Battery device and electric device

Abstract

The invention relates to a battery device and a power utilization device.The battery device comprises a heat insulation part and at least two battery single bodies arranged in the first direction, each battery single body comprises an electrode assembly and electrolyte, and the electrode assembly comprises a positive pole piece and a negative pole piece; the positive pole piece comprises a positive current collector and a positive film layer arranged on at least one side of the positive current collector, and the positive film layer comprises lithium-containing phosphate; the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, and the negative electrode film layer comprises graphite particles; wherein the electrolyte comprises fluorine-containing sulfimide salt, and the mass content of the fluorine-containing sulfimide salt in the electrolyte is 2%-12%; the battery cell includes two first surfaces opposite to each other in a first direction, the heat insulating member covers at least one of the two first surfaces, and the size of the heat insulating member in the first direction is 0.3 mm to 5 mm. The cycle performance and the use reliability of the battery device can be improved.

Description

[0001] This application claims the priority of PCT International Application PCT / CN2025 / 082580, entitled "Battery Device and Electrical Device", filed on March 14, 2025, the entire content of which is incorporated herein by reference. Technical Field

[0002] This application relates to a battery device and an electrical device. Background Art

[0003] Battery devices have characteristics such as high capacity and long life, and are thus widely used in electronic devices, such as mobile phones, laptop computers, battery-powered vehicles, electric vehicles, electric aircraft, electric ships, and electric tools, etc. With the development of the application fields of lithium-ion batteries, higher requirements are put forward for the performance of battery devices, such as the cycling performance and use reliability of battery devices. Summary of the Invention This application provides a battery device and an electrical device, which can improve the cycling performance and use reliability of the battery device.

[0004] In a first aspect, this application provides a battery device, which includes a heat-insulating member and at least two battery cells arranged along a first direction. Each battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode tab and a negative electrode tab. The positive electrode tab includes a positive current collector and a positive electrode film layer provided on at least one side of the positive current collector, and the positive electrode film layer includes a lithium-containing phosphate. The negative electrode tab includes a negative current collector and a negative electrode film layer provided on at least one side of the negative current collector, and the negative electrode film layer includes graphite particles. Wherein, the electrolyte includes a fluorosulfonylimide salt, and the mass content of the fluorosulfonylimide salt in the electrolyte is 2% to 12%. Each battery cell includes two first surfaces facing each other along the first direction, and the heat-insulating member covers at least one of the two first surfaces. The dimension of the heat-insulating member along the first direction is 0.3 mm to 5 mm.

[0005] Thus, in the embodiments of this application, on the one hand, the material system is selected. The positive electrode active material includes a lithium-containing phosphate, and the negative electrode active material includes graphite particles. The above material system has excellent cycling stability; in the case of adopting the above material system, the risk of thermal runaway of the battery cell is relatively low. On the other hand, the electrolyte includes fluorosulfonylimide salt. The introduction of fluorosulfonylimide salt with a mass content greater than or equal to 2% can reduce the addition amount of hexafluorophosphate, thereby reducing the content of hydrofluoric acid generated by the decomposition of hexafluorophosphate, alleviating the damage of hydrofluoric acid to the solid electrolyte interface (SEI) film on the negative electrode side, improving the protective effect of the SEI film on the negative electrode active material, and enhancing the cycle performance of the battery cell; setting a heat insulation member with a preset size to cover the first surface of the heat insulation member can effectively block the rapid conduction of heat to other battery cells, reduce the risk of thermal runaway, and improve the use reliability of the battery device.

[0006] In some embodiments, the size of the heat insulation member in the first direction is 0.5 mm to 2.5 mm. When the size of the heat insulation member is within the above range, it can effectively alleviate heat conduction, and the occupied space in the battery device is small, which can improve the energy density of the battery device.

[0007] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is 2% to 6%; the size of the heat insulation member in the first direction is greater than or equal to 0.5 mm and less than or equal to 1.0 mm. The cooperation of the fluorosulfonylimide salt and a heat insulation member with an appropriate size can effectively improve the heat alleviating ability of the heat insulation member, taking into account the improvement of the energy density and use reliability of the battery device.

[0008] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is greater than 6% and less than or equal to 8%; the size of the heat insulation member in the first direction is greater than 1.0 mm and less than or equal to 1.5 mm. The cooperation of the fluorosulfonylimide salt and a heat insulation member with an appropriate size can effectively improve the heat alleviating ability of the heat insulation member, taking into account the improvement of the energy density and use reliability of the battery device.

[0009] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is greater than 8% and less than or equal to 12%; the size of the heat insulation member in the first direction is greater than 1.5 mm and less than or equal to 2.5 mm. The cooperation of the fluorosulfonylimide salt and a heat insulation member with an appropriate size can effectively improve the heat alleviating ability of the heat insulation member, taking into account the improvement of the energy density and use reliability of the battery device.

[0010] In some embodiments, the volume energy density of the battery cell is 400 Wh / L to 530 Wh / L, making the energy density of the battery cell relatively high.

[0011] In some embodiments, the volume energy density of the battery cell is 400 Wh / L to 440 Wh / L; the size of the heat insulation member in the first direction is greater than or equal to 0.5 mm and less than or equal to 1.0 mm. The cooperation of the energy density of the battery cell and a heat insulation member with an appropriate size can effectively improve the heat alleviating ability of the heat insulation member and improve the use reliability of the battery device.

[0012] In some embodiments, the volumetric energy density of the battery cell is greater than 440 Wh / L and less than or equal to 490 Wh / L; the dimension of the heat insulation member along the first direction is greater than 1.0 mm and less than or equal to 1.5 mm. The energy density of the battery cell in cooperation with a heat insulation member of appropriate size can effectively improve the heat dissipation capacity of the heat insulation member and improve the usage reliability of the battery device.

[0013] In some embodiments, the volumetric energy density of the battery cell is greater than 490 Wh / L and less than or equal to 530 Wh / L; the dimension of the heat insulation member along the first direction is greater than 1.5 mm and less than or equal to 2.5 mm. The energy density of the battery cell in cooperation with a heat insulation member of appropriate size can effectively improve the heat dissipation capacity of the heat insulation member and improve the usage reliability of the battery device.

[0014] In some embodiments, the battery device satisfies: 0.9 ≤ S 2 / S 1 ≤ 1, where S 1 represents the area of the first surface, with the unit of mm 2 ; and S 2 represents the area of the projection surface of the heat insulation member perpendicular to the first direction, with the unit of mm 2 . When the battery device satisfies the above conditions, the heat insulation member covers a relatively large area of the first surface, and can more effectively alleviate heat conduction.

[0015] In some embodiments, the battery cell includes electrode terminals, the electrode terminals are connected to at least one side of the electrode assembly along the second direction, and the second direction is perpendicular to the first direction; the battery cell includes two first surfaces opposite to each other along the first direction, and the heat insulation member covers the first surface; wherein, the battery device satisfies: 0.8 ≤ L 2 / L 1 ≤ 1, where L 1 represents the dimension of the first surface along the second direction, with the unit of mm; and L 2 represents the dimension of the heat insulation member along the second direction, with the unit of mm. When the battery device satisfies the above conditions, the heat insulation member covers a relatively large area of the first surface, and can more effectively alleviate heat conduction.

[0016] In some embodiments, the battery device further satisfies: 2 mm ≤ L 1 -L 2 ≤ 10 mm. When the battery device satisfies the above conditions, the heat insulation member covers a relatively large area of the first surface, and can more effectively alleviate heat conduction.

[0017] In some embodiments, the battery cell includes electrode terminals connected to at least one side of the electrode assembly in the second direction; the battery cell includes two first surfaces opposite to each other in the first direction, and the heat insulation member covers the first surfaces; wherein, the battery device satisfies: 0.9 ≤ H2 / H1 ≤ 1, where H1 represents the dimension of the first surface in the third direction, with the unit of mm, and the third direction, the second direction, and the first direction are perpendicular to each other in pairs; H2 represents the dimension of the heat insulation member in the third direction, with the unit of mm.

[0018] In some embodiments, the battery device further satisfies: 1 mm ≤ H 1 -H 2 ≤ 10 mm. When the battery device satisfies the above conditions, the heat insulation member covers a relatively large area of the first surface, and can more effectively alleviate heat conduction.

[0019] In some embodiments, the heat insulation member includes a heat insulation main body and a support member. The support member is disposed around the outside of the heat insulation main body, and both the heat insulation main body and the support member cover the surface of the battery cell in the first direction. The support member can support and fix the heat insulation main body, enabling the heat insulation main body to effectively play the role of heat insulation.

[0020] In some embodiments, the battery cell further includes two second surfaces opposite to each other in the third direction. The two second surfaces are connected by the first surface, and the third direction is perpendicular to the first direction. Among them, the area of the first surface is larger than the area of the second surface.

[0021] The area of the first surface is relatively large, and the heat insulation member covers the first surface, which can more effectively alleviate heat diffusion.

[0022] In some embodiments, the heat insulation member covers the two first surfaces of the battery cell. With such a setting, the heat insulation member can more effectively alleviate heat diffusion.

[0023] In some embodiments, the heat insulation member is bonded to the first surface, and the bonding force between the heat insulation member and the first surface is relatively strong, enabling the heat insulation member to effectively play the role of heat insulation.

[0024] In some embodiments, the support member is an annular member, and the support member satisfies: 10 mm ≤ W 1 -W 2 ≤ 60 mm, where W 1 represents the dimension of the outer contour of the annular member in the second direction; the battery cell includes electrode terminals connected to at least one side of the electrode assembly in the second direction, and the second direction is perpendicular to the first direction; W 2 represents the dimension of the inner contour of the annular member in the second direction; and / or the support member satisfies: 10 mm ≤ W 3 -W 4 ≤ 60 mm, where W 3represents the dimension of the outer contour of the annular member in the third direction; the battery cell includes electrode terminals, and the electrode terminals are connected to at least one side of the electrode assembly in the second direction. The third direction, the second direction, and the first direction are perpendicular to each other pairwise; W 4 represents the dimension of the inner contour of the annular member in the third direction. When the support member meets the above conditions, it can effectively support and fix the heat insulation main body.

[0025] In some embodiments, the heat insulation main body includes a heat insulation material, and the heat insulation material includes one or more of aerogel, foam, polyurethane, and silicone rubber. The heat insulation effect of the above materials is relatively excellent, and it can effectively alleviate heat diffusion.

[0026] In some embodiments, the support member includes one or more of polysaccharide, polyethylene terephthalate, polyurethane, polyacrylonitrile, polypropylene, polyamide, and aromatic polyamide. The support effect of the above materials is relatively excellent, and it can effectively support the heat insulation material.

[0027] In some embodiments, the fluorosulfonylimide salt includes one or more of bis(fluorosulfonyl)imide salt, bis(trifluoromethanesulfonyl)imide salt, and perfluorobutanesulfonylimide salt. The above materials can take into account improving the cycling performance and use reliability of the battery device.

[0028] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is 4% to 8%. When the mass content of the fluorosulfonylimide salt is within the above range, it can take into account improving the cycling performance and use reliability of the battery device.

[0029] In some embodiments, the electrolyte further includes hexafluorophosphate, and the mass content of hexafluorophosphate in the electrolyte is 3% to 13%. The combined use of the fluorosulfonylimide salt and hexafluorophosphate is beneficial to improving the cycling performance and use reliability of the battery device.

[0030] In some embodiments, the electrolyte further includes a carboxylic ester solvent, and the carboxylic ester solvent includes one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate. The above carboxylic ester solvents are beneficial to improving the cycling performance and fast charging performance of the battery cell.

[0031] In some embodiments, the mass content of the carboxylic ester solvent in the electrolyte is 8% to 60%. The carboxylic ester solvent with the above mass content is beneficial to improving the cycling performance and fast charging performance of the battery cell.

[0032] In some embodiments, the electrolyte further includes a carbonate solvent, and the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The above electrolyte system is beneficial to further improving the cycling performance of the battery cell.

[0033] In some embodiments, the mass content of the carbonate solvent in the electrolyte is 18% to 70%. The above electrolyte system is beneficial to further improving the cycling performance of the battery cell.

[0034] In some embodiments, the electrolyte further includes an additive; the additive includes a carbonate additive, and the carbonate additive includes one or more of vinylene carbonate and ethylene carbonate derivatives. The ethylene carbonate derivatives include the compounds shown in Formula A, Formula A, In Formula A, Q 1 、Q 2 、Q 3 and Q 4 each independently includes any one of a hydrogen atom, a halogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group, and Q 1 、Q 2 、Q 3 、Q 4 are not simultaneously hydrogen atoms; the carbonate additive can participate in the formation of the solid electrolyte interface SEI film at the negative electrode, which is beneficial to improving the cycling performance of the battery cell.

[0035] In some embodiments, the electrolyte further includes a sulfur-containing additive, and the sulfur-containing additive includes one or more of ethylene sulfate, bis(ethylene sulfate), 1,3-propane sultone, butylene sulfite, ethylene sulfite, and methylene methanedisulfonate; the sulfur-containing additive can optimize the film layer components of the SEI film and improve the cycling performance of the battery cell.

[0036] In some embodiments, the electrolyte further includes a lithium salt additive, and the lithium salt additive includes one or more of lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, and lithium bis(oxalato)borate. The lithium salt additive can optimize the film layer components of the SEI film and improve the cycling performance of the battery cell at high energy density.

[0037] In some embodiments, the mass content of the carbonate additive in the electrolyte is 2.5% to 10.0%; the carbonate additive with the above mass content can participate in the formation of the solid electrolyte interface SEI film at the negative electrode, which is beneficial to improving the cycling performance of the battery cell.

[0038] In some embodiments, the mass content of the sulfur-containing additive in the electrolyte is 0% to 2%; the sulfur-containing additive with the above mass content can optimize the film layer components of the SEI film and improve the cycling performance of the battery cell.

[0039] In some embodiments, the mass content of the lithium salt additive in the electrolyte is 0% to 1%. The lithium salt additive with the above mass content can optimize the film layer components of the SEI film and improve the cycling performance of the battery cell at high energy density.

[0040] In some embodiments, the single-sided coating weight of the positive electrode film layer is 220 mg / 1540.25 mm 2 to 450 mg / 1540.25 mm 2 When the single-sided coating weight of the positive electrode film layer is within the above range, the heat generation per unit area of the positive electrode plate will not be too large, improving the cycling performance of the battery cell at high energy density.

[0041] In some embodiments, the single-sided coating weight of the negative electrode film layer is 100 mg / 1540.25 mm 2 to 200 mg / 1540.25 mm 2 When the single-sided coating weight of the negative electrode film layer is within the above range, it is beneficial to improve the energy density and cycling performance of the battery cell.

[0042] In some embodiments, when the battery cell is at 100% SOC state of charge, the tap density of the positive electrode film layer is 2.6 g / cm 3 to 2.8 g / cm 3 When the tap density of the positive electrode film layer is within the above range, the energy density and cycling performance of the battery cell can be improved.

[0043] In some embodiments, when the battery cell is at 100% state of charge, the tap density of the negative electrode film layer is 1.2 g / cm 3 to 1.4 g / cm 3 When the tap density of the negative electrode film layer is within the above range, it is beneficial to improve the energy density and cycling performance of the battery cell.

[0044] In some embodiments, the lithium-containing phosphate includes phosphate particles and a positive electrode coating layer. The positive electrode coating layer is located on at least part of the surface of the phosphate particles, and the positive electrode coating layer contains carbon elements. By surface-coating the phosphate particles with the positive electrode coating layer, the conductivity of the lithium-containing phosphate can be improved, which is beneficial to the migration rate of lithium ions, improves the fast charging ability of the battery, and reduces the heat generation of the battery cell, improving the cycling performance of the battery cell.

[0045] In some embodiments, based on the mass of the lithium-containing phosphate, the mass content of carbon element is 0.8% to 2.3%. When the mass content of carbon element is within the above range, the conductivity of the lithium-containing phosphate can be significantly improved, which is beneficial to enhancing the ionic conductivity and electronic conductivity of the lithium-containing phosphate, and can improve the rapid charging ability of the battery cell at high energy density.

[0046] In some embodiments, the positive electrode coating layer further includes one or more elements of Fe, Ti, Zr, Hf, Ge, and Sn. The above positive electrode coating layer can improve the ionic conductivity of the positive electrode active material, improve the rapid charging ability of the battery cell, and in addition, can also improve the specific capacity and the energy density of the corresponding battery cell.

[0047] In some embodiments, the phosphate particles include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The cycle stability of the above materials is relatively excellent, and can improve the cycle performance of the battery cell.

[0048] In some embodiments, the lithium-containing phosphate includes a material with the general formula 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, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge, and Ce; X includes one or more of Cl, C, and N; Y includes one or more of O and F. The cycle stability of the above materials is relatively excellent, and can improve the cycle performance of the battery cell.

[0049] In some embodiments, the thickness of the positive electrode current collector is 10 μm to 15 μm. When the thickness of the positive electrode current collector is within the above range, the thickness of the positive electrode current collector is relatively thin, which is beneficial to enhancing the volume energy density of the battery cell.

[0050] In some embodiments, the positive electrode tab further includes a positive electrode conductive layer, which is located between the positive electrode current collector and the positive electrode film layer. The positive electrode conductive layer includes a positive electrode conductive agent, and the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The positive electrode conductive layer can further improve the conductivity of the positive electrode tab, reduce the heat generation of the positive electrode tab, and thus reduce the heat generation of the battery cell.

[0051] In some embodiments, the thickness of the positive electrode conductive layer is 0.5 μm to 2 μm. When the thickness of the positive electrode conductive layer is within the above range, it can further improve the conductivity of the positive electrode tab, reduce the heat generation of the positive electrode tab, and thus reduce the heat generation of the battery cell, and can improve the fast charging performance and high-temperature cycling performance of the battery cell at high energy density.

[0052] In some embodiments, the graphite particles include graphite body particles and a negative electrode coating layer coated on the surface of the graphite body particles. The graphite body particles include secondary particles, and the negative electrode coating layer includes carbon elements. The conductivity of the negative electrode coating layer is relatively excellent, which can reduce the internal resistance of the negative electrode tab, reduce the heat generation of the battery cell, and improve the cycling performance of the battery cell at high energy density.

[0053] In some embodiments, the graphite body particles include one or more of artificial graphite and natural graphite.

[0054] In some embodiments, based on the mass of the graphite particles, the mass content of carbon elements in the negative electrode coating layer is 2% to 5%. When the mass content of carbon elements in the negative electrode coating layer is within the above range, it can further reduce the internal resistance of the negative electrode tab, reduce the heat generation of the battery cell, and can improve the cycling performance of the battery cell at high energy density.

[0055] In some embodiments, the powder resistivity of the graphite particles is 0.005 Ω•cm to 0.04 Ω•cm. When the graphite particles meet the above conditions, it is beneficial to improve the fast charging ability of the battery cell.

[0056] In some embodiments, the volume average particle size Dv50 of the graphite particles is 9.5 μm to 16.5 μm. When the graphite particles meet the above conditions, it is beneficial to improve the energy density and cycling performance of the battery cell.

[0057] In some embodiments, the negative electrode film layer further includes a silicon-based material, and the mass content of silicon elements in the negative electrode film layer is 1% to 5%. When the mass content of silicon elements is within the above range, it can improve the energy density and cycling performance of the battery cell.

[0058] In some embodiments, the silicon-based material includes one or more of elemental silicon, silicon-carbon material, silicon-oxygen material, and silicon-nitrogen material; optionally, the silicon-based material includes one or more of silicon-carbon material, silicon-oxygen material, and silicon-nitrogen material. Optionally, the silicon-based material includes silicon-carbon material. The specific capacity of the above materials is relatively high, which is beneficial to improving the energy density of the battery cell.

[0059] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 6 μm. When the thickness of the negative electrode current collector is within the above range, the thickness of the negative electrode current collector is relatively thin, which is beneficial to improving the volume energy density of the battery cell.

[0060] In some embodiments, the negative electrode sheet further includes a negative electrode conductive layer, the negative electrode conductive layer is located between the negative electrode current collector and the negative electrode film layer, the negative electrode conductive layer includes a negative electrode conductive agent, and the negative electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The negative electrode conductive layer can further improve the conductivity of the negative electrode sheet, reduce the heat generation of the negative electrode sheet, thereby reducing the heat generation of the battery cell, and improving the fast charging performance and high-temperature cycle performance of the battery cell.

[0061] In some embodiments, the thickness of the negative electrode conductive layer is 0.5 μm to 2 μm. When the thickness of the negative electrode conductive layer is within the above range, it can further improve the conductivity of the negative electrode sheet, reduce the heat generation of the negative electrode sheet, thereby reducing the heat generation of the battery cell, and can also take into account improving the energy density of the battery cell.

[0062] In some embodiments, the electrode assembly further includes a separator, the separator is located between the positive electrode sheet and the negative electrode sheet, and the thickness of the separator is 4 μm to 12 μm. When the thickness of the separator is within the above range, the migration path of lithium ions in the separator is shorter, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance and high-temperature cycle performance of the battery cell at high energy density.

[0063] In some embodiments, the porosity of the separator is 20% to 70%. When the porosity of the separator is within the above range, it can improve the migration ability of lithium ions in the separator, can further reduce the internal resistance of the battery cell, thereby reducing heat generation, and improving the fast charging performance and high-temperature cycle performance of the battery cell at high energy density.

[0064] In some embodiments, the separator membrane further includes a base film and a functional layer disposed on the base film. The functional layer includes a first functional layer and a second functional layer. The first functional layer is located on one side of the base film and includes first inorganic particles. The second functional layer is located on the other side of the base film and includes composite particles. The composite particles include second inorganic particles and a plurality of non-fluoropolymer particles. The second inorganic particles are attached to the surface of the non-fluoropolymer particles and / or dispersed inside the non-fluoropolymer particles. The first functional layer and the second functional layer have good heat resistance, which can improve the heat resistance of the separator membrane.

[0065] In some embodiments, the non-fluoropolymer particles include acrylate copolymers. Acrylate copolymers have excellent adhesion properties and high adhesion stability with the base film.

[0066] In some embodiments, the first inorganic particles include one or more of silica, alumina, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide; the first inorganic particles are beneficial to improving the heat resistance and compression modulus of the separator membrane.

[0067] In some embodiments, the average particle size of the first inorganic particles is 5 nm to 100 nm. When the average particle size of the first inorganic particles is in the above range, it is beneficial to improve the heat resistance and compression modulus of the separator membrane.

[0068] In some embodiments, the second inorganic particles include one or more of silica, alumina, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. The second inorganic particles can improve the heat resistance of the second functional layer and can cooperate with the non-fluoropolymer to form composite particles, further improving the cycle stability and kinetic performance of the separator membrane, and improving the cycle performance and fast charging performance of the battery cell.

[0069] In some embodiments, the average particle size of the second inorganic particles is 5 nm to 100 nm. When the average particle size of the second inorganic particles is in the above range, it is beneficial to improve the heat resistance and compression modulus of the composite particles.

[0070] In some embodiments, the positive electrode tab and the negative electrode tab are stacked along the thickness direction of the battery cell; the electrode assembly further includes a positive electrode ear and a negative electrode ear. The positive electrode ear is connected to at least one side of the positive electrode current collector along the length direction of the battery cell, and the negative electrode ear is connected to at least one side of the negative electrode current collector along the length direction of the battery cell; along the length direction of the battery cell, the size of the negative electrode film layer is larger than the size of the positive electrode film layer, and the difference between the size of the negative electrode film layer and the size of the positive electrode film layer is OH 1 ; along the width direction of the battery cell, the size of the negative electrode film layer is larger than the size of the positive electrode film layer, and the difference between the size of the negative electrode film layer and the size of the positive electrode film layer is OH 2, wherein, OH 1 is greater than OH 2 . When the battery cell meets the above conditions, the risk of lithium plating can be reduced, and the reliability of the battery cell in use can be improved.

[0071] In some embodiments, OH 1 is from 1 mm to 4 mm; and / or OH 2 is from 1 mm to 3 mm. When the battery cell meets the above conditions, the risk of lithium plating can be reduced, and the reliability of the battery cell in use can be improved.

[0072] In a second aspect, the present application provides an electrical device, and the electrical device includes the battery device according to any one of the embodiments of the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the drawings.

[0074] Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

[0075] Figure 2 is an exploded schematic diagram of a battery pack provided by some embodiments of the present application.

[0076] Figure 3 is Figure 2 a schematic structural diagram of the battery module shown.

[0077] Figure 4 is a schematic structural diagram of a battery cell provided by some embodiments of the present application.

[0078] Figure 5 is a schematic structural diagram of an electrode assembly of a battery cell provided by some embodiments of the present application.

[0079] Figure 6 is a top view schematic diagram of an electrode assembly of a battery cell provided by some embodiments of the present application.

[0080] Figure 7 is a schematic structural diagram of a battery cell provided by some other embodiments of the present application.

[0081] Figure 8 is a schematic structural diagram of a battery device provided by some embodiments of the present application.

[0082] Figure 9 is a schematic structural diagram of a battery device provided by some other embodiments of the present application.

[0083] Figure 10 Schematic structural diagram of a battery device provided for other embodiments of the present application.

[0084] Figure 11 Schematic structural diagram of a battery device provided for other embodiments of the present application.

[0085] Figure 12 Schematic structural diagram of a battery device provided for other embodiments of the present application.

[0086] Figure 13 Schematic structural diagram of a battery device provided for other embodiments of the present application.

[0087] Figure 14 Schematic structural diagram of a heat insulation member of a battery device provided for some embodiments of the present application.

[0088] Figure 15 Assembly schematic diagram of a battery cell, a heat insulation member and a fixture of the present application.

[0089] Figure 16 Schematic structural diagram of some battery cells of the present application.

[0090] The drawings are not necessarily drawn to actual scale.

[0091] Explanation of the reference numerals in the drawings is as follows: X, thickness direction; Y, width direction; Z, length direction; 1, vehicle; 2, battery pack; 3, controller; 4, motor; 5, box body; 5a, first box body part; 5b, second box body part; 5c, accommodation space; 6, battery module; 7, battery cell; 71, first test battery; 72, trigger battery; 10, electrode assembly; 11, positive electrode tab; 111, positive electrode tab ear; 112, positive electrode current collector; 113, positive electrode film layer; 12, negative electrode tab; 121, negative electrode tab ear; 122, negative electrode current collector; 123, negative electrode film layer; 13, separator; 20, outer shell; 21, housing; 211, first surface; 212, second surface; 22, end cover; 31, positive terminal; 32, negative terminal; 40, heat insulation member; 41, heat insulation main body; 42, support member; 50, battery device; F1, first direction; F2, second direction; F3, third direction; 60, fixture. Detailed implementation manners

[0092] Hereinafter, embodiments of the battery device and the electrical device of the present application will be specifically disclosed in detail with reference to the accompanying drawings as appropriate. However, there may be cases where unnecessary details are omitted. For example, there are cases where details of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0093] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present application, unless otherwise stated, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0094] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0095] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0096] Unless otherwise specified, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method can include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. For example, if it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0097] In the present application, the battery cell can be in the shape of a cylinder, a flat body, a cuboid or other shapes, etc., and the embodiments of the present application are not limited thereto. Generally, the battery cells are divided into three types according to the encapsulation method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application are not limited thereto.

[0098] The battery device mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0099] In the related art, in the case of internal heat accumulation in the battery cell, thermal runaway may occur. In the case where the battery device includes multiple battery cells, the overheated battery cell may trigger thermal runaway of other battery cells, deteriorating the reliability of the battery device in use.

[0100] In view of the above problems, the present application selects a material system. The positive electrode active material includes lithium-containing phosphate, and the negative electrode active material includes graphite. The cyclic stability of the above material system is relatively excellent, and the risk of thermal runaway of the battery cell is relatively low. However, in the above material system, when the lithium salt in the electrolyte is lithium hexafluorophosphate, the decomposition product (hydrofluoric acid) of lithium hexafluorophosphate further reacts with the solid electrolyte interface SEI film on the surface of graphite, resulting in an increase in gas generation during high-temperature storage of the battery cell, which is not conducive to the long-term cyclic performance of the battery cell. The present application adds lithium fluorosulfonylimide to the electrolyte to significantly reduce the content of hydrofluoric acid in the electrolyte and improve the cyclic performance of the battery cell. Since lithium fluorosulfonylimide has characteristics such as a decomposition temperature close to the thermal runaway temperature of the battery cell, a relatively fast thermal decomposition rate, and intense heat release, for a battery cell containing lithium fluorosulfonylimide, when the battery cell reaches the thermal runaway temperature, it will cause the electrolyte to rapidly release a large amount of heat and high-temperature gas, thereby causing a sharp increase in internal heat within a short period of time, and a large amount of heat is difficult to rapidly dissipate, exacerbating the severity of the thermal runaway of the battery cell and significantly increasing the safety risk. The present application provides a heat insulation member that covers the surface of a battery cell containing a specific content of lithium fluorosulfonylimide, and the size of the heat insulation member is adapted to the content of lithium fluorosulfonylimide, which can effectively block the rapid conduction of heat to other battery cells and reduce the speed of thermal propagation when the battery cell undergoes thermal runaway, thereby improving the reliability of use of the battery device.

[0101] Thus, the embodiments of the present application can balance the improvement of the cyclic performance and the reliability of use of the battery device.

[0102] The battery cell described in the embodiments of the present application is applicable to a battery device and an electrical device using the battery device.

[0103] The electrical device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; the electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, an electric planer, etc. The embodiments of the present application do not impose special restrictions on the above electrical devices.

[0104] For the convenience of description, the following embodiments take the electrical device as a vehicle as an example for description.

[0105] Figure 1Schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0106] As Figure 1 shown, a battery device is provided inside the vehicle 1, and the battery device can be arranged at the bottom, head or tail of the vehicle 1. The battery device can be used to supply power to the vehicle 1. For example, the battery device can be used as the operating power source of the vehicle 1.

[0107] The vehicle 1 may further include a controller 3 and a motor 4. The controller 3 is used to control the battery device to supply power to the motor 4. For example, it is used for the working power requirements during the start-up, navigation and driving of the vehicle 1.

[0108] In some embodiments of the present application, the battery device can not only be used as the operating power source of the vehicle 1, but also be used as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0109] The battery device (Battery Apparatus) mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly (Battery Cell Assembly) may include a plurality of battery cells, and the plurality of battery cells are connected in series, parallel or in a hybrid connection through a busbar component.

[0110] In some embodiments, the battery cell assembly (Battery Cell Assembly) is generally formed by arranging a plurality of battery cells.

[0111] As an example, the battery cell assembly can be a battery module (Battery Module), and the battery module is formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with cable ties.

[0112] In some embodiments, the battery device can be a battery pack 2 (battery Pack), and the battery pack 2 includes a box body and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body.

[0113] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box body by fixing the battery module in the box body.

[0114] As an example, the battery cell assembly can also be accommodated in the box body by directly fixing a plurality of battery cells to the box body.

[0115] Figure 2 Explosion schematic diagram of the battery pack provided for some embodiments of the present application. As Figure 2 shown, the battery pack 2 includes a box body 5 and battery cells ( Figure 2(not shown), the battery cells are accommodated in the box body 5.

[0116] The box body 5 is used to accommodate the battery cells, and the box body 5 can have various structures. In some embodiments, the box body 5 can include a first box body part 5a and a second box body part 5b. The first box body part 5a and the second box body part 5b cover each other, and the first box body part 5a and the second box body part 5b jointly define an accommodation space 5c for accommodating the battery cells. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a is a plate-like structure. The first box body part 5a covers the opening side of the second box body part 5b to form the box body 5 with the accommodation space 5c; both the first box body part 5a and the second box body part 5b can also be hollow structures with one side open, and the opening side of the first box body part 5a covers the opening side of the second box body part 5b to form the box body 5 with the accommodation space 5c. Of course, the first box body part 5a and the second box body part 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0117] To improve the sealing performance after the connection between the first box body part 5a and the second box body part 5b, a sealing member can also be provided between the first box body part 5a and the second box body part 5b, such as sealant, sealing ring, etc.

[0118] Assuming that the first box body part 5a covers the top of the second box body part 5b, the first box body part 5a can also be called the upper box cover, and the second box body part 5b can also be called the lower box body.

[0119] Figure 3 For Figure 2 The structural schematic diagram of the battery module shown.

[0120] In some embodiments, as Figure 3 shown, there are multiple battery cells 7. The multiple battery cells 7 are first connected in series or in parallel or in a hybrid connection to form a battery module 6. Then, multiple battery modules 6 are connected in series or in parallel or in a hybrid connection to form a whole and are accommodated in the box body.

[0121] The multiple battery cells 7 in the battery module 6 can be electrically connected through a busbar component to achieve the parallel or series or hybrid connection of the multiple battery cells 7 in the battery module 6. The busbar component can be one or more, and each busbar component is used to electrically connect at least two battery cells 7.

[0122] Figure 4 The structural schematic diagram of the battery cell 7 provided by some embodiments of the present application, Figure 5 The explosion schematic diagram of the battery cell 7 provided by some embodiments of the present application.

[0123] As Figure 4 and Figure 5As shown, in some embodiments, the battery cell 7 includes an electrode assembly 10 and a housing 20, and the electrode assembly 10 is accommodated in the housing 20.

[0124] The housing 20 can be of various shapes, such as a cylinder, a cuboid, etc. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cylinder structure, the housing 20 can be selected as a cylinder structure. If the electrode assembly 10 is a cuboid structure, the housing 20 can be selected as a cuboid structure. Optionally, the electrode assembly 10 is a cuboid structure.

[0125] The material of the housing 20 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiments of the present application do not impose special restrictions on this. Optionally, the inner wall of the housing 20 can further include an insulating layer, and the insulating layer can separate the housing 20 and the electrode assembly 10. The material of the insulating layer can be selected from the commonly used materials in the art and is not specifically limited herein.

[0126] The electrode assembly 10 accommodated in the housing 20 can be one or more.

[0127] In some embodiments, the housing 20 includes a housing body 21 and an end cap 22. The housing body 21 has an opening, and the end cap 22 covers the opening, and the electrode assembly is accommodated in the housing body 21.

[0128] In some embodiments, the material of the housing body 21 includes steel. Steel has high mechanical strength and is not easily deformed, which can improve the use reliability and cycling performance of the battery cell. Optionally, the mass ratio of steel is the highest among the materials in the housing body 21. Of course, the material of the housing body 21 can also include aluminum, etc.

[0129] Optionally, the housing body 21 is a cuboid structure. For example, the housing body 21 includes two opposite first surfaces 211 and two opposite second surfaces 212. The two second surfaces 212 are connected by the two first surfaces 211, and the area of the first surface 211 is larger than the area of the second surface 212.

[0130] Optionally, the thickness of the housing body 21 is from 0.1 mm to 0.5 mm, and can be selected from 0.2 mm to 0.35 mm. Exemplarily, the thickness of the housing body 21 is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm or a range composed of any two of the above values. When the thickness of the housing body 21 is within the above range, the housing body 21 has high mechanical strength, can improve the use reliability and cycling performance of the battery cell 7, and the housing body 21 occupies less space and has more internal space, which is beneficial to improving the energy density of the battery cell 7.

[0131] The electrode assembly 10 can be of a stacked structure or a wound structure.

[0132] Next, taking the electrode assembly 10 as an example of a stacked structure, the description is as follows. As Figure 5 shown, when the electrode assembly 10 is of a stacked structure, there are multiple positive electrode plates 11 and multiple negative electrode plates 12. The multiple positive electrode plates 11 and the multiple negative electrode plates 12 are stacked along the thickness direction X of the battery cell 7. Optionally, the electrode assembly 10 further includes a separator 13, and the separator 13 is located between the positive electrode plate 11 and the negative electrode plate 12.

[0133] In some embodiments, as Figure 5 and Figure 6 shown, the positive electrode plate 11 includes at least one positive electrode tab 111. At least one positive electrode tab 111 is connected to the positive electrode current collector 112 and extends out of the positive electrode current collector 112 along the length direction Z of the battery cell 7. Of course, at least one positive electrode tab 111 can also be connected to the positive electrode current collector 112 and extend out of the positive electrode current collector 112 along the width direction Y of the battery cell 7.

[0134] In some embodiments, the negative electrode plate 12 includes at least one negative electrode tab 121. At least one negative electrode tab 121 is connected to the negative electrode current collector 122 and extends out of the negative electrode current collector 122 along the length direction Z of the battery cell 7. Of course, at least one negative electrode tab 121 can also be connected to the negative electrode current collector 122 and extend out of the negative electrode current collector 122 along the width direction Y of the battery cell 7.

[0135] In some embodiments, the positive electrode tab 111 is connected to at least one side of the positive electrode current collector 112 along the length direction Z, and the negative electrode tab 121 is connected to at least one side of the negative electrode current collector 122 along the length direction Z. Along the length direction Z of the battery cell 7, the size of the negative electrode film layer 123 is larger than the size of the positive electrode film layer 113, and the difference between the size of the negative electrode film layer 123 and the size of the positive electrode film layer 113 is OH 1 ; along the width direction Y of the battery cell 7, the size of the negative electrode film layer 123 is larger than the size of the positive electrode film layer 113, and the difference between the size of the negative electrode film layer 123 and the size of the positive electrode film layer 113 is OH 2 , OH 1 is greater than OH 2 .

[0136] The negative electrode tab 121 is located on at least one side of the negative electrode current collector 122 along the length direction Z. The current density in the connection area between the negative electrode tab 121 and the negative electrode current collector 122 increases sharply, and problems such as lithium deposition are more likely to occur in this area; while in the embodiment of the present application, OH 1 is set to be greater than OH 2, so that the ability of the negative electrode film layer 123 to receive lithium ions is stronger in the length direction Z, especially the ability of the area of the negative electrode film layer 123 close to the negative electrode tab 121 to receive lithium ions can be improved, the risk of lithium deposition can be reduced, and the use reliability of the battery cell 7 can be improved.

[0137] Exemplarily, OH 1 is from 0.5 mm to 3.0 mm, such as 0.5 mm, 0.8 mm, 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 or a range composed of any two of the above values. Along the length direction Z, both sides of the negative electrode film layer 123 extend beyond the positive electrode film layer 113, and each side extends beyond OH 1 / 2, that is, half of the size of OH 1 is shown in Figure 6 OH 1 / 2.

[0138] Exemplarily, OH 2 is from 0.5 mm to 3.0 mm, such as 0.5 mm, 0.8 mm, 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 or a range composed of any two of the above values. Along the width direction Y, both sides of the negative electrode film layer 123 extend beyond the positive electrode film layer 113, and each side extends beyond OH 2 / 2, that is, half of the size of OH 2 is shown in Figure 6 OH 2 / 2.

[0139] In some embodiments, as Figure 7 shown, the battery cell 7 further includes a positive terminal 31, and the positive terminal 31 is disposed on the outer casing 20 and can be disposed on the housing 21 or the end cap 22.

[0140] The positive terminal 31 is electrically connected to the positive electrode tab 111. Optionally, the positive terminal 31 and the positive electrode tab 111 are welded. The positive terminal 31 and the positive electrode tab 111 can be connected through an adapter, or an adapter may not be used. Optionally, no adapter is used between the positive terminal 31 and the positive electrode tab 111, that is, the positive terminal 31 and the positive electrode tab 111 are directly welded, which can reduce the resistance at the connection and is beneficial to reducing the overall internal resistance of the battery cell 7.

[0141] In some embodiments, the battery cell 7 further includes a negative terminal 32, and the negative terminal 32 is disposed on the outer casing 20 and can be disposed on the housing 21 or the end cap 22.

[0142] The negative terminal 32 is electrically connected to the negative electrode tab 121. Optionally, the negative terminal 32 and the negative electrode tab 121 are welded. The negative terminal 32 and the negative electrode tab 121 can be connected through an adapter, or can be connected without using an adapter. Optionally, no adapter is used to connect the negative terminal 32 and the negative electrode tab 121, that is, the negative terminal 32 and the negative electrode tab 121 are directly welded, which can reduce the resistance at the connection and is beneficial to reducing the overall internal resistance of the battery cell 7.

[0143] Optionally, the number of positive terminals 31 on the same side of the electrode assembly 10 is at least one, optionally at least two. At least two positive terminals 31 can increase the current-carrying capacity of the positive terminals 31.

[0144] Optionally, the number of negative terminals 32 on the same side of the electrode assembly 10 is at least one, optionally at least two. At least two negative terminals 32 can increase the current-carrying capacity of the negative terminals 32.

[0145] In some embodiments, the positive electrode plate may include a positive current collector and a positive active material layer provided on at least one surface of the positive current collector. The positive active material layer includes a positive active material.

[0146] In some embodiments, the negative electrode plate may include a negative current collector and a negative active material layer provided on at least one surface of the negative current collector. The negative active material layer includes a negative active material.

[0147] In some embodiments, as Figure 8 shown, the battery device 50 includes a heat insulating member 40 and at least two battery cells 7 arranged along the first direction F1. The battery cell 7 includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive current collector and a positive film layer provided on at least one side of the positive current collector. The positive film layer includes a lithium-containing phosphate; the negative electrode plate includes a negative current collector and a negative film layer provided on at least one side of the negative current collector. The negative film layer includes graphite particles; Among them, the electrolyte includes a fluorosulfonylimide salt, and the mass content of the fluorosulfonylimide salt in the electrolyte is 2% to 12%; the battery cell 7 includes two first surfaces 211 opposite to each other along the first direction F1. The heat insulating member 40 covers at least one of the two first surfaces 211. The size of the heat insulating member 40 along the first direction F1 is 0.3 mm to 5 mm.

[0148] On the one hand, in the embodiments of the present application, a material system is selected. The positive active material includes a lithium-containing phosphate, and the negative active material includes graphite particles. The above material system has relatively excellent cycle stability; in the case of adopting the above material system, the risk of thermal runaway of the battery cell 7 is relatively low; On the other hand, lithium hexafluorophosphate may decompose to produce hydrofluoric acid (HF). The side reaction between hydrofluoric acid and the SEI film on the surface of the anode active material such as graphite may lead to an increase in gas generation during high-temperature storage. The electrolyte of the present application further includes a fluorosulfonylimide salt. However, when the mass content of the fluorosulfonylimide salt is less than 2%, the effect of improving the thermal stability of the electrolyte is not obvious. The introduction of a fluorosulfonylimide salt with a mass content greater than or equal to 2% can reduce the addition amount of the hexafluorophosphate salt, thereby reducing the content of hydrofluoric acid generated by the decomposition of the hexafluorophosphate salt, alleviating the damage of hydrofluoric acid to the SEI film, improving the protective effect of the SEI film on the anode active material, and enhancing the cycle performance of the battery cell 7. However, as the addition amount of the fluorosulfonylimide salt increases, the risk of thermal diffusion increases. Specifically, the thermal decomposition temperature of the fluorosulfonylimide salt is close to the thermal runaway temperature of the battery cell 7, and the fluorosulfonylimide salt has a relatively fast thermal decomposition rate and intense heat release, capable of rapidly releasing a large amount of heat and high-temperature gas, resulting in a sharp increase in the internal heat of the battery cell 7. A large amount of heat is difficult to release quickly, leading to thermal runaway. In the embodiment of the present application, the addition amount of the fluorosulfonylimide salt is not too high, less than or equal to 12%. Moreover, a heat insulation member 40 with a preset size is provided on the first surface 211 of the battery cell 7. For example, the size of the heat insulation member 40 along the first direction F1 is greater than or equal to 0.3 mm, so that the heat insulation effect of the heat insulation member 40 is relatively excellent, capable of effectively blocking the rapid conduction of heat to other battery cells 7, reducing the risk of thermal spread, and enhancing the use reliability of the battery device 50. As the size of the heat insulation member 40 increases, the heat insulation effect increases, but due to the increased space occupied by the heat insulation member 40, the energy density of the battery device 50 decreases. Therefore, the size of the heat insulation member 40 along the first direction F1 is limited to be less than or equal to 5 mm, which can balance the improvement of the use reliability and energy density of the battery device 50.

[0149] Thus, the embodiment of the present application can balance the improvement of the cycle performance and use reliability of the battery device 50, and can enhance the energy density of the battery device 50.

[0150] In some embodiments, the volumetric energy density of the battery cell 7 is 400 Wh / L to 530 Wh / L. Exemplarily, the volumetric energy density of the battery cell 7 is 400 Wh / L, 410 Wh / L, 420 Wh / L, 430 Wh / L, 450 Wh / L, 460 Wh / L, 470 Wh / L, 480 Wh / L, 490 Wh / L, 500 Wh / L, 510 Wh / L, 520 Wh / L, 530 Wh / L or the range composed of any two of the above values. The volumetric energy density of the battery cell 7 is relatively high.

[0151] In the embodiments of the present application, the volumetric energy density of the battery cell 7 has the meaning well-known in the art and can be detected by using the equipment and methods well-known in the art. For example, taking the upper limit voltage of battery charging as 3.65V and the cut-off voltage of battery discharging as 2.0V as an example for illustration, Place the battery cell 7 at 25°C, charge it at a constant current of 0.33C to 3.65V, then charge it at a constant voltage until the current is 0.05C, and discharge it at a constant current of 0.33C to 2.0V, and record the discharge capacity A at this time 0 , unit: Ah. Use a caliper to measure the length, width, and height of the battery cell 7 (generally calculated based on the outer shell size of the battery, excluding the height of the electrode terminals and excluding the insulating film outside the outer shell), and calculate the volume V of the single cell 0 , unit: L. The volumetric energy density VED of the battery cell 7 = (A 0 × the discharge platform voltage) / V 0 , unit: Wh / L.

[0152] In some embodiments, the volumetric energy density of the battery cell 7 can be increased by the following optional methods: From the perspective of the active materials, positive and negative active materials with high specific capacity can be used. For example, for the positive active material, a lithium-containing phosphate material with a higher gram capacity is used. For example, physically mix a positive active material with a higher gram capacity, such as a ternary material, to improve the energy density; for example, for the negative active material, graphite with a higher gram capacity is used. For example, physically mix a negative active material with a higher gram capacity, such as a silicon-based material, etc.; From the perspective of the electrolyte, reducing the amount of electrolyte injection or using an electrolyte that supports a higher energy density, etc., to improve the energy density of the battery cell 7; From the perspective of the electrode sheet design, the energy density of the battery cell 7 can be improved by adjusting the compaction density and coating weight of the positive electrode sheet or the negative electrode sheet. For example, increasing the compaction density or coating weight, etc.; or, the thickness of the positive current collector or the negative current collector can be reduced, etc.; In terms of the separator, the thickness of the separator can be adjusted. For example, reducing the thickness of the separator to improve the energy density of the battery cell 7; In terms of the structural design, first, the proportion of non-active materials such as battery components can be reduced. For example, making the battery outer shell thinner while ensuring its safety and mechanical properties, so that more active materials can be accommodated in the same space, improving the energy density. For example, adjusting the space occupancy ratio of the electrode assembly in the housing cavity.

[0153] At least two battery cells 7 arranged along the first direction F1. In other words, at least two battery cells 7 are arranged along the first direction F1. The first surface 211 of the battery cell 7 is perpendicular to the first direction F1.

[0154] In an embodiment of the present application, the housing of the battery cell 7 may be a cuboid structure, and the first direction F1 may be parallel to the thickness direction of the battery cell 7.

[0155] The second direction F2 may be parallel to the length direction or the width direction of the battery cell 7. When the second direction F2 is parallel to the length direction of the battery cell 7, the third direction F3 is parallel to the width direction of the battery cell 7; when the second direction F2 is parallel to the width direction of the battery cell 7, the third direction F3 is parallel to the length direction of the battery cell 7.

[0156] The battery cell 7 includes two first surfaces 211 that face each other along the first direction F1.

[0157] When the first surface 211 is larger than the second surface 212, the first surface 211 is the largest surface of the cuboid structure, and the heat insulation member 40 at least partially covers the first surface 211, which can effectively play a role in alleviating heat transfer. The heat insulation member 40 may cover at least part of the first surface 211, for example, cover the entire first surface 211, or may cover part of the first surface 211.

[0158] [Heat insulation member] As Figure 8 shown, the heat insulation member 40 covers at least one of the two first surfaces 211 of the battery cell 7, which can alleviate heat diffusion and improve the use reliability of the battery device 50.

[0159] As Figure 8 and Figure 9 shown, the heat insulation member 40 covers at least one of the two first surfaces 211 of the battery cell 7, which can alleviate heat conduction. In some embodiments, the heat insulation member 40 covers two first surfaces 211 of part of the battery cells 7 and covers one first surface 211 of another part of the battery cells 7. Exemplarily, the heat insulation member 40 is disposed between two adjacent battery cells 7, and no heat insulation member is disposed on the outermost sides of the plurality of battery cells 7 along the first direction F1.

[0160] As Figure 10 shown, in some other embodiments, the heat insulation member 40 covers the two first surfaces 211 of the battery cell 7. Exemplarily, the heat insulation member 40 is disposed between two adjacent battery cells 7, and the heat insulation member 40 is disposed on the outermost sides of the plurality of battery cells 7 along the first direction F1.

[0161] As shown in 11, in some embodiments, the heat insulation member 40 covers one of the two first surfaces 211 of the battery cell 7.

[0162] For example, there are 6 battery cells 7, and the 6 battery cells 7 are arranged along the first direction F1. A heat insulation member 40 is provided between the first battery cell 7 and the second battery cell 7, a heat insulation member 40 is provided between the third battery cell 7 and the fourth battery cell 7, and a heat insulation member 40 is provided between the fifth battery cell 7 and the sixth battery cell 7.

[0163] The heat insulation member 40 can be of a plate structure or other structural forms.

[0164] In the embodiment of the present application, the dimension of the heat insulation member 40 along the first direction F1 is 0.3 mm to 5 mm, such as 0.3 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm or the range composed of any two of the above values. Optionally, the dimension of the heat insulation member 40 along the first direction F1 is 0.5 mm to 2.5 mm. Figure 8 T1 shown in the figure represents the dimension of the heat insulation member 40 along the first direction F1.

[0165] The dimension of the heat insulation member 40 along the first direction F1 can be understood as the thickness of the heat insulation member 40. Within the above range, it can effectively alleviate heat conduction, and the occupied space in the battery device 50 is small, which can improve the energy density of the battery device 50.

[0166] As the mass content of the fluorosulfonylimide salt increases, the heat released when the battery cell 7 undergoes thermal runaway is higher, and the severity of thermal runaway is greater; in cooperation with the fluorosulfonylimide salt, the heat insulation member 40 can adopt an appropriate thickness to improve the ability of the heat insulation member 40 to alleviate heat diffusion.

[0167] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is 2% to 6%; the dimension of the heat insulation member 40 along the first direction F1 is 0.5 mm to 1.0 mm.

[0168] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is greater than 6% and less than or equal to 8%; the dimension of the heat insulation member 40 along the first direction F1 is greater than 1.0 mm and less than or equal to 1.5 mm.

[0169] In some embodiments, the mass content of the fluorosulfonylimide salt in the electrolyte is greater than 8% and less than or equal to 12%; the dimension of the heat insulation member 40 along the first direction F1 is greater than 1.5 mm and less than or equal to 2.5 mm.

[0170] As the volume energy density of the battery cell 7 increases, in the case of thermal runaway, more heat is released; in cooperation with the volume energy density of the battery cell 7, the heat insulation member 40 can adopt an appropriate thickness to improve the ability of the heat insulation member 40 to alleviate heat diffusion.

[0171] In some embodiments, the volumetric energy density of the battery cell 7 is from 400 Wh / L to 440 Wh / L; the dimension of the heat insulation member 40 along the first direction F1 is from 0.5 mm to 1.0 mm.

[0172] In some embodiments, the volumetric energy density of the battery cell 7 is greater than 440 Wh / L and less than or equal to 490 Wh / L; the dimension of the heat insulation member 40 along the first direction F1 is greater than 1.0 mm and less than or equal to 1.5 mm.

[0173] In some embodiments, the volumetric energy density of the battery cell 7 is greater than 490 Wh / L and less than or equal to 530 Wh / L; the dimension of the heat insulation member 40 along the first direction F1 is greater than 1.5 mm and less than or equal to 2.5 mm.

[0174] In some embodiments, as Figure 12 shown, the battery cell 7 includes two first surfaces 211 that face each other along the first direction F1, and the heat insulation member 40 covers the first surfaces 211. When the housing of the battery cell 7 is in a cuboid structure, the first surfaces 211 may be the largest surfaces of the cuboid structure. The heat insulation member 40 covering the first surfaces 211 can effectively play a role in alleviating heat transfer.

[0175] In some embodiments, the battery device 50 satisfies: 0.9 ≤ S 2 / S 1 ≤ 1, S 1 represents the area of the first surface 211, and its unit is mm 2 ; S 2 represents the area of the projection plane of the heat insulation member 40 perpendicular to the first direction F1, and its unit is mm 2 .

[0176] Exemplarily, S 2 / S 1 is 0.9, 0.92, 0.94, 0.95, 0.98, 1.0 or a range composed of any two of the above values. Figure 12 The area of the surface of the heat insulation member shown in 2 is S 1 .

[0177] When the battery device 50 satisfies the above conditions, the area of the heat insulation member 40 covering the first surface is relatively large, and heat conduction can be more effectively alleviated.

[0178] In some embodiments, the battery cell 7 includes electrode terminals such as a positive electrode terminal 31 and a negative electrode terminal 32. The electrode terminals are connected to at least one side of the electrode assembly along the second direction F2, and the second direction F2 is perpendicular to the first direction F1. Among them, the battery device 50 satisfies: 0.8 ≤ L 2 / L 1 ≤ 1, L 1 represents the dimension of the first surface 211 along the second direction F2, and its unit is mm; L 2 represents the dimension of the heat insulation member 40 along the second direction F2, and its unit is mm.

[0179] Exemplarily, L 2 / L 1 is 0.8, 0.82, 0.84, 0.85, 0.88, 0.9, 0.92, 0.94, 0.95, 0.98, 1.0 or a range composed of any two of the above values. Figure 12 L 1 and L 2 .

[0180] When the battery device 50 satisfies the above conditions, the heat insulation member 40 covers a relatively large size of the first surface 211, and can more effectively relieve heat conduction.

[0181] In some embodiments, the battery device 50 further satisfies: 2 mm ≤ L 1 -L 2 ≤ 10 mm.

[0182] Exemplarily, L 1 -L 2 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or a range composed of any two of the above values. Figure 12 In, both sides of the first surface 211 exceed the heat insulation member 40, and each side exceeds (L 1 -L 2 ) / 2, and both exceed 1 mm to 5 mm. Of course, only one side of the first surface 211 may exceed the heat insulation member 40.

[0183] When the battery device 50 satisfies the above conditions, the heat insulation member 40 covers a relatively large size of the first surface, and can more effectively relieve heat conduction.

[0184] In some embodiments, the battery device 50 satisfies: 0.9 ≤ H 2 / H 1 ≤ 1, H 1 represents the dimension of the first surface 211 along the third direction F3, and its unit is mm, and the third direction F3, the second direction F2 and the first direction F1 are perpendicular to each other in pairs; H 2Represents the dimension of the heat insulation member 40 along the third direction F3, with the unit of mm.

[0185] Exemplarily, H 2 / H 1 Is 0.9, 0.92, 0.94, 0.95, 0.98, 1.0 or a range composed of any two of the above values. Figure 12 Shows H 1 And H 2 .

[0186] When the battery device 50 meets the above conditions, the dimension of the heat insulation member 40 covering the first surface 211 is relatively large, and heat conduction can be more effectively alleviated.

[0187] In some embodiments, the battery device 50 further satisfies: 1mm ≤ H 1 -H 2 ≤ 10mm.

[0188] Exemplarily, H 1 -H 2 Can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or a range composed of any two of the above values. Figure 12 In, both sides of the first surface 211 exceed the heat insulation member 40, and each side exceeds (H 1 -H 2 ) / 2, and both exceed 0.5mm to 5mm. Of course, only one side of the first surface 211 may exceed the heat insulation member 40.

[0189] When the battery device 50 meets the above conditions, the dimension of the heat insulation member 40 covering the first surface 211 is relatively large, and heat conduction can be more effectively alleviated.

[0190] In some embodiments, the heat insulation member 40 can be bonded to the first surface 211. Such a setting enables the heat insulation member 40 to be closely attached to the first surface 211, which is beneficial to alleviating heat diffusion. Of course, the heat insulation member 40 can also only be in close contact with the first surface 211 and not be bonded together.

[0191] In some embodiments, the heat insulation member 40 includes a heat insulation main body 41 and a support member 42. The support member 42 is disposed around the heat insulation main body 41, and both the heat insulation main body 41 and the support member 42 cover the surface of the battery cell 7 along the first direction F1, that is, the first surface 211.

[0192] The support member 42 can support and fix the heat insulation main body 41, enabling the heat insulation main body 41 to effectively play the role of heat insulation.

[0193] In some embodiments, such as Figure 13As shown, the support member 42 is an annular member that is disposed around the heat insulation body 41 and can effectively support the heat insulation body 41. The annular member can be a square, rectangular, circular or other member, and can be adaptively adjusted according to the shape of the first surface 211. For example, if the first surface 211 is rectangular, the annular member is set to a rectangular structure.

[0194] In some embodiments, the support member 42 satisfies: 10mm ≤ W 1 -W 2 ≤ 60mm, W 1 represents the dimension of the outer contour of the annular member along the second direction F2, and the second direction F2 is perpendicular to the first direction F1; W 2 represents the dimension of the inner contour of the annular member along the second direction F2.

[0195] Exemplarily, W 1 -W 2 can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm or a range composed of any two of the above values. Figure 13 shows W 1 and W 2 , the dimensions of each part of the annular member are basically the same, and (W 1 -W 2 ) / 2 can be considered as the dimension of the annular member along the second direction F2.

[0196] When the support member 42 satisfies the above conditions, it can effectively support and fix the heat insulation body 41.

[0197] In some embodiments, the support member 42 satisfies: 10mm ≤ W 3 -W 4 ≤ 60mm, W 3 represents the dimension of the outer contour of the annular member along the third direction F3, and the third direction F3, the second direction F2 and the first direction F1 are perpendicular to each other in pairs; W 4 represents the dimension of the inner contour of the annular member along the third direction F3.

[0198] Exemplarily, W 3 -W 4 can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm or a range composed of any two of the above values. Figure 13 shows W 3 and W4 , the dimensions of each part of the annular member are basically the same, (W 3 -W 4 ) / 2 can be regarded as the dimension of the annular member along the third direction F3.

[0199] When the support member 42 meets the above conditions, it can effectively support and fix the heat insulation main body 41.

[0200] In some embodiments, as Figure 14 shown, the heat insulation main body 41 includes a heat insulation material, Figure 11 where G represents the heat insulation material.

[0201] In some embodiments, the heat insulation material includes one or more of aerogel, foam, polyurethane, and silicone rubber. The above materials have excellent heat insulation effects and can effectively alleviate heat diffusion.

[0202] In some embodiments, the material of the support member 42 may include a fiber material. Optionally, the fiber material may include one or more of polysaccharide, polyethylene terephthalate, polyurethane, polyacrylonitrile, polypropylene, polyamide, and aromatic polyamide. The above materials have excellent support effects and can effectively support the heat insulation material.

[0203] [Electrolyte] The battery cell includes an electrolyte. During the charge and discharge process of the battery cell, active ions such as lithium ions are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate, and the electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate.

[0204] In the embodiments of the present application, the electrolyte salt is a fluorosulfonylimide salt, and the mass content of the fluorosulfonylimide salt in the electrolyte is 2% to 12%, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12% or a range composed of any two of the above values. Optionally, the mass content of the fluorosulfonylimide salt in the electrolyte is 4% to 8%.

[0205] When the mass content of the fluorosulfonylimide salt is less than 2%, it may cause a relatively large addition amount of hexafluorophosphate in the electrolyte, and the excessive HF content may damage the SEI film and deteriorate the cycle; and when the addition amount of the fluorosulfonylimide salt is too small, the improvement of the thermal stability of the electrolyte is limited; When the mass content of the fluorosulfonylimide salt is greater than 12%, it may cause too high a severity and excessive heat release in the case of thermal runaway, and the heat diffuses to other battery cells, resulting in thermal runaway of other battery cells and causing problems with the use reliability of the battery device. When the mass content of the fluorosulfonylimide salt in the embodiments of the present application is within the above range, it can balance the improvement of the cycle performance and use reliability of the battery device.

[0206] Exemplarily, the fluorosulfonylimide salt includes one or more of bis(fluorosulfonyl)imide salts, bis(trifluoromethanesulfonyl)imide salts, and perfluorobutanesulfonylimide salts. The above materials can balance the improvement of the cycling performance and use reliability of the battery device.

[0207] In some embodiments, the electrolyte further includes hexafluorophosphate, and the mass content of hexafluorophosphate in the electrolyte is 3% to 13%, such as 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or the range composed of any two of the above values.

[0208] The combined use of the fluorosulfonylimide salt and hexafluorophosphate is beneficial to improving the cycling performance and use reliability of the battery device.

[0209] When the electrolyte salt includes a lithium salt, the fluorosulfonylimide salt may include lithium fluorosulfonylimide. For example, lithium fluorosulfonylimide includes one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium perfluorobutanesulfonylimide. The hexafluorophosphate may include lithium hexafluorophosphate.

[0210] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes a carboxylic acid ester solvent. The mass content of the carboxylic acid ester solvent in the electrolyte is 8% to 60%. Exemplarily, the mass content of the carboxylic acid ester solvent is 8%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60% or the range composed of any two of the above values. When the mass content of the carboxylic acid ester solvent is greater than or equal to 8%, the viscosity of the electrolyte system is relatively small, which is beneficial to the migration of lithium ions; when the mass content of the carboxylic acid ester solvent is less than or equal to 60%, the side reaction between the carboxylic acid ester solvent and the negative electrode active material is relatively small, which is beneficial to improving the cycling performance.

[0211] In some embodiments, the carboxylic acid ester solvent may include one or more of a linear carboxylic acid ester solvent and a cyclic carboxylic acid ester solvent, and may be selected as a linear carboxylic acid ester solvent. The carboxylic acid ester solvent has a lower viscosity and better fluidity, which is more beneficial to the rapid infiltration of the electrode sheet, and local lithium deposition is not likely to occur on the surface of the negative electrode sheet, improving the use reliability of the battery cell.

[0212] Exemplarily, the carboxylic acid ester solvent includes one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate.

[0213] The above materials have a lower viscosity, which can further improve the use reliability of the battery cell.

[0214] In the embodiments of the present application, the organic solvent further includes a carbonate solvent, and the mass content of the carbonate solvent in the electrolyte is 18% to 70%. Exemplarily, the mass content of the carbonate solvent in the electrolyte is 18%, 20%, 25%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, 65%, 70% or a range composed of any two of the above values.

[0215] The carbonate solvent with the above mass content can further improve the viscosity of the electrolyte, enhance the wetting performance of the electrode sheet, prevent local lithium deposition on the surface of the negative electrode sheet, and improve the reliability of the battery cell in use.

[0216] Exemplarily, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0217] The above materials have relatively low viscosity, which is beneficial to the rapid wetting of the electrode sheet, prevent local lithium deposition on the surface of the negative electrode sheet, and improve the reliability of the battery cell in use.

[0218] In the embodiments of the present application, the electrolyte further includes additives, and the additives include one or more of carbonate additives, sulfur-containing additives, and lithium salt additives. The additives can participate in the formation of the SEI film on the negative electrode side, improve the protection effect on the negative electrode active material, reduce the gas generation amount on the negative electrode side, slow down the risk of thermal runaway caused by gas accumulation, and can effectively improve the cycle performance of the battery cell.

[0219] In some embodiments, the mass content of the carbonate additive in the electrolyte is 2.5% to 10.0%, such as 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0% or a range composed of any two of the above values. When the mass content of the carbonate additive is within the above range, the cycle performance of the battery cell can be effectively improved.

[0220] In some embodiments, the carbonate additive includes one or more of vinylene carbonate and ethylene carbonate derivatives, and the ethylene carbonate derivatives include the compounds shown in Formula A. Formula A In Formula A, Q 1 、Q 2 、Q 3 and Q 4 each independently includes any one of a hydrogen atom, a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group, and Q1 and Q 2 and Q 3 and Q 4 are not all hydrogen atoms at the same time.

[0221] Q 1 and Q 2 and Q 3 and Q 4 are not all hydrogen atoms at the same time. In other words, at least one of Q 1 and Q 2 and Q 3 and Q 4 includes a halogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group.

[0222] Exemplarily, one of Q 1 and Q 2 and Q 3 and Q 4 includes a halogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group, and the rest are hydrogen atoms.

[0223] Exemplarily, at least two of Q 1 and Q 2 and Q 3 and Q 4 include a halogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group.

[0224] Exemplarily, at least three of Q 1 and Q 2 and Q 3 and Q 4 include a halogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group.

[0225] Exemplarily, each of Q 1 and Q 2 and Q 3 and Q 4 independently includes a halogen atom, a C1-C5 alkyl group, or a C1-C5 haloalkyl group.

[0226] Optionally, at least one of Q 1 and Q 2 and Q 3 and Q 4 includes a halogen atom or a C1-C5 haloalkyl group. The halogen atom includes a fluorine atom, a bromine atom, or a chlorine atom, etc., and may be a fluorine atom. The C1-C5 haloalkyl group includes a C1-C5 fluoroalkyl group, a C1-C5 bromoalkyl group, or a C1-C5 chloroalkyl group, etc., and may be a fluorine atom. For example, the C1-C5 fluoroalkyl group includes fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, or fluoropentyl.

[0227] When the ethylene carbonate derivative contains fluorine atoms, the ethylene carbonate derivative can form a film layer rich in F and Li on the negative electrode side, which can, while protecting the negative electrode active material, make the impedance of the film layer relatively low, and can more effectively balance the improvement of the high-temperature cycling performance and fast charging performance of the battery cell.

[0228] For example, the ethylene carbonate derivative includes one or more of the compounds represented by Formula A-1 to the compounds represented by Formula A-6.

[0229] The above materials can further improve the high-temperature cycling performance and fast charging performance of the battery cell.

[0230] Optionally, the ethylene carbonate derivative includes one or more of the compounds represented by Formula A-1 to the compounds represented by Formula A-3. Further optionally, the ethylene carbonate derivative includes the compound represented by Formula A-1.

[0231] In some embodiments, the mass content of the sulfur-containing additive in the electrolyte is 0% to 2%, such as 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0% or the range composed of any two of the above values. The sulfur-containing additive can form a dense SEI film on the negative electrode side, can effectively alleviate the risk of the carboxylate solvent penetrating the SEI film and reacting with the negative electrode active material, reduce the gas generation amount, and improve the cycling performance of the battery cell.

[0232] Taking the case where the mass content of the sulfur-containing additive is 0 as an example, it can be that the freshly prepared electrolyte does not contain the sulfur-containing additive. Or the electrolyte obtained after disassembling the battery cell does not contain the sulfur-containing additive. This situation may be that the freshly prepared electrolyte does not contain the sulfur-containing additive, or it may contain a small amount of the sulfur-containing additive, but it participates in the film-forming reaction of the SEI film during the formation process of the battery cell, resulting in the mass content of the sulfur-containing additive being 0 during the detection process.

[0233] Optionally, the freshly prepared electrolyte includes the sulfur-containing additive.

[0234] Furthermore, regarding the addition of certain substances, such as additives, to the electrolyte, due to the characteristic that additives play a role by participating in the film formation on the surface of the active material, the content of additives in the electrolyte of a battery cell is related to the state after formation, different battery life cycles, or different battery storage states. Therefore, there may be a difference in the content of additives between the freshly prepared electrolyte and the electrolyte obtained from reverse-disassembling the battery. However, those skilled in the art can know the approximate range of the content of relevant substances in the corresponding fresh electrolyte based on the performance expression level (such as the number of cycles) and residual content of the battery cell. Similarly, those skilled in the art can also know the approximate range of the content of the non-freshly prepared (i.e., reverse) electrolyte corresponding to the freshly prepared additive content based on the performance requirements of the battery cell and the storage environment.

[0235] Therefore, the additive content mentioned in the technical solution of this application can be the content of additives actively added to the fresh electrolyte, or the content of residual additives detected by reverse according to the actual battery state.

[0236] In some embodiments, the sulfur-containing additives include one or more of vinylene sulfate, divinylene sulfate, 1,3-propane sultone, butene sulfite, ethylene sulfite, and methylene methyl disulfonate.

[0237] In some embodiments, the mass content of lithium salt additives in the electrolyte is from 0% to 1%, such as 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, or a range composed of any two of the above values. The lithium salt additives cooperate to participate in film formation and can optimize the film layer components of the SEI film. The lithium salt additives can participate in the formation of an SEI film rich in inorganic substances, and the inorganic substances can improve the high-temperature stability and high-voltage stability of the SEI film, thereby improving the cycle performance of the battery cell.

[0238] When the mass content of the lithium salt additives is 0, it means that the freshly prepared electrolyte may not contain lithium salt additives, or the electrolyte obtained after disassembling the battery cell does not contain lithium salt additives.

[0239] In some embodiments, the lithium salt additives include one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium bis(oxalato)borate.

[0240] In the embodiments of the present application, the types and contents of inorganic components / lithium salts in the electrolyte have meanings well-known in the art, and can be detected by equipment and methods well-known in the art. For example, reference can be made to the standard JY / T 0575-2020 "General Rules for Ion Chromatography Analysis Methods" to qualitatively or quantitatively analyze the inorganic components / lithium salts in the electrolyte by ion chromatography analysis methods. In the embodiments of the present application, newly prepared electrolyte can be taken as a sample, free electrolyte of a fresh battery can be taken as a sample, or a battery cell that has been fully discharged (discharged to the discharge cut-off voltage so that the charged state of the battery cell is approximately 0% SOC) can be reverse disassembled, and the free electrolyte obtained from the battery cell can be taken as a sample for detection by ion chromatography analysis methods.

[0241] In the embodiments of the present application, the types and contents of organic components in the electrolyte have meanings well-known in the art, and can be detected by equipment and methods well-known in the art. For example, reference can be made to GB / T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents" to qualitatively and quantitatively analyze the organic components in the electrolyte by gas chromatography.

[0242] [Positive electrode plate] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector.

[0243] In some embodiments, when the battery cell is in a 100% charged state, the tap density of the positive electrode film layer is 2.6 g / cm 3 to 2.8 g / cm 3 . Exemplarily, when the battery cell is in a 100% charged state, the tap density of the positive electrode film layer is 2.6 g / cm 3 , 2.65 g / cm 3 , 2.7 g / cm 3 , 2.75 g / cm 3 , 2.8 g / cm 3 or the range composed of any two of the above values.

[0244] When the tap density of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell, and since the positive electrode active materials in the positive electrode film layer are stacked relatively tightly and the contact resistance between particles is small, the resistance of the electrode plate can be further reduced, thereby reducing heat generation and improving the cycle performance of the battery cell.

[0245] In some embodiments, the single-sided coating weight of the positive electrode film layer is 220 mg / 1540.25 mm 2 to 450 mg / 1540.25 mm2 , such as 220 mg / 1540.25 mm 2 , 230 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm², 260 mg / 1540.25 mm², 270 mg / 1540.25 mm², 280 mg / 1540.25 mm², 290 mg / 1540.25 mm², 300 mg / 1540.25 mm², 310 mg / 1540.25 mm², 320 mg / 1540.25 mm², 330 mg / 1540.25 mm², 350 mg / 1540.25 mm², 380 mg / 1540.25 mm², 400 mg / 1540.25 mm², 420 mg / 1540.25 mm², 450 mg / 1540.25 mm² or a range composed of any two of the above values.

[0246] When the single-sided coating weight of the positive electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell, and the heat generation per unit area of the positive electrode plate will not be too large, improving the cycle performance of the battery cell.

[0247] The upper charging limit voltage and the lower discharging cut-off voltage of the battery cell are different according to the different positive active materials. For example, when the phosphate material includes lithium iron phosphate, the upper charging limit voltage can be 3.65 V and the lower discharging cut-off voltage can be 2.0 V. Another example is that when the phosphate material includes lithium manganese iron phosphate, the upper charging limit voltage can be 4.2 V and the lower discharging cut-off voltage can be 2.0 V. Next, taking the upper charging limit voltage of 3.65 V and the lower discharging cut-off voltage of 2.0 V as an example, the state of the battery cell will be described: In the embodiment of the present application, the 100% state of charge (SOC) and the 0% state of charge (SOC) of the battery cell are defined as follows. The battery cell is charged at a constant current charging rate of 0.33C to the upper charging limit voltage, and then charged at a constant voltage to 0.05C, corresponding to the state of 100% SOC of the battery cell. The battery cell is discharged at a constant current discharging rate of 0.33C to the cut-off voltage, corresponding to the state of 0% SOC of the battery cell.

[0248] In the embodiments of the present application, the compaction density of the positive electrode film layer of the battery cell at 100% state of charge (SOC) can be detected by the following method. The positive electrode plate is disassembled from the battery cell, and the compaction density of the positive electrode film layer is measured. For example, for a single-sided coated positive electrode plate (if it is a double-sided coated plate, the positive electrode film layer on one side can be wiped off first), it is punched into small round pieces with an area of S1, weighed, and recorded as M1, and its thickness H1 is measured. Then, the positive electrode film layer of the above-mentioned weighed positive electrode plate is wiped off, the weight of the positive electrode current collector is weighed, and recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the positive electrode film layer = (the weight M1 of the positive electrode plate - the weight M0 of the positive electrode current collector) / S1, the thickness of the positive electrode film layer = the thickness H1 of the positive electrode plate - the thickness H0 of the positive electrode current collector, and the compaction density of the positive electrode film layer = the single-sided coating weight of the positive electrode film layer / the thickness of the positive electrode film layer.

[0249] In the case where the battery cell is a lithium-ion battery, The lithium-containing phosphate can have an olivine structure, and the modified compound can be a material obtained by doping modification or coating modification thereof. For example, the lithium-containing phosphate includes phosphate particles and a positive electrode coating layer, and the positive electrode coating layer coats at least a part of the surface of the phosphate particles, and the positive electrode coating layer contains carbon elements.

[0250] By surface coating the positive electrode coating layer on the phosphate particles, the conductivity of the lithium-containing phosphate can be improved, which is beneficial to the migration rate of lithium ions, improves the fast charging ability of the battery, and reduces the heat generation of the battery cell, and improves the high-temperature cycle performance of the battery cell.

[0251] Examples of the phosphate particles can include but are not limited to one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The above-mentioned materials have excellent cycle stability and can improve the cycle performance of the battery cell.

[0252] In some embodiments, the lithium-containing phosphate includes a general formula of Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1a material, wherein 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, A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge, and Ce; X includes one or more of Cl, C, N, and P; Y includes one or more of O and F.

[0253] The lithium-containing phosphate has relatively excellent cycle stability, which is beneficial to improving the cycle performance of the battery cell.

[0254] Exemplarily, the phosphate particles include one or more of LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 . During the charge and discharge process of the battery cell, the insertion and extraction and consumption of active ions such as Li will occur, and the molar content of Li is different when the battery cell is discharged to different states. Regarding the positive electrode active materials LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 etc., the molar content of Li is the initial state of the material, that is, the state before feeding. When the positive electrode active material is applied to the battery system and undergoes charge and discharge cycles, the molar content of Li may change. In the embodiments of the present application, regarding the positive electrode active materials LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 etc., the molar content of oxygen O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen O to change. Actually, the molar content of oxygen O will show fluctuations, and the above situations are all within the protection scope of the present application.

[0255] In some embodiments, based on the mass of the lithium-containing phosphate, the mass content of carbon element is 0.8% to 2.3%, such as 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 the range composed of any two of the above values.

[0256] The carbon element mainly exists in the positive electrode coating in the form of a carbon coating layer. The carbon coating layer is loose and porous, which is beneficial to increasing the specific surface area of ​​the material, and is more conducive to the effective contact between the electrolyte and the phosphate particles, and is beneficial to the transmission of lithium ions at the phase interface. In addition, when the mass content of the carbon element is within the above range, it can significantly improve the conductivity of the lithium-containing phosphate with an olivine structure, which is beneficial to improving the ionic conductivity and electronic conductivity of the lithium-containing phosphate with an olivine structure, and can improve the rapid charging capability of the battery cell at a high energy density.

[0257] In some embodiments, the positive electrode coating layer further includes one or more elements of Fe, Ti, Zr, Hf, Ge, and Sn.

[0258] In some embodiments, the positive electrode coating layer includes a general formula of Li 3-d1 Fe 2-d1 M3 d1 (PO m1 ) n1 A compound wherein 0≤d1≤1, 3≤m1≤5, 2≤n1≤4, and M3 includes one or more of Ti, Zr, Hf, Ge, and Sn.

[0259] Li 3-d1 Fe 2-d1 M3 d1 (PO m1 ) n1 The compound is a fast ion conductor having a NASICON structure, for example, one or more of lithium iron titanium phosphate Li2FeTi(PO4)3, lithium iron zirconium phosphate Li2FeZr(PO4)3, and lithium iron tin phosphate Li2FeSn(PO4)3.

[0260] Fast ion conductors with NASICON structures are materials with ultrafast ion conduction capabilities, rich three-dimensional lithium ion diffusion and transmission channels, and have the advantages of high ion conduction efficiency and strong structural stability during multiple lithium removal and insertion processes. Coating fast ion conductors with NASICON structures on the surface of phosphate particles can significantly increase the transmission rate of lithium ions during multiple lithium removal / insertion at the positive terminal, improve the ionic conductivity of the positive electrode active material, and improve the fast charging capability of the battery cell. In addition, it can also increase the gram capacity and the energy density of the corresponding battery cell.

[0261] The carbon element and the fast ion conductor can be arranged in layers. For example, the carbon element serves as an independent carbon coating layer, and the fast ion conductor serves as an independent fast ion conductor layer. The carbon coating layer can coat the surface of the phosphate particles, and the fast ion conductor layer is located on the surface of the carbon coating layer, that is, the fast ion conductor layer is located on the side of the carbon coating layer away from the phosphate particles. Or, the fast ion conductor layer can coat the surface of the phosphate particles, and the carbon coating layer is located on the surface of the fast ion conductor layer, that is, the carbon coating layer is located on the side of the fast ion conductor layer away from the phosphate particles. Of course, the carbon element and the fast ion conductor can also be arranged in the same layer.

[0262] Optionally, the carbon coating layer can be formed by carbonizing an organic carbon source (such as glucose, polyethylene glycol, etc.) on the surface of the fast ion conductor layer. The carbon coating layer can partially coat the fast ion conductor layer or completely coat the fast ion conductor layer. The setting of the carbon coating layer can significantly improve the electronic conductivity of the phosphate particles, make up for the defect of poor electronic conduction performance of the phosphate particles, and improve the energy density of the battery cell. The positive electrode active material of this application uses phosphate particles as the base material, giving full play to the advantages of low cost, high reliability in use, and good cycle stability of the phosphate particles. At the same time, the positive electrode coating layer (fast ion conductor layer and carbon coating layer) is used to solve the disadvantages of poor electronic conductivity and ion conductivity. The battery cell prepared from the positive electrode active material of this application can improve the energy density of the battery cell on the premise of excellent cycle performance. In the embodiments of this application, the content of elements in the positive electrode active material has the meaning well-known in the art, and can be detected by equipment and methods well-known in the art. For example, referring to EPA 6010D-2014, it is tested by inductively coupled plasma atomic emission spectrometry and determined by inductively coupled plasma optical emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400). After discharging the battery cell to 0% state of charge (SOC) and disassembling the positive electrode plate, it is cleaned with DMC and dried, and then impurities are removed by high-temperature calcination. Then, 0.4 g of the positive electrode active material is weighed, and 10 ml (50% concentration) of aqua regia is added thereto. Then it is placed on a flat plate at 180 °C for 30 min. After digestion on the flat plate, it is fixed to a volume of 100 mL, and quantitative testing is carried out by the standard curve method.

[0263] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. There is no particular limitation on the type of the positive electrode conductive agent in the embodiments of this application. As an example, the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, based on the mass of the positive electrode film layer, the mass content of the positive electrode conductive agent is ≤5%.

[0264] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. There is no particular limitation on the type of the positive electrode binder in the embodiments of the present application. As an example, the positive electrode binder may include one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins. In some embodiments, based on the mass of the positive electrode film layer, the mass content of the positive electrode binder is ≤5%.

[0265] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of the metal foil, one or more foils of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material of the metal material layer may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0266] In some embodiments, the thickness of the positive electrode current collector is 10 μm to 15 μm. When the thickness of the positive electrode current collector is within the above range, it is beneficial to improve the overcurrent capacity and the fast charging capacity of the battery cell.

[0267] The positive electrode film layer is usually formed by coating a positive electrode paste on the positive electrode current collector and then drying and cold pressing. The positive electrode paste is usually formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring evenly. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.

[0268] The positive electrode tab does not exclude other additional functional layers other than the positive electrode film layer. For example, in some embodiments, the positive electrode tab of the embodiments of the present application further includes a positive electrode conductive layer sandwiched between the positive electrode current collector and the positive electrode film layer and disposed on the surface of the positive electrode current collector. In some other embodiments, the positive electrode tab of the embodiments of the present application further includes a protective layer covering the surface of the positive electrode film layer.

[0269] In some embodiments, the positive electrode tab further includes a positive electrode conductive layer, and the positive electrode conductive layer is located between the positive electrode film layer and the positive electrode current collector. The positive electrode conductive layer can further improve the conductivity of the positive electrode tab and reduce the heat generation of the positive electrode tab, thereby reducing the heat generation of the battery cell.

[0270] In some embodiments, the thickness of the positive electrode conductive layer is from 0.5 μm to 2 μm. Exemplarily, the thickness of the positive electrode conductive 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 a range composed of any two of the above values.

[0271] When the thickness of the positive electrode conductive layer is within the above range, the conductivity of the positive electrode plate can be further improved, the heat generation of the positive electrode plate can be reduced, thereby reducing the heat generation of the battery cell, and the fast charging performance and high-temperature cycling performance of the battery cell at high energy density can be improved.

[0272] In the embodiments of the present application, the thickness of the positive electrode conductive layer has the meaning well known in the art, and can be detected by devices and methods well known in the art. For example, tomographic scanning of the positive electrode plate can be performed to directly measure the thickness of the positive electrode conductive layer.

[0273] In some embodiments, the positive electrode conductive layer includes one or more of a positive electrode conductive agent and a positive electrode binder.

[0274] Optionally, the mass content of the positive electrode conductive agent in the positive electrode conductive layer is from 30% to 50%. Exemplarily, the mass content of the positive electrode conductive agent is 30%, 35%, 40%, 45%, 50% or a range composed of any two of the above values.

[0275] Exemplarily, the positive electrode conductive agent of the positive electrode conductive layer includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The positive electrode conductive agent of the positive electrode conductive layer can improve the conductivity of the positive electrode conductive layer, thereby improving the conductivity of the positive electrode plate and reducing the heat generation amount of the battery cell.

[0276] Optionally, the mass content of the positive electrode binder in the positive electrode conductive layer is from 50% to 70%. Exemplarily, 50%, 60%, 65%, 70% or a range composed of any two of the above values.

[0277] Exemplarily, the positive electrode binder of the positive electrode conductive layer includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins. The positive electrode binder of the positive electrode conductive layer can improve the bonding performance between the positive electrode current collector and the positive electrode film layer, and improve the structural stability of the positive electrode plate.

[0278] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0279] In some embodiments, when the battery cell is in a 100% charged state, the tap density of the negative electrode film layer is 1.2 g / cm 3 to 1.4 g / cm 3 . Exemplarily, when the battery cell is in a 100% charged state, the tap density of the negative electrode film layer is 1.20 g / cm 3 , 1.22 g / cm 3 , 1.25 g / cm 3 , 1.28 g / cm 3 , 1.3 g / cm 3 , 1.32 g / cm 3 , 1.35 g / cm 3 , 1.40 g / cm 3 or a range composed of any two of the above values.

[0280] When the tap density of the negative electrode film layer is within the above range, it is beneficial to improve the energy density of the battery cell, and since the negative electrode active materials in the negative electrode film layer are stacked relatively tightly and the contact resistance between particles is small, the resistance of the electrode plate can be further reduced, thereby reducing heat generation and reducing the amount of gas generated by the decomposition of carboxylic ester solvents due to heat accumulation, and improving the cycle performance of the battery cell.

[0281] In the embodiments of the present application, the tap density of the negative electrode film layer when the battery cell is in a 100% charged state has the meaning well-known in the art, and can be detected by using equipment and methods well-known in the art, and its detection method is like the tap density test method of the positive electrode film layer.

[0282] In some embodiments, the single-sided coating weight of the negative electrode film layer is 100 mg / 1540.25 mm 2 to 200 mg / 1540.25 mm 2 . Exemplarily, the single-sided coating weight of the negative electrode film layer is 100 mg / 1540.25 mm 2 , 110 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 , 145 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 155 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm 2 , 165 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 , 175 mg / 1540.25 mm 2 , 200 mg / 1540.25 mm 2 or a range composed of any two of the above values. When the single-sided coating weight of the negative electrode film layer is within the above range, the energy density of the battery cell can be improved; the heat generation per unit area of the negative electrode plate will not be too large, and the high-temperature cycling performance of the battery cell can be improved while taking it into account.

[0283] In the embodiments of the present application, the single-sided coating weight of the negative electrode film layer has the meaning well-known in the art, and can be detected by using the equipment and methods well-known in the art. The negative electrode plate is disassembled from the battery cell, and the compaction density of the negative electrode film layer is measured. For example, a single-sided coated negative electrode plate (if it is a double-sided coated plate, one side of the negative electrode film layer can be wiped off first) is punched into small round pieces with an area of S1, weighed, recorded as M1, and its thickness H1 is measured. Then, the negative electrode film layer of the above weighed negative electrode plate is wiped off, and the weight of the negative electrode current collector is weighed, recorded as M0, and its thickness H0 is measured. The single-sided coating weight of the negative electrode film layer = (the weight M1 of the negative electrode plate - the weight M0 of the negative electrode current collector) / S1.

[0284] In the embodiments of the present application, the negative electrode film layer includes at least one layer of film layer, and a single layer of film layer can be used, or at least two layers of film layer can be used. The negative electrode film layer can include two layers of film layer, three layers of film layer, four layers of film layer, or even more layers of film layer.

[0285] In the embodiments of the present application, the negative electrode active material includes a carbon-based material, and the carbon-based material includes graphite particles. The graphite particles have high cycle stability and can improve the cycle performance of the battery cell. The positive electrode active material of the present application is mainly a phosphate system, and the negative electrode active material is mainly a carbon-based material system. When the two are used in combination, the cycle performance of the battery cell is relatively excellent.

[0286] In some embodiments, the volume-average particle size Dv50 of the graphite particles is from 9.5 μm to 16.5 μm, such as, for example, 8.5 μm, 9 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.8 μm, 11 μm, 11.2 μm, 11.5 μm, 11.8 μm, 12 μm, 12.2 μm, 12.5 μm, 12.8 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm or a range composed of any two of the above values.

[0287] The volume-average particle size of the graphite particles is relatively small, resulting in a short solid-phase migration path for lithium ions, which can improve the fast-charging ability of the battery cell. However, under fast-charging conditions, the side reaction between the small-sized graphite particles and the carboxylic ester solvents in the electrolyte is relatively intense. The electrolyte is further added with a first additive, which can preferentially form a film on the negative electrode side, providing excellent protection for the negative electrode active material, reducing the risk of side reactions occurring on the negative electrode side, and improving the cycle performance of the battery cell.

[0288] In the embodiments 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, and can be detected by using equipment and methods well known in the art. For example, taking the positive electrode active material as a sample, according to the test standard GB / T 19077-2016, the Dv50 of the particles is tested by a Mastersizer 2000E laser particle size analyzer, etc.

[0289] In some embodiments, the powder resistivity of the graphite particles is from 0.005 Ω·cm to 0.04 Ω·cm. Exemplarily, the powder resistivity of the graphite particles can be 0.04 Ω·cm, 0.035 Ω·cm, 0.03 Ω·cm, 0.025 Ω·cm, 0.02 Ω·cm, 0.015 Ω·cm, 0.01 Ω·cm, 0.005 Ω·cm or a range composed of any two of the above values.

[0290] The powder resistivity of the graphite particles is relatively low, resulting in a relatively low resistance of the negative electrode sheet and less heat generation of the battery cell, which can reduce the amount of gas generated by the decomposition of carboxylic ester solvents due to heat accumulation and improve the cycle performance of the battery cell.

[0291] In the embodiments of the present application, the powder resistivity of the negative electrode active material has the meaning well known in the art and can be detected by using equipment and methods well known in the art. For example, according to the test standard GB / T30835-2014, a PRCD1100 powder resistivity meter is used for testing.

[0292] In some embodiments, the graphite particles include graphite bulk particles and a negative electrode coating layer. The graphite bulk particles include secondary particles, and the secondary particles include a plurality of primary particles. The negative electrode coating layer coats the surface of the graphite bulk particles, and the negative electrode coating layer includes carbon elements. The carbon in the negative electrode coating layer is mainly amorphous carbon. Amorphous carbon refers to a transition carbon material with a very low degree of graphitization crystallization and an approximate amorphous form (or no fixed shape and periodic structural rules). In the present application, amorphous carbon refers to the product after carbonization treatment of an organic carbon source.

[0293] The graphite bulk particles include secondary particles. The migration path of lithium ions in the graphite bulk particles is relatively long, and the migration path in the primary particles is relatively short, which can improve the migration rate of lithium ions. The negative electrode coating layer has more end faces and defects, resulting in a larger number of sites where lithium ions can be inserted and extracted, making the conductivity of the negative electrode coating layer relatively excellent. It can reduce the internal resistance of the negative electrode sheet, reduce the heat generation of the battery cell, and improve the fast charging performance and high-temperature cycling performance of the battery cell at high energy density.

[0294] Exemplarily, the graphite bulk particles include one or more of artificial graphite and natural graphite, and may be artificial graphite.

[0295] Optionally, based on the mass of the graphite particles, the mass content of carbon elements in the negative electrode coating layer is 2% to 5%. Exemplarily, the mass content of carbon elements in the negative electrode coating layer is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or the range composed of any two of the above values.

[0296] When the mass content of carbon elements in the negative electrode coating layer is within the above range, it can further reduce the internal resistance of the negative electrode sheet, reduce the heat generation of the battery cell, and improve the high-temperature cycling performance of the battery cell at high energy density.

[0297] In the embodiments of the present application, the graphite particles can be prepared by methods well known in the art. Taking the graphite bulk particles as artificial graphite as an example, the preparation method includes: providing artificial graphite and an organic carbon source, mixing the two, and after carbonization treatment, forming a negative electrode coating layer on at least part of the surface of the artificial graphite particles.

[0298] Optionally, the organic carbon source includes one or more of coal tar pitch, petroleum pitch, phenolic resin, and coconut shell. Further optionally, the organic carbon source includes petroleum pitch. Optionally, the softening point of coal tar pitch and petroleum pitch is below 250°C.

[0299] Optionally, the carbonization treatment temperature is 700°C to 1800°C. Optionally, the carbonization treatment temperature is 1000°C to 1300°C. When the carbonization treatment temperature is within a suitable range, the organic carbon source can be carbonized and a negative electrode coating layer containing amorphous carbon can be formed on at least part of the surface of the artificial graphite.

[0300] Optionally, the carbonization treatment time is 1 h to 6 h.

[0301] In some embodiments, the carbon-based material may further include natural graphite. Specifically, the carbon-based material may include graphite particles, or the carbon-based material may include graphite particles and natural graphite. Optionally, the carbon-based material is graphite particles.

[0302] In some embodiments, the negative electrode active material may further include a silicon-based material in addition to graphite particles. The introduction of the silicon-based material can improve the capacity of the negative electrode active material and increase the energy density of the battery cell.

[0303] Optionally, based on the mass of the negative electrode film layer, the mass content of silicon element in the silicon-based material is 1% to 5%, optionally 1% to 6%. Exemplarily, the mass content of silicon element in the silicon-based material is 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 a range composed of any two of the above values.

[0304] When the mass content of silicon element in the silicon-based material is within the above range, the capacity of the negative electrode active material can be improved, and the energy density of the battery cell can be improved.

[0305] Optionally, the silicon-based material may include one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite and silicon alloy material.

[0306] In some embodiments, the negative electrode active material may further include one or more of a tin-based material and lithium titanate in addition to the above-mentioned carbon-based material and optional silicon-based material. The tin-based material may include one or more of elemental tin, tin oxide and tin alloy material.

[0307] The qualitative and quantitative determination of each substance or each element in this application can be detected by suitable equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc. And those skilled in the art can also adaptively change some detection steps / instrument parameters, etc. from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used in combination for qualitative or quantitative determination.

[0308] For example, the negative electrode sheet is placed in a solvent such as water for soaking to separate the negative electrode active material from the negative electrode current collector. Each substance in the negative electrode film layer is obtained by suction filtration and used as a test sample. The mass content of silicon element can be obtained by using an inductively coupled plasma - emission spectrometer of model ICAP7400 from Thermo Fisher Scientific Company in the United States and referring to the standard of GB / T30902 - 2014.

[0309] For example, the present application can also perform X - ray powder diffraction testing and qualitative analysis on the negative electrode sheet or the negative electrode active material in combination with the general rules of JIS / K0131 - 1996 X - ray diffraction analysis method.

[0310] Artificial graphite and natural graphite can be distinguished by the SEM cross - sectional view taken by a scanning electron microscope (SEM). There are voids between flaky structures in the SEM cross - sectional view of natural graphite, while the SEM cross - sectional view of artificial graphite is dense and has no obvious gaps, or they can be distinguished by the XRD spectrum obtained by the X - ray diffraction method. There are obvious 2H phase and 3R phase in the XRD spectrum of natural graphite, and only the 2H phase exists in the XRD spectrum of artificial graphite.

[0311] In some embodiments, the negative electrode film layer further includes a negative electrode binder. The negative electrode binder includes one or more of styrene - butadiene rubber (SBR), water - soluble unsaturated resin SR - 1B, water - based acrylic resins (for example, polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, based on the total weight of the negative electrode film layer, the mass content of the negative electrode binder is ≤5%.

[0312] In some embodiments, the negative electrode film layer optionally further includes a negative electrode conductive agent. There is no particular limitation on the type of the negative electrode conductive agent in the embodiments of the present application. As an example, the negative electrode conductive agent can include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, based on the total weight of the negative electrode film layer, the mass content of the negative electrode conductive agent is ≤5%.

[0313] In some embodiments, the negative electrode film layer optionally further includes other additives. As an example, other additives can include thickeners, dispersants, etc., such as sodium carboxymethyl cellulose (CMC - Na), PTC thermistor materials, etc. In some embodiments, based on the total weight of the negative electrode film layer, the mass content of other additives is ≤2%.

[0314] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As an example of the metal foil, one or more foils of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0315] In some embodiments, the thickness of the negative electrode current collector is 4 μm to 6 μm, such as 4 μm, 5 μm, 6 μm, or a range composed of any two of the above values. When the thickness of the negative electrode current collector is within the above range, it is beneficial to improve the overcurrent capacity and the fast charging ability of the battery cell.

[0316] The negative electrode film layer is usually formed by coating a negative electrode paste on the negative electrode current collector and then drying and cold pressing. The negative electrode paste is usually formed by dispersing a negative electrode active material, an optional conductive agent, an optional binder, and other optional additives in a solvent and stirring evenly. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0317] The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of the embodiments of the present application further includes a negative electrode conductive layer sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0318] In some embodiments, the negative electrode sheet further includes a negative electrode conductive layer, and the negative electrode conductive layer is located between the negative electrode film layer and the negative electrode current collector. The negative electrode conductive layer can further improve the conductivity of the negative electrode sheet, reduce the heat generation of the negative electrode sheet, thereby reducing the heat generation of the battery cell, and improving the fast charging performance and high temperature cycle performance of the battery cell.

[0319] In some embodiments, the thickness of the negative electrode conductive layer is 0.5 μm to 2 μm. Exemplarily, the thickness of the negative electrode conductive 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 a range composed of any two of the above values.

[0320] When the thickness of the negative conductive layer is within the above range, the conductivity of the negative electrode plate can be further improved, the heat generation of the negative electrode plate can be reduced, thereby reducing the heat generation of the battery cell, and the energy density of the battery cell can be improved while taking into account.

[0321] In the embodiments of the present application, the thickness of the negative conductive layer has the meaning well known in the art, and can be detected by using the equipment and methods well known in the art. For example, tomographic scanning is performed on the negative electrode plate to directly measure the thickness of the negative conductive layer.

[0322] In some embodiments, the negative conductive layer includes one or more of a negative conductive agent and a negative binder. The negative conductive agent of the negative conductive layer can improve the conductivity of the negative conductive layer, thereby improving the conductivity of the negative electrode plate and reducing the heat generation of the battery cell. The negative binder of the negative conductive layer can improve the bonding performance between the negative current collector and the negative film layer, and improve the structural stability of the negative electrode plate.

[0323] In some embodiments, the negative conductive layer may further optionally include other additives. As an example, the other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0324] Optionally, the mass content of the negative conductive agent in the negative conductive layer is 20% to 40%. Exemplarily, the mass content of the negative conductive agent is 20%, 25%, 30%, 35%, 40% or a range composed of any two of the above values.

[0325] Exemplarily, the negative conductive agent of the negative conductive layer includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0326] Optionally, the mass content of the negative binder in the negative conductive layer is 60% to 80%. Exemplarily, 60%, 65%, 70%, 75%, 80% or a range composed of any two of the above values.

[0327] Exemplarily, the negative binder of the negative conductive layer includes one or more of styrene-butadiene rubber SBR, water-soluble unsaturated resin SR-1B, water-based acrylic resin, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan.

[0328] [Separator membrane] In the embodiments of the present application, the separator membrane is disposed between the positive electrode plate and the negative electrode plate to isolate the positive electrode plate and the negative electrode plate.

[0329] In the embodiments of the present application, the separator membrane includes a base film with a porous structure.

[0330] In some embodiments, the base film comprises one or more of glass fiber, non-woven fabric, and polyolefin. The base film can be a single-layer film or a multi-layer composite film, without particular limitation. When the base film is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0331] Optionally, the polyolefin comprises one or more of polyethylene, polypropylene, and polyvinylidene fluoride.

[0332] In some embodiments, the porosity of the separator is 20% to 70%, optionally 35% to 60%. Exemplarily, the porosity of the separator is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or a range composed of any two of the above values.

[0333] When the porosity of the separator in the embodiments of the present application is within the above range, the migration ability of lithium ions in the separator can be improved, the internal resistance of the battery cell can be further reduced, thereby reducing heat generation, and improving the fast charging performance and high-temperature cycling performance of the battery cell at high energy density.

[0334] Optionally, the porosity of the base film is 20% to 70%, optionally 35% to 60%.

[0335] In the embodiments of the present application, the porosity refers to the percentage of the pore volume of the separator occupying the total volume of the separator. The porosity can be tested in accordance with the standard GB / T36363-2018 "Polyolefin Separator for Battery Cell". It should be noted that in the actual testing process, the testing process may be slightly different from the standard according to the differences in testing instruments, testing errors, and in order to eliminate the influence on the porosity test as much as possible, so as to obtain a more accurate test value.

[0336] In some embodiments, the thickness of the separator is 4μm to 12μm. Exemplarily, the thickness of the separator is 4μm, 5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm or a range composed of any two of the above values.

[0337] When the thickness of the separator is within the above range, the migration path of lithium ions in the separator is shorter, the internal resistance of the battery cell can be further reduced, thereby reducing heat generation, and improving the fast charging performance and high-temperature cycling performance of the battery cell at high energy density.

[0338] In the embodiments of the present application, the separator can be a base film. Optionally, the separator further comprises a functional layer disposed on at least one side of the base film. The functional layer can comprise inorganic particles to improve the heat resistance of the separator. Optionally, the functional layer is disposed on both sides of the base film.

[0339] In some embodiments, the functional layer includes a first functional layer and a second functional layer. The first functional layer is located on one side of the base film and includes first inorganic particles. The second functional layer is located on the other side of the base film and includes composite particles. The composite particles include second inorganic particles and a plurality of non-fluoropolymer particles, and the second inorganic particles are attached to the surface of the non-fluoropolymer particles and / or dispersed inside the non-fluoropolymer particles.

[0340] The first functional layer and the second functional layer have good heat resistance, which can improve the heat resistance of the separator.

[0341] Optionally, the first functional layer may include a binder, optionally one or more of a fluorine-containing binder or a polyacrylic acid binder, such as polyvinylidene fluoride.

[0342] Optionally, the first inorganic particles include one or more of silica, alumina, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. The above first inorganic particles can improve the heat resistance of the first functional layer.

[0343] Optionally, the average particle size of the first inorganic particles is 5 nm to 100 nm, optionally 10 nm to 100 nm, optionally 5 nm to 20 nm. Exemplarily, 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 a range composed of any two of the above values. When the average particle size of the first inorganic particles is within the above range, it is beneficial to improve the heat resistance and compression modulus of the composite particles.

[0344] In the embodiments of the present application, the meaning of the thickness of the film layer is well-known in the art and can be detected using the well-known meaning and equipment in the art. For example, a newly prepared separator can be taken as a sample, or a battery monomer that has been discharged (discharged to the lower cut-off voltage so that the charged state of the battery is about 0% SOC) can be disassembled in reverse, the separator is obtained from the battery monomer, and the separator is dried and used as a sample. The separator is cut off with an ion beam cutter to form a cross-section. Subsequently, a scanning electron microscope is used to measure the thickness of the cross-section of the separator and its respective layers.

[0345] The non-fluoropolymer particles in the second functional layer refer to polymers that are non-fluorinated polymers. For example, the non-fluoropolymer particles include acrylate copolymers. Optionally, the acrylate copolymers include acrylate-acrylonitrile-acrylamide-propylene copolymers. The acrylate copolymers have excellent adhesion properties and relatively high adhesion stability with the base film. The molar ratio of each monomer in the copolymer can be any ratio, such as 35%:30%:15%:20%, or 40%, 20%, 10%, 30%, or 45%, 15%, 20%, 20%, etc.

[0346] The second inorganic particles in the composite particles prevent the non-fluoropolymer particles from easily adhering to each other due to the high-temperature treatment during the granulation process, creating pores in the composite particles, which is beneficial for the transport of lithium ions and improves the ionic conductivity of the separator. Moreover, the second inorganic particles can also increase the compression modulus of the composite particles. During charge and discharge processes, the composite particles are not easily deformed, making the structure of the separator more stable, which can enhance the kinetic performance of the battery monomer and improve the fast charging performance. Optionally, compared with the first functional layer, the second functional layer is disposed closer to the negative electrode tab. Since the composite particles are not easily deformed, the separator basically does not cause side effects such as extrusion to the negative electrode tab, ensuring the stable kinetic performance of the negative electrode tab. Correspondingly, the first functional layer is disposed closer to the positive electrode tab.

[0347] Optionally, the second 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. Optionally, the second inorganic particles include silicon oxide. The above-mentioned second inorganic particles can improve the heat resistance of the second functional layer and can cooperate with the non-fluoropolymer 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 monomer.

[0348] The average particle size of the second inorganic particles is from 5 nm to 100 nm, optionally from 10 nm to 100 nm, and optionally from 5 nm to 20 nm. Exemplarily, 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 a range composed of any two of the above values. When the average particle size of the second inorganic particles is within the above range, it is beneficial to improve the heat resistance and compression modulus of the composite particles.

[0349] In the embodiments of the present application, the average particle size of the second inorganic particles has the meaning well-known in the art and can be detected by equipment and methods well-known in the art. For example, after obtaining the separator membrane and drying it as a sample, the separator membrane is cut by an ion beam cutter to form a cross-section. Subsequently, a scanning electron microscope is used to measure the particle size of the second inorganic particles in the separator membrane. The particle sizes of multiple, for example, 50 second inorganic particles are measured, and their average value is calculated as the average particle size of the second inorganic particles.

[0350] Embodiment The following examples more specifically describe the content disclosed in the embodiments of the present application. These examples are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the embodiments of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the examples are all commercially available.

[0351] Example 1 1. Preparation of the positive electrode sheet The positive electrode sheet includes a positive electrode current collector, a positive electrode film layer, and a positive electrode conductive layer. The positive electrode film layer is disposed on both sides of the positive electrode current collector, and the positive electrode conductive layer is located between the positive electrode current collector and the positive electrode film layer. The positive electrode current collector is aluminum foil.

[0352] The positive electrode conductive layer on the positive electrode current collector is a film layer formed by uniformly coating a mixture of a positive electrode conductive agent, superconducting carbon, a positive electrode binder, polyvinylidene fluoride (PVDF), and a solvent, N-methylpyrrolidone (NMP), on the surface of the positive electrode current collector and drying it. The thickness is 1 μm. The mass content of the positive electrode conductive agent in the positive electrode conductive layer is 40%, and the mass content of the positive electrode binder is 60%.

[0353] The positive electrode film layer includes a film layer formed by uniformly coating a positive electrode slurry (solvent: N-methylpyrrolidone (NMP)) on the surface of the positive electrode conductive layer, followed by drying and cold pressing. The positive electrode film layer includes a positive electrode active material, a binder, polyvinylidene fluoride (PVDF), and a conductive agent, acetylene black, in a weight ratio of 97:2:1.

[0354] The positive electrode active material includes lithium iron phosphate particles and a positive electrode coating layer. The positive electrode coating layer coats the surface of the lithium iron phosphate particles. The positive electrode coating layer includes lithium iron titanium phosphate Li 2 FeTi(PO 4 ) 3 and carbon element. The mass content of the carbon element is 1.12%.

[0355] The single-sided coating weight of the positive electrode film layer is 263 mg / 1540.25 mm 2 。

[0356] 2. Preparation of the negative electrode plate The negative electrode plate includes a negative electrode current collector, a negative electrode film layer, and a negative electrode conductive layer. The negative electrode film layer is disposed on both sides of the negative electrode current collector, and the negative electrode conductive layer is located between the negative electrode current collector and the negative electrode film layer. The negative electrode current collector is a copper foil.

[0357] The negative electrode conductive layer on the negative electrode current collector is a film layer formed by uniformly coating a mixture of a negative electrode conductive agent superconducting carbon, a negative electrode binder styrene-butadiene rubber (SBR), a thickening agent sodium carboxymethyl cellulose (CMC-Na), and a solvent water on the surface of the negative electrode current collector and drying. The thickness is 1 μm. The mass content of the negative electrode conductive agent in the negative electrode conductive layer is 35%, the mass content of the negative electrode binder in the negative electrode conductive layer is 60%, and the mass content of the thickening agent in the negative electrode conductive layer is 5%.

[0358] The negative electrode film layer includes a film layer formed by uniformly coating a negative electrode slurry (with deionized water as the solvent) on the surface of the negative electrode conductive layer and drying and cold pressing.

[0359] The negative electrode film layer includes a negative electrode active material, a conductive agent acetylene black, a negative electrode binder styrene-butadiene rubber, and a thickening agent sodium carboxymethyl cellulose with a mass ratio of 96.5:0.5:2:1. The graphite particles include artificial graphite and a negative electrode coating layer. The negative electrode coating layer covers the surface of the artificial graphite, and the mass content of carbon element in the negative electrode coating layer is 3.5%. The Dv50 of the graphite particles is 11.3 μm.

[0360] The single-sided coating weight of the negative electrode film layer is 120 mg / 1540.25 mm 2 。

[0361] The length of the negative electrode film layer is 3 mm larger than the length of the positive electrode film layer, and the width of the negative electrode film layer is 3 mm larger than the length of the positive electrode film layer.

[0362] 3. Separator The separator includes a base film and functional layers disposed on both sides of the base film. The base film includes polyethylene with a thickness of 7 μm and a porosity of 42%; The functional layer includes a first functional layer and a second functional layer. The first functional layer is a film layer formed by coating alumina particles and a binder polyvinylidene fluoride on one side of the base film, with a thickness of 1 μm and an average particle size of 10 nm for the alumina particles; The second functional layer is a film layer formed by coating a composite particle composed of polyacrylate and silica particles dispersed on the polyacrylate on the other side of the base film, with a thickness of 1 μm and an average particle size of 10 nm for the silica particles.

[0363] 4. Preparation of the electrolyte The electrolyte includes an organic solvent, a lithium salt, and an additive.

[0364] After mixing the components of each organic solvent, the lithium salt and the additive are added to prepare the electrolyte.

[0365] The organic solvent includes a chain carboxylic acid ester solvent (ethyl acetate) with a mass content of 39%, ethylene carbonate EC with a mass content of 27.3%, and dimethyl carbonate with a mass content of 11.7%. The mass contents of the components in the organic solvent are calculated based on the mass of the electrolyte.

[0366] The mass content of the additive is 7%, and it includes vinylene carbonate VC, fluoroethylene carbonate FEC, ethylene sulfite ES, and lithium difluorooxalate borate LiDFOB with a mass ratio of 3.5:2.5:0.5:0.5.

[0367] The lithium salt includes lithium bis(fluorosulfonyl)imide LiFSI with a mass content of 5% and lithium hexafluorophosphate LiPF6 with a mass content of 10%. The mass content of the lithium salt is calculated based on the mass of the electrolyte.

[0368] 5. Preparation of the battery cell The above positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolation role, obtaining a stacked electrode assembly. The electrode assembly is placed in a housing, and positive and negative terminals are provided on the housing. After baking, the electrolyte is injected, and through processes such as vacuum packaging, standing, formation, and shaping, the battery cell is obtained.

[0369] The housing includes an aluminum shell with a cuboid structure. The thickness of the largest surface of the cuboid structure (i.e., the large surface of the shell) is 0.5 mm.

[0370] The energy density of the battery cell is 423 Wh / L.

[0371] The compaction density of the positive electrode film layer of the battery cell at 100% SOC is 2.67 g / cm 3 , and the compaction density of the negative electrode film layer at 100% SOC is 1.33 g / cm 3 .

[0372] 6. Preparation of the battery device A plurality of battery cells are sequentially arranged along their own thickness direction (parallel to the first direction), and heat insulation members are provided between adjacent two battery cells. Heat insulation members are provided on both sides of the plurality of battery cells along the first direction (such as Figure 10 the arrangement form), and the above components are assembled in a box to form a battery device.

[0373] The battery cells are placed vertically. The dimension along the second direction can be understood as the height dimension of the battery cell, and the dimension along the third direction can be understood as the width dimension of the battery cell.

[0374] Accordingly, the dimension of the heat insulation member in the second direction can be understood as the height dimension of the heat insulation member, and the dimension in the third direction can be understood as the width dimension of the heat insulation member.

[0375] The thickness of the heat insulation member is 0.8 mm, the height L 2 is 106 mm, and the width H 2 is 304 mm. The cross-sectional area S perpendicular to its own thickness direction 2 is 32224 mm 2 .

[0376] The height L of the battery cell 1 is 112 mm, and the width H 1 is 312 mm. The cross-sectional area perpendicular to its own thickness direction is 34944 mm 2 .

[0377] L 2 / L 1 is 0.95, L 1 -L 2 is 6 mm, H 2 / H 1 is 0.97, H 2 -H 1 is 8 mm, S 2 / S 1 is 0.92.

[0378] Comparative Example 1 A battery device was prepared by a method similar to that of Example 1. Different from Example 1, no heat insulation member was provided in the battery device.

[0379] Performance Test 1. Thermal runaway test of the battery device As Figure 15 and Figure 16 , First step: Take 5 battery cells of the same specification as test samples. Charge the battery cells at a constant current of 0.33C to the charging cut-off voltage of 3.6V, and then charge at a constant current of 0.1C to the charging cut-off voltage of 3.65V to adjust the SOC state of the battery cells to 100% Second step: Arrange the 5 battery cells in the direction of their own thickness. The 5 battery cells are connected in series, and the battery cells are basically aligned in the length, thickness, and width directions. As Figure 15 the arranged form, set the heat insulation member 40, and then apply a clamping force of 3000N to the 5 juxtaposed battery cells with the clamp 60 to assemble them into a 1P5S module; the height of the clamp 60, the height of the heat insulation member 40, and the height of the battery cells are the same; Step 3: Label the battery cell in the middle of the five battery cells as the triggering battery 72, and define the remaining battery cells as the first test batteries 71. Use a needle puncture to trigger the triggering battery 72 in the middle.

[0380] As Figure 16 shown, label the triggering position C. The position C is located at the geometric center of the bottom wall of the triggering battery 72, and the bottom wall and the end cover are oppositely arranged along the length direction of the triggering battery 72. Place the 1P5S module in a sealed box (only the position C of the triggering battery 72 is exposed in the sealed box).

[0381] Step 4: Use an 8-mm flat-head needle to puncture and trigger the position C from the bottom (the needle head of the flat-head needle is perpendicular to the length direction of the battery cell). Puncture and trigger the above-mentioned triggering battery 72 at a speed of 1 mm / s until it gets out of control. Observe for 2 h after the test, then disassemble the box, and observe whether the first test batteries 71 have phenomena such as the opening of the pressure relief component (such as the explosion-proof valve) and the thermal runaway phenomenon, and measure the weight of the first test batteries 71, so as to evaluate the thermal runaway phenomenon of the battery cells.

[0382] 2. The number of cycles for the battery cell to reach 70% SOH At 60 °C, charge the battery cell at a constant current of 0.8C to the charging cut-off voltage of 3.6V, then charge it at a constant current of 0.1C to the charging cut-off voltage of 3.65V, and let it stand for 30 min; discharge it at a constant current of 1C to 2.83V, and let it stand for 30 min. This is one charge-discharge cycle. Repeat the above charge-discharge cycle steps until the cycle capacity retention rate (i.e., Cn / C0×100%) is 70%, and record the number of cycles. The more the number of cycles, the better the cycle performance of the battery cell.

[0383] When performing the charge-discharge test on the battery cell above, the battery cell can be assembled in a battery device, and the required charge-discharge strategy can be regulated through the battery management system for testing.

[0384] The test results are shown in Table 1.

[0385] Table 1

[0386] An adjacent battery cell refers to a battery cell adjacent to the triggering battery.

[0387] In Comparative Example 1, during normal cyclic operation, the cycle performance is relatively excellent; however, since no heat insulation component is provided, when the triggering battery undergoes thermal runaway, the heat will quickly spread to the adjacent battery cells, triggering the thermal runaway of other battery cells, resulting in poor reliability in the use of the battery cells.

[0388] Compared with Comparative Example 1, in Example 1, a heat insulation member is provided in the battery device, and the battery device still has relatively excellent cycle performance; moreover, the heat insulation member can effectively alleviate the problem of heat diffusion, reduce the risk of thermal runaway, and improve the use reliability of the battery cell.

[0389] Examples 2-1 to 2-6 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the mass contents of fluorosulfonylimide salt and lithium hexafluorophosphate were adjusted, and the thickness of the heat insulation member was adjusted.

[0390] Example 2-7 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the type of fluorosulfonylimide salt was adjusted.

[0391] Comparative Examples 2-1 and 2-2 The battery cells were prepared by a method similar to that of Example 1. Different from Example 1, the mass contents of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate were adjusted, and the thickness of the heat insulation member was adjusted.

[0392] The test results are shown in Table 2.

[0393] Table 2

[0394] In Comparative Example 2-1, a heat insulation member is provided in the battery device, which can effectively isolate the heat diffusion between other battery cells and reduce the risk of thermal runaway; however, the mass content of lithium bis(fluorosulfonyl)imide is relatively low. Although it can reduce the usage amount of lithium hexafluorophosphate in the electrolyte, the content of hydrofluoric acid contained in the electrolyte is still relatively high, resulting in the destruction of the SEI film by hydrofluoric acid and deteriorating the cycle performance of the battery cell.

[0395] The electrolyte of Comparative Example 2-2 contains a large amount of lithium bis(fluorosulfonyl)imide, which can effectively improve the cycle life of the battery device. Although a heat insulation member is provided in the battery device of Comparative Example 2-2, due to the too high mass content of lithium bis(fluorosulfonyl)imide in the electrolyte, the thermal stability of the electrolyte is poor. When thermal runaway occurs, a large amount of heat will be released, and the large amount of heat may still trigger the thermal runaway of adjacent battery cells.

[0396] In the embodiments of the present application, by synchronously regulating the thicknesses of lithium bis(fluorosulfonyl)imide and the heat insulation member, when the mass content of lithium bis(fluorosulfonyl)imide is relatively high, the thickness of the heat insulation member is increased to reduce the risk of thermal runaway. For example, in Example 2-1, the mass content of lithium bis(fluorosulfonyl)imide is relatively low, and a relatively thin heat insulation member is used. When thermal runaway occurs, the heat released by the battery cell is relatively small, and the relatively thin heat insulation member can effectively isolate the heat diffusion. As the mass content of lithium bis(fluorosulfonyl)imide increases, the amount of acid produced in the electrolyte decreases, and the cycling performance is significantly improved; however, when thermal runaway occurs, the heat released instantaneously increases, and the thickness of the heat insulation member is synchronously increased. By increasing the thickness of the heat insulation member, such as in Examples 2-2 to 2-6, the risk of heat spreading to adjacent battery cells is reduced, and the reliability of the battery device in use is improved.

[0397] A variety of fluorosulfonylimide salts are applicable to the present application. For example, lithium bis(fluorosulfonyl)imide in Example 1, lithium tris(fluorosulfonyl)imide in Example 2-6, etc. can all effectively improve the reliability and cycling performance of the battery device in use.

[0398] Examples 3-1 and 3-2 The battery device was prepared by a method similar to that of Example 1. Different from Example 1, the compaction density of the positive electrode film layer and the negative electrode film layer was adjusted, and the thickness of the heat insulation member was adjusted.

[0399] Examples 3-3 and 3-4 The battery device was prepared by a method similar to that of Example 1. Different from Example 1, the coating weight and compaction density of the positive electrode film layer and the negative electrode film layer were adjusted, and the thickness of the heat insulation member was adjusted; Among them, in Example 3-3, the negative electrode film layer includes 6% of silicon carbide, and the mass content of graphite particles is synchronously reduced, so that the mass content of the negative electrode active material in the negative electrode film layer remains basically unchanged; In Example 3-4, the negative electrode film layer includes 10% of silicon carbide, and the mass content of graphite particles is synchronously reduced, so that the mass content of the negative electrode active material in the negative electrode film layer remains basically unchanged.

[0400] The test results are shown in Table 3.

[0401] Table 3

[0402] In Table 3, in Examples 3-1 and 3-2, by adjusting the compaction density of the positive and negative electrode film layers, the volumetric energy density of the battery cell is reduced or increased. When the volumetric energy density of the battery cell is relatively small, a relatively thin heat insulation member can be used, which can take into account improving the reliability and cycling performance of the battery cell in use.

[0403] Example 3-3 and Example 3-4 can effectively improve the energy density of a battery cell by increasing the adjustment of silicon elements in the negative electrode film layer and coordinating with the compaction density and coating weight of the positive and negative electrode film layers. Synchronously increasing the thickness of the heat insulation member can take into account the improvement of the use reliability and cycle performance of the battery cell.

[0404] Example 4-1 and Example 4-2 A battery device was prepared using a method similar to that of Example 1. Different from Example 1, the height of the heat insulation member was adjusted.

[0405] Example 4-3 and Example 4-4 A battery device was prepared using a method similar to that of Example 1. Different from Example 1, the width of the heat insulation member was adjusted.

[0406] The test results are shown in Table 4.

[0407] Table 4

[0408] The more area of the battery cell covered by the heat insulation member, the better the ability to relieve heat diffusion, the lower the risk of thermal runaway of adjacent battery cells, and the use reliability of the battery cell can be effectively improved; the difference in the cycle performance of the battery cell is small. For example, compared with Example 4-2, the height of the heat insulation member in Example 4-1 is higher, the area of the battery cell covered is larger, and the use reliability of the battery cell is higher.

[0409] Compared with Example 4-3, the width of the heat insulation member in Example 4-4 is larger, the area of the battery cell covered is larger, and the use reliability of the battery cell is higher.

[0410] Although the illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments cannot be construed as a limitation of the present application, and changes, substitutions, and modifications can be made to the embodiments without departing from the spirit, principle, and scope of the present application.

Claims

1. A battery device, characterized in that: comprising a heat insulating member and at least two battery cells arranged along a first direction, The battery cell comprises an electrode assembly and an electrolyte, wherein the electrode assembly comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode film layer comprises a lithium-containing phosphate; wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode film layer comprises graphite particles; in, The electrolyte includes a fluorine-containing sulfonyl imide salt, and the mass content of the fluorine-containing sulfonyl imide salt in the electrolyte is 2% to 12%; The battery cell includes two first surfaces opposite to each other along the first direction, the heat insulator covers at least one of the two first surfaces, and a dimension of the heat insulator along the first direction is 0.3 mm to 5 mm.

2. The battery device according to claim 1, characterized in that: A dimension of the heat insulating member along the first direction is 0.5 mm to 2.5 mm.

3. The battery device according to claim 1 or 2, characterized in that: The mass content of the fluorinated sulfonyl imide salt in the electrolyte is 2% to 6%; The dimension of the heat insulating member along the first direction is greater than or equal to 0.5 mm and less than or equal to 1.0 mm.

4. The battery device according to claim 1 or 2, characterized in that: The mass content of the fluorinated sulfonyl imide salt in the electrolyte is greater than 6% and less than or equal to 8%; The dimension of the heat insulating member along the first direction is greater than 1.0 mm and less than or equal to 1.5 mm.

5. The battery device according to claim 1 or 2, characterized in that: The mass content of the fluorinated sulfonyl imide salt in the electrolyte is greater than 8% and less than or equal to 12%; The dimension of the heat insulating member along the first direction is greater than 1.5 mm and less than or equal to 2.5 mm.

6. The battery device according to claim 1, characterized in that: The volume energy density of the battery cell is 400Wh / L to 530Wh / L.

7. The battery device according to claim 1, characterized in that: The volume energy density of the battery cell is 400Wh / L to 440Wh / L; The dimension of the heat insulating member along the first direction is greater than or equal to 0.5 mm and less than or equal to 1.0 mm.

8. The battery device according to claim 1, characterized in that: The volume energy density of the battery cell is greater than 440Wh / L and less than or equal to 490Wh / L; The dimension of the heat insulating member along the first direction is greater than 1.0 mm and less than or equal to 1.5 mm.

9. The battery device according to claim 1, characterized in that: The volume energy density of the battery cell is greater than 490Wh / L and less than or equal to 530Wh / L; The dimension of the heat insulating member along the first direction is greater than 1.5 mm and less than or equal to 2.5 mm.

10. The battery device according to claim 1, characterized in that: The battery device satisfies: 0.9≤S2 / S1≤1, S1 represents the area of ​​the first surface, and its unit is mm 2 ; S2 represents the area of ​​the projection surface of the thermal insulation member perpendicular to the first direction, and its unit is mm 2 .

11. The battery device according to claim 1, characterized in that: The battery cell comprises an electrode terminal, wherein the electrode terminal is connected to at least one side of the electrode assembly along a second direction, wherein the second direction is perpendicular to the first direction; Wherein, the battery device satisfies: 0.8≤L2 / L1≤1, L1 represents the dimension of the first surface along the second direction, and its unit is mm; L2 represents the dimension of the thermal insulation component along the second direction, and its unit is mm.

12. The battery device according to claim 11, characterized in that: The battery device also satisfies: 2mm≤L1-L2≤10mm.

13. The battery device according to claim 1, characterized in that: The battery cell includes an electrode terminal connected to at least one side of the electrode assembly along the second direction; Wherein, the battery device satisfies: 0.9≤H2 / H1≤1, H1 represents the dimension of the first surface along the third direction, in mm, and the third direction and the second direction are perpendicular to the first direction in pairs; H2 represents the dimension of the thermal insulation member along the third direction, and its unit is mm.

14. The battery device according to claim 13, characterized in that: The battery device also satisfies: 1mm≤H1-H2≤10mm.

15. The battery device according to claim 1, characterized in that: The battery cell further includes two second surfaces opposite to each other along a third direction, the two second surfaces being connected by the first surface, the third direction being perpendicular to the first direction, wherein an area of ​​the first surface is greater than an area of ​​the second surface.

16. The battery device according to claim 1, characterized in that: The heat insulating member covers the two first surfaces of the battery cell.

17. The battery device according to claim 1, characterized in that: The thermal insulation is bonded to the first surface.

18. The battery device according to claim 1, characterized in that The heat insulating member includes a heat insulating body and a supporting member. The supporting member is disposed around the heat insulating body. Both the heat insulating body and the supporting member cover the surface of the battery cell along the first direction.

19. The battery device according to claim 18, characterized in that: The supporting member is an annular member, The supporting member satisfies: 10mm≤W1-W2≤60mm, W1 represents the size of the outer contour of the annular member along the second direction; the battery cell includes an electrode terminal, the electrode terminal is connected to at least one side of the electrode assembly along the second direction, and the second direction is perpendicular to the first direction; W2 represents the size of the inner contour of the annular member along the second direction; and / or The supporting member satisfies: 10mm≤W3-W4≤60mm, W3 represents the size of the outer contour of the annular member along the third direction; the battery cell includes an electrode terminal, the electrode terminal is connected to at least one side of the electrode assembly along the second direction, and the third direction, the second direction and the first direction are perpendicular to each other; W4 represents the dimension of the inner contour of the annular member along the third direction.

20. The battery device according to claim 18 or 19, characterized in that: The heat-insulating body comprises a heat-insulating material, and the heat-insulating material comprises one or more of aerogel, foam, polyurethane, and silicone rubber; and / or The support member includes one or more of polysaccharide, polyethylene terephthalate, polyurethane, polyacrylonitrile, polypropylene, polyamide, and aromatic polyamide.

21. The battery device according to claim 1, characterized in that: The fluorine-containing sulfonyl imide salt includes one or more of bisfluorosulfonyl imide salt, bistrifluoromethanesulfonyl imide salt, and perfluorobutylsulfonyl imide salt.

22. The battery device according to claim 1, characterized in that The mass content of the fluorine-containing sulfonyl imide salt in the electrolyte is 4% to 8%.

23. The battery device according to claim 1, characterized in that The electrolyte also includes hexafluorophosphate, and the mass content of the hexafluorophosphate in the electrolyte is 3% to 13%.

24. The battery device according to claim 1, characterized in that The electrolyte further includes a carboxylate solvent, and the carboxylate solvent includes one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate.

25. The battery device according to claim 24, characterized in that The mass content of the carboxylic acid ester solvent in the electrolyte is 8% to 60%.

26. The battery device according to claim 1, characterized in that The electrolyte further includes a carbonate solvent, and the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

27. The battery device according to claim 26, characterized in that The mass content of the carbonate solvent in the electrolyte is 18% to 70%.

28. The battery device according to claim 1, characterized in that The electrolyte further comprises an additive; The additive includes a carbonate additive, and the carbonate additive includes one or more of vinylene carbonate and a vinyl carbonate derivative, and the vinyl carbonate derivative includes a compound shown in formula A, Formula A, In formula A, Q1, Q2, Q3 and Q4 each independently include any one of a hydrogen atom, a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group, and Q1, Q2, Q3, Q4 are not hydrogen atoms at the same time; and / or The additive includes a sulfur-containing additive, and the sulfur-containing additive includes one or more of vinyl sulfate, vinyl disulfate, 1,3-propane sultone, butylene sulfite, vinyl sulfite, and methylene disulfonate; and / or The additive includes a lithium salt additive, and the lithium salt additive includes one or more of lithium difluorophosphate, lithium difluorooxalatoborate, lithium tetrafluoroborate and lithium bis(oxalatoborate).

29. The battery device according to claim 28, characterized in that The mass content of the carbonate additive in the electrolyte is 2.5% to 10.0%; and / or The mass content of the sulfur-containing additive in the electrolyte is 0% to 2%; and / or The mass content of the lithium salt additive in the electrolyte is 0% to 1%.

30. The battery device according to claim 1, characterized in that The single-sided coating weight of the positive electrode film layer is 220 mg / 1540.25 mm 2 Up to 450mg / 1540.25mm 2 ; and / or The single-sided coating weight of the negative electrode film layer is 100 mg / 1540.25 mm 2 Up to 200mg / 1540.25mm 2 .

31. The battery device according to claim 1, characterized in that The compaction density of the positive electrode film layer of the battery cell is 2.6 g / cm 3 Up to 2.8g / cm 3 ; and / or The compaction density of the negative electrode film layer of the battery cell is 1.2 g / cm 3 Up to 1.4g / cm 3 .

32. The battery device according to claim 1, characterized in that The lithium-containing phosphate comprises: Phosphate particles, and A positive electrode coating layer is located on at least a portion of the surface of the phosphate particles, and the positive electrode coating layer contains carbon elements.

33. The battery device according to claim 32, characterized in that Based on the mass of the lithium-containing phosphate, the mass content of the carbon element is 0.8% to 2.3%.

34. The battery device according to claim 32 or 33, characterized in that: The positive electrode coating layer also includes one or more elements of Fe, Ti, Zr, Hf, Ge, and Sn.

35. The battery device according to claim 32, characterized in that The phosphate particles include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate.

36. The battery device according to claim 1, characterized in that The lithium-containing phosphate includes a general formula of Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Materials, Among them, 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, A includes one or more of Na, K and Mg; Me includes one or more of Mn, Fe, Co and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge and Ce; X includes one or more of Cl, C, N; Y includes one or more of O and F.

37. The battery device according to claim 1, characterized in that The thickness of the positive electrode current collector is 10 μm to 15 μm.

38. The battery device according to claim 1, characterized in that The positive electrode plate further comprises a positive electrode conductive layer, wherein the positive electrode conductive layer is located between the positive electrode current collector and the positive electrode film layer. The positive electrode conductive layer includes a positive electrode conductive agent, and the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; and / or The positive electrode conductive layer includes a positive electrode binder, and the positive electrode binder includes 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 acrylic resin.

39. The battery device according to claim 38, characterized in that The thickness of the positive electrode conductive layer is 0.5 μm to 2 μm.

40. The battery device according to claim 1, characterized in that The graphite particles include graphite main particles and a negative electrode coating layer coated on the surface of the graphite main particles, the graphite main particles include secondary particles, and the negative electrode coating layer includes carbon elements.

41. The battery device according to claim 40, characterized in that The graphite bulk particles include one or more of artificial graphite and natural graphite.

42. The battery device according to claim 40 or 41, characterized in that: The mass content of carbon element in the negative electrode coating layer is 2% to 5% based on the mass of the graphite particles.

43. The battery device according to claim 1, characterized in that The powder resistivity of the graphite particles is 0.005 Ω•cm to 0.04 Ω•cm; and / or The volume average particle size Dv50 of the graphite particles is 9.5 μm to 16.5 μm.

44. The battery device according to claim 1, characterized in that The negative electrode film layer further comprises a silicon-based material, and the mass content of silicon element of the silicon-based material in the negative electrode film layer is 1% to 5%.

45. The battery device according to claim 44, characterized in that The silicon-based material includes one or more of elemental silicon, silicon-carbon material, silicon-oxygen material, and silicon-nitrogen material.

46. ​​The battery device according to claim 1, characterized in that The thickness of the negative electrode current collector is 4 μm to 6 μm.

47. The battery device according to claim 1, characterized in that The negative electrode plate further includes a negative electrode conductive layer, and the negative electrode conductive layer is located between the negative electrode current collector and the negative electrode film layer. The negative electrode conductive layer includes a negative electrode conductive agent, and the negative electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; and / or The negative electrode conductive layer includes a negative electrode binder, and the negative electrode binder includes 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 acrylic resin.

48. The battery device according to claim 47, characterized in that The thickness of the negative electrode conductive layer is 0.5 μm to 2 μm.

49. The battery device according to claim 1, characterized in that The electrode assembly further includes a separator, which is located between the positive electrode sheet and the negative electrode sheet. The thickness of the isolation film is 4 μm to 12 μm; and / or The porosity of the isolation film is 20% to 70%.

50. The battery device according to claim 49, characterized in that The isolation film includes a base film and a functional layer disposed on the base film, and the functional layer includes: a first functional layer, located on one side of the base film, the first functional layer comprising first inorganic particles, The second functional layer is located on the other side of the base film, and the second functional layer includes composite particles. The composite particles include second inorganic particles and a plurality of non-fluoropolymer particles. The second inorganic particles are attached to the surface of the non-fluoropolymer particles and / or dispersed inside the non-fluoropolymer particles.

51. The battery device according to claim 50, characterized in that The non-fluorinated polymer particles include acrylic copolymers.

52. The battery device according to claim 50 or 51, characterized in that: 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; and / or The average particle size of the first inorganic particles is 5 nm to 100 nm.

53. The battery device according to claim 50, characterized in that The second 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, and / or The average particle size of the second inorganic particles is 5 nm to 100 nm.

54. The battery device according to claim 1, characterized in that The electrode assembly further comprises a positive electrode tab and a negative electrode tab, wherein the positive electrode tab is connected to at least one side of the positive electrode collector along the length direction of the positive electrode sheet, and the negative electrode tab is connected to at least one side of the negative electrode collector along the length direction; Along the length direction, the size of the negative electrode film layer is larger than the size of the positive electrode film layer, and the difference between the size of the negative electrode film layer and the size of the positive electrode film layer is OH1; Along the width direction of the positive electrode sheet, the size of the negative electrode film layer is larger than the size of the positive electrode film layer, and the difference between the size of the negative electrode film layer and the size of the positive electrode film layer is OH2. Among them, OH1 is greater than OH2.

55. The battery device according to claim 54, characterized in that OH1 is 0.5 mm to 3.0 mm; and / or OH2 is 0.5 mm to 3.0 mm.

56. The battery device according to claim 1, characterized in that The battery cell includes a case that accommodates the electrode assembly and the electrolyte, and a thickness of the case is 0.1 mm to 0.5 mm.

57. An electrical device, characterized in that: A battery device comprising the battery device of any one of claims 1 to 56.

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