A battery device and an electrical device

Abstract

Battery device comprising a thermal insulation element and at least two battery cells arranged along a first direction, wherein the battery cell comprises an electrode assembly and electrolyte solution, the electrode assembly comprising positive electrode plates and negative electrode plates, the positive electrode plate comprising positive current collectors and positive film layers arranged on at least one side of the positive current collectors, the positive film layer comprising lithium phosphate, wherein the negative electrode plate comprises negative current collectors and negative film layers arranged on at least one side of the negative current collector, the negative film layer comprising graphite particles. characterized in that the electrolyte solution comprises fluorosulfonylimide salt, wherein the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 12%; wherein the battery cell comprises two first surfaces which are opposite each other along the first direction, wherein the thermal insulation element covers at least one of the two first surfaces and the dimension of the thermal insulation element along the first direction is 0.3 mm to 5 mm.

Description

TECHNICAL AREA

[0001] This application relates to a battery device and an electrical device. BACKGROUND TECHNOLOGY

[0002] The battery devices are characterized by high capacity and long lifespan and are therefore frequently used in electronic devices such as mobile phones, laptops, electric bicycles, electric vehicles, electric aircraft, electric boats and power tools.

[0003] As the application areas of lithium-ion batteries develop, higher demands are placed on the performance of battery devices, for example on the cycle performance and the reliability of the battery devices. CONTENTS OF THE INVENTION

[0004] The present application describes a battery device and an electrical device with which the cycle performance and reliability of the battery device can be improved.

[0005] Firstly, the present application provides a battery device comprising a thermal insulation element and at least two battery cells arranged along a first direction, wherein the battery cell comprises an electrode assembly and electrolyte solution, the electrode assembly comprising positive electrode plates and negative electrode plates, the positive electrode plate comprising positive current collectors and positive film layers arranged on at least one side of the positive current collectors, the positive film layer comprising lithium phosphate, wherein the negative electrode plate comprising negative current collectors and negative film layers arranged on at least one side of the negative current collector, the negative film layer comprising graphite particles; where, the electrolyte solution comprises fluorosulfonylimide salt, wherein the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 12%; wherein the battery cell comprises two first surfaces which are opposite each other along the first direction, wherein the thermal insulation element covers at least one of the two first surfaces and the dimension of the thermal insulation element along the first direction is 0.3 mm to 5 mm.

[0006] Thus, the embodiment of the present application comprises, on the one hand, the selection of a material system wherein the positive active material comprises lithium phosphate and the negative active material comprises graphite particles, wherein the above-mentioned material system exhibits excellent cycle stability; when using the above-mentioned material system, the risk of thermal instability of the battery cell is low;

[0007] On the other hand, the electrolyte solution contains fluorosulfonylimide salt, and the introduction of fluorosulfonylimide salt at a mass fraction greater than or equal to 2% can reduce the amount of hexafluorophosphate required. This can reduce the hydrofluoric acid content generated by the decomposition of hexafluorophosphate and mitigate the damage to the SEI film (solid-state electrolyte membrane) on the cathode side by hydrofluoric acid, thereby improving the protective effect of the SEI film on the negative active material and increasing the cycle performance of the battery cell. Furthermore, by applying a thermal insulation element with predefined dimensions to the first surface of the thermal insulation element, rapid heat transfer to other battery cells can be effectively prevented, the risk of heat dissipation can be reduced, and the reliability of the battery device can be improved.

[0008] In some embodiments, the dimension of the thermal insulation element along the first direction is 0.5 mm to 2.5 mm. If the dimension of the thermal insulation element lies within the aforementioned range, heat transfer can be effectively reduced, and since the battery device occupies less space, the energy density of the battery device can be increased.

[0009] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 6%; the dimension of the thermal insulation element along the first direction is greater than or equal to 0.5 mm and less than or equal to 1.0 mm. The combination of the fluorosulfonylimide salt and a thermal insulation element with suitable dimensions can effectively improve the heat dissipation capacity of the thermal insulation element while simultaneously improving the energy density and reliability of the battery device.

[0010] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is greater than 6% and less than or equal to 8%; the dimension of the thermal insulation element along the first direction is greater than 1.0 mm and less than or equal to 1.5 mm. The combination of the fluorosulfonylimide salt and a thermal insulation element with suitable dimensions can effectively improve the heat dissipation capacity of the thermal insulation element while simultaneously improving the energy density and reliability of the battery device.

[0011] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is greater than 8% and less than or equal to 12%; the dimension of the thermal insulation element along the first direction is greater than 1.5 mm and less than or equal to 2.5 mm. The combination of the fluorosulfonylimide salt and a thermal insulation element with suitable dimensions can effectively improve the heat dissipation capacity of the thermal insulation element while simultaneously improving the energy density and reliability of the battery device.

[0012] In some embodiments, the volume energy density of the battery cell is 400 Wh / L to 530 Wh / L, resulting in a relatively high energy density of the battery cell.

[0013] In some embodiments, the volume energy density of the battery cell is 400 Wh / L to 440 Wh / L; the dimension of the thermal insulation element in the first direction is greater than or equal to 0.5 mm and less than or equal to 1.0 mm. The combination of the battery cell's energy density and a thermal insulation element with suitable dimensions can effectively improve the thermal insulation element's heat dissipation capability and enhance the reliability of the battery device.

[0014] In some embodiments, the volume 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 thermal insulation element along the first direction is greater than 1.0 mm and less than or equal to 1.5 mm. The combination of the battery cell's energy density and a thermal insulation element with suitable dimensions can effectively improve the thermal insulation element's heat dissipation capability and enhance the reliability of the battery device.

[0015] In some embodiments, the volume 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 thermal insulation element along the first direction is greater than 1.5 mm and less than or equal to 2.5 mm. The combination of the battery cell's energy density and a thermal insulation element with suitable dimensions can effectively improve the thermal insulation element's heat dissipation capability and enhance the reliability of the battery device.

[0016] In some embodiments, the battery device satisfies the following condition: 0.9 ≤ S2 / S1 ≤ 1, where S1 is the area of ​​the first surface in mm² 2 denoted; where S2 is the area of ​​the projection surface of the thermal insulation element perpendicular to the first direction in mm² 2This is referred to as... If the battery device meets the above-mentioned condition, the thermal insulation element covers a relatively large part of the first surface and can thus reduce heat transfer more effectively.

[0017] In some embodiments, the battery cell comprises an electrode terminal, wherein the electrode terminal is connected to at least one side of the electrode assembly along the second direction, the second direction being perpendicular to the first direction; wherein the battery cell comprises two first surfaces opposite each other along the first direction, the thermal insulation element covering the first surface; wherein the battery device satisfies the following condition: 0.8 ≤ L 2 / L, ≤ 1, where L1 denotes the dimension of the first surface along the second direction in mm; where L2 denotes the dimension of the thermal insulation element along the second direction in mm. If the battery device meets the above condition, the thermal insulation element covers a relatively large part of the first surface and can thus reduce heat transfer more effectively.

[0018] In some embodiments, the battery device also fulfills the following condition: 2 mm ≤ L1-L2 ≤ 10 mm. If the battery device fulfills the above condition, the thermal insulation element covers a relatively large part of the first surface and can thus reduce heat transfer more effectively.

[0019] In some embodiments, the battery cell comprises an electrode terminal, wherein the electrode terminal is connected to at least one side of the electrode assembly along the second direction; wherein the battery cell comprises two first surfaces that are opposite each other along the first direction, the thermal insulation element covering the first surface; wherein the battery device satisfies the following condition: 0.9 ≤ H2 / H1 ≤ 1, where H1 denotes the dimension of the first surface along the third direction in mm, where the third direction and the second direction are each perpendicular to the first direction; where H2 denotes the dimension of the thermal insulation element along the third direction in mm.

[0020] In some embodiments, the battery device also fulfills the following condition: 1 mm < H1-H2 ≤ 10 mm. If the battery device fulfills the above condition, the thermal insulation element covers a relatively large part of the first surface and can thus reduce heat transfer more effectively.

[0021] In some embodiments, the thermal insulation element comprises a thermal insulation body and a support element, wherein the support element is arranged annularly around the thermal insulation body and both the thermal insulation body and the support element cover the surface of the battery cell along the first direction. The support element can support and fix the thermal insulation body so that the thermal insulation body can effectively exert its thermal insulation effect.

[0022] In some embodiments, the battery cell also comprises two second surfaces that are opposite each other along a third direction and that the two second surfaces are connected to each other via the first surface, wherein the third direction is perpendicular to the first direction and the area of ​​the first surface is larger than the area of ​​the second surface.

[0023] Since the area of ​​the first surface is larger, the thermal insulation element covering the first surface can reduce heat propagation more effectively.

[0024] In some embodiments, the thermal insulation element covers the first two surfaces of the battery cell. This arrangement allows the thermal insulation element to reduce heat propagation more effectively.

[0025] In some embodiments, the thermal insulation element is bonded to the first surface, with the adhesive force between the thermal insulation element and the first surface being strong, so that the thermal insulation element can effectively exert its thermal insulation effect.

[0026] In some embodiments, the support element is an annular element, wherein the support element satisfies the following condition: 10 mm ≤ W1-W2 ≤ 60 mm, where W1 denotes the dimension of the outer outline of the annular element along the second direction; wherein the battery cell comprises an electrode terminal, the electrode terminal being connected to at least one side of the electrode assembly along the second direction, the second direction being perpendicular to the first direction; where W2 denotes the dimension of the inner outline of the annular element along the second direction; and / or wherein the support element satisfies the following condition: 10 mm ≤ W3-W4 ≤ 60 mm, where W3 denotes the dimension of the outer outline of the annular element along the third direction;wherein the battery cell comprises an electrode terminal, the electrode terminal being connected to at least one side of the electrode assembly along the second direction, wherein the third direction, the second direction and the first direction are each perpendicular to each other; wherein W4 denotes the dimension of the inner outline of the annular element along the third direction. If the support element satisfies the above condition, it can effectively support and fix the thermal insulation body.

[0027] In some embodiments, the thermal insulation body comprises a thermal insulation material, wherein the thermal insulation material includes one or more of aerogel, foam, polyurethane, or silicone rubber. The aforementioned materials exhibit excellent thermal insulation properties and can effectively reduce heat propagation.

[0028] In some embodiments, the support element comprises one or more of polysaccharide, polyethylene terephthalate, polyurethane, polyacrylonitrile, polypropylene, polyamide, and aromatic polyamide. The aforementioned materials exhibit excellent support properties and can effectively support the thermal insulation material.

[0029] In some embodiments, the fluorosulfonylimide salt comprises one or more of the difluorosulfonylimide salt, difluoromethanesulfonylimide salt, and perfluorobutylsulfonylimide salt. The aforementioned materials can improve both the cycle performance and the reliability of the battery device.

[0030] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 4% to 8%. If the mass fraction of the fluorosulfonylimide salt is within the aforementioned range, both the cycle performance and the reliability of the battery device can be improved.

[0031] In some embodiments, the electrolyte solution also comprises hexafluorophosphate, wherein the mass fraction of the hexafluorophosphate in the electrolyte solution is 3% to 13%. The combined use of fluorosulfonylimide salt and hexafluorophosphate contributes to improved cycle performance and reliability of the battery device.

[0032] In some embodiments, the electrolyte solution also comprises a carboxylic acid ester solvent, wherein the carboxylic acid ester solvent comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl butyrate. The aforementioned carboxylic acid ester solvent contributes to improving the cycle performance and fast-charging capability of the battery cell.

[0033] In some embodiments, the mass fraction of the carboxylic acid ester solvent in the electrolyte solution is 8% to 60%. The aforementioned mass fraction of the carboxylic acid ester solvent contributes to improving the cycle performance and fast-charging capability of the battery cell.

[0034] In some embodiments, the electrolyte solution also includes a carbonate solvent, wherein the carbonate solvent comprises one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methylethyl carbonate. The above-mentioned electrolyte system contributes to a further improvement in the cycle performance of the battery cell.

[0035] In some embodiments, the mass fraction of the carbonate solvent in the electrolyte solution ranges from 18% to 70%. The electrolyte system described above contributes to a further improvement in the cycle performance of the battery cell.

[0036] In some embodiments, the electrolyte solution also includes an additive; wherein the additive comprises a carbonate ester additive, wherein the carbonate ester additive comprises one or more derivatives of vinylidene carbonate and vinyl carbonate, wherein the vinyl carbonate derivatives comprise the compounds shown in Formula A, wherein in Formula A Q1, Q2, Q3 and Q4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a Cl to C5 haloalkyl group, and Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms; the carbonate ester additive may participate in the formation of the SEI film solid electrolyte interface film on the cathode side, which contributes to improving the cycle performance of the battery cell.

[0037] In some embodiments, the electrolyte solution also includes a sulfur-containing additive, wherein the sulfur-containing additive comprises one or more of ethylene sulfate, vinyl bisulfate, 1,3-propanesulfonic acid lactone, butyl sulfite, vinyl sulfite, methylene disulfonate; the sulfur-containing additive can optimize the composition of the SEI film and improve the cycle performance of the battery cell.

[0038] In some embodiments, the electrolyte solution also includes a lithium salt additive, wherein the lithium salt additive comprises one or more of lithium difluorophosphate, lithium borate difluorooxalate, lithium tetrafluoroborate, and lithium borate bis(oxalate). The lithium salt additive can optimize the composition of the SEI film and improve the cycle performance of the battery cell at high energy density.

[0039] In some embodiments, the mass fraction of the carbonate ester additive in the electrolyte solution is 2.5% to 10.0%; carbonate ester additive with the above-mentioned mass fraction can participate in the formation of the SEI film solid electrolyte interface film on the cathode side, which contributes to improving the cycle performance of the battery cell.

[0040] In some embodiments, the mass fraction of the sulfur-containing additive in the electrolyte solution is 0% to 2%; the sulfur-containing additive with the above-mentioned mass fraction can optimize the composition of the SEI film and improve the cycle performance of the battery cell.

[0041] In some embodiments, the mass fraction of the lithium salt additive in the electrolyte solution is 0% to 1%. The aforementioned lithium salt additive can optimize the composition of the SEI film and improve the cycle performance of the battery cell at high energy density.

[0042] In some embodiments, the one-sided coating weight of the positive film layer is 220 mg / 1540.25 mm². 2 up to 450 mg / 1540.25 mm 2 If the one-sided coating weight of the positive film layer is within the range mentioned above, the heat generation per unit area of ​​the positive electrode plate will not be too high, thereby improving the cycle performance of the battery cell at high energy density.

[0043] In some embodiments, the one-sided coating weight of the negative film layer is 100 mg / 1540.25 mm². 2 up to 200 mg / 1540.25 mm 2 If the one-sided coating weight of the negative film layer is within the range mentioned above, this contributes to improving the energy density and cycle performance of the battery cell.

[0044] In some embodiments, the compaction density of the positive film layer at a charge of 100% SOC is 2.6 g / cm³. 3 up to 2.8 g / cm³ 3 If the density of the positive film layer is within the range mentioned above, the energy density and cycle performance of the battery cell can be improved.

[0045] In some embodiments, the compaction density of the negative film layer at a charge of 100% is 1.2 g / cm³. 3 up to 1.4 g / cm³ 3 A density of the negative film layer within the above-mentioned range contributes to improving the energy density and cycle performance of the battery cell.

[0046] In some embodiments, the lithium phosphate comprises phosphate particles and a positive coating layer, wherein the positive coating layer is located on at least a portion of the phosphate particle surface and comprises a carbon element. Coating the phosphate particles with the positive coating layer improves the conductivity of the lithium phosphate, which promotes the migration rate of lithium ions, increases the fast-charging capability of the battery, reduces heat generation in the battery cell, and improves the cycle performance of the battery cell.

[0047] In some embodiments, the mass fraction of the carbon element is 0.8% to 2.3%, based on the mass of the lithium phosphate. If the mass fraction of the carbon element is within the aforementioned range, the conductivity of the lithium phosphate can be significantly improved, which has a positive effect on the ionic and electronic conductivity of the lithium phosphate and increases the fast-charging capability of the battery cell at high energy density.

[0048] In some embodiments, the positive cover layer also comprises one or more of the elements Fe, Ti, Zr, Hf, Ge, and Sn. The aforementioned positive cover layer can improve the ionic conductivity of the positive active material, increase the fast-charging capability of the battery cell, and furthermore improve the gram capacity and energy density of the corresponding battery cells.

[0049] In some embodiments, the phosphate particles comprise one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The aforementioned materials exhibit excellent cycle stability and can improve the cycle performance of the battery cell.

[0050] In some embodiments, the lithium phosphate comprises a material with the general formula Li x1 Ay1Me a1 M b1 P 1-c1 X c1 Y z1, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises one or more of the elements Na, K and Mg, Me comprises one or more of the elements Mn, Fe, Co and Ni, M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge and Ce are included; X includes one or more of the elements Cl, C, N; Y includes one or more of the elements O and F. The above-mentioned materials exhibit excellent cycle stability and can improve the cycle performance of the battery cell.

[0051] In some embodiments, the thickness of the positive current collector is 10 µm to 15 µm. If the thickness of the positive current collector is within the aforementioned range, the positive current collector is thinner, which contributes to improving the volume energy density of the battery cell.

[0052] In some embodiments, the positive electrode plate also includes a positive conductive layer, wherein the positive conductive layer is located between the positive current collector and the positive film layer, and wherein the positive conductive layer comprises a positive conductive element, the positive conductive element comprising one or more of the following elements, such as superconducting carbon, conductive graphite, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofiber. The positive conductive layer can further improve the conductivity of the positive electrode plate, reduce the heat generation of the positive electrode plate, and thus reduce the heat generation of the battery cell.

[0053] In some embodiments, the thickness of the positive conductive layer is 0.5 µm to 2 µm. When the thickness of the positive conductive layer is within the aforementioned range, it can further improve the conductivity of the positive electrode plate, reduce the heat generation of the positive electrode plate, and thus reduce the heat generation of the battery cell, thereby improving the fast-charging capability and high-temperature cycle performance of the battery cell at high energy density.

[0054] In some embodiments, the graphite particles comprise graphite particles and a negative cover layer applied to the surface of the graphite particles, wherein the graphite particles comprise secondary particles and the negative cover layer comprises carbon elements. The negative cover layer exhibits excellent conductivity, which reduces the internal resistance of the negative electrode plate, reduces heat generation from the battery cell, and improves the cycle performance of the battery cell at high energy density.

[0055] In some embodiments, the graphite particles comprise one or more of artificial graphite and natural graphite.

[0056] In some embodiments, the mass fraction of the carbon element in the negative cover layer, based on the mass of the graphite particles, is 2% to 5%. If the mass fraction of the carbon element in the negative cover layer is within the aforementioned range, the internal resistance of the negative electrode plate can be further reduced, the heat generation of the battery cell reduced, and the cycle performance of the battery cell improved at high energy density.

[0057] In some embodiments, the specific powder resistance of the graphite particles is 0.005 Ω·cm to 0.04 Ω·cm. If the graphite particles meet the above-mentioned conditions, this contributes to improving the fast-charging capability of the battery cell.

[0058] In some embodiments, the volume-averaged particle size Dv50 of the graphite particles is 9.5 µm to 16.5 µm. If the graphite particles meet the above-mentioned conditions, this contributes to improving the energy density and cycle performance of the battery cell.

[0059] In some embodiments, the negative film layer also comprises a silicon-based material, wherein the mass fraction of the silicon element in the silicon-based material in the negative film layer is 1% to 5%. If the mass fraction of the silicon element is within the aforementioned range, the energy density and cycle performance of the battery cell can be improved.

[0060] In some embodiments, the silicon-based material comprises one or more silicon monomers, silicon-carbon material, silicon-oxygen material, or silicon-nitrogen material. Preferably, the silicon-based material comprises one or more of the following materials: silicon-carbon material, silicon-oxygen material, or silicon-nitrogen material. Preferably, the silicon-based material comprises silicon-carbon material. The aforementioned materials exhibit a high gram capacity, which contributes to improving the energy density of the battery cell.

[0061] In some embodiments, the thickness of the negative current collector is 4 µm to 6 µm. When the thickness of the negative current collector is within the aforementioned range, the negative current collector is thinner, which contributes to improving the volume energy density of the battery cell.

[0062] In some embodiments, the negative electrode plate also includes a negative conductive layer located between the negative current collector and the negative film layer. The negative conductive layer comprises a negative conductive agent, which may include one or more of the following elements: superconducting carbon, conductive graphite, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofiber. The negative conductive layer can further improve the conductivity of the negative electrode plate, reduce heat generation from the negative electrode plate, and thus reduce heat generation from the battery cell, thereby improving the fast-charging capability and high-temperature cycle performance of the battery cell.

[0063] In some embodiments, the thickness of the negative conductive layer is 0.5 µm to 2 µm. If the thickness of the negative conductive layer is within the aforementioned range, the conductivity of the negative electrode plate can be further improved, the heat generation of the negative electrode plate reduced, and thus the heat generation of the battery cell reduced, while simultaneously increasing the energy density of the battery cell.

[0064] In some embodiments, the electrode assembly also includes a separator film located between the positive and negative electrode plates, with a thickness of 4 µm to 12 µm. When the thickness of the separator film is within the aforementioned range, the migration path of the lithium ions within the separator film is shorter, which further reduces the internal resistance of the battery cell. This, in turn, reduces heat generation and improves the fast-charging capability and high-temperature cycle performance of the battery cell at high energy density.

[0065] In some designs, the porosity of the separating film ranges from 20% to 70%. If the porosity of the separating film is within the aforementioned range, the migration capability of the lithium ions in the separating film can be improved, which can further reduce the internal resistance of the battery cell. This, in turn, reduces heat generation and improves the fast-charging capability and high-temperature cycle performance of the battery cell at high energy density.

[0066] In some embodiments, the release film further comprises a base film and a functional layer arranged on the base film, wherein the functional layer comprises a first functional layer and a second functional layer, the first functional layer being located on one side of the base film and comprising first inorganic particles, and the second functional layer being located on the other side of the base film and comprising composite particles, the composite particles comprising second inorganic particles and several non-fluorinated polymer particles, wherein the second inorganic particles adhere to the surface of the non-fluorinated polymer particles and / or are dispersed within the non-fluorinated polymer particles. The first and second functional layers exhibit good heat resistance and can improve the heat resistance of the release film.

[0067] In some embodiments, the non-fluorinated polymer particles comprise acrylate copolymers. Acrylate copolymers exhibit excellent adhesion properties and high adhesion stability to the base film.

[0068] In some embodiments, the first inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide; the first inorganic particles contribute to improving the heat resistance and bulk modulus of the separating film.

[0069] In some embodiments, the first inorganic particles have an average particle size of 5 nm to 100 nm. If the average particle size of the first inorganic particles is within the aforementioned range, this improves the heat resistance and the bulk modulus of the separating film.

[0070] In some embodiments, the second inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These second inorganic particles can improve the heat resistance of the second functional layer and can be combined with non-fluorinated polymers to form composite particles, further enhancing the cycle stability and kinetic properties of the separator film and improving the cycle performance and fast-charging capability of the battery cell.

[0071] In some embodiments, the second inorganic particles have an average particle size of 5 nm to 100 nm. If the average particle size of the second inorganic particles is within the aforementioned range, this improves the heat resistance and bulk modulus of the composite particles.

[0072] In some embodiments, the positive electrode plate and the negative electrode plate are arranged one above the other along the thickness direction of the battery cell; the electrode assembly further comprises a positive electrode tab and a negative electrode tab, wherein the positive electrode tab is connected to the positive current collector along at least one side of the longitudinal direction of the positive electrode plate and the negative electrode tab is connected to the negative current collector along at least one side of the longitudinal direction; wherein the dimension of the negative film layer along the longitudinal direction is larger than the dimension of the positive film layer, wherein the difference between the dimension of the negative film layer and the dimension of the positive film layer is OH1;wherein the dimension of the negative film layer along the width direction of the battery cell is larger than the dimension of the positive film layer, wherein the difference between the dimension of the negative film layer and the dimension of the positive film layer is OH2; where OH1 is larger than OH2. If the battery cell meets the above conditions, the risk of lithium deposition can be reduced and the reliability of the battery cell can be improved.

[0073] In some embodiments, OH1 is 1 mm to 4 mm and / or OH2 is 1 mm to 3 mm. If the battery cell meets the above conditions, the risk of lithium deposition can be reduced and the reliability of the battery cell improved.

[0074] Secondly, this application provides an electrical device comprising a battery device according to any embodiment of the first aspect of the present application. FIGURES

[0075] In order to illustrate the technical solution in the embodiments of the application more clearly, a brief description of the figures that must be used in the embodiments of the application follows, whereby it is obvious that the figures in the following description are only some embodiments for the application and that other figures can be obtained on the basis of the figures without creative effort by general technical personnel. Fig. Figure 1 is a schematic representation of the structure of a vehicle in some embodiments of the present application; Fig. Figure 2 is an exploded view of a battery pack in some embodiments of the present application; Fig. Figure 3 is a schematic representation of the structure of the battery module in Fig. 2; Fig.Figure 4 is a schematic representation of the structure of a battery cell in some embodiments of the present application; Fig. Figure 5 is a schematic representation of the structure of an electrode assembly of a battery cell in some embodiments of the present application; Fig. 6 is a schematic top view of an electrode assembly of a battery cell in some embodiments of the present application; Fig. Figure 7 is a schematic representation of the structure of a battery cell in some other embodiments of the present application; Fig. Figure 8 is a schematic representation of the structure of a battery device in some embodiments of the present application; Fig. Figure 9 is a schematic representation of the structure in some other embodiments of the present application; Fig.Figure 10 is a schematic representation of the structure in some other embodiments of the present application; Fig. Figure 11 is a schematic representation of the structure in some other embodiments of the present application; Fig. Figure 12 is a schematic representation of the structure in some other embodiments of the present application; Fig. Figure 13 is a schematic representation of the structure in some other embodiments of the present application; Fig. Figure 14 is a schematic representation of the structure of the thermal insulation element of the battery device in some embodiments of the present application; Fig. Figure 15 is a schematic representation of the assembly of the battery cell, the thermal insulation element and the clamping device in the present application; Fig.Figure 16 is a schematic representation of the structure of some battery cells in the present application.

[0076] The figures may not be to scale. Reference symbol list:

[0077] X. Thickness direction; Y. Width direction; Z. Length direction; 1. Vehicle; 2. Battery pack; 3. Controller; 4. Motor; 5. Box; 5a. First box section; 5b. Second box section; 5c. Storage compartment; 6. Battery module; 7. Battery cell; 71. First test battery; 72. Trigger battery; 10. Electrode assembly; 11. Positive electrode plate; 111. Positive electrode tab; 112. Positive current collector; 113. Positive film layer; 12. Negative electrode plate; 121. Negative electrode tab; 122. Negative current collector; 123. Negative film layer; 13. Separating film; 20. Outer casing; 21. Casing; 211. First surface; 212. Second surface; 22. End cover 31. Positive terminal; 32. Negative clamp; 40. Thermal insulation element; 41. Thermal insulation body; 42. Support element; 50. Battery device; F1. First direction; F2. Second direction; F3. Third direction; 60. Clamping device. SPECIFIC EXECUTION FORMS

[0078] The embodiments of the battery device and the electrical device of the present application are disclosed in detail below with appropriate reference to the figures. However, there may be cases where unnecessary detailed descriptions are omitted. For example, detailed descriptions of things that are already well known and repetitive descriptions of practically the same structure are omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding by the person skilled in the art. Furthermore, the figures and the following description serve to ensure the complete understanding of the present application by the person skilled in the art and are not intended to limit the subject matter specified in the claims.

[0079] The "range" disclosed here is defined in terms of a lower bound and an upper bound, and a particular range is defined by selecting a lower bound and an upper bound that establish the limits of that range. Ranges defined in this way can include or exclude end values ​​and can be combined in any way; that is, any lower bound can be combined with any upper bound to form a range. For example, if a range of 60 to 120 and 80 to 110 is specified for a given parameter, then a range of 60 to 110 and 80 to 120 is also expected. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4, and 5, then all of the following ranges are predictable: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.In this application, unless otherwise specified, the range of values ​​“a to b” denotes a shorthand representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the range of values ​​“0 to 5” denotes all real numbers between 0 and 5 listed in this document, where 0 to 5 is merely a shorthand for these combinations of numbers. When a parameter is specified as an integer ≥ 2, this is equivalent to disclosing that parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0080] Unless otherwise stated, all embodiments and optional embodiments of this application may be combined to form new technical solutions.

[0081] Unless otherwise stated, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0082] Unless otherwise stated, all steps of this application may be carried out sequentially or randomly, with sequential execution being preferred. For example, the procedure includes steps (a) and (b), which means that the procedure may include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. Similarly, when it is mentioned that the procedure may also include step (c), this means that step (c) may be included in the procedure in any order; for example, the procedure may include steps (a), (b), and (c), it may also include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0083] In this application, the battery cell may be cylindrical, flat, rectangular, or any other shape, and the embodiment of this application is not limited in this respect. Battery cells are generally classified into three types according to their packaging: cylindrical battery cells, square battery cells, and softpack battery cells, and the embodiment of this application is not limited in this respect.

[0084] The battery device referred to in the present application relates to a single physical module comprising one or more battery cells to provide a higher voltage and capacity.

[0085] In related technologies, internal heat accumulation in battery cells can lead to thermal instability. If the battery device comprises multiple battery cells, an overheated cell can trigger thermal instability in other cells, compromising the reliability of the battery device.

[0086] In light of the aforementioned problems, a material system comprising lithium phosphate as the positive active material and graphite as the negative active material was selected for this application. This material system exhibits excellent cycle stability, and the risk of thermal instability in the battery cells is low. However, a side reaction occurs in this material system between the decomposition products of lithium hexafluorophosphate (hydrofluoric acid) and the SEI film solid electrolyte interface film on the graphite surface when the lithium salt in the electrolyte solution is lithium hexafluorophosphate. This leads to increased gas evolution during storage of the battery cells at high temperatures, which adversely affects the long-term cycle stability of the battery cells.Adding lithium fluorosulfonylimide to the electrolyte solution significantly reduces the hydrofluoric acid content and improves the cycle performance of the battery cells. However, because lithium fluorosulfonylimide has a decomposition temperature close to the thermal instability temperature of the battery cells, a rapid thermal decomposition rate, and strong heat dissipation, battery cells containing lithium fluorosulfonylimide rapidly release a large amount of heat and high-temperature gas from the electrolyte solution when the battery cells reach the thermal instability temperature. This, in turn, leads to a sharp increase in internal heat within a short time, preventing rapid heat dissipation. This exacerbates the thermal instability of the battery cells and significantly increases the safety risk.By using thermal insulation elements that cover the surface of the battery cells with a specific amount of lithium fluorosulfonylimide and whose size is adapted to the lithium fluorosulfonylimide content, rapid heat transfer to other battery cells can be effectively prevented, the propagation rate of heat in the event of thermal instability of the battery cells can be reduced, and the reliability of the battery device can be improved.

[0087] This allows the embodiment of the present application to improve both the cycle performance and the reliability of the battery device.

[0088] The battery cell described in the embodiments of the present application is suitable for battery devices and electrical devices that use battery devices.

[0089] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be fuel-powered, gas-powered, or new energy vehicles, with new energy vehicles being pure electric vehicles, hybrid vehicles, or range-extender vehicles. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric toy cars, electric toy boats, and electric toy airplanes, etc. Power tools include metal cutting tools, grinding tools, assembly tools, and railway tools, such as drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.The embodiments of the present application do not provide for any special restrictions on the aforementioned electrical devices.

[0090] To simplify the explanation, the electrical device will be described below using the example of a vehicle.

[0091] Fig. Figure 1 is a schematic representation of the structure of a vehicle in some embodiments of the present application;

[0092] As in Fig. As shown in Figure 1, a battery system is arranged inside the vehicle 1, which can be located on the floor, at the front, or at the rear of the vehicle 1. The battery system can be used to supply power to the vehicle 1; for example, the battery system can serve as the operating power source for the vehicle 1.

[0093] The vehicle 1 can also include a control unit 3 and a motor 4, wherein the control unit 3 serves to control the power supply to the motor 4 by the battery device, for example for starting, navigation and operation of the vehicle 1 while driving.

[0094] In some embodiments of the present application, the battery device can not only be used as an operating current source for the vehicle 1, but can also be used as a drive current source for the vehicle 1 in order to provide the drive power for the vehicle 1 instead of or partially instead of fuel or natural gas.

[0095] The battery apparatus in the embodiment of the present application can comprise one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can comprise a plurality of battery cells, wherein the plurality of battery cells are connected in series, parallel, or mixed configurations via a busbar.

[0096] In some embodiments, the battery cell assembly is typically formed by arranging a large number of battery cells.

[0097] For example, the battery cell assembly can be a battery module, where the battery module is formed from a multitude of battery cells arranged and secured in such a way as to form a single module. The battery module can be formed, for example, by bonding the multiple battery cells together.

[0098] In some embodiments, the battery device can be a battery pack 2, wherein the battery pack 2 comprises a box and one or more battery cell assemblies, the battery cell assemblies being housed in the box.

[0099] The battery cell assembly can, for example, be a battery module, and the battery cell assembly can be housed in the box by attaching the battery module to the box.

[0100] For example, the battery cell assembly can also be housed in the box by attaching a large number of battery cell assemblies directly to the box.

[0101] Fig. Figure 2 is an exploded view of a battery pack in some embodiments of the present application; as shown in Fig. As shown in Figure 2, the battery pack 2 comprises a box 5 and a battery cell (in Fig.2 not shown), which are housed in box 5.

[0102] The box 5 serves to hold the battery cell and the box 5 can have various structures. In some embodiments, the box 5 can comprise a first box part 5a and a second box part 5b, wherein the first box part 5a and the second box part 5b are closed to each other, and the first box part 5a and the second box part 5b together define the receiving space 5c for holding the battery cells.The second box part 5b can be a hollow structure with an opening at one end, wherein the first box part 5a has a plate-shaped structure and the first box part 5a is placed on the opening side of the second box part 5b to form a box 5 with a receiving space 5c; the first box part 5a and the second box part 5b can also each be a hollow structure with an opening side, wherein the opening side of the first box part 5a is covered by the opening side of the second box part 5b to form a box 5 with a receiving space 5c. Naturally, the first box part 5a and the second box part 5b can have different shapes, for example, a cylinder, a cuboid, etc.

[0103] To improve the tightness between the first box part 5a and the second box part 5b after their connection, a seal can also be installed between the first box part 5a and the second box part 5b, for example sealant, sealing ring, etc.

[0104] Assuming that the first box part 5a is placed on top of the second box part 5b, then the first box part 5a can also be referred to as the upper box lid and the second box part 5b as the lower box.

[0105] Fig. Figure 3 is a schematic representation of the structure of the battery module in Fig. 2.

[0106] In some embodiments, such as in Fig.As shown in Figure 3, there are several battery cells 7, which are initially connected in series, parallel, or a mixture to form a battery module 6. Several battery modules 6 are then connected in series, parallel, or a mixture to form a unit and housed in a box.

[0107] The multiple battery cells 7 in the battery module 6 can be electrically connected via busbars to connect them in parallel, in series, or in a mixed configuration. There can be one or more busbars, with each busbar serving to electrically connect at least two battery cells 7.

[0108] Fig. Figure 4 is a schematic representation of the structure of a battery cell 7 in some embodiments of the present application, Fig. Figure 5 is an exploded view of a battery cell 7 in some embodiments of the present application.

[0109] As in Fig.4 and Fig. As shown in Figure 5, in some embodiments the battery cell 7 comprises an electrode assembly 10 and an outer housing 20, wherein the electrode assembly 10 is housed in the outer housing 20.

[0110] The outer housing 20 can have various shapes, for example, a cylinder, a cuboid, etc. The shape of the outer housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, the outer housing 20 can also have a cylindrical structure. If the electrode assembly 10 has a rectangular structure, the outer housing 20 can also have a rectangular structure. Preferably, the electrode assembly 10 can have a rectangular structure.

[0111] The material of the outer housing 20 can be of various types, for example copper, iron, aluminum, stainless steel, aluminum alloy, etc. The embodiment of the present application does not impose any particular restrictions in this regard. Preferably, the inner wall of the outer housing 20 can also comprise an insulating layer, wherein the insulating layer separates the outer housing 20 from the electrode assembly 10. The material of the insulating layer can be selected from the materials commonly used in this field, without any particular restrictions in this respect.

[0112] The electrode assembly 10 housed in the outer casing 20 can consist of one or more assemblies.

[0113] In some embodiments, the outer housing 20 comprises a housing 21 and an end cover 22, wherein the housing 21 has an opening, the end cover 22 closes the opening, and the electrode assembly is housed in the housing 21.

[0114] In some embodiments, the housing material 21 comprises steel, which has high mechanical strength, is not easily deformed, and can improve the reliability and cycle performance of the battery cell. Preferably, steel can constitute the largest proportion of the housing material 21. Of course, the housing material 21 can also include aluminum, etc.

[0115] Preferably the housing 21 can have a rectangular structure, for example the housing 21 comprises two opposing first surfaces 211 and two opposing second surfaces 212, wherein the two second surfaces 212 are connected by the two first surfaces 211 and the area of ​​the first surfaces 211 is larger than the area of ​​the second surfaces 212.

[0116] Preferably, the thickness of the casing 21 can be between 0.1 mm and 0.5 mm, more preferably between 0.2 mm and 0.35 mm. For example, the thickness of the casing 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 lies within any range of two of the above values. If the thickness of the casing 21 is within the above range, the casing 21 exhibits high mechanical strength, which can improve the reliability and cycle performance of the battery cell 7, and the casing 21 occupies less space, thus providing more space inside the casing 21, which contributes to improving the energy density of the battery cell 7.

[0117] The electrode assembly 10 can have a stacked or a wound structure.

[0118] This will be described below using the example of a stacked electrode assembly 10.

[0119] As in Fig.As shown in Figure 5, the electrode assembly 10 in the stacked structure comprises several positive electrode plates 11 and several negative electrode plates 12, wherein several positive electrode plates 11 and several negative electrode plates 12 are arranged one above the other along the thickness direction X of the battery cell 7. Preferably, the electrode assembly 10 also includes a separating film 13, wherein the separating film 13 is located between the positive electrode plate 11 and the negative electrode plate 12.

[0120] In some embodiments, such as in Fig. 5 and Fig.As shown in Figure 6, the positive electrode 11 comprises at least one positive electrode tab 111, wherein at least one positive electrode tab 111 is connected to the positive current collector 112 and extends out of the positive current collector 112 along the longitudinal direction Z of the battery cell 7. Alternatively, at least one positive electrode tab 111 can also be connected to the positive current collector 112 and extend out of the positive current collector 112 along the lateral direction Y of the battery cell 7.

[0121] In some embodiments, the negative electrode plate 12 comprises at least one negative electrode tab 121, wherein at least one negative electrode tab 121 is connected to the negative current collector 122 and extends out of the negative current collector 122 along the longitudinal direction Z of the battery cell 7. Alternatively, at least one negative electrode tab 121 can also be connected to the negative current collector 122 and extend out of the negative current collector 122 along the lateral direction Y of the battery cell 7.

[0122] In some embodiments, the positive electrode tab 111 is connected to at least one side of the positive current collector 112 along the longitudinal direction Z, wherein the negative electrode tab 121 is connected to at least one side of the negative current collector 122 along the longitudinal direction Z, wherein along the longitudinal direction Z of the battery cell 7 the dimension of the negative film layer 123 is larger than the dimension of the positive film layer 113 and the difference between the dimension of the negative film layer 123 and the dimension of the positive film layer 113 is OH1; along the lateral direction Y of the battery cell 7 the dimension of the negative film layer 123 is larger than the dimension of the positive film layer 113, and the difference between the dimension of the negative film layer 123 and the dimension of the positive film layer 113 is OH2, wherein OH1 is larger than OH2.

[0123] The negative electrode tab 121 is located on at least one side of the negative current collector 122 along the longitudinal direction Z, and the current density in the connection area between the negative electrode tab 121 and the negative current collector 122 increases significantly, so that problems such as lithium deposits can occur more easily in this area; In the embodiment of the present application, OH1 is larger than OH2, which improves the ability to absorb lithium ions in the longitudinal direction Z near the negative film layer 123, in particular the ability to absorb lithium ions in the area of ​​the negative film layer 123 near the negative electrode tab 121, thereby reducing the risk of lithium deposition and improving the reliability of the battery cell 7.

[0124] For example, OH1 is 0.5 mm to 3.0 mm, 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 lies in any range between two of the above values. Along the longitudinal direction Z, the negative film layer 123 projects beyond the positive film layer 113 on both sides by OH1 / 2 on each side, i.e., by half the dimension of OH1. OH1 / 2 is in Fig. 6 shown.

[0125] For example, OH2 is 0.5 mm to 3.0 mm, 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 lies within any range of two of the above values. Along the width direction Y, the negative film layer 123 projects beyond the positive film layer 113 on both sides by OH2 / 2 on each side, i.e., half the dimension of OH2. OH2 / 2 is in Fig. 6 shown.

[0126] In some embodiments, the battery cell comprises 7, as shown in Fig. Figure 7 shows a positive terminal 31, wherein the positive terminal 31 is attached to the outer housing 20 and can be attached to the housing 21 or the end cover 22.

[0127] The positive terminal 31 is electrically connected to the positive electrode tab 111. Preferably, the positive terminal 31 and the positive electrode tab 111 can be welded together, either by means of an adapter or without. Preferably, the positive terminal 31 and the positive electrode tab 111 can be connected without an adapter, i.e., directly welded together, thereby reducing the resistance at the connection point and lowering the internal resistance of the battery cell 7.

[0128] In some embodiments, the battery cell 7 also includes a negative terminal 32, wherein the negative terminal 32 is attached to the outer housing 20 and may be attached to the housing 21 or the end cover 22.

[0129] The negative terminal 32 is electrically connected to the negative electrode tab 121. Preferably, the negative terminal 32 and the negative electrode tab 121 can be welded together, either by means of an adapter or without. Preferably, the negative terminal 32 and the negative electrode tab 121 can be connected without an adapter, i.e., directly welded together, thereby reducing the resistance at the connection point and lowering the internal resistance of the battery cell 7.

[0130] Preferably, the number of positive terminals 31 on the same side of the electrode assembly 10 can be at least one, preferably at least two, wherein at least two positive terminals 31 can improve the overcurrent capability of the positive terminal 31.

[0131] Preferably, the number of negative terminals 32 on the same side of the electrode assembly 10 can be at least one, preferably at least two, wherein at least two negative terminals 32 can improve the overcurrent capability of the negative terminal 32.

[0132] In some embodiments, the positive electrode plate can comprise a positive current collector and a positive active material layer arranged on at least one surface of the positive current collector, wherein the positive active material layer comprises positive active material.

[0133] In some embodiments, the negative electrode plate may comprise a negative current collector and a negative active material layer arranged on at least one surface of the negative current collector, wherein the negative active material layer comprises negative active material.

[0134] In some embodiments, such as in Fig.As shown in Figure 8, the battery device 50 comprises a thermal insulation element 40 and at least two battery cells 7 arranged along a first direction F1, wherein the battery cell 7 comprises an electrode assembly and electrolyte solution, the electrode assembly comprises positive electrode plates and negative electrode plates, the positive electrode plate comprises positive current collectors and positive film layers arranged on at least one side of the positive current collectors, the positive film layer comprising lithium phosphate, wherein the negative electrode plate comprises negative current collectors and negative film layers arranged on at least one side of the negative current collector, the negative film layer comprising graphite particles; where, the electrolyte solution comprises a fluorosulfonylimide salt, wherein the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is between 2% and 12%; wherein the battery cell 7 comprises two first surfaces 211 which are opposite each other along the first direction F1, wherein the thermal insulation element 40 covers at least one of the two first surfaces 211 and the dimension of the thermal insulation element 40 along the first direction F1 is 0.3 mm to 5 mm.

[0135] On the one hand, the embodiment of the present application includes the selection of a material system wherein the positive active material comprises lithium phosphate and the negative active material comprises graphite particles, wherein the above-mentioned material system exhibits excellent cycle stability; when using the above-mentioned material system, the risk of thermal instability of the battery cell 7 is low;

[0136] On the other hand, lithium hexafluorophosphate can decompose HF to form hydrofluoric acid, and side reactions between hydrofluoric acid and the SEI film on the surface of the negative active material, for example graphite, can lead to increased gas formation during storage at high temperatures. The electrolyte solution of this application also includes fluorosulfonylimide salt; however, an amount of less than 2% fluorosulfonylimide salt has no significant effect on improving the thermal stability of the electrolyte solution. The addition of fluorosulfonylimide salts with a mass fraction of at least 2% can reduce the amount of hexafluorophosphate added, thereby reducing the content of hydrofluoric acid produced by the decomposition of hexafluorophosphate and mitigating hydrofluoric acid damage to the SEI film. This improves the protective effect of the SEI film on the negative active material and increases the cycle performance of the battery cell.

[0137] However, with increasing addition of fluorosulfonylimide salts, the risk of heat dissipation increases; in particular, the thermal decomposition temperature of fluorosulfonylimide salts is close to the thermal instability temperature of battery cell 7, and fluorosulfonylimide salts decompose rapidly, releasing a large amount of heat and hot gases, which leads to a sharp increase in the temperature inside battery cell 7, so that the large amount of heat cannot be dissipated quickly and thermal instability occurs;

[0138] However, the amount of fluorosulfonylimide salt added in the embodiment of the present application is not too high and is at most 12%. Furthermore, a thermal insulation element 40 with a predetermined dimension is attached to the first surface 211 of the battery cell 7. For example, the dimension of the thermal insulation element 40 along the first direction F1 is greater than or equal to 0.3 mm, giving the thermal insulation element 40 excellent thermal insulation properties and effectively preventing the rapid transfer of heat to other battery cells 7. This reduces the risk of heat propagation and increases the reliability of the battery device 50. While the thermal insulation effect increases with increasing size of the thermal insulation element 40, the energy density of the battery device 50 decreases due to the increased space requirement of the thermal insulation element 40.Therefore, the dimension of the thermal insulation element 40 along the first direction F1 is limited to less than or equal to 5 mm in order to improve both the reliability and the energy density of the battery device 50.

[0139] This allows the embodiment of the present application to improve both the cycle performance and the reliability of the battery device 50 and to increase the energy density of the battery device 50.

[0140] In some embodiments, the volume energy density of battery cell 7 ranges from 400 Wh / L to 530 Wh / L. For example, the volume energy density of 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 lies within any range of two of the above values. The volume energy density of battery cell 7 is relatively high.

[0141] In the embodiment of the present application, the volume energy density of the battery cell 7 has the meaning generally known in this field and can be measured with the devices and methods generally known in this field, for example, the maximum charging voltage of the battery is 3.65 V and the discharge cut-off voltage of the battery is 2.0 V.

[0142] Place battery cell 7 at 25 °C, charge it to 3.65 V with a constant current of 0.33 C and then with a constant voltage down to 0.05 C, discharge it to 2.0 V with a constant current of 0.33 C, record the discharge capacity A0 at this time, unit: Ah, measure the length, width and height of battery cell 7 with calipers (generally calculated from the dimensions of the battery casing, excluding the height of the electrode terminals and the insulating film outside the casing) and calculate the volume of battery cell V0, unit: L, the volume energy density VED of battery cell 7 = (A0 × discharge platform voltage) / V0, unit: Wh / L.

[0143] In some embodiments, the volume energy density of the battery cell 7 can be improved by the following preferred methods for increasing the energy density:

[0144] From the perspective of the active material, positive and negative active materials with high specific capacity can be used. For example, a lithium phosphate material with a higher gram capacity can be used for the positive active material, e.g., by physically mixing it with a higher gram capacity positive active material, such as ternary materials, to increase the energy density. Similarly, graphite with a higher gram capacity can be used for the negative active material, e.g., by physically mixing it with a higher capacity negative active material, such as a silicon-based material.

[0145] From the perspective of the electrolyte solution, the energy density of battery cell 7 can be increased by reducing the amount of electrolyte solution added or by using an electrolyte solution that supports a higher energy density.

[0146] From the point of view of the electrode plate design, the energy density of the battery cell 7 can be increased by adjusting the compaction density and the coating weight of the positive or negative electrode plate, e.g. by increasing the compaction density or the coating weight or by reducing the thickness of the positive or negative current collector;

[0147] From the perspective of the separating film, the energy density of battery cell 7 can be increased by adjusting the thickness of the separating film, e.g. by reducing the thickness of the separating film.

[0148] Regarding the design, the proportion of inactive materials such as battery components can be reduced. For example, the battery casing can be made thinner while maintaining its safety and mechanical performance, allowing more active materials to fit into the same space and increasing energy density, e.g., by adjusting the space allocated to the electrode assembly within the casing.

[0149] At least two battery cells 7 are arranged along the first direction F1, i.e., 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.

[0150] In the embodiment of the present application, the housing of the battery cell 7 can have a rectangular structure, wherein the first direction F1 can run parallel to the thickness direction of the battery cell 7.

[0151] The second direction F2 can run parallel to the longitudinal direction of battery cell 7 or to the transverse direction of battery cell 7. If the second direction F2 runs parallel to the longitudinal direction of battery cell 7, the third direction F3 runs parallel to the transverse direction of battery cell 7; if the second direction F2 runs parallel to the transverse direction of battery cell 7, the third direction F3 runs parallel to the longitudinal direction of battery cell 7.

[0152] The battery cell 7 comprises two first surfaces 211 which are opposite each other along the first direction F1.

[0153] If the first surface 211 is larger than the second surface 212, the first surface 211 is the largest surface of the rectangular structure, and the thermal insulation element 40 covers at least part of the first surface 211, thereby effectively reducing heat transfer. The thermal insulation element 40 can cover at least part of the first surface 211, for example, the entire first surface 211, or only part of the first surface 211. [Thermal insulation element]

[0154] As in Fig. As shown in Figure 8, the thermal insulation element 40 covers at least one of the two first surfaces 211 of the battery cell 7, thereby reducing heat propagation and increasing the reliability of the battery device 50.

[0155] As in Fig. 8 and Fig.As shown in Figure 9, the thermal insulation element 40 covers at least one of the two first surfaces 211 of the battery cell 7, thereby reducing heat transfer.

[0156] In some embodiments, the thermal insulation element 40 covers part of the two first surfaces 211 of the battery cell 7 and covers the other part of the first surface 211 of the battery cell 7. For example, the thermal insulation element 40 is arranged between two adjacent battery cells 7, wherein several battery cells 7 along the first direction F1 do not have a thermal insulation element on their outside.

[0157] As in Fig.As shown in Figure 10, in other embodiments the thermal insulation element 40 covers the two first surfaces 211 of the battery cell 7. For example, the thermal insulation element 40 is arranged between two adjacent battery cells 7, with several battery cells 7 having thermal insulation element 40 on their outside along the first direction F1.

[0158] As in Fig. As shown in Figure 11, in some embodiments the thermal insulation element 40 covers one of the two first surfaces 211 of the battery cell 7.

[0159] For example, there are six battery cells 7, wherein the six battery cells 7 are arranged along the first direction F1, wherein a thermal insulation element 40 is arranged between the first battery cell 7 and the second battery cell 7, a thermal insulation element 40 is arranged between the third battery cell 7 and the fourth battery cell 7, and a thermal insulation element 40 is arranged between the fifth battery cell 7 and the sixth battery cell 7.

[0160] The thermal insulation element 40 can have a plate construction or another construction form.

[0161] In the embodiment of the present application, the thermal insulation element 40 has a dimension of 0.3 mm to 5 mm along the first direction F1, for example 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 lies in any range between two of the above-mentioned values. Preferably, the dimension of the thermal insulation element 40 along the first direction F1 can be between 0.5 mm and 2.5 mm. Fig. 8 denotes the dimension of the thermal insulation element 40 along the first direction F1.

[0162] The dimension of the thermal insulation element 40 along the first direction F1 can be understood as the thickness of the thermal insulation element 40. Within the aforementioned area, it can effectively reduce heat transfer and occupies only a small space in the battery device 50, thereby increasing the energy density of the battery device 50.

[0163] With increasing mass fraction of fluorosulfonylimide salt, the heat released during a thermal instability of the battery cell 7 increases, and thus the intensity of the thermal instability increases; In combination with fluorosulfonylimide salt, the thermal insulation element 40 can have a suitable thickness to improve the ability of the thermal insulation element 40 to reduce heat propagation.

[0164] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 6%; the dimension of the thermal insulation element 40 along the first direction F1 is 0.5 mm to 1.0 mm.

[0165] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is more than 6% and less than or equal to 8%; the dimension of the thermal insulation element 40 along the first direction F1 is more than 1.0 mm and less than or equal to 1.5 mm.

[0166] In some embodiments, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is more than 8% and less than or equal to 12%; the dimension of the thermal insulation element 40 along the first direction F1 is more than 1.5 mm and less than or equal to 2.5 mm.

[0167] As the volume energy density of the battery cell 7 increases, more heat is released in the event of thermal instability; in accordance with the volume energy density of the battery cell 7, the thermal insulation element 40 can have a suitable thickness to improve the ability of the thermal insulation element 40 to reduce heat propagation.

[0168] In some embodiments, the volume energy density of the battery cell 7 is 400 Wh / L to 440 Wh / L; the dimension of the thermal insulation element 40 along the first direction F1 is 0.5 mm to 1.0 mm.

[0169] In some embodiments, the volume energy density of the battery cell 7 is more than 440 Wh / L and less than or equal to 490 Wh / L; the dimension of the thermal insulation element 40 along the first direction F1 is more than 1.0 mm and less than or equal to 1.5 mm.

[0170] In some embodiments, the volume energy density of the battery cell 7 is more than 490 Wh / L and less than or equal to 530 Wh / L; the dimension of the thermal insulation element 40 along the first direction F1 is greater than 1.5 mm and less than or equal to 2.5 mm.

[0171] In some embodiments, the battery cell comprises 7, as shown in Fig.Figure 12 shows two first surfaces 211 facing each other along the first direction F1, with the thermal insulation element 40 covering the first surface 211. If the battery cell housing 7 has a rectangular structure, the first surface 211 can be the largest surface of the rectangular structure, with the thermal insulation element 40 covering the first surface 211, thereby effectively reducing heat transfer.

[0172] In some embodiments, the battery device 50 satisfies the following condition: 0.9 ≤ S2 / S1 ≤ 1, where S1 is the area of ​​the first surface 211 in mm² 2 designated; where S2 is the area of ​​the projection surface of the thermal insulation element 40 perpendicular to the first direction F1 in mm² 2 designated.

[0173] For example, S2 / S1 is 0.9, 0.92, 0.94, 0.95, 0.98, 1.0, or lies within any range of two of the above values. The area of ​​the surface of the in Fig. The thermal insulation element shown in 12 is S2, the first surface 211 of the battery cell 7 is S1.

[0174] If the battery device 50 meets the above-mentioned condition, the thermal insulation element 40 covers a relatively large part of the first surface and can thus reduce heat transfer more effectively.

[0175] In some embodiments, the battery cell comprises 7 electrode terminals, for example a positive terminal 31 and a negative terminal 32, wherein the electrode terminals are connected to at least one side of the electrode assembly along the second direction F2, wherein the second direction F2 is perpendicular to the first direction F1.

[0176] Whereby the battery device 50 satisfies the following condition: 0.8 ≤ L2 / L1 ≤ 1, where L1 denotes the dimension of the first surface 211 along the second direction F2 in mm where L2 denotes the dimension of the thermal insulation element 40 along the second direction F2 in mm.

[0177] For example, L2 / L1 is 0.8, 0.82, 0.84, 0.85, 0.88, 0.9, 0.92, 0.94, 0.95, 0.98, 1.0, or lies within any range of any two of the above values. L1 and L2 are in Fig. 12 shown.

[0178] If the battery device 50 meets the above-mentioned condition, the thermal insulation element 40 covers a relatively large part of the first surface 211 and can thus reduce heat transfer more effectively.

[0179] In some embodiments, the battery device 50 also satisfies the following condition: 2 mm ≤ L1-L2 ≤ 10 mm.

[0180] For example, L1-L2 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any range between any two of the above values. Fig. 12 The first surface 211 projects beyond the thermal insulation element 40 on both sides, by (L1-L2) / 2 on each side, from 1 mm to 5 mm. Of course, the first surface 211 can also project beyond the thermal insulation element 40 on only one side.

[0181] If the battery device 50 meets the above-mentioned condition, the thermal insulation element 40 covers a relatively large part of the first surface and can thus reduce heat transfer more effectively.

[0182] In some embodiments, the battery device 50 satisfies the following condition: 0.9 ≤ H2 / H1 ≤ 1, where H1 denotes the dimension of the first surface 211 along the third direction F3 in mm, where the third direction F3, the second direction F2 and the first direction F1 are each perpendicular to each other; where H2 denotes the dimension of the thermal insulation element 40 along the third direction F3 in mm.

[0183] For example, H2 / H1 is 0.9, 0.92, 0.94, 0.95, 0.98, 1.0, or lies within any range of any two of the above values. H1 and H2 are in Fig. 12 shown.

[0184] If the battery device 50 meets the above-mentioned condition, the thermal insulation element 40 covers a relatively large part of the first surface 211 and can thus reduce heat transfer more effectively.

[0185] In some embodiments, the battery device 50 also satisfies the following condition: 1 mm ≤ H1-H2 ≤ 10 mm.

[0186] For example, H1-H2 can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any range of two of the above values. Fig. 12 The first surface 211 projects beyond the thermal insulation element 40 on both sides, by (H1-H2) / 2 on each side, from 0.5 mm to 5 mm. Of course, the first surface 211 can also project beyond the thermal insulation element 40 on only one side.

[0187] If the battery device 50 meets the above-mentioned condition, the thermal insulation element 40 covers a relatively large part of the first surface 211 and can thus reduce heat transfer more effectively.

[0188] In some embodiments, the thermal insulation element 40 can be bonded to the first surface 211, causing the thermal insulation element 40 to lie close to the first surface 211, thus reducing heat propagation. Of course, the thermal insulation element 40 can also simply lie close to the first surface 211 without being bonded to it.

[0189] In some embodiments, the thermal insulation element 40 comprises a thermal insulation body 41 and a support element 42, wherein the support element 42 is arranged annularly around the thermal insulation body 41 and both the thermal insulation body 41 and the support element 42 cover the surface of the battery cell 7 along the first direction F1, i.e. the first surface 211.

[0190] The support element 42 can support and fix the thermal insulation body 41, so that the thermal insulation body 41 can effectively exert its thermal insulation effect.

[0191] In some embodiments, such as in Fig. As shown in Figure 13, the support element 42 is an annular element arranged in a ring around the thermal insulation body 41 and provides effective support for the thermal insulation body 41. The annular element can be square, rectangular, round, or other in shape and can be adapted to the shape of the first surface 211. For example, if the first surface 211 is rectangular, the annular element is arranged as a rectangular structure.

[0192] In some embodiments, the support element 42 meets the following condition: 10 mm ≤ W1-W2 ≤ 60 mm.

[0193] W 1. denotes the dimension of the outer outline of the ring-shaped element along the second direction F2, where the second direction F2 is perpendicular to the first direction F1;

[0194] W2 denotes the dimension of the inner outline of the ring-shaped element along the second direction F2.

[0195] For example, W1-W2 can be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm or any range of two of the above values. Fig. Figure 13 shows W1 and W2, where the dimensions at different points of the ring-shaped element are essentially the same and (W1-W2) / 2 can be considered as the dimension of the ring-shaped element along the second direction F2.

[0196] If the support element 42 meets the above-mentioned condition, it can effectively support and fix the thermal insulation body 41.

[0197] In some embodiments, the support element 42 meets the following condition: 10 mm ≤ W3-W4 ≤ 60 mm.

[0198] W3 denotes the dimension of the outer outline of the ring-shaped element along the third direction F3, wherein the third direction F3, the second direction F2 and the first direction F1 are each perpendicular to each other;

[0199] W4 denotes the dimension of the inner outline of the ring-shaped element along the third direction F3.

[0200] For example, W3-W4 can be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm or any range of two of the above values. Fig. Figure 13 shows W3 and W4, where the dimensions at different points of the ring-shaped element are essentially the same and (W3-W4) / 2 can be regarded as the dimension of the ring-shaped element along the third direction F3.

[0201] If the support element 42 meets the above-mentioned condition, it can effectively support and fix the thermal insulation body 41.

[0202] In some embodiments, the thermal insulation body 41 comprises, as in Fig. Figure 14 shows a thermal insulation material, wherein G in Fig. 11 refers to the thermal insulation material.

[0203] In some embodiments, the thermal insulation material comprises one or more types of aerogel, foam, polyurethane, or silicone rubber. The aforementioned materials exhibit excellent thermal insulation properties and can effectively reduce heat loss.

[0204] In some embodiments, the material of the support element 42 can comprise fiber materials; preferably, the fiber materials can comprise one or more of polysaccharide, polyethylene terephthalate, polyurethane, polyacrylonitrile, polypropylene, polyamide, and aromatic polyamide. The above-mentioned materials exhibit excellent support properties and can effectively support the thermal insulation material. [Electrolyte solution]

[0205] The battery cell contains an electrolyte solution. During charging and discharging of the battery cell, active ions, such as lithium ions, are embedded between and released from the positive and negative electrode plates, and the electrolyte solution acts as a conductor of the active ions between the positive and negative electrode plates.

[0206] In the embodiment of the present application, the electrolyte salt comprises a fluorosulfonylimide salt, wherein the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 12%, for example 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, or lies in any range between two of the above values. Preferably, the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 4% to 8%.

[0207] If the mass fraction of fluorosulfonylimide salt is less than 2%, this can lead to a higher addition of hexafluorophosphate to the electrolyte solution, causing the HF content to become too high and damaging the SEI film, resulting in cycle degradation; furthermore, the improvement in the thermal stability of the electrolyte solution is limited if the addition of fluorosulfonylimide salt is too low;

[0208] If the mass fraction of fluorosulfonylimide salt exceeds 12%, thermal instability can lead to excessive intensity and heat dissipation, transferring heat to other battery cells. This, in turn, causes thermal instability in those cells and impairs the reliability of the battery device. In the embodiment of the present application, if the mass fraction of the fluorosulfonylimide salt is within the aforementioned range, both the cycle performance and the reliability of the battery device can be improved.

[0209] For example, the fluorosulfonylimide salt comprises one or more of the difluorosulfonylimide salts, difluoromethanesulfonylimide salts, and perfluorobutylsulfonylimide salts. The materials mentioned above can improve both the cycle performance and the reliability of the battery device.

[0210] In some embodiments, the electrolyte solution also includes hexafluorophosphate, wherein the mass fraction of hexafluorophosphate in the electrolyte solution is 3% to 13%, for example 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, or lies in any range of two of the above values.

[0211] The combined use of fluorosulfonylimide salt and hexafluorophosphate contributes to improving the cycle performance and reliability of the battery device.

[0212] If the electrolyte salt includes lithium salts, the fluorosulfonylimide salt may include lithium fluorosulfonylimide; for example, lithium fluorosulfonylimide includes one or more of lithium bifluorosulfonamide, lithium bis(trifluoromethanesulfonyl)imide, and lithium perfluorobutylsulfonimide. Hexafluorophosphate may include lithium hexafluorophosphate.

[0213] In some embodiments, the electrolyte solution comprises organic solvents, wherein the organic solvents include carboxylic ester solvents, the mass fraction of the carboxylic ester solvent in the electrolyte solution being 8% to 60%. For example, the mass fraction of the carboxylic ester solvent is 8%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, or lies in any range between two of the above values. When the mass fraction of carboxylic ester solvent is greater than or equal to 8%, the viscosity of the electrolyte system is relatively low, which favors the migration of lithium ions; when the mass fraction of carboxylic ester solvent is less than or equal to 60%, relatively few side reactions occur between the carboxylic ester solvent and the negative active material, which improves cycle performance.

[0214] In some embodiments, the carboxylic acid ester solvent can comprise one or more linear and cyclic carboxylic acid ester solvents, with the linear carboxylic acid ester solvent being preferred. The carboxylic acid ester solvent exhibits lower viscosity and better flowability, which facilitates rapid wetting of the electrode plate. Local lithium deposition on the surface of the negative electrode plate is less likely, thus increasing the reliability of the battery cell.

[0215] For example, the carboxylic acid ester solvent comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate.

[0216] The materials mentioned above have a lower viscosity and can further improve the reliability of the battery cells.

[0217] In the embodiment of the present application, the organic solvents also include carbonate solvents whose mass fraction in the electrolyte solution is between 18% and 70%. For example, the mass fraction of the carbonate solvent in the electrolyte solution is 18%, 20%, 25%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, 65%, 70%, or lies in any range between two of the above values.

[0218] The above-mentioned mass fractions of carbonate solvent can further improve the viscosity of the electrolyte solution, increase the wetting performance of the electrode plate, reduce local lithium deposition on the surface of the negative electrode plate, and improve the reliability of the battery cell.

[0219] For example, the carbonate solvent comprises one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methylethyl carbonate.

[0220] The materials mentioned above have a relatively low viscosity, which promotes rapid wetting of the electrode plate. Local lithium deposition is less likely to occur on the surface of the negative electrode plate, thus increasing the reliability of the battery cell.

[0221] In the embodiment of the present application, the electrolyte solution also comprises an additive, wherein the additive is one or more carbonate ester additives, sulfur-containing additives, and lithium salt additives. The additive can participate in the formation of the SEI film on the cathode side, thereby improving the protective effect for the negative active material, reducing gas evolution on the cathode side, mitigating the risk of thermal instability due to gas accumulation, and effectively improving the cycle performance of the battery cell.

[0222] In some embodiments, the mass fraction of the carbonate ester additive in the electrolyte solution is 2.5% to 10.0%, for example, 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 lies within any range of two of the above values. If the mass fraction of the carbonate ester additive is within the above range, the cycle performance of the battery cell can be effectively improved.

[0223] In some embodiments, the carbonate ester additive comprises one or more derivatives of vinylidene carbonate and vinyl carbonate, wherein the vinyl carbonate derivatives comprise the compounds shown in formula A, wherein in formula A Q1, Q2, Q3 and Q4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, and Qi, Q2, Q3 and Q4 are not simultaneously hydrogen atoms.

[0224] Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms, i.e. at least one of Q1, Q2, Q3 and Q4 comprises a halogen atom, C1 to C5 alkyl group or C1 to C5 halogen alkyl group.

[0225] For example, one of Q1, Q2, Q3 and Q4 comprises a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, while the remaining residues are hydrogen atoms.

[0226] For example, at least two of Q1, Q2, Q3 and Q4 comprise a halogen atom, a C1 to C5 alkyl group or a C1 to C5 halogen alkyl group.

[0227] For example, at least three of Q1, Q2, Q3 and Q4 comprise a halogen atom, a C1 to C5 alkyl group or a C1 to C5 halogen alkyl group.

[0228] For example, Q1, Q2, Q3 and Q4 each independently comprise a halogen atom, C1 to C5 alkyl group or C1 to C5 halogen alkyl group.

[0229] Preferably, at least one of Q1, Q2, Q3, and Q4 comprises a halogen atom or a C1 to C5 haloalkyl group. The halogen atom comprises a fluorine atom, bromine atom, or chlorine atom, etc., and may preferably be a fluorine atom. The C1 to C5 haloalkyl group comprises a C1 to C5 fluoroalkyl group, a C1 to C5 bromoalkyl group, or a C1 to C5 chloroalkyl group, etc., and may preferably be a fluorine atom. For example, the C1 to C5 fluoroalkyl group comprises a fluoromethyl group, a fluoroethyl group, a fluoropropyl group, a fluorobutyl group, or a fluoropentyl group.

[0230] If the vinyl carbonate derivative includes a fluorine atom, the vinyl carbonate derivative can form an F- and Li-rich film layer on the cathode side, which, based on the protection of the negative active material, enables a low resistance of the film layer and thus more effectively improves the high-temperature cycle performance and fast-charging capability of the battery cells.

[0231] For example, the vinyl carbonate derivative comprises one or more of the compounds shown in Formula A-1 to Formula A-6,

[0232] The materials mentioned above can further improve the high-temperature cycle performance and fast-charging capability of the battery cell.

[0233] Preferably, the vinyl carbonate derivative comprises one or more of the compounds shown in Formula A-1 to Formula A-3, and preferably, the vinyl carbonate derivative comprises the compound shown in Formula A-1.

[0234] In some embodiments, the mass fraction of the sulfur-containing additive in the electrolyte solution is 0% to 2%, for example, 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, or lies in any range between two of the above values. The sulfur-containing additive can form a dense SEI film on the cathode side, effectively reducing the risk of a side reaction between the carboxylic acid ester solvent penetrating the SEI film and the negative active material, decreasing gas evolution, and improving the cycle performance of the battery cell.

[0235] Let's take as an example a mass fraction of the sulfur-containing additive of 0%. It could be a freshly prepared electrolyte solution without the addition of sulfur-containing additives, or electrolyte solution obtained after disassembly of the battery cell that does not contain sulfur-containing additives. In this case, no sulfur-containing additives may be added to the freshly prepared electrolyte solution, or only a small amount of sulfur-containing additives may be added, which, however, are involved in the formation of the SEI film during the battery cell manufacturing process, so that the mass fraction of sulfur-containing additives is 0 in the analysis.

[0236] Preferably, the freshly prepared electrolyte solution may contain a sulfur-containing additive.

[0237] Furthermore, the additive content in the battery cell's electrolyte solution depends on the battery cell's condition after formation, its lifespan, and its storage conditions, due to the additives' role in forming the layer on the active material's surface. Therefore, differences can occur between the additive content of freshly prepared electrolyte solution and that of electrolyte solution from a reverse-disassembled battery. However, experts in this field can determine the approximate content of the relevant substances in the fresh electrolyte solution based on the battery cell's performance characteristics (e.g., number of cycles) and the residual content. Similarly, experts in this field can estimate the approximate content of additives that are not freshly prepared (i.e., not freshly prepared) based on the content of freshly prepared additives, taking into account the battery cell's performance requirements and storage conditions.Determine recovered additives.

[0238] Therefore, the additive content mentioned in the present application can either be the content of additives that are actively added to the freshly produced electrolyte solution, or the content of residual additives that are recovered based on the actual state of the battery.

[0239] In some embodiments, the sulfur-containing additive comprises one or more of ethylene sulfate, vinyl bisulfate, 1,3-propanesulfonic acid lactone, butyl sulfite, vinyl sulfite, methylene disulfonate.

[0240] In some embodiments, the mass fraction of the lithium salt additive in the electrolyte solution is 0% to 1%, for example, 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, or lies within any range of two of the values ​​mentioned above. The lithium salt additive contributes to film formation and optimizes the composition of the SEI film. The lithium salt additive can contribute to the formation of an inorganic SEI film, with the inorganic components improving the high-temperature and high-pressure stability of the SEI film and enhancing the cycle performance of the battery cell.

[0241] If the mass fraction of the lithium salt additive is 0, this means that no lithium salt additive can be added to the freshly produced electrolyte solution or that the electrolyte solution obtained from the disassembly of the battery cell does not include any cycle power.

[0242] In some embodiments, the lithium salt additive comprises one or more of lithium difluorophosphate, lithium borate difluorooxalate, lithium tetrafluoroborate and lithium borate bis(oxalate).

[0243] In the embodiment of the present application, the types and concentrations of the inorganic components / lithium salts in the electrolyte solution have a meaning generally known in this field and can be measured using equipment and methods generally known in this field; for example, with reference to the standard JY / T 0575-2020 "General rules for ion chromatography analysis", a qualitative or quantitative analysis of the inorganic components / lithium salts in the electrolyte solution can be carried out by means of ion chromatography analysis.In the embodiment of the present application, newly produced electrolyte solution can be taken as a sample, free electrolyte solution can be taken from a new battery as a sample, or a completely discharged battery cell (which has been discharged to the discharge cut-off voltage, so that the state of charge of the battery cell is approximately 0% SOC) can be reverse disassembled to take free electrolyte solution from the battery cell as a sample, which is analyzed by means of ion chromatography.

[0244] In the embodiment of the present application, the types and concentrations of the organic components in the electrolyte solution have a meaning generally known in this field and can be measured using equipment and methods generally known in this field; for example, with reference to GB / T9722-2006 “Chemical reagents - General rules for gas chromatography”, a qualitative and quantitative analysis of the organic components in the electrolyte solution can be carried out by means of gas chromatography. [Positive electrode plate]

[0245] The positive electrode plate comprises a positive current collector and a positive film layer arranged on at least one surface of the positive current collector and comprising positive active material. For example, the positive current collector has two surfaces opposite in its thickness direction, with the positive film layer arranged on one or both of the two opposite surfaces of the positive current collector.

[0246] In some embodiments, the compaction density of the positive film layer in a battery cell at 100% charge is 2.6 g / cm³. 3 up to 2.8 g / cm³ 3 For example, the density of the positive film layer in a battery cell at 100% charge is 2.6 g / cm³. 3 , 2.65 g / cm³ 3 , 2.7 g / cm³ 3 , 2.75 g / cm³ 3 , 2.8 g / cm³ 3 or lies within any range of two of the values ​​mentioned above.

[0247] If the density of the positive film layer is within the range mentioned above, this contributes to increasing the energy density of the battery cell. Since the positive active material of the positive film layer is relatively densely packed, the contact resistance between the particles is low, which further reduces the resistance of the electrode plate, thereby reducing heat generation and improving the cycle performance of the battery cell.

[0248] In some embodiments, the one-sided coating weight of the positive film layer is 220 mg / 1540.25 mm². 2 up to 450 mg / 1540.25 mm 2 , for example 220 mg / 1 540.25 mm 2 , 230 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2, 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 , 380 mg / 1540.25 mm 2 , 400 mg / 1540.25 mm 2 , 420 mg / 1540.25 mm 2 , 450 mg / 1540.25 mm 2 or lies within any range of two of the values ​​mentioned above.

[0249] If the one-sided coating weight of the positive film layer is within the above-mentioned range, this contributes to increasing the energy density of the battery cell, and the heat generation per unit area of ​​the positive electrode plate is not too high, which improves the cycle performance of the battery cell.

[0250] The maximum charging voltage and the discharge cut-off voltage of the battery cell differ depending on the positive active material. For example, if the phosphate material contains lithium iron phosphate, the maximum charging voltage can be 3.65 V and the discharge cut-off voltage 2.0 V. If, for example, the phosphate materials include lithium manganese iron phosphate, the maximum charging voltage can be 4.2 V and the discharge cut-off voltage 2.0 V. The following describes the state of the battery cell using the example of a maximum charging voltage of 3.65 V and a discharge cut-off voltage of 2.0 V: 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:

[0251] The battery cell is charged at a constant charging current of 0.33C up to the maximum charging voltage and then charged at a constant voltage of 0.05C, which corresponds to a state of 100% SOC (State of Charge) of the battery cell. The battery cell is then discharged at a constant discharge current of 0.33C down to the cutoff voltage, which corresponds to a state of 0% SOC of the battery cell.

[0252] In the embodiment of the present application, the density of the positive film layer below 100% state of charge (SOC) of the battery cell can be measured using the following method: The positive electrode plate is removed from the battery cell, the density of the positive film layer is determined, e.g., by taking a positive electrode plate coated with a single-sided coating (in the case of an electrode plate coated with a double-sided coating, one of the positive film layers can be wiped off first), the positive electrode plate is punched and cut into small discs with an area of ​​S1, weighed, recorded as M1, and the thickness H1 is measured. Then, after weighing, the positive film layer of the positive electrode plate is wiped off, the positive current collector is weighed, recorded as M0, and its thickness H0 is measured.Weight of the one-sided coated positive film layer = (weight of the positive electrode plate M1 - weight of the positive current collector M0) / S1, and thickness of the positive film layer = thickness of the positive electrode plate H1 - thickness of the positive current collector H0, and the compaction density of the positive film layer = one-sided coating weight of the positive film layer / thickness of the positive film layer.

[0253] In the event that the battery cell is a lithium-ion battery, The lithium phosphate can have an olivite structure, and the modified compound can be a material modified by doping or coating; for example, lithium phosphate comprises the phosphate particle and a positive cover layer, wherein the positive cover layer covers at least part of the phosphate particle surface and the positive cover layer comprises a carbon element.

[0254] Coating the phosphate particles with the positive top layer improves the conductivity of the lithium phosphate, which promotes the migration rate of lithium ions, increases the fast charging capability of the battery, reduces the heat generation of the battery cell and improves the high-temperature cycle performance of the battery cell.

[0255] For example, the phosphate particles comprise one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, and lithium cobalt phosphate. The materials mentioned above exhibit excellent cycle stability and can improve the cycle performance of the battery cell.

[0256] In some embodiments, the lithium phosphate comprises 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, where A comprises one or more of the elements Na, K and Mg, Me comprises one or more of the elements Mn, Fe, Co and Ni, M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge and Ce are included, X includes one or more of the elements Cl, C, N and P, Y includes one or more of the elements O and F.

[0257] The lithium phosphate exhibits excellent cycle stability, which contributes to improving the cycle performance of the battery cell.

[0258] For example, the phosphate particles comprise one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. During charging and discharging, the battery cell undergoes the deposition and consumption of active ions, such as lithium, and the battery cell exhibits varying molar concentrations of lithium as it discharges to different states. When listing the active materials LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., the molar concentration of lithium represents the initial state of the material, i.e., the state before input. The molar concentration of lithium can change when the active material is introduced into the battery system after a charge and discharge cycle. The molar concentration of oxygen (O) in the active materials LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, etc., is also relevant., which are listed in the embodiment of the present application, is only the theoretical state value, and the release of oxygen from the crystal lattice leads to a change in the molar content of oxygen O, and in practice the molar content of oxygen O can fluctuate, and the above-mentioned situations fall within the scope of protection of the present application.

[0259] In some embodiments, the mass fraction of the carbon element, based on the weight of the lithium phosphate, is 0.8% to 2.3%, for example 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 lies in any range between two of the above values.

[0260] Carbon is primarily present in the form of a carbon cover layer within the positive surface layer. This carbon cover layer is loose and porous, increasing the material's specific surface area and facilitating effective contact between the electrolyte solution and the phosphate particles. This, in turn, promotes the transport of lithium ions at the interface. Furthermore, the mass fraction of carbon in this area significantly improves the conductivity of the lithium phosphate within the olivite structure. This enhances both the ionic and electronic conductivity of the lithium phosphate within the olivite structure, thereby improving the fast-charging capability of the battery cell at high energy density.

[0261] In some embodiments, the positive top layer also comprises one or more of the elements Fe, Ti, Zr, Hf, Ge and Sn.

[0262] In some embodiments, the positive cover layer comprises a compound of the general formula Li 3-d1 Fe 2-d1 M3 d1 (POm1) n1 , where 0 ≤ d1 ≤ 1,3 ≤ m1 ≤5,2 ≤ n1 ≤ 4 and M3 comprises one or more of the elements Ti, Zr, Hf, Ge and Sn.

[0263] The Li connection 3-d1 Fe 2-d1 M3 d1 (PO m1 ) n1 is a fast ion conductor with NASICON structure and comprises, for example, one or more of lithium iron titanate phosphate Li2FeTi(PO4)3, lithium iron zirconate phosphate Li2FeZr(PO4)3, lithium iron tinnate phosphate Li2FeSn(PO4)3.

[0264] Fast ion conductor with NASICON structure is a material with extremely fast ion conductivity. It features numerous three-dimensional diffusion and transport channels for lithium ions and is characterized by high ion conductivity and structural stability during repeated lithium debedding and embedding processes. Coating the phosphate particle surface with a fast ion conductor with NASICON structure significantly increases the lithium ion transfer rate during repeated lithium debedding and embedding at the positive terminal. This improves the ion conductivity of the positive active material, enhances the fast-charging capability of the battery cell, and further improves the gram capacity and energy density of the corresponding battery cell.

[0265] Carbon and fast ion conductors can be arranged in layers, for example, as a separate carbon cover layer and a separate layer of fast ion conductors. The carbon cover layer can cover the phosphate particle surface, with the fast ion conductor layer located on the surface of the carbon cover layer (i.e., the fast ion conductor layer is on the side of the carbon cover layer facing away from the phosphate particles). Alternatively, the fast ion conductor layer can cover the phosphate particle surface, with the carbon cover layer located on the surface of the fast ion conductor layer (i.e., the carbon cover layer is on the side of the fast ion conductor layer facing away from the phosphate particles). Of course, carbon and the fast ion conductor can also be arranged in the same layer.

[0266] Preferably, the carbon cover layer can be applied to the surface of the fast ion conductor layer by a carbonization process using an organic carbon source (e.g., glucose, polyethylene glycol, etc.). The carbon cover layer can partially or completely cover the fast ion conductor layer. The arrangement of the carbon cover layer can significantly improve the electronic conductivity of the phosphate particles, compensate for their lack of electronic conductivity, and increase the energy density of the battery cell.

[0267] The positive active material of this application is based on phosphate particles and utilizes their advantages such as low cost, high reliability, and good cycle performance. At the same time, the disadvantages of poor electronic and ionic conductivity are overcome by the positive cover layer (a layer of fast ionic conductors and a carbon cover layer). Provided that the positive active material of this application is excellent, the battery cell manufactured from this application can improve its energy density.

[0268] In the embodiment of the present application, the elemental content of the positive active material, as defined in the technical term, is known and can be measured using equipment and methods known in the art. For example, the measurement is carried out by inductively coupled plasma atomic emission spectrometry (ICP-OES, instrument model: Thermo ICAP7400) in accordance with EPA 6010D-2014. After discharging the battery cell to 0% state of charge (SOC) and disassembling the positive electrode plate, it was cleaned with DMC and dried, and then calcined at high temperature to remove impurities. 0.4 g of the positive active material was weighed out, and 10 ml (50% concentration) of aqua regia was added. The mixture was then placed on the plate for 30 minutes at 180 °C. After dissolution on the plate, the solution was fixed to a volume of 100 mL, and the quantitative test was performed using the standard curve method.

[0269] In some embodiments, the positive film layer may preferably also comprise a positive conductive element. The embodiment of the present application does not impose any particular restrictions regarding the type of positive conductive element. For example, the positive conductive element comprises at least one of the following elements, such as superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofiber. In some embodiments, the mass fraction of the positive conductive element is ≤ 5% based on the mass of the positive film layer.

[0270] In some embodiments, the positive film layer may preferably also comprise a positive binder. The embodiment of the present application does not contain any specific restrictions regarding the type of positive binder. For example, the positive binder may comprise one or more of polyvinylidene fluoride, polytetrafluoroethylene, a terpolymer of vinylidene fluoride, tetrafluoroethylene and propylene, a terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, polyacrylic acid, and fluorinated acrylic ester resins. In some embodiments, the mass fraction of the positive binder is ≤ 5% based on the mass of the positive film layer.

[0271] In some embodiments, the positive current collector can be a metal foil or a composite current collector. For example, a metal foil can be made of one or more foils of aluminum, aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, or a silver alloy. The composite current collector can comprise a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The metal material in the metal layer can, for example, include one or more of the following materials: aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or a silver alloy. The polymer base layer can, for example, include one or more of the following materials: polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0272] In some embodiments, the thickness of the positive current collector is 10 µm to 15 µm. When the thickness of the positive current collector is within the aforementioned range, it is advantageous to increase the overcurrent capability and improve the fast-charging capability of the battery cell.

[0273] The positive electrode layer is typically formed by applying the positive electrode slurry to the positive current collector, drying, and cold pressing. The positive electrode slurry is generally formed by dispersing the positive active material, an optional conductive agent, an optional binder, and all other components in a solvent and mixing thoroughly. The solvent may include, but is not limited to, N-methylpyrrolidone (NMP).

[0274] The positive electrode plate does not preclude additional functional layers besides the positive film layer. In some embodiments, the positive electrode plate of the embodiment of the present application, for example, further comprises a positive conductive layer located between the positive current collector and the positive film layer and provided on the surface of the positive current collector. In further embodiments, the positive electrode plate of the embodiment of the present application additionally comprises a protective layer covering the surface of the positive film layer.

[0275] In some embodiments, the positive electrode plate also includes a positive conductive layer located between the positive film layer and the positive current collector. This positive conductive layer can further improve the conductivity of the positive electrode plate, reduce heat generation from the positive electrode plate, and thus reduce the heat generation of the battery cell.

[0276] In some embodiments, the thickness of the positive conductive layer is 0.5 µm to 2 µm. For example, the thickness of the positive 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 any range between two of the above values.

[0277] If the thickness of the positive conductive layer is within the range mentioned above, it can further improve the conductivity of the positive electrode plate, reduce the heat generation of the positive electrode plate and thus reduce the heat generation of the battery cell, thereby improving the fast charging capability and high-temperature cycle performance of the battery cell at high energy density.

[0278] In the embodiment of the present application, the thickness of the positive conductive layer has a meaning generally known in this field and can be measured using devices and methods generally known in this field, for example by a tomographic examination of the positive electrode plate to directly measure the thickness of the positive conductive layer.

[0279] In some embodiments, the positive conductive layer comprises one or more positive conductive agents and positive binders.

[0280] Preferably, the mass fraction of the positive conductive material in the positive conductive layer is between 30% and 50%. For example, the mass fraction of the positive conductive material is 30%, 35%, 40%, 45%, 50%, or lies in any range between the two values ​​mentioned above.

[0281] For example, the positive conductive material in the positive conductive layer comprises one or more of the following elements, such as superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofiber. The positive conductive material in the positive conductive layer can improve the conductivity of the positive conductive layer, thereby increasing the conductivity of the positive electrode plate and reducing heat generation from the battery cell.

[0282] Preferably, the mass fraction of the positive binder in the positive conductive layer can be between 50% and 70%. For example, 50%, 60%, 65%, 70%, or any range between any two of the above values.

[0283] For example, the positive binder of the positive conductive layer comprises one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene, a terpolymer of vinylidene fluoride, tetrafluoroethylene, and propylene, a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, polyacrylic acid, and fluorinated acrylic ester resin. The positive binder of the positive conductive layer improves the adhesion between the positive current collector and the positive film layer and increases the structural stability of the positive electrode plate. [Negative electrode plate]

[0284] The negative electrode plate comprises a negative current collector and a negative film layer arranged on at least one surface of the negative current collector and comprising negative active material. For example, the negative current collector has two surfaces opposite in its thickness direction, with the negative film layer arranged on one or both of the two opposite surfaces of the negative current collector.

[0285] In some embodiments, the compaction density of the negative film layer in a battery cell at 100% charge is 1.2 g / cm³. 3 up to 1.4 g / cm³ 3 For example, the density of the negative film layer in a battery cell at 100% charge is 1.20 g / cm³. 3 , 1.22 g / cm³ 3 , 1.25 g / cm³ 3 , 1.28 g / cm³ 3 , 1.3 g / cm³ 3 , 1.32 g / cm³ 3 , 1.35 g / cm³ 3 , 1.40 g / cm³ 3or lies within any range of two of the values ​​mentioned above.

[0286] If the density of the negative film layer is within the range mentioned above, this contributes to increasing the energy density of the battery cell. Since the negative active material of the negative film layer is relatively densely packed, the contact resistance between the particles is low, which further reduces the resistance of the electrode plate, thus reducing heat generation, thereby decreasing the amount of gases caused by heat accumulation resulting from the decomposition of carboxylic acid ester solvents, and improving the cycle performance of the battery cell.

[0287] In the embodiment of the present application, the density of the negative film layer of the battery cell at 100% charge has the meaning generally known in this field and can be measured using the devices and methods generally known in this field, wherein the measuring method corresponds to the measuring method for the density of the positive film layer.

[0288] In some embodiments, the one-sided coating weight of the negative film layer is 100 mg / 1540.25 mm². 2 up to 200 mg / 1540.25 mm 2 For example, the one-sided coating weight of the negative film layer is 100 mg / 1540.25 mm². 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 lies within any range of two of the values ​​mentioned above.

[0289] If the one-sided coating weight of the negative film layer is within the above-mentioned range, the energy density of the battery cell can be increased; the heat generation per unit area of ​​the negative electrode plate is not too high, and at the same time the high-temperature cycle performance of the battery cell can be improved.

[0290] In the embodiment of the present application, the single-sided coating weight of the negative film layer has a meaning generally known in this field and can be measured using equipment and methods generally known in this field, i.e., disassembling the negative electrode plate of the battery cell and determining the compaction density of the negative film layer, e.g., by taking a negative electrode plate coated with a single-sided coating (in the case of an electrode plate coated with a double-sided coating, one of the negative film layers can be wiped off first), punching and cutting the negative electrode plate into small discs with an area of ​​S1, weighing them, noting them as M1, and measuring the thickness H1. Then, after weighing, wiping off the negative film layer of the negative electrode plate, weighing the negative current collector, noting it as M0, and measuring its thickness H0.The one-sided coating weight of the negative film layer = (weight of the negative electrode plate M1 - weight of the negative current collector M0) / S1.

[0291] The negative film layer in the embodiment of the present application comprises at least one film layer, wherein either a single film layer or at least two film layers may be used. The negative film layer may comprise two film layers, three film layers, four film layers, or even more film layers.

[0292] In the embodiment of the present application, the negative active material comprises a carbon-based material, wherein the carbon-based material includes graphite particles that exhibit high cycle stability and can improve the cycle performance of the battery cell. The positive active material in the present application is mainly a phosphate system, while the negative active material is mainly a carbon-based system. By combining both materials, the battery cell exhibits excellent cycle performance.

[0293] In some embodiments, the volume-averaged particle size Dv50 of the graphite particles is 9.5 µm to 16.5 µm, 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 lies within any range of two of the above values.

[0294] The volume-averaged particle size of the graphite particles is relatively small, which shortens the solid-phase migration path of the lithium ions and improves the fast-charging capability of the battery cell. However, under fast-charging conditions, violent side reactions occur between the small graphite particles and the carboxylic acid ester solvents in the electrolyte solution. Therefore, a first additive is added to the electrolyte solution. This additive primarily forms on the cathode side of the foil and provides excellent protection for the negative active material, thereby reducing the risk of side reactions on the cathode side and improving the cycle performance of the battery cell.

[0295] In the embodiment of the present application, the volume-averaged particle size Dv50 denotes the particle size corresponding to 50% of the volume distribution. It can be measured using equipment and methods known in this field, for example by using the positive active material as a sample and measuring the particle size Dv50 according to the test standard GB / T 19077-2016 with a Mastersizer 2000E laser particle size analyzer.

[0296] In some embodiments, the specific resistivity of the graphite particles is 0.005 Ω·cm to 0.04 Ω·cm. For example, the specific resistivity of the graphite powder 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 any range between two of the above values.

[0297] The specific resistance of the graphite powder is relatively low, which means that the resistance of the negative electrode plate is relatively low, the battery cell generates less heat, thereby reducing the amount of gases caused by heat accumulation resulting from the decomposition of carboxylic acid ester solvents and improving the cycle performance of the battery cell.

[0298] In the embodiment of the present application, the specific powder resistance of the negative active material has the meaning generally known in this field and can be measured using the equipment and methods generally known in this field, for example in accordance with the test standard GB / T30835-2014 using a PRCD1100 powder resistance measuring instrument.

[0299] In some embodiments, the graphite particles comprise graphite particles and a negative cover layer, wherein the graphite particles comprise secondary particles, the secondary particles comprise several primary particles, the negative cover layer covers the surface of the graphite particles, and the negative cover layer comprises carbon elements. The carbon in the negative cover layer consists mainly of amorphous carbon. Amorphous carbon refers to a carbon material in a transitional state with a very low degree of graphitization and crystallization, closely resembling an amorphous form (or a structure without a fixed shape and periodic structural regularity). In this application, amorphous carbon refers to the product after the carbonization of an organic carbon source.

[0300] The graphite particles comprise secondary particles. Within the graphite particles, there are numerous migration pathways for lithium ions, while the migration pathways in the primary particles are shorter, thus increasing the migration rate of the lithium ions. The negative cover layer exhibits many end faces and defects, increasing the number of sites where lithium ions can embed and eject. This results in improved conductivity of the negative cover layer, thereby reducing the internal resistance of the negative electrode plate, minimizing heat generation within the battery cell, and enhancing the fast-charging capability and high-temperature cycle performance of the battery cell at high energy density.

[0301] For example, the graphite particles comprise one or more of synthetic graphite and natural graphite, with synthetic graphite being preferentially used.

[0302] Preferably, the mass fraction of the carbon element in the negative cover layer, based on the mass of the graphite particles, is 2% to 5%. For example, the mass fraction of the carbon element in the negative cover layer is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or lies in any range between two of the values ​​mentioned above.

[0303] If the mass fraction of the carbon element in the negative cover layer is within the range mentioned above, the internal resistance of the negative electrode plate can be further reduced, the heat generation of the battery cell reduced, and the high-temperature cycle performance of the battery cell improved at high energy density.

[0304] In the embodiment of the present application, the graphite particles can be produced according to a method known in this field, using artificial graphite with graphite particles as an example. The production method comprises: providing artificial graphite and an organic carbon source, mixing both components, carbonizing, and forming a negative coating on at least a part of the surface of the artificial graphite particles.

[0305] Preferably, the organic carbon source comprises one or more types of coal tar, petroleum tar, phenolic resin, or coconut shells. More preferably, the organic carbon source may also comprise bitumen. Preferably, the softening point of coal bitumen and bitumen is below 250 °C.

[0306] Preferably, the carbonization temperature lies between 700 °C and 1800 °C. More preferably, the carbonization temperature lies between 1000 °C and 1300 °C. At a carbonation temperature within the suitable range, the organic carbon source can be carbonized and form a negative cover layer of amorphous carbon on at least a portion of the surface of the synthetic graphite.

[0307] The preferred carbonation time is 1 to 6 hours.

[0308] In some embodiments, the carbon-based material may also include natural graphite. In particular, the carbon-based material may comprise graphite particles, or the carbon-based material may comprise graphite particles and natural graphite. Preferably, the carbon-based material may consist of graphite particles.

[0309] In some embodiments, the negative active material can include silicon-based material in addition to graphite particles. The introduction of silicon-based material can increase the capacity of the negative active material and improve the energy density of the battery cell.

[0310] Preferably, the mass fraction of the silicon element in the silicon-based material, based on the mass of the negative film layer, can be 1% to 5% or optionally 1% to 6%. For example, the mass fraction of the 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 lies in any range between two of the values ​​mentioned above.

[0311] If the mass fraction of the silicon element in the silicon-based material is within the range mentioned above, the capacity of the negative active material can be increased and the energy density of the battery cell improved.

[0312] Preferably, the silicon-based material can be one or more of silicon monomers, silicon oxide and silicon-carbon complex, silicon-nitrogen complex and silicon alloy material.

[0313] In some embodiments, the negative active material may, in addition to the carbon-based material mentioned above and the optional silicon-based material, also comprise one or more tin-based materials and lithium titanate. The tin-based material may comprise at least one or more tin monomers, tin oxides, and tin alloy materials.

[0314] The qualitative and quantitative determination of the individual substances or elements in this application can be carried out using suitable equipment and procedures known to those skilled in the field. The relevant test methods may refer to domestic and foreign test standards, domestic and foreign company standards, etc., and those skilled in the field may also adjust certain test steps / equipment parameters, etc., for reasons of test accuracy in order to obtain more precise test results. The qualitative or quantitative determination may be carried out using a single test method or a combination of several test methods.

[0315] For example, the negative electrode plate can be immersed in a solvent such as water to separate the negative active material from the negative current collector. Filtration is then used to extract the individual substances in the negative film layer, which are used as test samples. These test samples are analyzed using an inductively coupled plasma emission spectrometer (ICAP7400) from the American company Thermo Fisher Scientific, in accordance with standard GB / T30902-2014, to determine the mass fraction of the silicon element.

[0316] For example, in this application, an X-ray powder diffraction test and qualitative analysis of the negative electrode plate or the negative active material can also be carried out in conjunction with the general method for X-ray diffraction analysis JIS / K0131-1996.

[0317] Artificial and natural graphite can be distinguished using SEM profile images acquired with a scanning electron microscope (SEM). The SEM profile of natural graphite shows gaps between the flake-like structures, while the SEM profile of artificial graphite is dense and shows no obvious gaps. A further distinction can be made using the XRD spectrum, obtained by X-ray diffraction. The XRD spectrum of natural graphite shows a distinct 2H and 3R phase, while the XRD spectrum of artificial graphite shows only the 2H phase.

[0318] In some embodiments, the negative film layer additionally comprises a negative binder comprising one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resins SR-1B, water-based acrylic resins (e.g., polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass fraction of the negative electrode binder is ≤ 5% based on the total weight of the negative film layer.

[0319] In some embodiments, the negative film layer may preferably also comprise a negative conductive element. The embodiment of the present application does not impose any particular restrictions regarding the type of negative conductive element. For example, the negative conductive element comprises at least one of the following elements, such as superconducting carbon, conductive graphite, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofiber. In some embodiments, the mass fraction of the negative conductive element is ≤ 5% based on the total weight of the negative film layer.

[0320] In some embodiments, the negative film layer may preferably also comprise other additives. These other additives may include, for example, thickening agents, dispersing agents, and the like, such as sodium carboxymethylcellulose (CMC-Na), PTC thermistor materials, and the like. In some embodiments, the mass fraction of the other additives is ≤ 2% based on the total weight of the negative film layer.

[0321] In some embodiments, the negative current collector can be a metal foil or a composite current collector. For example, a metal foil can be made of one or more foils of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. The composite current collector can comprise a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The metal material in the metal layer can, for example, include one or more of the following materials: copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy. The polymer base layer can, for example, include one or more of the following materials: polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE).

[0322] In some embodiments, the negative current collector has a thickness of 4 µm to 6 µm, e.g., 4 µm, 5 µm, 6 µm, or a range consisting of any two of the above values. When the thickness of the negative current collector is within the above range, it is advantageous to increase the overcurrent capability and improve the fast-charging capability of the battery cell.

[0323] The negative film layer is typically formed by applying the negative electrode slurry to the negative current collector, drying, and cold pressing. The negative electrode slurry is generally formed by dispersing the negative active material of the negative electrode, an optional conductive agent, an optional binder, and other optional additives in a solvent and mixing thoroughly. The solvent may include, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0324] The negative electrode plate does not preclude additional functional layers besides the negative film layer. In some embodiments, the negative electrode plate of the embodiment of the present application, for example, further comprises a negative conductive layer located between the negative current collector and the negative film layer and provided on the surface of the negative current collector. In further embodiments, the negative electrode plate of the embodiment of the present application additionally comprises a protective layer covering the surface of the negative film layer.

[0325] In some embodiments, the negative electrode plate also includes a negative conductive layer located between the negative film layer and the negative current collector. This negative conductive layer can further improve the conductivity of the negative electrode plate, reduce heat generation from the negative electrode plate, and thus reduce heat generation from the battery cell, thereby improving the fast-charging capability and high-temperature cycle performance of the battery cell.

[0326] In some embodiments, the thickness of the negative conductive layer is 0.5 µm to 2 µm. For example, the thickness of the negative 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 any range between two of the above values.

[0327] If the thickness of the negative conductive layer is within the range mentioned above, the conductivity of the negative electrode plate can be further improved, the heat generation of the negative electrode plate reduced, and thus the heat generation of the battery cell reduced, while at the same time the energy density of the battery cell can be increased.

[0328] In the embodiment of the present application, the thickness of the negative conductive layer has a meaning generally known in this field and can be measured using devices and methods generally known in this field, for example by a tomographic examination of the negative electrode plate to directly measure the thickness of the negative conductive layer.

[0329] In some embodiments, the negative conductive layer comprises one or more negative conductive agents and negative binders. 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 heat generation in the battery cell. The negative binder of the negative conductive layer can improve the adhesion between the negative current collector and the negative film layer and increase the structural stability of the negative electrode plate.

[0330] In some embodiments, the negative conductive layer may preferably also comprise other additives. These other additives may include, for example, thickening agents such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, and the like.

[0331] Preferably, the negative conductive element of the negative conductive layer can constitute a mass fraction of 20% to 40% of the negative conductive layer. For example, the mass fraction of the negative conductive element is 20%, 25%, 30%, 35%, 40%, or lies within any range of the two values ​​mentioned above.

[0332] For example, the negative conductive medium in the negative conductive layer comprises one or more of the following elements such as superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen black, carbon dots, carbon nanotube, graphene and carbon nanofiber.

[0333] Preferably, the negative binder of the negative conductive layer can constitute a mass fraction of 60% to 80% of the negative conductive layer. For example, 60%, 65%, 70%, 75%, 80%, or any range between the two values ​​mentioned above.

[0334] For example, the negative binder of the negative conductive layer comprises one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resins (SR-1B), water-based acrylic resins, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan. [Separating film]

[0335] In the embodiment of the present application, the separating film is arranged between the positive electrode plate and the negative electrode plate in order to separate the positive electrode plate and the negative electrode plate from each other.

[0336] In the embodiment of the present application, the separating film comprises a base film with a porous structure.

[0337] In some embodiments, the base film comprises one or more of the following materials, such as glass fiber, nonwoven fabric, or polyolefin. The base film can be a single-layer film or a multi-layer composite film, without any particular restrictions. If the base film is a multi-layer composite film, the materials of the individual layers can be the same or different, without any particular restrictions.

[0338] Preferably, the polyolefin comprises one or more of polyethylene, polypropylene and polyvinylidene fluoride.

[0339] In some embodiments, the porosity of the separating film is 20% to 70%, preferably 35% to 60%. For example, the porosity of the separating film can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any range between two of the values ​​mentioned above.

[0340] If the porosity of the separating film in the embodiment of the present application is within the aforementioned range, the migration capability of the lithium ions in the separating film can be improved, which can further reduce the internal resistance of the battery cell, which in turn reduces heat generation and improves the fast charging capability and the high-temperature cycle performance of the battery cell at high energy density.

[0341] Preferably the porosity of the base film is 20% to 70%, more preferably 35% to 60%.

[0342] In the embodiment of the present application, porosity refers to the percentage of the pore volume of the separator film relative to the total volume of the separator film. The porosity can be tested in accordance with standard GB / T 36363-2018 "Polyolefin separator film for battery cells". It should be noted that the actual test procedure may deviate slightly from the standard, depending on differences in test equipment, test errors, and in order to minimize the influence of these factors on the porosity tests as much as possible, in order to obtain more accurate test results.

[0343] In some embodiments, the thickness of the separating film is 4 µm to 12 µm. For example, the thickness of the separating film can be 4 µm, 5 µm, 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, 10.5 µm, 11 µm, 11.5 µm, 12 µm, or any range between two of the above values.

[0344] If the thickness of the separating film is within the range mentioned above, the migration path of the lithium ions in the separating film is shorter, which further reduces the internal resistance of the battery cell, which in turn reduces heat generation and improves the fast charging capability and high-temperature cycle performance of the battery cell at high energy density.

[0345] In the embodiment of the present application, the separating film can be a base film; preferably, the separating film can also comprise a functional layer arranged on at least one side of the base film, wherein the functional layer can comprise inorganic particles to improve the heat resistance of the separating film. Preferably, the functional layer can be arranged on both sides of the base film.

[0346] In some embodiments, the functional layer comprises a first functional layer and a second functional layer, wherein the first functional layer is located on one side of the base film, the first functional layer comprises first inorganic particles, the second functional layer is located on the other side of the base film, the second functional layer comprises composite particles, the composite particles comprise second inorganic particles and several non-fluorinated polymer particles, wherein the second inorganic particles adhere to the surface of the non-fluorinated polymer particles and / or are distributed within the non-fluorinated polymer particles.

[0347] The first functional layer and the second functional layer exhibit good heat resistance and can improve the heat resistance of the separating film.

[0348] Preferably, the first functional layer can comprise a binder, preferably one or more fluorine-containing binders or polyacrylic acid binders, for example polyvinylidene fluoride.

[0349] Preferably, the first inorganic particles may comprise one or more of silicon dioxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. The aforementioned first inorganic particles can improve the heat resistance of the first functional layer.

[0350] Preferably, the average particle size of the first inorganic particles can be between 5 nm and 100 nm, more preferably between 10 nm and 100 nm, and more preferably between 5 nm and 20 nm. For example, the average particle size of the second inorganic particles is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or lies within any range between the two values ​​mentioned above. Having the average particle size of the first inorganic particles within the range mentioned above improves the heat resistance and bulk modulus of the composite particles.

[0351] In the embodiment of the present application, the thickness of the film layer has a meaning generally known in this field and can be measured using methods and equipment generally known in this field. For example, a newly manufactured separating film can be taken as a sample, or a fully discharged battery cell (discharged to its lower limit voltage, so that the battery's state of charge is approximately 0% SOC) can be dissected from the back. The separating film is removed from the battery cell, dried, and used as a sample. The separating film is cut with an ion beam cutter to obtain a cross-section. Subsequently, the thickness of the separating film and its individual layers is measured using a scanning electron microscope.

[0352] The non-fluorinated polymer particles in the second functional layer are non-fluorinated polymers, for example, non-fluorinated polymer particles comprising acrylate copolymers, preferably acrylate-acrylonitrile-acrylamide-acrylic copolymers. Acrylate copolymers exhibit excellent adhesive properties and adhere very well to the base film. The molar ratio of the individual monomers in the copolymer can be chosen as desired, for example, 35%:30%:15%:20%, or 40%:20%:10%:30%, or 45%:15%:20%:20%, etc.

[0353] The second set of inorganic particles in the composite particles prevents the non-fluorinated polymer particles from sticking together due to the high temperatures during the granulation process. This porosity of the composite particles promotes lithium ion transport and improves the ionic conductivity of the separator film. Furthermore, these second set of inorganic particles increase the bulk modulus of the composite particles, making them less prone to deformation during charging and discharging. This results in a more stable separator film structure and improves the kinetic properties of the battery cell as well as its fast-charging capability. Preferably, the second functional layer can be positioned closer to the negative electrode plate compared to the first functional layer.Since the composite particles are not easily deformable, the separating film causes essentially no side effects such as pressure on the negative electrode plate, thus maintaining the stability of the negative electrode plate's kinetic properties. Accordingly, the first functional layer is positioned close to the positive electrode plate.

[0354] Preferably, the second inorganic particles comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide; more preferably, the second inorganic particles comprise silicon oxide. The aforementioned second inorganic particles can improve the heat resistance of the second functional layer and can be combined with non-fluorinated polymers to form composite particles, further enhancing the cycle stability and kinetic properties of the separator film and improving the cycle performance and fast-charging capability of the battery cell.

[0355] Preferably, the average particle size of the second inorganic particles can be between 5 nm and 100 nm, more preferably between 10 nm and 100 nm, and more preferably between 5 nm and 20 nm. For example, the average particle size of the second inorganic particles is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or lies within any range between the two values ​​mentioned above. Having the average particle size of the second inorganic particles within the range mentioned above improves the heat resistance and bulk modulus of the composite particles.

[0356] In the embodiment of the present application, the average particle size of the second inorganic particles has a meaning generally known in this field and can be measured using equipment and methods generally known in this field, for example, by drying the separating film after obtaining it and using it as a sample, cutting the separating film with an ion beam cutter to form a cross-section, and then measuring the particle size of the second inorganic particles in the separating film with a scanning electron microscope, whereby the particle size of several, for example 50, second inorganic particles is measured and their average value is calculated as the average particle size of the second inorganic particles. Example of implementation

[0357] The following embodiments describe in more detail what is disclosed by the embodiments of the present application, and these embodiments serve only for illustration, since various modifications and variations within the scope of disclosure of the embodiments of the present application are obvious to the person skilled in the art. Unless otherwise stated, all parts, percentages, and ratios given in the following embodiments are based on mass counts, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the equipment used in the embodiments is commercially available. Example 11. Production of a positive electrode plate

[0358] The positive electrode comprises a positive current collector, positive film layers, and a positive conductive layer, wherein the positive film layers are arranged on both sides of the positive current collector and the positive conductive layer lies between the positive current collector and the positive film layer. The positive current collector is made of aluminum foil.

[0359] The positive conductive layer on the positive current collector consists of a positive conductive material made of superconducting carbon and a positive binder made of polyvinylidene fluoride (PVDF), along with the solvent N-methylpyrrolidone (NMP). These materials are mixed uniformly, applied to the surface of the positive current collector, and dried to form a layer 1 µm thick. The mass fraction of the positive conductive material in the positive conductive layer is 40%, and the mass fraction of the positive binder is 60%.

[0360] The positive film layer consists of a positive electrode slurry (solvent: N-methylpyrrolidone, NMP) which is uniformly applied to the surface of the positive conductive layer and, after drying and cold pressing, formed into a film layer. The positive film layer consists of a weight ratio of 97:2:1 of positive active material, binder polyvinylidene fluoride (PVDF), and conductive carbon black.

[0361] The positive active material comprises lithium iron phosphate particles and a positive cover layer that coats the surface of the lithium iron phosphate particles. The positive cover layer comprises lithium iron titanate (Li₂FeTi(PO₄)₃) and carbon, with the carbon element comprising 1.12% by mass.

[0362] The one-sided coating weight of the positive film layer is 263 mg / 1540.25 mm². 2 . 2. Production of the negative electrode plate

[0363] The negative electrode plate comprises a negative current collector, negative film layers and a negative conductive layer, wherein the negative film layers are arranged on both sides of the negative current collector, the negative conductive layer is located between the negative current collector and the negative film layer, and the negative current collector is made of copper foil.

[0364] The negative conductive layer on the negative current collector consists of a negative conductive material made of superconducting carbon, a negative binder made of styrene-butadiene rubber (SBR), a thickener made of sodium carboxymethylcellulose (CMC-Na), and a solvent made of water, which are uniformly mixed and applied to the surface of the negative current collector to form a 1 µm thick film. The mass fraction of the negative conductive material in the negative conductive layer is 35%. The mass fraction of the negative binder in the negative conductive layer is 60%, and the mass fraction of the thickener in the negative conductive layer is 5%.

[0365] The negative film layer comprises a film layer formed by uniformly applying the negative electrode slurry (the solvent is deionized water) to the surface of the negative current collector, drying, and cold pressing.

[0366] The negative film layer consists of a negative active material with a mass ratio of 96.5:0.5:2:1, the conductive agent acetylene carbon black, the negative binder styrene-butadiene rubber, and the thickening agent sodium carboxymethylcellulose. The graphite particles consist of synthetic graphite and a negative top layer covering the surface of the synthetic graphite. The mass fraction of the carbon element in the negative top layer is 3.5%. The Dv50 of the graphite particles is 11.3 µm.

[0367] The one-sided coating weight of the negative film layer is 120 mg / 1540.25 mm². 2 .

[0368] The length of the negative film layer is 3 mm greater than the length of the positive film layer, and the width of the negative film layer is 3 mm greater than the length of the positive film layer. 3. Separating film

[0369] The release film comprises a base film and functional layers arranged on both sides of the base film. The base film consists of 7 µm polyethylene with a porosity of 42%;

[0370] The functional layer consists of a first and a second functional layer. The first functional layer is a 1 µm thick layer of aluminum oxide particles and the binder polyvinylidene fluoride, applied to one side of the base film, and the average particle size of the aluminum oxide particles is 10 nm;

[0371] The second functional layer consists of a composite particle formed from polyacrylate and silicon oxide particles dispersed on polyacrylate, and is applied to the other side of the base film to form a 1 µm thick layer, with the average particle size of the silicon oxide particles being 10 nm. 4. Preparation of the electrolyte solution

[0372] The electrolyte solution consists of organic solvents, lithium salts and additives.

[0373] After mixing the components of the individual organic solvents, lithium salts and additives are added to produce the electrolyte solution.

[0374] The organic solvents comprise 39% by mass of chain carboxylic acid ester solvents (ethyl acetate), 27.3% by mass of vinyl carbonate EC, and 11.7% by mass of dimethyl carbonate. The mass fraction of each component in the organic solvents is calculated based on the mass of the electrolyte solution.

[0375] The additive has a mass fraction of 7% and comprises vinylidene carbonate VC, vinyl fluorocarbonate FEC, vinyl sulfite ES and lithium borate difluorooxalate LiDFOB in a mass ratio of 3.5:2.5:0.5:0.5.

[0376] The lithium salt comprises lithium bifluorosulfonamide (LiFSI) at a mass fraction of 5% and lithium hexafluorophosphate (LiPF6) at a mass fraction of 10%. The mass fraction of the lithium salt is calculated based on the mass of the electrolyte solution. 5. Manufacturing the battery cell

[0377] The positive electrode plate, separating film, and negative electrode plate mentioned above are stacked on top of each other in this order, so that the separating film lies between the positive and negative electrode plates, thus providing separation. This creates a stacked electrode assembly, which is then inserted into a housing. The housing is equipped with a positive and a negative terminal. After vacuum packaging, decommissioning, forming, and shaping, the battery cell is produced.

[0378] The housing consists of a rectangular aluminum case, the largest surface of which (i.e. the large side of the case) has a thickness of 0.5 mm.

[0379] The energy density of the battery cell is 423 Wh / L.

[0380] The density of the positive film layer of the battery cell is 2.67 g / cm³ at 100% SOC. 3 The compaction density of the negative film layer at 100% SOC is 1.33 g / cm³. 3. 6. Manufacturing the battery device

[0381] Several battery cells are arranged sequentially along their thickness direction (parallel to the first direction), thermal insulation elements are placed between two adjacent battery cells, and thermal insulation elements are placed on both sides of the battery cell along the first direction (as in Fig. (shown in 10). The components mentioned above are mounted in a box and assembled into a battery device.

[0382] The battery cell is arranged vertically, with the dimension along the second direction being understood as the height of the battery cell and the dimension along the third direction as the width of the battery cell.

[0383] Accordingly, the dimension of the thermal insulation element in the second direction can be understood as the height of the thermal insulation element and the dimension in the third direction as the width of the thermal insulation element.

[0384] The thermal insulation element has a thickness of 0.8 mm, a height L2 of 106 mm, a width H2 of 304 mm and a cross-sectional area S2 of 32224 mm². 2 perpendicular to its own thickness direction.

[0385] The height L1 of the battery cell is 112 mm, the width H1 is 312 mm and the cross-sectional area perpendicular to its own thickness direction is 34944 mm². 2 .

[0386] L2 / L1 is 0.95, L1-L2 is 6 mm, H2 / H1 is 0.97, H2-H1 is 8 mm and S2 / S1 is 0.92. Comparative example 1

[0387] The battery device is manufactured according to a similar method as in embodiment 1, the difference being that no thermal insulation element is provided in the battery device. Performance test 1. Thermal instability test of the battery unit

[0388] As in Fig. 15 and Fig. 16 shown, Step 1: Take five battery cells with identical specifications as a test sample. Charge the battery cells with a constant current of 0.33C until the final charging voltage of 3.6V is reached, and then with a constant current of 0.1C until the final charging voltage of 3.65V is reached. Set the state of charge (SOC) of the battery cells to 100%. Step 2: The five battery cells are arranged along their thickness direction and connected in series, with the battery cells being largely aligned in the longitudinal, thickness, and width directions, as shown in Fig.As shown in Figure 15, the thermal insulation elements 40 are attached, and then the five adjacent battery cells are pressed together with a clamping force of 3000 N using the clamping device 60 and assembled into a 1P5S module; The height of the clamp 60, the height of the thermal insulation element 40 and the height of the battery cells are identical; Step 3: The battery cell in the middle of the five battery cells is designated as trigger battery 72, the remaining battery cells are defined as first test battery 71. The trigger battery 72 in the middle is triggered with a needle.

[0389] As in Fig. As shown in Figure 16, the release position C is marked. Position C is located at the geometric center of the bottom wall of the release battery 72, with the bottom wall and the end cover arranged opposite each other along the longitudinal direction of the release battery 72;

[0390] The 1P5S module is placed in a closed box (the closed box leaves only position C of the trigger battery 72 free).

[0391] Step 4: Use an 8 mm long flat-headed needle to activate position C (the needle tip should be perpendicular to the longitudinal direction of the battery cell) and activate the aforementioned trigger battery 72 at a rate of 1 mm / s until it goes out of control. After testing, observe for 2 hours, then disassemble the box and observe whether the first test battery 71 exhibits an opening of the explosion protection valve and thermal instability of the pressure relief components. Measure the weight of the first test battery 71 to assess the thermal instability of the battery cell. 2. Number of battery cell cycles up to 70% SOH

[0392] At 60 °C, the battery cell is charged with a constant current of 0.8 C to a final charging voltage of 3.6 V, then charged with a constant current of 0.1 C to a final charging voltage of 3.65 V and left to rest for 30 minutes; discharged with a constant current of 1 C to 2.83 V and left to rest for 30 minutes. This is one charge and discharge cycle. The above steps are repeated until the cycle capacity retention (i.e., Cn / C0 × 100%) reaches 70%, and the number of cycles is recorded. The higher the number of cycles, the better the cycle performance of the battery cell.

[0393] During the above-mentioned charging and discharging tests of the battery cell, these can be integrated into a battery system to control the required charging and discharging strategies via the battery management system.

[0394] The test results are listed in Table 1. Table 1 Battery performance Thermal instability testing Number of cycles Example 1 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2153 Comparative example 1 The explosion protection valve of the adjacent battery cell is open, and thermal instability occurs. 2139

[0395] Adjacent battery cell is a battery cell located next to the trigger battery.

[0396] Comparative example 1: Under normal cycle operation, the cycle performance is relatively good; however, since no thermal insulation element is provided, in the event of thermal instability of the trigger battery, the heat spreads quickly to neighboring battery cells and triggers thermal instability in other battery cells, thereby impairing the reliability of the battery cells.

[0397] In comparison to example 1, embodiment 1 exhibits excellent cycle performance due to the inclusion of a thermal insulation element in the battery device; furthermore, the thermal insulation element can effectively reduce heat propagation, lower the risk of thermal instability, and improve the reliability of the battery cells. Exemplary embodiments 2-1 to 2-6

[0398] The battery cell is manufactured according to a similar process as in embodiment 1, however, in contrast to embodiment 1, the mass fractions of fluorosulfonylimide salt and lithium hexafluorophosphate as well as the thickness of the thermal insulation element are adjusted. Example 2-7

[0399] The battery cell is manufactured using a similar process to that in embodiment 1, however, in contrast to embodiment 1, the type of fluorosulfonylimide salt is adapted. Comparative example 2-1 and 2-2

[0400] The battery cell is manufactured using a similar process to that in embodiment 1, however, in contrast to embodiment 1, the mass fractions of lithium fluorosulfonylimide and lithium hexafluorophosphate as well as the thickness of the thermal insulation element are adjusted.

[0401] The test results are listed in Table 2. Table 2 electrolyte solution Thermal insulation element thickness / mm Battery performance Fluorosulfonylimide salt Lithium hexafluorophosphate Thermal instability testing Number of cycles material Mass fraction % Mass fraction % Example 2-1 LiFSI 2 13 0,3 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 1901 Example 2-2 LiFSI 6 9 1 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2212 Example 2-3 LiFSI 7 8 1,2 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2268 Example 2-4 LiFSI 8 7 1,5 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2293 Example 2-5 LiFSI 12 3 2,5 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2358 Example 2-6 LiTFSI 5 10 0,8 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2190 Comparative example 2-1 LiFSI 1 14 / The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 1712 Comparative example 2-2 LiFSI 15 0 2,5 After the battery's thermal instability was triggered, a fire and an explosion occurred; the neighboring battery cells became thermally unstable. 2423

[0402] Comparative example 2-1: By incorporating thermal insulation elements into the battery device, heat transfer between other battery cells can be effectively prevented and the risk of thermal instability reduced; however, the mass fraction of lithium bifluorosulfonamide is relatively low, so although the amount of lithium hexafluorophosphate in the electrolyte solution can be reduced, the hydrofluoric acid content in the electrolyte solution remains relatively high, leading to damage to the SEI film by hydrofluoric acid and a deterioration in the cycle performance of the battery cell.

[0403] The electrolyte solution according to Comparative Example 2-2 contains a large amount of lithium bifluorosulfonamide, which can effectively improve the cycle life of the battery device. Although a thermal insulation element is provided in the battery device according to Comparative Example 2-2, the thermal stability of the electrolyte solution is poor due to the excessively high mass fraction of lithium bifluorosulfonamide, so that in the event of thermal instability, a large amount of heat is released, which in turn can trigger thermal instability in neighboring battery cells.

[0404] In this embodiment of the present application, the thickness of the lithium bifluorosulfonamide and the thermal insulation element is increased by simultaneously regulating their thicknesses. At high mass fractions of lithium fluorosulfonylimide, the thickness of the thermal insulation element is increased to reduce the risk of thermal instability. For example, in embodiment 2-1, the mass fraction of lithium fluorosulfonylimide is relatively low, so that, in combination with a thinner thermal insulation element, relatively little heat is released from the battery cell during thermal instability, and the thinner thermal insulation element can effectively prevent heat propagation. With increasing mass fraction of lithium fluorosulfonylimide, acid production in the electrolyte solution decreases, thereby significantly improving circulation performance; however, during thermal instability, instantaneous heat dissipation increases, thus simultaneously increasing the thickness of the thermal insulation element.By increasing the thickness of the thermal insulation element, for example in embodiments 2-2 to 2-6, the risk of heat propagation to neighboring battery cells is reduced and the reliability of the battery device is increased.

[0405] Various fluorosulfonylimide salts are suitable for this application, for example lithium bifluorosulfonamide in embodiment 1 and lithium trifluorosulfonimide in embodiments 2 to 6, all of which can effectively improve the reliability and cycle performance of the battery device. Exemplary embodiment 3-1 and Exemplary embodiment 3-2

[0406] The battery device is manufactured using a similar method to that in embodiment 1, the difference being that the compaction density of the positive and negative film layers and the thickness of the thermal insulation element are adjusted. Exemplary embodiment 3-3 and Exemplary embodiment 3-4

[0407] The battery device is manufactured using a similar method to that in embodiment 1, the difference being that the coating weight and the compaction density of the positive and negative film layers, as well as the thickness of the thermal insulation element, are adjusted.

[0408] In embodiment 3-3, the negative film layer comprises 6% silicon carbide, while at the same time the mass fraction of the graphite particles is reduced, so that the mass fraction of the negative active material in the negative film layer remained essentially unchanged;

[0409] In embodiment 3-4, the negative film layer comprises 10% silicon carbide, while at the same time the mass fraction of the graphite particles is reduced, so that the mass fraction of the negative active material in the negative film layer remained essentially unchanged.

[0410] The test results are listed in Table 3. Table 3 Thermal insulation element thickness / mm Positive electrode plate Negative electrode plate Battery performance Coating weight mg / 1540.25 mm 2 Compaction density / cm 3 Coating weight mg / 1540.25 mm 2 Compaction density / cm 3 Volume energy density Wh / L Thermal instability testing Number of cycles Example 3-1 0,5 263 2,65 120 1,30 400 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2221 Example 3-2 1 263 2,72 120 1,38 440 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2143 Example 3-3 1,5 353 2,80 130 1,35 490 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 1857 Example 3-4 2,5 430 2,80 140 1,38 530 The explosion protection valve of the adjacent battery cell is open, but no thermal instability occurs. 1560

[0411] In Table 3, the volume energy density of the battery cell is reduced or increased in embodiments 3-1 and 3-2 by the compression density of the positive and negative film layers. A lower volume energy density of the battery cell allows for the use of a relatively thin thermal insulation element, thereby improving both the reliability and the cycle performance of the battery cell.

[0412] In embodiments 3-3 and 3-4, the energy density of the battery cell can be effectively increased by adapting the silicon element in the negative film layer in conjunction with the compaction density and the coating weight of the positive and negative film layers, while simultaneously increasing the thickness of the thermal insulation element, thereby improving both the reliability and the cycle performance of the battery cell. Exemplary embodiment 4-1 and Exemplary embodiment 4-2

[0413] The battery device is manufactured according to a similar method as in embodiment 1, the difference being that the height of the thermal insulation element is adjusted. Exemplary embodiment 4-3 and Exemplary embodiment 4-4

[0414] The battery device is manufactured using a similar method to that in embodiment 1, the difference being that the width of the thermal insulation element is adjusted.

[0415] The test results are listed in Table 4. Table 4 Thermal insulation element L2 / L1 L1-L2 / mm H2 / H1 H2-H1 / mm S2 / S1 Battery performance HeightL2 / mm Width H2 / mm Area S2 / mm 2 Thermal instability testing Number of cycles Example 4-1 110 304 33440 0,98 2 0,97 8 0,96 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2173 Example 4-2 102 304 31008 0,91 10 0,97 8 0,89 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2147 Example 4-3 106 302 32012 0,95 6 0,97 10 0,92 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2154 Example 4-4 106 311 32966 0,95 6 1,00 1 0,94 The explosion protection valve of the adjacent battery cell is not open; no thermal instability occurs. 2149

[0416] The larger the area of ​​the battery cell covered by the thermal insulation element, the better the ability to reduce heat dissipation, the lower the risk of thermal instability in neighboring battery cells, and the higher the reliability of the battery cells; the difference in the cycle performance of the battery cell is small. For example, compared to embodiment 4-2, the height of the thermal insulation element in embodiment 4-1 is greater, the thermal insulation element covers a larger area of ​​the battery cell, and the reliability of the battery cell is higher.

[0417] In contrast to embodiment 4-3, the thermal insulation element in embodiment 4-4 is wider and covers a larger area of ​​the battery cell, thereby increasing the reliability of the battery cell.

[0418] Although illustrative embodiments have been shown and described, it should be clear to those skilled in the art that the above-mentioned embodiments are not to be understood as limiting this application and that the embodiments can be changed, replaced and modified without departing from the spirit, principles and scope of this application. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] GB 9722-2006

[0244] GB 19077-2016

[0295] GB 30835-2014

[0298] GB 36363-2018

[0342]

Claims

[1] Battery device comprising a thermal insulation element and at least two battery cells arranged along a first direction, the battery cell comprising an electrode assembly and electrolyte solution, the electrode assembly comprising positive electrode plates and negative electrode plates, the positive electrode plate comprising positive current collectors and positive film layers arranged on at least one side of the positive current collectors, the positive film layer comprising lithium phosphate, the negative electrode plate comprising negative current collectors and negative film layers arranged on at least one side of the negative current collector, the negative film layer comprising graphite particles, characterized by , that the electrolyte solution comprises fluorosulfonylimide salt, wherein the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 12%; wherein the battery cell comprises two first surfaces which are opposite each other along the first direction, wherein the thermal insulation element covers at least one of the two first surfaces and the dimension of the thermal insulation element along the first direction is 0.3 mm to 5 mm. [2] Battery device according to claim 1, characterized by , that the dimension of the thermal insulation element along the first direction is 0.5 mm to 2.5 mm. [3] Battery device according to claim 1 or 2, characterized by , that the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 2% to 6%; wherein the thermal insulation element has a dimension greater than or equal to 0.5 mm and less than or equal to 1.0 mm along the first direction. [4] Battery device according to claim 1 or 2, characterized by, that the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is greater than 6% and less than or equal to 8%; wherein the thermal insulation element has a dimension greater than 1.0 mm and less than or equal to 1.5 mm along the first direction. [5] Battery device according to claim 1 or 2, characterized by , that the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is greater than 8% and less than or equal to 12%; wherein the thermal insulation element has a dimension greater than 1.5 mm and less than or equal to 2.5 mm along the first direction. [6] Battery device according to any one of claims 1 to 5, characterized by that the volume energy density of the battery cell is between 400 Wh / L and 530 Wh / L. [7] Battery device according to any one of claims 1 to 6, characterized by, that the volume energy density of the battery cell is 400 Wh / L to 440 Wh / L; wherein the thermal insulation element has a dimension greater than or equal to 0.5 mm and less than or equal to 1.0 mm along the first direction. [8] Battery device according to any one of claims 1 to 6, characterized by , that the volume energy density of the battery cell is greater than 440 Wh / L and less than or equal to 490 Wh / L; wherein the thermal insulation element has a dimension greater than 1.0 mm and less than or equal to 1.5 mm along the first direction. [9] Battery device according to any one of claims 1 to 6, characterized by , that the volume energy density of the battery cell is greater than 490 Wh / L and less than or equal to 530 Wh / L; wherein the thermal insulation element has a dimension greater than 1.5 mm and less than or equal to 2.5 mm along the first direction. [10] Battery device according to any one of claims 1 to 9, characterized bythat the battery device meets the following condition: 0.9 ≤ S2 / S1 ≤ 1, where S1 is the area of ​​the first surface in mm 2 designated; where S2 is the area of ​​the projection surface of the thermal insulation element perpendicular to the first direction in mm. 2 designated. [11] Battery device according to any one of claims 1 to 10, characterized by , that the battery cell comprises an electrode terminal, wherein the electrode terminal is connected to at least one side of the electrode assembly along the second direction, the second direction being perpendicular to the first direction; where the battery device meets the following condition: 0.8 ≤ L2 / L1 ≤ 1, where L1 denotes the dimension of the first surface along the second direction in mm; where L2 denotes the dimension of the thermal insulation element along the second direction in mm. [12] Battery device according to claim 11, characterized by , that the battery device also meets the following condition: 2 mm ≤ L1-L2 ≤ 10 mm. [13] Battery device according to any one of claims 1 to 12, characterized by , that the battery cell comprises an electrode terminal, wherein the electrode terminal is connected to at least one side of the electrode assembly along the second direction; where the battery device meets the following condition: 0.9 ≤ H2 / H1 ≤ 1, where H1 denotes the dimension of the first surface along the third direction in mm, where the third direction and the second direction are each perpendicular to the first direction; where H2 denotes the dimension of the thermal insulation element along the third direction in mm. [14] Battery device according to claim 13, characterized by , that the battery device also meets the following condition: 1 mm ≤ H1-H2 ≤ 10 mm. [15] Battery device according to any one of claims 1 to 14, characterized by that the battery cell also comprises two second surfaces that are opposite each other along a third direction and that the two second surfaces are connected to each other via the first surface, the third direction being perpendicular to the first direction and the area of ​​the first surface being larger than the area of ​​the second surface. [16] Battery device according to any one of claims 1 to 15, characterized by that the thermal insulation element covers the first two surfaces of the battery cell. [17] Battery device according to any one of claims 1 to 16, characterized by that the thermal insulation element is bonded to the first surface. [18] Battery device according to any one of claims 1 to 17, characterized bythat the thermal insulation element comprises a thermal insulation body and a support element, wherein the support element is arranged in a ring shape around the thermal insulation body and both the thermal insulation body and the support element cover the surface of the battery cell along the first direction. [19] Battery device according to claim 18, characterized by , that the support element is an annular element, wherein the support element satisfies the following condition: 10 mm ≤ W1-W2 ≤ 60 mm, where W1 denotes the dimension of the outer outline of the annular element along the second direction, wherein the battery cell comprises an electrode terminal, the electrode terminal being connected to at least one side of the electrode assembly along the second direction, wherein the second direction is perpendicular to the first direction; where W2 denotes the dimension of the inner outline of the annular element along the second direction; and / or where the support element satisfies the following condition: 10 mm ≤ W3-W4 ≤ 60 mm, where W3 denotes the dimension of the outer outline of the ring-shaped element along the third direction, wherein the battery cell comprises an electrode terminal, the electrode terminal being connected to at least one side of the electrode assembly along the second direction, wherein the third direction, the second direction and the first direction are each perpendicular to each other; where W4 denotes the dimension of the inner outline of the ring-shaped element along the third direction. [20] Battery device according to claim 18 or 19, characterized by that the thermal insulation body comprises a thermal insulation material, wherein the thermal insulation material comprises one or more of aerogel, foam, polyurethane, silicone rubber; and / or wherein the supporting element comprises one or more of polysaccharide, polyethylene terephthalate, polyurethane, polyacrylonitrile, polypropylene, polyamide and aromatic polyamide. [21] Battery device according to any one of claims 1 to 20, characterized by , that the fluorosulfonylimide salt comprises one or more of difluorosulfonylimide salt, difluoromethanesulfonylimide salt, perfluorobutylsulfonylimide salt. [22] Battery device according to any one of claims 1 to 21, characterized by that the mass fraction of the fluorosulfonylimide salt in the electrolyte solution is 4% to 8%. [23] Battery device according to any one of claims 1 to 22, characterized by , that the electrolyte solution also includes hexafluorophosphate, with the mass fraction of hexafluorophosphate in the electrolyte solution being 3% to 13%. [24] Battery device according to any one of claims 1 to 23, characterized by, that the electrolyte solution also comprises a carboxylic acid ester solvent, wherein the carboxylic acid ester solvent comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate. [25] Battery device according to claim 24, characterized by that the mass fraction of the carboxylic acid ester solvent in the electrolyte solution is 8% to 60%. [26] Battery device according to any one of claims 1 to 25, characterized by that the electrolyte solution also comprises a carbonate solvent, wherein the carbonate solvent comprises one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and methylethyl carbonate. [27] Battery device according to claim 26, characterized by that the mass fraction of the carbonate solvent in the electrolyte solution is 18% to 70%. [28] Battery device according to any one of claims 1 to 27, characterized by , that the electrolyte solution also comprises additive; wherein the additive comprises carbonate ester additive, wherein the carbonate ester additive comprises one or more derivatives of vinylidene carbonate and vinyl carbonate, wherein the vinyl carbonate derivatives comprise the compounds shown in formula A, wherein in formula A Q1, Q2, Q3 and Q4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group or a C1 to C5 haloalkyl group, and Q1, Q2, Q3 and Q4 are not simultaneously hydrogen atoms; and / or wherein the additive comprises a sulfur-containing additive, wherein the sulfur-containing additive comprises one or more of ethylene sulfate, vinyl bisulfate, 1,3-propanesulfonic acid lactone, butyl sulfite, vinyl sulfite, methylene disulfonate; and / or wherein the additive comprises lithium salt additive, wherein the lithium salt additive comprises one or more of lithium difluorophosphate, lithium borate difluorooxalate, lithium tetrafluoroborate and lithium borate bis(oxalate). [29] Battery device according to claim 28, characterized by that the mass fraction of the carbonate ester additive in the electrolyte solution is 2.5% to 10.0%; and / or wherein the mass fraction of the sulfur-containing additive in the electrolyte solution is 0% to 2%; and / or where the mass fraction of the lithium salt additive in the electrolyte solution is 0% to 1%. [30] Battery device according to any one of claims 1 to 29, characterized by , that the one-sided coating weight of the positive film layer is 220 mg / 1540.25 mm 2 up to 450 mg / 1540.25 mm 2 is; and / or wherein the one-sided coating weight of the negative film layer is between 100 mg / 1540.25 mm 2 and 200 mg / 1540.25 mm 2lay. [31] Battery device according to any one of claims 1 to 30, characterized by , that The density of the positive film layer at a 100% charge of the battery cell is between 2.6 g / cm². 3 and 2.8 g / cm² 3 is; and / or where the density of the negative film layer at a 100% charge of the battery cell is between 1.2 g / cm² 3 and 1.4 g / cm³ 3 amounts. [32] Battery device according to any one of claims 1 to 31, characterized by , that the lithium phosphate comprises phosphate particles, and a positive cover layer, wherein the positive cover layer is located on at least a part of the phosphate particle surface and the positive cover layer comprises a carbon element. [33] Battery device according to claim 32, characterized by , that the mass fraction of the carbon element, based on the mass of the lithium phosphate, is 0.8% to 2.3%. [34] Battery device according to claim 32 or 33, characterized by that the positive top layer also includes one or more of the elements Fe, Ti, Zr, Hf, Ge and Sn. [35] Battery device according to any one of claims 32 to 34, characterized by that the phosphate particles comprise one or more of lithium iron phosphate, lithium unangan phosphate, lithium manganese iron phosphate, lithium nickel phosphate and lithium cobalt phosphate. [36] Battery device according to any one of claims 1 to 35, characterized by that lithium phosphate is a material with the general formula Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 includes where 0.5 _< x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.5 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5. where A comprises one or more of the elements Na, K and Mg, Me comprises one or more of the elements Mn, Fe, Co and Ni, M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Hf, Ge and Ce, X comprises one or more of the elements Cl, C, N, Y comprises one or more of the elements O and F. [37] Battery device according to any one of claims 1 to 36, characterized by , that the thickness of the positive current collector is 10 µm to 15 µm. [38] Battery device according to any one of claims 1 to 37, characterized by , that the positive electrode plate also includes a positive conductive layer, wherein the positive conductive layer is located between the positive current collector and the positive film layer, wherein the positive conductive layer comprises a positive conductive medium, wherein the positive conductive medium comprises one or more of the following elements such as superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen black, carbon dots, carbon nanotube, graphene and carbon nanofiber; and / or wherein the positive conductive layer comprises a positive binder, wherein the positive binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, terpolymer of vinylidene fluoride, tetrafluoroethylene and propylene, terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, copolymer of tetrafluoroethylene and hexafluoropropylene, polyacrylic acid and fluorinated acrylic ester resin. [39] Battery device according to claim 38, characterized by , that the thickness of the positive conductive layer is 0.5 µm to 2 µm. [40] Battery device according to any one of claims 1 to 39, characterized by, that the graphite particles comprise graphite particles and a negative cover layer applied to the surface of the graphite particles, wherein the graphite particles comprise secondary particles and the negative cover layer comprises carbon elements. [41] Battery device according to claim 40, characterized by that the graphite particles comprise one or more of artificial graphite and natural graphite. [42] Battery device according to claim 40 or 41, characterized by , that the mass fraction of the carbon element in the negative cover layer, based on the mass of the graphite particles, is 2% to 5%. [43] Battery device according to any one of claims 1 to 42, characterized by , that the specific powder resistance of the graphite particles is 0.005 Ω·cm to 0.04 Ω·cm; and / or wherein the volume-averaged particle size Dv50 of the graphite particles is 9.5 µm to 16.5 µm. [44] Battery device according to any one of claims 1 to 43, characterized by, that the negative film layer also comprises a silicon-based material, wherein the mass fraction of the silicon element of the silicon-based material in the negative film layer is 1% to 5%. [45] Battery device according to claim 44, characterized by that the silicon-based material comprises one or more silicon monomers, silicon-carbon material, silicon-oxygen material, silicon-nitrogen material. [46] Battery device according to any one of claims 1 to 45, characterized by , that the thickness of the negative current collector is 4 µm to 6 µm. [47] Battery device according to any one of claims 1 to 46, characterized by , that the negative electrode plate also includes a negative conductive layer, wherein the negative conductive layer is located between the negative current collector and the negative film layer, wherein the negative conductive layer comprises a negative conductive medium, wherein the negative conductive medium comprises one or more of the following elements such as superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen black, carbon dots, carbon nanotube, graphene and carbon nanofiber; and / or wherein the negative conductive layer comprises a negative binder, wherein the negative binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, terpolymer of vinylidene fluoride, tetrafluoroethylene and propylene, terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, copolymer of tetrafluoroethylene and hexafluoropropylene, polyacrylic acid and fluorinated acrylic ester resin. [48] ​​Battery device according to claim 47, characterized by , that the thickness of the negative conductive layer is 0.5 µm to 2 µm. [49] Battery device according to any one of claims 1 to 48, characterized by, that the electrode assembly also includes a separating film, wherein the separating film is located between the positive electrode plate and the negative electrode plate, where the thickness of the separating film is 4 µm to 12 E and is; and / or where the porosity of the separating film is between 20% and 70%. [50] Battery device according to claim 49, characterized by that the separating film comprises a base film and a functional layer arranged on the base film, wherein the functional layer a first functional layer located on one side of the base film, wherein the first functional layer comprises first inorganic particles, and a second functional layer located on the other side of the base film, wherein the second functional layer comprises composite particles, the composite particles comprise second inorganic particles and several non-fluorinated polymer particles, wherein the second inorganic particles adhere to the surface of the non-fluorinated polymer particles and / or are distributed within the non-fluorinated polymer particles. [51] Battery device according to claim 50, characterized by that the non-fluorinated polymer particles comprise acrylate copolymers. [52] Battery device according to claim 50 or 51, characterized by , that the first inorganic particles comprise one or more of silicon dioxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide; and / or wherein the first inorganic particles have an average particle size of 5 nm to 100 nm. [53] Battery device according to any one of claims 50 to 52, characterized by , that the second inorganic particles comprise one or more of silicon dioxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide; and / or wherein the average particle size of the second inorganic particles is 5 nm to 100 nm. [54] Battery device according to any one of claims 1 to 53, characterized by , that the electrode assembly further comprises a positive electrode tab and a negative electrode tab, wherein the positive electrode tab is connected to the positive current collector along at least one side of the longitudinal direction of the positive electrode plate and the negative electrode tab is connected to the negative current collector along at least one side of the longitudinal direction; wherein the dimension of the negative film layer along the longitudinal direction is larger than the dimension of the positive film layer, wherein the difference between the dimension of the negative film layer and the dimension of the positive film layer is OH1; wherein the dimension of the negative film layer along the width direction of the positive electrode plate is larger than the dimension of the positive film layer, wherein the difference between the dimension of the negative film layer and the dimension of the positive film layer is OH2; where OH1 is larger than OH2. [55] Battery device according to claim 54, characterized by , that OH1 is 0.5 mm to 3.0 mm and / or OH2 is 0.5 mm to 3.0 mm. [56] Battery device according to any one of claims 1 to 55, characterized by , that the battery cell comprises a housing, wherein the housing accommodates the electrode assembly and the electrolyte solution, the thickness of the housing being 0.1 mm to 0.5 mm. [57] Electrical appliance, characterized by that it comprises a battery device according to any one of claims 1 to 56.

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