Battery cell, battery device and power-consuming device

Abstract

Battery cell comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil and an anode foil; wherein the cathode foil comprises a cathode collector and a cathode film layer arranged on at least one side of the cathode collector, wherein the cathode film layer comprises a lithium-containing phosphate; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one side of the anode collector, wherein the anode film layer comprises a carbon-based material and a silicon-based material; wherein the electrolyte solution comprises vinyl carbonate and a cyclic carbonate additive, wherein the cyclic carbonate additive comprises one or more of vinylidene carbonate and a vinyl carbonate derivative, where the mass content of the silicon element of the silicon-based material in the anode film layer is 0.5% to 5%; the mass content of vinyl carbonate in the electrolyte solution is 20% to 40%; The mass content of the cyclic carbonate additive in the electrolyte solution is 2% to 8%.

Description

TECHNICAL AREA

[0001] The present application relates to a battery cell, a battery device and a power-consuming device. STATE OF THE ART

[0002] Battery cells are characterized by high capacity and a long lifespan and are therefore frequently used in electronic devices. Examples include mobile phones, laptops, battery-powered cars, electric vehicles, electric aircraft, electric boats, and power tools. With the development of applications for lithium-ion batteries, the performance requirements of the battery cell, such as its cycle life at high energy density, have increased. CONTENT OF THE PRESENT INVENTION

[0003] The present application provides a battery cell, a battery device and a power-consuming device, which can improve the cycle performance of the battery cell at a high energy density.

[0004] A first aspect of the present application provides a battery cell, the battery cell comprising an electrode assembly and an electrolyte solution, the electrode assembly comprising a cathode foil and an anode foil; the cathode foil comprising a cathode collector and a cathode film layer arranged on at least one side of the cathode collector, the cathode film layer of the cathode foil comprising a lithium-containing phosphate; the anode foil comprising an anode collector and an anode film layer arranged on at least one side of the anode collector, the anode film layer of the anode foil comprising a carbon-based material and a silicon-based material;wherein the electrolyte solution comprises vinyl carbonate and a cyclic carbonate additive, wherein the cyclic carbonate additive comprises one or more of vinylidene carbonate and a vinyl carbonate derivative, wherein the mass fraction of the silicon element of the silicon-based material in the anode film layer is 0.5% to 5%; wherein the mass fraction of the vinyl carbonate in the electrolyte solution is 20% to 40%; wherein the mass fraction of the cyclic carbonate additive in the electrolyte solution is 2% to 8%.

[0005] In the embodiment of the present application, the energy density of the battery cell can be improved by regulating the mass fraction of the silicon element; and the cycle performance of the battery cell can be improved by regulating the components of the electrolyte solution. In particular, the electrolyte solution comprises vinyl carbonate and a cyclic carbonate additive. A portion of the vinyl carbonate can act synergistically with the cyclic carbonate additive to participate in the formation of an SEI film at the interface of a solid electrolyte on the anode side, to optimize the mechanical and protective properties of the SEI film, and to effectively mitigate volume expansion on the anode side and side reactions on the anode side, thereby improving the cycle performance of the battery cell.Another part of the vinyl carbonate can be used as a solvent, which can improve the stability of the electrolyte solution; furthermore, vinyl carbonate has a high dielectric constant and a strong ability to dissociate ions, which is conducive to the transfer of lithium ions, and under a certain current density, lithium ions can be rapidly embedded in the anode film layer to bond with electrons, reducing the risk of lithium precipitation on the surface of the anode film layer and improving the cycle performance of the battery cell.Further regulation of the mass content of vinyl carbonate and the cyclic carbonate additive is beneficial for uniformly infiltrating the anode foil, thereby reducing the risk of lithium precipitation on the surface of the anode film layer, and ensuring that the film-forming impedance of the SEI film is not too high, which is beneficial for fast charging of the battery cell and further reduces the risk of lithium precipitation on the surface of the anode film layer, thus improving the cycle performance of the battery cell.

[0006] In some embodiments, the mass fraction of vinyl carbonate in the electrolyte solution is 20% to 35%. The mass fraction of vinyl carbonate is within the above range, which contributes to a further improvement in the cycle performance of the battery cell.

[0007] In some embodiments, the mass fraction of vinylidene carbonate in the electrolyte solution is 1.5% to 5%. When the mass fraction of vinylidene carbonate is in the above range, a dense SEI film containing organic components can form on the anode side, and the impedance of the SEI film is relatively low, which reduces side reactions on the anode side and improves the cycle performance of the battery cell at high energy density.

[0008] In some embodiments, the mass fraction of the vinyl carbonate derivative in the electrolyte solution is 0 to 4%, optionally 1.5% to 3.5%. The vinyl carbonate derivative and the vinyl carbonate interact, and the vinyl carbonate derivative can further optimize the components of the SEI film, reduce the impedance of the SEI film, and effectively improve the cycle performance of the battery cell at high energy density.

[0009] In some embodiments, the vinyl carbonate derivative comprises a compound represented in formula A, wherein in formula A Q1, Q2, Q3 and Q4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group and at least one of Q1, Q2, Q3 and Q4 comprises a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group.

[0010] The vinyl carbonate derivative can improve the cycle performance of the battery cell more effectively at high energy density.

[0011] In some embodiments, at least one of Q1, Q2, Q3, and Q4 comprises a halogen atom or a C1 to C5 haloalkyl group. The vinyl carbonate derivative can form a film layer with a high F and Li content on the anode side, which can protect the active anode material due to the lower impedance of the film layer and improve the cycle performance of the battery cell at high energy density.

[0012] In some embodiments, the vinyl carbonate derivative comprises one or more of the compounds shown in Formula A-1 to Formula A-3,

[0013] The above materials can further improve the cycle performance of the battery cell effectively at high energy density.

[0014] In some embodiments, the electrolyte solution further comprises a linear ester solvent, wherein the linear ester solvent comprises one or more linear carboxylic acid ester solvents and linear carbonate solvents, the mass fraction of the linear ester solvent in the electrolyte solution being 45% to 65%. The linear ester solvent with the above mass fraction is advantageous for improving the cycle performance and fast-charging performance of the battery cell.

[0015] In some embodiments, the linear carboxylic acid ester solvent comprises a compound represented in formula I, where in Formula I, R1 comprises a hydrogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, R2 comprises a C1 to C5 alkyl group or a C1 to C5 haloalkyl group.

[0016] The lower viscosity of the above linear carboxylic acid ester solvent improves the fast-charging capability of the battery cell at high energy density and reduces the risk of lithium precipitation during fast charging, thereby improving the cycle performance of the battery cell.

[0017] In some embodiments, the linear carboxylic acid ester solvent comprises one or more of the compounds shown in Formula I-1 to Formula I-12,

[0018] The above materials can further improve the cycle performance of the battery cell effectively at high energy density.

[0019] In some embodiments, the linear carbonate solvent comprises one or more of dimethyl carbonate, diethyl carbonate, and methylethyl carbonate. The above materials can further and effectively improve the cycle performance of the battery cell at high energy density.

[0020] In some embodiments, the linear ester solvent comprises a linear carbonate solvent, and the mass fraction of the cyclic carbonate additive is 2% to 5%. The above electrolyte solution system contributes to a further improvement in the cycle performance of the battery cell.

[0021] In some embodiments, the linear ester solvent comprises a linear carboxylic acid ester solvent with a mass fraction >0 and a linear carbonate solvent with a mass fraction ≥0, and the mass fraction of the cyclic carbonate additive is 3.5% to 8%. The above electrolyte solution system contributes to further improving the cycle performance of the battery cell.

[0022] In some embodiments, the electrolyte solution comprises an electrolyte lithium salt, wherein the mass fraction of the electrolyte lithium salt in the electrolyte solution is 10% to 18%. The electrolyte lithium salt with the above mass fraction can improve the cycle performance of the battery cell.

[0023] In some embodiments, the electrolyte lithium salt comprises one or more lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6). The electrolyte lithium salt described above can improve the cycle performance of the battery cell.

[0024] In some embodiments, the mass fraction of lithium bis(fluorosulfonyl)imide (LiFSI) in the electrolyte solution is 4% to 6%. If the mass fraction of lithium bis(fluorosulfonyl)imide is in the above range, the mass fraction of lithium hexafluorophosphate can be reduced, thus decreasing the amount of acid generated in the electrolyte solution, reducing the side reaction, and improving the cycle performance of the battery cell.

[0025] In some embodiments, the electrolyte solution further comprises a sulfur-containing additive with a mass content of 0 to 2%, optionally 0.5% to 2%, in the electrolyte solution, wherein the sulfur-containing additive comprises one or more of vinyl sulfate, vinyl bisulfate, 1,3-propanesulfonyllactone, butylenyl sulfite, vinyl sulfite, and methylenedisulfonylmethane. When synergistically incorporated into the film formation process, the sulfur-containing additive and the cyclic carbonate additive can optimize the composition of the SEI film. This improves the cycle performance of the battery cell at high temperatures and high energy densities.

[0026] In some embodiments, the electrolyte solution further comprises a lithium salt-like additive with a mass content of 0 to 1%, optionally 0.2% to 1%, in the electrolyte solution, wherein the lithium salt-like additive comprises one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium bisoxalate borate. When synergistically incorporated into the film formation process, the lithium salt-like additive and the cyclic carbonate additive can optimize the composition of the SEI film. This improves the cycle performance of the battery cell at high energy density.

[0027] In some embodiments, the mass fraction of the silicon element in the silicon-based material in the anode film layer is 0.8% to 3%. A silicon element mass fraction in the above range can improve the energy density and cycle life of the battery cell.

[0028] In some embodiments, the silicon-based material comprises one or more monomeric silicon, silicon-carbon material, silicon-oxygen material, or silicon-nitrogen material. Optionally, the silicon-based material comprises one or more silicon-carbon materials, silicon-oxygen materials, or silicon-nitrogen materials. Optionally, the silicon-based material includes the silicon-carbon material. The above materials have a high gram capacity, which is conducive to increasing the energy density of the battery cell.

[0029] In some embodiments, the mass content of the silicon element is 40% to 80% based on the mass of the silicon-based material; the silicon-based material meets the above conditions, which further improves the energy density and cycle performance of the battery cell.

[0030] In some embodiments, the silicon-based material has a volume-average particle size Dv50 of 5.0 µm to 12.5 µm, and the silicon-based material meets the above conditions, further improving the energy density and cycle performance of the battery cell.

[0031] In some embodiments, the silicon-based material has a specific surface area of ​​3.1 m². 2 / g up to 3.6 m 2 / g, the silicon-based material meets the above conditions, further improving the energy density and cycle performance of the battery cell.

[0032] In some embodiments, the silicon-based material has a powder compaction density of 0.7 g / cm³ at 25,000 N. 3 up to 1.2 g / cm³ 3 The silicon-based material meets the above conditions, further improving the energy density and cycle performance of the battery cell.

[0033] In some embodiments, the carbon-based material comprises graphite particles, wherein the graphite particles include graphite body particles and an anode coating layer applied to the surface of the graphite body particles, the graphite body particles including secondary particles, and the anode coating layer comprising carbon elements. The conductivity of the anode coating layer is excellent, which reduces the internal resistance of the anode foil, decreases heat generation in the battery cell, and improves the cycle performance of the battery cell at high energy density.

[0034] In some embodiments, the graphite body particles comprise one or more of artificial graphite and natural graphite.

[0035] In some embodiments, the mass fraction of the carbon element in the anode coating layer is 2% to 5%, based on the mass of the graphite particles. If the mass fraction of the carbon element in the anode coating layer is within the above range, the internal resistance of the anode foil can be further reduced, the heat generation of the battery cells can be decreased, and the cycle performance of the battery cells can be improved at high energy density.

[0036] In some embodiments, the anode film layer comprises a first anode film layer and a second anode film layer, wherein the first anode film layer is arranged on the surface of the anode collector, wherein the second anode film layer is arranged on a side of the first anode film layer facing away from the anode collector, wherein the volume mean particle size Dv50 of the carbon-based material of the first anode film layer is greater than or equal to the volume mean particle size Dv50 of the carbon-based material of the second anode film layer, wherein at least one layer of the first anode film layer and the second anode film layer comprises a silicon-based material.The relatively small particle size of the carbon-based material particles in the second anode film layer in the embodiment of the present application can shorten the solid-phase transfer path of the lithium ions, improve fast charging performance, improve the problem of lithium precipitation in the surface layer of the anode film, and improve cycle performance.

[0037] In some embodiments, the volume-mean particle size Dv50 of the carbon-based material in the second anode film layer is 8.5 µm to 14.5 µm. When the volume-mean particle size Dv50 of the carbon-based material in the second anode film layer is within the above range, it can, on the one hand, shorten the solid-phase transfer path of the lithium ions, improve fast-charging performance, enable the lithium ions to quickly gain electrons at the anode side, reduce the risk of lithium precipitation, and improve cycle performance.

[0038] In some embodiments, the volume-mean particle size Dv50 of the carbon-based material in the first anode film layer ranges from 9.8 µm to 16.8 µm. If the volume-mean particle size Dv50 of the carbon-based material in the first anode film layer is within the above range, it can, on the one hand, shorten the solid-state transfer path of the lithium ions, improving fast-charging performance; on the other hand, the material is less prone to agglomeration during the manufacturing process, which can increase the material's stability and improve cycle performance.

[0039] In some embodiments, the silicon-based material is located in the first anode film layer. The second anode film layer can effectively mitigate the volume expansion of the silicon-based material in the first anode film layer and improve the cycle performance of the battery cell.

[0040] In some embodiments, the density of the anode film layer at a 100% charge level of the battery cell is 1.10 g / cm³. 3 up to 1.50 g / cm³ 3 The pressure density of the anode film layer is in the above range, which is beneficial for improving the energy density and cycle performance of the battery cell.

[0041] In some embodiments, the one-sided coating weight of the anode film layer is 90 mg / 1540.25 mm². 2 up to 140 mg / 1540.25 mm 2 The one-sided coating weight of the anode film layer is in the above range, which is beneficial for improving the energy density and cycle performance of the battery cell.

[0042] In some embodiments, the thickness of the anode collector is 4 µm to 6 µm. When the thickness of the anode collector is in the above range, the anode collector becomes thinner, which contributes to an improvement in the volumetric energy density of the battery cell.

[0043] In some embodiments, the anode foil further comprises a conductive anode layer, wherein the conductive anode layer is located between the anode collector and the anode film layer, and wherein the conductive anode layer comprises a conductive anode medium, the conductive anode medium comprising one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive anode layer can further improve the conductivity of the anode foil, reduce the heat generation of the anode foil, and thus reduce the heat generation of the battery cell, which improves the fast-charging performance and the cycle performance of the battery cells at high temperatures.

[0044] In some embodiments, the thickness of the conductive anode layer is 0.5 µm to 2 µm. If the thickness of the conductive anode layer is in the above range, the conductivity of the anode foil can be further improved, the heat generation of the anode foil can be reduced, and thus the heat generation of the battery cell can be reduced, while the energy density of the battery cell can be improved at the same time.

[0045] In some embodiments, the lithium-containing phosphate comprises phosphate particles and a cathode coating layer, wherein the cathode coating layer is arranged on at least a portion of the surface of the phosphate particles and the cathode coating layer comprises carbon elements. Phosphate particles can increase the conductivity of the lithium-containing phosphate by surface coating the cathode coating layer, which promotes the migration rate of the lithium ions, improves the fast-charging capability of the battery, reduces heat generation in the battery cell, and improves the cycle performance of the battery cell.

[0046] In some embodiments, the mass fraction of the carbon element is 0.8% to 2.3%, based on the mass of the lithium phosphate. When the mass fraction of the carbon element is within the above range, the electrical conductivity of the lithium phosphate can be significantly improved, which contributes to the improvement of the ionic and electronic conductivity of the lithium phosphate and can enhance the fast-charging capability of the battery cell at high energy density.

[0047] In some embodiments, the cathode coating layer further comprises one or more of the elements Fe, Ti, Zr, Hf, Ge, Sn. The above cathode coating layer can improve the ionic conductivity of the active cathode material, improve the fast-charging capability of the battery cell, and, in addition to improving the gram capacity, increase the energy density of the corresponding battery cell.

[0048] In some embodiments, the phosphate particles comprise one or more of lithium iron phosphate, lithium manganese phosphate, lithium ferromanganese phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The above materials exhibit excellent cycle stability, which contributes to improved cycle performance of the battery cell.

[0049] In some embodiments, the lithium-containing phosphate comprises a material with the general formula of Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises one or more of the elements Na, K and Mg; where Me comprises one or more of the elements Mn, Fe, Co and Ni; where M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge, and Ce; where X comprises one or more of the elements Cl, C, and N, and where Y comprises one or more of the elements O and F. The above materials exhibit excellent cycle stability, which contributes to improved cycle performance of the battery cell.

[0050] In some embodiments, the active cathode material has a powder density of 2.46 g / cm³ at 30000 N. 3 up to 2.85 g / cm³ 3The powder density of the active cathode material at 30000N is in the range above, which can improve the energy density and cycle performance of the battery cell.

[0051] In some embodiments, the density of the cathode film layer is 2.5 g / cm³. 3 up to 2.8 g / cm³ 3 at a 100% state of charge (SOC) of the battery cell. The density of the cathode film layer is within the range mentioned above, which can improve the energy density and cycle performance of the battery cell.

[0052] In some embodiments, the one-sided coating weight of the cathode film layer is 200 mg / 1540.25 mm². 2 up to 350 mg / 1540.25 mm 2 If the one-sided coating weight of the cathode film layer is within the above range, the heat generation per unit area of ​​the cathode film is not too high, and the cycle performance of the battery cell at high energy density is improved.

[0053] In some embodiments, the thickness of the cathode collector is 10 µm to 15 µm. When the thickness of the cathode collector is in the above range, the thickness of the cathode collector is reduced, which contributes to an improvement in the volumetric energy density of the battery cell.

[0054] In some embodiments, the cathode foil further comprises a conductive cathode layer, wherein the conductive cathode layer is located between the cathode collector and the cathode film layer, and wherein the conductive cathode layer comprises a conductive cathode material, the conductive cathode material comprising one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive cathode layer can further improve the conductivity of the cathode foil, reduce the heat generation of the anode foil, and thus reduce the heat generation of the battery cell.

[0055] In some embodiments, the thickness of the conductive cathode layer is 0.5 µm to 2 µm. When the thickness of the conductive cathode layer is in the above range, the conductivity of the cathode foil can be further improved, the heat generation of the cathode foil can be reduced, and thus the heat generation of the battery cell can be reduced, which improves fast charging performance and cycle performance at high battery cell temperatures and high energy density.

[0056] In some embodiments, the electrode assembly further comprises a separator, wherein the separator is located between the cathode foil and the anode foil, the thickness of the separator being 5 µm to 12 µm. When the thickness of the separator is in the above range, the migration path of the lithium ions in the separator is shorter, and the internal resistance of the battery cell can be further reduced, thereby decreasing heat generation. This improves the fast-charging performance and the cycle performance at high temperatures of high-energy-density battery cells.

[0057] In some embodiments, the separator porosity ranges from 20% to 70%. When the separator porosity is within this range, the migration capability of lithium ions within the separator can be improved, and the internal resistance of the battery cell can be further reduced, thereby decreasing heat generation. This improves fast-charging performance and cycle performance at high temperatures and high energy density battery cells.

[0058] In some embodiments, the separator further comprises a base film and a functional layer arranged in the base film, wherein the functional layer comprises a first functional layer and a second functional layer, the first functional layer being located on one side of the base film and comprising first inorganic particles; the second functional layer being located on the other side of the base film and comprising composite particles, the composite particles comprising second inorganic particles and several non-fluorinated polymer particles, the second inorganic particles adhering to the surface of the non-fluorinated polymer particles and / or being dispersed within the non-fluorinated polymer particles. The first and second functional layers exhibit improved heat resistance, thereby enhancing the heat resistance of the separator.

[0059] In some embodiments, the non-fluorinated polymer particles comprise an acrylate copolymer. The acrylate copolymer exhibits excellent bonding properties and high bond stability to the base film.

[0060] In some embodiments, the first inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. The first inorganic particles contribute to the heat resistance and bulk modulus of the separator.

[0061] In some embodiments, the average particle size of the first inorganic particles is 5 nm to 100 nm. If the average particle size of the first inorganic particles is within the above range, it is advantageous to improve the heat resistance and bulk modulus of the separator.

[0062] In some embodiments, the second inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These second inorganic particles can enhance the heat resistance of the second functional layer and interact with the non-fluorinated polymer to form composite particles, further improving the cycle stability and kinetic performance of the separator and enhancing the cycle performance and fast-charging performance of the battery cell.

[0063] In some embodiments, the average particle size of the second inorganic particles is 5 nm to 100 nm. If the average particle size of the second inorganic particles is within the above range, it is advantageous to improve the heat resistance and bulk modulus of the composite particles.

[0064] In some embodiments, the cathode foil and the anode foil are arranged in a cascade configuration along a thickness direction of the battery cell; wherein the electrode assembly further comprises a cathode tab and an anode tab, wherein the cathode tab is connected to at least one side of the cathode collector along a longitudinal direction of the battery cell, and wherein the anode tab is connected to at least one side of the anode collector along the longitudinal direction of the battery cell; wherein along the longitudinal direction of the battery cell the dimension of the anode film layer is larger than the dimension of the cathode film layer, and wherein the difference between the dimension of the anode film layer and the dimension of the cathode film layer is OH1;where, along the width direction of the battery cell, the dimension of the anode film layer is larger than the dimension of the cathode film layer, and where the difference between the dimension of the anode film layer and the dimension of the cathode film layer is OH2; where OH1 is larger than OH2. If the battery cell meets the above conditions, it can reduce the risk of lithium precipitation and improve the reliability of the battery cell.

[0065] In some embodiments, OH1 is 1 mm to 4 mm; and / or OH2 is 1 mm to 3 mm. If the battery cell meets the above conditions, it can reduce the risk of lithium precipitation and improve the reliability of the battery cell.

[0066] In some embodiments, the cathode tab and the anode tab are arranged at the same end along the longitudinal direction of the electrode assembly, which contributes to improving the energy density of the battery cell.

[0067] In some embodiments, the cathode tab and the anode tab are each arranged at the two ends along the longitudinal direction of the electrode assembly, thereby shortening the electron transfer path and improving the fast-charging capability of the battery cell.

[0068] In some embodiments, the battery cell comprises a housing body, the housing body containing the electrode assembly and the electrolyte solution, the housing body having a rectangular structure, the housing body comprising two opposing first side walls and two opposing second side walls, the two first side walls being connected to each other by the second side walls, the first side walls having a cross-sectional area perpendicular to their own thickness direction that is larger than the cross-sectional area of ​​the second side walls perpendicular to their own thickness direction, the thickness of the first side walls being 0.1 mm to 0.5 mm, optionally 0.2 mm to 0.35 mm. The higher mechanical strength of the first side wall improves the reliability and cycle performance of the battery cells.

[0069] In some embodiments, the volumetric energy density of the battery cell is 450 Wh / L to 530 Wh / L, resulting in a higher energy density for the battery cell.

[0070] A second aspect of the present application further provides a battery device comprising a plurality of battery cells according to one of the embodiments of the first aspect of the present embodiments.

[0071] A third aspect of the present application provides a power-consuming device, the power-consuming device comprising a battery device according to one of the embodiments of the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWING

[0072] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings, which are to be used in the embodiments of the present application, are briefly described below. Of course, the accompanying drawings described below are only some of the embodiments of the present application, and other accompanying drawings can be derived from the accompanying drawings by a person with normal technical knowledge without any creative effort. Fig. Figure 1 shows a schematic representation of the structure of a battery cell in some embodiments of the present application, Fig. Figure 2 shows a schematic exploded view of the battery cell according to some embodiments of the present application, Fig.Figure 3 shows a schematic representation of the structure of an electrode assembly of the battery cell in some embodiments of the present application, Fig. Figure 4 shows a schematic representation of the structure of a cathode foil of the battery cell in some embodiments of the present application, Fig. Figure 5 shows a schematic representation of the structure of the cathode foil of the battery cell in some other embodiments of the present application, Fig. Figure 6 shows a schematic representation of the structure of an anode foil of the battery cell in some embodiments of the present application, Fig. Figure 7 shows a schematic representation of the structure of the anode foil of the battery cell in some other embodiments of the present application, Fig.Figure 8 shows a top view of the structure of an electrode assembly of the battery cell in some embodiments of the present application, Fig. Figure 9 shows a schematic representation of a battery module in some embodiments of the present application, Fig. Figure 10 shows a schematic representation of the structure of a battery pack in some embodiments of the present application, Fig. 11 the present a schematic representation of the structure of a power-consuming device in some embodiments of the present application.

[0073] The attached drawings may not be to scale. Reference symbol list:

[0074] X. Thickness direction; Y. Width direction; Z. Length direction; 1. Power-consuming device; 2. Battery pack; 3. Control unit; 4. Motor; 5. Box; 5a. First box section; 5b. Second box section; 5c. Receiving chamber; 6. Battery module; 7. Battery cell; 10. Electrode assembly; 11. Cathode foil; 111. Cathode tab; 112. Cathode collector; 12. Anode foil; 121. Anode tab; 122. Anode collector; 13. Searator; 14. Main body section; 20. Outer casing; 21. Housing body; 211. First side wall; 212. Second side wall; 22. End cap; 31. Cathode terminal; 32. Anode terminal. DETAILED DESCRIPTION

[0075] The following sections disclose in detail embodiments of the battery cell, the battery device, and the power-consuming device of the present application with corresponding reference to the accompanying drawings. However, there will be instances where an unnecessarily detailed description is omitted. For example, detailed descriptions of things that are already well known and repeated descriptions of the same structure will be left out. This is to prevent the following description from becoming unnecessarily long and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description serve to ensure the complete understanding of the present application by those skilled in the art and are not intended to limit the subject matter specified in the claims.

[0076] The "range" disclosed here is defined in terms of a lower bound and an upper bound, with a particular range being defined by selecting a lower bound and an upper bound that establish the limits of that range. Ranges defined in this way can include or exclude end values ​​and can be combined in any way; that is, any lower bound can be combined with any upper bound to form a range. For example, if a range of 60 to 120 and 80 to 110 is specified for a particular parameter, then a range of 60 to 110 and 80 to 120 is also to be expected. Furthermore, if the minimum values ​​1 and 2 and the maximum values ​​3, 4, and 5 are specified, then the following ranges can be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.Unless otherwise specified, the range "a to b" denotes any combination of real numbers between a and b, where both a and b are real numbers. For example, the range "0 to 5" means that all real numbers between 0 and 5 are listed here, and "0 to 5" is simply a shorthand representation of the combination of these values. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to stating that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on.

[0077] Unless expressly stated otherwise, all embodiments and optional embodiments of the present application may be combined to form new technical solutions.

[0078] Unless expressly stated otherwise, all technical features of the present application, as well as optional technical features, may be combined to form a new technical solution.

[0079] Unless expressly stated otherwise, all steps of the present application may be carried out sequentially or randomly, preferably sequentially. For example, the phrase "procedure comprising steps (a) and (b)" means that the procedure may include steps (a) and (b) carried out one after the other, or that it may include steps (b) and (a) carried out one after the other. The indication that the procedure may also include step (c) means, for example, that step (c) may be added to the procedure in any order; e.g., the procedure may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b).

[0080] The battery cell comprises an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil and an anode foil; wherein the cathode foil comprises a cathode collector and a cathode film layer arranged on at least one side of the cathode collector, the cathode film layer comprising an active cathode material; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one side of the anode collector, the anode film layer comprising an active anode material.

[0081] The active cathode material contains the lithium-containing phosphate, and the gram capacity of the active cathode material is low, resulting in a low volumetric energy density of the battery cell.

[0082] To improve the volumetric energy density of the battery cell, a silicon-based material is introduced into the active anode material. The gram capacity of this silicon-based material is higher, thus improving the overall gram capacity of the active anode material. The main bottleneck in improving the volumetric energy density of the battery cell is the cathode film layer. This can be improved by reducing the space occupied by the anode film layer and increasing the space occupied by the cathode film layer, resulting in a relatively high volumetric energy density for the battery cell.

[0083] However, due to the large volume change of the silicon-based material during the charging and discharging process of the battery cell, the SEI film of the solid electrolyte interface on the anode side is repeatedly interrupted, leading to an intensification of the side reaction on the anode side, deteriorating the cycle performance of the battery cell and impairing the cycle performance of the battery cell at a high volumetric energy density.

[0084] In the embodiment of the present application, the battery cell system is designed to improve the cycle performance of the battery cell in a balanced manner at high energy density; in particular:

[0085] Firstly, the silicon element of the silicon-based material is regulated so that it is within an appropriate range, and the mass content of the silicon element is not too high, which can mitigate the degree of volume change to some extent;

[0086] Secondly, the electrolyte solution comprises a vinyl carbonate and a cyclic carbonate additive, and the cyclic carbonate additive comprises one or more vinylidene carbonate and a vinyl carbonate derivative. A portion of the vinyl carbonate can act synergistically with the cyclic carbonate additive to participate in the formation of an SEI film at the interface of a solid electrolyte on the anode side, optimizing the mechanical and protective properties of the SEI film, effectively mitigating volume expansion on the anode side, ensuring that the impedance is not too high, and effectively mitigating side reactions on the anode side, thus improving the cycle performance of the battery cell.

[0087] Another part of the vinyl carbonate can be used as a solvent; due to its relatively high boiling point, it is not easily decomposed at the operating temperature of the battery cell, which can improve the stability of the electrolyte solution; furthermore, vinyl carbonate has a high dielectric constant and a strong ability to dissociate ions, which is conducive to the transfer of lithium ions, and under a certain current density, lithium ions can be rapidly embedded in the anode film layer to bond with electrons, reducing the risk of lithium precipitation on the surface of the anode film layer and improving the cycle performance of the battery cell;

[0088] Further regulation of the mass fraction of vinyl carbonate and the mass fraction of the cyclic carbonate additive ensures that the mass fraction of vinyl carbonate is not too high and the viscosity of the electrolyte solution is not too high, resulting in uniform infiltration of the anode foil, a reduction in the risk of lithium precipitation on the surface of the anode film layer, and an improvement in the cycle performance of the battery cell. The mass fraction of the cyclic carbonate additive is not too high, so the film-forming impedance of the SEI film is not too high, which facilitates fast charging of the battery cell and further reduces the risk of lithium precipitation on the surface of the anode film layer, thus improving the cycle performance of the battery cell.

[0089] Thus, the embodiments of the present application are able to improve the cycle performance of the battery cell at high energy density. Battery cell

[0090] According to the first aspect, the embodiment of the present application provides a battery cell.

[0091] The battery cell comprises an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil and an anode foil; wherein the cathode foil comprises a cathode collector and a cathode film layer arranged on at least one side of the cathode collector, the cathode film layer comprising an active cathode material, the active cathode material comprising a lithium-containing phosphate; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one side of the anode collector, the anode film layer comprising an active anode material, the active anode material comprising a carbon-based material and a silicon-based material;

[0092] The electrolyte solution comprises vinyl carbonate and a cyclic carbonate additive, wherein the cyclic carbonate additive comprises one or more of vinylidene carbonate and a vinyl carbonate derivative. where the mass content of the silicon element of the silicon-based material in the anode film layer is 0.5% to 5%; the mass content of vinyl carbonate in the electrolyte solution is 20% to 40%; The mass content of the cyclic carbonate additive in the electrolyte solution is 2% to 8%.

[0093] The active cathode material comprises a lithium-containing phosphate, and the active anode material comprises a silicon-based material, and the mass content of the silicon element is greater than or equal to 0.5%, which allows the battery cell to have a relatively high volumetric energy density;

[0094] The volumetric energy density of the battery cells increases further with the increasing mass content of silicon element. However, due to the large volume change of the silicon-based material during the charging and discharging process of the battery cell, the SEI film at the interface of the solid electrolyte on the anode side is repeatedly interrupted, leading to an intensification of the side reaction on the anode side, degrading the cycle performance of the battery cell, and impairing the cycle performance of the battery cell at high volumetric energy densities.

[0095] In this embodiment of the present application, the mass content of the silicon element is regulated to be less than or equal to 5%, and the mass content of the silicon element is not too high, which can mitigate the degree of volume change to a certain extent;

[0096] The embodiment of the present application, on the other hand, improves the cycle performance of the battery cell by regulating the components of the electrolyte solution; in particular, the electrolyte solution comprises a vinyl carbonate with a mass fraction greater than or equal to 20% and a cyclic carbonate additive with a mass fraction greater than or equal to 2%, and the cyclic carbonate additive comprises one or more vinylidene carbonate and a vinyl carbonate derivative. A portion of the vinyl carbonate can act synergistically with the cyclic carbonate additive to participate in the formation of an SEI film at the interface of a solid electrolyte on the anode side, to optimize the mechanical and protective properties of the SEI film, and to effectively mitigate volume expansion on the anode side, and can effectively mitigate side reactions on the anode side and improve the cycle performance of the battery cell.

[0097] Another part of the vinyl carbonate can be used as a solvent; due to its relatively high boiling point, it is not easily decomposed at the operating temperature of the battery cell, which can improve the stability of the electrolyte solution; furthermore, vinyl carbonate has a high dielectric constant and a strong ability to dissociate ions, which is conducive to the transfer of lithium ions, and under a certain current density, lithium ions can be rapidly embedded in the anode film layer to bond with electrons, reducing the risk of lithium precipitation on the surface of the anode film layer and improving the cycle performance of the battery cell;

[0098] By further regulating the mass fraction of vinyl carbonate and the mass fraction of the cyclic carbonate additive, the mass fraction of vinyl carbonate will not be too high and the viscosity of the electrolyte solution will not be too high, e.g., less than or equal to 40%, resulting in uniform infiltration of the anode foil, a reduction in the risk of lithium precipitation on the surface of the anode film layer, and an improvement in the cycle performance of the battery cell; the mass fraction of the cyclic carbonate additive will not be too high, so that the film-forming impedance of the SEI film will not be too high, e.g., less than or equal to 8%, which promotes fast charging of the battery cell and further reduces the risk of lithium precipitation on the surface of the anode film layer, improving the cycle performance of the battery cell.

[0099] Thus, the embodiments of the present application are able to improve the cycle performance of the battery cell at high energy density. [Electrolyte solution]

[0100] The battery cell contains an electrolyte solution. During charging and discharging of the battery cell, active ions, such as lithium ions, are embedded and unembedded between the cathode foil and the anode foil, and the electrolyte solution acts as a conductor for active ions between the cathode foil and the anode foil.

[0101] The electrolyte solution comprises an organic solvent, an additive, and an electrolyte salt.

[0102] In the embodiment of the present application, the electrolyte solution comprises vinyl carbonate, wherein the mass content of the vinyl carbonate in the electrolyte solution is 20% to 40%, optionally 20% to 35%.

[0103] For example, the mass fraction of vinyl carbonate is 20%, 25%, 30%, 35%, 40% or any value in a range between two of these values.

[0104] Vinyl carbonate is able to form components of the SEI film on the anode side, which contain organic components (such as polyether substances) and inorganic components, and its synergistic effect with the cyclic carbon additive can optimize the components of the SEI film and improve the protective effect on the anode side.

[0105] If the mass fraction of vinyl carbonate is too low, the SEI film formed on the anode side is too thin and the protective strength is weakened, which cannot effectively mitigate the volume expansion of the silicon-based material on the anode side, and the side reaction on the anode side is still serious; In the case where the mass fraction of vinyl carbonate is greater than or equal to 20%, the protective strength of the SEI film is increased, which can effectively mitigate the volume expansion of the anode side and the side reaction on the anode side, and improve the cycle performance of the battery cell;

[0106] If the mass fraction of vinyl carbonate is too high, the viscosity of the electrolyte solution is too high, the mobility of the electrolyte solution is poor, the infiltration of the anode foil is uneven, and lithium precipitation on the surface of the anode film layer can easily occur; whereas, in the embodiment of the present application, the mass fraction of vinyl carbonate is not too high, for example, less than or equal to 40%, the viscosity of the electrolyte solution is not too high, which contributes to uniform infiltration of the anode foil, reduces the risk of lithium precipitation on the surface of the anode film layer, and improves the cycle performance of the battery cell.

[0107] In some embodiments, the organic solvent also includes a linear ester solvent, and the viscosity of the linear ester solvent is low, resulting in a low viscosity of the electrolyte solution. This improves the infiltration performance of the electrolyte solution onto the electrode foil and enhances the cycle performance of the battery. Furthermore, the linear ester solvent can improve the transfer rate of lithium ions in the electrolyte solution, contributing to improved fast-charging performance of the battery.

[0108] In some embodiments, the linear ester solvent comprises one or more linear carboxylic acid ester solvents and linear carbonate solvents, and the mass fraction of the linear ester solvent in the electrolyte solution is 45% to 65%, e.g., 45%, 50%, 55%, 60%, 65%, or any value in the range between two of these values. The linear ester solvent with the above mass fraction is advantageous for improving the cycle performance and fast-charging performance of the battery cell.

[0109] For example, the linear carboxylic acid ester solvent comprises a compound represented in formula I,

[0110] In Formula 1, R1 comprises a hydrogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group. R2 comprises a C1 to C5 alkyl group or a C1 to C5 haloalkyl group.

[0111] The lower viscosity of the above linear carboxylic acid ester solvent improves the fast-charging capability of the battery cell at high energy density and reduces the risk of lithium precipitation during fast charging, thereby improving the cycle performance of the battery cell.

[0112] Optionally, R1 comprises a hydrogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group. Further optionally, R1 comprises a hydrogen atom, a C1 to C2 alkyl group, or a C1 to C2 haloalkyl group.

[0113] Optionally, R2 comprises a C1 to C3 alkyl group or a C1 to C3 haloalkyl group. Further optionally, R2 comprises a C1 to C2 alkyl group or a C1 to C2 haloalkyl group.

[0114] In each of the above embodiments, the haloalkyl group comprises one or more of a fluoroalkyl group, a chloroalkyl group, a bromoalkyl group and an iodoalkyl group, and optionally the haloalkyl group comprises a fluoroalkyl group.

[0115] For example, the linear carboxylic acid ester solvent comprises one or more of the compounds shown in Formula I-1 to Formula I-12,

[0116] The above materials can further improve the cycle performance of the battery cell effectively at high energy density.

[0117] For example, the linear carbonate solvent comprises one or more of dimethyl carbonate, diethyl carbonate, and methylethyl carbonate. The above materials can further and effectively improve the cycle performance of the battery cell at high energy density.

[0118] In the embodiment of the present application, the electrolyte solution further comprises an additive, wherein the additive comprises a cyclic carbonate additive, wherein the cyclic carbonate additive has a mass content of 2% to 8% in the electrolyte solution.

[0119] For example, the cyclic carbonate additive has a mass content of 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% or any value in a range between two of these values.

[0120] If the mass fraction of the cyclic carbonate additive is less than 2%, the film layer formed on the anode side is thin, which is detrimental to the protection of the active anode material. Increasing the mass fraction of the cyclic carbonate additive improves the film formation effect on the anode side, providing excellent protection for the active anode material, reducing side reactions on the anode side, and improving cycle performance. However, with further increases in the mass fraction of the cyclic carbonate additive, the SEI film formed on the anode side has a higher impedance, which is detrimental to fast charging and can lead to lithium precipitation during the cycling process, thus degrading cycle performance.Therefore, the mass content of the cyclic carbonate additive in the embodiment of the present application is regulated to 2% to 8%, which can effectively improve the cycle performance of the battery cell at high energy density.

[0121] In some embodiments, the mass fraction of vinylidene carbonate in the electrolyte solution is 1.5% to 5%, such as 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any value in the range between these two values. When the mass fraction of vinylidene carbonate is in the above range, a dense SEI film containing organic components can form on the anode side, and the impedance of the SEI film is relatively low, which reduces side reactions on the anode side and improves the cycle performance of the battery cell at high energy density.

[0122] Vinylidene carbonate is capable of forming an organically rich SEI film on the anode side, and the volume changes of the active anode material during battery cell cycles do not essentially lead to SEI film rupture. Furthermore, vinylidene carbonate and vinyl carbonate act synergistically: vinyl carbonate can increase the inorganic components in the SEI film, improve its mechanical properties, further enhance its stability, provide more effective protection for the active anode material, and ultimately improve the battery cell's cycle life.

[0123] In some embodiments, the mass content of the vinyl carbonate derivative in the electrolyte solution is 0 to 4%, optionally 1.5% to 3.5%.

[0124] For example, the mass fraction of the vinyl carbonate derivative in the electrolyte solution is 0, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or any value in a range between two of these values.

[0125] If the mass content of the vinyl carbonate derivative is 0, for example: It is possible that no vinyl carbonate derivative is added to the freshly prepared electrolyte solution. or the electrolyte solution obtained after disassembly of the battery cell contains no vinyl carbonate derivatives, which may be the case if no vinyl carbonate derivatives are added to the freshly prepared electrolyte solution, or if a small amount of vinyl carbonate derivatives is added, which, however, is involved in the film formation reaction of the SEI film during the formation of the battery cell, so that the mass content of the vinyl carbonate derivative in the test procedure is 0.

[0126] Optionally, the freshly prepared electrolyte solution includes the vinyl carbonate derivative.

[0127] When certain substances, such as additives, are added to the electrolyte solution, the additive concentration in the battery cell's electrolyte solution is related to the various life cycles or storage conditions of the battery after formation, since the additive has the property of participating in film formation on the surface of the active material. Therefore, the additive concentration in the freshly prepared electrolyte solution may differ from that in the electrolyte solution obtained by reverse disassembly of the battery. However, a person skilled in the art can determine the approximate range of the concentration of the corresponding substances in the fresh electrolyte solution based on the battery cell's performance level (e.g., the number of cycles), residual concentration, and the like. Similarly, a person skilled in the art can also determine the approximate range of the corresponding additive concentration in the non-freshly prepared electrolyte solution (i.e., the concentration in the electrolyte solution obtained by reverse disassembly of the battery).(converse) content based on the additive content of the freshly produced additive based on the performance requirements for the battery cell, the storage environment, and the like.

[0128] Therefore, the additive content referred to in the technical solution of the present application can be the content of the additive that is actively added to the fresh electrolyte solution, or the content of the residual additive that is determined conversely according to the actual battery condition.

[0129] The vinyl carbonate derivative and the vinyl carbonate interact synergistically, with the vinyl carbonate derivative further optimizing the components of the SEI film, reducing its impedance, and effectively improving the cycle performance of the battery cell at high energy density. In cases where the vinyl carbonate derivative includes optional fluorine atoms, it can increase the fluorine content of the SEI film, improve its mechanical strength, effectively reduce the volumetric expansion of the silicon-based material, decrease the risk of SEI film breakage, and further enhance the cycle performance of the battery cell.

[0130] In some embodiments, the linear ester solvent comprises a linear carbonate solvent, and the mass fraction of the cyclic carbonate additive is 2% to 5%. Optionally, the linear ester solvent is a linear carbonate solvent, and the mass fraction of the cyclic carbonate additive is 2% to 5%. The above electrolyte solution system contributes to further improving the cycle performance of the battery cell.

[0131] In some other embodiments, the linear ester solvent comprises a linear carboxylic acid ester solvent with a mass fraction >0 and a linear carbonate solvent with a mass fraction ≥0, and the mass fraction of the cyclic carbonate additive is 3.5% to 8%. The above electrolyte solution system contributes to further improving the cycle performance of the battery cell.

[0132] Optionally, the linear ester solvent is a linear carboxylic acid ester solvent, and the mass content of the cyclic carbonate additive is 3.5% to 8%.

[0133] For example, the linear ester solvent is a mixture of a linear carboxylic acid ester solvent and a linear carbonate solvent, and the cyclic carbonate additive has a mass content of 3.5% to 8%.

[0134] In the embodiment of the present application, the vinyl carbonate derivative means that at least one hydrogen atom of the vinyl carbonate is substituted, and the substituent group can be one, two, three or four, and so on.

[0135] For example, the vinyl carbonate derivative comprises a compound represented in formula A,

[0136] In formula A, Q1, Q2, Q3 and Q4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, and Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms.

[0137] Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms, i.e. at least one of Q1, Q2, Q3 and Q4 comprises a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group.

[0138] For example, one of Q1, Q2, Q3, Q4 comprises a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, and the others are hydrogen atoms.

[0139] For example, at least two of Q1, Q2, Q3, Q4 comprise a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 halogen alkyl group.

[0140] For example, at least three of Q1, Q2, Q3, Q4 comprise a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 halogen alkyl group.

[0141] For example, each of Q1, Q2, Q3, Q4 independently comprises a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 halogen alkyl group.

[0142] Optionally, at least one of Q1, Q2, Q3, and Q4 comprises a halogen atom or a C1 to C5 haloalkyl group. The halogen atom comprises a fluorine atom, a bromine atom, a chlorine atom, etc., optionally a fluorine atom. The C1 to C5 haloalkyl group comprises a C1 to C5 fluoroalkyl group, a C1 to C5 bromoalkyl group, or a C1 to C5 chloroalkyl group, etc., optionally a C1 to C5 fluoroalkyl group. For example, the C1 to C5 fluoroalkyl group comprises fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, or fluoropentyl.

[0143] In the case where the vinyl carbonate derivative contains a fluorine atom, the vinyl carbonate derivative can form a film layer with high F and Li content on the anode side, which can protect the active anode material due to a lower impedance of the film layer and improve the cycle performance of the battery cell at high energy density.

[0144] For example, the vinyl carbonate derivative comprises one or more of the compounds shown in Formula A-1 to Formula A-6,

[0145] The above materials can further improve the cycle performance of the battery cell at high temperature and high energy density.

[0146] Optionally, the vinyl carbonate derivative comprises one or more of the compounds shown in formula A-1 to formula A-3; further optionally, the vinyl carbonate derivative comprises a compound shown in formula A-1.

[0147] In some embodiments, the additive further comprises one or more, optionally at least two, sulfur-containing additives and lithium salt additives. The above additive can improve the performance of the interfacial film on the cathode side and / or the anode side, which contributes to improving the fast-charging performance of the battery cell and improving its cycle performance.

[0148] In some embodiments, the electrolyte solution comprises a sulfur-containing additive with a mass fraction of 0 to 2% in the electrolyte solution. For example, the mass fraction of the sulfur-containing additive is 0, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any value in a range between any two of these values. Optionally, the mass fraction of the sulfur-containing additive in the electrolyte solution is 0.5% to 2%.The sulfur-containing additive and the cyclic carbonate additive, when synergistically integrated into the film formation process, can optimize the composition of the SEI film, and the sulfur-containing additive can participate in the formation of the SEI film, which is rich in inorganic substances, and the inorganic substances can improve the stability of the SEI film at high temperature and high pressure, thus improving the cycle performance of the battery cell at high temperature and high energy density.

[0149] For example, the sulfur-containing additive includes one or more of vinyl sulfate DTD, vinyl bisulfate 2-DTD, 1,3-propanesulfonyllactone, butylenyl sulfite bs, vinyl sulfite ES and methylenedisulfonylmethane MMDS.

[0150] In some embodiments, the electrolyte solution comprises a lithium salt-like additive with a mass fraction of 0 to 1%, such as the lithium salt-like additive with a mass fraction of 0, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or any value in a range between two of these values. Optionally, the mass fraction of the lithium salt-like additive in the electrolyte solution is 0.2% to 1%. The lithium salt-like additive and the cyclic carbonate additive, when synergistically incorporated into the film formation process, can optimize the composition of the SEI film, and the lithium salt-like additive can participate in the formation of the SEI film, which is rich in inorganic substances, and the inorganic substances can improve the stability of the SEI film at high temperature and high pressure, thus improving the cycle performance of the battery cell at high energy density.

[0151] For example, the lithium salt-like additive comprises one or more of lithium difluorophosphate LiPO2F2, lithium difluorooxalate borate LiDFOB, lithium tetrafluoroborate LiBF4 and lithium bisoxalate borate LiBOB.

[0152] In some embodiments, the electrolyte salt comprises a lithium electrolyte salt, wherein the lithium electrolyte salt has a mass fraction of 10% to 18% in the electrolyte solution, such as 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or any value in the range between two of these values. The above lithium electrolyte salt can improve the cycle performance of the battery cell.

[0153] Optionally, the electrolyte lithium salt comprises one or more lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6). The above electrolyte lithium salt can improve the cycle performance of the battery cell.

[0154] In some embodiments, the mass fraction of lithium bis(fluorosulfonyl)imide (LiFSI) in the electrolyte solution is 4% to 6%, e.g., 4%, 4.5%, 5%, 5.5%, 6%, or any value in the range between these two values. When the mass fraction of lithium bis(fluorosulfonyl)imide (LiFSI) is within the above range, the mass fraction of lithium hexafluorophosphate can be reduced, thereby decreasing the amount of acid generated in the electrolyte solution, reducing the side reaction, and improving the cycle performance of the battery cell.

[0155] In the embodiment of the present application, the nature and content of the inorganic component / electrolyte lithium salt in the electrolyte solution are known in the art and can be detected using equipment and methods known in the art; for example, the inorganic component / electrolyte lithium salt in the electrolyte solution can be qualitatively or quantitatively analyzed by ion chromatography with reference to the standard JY / T 0575-2020 "General principles of ion chromatography analysis methods".In the embodiments of the present application, a freshly prepared electrolyte solution can be taken as a sample, and a free electrolyte solution from a freshly prepared battery can be taken as a sample, or a discharged battery cell (which has been discharged to a discharge cut-off voltage so that the state of charge of the battery cell is approximately 0% SOC) can be disassembled in the reverse manner, and the free electrolyte solution obtained from the battery cell can be taken as a sample. The test is carried out by ion chromatographic analysis.

[0156] In the embodiment of the present application, the nature and content of the organic components in the electrolyte solution are known in the art and can be detected using equipment and methods known in the art; for example, the organic components in the electrolyte solution can be qualitatively and quantitatively analyzed by means of gas chromatography with reference to GB / T9722-2006 “General principles for the gas chromatography of chemical reagents”. [Anode foil]

[0157] The anode foil comprises an anode collector and an anode film layer arranged on at least one surface of the anode collector and comprising an active anode material. For example, the anode collector has two surfaces opposite each other in its thickness direction, and the anode film layer is provided on one or both of the two surfaces opposite the anode collector.

[0158] The upper charging voltage and the discharge cut-off voltage of the battery cell differ depending on the active cathode material. For example, if the phosphate material contains lithium iron phosphate, the upper charging voltage can be 3.65 V and the discharge cut-off voltage 2.0 V. Similarly, if the phosphate material contains lithium manganese iron phosphate, the upper charging voltage can be 4.2 V and the discharge cut-off voltage 2.0 V. The state of the battery cell is then illustrated using the example of an upper charging voltage of 3.65 V and a discharge cut-off voltage of 2.0 V. In the embodiment of the present application, the state of charge (SOC) of the battery cell at 100% charge and the state of charge (SOC) of the battery cell at 0% charge are defined as follows.

[0159] The battery cell is charged at a constant current rate of 0.33C up to the upper charging voltage and then charged at a constant voltage down to 0.05C, which corresponds to a state of 100% SOC (State of Charge). The battery cell is then discharged at a constant current rate of 0.33C down to the cutoff voltage, which corresponds to a state of 0% SOC.

[0160] In the embodiment of the present application, the active anode material comprises a silicon-based material. The introduction of the silicon-based material can improve the capacity of the active anode material and increase the energy density of the battery cell.

[0161] The mass content of the silicon element in the silicon-based material in the anode film layer is 0.5% to 5%, optionally 0.8% to 3%.

[0162] For example, the mass fraction of the silicon element is 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, or any value in the range between two of these values. A silicon element mass fraction within the above range can improve the energy density and cycle life of the battery cell.

[0163] Optionally, the silicon-based material can include one or more monomeric silicon, silicon-oxygen, silicon-carbon, or silicon-nitrogen materials. The above materials have a high gram capacity, which is beneficial for increasing the energy density of the battery cell.

[0164] Optionally, the silicon-based material can comprise one or more silicon oxide, silicon-carbon, or silicon-nitrogen materials. The silicon-based material can also optionally comprise silicon-carbon materials. The above material exhibits relatively good cycle stability during the battery cell's cycling process, contributing to a balanced improvement in the battery cell's energy density and cycle performance.

[0165] The silicon-carbon material can, for example, contain a porous carbon skeleton and silicon arranged within that porous carbon skeleton, and the silicon can be nanosilicon. The nanosilicon can be deposited within the porous carbon skeleton by processes such as chemical deposition from the gas phase, and specific process parameters known in engineering can be used.

[0166] In the case where the silicon-based material comprises one or more silicon oxide, silicon-carbon, or silicon-nitrogen materials; in particular, where the silicon-based material comprises a silicon-carbon material, the silicon-based material is able to further improve the energy density and cycle performance of the battery cells by improving at least one parameter such as the mass fraction of a silicon element, a volume mean particle size, a specific surface area, a powder density, and the like.

[0167] For example, the mass fraction of the silicon element, relative to the mass of the silicon-based material, is 40% to 80%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any value in a range between two of these values.

[0168] For example, the volume-mean particle size Dv50 of the silicon-based material is 5.0 µm to 12.5 µm, such as 5.0 µm, 5.5 µm, 6.0 µm, 6.5 µm, 7.0 µm, 7.5 µm, 8.0 µm, 8.5 µm, 9.0 µm, 9.5 µm, 10.0 µm, 10.5 µm, 11.0 µm, 11.5 µm, 12.0 µm, 12.5 µm or any value in a range between two of these values.

[0169] In the embodiment of the present application, the volume-average particle size Dv50 of the material refers to the particle size corresponding to 50% in the volume distribution, which can be tested using equipment and methods known in the art, such as using the active cathode material as a sample and testing the Dv50 of the particles with a Mastersizer 2000E laser particle size analyzer in accordance with test standard GB / T 19077-2016 and the like.

[0170] For example, the specific surface area of ​​the silicon-based material is 3.1 m². 2 / g up to 3.6 m 2 / g, like 3.1 m2 / g, 3.2 m 2 / g, 3.3 m 2 / g, 3.4 m 2 / g, 3.5 m 2 / g, 3.6 m 2 / g or any value in a range between two of these values.

[0171] In the embodiment of the present application, the specific surface area of ​​the material has a meaning known in the art and can be tested using equipment and methods known in the art. For example, the test is carried out in accordance with test standard GB / T 19587-2017, and the active cathode material is used as a sample to test the specific surface area using a Tri-Star 3020 pore size analyzer from Micromeritics, Inc. in the United States.

[0172] For example, the powder density of the silicon-based material is 0.7 g / cm³. 3 up to 1.2 g / cm³ 3 at 25000 N, equivalent to 0.7 g / cm³ 3 , 0.8 g / cm³ 3 , 0.9 g / cm³ 3 , 1.0 g / cm³ 3 , 1.1 g / cm³3 , 1.2 g / cm³ 3 or any value within a range between two of these values.

[0173] If the powder density of the silicon-based material is in the above range at 25000N, the energy density of the battery cell can be increased; and since the active anode material can be stacked more densely in the anode film layer, the particle-to-particle contact resistance is lower, which can further reduce the resistance of the electrode foil, thereby decreasing heat generation and improving the cycle performance of the battery cell at high energy density.

[0174] In the embodiment of the present application, the powder density of the material has a meaning known in the art and can be tested using methods and equipment known in the art based on the test standard GB / T24533-2009. For example, a certain quantity of the active anode material is taken as a sample and placed in a mold with a base area of ​​1.327 cm². 2 The powder is placed in an electronic pressure testing device UTM7305, subjected to a pressure of 2500 kg (equivalent to 25000 N), held for 30 seconds, then depressurized and held for 10 seconds, and then the powder density of the active anode material under the force of 25000 N is recorded and calculated.

[0175] In the embodiment of the present application, the active anode material further comprises a carbon-based material, and the carbon-based material comprises graphite particles, and the graphite particles exhibit high cycle stability, which can improve the cycle performance of the battery cell. The active cathode material of the present application is mainly a lithium-containing phosphate system, and the active anode material is mainly a system of graphite and a silicon-based material, and the use of the two in combination can improve the energy density of the lithium-containing phosphate battery cell, taking into account the lifetime of the battery cell.

[0176] In some embodiments, the graphite particles comprise graphite body particles and an anode coating layer. The graphite body particles comprise secondary particles, the secondary particles comprise a plurality of primary particles, the anode coating layer is coated on the surface of the graphite body particles, and the anode coating layer comprises carbon elements. The carbon in the anode coating layer is mainly amorphous carbon. Amorphous carbon refers to a carbon material in a transitional state in which graphite has a very low degree of crystallinity and an approximately amorphous shape (or no solid shape and no periodic structural pattern). In the present application, amorphous carbon refers to the product of a carbonization treatment with an organic carbon source.

[0177] The graphite body particles include secondary particles, so the migration path of lithium ions in the graphite body particles is more numerous and shorter than in the primary particles, which can increase the migration rate of lithium ions; the anode coating layer has more end faces and defects, so the number of sites where lithium ions can de-embed is higher, the conductivity of the anode coating layer is better, the internal resistance of the anode foil can be reduced, and the heat generation of the battery cell is reduced, thereby improving the cycle performance of the battery cell at high energy density.

[0178] For example, the graphite body particles comprise one or more of artificial graphite and natural graphite, optionally artificial graphite.

[0179] Optionally, the mass fraction of the carbon element in the anode coating layer is 2% to 5%, based on the mass of the graphite particles. For example, the mass fraction of the carbon element in the anode coating layer is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any value in the range between two of these values.

[0180] If the mass content of the carbon element in the anode coating layer is in the above range, the internal resistance of the anode foil can be further reduced, the heat generation of the battery cells can be reduced, and the cycle performance of the battery cells can be improved at high energy density.

[0181] If the powder resistance of the graphite particles is in the above range, the resistance of the anode foil is relatively low, which reduces the internal resistance of the anode foil, reduces the heat generation of the battery cell and improves the cycle performance of the battery cell at high energy density.

[0182] In the embodiment of the present application, the graphite particles can be produced by a method known in the art, the graphite particles being, for example, artificial graphite, a production method comprising the following: providing artificial graphite and an organic carbon source, mixing the two and forming an anode coating layer on at least a part of the surface of the artificial graphite particles after a carbonization treatment.

[0183] Optionally, the organic carbon source comprises one or more of coal pitch, petroleum pitch, phenolic resin, and coconut shell. Furthermore, the organic carbon source may include petroleum asphalt. Optionally, the coal asphalt or petroleum asphalt has a softening point of 250°C or less.

[0184] Optionally, the temperature for the carbonization treatment is between 700°C and 1800°C. Optionally, the temperature for the carbonization treatment is between 1000°C and 1300°C. The temperature for the carbonization treatment is within a suitable range to carbonize the organic carbon source and form an anode coating layer of amorphous carbon on at least part of the surface of the synthetic graphite.

[0185] Optionally, the carbonation time can be between 1 hour and 6 hours.

[0186] In some embodiments, the carbon-based material may also include natural graphite. In particular, the carbon-based material may contain graphite particles, or the carbon-based material may comprise graphite particles and natural graphite. Optionally, the carbon-based material may consist of graphite particles.

[0187] In some embodiments, the active anode material may, in addition to the carbon-based and silicon-based materials mentioned above, contain one or more tin-based materials and lithium titanate. The tin-based material may contain one or more monomeric tin materials, tin oxide materials, and tin alloy materials.

[0188] The qualitative characterization and quantitative characterization of each substance or element in the present application can be tested using suitable equipment and methods known to a person skilled in the art. The relevant test procedure may refer to domestic and foreign testing standards, domestic and foreign company standards, etc. A person skilled in the art may also adaptively modify certain test steps / instrument parameters, etc., with regard to accuracy, in order to obtain a more accurate test result. A test procedure may be used qualitatively or quantitatively, and several test procedures may be used together for a qualitative or quantitative determination.

[0189] For example, the mass fraction of the silicon element in the anode film layer has a well-established significance in engineering and can be tested using established equipment and procedures. For instance, the anode foil is immersed in a solvent such as water, the active anode material is separated from the anode collector, and the substances in the anode film layer are extracted by pumping and filtering; these substances are then used as test samples. The mass fraction of the silicon element can be determined by placing the test samples in an inductively coupled plasma emission spectrometer, model ICAP7400, manufactured by Thermo Fisher Scientific, in accordance with standard GB / T30902-2014.

[0190] The present application can, for example, also be combined with the method JIS / K0131-1996 “General principles of X-ray diffraction analysis” to test and qualitatively analyze the X-ray powder diffraction of the anode foil or active anode material.

[0191] Artificial and natural graphite can be distinguished by scanning electron microscope (SEM) profiles. Natural graphite's SEM profiles show voids between platelet structures, while artificial graphite's SEM profile is dense and lacks obvious gaps. Alternatively, it can be distinguished by its X-ray diffraction (XRD) spectrum. Natural graphite's XRD spectrum shows obvious 2H and 3R phases, whereas artificial graphite's XRD spectrum shows only the 2H phase.

[0192] The anode film layer in the embodiment of the present application comprises at least one film layer, wherein a single film layer or at least two film layers may be used. The anode film layer may contain two film layers, three film layers, four film layers or even more film layers.

[0193] In some embodiments, the anode film layer comprises a first anode film layer and a second anode film layer, wherein the first anode film layer is arranged on a surface of the anode collector, the carbon-based material in the first anode film layer comprises graphite particles, and the second anode film layer is connected to a side of the first anode film layer facing away from the anode collector, and the carbon-based material in the second anode film layer comprises graphite particles.

[0194] The anode film layer comprises at least two film layers, and the layered coating is advantageous for improving the fast-charging performance of the battery cell. Specifically, if there is a difference between the first and second anode film layers, it is possible to create a difference in the pores of the anode film layer, reducing the degree of zigzag lithium-ion transfer and improving the fast-charging performance of the battery cell.

[0195] Optionally, the volume-mean particle size Dv50 of the active anode material in the first anode film layer is greater than or equal to the volume-mean particle size Dv50 of the active anode material in the second anode film layer. Furthermore, optionally, the volume-mean particle size Dv50 of the active anode material in the first anode film layer is greater than the volume-mean particle size Dv50 of the active anode material in the second anode film layer, which increases the packing density of the anode film layer. If the active anode material includes graphite particles, the volume-mean particle size Dv50 of the graphite particles in the first anode film layer is greater than or equal to the volume-mean particle size Dv50 of the graphite particles in the second anode film layer.

[0196] The difference in particle size between the first and second anode film layers can improve the fast-charging performance of the battery cell. In particular, the overpotential of the second anode film layer is typically high, and the charging bottleneck is primarily located there. The relatively small particle size of the particles in the second anode film layer, as described in the present application, can shorten the solid-state transfer path of the lithium ions, improve fast-charging performance, mitigate the problem of lithium precipitation in the surface layer of the anode film, and enhance cycle performance.

[0197] Optionally, the active anode material in the first anode film layer has the form of particles with a volume-average particle size Dv50 of 9.8 µm to 16.8 µm, for example 9.8 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, 12.5 µm, 13 µm, 13.5 µm, 14 µm, 14.5 µm, 15 µm, 15.5 µm, 16 µm, 16.5 µm, 16.8 µm or any value in a range between two of these values. If the first anode film layer contains graphite particles, the volume mean particle size Dv50 of the graphite particles in the first anode film layer is 9.8 µm to 16.8 µm.

[0198] If the volume-average particle size Dv50 of the active anode material in the first anode film layer is in the above range, it can, on the one hand, shorten the solid-phase transfer path of the lithium ions, improve fast charging performance, and on the other hand, the material is less prone to agglomeration during the manufacturing process, which can increase the stability of the material and improve cycle performance.

[0199] Optionally, the active anode material in the second anode film layer has the form of particles with a volume-mean particle size Dv50 of 8.5 µm to 14.5 µm, for example, 8.5 µm, 9.0 µm, 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, 12.5 µm, 13 µm, 13.5 µm, 14 µm, 14.5 µm, or any value in the range between two of these values. If the second anode film layer comprises graphite particles, the volume-mean particle size Dv50 of the graphite particles in the second anode film layer is 8.5 µm to 14.5 µm.

[0200] If the volume mean particle size Dv50 of the active anode material in the second anode film layer is in the above range, it can, on the one hand, shorten the solid-phase transfer path of the lithium ions, improve fast charging performance, and on the other hand, the material is less prone to agglomeration during the manufacturing process, which can increase the stability of the material and improve cycle performance.On the other hand, the interaction between the active anode material in the second anode film layer and the active anode material in the first anode film layer with the volume-mean particle size in the above region is conducive to the establishment of a gradient pore difference between the second anode film layer and the first anode film layer, thereby reducing the tortuosity degree of lithium-ion transfer, allowing the lithium ions to be rapidly precipitated by gaining electrons on the anode side, reducing the risk of lithium precipitation, and improving cycle performance.

[0201] In some embodiments, at least one layer of the first anode film layer and the second anode film layer comprises a silicon-based material.

[0202] For example, the first anode film layer comprises a silicon-based material. The second anode film layer can effectively mitigate the volume expansion of the silicon-based material in the first anode film layer and improve the cycle performance of the battery cell.

[0203] For example, the second anode film layer comprises a silicon-based material.

[0204] For example, both the first anode film layer and the second anode film layer consist of a silicon-based material, and this arrangement helps to increase the energy density of the battery cell.

[0205] In some embodiments, the density of the anode film layer at a 100% charge level of the battery cell is 1.10 g / cm³. 3 up to 1.50 g / cm³ 3 For example, the density of the anode film layer at a 100% charge level of the battery cell is 1.10 g / cm³. 3 , 1.15 g / cm³ 3 , 1.20 g / cm³3 , 1.22 g / cm³ 3 , 1.25 g / cm³ 3 , 1.28 g / cm³ 3 , 1.3 g / cm³ 3 , 1.32 g / cm³ 3 , 1.35 g / cm³ 3 , 1.40 g / cm³ 3 , 1.45 g / cm³ 3 , 1.50 g / cm² 3 or any value within a range between two of these values.

[0206] If the density of the cathode layer is in the above range, this is beneficial for increasing the energy density of the battery cell, and since the active anode material is more densely packed in the anode film layer, the particle-to-particle contact resistance is lower, which can further reduce the resistance of the electrode foil, thereby decreasing heat generation, and thus reducing the amount of gas produced by the decomposition of the carboxylic acid ester solvent due to heat accumulation, and improving the cycle performance of the battery cell.

[0207] In the embodiment of the present application, the compression density of the anode film layer at a 100% charge state of the battery cell is a meaning known in the art and can be tested with devices and methods known in the art, and the test method is such as the compression density test method for the cathode film layer.

[0208] In some embodiments, the one-sided coating weight of the anode film layer is 90 mg / 1540.25 mm². 2 up to 140 mg / 1540.25 mm 2 For example, the one-sided coating weight of the anode film layer is 90 mg / 1540.25 mm². 2 , 92 mg / 1540.25 mm 2 , 95 mg / 1540.25 mm 2 , 96 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 102 mg / 1540.25 mm 2 , 104 mg / 1540.25 mm 2 , 105 mg / 1540.25 mm 2 , 108 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 112 mg / 1540.25 mm 2 , 114 mg / 1540.25 mm 2, 115 mg / 1540.25 mm 2 , 116 mg / 1540.25 mm 2 , 118 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 122 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2 , 128 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 132 mg / 1540.25 mm 2 , 135 mg / 1540.25 mm 2 , 137 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 or any value within a range between two of these values.

[0209] If the one-sided coating weight of the anode film layer is within the above range, the heat generation per unit area of ​​the anode foil is not too high, and the cycle performance of the battery cell at high energy density is improved at the same time.

[0210] In the embodiment of the present application, the single-sided coating weight of the anode film layer is a known value in the art and can be determined using equipment and methods known in the art. The anode foil is removed from a battery cell with a state of charge of 100% SOC, and the compression density of the anode foil is determined, for example, by taking a single-sided coated anode foil (in the case of a double-sided coated electrode foil, the anode film layer can be wiped off one side first), punching and cutting it into a small disc with an area of ​​S1, weighing it, recording it as M1, and measuring its thickness as H1. Then, the anode film layer of the anode foil, which was weighed as described above, is wiped off, and the weight of the anode collector is weighed and recorded as M0, and its thickness H0 is measured.The one-sided coating weight of the anode film layer = (weight of the anode foil M1 - weight of the anode collector M0) / S1, the thickness of the anode film layer = thickness H1 of the anode foil - thickness H0 of the anode collector, and the pressing density of the anode film layer = the one-sided coating weight of the anode film layer / thickness of the anode film layer.

[0211] In some embodiments, the anode film layer further comprises an anode binder, wherein the anode binder comprises one or more of styrene-butadiene rubber (SBR), a water-soluble unsaturated resin SR-1B, an aqueous acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass fraction of the anode binder, based on the total mass of the anode film layer, is ≤5%.

[0212] In some embodiments, the anode film layer optionally further comprises a conductive anode material. The embodiments of the present application do not specifically restrict the type of conductive anode material, and by way of example, the conductive anode material comprises one or more of the following: superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass fraction of the conductive anode material, based on the total weight of the anode film layer, is ≤5%.

[0213] In some embodiments, the anode film layer optionally comprises other additives. These additives may include, for example, thickeners, dispersants, etc., such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor materials, and the like. In some embodiments, the mass fraction of the other additives, based on the total weight of the anode film layer, is ≤2%.

[0214] In some embodiments, the anode collector can be a metal foil or a composite collector. Examples of the metal foil include one or more sheets of copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. The composite collector can comprise a polymer base layer and a metallic material layer formed on at least one surface of the polymer base layer. For example, the metallic material in the metallic material layer can include one or more sheets of copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. For example, the polymer base layer can comprise one or more sheets of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0215] The anode film layer is typically produced by applying an anode slurry to the anode collector, drying, and cold pressing. The anode slurry is usually prepared by dispersing the active anode material, an optional conductive agent, an optional binder, and other optional additives, etc., in a solvent and mixing thoroughly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0216] In some embodiments, the thickness of the anode collector is 4 µm to 6 µm, for example 4 µm, 5 µm, 6 µm, or any value in a range between two of these values. When the thickness of the anode collector is within the above range, the anode collector becomes thinner, which contributes to an improvement in the volumetric energy density of the battery cell.

[0217] The anode foil does not preclude the inclusion of additional functional layers besides the anode film layer. In some embodiments, the anode foil in one embodiment of the present application further comprises a conductive anode layer, which is provided between the anode collector and the anode film layer and is located on the surface of the anode collector. In some other embodiments, the anode foil in one embodiment of the present application further comprises a protective layer covering the surface of the anode film layer.

[0218] In some embodiments, the anode foil further comprises a conductive anode layer located between the anode film layer and the anode collector. The conductive anode layer can further improve the conductivity of the anode foil, reduce the heat generation of the anode foil, and thus reduce the heat generation of the battery cell, which improves the fast-charging performance and the cycle performance of the battery cells at high temperatures.

[0219] In some embodiments, the thickness of the conductive anode layer is 0.5 µm to 2 µm. For example, the thickness of the conductive anode layer can be 0.5 µm, 0.8 µm, 1 µm, 1.2 µm, 1.5 µm, 1.6 µm, 1.8 µm, 2 µm, or any value in a range between two of these values.

[0220] If the thickness of the conductive anode layer is in the above range, the conductivity of the anode foil can be further improved, the heat generation of the anode foil can be reduced, and thus the heat generation of the battery cell can be reduced, and the energy density of the battery cell can be improved at the same time.

[0221] In the embodiment of the present application, the thickness of the conductive anode layer has a meaning known in the art, such that it can be tested using devices and methods known in the art, such as tomography of the anode foil for direct measurement of the thickness of the conductive anode layer.

[0222] In some embodiments, the conductive anode layer comprises one or more conductive anode media and an anode binder. The conductive anode media of the conductive anode layer can increase the conductivity of the conductive anode layer, thereby increasing the conductivity of the anode foil and reducing heat generation in the battery cell, and the anode binder of the conductive anode layer can improve the bonding performance between the anode collector and the anode film layer, thereby increasing the structural stability of the anode foil.

[0223] In some embodiments, the conductive anode layer optionally comprises other additives. These other additives may include, for example, thickening agents such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, and the like.

[0224] Optionally, the conductive anode compound of the conductive anode layer has a mass fraction of 20% to 40% in the conductive anode layer. For example, the mass fraction of the conductive anode compound is 20%, 25%, 30%, 35%, 40%, or any value in a range between two of these values.

[0225] For example, the conductive anode material of the conductive anode layer comprises one or more of the following materials: superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0226] Optionally, the mass fraction of the anode binder in the conductive anode layer is 60% to 80%. For example, the mass fraction can be 60%, 65%, 70%, 75%, 80%, or any value in the range between two of these values.

[0227] For example, the conductive anode material of the conductive anode layer comprises one or more of styrene-butadiene rubber SBR, water-soluble unsaturated resin SR-1B, aqueous acrylic resin, polyvinyl alcohol, sodium alginate and carboxymethyl chitosan. [Cathode foil]

[0228] The cathode foil comprises a cathode collector and a cathode film layer arranged on at least one surface of the cathode collector and comprising an active cathode material. For example, the cathode collector has two surfaces opposite each other in its thickness direction, and the cathode film layer is provided on one or both of the two surfaces opposite the cathode collector.

[0229] In the embodiment of the present application, the lithium-containing phosphate can be a phosphate particle having an olivine structure; or a material obtained by coating modification of the phosphate particle, e.g. the lithium-containing phosphate comprises phosphate particles and a cathode coating layer, wherein the cathode coating layer is coated on at least a part of a surface of the phosphate particles and the cathode coating layer comprises carbon elements.

[0230] Phosphate particles can increase the conductivity of the lithium-containing phosphate by surface coating the cathode coating layer, which promotes the migration rate of lithium ions, improves the fast charging capability of the battery, reduces the heat generation of the battery cell and improves the cycle performance of the battery cell.

[0231] Examples of phosphate particles include, but are not limited to, one or more of lithium iron phosphate, lithium manganese phosphate, lithium ferromanganese phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The above materials exhibit excellent cycle stability, which contributes to improved cycle performance of the battery cell.

[0232] In some embodiments, the lithium-containing phosphate comprises a material with the general formula of Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises one or more of the elements Na, K and Mg; where Me comprises one or more of the elements Mn, Fe, Co and Ni; wherein M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge and Ce; wherein X comprises one or more of the elements Cl, C, N and P, and wherein Y comprises one or more of the elements O and F.

[0233] The lithium-containing phosphate exhibits excellent cycle stability, which contributes to improving the cycle performance of the battery cell.

[0234] For example, the phosphate particles comprise one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. During charging and discharging, the battery cell undergoes deposition and depletion of active ions, such as lithium, and the molar lithium content of the battery cell varies depending on the discharge state. In the listing of active cathode materials such as LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., the molar lithium content represents an initial state of the material, i.e., the state before it is added. The molar lithium content changes when the active cathode material is added to the battery system after a charge and discharge cycle.In the embodiment of the present application, the molar fraction of oxygen O is only a theoretical state value; the lattice release of oxygen leads to a change in the molar fraction of oxygen O, and in practice the molar fraction of oxygen O will fluctuate; all the above-mentioned cases fall within the scope of protection of the present application.

[0235] In some embodiments, the mass fraction of the carbon element in the lithium-containing phosphate is 0.8% to 2.3%. For example, the mass fraction of the carbon element in the lithium-containing phosphate is 0.8%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.3%, or any value in a range between two of these values.

[0236] The carbon element is primarily present as a carbon coating layer within the cathode coating layer. This layer is loose and porous, which improves the material's specific surface area and promotes effective contact between the electrolyte solution and the phosphate particles, thus facilitating lithium ion transfer at the interface. When the carbon element mass fraction is within the range described above, the electrical conductivity of the lithium phosphate can be significantly enhanced. This improves both the ionic and electronic conductivity of the lithium phosphate and can enhance the fast-charging capability of the battery cell at high energy density.

[0237] In some embodiments, the cathode coating layer further comprises one or more of the elements Fe, Ti, Zr, Hf, Ge and Sn.

[0238] In some embodiments, the cathode coating layer comprises a compound with the general formula Li 3-d1 Fe 2-d1 M3 d1 (PO m1 ) n1 , where 0 ≤ d1 ≤ 1, 3 ≤ m1 ≤ 5 and 2 ≤ n1 ≤ 4, and where M3 comprises one or more of the elements Ti, Zr, Hf, Ge, Sn.

[0239] The connection of Li 3-d1 Fe 2-d1 M3 d1 (PO m1 ) n1 is a fast ion conductor with a NASICON structure, for example comprising one or more of lithium iron titanium phosphate Li2FeTi(PO4)3, lithium iron zirconium phosphate Li2FeZr(PO4)3, lithium iron tin phosphate Li2FeSn(PO4)3.

[0240] The fast-ion conductor with NASICON structure is a material with ultrafast ion conductivity, featuring numerous three-dimensional lithium-ion diffusion and transfer channels. It offers the advantages of high ion conductivity and strong structural stability during multiple lithium de- / embedding cycles. Surface coating of the phosphate particles with the fast-ion conductor featuring NASICON structure can significantly increase the lithium-ion transfer rate at the anode end during multiple lithium de- / embedding cycles, improve the ion conductivity of the active anode material, enhance the fast-charging capability of the battery cell, and, in addition to improving the gram capacity, increase the energy density of the corresponding battery cell.

[0241] The carbon monomers and the fast-ion conductor can be arranged in layers, e.g., the carbon monomers as a separate carbon shell layer and the fast-ion conductor as a separate fast-ion conductor layer, wherein the carbon coating layer can be coated on the surface of the phosphate particles and the fast-ion conductor layer is located on the surface of the carbon coating layer, i.e., the fast-ion conductor layer is located on the side of the carbon coating layer facing away from the phosphate particles, or the fast-ion conductor layer can be coated on the surface of the phosphate particles, and the carbon coating layer is located on the surface of the fast-ion conductor layer, i.e., the carbon coating layer is located on the side of the fast-ion conductor layer facing away from the phosphate particles.Of course, the carbon monomer and the rapid ion conductor can also be provided in one and the same layer.

[0242] Optionally, the carbon coating layer on the surface of the fast-ion conductor layer can be applied using an organic carbon source (e.g., glucose, polyethylene glycol, etc.) after a carbonization process. The carbon coating layer can partially or completely cover the fast-ion conductor layer. The carbon coating layer can be applied to significantly improve the electronic conductivity of the phosphate particles, compensating for the defect of poor electronic conductivity in the phosphate particles and improving the energy density of the battery cell.

[0243] The active cathode material of the present application, with lithium phosphate as the base material, fully exploits the advantages of lithium phosphate in terms of low cost, high reliability in use, and good cycle stability, while simultaneously overcoming the disadvantages of its poor electronic and ionic conductivity through the use of the cathode coating layer (fast ion-conducting layer and carbon coating layer). Battery cells manufactured from the active cathode materials of the present application exhibit improved battery cell energy density with excellent cycle performance.

[0244] In the embodiment of the present application, the proportion of elements in the active cathode material is of a meaning known in the art and can be determined using equipment and methods known in the art. With reference to EPA 6010D-2014, it is measured, for example, by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). The battery cell was discharged to 0% state of charge (SOC), and then the cathode foil was removed, cleaned with DMC, and dried. After high-temperature calcination and removal of impurities, 0.4 g of the active cathode material was weighed, and 10 ml (50% concentration) of aqua regia was added. It was then placed on a plate at 180°C for 30 minutes. After dissipation on the plate, it was fixed to a volume of 100 mL and quantitatively tested using the standard curve method.

[0245] In some embodiments, the active cathode material has a powder density of 2.46 g / cm³ at 30000 N. 3 up to 2.85 g / cm³ 3 on.

[0246] For example, the powder density of the active cathode material at 30,000 N is 2.46 g / cm³. 3 , 2.47 g / cm³ 3 , 2.48 g / cm³ 3 , 2.49 g / cm³ 3 , 2.5 g / cm³ 3 , 2.51 g / cm³ 3 , 2.55 g / cm³ 3 , 2.58 g / cm³ 3 , 2.60 g / cm³ 3 , 2.65 g / cm³ 3 , 2.68 g / cm³ 3 , 2.70g / cm³ 3 , 2.72g / cm³ 3 , 2.75g / cm³ 3 , 2.8g / cm³ 3 , 2.85g / cm³ 3 or any value within a range between two of these values.

[0247] If the powder density of the active cathode material is in the above range at 30000N, the energy density of the battery cell can be increased; and since the active cathode material can be stacked more densely in the cathode film layer, the particle-to-particle contact resistance is lower, which can further reduce the resistance of the electrode foil, thereby reducing heat generation and improving the cycle performance of the battery cell at high energy density.

[0248] In the embodiment of the present application, the powder density of the material is a value known in the art and can be tested using methods and equipment known in practice, based on the test standard GB / T24533-2009. For example, a certain quantity of the active cathode material is taken as a sample and placed in a mold with a base area of ​​1.327 cm². 2The powder is placed in an electronic pressure testing device UTM7305, subjected to a pressure of 3000kg (equivalent to 30000N), held for 30 seconds, then depressurized and held for 10 seconds, and then the powder density of the active cathode material under the force of 30000 N is recorded and calculated.

[0249] In some embodiments, the density of the cathode film layer at a 100% state of charge (SOC) of the battery cell is 2.5 g / cm³. 3 up to 2.8g / cm³ 3 For example, the density of the cathode film layer at a 100% state of charge (SOC) of the battery cell is 2.5 g / cm³. 3 , 2.52 g / cm³ 3 , 2.55 g / cm³ 3 , 2.56 g / cm³ 3 , 2.57 g / cm³ 3 , 2.58 g / cm³ 3 , 2.60 g / cm³ 3 , 2.62 g / cm³ 3 , 2.65 g / cm³ 3 , 2.68 g / cm³ 3 , 2.70 g / cm³ 3 , 2.75 g / cm³ 3 , 2.8 g / cm³ 3or any value within a range between two of these values.

[0250] If the pressure density of the cathode film layer is in the above range, the energy density of the battery cell can be increased; and since the active anode material in the anode film layer can be stacked more densely, the particle-to-particle contact resistance is lower, which can further reduce the resistance of the electrode foil, thereby reducing heat generation during fast charging and improving the cycle performance of the battery cell at high energy density.

[0251] In some embodiments, the one-sided coating weight of the cathode film layer is 200 mg / 1540.25 mm². 2 up to 350 mg / 1540.25 mm 2 , for example 200 mg / 1540.25 mm², 210 mg / 1540.25 mm² 2 , 220 mg / 1540.25 mm 2 , 230 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2, 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 or any value within a range between two of these values.

[0252] If the one-sided coating weight of the cathode film layer is within the above range, the heat generation per unit area of ​​the cathode film is not too high, and the cycle performance of the battery cell at high energy density is improved.

[0253] In the embodiment of the present application, the density of the cathode film layer at a 100% state of charge (SOC) of the battery cell can be tested using the following method. The cathode foil is removed from a battery cell, and the density of the cathode foil is determined, for example, by taking a single-sided coated cathode foil (in the case of a double-sided coated electrode foil, the cathode film layer on one side can be wiped first), punching and cutting it into a small disc with an area of ​​S1, weighing it, recording it as M1, and measuring its thickness as H1. Then, the cathode film layer of the cathode foil, which was weighed as described above, is wiped, and the weight of the cathode collector is weighed and recorded as M0, and its thickness H0 is measured.The one-sided coating weight of the cathode film layer = (weight of the cathode foil M1 - weight of the cathode collector M0) / S1, the thickness of the cathode film layer = thickness H1 of the cathode foil - thickness H0 of the cathode collector, and the pressure density of the cathode film layer = the one-sided coating weight of the cathode film layer / thickness of the cathode film layer.

[0254] In some embodiments, the cathode film layer optionally further comprises a conductive cathode material. The embodiments of the present application do not specifically restrict the type of conductive cathode material, and by way of example, the conductive cathode material comprises one or more of the following: superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass fraction of the conductive cathode material, based on the mass of the cathode film layer, is ≤5%.

[0255] In some embodiments, the cathode film layer optionally comprises a cathode binder. The embodiments of the present application do not expressly restrict the type of cathode binder; for example, the cathode binder may comprise one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorine-containing acrylate resins. In some embodiments, the mass fraction of the cathode binder, based on the mass of the cathode film layer, is ≤5%.

[0256] In some embodiments, the cathode collector can be a metal foil or a composite collector. Examples of the metal foil include one or more sheets of aluminum, aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. The composite collector can comprise a polymer base layer and a metallic material layer formed on at least one surface of the polymer base layer. For example, the metallic material in the metallic material layer can include one or more sheets of aluminum, aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. For example, the polymer base layer can comprise one or more sheets of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0257] The cathode film layer is typically produced by applying a cathode slurry to the cathode collector, drying, and cold pressing. The cathode slurry is usually prepared by dispersing the active cathode material, an optional conductive agent, an optional binder, and other components in a solvent and mixing thoroughly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

[0258] In some embodiments, the thickness of the cathode collector is 10 µm to 15 µm, for example 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, or any value in a range between two of these values. When the thickness of the cathode collector is within the above range, the thickness of the cathode collector is reduced, which contributes to an improvement in the volumetric energy density of the battery cell.

[0259] The cathode foil does not preclude additional functional layers besides the cathode film layer. In some embodiments, the cathode foil in one embodiment of the present application further comprises a conductive cathode layer, which is provided between the cathode collector and the cathode film layer and is provided on the surface of the cathode collector. In some other embodiments, the cathode foil in one embodiment of the present application further comprises a protective layer that covers the surface of the cathode film layer.

[0260] In some embodiments, the cathode foil further comprises a conductive cathode layer located between the cathode film layer and the cathode collector. The conductive cathode layer can further improve the conductivity of the cathode foil, reduce heat generation from the anode foil, and thus reduce the heat generation of the battery cell.

[0261] In some embodiments, the thickness of the conductive cathode layer is 0.5 µm to 2 µm. For example, the thickness of the conductive cathode layer can be 0.5 µm, 0.8 µm, 1 µm, 1.2 µm, 1.5 µm, 1.6 µm, 1.8 µm, 2 µm, or any value in a range between two of these values.

[0262] If the thickness of the conductive cathode layer is in the above range, the conductivity of the cathode foil can be further improved, the heat generation of the cathode foil can be reduced, and thus the heat generation of the battery cell can be reduced, which improves the fast charging performance and the cycle performance at high battery cell temperatures and high energy density.

[0263] In the embodiment of the present application, the thickness of the conductive cathode layer has a meaning known in the art, such that it can be tested using devices and methods known in the art, such as tomography of the cathode foil for direct measurement of the thickness of the conductive cathode layer.

[0264] In some embodiments, the conductive cathode layer comprises one or more conductive cathode media and cathode binder media.

[0265] Optionally, the conductive cathode compound has a mass fraction of 30% to 50% in the conductive cathode layer. For example, the mass fraction of the conductive cathode compound is 30%, 35%, 40%, 45%, 50%, or any value in a range between two of these values.

[0266] For example, the conductive cathode material of the conductive cathode layer comprises one or more of the following: superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive cathode material in the conductive cathode layer can improve the electrical conductivity of the conductive cathode layer, thereby increasing the electrical conductivity of the cathode foil and reducing heat generation in the battery cell.

[0267] Optionally, the mass fraction of the cathode binder is 50% to 70% in the conductive anode layer. For example, it can be 50%, 60%, 65%, 70%, or any value in a range between two of these values.

[0268] For example, the cathode binder in the conductive cathode layer comprises one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resin. The cathode binder in the conductive cathode layer can improve the bonding performance between the cathode collector and the cathode film layer and increase the structural stability of the cathode film. [Separator]

[0269] In the embodiments of the present application, the separator is arranged between the cathode foil and the anode foil in order to isolate the cathode foil and the anode foil.

[0270] In some embodiments, the porosity of the separator is 20% to 70%, optionally 35% to 60%. For example, the porosity of the separator is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any value in a range between two of these values.

[0271] If the porosity of the separator in the embodiment of the present application is in the above range, the migration capability of lithium ions in the separator can be improved, and the internal resistance of the battery cell can be further reduced, thereby decreasing heat generation, which improves the fast charging performance and cycle performance at high temperatures of battery cells at high energy density.

[0272] In this application, porosity refers to the percentage of the separator's pore volume that occupies the total volume of the separator. The porosity can be tested according to standard GB / T 36363-2018, Polyolefin separators for battery cells. It should be noted that the actual test procedure may deviate slightly from the standard due to differences in testing equipment, testing errors, and a minor deviation from the standard procedure itself, in order to minimize the impact on the porosity test results and obtain a more accurate test value.

[0273] In some embodiments, the thickness of the separator is 5 µm to 12 µm. For example, the thickness of the separator is 5 µm, 5.5 µm, 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, or any value in a range between two of these values.

[0274] If the separator thickness is within the range above, the migration path of the lithium ions in the separator is shorter, and the internal resistance of the battery cell can be further reduced, thereby decreasing heat generation, which improves fast charging performance and cycle performance at high temperatures of high energy density battery cells.

[0275] In the embodiment of the present application, the separator comprises a base film with a porous structure.

[0276] Optionally, the porosity of the base film is 20% to 70%, optionally 35% to 60%.

[0277] In some embodiments, the base film comprises one or more layers of glass fiber, nonwoven fabric, or polyolefin. The base film can be a single-layer film or a multi-layer composite film without any particular restriction. If the base film is a multi-layer composite film, the materials of the layers can be the same or different without any particular restriction.

[0278] Optionally, the polyolefin can comprise one or more of polyethylene, polypropylene, and polyvinylidene fluoride.

[0279] In the embodiment of the present application, the separator can be a base film; optionally, the separator further comprises a functional layer provided on at least one side of the base film, and the functional layer can comprise inorganic particles to improve the heat resistance of the separator. Optionally, the functional layer is provided on both sides of the base film.

[0280] In some embodiments, the functional layer comprises a first functional layer and a second functional layer, wherein the first functional layer is located on one side of the base film, the first functional layer comprising first inorganic particles, while the second functional layer is located on the other side of the base film. The second functional layer comprises composite particles, the composite particles comprising second inorganic particles and a plurality of non-fluorinated polymer particles, the second inorganic particles being bound to a surface of the non-fluorinated polymer particles and / or dispersed within the non-fluorinated polymer particles.

[0281] The first functional layer and the second functional layer exhibit better heat resistance, which can improve the heat resistance of the separator.

[0282] Optionally, the first functional layer may include a binder, which may optionally include one or more fluorinated binders or a binder made of polyacrylic acid, such as polyvinylidene fluoride.

[0283] Optionally, the first inorganic particles include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These initial inorganic particles can increase the heat resistance of the first functional layer.

[0284] Optionally, the first inorganic particles have an average particle size of 5 nm to 100 nm, optionally 10 nm to 100 nm, optionally 5 nm to 20 nm. For example, the average particle size of the second inorganic particles is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or any value in the range between any two of these values. If the average particle size of the first inorganic particles is within the above range, it is advantageous to improve the heat resistance and bulk modulus of the composite particles.

[0285] In the embodiment of the present application, the meaning of the base film thickness is one known in the art and can be tested using equipment and methods known in the art. For example, a newly manufactured separator can be taken as a sample, or a battery cell that has been discharged (discharged to a lower cutoff voltage so that the state of charge of the battery is approximately 0% SOC) can be disassembled in reverse. The separator was extracted from the battery cell and dried as a sample. The separator was then cut into a cross-section using an ion beam cutter, and subsequently, the thickness of the separator and its individual layer sections were measured using a scanning electron microscope.

[0286] Non-fluorinated polymer particles in the second functional layer mean that the polymer is a non-fluorinated polymer; for example, the non-fluorinated polymer particles consist of acrylate copolymers. Optionally, the acrylate copolymer comprises an acrylate-acrylonitrile-acrylamide-propylene copolymer, and the acrylate copolymer has excellent bonding properties and high bond stability to the base film. The molar ratio of the individual monomers in the copolymer can be any ratio, such as 35%:30%:15%:20%, or 40%:20%:10%:30%, or 45%:15%:20%:20%, and so on.

[0287] The second inorganic particles in the composite particles make it less likely that the non-fluorinated polymer particles will bond together due to the high-temperature treatment in the granulation process, so that the composite particles have pores, which promotes the transfer of lithium ions and improves the ionic conductivity of the separator. Furthermore, the second inorganic particles can improve the bulk modulus of the composite particles, so that the composite particles are not easily deformed during the charging and discharging process, making the structure of the separator more stable. This can improve the kinetic performance of the battery cell and enhance fast-charging performance.Optionally, the second functional layer is positioned closer to the anode foil compared to the first functional layer. Since the composite particles are not easily deformed, the separator essentially does not cause any side effects such as extrusion on the anode foil, thus ensuring stable kinetic performance of the anode foil. Accordingly, the first functional layer is positioned close to the anode foil.

[0288] Optionally, the second inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide; optionally, the second inorganic particles may include silicon oxide. The above-mentioned second inorganic particles can increase the heat resistance of the second functional layer and interact with the non-fluorinated polymer to form composite particles, further improving the cycle stability and kinetic performance of the separator and enhancing the cycle performance and fast-charging performance of the battery cell.

[0289] The second inorganic particles have an average particle size of 5 nm–100 nm, optionally 10 nm–100 nm, or optionally 5 nm–20 nm. For example, the average particle size of the second inorganic particles could be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or any value in the range between any two of these values. If the average particle size of the second inorganic particles is within the above range, it is advantageous to improve the heat resistance and bulk modulus of the composite particles.

[0290] In the embodiment of the present application, the average particle size of the second inorganic particles is in the sense known in the art and can be determined using equipment and methods known in the art, e.g., after receiving the separator and drying it as a sample, the separator is cut with an ion beam cutter to form a cross-section, then the particle size of the second inorganic particles in the separator is measured using a scanning electron microscope, and a plurality of, e.g., 50, particle sizes of the second inorganic particles are measured, and an average value is calculated as the average particle size of the second inorganic particles.

[0291] In some embodiments, the cathode foil, the separator and the anode foil can be assembled into an electrode assembly by a winding process and / or a stacking process.

[0292] Fig. 1 and Fig. Figure 2 shows a schematic representation of the structure of the battery cell.

[0293] In some embodiments, the battery cell 7 can include an outer casing 20.

[0294] The outer housing 20 can have various structures, such as cylindrical, rectangular, and the like. The shape of the outer housing 20 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, the outer housing 20 can be chosen as a cylindrical structure. If the electrode assembly 10 has a rectangular structure, the outer housing 20 can be chosen as a rectangular structure. Optionally, the electrode assembly 10 can have a rectangular structure.

[0295] The outer casing 20 can be made of various materials, e.g., copper, iron, aluminum, stainless steel, aluminum alloys, etc., and the present application does not impose any particular restrictions in this regard. Optionally, the inner wall of the outer casing 20 can also have an insulating layer, wherein the insulating layer is capable of separating the outer casing 20 and the electrode assembly 10. The material of the insulating layer can be selected from materials commonly used in the art, and no particular restrictions are imposed here.

[0296] The electrode assembly 10 housed in the outer casing 20 can be one or more.

[0297] In some embodiments, the outer housing 20 comprises a housing body 21 and an end cap 22, wherein the housing body 21 has an opening, the end cap 22 closes the opening, and the housing body 21 accommodates the electrode assembly 10 and the electrolyte solution.

[0298] In some embodiments, the material of the housing body 21 comprises one or more of the following materials: aluminum, steel, optionally steel, wherein steel has higher mechanical strength, is less prone to deformation, and can improve the reliability of the battery cell's use and its cycle performance. Optionally, steel constitutes the largest proportion of the material in the housing body 21.

[0299] Optionally, the thickness of the casing 21 is between 0.1 mm and 0.5 mm. For example, the thickness of the casing 21 can be 0.1 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.5 mm, or any value in the range between these two values. If the thickness of the casing 21 is within the above range, the mechanical strength of the casing 21 is higher, which can improve the reliability of use and the cycle performance of the battery cell 7. Furthermore, the casing 21 occupies less space, and the internal volume of the casing 21 is larger, which is beneficial for improving the energy density of the battery cell 7.

[0300] Optionally, the housing body 21 has a rectangular structure, comprising two opposing first side walls 211 and two opposing second side walls 212, the two first side walls 211 being connected to each other by the second side walls 212, the first side walls 211 having a cross-sectional area perpendicular to their own thickness direction that is larger than the cross-sectional area of ​​the second side walls 212 perpendicular to their own thickness direction, the thickness of the first side walls 211 being 0.1 mm to 0.5 mm, optionally 0.2 mm to 0.35 mm.

[0301] The first side wall 211 has a relatively large cross-sectional area and if its thickness is in the above range, the mechanical strength of the first side wall 211 is higher, which can improve the reliability of use and the cycle performance of the battery cell 7, and the housing body 21 takes up less space, and the interior of the housing body 21 is larger, which is conducive to improving the energy density of the battery cell 7.

[0302] Next, the electrode assembly 10 is presented as an example of a stacked foil structure,

[0303] The electrode assembly 10 comprises a cathode foil 11, an anode foil 12 and a separator 13, which are arranged in a cascade along a thickness direction X of the battery cell 7.

[0304] As in Fig. 2 and Fig.Figure 3 shows that the electrode assembly 10 comprises a main body section 14, a cathode tab 111, and an anode tab 121, with the cathode tab 111 and the anode tab 121 respectively projecting from the main body section 14. The cathode tab 111 and the anode tab 121 are used to draw current from the main body section 14.

[0305] The section in the cathode foil 11 that is not coated with an active material layer is the cathode flap 111, the active material that is coated onto the cathode collector in the cathode foil 11 forms a cathode film layer, and the cathode film layer and the cathode collector that is coated with the active material are part of the main body section 14.

[0306] The section in the anode foil 12 that is not coated with an active material layer is the anode tab 121, the active material that is coated on the anode collector of the anode foil 12 forms an anode film layer, and the anode film layer and the anode collector that is coated with the active material are part of the main body section 14.

[0307] The main body section 14 can also include a separator 13, the separator 13 being arranged between the cathode foil and the anode foil.

[0308] The cathode tab 111 and the anode tab 121 can extend from the same side of the main body section 14, or they can extend from opposite sides. Fig. 2 and Fig.Figure 3 shows that the cathode tabs 111 and the anode tabs 121 are arranged on the same side, e.g. the cathode tabs 111 and the anode tabs 121 are arranged at the same end in the longitudinal direction Z of the electrode assembly 10.

[0309] Naturally, the cathode tab 111 and the anode tab 121 can extend from opposite sides. For example, the cathode tab 111 and the anode tab 121 are each arranged at the two ends along the longitudinal direction of the electrode assembly 10.

[0310] In some embodiments, the cathode tab 111 is connected to at least one side of the cathode collector along a longitudinal direction Z of the battery cell 7, wherein the anode tab 121 is connected to at least one side of the anode collector along the longitudinal direction Z of the battery cell.

[0311] As in Fig.As shown in Figure 4, for example, the cathode tab 111 is connected to one side of the cathode collector 112 along the longitudinal direction Z of the battery cell 7.

[0312] As in Fig. As shown in Figure 5, for example, the cathode tab 111 is connected to the two sides of the cathode collector 112 along the longitudinal direction Z of the battery cell 7.

[0313] As in Fig. As shown in Figure 6, for example, the anode tab 121 is connected to one side of the anode collector 122 along the longitudinal direction Z of the battery cell 7.

[0314] As in Fig. As shown in Figure 7, for example, the anode tab 121 is connected to the two sides of the anode collector 122 along the longitudinal direction Z of the battery cell 7.

[0315] As in Fig.Figure 8 shows that in some embodiments the cathode tab 111 is connected to at least one side of the cathode collector 112 along a longitudinal direction Z, wherein the anode tab 121 is connected to at least one side of the anode collector 122 along the longitudinal direction Z; wherein along the longitudinal direction Z of the battery cell 7 the dimension of the anode film layer 123 is larger than the dimension of the cathode film layer 113, and wherein the difference between the dimension of the anode film layer 123 and the dimension of the cathode film layer 113 is OH1; wherein along the lateral direction Y of the battery cell 7 the dimension of the anode film layer 123 is larger than the dimension of the cathode film layer 113, and wherein the difference between the dimension of the anode film layer 123 and the dimension of the cathode film layer 113 is OH2; where OH1 is larger than OH2.

[0316] The anode tab 121 is located on at least one side of the anode collector 122 along the longitudinal direction Z. The current density in the junction area of ​​the anode tab 121 and the anode collector 122 increases significantly, and lithium precipitation and other problems are more likely to occur in this area. In the embodiment of the present application, OH1 is larger than OH2, so that the ability of the area near the anode film layer 123 to absorb lithium ions in the longitudinal direction Z is greater, and in particular, the ability of the anode film layer 123 to absorb lithium ions in the area near the anode tab 121 can be improved to reduce the risk of lithium precipitation and improve the reliability of the battery cell 7.

[0317] For example, OH1 is between 1 mm and 4 mm, e.g., 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, 3.5 mm, 4 mm, or any value in a range between any two of these values. Along the longitudinal direction Z, the anode film layer 123 overhangs the cathode film layer 113 on both sides, with each side exceeding OH1 / 2, i.e., half the dimension of OH1, OH1 / 2 as shown in Fig. 8 shown.

[0318] For example, OH2 is between 1 mm and 3 mm, e.g., 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, or any value in a range between any two of these values. Along the lateral direction Y, the anode film layer 123 overhangs the cathode film layer 113 on both sides, with each side exceeding OH2 / 2, i.e., half the dimension of OH2, OH2 / 2 as shown in Fig. 8 shown.

[0319] In some other embodiments, the cathode tab 111 is connected to at least one side of the cathode collector 112 along a lateral direction Y, wherein the anode tab 121 is connected to at least one side of the anode collector 122 along the lateral direction Y.

[0320] Optionally, the number of cathode lugs 111 arranged on the same side of the main body section 14 is at least one, optionally at least two, wherein the at least two cathode lugs 111 can increase the overflow capacity of the cathode lugs 111.

[0321] Optionally, the number of anode lugs 121 arranged on the same side of the main body section 14 is at least one, optionally at least two, wherein the at least two anode lugs 121 can increase the overflow capacity of the anode lugs 121.

[0322] In some embodiments, the battery cell 7 further comprises a cathode terminal 31, wherein the cathode terminal 31 is arranged on the outer housing 20, which may be arranged on the housing body 21 or the end cap 22.

[0323] The cathode terminal 31 is electrically connected to the cathode tab 111. Optionally, the cathode terminal 31 and the cathode tab 111 are welded together, and the cathode terminal 31 and the cathode tab 111 can be connected by an adapter or not. Optionally, the cathode terminal 31 and the cathode tab 111 are not connected by an adapter, i.e., the cathode terminal 31 and the cathode tab 111 are welded directly together, which can reduce the resistance at the connection and contribute to reducing the overall internal resistance of the battery cell 7.

[0324] In some embodiments, the battery cell 7 further comprises an anode terminal 32, wherein the anode terminal 32 is arranged on the outer housing 20, which may be arranged on the housing body 21 or the end cap 22.

[0325] The anode terminal 32 is electrically connected to the anode tab 121. Optionally, the anode terminal 32 and the anode tab 121 are welded together, and the anode terminal 32 and the anode tab 121 can be connected by an adapter or not. Optionally, the anode terminal 32 and the anode tab 121 are not connected by an adapter, i.e., the anode terminal 32 and the anode tab 121 are welded directly together, which can reduce the resistance at the connection and contribute to reducing the overall internal resistance of the battery cell 7.

[0326] Optionally, the number of cathode terminals 31 arranged on the same side of the main body section 14 is at least one, optionally at least two, wherein the at least two cathode terminals 31 can increase the overflow capacity of the cathode terminals 31.

[0327] Optionally, the number of anode terminals 32 arranged on the same side of the main body section 14 is at least one, optionally at least two, wherein the at least two anode terminals 32 can increase the overflow capacity of the anode terminals 32.

[0328] As in Fig. As shown in Figure 9, in the embodiments of the present application the battery cells 7 can be assembled to form a battery module 6, and the number of battery cells 7 contained in the battery module 6 can be one or a plurality, the exact number being adjustable depending on the application and capacity of the battery module 6.

[0329] In the case of a plurality of battery cells 7, the plurality of battery cells 7 can be connected in series, parallel, or in a mixed circuit, where mixed circuit means that the plurality of battery cells 7 are connected in series and parallel. The multiple battery cells 7 can be connected directly in series, parallel, or in a mixed circuit, and then the whole formed by the multiple battery cells 7 is received in a receiving section of the battery module 6; of course, it is also possible that the multiple battery cells 7 are first connected in series, parallel, or in a mixed circuit to form a battery module 6, and the multiple battery modules 6 are then connected in series, parallel, or in a mixed circuit to form a whole and received in the receiving section.Optionally, the battery module 6 can also include a recording section with a recording space, and the multitude of battery cells 7 are recorded in the recording space.

[0330] The multiple battery cells 7 in the battery module 6 can be electrically connected to one another by means of a converging component to enable a parallel, series, or mixed connection of the multiple battery cells 7 in the battery module 6. The converging components can be one or more, with each converging component serving to electrically connect at least two battery cells 7.

[0331] As in Fig.Figure 10 shows that in some embodiments, the battery modules 6 described above can also be assembled into a battery pack 2, wherein the number of battery modules 6 contained in the battery pack 2 is adjustable depending on the application and capacity of the battery pack. The battery device can be a battery module 6, a battery pack 2, or a battery cell 7, wherein the battery cell 7 can be the smallest unit of the battery device.

[0332] The battery pack 2 can comprise a box 5 and a plurality of battery modules 6 arranged within the box 5. The box 5 consists of a first box section 5a and a second box section 5b, wherein the box 5 has a receiving space 5c and the first box section 5a serves to cover the second box section 5b and form an enclosed space for receiving the battery module 6. The plurality of battery modules 6 can be arranged within the box 5 in any configuration.

[0333] The first box section 5a and the second box section 5b cover each other, and together they define a receiving space 5c for the battery cells. The second box section 5b can be a hollow structure with an opening at one end, the first box section 5a is a plate-shaped structure, and the first box section 5a covers one opening side of the second box section 5b to form a box 5 with the receiving space 5c. Alternatively, both the first box section 5a and the second box section 5b can be hollow structures with an opening on one side, with the opening side of the first box section 5a covering the opening side of the second box section 5b to form the box with a receiving space 5c. Of course, the first box section 5a and the second box section 5b can have different structures, such as...cylindrical, rectangular, and the like.

[0334] To improve the sealing of the first box section 5a and the second box section 5b when they are connected, a sealing element, such as a sealant, a sealing ring and the like, may also be provided between the first box section 5a and the second box section 5b.

[0335] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be referred to as the upper box lid, and the second box section 5b can also be referred to as the lower box body. Power-consuming device

[0336] A second aspect of an embodiment of the present application provides a power-consuming device, wherein the power-consuming device comprises a battery device of an embodiment of the present application, such as a battery cell, a battery module, or a battery pack. The battery cell, battery module, or battery pack can be used as a power supply for the power-consuming device or as an energy storage unit for the power-consuming device. The power-consuming devices may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, power tools, and the like.The vehicle may be a fuel-powered vehicle, a gas-powered vehicle, or a new energy vehicle; the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or a programmable vehicle, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, e.g., game consoles, electric car toys, electric boat toys, and electric airplane toys, etc. Power tools include power tools for metal cutting, grinding tools, power tools for assembly, and power tools for railways, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, and the like.The embodiments of the present application do not provide for any special restrictions on the above power-consuming device.

[0337] Depending on requirements, the power-consuming device can be a battery cell, a battery module or a battery pack.

[0338] Fig. Figure 11 shows a schematic representation of the power-consuming device 1 as an example. The power-consuming device 1 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this power-consuming device 1, a battery pack or battery module can be used.

[0339] The power-consuming device 1 is equipped internally with a battery pack 2. The battery pack 2 can be located on the underside, at the top, or at the rear of the power-consuming device 1. The battery pack 2 can be used to supply power to the power-consuming device 1; for example, the battery pack 2 can be used as the operating power source for the power-consuming device 1 and can also be used as a drive power source for the power-consuming device 1, instead of or partially instead of heating oil or natural gas to provide drive power for the power-consuming device 1.

[0340] The power-consuming device 1 can further comprise a control unit 3 and a motor 4, wherein the control unit 3 serves to control the battery pack 2 in order to supply the motor 4 with energy, e.g. for the operating energy requirements of the power-consuming device 1 for starting, navigating and driving.

[0341] Another example of such a power-consuming device is a mobile phone, a tablet, a laptop, etc. The power-consuming device usually needs to be light and thin and can use a battery cell as its power source. Example of implementation

[0342] The following embodiments describe in more detail what is disclosed in the exemplary embodiments of the present application, and these exemplary embodiments serve only for illustration, since various modifications and variations within the scope of disclosure of the exemplary embodiments of the present application will be obvious to the person skilled in the art. Unless otherwise stated, all parts, percentages, and ratios given in the following exemplary embodiments are based on mass counts, and all reagents used in the exemplary embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the equipment used in the exemplary embodiments is commercially available. Example 11. Production of the cathode foil:

[0343] The cathode foil comprises a cathode collector, a cathode film layer and a conductive cathode layer, wherein the cathode film layer is arranged on both sides of the cathode collector, wherein the conductive cathode layer is located between the cathode collector and the cathode film layer, wherein the cathode collector consists of an aluminum foil with a thickness of 13 µm.

[0344] The conductive cathode layer on the cathode collector is a film layer formed by mixing a conductive cathode agent of superconducting carbon, a cathode binder of polyvinylidene fluoride (PVDF) and a solvent of N-methylpyrrolidone (NMP), and obtained by coating it onto the surface of the cathode collector and after drying. The thickness is 1 µm, and the mass fraction of the conductive cathode agent in the conductive cathode layer is 40%, while the mass fraction of the cathode binder is 60%.

[0345] The cathode film layer comprises a cathode slurry (whose solvent is N-methylpyrrolidone, NMP) uniformly coated onto the surface of the conductive cathode layer. The film layer is formed after drying and cold pressing, and the cathode film layer comprises an active cathode material, a binder (polyvinylidene fluoride, PVDF), and a conductive agent (acetylene black) in a mass ratio of 97:2:1.

[0346] The active cathode material comprises lithium iron phosphate particles and a cathode coating layer, the cathode coating layer is coated on the surface of the lithium iron phosphate particles, the cathode coating layer comprises lithium titanium iron phosphate Li2FeTi(PO4)3 and carbon, and the mass content of the carbon element is 1.12%.

[0347] The powder density of the active cathode material is 2.75 g / cm³ at 30,000 N. 3 .

[0348] The one-sided coating weight of the cathode film layer is 323 mg / 1540.25 mm². 2 . 2. Production of the anode foil:

[0349] The anode foil comprises an anode collector, a conductive anode layer on the anode collector and an anode film layer, and the anode collector is a copper foil with a thickness of 6 µm;

[0350] The conductive anode layer on the anode collector is a film layer formed by mixing a conductive anode compound of superconducting carbon, an anode binder of styrene-butadiene rubber (SBR), a thickening agent of sodium carboxymethylcellulose (CMC-Na), and a solvent, water. This mixture is applied to the surface of the anode collector and, after drying, is obtained by coating it. The thickness is 1 µm. The mass fraction of the conductive anode compound in the conductive anode layer is 35%, the mass fraction of the anode binder in the conductive anode layer is 60%, and the mass fraction of the thickening agent in the conductive anode layer is 5%.

[0351] The anode film layer comprises a first anode film layer and a second anode film layer, wherein the first anode film layer is located on the surface of the conductive anode layer and the second anode film layer is located on the surface of the first anode film layer;

[0352] The first anode film layer is a film layer formed by uniformly coating the surface of the conductive anode layer with a first anode slurry (whose solvent is water) after drying and cold pressing. The first anode film layer comprises graphite particles, silicon-carbon material, a conductive agent (acetylene black), a binder (styrene-butadiene rubber), and a thickening agent (sodium carboxymethylcellulose) in a mass ratio of 94:3.5:0.5:1:1. The silicon-carbon material is silicon carbide, the mass content of silicon element in the silicon-carbon material is 48%, the Dv50 of the silicon-carbon material is 8.8 µm, and the Dv50 of the graphite particles is 11.3 µm.The graphite particles comprise graphite body particles and an anode coating layer that is coated on the surface of the graphite body particles; the graphite body particles comprise secondary particles; the anode coating layer comprises carbon elements; the mass content of the carbon element is 2.5%; and the graphite body particles are artificial graphite.

[0353] The second anode film layer is a film layer formed by uniformly coating a second anode slurry (the solvent is water) onto the surface of the first anode film layer after drying and cold pressing. The second anode film layer comprises graphite particles, a conductive agent (acetylene black), a binder (styrene-butadiene rubber), and a thickening agent (sodium carboxymethylcellulose) in a mass ratio of 96.5:0.5:2:1. The Dv50 of the graphite particles is 11.3 µm. The graphite particles comprise graphite body particles and an anode coating layer applied to the surface of the graphite body particles. The graphite body particles include secondary particles. The anode coating layer comprises carbon elements with a mass content of 2.5%. The graphite body particles are synthetic graphite.

[0354] The thickness ratio of the first anode film layer and the second anode film layer is 1:1. The mass fraction of the silicon element in the anode film layer is 0.84%.

[0355] The one-sided coating weight of the anode film layer is 130 mg / 1540.25 mm². 2 . 3. Separator

[0356] The separator comprises a base film and a functional layer arranged on both sides of the base film, wherein the base film comprises 7 µm polyethylene PE and the separator has a porosity of 42%;

[0357] The functional layer comprises a first functional layer and a second functional layer, wherein the first functional layer is a film layer formed by coating aluminium oxide particles and a binder polyvinylidene fluoride on one side of the base film with a thickness of 1 µm, and the average particle size of the aluminium oxide particles is 10 nm;

[0358] The second functional layer is a film layer formed by coating composite particles of polyacrylate and silicon oxide particles dispersed on the polyacrylate on the other side of the base film, with a thickness of 1 µm, the average particle size of the silicon oxide particles is 10 nm. 4. Preparation of the electrolyte solution

[0359] The electrolyte solution comprises an organic solvent, an electrolyte lithium salt, and an additive.

[0360] After mixing the components of each organic solvent, the lithium electrolyte salt and the additive are added and the mixture is prepared as an electrolyte solution.

[0361] The organic solvent comprises ethylene carbonate EC with a mass fraction of 27.3%, ethyl acetate with a mass fraction of 22%, methyl acetate with a mass fraction of 19.7% and dimethyl carbonate DMC with a mass fraction of 6.7%, and the mass fraction of each component in the solvent is calculated on the basis of the total mass of the electrolyte solution;

[0362] Based on the total mass of the electrolyte solution, the additive comprises vinylidene carbonate VC, fluoroethylene carbonate FEC, vinylidene sulfite ES and lithium difluorooxalate borate LiDFOB in a mass ratio of 4:2.5:2:0.8;

[0363] The lithium electrolyte salt comprises lithium hexafluorophosphate LiPF6 with a mass content of 15%. 5. Manufacturing the battery cell

[0364] The cathode foil, separator, and anode foil are stacked in a row, with the separator positioned between the cathode foil and the anode foil to insulate them, thus creating a stacked electrode assembly. The electrode assembly is then placed into the outer casing, which is equipped with a cathode clamp and an anode clamp. After baking, the electrolyte solution is injected, and then after vacuum encapsulation, standing, forming, shaping, and other processes, a battery cell is obtained. The battery cell has a liquid injection factor of 2.5 g / Ah.

[0365] The battery cell has a density of 2.75 / cm³. 3 the cathode film layer at 100% SOC and a pressing density of 1.25g / cm³ 3 of the anode film layer at 100% SOC.

[0366] The outer casing comprises an aluminum housing with a rectangular structure, and the thickness of the large-area housing body of the battery cell is 0.3 mm, and the large-area housing body of the battery cell is the thickness of a first side wall of the housing body;

[0367] wherein the cathode film layer has a dimension of 630 mm along a longitudinal direction of the battery cell, and OH1 is 4 mm;

[0368] where the dimension of the cathode film layer along the width direction of the battery cell is 95 mm and OH2 is 3 mm.

[0369] The energy density of the battery cell is 453 Wh / L. Exemplary embodiment 2-1 and Exemplary embodiment 2-2

[0370] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the component and the mass content of the solvent are adjusted. Exemplary embodiment 3-1 to Exemplary embodiment 3-3

[0371] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the mass content of vinylidene carbonate is adjusted, and while the mass content of vinylidene carbonate changes, the mass content of dimethyl carbonate is adjusted in parallel. Exemplary embodiment 4-1 and Exemplary embodiment 4-2

[0372] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the mass content of vinylidene fluorocarbonate is adjusted, and while the mass content of vinylidene fluorocarbonate changes, the mass content of dimethyl carbonate is adjusted in parallel. Example 5

[0373] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the type of cyclic carbonate additive is adapted. Comparison example 1-1 and comparison example 1-2

[0374] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the component and the mass content of the solvent are adjusted. Comparative example 2-1 to Comparative example 2-3

[0375] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the mass fraction of vinylidene carbonate and vinylidene fluorocarbonate is adjusted, and while the mass fraction of vinylidene carbonate and vinylidene fluorocarbonate changes, the mass fraction of dimethyl carbonate is adjusted in parallel. Performance test 1. Volumetric energy density of battery cells

[0376] The battery cells of the exemplary embodiments and the comparative examples are stored at 25°C, charged to 3.65V at a constant current of 0.33C, then charged to 0.05C at a constant voltage of 3.65V and left to stand for 30 minutes, discharged to 2.0V at a constant current of 0.33C, and the discharge capacity at this time is recorded as A0, unit: Ah; The length, width, and height of the battery cell are measured with calipers, and the volume of the battery cell V0, unit: L, is calculated; the volumetric energy density of the battery cell VED=(A0×discharge platform voltage) / V0, unit: Wh / L. 2. Cycle performance of the battery cell

[0377] At 60°C, the battery cell is charged to the charging cutoff voltage of 3.6V at a constant current of 0.8C, then charged to the charging cutoff voltage of 3.65V at a constant current of 0.1C and left for 30 minutes; discharged to 3.1V at a constant current of 1C and left for 30 minutes. This is one charge / discharge cycle. Repeat the above charge / discharge cycle steps until the cycle capacity retention rate (i.e., Cn / C0 × 100%) reaches 70%, and record the number of cycles. The higher the number of cycles, the better the cycle performance of the battery cell.

[0378] The test results are listed in Table 1. Table 1 electrolyte solution Battery power Mass content of vinyl carbonate EC / % Linear ester solvent Mass content of the cyclic carbonate additive Number of cycles at 60°C Carboxylic acid ester solvents Dimethyl carbonate Total mass content / % Mass content of vinylidene carbonate VC / % Vinyl carbonate derivative Total mass content / % material Mass content / % Mass content / % material Mass content / % Example 1 27,30 Ethyl acetate 22Methyl acetate 19.7 41,7 6,7 48,4 4 FEC 2,5 6,5 1893 Example 2-1 20,0 Ethyl acetate 22Methyl acetate 19.7 41,7 14,0 55,7 4 FEC 2,5 6,5 1721 Example 2-2 40,0 Ethyl acetate 22Methyl acetate 13.7 35,7 0 35,7 4 FEC 2,5 6,5 1747 Example 3-1 27,30 Lthyl acetate 22Methyl acetate 19.7 41,7 8,7 50,4 2 FEC 2,5 4,5 1663 Example 3-2 27,30 41,7 5,7 47,4 5 FEC 2,5 7,5 1856 Example 3-3 27,30 41,7 11,2 52,9 1 FEC 1,0 2,0 1501 Example 4-1 27,30 41,7 7,7 49,4 4 FEC 1,5 5,5 1823 Example 4-2 27,30 41,7 5,2 47,4 4,5 FEC 3,5 8,0 1804 Example 5 27,30 41,7 6,7 48,4 4 DFEC 2,5 6,5 1725 Comparison example 1-1 10 41,7 24,0 65,7 4 FEC 2,5 6,5 537 Comparison example 1-2 50 Ethyl acetate 22Methyl acetate 3.7 25,7 / 25,7 4 FEC 2,5 6,5 712 Comparative example 2-1 27,30 Lthyl acetate 22Methyl acetate 19.7 41,7 11,7 53,4 1 FEC 0,5 1,5 216 Comparative example 2-2 27,30 41,7 11,7 53,4 1,5 FEC 0 1,5 233 Comparative example 2-3 27,30 41,7 3,2 44,9 5 FEC 5,0 10,0 958

[0379] In Table 1, Ethyl acetate 22 means that the mass content of ethyl acetate in the electrolyte solution is 22%; Methyl acetate 19.7 means that the mass content of methyl acetate in the electrolyte solution is 19.7%; Methyl acetate 13.7 means that the mass content of methyl acetate in the electrolyte solution is 13.7%; Methyl acetate 3.7 means that the mass content of methyl acetate in the electrolyte solution is 3.7%;

[0380] The amount of vinyl carbonate EC added in comparison example 1-1 is too low, the SEI film formed on the anode side cannot provide good protection for the active anode material, and the side reaction on the anode side is more violent, especially at high temperatures, and the degree of violent side reaction is higher, which worsens the cycle performance of the battery cell at high temperature.

[0381] The amount of vinyl carbonate EC added in comparison example 1-2 is too high, which makes the viscosity of the electrolyte solution too high, which is not conducive to uniform infiltration of the anode foil, increases the risk of lithium precipitation in the anode film layer and shortens the cycle life of the battery cell.

[0382] In the embodiments of the present application, the mass fraction of vinyl carbonate is specified within a reasonable range; for example, the mass fraction of embodiment 1, embodiment 2-1, and embodiment 2 is 20% to 40%. On the one hand, the vinyl carbonate is able to participate in the film-forming reaction of the SEI film on the anode side with the cyclic carbonate additive, effectively reduces the volume expansion on the anode side, effectively reduces the side reaction on the anode side, and improves the cycle performance of the battery cell. On the other hand, the viscosity of the electrolyte solution is not very high, which leads to uniform infiltration of the anode foil, reduces the risk of lithium precipitation on the surface of the anode film layer, and improves the cycle performance of the battery cell.

[0383] The mass fraction of the cyclic carbonate additive in comparison example 2-1 and in comparison example 2-2 is too low, the SEI film formed on the anode side cannot provide good protection for the active anode material, and the side reaction on the anode side is more violent, especially at high temperatures, and the degree of violent side reaction is higher, which degrades the cycle performance of the battery cell at high temperature.

[0384] In comparison example 2-3, the mass content of the cyclic carbonate additive is too high, which makes the impedance of the SEI film too high, which is not conducive to fast charging of the battery cell, and the risk of lithium precipitation of the anode film layer increases at the same current density, which shortens the cycle life of the battery cell.

[0385] In embodiments 3-1 to 3-3, the mass fraction of vinylene carbonate is regulated such that the mass fraction of the cyclic carbonate additive is within a suitable range, is able to participate synergistically in the film-forming reaction of the SEI film on the anode side with the vinylene carbonate, is able to effectively mitigate the volume expansion on the anode side, and is able to effectively mitigate the side reaction on the anode side and improve the cycle performance of the battery cell.

[0386] In embodiments 4-1 to 4-3, the mass fraction of fluorinated vinyl carbonate is regulated such that it remains within a suitable range, enabling it to participate synergistically in the film-forming reaction of the SEI film on the anode side with the vinyl carbonate, effectively mitigating volume expansion on the anode side, and effectively mitigating side reactions on the anode side, thereby improving the cycle performance of the battery cell. The high-temperature stability of fluorinated vinyl carbonate is poor, and with an increase in its mass fraction, partial decomposition may occur, which can reduce the protective effect on the anode side to some extent.

[0387] The use of vinyl carbonate derivatives from various materials, such as fluorinated vinyl carbonate and difluorinated vinyl carbonate, can effectively improve the cycle performance of the battery cell at high temperatures. Exemplary embodiment 6-1 and Exemplary embodiment 6-2

[0388] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the mass content of sulfur-containing additive is adjusted, and while the mass content of sulfur-containing additive changes, the mass content of dimethyl carbonate is adjusted in parallel. Exemplary embodiment 6-3 and Exemplary embodiment 6-4

[0389] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the mass content of lithium salt additive is adjusted, and while the mass content of lithium salt additive changes, the mass content of dimethyl carbonate is adjusted in parallel. The test results are listed in Table 2. Table 2 electrolyte solution Battery power Linear ester solvent Sulfur-containing additive Lithium salt-like additive Number of cycles at 60°C Carboxylic acid ester solvent mass content / % Dimethyl carbonate mass content / % Total mass content / % Mass content / % Mass content / % Example 6-1 41,70 8,20 49,9 0,5 0,80 1642 Example 6-2 41,70 7,40 49,1 1,3 0,80 1739 Example 6-3 41,70 7,30 49,0 2 0,20 1745 Example 6-4 41,70 6,90 48,6 2 0,60 1828

[0390] As can be seen from Table 2, In embodiments 6-1 and 6-2, the mass fraction of the sulfur-containing additive is adjusted, and the mass fraction of the sulfur-containing additive is 0.5% to 2.0%, which further optimizes the components of the SEI film, increases the protective effect on the anode side, mitigates the expansion of the silicon-based material, and improves the cycle performance of the battery cell at high temperatures. In embodiments 6-3 and 6-4, the mass fraction of the lithium salt-like additive is adjusted, and the mass fraction of the lithium salt-like additive is 0.2% to 1.0%, which further optimizes the components of the SEI film, increases the protective effect on the anode side, mitigates the expansion of the silicon-based material, and improves the cycle performance of the battery cell at high temperature. Exemplary embodiment 7-1 to Exemplary embodiment 7-3

[0391] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the mass content of the silicon element in the anode film layer is adjusted. Example 8

[0392] A battery cell is manufactured using a similar method to that in embodiment 1, but in contrast to embodiment 1, the type of material is adapted to be silicon-based. Example 9

[0393] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the manufacturing process of the anode foil is adapted; the anode film layer uses a single-layer film layer, in particular:

[0394] The anode film layer comprises a first anode film layer, wherein the anode film layer is located on the surface of the conductive anode layer;

[0395] The anode film layer is a film layer formed by uniformly coating an anode slurry (whose solvent is water) on the surface of the conductive cathode layer after drying and cold pressing. The first anode film layer comprises graphite particles, silicon-carbon material, a conductive agent (acetylene black), a binder (styrene-butadiene rubber), and a thickening agent (sodium carboxymethylcellulose) in a mass ratio of 95.75:1.75:0.5:1:1. The silicon-carbon material is silicon carbide, and the mass content of silicon in the silicon-carbon material is 48%. Example 10

[0396] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the manufacturing process of the anode foil is adapted, in particular the distribution position of the silicon-based material is adapted, wherein the silicon-based material is located on the first anode film layer and on the second anode film layer, in particular:

[0397] The anode film layer comprises a first anode film layer and a second anode film layer, wherein the first anode film layer is located on the surface of the conductive anode layer and the second anode film layer is located on the surface of the first anode film layer;

[0398] The first anode film layer is a film layer formed by uniformly coating the surface of the conductive cathode layer with a first anode slurry (whose solvent is water) after drying and cold pressing. The first anode film layer comprises graphite particles, silicon-carbon material, a conductive agent (acetylene black), a binder (styrene-butadiene rubber), and a thickening agent (sodium carboxymethylcellulose) in a mass ratio of 95.75:1.75:0.5:1:1. The silicon-carbon material is silicon carbide, and the mass content of silicon in the silicon-carbon material is 48%.

[0399] The second anode film layer is a film layer formed by uniformly coating a second anode slurry (whose solvent is water) on the surface of the first anode film layer after drying and cold pressing, and the second anode film layer comprises graphite particles, a conductive agent acetylene black, a binder styrene-butadiene rubber and a thickening agent sodium carboxymethylcellulose in a mass ratio of 95.75:1.75:0.5:1:1. Example 11

[0400] A battery cell is manufactured according to a similar process as in embodiment 1, and in contrast to embodiment 1, the manufacturing process of the anode foil is adapted, in particular the distribution position of the silicon-based material is adapted, wherein the silicon-based material is located on the second anode film layer, in particular:

[0401] The anode film layer comprises a first anode film layer and a second anode film layer, wherein the first anode film layer is located on the surface of the conductive anode layer and the second anode film layer is located on the surface of the first anode film layer;

[0402] The first anode film layer is a film layer formed by uniformly coating a first anode slurry (whose solvent is water) on the surface of the conductive anode layer after drying and cold pressing, and the first anode film layer comprises graphite particles, a conductive agent acetylene black, a binder styrene-butadiene rubber and a thickening agent sodium carboxymethylcellulose in a mass ratio of 96.5:0.5:2:1.

[0403] The second anode film layer is a film layer formed by uniformly coating a first anode slurry (whose solvent is water) onto the surface of the first anode film layer after drying and cold pressing. The second anode film layer comprises graphite particles, silicon-carbon material, a conductive agent (acetylene black), a binder (styrene-butadiene rubber), and a thickening agent (sodium carboxymethylcellulose) in a mass ratio of 94:3.5:0.5:1:1. The silicon-carbon material is silicon carbide, and the mass content of silicon in the silicon-carbon material is 48%. The test results are listed in Table 3. Table 3 Anode film layer of the anode foil Battery power Nickel-based material Mass content of the silicon element in the anode film layer % Number of cycles at 60°C Volumetric energy density Wh / L Exemplary embodiment 7-1 Silicon carbide 0,50 2145 442 Exemplary embodiment 7-2 Silicon carbide 4,99 1554 490 Exemplary embodiment 7-3 Silicon carbide 3,00 1785 473 Example 8 silicon dioxide 0,84 1583 441 Example 9 Silicon carbide 0,84 1743 453 Example 10 Silicon carbide 0,84 1780 453 Example 11 Silicon carbide 0,84 1732 453 Comparative example 3-1 / / 2367 430 Comparison example 3-2 Silicon carbide 7,20 538 512

[0404] In Table 3, In comparison with Comparative Example 3-1, the embodiment of the present application introduces a silicon-based material into the anode film layer, which can significantly improve the energy density of the battery cell; however, the addition of the silicon-based material is too high, as in Comparative Example 3-2, and although the energy density of the battery cell is higher, the volume of the silicon-based material expands excessively and degrades the cycle.

[0405] The silicon-based material of embodiment 1, embodiment 7-1 to embodiment 7-3 of the present application has a suitable silicon content by mass in the anode film layer, for example, from 0.5% to 5.00%, optionally from 0.8% to 3%, so that the battery cell has a relatively high energy density. At high energy density, the synergistic effect of vinyl carbonate and cyclic carbonate additives in the electrolyte solution effectively mitigates the volume expansion of the silicon-based material and improves the cycle performance of the battery cell.

[0406] The silicon-based material has various distribution forms, such as embodiment 1, embodiment 9, embodiment 10 and embodiment 11, etc. In contrast to other embodiments, in embodiment 1 the silicon-based material is arranged in the first anode film layer, so that the second anode film layer can exert a certain inhibiting effect on the volume expansion of the first anode film layer, reduce the volume expansion of the anode film layer as a whole and effectively improve the cycle performance of the battery cell.

[0407] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments are not to be construed as limiting the present application and that changes, substitutions and modifications to the embodiments may be made without departing from the spirit, principles and scope of the present application. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Standard JY / T 0575-2020

[0155] GB / T9722-2006

[0156] GB / T 19077-2016

[0169] GB / T 19587-2017

[0171] Norm GB / T30902-2014

[0189] GB / T24533-2009

[0248] GB / T 36363-2018

[0272]

Claims

[1] Battery cell comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil and an anode foil; wherein the cathode foil comprises a cathode collector and a cathode film layer arranged on at least one side of the cathode collector, wherein the cathode film layer comprises a lithium-containing phosphate; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one side of the anode collector, wherein the anode film layer comprises a carbon-based material and a silicon-based material; wherein the electrolyte solution comprises vinyl carbonate and a cyclic carbonate additive, wherein the cyclic carbonate additive comprises one or more of vinylidene carbonate and a vinyl carbonate derivative, where the mass content of the silicon element of the silicon-based material in the anode film layer is 0.5% to 5%; the mass content of vinyl carbonate in the electrolyte solution is 20% to 40%; The mass content of the cyclic carbonate additive in the electrolyte solution is 2% to 8%. [2] Battery cell according to claim 1, wherein the mass content of vinyl carbonate in the electrolyte solution is 20% to 35%. [3] Battery cell according to claim 1 or 2, wherein the mass content of vinylidene carbonate in the electrolyte solution is 1.5% to 5%. [4] Battery cell according to any one of claims 1 to 3, wherein the mass content of the vinyl carbonate derivative in the electrolyte solution is 0 to 4%. [5] Battery cell according to claim 4, wherein the mass content of the vinyl carbonate derivative in the electrolyte solution is 1.5% to 3.5%. [6] Battery cell according to any one of claims 1 to 5, wherein the vinyl carbonate derivative comprises a compound represented in formula A, wherein in formula A Q1, Q2, Q3 and Q4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group and at least one of Q1, Q2, Q3 and Q4 comprises a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group. [7] Battery cell according to claim 6, wherein at least one of Q1, Q2, Q3 and Q4 comprises a halogen atom or a C1 to C5 haloalkyl group. [8] Battery cell according to any one of claims 1 to 7, wherein the vinyl carbonate derivative comprises one or more of the compounds shown in formula A-1 to formula A-3, [9] Battery cell according to any one of claims 1 to 8, wherein the electrolyte solution further comprises a linear ester solvent, wherein the linear ester solvent comprises one or more of a linear carboxylic acid ester solvent and a linear carbonate solvent, wherein the mass fraction of the linear ester solvent in the electrolyte solution is 45% to 65%. [10] Battery cell according to claim 9, wherein the linear carboxylic acid ester solvent comprises a compound represented in formula I, where in Formula I, R1 comprises a hydrogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, R2 comprises a C1 to C5 alkyl group or a C1 to C5 haloalkyl group. [11] Battery cell according to claim 9 or 10, wherein the linear carboxylic acid ester solvent comprises one or more of the compounds shown in Formula I-1 to Formula I-12, [12] Battery cell according to any one of claims 9 to 11, wherein the linear carbonate solvent comprises one or more of dimethyl carbonate, diethyl carbonate and methylethyl carbonate. [13] Battery cell according to any one of claims 9 to 12, wherein the linear ester solvent comprises a linear carbonate solvent; The mass content of the cyclic carbonate additive is 2% to 5%. [14] Battery cell according to any one of claims 9 to 12, wherein the linear ester solvent comprises a linear carboxylic acid ester solvent with a mass content >0 and a linear carbonate solvent with a mass content ≥0; The mass content of the cyclic carbonate additive is 3.5% to 8%. [15] Battery cell according to any one of claims 1 to 14, wherein the electrolyte solution comprises an electrolyte lithium salt, wherein the mass content of the electrolyte lithium salt in the electrolyte solution is 10% to 18%. [16] Battery cell according to claim 15, wherein the electrolyte lithium salt comprises one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. [17] Battery cell according to claim 16, wherein the mass content of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte solution is 4% to 6%. [18] Battery cell according to any one of claims 1 to 17, wherein the electrolyte solution further comprises a sulfur-containing additive with a mass content of 0 to 2% in the electrolyte solution, wherein the sulfur-containing additive comprises one or more of vinyl sulfate, vinyl bisulfate, 1,3-propanesulfonyllactone, butylenyl sulfite, vinyl sulfite and methylenedisulfonylmethane; and / or wherein the electrolyte solution further comprises a lithium salt-like additive having a mass content of 0 to 1% in the electrolyte solution, wherein the lithium salt-like additive comprises one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium bisoxalate borate. [19] Battery cell according to claim 18, wherein the mass content of the sulfur-containing additive in the electrolyte solution is 0.5% to 2%; and / or wherein the mass content of the lithium salt-like additive in the electrolyte solution is 0.2% to 1%. [20] Battery cell according to any one of claims 1 to 19, wherein the mass content of the silicon element of the silicon-based material in the anode film layer is 0.8% to 3%. [21] Battery cell according to any one of claims 1 to 20, wherein the silicon-based material comprises one or more of monomeric silicon, silicon-carbon material, silicon-oxygen material, silicon-nitrogen material. [22] Battery according to claim 21, wherein the silicon-based material comprises one or more silicon-carbon materials, silicon-oxygen materials, or silicon-nitrogen materials. [23] Battery cell according to claim 22, wherein the silicon-based material comprises a silicon-carbon material. [24] Battery cell according to claim 22 or 23, wherein the mass content of the silicon element is 40% to 80% based on the mass of the silicon-based material; and / or wherein the silicon-based material has a volume-average particle size Dv50 of 5.0 µm to 12.5 µm; and / or the silicon-based material has a specific surface area of ​​3.1 m²2 / g up to 3.6 m 2 / g exhibits; and / or the silicon-based material has a powder compaction density of 0.7 g / cm³ at 25,000 N. 3 up to 1.2 g / cm³ 3 exhibits. [25] Battery cell according to any one of claims 1 to 24, wherein the carbon-based material comprises graphite particles, wherein the graphite particles comprise graphite body particles and an anode coating layer coated on the surface of the graphite body particles, wherein the graphite body particles comprise secondary particles, wherein the anode coating layer comprises carbon elements. [26] Battery cell according to claim 25, wherein the graphite body particles comprise one or more of artificial graphite and natural graphite. [27] Battery cell according to claim 25 or 26, wherein the mass content of the carbon element in the anode coating layer is 2% to 5%, based on the mass of the graphite particles. [28] Battery cell according to any one of claims 1 to 27, wherein the anode film layer comprises a first anode film layer and a second anode film layer, wherein the first anode film layer is arranged on the surface of the anode collector; wherein the second anode film layer is arranged on a side of the first anode film layer facing away from the anode collector, wherein the volume mean particle size Dv50 of the carbon-based material of the first anode film layer is greater than or equal to the volume mean particle size Dv50 of the carbon-based material of the second anode film layer, wherein at least one of the first anode film layer and the second anode film layer comprises a silicon-based material. [29] Battery cell according to claim 28, wherein the volume mean particle size Dv50 of the carbon-based material of the second anode film layer is 8.5 µm to 14.5 µm; and / or wherein the volume mean particle size Dv50 of the carbon-based material of the first anode film layer is 9.8 µm to 16.8 µm. [30] Battery cell according to claim 28 or 29, wherein the silicon-based material is located in the first anode film layer. [31] Battery cell according to any one of claims 1 to 30, wherein the density of the aode film layer at a 100% charge state of the battery cell is 1.10 g / cm³ 3 up to 1.50 g / cm³ 3 amounts. [32] Battery cell according to any one of claims 1 to 31, wherein the one-sided coating weight of the anode film layer is 90 mg / 1540.25 mm 2 up to 140 mg / 1540.25 mm 2 amounts. [33] Battery cell according to any one of claims 1 to 32, wherein the thickness of the anode collector is 4 µm to 6 µm. [34] Battery cell according to one of claims 1 to 33, wherein the anode foil further comprises a conductive anode layer, wherein the conductive anode layer is located between the anode collector and the anode film layer, wherein the conductive anode layer comprises a conductive anode medium, wherein the conductive anode medium comprises one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. [35] Battery cell according to claim 34, wherein the thickness of the conductive anode layer is 0.5 µm to 2 µm. [36] Battery cell according to any one of claims 1 to 35, wherein the lithium-containing phosphate comprises: Phosphate particles, and a cathode coating layer, wherein the cathode coating layer is arranged on at least a part of the surface of the phosphate particles, and wherein the cathode coating layer comprises carbon elements. [37] Battery cell according to claim 36, wherein the mass content of the carbon element is 0.8% to 2.3%, based on the mass of the lithium-containing phosphate. [38] Battery cell according to claim 36 or 37, wherein the cathode coating layer further comprises one or more of the elements Fe, Ti, Zr, Hf, Ge, Sn. [39] Battery cell according to one of claims 36 to 38, wherein the phosphate particles comprise one or more of lithium iron phosphate, lithium manganese phosphate, lithium ferromanganese phosphate, lithium nickel phosphate and lithium cobalt phosphate. [40] Battery cell according to any one of claims 1 to 39, wherein the lithium-containing phosphate is a material having the general formula of Li x1 A y1 Me a1 Mb1 P 1-c1 X c1 Y z1 includes where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5. where A comprises one or more of the elements Na, K and Mg; where Me comprises one or more of the elements Mn, Fe, Co and Ni; where M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge and Ce; where X comprises one or more of the elements Cl, C, N; where Y comprises one or more of the elements O and F. [41] Battery cell according to any one of claims 1 to 40, wherein the powder density of the active cathode material is 2.46 g / cm³ 3 up to 2.85 g / cm³ 3 at 30,000 N. [42] Battery cell according to one of claims 1 to 41, wherein the density of the cathode film layer is 2.5 g / cm³ 3 up to 2.8 g / cm³ 3at a 100% state of charge (SOC) of the battery cell. [43] Battery cell according to any one of claims 1 to 42, wherein the one-sided coating weight of the cathode film layer is 200 mg / 1540.25 mm 2 up to 350 mg / 1540.25 mm 2 amounts. [44] Battery cell according to any one of claims 1 to 43, wherein the thickness of the cathode collector is 10 µm to 15 µm. [45] Battery cell according to one of claims 1 to 44, wherein the cathode foil further comprises a conductive cathode layer, wherein the conductive cathode layer is located between the cathode collector and the cathode film layer, wherein the conductive cathode layer comprises a conductive cathode medium, wherein the conductive cathode medium comprises one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. [46] Battery cell according to claim 45, wherein the thickness of the conductive cathode layer is 0.5 µm to 2 µm. [47] Battery cell according to one of claims 1 to 46, wherein the electrode assembly further comprises a separator, wherein the separator is located between the cathode foil and the anode foil, wherein the thickness of the separator is 4 µm to 12 µm. [48] ​​Battery cell according to any one of claims 1 to 46, characterized by that the porosity of the separator is between 20% and 70%. [49] Battery cell according to claim 47 or 48, wherein the separator further comprises a base film and a functional layer arranged in the base film, the functional layer comprising: a first functional layer located on one side of the base film, wherein the first functional layer comprises first inorganic particles; a second functional layer located on the other side of the base film, wherein the second functional layer comprises composite particles, the composite particles comprising second inorganic particles and several non-fluorinated polymer particles, wherein the second inorganic particles adhere to the surface of the non-fluorinated polymer particles and / or are dispersed in the non-fluorinated polymer particles. [50] Battery cell according to claim 49, wherein the non-fluorinated polymer particles comprise an acrylate copolymer. [51] Battery cell according to claim 49 or 50, wherein the first inorganic particle comprises one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide; and / or where the average particle size of the first inorganic particles is 5 nm to 100 nm. [52] Battery cell according to any one of claims 49 to 51, wherein the second inorganic particle is one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide, and / or where the average particle size of the second inorganic particles is 5 nm to 100 nm. [53] Battery cell according to one of claims 1 to 52, wherein the cathode foil and the anode foil are arranged in a cascade-like manner along a thickness direction of the battery cell; wherein the electrode assembly further comprises a cathode tab and an anode tab, wherein the cathode tab is connected to at least one side of the cathode collector along a longitudinal direction of the battery cell, wherein the anode tab is connected to at least one side of the anode collector along the longitudinal direction of the battery cell; wherein along the longitudinal direction of the battery cell the dimension of the anode film layer is larger than the dimension of the cathode film layer, and wherein the difference between the dimension of the anode film layer and the dimension of the cathode film layer is OH1; wherein along the width direction of the battery cell the dimension of the anode film layer is larger than the dimension of the cathode film layer, and wherein the difference between the dimension of the anode film layer and the dimension of the cathode film layer is OH2; where OH1 is larger than OH2. [54] Battery cell according to claim 53, wherein OH1 is 1 mm to 4 mm; and / or where OH2 is 1 mm to 3 mm. [55] Battery cell according to claim 53 or 54, wherein the cathode tab and the anode tab are arranged at the same end along the longitudinal direction of the electrode assembly; and / or wherein the cathode tab and the anode tab are each arranged at both ends along the longitudinal direction of the electrode assembly. [56] Battery cell according to any one of claims 1 to 55, wherein the battery cell comprises a housing body, wherein the housing body accommodates the electrode assembly and the electrolyte solution, wherein the housing body has a rectangular structure, wherein the housing body comprises two first side walls arranged opposite each other and two second side walls arranged opposite each other, wherein the two first side walls are connected to each other by the second side walls, wherein the first side walls have a cross-sectional area perpendicular to their own thickness direction which is larger than the cross-sectional area of ​​the second side walls perpendicular to their own thickness direction, wherein the thickness of the first side walls is 0.1 mm to 0.5 mm. [57] Battery cell according to claim 56, wherein the thickness of the first side wall is 0.2 mm to 0.35 mm. [58] Battery cell according to any one of claims 1 to 57, wherein the volumetric energy density of the battery cell is 450 Wh / L to 530 Wh / L. [59] Battery device comprising a battery cell according to any one of claims 1 to 58. [60] Power consumption device comprising a battery device according to claim 59.

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