Battery cell, battery device, and electric device

Abstract

A battery cell, a battery device, and an electric device. In the battery cell, a positive electrode active material comprises a lithium-containing phosphate salt having an olivine structure; the average particle size Dv50 of a negative electrode active material is 8 μm to 15 μm, and the negative electrode active material comprises graphite; and an electrolyte comprises a carbonate additive, the carbonate additive comprises fluoroethylene carbonate (FEC) and vinylene carbonate (VC), and on the basis of the total mass of the electrolyte, the mass proportion of the carbonate additive is 0.5% to 7%.

Description

Battery cell, battery device and electric device TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery cell, a battery device and an electric device. BACKGROUND

[0002] In recent years, batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the popularization of battery applications, higher requirements are put forward for its energy density, fast charging performance, cycle performance, service life, safety performance, etc.

[0003] SUMMARY

[0004] The present application aims to provide a new type of battery cell which has excellent fast charging performance and also has high energy density, good cycle performance and low direct current internal resistance.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a battery cell, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator film between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a negative current collector and a positive film layer arranged on at least one surface of the positive current collector, the positive film layer comprising a positive active material, the positive active material comprising lithium-containing phosphate with olivine structure; the negative electrode sheet comprises a negative current collector and a negative film layer arranged on at least one surface of the negative current collector, the negative film layer comprising a negative active material, the average particle size Dv50 of the negative active material being 8-15 μm, the negative active material comprising graphite; the electrolyte comprises a carbonate additive, the carbonate additive comprising fluoroethylene carbonate FEC and vinylene carbonate VC; the mass fraction of the carbonate additive is 0.5-7% based on the total mass of the electrolyte.

[0006] The battery charging process is the process of lithium ions being extracted from the positive active material and embedded in the negative active material. When fast charging, the embedding capacity of lithium ions in the negative active material becomes a bottleneck limiting the improvement of the fast charging capacity of the battery. The present application uses a small particle size of the negative active material to reduce the transmission path of lithium ions in the negative active material, reduce the embedding difficulty of lithium ions in the negative active material, slow down the lithium precipitation of the battery during the fast charging process, reduce the charging time of the battery, and reduce the internal resistance of the battery, reduce the temperature rise of the battery during the fast charging process, and improve the safety performance of the battery. However, when the particle size of the negative active material is small, the corresponding specific surface area is large, which increases the contact area of the negative active material and the electrolyte, and the side reaction at the interface increases. Therefore, it is necessary to optimize the composition of the solid electrolyte interface film (SEI film) of the negative active material. The present application introduces a high content of carbonate electrolyte film-forming additives fluoroethylene carbonate FEC and vinylene carbonate VC and reasonably controls the content to optimize the composition of the negative SEI film. On the one hand, the film-forming rate and film quality of the SEI film are higher, and the side reaction of the negative active material and the electrolyte is timely and efficient, which improves the cycle performance of the battery. On the other hand, the film impedance of the SEI film is reduced, which further improves the fast charging performance of the battery and reduces the internal resistance of the battery.

[0007] In the battery cell provided by the present application, a carbonate additive with a mass ratio in the above range, such as fluoroethylene carbonate and vinylene carbonate, is also added to the electrolyte. The SEI film can be formed on the negative electrode surface, thereby reducing the side reaction between the graphite with the above range of particle size and the electrolyte, and further improving the cycle performance of the battery.

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

[0009] When the particle size of the negative active material (such as graphite) is in the above range, the fast charging performance and direct current resistance of the battery can be further improved, and the cycle performance of the battery can be further improved.

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

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

[0012] When the negative active material (e.g., graphite) has a specific surface area in the above range, the speed of lithium ion intercalation and deintercalation between graphite layers can be further accelerated, thereby further improving the fast-charging performance of the battery.

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

[0014] When the electrolyte includes vinylene carbonate VC as an additive in the above mass percentage range, the SEI film formed thereby is more stable, which is conducive to further improving the cycle performance of the battery.

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

[0016] When the electrolyte includes fluoroethylene carbonate FEC as an additive in the above mass percentage range, the SEI film formed thereby has low impedance, which is conducive to further improving the fast-charging performance of the battery.

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

[0018] In the battery cell provided herein, when the electrolyte includes the above type of organic solvent, 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 percentage 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 a general structure of R1-COO-R2, where R1 and R2 each independently includes one or more of C1-C5 alkyl and C1-C5 haloalkyl.

[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 electrolyte includes the above type and mass percentage of linear carboxylic acid ester as an organic solvent, the linear carboxylic acid ester can effectively improve the conductivity of the electrolyte due to its low viscosity, thereby further improving the fast-charging performance of the battery.

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

[0024] In any embodiment, the cyclic carbonate comprises one or more of vinyl carbonate and propylene carbonate, and the linear carbonate comprises one or more of dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate.

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

[0026] When the electrolyte adopts the above type and mass percentage of carbonate as the organic solvent, the side reactions and the degree of gas production of the battery during the cycle process can be improved, so that the battery has good cycle performance.

[0027] In any embodiment, the organic solvent comprises 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.

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

[0029] When the electrolyte simultaneously adopts the above mass ratio of dimethyl carbonate and linear carboxylic acid ester as the organic solvent, the combination of the two solvents can further improve the fast charging performance and cycle performance of the battery.

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

[0031] In any embodiment, the lithium salt comprises at least two of lithium hexafluorophosphate LiPF6 and fluorine-containing sulfonimide salt, and the fluorine-containing sulfonimide salt comprises one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI.

[0032] Lithium hexafluorophosphate is not easy to produce gas during the cycle process, which can further improve the cycle performance of the battery; and the dissociation ability of fluorine-containing sulfonimide salt is strong, which can further improve the fast charging performance of the battery.

[0033] In any embodiment, the lithium salt comprises lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

[0034] In any embodiment, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI in the electrolyte is 1.2:1 to 2:1.

[0035] When lithium hexafluorophosphate and lithium bisfluorosulfonylimide in the above mass ratio range are simultaneously used in the electrolyte, the fast-charging performance and the cycle performance of the battery can be further improved.

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

[0037] wherein 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, 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, Ce; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F.

[0038] 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.

[0039] In any embodiment, M includes one or more of Al, Ti, V, Mg.

[0040] In any embodiment, the positive electrode active material satisfies at least one of the following conditions:

[0041] (1) the positive electrode active material contains Al element, the mass content is 0.01-0.05%, based on the total mass of the positive electrode active material;

[0042] (2) the positive electrode active material contains Ti element, the mass content is 0.01-0.03%, based on the total mass of the positive electrode active material;

[0043] (3) the positive electrode active material contains V element, the mass content is 0.1-0.3%, based on the total mass of the positive electrode active material;

[0044] (4) The positive electrode active material contains Mg element with a mass content of 0.001 to 0.01%, based on the total mass of the positive electrode active material.

[0045] When lithium phosphates used as positive electrode active materials contain elements such as Al, Ti, V, and Mg, their specific capacity can be further improved.

[0046] In any embodiment, in a cross-section along the thickness direction of the positive electrode film, the lithium phosphate with olivine structure comprises a first lithium phosphate particle with a longest diameter of 0.05 μm to 0.3 μm and a second lithium phosphate particle with a longest diameter of 1 μm to 3 μm.

[0047] When the positive electrode active material of the battery cell provided in this application contains lithium 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 battery heat generation and enabling the battery to have excellent safety performance.

[0048] In the battery cell provided in this application, when the lithium phosphate used as the positive electrode active material contains both a first lithium phosphate particle with a longest diameter of 0.05 μm to 0.3 μm and a second lithium phosphate particle with a longest diameter of 1 μm to 3 μm, the compaction density of the electrode can be effectively improved by grading the size of the particles, thereby enabling the battery cell to also have a high energy density.

[0049] In any embodiment, in a cross-section of the positive electrode film layer along the thickness direction, the number of the first lithium phosphate particles is greater than the number of the second lithium phosphate particles.

[0050] When the number of first lithium phosphate particles with a longest diameter of 0.05 μm to 0.3 μm is greater than the number of second lithium phosphate particles with a longest diameter of 1 μm to 3 μm in the positive electrode active material, the DC internal resistance and fast charging performance of the battery can be further improved.

[0051] In any embodiment, the compaction density of the positive electrode sheet is 2.3 g / cm³. 3 Up to 2.6 g / cm 3 .

[0052] In any embodiment, the compaction density of the positive electrode sheet is 2.4 g / cm³. 3 Up to 2.55 g / cm 3 .

[0053] 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 dynamic performance.

[0054] In any embodiment, the areal density of the positive electrode film layer on a single side is 0.33 g / 15 40.25 mm 2 to 0.4 g / 15 40.25 mm 2 .

[0055] In any embodiment, the areal density of the positive electrode film layer on a single side is 0.335 g / 15 40.25 mm 2 to 0.38 g / 15 40.25 mm 2 .

[0056] 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.

[0057] In any embodiment, the compaction density of the negative electrode tab is 1.3 g / cm 3 to 1.6 g / cm 3 .

[0058] In any embodiment, the compaction density of the negative electrode tab is 1.35 g / cm 3 to 1.55 g / cm 3 .

[0059] 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 the kinetic performance is ensured.

[0060] In any embodiment, the areal density of the negative electrode film layer on a single side is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

[0061] In any embodiment, the areal density of the negative electrode film layer on a single side is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

[0062] 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.

[0063] In any embodiment, the thickness of the negative electrode current collector is less than or equal to 4-6 μm.

[0064] In any embodiment, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is 12-20.

[0065] In any embodiment, 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.

[0066] The battery cell provided in the present application can further improve the energy density and fast-charging performance of the battery when the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative electrode current collector is within the above range.

[0067] In any embodiment, the negative electrode film layer comprises a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer comprises a first artificial graphite, and the negative electrode active material in the second negative electrode active material layer comprises a second artificial graphite, wherein the average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

[0068] In any embodiment, the average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

[0069] In any embodiment, the average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

[0070] In any embodiment, the average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

[0071] The battery cell provided in the present application can further improve the kinetic performance of the battery when the double-layer coating scheme is used in the negative electrode film layer.

[0072] In any embodiment,

[0073] The positive electrode current collector comprises a positive electrode current collector portion and at least two positive electrode tabs disposed on the same side of the positive electrode current collector portion, the positive electrode tabs extending from the positive electrode current collector portion along a first direction, wherein the distance between the center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction; and / or,

[0074] The negative electrode current collector comprises a negative electrode current collector portion and at least two negative electrode tabs disposed on the same side of the negative electrode current collector portion, the negative electrode tabs extending from the negative electrode current collector portion along a first direction, wherein the distance between the center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction.

[0075] In any embodiment, the distance between the center lines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or,

[0076] The distance between the center lines of the two adjacent negative tabs is 20-330 mm.

[0077] The battery cell provided in the application can further improve the direct current internal resistance of the battery cell when the positive and negative current collectors include at least two tabs with the above structural features, thereby further reducing the heat generation of the battery, and making the battery have better safety performance.

[0078] In any embodiment, the battery cell further includes a top cover including a positive electrode terminal and a negative electrode terminal with opposite polarities, which are respectively used to be electrically connected with the positive tab and the negative tab.

[0079] In a conventional battery, a jumper is needed to connect the electrode terminal and the tab, but the utilization rate of the electrode assembly is lost, and the energy density of the battery is reduced. When the above structure is used in the battery cell provided in the application, the jumper is cancelled, which can effectively solve this problem, reduce the internal resistance of the battery, and further improve the energy density and fast charging performance of the battery.

[0080] In any embodiment, the size of the positive film layer along the first direction is W1 mm, and the size of the negative film layer along the first direction is W2 mm, wherein W2>W1, and the difference between W2 and W1 is 3-5 mm.

[0081] During the cycle of the battery, lithium ions that cannot be timely embedded in the negative electrode may form lithium dendrites on the surface of the negative electrode, which deteriorates the cycle performance of the battery. When the size W2 of the negative film layer and the size W1 of the positive film layer have the above relationship in the battery cell provided in the application, the formation of lithium dendrites on the surface of the negative electrode by lithium ions can be improved, thereby further improving the cycle performance of the battery.

[0082] In any embodiment, the battery cell further includes a shell, which is square, and has a thickness of 30-55 mm, a width of 150-250 mm, and a height of 90-120 mm.

[0083] In any embodiment, the battery cell is configured to have a charging time of 10-17 min for charging from 10% SOC to 80% SOC at room temperature.

[0084] The battery cell provided in the application has excellent fast charging performance.

[0085] The second aspect of the application also provides a battery device, which includes the battery cell of the first aspect of the application, and is at least one of a battery module, a battery pack, and an energy storage device.

[0086] The third aspect of the present application also provides a power consuming device including the battery cell of the first aspect or the battery device of the second aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0087] Fig. 1 is a schematic view of the size of the electrode sheet film layer according to an embodiment of the present application;

[0088] Fig. 2 is a schematic view of the size of the electrode sheet film layer according to an embodiment of the present application;

[0089] Fig. 3 is a schematic view of the size of the electrode sheet film layer according to an embodiment of the present application;

[0090] Fig. 4 is a graph of the electron microscope observation results of the longitudinal cross section of the positive electrode sheet according to an embodiment of the present application;

[0091] Fig. 5 is a schematic view of the electrode sheet according to an embodiment of the present application;

[0092] Fig. 6 is an exploded view of the battery cell according to an embodiment of the present application;

[0093] Fig. 7 is a schematic view of the battery cell according to an embodiment of the present application;

[0094] Fig. 8 is a schematic view of the battery cell according to an embodiment of the present application;

[0095] Fig. 9 is a schematic view of the battery cell according to an embodiment of the present application;

[0096] Fig. 10 is a schematic view of the battery cell according to an embodiment of the present application;

[0097] Fig. 11 is an exploded view of the battery cell according to an embodiment of the present application shown in Fig. 10;

[0098] Fig. 12 is a schematic view of the battery module according to an embodiment of the present application;

[0099] Fig. 13 is a schematic view of the battery pack according to an embodiment of the present application;

[0100] Fig. 14 is an exploded view of the battery pack according to an embodiment of the present application shown in Fig. 13;

[0101] Fig. 15 is a schematic view of the power consuming device using the battery cell according to an embodiment of the present application as a power source.

[0102] EXPLANATION OF REFERENCE NUMERALS:

[0103] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 case; 52 electrode assembly; 53 top cap assembly; 10 battery cell; 11 current collector; 11a current collecting portion; 111a positive electrode current collecting portion; 112a negative electrode current collecting portion; 11b tab; 111b positive electrode tab; 112b negative electrode tab; F1 first direction; W1 dimension of positive electrode film layer along first direction; W2 dimension of negative electrode film layer along first direction; L center line; 13 top cap; 131 electrode terminal; 14 case. DETAILED DESCRIPTION

[0104] Hereinafter, embodiments of the battery cell and the electrical device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known well, repeated description of substantially the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0105] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 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, 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, a numerical range "a-b" represents a shorthand notation for any real combination of integers 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 listed herein, and "0-5" is just a shorthand notation for these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0106] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0107] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0108] If not specifically stated, all steps of the present application can be performed in sequence or randomly, preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0109] If not specifically stated, the present application refers to "including" and "comprising" as open-ended, and can also be closed. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0110] If not specifically stated, 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 one 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) and B is true (or exists); or A and B are both true (or exist).

[0111] In recent years, as the demand for batteries as energy sources continues to increase, higher requirements are placed on the fast charging performance of batteries. However, fast charging batteries can release a large amount of heat in a short time during charging, which can have certain safety hazards. Therefore, if the battery dynamics performance can be improved while taking into account the improvement of the direct current impedance and cycle performance of the battery, the overall performance of the battery can be further improved.

[0112] In order to solve the above problems, the present application provides a battery monomer, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator film located between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising a lithium-containing phosphate with an olivine structure; the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material, the average particle size Dv50 of the negative electrode active material being 8 μm to 15 μm, the negative electrode active material comprising graphite; the electrolyte comprises a carbonate additive, the carbonate additive comprising fluoroethylene carbonate FEC and vinylene carbonate VC; the mass fraction of the carbonate additive is 0.5% to 7% based on the total mass of the electrolyte.

[0113] In some embodiments, the "average particle size Dv50" refers to the particle size corresponding to the cumulative volume distribution percentage of 50% from the small particle size side in the particle size distribution of the particles. The determination method can refer to GB / T19077-2016 / ISO 13320:2009, and a Malvern 2000 (MasterSizer 2000) laser particle size analyzer is used for determination.

[0114] In the embodiments of the present application, the types and contents of the organic components in the electrolyte are well known in the art, and can be detected by using the devices and methods known in the art, for example, the composition of the electrolyte can be detected by liquid chromatography, gas chromatography, ion chromatography, liquid nuclear magnetic method, etc. For example, the organic components in the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography according to GB / T9722-2006 "General method for gas chromatography of chemical reagents".

[0115] The test sample in the embodiments of the present application can be the freshly prepared electrolyte, or the free electrolyte obtained from the battery after the battery is fully discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC).

[0116] In the embodiments of the present application, the types and contents of the inorganic components / lithium salt concentration in the electrolyte are well known in the art, and can be detected by using the devices and methods known in the art, for example, the inorganic components / lithium salt concentration in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography according to the standard JY / T020-1996 "General method for ion chromatography analysis". In the embodiments of the present application, the freshly prepared electrolyte can be used as the sample, or the free electrolyte obtained from the battery after the battery is fully discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC), and the ion chromatography analysis method is used for detection.

[0117] The battery charging process is the process of lithium ions being extracted from the positive active material and embedded in the negative active material. When fast charging, the embedding capacity of lithium ions in the negative active material becomes a bottleneck limiting the improvement of the fast charging capacity of the battery. The application uses small particle size negative active material to reduce the transmission path of lithium ions in the negative active material, reduce the embedding difficulty of lithium ions in the negative active material, slow down the lithium precipitation of the battery during fast charging, reduce the charging time of the battery, and reduce the internal resistance of the battery, reduce the temperature rise of the battery during fast charging, and improve the safety performance of the battery. However, when the particle size of the negative active material is small, the specific surface area is large, which increases the contact area of the negative active material and the electrolyte, and the side reaction at the interface increases. Therefore, it is necessary to optimize the SEI film composition of the negative active material. The application introduces a high content of carbonate electrolyte film-forming additive FEC and VC and reasonably controls the content to optimize the composition of the negative SEI film. On the one hand, the film-forming rate and film quality of the SEI film are higher, and the side reaction of the negative active material and the electrolyte is timely and efficient, which improves the cycle performance of the battery. On the other hand, the film impedance of the SEI film is reduced, which further improves the fast charging performance of the battery and reduces the internal resistance of the battery.

[0118] [The negative electrode sheet]

[0119] In some embodiments, the negative electrode sheet 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 opposite surfaces in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0120] In some embodiments, the negative electrode film layer includes a negative active material.

[0121] In some embodiments, the average particle size Dv50 of the negative 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, or other unlisted values within the range of 8 μm to 15 μm. In some embodiments, the negative active material includes graphite.

[0122] In the battery cell provided by the application, when the particle size of the negative active material (such as graphite) is within the above range, the specific surface area is large, the migration channel of lithium ions between the graphite layers increases, the migration path is shortened, the embedding and extracting speed of lithium ions between the graphite layers is accelerated, and the battery cell has good fast charging performance. At the same time, when the particle size of the negative active material (such as graphite) is within the above range, the direct current internal resistance of the battery cell can also be improved, thereby reducing the heat generation of the battery and improving the safety performance of the battery.

[0123] In some embodiments, the average particle size Dv50 of the negative active material is 9.5 μm to 11.5 μm, for example, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, or other unlisted values within the range of 9.5 μm to 11.5 μm.

[0124] When the negative active material (for example, graphite) has a particle size within the above range, the fast-charging performance and direct current internal resistance of the battery can be further improved, while the battery also has good cycle performance.

[0125] In some embodiments, the specific surface area of the negative active material is 3 m 2 / g to 8 m 2 / g, for example, 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, and the like, or other unlisted values within the range of 3 m 2 / g to 8 m 2 / g.

[0126] In some embodiments, the specific surface area of the negative active material is 4 m 2 / g to 6 m 2 / g, for example, 4 m 2 / g, 4.5 m 2 / g, 5 m 2 / g, 5.5 m 2 / g, 6 m 2 / g, and the like, or other unlisted values within the range of 4 m 2 / g to 6 m 2 / g.

[0127] As used herein, “specific surface area” refers to the total area possessed by a unit mass of material. The determination method can refer to GB / T 19587-2017, and is tested using the nitrogen adsorption specific surface area analysis test method and calculated using the BET (Brunauer Emmett Teller) method, wherein the nitrogen adsorption specific surface area analysis test can be performed using a Tri-Star 3020 specific surface area pore size analyzer from the United States Micromeritics company.

[0128] As a negative active material, for example, graphite, having a specific surface area within the above range, the speed of lithium ion intercalation and deintercalation between graphite layers can be further accelerated, thereby further improving the fast-charging performance of the battery.

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

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

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

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

[0133] The battery cell provided in the present application can further improve the kinetic performance of the battery when the double-layer coating scheme described above is used in the negative electrode film layer.

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

[0135] In some embodiments, the negative electrode film layer can optionally further comprise a conductive agent. The conductive agent can be selected from at least one of super-conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0136] In some embodiments, the negative electrode film layer can optionally further comprise other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0137] In some embodiments, the areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 , for example, 0.15 g / 15 40.25 mm 2 , 0.16 g / 15 40.25 mm 2 , 0.17 g / 15 40.25 mm 2 , 0.18 g / 15 40.25 mm 2 , 0.19 g / 15 40.25 mm 2 , or other unlisted values within the range of 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

[0138] In some embodiments, the areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

[0139] As used herein, the "areal density" of a positive electrode film layer or a negative electrode film layer has the meaning known in the art and can be tested using methods known in the art. For example, a single-side coated and cold-pressed negative electrode sheet (if a double-side coated negative electrode sheet, the negative electrode film layer on one side can be wiped off) is punched into a small round piece with an area of S1, weighed, and recorded as M1. Then the negative electrode film layer of the weighed negative electrode sheet is wiped off, the weight of the negative electrode current collector is weighed and recorded as M0, and the areal density of the negative electrode film layer = (weight of the negative electrode sheet M1 - weight of the negative electrode current collector M0) / 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 is calculated as the test result.

[0140] The battery cell provided herein can further improve the energy density of the battery and avoid the influence of thick coating on the electrochemical performance when the coating areal density of the negative electrode film layer is within the above range, thereby further improving the fast-charging performance of the battery.

[0141] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0142] In some embodiments, the thickness of the negative current collector is 4-6 μm, for example, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or other non-listed values within the range of 4-6 μm.

[0143] In some embodiments, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative current collector is 12-20, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, or other non-listed values within the range of 12-20.

[0144] In some embodiments, the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative current collector is 13-20.

[0145] In some embodiments, the single-side thickness of the negative electrode film layer corresponds to the single-side thickness of the negative electrode film layer of a battery cell at a 0% SOC state, wherein the battery cell at the 0% SOC state is discharged at 1 / 3 C to 2.0 V and then discharged at 0.05 C to 2.0 V.

[0146] The battery cell provided herein can further improve the energy density and fast-charging performance of the battery when the ratio of the single-side thickness of the negative electrode film layer to the thickness of the negative current collector is within the above range.

[0147] In some embodiments, as shown in FIG. 5, the current collector 11 includes a current collecting portion 11a and at least two tabs 11b disposed on the same side of the current collecting portion 11a, the tabs 11b extending from the current collecting portion 11a along a first direction F1, wherein the distance between the center lines L of two adjacent tabs 11b is 10-350 mm, the center lines L being 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, or other non-listed values within the range of 10-350 mm.

[0148] In some embodiments, the distance between the center lines L of two adjacent tabs 11b is 20-330 mm, the center lines L being 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, or other non-listed values within the range of 20-330 mm.

[0149] In some embodiments, as shown in FIG. 5 and FIG. 6, the current collector 1 can be a positive current collector, and the tab 11b can be a positive tab 111b.

[0150] In some embodiments, as shown in FIG. 5 and FIG. 6, the current collector 11 can be a negative current collector, and the tab 11b can be a negative tab 112b.

[0151] In some embodiments, the negative current collector comprises a negative current collecting portion and at least two negative tabs disposed on the same side of the negative current collecting portion, the negative tabs extending from the negative current collecting portion along a first direction, wherein the distance between the center lines of two adjacent negative tabs is 10 mm to 350 mm, the center lines being parallel to the first direction, such as 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 350 mm, or other values not listed in the range of 10 mm to 350 mm.

[0152] In some embodiments, the distance between the center lines of two adjacent negative tabs is 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, or other values not listed in the range of 20 mm to 330 mm.

[0153] In some embodiments, as shown in FIG. 5 and FIG. 6, the center line L refers to the axis of symmetry passing through the midpoint of the tab 11b along the length direction of the current collector 11, and the center line L is parallel to the first direction F1. In some embodiments, the size of each tab 11b along the length direction of the current collector 11 is equal.

[0154] In some embodiments, as shown in FIG. 5, the distance between the center lines L of two adjacent tabs 11b comprises S1 or S2, wherein S1 and S2 can be equal (in which case the adjacent tabs are equally spaced), or S1 and S2 can not be equal (in which case the adjacent tabs are not equally spaced).

[0155] The battery cell provided in the present application can further improve the overcurrent capacity and the direct current resistance of the battery cell when the positive and negative current collectors comprise at least two tabs with the above structural characteristics, thereby further reducing the heat generation of the battery and improving the safety performance of the battery.

[0156] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0157] In some embodiments, the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 , for example, 1.3 g / cm 3 , 1.4 g / cm 3 , 1.5 g / cm 3 , 1.6 g / cm 3 , or other unlisted values within the range of 1.3 g / cm 3 to 1.6 g / cm 3 .

[0158] In some embodiments, the compaction density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 , for example, 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 , or other unlisted values within the range of 1.35 g / cm 3 to 1.55 g / cm 3 .

[0159] In some embodiments, the compaction density of the negative electrode sheet corresponds to the compaction density of the negative electrode film layer of the battery cell in the 0% SOC state, wherein the battery cell in the 0% SOC state refers to a battery cell discharged at 1 / 3C to 2.0V and then discharged at 0.05C to 2.0V.

[0160] As used herein, the "compaction density" of the electrode sheet is: compaction density = areal density / (electrode sheet thickness - current collector thickness), and the determination method can refer to GB / T 24533-2009.

[0161] 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.

[0162] [Positive electrode sheet]

[0163] In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. As an example, the positive electrode current collector has two surfaces opposite in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0164] In some embodiments, the positive electrode film layer includes a positive electrode active material.

[0165] In some embodiments, the positive electrode active material includes a lithium-containing phosphate of olivine structure.

[0166] In some embodiments, the lithium-containing phosphate of olivine structure has a general formula as shown in Formula I, Li x A y Me a M b P 1-c X c Y z Formula I,

[0167] wherein 0.1≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, 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, Ce; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F.

[0168] As used herein, "the lithium-containing phosphate of olivine structure has a general formula as shown in Formula I" is not limited to only the substance represented by the molecular formula, but also includes other substances formed by further modifying the substance on the basis of the molecular formula, which is not limited herein. The use of "general formula" is only for the convenience of description, and is not intended to limit the present application. It can be understood that new materials or substances obtained by appropriately modifying the listed positive electrode active materials are also within the scope of positive electrode active materials, and the aforementioned appropriate modification refers to acceptable modification of the positive electrode active material, and non-limiting examples include coating modification.

[0169] When the lithium-containing phosphate as the positive electrode active material has the above chemical formula, the energy density of the battery can be further improved.

[0170] In some embodiments, M includes one or more of Al, Ti, V, Mg.

[0171] In some embodiments, the positive electrode active material contains Al element, the mass content of which is 0.001% to 0.05%, optionally 0.01% to 0.05%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or other values not listed in the range of 0.001% to 0.05%, based on the total mass of the positive electrode active material.

[0172] In some embodiments, the positive electrode active material contains Ti element, the mass content of which is 0.001% to 0.03%, optionally 0.01 to 0.03%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.02%, 0.03%, or other values not listed in the range of 0.001% to 0.03%, based on the total mass of the positive electrode active material.

[0173] In some embodiments, the positive electrode active material contains V element, the mass content of which is 0.001% to 0.3%, optionally 0.1 to 0.3%, based on the total mass of the positive electrode active material, such as 0.001%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, or other values not listed in the range of 0.001% to 0.3%, based on the total mass of the positive electrode active material.

[0174] In some embodiments, the positive electrode active material contains Mg element, the mass content of which is 0.001% to 0.01%, based on the total mass of the positive electrode active material, optionally 0.001%, 0.002%, 0.005%, 0.01%, or other values not listed in the range of 0.001% to 0.01%, based on the total mass of the positive electrode active material.

[0175] When the lithium-containing phosphate as the positive electrode active material contains Al, Ti, V, Mg, etc., the structural stability of the material can be further improved, and the cycle performance can be improved.

[0176] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphate of olivine structure comprises 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.

[0177] In some embodiments, in the 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, for example, 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, or other unlisted values within the range of 0.05 μm to 0.3 μm.

[0178] In some embodiments, in the cross section of the positive electrode film layer along the thickness direction, the olivine-structured lithium-containing phosphate includes second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or other unlisted values within the range of 1 μm to 3 μm.

[0179] In some embodiments, since the first lithium-containing phosphate and the second lithium-containing phosphate have been sufficiently mixed when preparing the slurry and uniformly coated onto the current collector to form the positive electrode film layer, the cross section taken along the thickness direction of the positive electrode tab can represent the particle size and distribution of the lithium-containing phosphate in the entire tab. When selecting the cross section, the cross section in the middle of the tab, which is relatively flat, is preferred, so that the distribution of the lithium-containing phosphate therein can be more clearly observed.

[0180] In some embodiments, the "longest diameter" refers to: cutting the positive electrode tab including the lithium-containing phosphate particles along the thickness direction of the tab to expose the longitudinal section of the positive electrode film layer; and determining the longest diameter of the lithium-containing phosphate particles by scanning electron microscopy (SEM) test on the longitudinal section of the positive electrode film layer. Specifically, the maximum value among the distances between any two points on the outer peripheral edge line of the lithium-containing phosphate particles is the "longest diameter" of the particles. In some embodiments, as shown in the longitudinal section of the tab along the thickness direction in FIG. 4, the longest diameter of the single particles satisfying the first lithium-containing phosphate particles (0.05 μm to 0.3 μm) is shown, and the shortest diameter of the single particles satisfying the second lithium-containing phosphate particles (1 μm to 3 μm) is also shown.

[0181] In the battery cell provided in 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, the direct current internal resistance of the battery cell can be further improved, thereby further reducing the heat generation of the battery, and the battery has excellent safety performance.

[0182] In the battery cell provided in the present application, when the lithium-containing phosphate as the positive electrode active material contains both the first lithium-containing phosphate particles with a longest diameter of 0.05 μm to 0.3 μm and the second lithium-containing phosphate particles with a longest diameter of 1 μm to 3 μm, the compaction density of the tab can be effectively improved by size grading, thereby making the battery cell also have a high energy density.

[0183] In some embodiments, referring to the particle distribution state in FIG. 4, in a 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.

[0184] When the number of the first lithium-containing phosphate particles having a longest diameter of 0.05 μm to 0.3 μm is greater than the number of the second lithium-containing phosphate particles having a longest diameter of 1 μm to 3 μm, the DC internal resistance and the fast charging performance of the battery can be further improved.

[0185] It should be noted that the smaller size first lithium-containing phosphate particle material having 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.

[0186] The larger size second lithium-containing phosphate particle material having 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.

[0187] A person skilled in the art can mix the two size range lithium-containing phosphate particle materials according to actual needs.

[0188] In some embodiments, the positive electrode film layer can further optionally include a positive electrode conductive agent. The present application does not have a particular limitation on the type of positive electrode conductive agent, and as an example, the positive electrode conductive agent includes at least one of super conductive carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0189] In some embodiments, the positive electrode film layer can further optionally include a positive electrode binder. The present application does not have a particular limitation on the type of positive electrode binder, and as an example, the positive electrode binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0190] In some embodiments, the areal density of the positive electrode film layer on one side is 0.33 g / 15 40.25 mm 2 to 0.4 g / 15 40.25 mm 2 , for example, 0.33 g / 15 40.25 mm 2 , 0.34 g / 15 40.25 mm 2 , 0.35 g / 15 40.25 mm 2 , 0.36 g / 15 40.25 mm 20.37g / 1540.25mm 2 0.38g / 1540.25mm 2 0.39g / 1540.25mm 2 0.4g / 1540.25mm 2 Wait, or 0.33g / 1540.25mm 2 Up to 0.4g / 1540.25mm 2 Other values ​​not listed within the range.

[0191] In some embodiments, the areal density of the positive electrode film layer on one side is 0.335 g / 1540.25 mm. 2 Up to 0.38g / 1540.25mm 2 .

[0192] In the battery cell provided in this application, when the coating surface density of the positive electrode film is within the above-mentioned range, the energy density of the battery can be further improved, and the influence of thick coating on electrochemical performance can be avoided, thereby further improving the fast charging performance of the battery.

[0193] In some embodiments, the positive electrode film layer has a dimension of W1 mm ​​along the first direction, and the negative electrode film layer has a dimension of W2 mm along the first direction, wherein W2 > W1, and the difference between W2 and W1 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.

[0194] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0195] In some embodiments, the battery cell is a wound battery. Referring to Figure 3, after the electrode sheets are unwound from their wound state, the positive current collector includes a positive current collector portion 111a and at least two positive electrode tabs 111b disposed on the same side of the positive current collector portion 111a. The positive electrode tabs 111b extend from the positive current collector portion 111a along a first direction F1. The negative current collector includes a negative current collector portion 112a and at least two negative electrode tabs 112b disposed on the same side of the negative current collector portion 112a. The negative electrode tabs 112b extend from the negative current collector portion 112a along the first direction F1. The dimension W2 of the negative electrode film layer along the first direction is greater than the dimension W1 of the positive electrode film layer along the first direction, and the difference is 3 mm to 5 mm.

[0196] In some embodiments, the battery cell is a jelly-roll battery, as shown in FIG. 1 and FIG. 2, each of the positive electrode plates comprises a positive current collector, the positive current collector comprises a positive current collecting portion 111a and a positive tab 111b disposed on the positive current collecting portion 111a, the positive tab 111b extends from the positive current collecting portion 111a along a first direction F1; each of the negative electrode plates comprises a negative current collector, the negative current collector comprises a negative current collecting portion 112a and a negative tab 112b disposed on the negative current collecting portion 112a, the negative tab 112b extends from the negative current collecting portion 112a along the first direction F1. Wherein, the dimension W2 of the negative electrode film layer along the first direction is greater than the dimension W1 of the positive electrode film layer along the first direction, and the difference is 3mm to 5mm.

[0197] During the cycle process of the battery, lithium ions that cannot be timely embedded in the negative electrode may form lithium dendrites on the surface of the negative electrode, which deteriorates the cycle performance of the battery. In the battery cell provided in the present application, when the dimension W2 of the negative electrode film layer and the dimension W1 of the positive electrode film layer have the above relationship, the formation of lithium dendrites on the surface of the negative electrode can be improved, so that the battery has good cycle performance at the same time.

[0198] In some embodiments, the positive current collector can be a metal foil or a composite current collector. As an example of the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one side surface of the polymer material base layer. As an example, the metal material can include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0199] In some embodiments, the thickness of the positive current collector is 10μm to 15μm, such as 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, or other unlisted values within the range of 10μm to 15μm.

[0200] In some embodiments, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive current collector is 5 to 12, such as 5, 6, 7, 8, 9, 10, 11, 12, or other unlisted values within the range of 5 to 12.

[0201] In some embodiments, the ratio of the single-side thickness of the positive electrode film layer to the thickness of the positive current collector is 6 to 10.

[0202] The battery cell provided in the present application has the ratio of the single-face thickness of the positive electrode film layer to the thickness of the positive electrode current collector within the above range, so that the thickness of the current collector is within a suitable range, and the problems of poor current-carrying capacity and low tensile strength leading to cracking of the electrode sheet caused by excessively thick or excessively thin current collectors are avoided, and the energy density and fast-charging performance of the battery are further improved.

[0203] In some embodiments, the positive electrode current collector comprises 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 extending from the positive electrode current collecting portion along a first direction, wherein the distance between the center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, the center lines being 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, or other values not listed in the range of 10 mm to 350 mm.

[0204] In some embodiments, the distance between the center lines 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, or other values not listed in the range of 20 mm to 330 mm.

[0205] In the battery cell provided in the present application, when the positive and negative electrode current collectors comprise at least two tabs having the above structural features, the current-carrying capacity can be further improved, the direct current resistance of the battery cell is improved, and thus the heat generation of the battery is reduced, and the battery has better safety performance.

[0206] In some embodiments, the positive electrode sheet can be prepared by dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (for example, N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained.

[0207] In some embodiments, the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 , for example, 2.30 g / cm 3 , 2.35 g / cm 32.40 g / cm 3 2.45 g / cm 3 2.50 g / cm 3 2.55 g / cm 3 2.60 g / cm 3 2.65 g / cm 3 2.70 g / cm 3 2.75 g / cm

[0208] In some embodiments, the compacted density of the positive electrode tab is 2.4 g / cm 3 3 to 2.55 g / cm 3 .

[0209] When the compacted density of the positive electrode tab is in the above range, the energy density of the battery can be further improved while ensuring the kinetic performance.

[0210] In some embodiments, the compacted density of the positive electrode tab corresponds to the compacted density of the positive electrode film layer corresponding to the battery cell in the 0% SOC state, wherein the battery cell in the 0% SOC state refers to a battery cell discharged to 2.0 V at 1 / 3 C and then discharged to 2.0 V at 0.05 C.

[0211] [Electrolyte]

[0212] The electrolyte plays a role in conducting ions between the positive electrode tab and the negative electrode tab. For example, the electrolyte can be liquid, solid or gel.

[0213] In some embodiments, the electrolyte uses an electrolyte solution. The electrolyte solution includes an electrolyte salt and an organic solvent.

[0214] In some embodiments, the organic solvent includes a carboxylic acid ester solvent and a carbonate solvent.

[0215] In the battery cell provided in the present application, when the electrolyte solution uses the above type of organic solvent, the kinetic performance of the battery can be further improved.

[0216] In some embodiments, the organic solvent includes a linear carboxylic acid ester, and the mass fraction of the linear carboxylic acid ester in the total mass of the electrolyte solution is 40% to 75%, for example, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or other non-listed values within the range of 40% to 75%.

[0217] In some embodiments, the linear carboxylic acid ester has a general structure of R1-COO-R2, wherein R1 and R2 each independently includes one or more of C1-C5 alkyl and C1-C5 halogenated alkyl.

[0218] In some embodiments, the linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, isopropyl formate.

[0219] When the electrolyte adopts the linear carboxylic acid ester of the above type and mass ratio as the organic solvent, the low viscosity of the linear carboxylic acid ester can effectively improve the conductivity of the electrolyte, thereby further improving the fast-charging performance of the battery.

[0220] In some embodiments, the organic solvent comprises a carbonate solvent, the carbonate solvent comprises a linear carbonate and a cyclic carbonate, the mass ratio of the linear carbonate to the cyclic carbonate is 2.0 to 7.0, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, or other values not listed in the range of 2.0 to 7.0.

[0221] In some embodiments, the cyclic carbonate comprises one or more of ethylene carbonate, propylene carbonate, and the linear carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0222] In some embodiments, the linear carbonate comprises dimethyl carbonate, and the mass ratio of the dimethyl carbonate to the cyclic carbonate is 2.0 to 7.0, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, or other values not listed in the range of 2.0 to 7.0.

[0223] When the electrolyte adopts the carbonate of the above type and mass ratio as the organic solvent, the side reactions and the degree of gas production of the battery during the cycle process can be improved, thereby simultaneously making the battery have good cycle performance.

[0224] In some embodiments, the organic solvent comprises dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 2.0 to 7.0, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, or other values not listed in the range of 2.0 to 7.0.

[0225] In some embodiments, the organic solvent comprises dimethyl carbonate and a linear carboxylic acid ester, and the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.0.

[0226] When the electrolyte simultaneously adopts the dimethyl carbonate and the linear carboxylic acid ester of the above mass ratio as the organic solvent, the combination of the two solvents can further improve the fast-charging performance and the cycle performance of the battery.

[0227] In some embodiments, the electrolyte further comprises a lithium salt, such as at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro-oxalato-borate, lithium bis-oxalato-borate, lithium difluoro-bis-oxalato-phosphate, and lithium tetrafluoro-oxalato-phosphate.

[0228] In some embodiments, the lithium salt has a mass fraction of 13% to 20%, such as 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or other unlisted values within the range of 13% to 20%, based on the total mass of the electrolyte.

[0229] In some embodiments, the lithium salt comprises at least two of lithium hexafluorophosphate LiPF6 and a fluorine-containing sulfonylimide salt, such as one or more of lithium bisfluorosulfonylimide LiFSI and lithium bis-trifluoromethanesulfonylimide LiTFSI.

[0230] Lithium hexafluorophosphate is less likely to produce gas during cycling, which can further improve the cycling performance of the battery. A fluorine-containing sulfonylimide salt has strong dissociation ability, which can further improve the fast-charging performance of the battery.

[0231] In some embodiments, the lithium salt comprises lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI.

[0232] In some embodiments, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonylimide LiFSI in the electrolyte 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, or other unlisted values within the range of 1.2:1 to 2:1.

[0233] When lithium hexafluorophosphate and lithium bisfluorosulfonylimide in the above mass ratio range are used in the electrolyte at the same time, the fast-charging performance and the cycling performance of the battery can be further improved.

[0234] In some embodiments, the electrolyte further comprises an additive. For example, the additive can comprise a negative electrode film-forming additive, a positive electrode film-forming additive, and can further comprise an additive capable of improving certain performance of the battery, such as an additive capable of improving the overcharge performance of the battery, an additive capable of improving the high-temperature or low-temperature performance of the battery, and the like.

[0235] In some embodiments, the electrolyte comprises a carbonate additive, such as fluoroethylene carbonate FEC and vinylene carbonate VC.

[0236] In some embodiments, the mass percentage of the carbonate additive in the electrolyte is 0.5% to 7%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 6.5%, 7%, or the like, or other values not listed in the range of 0.5% to 7%, based on the total mass of the electrolyte.

[0237] In the battery cell provided by the present application, the carbonate additive, for example, fluoroethylene carbonate and vinylene carbonate, having a mass percentage in the above range is further added to the electrolyte. The carbonate additive can form an SEI film on the surface of the negative electrode, thereby reducing the side reaction between the electrode and the electrolyte, and further improving the cycle performance of the battery.

[0238] In some embodiments, the electrolyte includes vinylene carbonate VC, and the mass percentage of the vinylene carbonate VC in the electrolyte is 0.5% to 2%, for example, 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%, or the like, or other values not listed in the range of 0.5% to 2%, based on the total mass of the electrolyte.

[0239] When the vinylene carbonate having a mass percentage in the above range is added to the electrolyte as an additive, the SEI film formed by the vinylene carbonate is stable, which is beneficial to further improving the cycle performance of the battery.

[0240] In some embodiments, the electrolyte includes fluoroethylene carbonate FEC, and the mass percentage of the fluoroethylene carbonate FEC in the electrolyte is 0.1% to 1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or the like, or other values not listed in the range of 0.1% to 1%, based on the total mass of the electrolyte.

[0241] When the fluoroethylene carbonate having a mass percentage in the above range is added to the electrolyte as an additive, the SEI film formed by the fluoroethylene carbonate has low impedance, which is beneficial to further improving the fast-charging performance of the battery.

[0242] [Separator]

[0243] In some embodiments, the battery cell further includes a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0244] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0245] [Battery cell]

[0246] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator film can be used to make an electrode assembly through a winding process or a stacking process.

[0247] In some embodiments, the positive current collector, the separator, the negative current collector, and the separator are sequentially stacked 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 shown in FIG. 6.

[0248] In some embodiments, the battery cell further comprises a top cover comprising electrode terminals of opposite polarity for electrically connecting with the positive electrode tabs or the negative electrode tabs.

[0249] In some embodiments, as shown in FIG. 6, the battery cell 10 further comprises a top cover 13 comprising two electrode terminals 131 of opposite polarity, one of which is a positive electrode terminal 131 for electrically connecting with the positive electrode tabs 111b, and the other is a negative electrode terminal 131 for electrically connecting with the negative electrode tabs 112b.

[0250] After winding, the positive electrode tabs 111b are aligned and stacked, having a larger connection area, so that the positive electrode tabs 111b can be directly electrically connected with the electrode terminals 131 without the need for a connecting tab to connect the positive electrode tabs 111b with the electrode terminals 131. Similarly, after winding, the negative electrode tabs 112b are aligned and stacked, having a larger connection area, so that the negative electrode tabs 112b can be directly electrically connected with the electrode terminals 131 without the need for a connecting tab to connect the negative electrode tabs 112b with the electrode terminals 131.

[0251] In conventional batteries, a connecting tab is needed to connect the electrode terminals with the tabs, but this results in a loss of utilization of the electrode assembly and a reduction in the energy density of the battery. When the above structure is used in the battery cell provided in the present application, the elimination of the connecting tab can effectively solve this problem, reduce the internal resistance of the battery, and further improve the energy density and fast-charging performance of the battery.

[0252] In some embodiments, the battery cell can comprise an outer package. The outer package can be used to package the above electrode assembly and the electrolyte.

[0253] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0254] In some embodiments, as shown in FIGS. 6-9, the battery cell 10 further comprises a housing 14, and the current collector 11 is disposed within the housing 14.

[0255] In some embodiments, as shown in FIGS. 6-9, the housing 14 is square, the thickness T of the housing is 30-55 mm, the width W of the housing is 150-250 mm, and the height H of the housing is 90-120 mm.

[0256] In some embodiments, the thickness T of the housing is 30-55 mm, such as 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, etc., or other unlisted values within the range of 30-55 mm.

[0257] In some embodiments, the width W of the housing is 150-250 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 150-250 mm.

[0258] In some embodiments, the height H of the housing is 90-120 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 90-120 mm.

[0259] In some embodiments, the battery cell is configured to have a charging time of 10-17 min 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 10-17 min.

[0260] The battery cell provided in the present application has excellent fast charging performance.

[0261] In some embodiments, the shape of the battery cell is not particularly limited in the present application, and it can be cylindrical, square, or any other shape. For example, FIG. 10 is a square structure of a battery cell 5 as an example. Optionally, the battery cell is a lithium ion battery or a sodium ion battery.

[0262] In some embodiments, referring to FIG. 11, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode tab, the negative electrode tab, and the separator film can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific actual needs.

[0263] In some embodiments, a battery device is provided, which can be a battery module, a battery pack, an energy storage battery, etc. The above battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0264] FIG. 12 is a battery module 4 as an example. Referring to FIG. 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, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0265] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0266] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0267] FIGS. 13 and 14 are a battery pack 1 as an example. Referring to FIGS. 13 and 14, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0268] [Electric device]

[0269] In addition, the application also provides a power utilization device comprising at least one of the battery cell, the battery module or the battery pack provided by the application. The battery cell, the battery module or the battery pack can be used as a power supply of the power utilization device, and can also be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0270] As the power utilization device, the battery cell, the battery module or the battery pack can be selected according to the use requirement thereof.

[0271] FIG. 15 is a power utilization device as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the battery cell for the power utilization device, the battery pack or the battery module can be used.

[0272] In some embodiments, the power utilization device comprises a vehicle, and the length direction of the electrode assembly is arranged along the running direction of the vehicle.

[0273] As another example of the device, the device can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the battery cell can be used as a power supply.

[0274] Embodiments

[0275] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If the specific technology or condition is not indicated in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument used is not indicated by the manufacturer, it is a conventional product that can be obtained by purchase.

[0276] Embodiment 1

[0277] 1) Negative electrode tab

[0278] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber and the thickening agent sodium carboxymethyl cellulose were mixed according to the mass ratio of 96:1:2:1, and then the solvent deionized water was added and stirred to form a negative electrode slurry. The negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, and then dried and cold-pressed to obtain a negative electrode tab; wherein the thickness of the negative electrode current collector copper foil was 4.5 μm, the single-sided area density of the negative electrode tab was 0.155 g / 1540 mm 2 , and the compacted density of the negative electrode tab was 1.47 g / cm 3, the size of the positive electrode film layer along the first direction is 92 mm; the volume particle size Dv50 of the artificial graphite is 11 pm, and the specific surface area is 5.5 m 2 / g.

[0279] 2) Positive electrode tab

[0280] The positive electrode active material lithium iron phosphate (LFP), the binder polyvinylidene fluoride, and the conductive agent acetylene black are mixed in a ratio of 97:2:1, and then a solvent N-methyl pyrrolidone (NMP) is added to stir into a positive electrode slurry; the positive electrode slurry is uniformly coated on a positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode tab is obtained. The thickness of the positive electrode current collector aluminum foil is 13 pm, the single-sided area density of the positive electrode tab is 0.341 mg / 1540 mm 2 , the tap density of the positive electrode tab is 2.51 g / cm 3 , the size of the positive electrode film layer along the first direction is 88.5 mm; the positive electrode active material contains first lithium-containing phosphate particles with a longest diameter of 0.3 pm-1 pm and second lithium-containing phosphate particles with a longest diameter of 3 pm-5 pm, and in a longitudinal cross section of the positive electrode tab, at least any region containing 100 lithium-containing phosphate particles with an olivine structure is selected, and in the any region, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

[0281] 3) Electrolyte

[0282] Dimethyl carbonate (DMC), ethyl acetate (EA), ethylene carbonate (EC), and methyl ethyl carbonate (EMC) are uniformly mixed in a mass ratio of 10:50:35:5 to obtain an electrolyte solvent. Lithium hexafluorophosphate (LiPF6) and lithium bisfluorosulfonylimide (LiFSI) are included as lithium salts, and are fully stirred until they are completely dissolved. The additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are included in a mass percentage of 0.7% and 0.3%, respectively, relative to the total mass of the electrolyte. Based on the total mass of the electrolyte, the mass percentage of lithium hexafluorophosphate (LiPF6) is 8.9%, and the mass percentage of lithium bisfluorosulfonylimide LiFSI is 4.6%. The lithium ion conductivity of the electrolyte is 14.5 mS / cm.

[0283] 4) Separating film

[0284] A polyethylene microporous film with a thickness of 7 pm and an average pore size of 80 nm is used as a separator.

[0285] 5) Battery cell

[0286] The positive electrode tab and the negative electrode tab are cut, the distance between the center lines of the two adjacent tabs of the positive electrode tab is 316 mm, and the distance between the center lines of the two adjacent tabs of the negative electrode tab is 314 mm. The positive electrode tab, the separator and the negative electrode tab are stacked and wound in sequence to obtain a wound electrode assembly, so that the positive electrode tab and the negative electrode tab of each layer of the electrode assembly have at least one tab. The electrode assembly is added to an outer packaging square aluminum shell with a thickness of 50 mm, a width of 208 mm and a height of 103 mm, and after drying, an electrolyte is injected. After packaging, standing, formation, aging, secondary packaging and capacity processes, a battery monomer is obtained, and the tabs of the battery monomer are connected with the cover plate.

[0287] Examples 2-5

[0288] The battery monomers of Examples 2-5 are basically similar to Example 1, and the difference lies in adjusting the particle size Dv50 of the graphite, as shown in Tables 1-4.

[0289] Examples 6-9

[0290] The battery monomers of Examples 6-9 are basically similar to Example 1, and the difference lies in changing the content of the carbonate additive in the electrolyte, as shown in Tables 1-4.

[0291] Examples 10-13

[0292] The battery monomers of Examples 10-13 are basically similar to Example 1, and the difference lies in changing the types or contents of the organic solvent and the lithium salt in the electrolyte, as shown in Tables 1-4.

[0293] Example 14

[0294] The battery monomer of Example 14 is basically similar to Example 1, and the difference lies in that the negative active material uses double-layer coating, and the method is as follows: the particle size Dv50 of the artificial graphite is 13 μm as the lower layer, and the particle size Dv50 of the artificial graphite is 10 μm as the upper layer, which are uniformly coated on the negative current collector copper foil, dried and cold-pressed to obtain a negative electrode tab. See Tables 1-4 for details.

[0295] Examples 15-16

[0296] The battery monomers of Examples 15-16 are basically similar to Example 1, and the difference lies in changing the thickness ratio of the single-sided film layer and the current collector of the positive and negative electrodes, as shown in Tables 1-4.

[0297] Comparative Examples 1-2

[0298] Comparative Examples 1-2 are basically similar to Example 1, and the difference lies in adjusting the particle size Dv50 and the specific surface area of the graphite, as shown in Tables 1-4.

[0299] Comparative Examples 3-4

[0300] Comparative Examples 3-4 are substantially similar to Example 1, except that the type and amount of carbonate additive in the electrolyte is changed, as shown in Tables 1-4.

[0301] I. Performance Test

[0302] 1. DC Internal Resistance

[0303] The DC internal resistance (DCR) of the battery cell can be tested according to the method in GB / T31467 "HEV High Power Lithium-ion Power Battery Performance Test Specification". For example, at room temperature, the battery cell is charged to 3.65V at a constant current of 0.33C, left for 1 min, then charged to 3.65V at a constant current of 0.1C, left for 30 min, discharged to 2.0V at a constant current of 0.33C, and the discharge capacity A0 is recorded, in Ah. Then the battery cell is charged at a constant current of 0.33C for 0.5A0 Ah, and the SOC is adjusted to 50%. After the battery cell is left at 25°C for 2h, it is discharged at a constant current of 3C for 10s, and the ΔU discharge and ΔI discharge are recorded. The discharge DCR data of the lithium-ion battery is calculated by the following formula: Rdischarge = ΔU discharge / ΔI discharge, wherein ΔU discharge represents the voltage change within 10s at the beginning of discharge, and ΔI discharge represents the current value within 10s at the beginning of discharge.

[0304] 2. Charge Time at 10%-80% SOC

[0305] Charging time test: ① Voltage calibration: 1) The positive electrode sheet, negative electrode sheet, separator and electrolyte in the example or comparative example were prepared into a stacked three-electrode battery, which was placed at 25 °C for 30 min; 2) The battery monomer was charged to a charging cutoff voltage of 3.65 V at 0.33 C at 25 °C, and then constant voltage charging was continued at the charging cutoff voltage until the current was 0.05 C, and the charging cutoff (wherein C represents the rated capacity of the battery monomer); 3) 25 °C for 1 h; 4) The battery monomer was discharged to a discharge cutoff voltage of 2.5 V at 0.33 C at 25 °C, and the total discharge capacity C0 discharged by the battery monomer was recorded; 5) 25 °C for 1 h. ② Normal temperature charging test: 1) The positive electrode sheet, negative electrode sheet, separator and electrolyte in the example or comparative example were prepared into a stacked three-electrode battery, which was placed for 30 min; 2) 0.33 C0 direct current discharge to the discharge cutoff voltage of 2.5 V, which corresponds to 0% SOC at this time; 3) 5 min of standing; 4) 5C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C1 at this time, which corresponds to C1 / C0 SOC at this time; 5) 5 min of standing; 6) 4.5C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C2 at this time, which corresponds to C2 / C0 SOC at this time; 7) 5 min of standing; 8) 4C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C3 at this time, which corresponds to C3 / C0 SOC at this time; 9) 5 min of standing; 10) 3C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C4 at this time, which corresponds to C4 / C0 SOC at this time; 11) 5 min of standing; 12) 2C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C5 at this time, which corresponds to C5 / C0 SOC at this time; 13) 5 min of standing; 14) 1C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C6 at this time, which corresponds to C6 / C0 SOC at this time; 15) 5 min of standing; 16) 0.8C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C7 at this time, which corresponds to C7 / C0 SOC at this time; 17) 5 min of standing; 18) 0.5C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C8 at this time, which corresponds to C8 / C0 SOC at this time; 19) 5 min of standing; 20) 0.33C0 constant current charging to the negative electrode potential of 0 V, reading the capacity C9 (also C0) at this time, which corresponds to 100% SOC. The total charging time from 10% SOC to 80% SOC charging process is added to obtain the required charging time.

[0306] 3. Volume energy density

[0307] At room temperature, the battery monomer was discharged at 0.33C to 2.5V, rested for 5min, charged to the upper limit cutoff voltage 3.65V at 0.33C, then charged to a current of 0.05C at constant voltage, rested for 5min; discharged to the cutoff voltage 2.5V at 0.33C, and the discharge capacity at this time was recorded to obtain the discharge energy E0. The volumetric energy density (Wh / L) = discharge energy E0 / monomer volume (L).

[0308] 4. Cycle performance

[0309] At room temperature, charge to 3.65V at 0.5C charge rate, then charge to 0.05C at constant voltage at 3.65V, rest for 10min, then discharge to 2.5V at 1C discharge rate, rest for 10min, the above one charge-discharge is one cycle, until the battery capacity decays to 80% of the nominal capacity, stop testing, recorded as the cycle number @ 80% SOH.

[0310] II. Analysis of test results of each example and comparative example

[0311] The battery monomers of each example and comparative example were prepared according to the above method, and various performance parameters were measured, and the results are shown in Tables 1-5 below.

[0312] Table 1. Negative electrode tab preparation parameters

[0313] Table 2. Positive electrode tab and electrolyte preparation parameters

[0314] Table 3. Electrolyte preparation parameters

[0315] Table 4. Electrolyte preparation parameters

[0316] Table 5. Battery performance parameters

[0317] In the battery monomers of Examples 1-16: lithium-containing phosphate containing olivine structure was used as the positive electrode active material in the positive electrode film layer; graphite with an average particle size Dv50 of 8-15μm was used as the negative electrode active material in the negative electrode film layer; FEC and VC were simultaneously contained in the electrolyte as carbonate additives, and the total mass fraction was 0.5%-7%; therefore, the battery monomers prepared in Examples 1-16 all have excellent fast-charging performance and cycle performance, as well as low DC internal resistance, and also have good energy density.

[0318] The average particle size Dv50 of the graphite in the negative electrode film layer of Comparative Examples 1-2 is outside the range of 8-15μm, wherein: the Dv50 of the graphite in Comparative Example 1 is too large, and the Dv50 of the graphite in Comparative Example 2 is too small.

[0319] From the comparison of Comparative Examples 1-2 and Examples 1-16, it can be seen that when the average particle size Dv50 of the graphite is greater than 15 μm, the fast-charging performance and the direct-current internal resistance of the battery cell cannot be effectively improved; and 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, when the average particle size Dv50 of the graphite in the negative electrode film layer is in the range of 8 μm to 15 μm, the cycle performance, the fast-charging performance and the direct-current internal resistance of the battery can be improved, and when the average particle size Dv50 of the graphite is out of the range, the comprehensive performance of the battery is poor.

[0320] In the electrolyte of Comparative Examples 3-4, the carbonate-based additive only contains one of FEC or VC, and the total mass percentage is out of the range of 0.5% to 7%, wherein: Comparative Example 3 only contains FEC, and the mass percentage is too small; and Comparative Example 4 only contains VC, and the mass percentage is too large.

[0321] From the comparison of Comparative Examples 3-4 and Examples 1-16, it can be seen that when the electrolyte only contains one kind of FEC carbonate-based additive and the mass percentage is too small, the cycle performance of the battery cell cannot be effectively improved; and when the electrolyte only contains one kind of VC carbonate-based additive and the mass percentage is too large, the fast-charging performance and the direct-current internal resistance of the battery cell cannot be effectively improved; therefore, when the electrolyte contains both FEC and VC as carbonate-based additives and the total mass percentage is 0.5% to 7%, the cycle performance, the fast-charging performance and the direct-current internal resistance of the battery can be improved; when only one of FEC or VC is contained as the additive or the mass percentage of the additive is out of the range, the comprehensive performance of the battery is poor.

[0322] In Examples 1-5, the average particle size Dv50 of the graphite in the negative electrode film layer is in the range of 8 μm to 15 μm, and the battery cell prepared thereby can have excellent energy density, fast-charging performance, cycle performance and low direct-current internal resistance. In addition, the results also show that when the Dv50 of the graphite gradually increases in 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 is decreased to a certain extent and the direct-current internal resistance is increased to a certain extent; and when the Dv50 of the graphite gradually decreases in the range of 8 μm to 15 μm, the fast-charging performance of the battery is improved to a certain extent and the direct-current internal resistance is decreased to a certain extent, but the cycle performance is decreased to a certain extent. Therefore, only when the Dv50 of the graphite in the negative electrode film layer is in the range of 8 μm to 15 μm, the fast-charging performance, the cycle performance and the direct-current internal resistance of the battery can be improved; and when the Dv50 of the 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 the graphite is too low, the energy density of the battery is reduced.

[0323] In Examples 1, 6-9, the electrolyte contains both FEC and VC as carbonate-based additives, and the total mass percentage of the two is 0.5% to 7%. The battery cells prepared by using the electrolyte have excellent energy density, fast-charging performance, cycle performance, and low DC internal resistance. In addition, the results of Examples 1, 6, and 7 show that when the mass percentage of the carbonate-based additives in the electrolyte gradually increases from 0.5% to 7%, the cycle performance of the battery is further improved. Furthermore, when the mass percentage of VC in the electrolyte is 0.5% to 2% and the mass percentage of FEC is 0.1% to 1%, the fast-charging performance, cycle performance, and DC internal resistance of the battery are further improved, and the overall performance of the battery is better.

[0324] In Examples 1, 10-13, the electrolyte is formulated as follows: the linear carboxylic acid ester (e.g., ethyl acetate) accounts for 40% to 75% of the mass percentage of the organic solvent, the linear carbonate (e.g., DMC, EMC) accounts for 10% to 40% of the mass percentage of the organic solvent, and the cyclic carbonate (e.g., ethylene carbonate) accounts for 5% to 15% of the mass percentage of the organic solvent. The mass ratio of the linear carboxylic acid ester (e.g., ethyl acetate) to the dimethyl carbonate is 2.0 to 7.0. The LiPF6 and LiFSI account for 13% to 20% of the mass percentage of the lithium salt, and the mass ratio of LiPF6 to LiFSI is 1.2:1 to 2:1. The battery cells prepared by using the electrolyte have excellent energy density, fast-charging performance, cycle performance, and low DC internal resistance.

[0325] In addition, as can be seen from Examples 1, 10, and 11, when the proportion of the linear carboxylic acid ester (e.g., ethyl acetate) and LiFSI in the electrolyte gradually increases, the fast-charging performance and DC internal resistance of the battery are further improved. When the proportion of the linear carbonate (e.g., DMC) and LiPF6 in the electrolyte gradually increases, the cycle performance of the battery is further improved.

[0326] In addition, as can be seen from Examples 1, 12, and 13, when the organic solvent of the electrolyte contains only the linear carboxylic acid ester (e.g., ethyl acetate) and no carbonate, and the lithium salt contains only LiFSI and no LiPF6, the fast-charging performance and DC internal resistance of the battery are further improved, but the cycle performance of the battery is not good. When the organic solvent of the electrolyte contains only the linear carbonate (e.g., DMC) and no linear carboxylic acid ester, and the lithium salt contains only LiPF6 and no LiFSI, the cycle performance of the battery is further improved, but the improvement in fast-charging performance and DC internal resistance is limited. Therefore, when the linear carbonate and the linear carboxylic acid ester with the above mass ratio are used as the organic solvent in the electrolyte, and the LiPF6 and LiFSI with the above mass ratio are used as the lithium salt, the fast-charging performance, DC internal resistance, and cycle performance of the battery can be further improved by matching various solvents and lithium salts, and the overall performance of the battery is better.

[0327] In Examples 1 and 14, at least one layer of graphite is included in the negative electrode film layer as the negative electrode active material, and the average particle size Dv50 thereof is in the range of 8 μm to 15 μm, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance. In addition, it can be seen from the comparison between Example 1 and Example 11 that when the negative electrode film layer includes two layers of artificial graphite having different particle sizes as the negative electrode active material layer (the first negative electrode active material layer is disposed on the surface of the negative electrode current collector, and the second negative electrode active material layer is disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, and the Dv50 of the first negative electrode active material layer is greater than that of the second negative electrode active material layer), the fast charging performance and direct current internal resistance of the battery can be further improved, and the overall performance of the battery is better.

[0328] In Examples 1 and 15-16, 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, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance. In addition, the results also show that when the ratio of the single-side 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; and when the ratio of the single-side 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, direct current internal resistance, and cycle performance of the battery can be further improved.

[0329] In Examples 1-16, as shown in FIG. 4, in the cross section of the positive electrode film layer along the thickness direction, the lithium-containing phosphates in the positive electrode film layer include first lithium-containing phosphate particles having a longest diameter of 0.05 μm to 0.3 μm and second lithium-containing phosphate particles having a longest diameter of 1 μm to 3 μm, and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance.

[0330] In Examples 1-16, the specific surface area of the graphite in the positive electrode film layer is 3 m 2 / g to 8 m 2 / g, the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.6 g / cm 3 , and the compaction density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 , and the battery cell prepared thereby can have excellent energy density, fast charging performance, cycle performance, and low direct current internal resistance.

[0331] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A battery cell, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator film located between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising a lithium-containing phosphate with an olivine structure; the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material, the negative electrode active material having an average particle size Dv50 of 8 μm to 15 μm, the negative electrode active material comprising graphite; and the electrolyte comprises a carbonate-based additive, the carbonate-based additive comprising fluoroethylene carbonate FEC and vinylene carbonate VC, the mass fraction of the carbonate-based additive being 0.5% to 7% based on the total mass of the electrolyte. The average particle size Dv50 of the negative electrode active material is 9.5 μm to 11.5 μm. The electrolyte comprises vinylene carbonate VC, the mass fraction of the vinylene carbonate VC in the electrolyte being 0.5% to 2% based on the total mass of the electrolyte. The electrolyte comprises fluoroethylene carbonate FEC, the mass fraction of the fluoroethylene carbonate FEC in the electrolyte being 0.1% to 1% based on the total mass of the electrolyte.

2. The battery cell of claim 1, wherein, The electrolyte further comprises an organic solvent, the organic solvent comprising a carboxylic acid ester solvent and a carbonate solvent.

3. The battery cell according to claim 1 or 2, characterized in that, The specific surface area of the negative active material is 3 m 2 / g to 8 m 2 / g.

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

5. The battery cell according to any one of claims 1 to 4, characterized in that, The organic solvent comprises a linear carboxylic acid ester, the mass fraction of the linear carboxylic acid ester being 40% to 75% based on the total mass of the electrolyte.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The linear carboxylic acid ester has a general structure of R1-COO-R2, wherein R1 and R2 each independently comprise one or more of C1-C5 alkyl and C1-C5 haloalkyl.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The linear carboxylic acid ester comprises one or more of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

8. The battery cell of claim 7, wherein, The organic solvent comprises a carbonate solvent, the carbonate solvent comprising a linear carbonate and a cyclic carbonate, the mass fraction of the linear carbonate being 10% to 40% based on the total mass of the electrolyte.

9. The battery cell of claim 8, wherein, The cyclic carbonate comprises one or more of vinyl carbonate and propylene carbonate, and the linear carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

10. The battery cell of claim 9, wherein, The linear carbonate comprises dimethyl carbonate, the mass fraction of the dimethyl carbonate being 5% to 15% based on the total mass of the electrolyte.

11. The battery cell according to any one of claims 7 to 10, characterized in that, The organic solvent comprises dimethyl carbonate and a linear carboxylic acid ester, the mass ratio of the linear carboxylic acid ester to the dimethyl carbonate being 2.0 to 7.

0.

12. The battery cell of claim 11, wherein, The mass ratio of the linear carboxylic acid ester to the dimethyl carbonate is 3.0 to 6.

0.

13. The battery cell of claim 12, wherein, The electrolyte further comprises a lithium salt, the mass fraction of the lithium salt being 13% to 20% based on the total mass of the electrolyte.

14. The battery cell of any one of claims 7 to 13, wherein, ​ 15. The battery cell of claim 14, wherein, ​ 16. The battery cell of any one of claims 1 to 14, wherein, ​ 17. The battery cell of claim 16, wherein, The lithium salt includes at least two of lithium hexafluorophosphate LiPF6 and a fluorine-containing sulfonimide salt including one or more of lithium bisfluorosulfonimide LiFSI and lithium bis-trifluoromethanesulfonimide LiTFSI.

18. The battery cell of claim 16, wherein, The lithium salt includes lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonimide LiFSI.

19. The battery cell of claim 18, wherein, In the electrolyte, the mass ratio of lithium hexafluorophosphate LiPF6 to lithium bisfluorosulfonimide LiFSI is 1.2:1 to 2:

1.

20. The battery cell of any one of claims 1-18, wherein, The lithium-containing phosphate of olivine structure has a general composition according to Formula I, Li x A y Me a M b P 1-c X c Y z Formula I, 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, Mg; Me includes one or more of Mn, Fe, Co, Ni; M includes one or more of Al, Ti, V, Mg. 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, Ce, one or more of; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F.

21. The battery cell of claim 19, wherein, M includes one or more of Al, Ti, V, Mg.

22. The battery cell of claim 20 or 21, wherein, 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 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 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 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, the mass content is 0.001-0.01%, based on the total mass of the positive electrode active material.

23. The battery cell of any one of claims 1-22, wherein, In the cross section of the positive electrode film layer along the thickness direction, the lithium-containing olivine 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.

24. The battery cell of claim 23, wherein, In the cross section of the positive electrode film layer along the thickness direction, the number of the first lithium-containing phosphate particles is greater than the number of the second lithium-containing phosphate particles.

25. The battery cell of any one of claims 1-24, wherein, The compacted density of the positive electrode plate is 2.3 g / cm 3 to 2.6 g / cm 3 .

26. The battery cell of any one of claims 1-24, wherein, The compacted density of the positive electrode plate is 2.4 g / cm 3 to 2.55 g / cm 3 .

27. The battery cell of any one of claims 1-26, wherein, The areal density of the positive electrode film layer on one side is 0.33 g / 1540.25 mm 2 to 0.4 g / 1540.25 mm 2 .

28. The battery cell of any one of claims 1-26, wherein, 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 .

29. The battery cell of any one of claims 1-28, wherein, The compacted density of the negative electrode sheet is 1.3 g / cm 3 to 1.6 g / cm 3 .

30. The battery cell of any one of claims 1-28, wherein, The compacted density of the negative electrode sheet is 1.35 g / cm 3 to 1.55 g / cm 3 .

31. The battery cell of any one of claims 1-30, wherein, The areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.19 g / 15 40.25 mm 2 .

32. The battery cell of any one of claims 1-30, wherein, The areal density of the negative electrode film layer on one side is 0.15 g / 15 40.25 mm 2 to 0.165 g / 15 40.25 mm 2 .

33. The battery cell of any one of claims 1-32, wherein, The thickness of the negative electrode current collector is less than or equal to 4-6 μm.

34. The battery cell of any one of claims 1-33, wherein, 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.

35. The battery cell of any one of claims 1-33, wherein, 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.

36. The battery cell of any one of claims 1-35, wherein, The negative electrode film layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, the negative electrode active material in the first negative electrode active material layer includes a first artificial graphite, and the negative electrode active material in the second negative electrode active material layer includes a second artificial graphite, the average particle size Dv50 of the first artificial graphite is greater than the average particle size Dv50 of the second artificial graphite.

37. The battery cell of claim 36, wherein, The average particle size Dv50 of the first artificial graphite is 11 μm to 15 μm.

38. The battery cell of claim 36, wherein, The average particle size Dv50 of the second artificial graphite is 8 μm to 15 μm.

39. The battery cell of claim 36, wherein, The average particle size Dv50 of the second artificial graphite is 9.5 μm to 11.5 μm.

40. The battery cell of any one of claims 1-39, wherein, The positive electrode current collector includes a positive electrode current collector portion and at least two positive electrode tabs disposed on the same side of the positive electrode current collector portion, the positive electrode tabs extending from the positive electrode current collector portion along a first direction, wherein the distance between the center lines of two adjacent positive electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction; and / or, The negative electrode current collector includes a negative electrode current collector portion and at least two negative electrode tabs disposed on the same side of the negative electrode current collector portion, the negative electrode tabs extending from the negative electrode current collector portion along a first direction, wherein the distance between the center lines of two adjacent negative electrode tabs is 10 mm to 350 mm, and the center lines are parallel to the first direction.

41. The battery cell of claim 40, wherein, The distance between the center lines of two adjacent positive electrode tabs is 20 mm to 330 mm; and / or, The distance between the center lines of two adjacent negative electrode tabs is 20 mm to 330 mm. The battery cell further includes a top cover, the top cover including a positive electrode terminal and a negative electrode terminal of opposite polarity, the positive electrode terminal and the negative electrode terminal being respectively used for electrical connection with the positive electrode tab and the negative electrode tab.

42. The battery cell of either claim 40 or 41, wherein, The dimension of the positive electrode film layer along the first direction is W1 mm, and the dimension of the negative electrode film layer along the first direction is W2 mm, wherein W2 > W1, and the difference between W2 and W1 is 3 mm to 5 mm.

43. The battery cell of any one of claims 40-42, wherein, The battery cell further includes a shell, the shell being square, the thickness of the shell being 30 mm to 55 mm, the width of the shell being 150 mm to 250 mm, and the height of the shell being 90 mm to 120 mm.

44. The battery cell of any one of claims 1-43, wherein, The battery cell is configured to have a charging time of 10-17 min from 10% SOC to 80% SOC at room temperature.

45. The battery cell of any one of claims 1-44, wherein, The battery device includes at least one of a battery module, a battery pack, and an energy storage device.

46. A battery device, comprising: The battery cell or the battery device includes any one of claims 1 to 46.

47. An electrical device, comprising: ​

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