Battery monomer, battery device and electric equipment

Abstract

The invention discloses a battery monomer, a battery device and electric equipment, and belongs to the technical field of batteries. The single battery comprises a laminated electrode assembly and an electrolyte, and the laminated electrode assembly comprises a positive pole piece, an isolating membrane and a negative pole piece which are arranged in a laminated manner; the positive pole piece comprises lithium-containing phosphate, the lithium-containing phosphate comprises a positive coating layer, the positive coating layer comprises a carbon element, and the compaction density of the positive pole piece is 2.3 g / cm < 3 > to 2.65 g / cm < 3 >; the negative pole piece comprises graphite, and the compaction density of the negative pole piece is 1.30 g / cm < 3 > to 1.52 g / cm < 3 >; the electrolyte comprises at least one of linear carbonic ester and linear carboxylic ester; the isolating membrane is arranged between the positive pole piece and the negative pole piece, the isolating membrane comprises a base membrane and an organic coating arranged on the surface of at least one side of the base membrane, and the organic coating is a continuous layer with a porous structure, so that the energy density, the cycle performance and the quick charge performance of the battery monomer can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a battery cell, a battery device, and an electrical device. Background Art

[0002] The new energy industry is attracting more and more attention. In the new energy industry, battery technology is an important factor related to its development.

[0003] The development of battery technology needs to consider many design factors, such as energy density, cycle life, service life, capacity, fast charging performance, reliability, etc. How to provide a battery cell with high energy density, fast charging performance and excellent cycle performance is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell with high energy density, fast charging performance and excellent cycle performance.

[0005] In order to achieve the above-mentioned objectives, the present application provides a battery cell, a battery device, and an electrical equipment.

[0006] In a first aspect, a battery cell is provided, comprising: a laminated electrode assembly and an electrolyte, wherein the laminated electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet which are stacked; wherein the positive electrode sheet comprises a positive electrode active material, wherein the positive electrode active material comprises a lithium-containing phosphate, wherein the lithium-containing phosphate comprises a lithium-containing phosphate matrix and a positive electrode coating layer which at least partially coats the surface of the lithium-containing phosphate matrix, wherein the positive electrode coating layer comprises carbon elements, and wherein the compaction density of the positive electrode sheet is 2.3 g / cm 3 Up to 2.65g / cm 3 The negative electrode sheet includes a negative electrode active material, the negative electrode active material includes graphite, and the compaction density of the negative electrode sheet is 1.30 g / cm 3 Up to 1.52g / cm 3 ; The electrolyte includes an organic solvent, the organic solvent includes a first solvent, the first solvent includes at least one of a linear carbonate and a linear carboxylate; the isolation membrane is arranged between the positive electrode plate and the negative electrode plate, the isolation membrane includes a base film and an organic coating arranged on at least one side surface of the base film, and the organic coating is a continuous layer of a porous structure.

[0007] In the embodiments of the present application, the battery cell includes a stacked electrode assembly. The stacked electrode assembly includes a stacked positive electrode sheet, a separator, and a negative electrode sheet. Moreover, the positive electrode sheet and the negative electrode sheet have a high compaction density. In addition, the positive electrode coating layer containing lithium phosphate includes carbon elements, and an electrolyte including at least one of a linear carbonate and a linear carboxylate is also used. The battery cell takes into account both a high energy density and good fast charging performance. The organic coating in the separator is a continuous layer with a porous structure. In this way, there is better adhesion between the separator and the positive electrode sheet and the negative electrode sheet, which can reduce the risk of gaps appearing between the separator and the positive electrode sheet and the negative electrode sheet, thereby reducing the risk of at least one organic solvent in the linear carbonate and the linear carboxylate accumulating at the gaps between the separator and the positive electrode sheet and the negative electrode sheet, reducing the adverse effect of the gas on lithium ion transport, reducing the risk of lithium deposition, and further being beneficial to improving the cycle performance of the battery cell. Therefore, the battery cell of the present application can take into account a high energy density, good fast charging performance, and good cycle performance.

[0008] In some embodiments, the organic coating includes a fluoropolymer. The organic coating including a fluoropolymer has good adhesiveness, which is beneficial to increasing the adhesion between the separator and the positive electrode sheet and the negative electrode sheet, thereby reducing the risk of lithium deposition caused by the obstruction of lithium ion transport due to the accumulation of gas between the separator and the positive electrode sheet and the negative electrode sheet, and being beneficial to improving the cycle performance of the battery cell.

[0009] In some embodiments, within an area of 50μm×50μm of the organic coating, the area ratio of the region containing the fluoropolymer is 50% to 90%.

[0010] The area ratio of the region containing the fluoropolymer can reflect the continuity of the organic coating. The larger the area ratio of the region containing the fluoropolymer, the more continuous the film structure of the organic coating, the more complete the continuous layer of the organic coating, and the fewer pores in the organic coating, which is beneficial to increasing the adhesion between the separator and the positive electrode sheet and the negative electrode sheet, and further being beneficial to reducing the risk of lithium deposition and improving the cycle performance of the battery cell. When the area ratio of the region containing the fluoropolymer within an area of 50μm×50μm is 50% to 90%, the battery cell has a low risk of lithium deposition, and thus the battery cell has good cycle performance.

[0011] In some embodiments, the fluoropolymer includes one or more of polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene copolymer. The above - mentioned fluoropolymer helps to form a continuous and uniform porous continuous layer, which is conducive to making the adhesion force at each position between the separator and the positive electrode sheet and the negative electrode sheet more uniform. Thus, the risk of lithium plating caused by the aggregation of gas between the separator and the positive electrode sheet and the negative electrode sheet, which hinders the lithium - ion transport, can be reduced, and it is beneficial to improve the cycle performance of the battery cell.

[0012] In some embodiments, the thickness of the organic coating is from 0.5 μm to 2 μm.

[0013] When the thickness of the organic coating is greater than or equal to 0.5 μm, there is a strong adhesion force between the separator and the positive electrode sheet and the negative electrode sheet. Thus, the risk of the gas generated by at least one of the organic solvents such as linear carbonates and linear carboxylates aggregating between the separator and the positive electrode sheet and the negative electrode sheet can be reduced. Thereby, the adverse effect of the gas on the lithium - ion transport can be reduced, the risk of lithium plating can be reduced, and further it is beneficial to improve the cycle performance of the battery cell; when the thickness of the organic coating is less than or equal to 2 μm, the separator occupies a suitable space, which is beneficial to improving the energy density of the battery cell.

[0014] In some embodiments, the separator further includes an inorganic coating. Along the thickness direction of the separator, the inorganic coating is disposed between the base film and the organic coating. The setting of the inorganic coating is beneficial to improving the wettability of the separator to the electrolyte, facilitating the lithium - ion transport, thus reducing the risk of lithium plating, and the battery cell has good cycle performance.

[0015] In some embodiments, the inorganic coating includes inorganic particles, and the inorganic particles include at least one of alumina, boehmite, and magnesia. The inorganic coating including the above - mentioned materials is beneficial to improving the wettability of the separator to the electrolyte, facilitating the lithium - ion transport, thus reducing the risk of lithium plating, and the battery cell has good cycle performance.

[0016] In some embodiments, the linear carbonate includes dimethyl carbonate. Dimethyl carbonate has a low viscosity, which is conducive to the lithium - ion transport; in addition, it can also make up for the deficiency of the slow lithium - ion transport when the positive electrode sheet and the negative electrode sheet have a high tap density. Through the combination of dimethyl carbonate and the positive electrode sheet and the negative electrode sheet with a high tap density, the battery cell has good fast - charging performance and a high energy density.

[0017] In some embodiments, the linear carboxylic acid ester includes R1-COO-R2, and R1 and R2 each independently include at least one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms. The linear carboxylic acid ester conforming to the above structure has a low viscosity, which is beneficial to the transport of lithium ions. In addition, it can make up for the deficiency that the transport of lithium ions slows down when the positive electrode sheet and the negative electrode sheet have a high compaction density. Through the combination of the above linear carboxylic acid ester and the positive electrode sheet and the negative electrode sheet having a high compaction density, the battery cell has good fast charging performance and a high energy density.

[0018] In some embodiments, the linear carboxylic acid ester includes at least one of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate. Through the combination of the above linear carboxylic acid ester and the positive electrode sheet and the negative electrode sheet having a high compaction density, the battery cell has good fast charging performance and a high energy density.

[0019] In some embodiments, based on the total mass of the electrolyte, the mass content of the first solvent is 8.6% to 77%.

[0020] When the mass content of the first solvent is greater than or equal to 8.6% based on the total mass of the electrolyte, the electrolyte has a low viscosity, which is beneficial to the transport of lithium ions, and the battery cell has good fast charging performance; when the mass content of the first solvent is less than or equal to 77% based on the total mass of the electrolyte, the gas generation of the linear carbonate and the linear carboxylic acid ester in the battery cell can be reduced, and further the risk that the generated gas accumulates between the separator and the positive electrode sheet and the negative electrode sheet can be reduced, and the risk of lithium plating can be reduced, which is beneficial to improving the cycle performance of the battery cell.

[0021] In some embodiments, based on the total mass of the electrolyte, the mass content of the first solvent is 34.4% to 66%. In this way, the mass content of the first solvent has a suitable range, and the battery cell can take into account good fast charging performance and cycle performance.

[0022] In some embodiments, the ionic conductivity of the electrolyte at room temperature is 9.5 mS / cm to 20 mS / cm. In this way, the electrolyte has a high ionic conductivity, which is convenient for the transport of lithium ions, is beneficial to reducing the risk of lithium plating, and improving the cycle performance and life of the battery cell.

[0023] In some embodiments, the ionic conductivity of the electrolyte at room temperature is 12 mS / cm to 16 mS / cm. In this way, the electrolyte has a high ionic conductivity, which is convenient for the transport of lithium ions, is beneficial to reducing the risk of lithium plating, and improving the cycle performance and life of the battery cell.

[0024] In some embodiments, the electrolyte includes an electrolyte salt, and the electrolyte salt includes one or more of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide. Lithium bis(fluorosulfonyl)imide has a good ability to dissociate lithium ions, and the electrolyte including lithium bis(fluorosulfonyl)imide has a high ionic conductivity; lithium hexafluorophosphate has a low cost and a relatively suitable ability to dissociate lithium ions, and the electrolyte including lithium hexafluorophosphate can be applied to more types of battery cells.

[0025] In some embodiments, based on the total mass of the electrolyte, the mass content of the electrolyte salt is 12% to 20%.

[0026] When, based on the total mass of the electrolyte, the mass content of the electrolyte salt is greater than or equal to 12%, the electrolyte has a high ionic conductivity, which facilitates the transport of lithium ions, is conducive to reducing the risk of lithium plating, and improves the cycling performance of the battery cell; when, based on the total mass of the electrolyte, the mass content of the electrolyte salt is less than or equal to 20%, the electrolyte has a relatively suitable viscosity, which facilitates the transport of lithium ions and is conducive to improving the fast charging performance of the battery cell.

[0027] In some embodiments, the electrolyte salt includes the lithium hexafluorophosphate and the lithium bis(fluorosulfonyl)imide, and the mass ratio of the lithium hexafluorophosphate to the lithium bis(fluorosulfonyl)imide is 1.2 to 3. In this way, the electrolyte has a high ionic conductivity, which facilitates the transport of lithium ions, is conducive to reducing the risk of lithium plating, and improves the cycling performance of the battery cell.

[0028] In some embodiments, the ratio of the mass of the electrolyte to the capacity of the battery cell is 2.8 g / Ah to 3.5 g / Ah. In this way, it is conducive to improving the wettability of the positive electrode plate and the negative electrode plate to the electrolyte, facilitating the transport of lithium ions, being conducive to reducing the risk of lithium plating, and improving the cycling performance of the battery cell.

[0029] In some embodiments, the ratio of the mass of the electrolyte to the capacity of the battery cell is 3.0 g / Ah to 3.2 g / Ah. In this way, it is conducive to improving the wettability of the positive electrode plate and the negative electrode plate to the electrolyte, facilitating the transport of lithium ions, being conducive to reducing the risk of lithium plating, and improving the cycling performance of the battery cell.

[0030] In some embodiments, the single-sided areal density of the positive electrode plate is 0.33 g / 1540.25 mm 2 to 0.45 g / 1540.25 mm 2 .

[0031] When the single-sided areal density of the positive electrode plate is greater than or equal to 0.33 g / 1540.25 mm 2In this case, it is beneficial to improve the energy density of the battery cell; when the single-sided areal density of the positive electrode sheet is less than or equal to 0.45 g / 1540.25 mm 2 in this case, it is beneficial to the transmission of lithium ions and beneficial to improving the fast charging performance of the battery cell.

[0032] In some embodiments, the single-sided areal density of the negative electrode sheet is 0.15 g / 1540.25 mm 2 to 0.22 g / 1540.25 mm 2 .

[0033] When the single-sided areal density of the negative electrode sheet is greater than or equal to 0.15 g / 1540.25 mm 2 in this case, it is beneficial to improve the energy density of the battery cell; when the single-sided areal density of the negative electrode sheet is less than or equal to 0.22 g / 1540.25 mm 2 in this case, it is beneficial to the transmission of lithium ions and beneficial to improving the fast charging performance of the battery cell.

[0034] In some embodiments, the positive electrode sheet includes 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 includes the positive electrode active material, and the thickness of the positive electrode current collector is 13 μm to 16 μm.

[0035] When the thickness of the positive electrode current collector is greater than or equal to 13 μm, the positive electrode sheet has good electrical conductivity, which is beneficial to improving the electronic conductivity, reducing the impedance of the battery cell, and further beneficial to improving the kinetic performance of the battery cell; when the thickness of the positive electrode current collector is less than or equal to 16 μm, the positive electrode sheet has a more appropriate thickness, which is beneficial to improving the energy density of the battery cell.

[0036] In some embodiments, the negative electrode sheet includes 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 includes the negative electrode active material, and the thickness of the negative electrode current collector is 7 μm to 10 μm.

[0037] When the thickness of the negative electrode current collector is greater than or equal to 7 μm, the negative electrode sheet has good electrical conductivity, which is beneficial to improving the electronic conductivity, reducing the impedance of the battery cell, and further beneficial to improving the kinetic performance of the battery cell; when the thickness of the negative electrode current collector is less than or equal to 10 μm, the negative electrode sheet has a more appropriate thickness, which is beneficial to improving the energy density of the battery cell.

[0038] In some embodiments, the thickness of the base film is 5 μm to 9 μm.

[0039] When the thickness of the base film is greater than or equal to 5 μm, the separator has high strength, which can reduce the risk of internal short circuit in the battery cell caused by lithium dendrites piercing the separator; when the thickness of the base film is less than or equal to 9 μm, it is beneficial to reduce the space occupied by the separator, and the battery cell has a high energy density.

[0040] In some embodiments, the porosity of the separator is 40% to 55%. In this way, the separator has a suitable porosity, which is convenient for the infiltration of the electrolyte and the transmission of lithium ions, and is beneficial to improving the fast charging performance of the battery cell.

[0041] In some embodiments, the battery cell includes a housing, the material of the housing includes an aluminum-plastic film, and the positive electrode plate and the negative electrode plate are accommodated in the space formed by the aluminum-plastic film. In this embodiment, the battery cell is a soft-pack battery cell.

[0042] In some embodiments, the average value of the longest diameter of the primary particles of the lithium-containing phosphate is 300 nm to 800 nm. In this way, the lithium ion extraction path has a suitable distance, which is beneficial to improving the power performance of the battery cell.

[0043] In some embodiments, the lithium-containing phosphate matrix includes lithium iron phosphate, and the lithium iron phosphate is doped with at least one of Al, V, and Ti. The above doping elements are beneficial to improving the performance such as the conductivity of the lithium-containing phosphate, and thus are beneficial to the capacity of the battery cell; in addition, the above doping elements are also beneficial to improving the compaction density of the positive electrode plate, and thus are beneficial to improving the energy density of the battery cell.

[0044] In some embodiments, based on the total mass of the lithium-containing phosphate, the mass content of Al is 200 ppm to 2500 ppm, the mass content of V is 300 ppm to 2000 ppm, and the mass content of Ti is 1500 ppm to 3500 ppm. The above doping elements have suitable mass contents, and the battery cell has high energy density, capacity, and cycle performance.

[0045] In some embodiments, at least part of the surface of the graphite has a coating layer, and the coating layer includes amorphous carbon. In this way, it is beneficial to the rapid insertion of lithium ions into the graphite, and is beneficial to improving the fast charging performance of the battery cell.

[0046] In some embodiments, the thickness of the coating layer is 100 nm to 500 nm. In this way, the coating layer has a suitable thickness, which is convenient for the insertion and transmission of lithium ions, and is beneficial to improving the fast charging performance of the battery cell.

[0047] In some embodiments, the graphite includes secondary particles. In this way, it is convenient for the transmission of lithium ions, and is beneficial to improving the fast charging performance of the battery cell.

[0048] In some embodiments, the graphitization degree of the graphite is 90% to 94%. In this way, the graphite has a suitable graphitization degree, which is beneficial to the graphite having a relatively suitable specific capacity and can also control the side reactions in the battery cell within a suitable range, so that the battery cell has a relatively suitable capacity and cycle life.

[0049] In some embodiments, the volume average particle size Dv50 of the graphite is 15 μm to 25 μm. In this way, the particle size of the graphite is within a suitable range, which is beneficial to improving the tap density of the negative electrode sheet, and thus beneficial to improving the energy density of the battery cell.

[0050] In some embodiments, the volume average particle size Dv50 of the graphite is 16 μm to 20 μm. In this way, the particle size of the graphite is within a suitable range, which is beneficial to improving the tap density of the negative electrode sheet, and thus beneficial to improving the energy density of the battery cell.

[0051] In some embodiments, the electrolyte includes additives, and the additives include at least one of vinylene carbonate, fluoroethylene carbonate, and 1,3 - propane sultone. The above additives are beneficial to film formation at the negative electrode, can reduce the side reactions at the negative electrode, and thus are beneficial to improving the performance such as the cycle life and kinetics of the battery cell.

[0052] In some embodiments, based on the total mass of the electrolyte, the mass content of the additive is less than or equal to 5%. The above additives have a suitable mass content, which is beneficial to improving the performance such as the cycle life and kinetics of the battery cell.

[0053] In some embodiments, based on the total mass of the electrolyte, the mass content of the additive is 0.5% to 3%. The above additives have a suitable mass content, which is beneficial to improving the performance such as the cycle life and kinetics of the battery cell.

[0054] In a second aspect, a battery device is provided, including the battery cell in the first aspect and any one of the embodiments thereof.

[0055] In a third aspect, an electrical device is provided, including the battery cell in the first aspect and any one of the embodiments thereof, or the battery device in the second aspect, and the battery cell or the battery device is used to store or provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0057] Figure 1 Schematic diagram of a separator film according to an embodiment of the present application; Figure 2 Schematic diagram of an organic coating according to an embodiment of the present application; Figure 3 Schematic diagram of a separator film according to another embodiment of the present application; Figure 4 Schematic diagram of a positive electrode plate according to an embodiment of the present application; Figure 5 Schematic diagram of a negative electrode plate according to an embodiment of the present application; Figure 6 Schematic diagram of a battery cell according to an embodiment of the present application; Figure 7 Schematic diagram of a battery device according to an embodiment of the present application; Figure 8 Schematic diagram of a vehicle according to an embodiment of the present application. Detailed implementation manners

[0058] The implementation manners of the battery cell, battery device, and electrical equipment of the present application have been described in detail with appropriate reference to the accompanying drawings, but there may be cases where unnecessary details are omitted. For example, there are cases where the detailed description of well-known matters and the repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0059] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0060] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form a new technical solution.

[0061] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0062] If there is no special instruction, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0063] This application aims to develop a battery cell with high energy density, fast charging performance, and excellent cycling performance. A battery cell formed by laminating a positive electrode sheet and a negative electrode sheet can be called a laminated battery cell, and a battery cell formed by winding a positive electrode sheet and a negative electrode sheet can be called a wound battery cell. The electrode assembly of the laminated battery cell does not have a corner structure compared to the electrode assembly of the wound battery cell. Therefore, the positive electrode sheet and the negative electrode sheet in the laminated battery cell can have a higher compaction density, and thus the laminated battery cell has a higher energy density. When the positive electrode sheet and the negative electrode sheet have a high compaction density, in order to improve the wettability of the electrolyte on the positive electrode sheet and the negative electrode sheet, setting a linear carbonate and / or a linear carboxylate solvent with low viscosity in the electrolyte is a relatively effective means, so as to balance the energy density and fast charging performance of the battery cell. However, the above solvents are prone to gas generation, and the generated gas accumulates between the separator and the positive electrode sheet and the negative electrode sheet, affecting the transmission of lithium ions, increasing the risk of lithium deposition, and being unfavorable for the improvement of cycling performance.

[0064] In view of this, this application provides a battery cell, including: a laminated electrode assembly and an electrolyte. The laminated electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet arranged in a laminated manner; the positive electrode sheet includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, the lithium-containing phosphate includes a lithium-containing phosphate matrix and a positive electrode coating layer that at least coats a part of the surface of the lithium-containing phosphate matrix, the positive electrode coating layer includes carbon elements, and the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.65 g / cm 3 ; the negative electrode sheet includes a negative electrode active material, the negative electrode active material includes graphite, and the compaction density of the negative electrode sheet is 1.30 g / cm 3 to 1.52 g / cm 3 ; the electrolyte includes an organic solvent, the organic solvent includes a first solvent, the first solvent includes at least one of a linear carbonate and a linear carboxylate; the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the separator includes a base film and an organic coating arranged on at least one surface of the base film, and the organic coating is a continuous layer with a porous structure.

[0065] In the embodiments of the present application, the battery cell includes a stacked electrode assembly, in which the negative electrode sheet and the positive electrode sheet in the stacked electrode assembly are stacked, and the positive electrode sheet and the negative electrode sheet have a high compaction density. In addition, the positive electrode coating layer containing lithium phosphate includes carbon elements, and is also paired with an electrolyte including at least one of linear carbonates and linear carboxylates. The battery cell takes into account both a high energy density and good fast charging performance. The organic coating in the separator is a continuous layer with a porous structure. In this way, there is better adhesion between the separator and the positive electrode sheet and the negative electrode sheet, which can reduce the risk of gaps appearing between the separator and the positive electrode sheet and the negative electrode sheet, thereby reducing the risk of accumulation of gas generated by at least one organic solvent in linear carbonates and linear carboxylates at the gap between the separator and the positive electrode sheet and the negative electrode sheet, thereby reducing the adverse effect of the gas on lithium ion transport and reducing the risk of lithium plating, which is beneficial to improving the cycle performance of the battery cell. Therefore, the battery cell of the present application can take into account a high energy density, good fast charging performance and good cycle performance.

[0066] In the embodiments of the present application, the battery cell is a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to be used.

[0067] The battery cell can be a lithium ion battery.

[0068] During the charging process of the battery cell, lithium ions are removed from the positive electrode active material, move and embed into the negative electrode; during the discharging process, lithium ions are removed from the negative electrode, move and embed into the positive electrode active material.

[0069] It should be understood that the "embedding" process described in the present application refers to the process in which lithium ions are embedded in the positive electrode active material or the negative electrode due to an electrochemical reaction, and the "removing" process described in the present application refers to the process in which lithium ions are removed from the positive electrode active material or the negative electrode due to an electrochemical reaction.

[0070] Generally, the battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. Next, the battery cell provided by the present application and each part in the battery cell will be introduced.

[0071] [Battery cell] The embodiments of the present application provide a battery cell, including: a stacked electrode assembly and an electrolyte, and the stacked electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet that are stacked.

[0072] The positive electrode sheet includes a positive electrode active material, the positive electrode active material includes lithium phosphate, and the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.65 g / cm 3 .

[0073] Lithium-containing phosphates can refer to phosphates of lithium-containing transition metals with an olivine structure. For example, they can include lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their modified substances, etc. Among them, the modification methods can be doping modification or surface modification. For example, in the doping modification method, elements such as titanium can be doped into, for example, lithium iron phosphate; in the surface modification method, a coating layer can be provided on the surface of, for example, lithium iron phosphate.

[0074] Lithium-containing phosphates have high structural stability, and battery monomers including lithium-containing phosphates have a long cycle life.

[0075] Lithium-containing phosphates include a lithium-containing phosphate matrix and a positive electrode coating layer that at least coats a part of the surface of the lithium-containing phosphate matrix. The positive electrode coating layer includes carbon elements. By setting the positive electrode coating layer, it is beneficial to form a continuous electron transport network on the surface of the lithium-containing phosphate, thereby facilitating electron conduction, reducing the internal resistance of the battery monomer, and further facilitating the fast charging performance improvement of the battery monomer.

[0076] In the embodiments of the present application, the positive electrode active material can be tested in the following manner. After disassembling the battery monomer, the positive electrode plate is obtained. The positive electrode plate is cut along the thickness direction of the positive electrode plate to expose the longitudinal section of the positive electrode film layer. After performing SEM testing on the longitudinal section of the positive electrode film layer and selecting lithium-containing phosphate particles, it can be observed that the lithium-containing phosphate particles are core-shell structures, that is, the lithium-containing phosphates have a positive electrode coating layer; further, in combination with energy dispersive spectrometer (EDS) to test the elements in the positive electrode coating layer, carbon elements can be measured.

[0077] In the embodiments of the present application, the tap density of the positive electrode plate is the tap density in the case where the state of charge (SOC) of the battery monomer is 0%. The tap density of the positive electrode plate can be 2.3 g / cm 3 、2.32 g / cm 3 、2.35 g / cm 3 、2.36 g / cm 3 、2.38 g / cm 3 、2.4 g / cm 3 、2.42 g / cm 3 、2.45 g / cm 3 、2.48 g / cm 3 、2.5 g / cm 3 、2.52 g / cm 3 、2.55 g / cm 3 、2.58 g / cm 3 、2.6 g / cm 3 、2.62 g / cm 3 、2.65 g / cm 3Or any value within the above range.

[0078] The negative electrode plate includes a negative electrode active material, the negative electrode active material includes graphite, and the tap density of the negative electrode plate is 1.30 g / cm 3 to 1.52 g / cm 3 .

[0079] The graphite may include at least one of natural graphite and artificial graphite.

[0080] In the embodiment of the present application, the tap density of the negative electrode plate is the tap density under the condition that the state of charge (SOC) of the battery cell is 0%. The tap density of the negative electrode plate can be 1.3 g / cm 3 , 1.32 g / cm 3 , 1.35 g / cm 3 , 1.38 g / cm 3 , 1.4 g / cm 3 , 1.42 g / cm 3 , 1.45 g / cm 3 , 1.48 g / cm 3 , 1.5 g / cm 3 , 1.52 g / cm 3 Or any value within the above range.

[0081] The tap densities of the negative electrode plate and the positive electrode plate can be measured as follows. At 25°C, the battery cell is discharged at a constant current of 0.33C to 2.0V to obtain a battery cell with 0% SOC. Then, the positive and negative electrode plates are removed from the battery cell, the thickness of the electrode plate and the thickness of the current collector are measured respectively, and the electrode plate is punched into small circular pieces with an area of S1 (if it is a double-sided coated electrode plate, the film layer on one side can be wiped off first), weighed, and recorded as M1. Then, the film layer of the above weighed electrode plate is wiped off, and the weight of the current collector is weighed and recorded as M0. The areal density of a single side = (M1 - M0) / S1. The tap density = areal density / (electrode plate thickness - current collector thickness).

[0082] In the stacked electrode assembly, the negative electrode plate, the separator, and the positive electrode plate are stacked.

[0083] As an example, the battery cell includes a plurality of positive electrode plates and a plurality of negative electrode plates, and the plurality of positive electrode plates and the plurality of negative electrode plates are stacked. In addition, the battery cell further includes a separator, and the separator is disposed between the positive electrode plate and the negative electrode plate to isolate the positive electrode plate and the negative electrode plate.

[0084] As another example, a battery cell includes a positive electrode tab and a plurality of negative electrode tabs. The positive electrode tab includes a plurality of straight positive electrode segments and a plurality of bent positive electrode segments. The straight positive electrode segments are connected to the bent positive electrode segments, and the plurality of straight positive electrode segments and the plurality of negative electrode tabs are stacked.

[0085] As yet another example, a battery cell includes a plurality of positive electrode tabs and a negative electrode tab. The negative electrode tab includes a plurality of straight negative electrode segments and a plurality of bent negative electrode segments. The straight negative electrode segments are connected to the bent negative electrode segments, and the plurality of bent negative electrode segments and the plurality of positive electrode tabs are stacked.

[0086] In a stacked electrode assembly in which a negative electrode tab, a separator, and a positive electrode tab are stacked, the electrode assembly has substantially no or no bent region, and the battery cell with such a structure can also be a stacked battery cell.

[0087] The electrolyte includes an organic solvent, and the organic solvent includes a first solvent. The first solvent includes at least one of a linear carbonate and a linear carboxylate.

[0088] The linear carbonate and the linear carboxylate have low viscosities. The electrolyte including the linear carbonate and the linear carboxylate has a low viscosity, which is beneficial to improving the wettability of the electrolyte on the positive electrode tab and the negative electrode tab, thereby being beneficial to enhancing the kinetic performance of the battery cell, and the battery cell has good fast charging performance.

[0089] The linear carbonate may have the general formula RO-CO-OR', where R and R' are substituted or unsubstituted alkyl groups.

[0090] As an example, the linear carbonate may include at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0091] The linear carboxylate may have the general formula R1-COO-R2, where R1 and R2 may be substituted or unsubstituted alkyl groups.

[0092] As an example, the linear carboxylate may include at least one of methyl acetate and ethyl acetate.

[0093] In the embodiments of the present application, the linear carbonate and the linear carboxylate can be obtained by the following method. After disassembling the battery cell, the electrolyte of the battery cell is obtained, and then the components of the organic solvent in the electrolyte can be qualitatively and quantitatively analyzed by an organic gas chromatography analysis method with reference to the standard GB / T9722-2006.

[0094] The separator is disposed between the positive electrode tab and the negative electrode tab. In this way, the positive electrode tab and the negative electrode tab can be isolated.

[0095] Figure 1 Schematic diagram of the separator for an embodiment of the present applicationFigure 2 Schematic diagram of an organic coating according to an embodiment of the present application. In combination with Figure 1 and Figure 2 As shown, the separator membrane 8 includes a base film 80 and an organic coating 801 provided on at least one surface of the base film 80, and the organic coating 801 is a continuous layer with a porous structure.

[0096] The base film 80 has two surfaces opposite to each other in its own thickness direction, and the organic coating 801 can be provided on one surface of the base film 80 or on both surfaces of the base film 80.

[0097] As an example, organic coatings 801 are provided on both surfaces of the base film 80.

[0098] The organic coating 801 being a continuous layer with a porous structure means that the organic coating 801 has a continuous film-like structure. The continuous film-like structure here is in contrast to isolated dot-like or island-like structures. The organic coating 801 has a continuous film-like structure, so that the organic coating 801 is a whole, and compared with multiple discontinuous dot-like or island-like film-like structures, it can increase the bonding area between the separator membrane and the positive electrode plate and the negative electrode plate, thereby increasing the bonding force and making the bonding between the separator membrane and the positive electrode plate and the negative electrode plate more firm and uniform.

[0099] The organic coating 801 has pores 8011, and the number of pores 8011 can be one or more. Each pore 8011 can have the same or different shapes and can also have the same or different areas. For example, the shape of the pore 8011 can be circular, oval or other irregular shapes.

[0100] The material of the organic coating 801 can include polymers, such as fluoropolymers. The organic coating 801 has a certain adhesiveness. In this way, in a battery cell, the separator membrane 8 can be bonded to the positive electrode plate and the negative electrode plate through the organic coating 801. The above bonding can be achieved by hot pressing the stacked separator membrane, positive electrode plate and negative electrode plate during the preparation of the battery cell.

[0101] It can be understood that the continuous layer of the porous structure may break and deform into a block structure during the manufacturing of the electrode sheet or the cycling process due to contact or extrusion stress with the positive electrode sheet or the negative electrode sheet. The continuous structure referred to in this application means that at the microscopic level, such as observed under a scanning electron microscope or an optical microscope, the organic coating of the separator is continuous. In order to reflect the true morphology of the separator, during the sampling process, it is preferably sampled in the area where the organic coating of the separator in the battery cell does not bond with the positive electrode sheet or the negative electrode sheet. As an example, sampling is performed at the position of the separator beyond the positive electrode sheet and the negative electrode sheet; or sampling is performed on the separator near the surface of the electrode assembly. The bonding between the sampling area of the separator and the positive electrode sheet or the negative electrode sheet is less, and it can better reflect the true state of the separator.

[0102] The organic coating 801 is a continuous layer of a porous structure. In this way, the separator has better adhesion to the positive electrode sheet and the negative electrode sheet, which can reduce the risk of gaps appearing between the separator and the positive electrode sheet and the negative electrode sheet. Thus, it can reduce the risk of gas generated by at least one of the organic solvents such as linear carbonates and linear carboxylates accumulating at the gap between the separator and the positive electrode sheet and the negative electrode sheet, reduce the adverse effect of the gas on lithium ion transport, reduce the risk of lithium plating, and further facilitate improving the cycling performance of the battery cell.

[0103] In the embodiment of this application, the negative electrode sheet and the positive electrode sheet in the battery cell are stacked, and the positive electrode sheet and the negative electrode sheet have a high compaction density. In addition, an electrolyte including at least one of linear carbonates and linear carboxylates is used. The battery cell takes into account both a high energy density and good fast charging performance. The organic coating 801 is a continuous layer of a porous structure. In this way, the separator has better adhesion to the positive electrode sheet and the negative electrode sheet, which can reduce the risk of gaps appearing between the separator and the positive electrode sheet and the negative electrode sheet. Thus, it can reduce the risk of gas generated by at least one of the organic solvents such as linear carbonates and linear carboxylates accumulating at the gap between the separator and the positive electrode sheet and the negative electrode sheet, reduce the adverse effect of the gas on lithium ion transport, reduce the risk of lithium plating, and further facilitate improving the cycling performance of the battery cell. Therefore, the battery cell of this application can take into account a high energy density, good fast charging performance, and good cycling performance.

[0104] In addition, in the embodiments of the present application, compared with the wound electrode assembly, in the stacked electrode assembly, the extrusion between the separator and the electrode sheet is smaller, and relative displacement is likely to occur between the separator and the electrode sheet, thereby disturbing the film layer (for example, the positive electrode film layer including the positive electrode active material or the negative electrode film layer including the negative electrode active material), and the film layer is liable to generate powder falling or peeling off; in addition, it may also cause the positive and negative electrodes to be mutually overlapped, increasing the risk of internal short circuit in the battery cell. The bonding force between the organic coating and the electrode sheet in the embodiments of the present application is increased, which helps to improve the bonding force between the separator and the electrode sheet, and reduce the relative displacement between the separator and the electrode sheet. This not only helps to reduce the disturbance to the film layer and lower the probability of film layer peeling off, but also helps to reduce the risk of short circuit of the battery cell caused by the overlap of the positive and negative electrodes.

[0105] In some embodiments, the organic coating includes a fluoropolymer.

[0106] The organic coating including a fluoropolymer has good adhesiveness, which is beneficial to increasing the bonding force between the separator and the positive electrode sheet and the negative electrode sheet, thereby reducing the risk that gas accumulates between the separator and the positive electrode sheet and the negative electrode sheet, resulting in the blockage of lithium ion transmission and further leading to the risk of lithium deposition, and is beneficial to improving the cycle performance of the battery cell.

[0107] In the embodiments of the present application, the fluoropolymer in the organic coating can be measured in the following manner. After disassembling the battery cell, the separator is obtained, soaked in DMC for 1 h, the DMC is replaced, and soaking is continued for a total of 3 times. The surface of the separator is scanned using a scanning electron microscope (SEM), an area is randomly selected, and an energy dispersive spectrometer (EDS) is used to identify the elements in this area. When fluorine element is detected, it can be determined that the organic coating includes a fluoropolymer.

[0108] In some embodiments, within an area of 50 μm×50 μm of the organic coating, the area ratio of the area containing the fluoropolymer is 50% to 90%.

[0109] As an example, since the organic coating 801 does not completely cover the surface of the base film 80, the ratio of the area of the area containing the fluoropolymer in the organic coating to the total area of the base film is less than 100%.

[0110] Within an area of 50 μm×50 μm of the organic coating, the area ratio of the area containing the fluoropolymer is the ratio of the area of the area containing the fluoropolymer to the area of 50 μm×50 μm.

[0111] Within an area of 50 μm×50 μm, the area ratio of the area containing the fluoropolymer can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or any value within the above range.

[0112] The area proportion of the region containing the fluoropolymer can reflect the continuity of the film structure of the organic coating. The larger the area proportion of the region containing the fluoropolymer, the more continuous and complete the continuous layer of the organic coating is, and the larger the bonding area between the separator and the positive electrode plate and the negative electrode plate, which is beneficial to improving the bonding force between the separator and the positive electrode plate and the negative electrode plate, and further beneficial to reducing the risk of lithium deposition and improving the cycle performance of the battery cell. When the area proportion of the region containing the fluoropolymer is greater than or equal to 50% within an area of 50μm×50μm, it is beneficial to improve the bonding force between the separator and the positive electrode plate and the negative electrode plate; when the area proportion of the region containing the fluoropolymer is less than or equal to 90% within an area of 50μm×50μm, it is also beneficial to the infiltration of the electrolyte into the separator and beneficial to the transport of lithium ions. Therefore, when the area proportion of the region containing the fluoropolymer is 50% to 90% within an area of 50μm×50μm, the battery cell has a lower risk of lithium deposition, and thus the battery cell has better cycle performance.

[0113] In the embodiments of the present application, the area proportion of the region containing the fluoropolymer within an area of 50μm×50μm can be tested in the following manner. After disassembling the battery cell, the separator is obtained, samples are taken at the position of the separator beyond the positive electrode plate and the negative electrode plate, and the separator is placed under a scanning electron microscope to test the ratio of the area of the continuous layer within a field of view of 50μm×50μm to the area of 50μm×50μm.

[0114] In some embodiments, the organic coating can be prepared in the following manner. For example, a binder and a pore former are dissolved in an organic solvent to obtain a binder solution; the binder solution is applied to the base film, and after drying, the pore former is removed to form an organic coating on the base film.

[0115] In some embodiments, different area proportions of the region containing the fluoropolymer can be achieved by adjusting the mass proportion of the pore former in the binder solution.

[0116] In some embodiments, the fluoropolymer includes one or more of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride - hexafluoropropylene copolymer (PVDF - HFP).

[0117] The above-mentioned fluoropolymer helps to form a continuous and uniform porous continuous layer. It is beneficial to make the bonding force at each position between the separator and the positive electrode plate and the negative electrode plate more uniform, so as to reduce the risk of lithium deposition caused by the aggregation of gas between the separator and the positive electrode plate and the negative electrode plate, which hinders the transport of lithium ions, and is beneficial to improving the cycle performance of the battery cell.

[0118] In addition, the adhesion between the organic coating and the electrode sheet is improved and evenly distributed, which helps to reduce the stress concentration phenomenon in the positive electrode film layer caused by the relatively high compaction density of the positive electrode sheet (high compaction density is accompanied by a thicker coating of lithium-containing phosphate), thereby helping to further improve the cycle life of the battery; the stable adhesion between the organic coating and the positive electrode sheet or the negative electrode sheet helps to reduce the direct contact between the positive electrode sheet and the negative electrode sheet caused by the relative displacement between the electrode sheet and the separator, reducing the risk of internal short circuit and helping to improve the safety performance of the battery cell; furthermore, the organic coating helps to maintain the porosity of the separator, reserving space for the expansion of the battery cell and further improving the cycle life of the battery cell.

[0119] In some embodiments, the thickness of the organic coating is from 0.5 μm to 2 μm.

[0120] The thickness of the organic coating can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 1.9 μm, 2 μm or any value within the above range.

[0121] The thickness of the organic coating 801 can be the average thickness of the organic coating. As an example, along the length direction of the separator (e.g., the x direction), the thicknesses at multiple positions (e.g., 10 positions) are respectively measured by a scanning electron microscope (SEM), and the average value of the multiple thicknesses is taken as the thickness D1 of the organic coating.

[0122] When the thickness of the organic coating is greater than or equal to 0.5 μm, there is a strong adhesion between the separator and the positive electrode sheet and the negative electrode sheet, thereby reducing the risk of gas accumulation between the separator and the positive electrode sheet and the negative electrode sheet generated by at least one organic solvent in linear carbonates and linear carboxylates, reducing the adverse effect of the gas on lithium ion transport, reducing the risk of lithium deposition, and thus being beneficial to improving the cycle performance of the battery cell; when the thickness of the organic coating is less than or equal to 2 μm, the separator occupies a suitable space, which is beneficial to improving the energy density of the battery cell.

[0123] Figure 3 Schematic diagram of the separator according to another embodiment of the present application. In some embodiments, for example, as Figure 3 shown, the separator 8 further includes an inorganic coating 802, and the inorganic coating 802 is disposed between the base film 80 and the organic coating 801 along the thickness direction of the separator 8.

[0124] The separator 8 may include one layer of inorganic coating 802 or may include two layers of inorganic coating 802. That is, along one side surface of the base film, an inorganic coating 802 is disposed between the base film 80 and the organic coating 801; or, along both side surfaces of the base film, an inorganic coating 802 is disposed between the base film 80 and the organic coating 801.

[0125] The setting of the inorganic coating 802 is beneficial to improving the wettability of the separator membrane to the electrolyte, facilitating the transport of lithium ions, thereby reducing the risk of lithium deposition, and the battery cell has good cycle performance.

[0126] In some embodiments, the inorganic coating includes inorganic particles, and the inorganic particles include at least one of alumina, boehmite, and magnesia. The inorganic coating including the above materials is beneficial to improving the wettability of the separator membrane to the electrolyte, facilitating the transport of lithium ions, thereby reducing the risk of lithium deposition, and the battery cell has good cycle performance.

[0127] In some embodiments, the linear carbonate includes dimethyl carbonate.

[0128] Dimethyl carbonate has a low viscosity, which is beneficial to the transport of lithium ions; in addition, it can also make up for the deficiency of slow lithium ion transport in the case where the positive electrode sheet and the negative electrode sheet have a high tap density. Through the combination of dimethyl carbonate and the positive electrode sheet and the negative electrode sheet with a high tap density, the battery cell has good fast charging performance and a high energy density.

[0129] In some embodiments, the linear carboxylic acid ester includes R1-COO-R2, and R1 and R2 each independently include at least one of a C1-C5 alkyl group and a C1-C5 haloalkyl group.

[0130] The linear carboxylic acid ester conforming to the above structure has a low viscosity, which is beneficial to the transport of lithium ions. In addition, it can also make up for the deficiency of slow lithium ion transport in the case where the positive electrode sheet and the negative electrode sheet have a high tap density. Through the combination of the above linear carboxylic acid ester and the positive electrode sheet and the negative electrode sheet with a high tap density, the battery cell has good fast charging performance and a high energy density.

[0131] In some embodiments, the linear carboxylic acid ester includes at least one of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate. Through the combination of the above linear carboxylic acid ester and the positive electrode sheet and the negative electrode sheet with a high tap density, the battery cell has good fast charging performance and a high energy density.

[0132] In some embodiments, based on the total mass of the electrolyte, the mass content of the first solvent is 8.6% to 77%, for example, it can be 8.6%, 9%, 9.5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 77% or any value within the above range.

[0133] In the case of a total mass-based electrolyte, when the mass content of the first solvent is greater than or equal to 8.6%, the electrolyte has a lower viscosity, which is beneficial to the transport of lithium ions, and the battery cell has better fast charging performance; in the case of a total mass-based electrolyte, when the mass content of the first solvent is less than or equal to 77%, the gas generation of linear carbonates and linear carboxylates in the battery cell can be reduced, and thus the risk of gas accumulation between the separator and the positive electrode plate and the negative electrode plate can be reduced, the risk of lithium plating can be reduced, which is beneficial to improving the cycle performance of the battery cell.

[0134] In some embodiments, based on the total mass of the electrolyte, the mass content of the first solvent is 34.4% to 66%. In this way, the mass content of the first solvent has a suitable range, and the battery cell can take into account better fast charging performance and cycle performance.

[0135] In some embodiments, the organic solvent includes a second solvent, and the second solvent includes a cyclic carbonate. The cyclic carbonate has a good ability to dissociate electrolyte salts, which is beneficial to the transport of lithium ions.

[0136] The cyclic carbonate may include at least one of ethylene carbonate and propylene carbonate.

[0137] In some embodiments, the ionic conductivity of the electrolyte at room temperature is 9.5 mS / cm to 20 mS / cm. For example, it can be 9.5 mS / cm, 10 mS / cm, 11 mS / cm, 12 mS / cm, 12.5 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, 20 mS / cm or any value within the above range. In this way, the electrolyte has a high ionic conductivity, which is convenient for the transport of lithium ions, is beneficial to reducing the risk of lithium plating, and improving the cycle performance and lifespan of the battery cell.

[0138] Room temperature may refer to the range of 20°C to 30°C.

[0139] In some embodiments, the ionic conductivity of the electrolyte at room temperature is 12 mS / cm to 16 mS / cm. In this way, the electrolyte has a high ionic conductivity, which is convenient for the transport of lithium ions, is beneficial to reducing the risk of lithium plating, and improving the cycle performance and lifespan of the battery cell.

[0140] In some embodiments, the electrolyte includes an electrolyte salt, and the electrolyte salt includes at least one of lithium hexafluorophosphate and lithium bisfluorosulfonyl imide. Lithium bisfluorosulfonyl imide has a good ability to dissociate lithium ions, and the electrolyte including lithium bisfluorosulfonyl imide has a high ion conductivity; lithium hexafluorophosphate has a low cost and a more suitable ability to dissociate lithium ions, and the electrolyte including lithium hexafluorophosphate can be applied to more types of battery cells.

[0141] In some embodiments, the electrolyte salt includes lithium hexafluorophosphate and lithium bisfluorosulfonyl imide. Lithium bisfluorosulfonyl imide has a good ability to dissociate lithium ions. By combining lithium hexafluorophosphate and lithium bisfluorosulfonyl imide, the electrolyte has a higher ion conductivity.

[0142] In some embodiments, the mass content of the electrolyte salt is 12% to 20% based on the total mass of the electrolyte, for example, 12%, 13%, 15%, 16%, 18%, 19%, 20% or any value within the above range.

[0143] When the mass content of the electrolyte salt is greater than or equal to 12% based on the total mass of the electrolyte, the electrolyte has a higher ionic conductivity, which is convenient for the transmission of lithium ions, which is beneficial to reducing the risk of lithium precipitation and improving the cycle performance of the battery cell; when the mass content of the electrolyte salt is less than or equal to 20% based on the total mass of the electrolyte, the electrolyte has a more suitable viscosity, which is convenient for the transmission of lithium ions and is beneficial to improving the fast charging performance of the battery cell.

[0144] In some embodiments, the electrolyte salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, and the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is 1.2 to 3, for example, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3 or any value within the above range. In this way, the electrolyte has a high ionic conductivity, which is convenient for the transmission of lithium ions, helps to reduce the risk of lithium precipitation, and improves the cycle performance of the battery cell.

[0145] In the embodiment of the present application, the type and content of the organic components in the electrolyte can be detected using equipment and methods known in the art. For example, reference can be made to GB / T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents" to perform qualitative and quantitative analysis of organic solvents in the electrolyte by gas chromatography.

[0146] In the embodiments of the present application, the types and contents of the inorganic components / lithium salt concentrations in the electrolyte are well known in the art and can be detected using equipment and methods well known in the art. For example, the inorganic components / lithium salt concentrations in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography analysis method with reference to standard JY / T020-1996 "General Rules for Ion Chromatography Analysis Methods".

[0147] In the embodiments of the present application, the ionic conductivity of the electrolyte to be measured can be tested with a conductivity meter in accordance with HG / T 4067-2015: Take about 100 ml of the sample to be measured with a dry, clean and corrosion-resistant sample bottle, seal it and place it in a constant temperature water bath at 25±0.5 °C. When the temperature of the sample to be measured is constant, replace the sample bottle cap with a rubber stopper inserted with electrodes. When the temperature is within the range of 25±0.5 °C, read the data, which is the ionic conductivity of the sample to be measured.

[0148] In the embodiments of the present application, the newly prepared electrolyte can be taken as the sample, the free electrolyte of the fresh battery cell can be taken as the sample, or the battery cell that has been fully discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery cell is taken as the sample.

[0149] In the embodiments of the present application, after quantitatively and qualitatively detecting each component in the electrolyte, the composition and mass content of the solvent and the lithium salt can be determined based on the mass of the electrolyte.

[0150] In some embodiments, the ratio of the mass of the electrolyte to the capacity of the battery cell is 2.8 g / Ah to 3.5 g / Ah, for example, 2.8 g / Ah, 2.9 g / Ah, 3.0 g / Ah, 3.1 g / Ah, 3.2 g / Ah, 3.3 g / Ah, 3.4 g / Ah, 3.5 g / Ah or any value within the above range. In this way, it is beneficial to improve the wettability of the positive electrode plate and the negative electrode plate to the electrolyte, facilitate the transmission of lithium ions, reduce the risk of lithium deposition, and improve the cycle performance of the battery cell.

[0151] In some embodiments, the ratio of the mass of the electrolyte to the capacity of the battery cell is 3.0 g / Ah to 3.2 g / Ah. In this way, it is beneficial to improve the wettability of the positive electrode plate and the negative electrode plate to the electrolyte, facilitate the transmission of lithium ions, reduce the risk of lithium deposition, and improve the cycle performance of the battery cell.

[0152] In some embodiments, the single-sided density of the positive electrode plate is 0.33 g / 1540.25 mm 2 to 0.45 g / 1540.25 mm 2 , for example, it can be 0.33 g / 1540.25 mm 2 , 0.34 g / 1540.25 mm 2 , 0.36 g / 1540.25 mm 2 , 0.38 g / 1540.25 mm 2 , 0.40 g / 1540.25 mm 2 , 0.41 g / 1540.25 mm 2, 0.42 g / 1540.25 mm 2 , 0.43 g / 1540.25 mm 2 , 0.44 g / 1540.25 mm 2 , 0.45 g / 1540.25 mm 2 or any value within the above range.

[0153] When the single-sided density of the positive electrode sheet is greater than or equal to 0.33 g / 1540.25 mm 2 , it is beneficial to improve the energy density of the battery cell; when the single-sided density of the positive electrode sheet is less than or equal to 0.45 g / 1540.25 mm 2 , it is beneficial to the transmission of lithium ions and beneficial to improving the fast charging performance of the battery cell.

[0154] In some embodiments, the single-sided density of the negative electrode sheet is 0.15 g / 1540.25 mm 2 to 0.22 g / 1540.25 mm 2 , for example, it can be 0.15 g / 1540.25 mm 2 , 0.16 g / 1540.25 mm 2 , 0.17 g / 1540.25 mm 2 , 0.18 g / 1540.25 mm 2 , 0.19 g / 1540.25 mm 2 , 0.20 g / 1540.25 mm 2 , 0.21 g / 1540.25 mm 2 , 0.22 g / 1540.25 mm 2 or any value within the above range.

[0155] When the single-sided density of the negative electrode sheet is greater than or equal to 0.15 g / 1540.25 mm 2 , it is beneficial to improve the energy density of the battery cell; when the single-sided density of the negative electrode sheet is less than or equal to 0.22 g / 1540.25 mm 2 , it is beneficial to the transmission of lithium ions and beneficial to improving the fast charging performance of the battery cell.

[0156] Figure 4 is a schematic diagram of the positive electrode sheet of an embodiment of the present application. In some embodiments, for example, as Figure 4As shown, the positive electrode plate 5 includes a positive current collector 50 and a positive electrode film layer 51 disposed on at least one surface of the positive current collector. The positive electrode film layer 51 includes positive active materials. The thickness D3 of the positive current collector 50 is from 13 μm to 16 μm, and for example, it can be 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, or any value within the above range.

[0157] The positive current collector 50 has two surfaces opposite to each other along its own thickness direction. The positive electrode film layer 51 can be disposed on one surface of the positive current collector or on both surfaces of the positive current collector.

[0158] When the thickness of the positive current collector is greater than or equal to 13 μm, the positive electrode plate has good electrical conductivity, which is beneficial to improving the electronic conductivity, reducing the impedance of the battery cell, and thus beneficial to improving the kinetic performance of the battery cell; when the thickness of the positive current collector is less than or equal to 16 μm, the positive electrode plate has a more appropriate thickness, which is beneficial to improving the energy density of the battery cell.

[0159] Figure 5 It is a schematic diagram of the negative electrode plate of an embodiment of the present application. In some embodiments, for example, as Figure 5 As shown, the negative electrode plate 6 includes a negative current collector 60 and a negative electrode film layer 61 disposed on at least one surface of the negative current collector 60. The negative electrode film layer 61 includes negative active materials. The thickness of the negative current collector 60 is from 7 μm to 10 μm, and for example, it can be 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, or any value within the above range.

[0160] The negative current collector 60 has two surfaces opposite to each other along its own thickness direction. The negative electrode film layer 61 can be disposed on one surface of the negative current collector or on both surfaces of the negative current collector.

[0161] The thickness of the negative current collector is the average thickness. For example, after disassembling the battery cell to obtain the negative electrode plate, along the length direction of the negative electrode plate (for example, the x direction), then use a micrometer to measure the thickness of the negative current collector at multiple positions (for example, 10 positions) respectively, and take the average value of the multiple thicknesses as the thickness D4 of the negative current collector.

[0162] When the thickness of the negative current collector is greater than or equal to 7 μm, the negative electrode plate has good electrical conductivity, which is beneficial to improving the electronic conductivity, reducing the impedance of the battery cell, and thus beneficial to improving the kinetic performance of the battery cell; when the thickness of the negative current collector is less than or equal to 10 μm, the negative electrode plate has a more appropriate thickness, which is beneficial to improving the energy density of the battery cell.

[0163] In some embodiments, the thickness of the base film is 5 μm to 9 μm, and for example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 8.5 μm, 9 μm, or any value within the above range.

[0164] The thickness of the base film is the average thickness. Along the length direction of the separator film (e.g., the x direction), the thickness of the base film at multiple positions (e.g., 10 positions) is respectively measured using a micrometer, and the average value of the multiple thicknesses is taken as the thickness D2 of the base film.

[0165] The material of the base film may include at least one of polyethylene and polypropylene.

[0166] When the thickness of the base film is greater than or equal to 5 μm, the separator film has higher strength, which can reduce the risk of internal short circuit in the battery cell caused by lithium dendrites piercing the separator film; when the thickness of the base film is less than or equal to 9 μm, it is beneficial to reduce the space occupied by the separator film, and the battery cell has a higher energy density.

[0167] In some embodiments, the porosity of the separator film is 40% to 55%, and for example, it can be 40%, 42%, 45%, 48%, 50%, 52%, 55%, or any value within the above range. In this way, the separator film has an appropriate porosity, which is convenient for the infiltration of the electrolyte and the transmission of lithium ions, and is beneficial to improving the fast charging performance of the battery cell.

[0168] Figure 6 It is a schematic diagram of a battery cell according to an embodiment of the present application. In some embodiments, for example, as Figure 6 shown, the battery cell 3 includes a housing 31, and the material of the housing 31 includes an aluminum-plastic film. The positive electrode plate and the negative electrode plate are accommodated in the space formed by the aluminum-plastic film. In this embodiment, the battery cell is a soft-pack battery cell.

[0169] The aluminum-plastic film is a multi-layer composite flexible packaging material, which can be a material formed by laminating a polymer outer layer, an aluminum film intermediate layer, and a polymer inner layer. Compared with an aluminum shell or a steel shell, the battery cell prepared with the aluminum-plastic film material is a soft-pack battery cell.

[0170] The battery cell 3 further includes a stacked electrode assembly, and the stacked electrode assembly includes a positive electrode plate, a separator film, and a negative electrode plate stacked together. The stacked electrode assembly is accommodated in the housing 31.

[0171] In some embodiments, the battery cell 3 further includes a positive electrode terminal 321 and a negative electrode terminal 322, and the positive electrode terminal 321 and the negative electrode terminal 322 are oppositely arranged along the length direction of the battery cell. Among them, the positive electrode terminal 321 and the negative electrode terminal 322 are respectively connected to the positive electrode tab and the negative electrode tab.

[0172] In some embodiments, the average value of the longest diameter of the primary particles of the lithium-containing phosphate is 300 nm to 800 nm, and for example, it can be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm or any value within the above range. In this way, the lithium ion extraction path has an appropriate distance, which is beneficial to improving the power performance of the battery cell.

[0173] In the embodiments of the present application, the primary particle refers to the smallest unit of the particle within a certain observation range. There may be any form of defects inside the primary particle, but smaller particles cannot be further defined within the primary particle. The primary particles may aggregate under physical actions such as van der Waals forces, but this aggregation is easily de-aggregated under external forces such as ultrasonic waves, stirring, and rolling, so that the main composition form of the positive electrode active material in the film layer is still the primary particle.

[0174] The longest diameter of the lithium-containing phosphate refers to the longest straight line that passes through the center point of the lithium-containing phosphate and extends to the outer periphery of the particle.

[0175] In the embodiments of the present application, the average value of the longest diameter can be measured in the following manner.

[0176] Disassemble the battery cell to obtain the positive electrode plate. Cut the positive electrode plate along the thickness direction of the plate to expose the longitudinal section of the positive electrode film layer. Determine the longest diameter of the lithium-containing phosphate by performing a scanning electron microscope (SEM) test on the longitudinal section of the positive electrode film layer. As an example, randomly select 30 lithium-containing phosphate particles in the longitudinal section diagram of the positive electrode film layer, measure the longest diameters of the 30 lithium-containing phosphate particles respectively, and then take their average value.

[0177] In some embodiments, the lithium-containing phosphate matrix includes lithium iron phosphate, and the lithium iron phosphate is doped with at least one of Al, V, and Ti. The above doping elements are beneficial to improving the performance such as the conductivity of the lithium-containing phosphate, and thus are beneficial to the capacity of the battery cell; in addition, the above doping elements are also beneficial to improving the compaction density of the positive electrode plate, and thus are beneficial to improving the energy density of the battery cell.

[0178] In some embodiments, based on the total mass of the lithium-containing phosphate, the mass content of Al is 200 ppm to 2500 ppm, the mass content of V is 300 ppm to 2000 ppm, and the mass content of Ti is 1500 ppm to 3500 ppm. The above doping elements have appropriate mass contents, and the battery cell has high energy density, capacity, and cycle performance.

[0179] Based on the total mass of the lithium-containing phosphate, the mass content of Al can be 200 ppm, 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2500 ppm or any value within the above range. The mass content of V can be 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm or any value within the above range. The mass content of Ti is 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2500 ppm, 2800 ppm, 3000 ppm, 3200 ppm, 3500 ppm or any value within the above range.

[0180] The elements in the positive electrode active material and the content of each element can be measured by cooperating an argon ion cross-section polisher (model JEOL IB-19530CP) and a scanning electron microscope (model Zeiss sigma 300) (configured with an X-ray energy spectrometer (EDS, model Oxford Energy Spectrometer OXFord X-Max-50mm2)).

[0181] As an example, at 25°C, the battery cell is discharged at a constant current of 0.33C to 2.0V to obtain a battery cell with 0% SOC. Then, the positive electrode plate is removed from the battery cell, and the longitudinal section of the positive electrode film layer is obtained by using an ion cross-section polisher, and the cross-section of the positive electrode active material particles is scanned by using a scanning electron microscope to test each element and its content.

[0182] In some embodiments, the lithium-containing phosphate positive electrode active material includes at least one of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. The above lithium-containing phosphate positive electrode active material has high structural stability, which helps to improve the cycle life of the battery cell.

[0183] During the charge and discharge process of the battery cell, the insertion and extraction and consumption of Li will occur. The molar content of Li in the positive electrode active material is different when the battery cell is discharged to different states. In the listing of the positive electrode active material in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system, after charge and discharge cycles, the molar content of Li will change. In the listing of the positive electrode active material in this application, the molar content of O is only the ideal state value, and the release of oxygen from the lattice will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0184] In some embodiments, at least a portion of the surface of the graphite has a coating layer, and the coating layer includes amorphous carbon. In this way, it is beneficial to the rapid insertion of lithium ions into the graphite, which is conducive to improving the fast charging performance of the battery cell.

[0185] In some embodiments, the thickness of the coating layer is 100 nm to 500 nm, and for example, it can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or any value within the above range. In this way, the coating layer has an appropriate thickness, which facilitates the insertion and transmission of lithium ions and is conducive to improving the fast charging performance of the battery cell.

[0186] In some embodiments, the graphite includes secondary particles. In this way, it is convenient for the transmission of lithium ions and is conducive to improving the fast charging performance of the battery cell.

[0187] In some embodiments, the graphitization degree of the graphite is 90% to 94%, and for example, it can be 90%, 91%, 92%, 93%, 94% or any value within the above range. In this way, the graphite has an appropriate graphitization degree, which is not only beneficial for the graphite to have a relatively appropriate specific capacity, but also can control the side reactions in the battery cell within an appropriate range, so that the battery cell has a relatively appropriate capacity and cycle life.

[0188] In some embodiments, the volume average particle size Dv50 of the graphite is 15 μm to 25 μm. In this way, the particle size of the graphite is within an appropriate range, which is conducive to improving the compaction density of the negative electrode sheet, and thus conducive to improving the energy density of the battery cell.

[0189] The volume average particle size Dv50 of the graphite represents the particle size corresponding to when the cumulative volume distribution percentage of the graphite reaches 50%, and it can be measured by instruments and methods known in the art. As an example, the battery cell is disassembled to obtain the negative electrode sheet, the negative electrode film layer of the negative electrode sheet is scraped off to obtain the powder of the negative electrode film layer, and then the powder of the negative electrode film layer is stirred with water, and after filtration and drying, graphite is obtained. Then, referring to GB / T19077-2016 Laser Diffraction Method for Particle Size Distribution, it can be conveniently measured by a laser particle size analyzer. The test instrument can be the Mastersizer 3000 type laser particle size analyzer of Malvern Instruments Limited, UK.

[0190] The volume average particle size Dv50 of the graphite can be 115 μm, 15.2 μm, 15.5 μm, 15.8 μm, 16 μm, 16.2 μm, 16.5 μm, 16.8 μm, 17 μm, 17.2 μm, 17.5 μm, 17.8 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm or any value within the above range.

[0191] In some embodiments, the volume average particle size Dv50 of the graphite is 16 μm to 20 μm. In this way, the particle size of the graphite has a suitable range, which is beneficial to improving the compaction density of the negative electrode sheet, and thus beneficial to improving the energy density of the battery cell.

[0192] In some embodiments, the electrolyte includes additives, and the additives include at least one of vinylene carbonate VC, fluoroethylene carbonate FEC, and 1,3 - propane sultone PS. The above additives are beneficial to film formation at the negative electrode, can reduce side reactions at the negative electrode, and thus are beneficial to improving the performance of the battery cell such as cycle life and kinetics.

[0193] In some embodiments, based on the total mass of the electrolyte, the mass content of the additive is less than or equal to 5%, for example, it can be 5%, 4.8%, 4.5%, 4.2%, 4%, 3.8%, 3.5%, 3%, 2.8%, 2.5%, 2%, 1.8%, 1.5%, 1.2%, 1%, 0.8%, 0.5% or any value within the above range. The above additives have a suitable mass content, which is beneficial to improving the performance of the battery cell such as cycle life and kinetics.

[0194] In some embodiments, based on the total mass of the electrolyte, the mass content of the additive is 0.5% to 3%. The above additives have a suitable mass content, which is beneficial to improving the performance of the battery cell such as cycle life and kinetics.

[0195] [Battery device] The embodiment of the present application provides a battery device, including the battery cell in any of the above embodiments.

[0196] Figure 7 It is a schematic diagram of the battery device according to an embodiment of the present application. For example, as Figure 7 shown, the battery device 10 of the embodiment of the present application may include a plurality of battery cells 3 to meet different power usage requirements. The shape of the battery cell 3 of the embodiment of the present application can be set according to actual applications. For example, the battery cell 3 can be cylindrical, or can also be cuboid or other shapes, and the embodiment of the present application is not limited thereto.

[0197] The battery device 10 according to an embodiment of the present application may further include a box body 11, which can be used to accommodate a plurality of battery cells 3. The interior of the box body 11 according to an embodiment of the present application is a hollow structure, and a plurality of battery cells 3 are accommodated in the box body 11. The box body 11 may include two parts, which are respectively referred to as a first box body part 111 and a second box body part 112, and the first box body part 111 and the second box body part 112 are snapped together. The shapes of the first box body part 111 and the second box body part 112 may be determined according to the shape of the components accommodated inside, for example, according to the shape of the combination of the plurality of battery cells 3 accommodated inside. At least one of the first box body part 111 and the second box body part 112 has an opening. For example, as Figure 7 shown, the first box body part 111 and the second box body part 112 may both be hollow cuboids and each has an opening surface. The opening of the first box body part 111 and the opening of the second box body part 112 are arranged oppositely, and the first box body part 111 and the second box body part 112 are snapped together to form a box body 11 with a closed chamber, and this chamber can be used to accommodate a plurality of battery cells 3. A plurality of battery cells 3 are placed in the box body 11 formed after the first box body part 111 and the second box body part 112 are snapped together after being connected in parallel or in series or in a hybrid connection.

[0198] For another example, different from Figure 7 shown, only one of the first box body part 111 and the second box body part 112 may be a hollow cuboid with an opening, and the other may be a plate-like shape to cover the opening. Taking the second box body part 112 as a hollow cuboid with an opening and the first box body part 111 as a plate-like shape as an example, then the first box body part 111 covers the opening of the second box body part 112 to form a box body 11 with a closed chamber, and this chamber can be used to accommodate a plurality of battery cells 3.

[0199] [Electrical equipment] An embodiment of the present application provides an electrical equipment, including the battery cell in any of the above embodiments, or, the battery device in any of the above embodiments, and the battery cell or the battery device is used to store or provide electrical energy.

[0200] The technical solutions described in the embodiments of the present application are applicable to various electrical equipment using battery devices.

[0201] The electrical device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended electric vehicle, etc.; The spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; The electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, a planer, etc. The embodiments of the present application do not impose special restrictions on the above electrical devices.

[0202] For the convenience of description, the following embodiments will take the electrical device as a vehicle as an example for illustration.

[0203] For example, as Figure 8 shown, it is a schematic diagram of a vehicle according to an embodiment of the present application. The vehicle 1 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended electric vehicle, etc. A motor 40, a controller 30 and a battery device 10 can be arranged inside the vehicle 1. The controller 30 is used to control the battery device 10 to supply power to the motor 40. For example, the battery device 10 can be arranged at the bottom, the front end or the rear end of the vehicle 1. The battery device 10 can be used to supply power to the vehicle 1. For example, the battery device 10 can be used as the operating power source of the vehicle 1 and used for the circuit system of the vehicle 1, for example, for the working power requirements during the start, navigation and operation of the vehicle 1. In another embodiment of the present application, the battery device 10 can not only be used as the operating power source of the vehicle 1, but also be used as the driving power source of the vehicle 1 to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0204] [Positive electrode tab] In some embodiments, the positive current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0205] In some embodiments, the positive electrode film layer further includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0206] In some embodiments, the positive electrode film layer further includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0207] In one embodiment, the positive electrode plate can be prepared by the following method: forming a positive electrode slurry from the above components for preparing the positive electrode plate. For example, the positive electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry. Then, the positive electrode slurry is coated on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained.

[0208] [Negative electrode plate] In some embodiments, the negative electrode current collector can be a metal foil or a composite negative electrode current collector. The negative electrode current collector can be a copper foil. The composite negative electrode current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0209] The negative electrode film layer includes a negative electrode active material. The negative electrode active material can be a negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material includes graphite, and may further include at least one of the following materials: soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0210] The negative electrode film layer may alternatively include a binder. As an example, the binder may include at least one of styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), carboxymethyl chitosan (CMCS).

[0211] The negative electrode film layer may alternatively include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0212] In one embodiment, the negative electrode sheet can be prepared in the following manner: forming a negative electrode slurry from the above components for preparing the negative electrode sheet. For example, dispersing the negative electrode active material, conductive agent, binder, and any other components in a solvent (e.g., deionized water) to form a negative electrode slurry. Then coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode sheet can be obtained.

[0213] [Separator membrane] The separator membrane is used to separate the positive electrode sheet and the negative electrode sheet. The separator membrane includes a base film. The present application does not particularly limit the type of the base film. For example, any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0214] In one embodiment, the material of the base film may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The base film can be a single-layer film or a multi-layer composite film, without particular limitation. When the base film is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0215] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0216] [Embodiment] Embodiment 1 (1) Preparation of the negative electrode sheet The artificial graphite as the negative electrode active material, carbon black as the conductive agent, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC-Na) as the thickener are fully stirred in a deionized water solvent system according to a mass ratio of 96.5:0.5:2:1 to obtain a negative electrode slurry; the negative electrode slurry is uniformly coated on both side surfaces of the negative electrode current collector copper foil, and then dried, cold-pressed, and slit to obtain a negative electrode plate. Among them, the volume average particle size Dv50 of the artificial graphite is 18 μm, and in the state where the battery cell is at 0% SOC, the tap density of the negative electrode plate is 1.4 g / cm 3 , and the areal density of the single side of the negative electrode film layer is 0.17 g / 1540.25 mm 2 .

[0217] (2) Preparation of the positive electrode plate The lithium-containing phosphate as the positive electrode active material, carbon black as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder are fully stirred and mixed evenly in an N-methylpyrrolidone (NMP) solvent system according to a mass ratio of 97:1.0:2.0 to obtain a positive electrode slurry; the above positive electrode slurry is uniformly coated on both side surfaces of the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain a positive electrode plate. In the state where the battery cell is at 0% SOC, the tap density of the positive electrode plate is 2.5 g / cm 3 , and the areal density of the single side of the positive electrode film layer is 0.38 g / 1540.25 mm 2 . The lithium-containing phosphate includes a lithium iron phosphate matrix and a positive electrode coating layer that at least coats part of the surface of the lithium iron phosphate matrix, and the positive electrode coating layer includes carbon elements.

[0218] (3) Preparation of the electrolyte In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), dimethyl carbonate (DMC), methyl acetate (MA), and ethylene carbonate (EC) as organic solvents are mixed evenly. Then lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI are added and dissolved in the organic solvents, and vinylene carbonate (VC) is added and stirred evenly to obtain the electrolyte of Example 1.

[0219] Among them, based on the total mass of the electrolyte, the mass content of dimethyl carbonate is 8.6%, the mass content of methyl acetate is 42.8%, the mass content of ethylene carbonate is 30.8%, and the mass content of vinylene carbonate is 3.4%. The organic solvents include a first solvent, and the first solvent includes dimethyl carbonate and methyl acetate.

[0220] Based on the total mass of the electrolyte, the mass content of the electrolyte salt LiPF6 is 9.6%, and the mass content of LiFSI is 4.8%.

[0221] (4) Separator Preparation of inorganic coating slurry: Mix inorganic particles boehmite, binder styrene-butadiene rubber, dispersant sodium carboxymethyl cellulose (CMC-Na), and wetting agent organosilicon-modified polyether evenly in an appropriate amount of solvent deionized water according to a dry weight ratio of 85:13:1:1 to obtain the inorganic coating slurry.

[0222] Preparation of organic coating slurry: Dissolve polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP), stir evenly, add polyethylene glycol (PEG) as a pore-forming agent, and stir well to mix to obtain the organic coating slurry.

[0223] Use polyethylene (PE) with a thickness of 7 μm as the base film. Coat the above-mentioned inorganic coating slurry on both surfaces of the PE base film with a coater. After drying, apply the organic coating slurry on the base film with inorganic coatings on both sides. After pre-volatilization at 80 °C and drying at 110 °C, immerse it in deionized water to dissolve PEG to obtain the separator membrane. Among them, the thickness of the base film is 7 μm, the thickness of the single-sided inorganic coating is 2 μm, and the thickness of the single-sided organic coating is 1 μm.

[0224] Within the area of 50 μm × 50 μm of the organic coating, the area ratio of the region containing the fluoropolymer is 70%.

[0225] (5) Preparation of battery cells Stack the positive electrode sheet, separator membrane, and negative electrode sheet according to the lamination preparation process, so that the separator membrane is in the middle of the positive and negative electrode sheets to isolate the positive and negative electrode sheets. Place the electrode assembly in an aluminum-plastic film, inject the electrolyte, and after processes such as vacuum packaging, standing, forming, and shaping, obtain the battery cells.

[0226] Examples 2 - 3 The differences between Examples 2 - 3 and Example 1 are as follows: Within the area of 50 μm × 50 μm of the organic coating, the area ratio of the region containing the fluoropolymer is different. Among them, the area ratio of the region containing the fluoropolymer can be adjusted by adjusting the mass ratio of the pore-forming agent to PVDF.

[0227] Examples 4 - 5 The differences between Examples 4 - 5 and Example 1 are as follows: The thickness of the organic coating is different.

[0228] Example 6 The difference between Example 6 and Example 1 is as follows: The separator membrane does not include an inorganic coating.

[0229] Examples 7 - 8 The differences between Examples 7 - 8 and Example 1 are as follows: The compaction density of the positive electrode sheet is different.

[0230] Examples 9 - 10 Examples 9-10 are different from Example 1 in that the compaction density of the negative electrode plate is different.

[0231] Examples 11-14 Examples 11-14 are different from Example 1 in that, based on the total mass of the electrolyte, the mass content of the first solvent is different. Among them, in Examples 11-14, the mass ratio of dimethyl carbonate to methyl acetate is 1:5.

[0232] Examples 15-17 Examples 15-17 are different from Example 1 in that the type of the first solvent or the mass proportion of the specific components in the first solvent is different.

[0233] In Example 15, the first solvent includes dimethyl carbonate. Based on the total mass of the electrolyte, the mass content of dimethyl carbonate is 51.4%, the mass content of ethylene carbonate is 30.8%, and the mass content of vinylene carbonate is 3.4%.

[0234] In Example 16, the organic solvent includes dimethyl carbonate and methyl acetate. Based on the total mass of the electrolyte, the mass content of dimethyl carbonate is 25.7%, the mass content of methyl acetate is 25.7%, the mass content of ethylene carbonate is 30.8%, and the mass content of vinylene carbonate is 3.4%.

[0235] In Example 17, the linear carbonate is different and does not include linear carboxylic esters. Based on the total mass of the electrolyte, the mass content of ethyl methyl carbonate is 42.8%; the mass content of diethyl carbonate is 8.6%, the mass content of ethylene carbonate is 30.8%, and the mass content of vinylene carbonate is 3.4%.

[0236] Comparative Example 1 Comparative Example 1 is different from Example 1 in that in the separator, the organic coating is a dispersed island structure.

[0237] In Comparative Example 1, the organic coating is prepared by the following method: PVDF and the wetting agent organosilicon-modified polyether are respectively added to water to obtain a slurry of the organic coating, and the total mass proportion of the organic substances in the slurry of the organic coating is 15%; then the slurry is prepared on the surface of the inorganic coating by spraying, and the separator provided with the organic coating is obtained after drying at 60°C.

[0238] Comparative Example 2 Comparative Example 2 is different from Example 1 in that the compaction density of the positive electrode plate is less than 2.3 g / cm 3 。 Comparative Example 3 Comparative Example 3 is different from Example 1 in that the compaction density of the positive electrode plate is greater than 2.65 g / cm 3 。 Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the compaction density of the negative electrode sheet is less than 1.30 g / cm 3 . Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the compaction density of the negative electrode sheet is greater than 1.52 g / cm 3 .

[0239] Table 1 Data of Examples and Comparative Examples

[0240] In Table 1, A represents the area ratio of the fluorine element-containing region within an area of 50 μm × 50 μm, EA represents methyl acetate, DMC represents dimethyl carbonate, EMC represents ethyl methyl carbonate, and DEC represents diethyl carbonate.

[0241] Table 2 Data of Some Examples

[0242] In the examples of the present application, the cycle performance of the battery cell is reflected by the number of cycles when the discharge capacity of the battery cell decays to 80%, the energy density is reflected by the weight energy density of the battery cell, and the fast charging performance is reflected by the capacity retention rate at a 4C rate.

[0243] As shown in combination with Examples 1-17 and Comparative Examples 1-5, by setting the compaction density of the positive electrode sheet to be 2.3 g / cm 3 to 2.65 g / cm 3 , the compaction density of the negative electrode sheet to be 1.30 g / cm 3 to 1.52 g / cm 3 , the organic solvent of the electrolyte includes at least one of linear carbonates and linear carboxylates, and the organic coating of the separator has a continuous film structure, the battery cell can take into account relatively high energy density, good fast charging performance and good cycle performance.

[0244] As shown in combination with Examples 1-3, within an area of 50 μm × 50 μm, the area ratio of the region containing the fluorine element is 50% to 90%, the separator has good adhesiveness to the positive electrode sheet and the negative electrode sheet, and the risk of lithium deposition in the battery cell caused by gas accumulation between the separator and the positive electrode sheet and the negative electrode sheet is relatively low, so that the battery cell has good cycle performance.

[0245] As shown in combination with Example 1 and Examples 4-5, when the thickness of the organic coating is 0.5 μm to 2 μm, the separator has good adhesiveness to the positive electrode sheet and the negative electrode sheet, and the risk of lithium deposition in the battery cell caused by gas accumulation between the separator and the positive electrode sheet and the negative electrode sheet is relatively low. Therefore, the battery cell has good cycle performance; in addition, the battery cell also has a high energy density.

[0246] As shown in combination with Example 1 and Example 6, the setting of the inorganic coating is beneficial to improving the wettability of the separator to the electrolyte, and further helps to improve the cycle performance of the battery cell.

[0247] As shown in combination with Example 1 and Examples 7-8, when the compaction density of the positive electrode sheet is 2.3 g / cm 3 to 2.65 g / cm 3 , the battery cell can take into account a high energy density, good fast charging performance and good cycle performance; as shown in combination with Example 1 and Examples 9-10, when the compaction density of the negative electrode sheet is 1.30 g / cm 3 to 1.52 g / cm 3 , the battery cell can take into account a high energy density, good fast charging performance and good cycle performance.

[0248] As shown in combination with Examples 11-14, based on the total mass of the electrolyte, when the mass content of the first solvent is 8.6% to 77%, the battery cell can take into account good fast charging performance and good cycle performance.

[0249] As shown in combination with Example 1 and Examples 15-16, various linear carbonates and linear carboxylates are applicable to the embodiments of the present application.

[0250] As shown in combination with Example 1 and Example 17, using a linear carbonate solvent with low viscosity or using a linear carboxylate solvent is more beneficial to improving the fast charging performance of the battery cell.

[0251] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the technical solution scope of the present application are all included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be thought of by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of the present application.

[0252] The following briefly introduces the test methods for the physical and chemical parameters and performance parameters involved in the embodiments of the present application. It should be understood that the following test methods are only examples, and other well-known test methods in the art can also be used for testing.

[0253] 1. Test of cycling performance At 45 °C, charge the single battery at a constant current of 0.5C to 3.65V, then charge it at a constant voltage to 0.05C, let it stand for 10 min, and then discharge it at a constant current of 1C to 2.0V. This is one charge-discharge cycle. Record the discharge capacity of the first cycle; let it stand for 10 min, repeat the above charge-discharge cycle until the discharge capacity of the single battery decays to 80% of the discharge capacity of the first cycle, then stop the test and record the number of cycles.

[0254] 2. Test of energy density At 25 °C, charge the single battery at a constant current of 0.33C to the cut-off voltage of 3.65V, then charge it at a constant voltage to 0.05C, and then discharge it at a constant current of 0.33C to the cut-off voltage of 2.0V. Record the discharge energy E0 and the discharge capacity C0; weigh the mass of the single battery (generally weigh the single battery with the outer shell) M0; the energy density of the single battery is E0 / M0, with the unit of Wh / kg.

[0255] 3. Test of fast charging performance Pretreatment: At 25 °C, discharge the single battery at a constant current of 0.33C to the cut-off voltage of 2.0V and let it stand for 10 min.

[0256] Fast charging cycle: At 25 °C, charge the single battery at a constant current of 4C to 3.65V, then charge it at a constant voltage to 0.05C, let it stand for 10 min, and then discharge it at a constant current of 1C to 2.0V. This is one charge-discharge cycle. Record the discharge capacity of the first cycle; let it stand for 10 min, repeat the above charge-discharge cycle 200 times, record the discharge capacity of the last time, and calculate the capacity retention rate. Capacity retention rate = discharge capacity of the last time / discharge capacity of the first cycle.

Claims

1. A battery cell, characterized in that, Comprising: A laminated electrode assembly and an electrolyte, the laminated electrode assembly comprising a positive electrode tab, a separator, and a negative electrode tab stacked together; wherein, The positive electrode sheet includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, the lithium-containing phosphate includes a lithium-containing phosphate matrix and a positive electrode coating layer that at least coats a partial surface of the lithium-containing phosphate matrix, the positive electrode coating layer includes carbon element, and the tap density of the positive electrode sheet is 2.3 g / cm 3 to 2.65 g / cm 3 ; The negative electrode plate includes a negative active material, the negative active material includes graphite, and the tap density of the negative electrode plate is 1.30 g / cm 3 to 1.52 g / cm 3 ; The electrolyte comprises an organic solvent, the organic solvent comprises a first solvent, and the first solvent comprises at least one of a linear carbonate and a linear carboxylate; The separator is disposed between the positive electrode tab and the negative electrode tab, and the separator comprises a base film and an organic coating disposed on at least one surface of the base film, and the organic coating is a continuous layer with a porous structure.

2. The battery cell according to claim 1, characterized in that, The organic coating comprises a fluoropolymer.

3. The battery cell according to claim 2, wherein Within an area of 50μm×50μm of the organic coating, the area ratio of the region containing the fluoropolymer is 50% to 90%.

4. The battery cell according to claim 2, characterized in that, The fluoropolymer comprises one or more of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer.

5. The battery cell according to claim 1, characterized in that, The thickness of the organic coating is 0.5μm to 2μm.

6. The battery cell according to claim 1, wherein The separator further comprises an inorganic coating, and along the thickness direction of the separator, the inorganic coating is disposed between the base film and the organic coating.

7. The battery cell according to claim 6, wherein The inorganic coating comprises inorganic particles, and the inorganic particles comprise at least one of alumina, boehmite, and magnesia.

8. The battery cell according to claim 1, characterized in that, The linear carbonate comprises dimethyl carbonate.

9. The battery cell according to claim 1, wherein, The linear carboxylate comprises R1-COO-R2, and R1 and R2 each independently comprise at least one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms.

10. The battery cell according to claim 9, wherein, The linear carboxylate comprises at least one of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate.

11. The battery cell according to claim 1, wherein, Based on the total mass of the electrolyte, the mass content of the first solvent is 8.6% to 77%.

12. The battery cell according to claim 11, wherein, Based on the total mass of the electrolyte, the mass content of the first solvent is 34.4% to 66%.

13. The battery cell according to claim 1, wherein, The ionic conductivity of the electrolyte at room temperature is 9.5 ms / cm to 20 ms / cm.

14. The battery cell according to claim 13, wherein The ionic conductivity of the electrolyte at room temperature is 12 ms / cm to 16 ms / cm.

15. The battery cell according to claim 1, characterized in that, The electrolyte comprises an electrolyte salt, and the electrolyte salt comprises one or more of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

16. The battery cell according to claim 15, wherein, Based on the total mass of the electrolyte, the mass content of the electrolyte salt is 12% to 20%.

17. The battery cell according to claim 15, characterized in that, The electrolyte salt comprises the lithium hexafluorophosphate and the lithium bis(fluorosulfonyl)imide, and the mass ratio of the lithium hexafluorophosphate to the lithium bis(fluorosulfonyl)imide is 1.2 to 3.

18. The battery cell according to claim 1, characterized in that, The ratio of the mass of the electrolyte to the capacity of the battery cell is 2.8 g / Ah to 3.5 g / Ah.

19. The battery cell according to claim 18, wherein The ratio of the mass of the electrolyte to the capacity of the battery cell is 3.0 g / Ah to 3.2 g / Ah.

20. The battery cell according to claim 1, characterized in that, The single-sided density of the positive electrode sheet is 0.33 g / 1540.25 mm 2 to 0.45 g / 1540.25 mm 2 .

21. The battery cell according to claim 1, wherein The single-sided areal density of the negative electrode sheet is 0.15 g / 1540.25 mm 2 to 0.22 g / 1540.25 mm 2 .

22. The battery cell according to claim 1, wherein, The positive electrode tab comprises a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprises the positive electrode active material, and the thickness of the positive electrode current collector is 13μm to 16μm.

23. The battery cell according to claim 1, wherein, The negative electrode tab comprises a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer comprises the negative electrode active material, and the thickness of the negative electrode current collector is 7μm to 10μm.

24. The battery cell according to claim 1, wherein, The thickness of the base film is 5μm to 9μm.

25. The battery cell according to claim 1, characterized in that, The porosity of the separator membrane is 40% to 55%.

26. The battery cell according to claim 1, wherein, The battery cell includes a housing, the material of the housing includes an aluminum-plastic film, and the positive electrode sheet and the negative electrode sheet are accommodated in the space formed by the aluminum-plastic film.

27. The battery cell according to claim 1, characterized in that, The average value of the longest diameter of the primary particles containing lithium phosphate is 300 nm to 800 nm.

28. The battery cell according to claim 1, wherein, The lithium phosphate-containing matrix includes lithium iron phosphate, and the lithium iron phosphate is doped with at least one of Al, V, and Ti.

29. The battery cell according to claim 28, characterized in that, Based on the total mass of the lithium phosphate-containing material, the mass content of Al is 200 ppm to 2500 ppm, the mass content of V is 300 ppm to 2000 ppm, and the mass content of Ti is 1500 ppm to 3500 ppm.

30. The battery cell according to claim 1, characterized in that, At least part of the surface of the graphite has a coating layer, and the coating layer includes amorphous carbon.

31. The battery cell according to claim 30, wherein The thickness of the coating layer is 100 nm to 500 nm.

32. The battery cell according to claim 30, wherein The graphite includes secondary particles.

33. The battery cell according to claim 30, wherein, The graphitization degree of the graphite is 90% to 94%.

34. The battery cell according to claim 1, wherein, The volume average particle size Dv50 of the graphite is 15 μm to 25 μm.

35. The battery cell according to claim 34, wherein The volume average particle size Dv50 of the graphite is 16 μm to 20 μm.

36. The battery cell according to claim 1, characterized in that, The electrolyte includes additives, and the additives include at least one of vinylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone.

37. The battery cell according to claim 36, characterized in that, Based on the total mass of the electrolyte, the mass content of the additive is less than or equal to 5%.

38. The battery cell according to claim 37, wherein Based on the total mass of the electrolyte, the mass content of the additive is 0.5% to 3%.

39. A battery device, characterized in that, Comprising: A plurality of battery cells according to any one of claims 1-38.

40. An electrical device, characterized in that, Comprising: A plurality of battery cells according to any one of claims 1-38, or a battery device according to claim 39, wherein the battery cell or the battery device is used for storing or providing electrical energy.

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