Battery cells, batteries and electrical devices

Abstract

The present invention relates to a battery cell, a battery, and an electrical device. The battery cell includes an electrode assembly and an outer casing. The electrode assembly includes a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. The positive electrode film layer comprises a positive electrode active material containing a layered lithium-containing transition metal oxide in single-crystal form. The length of the battery cell is denoted as a, and the width of the battery cell is denoted as b. By having a length of 180 mm or more and a / b being 2.0 to 10.5, the battery can have both high energy density and long cycle life.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to Chinese Patent Application No. 202310936624.3, filed on 28 July 2023, with the title of the invention "Battery Cell, Battery and Electrical Device," and all contents of said application are incorporated into this application by reference.

[0002] This application relates to battery cells, batteries, and electrical devices. [Background technology]

[0003] In recent years, batteries have been widely applied in many fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As the range of battery applications expands, the demand for batteries is also increasing. However, achieving high energy density while also possessing other electrochemical properties remains a challenging issue in current battery development. [Overview of the project]

[0004] This application provides a battery cell, a battery, and an electrical device that can combine high energy density and long cycle life. [Means for solving the problem]

[0005] In a first aspect of this application, a battery cell including an electrode assembly and an outer casing is provided.

[0006] The electrode assembly includes a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material comprising a layered lithium-containing transition metal oxide in single-crystal form.

[0007] 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.

[0008] Let the length of the battery cell be denoted as a and the width of the battery cell be denoted as b. a is 180 mm or more, and a / b is 2.0 to 10.5.

[0009] When the positive electrode active material contains a single-crystalline form of layered lithium-containing transition metal oxide, and by setting the length a of the battery cell using the same to be 180 mm or more and the ratio a / b of the length a of the battery cell to the width b of the battery cell to be 2.0 to 10.5, the battery can have both a high energy density and a long cycle life.

[0010] In any embodiment, a is 190 mm to 1200 mm, and optionally 250 mm to 1200 mm.

[0011] In any embodiment, a is 350 mm to 1200 mm, and / or a / b is 3.1 to 10.5.

[0012] In any embodiment, a is 250 mm to 800 mm, and / or a / b is 2.5 to 8.0.

[0013] In any embodiment, a is 350 mm to 800 mm, optionally 420 mm to 800 mm, and / or a / b is 3.1 to 8.0, optionally 3.3 to 8.0.

[0014] When the length a of the battery cell is within a predetermined range, after ensuring normal welding of the tab portion, the electrode sheet can have a high effective dimension, thereby improving the group margin of the battery cell and improving the mass ratio of the positive electrode active material and the negative electrode active material in the entire battery cell, and further enabling the battery to have a high energy density. When the length a of the battery cell is within a predetermined range, the electrolyte impregnation property of the entire region including the central region of the electrode assembly can also be further improved, making it easier for the electrolyte to impregnate and reflux through the entire electrode sheet, which helps in the transport of lithium ions and further enables the battery to have a long cycle life.

[0015] When the ratio a / b of the battery cell length a to the battery cell width b is within a predetermined range, the battery's cycle characteristics can be further improved, and the battery can have a high energy density.

[0016] In any embodiment, b is 30 mm to 140 mm, and selectively 60 mm to 125 mm. When the width b of the battery cell is within a predetermined range, the battery's cycle characteristics can be further improved, and the battery can have a high energy density.

[0017] In any embodiment, the thickness of the battery cell is denoted as c, where c is 70 mm or less, and selectively between 10 mm and 60 mm.

[0018] In any embodiment, the outer casing is made of pouch material or hard case material.

[0019] In any embodiment, the electrode assembly is a laminated structure or a wound structure, and is selectively a laminated structure. 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.

[0020] In any embodiment, the electrode assembly includes a main body and a tab extending from the main body, wherein the tab has a dimension of 20 mm or less in the extending direction of the main body after being bent, and selectively 15 mm or less. This allows the electrode sheet to have a high effective dimension, improves the group margin of the battery cell, improves the mass ratio of positive electrode active material to negative electrode active material in the entire battery cell, and further allows the battery to have a high energy density.

[0021] In any embodiment, the tab portion includes a positive electrode tab portion and a negative electrode tab portion, and the positive electrode tab portion and the negative electrode tab portion extend from opposite ends of the main body portion of the electrode assembly. This allows the positive electrode tab portion and the negative electrode tab portion to be made wider, which helps to improve the electronic conductivity of the electrode sheet.

[0022] In any embodiment, the positive electrode active material simultaneously contains a single-crystal layered lithium-containing transition metal oxide and a polycrystalline layered lithium-containing transition metal oxide, and selectively, in the positive electrode active material, the ratio of the number of single-crystal layered lithium-containing transition metal oxides is denoted as S1, and the ratio of the number of polycrystalline layered lithium-containing transition metal oxides is denoted as S2, where S1 > S2.

[0023] In any embodiment, S1 is the percentage of the number of layered lithium-containing transition metal oxides in single-crystal form in the positive electrode active material, where S1 is 70% or more and selectively 80% to 99%.

[0024] By primarily containing single-crystal layered lithium-containing transition metal oxides as the positive electrode active material, the battery can achieve a combination of high energy density, long cycle life, and good power characteristics.

[0025] In any embodiment, the volume distribution particle size Dv50 of the positive electrode active material is 8 μm or less, and selectively between 2 μm and 5.5 μm.

[0026] In any embodiment, the volume distribution particle size Dv90 of the positive electrode active material is 18 μm or less, and selectively between 3 μm and 12 μm.

[0027] By adjusting the volume distribution particle size Dv50 and / or Dv90 of the positive electrode active material within the above range, side reactions of the battery can be reduced, the rate of battery capacity decay can be decreased, and the battery can have a long cycle life and good power characteristics.

[0028] In any embodiment, the electrode assembly includes a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material comprising a carbon material, and optionally, the carbon material comprises one or more artificial graphite and natural graphite.

[0029] In any embodiment, the electrode assembly includes a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material comprising a silicon-based material.

[0030] Selectively, the silicon-based material comprises a silicon element and one or more alkali metal elements and alkaline earth metal elements.

[0031] Selectively, the mass percentage of the silicon-based material in the negative electrode active material is 5% or more, and more selectively, 8% to 20%.

[0032] In any embodiment, the volume distribution particle size Dv10 of the negative electrode active material is 4 μm to 8 μm, and selectively 4.5 μm to 6.5 μm.

[0033] In any embodiment, the volume distribution particle size Dv50 of the negative electrode active material is 6 μm to 15 μm, and selectively 8 μm to 13 μm.

[0034] In any embodiment, the volume distribution particle size Dv90 of the negative electrode active material is 15 μm to 30 μm, and selectively 18 μm to 25 μm.

[0035] In any embodiment, the electrode assembly includes a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises 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 facing the first surface, the thickness of the negative electrode film layer is denoted as H, the region within a thickness range from the first surface of the negative electrode film layer to 0.3H is denoted as the first region of the negative electrode film layer, and the region within a thickness range from the second surface of the negative electrode film layer to 0.3H is denoted as the second region of the negative electrode film layer, the first region comprises a first negative electrode active material, the second negative electrode active material comprises a second carbon material, and the volume-distributed particle size Dv50 of the first carbon material is smaller than the volume-distributed particle size Dv50 of the second carbon material.

[0036] By adjusting the structure of the negative electrode film layer on one side of the negative electrode current collector and applying it individually, the battery can have good power characteristics. By having the first carbon material in direct contact with the electrolyte and making the volume distribution particle size Dv50 of the first carbon material smaller than that of the second carbon material, the first region of the negative electrode film layer can have a relatively large number of ion insertion pathways, which helps to speed up the movement of ions to the second carbon material. As a result, the battery can have good power characteristics while also having high energy density and long cycle life.

[0037] 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, and by making the specific surface area of ​​the first carbon material smaller than that of the second carbon material, it helps to reduce side reactions in the battery, thus helping the battery have more favorable cycle characteristics.

[0038] In any embodiment, the degree of graphitization of the first carbon material is lower than that of the second carbon material. Because the degree of graphitization of the first carbon material is lower, its interlayer distance is larger, which facilitates rapid ion insertion and deinsertion. Therefore, adjusting the degree of graphitization of the first carbon material to be lower than that of the second carbon material helps to improve the power characteristics of the battery.

[0039] In any embodiment, the first carbon material comprises artificial graphite.

[0040] In any embodiment, the second carbon material contains natural graphite.

[0041] In any embodiment, the first anode active material and / or the second anode active material further comprises a silicon-based material. Selectively, both the first anode active material and the second anode active material further comprise a silicon-based material.

[0042] A second embodiment of this application provides a battery including the battery cell of the first embodiment of this application.

[0043] In a third aspect of this application, an electrical device including a battery according to a second aspect of this application is provided.

[0044] The electrical device of this application includes a battery provided in this application and therefore has at least the same advantages as the aforementioned battery. [Brief explanation of the drawing]

[0045] To further clarify the technical means of the embodiments of this application, the drawings used in the embodiments of this application are briefly described below. The drawings described below are merely illustrations of some embodiments of this application, and it will be apparent to those skilled in the art that other drawings can be conceived based on these drawings without any creative effort.

[0046] [Figure 1] This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application. [Figure 2] Figure 1 is a schematic diagram of the structure of the electrode assembly of a battery cell. [Figure 3] Figure 1 is a schematic diagram of the exploded casing of the battery cell. [Figure 4] This is a schematic diagram of the structure of a battery cell provided in another embodiment of this application. [Figure 5] Figure 4 is a schematic diagram of the structure of the electrode assembly of a battery cell. [Figure 6] Figure 4 is a schematic diagram of the exploded casing of the battery cell. [Figure 7] This is a schematic diagram of the structure of a battery cell provided in yet another embodiment of this application. [Figure 8] Figure 7 is a schematic diagram of the structure of the electrode assembly of a battery cell. [Figure 9] Figure 7 shows another schematic diagram of the electrode assembly of the battery cell. [Figure 10] Figure 7 is a schematic diagram of the exploded casing of the battery cell. [Figure 11] This is a schematic diagram of the structure of the negative electrode sheet provided in some embodiments of this application. [Figure 12]This is a schematic diagram of the structure of a negative electrode sheet provided in another embodiment of this application. [Figure 13] This is a schematic diagram of the structure of a negative electrode sheet provided in yet another embodiment of this application. [Figure 14] This is a schematic diagram of an electrical device provided in some embodiments of this application.

[0047] In drawings, the figures are not always drawn to actual scale. [Modes for carrying out the invention]

[0048] The embodiments of the battery cell, battery, and electrical device of this application will be described and specifically disclosed below, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of well-known matters and redundant explanations of the same structure may be omitted. This is to avoid the following explanation becoming unnecessarily verbose in order to make it easy for those skilled in the art to understand. Furthermore, the drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the intent of the claims.

[0049] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, and the boundaries of a particular range are limited by the selected lower and upper limits. Such limited ranges may or may not include endpoint values, and may be in any combination, that is, any lower limit and any upper limit can be combined to form a single range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, the ranges 60-110 and 80-120 are also understood to be predictable. Also, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all predictable. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" are listed in this specification, and "0 to 5" is merely an abbreviated representation of combinations of these numbers. Furthermore, when a parameter is described as being an integer of 2 or more, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12.

[0050] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical means, and such technical means should be considered to be included in the disclosure of this application.

[0051] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical means, and such technical means should be considered to be included in the disclosures of this application.

[0052] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, the method described above may further include step (c), meaning that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), or other cases.

[0053] Unless otherwise specified, terms such as "first," "second," etc., in this application are used to distinguish different subjects and are not intended to describe a specific order or primary-secondary relationship.

[0054] In this application, the terms "multiple" and "multiple types" refer to two or more or two or more types.

[0055] In the descriptions of the embodiments of this application, unless otherwise specified, the statement that the first feature is "above" or "below" the second feature may mean that the first and second features are in direct contact, or that they are indirectly in contact via an intermediate medium. Furthermore, the statement that the first feature is "above," "above," and "on the top surface" of the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply that the horizontal height of the first feature is greater than that of the second feature. The statement that the first feature is "below," "below," and "on the bottom surface" of the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply that the horizontal height of the first feature is less than that of the second feature.

[0056] Unless otherwise stated, terms used in this application have the meanings commonly understood by those skilled in the art.

[0057] Unless otherwise stated, the numerical values ​​of each parameter mentioned in this application can be measured by various measurement methods commonly used in the art, for example, according to the measurement methods shown in the embodiments of this application. Unless otherwise stated, the measurement temperature for each parameter is 25°C.

[0058] The Dv10, Dv50, and Dv90 of materials (e.g., positive electrode active material, negative electrode active material, etc.) have known meanings in this art and can be measured with known instruments and methods in this art. For example, they can be easily measured using a laser particle size analyzer (e.g., Malvern Mastersizer 3000), referring to GB / T 19077-2016. The physical definition of Dv90 is the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 90%, the physical definition of Dv50 is the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%, and the physical definition of Dv10 is the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 10%.

[0059] The specific surface area of ​​a material (e.g., positive electrode active material, negative electrode active material, etc.) has a known meaning in this art and can be measured using known instruments and methods in this art. For example, referring to GB / T 19587-2017, it can be measured by specific surface area analysis using nitrogen adsorption and calculated using the BET (Brunauer Emmett Teller) method. As a measuring instrument, the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, Inc., USA, can be used.

[0060] The proportion of single-crystal (or polycrystalline) layered lithium-containing transition metal oxides in the positive electrode active material has known significance in this art and can be measured using known instruments and methods in this art. For example, the positive electrode active material may be laid and bonded on a conductive adhesive to prepare a sample for measurement with dimensions of 6 cm × 1.1 cm, and the particle morphology can be measured using a scanning electron microscope and energy-dispersive spectrometer (e.g., ZEISS Sigma300). For measurement procedures, refer to JY / T010-1996. To ensure the accuracy of the measurement results, 20 different regions are randomly selected from the sample to be measured and scanned. At a constant magnification (e.g., 1000x or more), the ratio of the number of single-crystal (or polycrystalline) layered lithium-containing transition metal oxides to the total number of particles in each region is statistically calculated and can be used as the proportion of single-crystal (or polycrystalline) layered lithium-containing transition metal oxides in that region. The average value of the measurement results from the 20 measurement regions is then used as the proportion of single-crystal (or polycrystalline) layered lithium-containing transition metal oxides in the positive electrode active material.

[0061] In this application, the technical term "single crystal" further includes pseudo-single crystals (also called monolike crystals), which generally refer to particles made up of a small number of primary particles (for example, not more than 10). Polycrystalline refers to secondary particles made up of multiple primary particles.

[0062] It should be explained that in the various parameter measurements for the positive electrode (or negative electrode) active material in the embodiments of this application, the sample may be taken from the positive electrode (or negative electrode) film layer after cold pressing. As an example of obtaining the negative electrode active material from the negative electrode film layer after cold pressing, the negative electrode sheet after cold pressing may be placed in deionized water to allow the negative electrode active material to detach naturally. The negative electrode active material is filtered by suction, dried in an oven, and then the oven-dried negative electrode active material is sintered at 400°C for 2 hours to remove the binder and conductive agent and obtain the negative electrode active material.

[0063] The battery referred to in the embodiments of this application may be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include battery cells, battery modules, or battery packs. A battery cell is the smallest constituent unit of a battery and can perform charging and discharging functions on its own. If there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed connections via busbar members. In some embodiments, the battery may be a battery module. If there are multiple battery cells, the multiple battery cells are arranged and fixed to form a single battery module. In some embodiments, the battery may be a battery pack, which includes a box and battery cells, and the battery cells or battery modules are housed in the box. In some embodiments, the box may be part of the vehicle chassis structure. For example, part of the box may be at least part of the vehicle's bottom plate, or part of the box may be at least part of the vehicle's cross members and side members.

[0064] In some embodiments, the battery may be an energy storage device. The energy storage device includes energy storage containers, energy storage cabinets, and the like.

[0065] The battery cells referred to in the embodiments of this application may include lithium-ion battery cells.

[0066] The battery cell provided in the embodiment of this application includes an electrode assembly and an outer casing.

[0067] The battery cell has a length direction X, a width direction Y, and a thickness direction Z.

[0068] The thickness direction Z of the battery cell is the thickness direction of the positive electrode sheet.

[0069] The electrode assembly may have a laminated structure or a wound structure. When the electrode assembly has 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 direction in which the multiple positive electrode sheets are stacked. When the electrode assembly has a wound structure, the electrode assembly includes a flat region and a bent region, and the positive electrode sheet includes multiple flat segments located in the flat region and multiple bent segments located in the bent region, and the thickness direction Z of the battery cell refers to the thickness direction of the positive electrode sheets of the flat segments located in the flat region, that is, the direction in which the positive electrode sheets of the multiple flat segments are stacked.

[0070] The electrode assembly includes a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material containing a layered lithium-containing transition metal oxide in single-crystal form.

[0071] Let a be the length of the battery cell and b be the width of the battery cell, where a is 180 mm or more, and a / b is between 2.0 and 10.5.

[0072] The positive electrode active material of the battery cell provided in the embodiments of this application contains a single-crystal layered lithium-containing transition metal oxide. Single-crystal layered lithium-containing transition metal oxides generally have a small specific surface area and excellent interfacial and thermal stability. Therefore, they can reduce side reactions in the battery and maintain good particle integrity during long-term charge-discharge processes, thereby reducing the rate of battery capacity decay. Consequently, when the positive electrode active material contains a single-crystal layered lithium-containing transition metal oxide, the battery can have a long cycle life. However, because the pressure density of single-crystal layered lithium-containing transition metal oxides is low, the energy density of the battery becomes low, making it difficult to meet the needs of batteries that require both long cycle life and high energy density.

[0073] The energy density of a battery can be improved by increasing the length a of the battery cell. However, after increasing the length a of the battery cell, the electrolyte impregnation of the electrode assembly, especially in the later stages of the cycle, deteriorates, thus affecting the battery's cycle characteristics.

[0074] By setting the length a of the battery cell to 180 mm or more, and the ratio a / b (the ratio of the length a to the width b) to 2.0 to 10.5, the battery can achieve both high energy density and a long cycle life.

[0075] When the positive electrode active material is a polycrystalline layered lithium-containing transition metal oxide, during the long-term battery charge-discharge process, the polycrystalline layered lithium-containing transition metal oxide develops structural instability due to anisotropic lattice contraction, leading to localized stress concentration at the particle boundaries, causing microcracks to propagate. This allows the electrolyte to easily penetrate and erode the polycrystalline particles (secondary particles), resulting in numerous battery side reactions and making it difficult to meet the needs of batteries requiring long cycle life.

[0076] Although the positive electrode active material contains a layered lithium-containing transition metal oxide in single-crystal form, when the length a of the battery cell is less than 180 mm, the pressure density of the layered lithium-containing transition metal oxide in single-crystal form is low. Therefore, if the length a of the battery cell is too small, the dimensional design of the battery cell is insufficient to compensate for the decrease in battery energy density due to the layered lithium-containing transition metal oxide in single-crystal form, making it difficult to meet the needs of batteries that require high energy density.

[0077] When the positive electrode active material contains a layered lithium-containing transition metal oxide in single-crystal form, if the ratio of the battery cell length a to the battery cell width b (a / b) is less than 2, then the battery cell length a is too small and / or the battery cell width b is too large. If the battery cell length a is too small, the dimensional design of the battery cell is insufficient to compensate for the decrease in battery energy density due to the layered lithium-containing transition metal oxide in single-crystal form, making it difficult to meet the needs of batteries that require high energy density. If the battery cell width b is too large, it can affect the impregnation of the electrolyte, and in particular, the probability of lithium deposition increases in the negative electrode sheet. Therefore, even if the ratio of the battery cell length a to the battery cell width b (a / b) is less than 2, it is difficult to meet the needs of batteries that require long cycle life and high energy density. When the positive electrode active material contains a layered lithium-containing transition metal oxide in single-crystal form, if the ratio of the battery cell length a to the battery cell width b (a / b) is greater than 10.5, the battery cell length a is too large, the electrolyte is greatly affected by its own gravity, and the electrolyte impregnation of the electrode assembly deteriorates. This reduces the battery's cycle characteristics and makes it difficult to meet the needs of batteries that require long cycle life and high energy density.

[0078] The length a of the battery cell is 180 mm or more, and may be, for example, 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 any of these values.

[0079] In some embodiments, the length a of the battery cell may be 190 mm or more, and is selectively between 190 mm and 1200 mm, 190 mm and 1000 mm, 190 mm and 800 mm, 190 mm and 600 mm, 190 mm and 420 mm, 220 mm and 1200 mm, 220 mm and 1000 mm, 220 mm and 800 mm, 220 mm and 600 mm, 220 mm and 420 mm, 250 mm and 1200 mm, 250 mm and 1000 mm, 250 mm and 800 mm, 300 mm and 1200 mm, 300 mm and 800 mm, 350 mm and 1200 mm, 350 mm and 800 mm, 420 mm and 1200 mm, and 420 mm and 800 mm.

[0080] When the length a of the battery cell is within a predetermined range, the electrode sheet can have a high effective dimension while ensuring normal welding of the tab portion. This improves the group margin of the battery cell and improves the mass ratio of positive electrode active material to negative electrode active material in the entire battery cell, allowing the battery to have a high energy density. When the length a of the battery cell is within a predetermined range, the electrolyte impregnation of the entire region including the central region of the electrode assembly can be further improved, making it easier to impregnate and recirculate the electrolyte throughout the electrode sheet. This helps in the transport of lithium ions, and allows the battery to have a longer cycle life.

[0081] The ratio a / b of the length a of the battery cell to the width b of the battery cell is 2.0 or greater, and is, for example, within the range of 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 any of these values.

[0082] In several embodiments, the ratio a / b of the battery cell length a to the battery cell width b is 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, and 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 are also acceptable.

[0083] When the ratio a / b of the battery cell length a to the battery cell width b is within a predetermined range, the effect of gravity on the electrolyte can be reduced, which helps in the penetration of the electrolyte into the electrode assembly. Furthermore, the expansion and contraction of the electrode sheet in the lateral and longitudinal directions can be more balanced, which helps in stabilizing the interface of the electrode sheet. Therefore, when the ratio a / b of the battery cell length a to the battery cell width b is within a predetermined range, the cycle characteristics of the battery can be further improved.

[0084] Furthermore, the dimensional design of a battery cell affects its capacity, and a battery can have a high energy density when the ratio a / b of the battery cell length a to the battery cell width b is within a predetermined range.

[0085] In some embodiments, the width b of the battery cell may be 140 mm or less, and is selectively 125 mm or less.

[0086] In some embodiments, the width b of the battery cell may 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, or 80mm-100mm.

[0087] When the width b of the battery cell is within a predetermined range, this helps in the uniform impregnation and reflux of the electrolyte into the electrode sheet, reducing the probability of ion reduction deposition problems occurring due to difficulties in electrolyte impregnation and reflux in the central region of the electrode sheet. It also mitigates the problem of wrinkles forming at the interface due to continuous contraction and expansion during the charge-discharge process in the electrode sheet (especially the negative electrode sheet), and further balances the current density on the electrode sheet surface, particularly reducing the probability of lithium deposition in the negative electrode. Therefore, when the width b of the battery cell is within a predetermined range, the battery's cycle characteristics can be further improved.

[0088] This also helps the battery have a high energy density when the width b of the battery cell is within a predetermined range.

[0089] In some embodiments, the thickness c of the battery cell may be 70 mm or less, and is selectively 10 mm to 60 mm, 15 mm to 60 mm, 20 mm to 60 mm, 10 mm to 50 mm, 15 mm to 50 mm, 20 mm to 50 mm, 10 mm to 40 mm, 15 mm to 40 mm, or 20 mm to 40 mm.

[0090] In some embodiments, the length a of the battery cell is 350 mm to 1200 mm, and / or a / b is 3.1 to 10.5 mm.

[0091] In some embodiments, the length a of the battery cell is 250 mm to 800 mm, and / or a / b is 2.5 to 8.0 mm.

[0092] In some embodiments, the length a of the battery cell is 350 mm to 800 mm, selectively 420 mm to 800 mm, and / or a / b is 3.1 to 8.0, selectively 3.3 to 8.0.

[0093] In some embodiments, the length a of the battery cell is 190 mm to 1200 mm, the width b of the battery cell is 30 mm to 140 mm, the thickness c of the battery cell is 10 mm to 60 mm, and a / b is 2.0 to 10.5.

[0094] In some embodiments, the length a of the battery cell is 350 mm to 1200 mm, the width b of the battery cell is 30 mm to 140 mm, the thickness c of the battery cell is 10 mm to 60 mm, and the ratio a / b is 3.1 to 10.5.

[0095] In some embodiments, the length a of the battery cell is 250 mm to 800 mm, the width b of the battery cell is 30 mm to 140 mm, the thickness c of the battery cell is 10 mm to 60 mm, and a / b is 2.5 to 8.0.

[0096] In some embodiments, the length a of the battery cell is 350 mm to 800 mm, the width b of the battery cell is 30 mm to 140 mm, the thickness c of the battery cell is 10 mm to 60 mm, and the ratio a / b is 3.1 to 8.0, and selectively 3.3 to 8.0.

[0097] In some embodiments, the length a of the battery cell is 420 mm to 800 mm, the width b of the battery cell is 30 mm to 140 mm, the thickness c of the battery cell is 10 mm to 60 mm, and the ratio a / b is 3.1 to 8.0, and selectively 3.3 to 8.0.

[0098] This allows the battery to more favorably combine high energy density and long cycle life.

[0099] The battery cell may have a prismatic structure or a pouch-type structure, and the embodiments of this application are not limited thereto. As shown in Figures 1 to 10, the battery cell 5 provided in some embodiments of this application has a prismatic structure.

[0100] The length a and width b of the battery cell refer to the dimensions of the main body of the battery cell in the length direction X and width direction Y, and do not include the dimensions of the electrode terminals protruding from the main body of the battery cell.

[0101] The length 'a' of the battery cell can be measured using a laser thickness gauge. When measuring, 3 to 5 points can be randomly selected, and then the average value can be taken.

[0102] The width b of the battery cell can be measured using a laser thickness gauge. When measuring, 3 to 5 points can be randomly selected, and then the average value can be taken.

[0103] The thickness c of a battery cell can be measured using a laser thickness gauge. When measuring, nine points can be randomly selected, and then the average value can be taken.

[0104] The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is located between the positive and negative electrode sheets and serves to prevent internal short circuits in the battery cell.

[0105] In some embodiments, the electrode assembly may have a wound structure. For example, the positive electrode sheet, negative electrode sheet, and separator are all strip-shaped structures. In the embodiments of this application, the positive electrode sheet, separator, and negative electrode sheet may be stacked in order and wound two or more times to form the electrode assembly. In a battery cell, there may be one or more electrode assemblies housed within the outer casing. When there are multiple electrode assemblies, the multiple electrode assemblies are arranged sequentially in the thickness direction Z of the battery cell.

[0106] In some embodiments, the electrode assembly may have a laminated structure. For example, the electrode assembly includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, and the positive electrode sheets and negative electrode sheets are alternately stacked in the thickness direction Z. When the electrode assembly has a laminated structure, the battery cell can have a higher group margin, thereby further improving the energy density of the battery.

[0107] A battery cell includes an electrode assembly, an outer casing, and an electrolyte. The outer casing is for enclosing the electrode assembly and electrolyte.

[0108] In some embodiments, the outer casing may be made of pouch material or rigid case material. The pouch material may be plastic, such as one or more of aluminum plastic film, polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). The rigid case material may include, but is not limited to, a rigid plastic case, an aluminum case, or a steel case.

[0109] In some embodiments, the outer casing may be made of a hard case material.

[0110] As shown in Figures 1 to 10, the battery cell 5 includes an electrode assembly 52 and an outer casing. The electrode assembly 52 includes a main body 521 and a tab portion 522 extending from the main body 521, and the outer casing includes a case 51 and an end cover assembly 53.

[0111] As shown in Figures 3 and 10, the case 51 may be a hollow structure with one side open, and the end cover assembly 53 covers the opening of the case 51 and seals the connection to form a housing chamber for housing the electrode assembly 52 and electrolyte.

[0112] As shown in Figure 6, the exterior may include a case 51 and two end cover assemblies 53, the case 51 being a hollow structure with open ends on opposing sides, and one end cover assembly 53 correspondingly covering and sealing one opening of the case 51 to form a housing chamber for housing the electrode assembly 52 and electrolyte.

[0113] The end cover assembly 53 may include an end cover that covers the opening of the case 51. The end cover may have various structures, such as a plate-like structure or a hollow structure with one end open.

[0114] The end cover may be made of an insulating material (e.g., plastic) or a conductive material (e.g., a metallic material). If the end cover is made of a conductive material, the end cover assembly may further include an insulating member, which is located on the side of the end cover facing the electrode assembly and insulates the end cover from the electrode assembly.

[0115] The end cover assembly 53 may further include electrode terminals 531 that are attached to the end cover. There may be two electrode terminals 531, which are defined as a positive electrode terminal and a negative electrode terminal, respectively, and the positive electrode terminal and the negative electrode terminal are electrically connected to the electrode assembly 52 to output the electrical energy generated by the electrode assembly 52. ​​The positive electrode terminal and the negative electrode terminal may be located at the same end of the battery cell 5, or at opposite ends of the battery cell 5.

[0116] The electrode assembly includes a main body and tab portions extending from the main body. In some embodiments, the number of tab portions 522 may be two. The two tab portions are defined as a positive electrode tab portion and a negative electrode tab portion, respectively.

[0117] As shown in Figures 2 and 9, the two tab portions 522 (i.e., the positive electrode tab portion and the negative electrode tab portion) may extend from the same end of the main body portion 521 of the electrode assembly 52. ​​For example, the two tab portions 522 may extend from one end of the main body portion 521 of the electrode assembly 52 that is close to the end cover assembly 53.

[0118] As shown in Figures 5 and 8, the two tab portions 522 (positive electrode tab portion and negative electrode tab portion) may extend from opposite ends of the main body portion 521 of the electrode assembly 52, for example, from opposite ends of the main body portion 521 of the electrode assembly 52 in the longitudinal direction X of the battery cell. This makes it possible to make the positive electrode tab portion and the negative electrode tab portion wider (i.e., to increase the dimensions in the direction in which the non-main body portion extends), which helps to improve the electronic conductivity of the electrode sheet.

[0119] When the two tab portions 522 extend from opposite ends of the main body portion 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.

[0120] The main body 521 is the core portion that realizes the charging and discharging function of the electrode assembly 52, and the tab portion 522 is for extracting the current generated in the main body 521. The main body 521 includes the positive electrode current collector portion, positive electrode film layer of the positive electrode current collector, negative electrode current collector portion, negative electrode film layer and separator of the negative electrode current collector, etc. The positive electrode tab portion may include multiple positive electrode tabs, and the negative electrode tab portion may include multiple negative electrode tabs.

[0121] 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 soldering or the like, or it may be indirectly connected to the electrode terminal 531 via another component. For example, the electrode assembly 52 further includes a current collector for electrically connecting the electrode terminal 531 and the tab portion 522. There may be two current collectors, defined as a positive electrode current collector and a negative electrode current collector, respectively. The positive electrode current collector is for electrically connecting the positive electrode terminal and the positive tab portion, and the negative electrode current collector is for electrically connecting the negative electrode terminal and the negative tab portion. When a plurality of electrode assemblies 52 are provided in the battery cell 5, the positive electrode current collectors of the plurality of electrode assemblies 52 may be provided integrally, and the negative electrode current collectors of the plurality of electrode assemblies 52 may be provided integrally.

[0122] In some embodiments, each tab portion 522 may have a dimension of 20 mm or less in the extending direction of the main body after being bent, and more selectively 15 mm or less. This allows the electrode sheet to have a high effective dimension, improves the group margin of the battery cell, improves the mass ratio of positive electrode active material to negative electrode active material in the entire battery cell, and further allows the battery to have a high energy density.

[0123] The positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is provided on one or two of the two opposing surfaces of the positive electrode current collector.

[0124] In some embodiments, the positive electrode active material may contain both a layered lithium-containing transition metal oxide in single-crystal form and a layered lithium-containing transition metal oxide in polycrystalline form.

[0125] Single-crystal layered lithium-containing transition metal oxides generally have a small specific surface area and excellent interfacial and thermal stability, thus reducing side reactions in batteries and maintaining good particle integrity during long-term charge-discharge processes, thereby lowering the rate of battery capacity decay. Therefore, when the positive electrode active material includes single-crystal layered lithium-containing transition metal oxides, batteries can generally have a long cycle life. However, single-crystal layered lithium-containing transition metal oxides generally have a low lithium-ion diffusion coefficient, which can degrade the power characteristics of the battery. Polycrystalline layered lithium-containing transition metal oxides have a high lithium-ion diffusion coefficient, excellent electrolyte impregnation properties, and short lithium-ion diffusion pathways, which are useful for lithium-ion desorption and insertion at high current densities. Therefore, when the positive electrode active material includes both single-crystal and polycrystalline layered lithium-containing transition metal oxides, batteries can have high energy density and long cycle life while also possessing good power characteristics.

[0126] In some embodiments, in the positive electrode active material, the ratio of layered lithium-containing transition metal oxides in single-crystal form is denoted as S1, and the ratio of layered lithium-containing transition metal oxides in polycrystalline form is denoted as S2, where S1 > S2. As a result, the battery can have high energy density, long cycle life, and good power characteristics.

[0127] In some examples, the proportion of layered lithium-containing transition metal oxides in single-crystal form in the positive electrode active material is denoted as S1, where S1 is greater than 50% and selectively greater than 70%.

[0128] In some embodiments, S1 may be 70%~100%, 80%~100%, 70%~99%, 80%~99%, 70%~97%, 80%~97%, 70%~95%, or 80%~95%.

[0129] By primarily containing single-crystal layered lithium-containing transition metal oxides as the positive electrode active material, the battery can achieve a combination of high energy density, long cycle life, and good power characteristics.

[0130] In some examples, the volume distribution particle size Dv50 of the positive electrode active material may be 8 μm or less, and is selectively 2 μm to 8 μm, 2 μm to 7.2 μm, 2 μm to 5.5 μm, 3 μm to 8 μm, 3 μm to 7.2 μm, or 3 μm to 5.5 μm.

[0131] In some embodiments, the volume distribution particle size Dv90 of the positive electrode active material may be 18 μm or less, and is selectively between 3 μm and 12 μm.

[0132] By adjusting the volume distribution particle size Dv50 and / or Dv90 of the positive electrode active material within the above range, side reactions of the battery can be reduced, the rate of battery capacity decay can be decreased, and the battery can have a long cycle life and good power characteristics.

[0133] In some embodiments, the layered lithium-containing transition metal oxide may include lithium cobalt oxide, one or more ternary materials. The general formula for the ternary material is Li a Ni b Co c M d O e A fIt may also be. 0.8 ≦ a ≦ 1.2, 0 < b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, but is not limited thereto, and A includes one or more of N, F, S, and Cl, but is not limited thereto. Optionally, 0.5 ≦ b < 1, 0.8 ≦ b < 1, 0.9 ≦ b < 1. Thereby, the energy density of the battery can be further improved.

[0134] As an example, the layered lithium-containing transition metal oxide is 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 [[ID=4)]]Mn 0.02 O2, LiNi 0.85 Co 0.15 Al 0.05 O2 may include one or more of them, but is not limited thereto.

[0135] In some embodiments, the positive electrode film layer optionally further includes a positive electrode conductive agent. In the present application, the type of the positive electrode conductive agent is not particularly limited. In some embodiments, as an example, 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.

[0136] In some embodiments, the positive electrode film layer further selectively comprises a positive electrode binder. The type of positive electrode binder is not particularly limited in this application. In some embodiments, for example, the positive electrode binder may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0137] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of metal foil, aluminum foil may be used. The composite current collector may include a polymer material substrate layer and a metal material layer formed on at least one surface of the polymer material substrate layer. As an example, the metal material may include one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer material substrate layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0138] The positive electrode film layer is generally obtained by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing a positive electrode active material, positive electrode binder, positive electrode conductive agent, etc., in a solvent and stirring it uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0139] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer containing a negative electrode active material.

[0140] The negative electrode current collector has two opposing surfaces in the thickness direction of itself, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0141] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymer material substrate layer and a metal material layer formed on at least one surface of the polymer material substrate layer. For example, the metal material may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material substrate layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0142] In some embodiments, the negative electrode active material may include a carbon material. Selectively, the carbon material may include one or more of artificial graphite and natural graphite.

[0143] In some embodiments, the negative electrode active material may include a silicon-based material. This can improve 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 materials.

[0144] In some embodiments, the silicon-based material may contain silicon and one or more alkali metal elements and alkaline earth metal elements. Selectively, the alkali metal element may include Li. Selectively, the alkaline earth metal element may include Mg. For example, the silicon-based material may be a silicon-based material with alkali metals and / or alkaline earth metals pre-inserted, for example, a silicon-based material with Li and / or Mg pre-inserted.

[0145] In some embodiments, the mass percentage of silicon-based material in the negative electrode active material may be 5% or more, and is selectively between 8% and 20%.

[0146] In some embodiments, the negative electrode active material may include a carbon material and a silicon-based material, with the mass proportion of the silicon-based material in the negative electrode active material being 8% to 20%, and the mass proportion of the carbon material being 80% or more. This allows the battery to have both high energy density and long cycle life.

[0147] In some embodiments, the volume distribution particle size Dv10 of the negative electrode active material may be 4 μm to 8 μm, and is selectively 4.5 μm to 6.5 μm.

[0148] In some examples, the volume distribution particle size Dv50 of the negative electrode active material may be 6 μm to 15 μm, and is selectively 8 μm to 13 μm.

[0149] In some examples, the volume distribution particle size Dv90 of the negative electrode active material may be 15 μm to 30 μm, and is selectively 18 μm to 25 μm.

[0150] By adjusting the volume distribution particle size Dv10, Dv50 and / or Dv90 of the negative electrode active material within the above range, side reactions of the battery can be reduced, and the battery can have a long cycle life and even better power characteristics.

[0151] In some embodiments, the negative electrode film layer may further contain a negative electrode binder, for example, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic acid resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS), but the embodiments of this application are not limited thereto.

[0152] In some embodiments, the negative electrode film layer further selectively comprises a negative electrode conductive agent. The type of negative electrode conductive agent is not particularly limited in this application, and 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.

[0153] In some embodiments, the negative electrode film layer selectively further comprises other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, etc.

[0154] The negative electrode sheet does not exclude other additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may further include a conductive undercoat 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 provided on the surface of the negative electrode current collector. In some embodiments, the negative electrode sheet may further include a protective layer covering the surface of the negative electrode film layer.

[0155] The negative electrode sheet may be manufactured according to the following method: A negative electrode active material, an optional negative electrode binder, an optional negative electrode conductive agent, and any other auxiliary agent are dispersed in a solvent and uniformly stirred to form a negative electrode slurry; the negative electrode slurry is applied to a negative electrode current collector; and a negative electrode sheet is formed through processes such as drying and cold pressing. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0156] In some embodiments, the negative electrode sheet may have other structures. Figure 11 is a schematic diagram of the structure of a negative electrode sheet provided in some embodiments of this application. Figure 12 is a schematic diagram of the structure of a negative electrode sheet provided in another embodiment of this application. Figure 13 is a schematic diagram of the structure of a negative electrode sheet provided in yet another embodiment of this application.

[0157] As shown in Figures 11 to 13, the negative electrode sheet 10 includes a negative electrode current collector 101 and a negative electrode film layer 102 provided on at least one surface of the negative electrode current collector 101. The negative electrode film layer 102 contains a negative electrode active material, and the negative electrode film layer 102 has a first surface 102a away from the negative electrode current collector 101 and a second surface 102b facing the first surface 102a. The thickness of the negative electrode film layer 102 is denoted as H.

[0158] The thickness H of the negative electrode film layer is the thickness of the negative electrode film layer located on one side of the negative electrode current collector.

[0159] The region within a thickness range of 0.3H from the first surface 102a of the negative electrode film layer 102 is denoted as the first region 1021 of the negative electrode film layer 102, and the region within a thickness range of 0.3H from the second surface 102b of the negative electrode film layer 102 is denoted as the second region 1022 of the negative electrode film layer 102.

[0160] The first region 1021 contains a first negative electrode active material, the second region 1022 contains a second negative electrode active material, the first negative electrode active material contains a first carbon material, the second negative electrode active material contains a second carbon material, and the volume-distributed particle size Dv50 of the first carbon material is smaller than the volume-distributed particle size Dv50 of the second carbon material.

[0161] The large length of the battery cells provided in the embodiments of this application contributes to the high energy density of the battery, but affects the power characteristics of the battery. By adjusting the structure of the negative electrode film layer on one side of the negative electrode current collector and applying it separately, the battery can have good power characteristics. By having the first carbon material in direct contact with the electrolyte and making the volume distribution particle size Dv50 of the first carbon material smaller than that of the second carbon material, the first region of the negative electrode film layer can have a relatively large number of ion insertion pathways, which helps to speed up the movement of ions to the second carbon material. As a result, the battery can have good power characteristics while also having high energy density and long cycle life.

[0162] In some embodiments, the specific surface area of ​​the first carbon material may be smaller than that of the second carbon material. By having the first carbon material in direct contact with the electrolyte and making its specific surface area smaller than that of the second carbon material, it helps to reduce side reactions in the battery, thus contributing to the battery having more favorable cycle characteristics.

[0163] In some embodiments, the degree of graphitization of the first carbon material may be lower than that of the second carbon material. Because the degree of graphitization of the first carbon material is lower, its interlayer distance is larger, which facilitates rapid ion insertion and deinsertion. Therefore, adjusting the degree of graphitization of the first carbon material to be lower than that of the second carbon material helps to improve the power characteristics of the battery.

[0164] In some embodiments, the first carbon material may include artificial graphite. Including artificial graphite in the first carbon material helps reduce side reactions in the battery, thus contributing to the battery having more favorable cycle characteristics.

[0165] In some embodiments, the secondary carbon material may contain natural graphite. Natural graphite has high surface activity, and the inclusion of natural graphite in the secondary carbon material helps to improve the power characteristics of the battery.

[0166] In some embodiments, the first negative electrode active material may include a carbon material and a silicon-based material. Compared to a pure carbon material, when the first negative electrode active material includes a carbon material and a silicon-based material, the battery can have a higher energy density under the same surface density conditions.

[0167] In some embodiments, the second negative electrode active material may include a carbon material and a silicon-based material. Compared to a pure carbon material, when the second negative electrode active material includes a carbon material and a silicon-based material, the battery can have a higher energy density under the same surface density conditions.

[0168] In some embodiments, both the first and second negative electrode active materials may contain both a carbon material and a silicon-based material. This allows the battery to have a higher energy density.

[0169] In some embodiments, both the first negative electrode active material and the second negative electrode active material contain both a carbon material and a silicon-based material.

[0170] As shown in Figures 11 to 13, the negative electrode film layer 102 further includes an intermediate 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 (where H represents the thickness of the negative electrode film layer 102).

[0171] 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 Figure 11, the intermediate region 1023 includes both the first and second negative electrode active materials, in which 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, and the two layer structures may further have a layer interface. Alternatively, as shown in Figure 12, the intermediate region 1023 may have the same composition as the first region 1021, and therefore the distribution region of the first negative electrode active material in the thickness direction of the negative electrode film layer 102 is within a thickness range from the first surface 102a of the negative electrode film layer to 0.7H. Alternatively, as shown in Figure 13, the intermediate region 1023 may have the same composition as the second region 1022. Therefore, the distribution region of the second negative electrode active material in the thickness direction of the negative electrode film layer 102 is within the thickness range from the second surface 102b of the negative electrode film layer to 0.7H.

[0172] In some embodiments, the first region, second region, and intermediate region of the negative electrode film layer selectively further comprise a negative electrode conductive agent and / or a negative electrode binder.

[0173] The negative electrode sheet may be manufactured according to the following method: Provide 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; apply the second negative electrode slurry to a negative electrode current collector; apply the first negative electrode slurry to the second negative electrode slurry; and after drying and cold pressing, a negative electrode sheet is obtained.

[0174] In some embodiments, the first negative electrode active material, a selective conductive agent, a selective binder, and other selective auxiliary agents may be dispersed in a solvent (e.g., deionized water) to form the first negative electrode slurry.

[0175] In some embodiments, a second negative electrode slurry may be formed by dispersing a second negative electrode active material, a selective conductive agent, a selective binder, and other selective auxiliary agents in a solvent (e.g., deionized water).

[0176] The first negative electrode slurry and the second negative electrode slurry may be applied simultaneously in one step or in two separate steps. In some embodiments, the first negative electrode slurry and the second negative electrode slurry are applied simultaneously in one step. Applying them simultaneously in one step can reduce the resistance of the negative electrode film layer, further improving the power characteristics and cycle characteristics of the battery.

[0177] The application weights of the first and second negative electrode slurries can be adjusted according to the actual conditions.

[0178] The first negative electrode active material, the second negative electrode active material, etc., mentioned above can be purchased from the market.

[0179] The battery cell further contains an electrolyte. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. In some embodiments, an electrolyte solution is used as the electrolyte, and the electrolyte solution contains an electrolyte salt and a solvent.

[0180] The type of electrolyte salt is not specifically limited and can be selected according to actual demand. In some examples, the electrolyte salt may include one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bisoxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0181] The type of solvent is not specifically limited and can be selected according to actual needs. In some examples, the solvent may include one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl 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), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0182] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and further additives that can improve some characteristic of the battery, such as additives that improve the overcharge characteristics of the battery, additives that improve the high-temperature characteristics of the battery, and additives that improve the low-temperature power characteristics of the battery.

[0183] The battery cell may further include a separator. The separator may be placed between the positive electrode sheet and the negative electrode sheet and primarily serves to prevent internal short circuits. In this application, the type of separator is not particularly limited, and any known porous structure membrane having good chemical and mechanical stability can be selected.

[0184] In some embodiments, the separator material may include one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different.

[0185] The method for manufacturing battery cells is known. In some embodiments, a battery cell may be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, the positive electrode sheet, separator, and negative electrode sheet may be formed into an electrode assembly by a winding process and / or a lamination process, the electrode assembly may be placed in an outer casing, the electrolyte may be injected after oven drying, and a battery cell may be obtained through processes such as vacuum packaging, standing, and chemical conversion. Multiple battery cells may be further assembled into a battery module by series connection, parallel connection, or mixed connection. Multiple battery modules may be further connected in series, parallel connection, or mixed connection to form a battery pack. In some embodiments, multiple battery cells may be directly assembled into a battery pack.

[0186] Embodiments of this application further provide an electrical device including a battery provided in embodiments of this application. The battery may serve as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, tablet computers, laptop computers, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships and satellites, energy storage systems, etc.

[0187] Electrical devices can select the type of battery, such as a battery cell, battery module, or battery pack, according to their usage needs.

[0188] Figure 14 is a schematic diagram of an example electrical device. This electrical device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the requirements for high power and high energy density, the electrical device may use a battery pack or battery module.

[0189] Other examples of electrical devices may include mobile phones, tablet computers, and laptop computers. These electrical devices are typically required to be lightweight and thin, and may use battery cells as a power source. Examples

[0190] The following examples further illustrate the disclosures of this application, but these examples are for interpretation only, as it is obvious to those skilled in the art that various modifications and changes can be made within the scope of the disclosures of this application. Unless otherwise noted, all parts, percentages and ratios reported in the following examples are by weight, and all reagents used in the examples are either commercially available or obtained by conventional methods and can be used as is without further processing, and all equipment used in the examples is commercially available. The batteries in Examples 1-14 and Comparative Examples 1-2 were all manufactured using the following method.

[0191] Table 1 shows the positive electrode active material LiNi 0.9 Co 0.06 Mn 0.04 O2, the conductive agent Super P, and the binder polyvinylidene fluoride were mixed in a weight ratio of 96.5:1.5:2, an appropriate amount of solvent NMP was added, and the mixture was uniformly stirred to obtain a positive electrode slurry. The positive electrode slurry was applied to two surfaces of the positive electrode current collector aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet. Positive electrode active material LiNi 0.9 Co 0.06 Mn 0.04 The O2 was in single-crystal form, and the proportion of single-crystal particles was over 98%.

[0192] The negative electrode slurry was obtained by thoroughly mixing the negative electrode active material graphite, the conductive agent Super P, the binder styrene-butadiene rubber, and the thickener sodium carboxymethylcellulose in a weight ratio of 96.2:0.8:1.8:1.2 in an appropriate amount of deionized water solvent. The negative electrode slurry was applied to two surfaces of the negative electrode current collector copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0193] Ethylene carbonate (EC), ethylmethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a 1:1:1 volume ratio to obtain an organic solvent. Then, LiPF6 was dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0194] A PP film was used as a separator and assembled together with the positive and negative electrode sheets manufactured above to obtain a laminated electrode assembly. The electrode assembly was placed in a hard case, dried, and then injected with electrolyte. After vacuum packaging, settling, and chemical conversion processes, the battery shown in Figure 4 was 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.

[0195] In Table 1, the length of the battery is denoted as a, the width as b, and the thickness as c. The length direction X, width direction Y, and thickness direction Z of the battery are perpendicular to each other in pairs, and the thickness direction Z is the stacking direction of the positive electrode sheet and the negative electrode sheet.

[0196] The coating surface density and pressure density of the positive electrode sheet and the negative electrode sheet were the same in each of the above examples and comparative examples. Performance measurement

[0197] (1) Measurement of the energy density of a battery At 25°C, the batteries manufactured as described above were charged with a constant current of 0.33C up to 4.3V, then charged with a constant voltage until the current reached 0.05C, left to stand for 5 minutes, and then discharged with a constant current of 0.33C up to 2.8V to obtain the discharge energy Q. The energy density of a battery (Wh / L) = discharge energy Q / battery volume V.

[0198] (2) Measurement of battery cycle characteristics At 25°C, the batteries manufactured as described above were charged with a constant current of 1C to 4.3V, then charged with a constant voltage until the current dropped to 0.05C, left to stand for 5 minutes, and then discharged with a constant current of 1C to 2.8V. The discharge capacity at this time was recorded, which was defined as the discharge capacity of the first cycle. The battery's cycle charge and discharge measurements were performed according to the above method until the battery's capacity decreased to 80% of the discharge capacity of the first cycle, and the number of battery cycles was recorded.

[0199] (3) Measurement of the power characteristics of the battery At 25°C, the batteries manufactured as described above were charged with a constant current of 1C to 4.3V, then charged with a constant voltage until the current reached 0.05C, left to stand for 5 minutes, then discharged at 1C for 30 minutes to adjust the SOC to 50%, the voltage U1 before discharge was recorded, and then discharged at a constant current of 3C for 30 seconds, and the voltage U2 after discharge was recorded. The battery power W = lower limit cutoff voltage × (U1 - lower limit cutoff voltage) / (U1 - U2) / 3C. The lower limit cutoff voltage was 2.8V.

[0200] [Table 1]

[0201] As can be seen from the measurement results in Table 1, by including a layered lithium-containing transition metal oxide in single-crystal form as the positive electrode active material, and by setting the battery length a to 180 mm or more, and the ratio of battery length a to battery width b a / b to 2.0 to 10.5, the battery can have both high energy density and long cycle life.

[0202] When the battery length a is less than 180 mm, the ratio of battery length a to battery width b (a / b) is less than 2.0, or the ratio of battery length a to battery width b (a / b) is greater than 10.5, it is difficult to meet the usage needs of batteries that require both long cycle life and high energy density.

[0203] As can be seen from the measurement results in Table 1, the overall performance of the battery can be further improved by further adjusting the battery length a and the ratio a / b between the battery length a and the battery width b.

[0204] [Table 2]

[0205] As can be seen from the measurement results in Table 2, by further adjusting the battery length a and the ratio a / b (the ratio of battery length a to battery width b), the battery can have good power characteristics. Examples 15-17

[0206] The battery manufacturing method is similar to that of Example 4, but the positive electrode active material is LiNi in single crystal form. 0.9 Co 0.06 Mn 0.04 O2 and polycrystalline LiNi 0.9 Co 0.06 Mn 0.04 They differ in that they both contain O2; see Table 3 for details on the proportion of each number.

[0207] [Table 3]

[0208] As can be seen from the measurement results in Table 3, by increasing the proportion of single-crystal layered lithium-containing transition metal oxides in the positive electrode active material to more than 50%, the battery can more favorably combine high energy density, long cycle life, and good power characteristics.

[0209] In each of the above examples, the layered lithium-containing transition metal oxides in single-crystal and polycrystalline forms are all LiNi 0.9 Co 0.06 Mn 0.04 Although O2 was used in the examples of this application, the layered lithium-containing transition metal oxides are not limited to this, and all other layered lithium-containing transition metal oxides have similar effects. Example 18

[0210] The battery manufacturing method is similar to that of Example 5, but the difference lies in the manufacturing process of the negative electrode sheet.

[0211] The first negative electrode slurry was obtained by thoroughly mixing the first carbon material (artificial graphite), the conductive agent Super P, the binder (styrene-butadiene rubber), and the thickener (carboxymethylcellulose sodium) in a weight ratio of 96.2:0.8:1.8:1.2 with an appropriate amount of deionized water solvent. The second negative electrode slurry was obtained by thoroughly mixing the second carbon material (artificial graphite), the conductive agent Super P, the binder (styrene-butadiene rubber), and the thickener (carboxymethylcellulose sodium) in a weight ratio of 96.2:0.8:1.8:1.2 with an appropriate amount of deionized water solvent.

[0212] The second negative electrode slurry was applied to two surfaces of the copper foil of the negative electrode current collector, and the first negative electrode slurry was applied to the second negative electrode slurry. The slurry-coated negative electrode current collector was dried at room temperature, then moved to an oven for drying, and then cold-pressed and cut to obtain a negative electrode sheet. The ratio of the coating thickness of the first negative electrode slurry to the coating thickness of the second negative electrode slurry was 5:5. The thickness of the negative electrode sheet was the same as in Example 5. The volume distribution particle size Dv50 of the artificial graphite of the first carbon material was 9.5 μm, and the volume distribution particle size Dv50 of the artificial graphite of the second carbon material was 12 μm. Example 19

[0213] The battery manufacturing method is similar to that of Example 5, but the difference lies in the manufacturing process of the negative electrode sheet.

[0214] The first negative electrode slurry was obtained by thoroughly mixing the first carbon material (artificial graphite), the conductive agent Super P, the binder (styrene-butadiene rubber), and the thickener (carboxymethylcellulose sodium) in a weight ratio of 96.2:0.8:1.8:1.2 with an appropriate amount of deionized water solvent. The second negative electrode slurry was obtained by thoroughly mixing the second carbon material (artificial graphite), the conductive agent Super P, the binder (styrene-butadiene rubber), and the thickener (carboxymethylcellulose sodium) in a weight ratio of 96.2:0.8:1.8:1.2 with an appropriate amount of deionized water solvent.

[0215] The second negative electrode slurry was applied to two surfaces of the copper foil of the negative electrode current collector, and the first negative electrode slurry was applied to the second negative electrode slurry. The slurry-coated negative electrode current collector was dried at room temperature, then moved to an oven for drying, and then cold-pressed and cut to obtain a negative electrode sheet. The ratio of the coating thickness of the first negative electrode slurry to the coating thickness of the second negative electrode slurry was 5:5. The thickness of the negative electrode sheet was the same as in Example 5. The volume distribution particle size Dv50 of the artificial graphite of the first carbon material was 14 μm, and the volume distribution particle size Dv50 of the artificial graphite of the second carbon material was 12 μm. Example 20

[0216] The battery manufacturing method is similar to that of Example 5, but the difference lies in the manufacturing process of the negative electrode sheet.

[0217] The first negative electrode slurry was obtained by thoroughly mixing the first carbon material (artificial graphite), the conductive agent Super P, the binder (styrene-butadiene rubber), and the thickener (carboxymethylcellulose sodium) in a weight ratio of 96.2:0.8:1.8:1.2 with an appropriate amount of deionized water solvent. The second negative electrode slurry was obtained by thoroughly mixing the second carbon material (natural graphite), the conductive agent Super P, the binder (styrene-butadiene rubber), and the thickener (carboxymethylcellulose sodium) in a weight ratio of 96.2:0.8:1.8:1.2 with an appropriate amount of deionized water solvent.

[0218] The second negative electrode slurry was applied to two surfaces of the copper foil of the negative electrode current collector, and the first negative electrode slurry was applied to the second negative electrode slurry. The slurry-coated negative electrode current collector was dried at room temperature, then moved to an oven for drying, and then cold-pressed and cut to obtain a negative electrode sheet. The ratio of the coating thickness of the first negative electrode slurry to the coating thickness of the second negative electrode slurry was 5:5. The thickness of the negative electrode sheet was the same as in Example 5. The volume distribution particle size Dv50 of the artificial graphite of the first carbon material was 12 μm, and the volume distribution particle size Dv50 of the natural graphite of the second carbon material was 14 μm.

[0219] [Table 4]

[0220] As can be seen from the measurement results of Examples 4, 18, and 19, 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 that of the second carbon material, the first region of the negative electrode film layer can have a relatively large number of ion insertion paths, which helps to speed up the movement of ions to the second carbon material. As a result, the battery can have a long cycle life while also having better power characteristics.

[0221] As can be further seen from the measurement results in Table 4, by adjusting the structure of the negative electrode film layer on one side of the negative electrode current collector, using artificial graphite as the first carbon material and natural graphite as the second carbon material, the battery can have better power characteristics.

[0222] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are merely illustrative, and all embodiments having substantially the same technical idea and achieving the same function and effect within the scope of the technical solutions of this application are included in the technical scope of this application. Furthermore, other forms that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included in the scope of this application, without departing from the gist of this application. [Explanation of Symbols]

[0223] 5 battery cells 51 cases 52 Electrode assembly 521 Main body 522 Tab section 53 End cover assembly 531 Electrode terminal 10 Negative electrode sheets 101 Negative electrode current collector 102 Negative electrode film layer 1021 1st area 1022 Second area 1023 Intermediate area 102a 1st surface 102b 2nd surface X-length direction Y width direction Z-axis thickness direction

Claims

1. A battery cell including an electrode assembly and an outer casing, The electrode assembly includes a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material comprising a layered lithium-containing transition metal oxide in single-crystal form. 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. A battery cell in which the length of the battery cell is denoted as a and the width of the battery cell is denoted as b, where a is 180 mm or more and a / b is between 2.0 and 10.

5.

2. The battery cell according to claim 1, wherein a is 190 mm to 1200 mm, and selectively 250 mm to 1200 mm.

3. A battery cell according to any one of claims 1 to 2, wherein a is 350 mm to 1200 mm, and / or a / b is 3.1 to 10.5 mm.

4. A battery cell according to any one of claims 1 to 2, wherein a is 250 mm to 800 mm, and / or a / b is 2.5 to 8.

0.

5. A battery cell according to any one of claims 1 to 4, wherein a is 350 mm to 800 mm, selectively 420 mm to 800 mm, and / or a / b is 3.1 to 8.0, selectively 3.3 to 8.

0.

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

7. The battery cell according to any one of claims 1 to 6, wherein the thickness of the battery cell is denoted as c, and c is 70 mm or less, and selectively between 10 mm and 60 mm.

8. The outer casing is made of pouch material or hard case material, and / or The battery cell according to any one of claims 1 to 7, wherein the electrode assembly has a laminated structure or a wound structure, and is selectively a laminated structure.

9. The electrode assembly includes a main body and a tab portion extending from the main body. The tab portion, after being folded, has a dimension of 20 mm or less in the extending direction of the main body, selectively 15 mm or less, and / or The battery cell according to any one of claims 1 to 8, wherein the tab portion includes a positive electrode tab portion and a negative electrode tab portion, and the positive electrode tab portion and the negative electrode tab 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 simultaneously comprises a layered lithium-containing transition metal oxide in single-crystal form and a layered lithium-containing transition metal oxide in polycrystalline form.

11. The battery cell according to claim 10, wherein in the positive electrode active material, S1 is the ratio of the number of layered lithium-containing transition metal oxides in single-crystal form, and S2 is the ratio of the number of layered lithium-containing transition metal oxides in polycrystalline form, and S1 > S2.

12. The battery cell according to any one of claims 1 to 11, wherein the proportion of the number of layered lithium-containing transition metal oxides in single-crystal form in the positive electrode active material is denoted as S1, and S1 is 70% or more, and selectively 80% to 99%.

13. The volume distribution particle size Dv50 of the positive electrode active material is 8 μm or less, selectively between 2 μm and 5.5 μm, and / or The battery cell according to any one of claims 1 to 12, wherein the volume distribution particle size Dv90 of the positive electrode active material is 18 μm or less, and selectively 3 μm to 12 μm.

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

15. The electrode assembly includes a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material including a silicon-based material. Selectively, the silicon-based material comprises a silicon element and one or more alkali metal elements and alkaline earth metal elements, and / or The battery cell according to any one of claims 1 to 14, wherein selectively, the mass percentage of the silicon-based material in the negative electrode active material is 5% or more, and more selectively, 8% to 20%.

16. The aforementioned negative electrode active material is (1) The volume distribution particle size Dv10 of the negative electrode active material is 4 μm to 8 μm, and selectively 4.5 μm to 6.5 μm, (2) The volume distribution particle size Dv50 of the negative electrode active material is 6 μm to 15 μm, and selectively 8 μm to 13 μm, (3) The battery cell according to any one of claims 14 to 15, wherein the volume distribution particle size Dv90 of the negative electrode active material is 15 μm to 30 μm, and selectively 18 μm to 25 μm.

17. The electrode assembly includes a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode film layer having a first surface away from the negative electrode current collector and a second surface provided opposite to the first surface, the thickness of the negative electrode film layer is denoted as H, the region within a thickness range from the first surface of the negative electrode film layer to 0.3H is denoted as the first region of the negative electrode film layer, the region within a thickness range from the second surface of the negative electrode film layer to 0.3H is denoted as the second region of the negative electrode film layer, the first region comprising a first negative electrode active material, the second region comprising a second negative electrode active material, the first negative electrode active material comprising a first carbon material, the second negative electrode active material comprising a second carbon material, and the volume-distributed particle size Dv50 of the first carbon material being smaller than the volume-distributed particle size Dv50 of the second carbon material, according to any one of claims 1 to 13.

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

19. The first carbon material contains artificial graphite and / or, The battery cell according to any one of claims 17 to 18, wherein the second carbon material contains 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 comprises a silicon-based material, and selectively, both the first negative electrode active material and the second negative electrode active material comprise a silicon-based material.

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

22. An electrical device comprising the battery described in claim 21.

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