Battery monomer, battery device and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device. In the battery monomer, a positive electrode active material comprises lithium-containing phosphate with an olivine structure; the average particle size Dv50 of the negative electrode active material is 8-15 [mu] m, and the negative electrode active material comprises graphite; the electrolyte comprises a carbonic ester additive, the carbonic ester additive comprises fluoroethylene carbonate (FEC) and vinylene carbonate (VC), and based on the total mass of the electrolyte, the mass ratio of the carbonic ester additive is 0.5%-7%.

Description

[0001] Cross - Reference to Related Applications This application claims the priority of PCT patent application PCT / CN2024 / 116546 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

[0002] This application relates to the technical field of batteries, and in particular to a battery cell, a battery device and an electrical device. Background Art

[0003] 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 multiple 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, cycling performance, service life, safety performance, etc. Summary of the Invention

[0004] The purpose of this application is to provide a new type of battery cell, which has excellent fast charging performance and also takes into account having a relatively high energy density, good cycling performance, and low DC internal resistance.

[0005] To achieve the above object, the first aspect of this application provides a battery cell, including a positive electrode tab, a negative electrode tab, an electrolyte, and a separator located between the positive electrode tab and the negative electrode tab. The positive electrode tab includes a negative current collector and a positive electrode film layer provided on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a lithium-containing phosphate in an olivine structure; the negative electrode tab includes a negative current collector and a negative electrode film layer provided on at least one surface of the negative current collector. The negative electrode film layer includes a negative electrode active material, and the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm. The negative electrode active material includes graphite; the electrolyte includes a carbonate additive, and the carbonate additive includes fluoroethylene carbonate FEC and vinylene carbonate VC; based on the total mass of the electrolyte, the mass ratio of the carbonate additive is 0.5% to 7%.

[0006] The battery charging process is a process in which lithium ions are removed from the positive electrode active material and embedded inside the negative electrode active material. And during fast charging, the embedding ability of lithium ions in the negative electrode active material becomes the bottleneck restricting the improvement of the battery's fast charging ability. In this application, by using a negative electrode active material with a small particle size, the transmission path of lithium ions in the negative electrode active material is reduced, the embedding difficulty of lithium ions in the negative electrode active material is reduced, the lithium deposition during the fast charging process of the battery is slowed down, the charging time of the battery is reduced, the internal resistance of the battery is reduced, the battery temperature rise during the fast charging process is reduced, and the battery safety performance is improved; However, when the particle size of the negative electrode active material is small, the corresponding specific surface area is large, which increases the contact area between the negative electrode active material and the electrolyte and increases the side reactions at the phase interface. Therefore, it is necessary to optimize the composition of the solid electrolyte interface membrane (Solid Electrolyte Interface membrane, SEI membrane) of the negative electrode active material. In this application, by introducing a higher content of the carbonate-based electrolyte film-forming additives fluoroethylene carbonate FEC and vinylene carbonate VC and reasonably controlling the content to optimize the composition of the negative electrode SEI membrane, on the one hand, the film-forming rate and film-forming quality of the SEI membrane are higher, timely and efficiently hindering the side reactions between the negative electrode active material and the electrolyte, improving the cycle performance of the battery, and on the other hand, reducing the film impedance of the SEI membrane, further improving the fast charging performance of the battery and reducing the internal resistance of the battery.

[0007] In the battery cell provided by this application, a carbonate-based additive with a mass ratio within the above range, such as fluoroethylene carbonate and vinylene carbonate, is also added to the electrolyte, which can form an SEI membrane on the surface of the negative electrode, thereby reducing the side reactions occurring between the graphite with a particle size within the above range and the electrolyte, and further enabling the battery to have good cycle performance.

[0008] In any implementation manner, the average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm.

[0009] 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 further take into account improving the cycle performance of the battery.

[0010] In any implementation manner, the specific surface area of the negative electrode active material is 3 m 2 / g to 8 m 2 / g.

[0011] In any implementation manner, the specific surface area of the negative electrode active material is 4 m 2 / g to 6 m 2 / g.

[0012] When the negative electrode active material (such as graphite) has a specific surface area within the above range, it can further accelerate the intercalation and deintercalation rate of lithium ions between graphite layers, thereby further improving the fast charging performance of the battery.

[0013] In any embodiment, the electrolyte includes vinylene carbonate (VC), and the mass ratio of vinylene carbonate (VC) in the electrolyte is 0.5% to 2% based on the total mass of the electrolyte.

[0014] 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.

[0015] In any embodiment, the electrolyte includes fluoroethylene carbonate (FEC), and the mass ratio of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 1% based on the total mass of the electrolyte.

[0016] 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.

[0017] In any embodiment, the electrolyte further contains an organic solvent, and the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0018] In the battery cell provided by the present application, when the above type of organic solvent is used in the electrolyte, the kinetic performance of the battery can be further improved.

[0019] 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.

[0020] In any embodiment, the linear carboxylic acid ester has the structural general formula of R 1 -COO-R 2 wherein R 1 and R 2 each independently includes one or more of an alkyl group of C 1 ~C 5 and a haloalkyl group of C 1 ~C 5

[0021] 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.

[0022] ​When the above types and mass ratios of linear carboxylic esters are used as organic solvents in the electrolyte, due to the low viscosity of linear carboxylic esters, the electrolyte conductivity can be effectively improved, thereby further improving the fast charging performance of the battery.

[0023] In any embodiment, the organic solvent includes a carbonate solvent, the carbonate solvent includes a linear carbonate and a cyclic carbonate, and the mass ratio of the linear carbonate is 10% to 40% based on the total mass of the electrolyte.

[0024] 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 methyl ethyl carbonate.

[0025] In any embodiment, the linear carbonate includes dimethyl carbonate, and the mass ratio of dimethyl carbonate is 5% to 15% based on the total mass of the electrolyte.

[0026] When the above types and mass ratios of carbonates are used as organic solvents in the electrolyte, side reactions and gas generation during battery cycling can be improved, so that the battery can simultaneously have good cycling performance.

[0027] In any embodiment, the organic solvent includes dimethyl carbonate and a linear carboxylic ester, and the mass ratio of the linear carboxylic ester to dimethyl carbonate is 2.0 to 7.0.

[0028] In any embodiment, the mass ratio of the linear carboxylic ester to dimethyl carbonate is 3.0 to 6.0.

[0029] When dimethyl carbonate and a linear carboxylic ester with the above mass ratio are simultaneously used as organic solvents in the electrolyte, by combining the two solvents, the fast charging performance and cycling performance of the battery can be further improved.

[0030] In any embodiment, the electrolyte further includes a lithium salt, and the mass ratio of the lithium salt is 13% to 20% based on the total mass of the electrolyte.

[0031] In any embodiment, the lithium salt includes at least two of lithium hexafluorophosphate LiPF 6 and fluorosulfonimide salts, and the fluorosulfonimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0032] Lithium hexafluorophosphate is not prone to gas generation during cycling and can further improve the cycling performance of the battery; while fluorosulfonimide salts have strong dissociation ability and can further improve the fast charging performance of the battery.

[0033] In any embodiment, the lithium salt includes lithium hexafluorophosphate LiPF 6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0034] In any embodiment, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF 6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:1.

[0035] 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.

[0036] In any embodiment, the general formula of the lithium-containing phosphate with olivine structure is shown as Formula I, Li x A y Me a M b P 1-c X c Y z Formula I, 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.

[0037] 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.

[0038] In any embodiment, M includes one or more of Al, Ti, V, and Mg.

[0039] In any embodiment, the positive electrode active material satisfies at least one of the following conditions: (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, and the mass content is 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, and the mass content is 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, and the mass content is 0.001 to 0.01%, based on the total mass of the positive electrode active material.

[0040] When the lithium-containing phosphate as the positive electrode active material contains elements such as Al, Ti, V, and Mg, its specific capacity can be further improved.

[0041] In any embodiment, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate with olivine structure includes a first lithium-containing phosphate particle with a longest diameter of 0.05 μm to 0.3 μm and a second lithium-containing phosphate particle with a longest diameter of 1 μm to 3 μm.

[0042] In the battery cell provided by the present application, when the positive electrode active material contains 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.

[0043] In the battery cell provided by the present application, when the lithium-containing phosphate as the positive electrode active material contains both a first lithium-containing phosphate particle with a longest diameter of 0.05 μm to 0.3 μm and a second lithium-containing phosphate particle with a 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.

[0044] 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.

[0045] In the lithium-containing phosphate as the positive electrode active material, when the number of the first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles with a 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.

[0046] In any embodiment, the tap density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 .

[0047] In any embodiment, the tap density of the positive electrode sheet is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0048] When the compaction density of the positive electrode sheet is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0049] In any embodiment, 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 .

[0050] In any embodiment, 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 .

[0051] 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 further improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby further improving the fast charging performance of the battery.

[0052] In any embodiment, the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

[0053] In any embodiment, the compaction density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

[0054] 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 kinetic performance.

[0055] In any embodiment, 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 .

[0056] In any embodiment, 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 .

[0057] In the battery cell provided by the present application, when the coating areal density of the negative electrode film layer is within the above range, the energy density of the battery can be further improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby further improving the fast charging performance of the battery.

[0058] In any embodiment, the thickness of the negative current collector is less than or equal to 4 - 6 μm.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] In any embodiment, the negative electrode current collector includes a negative electrode current collecting portion, the negative electrode film layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collecting portion 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 collecting portion. The negative electrode active material in the first negative electrode active material layer includes first artificial graphite, the negative electrode active material in the second negative electrode active material layer includes 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.

[0063] In any embodiment, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

[0064] In any embodiment, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

[0065] In any embodiment, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

[0066] 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.

[0067] In any embodiment, the positive electrode current collector includes a positive electrode current collecting portion and at least two positive electrode tabs disposed 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 center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center line is parallel to the first direction; and / or, 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. The negative electrode tabs extend from the negative electrode current collecting portion along a first direction. Among them, the distance between the center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the center line is parallel to the first direction.

[0068] In any embodiment, the distance between the centerlines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or, the distance between the centerlines of two adjacent negative electrode tabs is 20 mm to 330 mm.

[0069] 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 DC internal resistance of the battery cell, thereby further reducing the heat generation of the battery and making the battery have better safety performance.

[0070] In any embodiment, the battery cell further includes a top cover, the top cover includes a positive electrode terminal and a negative electrode terminal with opposite polarities, and 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.

[0071] In a conventional battery, a connecting piece is required to connect the electrode terminal and the tab, but this will reduce the utilization rate of the electrode assembly and the battery energy density. When the above structure is adopted in the battery cell provided by the present application, canceling the setting of the connecting piece can effectively solve this problem, reduce the battery internal resistance, and further take into account improving the battery energy density and fast charging performance.

[0072] In any embodiment, the size of the positive electrode film layer in the first direction is W 1 mm, the size of the negative electrode film layer in the first direction is W 2 mm, where W 2 > W 1 and the difference between W 2 and W 1 is 3 mm to 5 mm.

[0073] During the cycling of the battery, lithium ions that cannot be embedded in 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 W 2 of the negative electrode film layer and the size W 1 of the positive electrode film layer have the above relationship, it can improve the formation of lithium dendrites on the surface of the negative electrode by lithium ions, thereby further improving the cycling performance of the battery.

[0074] In any embodiment, the battery cell further includes a housing, the housing 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.

[0075] 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.

[0076] The battery cell provided by this application has excellent fast charging performance.

[0077] The second aspect of this application further provides a battery device, including the battery cell of the first aspect of this application, and the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0078] The third aspect of this application further provides an electrical device, including the battery cell of the first aspect of this application or the battery device of the second aspect of this application. Description of the Drawings

[0079] Figure 1 One of the schematic diagrams of the size of the electrode sheet film layer in an embodiment of this application; Figure 2 Another schematic diagram of the size of the electrode sheet film layer in an embodiment of this application; Figure 3 Another schematic diagram of the size of the electrode sheet film layer in an embodiment of this application; Figure 4 The electron microscope observation result diagram of the longitudinal section of the positive electrode sheet in an embodiment of this application; Figure 5 The schematic diagram of the electrode sheet in an embodiment of this application; Figure 6 The exploded view of the battery cell in an embodiment of this application; Figure 7 One of the schematic diagrams of the battery cell in an embodiment of this application; Figure 8 Another schematic diagram of the battery cell in an embodiment of this application; Figure 9 Another schematic diagram of the battery cell in an embodiment of this application; Figure 10 The schematic diagram of the battery cell in an embodiment of this application; Figure 11 is Figure 10 The exploded view of the battery cell shown in an embodiment of this application; Figure 12 The schematic diagram of the battery module in an embodiment of this application; Figure 13 The schematic diagram of the battery pack in an embodiment of this application; Figure 14 is Figure 13 The exploded view of the battery pack shown in an embodiment of this application; Figure 15 The schematic diagram of the electrical device using the battery cell as a power source in an embodiment of this application.

[0080] Description of the Reference Numerals: 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; W 1 Dimension of the positive electrode film layer in the first direction; W 2 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

[0081] 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 details 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 prevent the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions 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.

[0082] 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 particular range. The ranges 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 stated, 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.

[0083] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0084] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0085] 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 also 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 also include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

[0086] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present application mean open-ended or may also be closed-ended. For example, the "comprising" and "including" may mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0087] 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).

[0088] In recent years, with the increasing demand for batteries as an energy source, higher requirements have been put forward for the fast charging performance of batteries. However, fast charging batteries will release a large amount of heat in a short time during charging, which may pose certain safety hazards. Therefore, if it is possible to improve the battery's DC impedance and cycling performance while improving the battery's kinetic performance, the overall performance of the battery can be further improved.

[0089] To solve the above problems, the present application provides a battery cell, comprising a positive electrode plate, a negative electrode plate, an electrolyte, and a separator located between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive current collector and a positive electrode film layer provided on at least one surface of the positive current collector. The positive electrode film layer includes a positive active material, and the positive active material includes a lithium-containing phosphate in an olivine structure. The negative electrode plate includes a negative current collector and a negative electrode film layer provided on at least one surface of the negative current collector. The negative electrode film layer includes a negative active material, and the average particle size Dv50 of the negative active material is 8 μm to 15 μm. The negative active material includes graphite. The electrolyte includes a carbonate additive, and the carbonate additive includes fluoroethylene carbonate FEC and vinylene carbonate VC. Based on the total mass of the electrolyte, the mass percentage of the carbonate additive is 0.5% to 7%.

[0090] In some embodiments, the "average particle size Dv50" means: 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 be measured using a Malvern 2000 (MasterSizer 2000) laser particle size analyzer.

[0091] In the embodiments of the present application, the types and contents of the organic components in the electrolyte have meanings well-known in the art and can be detected using equipment and methods well-known in the art. For example, the composition of the electrolyte 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 electrolyte can be performed by gas chromatography with reference to GB / T9722-2006 "General Rules for Chemical Reagents - Gas Chromatography".

[0092] The test sample in the embodiments of the present application can take the newly prepared electrolyte as the sample, or the free electrolyte obtained from the battery after discharging the battery (discharging to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) as the sample.

[0093] In the embodiments of the present application, the types and contents of inorganic components / lithium salt concentration in the electrolyte have the meanings well-known in the art, and can be detected by using the equipment and methods well-known in the art. For example, reference can be made to the standard JY / T 020-1996 General Rules for Ion Chromatographic Analysis Methods to qualitatively or quantitatively analyze the inorganic components / lithium salt concentration in the electrolyte by ion chromatography analysis method. In the embodiments of the present application, newly prepared electrolyte can be taken as a sample, or the battery can be discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC), and the free electrolyte obtained from the battery can be taken as a sample, and detected by ion chromatography analysis method.

[0094] The battery charging process is a process in which lithium ions are removed from the positive electrode active material and embedded inside the negative electrode active material. And during fast charging, the embedding ability of lithium ions in the negative electrode active material becomes a bottleneck restricting the improvement of the battery's fast charging ability. The present application uses a negative electrode active material with a small particle size to reduce the transmission path of lithium ions in the negative electrode active material, reduce the embedding difficulty of lithium ions in the negative electrode active material, slow down the lithium deposition during the fast charging process of the battery, reduce the charging time of the battery, and reduce the internal resistance of the battery, reduce the battery temperature rise during the fast charging process, and improve the battery safety performance; however, when the particle size of the negative electrode active material is small, the corresponding specific surface area is large, which increases the contact surface between the negative electrode active material and the electrolyte and increases the side reactions at the phase interface. Therefore, it is necessary to optimize the SEI film components of the negative electrode active material. The present application optimizes the negative electrode SEI film composition by introducing a higher content of carbonate-based electrolyte film-forming additives FEC and VC and reasonably controlling the content. On the one hand, the film-forming rate and film-forming quality of the SEI film are higher, which can timely and efficiently hinder the side reactions between the negative electrode active material and the electrolyte and improve the cycle performance of the battery. On the other hand, the film impedance of the SEI film is reduced, further improving the fast charging performance of the battery and reducing the internal resistance of the battery.

[0095] [Negative electrode plate] In some embodiments, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed 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 layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0096] In some embodiments, the negative electrode film layer includes a negative electrode active material.

[0097] 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 unlisted values within the range of 8 μm to 15 μm. In some embodiments, the negative electrode active material includes graphite.

[0098] 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 for lithium ions between the graphite layers 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 the heat generation of the battery and enabling the battery to have good safety performance.

[0099] In some embodiments, the average particle size Dv50 of the negative electrode active material is from 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.

[0100] 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.

[0101] In some embodiments, the specific surface area of the negative electrode active material is 3 m 2 / g to 8 m 2 / g, such as 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, etc., or other values not listed within the range of 3 m 2 / g to 8 m 2 / g.

[0102] In some embodiments, the specific surface area of the negative electrode active material is 4 m 2 / g to 6 m 2 / g, such as 4 m 2 / g, 4.5 m 2 / g, 5 m 2 / g, 5.5 m 2 / g, 6 m 2 / g, etc., or other values not listed within the range of 4 m 2 / g to 6 m 2 / g.

[0103] As used herein, "specific surface area" refers to the total area per unit mass of a material. The measurement method can refer to GB / T 19587-2017, and the nitrogen adsorption specific surface area analysis test method is used for testing and calculated by the BET (Brunauer Emmett Teller) method. Among them, the nitrogen adsorption specific surface area analysis test can be carried out by a Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics Company in the United States.

[0104] As a negative electrode active material, for example, graphite, when it has a specific surface area within the above range, it can further accelerate the insertion and extraction rate of lithium ions between the graphite layers, thereby further improving the fast charging performance of the battery.

[0105] In some embodiments, the negative electrode film layer includes at least two negative electrode active material layers. In some embodiments, the negative electrode current collector includes a negative electrode current collecting portion, the negative electrode film layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collecting portion 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 collecting portion. 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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).

[0111] 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.

[0112] In some embodiments, the negative electrode film layer may further optionally include other additives, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0113] In some embodiments, 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 , 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 .

[0114] In some embodiments, the areal density of the single-sided negative electrode film layer is 0.15 g / 1540.25mm 2 to 0.165 g / 1540.25mm 2 .

[0115] 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 plate (if it is a double-sided coated negative electrode plate, 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 plate and weigh the weight of the negative electrode current collector, record it as M0. The areal density of the negative electrode film layer = (the weight M1 of the negative electrode plate - the weight M0 of the negative electrode current collector) / S1. To ensure the accuracy of the test results, multiple groups (e.g., 10 groups) of samples to be tested can be tested, and the average value can be calculated as the test result.

[0116] In the battery cell provided by the present application, when the coating areal density of the negative electrode film layer is within the above range, the energy density of the battery can be further improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby further improving the fast charging performance of the battery.

[0117] 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 can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can 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.).

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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 in which the battery cell is discharged to 2.0 V at 1 / 3 C and then discharged to 2.0 V at 0.05 C.

[0122] 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 improvement of the energy density and the fast charging performance of the battery can be further balanced.

[0123] In some embodiments, in combination with Figure 5As 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. Among them, the distance between the centerlines L of two adjacent tabs 11b is 10 mm to 350 mm, and the centerline 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 values not listed within the range of 10 mm to 350 mm.

[0124] In some embodiments, the distance between the centerlines L of two adjacent tabs 11b is 20 mm to 330 mm, and the centerline 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 values not listed within the range of 20 mm to 330 mm.

[0125] In some embodiments, in combination with Figure 5 and Figure 6 as shown, the current collector 1 may be a positive current collector, and the tab 11b may be a positive tab 111b.

[0126] In some embodiments, in combination with Figure 5 and Figure 6 as shown, the current collector 11 may be a negative current collector, and the tab 11b may be a negative tab 112b.

[0127] In some embodiments, the negative current collector includes a negative current collecting portion and at least two negative tabs provided on the same side of the negative current collecting portion. The negative tabs extend from the negative current collecting portion along a first direction. Among them, the distance between the centerlines of two adjacent negative 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 values not listed within the range of 10 mm to 350 mm.

[0128] In some embodiments, the distance between the centerlines of two adjacent negative electrode tabs is from 20 mm to 330 mm, 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 values not listed within the range of 20 mm to 330 mm.

[0129] In some embodiments, in combination with Figure 5 and Figure 6 as shown, the centerline L refers to the symmetry axis passing through the midpoint of the current collector 11 along the length direction of the tab 11b, 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.

[0130] In some embodiments, in combination with Figure 5 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), or S1 and S2 may not be equal (in this case, the adjacent tabs are not equally spaced).

[0131] 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.

[0132] In some embodiments, the negative electrode plate can be prepared in the following manner: dispersing the 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.

[0133] In some embodiments, the compaction density of the negative electrode plate 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 values not listed within the range of 1.3 g / cm 3 to 1.6 g / cm 3 .

[0134] In some embodiments, the compaction density of the negative electrode plate is 1.35 g / cm3 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 and so on, or other unlisted values within the range of 1.35 g / cm 3 to 1.55 g / cm 3 within the range.

[0135] In some embodiments, the compaction density of the negative electrode tab corresponds to the compaction 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 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.

[0136] When used herein, the "compaction density" of the electrode tab is: compaction density = areal density / (electrode tab thickness - current collector thickness), and the measurement method can refer to GB / T24533-2009.

[0137] When the compaction 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.

[0138] [Positive electrode tab] 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.

[0139] In some embodiments, the positive electrode film layer includes a positive active material.

[0140] In some embodiments, the positive active material includes a lithium-containing phosphate with an olivine structure.

[0141] In some embodiments, the general formula of the lithium-containing phosphate with an olivine structure is shown in Formula I, Li x A y Me a M b P 1-c X c Y z Formula I, Among them, 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.

[0142] 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 defined 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 cathode active materials. The aforementioned appropriate modification refers to the acceptable modification methods for cathode active materials, and non-limiting examples include coating modification.

[0143] 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.

[0144] In some embodiments, M includes one or more of Al, Ti, V, and Mg.

[0145] 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.

[0146] 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.

[0147] In some embodiments, the positive electrode active material contains V element, and its mass content is 0.001% - 0.3%, optionally 0.1 - 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% - 0.3%, based on the total mass of the positive electrode active material.

[0148] In some embodiments, the positive electrode active material contains Mg element, and the mass content is 0.001% - 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% - 0.01%, based on the total mass of the positive electrode active material.

[0149] When the lithium-containing phosphate as the positive electrode active material contains elements such as Al, Ti, V, Mg, etc., it can further improve the structural stability of the material and enhance the cycling performance.

[0150] 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 a first lithium-containing phosphate particle with a longest diameter of 0.05 μm to 0.3 μm and a second lithium-containing phosphate particle with a longest diameter of 1 μm to 3 μm.

[0151] 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 a first lithium-containing phosphate particle with a longest diameter of 0.05 μm to 0.3 μm. For example, 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.

[0152] 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 a second lithium-containing phosphate particle with a longest diameter of 1 μm to 3 μm. For example, 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.

[0153] 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, any cross-section taken along the thickness direction of the electrode can represent the particle size and distribution of the lithium-containing phosphate in the entire electrode; when selecting the cross-section, it is preferably a flat cross-section in the middle of the electrode to more clearly observe the distribution of the lithium-containing phosphate therein.

[0154] In some embodiments, the "longest diameter" means: cutting the positive electrode sheet including 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 4 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 particle (the longest diameter is 0.05 μm to 0.3 μm), and also shows the shortest diameter of a single particle satisfying the second lithium-containing phosphate particle (the longest diameter is 1 μm to 3 μm).

[0155] In the battery cell provided by the present application, when the positive electrode active material contains 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 enabling the battery to have excellent safety performance.

[0156] 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 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.

[0157] In some embodiments, referring to the Figure 4 particle distribution state, 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.

[0158] In the lithium-containing phosphate as the positive electrode active material, when the number of the first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles with a 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 taken into account.

[0159] It should be noted that the first lithium-containing phosphate particle material with a relatively small size and a 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.

[0160] The second lithium-containing phosphate particle material with a relatively large size and a 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.

[0161] Those skilled in the art can mix the lithium-containing phosphate particle materials within the above two size ranges according to actual needs.

[0162] 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. By way of 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.

[0163] 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. By way of 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.

[0164] 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 mm 2 , for example, 0.33 g / 1540.25 mm 2 , 0.34 g / 1540.25 mm 2 , 0.35 g / 1540.25 mm 2 , 0.36 g / 1540.25 mm 2 , 0.37 g / 1540.25 mm 2 , 0.38 g / 1540.25 mm 2 , 0.39 g / 1540.25 mm 2 , 0.4 g / 1540.25 mm 2 and so on, or other unlisted values within the range of 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 .

[0165] In some embodiments, 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 .

[0166] 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 further improved, and the influence of thick coating on the electrochemical performance can be avoided, thereby further improving the fast charging performance of the battery.

[0167] In some embodiments, the size of the positive electrode film layer in the first direction is W 1 mm, and the size of the negative electrode film layer in the first direction is W 2 mm, where W 2 > W 1 , and the difference between W 2 and W 1 is 3 mm to 5 mm, such as 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.

[0168] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0169] In some embodiments, the battery cell is a wound battery. As shown in Figure 3 , after the electrode tab is unwound 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 disposed on the same side of the positive electrode current collecting portion 111a. The positive electrode tabs 111b extend from the positive electrode current collecting portion 111a in the first direction F1; the negative electrode current collector includes a negative electrode current collecting portion 112a and at least two negative electrode tabs 112b disposed on the same side of the negative electrode current collecting portion 112a. The negative electrode tabs 112b extend from the negative electrode current collecting portion 112a in the first direction F1. Among them, the size W 2 of the negative electrode film layer in the first direction > the size W 1 of the positive electrode film layer in the first direction, and the difference is 3 mm to 5 mm.

[0170] In some embodiments, the battery cell is a stacked battery. As shown in Figure 1 and Figure 2 , each electrode tab becomes an electrode assembly in a stacked state. Among them, each positive electrode tab includes a positive electrode current collector. The positive electrode current collector includes a positive electrode current collecting portion 111a and a positive electrode tab 111b disposed on the positive electrode current collecting portion 111a. The positive electrode tab 111b extends from the positive electrode current collecting portion 111a in the first direction F1; each negative electrode tab includes a negative electrode current collector. The negative electrode current collector includes a negative electrode current collecting portion 112a and a negative electrode tab 112b disposed on the negative electrode current collecting portion 112a. The negative electrode tab 112b extends from the negative electrode current collecting portion 112a in the first direction F1. Among them, the size W 2 of the negative electrode film layer in the first direction > the size W 1 of the positive electrode film layer in the first direction, and the difference is 3 mm to 5 mm.

[0171] During the cycling process of the battery, lithium ions that cannot be embedded in 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 W of the negative electrode film layer 2 and the size W of the positive electrode film layer 1 have the above relationship, the formation of lithium dendrites on the surface of the negative electrode can be improved, so that the battery can simultaneously have good cycling performance.

[0172] 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).

[0173] 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 values not listed within the range of 10 μm to 15 μm.

[0174] 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 values not listed within the range of 5 to 12.

[0175] 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.

[0176] 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, not causing energy density loss due to excessive thickness, nor causing problems such as poor overcurrent capacity and low tensile strength resulting in electrode cracking due to too thin, further taking into account the improvement of the energy density and fast charging performance of the battery.

[0177] In some embodiments, the positive current collector includes a positive current collecting portion and at least two positive electrode tabs disposed 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. Among them, 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. 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 values not listed within the range of 10 mm to 350 mm.

[0178] 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 values not listed within the range of 20 mm to 330 mm.

[0179] 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 characteristics, 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.

[0180] In some embodiments, the positive electrode plate can be prepared in the following manner: Disperse the components for preparing the positive electrode plate, such as positive electrode active material, conductive agent, binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coat the positive electrode slurry on the positive current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0181] In some embodiments, the tap density of the positive electrode plate is 2.3 g / cm 3 to 2.6 g / cm 3 , for example, 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 2.3 g / cm 3 to 2.6 g / cm 3Other unlisted values within the range.

[0182] In some embodiments, the compaction density of the positive electrode sheet is 2.4 g / cm 3 to 2.55 g / cm 3 .

[0183] When the compaction density of the positive electrode sheet is within the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0184] In some embodiments, the compaction density of the positive electrode sheet corresponds to the compaction 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 where the battery cell is discharged at 1 / 3C to 2.0V and then discharged at 0.05C to 2.0V.

[0185] [Electrolyte] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. For example, the electrolyte can be liquid, solid, or gel.

[0186] In some embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and an organic solvent.

[0187] In some embodiments, the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0188] In the battery cell provided by the present application, when the above type of organic solvent is used in the electrolytic solution, the kinetic performance of the battery can be further improved.

[0189] In some embodiments, the organic solvent includes a linear carboxylic acid ester. Based on the total mass of the electrolytic solution, the mass percentage 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%.

[0190] In some embodiments, the linear carboxylic acid ester has the structural general formula of R 1 -COO-R 2 , where R 1 and R 2 each independently include one or more of an alkyl group of C 1 ~C 5 and a haloalkyl group of C 1 ~C 5 .

[0191] 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.

[0192] When the above - type and mass - ratio linear carboxylic esters are used as organic solvents in the electrolyte, due to the low viscosity of the linear carboxylic esters, they can effectively improve the electrolyte conductivity, thereby further improving the fast - charging performance of the battery.

[0193] 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%.

[0194] 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 methyl ethyl carbonate.

[0195] 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%.

[0196] When the above - type and mass - ratio carbonates are used as organic solvents in the electrolyte, the side reactions and gas - generation degree during the battery cycle can be improved, so that the battery can simultaneously have good cycle performance.

[0197] In some embodiments, the organic solvent includes dimethyl carbonate and a linear carboxylic ester, and the mass ratio of the linear carboxylic 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.

[0198] In some embodiments, the organic solvent includes dimethyl carbonate and a linear carboxylic ester, and the mass ratio of the linear carboxylic ester to dimethyl carbonate is 3.0 to 6.0.

[0199] When dimethyl carbonate and a linear carboxylic ester with the above - mentioned mass ratio are simultaneously used as organic solvents in the electrolyte, through the combination of the two solvents, the fast - charging performance and cycle performance of the battery can be further improved simultaneously.

[0200] 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.

[0201] In some embodiments, based on the total mass of the electrolyte, the mass fraction 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%.

[0202] In some embodiments, the lithium salt includes lithium hexafluorophosphate LiPF 6 , and at least two of fluorosulfonylimide salts, and the fluorosulfonylimide salts include one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0203] 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.

[0204] In some embodiments, the lithium salt includes lithium hexafluorophosphate LiPF 6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0205] In some embodiments, in the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF 6 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.

[0206] 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.

[0207] 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 properties of the battery, 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.

[0208] In some embodiments, the electrolyte includes carbonate additives, and the carbonate additives include fluoroethylene carbonate FEC and vinylene carbonate VC.

[0209] 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%.

[0210] 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, such as fluoroethylene carbonate and vinylene carbonate, which 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 good cycle performance.

[0211] 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%.

[0212] 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.

[0213] 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%.

[0214] 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.

[0215] [Separator membrane] 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.

[0216] In some embodiments, the material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane can 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 can be the same or different, without particular limitation.

[0217] [Battery cell] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator membrane can be made into an electrode assembly by a winding process or a stacking process.

[0218] In some embodiments, the positive current collector, the separator, the negative current collector, and the separator are stacked in sequence and wound together; after winding, the positive electrode tabs 111b of the positive current collector are aligned and stacked, and the negative electrode tabs 112b of the negative current collector are aligned and stacked, as Figure 6 shown.

[0219] 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.

[0220] In some embodiments, as shown in Figure 6 Figure 18, 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.

[0221] 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 the need to connect the positive electrode tabs 111b and the electrode terminals 131 through a connecting 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 the need to connect the negative electrode tabs 112b and the electrode terminals 131 through a connecting piece.

[0222] In a conventional battery, a connecting 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 connecting piece can effectively solve this problem, reduce the battery internal resistance, and further improve the battery energy density and fast charging performance.

[0223] In some embodiments, the battery cell can include an outer package. The outer package can be used to encapsulate the above electrode assembly and electrolyte.

[0224] 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.

[0225] In some embodiments, as Figures 6 - 9 shown, the battery cell 10 further includes a housing 14, and the current collector 11 is disposed within the housing 14.

[0226] In some embodiments, as Figures 6 - 9 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.

[0227] 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.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] The battery cell provided by the present application has excellent fast charging performance.

[0232] 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 shape. For example, Figure 10The battery cell 5 is a square structure as an example. Optionally, the battery cell is a lithium-ion battery or a sodium-ion battery.

[0233] In some embodiments, referring to Figure 11 , 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.

[0234] 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, and the number of battery cells included in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0235] Figure 12 The battery module 4 is shown as an example. Referring to Figure 12 , 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.

[0236] 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.

[0237] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0238] Figure 13 and Figure 14 The battery pack 1 is shown as an example. Referring to Figure 13 and Figure 14 , 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 and 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.

[0239] [Electrical device] 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.

[0240] As the electrical device, the battery cell, battery module, or battery pack can be selected according to its usage requirements.

[0241] Figure 15 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 high power and high energy density requirements of the electrical device for the battery cell, a battery pack or a battery module can be adopted.

[0242] 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.

[0243] 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.

[0244] Embodiment Hereinafter, the 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 the reagents or instruments not specified with the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0245] Embodiment 1 1) Negative electrode plate 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 thickener in a mass ratio of 96:1:2:1. Then add deionized water as the solvent and stir to form a negative electrode slurry. Coat the negative electrode slurry evenly on the negative electrode current collector copper foil, and after drying and cold pressing, obtain the negative electrode plate; wherein, the thickness of the negative electrode current collector copper foil is 4.5 μm, the single-sided areal density of the negative electrode plate is 0.155 g / 1540 mm 2 , and the tap density of the negative electrode plate is 1.47 g / cm 3, the size of the negative electrode film layer in the first direction is 92 mm; the volume particle size Dv50 of artificial graphite is 11 μm, and the specific surface area is 5.5 m 2 / g.

[0246] 2) Positive electrode sheet 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 surface 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 in 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 first lithium-containing phosphate particles is greater than the number of second lithium-containing phosphate particles.

[0247] 3) Electrolyte 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 (LiPF 6 ) 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% relative to the total mass of the electrolyte. Based on the total mass of the electrolyte, the mass fraction of lithium hexafluorophosphate (LiPF 6 ) is 8.9%; the mass fraction of lithium bis(fluorosulfonyl)imide LiFSI is 4.6%, and the lithium ion conductivity of the electrolyte is 14.5 mS / cm.

[0248] 4) Separator Use a commercially available polyethylene microporous film with a thickness of 7 μm and an average pore diameter of 80 nm as the separator.

[0249] 5) Battery cell 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, such 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 after drying, electrolyte is injected. 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.

[0250] Examples 2 to 5 The battery cells of Examples 2 to 5 are basically similar to those of Example 1, except that the particle size Dv50 of graphite is adjusted, as shown in Tables 1 to 4 specifically.

[0251] Examples 6 to 9 The battery cells of Examples 6 to 9 are basically similar to those of Example 1, except that the content of the carbonate additive in the electrolyte is changed, as shown in Tables 1 to 4 specifically.

[0252] Examples 10 to 13 The battery cells of Examples 10 to 13 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, as shown in Tables 1 to 4 specifically.

[0253] Example 14 The battery cell of Example 14 is basically similar to that of Example 1, except that the negative electrode active material uses double-layer coating, and the method is as follows: artificial graphite with a particle size Dv50 of 13 μm is used as the lower layer, and artificial graphite with a particle size Dv50 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. As shown in Tables 1 to 4 specifically.

[0254] Examples 15 to 16 The battery cells of Examples 15 to 16 are basically similar to those of Example 1, except that the ratio of the single-sided film layer to the current collector thickness of the positive and negative electrodes is changed, as shown in Tables 1 to 4 specifically.

[0255] Comparative Examples 1 to 2 Comparative Examples 1 to 2 are basically similar to Example 1, except that the particle size Dv50 and the specific surface area of graphite are adjusted, as shown in Tables 1 to 4 specifically.

[0256] Comparative Examples 3 to 4 Comparative Examples 3 to 4 are basically similar to Example 1, except that the types and contents of the carbonate additives in the electrolyte are changed, as shown in Tables 1 to 4 specifically.

[0257] I. Performance Test 1. DC Internal Resistance For the DC internal resistance DCR test of a single battery cell, the method in GB / T31467 "Performance Test Specification for High-power Lithium-ion Power Batteries for HEV" can be referred to. For example, at room temperature, charge the single battery cell to 3.65V at a constant current of 0.33C, let it stand for 1 min, then charge it to 3.65V at a constant current of 0.1C, let it stand for 30 min, discharge it to 2.0V at a constant current of 0.33C, record the discharge capacity A0 at this time, with the unit of Ah. Then charge it at 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 at 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.

[0258] 2. Charging Time at 10% - 80% SOC 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 monomer 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 monomer); 3) Leave to stand at 25 °C for 1 h; 4) At 25 °C, the battery monomer 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 monomer; 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) Discharge at 0.33C0 DC until the discharge cut-off voltage of 2.5V, corresponding to 0% SOC at this time; 3) Leave to stand for 5 min; 4) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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) Charge at a constant current of 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.

[0259] 3. Volume energy density At room temperature, discharge the battery cell at a constant current of 0.33C until 2.5V, then let it stand for 5 minutes, charge it at a constant current of 0.33C to the upper cut-off voltage of 3.65V, and then charge it at a constant voltage until the current is 0.05C, and let it stand for 5 minutes; discharge it at a constant current of 0.33C to the cut-off voltage of 2.5V, record the discharge capacity at this time and obtain the discharge energy E0. The volume energy density (Wh / L) = discharge energy E0 / monomer volume (L).

[0260] 4. Cycling performance At room temperature, charge at a charging rate of 0.5C to 3.65V, then charge at a constant voltage of 3.65V until 0.05C, let it stand for 10 minutes, and then discharge at a discharge rate of 1C to 2.5V, let it stand for 10 minutes. The above one charge and discharge cycle is one cycle, and the test is stopped until the battery capacity decays to 80% of the nominal capacity, denoted as the cycle number @80% SOH.

[0261] II. Analysis of test results of each example and comparative example Prepare the battery cells of each example and comparative example according to the above method, and measure various performance parameters. The results are shown in Tables 1 to 5 below.

[0262] Table 1 Preparation parameters of the negative electrode sheet

[0263] Table 2 Preparation parameters of the positive electrode sheet and electrolyte

[0264] Table 3 Preparation parameters of the electrolyte

[0265] Table 4 Preparation parameters of the electrolyte

[0266] Table 5 Battery performance parameters

[0267] Among the battery cells of Examples 1 to 16: Lithium-containing phosphate containing an olivine structure was used as the positive electrode active material in the positive electrode film layer; graphite with an average particle size Dv50 of 8 μm to 15 μm was used as the negative electrode active material in the negative electrode film layer; both FEC and VC were contained in the electrolyte as carbonate additives, and their total mass ratio was 0.5% to 7%; therefore, the battery cells prepared in Examples 1 to 16 all had excellent fast charging performance and cycling performance, as well as a low DC internal resistance, and also had a good energy density.

[0268] The average particle size Dv50 of the graphite in the negative electrode film layers of Comparative Examples 1 to 2 exceeded the range of 8 μm to 15 μm, where: the Dv50 of the graphite in Comparative Example 1 was too large, while the Dv50 of the graphite in Comparative Example 2 was too small.

[0269] From the comparison between Comparative Examples 1 to 2 and Examples 1 to 16, it can be seen that when the average particle size Dv50 of the graphite is greater than 15 μm, the fast charging performance and DC internal resistance of the battery cell cannot be effectively improved; while when the average particle size Dv50 of the graphite is less than 8 μm, the cycle performance of the battery cell cannot be effectively improved; therefore, the average particle size Dv50 of the graphite in the negative electrode film layer needs to be in the range of 8 μm to 15 μm to take into account the improvement of the cycle performance, fast charging performance and DC internal resistance of the battery. When it exceeds this range, the comprehensive performance of the battery is poor.

[0270] In the electrolytes of Comparative Examples 3 to 4, the carbonate additive only contained one of FEC or VC, and its total mass percentage exceeded the range of 0.5% to 7%, where: Comparative Example 3 only contained FEC and the mass percentage was too small; while Comparative Example 4 only contained VC and the mass percentage was too large.

[0271] From the comparison between Comparative Examples 3 to 4 and Examples 1 to 16, it can be seen that when the electrolyte only contains one carbonate additive, FEC, and the mass percentage is too small, the cycle performance of the battery cell cannot be effectively improved; while when the electrolyte only contains one carbonate additive, VC, and the mass percentage is too large, the fast charging performance and DC internal resistance of the battery cell cannot be effectively improved; therefore, when the electrolyte contains both FEC and VC as carbonate additives and their total mass percentage is 0.5% to 7%, it takes into account the improvement of the cycle performance, fast charging performance and DC internal resistance of the battery; when only one of FEC or VC is contained as an additive, or the mass percentage of the additive exceeds this range, the comprehensive performance of the battery is poor.

[0272] In Examples 1 to 5, the average particle size Dv50 of graphite in the negative electrode film layer is in the range of 8 μm to 15 μm. The battery cells prepared therefrom can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. In addition, the results also show that when the Dv50 of graphite gradually increases within the range of 8 μm to 15 μm, the cycle performance of the battery is improved to a certain extent, but the fast charging performance decreases to a certain extent and the DC internal resistance increases to a certain extent; when the Dv50 of graphite gradually decreases within the range of 8 μm to 15 μm, the fast charging performance of the battery is improved to a certain extent and the DC internal resistance decreases to a certain extent, but the cycle performance decreases to a certain extent. Therefore, only when the Dv50 of graphite in the negative electrode film layer is in the range of 8 μm to 15 μm can the fast charging performance, cycle performance, and DC internal resistance of the battery be improved while taking into account; when the Dv50 of graphite is in the range of 9.5 μm to 11.5 μm, the comprehensive performance of the battery is better. When the Dv50 of graphite is too low, the energy density of the battery decreases.

[0273] In Examples 1, 6 to 9, the electrolyte contains both FEC and VC as carbonate additives, and the total mass ratio thereof is 0.5% to 7%. The battery cells prepared therefrom can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. At the same time, the results of Examples 1, 6, and 7 also show that when the mass ratio of the carbonate additives in the electrolyte gradually increases within the range of 0.5% to 7%, the cycle performance of the battery is further improved. In addition, when the mass ratio of VC in the electrolyte is 0.5% to 2% and the mass ratio of FEC is 0.1% to 1%, it is possible to further take into account the improvement of the fast charging performance, cycle performance, and DC internal resistance of the battery, making the comprehensive performance of the battery better.

[0274] In Examples 1, 10 to 13, the electrolyte adopts the following formula, and the battery cells prepared therefrom can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance: the organic solvent adopts a linear carboxylic acid ester (such as ethyl acetate) with a mass ratio of 40% to 75%, a linear carbonate (such as DMC, EMC) with a mass ratio of 10% to 40%, and a cyclic carbonate (such as ethylene carbonate), wherein the mass ratio of dimethyl carbonate is 5% to 15%, and the mass ratio of the linear carboxylic acid ester (such as ethyl acetate) to dimethyl carbonate is 2.0 to 7.0; the lithium salt adopts LiPF 6 and LiFSI, and the mass ratio of LiPF 6 and LiFSI is 1.2:1 to 2:1.

[0275] Meanwhile, comparing Examples 1, 10, and 11 shows that: as the proportion of linear carboxylic esters (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 linear carbonates (such as DMC) and LiPF 6 added to the electrolyte gradually increases, the cycle performance of the battery is further improved.

[0276] Meanwhile, comparing Examples 1, 12, and 13 shows that: when only linear carboxylic esters (such as ethyl acetate) exist in the organic solvent of the electrolyte and no carbonates exist, and only LiFSI exists in the lithium salt and no LiPF 6 exists, the fast charging performance and DC internal resistance of the battery are further improved, but the cycle performance of the battery is poor; when only linear carbonates (such as DMC) exist in the organic solvent of the electrolyte and no linear carboxylic esters exist, and only LiPF 6 exists and no LiFSI exists, the cycle performance of the battery is further improved, but the improvement in fast charging performance and DC internal resistance is limited. Therefore, when linear carbonates and linear carboxylic esters with the above mass ratios are used as organic solvents in the electrolyte, and LiPF 6 and LiFSI with the above mass ratios are used as lithium salts, by the mutual combination of various solvents and lithium salts, the fast charging performance, DC internal resistance, and cycle performance of the battery can be further improved simultaneously, making the comprehensive performance of the battery better.

[0277] In Examples 1 and 14, the negative electrode film layer contains at least one layer of graphite as the negative electrode active material, and its average particle size Dv50 is in the range of 8 μm to 15 μm. The prepared battery monomer can take into account excellent energy density, fast charging performance, cycle performance, and low DC internal resistance. In addition, from the comparison between Example 1 and Example 11, it can be seen 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, 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 that of the second negative electrode active material layer), the fast charging performance and DC internal resistance of the battery can be further improved simultaneously, making the comprehensive performance of the battery better.

[0278] In Examples 1, 15 to 16, 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. The prepared battery cell 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 ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector gradually increases within the above range, the energy density of the battery can be further improved; when the ratio of the single-sided thickness of the negative electrode film layer to the thickness of the negative electrode current collector gradually decreases within the above range, the fast charging performance, DC internal resistance, and cycling performance of the battery can be further improved.

[0279] In Examples 1 to 16, as Figure 4 shown, in the cross-section of the positive electrode film layer along the thickness direction, the lithium-containing phosphates in the positive electrode film layer all contain 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 prepared battery cell can take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance.

[0280] In Examples 1 to 16, the specific surface area of graphite in the positive electrode film layer is 3 m 2 / g to 8 m 2 / g, the tap density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 , and the tap density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 . The prepared battery cell can take into account excellent energy density, fast charging performance, cycling performance, and low DC internal resistance.

[0281] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that can be thought of by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of this application.

Claims

1. A battery cell, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator between the positive electrode sheet and the negative electrode sheet, characterized in that: The positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium-containing phosphate with an olivine structure; The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material, wherein the average particle size Dv50 of the negative electrode active material is 8 μm to 15 μm, and the specific surface area of ​​the negative electrode active material is 3 m 2 / g to 8m 2 / g, the negative electrode active material includes graphite; The electrolyte includes carbonate additives, and the carbonate additives include fluoroethylene carbonate FEC and vinylene carbonate VC; based on the total mass of the electrolyte, the mass proportion of the carbonate additives is 0.5% to 7%.

2. The battery cell according to claim 1, characterized in that: The average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm.

3. The battery cell according to claim 1, characterized in that: The specific surface area of ​​the negative electrode active material is 4 m 2 / g to 6m 2 / g.

4. The battery cell according to claim 1, characterized in that: The electrolyte includes vinylene carbonate VC, and the mass proportion of vinylene carbonate VC in the electrolyte is 0.5% to 2% based on the total mass of the electrolyte.

5. The battery cell according to claim 1, characterized in that: The electrolyte includes fluoroethylene carbonate (FEC), and the mass proportion of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 1% based on the total mass of the electrolyte.

6. The battery cell according to claim 1, characterized in that: The electrolyte further comprises an organic solvent, and the organic solvent comprises a carboxylate solvent and a carbonate solvent.

7. The battery cell according to claim 6, characterized in that: The organic solvent includes a linear carboxylic acid ester, and the mass proportion of the linear carboxylic acid ester is 40% to 75% based on the total mass of the electrolyte.

8. The battery cell according to claim 7, characterized in that: The linear carboxylic acid ester has a general structural formula of R1-COO-R2, wherein R1 and R2 each independently include one or more of a C1-C5 alkyl group and a C1-C5 halogenated alkyl group.

9. The battery cell according to claim 8, 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.

10. The battery cell according to any one of claims 6 to 9, characterized in that: The organic solvent includes a carbonate solvent, and the carbonate solvent includes a linear carbonate and a cyclic carbonate. The mass proportion of the linear carbonate is 10% to 40% based on the total mass of the electrolyte.

11. The battery cell according to claim 10, characterized in that: 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.

12. The battery cell according to claim 11, characterized in that: The linear carbonate includes dimethyl carbonate, and based on the total mass of the electrolyte, the mass proportion of the dimethyl carbonate is 5% to 15%.

13. The battery cell according to claim 6, characterized in that: The organic solvent includes dimethyl carbonate and linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.

0.

14. The battery cell according to claim 13, characterized in that: The mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.

0.

15. The battery cell according to claim 1, characterized in that: The electrolyte further includes a lithium salt, and the mass proportion of the lithium salt is 13% to 20% based on the total mass of the electrolyte.

16. The battery cell according to claim 15, characterized in that: The lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonyl imide salts, and the fluorine-containing sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

17. The battery cell according to claim 15, characterized in that: The lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI.

18. The battery cell according to claim 17, characterized in that: In the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bis(fluorosulfonyl)imide LiFSI is 1.2:1 to 2:

1.

19. The battery cell according to claim 1, characterized in that: The general composition formula of the lithium-containing phosphate with an olivine structure is as shown in Formula I: Li x A y Me a M b P 1-c X c Y z Formula I Among them, 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.

20. The battery cell according to claim 19, characterized in that: M includes one or more of Al, Ti, V, and Mg.

21. The battery cell according to claim 19 or 20, characterized in that: The positive electrode active material satisfies at least one of the following conditions: (1) The positive electrode active material contains Al element, the mass content of which is 0.01-0.05%, based on the total mass of the positive electrode active material; (2) The positive electrode active material contains Ti element, the mass content of which is 0.01-0.03%, based on the total mass of the positive electrode active material; (3) The positive electrode active material contains V element, the mass content of which is 0.1-0.3%, 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 0.001-0.01% based on the total mass of the positive electrode active material.

22. The battery cell according to claim 1, characterized in that: In a cross section of the positive electrode film layer along the thickness direction, the olivine-structured 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.

23. The battery cell according to claim 22, characterized in that: In a cross section of the positive electrode film layer along a thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

24. The battery cell according to claim 1, characterized in that The compaction density of the positive electrode sheet is 2.3 g / cm 3 Up to 2.6g / cm 3 .

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

26. The battery cell according to claim 1, characterized in that: The surface density of the positive electrode film layer on one side is 0.33g / 1540.25mm 2 Up to 0.4 g / 1540.25 mm 2 .

27. The battery cell according to claim 1, characterized in that: The surface density of the positive electrode film layer on one side is 0.335g / 1540.25mm 2 Up to 0.38 g / 1540.25 mm 2 .

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

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

30. The battery cell according to claim 1, characterized in that The surface density of the negative electrode film layer on one side is 0.15g / 1540.25mm 2 Up to 0.19 g / 1540.25 mm 2 .

31. The battery cell according to claim 1, characterized in that The surface density of the negative electrode film layer on one side is 0.15g / 1540.25mm 2 Up to 0.165 g / 1540.25 mm 2 .

32. The battery cell according to claim 1, characterized in that The thickness of the negative electrode current collector is less than or equal to 4-6 μm.

33. The battery cell according to claim 1, characterized in that: The ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12 to 20.

34. The battery cell according to claim 1, characterized in that The ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 13 to 20.

35. The battery cell according to claim 1, characterized in that The negative electrode current collector includes a negative electrode current collecting portion, the negative electrode film layer includes a first negative electrode active material layer arranged on the surface of the negative electrode current collecting portion 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 collecting portion, 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.

36. The battery cell according to claim 35, characterized in that The average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

37. The battery cell according to claim 35, characterized in that: The average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

38. The battery cell according to claim 35, characterized in that: The average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

39. The battery cell according to claim 1, characterized in that: The positive electrode current collector comprises a positive electrode current collecting portion and at least two positive electrode tabs arranged on the same side of the positive electrode current collecting portion, wherein the positive electrode tabs extend from the positive electrode current collecting portion along a first direction, wherein a distance between center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center line is parallel to the first direction; and / or, The negative electrode current collector includes a negative electrode current collecting portion and at least two negative electrode tabs arranged on the same side of the negative electrode current collecting portion, the negative electrode tabs extend from the negative electrode current collecting portion along a first direction, wherein a distance between center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the center line is parallel to the first direction.

40. The battery cell according to claim 39, characterized in that 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 ears is 20 mm to 330 mm.

41. The battery cell according to claim 39 or 40, characterized in that: The battery cell further includes a top cover, wherein the top cover includes a positive electrode terminal and a negative electrode terminal with opposite polarities, wherein the positive electrode terminal and the negative electrode terminal are respectively used to be electrically connected to the positive electrode tab and the negative electrode tab.

42. The battery cell according to claim 39, characterized in that The size of the positive electrode film layer along the first direction is W1 mm, and the size of the negative electrode film layer along the first direction is W2 mm, wherein W2>W1, and the difference between W2 and W1 is 3 mm to 5 mm.

43. The battery cell according to claim 1, characterized in that The battery cell further includes a shell, which is square in shape, has a thickness of 30 mm to 55 mm, a width of 150 mm to 250 mm, and a height of 90 mm to 120 mm.

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

45. A battery device, characterized in that: Comprising the battery monomer described in any one of claims 1 to 44, the battery device is at least one of a battery module, a battery pack, and an energy storage device.

46. ​​An electrical device, characterized in that: A battery cell comprising any one of claims 1 to 44 or a battery device according to claim 45.

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