graphite is 1% to 40% based on the mass of the negative electrode active material layer, for example, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any combination of two of the above values.

[0195] Within the aforementioned mass content range, natural graphite, when combined with silicon-based materials, can reduce the overall expansion of the negative electrode 13; moreover, the mass content of natural graphite will not be too high, which can reduce the side reactions on the surface of natural graphite and improve the cycle life and dynamic performance of the cylindrical battery cell 7.

[0196] In some embodiments, the carbon-based material also includes one or more of hard carbon and soft carbon.

[0197] The qualitative and quantitative analysis of each substance or element in this application can be performed using suitable equipment and methods known to those skilled in the art. Relevant testing methods can be referenced from domestic and international testing standards and enterprise standards. Furthermore, those skilled in the art can adaptively modify certain testing steps / instrument parameters from the perspective of testing accuracy to obtain more accurate results. One testing method can be used for qualitative or quantitative analysis, or several testing methods can be used in combination for qualitative or quantitative determination.

[0198] For example, the graphite material in this application can be subjected to X-ray powder diffraction testing and qualitative analysis of the negative electrode sheet or negative electrode active material in accordance with the general rules of X-ray diffraction analysis in JIS / K0131-2009.

[0199] Artificial graphite and natural graphite can be distinguished by SEM cross-sectional images taken by scanning electron microscope (SEM). Natural graphite has gaps between the sheet-like structures in its SEM cross-section, while artificial graphite has a dense structure with no obvious gaps. Alternatively, they can be distinguished by XRD patterns obtained by X-ray diffraction. Natural graphite has obvious 2H and 3R phases in its XRD pattern, while artificial graphite has a 2H phase in its XRD pattern.

[0200] The elemental silicon, silicon-carbon materials, and silicon oxide SiOx (0 < x ≤ 2) mentioned in this application can also be tested and qualitatively analyzed using the above-mentioned X-ray diffraction. Silicon can also be qualitatively and quantitatively analyzed by referring to JY / T 0567-2020 "General Rules for Inductively Coupled Plasma Emission Spectrometry Analysis". Alternatively, the surface elements of the negative electrode sheet or the cross-sectional elements after ion polishing can be analyzed by referring to GB / T17359-2023 standard.

[0201] In some embodiments, the average particle size of the silicon-based material is from 1 μm to 12 μm, for example, 1 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm or any range of two of the above values.

[0202] When the average particle size of the silicon-based material is within the above range, the volume expansion of the silicon-based material will not be too high, and the degree of side reaction with the electrolyte will not be excessive, which is beneficial to balance the cycle performance and kinetic performance of the cylindrical battery cell 7.

[0203] In some embodiments, the average particle size of the carbon-based material is 10 μm to 18 μm, for example 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm or any combination of two of the above values.

[0204] Carbon-based materials refer to all carbon-based materials in the negative electrode active material layer 132, and the average particle size of carbon-based materials refers to the average particle size of all carbon-based materials in the negative electrode active material layer 132.

[0205] For example, the carbon-based material of the second film layer 1322 includes natural graphite and artificial graphite, and the average particle size of the carbon-based material refers to the average particle size of natural graphite and artificial graphite in the negative electrode active material layer 132.

[0206] When the average particle size of the carbon-based material is within the above range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life of the cylindrical battery cell 7.

[0207] In some embodiments, the negative electrode active material layer includes a negative electrode active material with an average particle size of 5 μm to 18 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, or any combination of two of the above values.

[0208] The negative electrode active material refers to all the active materials in the negative electrode active material layer 132, and the average particle size of the negative electrode active material refers to the average particle size of all the active materials in the negative electrode active material layer 132.

[0209] For example, when the silicon-based material is silicon-carbon material, the negative electrode active material includes silicon-carbon material, natural graphite, and artificial graphite, in which case the average particle size of the negative electrode active material is 5 μm to 10 μm.

[0210] For example, when the silicon-based material is silicon oxide, the negative electrode active material includes silicon carbon materials, natural graphite, and artificial graphite, in which case the average particle size of the negative electrode active material is 5 μm to 18 μm.

[0211] When the average particle size of the negative electrode active material is within the above range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life of the cylindrical battery cell 7.

[0212] In this embodiment, the negative electrode sheet is cut along its thickness direction to expose the cross-section of the negative electrode active material layer. This can be achieved through ion polishing (CP) and scanning electron microscopy (SEM). The complete cross-section of the negative electrode sheet is observed to obtain an SEM image. Based on the microscopic morphology of the SEM image, more than 100 active material particles in the negative electrode active material layer are observed, and the average particle size is calculated using image analysis. This average particle size is used as the average particle size of the negative electrode active material layer. If the particles are not circular, the major axis of the particles can be used as the particle size. More than 100 silicon-based particles in the negative electrode active material layer are observed, and their average particle size is calculated using image analysis. More than 100 carbon-based particles in the negative electrode active material layer are observed, and their average particle size is calculated using image analysis. This average particle size is used as the average particle size of the carbon-based particles.

[0213] The negative electrode active material layer 132 in the embodiments of this application can be a single-layer film or at least two-layer film.

[0214] When the negative electrode active material layer 132 is a single-layer film, the performance of the negative electrode active material layer 132 is relatively uniform, resulting in excellent kinetic performance of the negative electrode active material layer 132. Figure 6 The diagram shows that the negative electrode active material layer 132 is a single-layer film.

[0215] like Figure 7 As shown, when the negative electrode active material layer 132 is at least two film layers, the negative electrode active material layer 132 may include two film layers, three film layers, four film layers, or even more film layers.

[0216] Taking the negative electrode active material layer 132 as an example of two film layers, the negative electrode active material layer 132 includes a first film layer 1321 and a second film layer 1322 stacked together. The first film layer 1321 is located between the negative electrode current collector 131 and the second film layer 1322. The first film layer 1321 is disposed on the surface of the negative electrode current collector 131. The second film layer 1322 is located on the side of the first film layer 1321 away from the negative electrode current collector 131. The interface between the first film layer 1321 and the second film layer 1322 can be regular or irregular.

[0217] The cylindrical battery cell 7 can be disassembled to obtain the negative electrode 13. The complete cross-section of the negative electrode 13 is observed to obtain the cross-section morphology (CP). The boundary between the first film layer 1321 and the second film layer 1322 is confirmed based on the obvious discontinuous changes in the micromorphology in the CP diagram. The thickness of the first film layer 1321 and the thickness of the second film layer 1322 can be measured.

[0218] Second film layer 1322 The second film layer 1322 can be understood as the film layer in the negative electrode active material layer 132 that is away from the negative electrode current collector 131. Compared with the first film layer 1321, the second film layer 1322 is closer to the separator. During charging, active ions such as lithium ions pass through the second film layer 1322 and the first film layer 1321 in sequence.

[0219] In some embodiments, a silicon-based material is disposed in the second film layer 1322.

[0220] In some embodiments, based on the mass of the second film layer 1322, the mass content of silicon element is 10% to 30%, for example, 10%, 15%, 20%, 25%, 30%, or a range of any two of the above values.

[0221] When the mass content of silicon is within the above range, it is possible to further improve the energy density and cycle life of the cylindrical battery cell 7.

[0222] In some embodiments, based on the mass of the second film layer 1322, the mass content of the silicon-based material is 20% to 60%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any combination of two of the above values.

[0223] When the mass content of silicon-based materials is within the above range, it is possible to further improve the energy density, cycle life, and kinetic performance of the cylindrical battery cell 7.

[0224] In some embodiments, the second film layer 1322 includes a graphite material. Compared to silicon-based materials, graphite materials have less volume expansion. The combination of graphite and silicon-based materials helps to reduce the overall volume expansion of the second film layer 1322, thereby improving the cycle performance of the cylindrical battery cell 7.

[0225] In some embodiments, based on the mass of the second film layer 1322, the mass content of the graphite material is 20% to 80%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 80%, or a range of any two of the above values.

[0226] When the mass content of graphite material is within the above range, its combination with silicon-based materials can reduce the overall volume expansion of the negative electrode active material layer 132, thereby improving the cycle performance of the cylindrical battery cell 7.

[0227] In some embodiments, the graphite material of the second film layer 1322 includes one or more of natural graphite and artificial graphite.

[0228] Optionally, the graphite material of the second film layer 1322 includes natural graphite and artificial graphite. Artificial graphite has relatively weak surface activity and a weaker degree of side reaction with the electrolyte, which can further improve the cycle life and kinetic performance of the cylindrical battery cell 7.

[0229] Optionally, the graphite material of the second film layer 1322 includes natural graphite. Natural graphite has slip properties, and when the silicon-based material undergoes volume expansion, natural graphite can provide expansion space for the silicon-based material through slippage, thereby mitigating the volume expansion of the electrode thickness layer to a certain extent. This reduces the compression of the internal film layer of the electrode assembly 10, reduces internal stress, improves the structural stability of the active material, and improves cycling and kinetic performance.

[0230] In some embodiments, the mass content of natural graphite, based on the second film layer 1322, is 5% to 40%, optionally 10% to 35%. For example, based on the second film layer 1322, the mass content of natural graphite is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or a range of any two of the above values.

[0231] The second film layer 1322 includes silicon-based materials and natural graphite. Within the above-mentioned mass content range, the natural graphite can provide expansion space for the silicon-based materials through slippage, thereby reducing the overall expansion of the negative electrode sheet 13. Moreover, the mass content of natural graphite will not be too high, which can reduce the interfacial side reactions of natural graphite and improve the cycle life of the cylindrical battery cell 7.

[0232] In some embodiments, the carbon-based material in the second film layer 1322 may also include one or more of hard carbon and soft carbon.

[0233] In some embodiments, the average particle size of the carbon-based material in the second film layer 1322 is 10 μm to 18 μm, for example, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm or any combination of two of the above values.

[0234] The carbon-based material of the second film layer 1322 refers to all the carbon-based materials in the second film layer 1322, and the average particle size of the carbon-based material in the second film layer 1322 refers to the average particle size of all the carbon-based materials in the second film layer 1322.

[0235] For example, the carbon-based material of the second film layer 1322 is natural graphite, and the average particle size of the carbon-based material of the second film layer 1322 refers to the average particle size of the natural graphite in the second film layer 1322.

[0236] For example, the carbon-based material of the second film layer 1322 is natural graphite and artificial graphite, and the average particle size of the carbon-based material of the second film layer 1322 refers to the average particle size of natural graphite and artificial graphite in the second film layer 1322.

[0237] When the average particle size of the carbon-based material in the second film layer 1322 is within the above range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life and kinetic performance of the cylindrical battery cell 7.

[0238] In some embodiments, the average particle size of the active material in the second film layer 1322 is from 5 μm to 18 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm or any combination of two of the above values.

[0239] The active material in the second membrane layer 1322 refers to all active materials in the second membrane layer 1322, and the average particle size refers to the average particle size of all active materials in the second membrane layer 1322.

[0240] For example, when the silicon-based material is silicon-carbon material, the active material in the second film layer 1322 includes silicon-carbon material and natural graphite. In this case, the average particle size of the active material in the second film layer 1322 is 5 μm to 10 μm.

[0241] For example, when the silicon-based material is silicon oxide, the active material in the second film layer 1322 includes silicon oxide and natural graphite. In this case, the average particle size of the active material in the second film layer 1322 is 5 μm to 18 μm.

[0242] When the average particle size of the active material in the second film layer 1322 is within the above range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life and kinetic performance of the cylindrical battery cell 7.

[0243] In this embodiment, the negative electrode sheet is cut along its thickness direction to expose the cross-section of the negative electrode active material layer. The complete cross-section of the negative electrode sheet is observed to obtain a CP (Positioning Conversion) image. The boundary between the first and second film layers is confirmed based on the obvious discontinuous changes in the microstructure of the CP image. Subsequently, EDS (Electronic Data Separation) analysis is used to identify the elemental types, thus determining the first active material (e.g., a first carbon-based material) in the first film layer within the CP image, and the second active material (e.g., a silicon-based material) in the second film layer and the carbon-based material of the second film layer 1322. More than 100 active material particles in the second film layer are observed, and the average particle size is calculated using image analysis as the average particle size of the second active material. In cases where the particles are not circular, the major axis of the particle can be used as the particle size. More than 100 silicon-based particles in the second film layer are observed, and their average particle size is calculated using image analysis as the average particle size of the silicon-based particles. More than 100 carbon-based particles in the second film layer are observed, and their average particle size is calculated using image analysis as the average particle size of the carbon-based particles.

[0244] First membrane layer 1321 The first film layer 1321 is the film layer in the negative electrode active material layer 132 that is close to the negative electrode current collector 131.

[0245] In some embodiments, the first film layer 1321 comprises a carbon-based material.

[0246] Optionally, the first film layer 1321 may not include silicon-based materials. All silicon-based materials are disposed in the second film layer 1322. The mass content of silicon-based materials in the second film layer 1322 is appropriate, resulting in a shorter ion transport path for the silicon-based materials in the second film layer 1322 during charging and discharging of the cylindrical battery cell 7. Furthermore, the first film layer 1321 includes a first carbon-based material, which has excellent conductivity. The combination of multiple film layers is beneficial for improving the transport performance of ions and electrons, thereby improving the kinetic performance of the cylindrical battery cell 7.

[0247] Furthermore, the negative electrode active material layer 132 is configured as a multilayer structure, with silicon-based materials and graphite materials disposed in the film layer away from the negative electrode current collector 131, and graphite materials included in the film layer near the negative electrode current collector 131. This facilitates the construction of pore differences in the multilayer film layer, thereby improving electrolyte wettability and enhancing the cycle performance of the cylindrical battery cell 7.

[0248] Of course, the first film layer 1321 may also include silicon-based materials, in which case it is beneficial to improve the energy density of the cylindrical cell 7.

[0249] In some embodiments, the graphite material of the first film layer 1321 includes one or more of natural graphite and artificial graphite. Optionally, the graphite material of the first film layer 1321 includes artificial graphite. Artificial graphite has a denser structure, a more regular crystal structure, and an ordered interlayer arrangement, resulting in superior cycle stability and effectively improving the cycle performance of the cylindrical battery cell 7.

[0250] In some embodiments, the carbon-based material of the first film layer 1321 further includes one or more of hard carbon and soft carbon.

[0251] In some embodiments, the average particle size of the carbon-based material of the first film layer 1321 is 10 μm to 18 μm, for example 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm or any combination of two of the above values.

[0252] The average particle size of the carbon-based material in the first film layer 1321 refers to the average particle size of all carbon-based materials in the first film layer 1321.

[0253] For example, the carbon-based material of the first film layer 1321 is artificial graphite, and the average particle size of the carbon-based material of the first film layer 1321 refers to the average particle size of the artificial graphite in the first film layer 1321.

[0254] For example, the carbon-based material of the first film layer 1321 is natural graphite and artificial graphite, and the average particle size of the carbon-based material of the first film layer 1321 refers to the average particle size of natural graphite and artificial graphite in the first film layer 1321.

[0255] When the average particle size of the carbon-based material in the first film layer 1321 is within the above-mentioned range, the active surface area is relatively small, which can reduce the degree of side reactions and thus improve the cycle life and kinetic performance of the cylindrical battery cell 7.

[0256] In the embodiments of this application, the average particle size of the active material of the first film layer 1321 can be determined by referring to the test method of the average particle size of the active material of the second film layer 1322, which will not be repeated here.

[0257] In some embodiments, the thickness of the negative electrode active material layer 132 is from 45 μm to 75 μm, for example, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, or any combination of two of the above values. When the thickness of the negative electrode active material layer 132 is within the above range, it can improve the energy density, cycle life, and kinetic performance of the cylindrical battery cell 7. Figure 7 The H shown in the figure represents the thickness of the negative electrode active material layer 132.

[0258] In some embodiments, the thickness ratio of the second film layer 1322 to the first film layer 1321 is from 0.125 to 1, and may be selected as from 0.125 to 0.25. Exemplarily, the thickness ratio of the second film layer 1322 to the first film layer 1321 is 0.125, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or a range consisting of any two of the above values.

[0259] When the thickness ratio of the second film layer 1322 to the first film layer 1321 is within the above range, it is beneficial to reduce the overall volume expansion of the negative electrode sheet 13 and improve the cycle life and dynamic performance of the cylindrical battery cell 7.

[0260] For example, the thickness of the second film layer 1322 is from 5 μm to 20 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or any combination of two of the above values. The relatively thin thickness of the second film layer 1322 is beneficial to reducing the overall volume expansion of the negative electrode 13 and improving the cycle life and kinetic performance of the cylindrical battery cell 7. Figure 7 H2 shown in the figure represents the thickness of the second film layer 1322.

[0261] For example, the thickness of the first film layer 1321 is from 40 μm to 55 μm, such as 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, or any combination of two of the above values. The relatively thick thickness of the first film layer 1321 is beneficial for increasing energy density and improving the cycle life and kinetic performance of the cylindrical battery cell 7. Figure 7 H1 shown in the figure represents the thickness of the first film layer 1321.

[0262] In some embodiments, the compaction density of the negative electrode active material layer 132 is 1 g / cm³. 3 Up to 1.65 g / cm 3 For example, 1 g / cm³, 1.1 g / cm³, 1.3 g / cm³, 1.4 g / cm³, 1.5 g / cm³, 1.6 g / cm³, 1.65 g / cm³, or any range of two of the above values.

[0263] When the compaction density of the negative electrode active material layer 132 is within the above range, a stable and appropriate bond can be formed between the negative electrode active material layer 132 and the negative electrode current collector 131. During the cycling process, the negative electrode active material layer 132 is not easy to peel off from the negative electrode current collector 131; moreover, the particle packing is not too compact and dense, which can effectively reduce the risk of internal stress concentration. Moreover, the negative electrode active material layer 132 has an appropriate porous network structure, which is conducive to the electrolyte wetting and reflux during the circulation process, and fully wetting the electrode assembly 10. When the compaction density of the negative electrode active material layer 132 is within the above range, the compaction density of the negative electrode active material layer 132 is controlled to an excellent window. While maximizing the energy density, the risk of performance degradation caused by stress accumulation is reduced, and the energy density, cycle life and dynamic performance of the cylindrical battery cell 7 can be effectively balanced.

[0264] As the compaction density of the negative electrode active material layer 132 increases, the thickness of the negative electrode active material layer 132 may decrease accordingly. In this case, the number of turns of the electrode assembly 10 increases, which may further aggravate the inner ring stress of the electrode assembly 10, increase the risk of the inner ring active material being crushed and damaged and the electrode sheet breaking, and may also affect the electrolyte wetting and reflux, which is not conducive to cycling. The embodiments of this application control the compaction density of the negative electrode active material layer 132 within the above-mentioned range, which is beneficial to reduce the inner ring stress of the wound electrode assembly 10 and improve the cycle life and dynamic performance of the cylindrical battery cell 7.

[0265] In some embodiments, the compaction density of the first membrane layer 1321 is greater than the compaction density of the second membrane layer 1322.

[0266] The difference in compaction density between the first film layer 1321 and the second film layer 1322 is beneficial for constructing more porous structures, increasing the wettability of the electrolyte to the second film layer 1322, improving the migration rate of active ions, reducing the risk of lithium plating, and improving the cycle life of the cylindrical battery cell 7.

[0267] For example, the compaction density of the second membrane layer 1322 is 0.6 g / cm³. 3 Up to 1.2 g / cm 3 For example, 0.6 g / cm 3 0.8 g / cm³, 0.9 g / cm³, 1.0 g / cm³, 1.1 g / cm³, 1.2 g / cm³, or any range of two of the above values.

[0268] When the compaction density of the second film layer 1322 is within the above range, the particles in the second film layer 1322 will not be too densely packed, which helps the rapid migration of active ions such as lithium ions, reduces the risk of lithium plating, and improves the cycle life of the cylindrical battery cell 7.

[0269] For example, the compaction density of the first film layer 1321 is 1.4 g / cm³. 3 Up to 1.8 g / cm 3 For example, 1.40 g / cm³, 1.60 g / cm³, 1.65 g / cm³, 1.70 g / cm³, 1.75 g / cm³, 1.80 g / cm³, or any range of two of the above values.

[0270] When the compaction density of the first film layer 1321 is within the above range, it is beneficial to increase the capacity of the first film layer 1321, thereby increasing the energy density of the cylindrical battery cell 7.

[0271] In some embodiments, based on the mass of the negative electrode active material layer 132, the silicon content is 0.5% to 5%, and the compaction density of the negative electrode active material layer 132 is 1.3 g / cm³. 3 Up to 1.65 g / cm 3 The combination of the aforementioned silicon content and the compaction density of the negative electrode active material layer 132 effectively improves the energy density, cycle life, and storage life of the cylindrical battery cell 7.

[0272] In some embodiments, based on the mass of the negative electrode active material layer 132, the silicon content is greater than 5% and less than or equal to 10%, and the compaction density of the negative electrode active material layer 132 is 1.2 g / cm³. 3 Up to 1.55 g / cm 3 The combination of the aforementioned silicon content and the compaction density of the negative electrode active material layer 132 effectively improves the energy density, cycle life, and storage life of the cylindrical battery cell 7.

[0273] In some embodiments, based on the mass of the negative electrode active material layer 132, the silicon content is greater than 10% and less than or equal to 20%, and the compaction density of the negative electrode active material layer 132 is 1 g / cm³. 3 Up to 1.45 g / cm 3 The combination of the aforementioned silicon content and the compaction density of the negative electrode active material layer 132 effectively improves the energy density, cycle life, and storage life of the cylindrical battery cell 7.

[0274] In some embodiments, the one-sided density of the negative electrode active material layer 132 is 85 mg / 1540.25 mm². 2 Up to 180mg / 1540.25mm 2 The option is 110mg / 1540.25mm. 2 Up to 180mg / 1540.25mm 2 The option is 125mg / 1540.25mm.2 Up to 145mg / 1540.25mm 2 For example, the unilateral surface density of the negative electrode active material layer 132 is 85 mg / 1540.25 mm², 90 mg / 1540.25 mm², 100 mg / 1540.25 mm², 110 mg / 1540.25 mm², 120 mg / 1540.25 mm², 125 mg / 1540.25 mm², 130 mg / 1540.25 mm², 135 mg / 1540.25 mm², 140 mg / mm², etc. 1540.25mm², 145mg / 1540.25mm², 150mg / 1540.25mm², 155mg / 1540.25mm², 160mg / 1540.25mm², 165mg / 1540.25mm², 170mg / 1540.25mm², 175mg / 1540.25mm², 180mg / 1540.25mm², or a range consisting of any two of the above values.

[0275] When the density of the negative electrode active material layer 132 on one side is within the above range, the negative electrode capacity will not be too low and the lithium ion transport path will not be too long, which can effectively balance the energy density, cycle performance and dynamic performance of the cylindrical battery cell 7.

[0276] As the density of one side of the negative electrode active material layer 132 decreases, the thickness of the negative electrode active material layer 132 may decrease accordingly. In this case, the number of turns of the electrode assembly 10 increases, which may further aggravate the inner ring stress of the electrode assembly 10, increase the risk of inner ring active material being crushed and damaged and electrode sheet breakage, and may also affect electrolyte wetting and reflux, which is not conducive to cycling. The embodiments of this application control the density of one side of the negative electrode active material layer 132 within the above-mentioned range, which is beneficial to reduce the inner ring stress of the wound electrode assembly 10 and improve the cycle life and dynamic performance of the cylindrical battery cell 7.

[0277] In this embodiment, the compaction density of the negative electrode active material layer can be the compaction density of the negative electrode active material layer of the battery cell at 0% state of charge (SOC). The unilateral density of the negative electrode active material layer can also be the unilateral density of the negative electrode active material layer of the battery cell at 0% SOC.

[0278] In this application, a cylindrical battery cell being in a fully discharged state means that, at 25°C, the cylindrical battery cell is discharged at a constant current rate of 0.33C to the lower cutoff voltage. At this point, the cylindrical battery cell is considered to be in a fully discharged state, i.e., 0% SOC. The lower cutoff voltage is known in the art, and the voltage recommended in the product specification sheet can be used. For example, the positive electrode active material includes lithium transition metal oxides, such as LiNi. 0.8 Co 0.1Mn 0.1 O2, LiNi 0.88 Co 0.1 Mn 0.02 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2, LiNi 0.92 Co 0.02 Mn 0.06 O2, LiNi 0.93 Co 0.06 Mn 0.01 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.88 Co 0.09 Al 0.03 O2, LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 One or more of O2, the negative electrode active material includes silicon-based materials and graphite materials, and the lower cutoff voltage can be 2.5V.

[0279] The compaction density and single-sided density of the negative electrode active material layer can be tested using the following method: Disassemble the negative electrode sheet from the battery cell at 0% state of charge (SOC). For example, take a single-sided coated negative electrode sheet (if it is a double-sided coated sheet, wipe off the negative electrode active material layer on one side first), cut it into a small circular piece with an area of ​​S1, weigh it, record its mass as M1, and measure its thickness H1. Then wipe off the negative electrode active material layer of the weighed negative electrode sheet, weigh the negative electrode current collector, record its mass as M0, and measure its thickness H0.

[0280] The density of the negative electrode active material layer on one side = (mass of the negative electrode sheet M1 - mass of the negative electrode current collector M0) / S1, the thickness of the negative electrode active material layer = thickness of the negative electrode sheet H1 - thickness of the negative electrode current collector H0, and the compaction density of the negative electrode active material layer = density of the negative electrode active material layer on one side / thickness of the negative electrode active material layer.

[0281] In the embodiments of this application, the thickness of the negative electrode sheet and the negative current collector has a meaning known in the art and can be detected using equipment and methods known in the art, such as using a micrometer to measure the thickness of the negative electrode sheet and the negative current collector.

[0282] [Positive electrode plate] In some embodiments, the lithium-containing transition metal oxide may have a layered structure.

[0283] In some embodiments, the lithium-containing transition metal oxide includes at least one of single-crystal particles and polycrystalline particles.

[0284] In some implementations, based on the total number of lithium transition metal oxide particles being 100%, the proportion of single crystal particles is 80% to 100%, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any range of two of the above values.

[0285] When the proportion of single crystal particles is less than 100%, lithium-containing transition metal oxides include single crystal particles and polycrystalline particles. When the proportion of single-crystal particles is 100%, lithium-containing transition metal oxides are single-crystal particles.

[0286] When the proportion of single-crystal particles is within the above range, the overall structural stability of lithium-containing transition metal oxides is improved, thereby increasing the cycle life under fast charging.

[0287] In the embodiments of this application, the terms "single crystal" and "polycrystalline" have meanings known in the art. Single crystal also includes lithium-containing transition metal oxides with a quasi-single crystal (also known as near-single crystal) morphology. Quasi-single crystal (near-single crystal) morphology of lithium-containing transition metal oxides has a meaning known in the art, generally referring to lithium-containing transition metal oxides composed of a small number, for example, less than 10 primary particles, with a small number of grain boundaries within the particles. Polycrystalline lithium transition metal oxides generally refer to lithium-containing transition metal oxides composed of a large number, for example, greater than or equal to 10 primary particles, forming secondary particles, with a large number of grain boundaries within the particles.

[0288] Based on the total number of lithium-containing transition metal oxides, the proportion of single-crystal lithium-containing transition metal oxides can be measured using ion-polished cross-sectional morphology analysis (CP) combined with scanning electron microscopy (SEM). SEM images of the cathode active material layer are obtained using CP combined with SEM. Multiple test areas (e.g., 5) are randomly selected, and at a certain magnification (e.g., 500x or higher), the number of single-crystal lithium-containing transition metal oxide particles and the number of polycrystalline lithium-containing transition metal oxide particles in each test area are counted. The proportion of single-crystal lithium-containing transition metal oxides is calculated as: (Number of single-crystal lithium-containing transition metal oxide particles / (Number of single-crystal lithium-containing transition metal oxide particles + Number of polycrystalline lithium-containing transition metal oxide particles). To ensure the accuracy of the test results, multiple test samples (e.g., 10) can be used, and the average value of each sample is taken as the final test result.

[0289] The lithium-containing transition metal oxide includes single-crystal particles, optionally with an average particle size of 1.5 μm to 7.5 μm.

[0290] The structure of single-crystal particles is relatively stable, which can reduce the risk of lithium-containing transition metal oxides cracking under pressure; However, when the volume average particle size of lithium-containing transition metal oxides is too small, the contact area with the electrolyte is large, the side reactions are more intense, the side reaction products increase, which is not conducive to cycle and kinetic performance. When the volume average particle size of lithium-containing transition metal oxides is too large, the solid-phase transport path of lithium ions in lithium-containing transition metal oxides is longer, the transport resistance increases, and the kinetic performance is poor. Moreover, when the particle size is too large, there is a risk of cracking under external forces, which reduces the cycle life.

[0291] Lithium-containing transition metal oxides, including single-crystal structures, when their volume-average particle size is within an appropriate range, can reduce the degree of side reactions on the particle surface and shorten the lithium-ion transport path, thereby improving the cycle performance and kinetic performance of battery cells.

[0292] In some embodiments, the average particle size of the lithium-containing transition metal oxide is from 1.5 μm to 7.5 μm, optionally from 3 μm to 5 μm. Exemplarily, the average particle size of the lithium-containing transition metal oxide is 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, or a range consisting of any two of the above values.

[0293] When the volume average particle size of lithium-containing transition metal oxides is within the above range, it can shorten the ion transport path and improve kinetic performance; moreover, the specific surface area is relatively small, the surface activity is not too high, which can reduce the side reaction rate and improve the cycle life and kinetic performance of cylindrical battery cells.

[0294] In this embodiment, the average particle size of the lithium transition metal oxide can be measured using ion polishing cross-sectional morphology analysis (CP) combined with scanning electron microscopy (SEM). SEM images of the positive electrode active material layer are obtained using CP combined with SEM. Multiple test areas (e.g., 5) are randomly selected, and at a certain magnification (e.g., 500x or higher), the number and particle size of lithium transition metal oxide particles in each test area are counted. The arithmetic mean of the particle sizes of all lithium transition metal oxide particles in each test area is taken as the average particle size. To ensure the accuracy of the test results, multiple test samples (e.g., 10) can be used for the above test, and the average value of each test sample is taken as the final test result. It should be noted that when the particles are irregularly shaped, the distance between the two farthest points on the particle is taken as the particle size.

[0295] In some embodiments, the lithium-containing transition metal oxide includes a non-lithium metal element, including nickel. In the embodiments of this application, the non-lithium metal element refers to any other metal element in the lithium-containing transition metal oxide that does not contain lithium.

[0296] Examples of lithium-containing transition metal oxides may include, but are not limited to, lithium-containing nickel-cobalt-manganese oxides. Optionally, lithium-containing transition metal oxides include at least one of lithium nickel-cobalt-manganese oxide, lithium nickel-cobalt-manganese aluminum oxide, and their respective modified compounds.

[0297] For example, lithium-containing transition metal oxides include lithium nickel cobalt manganese oxide, and non-lithium metal elements include nickel, cobalt, and manganese.

[0298] In some embodiments, the lithium-containing transition metal oxide includes a non-lithium metal element, including nickel, with a molar percentage of nickel ranging from 0.80 to 0.95 based on the total molar amount of the non-lithium metal element. Exemplarily, the molar percentage of nickel, based on the total molar amount of the non-lithium metal element, is 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, or a range of any two of the above values. Optionally, the molar percentage of nickel is 0.80 to 0.93.

[0299] When non-lithium metal elements include nickel, cobalt, and manganese, the molar percentage of nickel refers to the molar percentage of nickel relative to the total molar amount of nickel, cobalt, and manganese, with the total molar amount of nickel, cobalt, and manganese being 1.

[0300] When the molar percentage of nickel is within the above range, the specific capacity of the positive electrode active material is relatively high; when combined with an appropriate amount of silicon in the negative electrode, it can effectively improve the energy density of the battery cell. Moreover, the molar percentage of nickel will not be too high, which can reduce the risk of nickel and other metal elements dissolving and damaging the interface film on the negative electrode surface, and improve the cycle life of the battery cell.

[0301] In some embodiments, lithium-containing transition metal oxides include those with the general formula Li a Ni b Co c M d O e A f At least one of the compounds and their modified compounds, 0.8≤a≤1.2, 0.80≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

[0302] Optionally, 0.80≤b≤0.95, and further optionally, 0.80≤b≤0.93. The aforementioned lithium-containing transition metal oxide has a high specific capacity; when combined with an appropriate amount of silicon in the negative electrode, it can effectively improve the energy density of the battery cell; moreover, the molar proportion of nickel is not too high, which can reduce the risk of nickel and other metal elements dissolving and damaging the interface film on the negative electrode surface, thereby improving the cycle life of the battery cell.

[0303] In some embodiments, examples of lithium transition metal oxides may 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 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8Co 0.1 Mn 0.1 O2 (also known as NCM) 811 LiNi 0.9 Co 0.05 Mn 0.05 O2 (also known as Ni90), LiNi 0.92 Co 0.02 Mn 0.06 O2, LiNi 0.93 Co 0.06 Mn 0.01 O2, lithium nickel cobalt aluminum oxides (such as LiNi) 0.80 Co 0.15 Al 0.05 O2, LiNi 0.88 Co 0.09 Al 0.03 O2, LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 At least one of O2 and its modified compounds. Lithium nickel cobalt aluminum oxide includes aluminum, which makes the structure more stable, less prone to oxygen release, reduces side reactions, and improves cycle performance and storage performance.

[0304] In the embodiments of this application, the modified compounds of the above-mentioned positive electrode active materials can be doped and / or surface coated to modify the positive electrode active materials, such as carbon coating modification, fast ion conductor coating modification, etc.

[0305] During the charging and discharging process, the cylindrical battery cell 7 undergoes the insertion and extraction of active ions such as Li, resulting in a different molar content of Li in the cylindrical battery cell 7 at different discharge states. In the examples of positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery system, the molar content of Li may change after charge-discharge cycles.

[0306] In the embodiments of this application, the molar content of oxygen (O) in the positive electrode active materials is only a theoretical value. Oxygen release from the crystal lattice will cause the molar content of oxygen (O) to change. In reality, the molar content of oxygen (O) will fluctuate.

[0307] In this embodiment, the elemental content in the positive electrode active material is defined in a way known in the art and can be detected using equipment and methods known in the art. For example, referring to EPA 6010D-2014, it can be measured by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). First, 0.4 g of the positive electrode active material is weighed and 10 ml (50 wt%) of aqua regia is added. Then, it is placed on a plate at 180°C for 30 min. After digestion on the plate, the volume is adjusted to 100 mL, and quantitative testing is performed using the standard curve method.

[0308] For example, the molar percentage of nickel is 0.80 to 0.95, and the lithium-containing transition metal oxide is a single crystal particle.

[0309] The high molar proportion of nickel poses risks such as lithium-nickel mixing, resulting in poor structural stability. In contrast, lithium-containing transition metal oxides use single-crystal particles, which can compensate for the adverse effects of high nickel content, improve the overall structural stability of lithium-containing transition metal oxides, and enhance the cycle life of cylindrical battery cells.

[0310] In some embodiments, the compaction density of the positive electrode active material layer is 3.1 g / cm³. 3 Up to 3.6 g / cm 3 For example, 3.1 g / cm³, 3.2 g / cm³, 3.4 g / cm³, 3.5 g / cm³, 3.6 g / cm³, or any range of two of the above values. Optionally, the compaction density of the positive electrode active material layer is 3.3 g / cm³. 3 Up to 3.5g / cm 3 .

[0311] When the compaction density of the positive electrode active material layer is within the above range, a stable and appropriate bond can be formed between the positive electrode active material layer and the positive electrode current collector. During cycling, the positive electrode active material layer is not easy to peel off from the positive electrode current collector. Moreover, the particle packing is not too compact and dense, which can effectively reduce the risk of internal stress concentration. Furthermore, the positive electrode active material layer has an appropriate porous network structure, which is beneficial for the electrolyte to wet and reflux during the circulation process, and to fully wet the electrode assembly. When the compaction density of the positive electrode active material layer is within the above range, the compaction density of the positive electrode active material layer is controlled to an excellent window. While maximizing the energy density, the risk of performance degradation caused by stress accumulation is reduced, which can effectively balance the energy density, cycle life and dynamic performance of cylindrical battery cells.

[0312] As the compaction density of the positive electrode active material layer increases, the thickness of the positive electrode active material layer may decrease accordingly. In this case, the number of turns of the electrode assembly increases, which may further aggravate the inner ring stress of the electrode assembly, increase the risk of inner ring active material being crushed and damaged, and electrode breakage, and may also affect electrolyte wetting and reflux, which is detrimental to cycling and storage. The embodiments of this application control the compaction density of the positive electrode active material layer within the above-mentioned range, which is beneficial to reduce the inner ring stress of the wound electrode assembly and improve the cycle life and dynamic performance of the cylindrical battery cell.

[0313] In some embodiments, the unilateral surface density of the positive electrode active material layer is 155 mg / 1540.25 mm². 2 Up to 320mg / 1540.25mm 2 The option is 220mg / 1540.25mm. 2 Up to 280 mg / 1540.25 mm 2 . For example, the single-sided density of the positive electrode active material layer is 155 mg / 1540.25 mm², 160 mg / 1540.25 mm², 180 mg / 1540.25 mm², 200 mg / 1540.25 mm², 210 mg / 1540.25 mm², 220 mg / 1540.25 mm², 230 mg / 1540.25 mm², 240 mg / 1540.25 mm², 250 mg / 1540.25 mm², 260 mg / 1540.25 mm², 270 mg / 1540.25 mm², 280 mg / 1540.25 mm², 290 mg / 1540.25 mm², 300 mg / 1540.25 mm², 320 mg / 1540.25 mm², or a range of any two of the above values.

[0314] When the unilateral density of the positive electrode active material layer is within the above range, the positive electrode capacity will not be too low, and the lithium-ion transport path will not be too long, effectively balancing the energy density and kinetic performance of the cylindrical battery cell.

[0315] As the density of the positive electrode active material layer decreases on one side, the thickness of the positive electrode active material layer may decrease accordingly. In this case, the number of turns of the electrode assembly increases, which may further aggravate the inner ring stress of the electrode assembly, increase the risk of inner ring active material being crushed and damaged, and electrode breakage, and may also affect electrolyte wetting and reflux, which is detrimental to cycling and storage. The embodiments of this application control the density of the positive electrode active material layer on one side within the above-mentioned range, which is beneficial to reduce the inner ring stress of the wound electrode assembly and improve the cycle life and dynamic performance of the cylindrical battery cell.

[0316] In this embodiment, the compaction density of the positive electrode active material layer can be the compaction density of the positive electrode active material layer of the battery cell at 0% state of charge (SOC). The unilateral density of the positive electrode active material layer can also be the unilateral density of the positive electrode active material layer of the battery cell at 0% SOC.

[0317] The methods for detecting the compaction density and single-sided density of the positive electrode active material layer can refer to the methods for detecting the compaction density and single-sided density of the negative electrode active material layer, and will not be repeated here.

[0318] Example The following embodiments describe the contents disclosed in this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of the embodiments of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0319] Example 1 1. Preparation of positive electrode sheet The positive electrode includes a positive current collector and a positive active material layer disposed on both sides of the positive current collector. The positive current collector is aluminum foil.

[0320] The positive electrode active material layer comprises a film layer formed by uniformly coating a positive electrode slurry (solvent being N-methylpyrrolidone NMP) onto the surface of the positive electrode current collector, followed by drying and cold pressing. The positive electrode active material layer comprises positive electrode active material, polyvinylidene fluoride (PVDF), and conductive carbon Super P in a mass ratio of 98:1:1. Positive electrode active materials include LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 O2, which consists of single-crystal particles, has an average particle size of 4.5 μm as measured.

[0321] 2. Preparation of negative electrode sheet The negative electrode sheet includes a negative current collector and a negative active material layer disposed on both sides of the negative current collector. The negative current collector is a copper foil.

[0322] The negative electrode active material layer includes a first film layer and a second film layer, wherein the first film layer is located on the surface of the negative electrode current collector and the second film layer is located on the surface of the first film layer.

[0323] The first membrane layer comprises a membrane layer formed by uniformly coating a first slurry (solvent being water) onto the surface of the negative electrode current collector, followed by drying and cold pressing. The first membrane layer comprises artificial graphite, sodium carboxymethyl cellulose, styrene-butadiene rubber, and conductive carbon in a mass ratio of 96.5:1:1.5:1.

[0324] The second film layer comprises a film layer formed by uniformly coating a second slurry (with water as the solvent) onto the surface of the first film layer, followed by drying and cold pressing. The second film layer comprises a second active material, sodium carboxymethyl cellulose, styrene-butadiene rubber, and conductive carbon in a mass ratio of 80:3:15:2. The second active material comprises artificial graphite, natural graphite, and silicon-based material in a mass ratio of 30:20:50. The silicon-based material comprises a porous carbon structure and nano-silicon disposed within the porous carbon structure.

[0325] The thickness of the negative electrode active material layer is 60 μm.

[0326] In the first film layer of the negative electrode active material layer, the average particle size of artificial graphite is 14 μm.

[0327] In the second film layer of the negative electrode active material layer, the average particle size of graphite material (including artificial graphite and natural graphite) is 14 μm, the average particle size of silicon-based material is 8 μm, and the average particle size of graphite material and silicon-based material is 12 μm.

[0328] 3. Separating membrane The separator comprises a base film and coatings disposed on both sides of the base film. The base film is a porous polyethylene (PE) polymer film. The single-sided coating comprises a 1.5 μm thick boehmite layer on the surface of the porous PE polymer film, and a polyvinylidene fluoride (PVDF) layer on the surface of the boehmite layer. The single-sided coating amount of the PVDF layer is 0.095 mg / cm². 2 .

[0329] 4. Preparation of electrolyte The electrolyte consists of organic solvents, lithium salts, and additives.

[0330] The components of the organic solvent are mixed, and then lithium salt and additives are added to form an electrolyte.

[0331] The organic solvents include ethylene carbonate EC, diethyl carbonate DEC, and dimethyl carbonate DMC in a volume ratio of 1:1:1. Lithium salts include 1 mol / L lithium hexafluorophosphate.

[0332] The additives include 5% fluoroethylene carbonate (FEC), based on the total mass of the electrolyte.

[0333] 5. Preparation of cylindrical battery cells The positive electrode, separator, and negative electrode are wound sequentially, with the separator positioned between the positive and negative electrodes to provide isolation. This yields a wound electrode assembly. The electrode assembly is then placed in a housing, dried, and injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a cylindrical battery cell is obtained. Among them, the cylindrical battery cell at 0% SOC The compaction density of the negative electrode active material layer is 1.51 g / cm³. 3 ; The compaction density of the second membrane layer is 0.9 g / cm³. 3 ; The compaction density of the first membrane layer is 1.61 g / cm³. 3 ; The single-sided density of the negative electrode active material layer is 147 mg / 1540.25 mm. 2 ; The compaction density of the positive electrode active material layer is 3.52 g / cm³. 3 ; The single-sided density of the positive electrode active material layer is 252 mg / 1540.25 mm². 2 .

[0334] Performance testing 1. Cyclic battery cell cycle test Before the cycle performance test, the cylindrical battery cells were first charged at 25℃ with a constant current of 0.33C to 4.25V, and then charged at 4.25V with a constant voltage until the current was less than or equal to 0.05C. After resting for 10 minutes, the cylindrical battery cells were considered to be at 100% SOC. Then, the cylindrical battery cells were discharged at a constant current of 0.33C to 2.5V and rested for 10 minutes. After resting for 10 minutes, the cylindrical battery cells were considered to be at 0% SOC. Then, through voltage and capacity calibration, the voltages corresponding to 3% SOC, 10% SOC, 80% SOC, and 97% SOC were obtained.

[0335] Adjust the cylindrical battery cell to 3% SOC (e.g., charge it to 3% SOC with a constant current at a rate of 0.33C, or discharge it to 3% SOC), let it stand for 10 minutes, and then perform a cycle performance test.

[0336] The cycle performance test is as follows: At 35℃, the cylindrical battery cell is charged at a constant current rate of 0.33C from the voltage corresponding to 3% SOC to the voltage corresponding to 10% SOC, then charged at an equivalent 2.2C to the voltage corresponding to 80% SOC, and then charged at a constant current rate of 0.33C to the voltage corresponding to 97% SOC. After resting for 10 minutes, the cylindrical battery cell is discharged at a constant current rate of 1C to the voltage corresponding to 3% SOC, and then rested for 10 minutes. This constitutes one charge-discharge cycle, and the discharge capacity at this point is recorded as the discharge capacity of the first cycle. The above charge-discharge cycle steps are repeated, and the discharge capacity after each cycle is recorded until the capacity retention rate after the cycle is 80%. The test is then stopped, and the number of cycles is recorded. The capacity retention rate after N cycles = discharge capacity of N cycles / discharge capacity of the first cycle × 100%.

[0337] The more cycles a cylindrical battery cell has, the better its cycle performance.

[0338] 2. Cyclic DCR growth rate test of cylindrical battery cells Charge to 4.25V at 0.33C, then charge at 4.25V at a constant voltage until the current does not exceed 0.05C, let stand for 5 minutes, and then discharge to 2.5V at 0.33C. The capacity is recorded as C0. The cylindrical battery cell was placed in a constant temperature environment of 25℃ and charged at 0.33C between 2.5V and 4.25V to 4.25V. Then, it was charged at a constant voltage of 4.25V until the current was ≤0.05C. After standing for 30 minutes, the voltage U1 was recorded. Then, it was discharged at 1C for 30 seconds, and the voltage at 30 seconds was recorded as U2. The internal resistance R1 = (U1-U2) / 1C0. After testing the initial internal resistance R1 of the cylindrical battery cell, cycle it at 0.33C between 2.5V and 4.25V for 500cls, and then test the internal resistance R2 again. The cyclic DCR growth rate is calculated as (R2 - R1) / R1 × 100%.

[0339] 3. Energy density of cylindrical battery cells At room temperature, for example, 25 ℃, a cylindrical battery cell is discharged at a constant current of 0.33C to the discharge cutoff voltage, for example, 2.5V, and allowed to stand for 5 minutes. It is then charged at a constant current of 0.33C to the upper charging limit voltage of 4.25V, followed by constant voltage charging to a current of 0.05C, and allowed to stand for 5 minutes. Finally, it is discharged at a constant current of 0.33C to the discharge cutoff voltage, for example, 2.5V. The discharge capacity at this point is recorded, and the discharge energy E0 (Wh) is obtained. The volumetric energy density VED (Wh / L) = discharge energy E0 / volume of the cylindrical battery cell (L).

[0340] Comparative Example 1, Examples 1-1 to 1-3 Cylindrical battery cells were prepared using a method similar to that in Example 1, except that the mass content of silicon in the negative electrode active material layer was adjusted.

[0341] For example, in Comparative Example 1, the negative electrode active material in the second film layer includes artificial graphite and natural graphite in a mass ratio of 80:20.

[0342] Examples 1-4 Cylindrical battery cells were prepared using a method similar to that in Example 1. The difference from Example 1 was that the preparation steps of the negative electrode active material layer were adjusted. The negative electrode sheet includes a negative current collector and a negative active material layer disposed on both sides of the negative current collector. The negative current collector is a copper foil.

[0343] The negative electrode active material layer comprises a film formed by uniformly coating a second slurry (with water as the solvent) onto the surface of the negative electrode current collector, followed by drying and cold pressing. The negative electrode active material layer includes a second active material in a mass ratio of 80:3:15:2, sodium carboxymethyl cellulose, styrene-butadiene rubber, and conductive carbon. The second active material comprises artificial graphite, natural graphite, and silicon-based materials in a mass ratio of 30:20:50. The silicon-based material includes a porous carbon structure and nano-silicon disposed within the porous carbon structure.

[0344] The test results are shown in Table 1.

[0345] Table 1

[0346] VED represents the volumetric energy density of a cylindrical battery cell. In all embodiments and comparative examples, the ratio of negative electrode capacity to positive electrode capacity is essentially the same.

[0347] In Example 1, the outer diameter of the cylindrical battery cell casing is 46 mm. The outer diameter of the casing in other examples and comparative examples is the same as that in Example 1.

[0348] In Example 1, the mass content of graphite material in the negative electrode active material layer is about 91%, and the mass content of natural graphite in the negative electrode active material layer is about 2%.

[0349] When the mass content of silicon is too low, such as in Comparative Example 1-1, the volumetric energy density of a cylindrical battery cell is low.

[0350] In Examples 1 and 1-1 to 1-3, when the mass content of silicon is within an appropriate range, for example, the mass content of silicon in the negative electrode active material layer is greater than or equal to 0.5%, and can be selected from 0.5% to 20%, 0.5% to 17.5%, or 0.5% to 15%. As the mass content of silicon increases, the volumetric energy density of the cylindrical battery cell increases accordingly. For example, when the mass content of silicon is 15%, the volumetric energy density is 986 Wh / L; when the mass content of silicon is 17.5%, the volumetric energy density is 1024 Wh / L. However, as the mass content of silicon increases, the overall expansion of the negative electrode increases, which slightly reduces the cycle performance, resulting in a certain reduction in the number of cycles. In addition, the by-reaction products on the surface of the silicon-based material increase, increasing the impedance and leading to a decrease in kinetic performance.

[0351] The mass content of silicon in the negative electrode active material layer can be selected from 0.5% to 10%. When combined with graphite materials and single-crystal lithium-containing transition metal oxides with appropriate particle size range, it can effectively improve the energy density, kinetic performance and cycle performance under fast charging of cylindrical battery cells. For example, the volumetric energy density of cylindrical battery cells is 670-1025 Wh / L.

[0352] In Examples 1-4, the negative electrode active material layer adopts a single-layer film. Under certain conditions, the amount of silicon added in the single-layer film is relatively small, and the volume expansion of the negative electrode active material layer is relatively small, which is beneficial to improving both the dynamic performance of the cylindrical battery cell and the cycle performance under fast charging. Examples 2-1 and 2-2 Cylindrical battery cells were prepared using a method similar to that in Example 1. The difference from Example 1 was that the ratio of artificial graphite to natural graphite in the second film layer of the negative electrode active material layer was adjusted.

[0353] The test results are shown in Table 2.

[0354] Table 2

[0355] Examples 2-1 and 2-2 show that by controlling the mass content of natural graphite within an appropriate range, the combination of natural graphite and silicon-based materials can effectively reduce the expansion in the thickness direction of the electrode sheet, weaken the degree of interfacial side reactions, and simultaneously improve the energy density, kinetic performance, and cycle performance under fast charging of cylindrical battery cells.

[0356] Examples 3-1 and 3-2 Cylindrical battery cells were prepared using a method similar to that of Example 1, except that the average particle size of the silicon-based material was adjusted.

[0357] Example 3-3 Cylindrical battery cells were prepared using a method similar to that in Example 1, except that the silicon-based material was changed to a silicon oxide compound.

[0358] Examples 3-4 and 3-5 Cylindrical battery cells were prepared using a method similar to that in Example 1, except that the average particle size of the graphite material in the second film layer was adjusted.

[0359] The test results are shown in Table 3.

[0360] Table 3

[0361] The volumetric energy density of the cylindrical battery cells in Examples 3-1 to 3-5 is basically the same as that of the cylindrical battery cell in Example 1.

[0362] When the average particle size of the silicon-based material in Examples 3-1 and 3-2 is within the above range, the volume expansion of the silicon-based material will not be too high, and the active surface area of ​​the silicon-based material will not be too high. This prevents the side reaction between the silicon-based material and the electrolyte from becoming excessive, which helps to reduce side reaction products and thus helps to balance the kinetic performance of the cylindrical battery cell and the cycle performance under fast charging.

[0363] Various silicon-based materials are applicable to this application, such as the silicon-carbon material of Example 1 and the silicon oxide of Examples 3-3, which can effectively balance the dynamic performance of cylindrical battery cells and the cycle performance under fast charging.

[0364] When the average particle size of the graphite material in Examples 3-4 and 3-5 is within the above range, the combination of silicon-based material and graphite material can effectively reduce the expansion in the thickness direction of the electrode, weaken the degree of interfacial side reactions, and the active surface of the graphite material will not be too high, which can further reduce the generation of by-products, and can simultaneously improve the energy density, kinetic performance and cycle performance under fast charging of cylindrical battery cells.

[0365] Comparative Example 4-1, Comparative Example 4-2, Examples 4-1 to 4-3 Cylindrical battery cells were prepared using a method similar to that in Example 1, except that the average particle size of the positive electrode active material was adjusted.

[0366] Example 4-4 Cylindrical battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 was that the positive electrode active material was adjusted to include both single-crystal particles and polycrystalline particles.

[0367] The test results are shown in Table 4.

[0368] Table 4

[0369] In Table 4, the volumetric energy density of the cylindrical battery cells in each embodiment and comparative example is basically the same as that in Example 1.

[0370] When the volume average particle size of the positive electrode active material is too small, such as in Comparative Example 4-1, the surface activity of the positive electrode active material is high, the surface side reaction is strong, and the surface by-products increase, resulting in poor cycle performance and kinetic performance.

[0371] When the volume average particle size of the positive electrode active material is too large, such as in Comparative Example 4-2, the solid-phase transport path of the positive electrode active material is too long, resulting in an excessively high DCR growth rate, which reduces kinetic performance. Furthermore, the excessively large particle size poses a risk of cracking under external pressure, thereby reducing cycle performance.

[0372] In Examples 4-4, the positive electrode active material also includes a relatively large number of polycrystalline particles with larger particle sizes. The average particle size of the lithium transition metal oxide is about 7.2 μm. Although the initial kinetic performance of the polycrystalline particles is better, the structural stability of the polycrystalline particles is weaker than that of the single crystal particles. When the positive electrode active material layer is squeezed, its structural stability is slightly worse, and it is easy to crack, which reduces the interface stability, increases the side reaction rate, reduces the cycle performance, and increases the DCR growth rate, thus reducing the kinetic performance.

[0373] In Examples 4-1 to 4-3, when the volume average particle size of the positive electrode active material is within the above range, it can balance weak surface activity and short solid-phase transport path. Combined with the single crystal structure, it can effectively control the kinetic performance and cycle performance of the cylindrical battery cell under fast charging.

[0374] Examples 5-1 and 5-2 Battery cells were prepared using a method similar to that of Example 1, except that the material of the positive electrode active material was adjusted.

[0375] The test results are shown in Table 5.

[0376] Table 5

[0377] Various positive electrode active materials are applicable to this application. For example, with a higher molar proportion of nickel, combined with single crystal particles, the overall structural stability of lithium-containing transition metal oxides can be improved, which is beneficial to improving the cycle life of cylindrical battery cells.

[0378] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. A cylindrical battery cell, characterized in that, The device includes a housing and an electrode assembly disposed within the housing. The electrode assembly includes a positive electrode and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector. The negative electrode includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector. in, The outer diameter of the outer shell is greater than or equal to 28 mm; The negative electrode active material layer includes a negative electrode active material, which includes carbon-based materials and silicon-based materials. The carbon-based materials include graphite materials. Based on the mass of the negative electrode active material layer, the mass content of silicon in the negative electrode active material layer is greater than or equal to 0.5%. The positive electrode active material layer includes a lithium-containing transition metal oxide, which includes single-crystal particles. Based on the total number of lithium-containing transition metal oxide particles being 100%, the number of single-crystal particles accounts for 80% to 100%, and the average particle size of the lithium-containing transition metal oxide is 1.5 μm to 7.5 μm.

2. The cylindrical battery cell according to claim 1, characterized in that, Based on the mass of the negative electrode active material layer, the mass content of silicon element is 0.5% to 20%.

3. The cylindrical battery cell according to claim 1, characterized in that, Based on the mass of the negative electrode active material layer, the mass content of the graphite material is 55% to 96%.

4. The cylindrical battery cell according to claim 1, characterized in that, The graphite material includes one or more of natural graphite and artificial graphite.

5. The cylindrical battery cell according to claim 4, characterized in that, Based on the mass of the negative electrode active material layer, the mass content of the natural graphite is 1% to 40%.

6. The cylindrical battery cell according to claim 1, characterized in that, The average particle size of the lithium-containing transition metal oxide is 3 μm to 5 μm.

7. The cylindrical battery cell according to claim 1, characterized in that, Based on the mass of the negative electrode active material layer, the mass content of the silicon-based material is 1% to 40%.

8. The cylindrical battery cell according to claim 1, characterized in that, The silicon-based materials include one or more of silicon-carbon materials, elemental silicon, silicon oxides, silicon-nitrogen composites, and silicon alloys.

9. The cylindrical battery cell according to claim 1, characterized in that, The silicon-based materials include silicon-carbon materials.

10. The cylindrical battery cell according to claim 1, characterized in that, The average particle size of the silicon-based material is 1 μm to 12 μm.

11. The cylindrical battery cell according to claim 1, characterized in that, The carbon-based materials also include one or more of hard carbon and soft carbon.

12. The cylindrical battery cell according to claim 1, characterized in that, The average particle size of the carbon-based material is 10 μm to 18 μm.

13. The cylindrical battery cell according to claim 1, characterized in that, The average particle size of the negative electrode active material is 5 μm to 18 μm.

14. The cylindrical battery cell according to claim 1, characterized in that, The negative electrode active material layer is a single-layer film.

15. The cylindrical battery cell according to claim 1, characterized in that, The negative electrode active material layer includes a first film layer and a second film layer stacked together. The first film layer is located between the negative electrode current collector and the second film layer. The second film layer includes the silicon-based material. The first film layer and the second film layer each independently include the graphite material.

16. The cylindrical battery cell according to claim 15, characterized in that, The thickness ratio of the second film layer to the first film layer is 0.125 to 1.

17. The cylindrical battery cell according to claim 15, characterized in that, The thickness of the first film layer is 40 μm to 55 μm; and / or The thickness of the second film layer is 5 μm to 20 μm; and / or The thickness of the negative electrode active material layer is 45 μm to 75 μm.

18. The cylindrical battery cell according to claim 15, characterized in that, The compaction density of the first membrane layer is greater than that of the second membrane layer.

19. The cylindrical battery cell according to claim 1, characterized in that, The compaction density of the negative electrode active material layer is 1 g / cm³. 3 Up to 1.65 g / cm 3 .

20. The cylindrical battery cell according to claim 1, characterized in that, Based on the mass of the negative electrode active material layer, the silicon content is 0.5% to 5% by mass, and the compaction density of the negative electrode active material layer is 1.3 g / cm³. 3 Up to 1.65 g / cm 3 ;or Based on the mass of the negative electrode active material layer, the silicon content is greater than 5% and less than or equal to 10%, and the compaction density of the negative electrode active material layer is 1.2 g / cm³. 3 Up to 1.55 g / cm 3 ;or Based on the mass of the negative electrode active material layer, the silicon content is greater than 10% and less than or equal to 20%, and the compaction density of the negative electrode active material layer is 1 g / cm³. 3 Up to 1.45 g / cm 3 .

21. The cylindrical battery cell according to claim 1, characterized in that, The single-sided density of the negative electrode active material layer is 85 mg / 1540.25 mm². 2 Up to 180 mg / 1540.25 mm 2 .

22. The cylindrical battery cell according to claim 21, characterized in that, The single-sided density of the negative electrode active material layer is 100 mg / 1540.25 mm². 2 Up to 180 mg / 1540.25 mm 2 .

23. The cylindrical battery cell according to claim 1, characterized in that, The lithium-containing transition metal oxide includes non-lithium metal elements, including nickel, with a molar percentage of nickel ranging from 0.80 to 0.95, based on the total molar amount of the non-lithium metal elements.

24. The cylindrical battery cell according to claim 23, characterized in that, The molar percentage of nickel is 0.80 to 0.93, based on the total molar amount of the non-lithium metal elements.

25. The cylindrical battery cell according to claim 1, characterized in that, Lithium-containing transition metal oxides include those with the general formula Li a Ni b Co c M d O e A f At least one of the compounds and their modified compounds, 0.8≤a≤1.2, 0.80≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

26. The cylindrical battery cell according to claim 1, characterized in that, The compaction density of the positive electrode active material layer is 3.1 g / cm³. 3 Up to 3.6 g / cm 3 .

27. The cylindrical battery cell according to claim 1, characterized in that, The compaction density of the positive electrode active material layer is 3.3 g / cm³. 3 Up to 3.5g / cm 3 .

28. The cylindrical battery cell according to claim 1, characterized in that, The single-sided density of the positive electrode active material layer is 155 mg / 1540.25 mm². 2 Up to 320mg / 1540.25mm 2 .

29. The cylindrical battery cell according to claim 1, characterized in that, The single-sided density of the positive electrode active material layer is 220 mg / 1540.25 mm². 2 Up to 280mg / 1540.25mm 2 .

30. The cylindrical battery cell according to claim 1, characterized in that, The electrode assembly has a wound structure.

31. The cylindrical battery cell according to claim 1, characterized in that, The outer diameter of the outer casing is 28mm to 80mm.

32. A battery device, characterized in that, It includes multiple cylindrical battery cells as described in any one of claims 1 to 31.

33. An electrical device, characterized in that, Includes the battery device as described in claim 32.

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