Battery cell, battery, and electric apparatus

Abstract

A battery cell, a battery, and an electric apparatus. The battery cell comprises an electrode assembly and an outer package, wherein the electrode assembly comprises a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, and the positive electrode active material comprising a layered lithium-containing transition metal oxide having a single crystal morphology; the length of the battery cell is denoted as a and the width of the battery cell is denoted as b, a being greater than or equal to 180 mm, and a / b being 2.0-10.5. The battery thus has both high energy density and long cycle life.

Description

Battery cells, batteries and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202310936624.3, filed on July 28, 2023, entitled “Battery Cell, Battery and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to a battery cell, a battery and an electrical device. Background Art

[0004] In recent years, batteries have been widely used in energy storage systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As battery applications expand, the demand for battery use is also increasing. However, achieving high energy density while balancing other electrochemical properties remains a challenge in battery development.

[0005] Summary of the Invention

[0006] The present application provides a battery cell, a battery and an electrical device, which can enable the battery to have both high energy density and long cycle life.

[0007] A first aspect of the present application provides a battery cell, which includes an electrode assembly and an outer package.

[0008] The electrode assembly includes a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a layered lithium-containing transition metal oxide with a single crystal morphology.

[0009] The battery cell has a length direction, a width direction and a thickness direction, and the thickness direction of the battery cell is the thickness direction of the positive electrode sheet.

[0010] The length of the battery cell is recorded as a, the width of the battery cell is recorded as b, a is greater than or equal to 180 mm, and a / b is 2.0-10.5.

[0011] By making the positive electrode active material include a layered lithium-containing transition metal oxide with a single crystal morphology, and making the length a of the battery cell using it greater than or equal to 180 mm, and the ratio a / b of the length a of the battery cell to the width b of the battery cell being 2.0-10.5, the battery can have both high energy density and long cycle life.

[0012] In any embodiment, a is 190 mm-1200 mm, optionally 250 mm-1200 mm.

[0013] In any embodiment, a is 350 mm to 1200 mm; and / or a / b is 3.1 to 10.5.

[0014] In any embodiment, a is 250 mm to 800 mm; and / or a / b is 2.5 to 8.0.

[0015] In any embodiment, a is 350 mm-800 mm, optionally 420 mm-800 mm; and / or a / b is 3.1-8.0, optionally 3.3-8.0.

[0016] When the length a of the battery cell is within the given range, the electrode sheet can have a larger effective size while ensuring normal welding of the electrode lug. This improves the cell group margin and the mass ratio of the positive and negative active materials in the entire cell, thereby enabling the battery to have a high energy density. When the length a of the battery cell is within the given range, the electrolyte wettability of the entire electrode assembly, including the central region, can be further improved, allowing the electrolyte to easily penetrate and reflux throughout the electrode sheet, thereby facilitating lithium ion transport and extending the battery cycle life.

[0017] When the ratio a / b of the length a of the battery cell to the width b of the battery cell is within a given range, the cycle performance of the battery can be further improved, and the battery can also have a high energy density.

[0018] In any embodiment, b is 30 mm to 140 mm, and can be optionally 60 mm to 125 mm. When the width b of the battery cell is within the given range, the cycle performance of the battery can be further improved, and the battery is also conducive to having a high energy density.

[0019] In any embodiment, the thickness of the battery cell is denoted as c, where c is less than or equal to 70 mm and can be optionally 10 mm to 60 mm.

[0020] In any embodiment, the outer packaging is made of soft packaging material or hard shell material.

[0021] In any embodiment, the electrode assembly is a laminated structure or a wound structure, and a laminated structure is optional. When the electrode assembly is a laminated structure, the battery cells can have a higher group margin, thereby further improving the energy density of the battery.

[0022] In any embodiment, the electrode assembly includes a main body and a tab extending from the main body. The tab, after being bent, has a dimension in the direction of extension of the main body of less than or equal to 20 mm, and optionally less than or equal to 15 mm. This allows the electrode sheet to have a larger effective size, thereby improving the group margin of the battery cell and increasing the mass ratio of the positive and negative active materials in the entire battery cell, thereby further achieving a high energy density of the battery.

[0023] In any embodiment, the electrode tabs include a positive electrode tab and a negative electrode tab, and the positive electrode tab and the negative electrode tab extend from opposite ends of the main body of the electrode assembly. This allows the positive electrode tab and the negative electrode tab to be wider, thereby improving the electronic conductivity of the electrode sheet.

[0024] In any embodiment, the positive electrode active material includes both a layered lithium-containing transition metal oxide with a single crystal morphology and a layered lithium-containing transition metal oxide with a polycrystalline morphology; optionally, in the positive electrode active material, the proportion of the layered lithium-containing transition metal oxide with a single crystal morphology is denoted as S1, and the proportion of the layered lithium-containing transition metal oxide with a polycrystalline morphology is denoted as S2, S1>S2.

[0025] In any embodiment, in the positive electrode active material, the proportion of the layered lithium-containing transition metal oxide with a single crystal morphology is recorded as S1, and S1 is greater than or equal to 70%, and can be optionally 80%-99%.

[0026] By making the positive electrode active material mainly include layered lithium-containing transition metal oxides with a single crystal morphology, the battery can have high energy density, long cycle life and good power performance.

[0027] In any embodiment, the volume distribution particle size Dv50 of the positive electrode active material is less than or equal to 8 μm, and can be optionally 2 μm-5.5 μm.

[0028] In any embodiment, the volume distribution particle size Dv90 of the positive electrode active material is less than or equal to 18 μm, and can be optionally 3 μm-12 μm.

[0029] By adjusting the volume distribution particle size Dv50 and / or Dv90 of the positive electrode active material within the above range, the battery side reactions can be reduced, the battery capacity attenuation rate can be lowered, the battery has a long cycle life, and the battery can also have good power performance.

[0030] In any embodiment, the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a carbon material; optionally, the carbon material includes one or more of artificial graphite and natural graphite.

[0031] In any embodiment, the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.

[0032] Optionally, the silicon-based material includes silicon and one or more of alkali metal elements and alkaline earth metal elements.

[0033] Optionally, the mass proportion of the silicon-based material in the negative electrode active material is greater than or equal to 5%, and more optionally 8%-20%.

[0034] In any embodiment, the volume distribution particle size Dv10 of the negative electrode active material is 4 μm-8 μm, and optionally 4.5 μm-6.5 μm.

[0035] In any embodiment, the volume distribution particle size Dv50 of the negative electrode active material is 6 μm-15 μm, and can be optionally 8 μm-13 μm.

[0036] In any embodiment, the volume distribution particle size Dv90 of the negative electrode active material is 15 μm-30 μm, and can be optionally 18 μm-25 μm.

[0037] In any embodiment, the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer includes a negative electrode active material, the negative electrode film layer has a first surface away from the negative electrode current collector and a second surface arranged opposite to the first surface, the thickness of the negative electrode film layer is recorded as H, the area within the thickness range from the first surface of the negative electrode film layer to 0.3H is recorded as the first area of ​​the negative electrode film layer, and the area within the thickness range from the second surface of the negative electrode film layer to 0.3H is recorded as the second area of ​​the negative electrode film layer, the first area includes a first negative electrode active material, the second area includes a second negative electrode active material, the first negative electrode active material includes a first carbon material, the second negative electrode active material includes a second carbon material, and the volume distribution particle size Dv50 of the first carbon material is smaller than the volume distribution particle size Dv50 of the second carbon material.

[0038] By adjusting the structure of the negative electrode film layer on one side of the negative current collector and performing differentiated coating, the battery can achieve excellent power performance. By placing the first carbon material in direct contact with the electrolyte and ensuring that the volume distribution particle size (Dv50) of the first carbon material is smaller than that of the second carbon material, the first region of the negative electrode film layer has more ion embedding channels, facilitating rapid ion migration to the second carbon material. This allows the battery to achieve both high energy density and long cycle life while maintaining excellent power performance.

[0039] In any embodiment, the specific surface area of ​​the first carbon material is smaller than the specific surface area of ​​the second carbon material. The first carbon material is in direct contact with the electrolyte. By making the specific surface area of ​​the first carbon material smaller than the specific surface area of ​​the second carbon material, it is beneficial to reduce battery side reactions, thereby facilitating better cycle performance of the battery.

[0040] In any embodiment, the degree of graphitization of the first carbon material is lower than that of the second carbon material. The lower degree of graphitization of the first carbon material results in a larger interlayer spacing, which facilitates rapid ion intercalation and deintercalation. Therefore, by adjusting the degree of graphitization of the first carbon material to be lower than that of the second carbon material, the power performance of the battery is improved.

[0041] In any embodiment, the first carbon material includes artificial graphite.

[0042] In any embodiment, the second carbon material includes natural graphite.

[0043] In any embodiment, the first negative electrode active material and / or the second negative electrode active material further comprises a silicon-based material. Optionally, the first negative electrode active material and the second negative electrode active material further comprise a silicon-based material.

[0044] A second aspect of the present application provides a battery, which includes the battery cell of the first aspect of the present application.

[0045] A third aspect of the present application provides an electrical device comprising the battery according to the second aspect of the present application.

[0046] The electric device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0048] FIG1 is a schematic structural diagram of a battery cell provided in some embodiments of the present application.

[0049] FIG. 2 is a schematic structural diagram of an electrode assembly of the battery cell shown in FIG. 1 .

[0050] FIG3 is an exploded schematic diagram of the outer package of the battery cell shown in FIG1 .

[0051] FIG4 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application.

[0052] FIG5 is a schematic structural diagram of an electrode assembly of the battery cell shown in FIG4 .

[0053] FIG. 6 is an exploded schematic diagram of the outer package of the battery cell shown in FIG. 4 .

[0054] FIG7 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application.

[0055] FIG8 is a schematic structural diagram of an electrode assembly of the battery cell shown in FIG7 .

[0056] FIG. 9 is another schematic structural diagram of the electrode assembly of the battery cell shown in FIG. 7 .

[0057] FIG10 is an exploded schematic diagram of the outer package of the battery cell shown in FIG7 .

[0058] FIG11 is a schematic structural diagram of a negative electrode plate provided in some embodiments of the present application.

[0059] FIG12 is a schematic structural diagram of the negative electrode sheet provided in other embodiments of the present application.

[0060] FIG13 is a schematic structural diagram of the negative electrode sheet provided in some other embodiments of the present application.

[0061] FIG14 is a schematic diagram of an electrical device provided in some embodiments of the present application.

[0062] In the accompanying drawings, which are not necessarily drawn to scale, the following reference numerals are used: 5, battery cell; 51, housing; 52, electrode assembly; 521, main body; 522, tab; 53, end cap assembly; 531, electrode terminal; 10, negative electrode tab; 101, negative electrode current collector; 102, negative electrode film; 1021, first region; 1022, second region; 1023, intermediate region; 102a, first surface; 102b, second surface; X, length direction; Y, width direction; Z, thickness direction. DETAILED DESCRIPTION

[0063] Below, the embodiments of the battery cell, battery, and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0064] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0065] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0066] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0067] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0068] Unless otherwise specified, in this application, the terms "first", "second", etc. are used to distinguish different objects rather than to describe a specific order or a primary-secondary relationship.

[0069] In this application, the terms "plurality" and "multiple" refer to two or more.

[0070] In the description of the embodiments of the present application, unless otherwise specified, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0071] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0072] Unless otherwise stated, the numerical values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0073] The Dv10, Dv50, and Dv90 values ​​of materials (e.g., positive electrode active materials, negative electrode active materials, etc.) are well-known in the art and can be measured using instruments and methods known in the art. For example, they can be conveniently measured using a laser particle size analyzer (e.g., the Malvern Mastersizer 3000) in accordance with GB / T 19077-2016. The physical definition of Dv90 is the particle size at which the cumulative volume distribution percentage of a material reaches 90%; the physical definition of Dv50 is the particle size at which the cumulative volume distribution percentage of a material reaches 50%; and the physical definition of Dv10 is the particle size at which the cumulative volume distribution percentage of a material reaches 10%.

[0074] The specific surface area of ​​a material (e.g., a positive electrode active material, a negative electrode active material, etc.) is well known in the art and can be measured using instruments and methods known in the art. For example, it can be measured using the nitrogen adsorption specific surface area analysis method in accordance with GB / T 19587-2017 and calculated using the BET (Brunauer Emmett Teller) method. The test instrument can be a Micromeritics Tri-Star 3020 Specific Surface Area Pore Size Analyzer.

[0075] The percentage of layered lithium-containing transition metal oxides with a single crystal (or polycrystalline) morphology in the positive electrode active material is well known in the art and can be measured using instruments and methods known in the art. For example, the positive electrode active material can be laid and adhered to a conductive adhesive to form a test sample with a length × width of 6 cm × 1.1 cm; the particle morphology can be tested using a scanning electron microscope and an energy dispersive spectrometer (such as a ZEISS Sigma300). The test can refer to JY / T010-1996. To ensure the accuracy of the test results, 20 different areas can be randomly selected from the test sample for scanning testing, and at a certain magnification (for example, 1000 times or more), the ratio of the number of layered lithium-containing transition metal oxides with a single crystal (or polycrystalline) morphology to the total number of particles in each area is calculated, which is the percentage of layered lithium-containing transition metal oxides with a single crystal (or polycrystalline) morphology in the area; the average of the test results of the 20 test areas is taken as the percentage of layered lithium-containing transition metal oxides with a single crystal (or polycrystalline) morphology in the positive electrode active material.

[0076] In this application, the term "single crystal" also includes quasi-single crystals (also known as single-crystal-like particles), which generally refer to particles formed by the aggregation of a small number of primary particles (e.g., no more than 10). Polycrystalline particles refer to secondary particles formed by the aggregation of multiple primary particles.

[0077] It should be noted that, for various parameter tests of the positive (or negative) active materials in the embodiments of the present application, samples can be taken from the cold-pressed positive (or negative) film layer. As an example of taking the negative active material from the cold-pressed negative film layer, the cold-pressed negative electrode sheet can be placed in deionized water, and the negative active material will fall off naturally. The negative active material is filtered and dried, and then the dried negative active material is sintered at 400°C for 2h to remove the binder and conductive agent to obtain the negative active material.

[0078] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery cell, a battery module or a battery pack, etc. A battery cell is the smallest unit that makes up a battery, which can independently realize the function of charging and discharging. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in mixed connection through a busbar. In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a case and battery cells, and the battery cells or battery modules are housed in the case. In some embodiments, the case may serve as part of the chassis structure of the vehicle. For example, part of the case may become at least part of the floor of the vehicle, or part of the case may become at least part of the crossbeam and longitudinal beam of the vehicle.

[0079] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0080] The battery cells mentioned in the embodiments of the present application may include lithium-ion battery cells.

[0081] The battery cell provided in the embodiment of the present application includes an electrode assembly and an outer packaging.

[0082] The battery cell has a length direction X, a width direction Y, and a thickness direction Z.

[0083] The thickness direction Z of the battery cell is the thickness direction of the positive electrode sheet.

[0084] The electrode assembly can be a laminated structure or a wound structure. When the electrode assembly is a laminated structure, the battery cell includes multiple positive electrode sheets, and the thickness direction Z of the battery cell is the thickness direction of the positive electrode sheets, that is, the stacking direction of the multiple positive electrode sheets. When the electrode assembly is a wound structure, the electrode assembly includes a straight area and a bent area, and the positive electrode sheets include multiple straight segments located in the straight area and multiple bent segments located in the bent area. The thickness direction Z of the battery cell refers to the thickness direction of the straight segment positive electrode sheets located in the straight area, that is, the stacking direction of the multiple straight segment positive electrode sheets.

[0085] The electrode assembly includes a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a layered lithium-containing transition metal oxide with a single crystal morphology.

[0086] The length of the battery cell is recorded as a, the width of the battery cell is recorded as b, a is greater than or equal to 180 mm, and a / b is 2.0-10.5.

[0087] The positive electrode active material of the battery cell provided in the embodiment of the present application includes a layered lithium-containing transition metal oxide with a single crystal morphology. The layered lithium-containing transition metal oxide with a single crystal morphology generally has a small specific surface area and good interface stability and thermal stability, thereby reducing battery side reactions; it can also maintain good particle integrity during long-term charge and discharge, thereby reducing the battery capacity decay rate. Therefore, when the positive electrode active material includes a layered lithium-containing transition metal oxide with a single crystal morphology, the battery can have a long cycle life. However, the compaction density of the layered lithium-containing transition metal oxide with a single crystal morphology is relatively low, which results in a low energy density of the battery, making it difficult to meet the use requirements of long cycle life and high energy density batteries.

[0088] The energy density of a battery can be increased by increasing the length a of the battery cell. However, increasing the length a of the battery cell deteriorates the electrolyte wettability of the electrode assembly, especially in the later stages of the cycle, which can affect the battery's cycling performance.

[0089] By making the length a of the battery cell greater than or equal to 180 mm and the ratio a / b of the length a of the battery cell to the width b of the battery cell being 2.0-10.5, the battery can have both high energy density and long cycle life.

[0090] When the positive electrode active material is a layered lithium-containing transition metal oxide with a polycrystalline morphology, during the long-term charge and discharge process of the battery, the structural instability of the layered lithium-containing transition metal oxide with a polycrystalline morphology caused by the anisotropic lattice contraction will produce local stress concentration along the particle boundaries and develop into microcracks, making it easy for the electrolyte to penetrate and corrode the interior of the polycrystalline particles (secondary particles), thereby generating more battery side reactions and making it difficult to meet the use requirements of long cycle life batteries.

[0091] When the positive electrode active material includes a layered lithium-containing transition metal oxide with a single crystal morphology, but the length a of the battery cell is less than 180 mm, since the compaction density of the layered lithium-containing transition metal oxide with a single crystal morphology is relatively small, if the length a of the battery cell is too small, the size design of the battery cell is not sufficient to compensate for the reduction in battery energy density caused by the layered lithium-containing transition metal oxide with a single crystal morphology, and thus it is difficult to meet the use requirements of high-energy-density batteries.

[0092] When the positive electrode active material includes a layered lithium-containing transition metal oxide with a single crystal morphology, if the ratio a / b of the length a of the battery cell to the width b of the battery cell is less than 2, the length a of the battery cell is too small and / or the width b of the battery cell is too large. When the length a of the battery cell is too small, the size design of the battery cell is not enough to compensate for the reduction in battery energy density caused by the layered lithium-containing transition metal oxide with a single crystal morphology, and thus it is difficult to meet the use requirements of high energy density batteries. When the width b of the battery cell is too large, it will affect the infiltration of the electrolyte, especially for the negative electrode sheet, and the probability of lithium plating will increase. Therefore, when the ratio a / b of the length a of the battery cell to the width b of the battery cell is less than 2, it is also difficult to meet the use requirements of long cycle life and high energy density batteries. When the positive electrode active material includes a layered lithium-containing transition metal oxide with a single crystal morphology, if the ratio a / b of the length a of the battery cell to the width b of the battery cell is greater than 10.5, the length a of the battery cell is too large, the electrolyte is greatly affected by its own gravity, and the electrolyte wettability of the electrode assembly is poor, thereby reducing the cycle performance of the battery, and it is difficult to meet the use requirements of long cycle life and high energy density batteries.

[0093] The length a of the battery cell is greater than or equal to 180 mm, for example, it can be 180 mm, 190 mm, 220 mm, 250 mm, 300 mm, 350 mm, 420 mm, 530 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm, 1200 mm, or a range thereof.

[0094] In some embodiments, the length a of the battery cell may be greater than or equal to 190 mm, and may be optionally 190 mm-1200 mm, 190 mm-1000 mm, 190 mm-800 mm, 190 mm-600 mm, 190 mm-420 mm, 220 mm-1200 mm, 220 mm-1000 mm, 220 mm-800 mm, 220 mm-600 mm, 220 mm-420 mm, 250 mm-1200 mm, 250 mm-1000 mm, 250 mm-800 mm, 300 mm-1200 mm, 300 mm-800 mm, 350 mm-1200 mm, 350 mm-800 mm, 420 mm-1200 mm, 420 mm-800 mm.

[0095] When the length a of the battery cell is within the given range, the electrode sheet can have a larger effective size while ensuring normal welding of the electrode lug. This improves the cell group margin and the mass ratio of the positive and negative active materials in the entire cell, thereby enabling the battery to have a high energy density. When the length a of the battery cell is within the given range, the electrolyte wettability of the entire electrode assembly, including the central region, can be further improved, allowing the electrolyte to easily penetrate and reflux throughout the electrode sheet, thereby facilitating lithium ion transport and extending the battery cycle life.

[0096] The ratio a / b of the length a of the battery cell to the width b of the battery cell is greater than or equal to 2.0. For example, it can be 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 3.0, 3.1, 3.3, 3.5, 4.0, 4.2, 4.4, 5.0, 5.6, 6.0, 7.0, 8.0, 8.3, 9.0, 10.0, 10.5, 12.0, 15.0, or a range consisting of any of the above values.

[0097] In some embodiments, the ratio a / b of the length a of the battery cell to the width b of the battery cell may be 2.0-12.0, 2.5-12.0, 2.8-12.0, 3.1-12.0, 3.3-12.0, 2.0-10.5, 2.5-10.5, 2.8-10.5, 3.0-10.5, 3.1-10.5, 3.3-10.5, 2.0-8 .0, 2.5-8.0, 2.8-8.0, 3.0-8.0, 3.1-8.0, 3.3-8.0, 2.0-5.6, 2.5-5.6, 2.8-5.6, 3.0-5.6, 3.1-5.6, 3.3-5.6, 2.0-4.4, 2.5-4.4, 2.8-4.4, 3.0-4.4, 3.1-4.4, 3.3-4.4.

[0098] When the ratio (a / b) of the battery cell length a to the battery cell width b is within the given range, the effect of gravity on the electrolyte can be reduced, thereby facilitating electrolyte infiltration into the electrode assembly. Furthermore, this can ensure more balanced expansion and contraction of the electrode sheet in both the lateral and longitudinal directions, thereby stabilizing the electrode sheet interface. Therefore, when the ratio (a / b) of the battery cell length a to the battery cell width b is within the given range, the battery's cycling performance can be further improved.

[0099] In addition, the size design of the battery cell will affect the capacity of the battery cell. When the ratio a / b of the length a of the battery cell to the width b of the battery cell is within a given range, the battery can also have a high energy density.

[0100] In some embodiments, the width b of the battery cell may be less than or equal to 140 mm, and may optionally be less than or equal to 125 mm.

[0101] In some embodiments, the width b of the battery cell can be 30mm-140mm, 30mm-125mm, 30mm-110mm, 30mm-100mm, 45mm-140mm, 45mm-125mm, 45mm-110mm, 45mm-100mm, 60mm-140mm, 60mm-125mm, 60mm-110mm, 60mm-100mm, 80mm-140mm, 80mm-125mm, 80mm-110mm, 80mm-100mm.

[0102] When the width b of a battery cell is within the given range, it facilitates uniform electrolyte infiltration and reflow within the electrode sheet, reducing the probability of ion reduction and precipitation problems in the central region of the electrode sheet due to electrolyte infiltration and reflow difficulties. It also reduces the problem of interface wrinkling caused by the continuous contraction and expansion of the electrode sheet (especially the negative electrode sheet) during the charge and discharge process. It also balances the current density on the electrode sheet surface, especially reducing the probability of lithium deposition at the negative electrode. Therefore, when the width b of a battery cell is within the given range, the cycle performance of the battery can be further improved.

[0103] When the width b of the battery cell is within the given range, it is also beneficial for the battery to have a high energy density.

[0104] In some embodiments, the thickness c of the battery cell may be less than or equal to 70 mm, and may be 10 mm-60 mm, 15 mm-60 mm, 20 mm-60 mm, 10 mm-50 mm, 15 mm-50 mm, 20 mm-50 mm, 10 mm-40 mm, 15 mm-40 mm, or 20 mm-40 mm.

[0105] In some embodiments, the length a of the battery cell is 350 mm-1200 mm; and / or a / b is 3.1-10.5.

[0106] In some embodiments, the length a of the battery cell is 250 mm-800 mm; and / or a / b is 2.5-8.0.

[0107] In some embodiments, the length a of the battery cell is 350 mm-800 mm, optionally 420 mm-800 mm; and / or a / b is 3.1-8.0, optionally 3.3-8.0.

[0108] In some embodiments, the length a of the battery cell is 190 mm-1200 mm, the width b of the battery cell is 30 mm-140 mm, the thickness c of the battery cell is 10 mm-60 mm, and a / b is 2.0-10.5.

[0109] In some embodiments, the length a of the battery cell is 350 mm-1200 mm, the width b of the battery cell is 30 mm-140 mm, the thickness c of the battery cell is 10 mm-60 mm, and a / b is 3.1-10.5.

[0110] In some embodiments, the length a of the battery cell is 250 mm-800 mm, the width b of the battery cell is 30 mm-140 mm, the thickness c of the battery cell is 10 mm-60 mm, and a / b is 2.5-8.0.

[0111] In some embodiments, the length a of the battery cell is 350 mm-800 mm, the width b of the battery cell is 30 mm-140 mm, the thickness c of the battery cell is 10 mm-60 mm, and a / b is 3.1-8.0, optionally 3.3-8.0.

[0112] In some embodiments, the length a of the battery cell is 420 mm-800 mm, the width b of the battery cell is 30 mm-140 mm, the thickness c of the battery cell is 10 mm-60 mm, and a / b is 3.1-8.0, optionally 3.3-8.0.

[0113] This allows the battery to better balance high energy density and long cycle life.

[0114] The battery cell can be a rectangular parallelepiped structure or a soft-pack structure, which is not limited in the embodiments of the present application. As shown in Figures 1 to 10, the battery cell 5 provided in some embodiments of the present application is a rectangular parallelepiped structure.

[0115] The length a and width b of a battery cell refer to the dimensions of the main body of the battery cell in the length direction X and the width direction Y, which do not include the dimensions of the electrode terminals protruding from the main body of the battery cell.

[0116] The length a of the battery cell can be measured by a laser thickness gauge. During the test, 3-5 points can be randomly selected and the average value can be taken.

[0117] The width b of the battery cell can be measured by a laser thickness gauge. During the test, 3-5 points can be randomly selected and the average value can be taken.

[0118] The thickness c of the battery cell can be measured by a laser thickness gauge. During the test, 9 points can be randomly selected and the average value is taken.

[0119] In addition to the positive electrode sheet, the battery assembly also includes the negative electrode sheet and a separator. The separator is located between the positive and negative electrode sheets and plays a role in preventing internal short circuits in the battery cells.

[0120] In some embodiments, the electrode assembly may be a wound structure. For example, the positive electrode sheet, negative electrode sheet, and separator are all strip-shaped structures. In embodiments of the present application, the positive electrode sheet, separator, and negative electrode sheet may be stacked sequentially and wound two or more times to form an electrode assembly. In a battery cell, the number of electrode assemblies contained within the outer packaging may be one or more. When there are multiple electrode assemblies, the multiple electrode assemblies are arranged sequentially in the thickness direction Z of the battery cell.

[0121] In some embodiments, the electrode assembly may have a laminated structure. For example, the electrode assembly includes multiple positive electrode sheets and multiple negative electrode sheets, with the positive and negative electrode sheets alternately stacked along the thickness direction Z. When the electrode assembly has a laminated structure, the battery cells can have a higher group margin, thereby further improving the battery's energy density.

[0122] A battery cell consists of an electrode assembly, an outer packaging, and an electrolyte. The outer packaging is used to encapsulate the electrode assembly and the electrolyte.

[0123] In some embodiments, the outer packaging can be made of a soft bag material or a hard shell material. The soft bag material can be plastic, such as one or more of aluminum-plastic film, polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). The hard shell material can include, but is not limited to, a hard plastic shell, an aluminum shell, or a steel shell.

[0124] In some embodiments, the outer packaging may be made of a hard shell material.

[0125] As shown in FIG. 1 to FIG. 10 , the battery cell 5 includes an electrode assembly 52 and an outer package. The electrode assembly 52 includes a main body 521 and a tab 522 extending from the main body 521 . The outer package includes a shell 51 and an end cap assembly 53 .

[0126] As shown in FIG3 and FIG10 , the shell 51 may be a hollow structure with one side open, and the end cap assembly 53 covers the opening of the shell 51 and forms a sealed connection to form a housing cavity for accommodating the electrode assembly 52 and the electrolyte.

[0127] As shown in Figure 6, the outer packaging may include a shell 51 and two end cover assemblies 53. The shell 51 is a hollow structure with openings on opposite sides. One end cover assembly 53 covers one opening of the shell 51 and forms a sealed connection to form a accommodating cavity for accommodating the electrode assembly 52 and the electrolyte.

[0128] The end cap assembly 53 may include an end cap, which covers the opening of the housing 51. The end cap may have various structures, for example, a plate-like structure, a hollow structure with one end open, etc.

[0129] The end cap can be made of an insulating material (such as plastic) or a conductive material (such as metal). When the end cap is made of a conductive material, the end cap assembly can further include an insulating member located on the side of the end cap facing the electrode assembly to insulate the end cap from the electrode assembly.

[0130] The end cap assembly 53 may further include an electrode terminal 531 mounted on the end cap. There may be two electrode terminals 531, each defined as a positive electrode terminal and a negative electrode terminal. Both the positive electrode terminal and the negative electrode terminal are used to electrically connect to the electrode assembly 52 to output the electrical energy generated by the electrode assembly 52. ​​The positive and negative electrode terminals may be located at the same end of the battery cell 5 or at opposite ends of the battery cell 5.

[0131] The electrode assembly includes a main body and a tab extending from the main body. In some embodiments, there may be two tabs 522. The two tabs are defined as a positive electrode tab and a negative electrode tab, respectively.

[0132] As shown in Figures 2 and 9, the two pole ear portions 522 (i.e., the positive pole ear portion and the negative pole ear portion) can extend from the same end of the main body portion 521 of the electrode assembly 52. ​​For example, the two pole ear portions 522 extend from one end of the main body portion 521 of the electrode assembly 52 close to the end cover assembly 53.

[0133] As shown in Figures 5 and 8, the two electrode tabs 522 (the positive electrode tab and the negative electrode tab) may also extend from opposite ends of the main body 521 of the electrode assembly 52, for example, from opposite ends of the main body 521 of the electrode assembly 52 along the length direction X of the battery cell. This can make the positive electrode tab and the negative electrode tab wider (i.e., larger in the direction not extending from the main body), thereby improving the electronic conductivity of the electrode sheet.

[0134] When the two tab portions 522 extend from opposite ends of the main body 521 of the electrode assembly 52 , the electrode terminals 531 may be located at the same end of the battery cell 5 or at opposite ends of the battery cell 5 .

[0135] The main body 521 is the core component of the electrode assembly 52 that enables charging and discharging. The tabs 522 are used to extract the current generated by the main body 521. The main body 521 includes the positive electrode current collector, the positive electrode film layer, the negative electrode current collector, the negative electrode film layer, and the separator. The positive electrode tabs can include multiple positive tabs, and the negative electrode tabs can include multiple negative tabs.

[0136] The tab portion 522 is electrically connected to the electrode terminal 531. The tab portion 522 may be directly connected to the electrode terminal 531 by welding or other methods, or may be indirectly connected to the electrode terminal 531 via other components. For example, the electrode assembly 52 also includes a current collecting member, which is used to electrically connect the electrode terminal 531 and the tab portion 522. There may be two current collecting members, each defined as a positive current collecting member and a negative current collecting member. The positive current collecting member is used to electrically connect the positive electrode terminal and the positive tab portion, and the negative current collecting member is used to electrically connect the negative electrode terminal and the negative tab portion. When the battery cell 5 is provided with multiple electrode assemblies 52, the positive current collecting members of the multiple electrode assemblies 52 may be provided integrally, and the negative current collecting members of the multiple electrode assemblies 52 may be provided integrally.

[0137] In some embodiments, the dimension of each tab 522 in the extension direction of the main body after bending can be less than or equal to 20 mm, and more preferably less than or equal to 15 mm. This allows the electrode sheet to have a larger effective size, thereby improving the group margin of the battery cell and increasing the mass ratio of the positive electrode active material and the negative electrode active material in the entire battery cell, thereby also enabling the battery to have a high energy density.

[0138] The positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0139] In some embodiments, the positive electrode active material may include both a single-crystal layered lithium-containing transition metal oxide and a polycrystalline layered lithium-containing transition metal oxide.

[0140] Single-crystal layered lithium-containing transition metal oxides typically have a smaller specific surface area and better interfacial and thermal stability, which can reduce battery side reactions. They also maintain good particle integrity during long-term charge and discharge processes, thereby reducing the rate of battery capacity decay. Therefore, when the positive electrode active material includes a single-crystal layered lithium-containing transition metal oxide, the battery can generally achieve a long cycle life. However, the lithium ion diffusion coefficient of single-crystal layered lithium-containing transition metal oxides is generally low, which can also reduce the battery's power performance. Polycrystalline layered lithium-containing transition metal oxides have a higher lithium ion diffusion coefficient, better electrolyte wettability, and shorter lithium ion diffusion paths, which facilitate lithium ion extraction and insertion at high current densities. Therefore, when the positive electrode active material includes both single-crystal layered lithium-containing transition metal oxides and polycrystalline layered lithium-containing transition metal oxides, the battery can achieve both high energy density and long cycle life while also achieving good power performance.

[0141] In some embodiments, in the positive electrode active material, the percentage of the layered lithium-containing transition metal oxide with a single crystal morphology is denoted as S1, and the percentage of the layered lithium-containing transition metal oxide with a polycrystalline morphology is denoted as S2, where S1>S2. This allows the battery to have high energy density, long cycle life, and good power performance.

[0142] In some embodiments, in the positive electrode active material, the proportion of the layered lithium-containing transition metal oxide with a single crystal morphology is denoted as S1, and S1 is greater than 50%, and can be optionally greater than or equal to 70%.

[0143] In some embodiments, S1 may be 70%-100%, 80%-100%, 70%-99%, 80%-99%, 70%-97%, 80%-97%, 70%-95%, 80%-95%.

[0144] By making the positive electrode active material mainly include layered lithium-containing transition metal oxides with a single crystal morphology, the battery can have high energy density, long cycle life and good power performance.

[0145] In some embodiments, the volume distribution particle size Dv50 of the positive electrode active material may be less than or equal to 8 μm, and may be 2 μm-8 μm, 2 μm-7.2 μm, 2 μm-5.5 μm, 3 μm-8 μm, 3 μm-7.2 μm, or 3 μm-5.5 μm.

[0146] In some embodiments, the volume distribution particle size Dv90 of the positive electrode active material may be less than or equal to 18 μm, and may be optionally 3 μm-12 μm.

[0147] By adjusting the volume distribution particle size Dv50 and / or Dv90 of the positive electrode active material within the above range, the battery side reactions can be reduced, the battery capacity attenuation rate can be lowered, the battery has a long cycle life, and the battery can also have good power performance.

[0148] In some embodiments, the layered lithium-containing transition metal oxide may include one or more of lithium cobalt oxide and ternary materials. The general formula of the ternary material can be Li a Ni b Co c M d O e A f 0.8≤a≤1.2, 0<b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes but is not limited to one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, A includes but is not limited to one or more of N, F, S and Cl. Optionally, 0.5≤b<1, 0.8≤b<1, 0.9≤b<1. This can further improve the energy density of the battery.

[0149] As an example, the layered lithium-containing transition metal oxide may include but is not limited to LiCoO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.9 Co 0.06 Mn 0.04 O2、LiNi 0.96 Co 0.02 Mn 0.02 O2、LiNi 0.85 Co 0.15 Al 0.05 One or more of O2.

[0150] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. The present application does not particularly limit the type of the positive electrode conductive agent. In some embodiments, as examples, the positive electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0151] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. The present application has no particular restrictions on the type of positive electrode binder. In some embodiments, as an example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0152] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0153] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, positive electrode binder, and positive electrode conductive agent in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0154] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0155] The negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0156] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As examples of metal foils, copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0157] In some embodiments, the negative electrode active material may include a carbon material. Alternatively, the carbon material may include one or more of artificial graphite and natural graphite.

[0158] In some embodiments, the negative electrode active material may include a silicon-based material, thereby increasing the energy density of the battery. The silicon-based material may include one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy.

[0159] In some embodiments, the silicon-based material may include silicon and one or more of an alkali metal element and an alkaline earth metal element. Optionally, the alkali metal element includes Li. Optionally, the alkaline earth metal element includes Mg. As an example, the silicon-based material may be a silicon-based material pre-embedded with an alkali metal and / or alkaline earth metal, for example, a silicon-based material pre-embedded with Li and / or Mg.

[0160] In some embodiments, the mass proportion of the silicon-based material in the negative electrode active material may be greater than or equal to 5%, and may be optionally 8%-20%.

[0161] In some embodiments, the negative electrode active material may include a carbon material and a silicon-based material. The silicon-based material may account for 8% to 20% by weight of the negative electrode active material, and the carbon material may account for greater than or equal to 80% by weight of the negative electrode active material. This allows the battery to have both high energy density and long cycle life.

[0162] In some embodiments, the volume distribution particle size Dv10 of the negative electrode active material may be 4 μm-8 μm, optionally 4.5 μm-6.5 μm.

[0163] In some embodiments, the volume distribution particle size Dv50 of the negative electrode active material may be 6 μm-15 μm, optionally 8 μm-13 μm.

[0164] In some embodiments, the volume distribution particle size Dv90 of the negative electrode active material may be 15 μm-30 μm, optionally 18 μm-25 μm.

[0165] By adjusting the volume distribution particle size Dv10, Dv50 and / or Dv90 of the negative electrode active material within the above range, the battery side reactions can be reduced, the battery can have a long cycle life, and the battery can also have good power performance.

[0166] In some embodiments, the negative electrode film layer may further include a negative electrode binder, for example, it may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (for example, polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS), and the embodiments of the present application are not limited to this.

[0167] In some embodiments, the negative electrode film layer may further optionally include a negative electrode conductive agent. The present application does not particularly limit the type of the negative electrode conductive agent. For example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0168] In some embodiments, the negative electrode film layer may further include other additives, such as thickeners, sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.

[0169] The negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate may further include a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode plate may further include a protective layer covering the surface of the negative electrode film layer.

[0170] The negative electrode sheet can be prepared by dispersing the negative electrode active material, optional negative electrode binder, optional negative electrode conductive agent, and optional other additives in a solvent and stirring uniformly to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and performing drying, cold pressing, and other steps to form the negative electrode sheet. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0171] In some embodiments, the negative electrode plate may also have other structures. Figure 11 is a schematic diagram of the structure of the negative electrode plate provided in some embodiments of the present application. Figure 12 is a schematic diagram of the structure of the negative electrode plate provided in other embodiments of the present application. Figure 13 is a schematic diagram of the structure of the negative electrode plate provided in still other embodiments of the present application.

[0172] As shown in Figures 11 to 13, the negative electrode plate 10 includes a negative electrode current collector 101 and a negative electrode film layer 102 arranged on at least one surface of the negative electrode current collector 101. The negative electrode film layer 102 includes a negative electrode active material. The negative electrode film layer 102 has a first surface 102a away from the negative electrode current collector 101 and a second surface 102b arranged opposite to the first surface 102a. The thickness of the negative electrode film layer 102 is recorded as H.

[0173] The thickness H of the negative electrode film layer refers to the thickness of the negative electrode film layer located on one side of the negative electrode current collector.

[0174] The region from the first surface 102a of the negative electrode film layer 102 to a thickness of 0.3H is recorded as the first region 1021 of the negative electrode film layer 102, and the region from the second surface 102b of the negative electrode film layer 102 to a thickness of 0.3H is recorded as the second region 1022 of the negative electrode film layer 102.

[0175] The first region 1021 includes a first negative electrode active material, and the second region 1022 includes a second negative electrode active material. The first negative electrode active material includes a first carbon material, and the second negative electrode active material includes a second carbon material. The volume distribution particle size Dv50 of the first carbon material is smaller than the volume distribution particle size Dv50 of the second carbon material.

[0176] The battery cell provided in the embodiment of the present application has a large length dimension, which is conducive to the battery having a high energy density, but the power performance of the battery will be affected. By adjusting the structure of the negative electrode film layer on one side of the negative electrode current collector and performing differential coating, the battery can have good power performance. The first carbon material is in direct contact with the electrolyte. By making the volume distribution particle size Dv50 of the first carbon material smaller than the volume distribution particle size Dv50 of the second carbon material, the first region of the negative electrode film layer can have more ion embedding channels, which is conducive to the rapid migration of ions to the second carbon material. This allows the battery to have high energy density and long cycle life while taking into account good power performance.

[0177] In some embodiments, the specific surface area of ​​the first carbon material can be smaller than the specific surface area of ​​the second carbon material. The first carbon material is in direct contact with the electrolyte. By making the specific surface area of ​​the first carbon material smaller than the specific surface area of ​​the second carbon material, it is beneficial to reduce battery side reactions, thereby facilitating better cycle performance of the battery.

[0178] In some embodiments, the degree of graphitization of the first carbon material can be lower than that of the second carbon material. The lower degree of graphitization of the first carbon material results in a larger interlayer spacing, which facilitates rapid ion deintercalation. Therefore, by adjusting the degree of graphitization of the first carbon material to be lower than that of the second carbon material, the power performance of the battery can be improved.

[0179] In some embodiments, the first carbon material may include artificial graphite. By making the first carbon material include artificial graphite, it is beneficial to reduce battery side reactions, thereby facilitating better cycle performance of the battery.

[0180] In some embodiments, the second carbon material may include natural graphite. Natural graphite has high surface activity, and including natural graphite as the second carbon material is beneficial for improving the power performance of the battery.

[0181] In some embodiments, the first negative electrode active material may include a carbon material and a silicon-based material. Compared to pure carbon material, when the first negative electrode active material includes a carbon material and a silicon-based material, the battery may have a higher energy density under the same areal density condition.

[0182] In some embodiments, the second negative electrode active material may include a carbon material and a silicon-based material. Compared to pure carbon material, when the second negative electrode active material includes a carbon material and a silicon-based material, the battery may have a higher energy density under the same areal density conditions.

[0183] In some embodiments, the first negative electrode active material and the second negative electrode active material may include both a carbon material and a silicon-based material, thereby enabling the battery to have a higher energy density.

[0184] In some embodiments, the first negative electrode active material and the second negative electrode active material both include a carbon material and a silicon-based material.

[0185] As shown in FIG11 to FIG13 , the negative electrode film layer 102 further includes a middle region 1023 located between the first region 1021 and the second region 1022 of the negative electrode film layer and having a thickness of 0.4H (H represents the thickness of the negative electrode film layer 102 ).

[0186] In some embodiments, the intermediate region includes a first negative electrode active material and / or a second negative electrode active material. For example, as shown in FIG11 , the intermediate region 1023 includes both the first negative electrode active material and the second negative electrode active material. In this case, the intermediate region 1023 includes both a layer structure having the first negative electrode active material and a layer structure having the second negative electrode active material. The two-layer structure may also have a layer interface. Alternatively, as shown in FIG12 , the intermediate region 1023 may be the same in composition as the first region 1021 , whereby the first negative electrode active material is distributed in the thickness direction of the negative electrode film layer 102 within a range from the first surface 102a of the negative electrode film layer to a thickness of 0.7H. Alternatively, as shown in FIG13 , the intermediate region 1023 may be the same in composition as the second region 1022 , whereby the second negative electrode active material is distributed in the thickness direction of the negative electrode film layer 102 within a range from the second surface 102b of the negative electrode film layer to a thickness of 0.7H.

[0187] In some embodiments, the first region, the second region, and the middle region of the negative electrode film layer may optionally further include a negative electrode conductor and / or a negative electrode binder.

[0188] The negative electrode sheet can be prepared according to the following method: providing a first negative electrode slurry containing a first negative electrode active material and a second negative electrode slurry containing a second negative electrode active material; coating the second negative electrode slurry on the negative electrode collector, coating the first negative electrode slurry on the second negative electrode slurry, and obtaining the negative electrode sheet after drying and cold pressing.

[0189] In some embodiments, the first negative electrode active material, an optional conductive agent, an optional binder, and other optional auxiliary agents may be dispersed in a solvent (eg, deionized water) to form a first negative electrode slurry.

[0190] In some embodiments, the second negative electrode active material, an optional conductive agent, an optional binder, and other optional auxiliary agents may be dispersed in a solvent (eg, deionized water) to form a second negative electrode slurry.

[0191] The first negative electrode slurry and the second negative electrode slurry can be applied simultaneously in one application or in two separate applications. In some embodiments, the first negative electrode slurry and the second negative electrode slurry are applied simultaneously in one application. Applying them simultaneously in one application can reduce the negative electrode film resistance, thereby further improving the power performance and cycle performance of the battery.

[0192] The coating weights of the first negative electrode slurry and the second negative electrode slurry can be adjusted according to actual conditions.

[0193] The first negative electrode active material, the second negative electrode active material, etc. mentioned above can be obtained commercially.

[0194] The battery cell also includes an electrolyte. The electrolyte conducts ions between the positive and negative electrodes. In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0195] The type of electrolyte salt is not specifically limited and can be selected according to actual needs. In some embodiments, the electrolyte salt may include 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 difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0196] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the solvent may include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl 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 one or more of diethyl sulfone (ESE).

[0197] 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, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0198] The battery cell may also include a separator. This separator can be positioned between the positive and negative electrode sheets, primarily to prevent internal short circuits. This application does not specifically limit the type of separator; any known porous membrane with good chemical and mechanical stability may be used.

[0199] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The isolation membrane may be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different.

[0200] The preparation method of battery cells is well known. In some embodiments, the positive electrode sheet, separator, negative electrode sheet and electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, separator, and negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process, and the electrode assembly is placed in an outer package, dried and injected with the above-mentioned electrolyte, and then vacuum packaged, allowed to stand, formed and other processes to obtain a battery cell. Multiple battery cells can also be further connected in series, in parallel or in a mixed connection to form a battery module. Multiple battery modules can also be connected in series, in parallel or in a mixed connection to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0201] The present application also provides an electrical device, which includes a battery provided in the present application. The battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0202] The electrical device can select the type of battery according to its usage requirements, such as a battery cell, a battery module or a battery pack.

[0203] Figure 14 is a schematic diagram of an exemplary electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module may be used.

[0204] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0205] Example

[0206] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0207] The batteries of Examples 1 to 14 and Comparative Examples 1 to 2 were prepared according to the following method.

[0208] The positive electrode active material LiNi shown in Table 1 0.9 Co 0.06 Mn 0.04 O2, conductive agent Super P, and binder polyvinylidene fluoride are mixed in a weight ratio of 96.5:1.5:2, and an appropriate amount of solvent NMP is added and stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is coated on both surfaces of the positive electrode current collector aluminum foil, dried, and cold pressed to obtain a positive electrode sheet. The positive electrode active material LiNi 0.9 Co 0.06 Mn 0.04 O2 has a single crystal morphology, and the number of single crystal particles accounts for more than 98%.

[0209] Graphite (negative electrode active material), Super P (conductive agent), styrene-butadiene rubber (binder), and sodium carboxymethyl cellulose (thickener) were thoroughly stirred in a suitable amount of deionized water (solvent) at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a negative electrode slurry. The negative electrode slurry was applied to both surfaces of the negative electrode current collector copper foil. After drying and cold pressing, the negative electrode sheet was obtained.

[0210] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and then LiPF6 is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0211] A PP film is used as a separator and assembled with the aforementioned positive and negative electrode sheets to form a laminated electrode assembly. The electrode assembly is placed in a hard shell, dried, and then injected with electrolyte. After vacuum packaging, standing, and formation, the battery shown in Figure 4 is obtained. The positive and negative electrode tabs extend from opposite ends of the main body of the electrode assembly, and the positive and negative electrode terminals are located at opposite ends of the battery.

[0212] In Table 1, the length of the battery is recorded as a, the width of the battery is recorded as b, and the thickness of the battery is recorded as c. The length direction X, width direction Y, and thickness direction Z of the battery are perpendicular to each other, and the thickness direction Z of the battery is the stacking direction of the positive and negative electrode sheets.

[0213] The coating area density and compaction density of the positive electrode sheets and the negative electrode sheets in the above-mentioned embodiments and comparative examples are the same.

[0214] Performance Testing

[0215] (1) Battery energy density test

[0216] At 25°C, the prepared battery was charged at a constant current of 0.33C to 4.3V, and then charged at a constant voltage to a current of 0.05C. After standing for 5 minutes, the battery was discharged at a constant current of 0.33C to 2.8V, and the discharge energy Q was obtained.

[0217] The energy density of a battery (Wh / L) = discharge energy Q / battery volume V.

[0218] (2) Battery cycle performance test

[0219] At 25°C, the prepared battery was charged at a constant current of 1C to 4.3V, then charged at a constant voltage to a current of 0.05C. After standing for 5 minutes, the battery was discharged at a constant current of 1C to 2.8V. The discharge capacity at this point was recorded as the first cycle discharge capacity. The battery was cyclically charged and discharged according to the above method until the battery capacity decayed to 80% of the first cycle discharge capacity. The number of cycles was recorded.

[0220] (3) Battery power performance test

[0221] At 25°C, the prepared battery was charged at a constant current of 1C to 4.3V, then charged at a constant voltage to a current of 0.05C. After 5 minutes of rest, the battery was discharged at 1C for 30 minutes, adjusting the SOC to 50%. The pre-discharge voltage, U1, was recorded. The battery was then discharged at a constant current of 3C for 30 seconds, and the post-discharge voltage, U2, was recorded. Battery power, W, = lower cutoff voltage × (U1 - lower cutoff voltage) / (U1 - U2) / 3C. The lower cutoff voltage was 2.8V.

[0222] Table 1

[0223] From the test results in Table 1, it can be seen that by making the positive electrode active material include a layered lithium-containing transition metal oxide with a single crystal morphology, and making the length a of the battery greater than or equal to 180 mm, and the ratio a / b of the length a of the battery to the width b of the battery being 2.0-10.5, the battery can have both high energy density and long cycle life.

[0224] When the length a of the battery is less than 180 mm, the ratio a / b of the length a of the battery to the width b of the battery is less than 2.0, or the ratio a / b of the length a of the battery to the width b of the battery is greater than 10.5, it is difficult to meet the use requirements of both long cycle life and high energy density batteries.

[0225] From the test results in Table 1, it can be seen that further adjusting the length a of the battery and the ratio a / b of the length a of the battery to the width b of the battery can further improve the overall performance of the battery.

[0226] Table 2

[0227] From the test results in Table 2, it can be seen that further adjusting the length a of the battery and the ratio a / b of the length a of the battery to the width b of the battery can also make the battery have good power performance.

[0228] Examples 15 to 17

[0229] The preparation method of the battery is similar to that of Example 4, except that the positive electrode active material also includes single crystal LiNi 0.9 Co0.06 Mn 0.04 O2 and polycrystalline LiNi 0.9 Co 0.06 Mn 0.04 O2, and their respective proportions are shown in Table 3.

[0230] Table 3

[0231] From the test results in Table 3, it can be seen that by making the proportion of single-crystal layered lithium-containing transition metal oxides in the positive electrode active material greater than 50%, the battery can better balance high energy density, long cycle life and good power performance.

[0232] In the above embodiments, the layered lithium-containing transition metal oxides in single crystal and polycrystalline morphologies are both LiNi 0.9 Co 0.06 Mn 0.04 O2, but the layered lithium-containing transition metal oxide in the embodiment of the present application is not limited thereto, and other layered lithium-containing transition metal oxides have similar effects.

[0233] Example 18

[0234] The preparation method of the battery is similar to that of Example 5, except that the preparation process of the negative electrode plate is different.

[0235] The first carbon material, artificial graphite, the conductive agent, Super P, the binder, styrene-butadiene rubber, and the thickener, sodium carboxymethyl cellulose, were mixed thoroughly in an appropriate amount of deionized water at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a first negative electrode slurry. The second carbon material, artificial graphite, the conductive agent, Super P, the binder, styrene-butadiene rubber, and the thickener, sodium carboxymethyl cellulose, were mixed thoroughly in an appropriate amount of deionized water at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a second negative electrode slurry.

[0236] The second negative electrode slurry was applied to both surfaces of the negative electrode current collector copper foil. The first negative electrode slurry was applied to the second negative electrode slurry. The negative electrode current collector coated with the slurry was air-dried at room temperature and then transferred to an oven for drying. The negative electrode sheet was then cold-pressed and slit. The coating thickness ratio of the first negative electrode slurry to the second negative electrode slurry was 5:5. The thickness of the negative electrode sheet was the same as that of Example 5. The volume distribution particle size Dv50 of the first carbon material artificial graphite was 9.5 μm, and the volume distribution particle size Dv50 of the second carbon material artificial graphite was 12 μm.

[0237] Example 19

[0238] The preparation method of the battery is similar to that of Example 5, except that the preparation process of the negative electrode plate is different.

[0239] The first carbon material, artificial graphite, the conductive agent, Super P, the binder, styrene-butadiene rubber, and the thickener, sodium carboxymethyl cellulose, were mixed thoroughly in an appropriate amount of deionized water at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a first negative electrode slurry. The second carbon material, artificial graphite, the conductive agent, Super P, the binder, styrene-butadiene rubber, and the thickener, sodium carboxymethyl cellulose, were mixed thoroughly in an appropriate amount of deionized water at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a second negative electrode slurry.

[0240] The second negative electrode slurry was applied to both surfaces of the negative electrode current collector copper foil. The first negative electrode slurry was applied to the second negative electrode slurry. The negative electrode current collector coated with the slurry was air-dried at room temperature and then transferred to an oven for drying. The negative electrode sheet was then cold-pressed and slit. The coating thickness ratio of the first negative electrode slurry to the second negative electrode slurry was 5:5. The thickness of the negative electrode sheet was the same as that of Example 5. The volume distribution particle size Dv50 of the first carbon material artificial graphite was 14 μm, and the volume distribution particle size Dv50 of the second carbon material artificial graphite was 12 μm.

[0241] Example 20

[0242] The preparation method of the battery is similar to that of Example 5, except that the preparation process of the negative electrode plate is different.

[0243] The first carbon material, artificial graphite, the conductive agent Super P, the binder styrene-butadiene rubber, and the thickener sodium carboxymethyl cellulose were thoroughly stirred and mixed in an appropriate amount of deionized water at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a first negative electrode slurry. The second carbon material, natural graphite, the conductive agent Super P, the binder styrene-butadiene rubber, and the thickener sodium carboxymethyl cellulose were thoroughly stirred and mixed in an appropriate amount of deionized water at a weight ratio of 96.2:0.8:1.8:1.2 to obtain a second negative electrode slurry.

[0244] The second negative electrode slurry was applied to both surfaces of the negative electrode current collector copper foil. The first negative electrode slurry was applied to the second negative electrode slurry. The negative electrode current collector coated with the slurry was air-dried at room temperature and then transferred to an oven for drying. The negative electrode sheet was then cold-pressed and slit. The coating thickness ratio of the first negative electrode slurry to the second negative electrode slurry was 5:5. The thickness of the negative electrode sheet was the same as that of Example 5. The volume distribution particle size Dv50 of the first carbon material, artificial graphite, was 12 μm, and the volume distribution particle size Dv50 of the second carbon material, natural graphite, was 14 μm.

[0245] Table 4

[0246] It can be seen from the test results of Example 4, Example 18 and Example 19 that by adjusting the structure of the negative electrode film layer on one side of the negative electrode current collector and making the volume distribution particle size Dv50 of the first carbon material smaller than the volume distribution particle size Dv50 of the second carbon material, the first region of the negative electrode film layer can have more ion embedding channels, which is conducive to the rapid migration of ions to the second carbon material, thereby enabling the battery to have better power performance while having a long cycle life.

[0247] From the test results in Table 4, it can be seen that by adjusting the structure of the negative electrode film layer on one side of the negative electrode current collector and making the first carbon material artificial graphite and the second carbon material natural graphite, the battery can have better power performance.

[0248] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, wherein: The battery cell includes an electrode assembly and an outer package; The electrode assembly comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a layered lithium-containing transition metal oxide with a single crystal morphology; The battery cell has a length direction, a width direction and a thickness direction, and the thickness direction of the battery cell is the thickness direction of the positive electrode sheet; The length of the battery cell is denoted as a, the width of the battery cell is denoted as b, a is greater than or equal to 180 mm, and a / b is 2.0-10.

5.

2. The battery cell according to claim 1, wherein: a is 190mm-1200mm, and can be optionally 250mm-1200mm.

3. The battery cell according to any one of claims 1 to 2, wherein: a is 350mm-1200mm; and / or a / b is 3.1-10.

5.

4. The battery cell according to any one of claims 1 to 2, characterized in that: a is 250mm-800mm; and / or a / b is 2.5-8.

0.

5. The battery cell according to any one of claims 1 to 4, characterized in that: a is 350mm-800mm, and can be optionally 420mm-800mm; and / or a / b is 3.1-8.0, and can be optionally 3.3-8.

0.

6. The battery cell according to any one of claims 1 to 5, wherein: b is 30mm-140mm, and can be 60mm-125mm.

7. The battery cell according to any one of claims 1 to 6, wherein: The thickness of the battery cell is denoted as c, which is less than or equal to 70 mm and can be optionally 10 mm-60 mm.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The outer packaging is made of soft packaging material or hard shell material; and / or, The electrode assembly is a laminated structure or a wound structure, and the laminated structure can be selected.

9. The battery cell according to any one of claims 1 to 8, wherein: The electrode assembly includes a main body and a tab extending from the main body. The dimension of the pole ear portion after being bent in the extending direction of the main body portion is less than or equal to 20 mm, and may be less than or equal to 15 mm; and / or, The electrode ear portion includes a positive electrode ear portion and a negative electrode ear portion, and the positive electrode ear portion and the negative electrode ear portion extend from opposite ends of the main body portion of the electrode assembly.

10. The battery cell according to any one of claims 1 to 9, wherein: The positive electrode active material includes both a layered lithium-containing transition metal oxide with a single crystal morphology and a layered lithium-containing transition metal oxide with a polycrystalline morphology.

11. The battery cell according to claim 10, wherein: In the positive electrode active material, the percentage of the layered lithium-containing transition metal oxide with a single crystal morphology is denoted as S1, and the percentage of the layered lithium-containing transition metal oxide with a polycrystalline morphology is denoted as S2, and S1>S2.

12. The battery cell according to any one of claims 1 to 11, wherein: In the positive electrode active material, the percentage of the layered lithium-containing transition metal oxide with a single crystal morphology is denoted as S1, and S1 is greater than or equal to 70%, and can be optionally 80%-99%.

13. The battery cell according to any one of claims 1 to 12, wherein: The volume distribution particle size Dv50 of the positive electrode active material is less than or equal to 8 μm, and can be optionally 2 μm-5.5 μm; and / or, The volume distribution particle size Dv90 of the positive electrode active material is less than or equal to 18 μm, and can be optionally 3 μm-12 μm.

14. The battery cell according to any one of claims 1 to 13, wherein: The electrode assembly comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises a carbon material; Optionally, the carbon material includes one or more of artificial graphite and natural graphite.

15. The battery cell according to any one of claims 1 to 14, wherein: The electrode assembly comprises a negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, and the negative electrode active material comprises a silicon-based material; Optionally, the silicon-based material includes silicon and one or more of alkali metal elements and alkaline earth metal elements; and / or, Optionally, the mass proportion of the silicon-based material in the negative electrode active material is greater than or equal to 5%, and more optionally 8%-20%.

16. The battery cell according to any one of claims 14 to 15, wherein: The negative electrode active material satisfies one or more of the following (1) to (3): (1) The volume distribution particle size Dv10 of the negative electrode active material is 4 μm-8 μm, and can be 4.5 μm-6.5 μm; (2) The volume distribution particle size Dv50 of the negative electrode active material is 6 μm-15 μm, and can be 8 μm-13 μm; (3) The volume distribution particle size Dv90 of the negative electrode active material is 15 μm-30 μm, and can be optionally 18 μm-25 μm.

17. The battery cell according to any one of claims 1 to 13, wherein: The electrode assembly includes a negative electrode plate, which includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer includes a negative electrode active material, the negative electrode film layer has a first surface away from the negative electrode current collector and a second surface arranged opposite to the first surface, the thickness of the negative electrode film layer is recorded as H, the area within the thickness range from the first surface of the negative electrode film layer to 0.3H is recorded as the first area of ​​the negative electrode film layer, and the area within the thickness range from the second surface of the negative electrode film layer to 0.3H is recorded as the second area of ​​the negative electrode film layer, the first area includes a first negative electrode active material, the second area includes a second negative electrode active material, the first negative electrode active material includes a first carbon material, the second negative electrode active material includes a second carbon material, and the volume distribution particle size Dv50 of the first carbon material is smaller than the volume distribution particle size Dv50 of the second carbon material.

18. The battery cell according to claim 17, wherein: The specific surface area of ​​the first carbon material is smaller than the specific surface area of ​​the second carbon material; and / or, The graphitization degree of the first carbon material is lower than the graphitization degree of the second carbon material.

19. The battery cell according to any one of claims 17 to 18, wherein: The first carbon material includes artificial graphite; and / or, The second carbon material includes natural graphite.

20. The battery cell according to any one of claims 17 to 19, wherein: The first negative electrode active material and / or the second negative electrode active material further include a silicon-based material; optionally, both the first negative electrode active material and the second negative electrode active material include a silicon-based material.

21. A battery comprising the battery cell according to any one of claims 1 to 20.

22. An electrical device comprising the battery according to claim 21.

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