Battery cell, battery device and electrical device

Abstract

The present application provides a battery cell, a battery device and an electrical device. In the battery cell of the present application, the areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 ; along the first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of PCT patent application PCT / CN2024 / 116576 titled "Battery Cell, Battery Device and Electrical Device" filed on September 3, 2024, and the entire content of this application is incorporated herein by reference. Technical Field

[0003] This application relates to the technical field of batteries, and particularly to a battery cell, a battery device and an electrical device. Background Art

[0004] In recent years, batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the popularization of battery applications, higher requirements have also been put forward for their energy density, fast charging performance, cycle performance, service life, safety performance, etc. Summary of the Invention

[0005] The purpose of this application is to provide a new type of battery cell, which has excellent energy density, fast charging performance, cycle performance, and can also take into account a relatively low DC internal resistance.

[0006] To achieve the above purpose, a first aspect of this application provides a battery cell, including a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive current collector and a positive electrode film layer provided on at least one side of the positive current collector. The negative electrode plate includes a negative current collector and a negative electrode film layer provided on at least one side of the negative current collector. Among them, the positive electrode film layer includes a positive active material, and the positive active material includes lithium-containing phosphate. The areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 ; the positive current collector includes a positive current collecting part and at least two positive electrode tabs provided on the same side of the positive current collecting part. The positive electrode tabs extend from the positive current collecting part along a first direction; the negative current collector includes a negative current collecting part and at least two negative electrode tabs provided on the same side of the negative current collecting part. The negative electrode tabs extend from the negative current collecting part along the first direction; along the first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

[0007] The formation of lithium dendrites is closely related to the capacity design of the positive and negative electrode sheets. In this application, by reasonably controlling the film areal density of the positive and negative electrode sheets within a reasonable range, the current density in the positive and negative electrode films becomes more uniform, effectively solving the problem of large-area lithium deposition on the negative electrode sheet. Furthermore, as the charging rate of the battery cell increases, since the root position of the tab is an electron aggregation area, the negative electrode film near the root of the tab is more likely to generate lithium dendrites. On the basis of reasonably controlling the areal density of the positive and negative electrode films, by further reasonably controlling the difference between the size W2 of the negative electrode film and the size W1 of the positive electrode film as described above, the problem of lithium deposition near the root of the tab on the negative electrode sheet can be further improved, thereby enabling the battery to have excellent fast charging performance and cycling performance.

[0008] In any embodiment, the areal density of the single-sided positive electrode film is 0.335 g / 1540.25mm 2 to 0.38 g / 1540.25mm 2 and the areal density of the single-sided negative electrode film is 0.15 g / 1540.25mm 2 to 0.165 g / 1540.25mm 2 .

[0009] In the battery cell provided by this application, when the coating areal density of the positive and negative electrode films is within the above range, it can further balance the improvement of the energy density and fast charging performance of the battery.

[0010] In any embodiment, the tap density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 .

[0011] In any embodiment, the tap density of the positive electrode sheet is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0012] When the tap density of the positive electrode sheet is within the above range, it can further improve the energy density of the battery while ensuring the kinetic performance.

[0013] In any embodiment, the tap density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

[0014] In any embodiment, the tap density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

[0015] When the compaction density of the negative electrode sheet is within the above range, the energy density of the battery can be further improved while ensuring the dynamic performance.

[0016] In any embodiment, the negative electrode film layer includes a negative electrode active material, the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, and the negative electrode active material includes graphite.

[0017] In any embodiment, the average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm.

[0018] In the battery cell provided in the present application, when the graphite as the negative electrode active material has a particle size within the above range, the fast charging performance of the battery can be further improved, and the DC internal resistance of the battery cell can also be improved, thereby reducing the heat generation of the battery.

[0019] In any embodiment, the graphitization degree of the negative electrode active material is 90% to 95%.

[0020] In any embodiment, the graphitization degree of the negative electrode active material is 92%-95%.

[0021] When the degree of graphitization of the negative electrode active material is within the above range, the capacity can be further improved.

[0022] In any embodiment, the negative electrode film layer includes a first negative electrode active material layer arranged on the surface of the negative electrode current collector and a second negative electrode active material layer arranged on the side of the first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer includes a first artificial graphite, the negative electrode active material in the second negative electrode active material layer includes a second artificial graphite, and the average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

[0023] In any embodiment, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

[0024] In any embodiment, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

[0025] In any embodiment, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

[0026] In the battery cell provided in the present application, when the above-mentioned double-layer coating scheme is adopted in the negative electrode film layer, the dynamic performance of the battery can be further improved.

[0027] In any embodiment, the thickness of the negative electrode current collector is 4-6 μm.

[0028] In any embodiment, the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20.

[0029] In any embodiment, the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

[0030] In the battery cell provided by the present application, when the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is within the above range, the energy density and fast charging performance of the battery can be further balanced.

[0031] In any embodiment, the battery cell includes an electrolyte, the electrolyte contains an organic solvent, and the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0032] In the battery cell provided by the present application, when the above types of organic solvents are used in the electrolyte, the kinetic performance of the battery can be further improved.

[0033] In any embodiment, the organic solvent includes a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester is 40% to 75% based on the total mass of the electrolyte.

[0034] In any embodiment, the linear carboxylic acid ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include one or more of C1-C5 alkyl groups and C1-C5 haloalkyl groups.

[0035] In any embodiment, the linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

[0036] When the above types and mass ratios of linear carboxylic acid esters are used as organic solvents in the electrolyte, due to the low viscosity of the linear carboxylic acid esters, they can effectively increase the electrolyte conductivity, thereby further improving the fast charging performance of the battery.

[0037] In any embodiment, the organic solvent includes a carbonate solvent, the carbonate solvent includes a linear carbonate and a cyclic carbonate, and based on the total mass of the electrolyte, the mass ratio of the linear carbonate is 10% to 40%.

[0038] In any embodiment, the cyclic carbonate includes one or more of ethylene carbonate and propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0039] In any embodiment, the linear carbonate includes dimethyl carbonate, and based on the total mass of the electrolyte, the mass ratio of dimethyl carbonate is 5% to 15%.

[0040] When the carbonate of the above type and mass ratio is used as the organic solvent in the electrolyte, the side reactions and gas generation degree during the cycling of the battery can be improved, so that the battery can have good cycling performance at the same time.

[0041] In any embodiment, the electrolyte includes dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.0.

[0042] In any embodiment, the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.0.

[0043] When dimethyl carbonate and a linear carboxylic acid ester with the above mass ratio are simultaneously used as the organic solvent in the electrolyte, through the combination of the two solvents, the fast charging performance and cycling performance of the battery can be further improved simultaneously.

[0044] In any embodiment, the electrolyte includes a lithium salt, and based on the total mass of the electrolyte, the mass ratio of the lithium salt is 13% to 20%.

[0045] In any embodiment, the lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorosulfonylimide salts, and the fluorosulfonylimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0046] Lithium hexafluorophosphate is not easy to generate gas during cycling, which can further improve the cycling performance of the battery; while the fluorosulfonylimide salt has strong dissociation ability, which can further improve the fast charging performance of the battery.

[0047] In any embodiment, the lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0048] In any embodiment, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:1.

[0049] When lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide with the above mass ratio range are simultaneously used in the electrolyte, the fast charging performance and cycling performance of the battery can be further improved simultaneously.

[0050] In any embodiment, the electrolyte further contains an additive, and the additive contains a carbonate additive.

[0051] In any embodiment, based on the total mass of the electrolyte, the mass ratio of the carbonate additive in the electrolyte is 0.5% to 7%.

[0052] In any embodiment, the carbonate additive includes vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0053] In the battery cell provided by the present application, a carbonate additive within the above mass ratio range is further added to the electrolyte. For example, fluoroethylene carbonate and vinylene carbonate can form a SEI film on the surface of the negative electrode, thereby reducing the side reactions occurring between the electrode sheet and the electrolyte, and further enabling the battery to have better cycle performance.

[0054] In any embodiment, the additive includes vinylene carbonate (VC); based on the total mass of the electrolyte, the mass ratio of vinylene carbonate (VC) in the electrolyte is 0.5% to 2%.

[0055] When vinylene carbonate within the above mass ratio range is added as an additive to the electrolyte, the formed SEI film is relatively stable, which is beneficial to further improving the cycle performance of the battery.

[0056] In any embodiment, the additive includes fluoroethylene carbonate (FEC); based on the total mass of the electrolyte, the mass ratio of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 1%.

[0057] When fluoroethylene carbonate within the above mass ratio range is added as an additive to the electrolyte, the formed SEI film has a low impedance, which can further improve the fast charging performance of the battery.

[0058] In any embodiment, the lithium-containing phosphate has a general formula as shown in Formula I,

[0059] Li x A y Me a M b P 1-c X c Y z Formula I,

[0060] where 0.1 ≤ x ≤ 1.3, 0 ≤ y ≤ 1.3, and 0.9 ≤ x + y ≤ 1.3; 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5; 0 ≤ c ≤ 0.5; 3 ≤ z ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

[0061] When the lithium-containing phosphate as the positive electrode active material has the above chemical general formula, the energy density of the battery can be further improved.

[0062] In any embodiment, M includes one or more of Al, Ti, V, and Mg.

[0063] In any embodiment, the positive electrode active material satisfies at least one of the following:

[0064] (1) The positive electrode active material contains Al element, and the mass content is 0.01% to 0.05% based on the total mass of the positive electrode active material;

[0065] (2) The positive electrode active material contains Ti element, and the mass content is 0.01% to 0.03% based on the total mass of the positive electrode active material;

[0066] (3) The positive electrode active material contains V element, and the mass content is 0.1% to 0.3% based on the total mass of the positive electrode active material;

[0067] (4) The positive electrode active material contains Mg element, and the mass content is 0.001% to 0.01% based on the total mass of the positive electrode active material.

[0068] When the lithium-containing phosphate as the positive electrode active material contains elements such as Al, Ti, and V, its specific capacity can be further improved.

[0069] In any embodiment, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate includes first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm.

[0070] In the battery cell provided by the present application, when the positive electrode active material includes lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm, it can further improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have excellent safety performance.

[0071] In the battery cell provided by the present application, when the lithium-containing phosphate as the positive electrode active material contains both first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, the compaction density of the electrode sheet is improved by the method of particle size grading, thereby further enhancing the energy density of the battery.

[0072] In any embodiment, in the cross-section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0073] Among lithium-containing phosphates as the positive electrode active material, when the number of first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm is greater than the number of second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, it is possible to further balance the improvement of the DC internal resistance and fast charging performance of the battery.

[0074] In any embodiment, the distance between the centerlines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the centerlines are parallel to the first direction; and / or,

[0075] The distance between the centerlines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the centerlines are parallel to the first direction.

[0076] In any embodiment, the distance between the centerlines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or,

[0077] The distance between the centerlines of two adjacent negative electrode tabs is 20 mm to 330 mm.

[0078] In the battery cell provided by the present application, when the positive and negative current collectors include at least two tabs with the above structural characteristics, it can further improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have better safety performance.

[0079] In any embodiment, the battery cell further includes a top cover, and the top cover includes a positive electrode terminal and a negative electrode terminal with opposite polarities. The positive electrode terminal and the negative electrode terminal are respectively used for electrically connecting with the positive electrode tab and the negative electrode tab.

[0080] In conventional batteries, a jumper is needed to connect the electrode terminal and the tab, but this will reduce the utilization rate of the electrode assembly and the energy density of the battery. When the above structure is adopted in the battery cell provided by the present application, canceling the setting of the jumper can effectively solve this problem, reduce the battery internal resistance, and further balance the improvement of the battery energy density and fast charging performance.

[0081] In any embodiment, the housing of the battery is square, the thickness of the housing is 30 mm to 55 mm, the width is 150 mm to 250 mm, and the height is 90 mm to 120 mm.

[0082] In any embodiment, the battery cell is configured to have a charging time of 10 to 17 minutes from 10% SOC to 80% SOC at room temperature.

[0083] The battery cell provided by the present application has excellent fast charging performance.

[0084] The second aspect of the present application further provides a battery device, including the battery cell of the first aspect of the present application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0085] The third aspect of the present application further provides an electrical device, including the battery cell of the first aspect of the present application or the battery device of the second aspect. Description of the Drawings

[0086] Figure 1 It is a schematic diagram of the size of the electrode sheet film layer in an embodiment of the present application;

[0087] Figure 2 It is an electron microscope observation result diagram of the longitudinal section of the positive electrode sheet in an embodiment of the present application;

[0088] Figure 3 It is a schematic diagram of the electrode sheet in an embodiment of the present application;

[0089] Figure 4 It is an exploded view of the battery cell in an embodiment of the present application;

[0090] Figure 5 It is one of the schematic diagrams of the battery cell in an embodiment of the present application;

[0091] Figure 6 It is another schematic diagram of the battery cell in an embodiment of the present application;

[0092] Figure 7 It is a third schematic diagram of the battery cell in an embodiment of the present application;

[0093] Figure 8 It is a schematic diagram of the battery cell in an embodiment of the present application;

[0094] Figure 9 It is Figure 8 The exploded view of the battery cell shown in an embodiment of the present application;

[0095] Figure 10 It is a schematic diagram of the battery module in an embodiment of the present application;

[0096] Figure 11 It is a schematic diagram of the battery pack in an embodiment of the present application;

[0097] Figure 12 It is Figure 11 The exploded view of the battery pack shown in an embodiment of the present application;

[0098] Figure 13 It is a schematic diagram of an electrical device using the battery cell as a power source in an embodiment of the present application.

[0099] Description of the Reference Numerals:

[0100] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly; 10 Battery cell; 11 Current collector; 11a Current collecting part; 111a Positive current collecting part; 112a Negative current collecting part; 11b Tab; 111b Positive tab; 112b Negative tab; F1 First direction; W1 Dimension of the positive electrode film layer in the first direction; W2 Dimension of the negative electrode film layer in the first direction; L Center line; 13 Top cover; 131 Electrode terminal; 14 Housing. Detailed implementation manners

[0101] Hereinafter, embodiments of the battery cell and the electrical device of the present application will be specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0102] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0103] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0104] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0105] Unless otherwise specified, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0106] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present application are open-ended and can also be closed-ended. For example, the "comprising" and "including" can mean that other components not listed may also be included or contained, or may only include or contain the listed components.

[0107] Unless otherwise specified, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0108] As the charging rate of the battery cell increases, lithium ions will be released from the positive electrode active material faster, and the lithium ion concentration distribution in the electrolyte phase may be uneven. As a result, lithium ions are likely to accumulate on the surface of the local negative electrode active material and cannot be embedded in the negative electrode active material equally. Therefore, electrons are obtained on the surface of the negative electrode active material to form silver-white metallic lithium, that is, "lithium dendrites". The formation of lithium dendrites will not only reduce the battery performance, such as shortening the cycle life and poor fast charging performance. At the same time, the continuously deposited metallic lithium will also fall off from the surface of the negative electrode active material, thereby forming "dead lithium" that cannot continue to participate in the reaction, resulting in a decrease in the energy density of the secondary battery.

[0109] To solve the above problems, the present application provides a battery cell, including a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector. The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector. Among them, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes lithium-containing phosphate. The areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2; The areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 ; The positive electrode current collector includes a positive electrode current collecting portion and at least two positive electrode tabs provided on the same side of the positive electrode current collecting portion, and the positive electrode tabs extend from the positive electrode current collecting portion in a first direction; the negative electrode current collector includes a negative electrode current collecting portion and at least two negative electrode tabs provided on the same side of the negative electrode current collecting portion, and the negative electrode tabs extend from the negative electrode current collecting portion in the first direction; along the first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

[0110] As used herein, the "areal density" of the positive electrode film layer or the negative electrode film layer has the meaning well known in the art and can be tested by methods known in the art. For example, take a single-sided coated and cold-pressed negative electrode sheet (if it is a double-sided coated negative electrode sheet, the negative electrode film layer on one side can be wiped off first), punch it into small round pieces with an area of S1, weigh it, and record it as M1. Then wipe off the negative electrode film layer of the above-mentioned weighed negative electrode sheet, weigh the weight of the negative electrode current collector, and record it as M0. The areal density of the negative electrode film layer = (the weight M1 of the negative electrode sheet - the weight M0 of the negative electrode current collector) / S1. To ensure the accuracy of the test results, multiple groups (for example, 10 groups) of samples to be tested can be tested, and the average value can be calculated as the test result.

[0111] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0112] In some embodiments, the battery cell is a wound battery. As shown in Figure 1 , after the electrode sheet is unfolded from the wound state, the positive electrode current collector includes a positive electrode current collecting portion 111a and at least two positive electrode tabs 111b provided on the same side of the positive electrode current collecting portion 111a, and the positive electrode tabs 111b extend from the positive electrode current collecting portion 111a in a first direction F1; the negative electrode current collector includes a negative electrode current collecting portion 112a and at least two negative electrode tabs 112b provided on the same side of the negative electrode current collecting portion 112a, and the negative electrode tabs 112b extend from the negative electrode current collecting portion 112a in the first direction F1. Among them, the size W2 of the negative electrode film layer along the first direction > the size W1 of the positive electrode film layer along the first direction, and the difference is 3 mm to 5 mm.

[0113] The formation of lithium dendrites is closely related to the capacity design of the positive and negative electrode sheets. In this application, by reasonably controlling the film areal density of the positive and negative electrode sheets within a reasonable range, the current density in the positive and negative electrode films becomes more uniform, effectively solving the problem of large-area lithium deposition on the negative electrode sheet. Further, as the charging rate of the battery cell increases, since the root position of the tab is an electron aggregation area, the negative electrode film near the root of the tab is more likely to generate lithium dendrites. On the basis of reasonably controlling the areal density of the positive and negative electrode films, by further reasonably controlling the difference between the size W2 of the negative electrode film and the size W1 of the positive electrode film, the problem of lithium deposition near the root of the tab on the negative electrode sheet can be further improved, thereby enabling the battery to have excellent fast charging performance and cycling performance.

[0114] [Negative electrode sheet]

[0115] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film provided on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film is provided on either or both of the two opposite surfaces of the negative electrode current collector.

[0116] In some embodiments, the areal density of the single-sided negative electrode film is 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 , such as 0.15 g / 1540.25mm 2 , 0.16 g / 1540.25mm 2 , 0.17 g / 1540.25mm 2 , 0.18 g / 1540.25mm 2 , 0.19 g / 1540.25mm 2 etc., or other unlisted values within the range of 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 range.

[0117] In some embodiments, the areal density of the single-sided negative electrode film is 0.15 g / 1540.25mm 2 to 0.165g / 1540.25mm 2 .

[0118] In the battery cell provided by this application, when the coating areal density of the negative electrode film is within the above range, it can improve the energy density of the battery, and also avoid the influence of thick coating on the electrochemical performance, thereby taking into account the improvement of the fast charging performance of the battery.

[0119] In some embodiments, the negative electrode film layer includes a negative electrode active material.

[0120] In some embodiments, the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, such as 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc., or other values not listed within the range of 8 μm to 15 μm. In some embodiments, the negative electrode active material includes graphite.

[0121] As used herein, "average particle size Dv50" refers to: in the particle size distribution of particles, starting from the small particle size side, the particle size corresponding to when the cumulative volume distribution percentage reaches 50%. Its measurement method can refer to GB / T19077-2016 / ISO13320:2009, and a Malvern 2000 (MasterSizer 2000) laser particle size analyzer is used for measurement.

[0122] In the battery cell provided by the present application, when the negative electrode active material (such as graphite) has a particle size within the above range, it has a relatively large specific surface area, the migration channels between the graphite layers for lithium ions increase, and the migration path becomes shorter, thereby accelerating the intercalation and deintercalation speed of lithium ions between the graphite layers, enabling the battery cell to have good fast charging performance; at the same time, when the negative electrode active material (such as graphite) has a particle size within the above range, it can also improve the DC internal resistance of the battery cell, thereby reducing battery heat generation and enabling the battery to have good safety performance.

[0123] In some embodiments, the average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm, such as 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, etc., or other values not listed within the range of 9.5 μm to 11.5 μm.

[0124] When the negative electrode active material (such as graphite) has a particle size within the above range, it can further improve the fast charging performance and DC internal resistance of the battery, and at the same time enable the battery to have good cycle performance.

[0125] In some embodiments, the graphitization degree of the negative electrode active material is 90% - 95%.

[0126] In some embodiments, the graphitization degree of the negative electrode active material is 92% - 95%.

[0127] When the graphitization degree of the negative electrode active material is within the above range, the capacity can be further improved.

[0128] As used herein, "graphitization degree" refers to an index for measuring the degree to which carbon atoms form a hexagonal close-packed graphite crystal structure, which can be tested using an X-ray diffractometer (such as Bruker D8 Discover). Referring to JIS K0131-1996 and JB / T 4220-2011, the average layer spacing d of the (002) crystal plane in the crystal structure of the carbon material is obtained. 002 , and then the graphitization degree is calculated according to the formula g = (0.344 - d 002 ) / (0.344 - 0.3354) × 100%. In the above formula, d 002 is the average layer spacing of the (002) crystal plane in the crystal structure of the carbon material expressed in nanometers (nm).

[0129] In some embodiments, the negative electrode film layer includes at least two negative electrode active material layers. In some embodiments, the negative electrode film layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector. The negative electrode active material in the first negative electrode active material layer includes a first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes a second artificial graphite. The average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

[0130] In some embodiments, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm, such as 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc., or other unlisted values within the range of 11 μm to 15 μm.

[0131] In some embodiments, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm, such as 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc., or other unlisted values within the range of 8 μm to 15 μm.

[0132] In some embodiments, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm, such as 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, etc., or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0133] In the battery cell provided by the present application, when the above double-layer coating scheme is adopted in the negative electrode film layer, the kinetic performance of the battery can be further improved.

[0134] In some embodiments, the negative electrode film layer may further optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0135] In some embodiments, the negative electrode film layer may further optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0136] In some embodiments, the negative electrode film layer may further optionally include other additives, such as a thickening agent (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0137] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0138] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 6 μm, such as 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, etc., or other values not listed within the range of 4 μm to 6 μm.

[0139] In some embodiments, the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20, such as 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., or other values not listed within the range of 12 to 20.

[0140] In some embodiments, the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

[0141] In some embodiments, the single-sided thickness of the negative electrode film layer corresponds to the single-sided thickness of the negative electrode film layer of the battery cell in the 0% SOC state. The battery cell in the 0% SOC state refers to the state where the battery cell is discharged at 1 / 3C to 2.0V and then discharged at 0.05C to 2.0V. In the battery cell provided in the present application, when the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector is within the above range, it can further balance and improve the energy density and fast charging performance of the battery.

[0142] In some embodiments, in combination with Figure 3 As shown, the current collector 11 includes a current collecting portion 11a and at least two tabs 11b provided on the same side of the current collecting portion 11a. The tabs 11b extend from the current collecting portion 11a along a first direction F1. Wherein, the distance between the center lines L of two adjacent tabs 11b is 10 mm to 350 mm, and the center line L is parallel to the first direction F1. For example, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, etc., or other unlisted values within the range of 10 mm to 350 mm.

[0143] In some embodiments, the distance between the center lines L of two adjacent tabs 11b is 20 mm to 330 mm, and the center line L is parallel to the first direction F1. For example, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, etc., or other unlisted values within the range of 20 mm to 330 mm.

[0144] In some embodiments, in combination with Figure 3 and Figure 4 As shown, the current collector 11 may be a positive current collector, and the tab 11b may be a positive tab 111b.

[0145] In some embodiments, in combination with Figure 3 and Figure 4 As shown, the current collector 11 may be a negative current collector, and the tab 11b may be a negative tab 112b.

[0146] In some embodiments, the negative electrode current collector includes a negative electrode current collecting portion and at least two negative electrode tabs disposed on the same side of the negative electrode current collecting portion, and the negative electrode tabs extend from the negative electrode current collecting portion along a first direction. In some embodiments, the distance between the centerlines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the centerlines are parallel to the first direction, such as 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, etc., or other unlisted values within the range of 10 mm to 350 mm.

[0147] In some embodiments, the distance between the centerlines of two adjacent negative electrode tabs is 20 mm to 330 mm, and the centerlines are parallel to the first direction, such as 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, etc., or other unlisted values within the range of 20 mm to 330 mm.

[0148] In some embodiments, in combination Figure 3 As shown, the centerline L refers to the symmetry axis passing through the midpoint of the tab 11b along the length direction of the current collector 11, and the centerline L is parallel to the first direction F1. In some embodiments, the dimensions of each tab 11b along the length direction of the current collector 11 are equal.

[0149] In some embodiments, in combination Figure 3 As shown, the distance between the centerlines L of two adjacent tabs 11b includes S1 or S2, where S1 and S2 may be equal (in this case, the adjacent tabs are equally spaced), and S1 and S2 may also be unequal (in this case, the adjacent tabs are unequally spaced).

[0150] In the battery cell provided by the present application, when the positive and negative electrode current collectors include at least two tabs having the above structural features, it can further improve the overcurrent capacity, improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery, and making the battery have better safety performance.

[0151] In some embodiments, the negative electrode plate can be prepared in the following manner: dispersing the above components for preparing the negative electrode plate, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0152] In some embodiments, the tap density of the negative electrode tab is 1.3 g / cm 3 to 1.6 g / cm 3 , such as 1.3 g / cm 3 , 1.4 g / cm 3 , 1.5 g / cm 3 , 1.6 g / cm 3 , etc., or other unlisted values within the range of 1.3 g / cm 3 to 1.6 g / cm 3 .

[0153] In some embodiments, the tap density of the negative electrode tab is 1.35 g / cm 3 to 1.55 g / cm 3 , such as 1.35 g / cm 3 , 1.40 g / cm 3 , 1.45 g / cm 3 , 1.50 g / cm 3 , 1.55 g / cm 3 , etc., or other unlisted values within the range of 1.35 g / cm 3 to 1.55 g / cm 3 .

[0154] In some embodiments, the tap density of the negative electrode tab corresponds to the tap density of the negative electrode film layer of the battery cell corresponding to the 0% SOC state. The battery cell in the 0% SOC state means: the battery cell is discharged to 2.0 V at 1 / 3 C and then discharged to 2.0 V at 0.05 C. When used herein, the "tap density" of the electrode tab is: tap density = areal density / (electrode tab thickness - current collector thickness), and its measurement method can refer to GB / T24533-2009.

[0155] When the tap density of the negative electrode tab is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0156] [Positive electrode tab]

[0157] In some embodiments, the positive electrode tab includes a positive current collector and a positive electrode film layer provided on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is provided on either or both of the two opposite surfaces of the positive current collector.

[0158] In some embodiments, the areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm2 , such as 0.33 g / 1540.25mm 2 , 0.34 g / 1540.25mm 2 , 0.35 g / 1540.25mm 2 , 0.36 g / 1540.25mm 2 , 0.37 g / 1540.25mm 2 , 0.38 g / 1540.25mm 2 , 0.39 g / 1540.25mm 2 , 0.4 g / 1540.25mm 2 etc., or values from 0.33g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 and other unlisted values within the range.

[0159] In some embodiments, the areal density of the single-sided positive electrode film layer is 0.335 g / 1540.25mm 2 to 0.38g / 1540.25mm 2 .

[0160] In the battery cell provided by the present application, when the coating areal density of the positive electrode film layer is within the above range, the energy density of the battery can be improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby taking into account the improvement of the fast charging performance of the battery.

[0161] In some embodiments, the positive electrode film layer includes a positive electrode active material.

[0162] In some embodiments, the positive electrode active material includes a lithium-containing phosphate with an olivine structure.

[0163] In some embodiments, the general formula of the composition of the lithium-containing phosphate with an olivine structure is shown in Formula I,

[0164] Li x A y Me a M b P 1-c X c Y z Formula I,

[0165] Wherein, 0.1 ≤ x ≤ 1.3, 0 ≤ y ≤ 1.3, and 0.9 ≤ x + y ≤ 1.3; 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5; 0 ≤ c ≤ 0.5; 3 ≤ z ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

[0166] As used herein, "the general formula of the lithium-containing phosphate having an olivine structure is shown in Formula I" is not limited to the substances represented by the general formula, but also includes other substances formed by further appropriate modification on the basis of the general formula, which are not limited herein. The use of "general formula" is only for convenience of description and is not intended to limit the present application. It can be understood that new materials or substances obtained by appropriate modification on the basis of the listed cathode active materials are also within the scope of the cathode active materials. The aforementioned appropriate modification refers to the acceptable modification methods for the cathode active materials, and non-limiting examples include coating modification.

[0167] When the lithium-containing phosphate as the cathode active material has the above chemical general formula, the energy density of the battery can be further improved.

[0168] In some embodiments, M includes one or more of Al, Ti, V, and Mg.

[0169] In some embodiments, the cathode active material contains Al element, and its mass content is 0.001% - 0.05%, optionally 0.01% - 0.05%, based on the total mass of the cathode active material. For example, 0.001%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, etc., or other unlisted values within the range of 0.001% - 0.05%, based on the total mass of the cathode active material.

[0170] In some embodiments, the cathode active material contains Ti element, and its mass content is 0.001% - 0.03%, optionally 0.01 - 0.03%, based on the total mass of the cathode active material. For example, 0.001%, 0.01%, 0.02%, 0.03%, etc., or other unlisted values within the range of 0.001% - 0.03%, based on the total mass of the cathode active material.

[0171] In some embodiments, the positive electrode active material contains V element, and its mass content is 0.001% to 0.3%, optionally 0.1% to 0.3%, based on the total mass of the positive electrode active material. For example, 0.001%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc., or other unlisted values within the range of 0.001% to 0.3%, based on the total mass of the positive electrode active material.

[0172] In some embodiments, the positive electrode active material contains Mg element, and the mass content is 0.001% to 0.01%, based on the total mass of the positive electrode active material. Optionally, it can be 0.001%, 0.002%, 0.005%, 0.01%, or other unlisted values within the range of 0.001% to 0.01%, based on the total mass of the positive electrode active material.

[0173] When the lithium-containing phosphate as the positive electrode active material contains elements such as Al, Ti, V, and Mg, it can further improve the structural stability of the material and enhance the cycling performance.

[0174] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm.

[0175] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm, such as 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, etc., or other unlisted values within the range of 0.05 μm to 0.3 μm.

[0176] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc., or other unlisted values within the range of 1 μm to 3 μm.

[0177] In some embodiments, since the first lithium-containing phosphate and the second lithium-containing phosphate have been fully mixed during the preparation of the slurry and uniformly coated on the current collector to form the positive electrode film layer, therefore, for any cross-section taken along the thickness direction of the electrode sheet, it can represent the particle size and distribution of the lithium-containing phosphate in the entire electrode sheet; when selecting the cross-section, it is preferably a relatively flat cross-section in the middle of the electrode sheet to more clearly observe the distribution of the lithium-containing phosphate therein.

[0178] In some embodiments, the "longest diameter" means: cutting the positive electrode sheet including the lithium-containing phosphate particles along the thickness direction of the sheet to expose the longitudinal section of the positive electrode film layer; determining the longest diameter of the lithium-containing phosphate particles by performing a scanning electron microscope (SEM) test on the longitudinal section of the positive electrode film layer. Specifically, among the distances between any two points on the outer peripheral edge line of the lithium-containing phosphate particles, the maximum value is the "longest diameter" of the particles. In some embodiments, as Figure 2 shown in the longitudinal section of the electrode sheet along the thickness direction, which shows the longest diameter of a single particle satisfying the first lithium-containing phosphate particles (with the longest diameter being 0.05 μm to 0.3 μm), and also shows the shortest diameter of a single particle satisfying the second lithium-containing phosphate particles (with the longest diameter being 1 μm to 3 μm).

[0179] In the battery cell provided by the present application, when the positive electrode active material contains lithium-containing phosphate particles with the longest diameter of 0.05 μm to 0.3 μm, it can further improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery, and enabling the battery to have excellent safety performance.

[0180] In the battery cell provided by the present application, when the lithium-containing phosphate as the positive electrode active material simultaneously contains first lithium-containing phosphate particles with the longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with the longest diameter of 1 μm to 3 μm, the tap density of the electrode sheet can be effectively improved by the method of grading of large and small particles, so that the battery cell also has a relatively high energy density.

[0181] In some embodiments, in the cross-section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0182] In the lithium-containing phosphate as the positive electrode active material, when the number of the first lithium-containing phosphate particles with the longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles with the longest diameter of 1 μm to 3 μm, the improvement of the DC internal resistance and the fast charging performance of the battery can be further considered.

[0183] It should be noted that the first lithium-containing phosphate particle material with a relatively small size and the longest diameter of 0.05 μm to 0.3 μm is one of the positive electrode active materials of the battery cell of the present application, and the particle size range of 0.05 μm to 0.3 μm is a characteristic parameter of the material itself.

[0184] The second lithium-containing phosphate particle material with a relatively large size and the longest diameter of 1 μm to 3 μm is one of the positive electrode active materials of the battery cell of the present application, and the particle size range of 1 μm to 3 μm is a characteristic parameter of the material itself.

[0185] Those skilled in the art can mix the lithium-containing phosphate particle materials within the above two size ranges according to actual needs.

[0186] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. The present application does not particularly limit the type of the positive electrode conductive agent. As an example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0187] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. The present application does not particularly limit the type of the positive electrode binder. As an example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0188] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of the metal foil, aluminum foil can be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0189] In some embodiments, the thickness of the positive electrode current collector is 10 μm to 15 μm, such as 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc., or other unlisted values within the range of 10 μm to 15 μm.

[0190] In some embodiments, the ratio of the single-sided thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 5 to 12, such as 5, 6, 7, 8, 9, 10, 11, 12, etc., or other unlisted values within the range of 5 to 12.

[0191] In some embodiments, the ratio of the single-sided thickness of the positive electrode film layer to the thickness of the positive electrode current collector is 6 to 10.

[0192] In the battery cell provided by the present application, when the ratio of the single-sided thickness of the positive electrode film layer to the thickness of the positive electrode current collector is within the above range, the thickness of the current collector is within a suitable range, which will not cause energy density loss due to excessive thickness, nor will it cause problems such as poor overcurrent capacity and low tensile strength resulting in pole piece cracking due to excessive thinness, and further takes into account improving the energy density and fast charging performance of the battery.

[0193] In some embodiments, the positive electrode current collector includes a positive electrode current collecting portion and at least two positive electrode tabs provided on the same side of the positive electrode current collecting portion. The positive electrode tabs extend from the positive electrode current collecting portion along a first direction. Among them, the distance between the centerlines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the centerline is parallel to the first direction. For example, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, etc., or other unlisted values within the range of 10 mm to 350 mm.

[0194] In some embodiments, the distance between the centerlines of two adjacent positive electrode tabs is 20 mm to 330 mm. For example, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 330 mm, etc., or other unlisted values within the range of 20 mm to 330 mm.

[0195] In the battery cell provided by the present application, when the positive and negative current collectors include at least two tabs having the above structural features, it can further improve the overcurrent capacity, improve the DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have better safety performance.

[0196] In some embodiments, the dimension of the positive electrode film layer along the first direction is W1 mm, and the dimension of the negative electrode film layer along the first direction is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm. For example, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm, etc., or other unlisted values within the range of 3 mm to 5 mm.

[0197] During the cycling process of the battery, lithium ions that cannot be embedded into the negative electrode in time may form lithium dendrites on the surface of the negative electrode, deteriorating the cycling performance of the battery. In the battery cell provided by the present application, when the size W2 of the negative electrode film layer and the size W1 of the positive electrode film layer have the above relationship, the formation of lithium dendrites on the surface of the negative electrode by lithium ions can be improved, so that the battery can simultaneously have better cycling performance.

[0198] In some embodiments, the positive electrode plate can be prepared in the following manner: dispersing the components for preparing the positive electrode plate, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0199] In some embodiments, the tap density of the positive electrode plate is 2.3 g / cm 3 to 2.6 g / cm 3 , such as 2.30 g / cm 3 , 2.35 g / cm 3 , 2.40 g / cm 3 , 2.45 g / cm 3 , 2.50 g / cm 3 , 2.55 g / cm 3 , 2.60 g / cm 3 , etc., or other unlisted values within the range of 2.3 g / cm 3 to 2.6 g / cm 3 .

[0200] In some embodiments, the tap density of the positive electrode plate is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0201] When the tap density of the positive electrode plate is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0202] In some embodiments, the tap density of the positive electrode plate corresponds to the tap density of the positive electrode film layer of the battery cell in the 0% SOC state. The battery cell in the 0% SOC state refers to the state in which the battery cell is discharged at 1 / 3C to 2.0 V and then discharged at 0.05C to 2.0 V.

[0203] [Electrolyte]

[0204] The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. For example, the electrolyte can be liquid, solid, or gel-like.

[0205] In some embodiments, the electrolyte is an electrolytic solution. The electrolytic solution includes an electrolyte salt and an organic solvent.

[0206] In the embodiments of the present application, the types and contents of the organic components in the electrolytic solution have meanings well-known in the art and can be detected by devices and methods well-known in the art. For example, the composition in the electrolytic solution can be measured by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic resonance method, etc. Exemplarily, qualitative and quantitative analysis of the organic components in the electrolytic solution can be performed by gas chromatography with reference to GB / T9722-2006 General Rules for Chemical Reagents - Gas Chromatography.

[0207] The test sample in the embodiments of the present application can be a newly prepared electrolytic solution as the sample, or the free electrolytic solution obtained from the battery after the battery is discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) as the sample.

[0208] In the embodiments of the present application, the types and contents of the inorganic components / lithium salt concentration in the electrolytic solution have meanings well-known in the art and can be detected by devices and methods well-known in the art. For example, qualitative or quantitative analysis of the inorganic components / lithium salt concentration in the electrolytic solution can be performed by ion chromatography with reference to the standard JY / T020-1996 General Rules for Ion Chromatographic Analysis. In the embodiments of the present application, a newly prepared electrolytic solution can be taken as the sample, or the free electrolytic solution obtained from the battery after the battery is discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) as the sample, and detected by ion chromatography.

[0209] In some embodiments, the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0210] In the battery cell provided by the present application, when the above types of organic solvents are used in the electrolytic solution, the kinetic performance of the battery can be further improved.

[0211] In some embodiments, the organic solvent includes a linear carboxylic acid ester. Based on the total mass of the electrolytic solution, the mass ratio of the linear carboxylic acid ester is 40% to 75%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc., or other unlisted values within the range of 40% to 75%.

[0212] In some embodiments, the linear carboxylic acid ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include one or more of C1~C5 alkyl groups and C1~C5 haloalkyl groups.

[0213] In some embodiments, the linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

[0214] When the above types and mass ratios of linear carboxylic acid esters are used as organic solvents in the electrolyte, due to the low viscosity of the linear carboxylic acid esters, they can effectively improve the conductivity of the electrolyte, thereby further improving the fast charging performance of the battery.

[0215] In some embodiments, the organic solvent includes a carbonate solvent, and the carbonate solvent includes a linear carbonate and a cyclic carbonate. Based on the total mass of the electrolyte, the mass ratio of the linear carbonate is 10% to 40%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc., or other unlisted values within the range of 10% to 40%.

[0216] In some embodiments, the cyclic carbonate includes one or more of ethylene carbonate and propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0217] In some embodiments, the linear carbonate includes dimethyl carbonate. Based on the total mass of the electrolyte, the mass ratio of dimethyl carbonate is 5% to 15%, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc., or other unlisted values within the range of 5% to 15%.

[0218] When the above types and mass ratios of carbonates are used as organic solvents in the electrolyte, the side reactions and gas generation during the cycling of the battery can be improved, so that the battery can simultaneously have good cycling performance.

[0219] In some embodiments, the organic solvent includes dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to dimethyl carbonate is 2.0 to 7.0, such as 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, etc., or other unlisted values within the range of 2.0 to 7.0.

[0220] In some embodiments, the organic solvent includes dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to dimethyl carbonate is 3.0 to 6.0.

[0221] When dimethyl carbonate and a linear carboxylic acid ester with the above mass ratio are simultaneously used as organic solvents in the electrolyte, through the combination of the two solvents, the fast charging performance and cycling performance of the battery can be further improved simultaneously.

[0222] In some embodiments, the electrolyte further includes a lithium salt, such as at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro(bis(oxalato))phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0223] In some embodiments, based on the total mass of the electrolyte, the mass percentage of the lithium salt is 13% to 20%, such as 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc., or other unlisted values within the range of 13% to 20%.

[0224] In some embodiments, the lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorosulfonylimide salts, and the fluorosulfonylimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0225] Lithium hexafluorophosphate is not prone to gas generation during cycling, which can further improve the cycling performance of the battery; while the fluorosulfonylimide salt has strong dissociation ability, which can further improve the fast charging performance of the battery.

[0226] In some embodiments, the lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0227] In some embodiments, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:1, such as 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc., or other unlisted values within the range of 1.2:1 to 2:1.

[0228] When lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide within the above mass ratio range are simultaneously used in the electrolyte, the fast charging performance and cycling performance of the battery can be further balanced.

[0229] In some embodiments, the electrolyte further includes additives. For example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives that can improve certain battery performance, such as additives for improving the overcharging performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0230] In some embodiments, the electrolyte includes carbonate additives, and the carbonate additives include fluoroethylene carbonate FEC and vinylene carbonate VC.

[0231] In some embodiments, based on the total mass of the electrolyte, the mass proportion of the carbonate additive is 0.5% to 7%, such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 6.5%, 7%, etc., or other unlisted values within the range of 0.5% to 7%.

[0232] In the battery cell provided by the present application, a carbonate additive with a mass proportion within the above range is further added to the electrolyte. For example, fluoroethylene carbonate and vinylene carbonate can form a SEI film on the surface of the negative electrode, thereby reducing the side reactions occurring between the electrode sheet and the electrolyte, and further enabling the battery to have better cycle performance.

[0233] In some embodiments, the electrolyte includes vinylene carbonate (VC). Based on the total mass of the electrolyte, the mass proportion of vinylene carbonate (VC) in the electrolyte is 0.5% to 2%, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc., or other unlisted values within the range of 0.5% to 2%.

[0234] When vinylene carbonate within the above mass proportion range is added as an additive to the electrolyte, the formed SEI film is relatively stable, which is beneficial to further improving the cycle performance of the battery.

[0235] In some embodiments, the electrolyte includes fluoroethylene carbonate (FEC). Based on the total mass of the electrolyte, the mass proportion of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 1%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc., or other unlisted values within the range of 0.1% to 1%.

[0236] When fluoroethylene carbonate within the above mass proportion range is added as an additive to the electrolyte, the formed SEI film has a low impedance, which can further improve the fast charging performance of the battery.

[0237] [Separator membrane]

[0238] In some embodiments, the battery cell further includes a separator membrane. The present application does not particularly limit the type of the separator membrane, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0239] In some embodiments, the material of the separator membrane may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0240] [Battery cell]

[0241] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator membrane may be made into an electrode assembly by a winding process or a stacking process.

[0242] In some embodiments, the positive electrode current collector, the separator, the negative electrode current collector, and the separator are stacked in sequence and wound together; after winding, the positive electrode tabs 111b of the positive electrode current collector are aligned and stacked, and the negative electrode tabs 112b of the negative electrode current collector are aligned and stacked, as Figure 4 shown.

[0243] In some embodiments, the battery cell further includes a top cover, and the top cover includes electrode terminals with opposite polarities for electrically connecting to the positive electrode tab or the negative electrode tab.

[0244] In some embodiments, as shown in Figure 4 the battery cell 10 further includes a top cover 13, and the top cover 13 includes two electrode terminals 131 with opposite polarities, one of which is a positive electrode terminal 131 for electrically connecting to the positive electrode tab 111b, and the other is a negative electrode terminal 131 for electrically connecting to the negative electrode tab 112b.

[0245] The wound positive electrode tabs 111b are aligned and stacked, having a large connection area, so as to facilitate the direct electrical connection between the positive electrode tabs 111b and the electrode terminals 131 without connecting the positive electrode tabs 111b and the electrode terminals 131 through a transition piece. Similarly, the wound negative electrode tabs 112b are aligned and stacked, having a large connection area, so as to facilitate the direct electrical connection between the negative electrode tabs 112b and the electrode terminals 131 without connecting the negative electrode tabs 112b and the electrode terminals 131 through a transition piece.

[0246] In a conventional battery, a transition piece is required to connect the electrode terminal and the tab, but this will reduce the utilization rate of the electrode assembly and lower the battery energy density. When the above structure is adopted in the battery cell provided in the present application, canceling the setting of the transition piece can effectively solve this problem, reduce the battery internal resistance, and further improve the battery energy density and fast charging performance.

[0247] In some embodiments, the battery cell may include an outer package. The outer package may be used to encapsulate the above electrode assembly and electrolyte.

[0248] In some embodiments, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell can also be a soft pack, such as a pouch soft pack. The material of the soft pack can be plastic. Examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate, etc.

[0249] In some embodiments, as Figures 4 - 7 shown, the battery cell 10 further includes a housing 14, and the current collector 11 is disposed within the housing 14.

[0250] In some embodiments, as Figures 4 - 7 shown, the housing 14 is square, the thickness T of the housing is 30 mm to 55 mm, the width W is 150 mm to 250 mm, and the height H is 90 mm to 120 mm.

[0251] In some embodiments, the thickness T of the housing is 30 mm to 55 mm, such as 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, etc., or other unlisted values within the range of 30 mm to 55 mm.

[0252] In some embodiments, the width W of the housing is 150 mm to 250 mm, such as 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, etc., or other unlisted values within the range of 150 mm to 250 mm.

[0253] In some embodiments, the height H of the housing is 90 mm to 120 mm, such as 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, etc., or other unlisted values within the range of 90 mm to 120 mm.

[0254] In some embodiments, the battery cell is configured to have a charging time of 10 min to 17 min when charging from 10% SOC to 80% SOC at room temperature, such as 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, etc., or other unlisted values within the range of 10 min to 17 min.

[0255] The battery cell provided by the present application has excellent fast charging performance.

[0256] In some embodiments, the present application does not particularly limit the shape of the battery cell, and it can be cylindrical, square, or any other arbitrary shape. For example, Figure 8The battery cell 5 has a square structure as an example. Optionally, the battery cell is a lithium-ion battery or a sodium-ion battery.

[0257] In some embodiments, referring to Figure 9 , the outer package may include a housing 51 and a cover plate 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0258] In some embodiments, a battery device is provided. The battery device can be a battery module, a battery pack, an energy storage battery, etc. The above battery cells can be assembled into a battery module. The number of battery cells included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0259] Figure 10 The battery module 4 is shown as an example. Referring to Figure 10 , in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0260] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of battery cells 5 are received in the receiving space.

[0261] In some embodiments, the above battery module can be further assembled into a battery pack. The number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0262] Figure 11 and Figure 12 The battery pack 1 is shown as an example. Referring to Figure 11 and Figure 12 , the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any way.

[0263] [Electrical device]

[0264] In addition, the present application also provides an electrical device, which includes at least one of the battery cells, battery modules, or battery packs provided by the present application. The battery cell, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0265] As the electrical device, the battery cell, battery module, or battery pack can be selected according to its usage requirements.

[0266] Figure 13 Take an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the requirements of the electrical device for the high power and high energy density of the battery cell, a battery pack or a battery module can be adopted.

[0267] In some embodiments, the electrical device includes a vehicle, and the length direction of the electrode assembly is placed along the traveling direction of the vehicle.

[0268] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a battery cell can be used as the power source.

[0269] Embodiment

[0270] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0271] Embodiment 1

[0272] 1) Negative electrode tab

[0273] Mix artificial graphite as the negative electrode active material, acetylene black as the conductive agent, styrene-butadiene rubber as the binder, and sodium carboxymethyl cellulose as the thickening agent in a mass ratio of 96:1:2:1, and then add deionized water as the solvent and stir to form a negative electrode slurry. Coat the negative electrode slurry evenly on a copper foil as the negative electrode current collector, and after drying and cold pressing, a negative electrode tab is obtained; wherein, the thickness of the copper foil as the negative electrode current collector is 4.5 μm, the single-sided surface density of the negative electrode tab is 0.155 g / 1540 mm 2 , and the compaction density of the negative electrode tab is 1.47 g / cm3 The size of the negative electrode film layer in the first direction is 92 mm; the volume particle size Dv50 of the artificial graphite is 11 μm, and the graphitization degree is 94.1%.

[0274] 2) Positive electrode sheet

[0275] Mix the positive electrode active material lithium iron phosphate (LFP), binder polyvinylidene fluoride, and conductive agent acetylene black in a ratio of 97:2:1, and then add the solvent N-methylpyrrolidone (NMP) and stir to form a positive electrode paste; coat the positive electrode paste evenly on the positive electrode current collector aluminum foil, and after drying and cold pressing, obtain the positive electrode sheet. Among them, the thickness of the positive electrode current collector aluminum foil is 13 μm, and the single-sided areal density of the positive electrode sheet is 0.341 mg / 1540 mm 2 The tap density of the positive electrode sheet is 2.51 g / cm 3 The size of the positive electrode film layer along the first direction is 88.5 mm; the positive electrode active material includes first lithium-containing phosphate particles with a longest diameter of 0.3 μm - 1 μm and second lithium-containing phosphate particles with a longest diameter of 3 μm - 5 μm. In the longitudinal section of the positive electrode sheet, select any area that contains at least 100 olivine-structured lithium-containing phosphates. In the said any area, the number of the first lithium-containing phosphate particles is greater than that of the second lithium-containing phosphate particles.

[0276] 3) Electrolyte

[0277] Mix dimethyl carbonate (DMC), ethyl acetate (EA), ethylene carbonate (EC), and ethyl methyl carbonate (EMC) evenly in a mass ratio of 10:50:35:5 to obtain an electrolyte solvent. Include lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) as lithium salts, and stir well until they are completely dissolved. Include vinylene carbonate (VC) with a mass percentage of 0.7% and fluoroethylene carbonate (FEC) with a mass percentage of 0.3% based on the total mass of the electrolyte. Based on the total mass of the electrolyte, the mass ratio of lithium hexafluorophosphate (LiPF6) is 8.9%; the mass ratio of lithium bis(fluorosulfonyl)imide LiFSI is 4.6%, and the lithium ion conductivity of the electrolyte is 14.5 mS / cm.

[0278] 4) Separator

[0279] Use a commercially available polyethylene microporous film with a thickness of 7 μm and an average pore diameter of 80 nm as the separator.

[0280] 5) Battery cell

[0281] The positive electrode tab and the negative electrode tab are cut. The distance between the center lines of two adjacent tabs of the positive electrode tab is 316 mm, and the distance between the center lines of two adjacent tabs of the negative electrode tab is 314 mm. The positive electrode tab, the separator, and the negative electrode tab are stacked and wound in sequence to obtain a wound electrode assembly, so that each layer of the positive electrode tab and the negative electrode tab of the electrode assembly has at least one tab. The electrode assembly is placed into a square aluminum outer package with a thickness of 50 mm, a width of 208 mm, and a height of 103 mm, and electrolyte is injected after drying. Through processes such as encapsulation, standing, formation, aging, secondary encapsulation, and capacity measurement, a battery cell is obtained, and the tab of the battery cell is connected to the cover plate.

[0282] Examples 2 to 3

[0283] The battery cells of Examples 2 to 3 are basically similar to those of Example 1, except that the widths W1 and W2 of the positive electrode film layer and the negative electrode film layer are adjusted, so as to adjust the value of W2 - W1. The specific values are shown in Tables 1 to 4.

[0284] Examples 4 to 6

[0285] The battery cells of Examples 4 to 6 are basically similar to those of Example 1, except that the areal density of the single-sided negative electrode film layer and the areal density of the single-sided positive electrode film layer are adjusted. The specific values are shown in Tables 1 to 4.

[0286] Examples 7 to 10

[0287] The battery cells of Examples 7 to 10 are basically similar to those of Example 1, except that the types or contents of the organic solvent and the lithium salt in the electrolyte are changed. The specific values are shown in Tables 1 to 4.

[0288] Example 11

[0289] The battery cell of Example 11 is basically similar to that of Example 1, except that the negative electrode active material uses double-sided coating, and the method is as follows: artificial graphite with a Dv50 particle size of 13 μm is used as the lower layer, and artificial graphite with a Dv50 particle size of 10 μm is used as the upper layer, and they are uniformly coated on the negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode tab is obtained. The specific values are shown in Tables 1 to 4.

[0290] Comparative Examples 1 to 2

[0291] Comparative Examples 1 to 2 are basically similar to Example 1, except that the widths W1 and W2 of the positive electrode film layer and the negative electrode film layer are adjusted, so as to adjust the value of W2 - W1. The specific values are shown in Tables 1 to 4.

[0292] Comparative Examples 3 to 4

[0293] Comparative Examples 3 to 4 are basically similar to Example 1, except that the areal density of the single-sided positive electrode tab and the single-sided negative electrode tab. The specific values are shown in Tables 1 to 4.

[0294] I. Performance Test

[0295] 1. DC Internal Resistance

[0296] The DC internal resistance DCR test of a single battery cell can refer to the method in GB / T 31467 "Performance Test Specification for High-Power Lithium-Ion Power Batteries for HEV". For example, at room temperature, charge the single battery cell to 3.65V with a constant current of 0.33C, let it stand for 1 min, then charge it to 3.65V with a constant current of 0.1C, let it stand for 30 min, discharge it to 2.0V with a constant current of 0.33C, record the discharge capacity A0 at this time, with the unit of Ah, and then charge it with a constant current of 0.33C for 0.5A0Ah to adjust the SOC to 50%. After leaving the single battery cell at 25°C for 2 h, discharge it with a constant current of 3C for 10 s, record ∆U discharge and ∆I discharge, and calculate the discharge DCR data of the lithium-ion battery through the following formula: R discharge = ∆U discharge / ∆I discharge, where ∆U discharge represents the voltage change within the first 10 s of discharge, and ∆I discharge represents the current value within the first 10 s of discharge.

[0297] 2. Charging Time at 10% - 80% SOC

[0298] Charging time test: ① Voltage calibration: 1) In the examples or comparative examples, the positive electrode sheet, negative electrode sheet, separator, and electrolyte are prepared into a laminated three-electrode battery and left to stand at 25°C for 30 min; 2) At 25°C, the battery cell is charged at 0.33C until the charging cut-off voltage of 3.65V, and then constant voltage charging is continued at this charging cut-off voltage until the current is 0.05C, and the charging is cut off (where C represents the rated capacity of the battery cell); 3) Leave to stand at 25°C for 1 h; 4) At 25°C, the battery cell is discharged at 0.33C until the discharge cut-off voltage of 2.5V, and record the total discharge capacity C0 discharged by the battery cell; 5) Leave to stand at 25°C for 1 h. ② Normal temperature charging test: 1) In the examples or comparative examples, the positive electrode sheet, negative electrode sheet, separator, and electrolyte are prepared into a laminated three-electrode battery and left to stand for 30 min; 2) DC discharge at 0.33C0 to the discharge cut-off voltage of 2.5V, corresponding to 0% SOC at this time; 3) Leave to stand for 5 min; 4) Constant current charge at 5C0 until the negative electrode potential is 0V, and read the capacity C1 at this time, corresponding to C1 / C0 SOC at this time; 5) Leave to stand for 5 min; 6) Constant current charge at 4.5C0 until the negative electrode potential is 0V, and read the capacity C2 at this time, corresponding to C2 / C0 SOC at this time; 7) Leave to stand for 5 min; 8) Constant current charge at 4C0 until the negative electrode potential is 0V, and read the capacity C3 at this time, corresponding to C3 / C0 SOC at this time; 9) Leave to stand for 5 min; 10) Constant current charge at 3C0 until the negative electrode potential is 0V, and read the capacity C4 at this time, corresponding to C4 / C0 SOC at this time; 11) Leave to stand for 5 min; 12) Constant current charge at 2C0 until the negative electrode potential is 0V, and read the capacity C5 at this time, corresponding to C5 / C0 SOC at this time; 13) Leave to stand for 5 min; 14) Constant current charge at 1C0 until the negative electrode potential is 0V, and read the capacity C6 at this time, corresponding to C6 / C0 SOC at this time; 15) Leave to stand for 5 min; 16) Constant current charge at 0.8C0 until the negative electrode potential is 0V, and read the capacity C7 at this time, corresponding to C7 / C0 SOC at this time; 17) Leave to stand for 5 min; 18) Constant current charge at 0.5C0 until the negative electrode potential is 0V, and read the capacity C8 at this time, corresponding to C8 / C0 SOC at this time; 19) Leave to stand for 5 min; 20) Constant current charge at 0.33C0 until the negative electrode potential is 0V, and read the capacity C9 (i.e., C0) at this time, corresponding to 100% SOC. The required charging time is obtained by adding up the total charging time during the charging process from 10% SOC to 80% SOC.

[0299] 3. Volume energy density

[0300] At 25°C, the battery cell is discharged at a constant current of 0.33C to 2.5V, left standing for 5 minutes, charged at a constant current of 0.33C to the upper cut-off voltage of 3.65V, then charged at a constant voltage until the current reaches 0.05C, and left standing for 5 minutes; it is discharged at a constant current of 0.33C to the cut-off voltage of 2.5V, and the discharge capacity at this time is recorded to obtain the discharge energy E0. The volume energy density (Wh / L) = discharge energy E0 / monomer volume (L).

[0301] 4. Cycle performance

[0302] At 25°C, it is charged at a charging rate of 0.5C to 3.65V, then charged at a constant voltage of 3.65V until the current reaches 0.05C, left standing for 10 minutes, and then discharged at a discharge rate of 1C to 2.5V, left standing for 10 minutes. One such charge-discharge cycle is counted as one cycle, and the test is stopped until the battery capacity decays to 80% of the nominal capacity, denoted as the cycle count @80% SOH.

[0303] II. Analysis of test results of each example and comparative example

[0304] The battery cells of each example and comparative example were prepared respectively according to the above method, and various performance parameters were measured. The results are shown in Tables 1 to 5 below.

[0305] Table 1 Electrode sheet preparation parameters

[0306]

[0307] Table 2 Electrode sheet preparation parameters

[0308]

[0309] Table 3 Electrolyte preparation parameters

[0310]

[0311] Table 4 Electrolyte preparation parameters

[0312]

[0313] Table 5 Battery performance parameters

[0314]

[0315] In the battery cells of Examples 1 to 11, the areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2; Along the first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm; Therefore, the battery monomers prepared in Examples 1 to 11 all have excellent fast charging performance, energy density, cycle performance, and low DC internal resistance.

[0316] For Comparative Examples 1 to 2, the difference between the sizes W2 and W1 of the positive and negative electrode film layers exceeds the range of 3 mm to 5 mm. Among them: in Comparative Example 1, the difference between W2 and W1 is too small, while in Comparative Example 2, the difference between W2 and W1 is too large.

[0317] From the comparison between Comparative Examples 1 to 2 and Examples 1 to 11, it can be seen that when the difference between the sizes W2 and W1 of the positive and negative electrode film layers is below the range of 3 mm, the cycle performance of the battery monomer will deteriorate; while when the difference between the sizes W2 and W1 of the positive and negative electrode film layers is greater than the range of 5 mm, the energy density of the battery monomer will deteriorate; Therefore, the difference between the sizes W2 and W1 of the positive and negative electrode film layers needs to be in the range of 3 mm to 5 mm to balance the improvement of the cycle performance and energy density of the battery. When it exceeds this range, the comprehensive performance of the battery is poor.

[0318] For Comparative Examples 3 to 4, the areal density of the positive and negative electrode film layers exceeds 0.33 g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 、0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 respectively. Among them: in Comparative Example 3, the areal density of the single-sided positive electrode film layer and the single-sided negative electrode film layer is too large, while in Comparative Example 4, the areal density of the single-sided positive electrode film layer and the single-sided negative electrode film layer is too small.

[0319] From the comparison between Comparative Examples 3 to 4 and Examples 1 to 11, it can be seen that when the areal density of the positive and negative electrode film layers is too large, the fast charging performance, DC internal resistance, and cycle performance of the battery monomer will deteriorate; while when the areal density of the positive and negative electrode film layers is too small, the energy density of the battery monomer will deteriorate; Therefore, when the areal density of the positive and negative electrode film layers is respectively in the range of 0.33 g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 、0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 respectively, it can balance the improvement of the fast charging performance, DC internal resistance, cycle performance, and energy density of the battery. When it exceeds this range, the comprehensive performance of the battery is poor.

[0320] In Examples 1 to 3, the difference between the sizes W2 and W1 of the positive and negative electrode film layers is in the range of 3 mm to 5 mm. The prepared battery cells can take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance. In addition, the results also show that when the difference between W2 and W1 gradually increases within the range of 3 mm to 5 mm, the cycling performance, fast charging performance, and DC internal resistance of the battery are improved to a certain extent, but the energy density decreases to a certain extent; when the difference between W2 and W1 gradually decreases within the range of 3 mm to 5 mm, the energy density of the battery is improved to a certain extent, but the improvement in cycling performance, fast charging performance, and DC internal resistance is limited.

[0321] In Examples 1, 4 to 6, the areal densities of the positive and negative electrode film layers are respectively in the range of 0.33 g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 and 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 The prepared battery cells can take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance. In addition, the results also show that when the areal densities of the positive and negative electrode film layers gradually decrease within the above range, the cycling performance, fast charging performance, and DC internal resistance of the battery are improved to a certain extent, but the energy density decreases to a certain extent; when the areal densities of the positive and negative electrode film layers gradually increase within the above range, the energy density of the battery is improved to a certain extent, but the improvement in cycling performance, fast charging performance, and DC internal resistance is limited.

[0322] Therefore, it can be seen from the results of Examples 1 to 6 that the difference between the sizes W2 and W1 of the positive and negative electrode film layers needs to be in the range of 3 mm to 5 mm, and it needs to be combined with the areal densities of the positive and negative electrode film layers being respectively in the range of 0.33 g / 1540.25mm 2 to 0.4 g / 1540.25mm 2 and 0.15 g / 1540.25mm 2 to 0.19 g / 1540.25mm 2 so as to take into account the improvement of the energy density, fast charging performance, cycling performance, and DC internal resistance of the battery and enable the battery to have excellent comprehensive performance.

[0323] In Examples 1, 7 to 10, the electrolyte adopted the following formulation, and the battery monomers prepared therefrom could take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance: The organic solvent adopted a linear carboxylic acid ester (such as ethyl acetate) with a mass fraction of 40% to 75%, a linear carbonate (such as DMC, EMC) with a mass fraction of 10% to 40%, and a cyclic carbonate (such as ethylene carbonate), wherein the mass fraction of dimethyl carbonate was 5% to 15%, and the mass ratio of the linear carboxylic acid ester (such as ethyl acetate) to dimethyl carbonate was 2.0 to 7.0; The lithium salt adopted LiPF6 and LiFSI with a mass fraction of 13% to 20%, and the mass ratio of LiPF6 to LiFSI was 1.2:1 to 2:1.

[0324] At the same time, by comparing Examples 1, 7, and 8, it can be seen that: as the proportion of the linear carboxylic acid ester (such as ethyl acetate) and LiFSI added to the electrolyte gradually increases, the fast charging performance and DC internal resistance of the battery are further improved; while as the proportion of the linear carbonate (such as DMC) and LiPF6 added to the electrolyte gradually increases, the cycling performance of the battery is further improved.

[0325] At the same time, by comparing Examples 1, 9, and 10, it can be seen that: when only the linear carboxylic acid ester (such as ethyl acetate) exists in the organic solvent of the electrolyte and no carbonate exists, and only LiFSI exists in the lithium salt and no LiPF6 exists, the fast charging performance and DC internal resistance of the battery are further improved, but the cycling performance of the battery is poor; when only the linear carbonate (such as DMC) exists in the organic solvent of the electrolyte and no linear carboxylic acid ester exists, and only LiPF6 exists in the lithium salt and no LiFSI exists, the cycling performance of the battery is further improved, but the improvement of the fast charging performance and DC internal resistance is limited. Therefore, when the linear carbonate and linear carboxylic acid ester with the above mass ratio are used as the organic solvent in the electrolyte at the same time, and LiPF6 and LiFSI with the above mass ratio are used as the lithium salt at the same time, through the mutual combination of various solvents and lithium salts, the fast charging performance, DC internal resistance, and cycling performance of the battery can be further taken into account and improved, making the comprehensive performance of the battery better.

[0326] In Examples 1 and 11, the negative electrode film layer includes at least one layer of graphite as the negative electrode active material, and its average particle size Dv50 is within the range of 8μm to 15μm. The battery cells prepared therefrom can achieve excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. In addition, a comparison between Example 1 and Example 11 shows that when the negative electrode film layer includes two layers of artificial graphite with different particle sizes as the negative electrode active material layers (the first negative electrode active material layer is disposed on the surface of the negative electrode current collector, and the second negative electrode active material layer is disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, and the Dv50 of the first negative electrode active material layer is greater than the Dv50 of the second negative electrode active material layer), it can further improve the battery's fast charging performance and DC internal resistance, thereby improving the battery's overall performance.

[0327] In Examples 1 to 11, Figure 2 As shown, in the cross-section of the positive electrode film layer along the thickness direction, the lithium phosphate in the positive electrode film layer includes first lithium-containing phosphate particles with a maximum diameter of 0.05μm to 0.3μm and second lithium-containing phosphate particles with a maximum diameter of 1μm to 3μm. The battery cells prepared therefrom can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance.

[0328] In Examples 1 to 11, when the ratio of the thickness of the negative electrode film layer on one side to the thickness of the negative electrode current collector is in the range of 12 to 20, or the compaction density of the positive electrode sheet is 2.3 g / cm 3 Up to 2.6g / cm 3 When the compaction density of the negative electrode is 1.3g / cm 3 Up to 1.6g / cm 3 The battery cells prepared therefrom can have excellent energy density, fast charging performance, cycle performance, and low DC internal resistance.

[0329] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, characterized in that, It includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive current collector and a positive electrode film layer provided on at least one side of the positive current collector. The negative electrode sheet includes a negative current collector and a negative electrode film layer provided on at least one side of the negative current collector. Among them, The positive electrode film layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and the areal density of the single-sided positive electrode film layer is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 ; the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.19 g / 1540.25 mm 2 ; the positive current collector includes a positive current collecting portion and at least two positive electrode tabs provided on the same side of the positive current collecting portion. The positive electrode tabs extend from the positive current collecting portion along a first direction; the negative current collector includes a negative current collecting portion and at least two negative electrode tabs provided on the same side of the negative current collecting portion. The negative electrode tabs extend from the negative current collecting portion along the first direction; along the first direction, the size of the positive electrode film layer is W1 mm, and the size of the negative electrode film layer is W2 mm, where W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

2. The battery cell according to claim 1, characterized in that, The areal density of the single-sided positive electrode film layer is 0.335 g / 1540.25 mm 2 to 0.38 g / 1540.25 mm 2 , and the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25 mm 2 to 0.165 g / 1540.25 mm 2 .

3. The battery cell according to claim 1, wherein, The tap density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 .

4. The battery cell according to claim 1, characterized in that, The compaction density of the positive electrode sheet is 2.4 g / cm 3 to 2.55 g / cm 3 .

5. The battery cell according to claim 1, characterized in that, The compaction density of the negative electrode plate is 1.3 g / cm 3 to 1.6 g / cm 3 .

6. The battery cell according to claim 1, characterized in that, The compaction density of the negative electrode plate is 1.35 g / cm 3 to 1.55 g / cm 3 .

7. The battery cell according to claim 1, characterized in that, The negative electrode film layer includes a negative electrode active material. The average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, and the negative electrode active material includes graphite.

8. The battery cell according to claim 7, wherein The average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm.

9. The battery cell according to claim 7 or 8, characterized in that, The graphitization degree of the negative electrode active material is 90% - 95%.

10. The battery cell according to claim 7 or 8, characterized in that, The graphitization degree of the negative electrode active material is 92% - 95%.

11. The battery cell according to claim 1, characterized in that, The negative electrode film layer includes a first negative electrode active material layer provided on the surface of the negative current collector and a second negative electrode active material layer provided on the side of the first negative electrode active material layer away from the negative current collector. The negative electrode active material in the first negative electrode active material layer includes first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes second artificial graphite. The average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

12. The battery cell according to claim 11, wherein, The average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

13. The battery cell according to claim 11, characterized in that, The average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

14. The battery cell according to claim 11, characterized in that, The average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

15. The battery cell according to claim 1, wherein, The thickness of the negative current collector is 4 - 6 μm.

16. The battery cell according to claim 1, wherein The ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative current collector is 12 to 20.

17. The battery cell according to claim 1, wherein The ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative current collector is 13 to 20.

18. The battery cell according to claim 1, wherein The battery cell includes an electrolyte. The electrolyte contains an organic solvent, and the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

19. The battery cell according to claim 18, wherein, The organic solvent includes a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester is 40% to 75% based on the total mass of the electrolyte.

20. The battery cell according to claim 19, characterized in that, The linear carboxylic acid ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include one or more of C1 - C5 alkyl groups and C1 - C5 haloalkyl groups.

21. The battery cell according to claim 20, characterized in that, The linear carboxylic acid ester includes one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

22. The battery cell according to any one of claims 18 to 21, characterized in that The organic solvent includes a carbonate solvent. The carbonate solvent includes a linear carbonate and a cyclic carbonate. Based on the total mass of the electrolyte, the mass ratio of the linear carbonate is 10% to 40%.

23. The battery cell according to claim 22, wherein, The cyclic carbonate includes one or more of ethylene carbonate and propylene carbonate, and the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

24. The battery cell according to claim 23, wherein The linear carbonate includes dimethyl carbonate, and based on the total mass of the electrolyte, the mass fraction of dimethyl carbonate is 5% to 15%.

25. The battery cell according to claim 18, wherein, The electrolyte includes dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to dimethyl carbonate is 2.0 to 7.

0.

26. The battery cell according to claim 25, characterized in that, The mass ratio of the linear carboxylic acid ester to dimethyl carbonate is 3.0 to 6.

0.

27. The battery cell according to claim 18, wherein, The electrolyte includes a lithium salt, and based on the total mass of the electrolyte, the mass fraction of the lithium salt is 13% to 20%.

28. The battery cell according to claim 27, wherein The lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorosulfonimide salts, and the fluorosulfonimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

29. The battery cell according to claim 27, wherein The lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI.

30. The battery cell according to claim 29, wherein, In the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:

1.

31. The battery cell according to claim 18, wherein The electrolyte further contains an additive, and the additive contains a carbonate additive.

32. The battery cell according to claim 31, wherein, Based on the total mass of the electrolyte, the mass fraction of the carbonate additive in the electrolyte is 0.5% to 7%.

33. The battery cell according to claim 31 or 32, characterized in that, The carbonate additive includes vinylene carbonate VC and fluoroethylene carbonate FEC.

34. The battery cell according to claim 31 or 32, characterized in that, The additive includes vinylene carbonate VC; based on the total mass of the electrolyte, the mass fraction of vinylene carbonate VC in the electrolyte is 0.5% to 2%.

35. The battery cell according to claim 31 or 32, characterized in that, The additive includes fluoroethylene carbonate FEC; based on the total mass of the electrolyte, the mass fraction of fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1%.

36. The battery cell according to claim 1, characterized in that, The lithium-containing phosphate has a general formula shown in Formula I. Li x A y Me a M b P 1-c X c Y z Formula I Wherein, 0.1 ≤ x ≤ 1.3, 0 ≤ y ≤ 1.3, and 0.9 ≤ x + y ≤ 1.3; 0.9 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.5, and 0.9 ≤ a + b ≤ 1.5; 0 ≤ c ≤ 0.5; 3 ≤ z ≤ 5; A includes one or several of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

37. The battery cell according to claim 36, wherein, M includes one or more of Al, Ti, V, and Mg.

38. The battery cell according to claim 36 or 37, characterized in that, The positive electrode active material satisfies at least one of the following: (1) The positive electrode active material contains Al element, and the mass content is 0.01% to 0.05% based on the total mass of the positive electrode active material. (2) The positive electrode active material contains Ti element with a mass content of 0.01% to 0.03% based on the total mass of the positive electrode active material; (3) The positive electrode active material contains V element with a mass content of 0.1% to 0.3% based on the total mass of the positive electrode active material; (4) The positive electrode active material contains Mg element with a mass content of 0.001% to 0.01% based on the total mass of the positive electrode active material.

39. The battery cell according to claim 1, wherein, In the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate includes first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm.

40. The battery cell according to claim 39, wherein In the cross-section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

41. The battery cell according to claim 1, wherein the distance between the center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction; and / or, the distance between the center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction.

42. The battery cell according to claim 41, wherein the distance between the center lines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or, the distance between the center lines of two adjacent negative electrode tabs is 20 mm to 330 mm.

43. The battery cell according to claim 41, wherein The battery cell further includes a top cover, and the top cover includes a positive electrode terminal and a negative electrode terminal with opposite polarities. The positive electrode terminal and the negative electrode terminal are respectively used for electrically connecting with the positive electrode tab and the negative electrode tab.

44. The battery cell according to claim 1, characterized in that, The housing of the battery is square, and the thickness of the housing is 30 mm to 55 mm, the width is 150 mm to 250 mm, and the height is 90 mm to 120 mm.

45. The battery cell according to claim 1, characterized in that, The battery cell is configured to have a charging time of 10 to 17 minutes for charging from 10% SOC to 80% SOC at room temperature.

46. A battery device, characterized in that, The battery device includes at least one of a battery module, a battery pack, and an energy storage device, which includes the battery cell according to any one of claims 1 to 45.

47. An electrical device, characterized in that, The battery device includes the battery cell according to any one of claims 1 to 45 or the battery device according to claim 46.

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