Battery cell, battery device, and electrical device

Abstract

The present application provides a battery cell, a battery device, and an electrical device. The battery cell includes a positive electrode tab and an electrolyte; the positive electrode tab includes a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector, the positive electrode active layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and the single-sided surface density of the positive electrode active layer is 230 mg / 1540.25mm 2 ~400mg / 1540.25mm 2 ; the electrolyte includes a solvent and a lithium-containing electrolyte salt, the solvent includes a chain carboxylic acid ester and ethylene carbonate, and the lithium-containing electrolyte salt includes one or more of lithium hexafluorophosphate and a fluorosulfonylimide salt; wherein the mass ratio of the lithium-containing electrolyte salt to ethylene carbonate is 0.29-0.72; the conductivity of the electrolyte is 13 mS / cm-20 mS / cm.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of PCT patent application PCT / CN2024 / 107342 titled "Battery Cell, Battery Device and Electrical Device" filed on July 24, 2024, and the entire content of this application is incorporated herein by reference. Technical Field

[0003] This application relates to the technical field of battery cells, and particularly to a battery cell, a battery device and an electrical device. Background Art

[0004] In recent years, battery cells have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0005] With the dual increase in the market's demand for the driving range and charging efficiency of electrical devices, higher requirements are also put forward for the energy density, fast charging performance, etc. of battery cells. However, it is difficult to simultaneously improve the above performances in the prior art, which has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This application is made in view of the above problems, and its purpose is to provide a battery cell with both high energy density and good fast charging performance.

[0007] A first aspect of this application provides a battery cell, comprising a positive electrode tab and an electrolyte; the positive electrode tab comprises a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector, the positive electrode active layer comprises a positive electrode active material, the positive electrode active material comprises a lithium-containing phosphate, and the areal density of a single side of the positive electrode active layer is 230 mg / 1540.25 mm 2 ~400 mg / 1540.25 mm 2 ; the electrolyte comprises a solvent and a lithium-containing electrolyte salt, the solvent comprises a chain carboxylic ester and ethylene carbonate, the lithium-containing electrolyte salt comprises one or more of lithium hexafluorophosphate and a fluorosulfonylimide salt; wherein the mass ratio of the lithium-containing electrolyte salt to ethylene carbonate is 0.29 - 0.72; the conductivity of the electrolyte is 13 mS / cm - 20 mS / cm.

[0008] In the electrolyte, ethylene carbonate easily forms a solvation structure with lithium ions in the lithium-containing electrolyte salt to increase the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt. However, with the increase in the content of ethylene carbonate, the viscosity of the electrolyte also increases, which has a negative impact on the conductivity of the electrolyte. The chain carboxylic ester can improve the wettability between the electrolyte and the electrode sheet, improve the solid-liquid transport rate of lithium ions between the electrolyte and the electrode sheet, and at the same time, the addition of the chain carboxylic ester is also beneficial to the improvement of the conductivity of the electrolyte. The lithium-containing phosphate positive electrode sheet with a single-sided density within the above range has both a high solid-phase transport rate of lithium ions and a positive electrode active material loading. By matching the above electrolyte, the battery cell has a matching lithium ion dissociation rate, lithium ion liquid-phase transport rate, lithium ion liquid-solid transport rate, and lithium ion solid-phase transport rate, and realizes the balance of the fast charging performance and energy density of the battery cell through the mutual cooperation between various steps.

[0009] In any embodiment, in the electrolyte, the mass ratio of ethylene carbonate to the chain carboxylic ester is (0.26 - 1):1.

[0010] The mass ratio of ethylene carbonate to the chain carboxylic ester within the above range enables the electrolyte to have both appropriate viscosity, conductivity, and good dissociation rate and wettability, which is beneficial to the improvement of the fast charging performance of the battery cell.

[0011] In any embodiment, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic ester is 25.5% - 63.75%.

[0012] The electrolyte with the mass content of the chain carboxylic ester within the above range has both good conductivity, wettability, and chemical stability, which is beneficial to the comprehensive improvement of the fast charging performance and cycle stability of the battery cell.

[0013] In any embodiment, the chain carboxylic ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include one or more of C1~C5 alkyl groups and C1~C5 haloalkyl groups.

[0014] In any embodiment, the chain carboxylic ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

[0015] In any embodiment, based on the total mass of the electrolyte, the mass content ratio of ethylene carbonate is 17% - 34%.

[0016] The electrolyte with the mass content of ethylene carbonate within the above range has both good viscosity, dissociation rate, and conductivity, which is beneficial to the comprehensive improvement of the fast charging performance of the battery cell.

[0017] In any embodiment, the lithium-containing electrolyte salt includes lithium hexafluorophosphate LiPF6.

[0018] In any embodiment, the lithium-containing electrolyte salt further includes at least one of fluorosulfonylimide salts. Optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0019] Fluorosulfonylimide salts are prone to dissociation in the electrolyte solvent, which is beneficial to improving the conductivity of the electrolyte. Moreover, fluorosulfonylimide salts have high chemical stability and are not easily decomposed during the recycling process, which can reduce the generation of hydrogen fluoride during battery cycling, reduce the probability of side reactions occurring at the negative electrode, and improve the cycle stability of the battery cell.

[0020] In any embodiment, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6, and the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate LiPF6 in the electrolyte is (2 - 5):10.

[0021] A battery cell with the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate LiPF6 in the electrolyte within the above range can balance the fast charging performance and safety performance of the battery cell.

[0022] In any embodiment, the battery cell further includes a negative electrode plate, which includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material, and the volume distribution particle size Dv10 负 of the negative electrode active material is 3.5 μm - 7.5 μm, optionally 4.5 μm - 6.5 μm; Dv99 负 is 25 μm - 35 μm.

[0023] Dv10 负 and Dv99 负 The negative electrode active material within the above range includes a certain content of small particles and large particles at the same time, enabling the battery cell to improve the lithium ion transmission rate through small particles to improve the fast charging performance, and to improve the compaction density of the battery cell electrode plate through the particle size grading of large and small particles to improve the energy density of the battery cell, thus achieving a balance between the fast charging performance and the energy density.

[0024] In any embodiment, the electrolyte further contains additives, which include at least one of carbonate additives, sulfur-containing additives, and lithium salt additives. The lithium salt additives include one or more of lithium difluorophosphate LiPO2F2, lithium difluoro(oxalato)borate LiDFOB, lithium tetrafluoroborate LiBF4, and lithium bis(oxalato)borate LiBOB.

[0025] The above additives are all film-forming additives, which can form a film on the surface of the negative electrode active layer prior to the solvents and lithium-containing electrolyte salts in the electrolyte, improving the electrochemical performance of the battery cell.

[0026] The components of the SEI film formed by carbonate additives are mainly organic components with excellent toughness, which can improve the cycle stability of the battery cell; the components of the SEI film formed by sulfur-containing additives have excellent thermal stability and chemical stability, which can make up for the deficiencies of organic components and improve the storage performance of the battery cell at high temperatures; lithium salt additives can reduce the problem of insufficient lithium ions at high-rate charging speeds and achieve the effect of lithium supplementation while improving the stability of the SEI film.

[0027] In any embodiment, the additive includes at least two of carbonate additives, sulfur-containing additives, and lithium salt additives.

[0028] The performance of the battery cell under fast charging conditions is comprehensively improved through the interaction of two or more components in the additive.

[0029] In any embodiment, based on the total mass of the electrolyte, the mass ratio of the additive in the electrolyte is 1% to 10%, optionally 2% to 8%, and further optionally 3.5% to 8%.

[0030] In any embodiment, the carbonate additive includes one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0031] In any embodiment, the sulfur-containing additive includes one or more of divinyl sulfite (DTD), 2-divinyl disulfite (2-DTD), butene sulfite (BS), 1,3-propane sultone (PS), ethylene sulfite (ES), and methylene methyl disulfonate (MMDS).

[0032] In any embodiment, the additive includes vinylene carbonate (VC); based on the total mass of the electrolyte, the mass content of vinylene carbonate (VC) in the electrolyte is 0.5% to 9%, optionally 2% to 6%.

[0033] Chain carboxylic esters have high activity, which can improve the wettability between the electrolyte and the electrode sheet and the conductivity of the electrolyte while eroding the solid electrolyte membrane (SEI membrane). Vinylene carbonate (VC) has a reduction potential close to that of chain carboxylic esters, which can inhibit the reaction activity of chain carboxylic esters and improve the cycle life of the battery cell.

[0034] In any embodiment, the additive includes fluoroethylene carbonate (FEC); based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate (FEC) in the electrolyte ranges from 0.1% to 4%, and may optionally be 0.5% - 3%.

[0035] If the content of vinylene carbonate (VC) is too high, it will cause an increase in the interfacial impedance and charge transfer impedance of the battery, which has an adverse effect on the fast charging performance of the battery cell. Fluoroethylene carbonate (FEC) can also form a film on the surface of the negative electrode at a relatively high potential and has a lower interfacial impedance and charge transfer impedance. However, the SEI film formed by fluoroethylene carbonate (FEC) has poor high-temperature stability, which is not conducive to the stability of the battery cell in a high-temperature environment. By adding vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in the electrolyte, the fast charging performance and high-temperature stability of the battery cell can be effectively balanced.

[0036] In any embodiment, the electrolyte includes vinylene carbonate and fluoroethylene carbonate, and the mass ratio of the total mass of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the mass of the chain carboxylic ester is 0.008 - 0.5.

[0037] Vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are combined with each other to improve the erosion of the chain carboxylic ester in the electrolyte on the SEI film, and effectively balance the fast charging performance and storage stability of the battery cell.

[0038] In any embodiment, the conductivity of the electrolyte is 14 mS / cm - 20 mS / cm, and may optionally be 15 mS / cm - 20 mS / cm.

[0039] The electrolyte with a conductivity within the above range can better balance the fast charging performance and cycle life of the battery cell.

[0040] In any embodiment, the single-sided areal density of the positive electrode active layer is 280 mg / 1540.25 mm 2 ~370 mg / 1540.25 mm 2 .

[0041] The positive electrode active layer with a single-sided areal density within the above range can more effectively balance the fast charging performance and energy density of the battery cell.

[0042] In any embodiment, when the battery cell is at 100% SOC, the tap density of the positive electrode active layer is 2.50 g / cm 3 ~2.80 g / cm 3 ; and may optionally be 2.55 g / cm 3 ~2.68 g / cm 3 .

[0043] When the battery cell is at 100% SOC, the positive electrode active layer with a tap density within the above range can achieve a balance between the fast charging performance and the energy density of the battery cell.

[0044] In any embodiment, the lithium-containing phosphate is a lithium-containing phosphate with an olivine structure, including the components shown in Formula I, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I

[0045] wherein, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.7 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, and 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

[0046] The lithium-containing phosphate with an olivine structure having the above components has good structural stability, can reduce the loss during fast charging, and improve the cycle stability of the battery cell.

[0047] In any embodiment, the positive electrode active material further includes an ion-conducting layer disposed on the surface of the lithium-containing phosphate, and the ion-conducting layer includes carbon. Based on the total mass of the positive electrode active material, the mass percentage of carbon is 1% - 2%.

[0048] The above ion-conducting layer containing carbon can simultaneously improve the ion conductivity and electrical conductivity of the positive electrode active material, improve the solid-phase transport rate of ions and electrons, and improve the energy density and fast charging performance of the battery cell.

[0049] In any embodiment, the ion-conducting layer further includes a fast ion conductor having a NASICON structure shown in Formula II

[0050] Li 3-b2 Fe 2-b2 M2 b2 (PO x2 ) y2 Formula II

[0051] In the formula II, M2 is selected from one or more of +4-valent Ti, Zr, Hf, Ge, and Sn, 0 ≤ b2 ≤ 1, 3 ≤ x2 ≤ 5, 2 ≤ y2 ≤ 4.

[0052] The fast ion conductor with NASICON structure has rich three-dimensional lithium ion diffusion and transport channels, and has advantages such as high ion conduction efficiency and strong structural stability during multiple de-lithiation and intercalation processes. Coating the surface of lithium-containing phosphate with a fast ion conductor containing NASICON structure can significantly improve the transport rate of lithium ions during multiple de-intercalation / intercalation at the positive electrode, improve the ion conductivity of the positive electrode active material, and improve the energy density and fast charging performance of the corresponding battery cell.

[0053] In any embodiment, the fast ion conductor includes one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, and Li2FeSn(PO4)3.

[0054] In any embodiment, the powder compaction density of the positive electrode active material under a pressure of 30000N is greater than or equal to 2.46 g / cm 3 , and may be 2.46 g / cm 3 -2.8 g / cm 3 .

[0055] In any embodiment, the volume average particle size of the positive electrode active material satisfies: 1 µm ≤ Dv50 正 ≤ 2 µm, 0.4 µm ≤ Dv10 正 ≤ 0.7 µm.

[0056] The above positive electrode active material effectively improves the powder compaction density and the carrier conduction between the positive electrode active materials through the grading of large and small particles, which is beneficial to taking into account the energy density and fast charging performance of the battery cell.

[0057] In any embodiment, the powder resistivity R of the positive electrode active material is ≤ 27.5 Ω•cm.

[0058] In any embodiment, the specific surface area S of the positive electrode active material is 5 m 2 / g ~ 18 m 2 / g.

[0059] The carbon structure in the positive electrode active layer has a high degree of correlation. The positive electrode active material with powder resistivity and specific surface area within the above ranges has both good ion conductivity and electron conductivity, which is beneficial to the improvement of the fast charging performance of the battery cell.

[0060] In any embodiment, the positive electrode active layer includes a lithium supplementing agent, and the lithium supplementing agent includes at least one of a ternary lithium supplementing material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and trilithium citrate.

[0061] Adding a lithium supplementing agent to the positive electrode active layer can offset the irreversible lithium loss during the electrochemical process to improve the total capacity and energy density of the battery cell.

[0062] In any embodiment, the general formula of the ternary lithium supplementing material is shown in Formula III,

[0063] Li x3 A y3 Ni a3 Co b3 Mn c3 M3 (1-a3-b3-c3) Y z3 , Formula III

[0064] where 0 ≤ x3 ≤ 2.1, 0 ≤ y3 ≤ 2.1, and 0.9 ≤ x3 + y3 ≤ 2.1; 0 ≤ a3 ≤ 1, 0 ≤ b3 ≤ 1, 0 ≤ c3 ≤ 1, and 0.1 ≤ a3 + b3 + c3 ≤ 1; 1.8 ≤ z3 ≤ 3.5; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y includes one or more of O and F.

[0065] In any embodiment, the mass content ratio of the lithium supplementing agent added in the positive electrode active layer is 0.1% - 10%.

[0066] In any embodiment, the positive electrode tab includes a positive electrode conductive layer, the positive electrode conductive layer is disposed between the positive electrode current collector and the positive electrode active layer, and the thickness of the positive electrode conductive layer is 0.5 µm - 2 µm; and / or the negative electrode tab includes a negative electrode conductive layer, the negative electrode conductive layer is disposed between the negative electrode current collector and the negative electrode active layer, and the thickness of the negative electrode conductive layer is 0.5 µm - 2 µm.

[0067] The provision of the positive electrode conductive layer and / or the negative electrode conductive layer is beneficial to improving the electronic conductivity of the battery cell tab and beneficial to improving the energy density of the battery cell.

[0068] In any embodiment, the positive electrode conductive layer comprises a conductive agent and a first binder, the negative electrode conductive layer comprises a conductive agent and a second binder, the conductive agent comprises one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. Optionally, the conductive agent comprises superconducting carbon and carbon nanotubes, the first binder comprises a fluorine-containing binder, and the second binder comprises a water-soluble binder.

[0069] In any embodiment, based on the total mass of the positive electrode conductive layer, the mass content of the conductive agent in the positive electrode conductive layer is 30% to 50%, and the mass content of the first binder is 50% to 70%; and / or based on the total mass of the negative electrode conductive layer, the mass content of the conductive agent in the negative electrode conductive layer is 20% to 40%, and the mass content of the second binder is 60% to 80%.

[0070] In any embodiment, the single-sided areal density of the negative electrode active layer is 104 mg / 1540.25 mm 2 -180 mg / 1540.25 mm 2 ; optionally 125 mg / 1540.25 mm 2 -167 mg / 1540.25 mm 2 .

[0071] The negative electrode active layer with a single-sided areal density within the above range can cooperate with the positive electrode active layer to achieve a balance between the energy density and fast charging performance of the battery cell.

[0072] In any embodiment, when the battery cell is at 100% SOC, the tap density of the negative electrode active layer is 1.15 g / cm 3 ~1.36 g / cm 3 ; optionally 1.25 g / cm 3 ~1.36 g / cm 3 .

[0073] In any embodiment, the negative electrode active material comprises graphite.

[0074] In any embodiment, the graphite comprises composite graphite particles, the composite graphite particles comprise body particles and a coating layer disposed at least partially on the surface of the body particles, the body particles comprise artificial graphite, the coating layer comprises amorphous carbon, and the composite graphite particles comprise secondary particles.

[0075] The composite graphite particles comprising secondary particles and the surface coating layer comprising amorphous carbon are both beneficial to the infiltration of the electrolyte in the negative electrode active layer of the electrode sheet, and contribute to the improvement of the rate performance of the battery cell.

[0076] In any embodiment, based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5%.

[0077] When the content of amorphous carbon is within a suitable range, the composite graphite material can have a high specific capacity while also having a high active ion solid-phase transport ability, which is beneficial to improving the fast charging performance of the battery cell.

[0078] In any embodiment, the powder resistivity of the negative electrode active material is less than or equal to 0.04 Ω•cm.

[0079] In any embodiment, the powder compaction density of the negative electrode active material under a pressure of 20000 N is 1.5 g / cm 3 to 1.7 g / cm 3 , and may be optionally 1.55 g / cm 3 to 1.65 g / cm 3 .

[0080] The negative electrode active material with a powder compaction density within a suitable range can make the negative electrode active layer have a high compaction density, and thus the battery cell has a high energy density; at the same time, the original pore structure of the negative electrode active layer can be maintained during the cycling process, which is beneficial to improving the retention of the high fast charging performance of the battery cell during the cycling process.

[0081] In any embodiment, the negative electrode active material further includes a silicon-based material, and the silicon-based material includes at least one of silicon, silicon oxide compound, and silicon-carbon composite; based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material is 0.3% to 10%, and may be optionally 1% to 6%.

[0082] The introduction of the silicon-based material is beneficial to improving the energy density of the battery cell. The silicon-based material within the above mass range can balance the energy density and cycling stability of the battery cell.

[0083] In some embodiments, the charging specific capacity of the negative electrode active material is 350 mAh / g to 480 mAh / g.

[0084] The negative electrode active material with a charging specific capacity within the above range is beneficial to improving the energy density of the battery cell.

[0085] In any embodiment, the negative electrode active layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, and the second negative electrode active material layer includes composite graphite particles.

[0086] In any embodiment, the first negative electrode active material layer includes one or more of composite graphite particles and natural graphite.

[0087] The composite graphite particles are disposed close to the electrolyte side, which can take into account the energy density while improving the fast charging performance of the battery cell.

[0088] In any embodiment, the ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer is 3:7 to 7:3.

[0089] In any embodiment, the volume average particle diameter Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 µm to 18.5 µm, and can be optionally 9.5 µm to 14.8 µm.

[0090] In any embodiment, the volume average particle diameter Dv502 of the negative electrode active material in the second negative electrode active layer is 7.8 µm to 14.3 µm, and can be optionally 7.8 µm to 12.8 µm.

[0091] The second negative electrode active material layer disposed on the electrolyte side includes negative electrode active materials with smaller particle sizes, which can further improve the solid-liquid transport rate of ions in the battery electrode sheet and improve the fast charging performance of the battery cell.

[0092] In any embodiment, the battery cell further includes a separator, the separator includes a porous base film and a functional layer disposed on at least one side of the porous base film, and the thickness of the porous base film is less than or equal to 12 µm, and can be optionally less than or equal to 9 µm.

[0093] In any embodiment, the porosity of the porous base film in the separator is 20% - 70%, and can be optionally 35% - 60%.

[0094] In any embodiment, the functional layer includes a first functional layer disposed on the negative electrode side of the porous base film and a second functional layer disposed on the positive electrode side of the porous base film. The first functional layer includes first inorganic particles, the second functional layer includes composite particles, the composite particles include second inorganic particles and non-fluoropolymer particles, and the second inorganic particles in the composite particles are attached to the surface and / or dispersed inside the non-fluoropolymer particles.

[0095] Inorganic particles can improve the heat resistance of the first functional layer and the second functional layer and improve the fast charging performance of the battery cell.

[0096] In any embodiment, the non-fluoropolymer particles include acrylate copolymers.

[0097] In any implementation, the electrolyte injection coefficient of the battery cell is 2.4 g / Ah - 3.1 g / Ah.

[0098] The electrolyte injection coefficient within the above range can improve the cycling stability of the battery cell.

[0099] In any implementation, the battery cell further includes electrode terminals, and the electrode assembly includes tab portions, and the tab portions are directly welded to the electrode terminals.

[0100] In any implementation, the time for the battery cell to charge from 10% state of charge (SOC) to 80% state of charge (SOC) at 30°C is 6 min - 15 min.

[0101] The battery cell has good fast charging performance and can meet the demand for improving the energy replenishment efficiency of the electrical device.

[0102] In any implementation, the battery cell is of a wound structure, the thickness of the positive current collector is less than or equal to 15 µm, and the thickness of the negative current collector is less than or equal to 6 µm.

[0103] The positive current collector and / or the negative current collector have a low thickness, enabling further improvement of the energy density of the battery cell.

[0104] In any implementation, the volume energy density of the battery cell is 400 Wh / L - 500 Wh / L.

[0105] The battery cell simultaneously has a high energy density and can meet the demand for increasing the driving range of the electrical device.

[0106] The second aspect of the present application provides a battery device, including the battery cell provided in the first aspect of the present application, and the battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0107] The third aspect of the present application further provides an electrical device, and the electrical device includes the battery cell provided in the first aspect of the present application. Description of the Drawings

[0108] Figure 1 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0109] Figure 2 is Figure 1 the exploded view of the battery cell shown in an embodiment of the present application.

[0110] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0111] Figure 4It is a schematic diagram of a battery pack according to an embodiment of the present application.

[0112] Figure 5 is Figure 4 An exploded view of the battery pack according to an embodiment of the present application shown.

[0113] Figure 6 It is a schematic diagram of an electrical device using a battery cell as a power source according to an embodiment of the present application.

[0114] Description of reference numerals:

[0115] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed implementation manners

[0116] Hereinafter, embodiments of the battery cell and the electrical device of the present application specifically disclosed will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0117] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0118] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0119] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0120] Unless otherwise specified, all steps of this application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0121] Unless otherwise specified, the "including" and "comprising" mentioned in this application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0122] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0123] The fast charging technology aims to shorten the time required for battery charging, mainly by increasing the charging current and improving the charging rate to achieve the rapid insertion / extraction of active ions in the active material layer. High-energy-density batteries usually have a high areal density in the active material layer, but the high areal density will affect the insertion / extraction rate of active ions in the battery cell, thereby reducing the fast charging performance of the battery cell. Therefore, the fast charging performance and energy density of the battery cell are often "contradictory points" that are difficult to balance.

[0124] Based on this, a first aspect of this application provides a battery cell, including a positive electrode plate and an electrolyte; the positive electrode plate includes a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector, the positive electrode active layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and the areal density of a single side of the positive electrode active layer is 230 mg / 1540.25mm 2 ~400mg / 1540.25mm 2; The electrolyte contains a solvent and a lithium-containing electrolyte salt. The solvent includes a chain carboxylic acid ester and ethylene carbonate. The lithium-containing electrolyte salt includes one or more of lithium hexafluorophosphate and fluorosulfonylimide salts. Wherein the mass ratio of the lithium-containing electrolyte salt to ethylene carbonate is 0.29 - 0.72; the conductivity of the electrolyte is 13 mS / cm - 20 mS / cm.

[0125] In this application, the "single-sided areal density of the positive electrode active layer" refers to the mass of the positive electrode active layer per unit area on one side of the current collector.

[0126] In this application, the single-sided areal density of the positive electrode active layer can be tested by methods known in the art. For example, a single-sided coated and cold-pressed positive electrode sheet (if it is a double-sided coated positive electrode sheet, the positive electrode active layer on one side can be wiped off first) can be taken and punched into small round pieces with an area of S1, weighed, and recorded as M1. Then, the positive electrode active layer of the above-mentioned weighed positive electrode sheet is wiped off, and the mass of the positive electrode current collector is weighed and recorded as M0. The single-sided areal density of the positive electrode sheet = (M1 - M0) / S1.

[0127] In some embodiments, the single-sided areal density of the positive electrode active layer can be selected as 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 、325 mg / 1540.25 mm 2 、340 mg / 1540.25 mm 2 、350 mg / 1540.25 mm 2 、360 mg / 1540.25 mm 2 、375 mg / 1540.25 mm 2 、400 mg / 1540.25 mm 2 or any value range between any two of them.

[0128] The lithium-containing phosphate is an active material with an olivine structure including lithium ions and phosphate groups. The types of the cathode active materials can be tested by any well-known method in the art. As an example, phase analysis methods such as X-ray diffraction (XRD) can be combined with elemental analysis methods such as energy spectrum and XPS for analysis.

[0129] The types and masses of the solvents and lithium-containing electrolyte salts in the electrolyte can be obtained by detecting the electrolyte through methods well-known to those skilled in the art. For example, the composition in the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Exemplarily, disassemble the battery cell, obtain the free electrolyte from the battery cell, dilute the free electrolyte in the battery cell with acetonitrile by 3 to 10 times to obtain the electrolyte dilution to be tested, use a GC-MS 3100 organic component gas chromatograph, place the above electrolyte dilution in the instrument for full-scan qualitative analysis, with the inlet temperature of 250 °C and the scanning range: 35 μm to 270 μm. After the test is completed, obtain the total ion current chromatogram of each organic substance, compare the corresponding organic substance types according to the peak positions in the chromatogram, and calculate the percentage of the corresponding content of each organic substance according to the peak areas. Exemplarily, an ion chromatograph (IC) can be used to test the content of inorganic substances in the electrolyte. Weigh a quantitative electrolyte (the dilution concentration is in the middle of the standard curve), make up the volume to 100 mL with ultrapure water, and perform automatic injection detection by the ion chromatograph to test the ion chromatogram of inorganic substances, and compare the corresponding inorganic substance types according to the peak positions in the chromatogram.

[0130] In some embodiments, the mass ratio of the lithium-containing electrolyte salt to ethylene carbonate can be selected as 0.29, 0.31, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72 or the numerical range between any two of them.

[0131] The conductivity of the electrolyte is to describe the ability of the positive and negative ions dissociated in the electrolyte solution to move directionally in an electric field to constitute the conduction process, and can be tested by any well-known method in the art. As an example, take about 100 mL of the electrolyte sample with a dry, clean and corrosion-resistant sample bottle, seal it and place it in a constant temperature water bath, shake the sample from time to time, and keep the temperature constant at 25 °C (deviation ±5 °C). After the temperature of the sample is constant, use a commercially available conductivity meter to test its conductivity. After wiping the conductivity meter clean with the calibration solution, vertically place it into the liquid to be tested, click to start the test, and record the test result after the data is stable for more than 10 s.

[0132] In some embodiments, the conductivity of the electrolyte can be optionally 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, 20 mS / cm, 21 mS / cm, 22 mS / cm, 23 mS / cm, 24 mS / cm, 25 mS / cm or the numerical range between any two of them.

[0133] Ethylene carbonate in the electrolyte and lithium ions in the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt. However, with the increase in the content of ethylene carbonate, the viscosity of the electrolyte will also increase, which has a negative impact on the conductivity of the electrolyte; while chain carboxylic esters can improve the wettability between the electrolyte and the electrode sheet, and improve the solid-liquid transport rate of lithium ions between the electrolyte and the electrode sheet. At the same time, the addition of chain carboxylic esters is also beneficial to the improvement of the electrolyte conductivity. The lithium-containing phosphate positive electrode sheet with a single-sided density in the above range has both a high solid-phase transport rate of lithium ions and a positive electrode active material loading. By matching the above electrolyte, the battery cell has a matching lithium ion dissociation rate, lithium ion liquid-phase transport rate, lithium ion liquid-solid transport rate, and lithium ion solid-phase transport rate, and realizes the balance of the fast charging performance and energy density of the battery cell through the mutual cooperation of each step.

[0134] In some embodiments, in the electrolyte, the mass ratio of ethylene carbonate to the chain carboxylic ester is (0.26-1):1.

[0135] In some embodiments, in the electrolyte, the mass ratio of ethylene carbonate to the chain carboxylic ester can be optionally 0.26:1, 0.30:1, 0.36:1, 0.40:1, 0.46:1, 0.50:1, 0.56:1, 0.60:1, 0.66:1, 0.70:1, 0.76:1, 0.80:1, 0.86:1, 0.90:1, 0.96:1, 1:1 or the numerical range between any two of them.

[0136] The mass ratio of ethylene carbonate to the chain carboxylic ester in the above range enables the electrolyte to have appropriate viscosity, conductivity, good dissociation rate and wettability at the same time, which is beneficial to the improvement of the fast charging performance of the battery cell.

[0137] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic ester is 25.5%-63.75%.

[0138] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic acid ester can be optionally 25.5%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 63.75% or a numerical range between any two of them.

[0139] The electrolyte with the mass content of the chain carboxylic acid ester within the above range has both good conductivity, wettability and chemical stability, which is beneficial to the comprehensive improvement of the fast charging performance and cycle stability of the battery monomer.

[0140] In some embodiments, the chain carboxylic acid ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include one or more of C1-C5 alkyl groups and C1-C5 haloalkyl groups.

[0141] "C1-C5 alkyl" refers to an unbranched or branched alkyl group having 1-5 carbon atoms; including but not limited to one or more of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl.

[0142] "C1-C5 haloalkyl" refers to an unbranched or branched alkyl group having 1-5 carbon atoms with at least one hydrogen atom substituted by a halogen, including but not limited to one or more of chloroalkyl, bromoalkyl, iodoalkyl.

[0143] In some embodiments, the chain carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, methyl formate.

[0144] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of ethylene carbonate is 17%-34%.

[0145] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of ethylene carbonate can be optionally 17%, 18%, 19%, 20%, 25%, 30%, 34% or a numerical range between any two of them.

[0146] The electrolyte with the mass content of ethylene carbonate within the above range has both good viscosity, dissociation rate and conductivity, which is beneficial to the comprehensive improvement of the fast charging performance of the battery monomer.

[0147] In some embodiments, the lithium-containing electrolyte salt includes lithium hexafluorophosphate LiPF6.

[0148] In some embodiments, the lithium-containing electrolyte salt further includes at least one of fluorosulfonylimide salts. Optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0149] Fluorosulfonylimide salts are prone to dissociation in the electrolyte solvent, which is beneficial to improving the conductivity of the electrolyte. Moreover, fluorosulfonylimide salts have high chemical stability and are not easily decomposed during the recycling process. They can reduce the generation of hydrogen fluoride during the battery cycling process, decrease the probability of side reactions occurring at the negative electrode, and improve the cycle stability of the battery cell. However, with the increase in the temperature of the battery cell, the fluorosulfonylimide salt will undergo violent decomposition at a certain temperature threshold, releasing a large amount of heat and sharply increasing the risk of thermal runaway of the battery. This safety risk is more significant in fast-charging batteries. Although lithium hexafluorophosphate will gradually decompose to produce hydrofluoric acid during the secondary cycling process, the addition of lithium hexafluorophosphate will greatly reduce the risk of thermal runaway of the battery cell, keeping the risk within a controllable range and improving the safety of the battery.

[0150] In some embodiments, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), and the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate (LiPF6) in the electrolyte is (2 - 5):10.

[0151] In some embodiments, the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate (LiPF6) in the electrolyte can be selected as 2:10, 3:10, 4:10, 5:10 or the numerical range between any two of them.

[0152] The battery cell with the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate (LiPF6) in the electrolyte within the above range can balance the fast-charging performance and safety performance of the battery cell.

[0153] In some embodiments, the battery cell further includes a negative electrode plate, which includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material, and the volume distribution particle size Dv10 负 of the negative electrode active material is 3.5 μm - 7.5 μm, and can be selected as 4.5 μm - 6.5 μm; Dv99 负 is 25 μm - 35 μm.

[0154] The volume distribution particle size Dv10 负 、Dv99 负It has the meanings well-known in the art, which respectively represent the particle sizes corresponding to when the cumulative volume distribution percentage of the material reaches 10% and 99%, and can be measured by the instruments and methods known in the art. For example, it can be conveniently measured with reference to GB / T 19077-2016 Laser diffraction method for particle size distribution by using a laser particle size analyzer. The test instrument can be the Mastersizer 3000 type laser particle size analyzer of Malvern Instruments Limited, UK. The negative electrode active material can be freshly prepared negative electrode active material or can be obtained by scraping powder from the negative electrode active layer after disassembling a secondary battery.

[0155] In some embodiments, the volume distribution particle size Dv10 of the negative electrode active material 负 can be optionally 3.5μm, 4.5μm, 5.5μm, 6.5μm, 7.5μm or the numerical range between any two of them.

[0156] In some embodiments, the volume distribution particle size Dv99 of the negative electrode active material 负 can be optionally 25μm, 27μm, 30μm, 32μm, 35μm or the numerical range between any two of them.

[0157] Dv10 负 and Dv99 负 The negative electrode active material within the above range includes a certain content of small particles and large particles at the same time, so that the battery cell can improve the lithium ion transmission rate through small particles to improve the fast charging performance, and can also improve the compaction density of the battery cell electrode sheet through the particle size grading of large and small particles to improve the energy density of the battery cell, achieving the balance between the fast charging performance and the energy density.

[0158] In some embodiments, the electrolyte further contains additives, and the additives include at least one of carbonate additives, sulfur-containing additives, and lithium salt additives. The lithium salt additives include one or more of lithium difluorophosphate LiPO2F2, lithium difluorooxalate borate LiDFOB, lithium tetrafluoroborate LiBF4, and lithium bis(oxalato)borate LiBOB.

[0159] Additives refer to components with relatively low contents in the electrolyte, generally with a mass fraction in the electrolyte not exceeding 10%. They are characterized by strong pertinence and small dosages. Without changing the production process, they can significantly optimize certain aspects of the battery's performance. The components of the additives can be obtained by any well-known method in the art. As an example, the composition in the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Exemplarily, an ion chromatograph (IC) can be used to test the inorganic content in the electrolyte. Weigh a certain amount of electrolyte (the dilution concentration is in the middle of the standard curve), make up the volume to 100 mL with ultrapure water, and automatically inject the sample into the ion chromatograph for detection. Test the inorganic ion chromatogram, and compare the corresponding inorganic species according to the peak position in the chromatogram. Dilute the above free electrolyte with acetonitrile by 3 to 10 times to obtain the electrolyte dilution to be tested. Use a GC-MS 3100 gas chromatograph for organic components. Place the above electrolyte dilution in the instrument for full-scan qualitative analysis. The inlet temperature is 250 °C, and the scanning range is 35 μm to 270 μm. After the test is completed, obtain the total ion current chromatogram of each organic substance, and compare the corresponding organic species according to the peak position in the chromatogram.

[0160] The above additives are all film-forming additives, which can form a film on the surface of the negative electrode active layer prior to the solvent and lithium-containing electrolyte salt in the electrolyte, improving the electrochemical performance of the battery cell.

[0161] In some embodiments, the additive includes at least two of carbonate additives, sulfur-containing additives, and lithium salt additives.

[0162] The SEI film components formed by carbonate additives are mainly organic components with excellent toughness, which can improve the cycle stability of the battery cell; the SEI film components formed by sulfur-containing additives have excellent thermal stability and chemical stability, which can make up for the deficiencies of organic components and improve the storage performance of the battery cell at high temperatures; lithium salt additives can reduce the problem of insufficient lithium ions at high-rate charging speeds, realize the lithium supplement function while improving the stability of the SEI film, and comprehensively improve the performance of the battery cell under fast charging conditions through the interaction of two or more of these components.

[0163] In some embodiments, based on the total mass of the electrolyte, the mass fraction of the additive in the electrolyte is 1% to 10%, optionally 2% to 8%, and further optionally 3.5% to 8%.

[0164] In some embodiments, based on the total mass of the electrolyte, the mass percentage of the additive in the electrolyte can be optionally 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or a numerical range between any two of them.

[0165] Based on the total mass of the electrolyte, the mass percentage of the additive in the electrolyte can be measured by any well-known method in the art. As an example, the testing method for the mass of the solvent and the lithium-containing electrolyte salt in the electrolyte described above can be used for testing. It should be understood that since the additive in the electrolyte will be consumed to some extent during formation and cycling, generating relevant components in the SEI film, the mass percentage of the additive in the electrolyte may be slightly lower than the initial added mass percentage of the additive in the electrolyte.

[0166] In some embodiments, the carbonate additive includes one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0167] In some embodiments, the sulfur-containing additive includes one or more of ethylene sulfate (DTD), bis(ethylene sulfate) (2-DTD), butene sulfite (BS), 1,3-propane sultone (PS), ethylene sulfite (ES), and methylene methyl disulfonate (MMDS).

[0168] In some embodiments, the additive includes vinylene carbonate (VC); based on the total mass of the electrolyte, the mass content of vinylene carbonate (VC) in the electrolyte is 0.5% to 9%, and can be optionally 2% - 6%.

[0169] In some embodiments, based on the total mass of the electrolyte, the mass content percentage of vinylene carbonate (VC) in the electrolyte can be optionally 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or a numerical range between any two of them.

[0170] Chain carboxylic esters have high activity. While improving the wettability between the electrolyte and the electrode sheet and the conductivity of the electrolyte, they will also erode the solid electrolyte membrane (SEI membrane). Vinylene carbonate (VC) has a reduction potential close to that of chain carboxylic esters, which can inhibit the reaction activity of chain carboxylic esters and improve the cycle life of the battery monomer.

[0171] In some embodiments, the additive includes fluoroethylene carbonate (FEC); based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate (FEC) in the electrolyte ranges from 0.1% to 4%, optionally from 0.5% to 3%.

[0172] In some embodiments, based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate (FEC) in the electrolyte can be optionally 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or any value range between any two of them.

[0173] Excessive content of vinylene carbonate (VC) will lead to an increase in the interfacial impedance and charge transfer impedance of the battery, which has an adverse effect on the fast charging performance of the battery cell. Fluoroethylene carbonate (FEC) can also form a film on the surface of the negative electrode at a relatively high potential and has a lower interfacial impedance and charge transfer impedance. However, the high-temperature stability of the SEI film formed by fluoroethylene carbonate (FEC) is poor, which is not conducive to the stability of the battery cell in a high-temperature environment. By adding vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in the electrolyte, the fast charging performance and high-temperature stability of the battery cell can be effectively balanced.

[0174] In some embodiments, the electrolyte includes vinylene carbonate and fluoroethylene carbonate, and the mass ratio of the total mass of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the mass of the chain carboxylic ester is 0.008 - 0.5.

[0175] In some embodiments, the mass ratio of the total mass of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in the electrolyte to the mass of the chain carboxylic ester can be optionally 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5 or any value range between any two of them.

[0176] Vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are combined with each other to improve the erosion of the chain carboxylic ester in the electrolyte on the SEI film, effectively balancing the fast charging performance and storage stability of the battery cell.

[0177] In some embodiments, the conductivity of the electrolyte is 14 mS / cm - 20 mS / cm, optionally 15 mS / cm - 20 mS / cm.

[0178] The electrolyte with conductivity within the above range can better balance the fast charging performance and cycle life of the battery cell.

[0179] In some embodiments, the single-sided areal density of the positive electrode active layer is 280 mg / 1540.25mm 2~370mg / 1540.25mm 2 。

[0180] The positive electrode active layer with a single-sided density within the above range can more effectively balance the fast charging performance and energy density of the battery cell.

[0181] In some embodiments, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is 2.50 g / cm 3 ~2.80 g / cm 3 ; optionally 2.55 g / cm 3 ~2.68 g / cm 3 。

[0182] In some embodiments, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer can be optionally 2.50 g / cm 3 、2.55 g / cm 3 、2.60 g / cm 3 、2.68 g / cm 3 、2.70 g / cm 3 、2.75 g / cm 3 、2.80 g / cm 3 or any value range between any two of them.

[0183] In the present application, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer has the meaning well-known in the art and can be tested by methods known in the art. For example, the battery cell is charged at a constant current charging rate of 0.33C according to a charging strategy to the cut-off voltage (for example, 3.65V), left standing for 1 minute, and then continued to be charged at a constant current charging rate of 0.1C to the cut-off voltage. At this time, the battery cell is charged to 100% SOC, and then the positive electrode plate is disassembled to measure the compaction density of the positive electrode active layer. The compaction density of the positive electrode active layer is the surface density of the positive electrode active layer measured after disassembly / the thickness of the positive electrode active layer. The surface density of the positive electrode active layer can be tested by the method mentioned above, and the thickness of the positive electrode active layer has the meaning well-known in the art and can be tested by methods known in the art, for example, tested by a micrometer (for example, Mitutoyo 293-100 type, with an accuracy of 0.1 μm). It can be understood that when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is different from the designed value of the battery cell compaction density. Affected by actual operations, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is often slightly lower than the designed value of the battery cell compaction density.

[0184] When the battery cell is at 100% SOC, the positive electrode active layer with a compaction density within the above range can achieve the balance of the fast charging performance and energy density of the battery cell.

[0185] In some embodiments, the lithium-containing phosphate is a lithium-containing phosphate with an olivine structure, including components shown in Formula I, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I,

[0186] wherein, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.7 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, and 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F.

[0187] In some embodiments, x1 can be selected from 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or the numerical range between any two of them; y1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or the numerical range between any two of them; x1 + y1 can be selected from 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or the numerical range between any two of them; a1 can be selected from 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or the numerical range between any two of them; b1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5 or the numerical range between any two of them; a1 + b1 can be selected from 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or the numerical range between any two of them; c1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5 or the numerical range between any two of them; z1 can be selected from 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or the numerical range between any two of them.

[0188] The lithium-containing phosphate with an olivine structure having the above components has good structural stability, can reduce the loss during fast charging, and improve the cycle stability of the battery cell.

[0189] In some embodiments, the positive electrode active material further includes an ion-conducting layer disposed on the surface of the lithium-containing phosphate. The ion-conducting layer includes carbon element, and based on the total mass of the positive electrode active material, the mass percentage of the carbon element is 1% to 2%.

[0190] In some embodiments, based on the total mass of the positive electrode active material, the mass percentage of the carbon element can be selected from 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% or the numerical range between any two of them.

[0191] It should be noted that the ion-conducting layer can be a single-layer structure or a multi-layer structure. That is to say, the ion-conducting components and carbon-containing components in the ion-conducting layer can be a mixed phase or a layered arrangement. It can be understood that the ion-conducting layer has a high ion transport rate.

[0192] The above-mentioned ion-conducting layer containing carbon element can simultaneously improve the ion conductivity and electrical conductivity of the positive electrode active material, improve the solid-phase transport rate of ions and electrons, and improve the energy density and fast charging performance of the battery cell.

[0193] In some embodiments, the ion-conducting layer further includes a fast ion conductor having a NASICON structure as shown in Formula II

[0194] Li 3-b2 Fe 2-b2 M2 b2 (PO x2 ) y2 Formula II

[0195] In Formula II, M2 is selected from one or more of Ti, Zr, Hf, Ge, and Sn with a valence of +4, 0≤b2≤1, 3≤x2≤5, 2≤y2≤4.

[0196] In some embodiments, b2 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or the numerical range between any two of them, x2 can be selected from 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or the numerical range between any two of them, and y2 can be selected from 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4 or the numerical range between any two of them.

[0197] The phase structure in the ion-conducting layer can be characterized by any well-known method in the art. For example, by characterizing the positive electrode active material through a transmission electron microscope, it can be seen that there are different phase structures in the ion-conducting layer and the matrix of the positive electrode active material. Combining the diffraction pattern and energy spectrum analysis can judge the fast ion conductor components in the ion-conducting layer.

[0198] Fast ion conductors, also known as superionic conductors and solid electrolytes, refer to solids whose ionic conductivity is close to or exceeds that of conductive liquids such as electrolyte solutions or molten salts. Fast ion conductors with NASICON structure have rich three-dimensional lithium-ion diffusion and transport channels, and have advantages such as high ion conduction efficiency and strong structural stability during multiple de-lithiation and intercalation processes. Coating the surface of lithium-containing phosphate with a fast ion conductor containing NASICON structure can significantly improve the transport rate of lithium ions during multiple de-intercalation / intercalation at the positive electrode end, improve the ionic conductivity of the positive electrode active material, and improve the energy density and fast charging performance of the corresponding battery monomer.

[0199] In some embodiments, the fast ion conductor includes one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, and Li2FeSn(PO4)3.

[0200] In some embodiments, the powder compaction density of the positive electrode active material under a pressure of 30000N is greater than or equal to 2.46 g / cm 3 , and can be optionally 2.46 g / cm 3 - 2.8 g / cm 3 .

[0201] In this application, the powder compaction density of the positive electrode active material has the well-known meaning in the art and can be measured by the instruments and methods known in the art. For example, it can be measured with reference to GB / T 24533-2009 through an electronic pressure testing machine (such as a UTM7305 type electronic pressure testing machine). An exemplary test method is as follows: Weigh 1g of the positive electrode active material powder, add it to a mold with a bottom area of 1.327 cm 2 , apply pressure up to 30000N, keep the pressure for 30s, then release the pressure, keep it for 10s, and then record and calculate the powder compaction density of the material under a pressure of 30000N.

[0202] In some embodiments, the powder compaction density of the positive electrode active material under a pressure of 30000N can be optionally 2.46 g / cm 3 , 2.47 g / cm 3 , 2.48 g / cm 3 , 2.49 g / cm 3 , 2.5 g / cm 3 , 2.55 g / cm 3, 2.6 g / cm 3 , 2.65 g / cm 3 , 2.7 g / cm 3 , 2.75 g / cm 3 , 2.8 g / cm 3 or a numerical range between any two of them.

[0203] In some embodiments, the volume average particle size of the positive electrode active material satisfies: 1 µm ≤ Dv50 正 ≤ 2 µm, 0.4 µm ≤ Dv10 正 ≤ 0.7 µm.

[0204] In some embodiments, the volume average particle size Dv50 of the positive electrode active material 正 can be optionally 1 µm, 1.1 µm, 1.2 µm, 1.3 µm, 1.4 µm, 1.5 µm, 1.6 µm, 1.7 µm, 1.8 µm, 1.9 µm, 2 µm or a numerical range between any two of them, and Dv10 正 can be optionally 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm or a numerical range between any two of them.

[0205] The volume average particle size Dv50 of the positive electrode active material 正、 Dv10 正 can adopt the same test method as the volume average particle size of the negative electrode active material above.

[0206] The above positive electrode active material effectively improves the tap density of the powder and the carrier conduction between the positive electrode active materials through the grading of large and small particles, which is beneficial to taking into account the energy density and fast charging performance of the battery cell.

[0207] In some embodiments, the powder resistivity R of the positive electrode active material ≤ 27.5 Ω•cm.

[0208] In the present application, the powder resistivity of the positive electrode active material has the meaning well-known in the art and can be measured by instruments and methods known in the art. For example, a powder resistivity tester (PRCD1100) can be used to analyze and test with reference to the standard GB / T30835-2014.

[0209] In some embodiments, the powder resistivity R of the positive electrode active material may be selected from 1 Ω•cm, 2 Ω•cm, 3 Ω•cm, 4 Ω•cm, 5 Ω•cm, 6 Ω•cm, 7 Ω•cm, 8 Ω•cm, 9 Ω•cm, 10 Ω•cm, 11 Ω•cm, 12 Ω•cm, 13 Ω•cm, 14 Ω•cm, 15 Ω•cm, 16 Ω•cm, 17 Ω•cm, 18 Ω•cm, 19 Ω•cm, 20 Ω•cm, 21 Ω•cm, 22 Ω•cm, 23 Ω•cm, 24 Ω•cm, 25 Ω•cm, 26 Ω•cm, 27 Ω•cm, 27.5 Ω•cm, or the numerical range between any two of them.

[0210] In some embodiments, the specific surface area S of the positive electrode active material is 5 m 2 / g ~ 18m 2 / g.

[0211] In the present application, the specific surface area of the positive electrode active material has the meaning well-known in the art and can be measured by instruments and methods known in the art. For example, it can be measured by the nitrogen adsorption specific surface area analysis test method with reference to GB / T 19587-2017 and calculated by the BET (Brunauer Emmett Teller) method. The test instrument can be the Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics, USA.

[0212] In some embodiments, the specific surface area S of the positive electrode active material may be selected from 5 m 2 / g, 6 m 2 / g, 7 m<s 2 / g, 8 m 2 / g, 9 m 2 / g, 10 m 2 / g, 11m 2 / g, 12m 2 / g, 13 m 2 / g, 14 m 2 / g, 15 m 2 / g, 16m 2 / g, 17 m 2 / g, 18m 2 / g or the numerical range between any two of them.

[0213] Both the powder resistivity and the specific surface area of the positive electrode active material are related to the ion conduction of the positive electrode active material.

[0214] The carbon structure in the positive electrode active layer has a high degree of correlation. The positive electrode active material with powder resistivity and specific surface area within the above ranges has both good ionic conductivity and electronic conductivity, which is beneficial to improving the fast charging performance of the battery cell.

[0215] In some embodiments, the positive electrode active layer includes a lithium supplement agent, and the lithium supplement agent includes at least one of a ternary lithium supplement material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and lithium citrate.

[0216] The lithium supplement agent generally refers to a material that decomposes and releases active lithium during the electrochemical process to make up for the irreversible loss of active lithium caused by the growth of the negative electrode SEI film. Adding a lithium supplement agent to the positive electrode active layer can offset the irreversible lithium loss during the electrochemical process to improve the total capacity and energy density of the battery cell.

[0217] The ternary lithium supplement material refers to an oxide lithium supplement agent including one or more of nickel, cobalt, and manganese. In some embodiments, the general formula of the ternary lithium supplement material is shown as Formula III,

[0218] Li x3 A y3 Ni a3 Co b3 Mn c3 M3 (1-a3-b3-c3) Y z3 , Formula III

[0219] where 0 ≤ x3 ≤ 2.1, 0 ≤ y3 ≤ 2.1, and 0.9 ≤ x3 + y3 ≤ 2.1; 0 ≤ a3 ≤ 1, 0 ≤ b3 ≤ 1, 0 ≤ c3 ≤ 1, and 0.1 ≤ a3 + b3 + c3 ≤ 1; 1.8 ≤ z3 ≤ 3.5; A includes one or several of Na, K, and Mg; M includes one or several of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y includes one or several of O and F.

[0220] In some embodiments, x3 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or a numerical range between any two of them; y3 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or a numerical range between any two of them; and x3 + y3 can be optionally 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or a numerical range between any two of them; a3 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; b3 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; c3 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; and a3 + b3 + c3 can be optionally 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; z3 can be optionally 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 or a numerical range between any two of them.

[0221] In some embodiments, the mass content ratio of the lithium supplementing agent added in the positive electrode active layer is 0.1% - 10%.

[0222] In some embodiments, the mass content ratio of the lithium supplementing agent added in the positive electrode active layer can be optionally 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a numerical range between any two of them.

[0223] The mass content ratio of the lithium supplementing agent added in the positive electrode active layer is calculated by dividing the added mass of the lithium supplementing agent by the total mass of the positive electrode active layer.

[0224] In some embodiments, the positive electrode tab includes a positive electrode conductive layer disposed between the positive electrode current collector and the positive electrode active layer, and the thickness of the positive electrode conductive layer is 0.5 µm to 2 µm; and / or the negative electrode tab includes a negative electrode conductive layer disposed between the negative electrode current collector and the negative electrode active layer, and the thickness of the negative electrode conductive layer is 0.5 µm to 2 µm.

[0225] In some embodiments, the thickness of the positive electrode conductive layer or the negative electrode conductive layer can be selected as 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1.0 µm, 1.1 µm, 1.2 µm, 1.3 µm, 1.4 µm, 1.5 µm, 1.6 µm, 1.7 µm, 1.8 µm, 1.9 µm, 2.0 µm or the numerical range between any two of them.

[0226] The setting of the positive electrode conductive layer and / or the negative electrode conductive layer is beneficial to improving the electronic conductivity of the battery single cell tab and beneficial to improving the energy density of the battery single cell.

[0227] In some embodiments, the positive electrode conductive layer includes a conductive agent and a first binder, the negative electrode conductive layer includes a conductive agent and a second binder, the conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Optionally, the conductive agent includes superconducting carbon and carbon nanotubes, the first binder includes a fluorine-containing binder, and the second binder includes a water-soluble binder.

[0228] In some embodiments, the fluorine-containing binder refers to a binder including fluorine element. As examples, it includes but is not limited to one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0229] In some embodiments, the water-soluble binder refers to a binder that can be dispersed in an aqueous medium. As examples, it includes but is not limited to styrene-butadiene rubber SBR, water-soluble unsaturated resin SR-1B, aqueous acrylic resin, polyvinyl alcohol, sodium alginate, carboxymethyl chitosan, etc.

[0230] In some embodiments, based on the total mass of the positive electrode conductive layer, the mass content of the conductive agent in the positive electrode conductive layer is 30% to 50%, and the mass content of the first binder is 50% to 70%; and / or based on the total mass of the negative electrode conductive layer, the mass content of the conductive agent in the negative electrode conductive layer is 20% to 40%, and the mass content of the second binder is 60% to 80%.

[0231] In some embodiments, based on the total mass of the positive electrode conductive layer, the mass content of the conductive agent in the positive electrode conductive layer is 30% to 50%, and the mass content of the first binder is 50% to 70%.

[0232] In some embodiments, based on the total mass of the positive electrode conductive layer, the mass content of the conductive agent in the positive electrode conductive layer can be selected from 30%, 35%, 40%, 45%, 50% or the numerical range between any two of them, and the mass content of the first binder can be selected from 50%, 55%, 60%, 65%, 70% or the numerical range between any two of them.

[0233] In some embodiments, based on the total mass of the negative electrode conductive layer, the mass content of the conductive agent in the negative electrode conductive layer is 20% to 40%, and the mass content of the second binder is 60% to 80%.

[0234] In some embodiments, based on the total mass of the negative electrode conductive layer, the mass content of the conductive agent in the negative electrode conductive layer can be selected from 20%, 25%, 30%, 35%, 40% or the numerical range between any two of them, and the mass content of the first binder can be selected from 60%, 65%, 70%, 75%, 80% or the numerical range between any two of them.

[0235] In some embodiments, the single-sided areal density of the negative electrode active layer is 104 mg / 1540.25 mm 2 -180 mg / 1540.25 mm 2 ; it can be selected as 125 mg / 1540.25 mm 2 -167 mg / 1540.25 mm 2 .

[0236] The single-sided areal density of the negative electrode active layer can be tested by a method similar to that of the positive electrode active layer described above.

[0237] In some embodiments, the areal density of the negative electrode active layer can be selected from 104 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 115 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 125 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm2 、167 mg / 1540.25 mm 2 、170 mg / 1540.25 mm 2 、180 mg / 1540.25 mm 2 or a numerical range between any two of them.

[0238] The negative electrode active layer with a single-sided areal density within the above range can cooperate with the positive electrode active layer to achieve a balance between the energy density and fast charging performance of the battery cell.

[0239] In some embodiments, when the battery cell is at 100% SOC, the tap density of the negative electrode active layer is 1.15 g / cm 3 ~1.36 g / cm 3 ; optionally 1.25 g / cm 3 ~1.36 g / cm 3 .

[0240] When the battery cell is at 100% SOC, the tap density of the negative electrode active layer can be tested with reference to the tap density of the positive electrode active layer of the battery cell described above. It can be understood that the tap density of the negative electrode active layer when the battery cell is at 100% SOC is different from the designed value of the tap density after cold pressing of the negative electrode active layer. During charge and discharge, with the insertion / extraction of lithium ions in the negative electrode active layer, the negative electrode active layer expands compared to after cold pressing, resulting in a decrease in the tap density of the negative electrode active layer when the battery cell is at 100% SOC compared to the tap density after cold pressing of the negative electrode active layer.

[0241] In some embodiments, when the battery cell is at 100% SOC, the tap density of the negative electrode active layer can be optionally 1.15 g / cm 3 、1.20 g / cm 3 、1.25 g / cm 3 、1.30 g / cm 3 、1.35 g / cm 3 、1.36 g / cm 3 or a numerical range between any two of them.

[0242] In some embodiments, the negative electrode active material includes graphite.

[0243] In some embodiments, the graphite includes composite graphite particles, the composite graphite particles include a body particle and a coating layer disposed at least partially on the surface of the body particle, the body particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0244] A secondary particle refers to a particle formed by the aggregation of two or more primary particles.

[0245] The composite graphite particles including secondary particles and the surface coating layer including amorphous carbon are both beneficial to the infiltration of the electrolyte in the negative electrode active layer of the electrode sheet, contributing to the improvement of the rate performance of the battery cell.

[0246] In some embodiments, the composite graphite material further includes kinetic carbon material.

[0247] In some embodiments, the kinetic carbon material is located between the primary particles of the body particles. At this time, the body particles of the negative electrode active material include artificial graphite primary particles and the kinetic carbon material located between the primary particles.

[0248] In some embodiments, the kinetic carbon material is located in the coating layer. At this time, the coating layer includes both amorphous carbon and kinetic carbon material.

[0249] In some embodiments, the raw material of the kinetic carbon material includes one or more of hard carbon, expanded graphite, and graphene.

[0250] In this article, the "raw material of the kinetic carbon material" and the "powder of the raw material of the kinetic carbon material" are completely consistent in composition. The "kinetic carbon material" refers to the product obtained by graphitization treatment and / or carbonization treatment of the "raw material of the kinetic carbon material".

[0251] In some embodiments, the layer spacing d002 of the (002) crystal plane of the raw material of the kinetic carbon material is ≥ 0.3358 nm, and optionally is 0.3359 nm to 0.3366 nm.

[0252] The layer spacing of the raw material of the kinetic carbon material is larger than that of conventional graphite (the layer spacing of conventional graphite is 0.335 nm). When the kinetic carbon material obtained therefrom is uniformly distributed in the body particles and / or the coating layer of the composite graphite material, it is beneficial to the rapid insertion and extraction of active ions, thereby improving the transport performance of active ions and electrons, further improving the fast charging performance of the battery cell, and not causing a large loss of the energy density of the battery cell, achieving the balance between the fast charging performance and the energy density of the battery cell.

[0253] In some embodiments, based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5%.

[0254] In some embodiments, based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles can be optionally 2%, 3%, 4%, 5% or the numerical range between any two of them.

[0255] When the content of amorphous carbon is within a suitable range, the composite graphite material can have a high specific capacity while also having a high active ion solid-phase transport ability, which is beneficial to improving the fast charging performance of a single battery cell.

[0256] In some embodiments, the powder resistivity of the negative electrode active material is less than or equal to 0.04 Ω•cm.

[0257] In some embodiments, the powder resistivity of the negative electrode active material can be selected as 0.01 Ω•cm, 0.02 Ω•cm, 0.03 Ω•cm, 0.04 Ω•cm or the numerical range between any two of them.

[0258] The powder resistivity of the negative electrode active material can be obtained by testing through any well-known method in the art. As an example, it can be tested with reference to the powder resistivity testing method of the positive electrode active material described above.

[0259] In some embodiments, the powder compaction density of the negative electrode active material under a pressure of 20000 N is 1.5 g / cm 3 to 1.7 g / cm 3 , and can be selected as 1.55 g / cm 3 to 1.65 g / cm 3 .

[0260] The powder compaction density of the negative electrode active material under a pressure of 20000 N can be tested by any well-known method in the art. As an example, it can be measured with known instruments and methods in the art. For example, it can be measured with reference to GB / T 24533-2009 through an electronic pressure testing machine (such as a UTM7305 type electronic pressure testing machine). The exemplary testing method is as follows: Weigh 1 g of the negative electrode active material powder, add it to a mold with a bottom area of 1.327 cm 2 , apply pressure up to 20000 N, keep the pressure for 30 s, then release the pressure, keep it for 10 s, and then record and calculate the powder compaction density of the material under a pressure of 20000 N.

[0261] In some embodiments, the powder compaction density of the negative electrode active material under a pressure of 20000 N can be selected as 1.5 g / cm 3 , 1.55 g / cm 3 , 1.6 g / cm 3 , 1.65 g / cm 3 , 1.7 g / cm 3 or the numerical range between any two of them.

[0262] The anode active material with a powder compaction density within a suitable range can endow the anode active layer with a high compaction density, thereby enabling the battery cell to have a high energy density. Meanwhile, during the cycling process, the original pore structure of the anode active layer can be maintained, which is conducive to improving the retention of the high fast-charging performance of the battery cell during cycling.

[0263] In some embodiments, the anode active material further includes a silicon-based material, which includes at least one of silicon, silicon oxides, and silicon-carbon composites. Based on the total mass of the anode active material, the mass content of silicon element in the silicon-based material is 0.3% to 10%, and optionally 1% to 6%.

[0264] In some embodiments, based on the total mass of the anode active material, the mass content of silicon element in the silicon-based material can be optionally 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value range between any two of them.

[0265] The introduction of the silicon-based material is beneficial to improving the energy density of the battery cell. The silicon-based material within the above mass range can balance the energy density and cycling stability of the battery cell.

[0266] In some embodiments, the charging specific capacity of the anode active material is 350 mAh / g to 480 mAh / g.

[0267] The charging specific capacity of the anode active material can be tested by well-known testing methods. As an example, the testing method for the first Coulomb efficiency and the first discharge specific capacity in Appendix G of National Standard GB / T 24533-2019 can be adopted. Disassemble the battery cell to obtain the anode electrode sheet, use a lithium metal sheet as the counter electrode, a polyethylene film as the separator, and the electrolyte in the battery cell as the electrolyte of the coin cell, and assemble it into a CR2430 type coin cell in a glove box under argon protection. After standing the obtained coin cell for 12 hours, at 25°C, discharge it at a constant current of 0.05C to 0.005V, stand for 10 minutes, then discharge it at a constant current of 50 μA to 0.005V, stand for 10 minutes, and then discharge it at a constant current of 10 μA to 0.005V; then charge it at a constant current of 0.1C to 2V, and record the charging capacity. The ratio of the charging capacity to the mass of the anode active material is the specific capacity of this material.

[0268] In some embodiments, the charging specific capacity of the negative electrode active material is 350 mAh / g, 360 mAh / g, 370 mAh / g, 380 mAh / g, 390 mAh / g, 400 mAh / g, 410 mAh / g, 420 mAh / g, 430 mAh / g, 440 mAh / g, 450 mAh / g, 460 mAh / g, 470 mAh / g, 480 mAh / g, or a numerical range between any two of them.

[0269] The negative electrode active material with a charging specific capacity within the above range is beneficial to improving the energy density of the battery cell.

[0270] In some embodiments, the negative electrode active layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, and the second negative electrode active material layer includes composite graphite particles.

[0271] In some embodiments, the first negative electrode active material layer includes one or more of composite graphite particles and natural graphite.

[0272] The composite graphite particles are disposed close to the electrolyte side, which can take into account the energy density while improving the fast charging performance of the battery cell.

[0273] In some embodiments, the ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer is from 3:7 to 7:3.

[0274] In some embodiments, the ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer can be selected as 3:7, 4:7, 5:7, 6:7, 1:1, 2:1, 7:3, or a numerical range between any two of them.

[0275] In some embodiments, the volume average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 µm to 18.5 µm, and can be selected as 9.5 µm to 14.8 µm.

[0276] In some embodiments, the volume average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer can be selected as 9.5 µm, 9.8 µm, 10 µm, 10.8 µm, 11 µm, 11.8 µm, 12 µm, 12.8 µm, 13 µm, 13.8 µm, 14 µm, 14.8 µm, 15 µm, 15.8 µm, 16 µm, 16.8 µm, 17 µm, 17.8 µm, 18 µm, 18.5 µm, or a numerical range between any two of them.

[0277] In some embodiments, the volume average particle size Dv502 of the negative electrode active material in the second negative electrode active layer is 7.8 µm to 14.3 µm, and may be optionally 7.8 µm to 12.8 µm.

[0278] In some embodiments, the volume average particle size Dv502 of the negative electrode active material in the second negative electrode active material layer may be optionally 7.8 µm, 8 µm, 8.8 µm, 9 µm, 9.8 µm, 10 µm, 10.8 µm, 11 µm, 11.8 µm, 12 µm, 12.8 µm, 13 µm, 13.8 µm, 14 µm, 14.3 µm or the numerical range between any two of them.

[0279] The volume average particle sizes Dv501 and Dv502 of the negative electrode active material in the first negative electrode active material layer and the second negative electrode active material layer can be tested with reference to the test method of the volume average particle size described above.

[0280] The second negative electrode active material layer provided on the electrolyte side includes negative electrode active material with a smaller particle size, which can further improve the solid-liquid transport rate of ions in the battery electrode sheet and improve the fast charging performance of the battery cell.

[0281] In some embodiments, the battery cell further includes a separator, the separator includes a porous base film and a functional layer provided on at least one side of the porous base film, and the thickness of the porous base film is less than or equal to 12 µm, and may be optionally less than or equal to 9 µm.

[0282] In some embodiments, the porous base film includes one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The porous base film may be a single-layer film or a multi-layer composite film, and there is no particular limitation.

[0283] In some embodiments, the porosity of the porous base film in the separator is 20% - 70%, and may be optionally 35% - 60%.

[0284] In some embodiments, the porosity of the porous base film in the separator may be optionally 20%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or the numerical range between any two of them.

[0285] In some embodiments, the functional layer includes a first functional layer provided on the negative electrode side of the porous base film and a second functional layer provided on the positive electrode side of the porous base film. The first functional layer includes first inorganic particles, the second functional layer includes composite particles, the composite particles include second inorganic particles and non-fluoropolymer particles, and the second inorganic particles in the composite particles adhere to the surface of the non-fluoropolymer particles and / or are dispersed inside the non-fluoropolymer particles.

[0286] In some embodiments, the inorganic particles include one or more of silica, alumina, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide.

[0287] The inorganic particles can improve the heat resistance of the first functional layer and the second functional layer, and improve the fast charging performance of the battery cell.

[0288] In some embodiments, the non-fluoropolymer particles include acrylate copolymers.

[0289] In some embodiments, the liquid injection coefficient of the battery cell is 2.4 g / Ah - 3.1 g / Ah.

[0290] The liquid injection coefficient of the battery cell refers to the ratio of the mass of the electrolyte inside the battery cell to the battery capacity. The liquid injection coefficient of the battery cell can be measured by any well-known method in the art. Exemplarily, the mass of the electrolyte in the battery cell can be measured by the following method: Weigh the battery, and record the mass as M0. Disassemble the battery cell and pour out the free electrolyte. Take out the internal electrode assembly and separate the positive electrode plate, negative electrode plate, separator, and mechanical parts. Immerse and clean the positive electrode plate, negative electrode plate, separator, and mechanical parts with dimethyl carbonate (DMC) solvent for 24 h to 48 h, and soak repeatedly for more than 3 times. Place the aforementioned positive electrode plate, negative electrode plate, separator, and mechanical parts in an oven at 100°C for more than 24 h until completely dried. Weigh the dried positive electrode plate, negative electrode plate, separator, and mechanical parts, and record the mass as M1. Thus, the mass of the electrolyte in the battery cell is (M0 - M1). The liquid injection coefficient is calculated by (M0 - M1) / the rated capacity of the battery cell. The rated capacity is the battery nominal capacity, or charge at a charging rate of 0.33C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C, stand for 10 min, and then discharge at a discharge rate of 0.33C to 2.0V, and use the discharge capacity of the battery cell as the rated capacity.

[0291] In some embodiments, the liquid injection coefficient of the battery cell can be selected as 2.4 g / Ah, 2.5 g / Ah, 2.6 g / Ah, 2.7 g / Ah, 2.8 g / Ah, 2.9 g / Ah, 3.0 g / Ah, 3.1 g / Ah, or any value range between any two of them. [[ID=-17]]

[0292] The liquid injection coefficient within the above range can improve the cycle stability of the battery cell.

[0293] In some embodiments, the battery cell further includes electrode terminals, the electrode assembly includes tab portions, and the tab portions are directly welded to the electrode terminals.

[0294] In some embodiments, the time for the battery cell to be charged from 10% state of charge (SOC) to 80% state of charge (SOC) at 30 °C is 6 min to 15 min.

[0295] The time for the battery cell to be charged from 10% state of charge (SOC) to 80% state of charge (SOC) at 30 °C can be obtained by testing in any well-known manner in the art. As an example, at 30 °C, charge the battery from 10% SOC. Charge from 10% SOC to 15% SOC at a constant current of 5.0 C, charge from 15% SOC to 20% SOC at a constant current of 5.0 C, charge from 20% SOC to 25% SOC at a constant current of 5.0 C, charge from 25% SOC to 30% SOC at a constant current of 5.0 C, charge from 30% SOC to 35% SOC at a constant current of 5.0 C, charge from 35% SOC to 40% SOC at a constant current of 5.0 C, charge from 40% SOC to 45% SOC at a constant current of 4.6 C, charge from 45% SOC to 50% SOC at a constant current of 4.3 C, charge from 50% SOC to 55% SOC at a constant current of 4.0 C, charge from 55% SOC to 60% SOC at a constant current of 3.7 C, charge from 60% SOC to 65% SOC at a constant current of 3.4 C, charge from 65% SOC to 70% SOC at a constant current of 3.1 C, charge from 70% SOC to 75% SOC at a constant current of 2.9 C, charge from 75% SOC to 80% SOC at a constant current of 2.7 C, and record the total charging time.

[0296] In some embodiments, the time for the battery cell to be charged from 10% state of charge (SOC) to 80% state of charge (SOC) at 30 °C can be selected as 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min or any numerical range between any two of them.

[0297] The battery cell has good fast charging performance and can meet the demand for improving the energy replenishment efficiency of the electrical device.

[0298] In some embodiments, the battery cell has a wound structure, the thickness of the positive current collector is less than or equal to 15 µm, and the thickness of the negative current collector is less than or equal to 6 µm.

[0299] The material of the positive current collector and / or the negative current collector is not particularly limited as long as it does not cause chemical changes in the battery cell and has electrical conductivity. The current collector includes a metal foil with a pure metal content of more than 95%, such as at least one of copper foil, aluminum foil, stainless steel foil, titanium foil, and nickel foil. It also includes an alloy foil of at least two main metals. For example, an alloy foil made of at least two main elements among copper, aluminum, nickel, titanium, and iron can be used. It can also include copper, aluminum cadmium alloy, iron, or stainless steel, etc. surface-treated with carbon, nickel, titanium, silver, copper, etc. In addition, the bonding force with the negative active material can be enhanced by forming micro-concavities and protrusions on the surface, and it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabrics, etc.

[0300] In some embodiments, the thickness of the positive current collector can be selected as 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, or the numerical range between any two of them.

[0301] In some embodiments, the thickness of the negative current collector can be selected as 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, or the numerical range between any two of them.

[0302] The positive current collector and / or the negative current collector have a lower thickness, enabling further improvement in the energy density of the battery cell.

[0303] In some embodiments, the volumetric energy density of the battery cell is 400 Wh / L to 500 Wh / L.

[0304] In some embodiments, the volumetric energy density of the battery cell can be selected as 400 Wh / L, 410 Wh / L, 420 Wh / L, 430 Wh / L, 440 Wh / L, 450 Wh / L, 460 Wh / L, 470 Wh / L, 480 Wh / L, 490 Wh / L, 500 Wh / L, or the numerical range between any two of them.

[0305] The volumetric energy density of the battery cell can be tested by any well-known method in the art. As an example, the battery cell is placed at 25 °C, charged at a constant current of 0.33C to 3.65V, then charged at a constant voltage to 0.05C, and discharged at a constant current of 0.33C to 2.0V. Record the discharge capacity A0 at this time, unit: Ah. Use a caliper to measure the length, width, and height of the battery cell (generally calculated based on the outer shell size of the battery, excluding the height of the electrode terminals and excluding the insulating film outside the shell), calculate the volume V0 of the single battery cell, unit: L. The volumetric energy density VED of the battery cell = (A0 × discharge platform voltage) / V0, unit: Wh / L.

[0306] The battery cell simultaneously has a high energy density and can meet the demand for increasing the cruising range of the electrical device.

[0307] In some embodiments, the battery cell may include an outer package. The outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0308] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0309] This application does not particularly limit the shape of the battery cell, and it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 is a battery cell 5 with a square structure as an example.

[0310] In some embodiments, referring to Figure 2 , the outer package may include a housing 51 and a top cover assembly 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0311] In some embodiments, the battery cells can be assembled into a battery module. The number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0312] Figure 3 is a battery module 4 as an example. Referring to Figure 3 , in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0313] Optionally, the battery module 4 can further include a housing with a receiving space, and a plurality of battery cells 5 are received in the receiving space.

[0314] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack. The number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0315] Figure 4 and Figure 5 is the battery pack 1 as an example. Referring to Figure 4 and Figure 5 In the battery pack 1, a battery box and a plurality of battery modules 4 disposed in the battery box may be included. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0316] The second aspect of the present application provides a battery device, including the battery cell provided in the first aspect of the present application. The battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0317] In addition, the third aspect of the present application further provides an electrical device, and the electrical device includes the battery cell provided in the first aspect of the present application. The battery cell, battery module or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0318] As the electrical device, a battery cell, battery module or battery pack can be selected according to its usage requirements.

[0319] Figure 6 is an example electrical device. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the battery cell, a battery pack or a battery module can be adopted.

[0320] Another example device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thinness and lightness, and a battery cell can be used as the power source.

[0321] Embodiment

[0322] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following will further elaborate on this application in combination with embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of them. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on this application and its applications. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0323] For those not specifying specific techniques or conditions in the embodiments, follow the techniques or conditions described in the literature in this field or according to the product specifications. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0324] Example 1

[0325] Preparation of the positive electrode plate

[0326] Mix the positive electrode active material lithium iron phosphate, the binder polyvinylidene fluoride, and the conductive agent acetylene black in a ratio of 97:2:1, and then add the solvent N-methylpyrrolidone (NMP) and stir to form a positive electrode slurry; among them, the tap density of the powder of the positive electrode active material is 2.53 g / cm 3 , the volume average particle size Dv50 of the positive electrode active material 正 is 1.6 µm, and Dv10 正 is 0.64 µm.

[0327] The positive electrode conductive layer is formed by uniformly mixing conductive carbon SP, the binder polyvinylidene fluoride (PVDF), and the solvent NMP and coating it on the surface of the current collector, with a thickness of 1 µm.

[0328] Uniformly coat the positive electrode conductive slurry on the positive electrode current collector aluminum foil with a thickness of 13 µm, and obtain the positive electrode conductive layer after drying; then uniformly coat the positive electrode slurry on the positive electrode conductive layer, and obtain the positive electrode plate after drying and cold pressing. Among them, the areal density of the positive electrode active layer of the positive electrode plate is 300 mg / 1540.25 mm 2 , and when the battery is charged at a charging rate of 0.33C to 100% SOC, the tap density of the positive electrode plate is 2.63 g / cm 3 ;

[0329] Preparation of the negative electrode plate

[0330] The negative electrode active material graphite, conductive agent acetylene black, binder styrene butadiene rubber, and thickener sodium carboxymethyl cellulose were mixed in a mass ratio of 96:1:2:1, and then deionized water was added as a solvent and stirred to form a negative electrode slurry. The negative electrode slurry was evenly coated on the negative electrode current collector copper foil, dried, and cold pressed to obtain a negative electrode sheet; the thickness of the negative electrode current collector copper foil was 4.5µm. The surface density of the negative electrode active layer of the negative electrode sheet was 138mg / 1540.25mm 2 The battery is charged at a charge rate of 0.33C to 100% SOC, and the compaction density of the negative electrode is 1.26g / cm 3 , the volume distribution particle size Dv50 of the negative electrode active material is 10.5 μm;

[0331] Electrolyte preparation

[0332] In an argon atmosphere glove box with a water content of less than 10 ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and ethyl acetate (EA) were thoroughly mixed in a mass ratio of 35:15:50 to prepare the electrolyte solvent. Lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) were slowly added as lithium salts and stirred thoroughly until completely dissolved. After returning to room temperature, the additives vinyl carbonate (VC), fluoroethylene carbonate (FEC), 1%, 1,3-propene sultone (PS), 0.5%, vinyl sulfite (DTD), and 0.5% lithium difluorophosphate (LiPO2F2) were added in sequence, with the weight percentages relative to the total weight of the electrolyte being 3.5%, respectively. The electrolyte was then thoroughly mixed to obtain the electrolyte. Based on the total weight of the electrolyte, lithium hexafluorophosphate (LiPF6) accounted for 10.5% by weight, and lithium bis(fluorosulfonyl)imide (LiFSI) accounted for 4.5% by weight. The electrolyte conductivity was 15.4 mS / cm.

[0333] Preparation of isolation membrane

[0334] The isolation film includes a base film, which is a 7 μm polyethylene film layer with a porosity of 42%.

[0335] Preparation of battery cells

[0336] The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to form a wound electrode assembly. The electrode assembly is placed in a square aluminum casing, dried, and then filled with electrolyte. After packaging, standing, formation, aging, secondary packaging, and capacity testing, a battery cell is obtained. The battery cell has a liquid retention coefficient (d3 / A) of 2.9 g / Ah.

[0337] The preparation methods of Examples 2-12 are basically the same as those of Example 1, except that some parameters in the battery cells are adjusted, as shown in Table 1.

[0338] Example 13

[0339] The battery preparation method of Example 13 is basically the same as that of Example 1, except that the negative electrode sheet in Example 13 is double-coated. The specific preparation method of the negative electrode sheet is as follows:

[0340] Mix the negative electrode active material, the first graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber, and the thickening agent sodium carboxymethyl cellulose in a mass ratio of 96:0.5:2.5:1, and then add the solvent deionized water and stir evenly to form the first negative electrode slurry.

[0341] Mix the negative electrode active material, the second graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber, and the thickening agent sodium carboxymethyl cellulose in a mass ratio of 96:0.5:2.5:1, and then add the solvent deionized water and stir evenly to form the second negative electrode slurry.

[0342] Coat the first negative electrode slurry evenly on the negative electrode conductive layer of the negative electrode current collector copper foil and dry it; coat the second negative electrode slurry on the surface of the dried first negative electrode slurry, and after drying and cold pressing, obtain the negative electrode sheet. The negative electrode sheet includes a negative electrode current collector and a negative electrode conductive layer and a negative electrode active material layer provided on the negative electrode current collector in sequence. The negative electrode active material layer includes a first negative electrode active layer and a second negative electrode active layer provided on the negative electrode conductive layer in sequence.

[0343] Among them, based on the total mass of the negative electrode active material layer, the single-sided coating mass of the negative electrode sheet is 138 mg / mm 2 ; when the battery is charged at a charging rate of 0.33C to 100% SOC, the compaction density of the positive electrode sheet is 1.25 g / cm 3 ; based on the total mass of the first graphite and the second graphite in the negative electrode active material layer, the mass ratios of the first graphite and the second graphite are 50% and 50% respectively.

[0344] The preparation methods of Comparative Examples 1-6 are basically the same as those of Example 1, except that some parameters in the battery monomer are adjusted.

[0345] Test method

[0346] (1) The test steps for the time T of the battery monomer to be charged from 10% SOC to 80% SOC at 30 °C are as follows:

[0347] At an ambient temperature of 30 °C, charge the battery from the 10% SOC state,

[0348] Charge at a constant current of 5.0C from 10% SOC to 15% SOC;

[0349] Charge at a constant current of 5.0C from 15% SOC to 20% SOC;

[0350] Charge at a constant current of 5.0C from 20% SOC to 25% SOC;

[0351] Charge from 25% SOC to 30% SOC at a constant current of 5.0C;

[0352] Charge from 30% SOC to 35% SOC at a constant current of 5.0C;

[0353] Charge from 35% SOC to 40% SOC at a constant current of 5.0C;

[0354] Charge from 40% SOC to 45% SOC at a constant current of 4.6C;

[0355] Charge from 45% SOC to 50% SOC at a constant current of 4.3C;

[0356] Charge from 50% SOC to 55% SOC at a constant current of 4.0C;

[0357] Charge from 55% SOC to 60% SOC at a constant current of 3.7C;

[0358] Charge from 60% SOC to 65% SOC at a constant current of 3.4C;

[0359] Charge from 65% SOC to 70% SOC at a constant current of 3.1C;

[0360] Charge from 70% SOC to 75% SOC at a constant current of 2.9C;

[0361] Charge from 75% SOC to 80% SOC at a constant current of 2.7C;

[0362] Record the total charging time. The time for different embodiments is different and can be achieved by slightly adjusting the charging rate.

[0363] (2) Number of cycles from 60°C to 80% SOH

[0364] At 60°C, charge at a charging rate of 1C of the battery nominal capacity to 3.65V, then charge at a constant voltage of 3.65V to 0.05C, stand still for 10 min, then discharge at a discharge rate of 1C to 2.5V, stand still for 10 min. The above one charge and discharge is one cycle. Stop the test until the battery capacity decays to 80% of the initial discharge capacity, and record it as the number of cycles @80% SOH.

[0365] (3) DC internal resistance DCR test of battery cells:

[0366] The method in GB / T 31467 "Performance Test Specification for High-power Lithium-ion Power Batteries for HEV" can be referred to.

[0367] For example, at room temperature, the battery cell is charged at a constant current of 0.33 C to 3.65 V, left standing for 1 min, then charged at a constant current of 0.1 C to 3.65 V, left standing for 30 min, and discharged at a constant current of 0.33 C to 2.0 V. Record the discharge capacity A0 at this time, with the unit of Ah. Then charge at a constant current of 0.33 C for 0.5A0 Ah and adjust the SOC to 50%.

[0368] After leaving the battery cell at -20 °C for 2 h, discharge it at a constant current of 4 C for 10 s and record ∆U 放电 、∆I 放电 . The discharge DCR data of the lithium-ion battery is calculated through the following formula, R 放电 =∆U 放电 / ∆I 放电 ,

[0369] wherein, ∆U 放电 represents the voltage change within 10 s at the start of discharge, and ∆I 放电 represents the current value within 10 s at the start of discharge. Some parameters of each example and comparative example are shown in Table 1, where the contents are all mass contents, and the unit of the single-sided coating mass of the positive electrode and the negative electrode is mg / 1540.25 mm 2 .

[0370] In Example 1, when the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is 2.63 g / cm 3 ; when the battery cell is at 100% SOC, the compaction density of the negative electrode active layer is 1.26 g / cm 3 .

[0371] The test results of each example and comparative example are shown in Tables 2 and 3

[0372] Table 1

[0373]

[0374] Table 2

[0375]

[0376] Table 3

[0377]

[0378] Test results

[0379] From the comparison between the examples and comparative examples of the present application, it can be seen that the positive electrode active layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and the single-sided areal density of the positive electrode active layer is 230 mg / 1540.25 mm2 ~400 mg / 1540.25 mm 2 ; The electrolyte includes a solvent and a lithium-containing electrolyte salt. The solvent includes a chain carboxylic acid ester and ethylene carbonate. The lithium-containing electrolyte salt includes one or more of lithium hexafluorophosphate and fluorosulfonylimide salt; wherein, for the battery cell with the mass ratio of the lithium-containing electrolyte salt to ethylene carbonate being 0.29 - 0.72, the conductivity of the electrolyte is 13 mS / cm - 20 mS / cm, which can take into account the energy density and fast charging performance of the battery cell and achieve the comprehensive improvement of the battery performance.

[0380] As can be seen from the comparison between Example 1 and Examples 6 - 7, based on the total mass of the electrolyte, the battery cell with the mass content ratio of the chain carboxylic acid ester being 25.5% - 63.75% can further take into account the cycle stability and improve the comprehensive performance of the battery cell.

[0381] It should be noted that the present disclosure is not limited to the above embodiments. The above embodiments are only examples, and the embodiments with the same structure and the same effect as the technical idea within the scope of the technical solution of the present disclosure are all included in the technical scope of the present disclosure. In addition, within the scope of not departing from the gist of the present disclosure, various modifications that can be thought of by those skilled in the art to the embodiments and other ways constructed by combining some of the constituent elements of the embodiments are also included in the scope of the present disclosure.

Claims

1. A battery cell, characterized in that, It includes a positive electrode sheet and an electrolyte solution; The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer located on at least one surface of the positive electrode current collector. The positive electrode active layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing phosphate, and the single-sided areal density of the positive electrode active layer is 230 mg / 1540.25mm 2 ~400mg / 1540.25mm 2 ; The electrolyte solution contains a solvent and a lithium-containing electrolyte salt. The solvent includes a chain carboxylic acid ester and ethylene carbonate. The lithium-containing electrolyte salt includes one or more of lithium hexafluorophosphate and fluorosulfonylimide salt; wherein the mass ratio of the lithium-containing electrolyte salt to ethylene carbonate is 0.29 - 0.72; The conductivity of the electrolyte solution is 13 mS / cm - 20 mS / cm.

2. The battery cell according to claim 1, characterized in that In the electrolyte solution, the mass ratio of ethylene carbonate to the chain carboxylic acid ester is (0.26 - 1):

1.

3. The battery cell according to claim 1, wherein Based on the total mass of the electrolyte solution, the mass content ratio of the chain carboxylic acid ester is 25.5% - 63.75%.

4. The battery cell according to claim 1, characterized in that The chain carboxylic acid ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include one or more of C1~C5 alkyl groups and C1~C5 haloalkyl groups.

5. The battery cell according to claim 1, characterized in that, The chain carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

6. The battery cell according to claim 1, characterized in that, Based on the total mass of the electrolyte solution, the mass content ratio of ethylene carbonate is 17% - 34%.

7. The battery cell according to claim 1, wherein The lithium-containing electrolyte salt includes lithium hexafluorophosphate.

8. The battery cell according to claim 7, characterized in that, The lithium-containing electrolyte salt also includes a fluorosulfonylimide salt.

9. The battery cell according to claim 8, wherein The fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide.

10. The battery cell according to claim 1, characterized in that, The lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate in the electrolyte solution is (2 - 5):

10.

11. The battery cell according to claim 1, characterized in that, The battery cell further includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector, the negative electrode active layer includes a negative electrode active material, and the volume distribution particle size Dv10 of the negative electrode active material 负 is 3.5 μm - 7.5 μm; Dv99 负 is 25 μm - 35 μm.

12. The battery cell according to claim 11, characterized in that, The volume-based particle size Dv10 of the negative electrode active material 负 is 4.5 μm - 6.5 μm.

13. The battery cell according to claim 1, characterized in that, The electrolyte solution also contains an additive. The additive contains at least one of a carbonate additive, a sulfur-containing additive, and a lithium salt additive. The lithium salt additive includes one or more of lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, and lithium bis(oxalato)borate.

14. The battery cell according to claim 13, wherein The additive contains at least two of a carbonate additive, a sulfur-containing additive, and a lithium salt additive.

15. The battery cell according to claim 13, characterized in that, Based on the total mass of the electrolyte solution, the mass ratio of the additive in the electrolyte solution is 1% to 10%.

16. The battery cell according to claim 13, wherein, Based on the total mass of the electrolyte solution, the mass ratio of the additive in the electrolyte solution is 2% - 8%.

17. The battery cell according to claim 13, wherein, Based on the total mass of the electrolyte solution, the mass ratio of the additive in the electrolyte solution is 3.5 - 8%.

18. The battery cell according to claim 13, wherein, The carbonate additive includes one or more of vinylene carbonate and fluoroethylene carbonate.

19. The battery cell according to claim 13, characterized in that, The sulfur-containing additive includes one or more of ethylene sulfate, bis(ethylene sulfate), butene sulfite, 1,3-propane sultone, ethylene sulfite, and methylene bis(methanesulfonate).

20. The battery cell according to claim 13, wherein The additive includes vinylene carbonate; based on the total mass of the electrolyte solution, the mass content ratio of vinylene carbonate in the electrolyte solution is 0.5% to 9%.

21. The battery cell according to claim 20, wherein Based on the total mass of the electrolyte solution, the mass content ratio of vinylene carbonate in the electrolyte solution is 2% - 6%.

22. The battery cell according to claim 13, wherein, The additive includes fluoroethylene carbonate; based on the total mass of the electrolyte solution, the mass content ratio of fluoroethylene carbonate in the electrolyte solution is 0.1% to 4%.

23. The battery cell according to claim 22, characterized in that, Based on the total mass of the electrolyte, the mass content of vinylene fluoride carbonate in the electrolyte accounts for 0.5% - 3%.

24. The battery cell according to claim 1, wherein The electrolyte includes vinylene carbonate and vinylene fluoride carbonate, and the mass ratio of the total mass of vinylene carbonate and vinylene fluoride carbonate to the mass of the chain carboxylic acid ester is 0.008 - 0.

5.

25. The battery cell according to claim 1, characterized in that, The conductivity of the electrolyte is 14 mS / cm - 20 mS / cm.

26. The battery cell according to claim 1, characterized in that, The conductivity of the electrolyte is 15 mS / cm - 20 mS / cm.

27. The battery cell according to claim 1, characterized in that, The single-sided density of the positive electrode active layer is 280 mg / 1540.25 mm 2 - 370 mg / 1540.25 mm 2 .

28. The battery cell according to claim 1, characterized in that When the battery cell is at 100% SOC, the compaction density of the positive electrode active layer is 2.50 g / cm 3 ~2.80 g / cm 3 .

29. The battery cell according to claim 1, wherein, When the battery cell is at 100% SOC, the tap density of the positive electrode active layer is 2.55 g / cm 3 ~2.68 g / cm 3 .

30. The battery cell according to claim 1, wherein The lithium-containing phosphate is a lithium-containing phosphate with an olivine structure, including the components shown in Formula I, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I wherein, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.7 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, and 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

31. The battery cell according to claim 30, wherein, The positive electrode active material further includes an ion-conducting layer disposed on the surface of the lithium-containing phosphate, and the ion-conducting layer includes carbon. Based on the total mass of the positive electrode active material, the mass percentage of carbon is 1% - 2%.

32. The battery cell according to claim 31, wherein The ion-conducting layer further contains a fast ion conductor having a NASICON structure shown in Formula II, Li 3-b2 Fe 2-b2 M2 b2 (PO x2 ) y2 Formula II In Formula II, M2 is selected from one or more of +4-valent Ti, Zr, Hf, Ge, and Sn, 0 ≤ b2 ≤ 1, 3 ≤ x2 ≤ 5, and 2 ≤ y2 ≤ 4.

33. The battery cell according to claim 32, characterized in that, The fast ion conductor includes one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, and Li2FeSn(PO4)3.

34. The battery cell according to claim 1, characterized in that, The positive electrode active material satisfies at least one of the following conditions: (1) The powder tap density of the positive electrode active material under a pressure of 30,000 N is greater than or equal to 2.46 g / cm 3 ; (2) The volume average particle size of the positive electrode active material satisfies: 1 µm ≤ Dv50 正 ≤ 2 µm, 0.4 µm ≤ Dv10 正 ≤ 0.7 µm; (3) The powder resistivity R of the positive electrode active material ≤ 27.5 Ω•cm; (4) The specific surface area S of the positive electrode active material is 5 m 2 / g - 18 m 2 / g.

35. The battery cell according to claim 34, wherein, The powder tap density of the positive electrode active material under a pressure of 30,000 N is 2.46 g / cm 3 -2.8 g / cm 3 .

36. The battery cell according to claim 1, characterized in that, The positive electrode active layer includes a lithium supplement agent, and the lithium supplement agent includes at least one of a ternary lithium supplement material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and lithium citrate.

37. The battery cell according to claim 36, wherein, The general formula of the ternary lithium supplement material is shown in Formula III, Li x3 A y3 Ni a3 Co b3 Mn c3 M3 (1-a3-b3-c3) Y z3 , formula III Among them, 0 ≤ x3 ≤ 2.1, 0 ≤ y3 ≤ 2.1, and 0.9 ≤ x3 + y3 ≤ 2.1; 0 ≤ a3 ≤ 1, 0 ≤ b3 ≤ 1, 0 ≤ c3 ≤ 1, and 0.1 ≤ a3 + b3 + c3 ≤ 1; 1.8 ≤ z3 ≤ 3.5; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y includes one or more of O and F.

38. The battery cell according to claim 36, wherein, The mass content ratio of the lithium supplement in the positive electrode active layer is 0.1% to 10%.

39. The battery cell according to claim 1, wherein The positive electrode tab includes a positive electrode conductive layer, the positive electrode conductive layer is disposed between the positive electrode current collector and the positive electrode active layer, and the thickness of the positive electrode conductive layer is 0.5 µm to 2 µm; and / or, the battery cell includes a negative electrode tab, the negative electrode tab includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector, the negative electrode tab further includes a negative electrode conductive layer, the negative electrode conductive layer is disposed between the negative electrode current collector and the negative electrode active layer, and the thickness of the negative electrode conductive layer is 0.5 µm to 2 µm.

40. The battery cell according to claim 39, wherein, The positive electrode conductive layer includes a conductive agent and a first binder, the negative electrode conductive layer includes a conductive agent and a second binder, and the conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

41. The battery cell according to claim 40, wherein, The conductive agent includes superconducting carbon and carbon nanotubes, the first binder includes a fluorine-containing binder, and the second binder includes a water-soluble binder.

42. The battery cell according to claim 40, wherein, Based on the total mass of the positive electrode conductive layer, the mass content of the conductive agent in the positive electrode conductive layer is 30% to 50%, and the mass content of the first binder is 50% to 70%; and / or Based on the total mass of the negative electrode conductive layer, the mass content of the conductive agent in the negative electrode conductive layer is 20% to 40%, and the mass content of the second binder is 60% to 80%.

43. The battery cell according to claim 11, wherein, The single-sided areal density of the negative electrode active layer is 104 mg / 1540.25 mm 2 -180 mg / 1540.25 mm 2 .

44. The battery cell according to claim 11, characterized in that, The single-sided areal density of the negative electrode active layer is 125 mg / 1540.25 mm 2 - 167 mg / 1540.25 mm 2 .

45. The battery cell according to claim 11, characterized in that, When the battery cell is at 100% SOC, the compaction density of the negative electrode active layer is 1.15 g / cm 3 ~1.36 g / cm 3 .

46. The battery cell according to claim 11, characterized in that, When the battery cell is at 100% SOC, the compaction density of the negative electrode active layer is 1.25 g / cm 3 ~1.36 g / cm 3 .

47. The battery cell according to claim 11, characterized in that, The negative electrode active material includes graphite.

48. The battery cell according to claim 47, characterized in that, The graphite includes composite graphite particles, the composite graphite particles include a body particle and a coating layer disposed at least partially on the surface of the body particle, the body particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

49. The battery cell according to claim 48, wherein, Based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5%.

50. The battery cell according to claim 48, characterized in that, The powder resistivity of the negative electrode active material is less than or equal to 0.04 Ω•cm.

51. The battery cell according to claim 48, wherein The powder compaction density of the negative electrode active material under a pressure of 20,000 N is 1.5 g / cm 3 to 1.7 g / cm 3 .

52. The battery cell according to claim 48, wherein, The powder compaction density of the negative electrode active material under a pressure of 20,000 N is 1.55 g / cm 3 to 1.65 g / cm 3 .

53. The battery cell according to claim 11, wherein The negative electrode active material further includes a silicon-based material, the silicon-based material includes at least one of silicon, silicon oxide compounds, and silicon-carbon composites; based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material is 0.3% to 10%.

54. The battery cell according to claim 53, wherein, Based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material is 1% to 6%.

55. The battery cell according to claim 11, characterized in that, The charging specific capacity of the negative electrode active material is 350 mAh / g to 480 mAh / g.

56. The battery cell according to claim 11, wherein, The negative electrode active layer includes a first negative electrode active material layer disposed on the surface of the negative electrode current collector and a second negative electrode active material layer disposed on the side of the first negative electrode active material layer away from the negative electrode current collector, and the second negative electrode active material layer includes composite graphite particles.

57. The battery cell according to claim 56, wherein, The first negative electrode active material layer includes one or more of composite graphite particles and natural graphite.

58. The battery cell according to claim 56, characterized in that, The ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer is 3:7 to 7:

3.

59. The battery cell according to claim 56, characterized in that, The volume average particle diameter Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 µm to 18.5 µm.

60. The battery cell according to claim 56, wherein, The volume average particle diameter Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 µm to 14.8 µm.

61. The battery cell according to claim 56, characterized in that, The volume average particle diameter Dv502 of the negative electrode active material in the second negative electrode active material layer is 7.8 µm to 14.3 µm.

62. The battery cell according to claim 56, wherein, The volume average particle diameter Dv502 of the negative electrode active material in the second negative electrode active material layer is 7.8 µm to 12.8 µm.

63. The battery cell according to claim 1, wherein The battery cell further includes a separator, and the separator includes a porous base film and a functional layer disposed on at least one side of the porous base film, and the thickness of the porous base film is less than or equal to 12 µm.

64. The battery cell according to claim 63, characterized in that, The thickness of the porous base film is less than or equal to 9 µm.

65. The battery cell according to claim 63, characterized in that, The porosity of the porous base film in the separator is 20% - 70%.

66. The battery cell according to claim 63, characterized in that, The porosity of the porous base film in the separator is 35% - 60%.

67. The battery cell according to claim 63, wherein, The functional layer includes a first functional layer disposed on the negative electrode side of the porous base film and a second functional layer disposed on the positive electrode side of the porous base film. The first functional layer includes first inorganic particles, and the second functional layer includes composite particles. The composite particles include second inorganic particles and non-fluoropolymer particles, and the second inorganic particles in the composite particles are attached to the surface and / or dispersed inside the non-fluoropolymer particles.

68. The battery cell according to claim 67, characterized in that, The non-fluoropolymer particles include acrylate copolymers.

69. The battery cell according to claim 1, wherein The liquid injection coefficient of the battery cell is 2.4 g / Ah - 3.1 g / Ah.

70. The battery cell according to claim 1, wherein The battery cell further includes electrode terminals and tab ears, and the tab ears are directly welded to the electrode terminals.

71. The battery cell according to claim 1, characterized in that, The time for the battery cell to charge from 10% state of charge to 80% state of charge at 30 °C is 6 min to 15 min.

72. The battery cell according to claim 1, characterized in that, The battery cell has a wound structure, and the thickness of the positive electrode current collector is less than or equal to 15 µm; the battery cell further includes a negative electrode plate, and the negative electrode plate includes a negative electrode current collector, and the thickness of the negative electrode current collector is less than or equal to 6 µm.

73. The battery cell according to any one of claims 1 to 72, characterized in that, The volume energy density of the battery cell is 400 Wh / L to 500 Wh / L.

74. A battery device, characterized in that, Including the battery cell according to any one of claims 1 to 73, the battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

75. An electrical device, characterized in that, Including the battery cell according to any one of claims 1 to 73.

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