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 plate, a negative electrode plate, and an electrolyte; the electrolyte includes a solvent, the solvent includes a chain carboxylic acid ester solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, the negative electrode film layer includes a negative electrode material, and the X-ray photoelectron spectroscopy (XPS) of the negative electrode material has a sulfur element 2p characteristic peak with a binding energy located at 162 eV to 170 eV.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of PCT patent application PCT / CN2024 / 106829 entitled "Battery Cell, Battery Device and Electrical Device" filed on July 22, 2024, the entire content of which 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 hydroelectric, thermal, wind and solar power stations, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.

[0005] With the dual increase in the market's demand for the charging efficiency of electrical devices and the service life in special environments, higher requirements are also put forward for the kinetic performance, high-temperature stability, etc. of battery cells. However, it is difficult to simultaneously improve the above performances in the prior art, which has become a technical problem urgently 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 and an electrical device that can take into account the high-temperature stability of the battery cell while improving the kinetic performance of the battery cell.

[0007] A first aspect of this application provides a battery cell, including a positive electrode plate, a negative electrode plate and an electrolyte; the electrolyte includes a solvent, the solvent includes a chain carboxylic ester solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector, the negative electrode film layer includes a negative electrode material, and the negative electrode material has a sulfur element 2p characteristic peak with a binding energy in the range of 162 eV to 170 eV in X-ray photoelectron spectroscopy (XPS).

[0008] The electrolyte including a chain carboxylic ester solvent and having a conductivity of 13 mS / cm - 20 mS / cm is beneficial to improving the kinetic performance of the battery, but chain carboxylic ester solvents often have high activity and will continuously erode the solid electrolyte interface (SEI) film on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI film and continuous increase of the DC internal resistance of the battery cell during storage. The SEI film contains sulfur elements, which can improve the erosion resistance of the SEI film and its thermal stability at high temperatures, taking into account the kinetic performance and storage stability of the battery cell.

[0009] In any embodiment, the sulfur element 2p characteristic peak includes at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV, a second sub-peak with a binding energy of 168.5 eV to 169.5 eV, and a third sub-peak with a binding energy of 166.5 eV to 167.5 eV. Optionally, the sulfur element 2p characteristic peak includes at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV and a third sub-peak with a binding energy of 166.5 eV to 167.5 eV, and a second sub-peak with a binding energy of 168.5 eV to 169.5 eV.

[0010] The standard spectrum and electron splitting energy level analysis show that the component corresponding to the first sub-peak with a binding energy of 162.5 eV to 164 eV is thiosulfate (S2O3 2- ), the component corresponding to the second sub-peak with a binding energy of 168.5 eV to 169.5 eV is alkoxysulfite (R-O-SO2 - ), and the component corresponding to the third sub-peak with a binding energy of 166.5 eV to 167.5 eV is sulfite (SO3 2- ). Thiosulfate and sulfite are inorganic acid radicals, which can improve the erosion resistance and thermal stability of the SEI film on the surface of the negative electrode material at high temperature; alkoxysulfite (R-O-SO2 - ) is an organic acid radical, which can improve the toughness of the SEI film on the surface of the negative electrode material. By combining the two, the kinetic performance and storage stability of the battery monomer can be taken into account.

[0011] In any embodiment, the negative electrode material includes an inorganic sulfur-containing component with the general formula Li x S y O z and an organic sulfur-containing component of ROSO2Li, where x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

[0012] The inorganic sulfur-containing component with the general formula Li x S y O z can improve the high-temperature stability and chemical stability of the SEI film, but it will also increase the brittleness of the SEI film, making it prone to rupture during the cycling process; while the organic sulfur-containing component of ROSO2Li will improve the toughness of the SEI film, so as to improve the toughness of the SEI film on the surface of the negative electrode material. By combining the two, the kinetic performance and storage stability of the battery monomer can be taken into account.

[0013] In any embodiment, the electrolyte includes a sulfur-containing additive. Optionally, the sulfur-containing additive includes one or more of sulfonate additives, sulfate esters additives, and sulfite esters additives. Optionally, the sulfur-containing additive includes one or more of sulfate esters additives and sulfite esters additives.

[0014] Sulfur-containing additives often have a relatively high potential. The sulfur-containing additives added to the electrolyte will react preferentially during formation or subsequent cycling processes and evolve into sulfur-containing components in the SEI film. Including sulfur-containing additives in the electrolyte can balance the kinetic performance and storage stability of the battery cell.

[0015] In any embodiment, the sulfur-containing additive includes a sulfur-containing additive with a cyclic structure.

[0016] The sulfur-containing additive with a cyclic structure has a suitable decomposition potential and is more likely to form a film on the surface of the negative electrode material, improving the storage stability of the battery cell.

[0017] In any embodiment, the sulfur-containing additive includes one or more of Formula I, Formula II, and Formula III.

[0018] Formula I Formula II Formula III

[0019] Each R1 independently includes one or more of -SO2-O-, C 1-3 One or more of alkylene; each of R4 and R7 independently includes C 1-3 Alkylene;

[0020] Each of R2, R3, R5, R6, R8, and R9 independently includes hydrogen, C 1-3 Alkyl, One or more of the following.

[0021] In any embodiment, based on the total mass of the electrolyte, the mass content of the sulfur-containing additive in the electrolyte of the battery cell is 0.01% - 1%.

[0022] An electrolyte with the mass content of the sulfur-containing additive in the electrolyte of the battery cell within the above range is beneficial to reinforce the SEI film during cycling and balance the kinetic performance and storage stability of the battery cell.

[0023] In any embodiment, the sulfonate additives include one or more of 1,3 - propane sultone (PS), 1,3 - propene sultone (PES), 1,4 - butane sultone (1,4 - BS), methylene methanedisulfonate (MMDS), and their derivatives.

[0024] In any embodiment, the sulfate additive includes one or more of vinylene sulfate (DTD), divinylene sulfate (2-DTD), trivinylene sulfate (3-DTD), 4-methyl-vinylene sulfate, 4-ethyl-vinylene sulfate, 4-propyl-vinylene sulfate, 4-butyl-vinylene sulfate, and their derivatives.

[0025] In any embodiment, the sulfite additive includes one or more of vinylene sulfite (ES), vinyl vinylene sulfite (VES), butylene sulfite (BS), trimethylene sulfite (TMS), and their derivatives.

[0026] In any embodiment, the sulfur-containing additive includes one or more of methylene methanedisulfonate (MMDS), vinylene sulfate (DTD), divinylene sulfate (2-DTD), trivinylene sulfate (3-DTD), vinylene sulfite (ES), butylene sulfite (BS), and their derivatives.

[0027] In any embodiment, the volume-based particle size distribution Dv50 of the negative electrode material 负 is 7.8 μm - 14.3 μm.

[0028] Dv50 负 The negative electrode active material within the above range simultaneously includes a certain content of small particles and large particles, enabling the battery cell to improve the lithium ion transmission rate through small particles and enhance the kinetic performance, and also to improve the compaction density of the battery cell electrode sheet and the energy density of the battery cell through the particle size grading of large and small particles, thereby achieving a balance between kinetic performance and energy density.

[0029] In any embodiment, the volume-based particle size distribution Dv50 of the negative electrode material 负 is 7.8 μm - 10.8 μm, and the mass content of the sulfur-containing additive in the electrolyte is 0.3% - 2%.

[0030] Volume-based particle size distribution Dv50 负 The negative electrode active material within the above range can shorten the diffusion distance of lithium ions in the solid phase and improve the kinetic performance of the battery cell. However, the negative electrode active material within the above range has a relatively large surface area and surface activity, and a relatively stronger reaction activity with chain carboxylic ester solvents. Therefore, a higher content of sulfur-containing additive is required in the electrolyte to balance kinetic performance and storage stability. 负

[0031] In any embodiment, the volume particle size Dv50 of the negative electrode material is 10.8 μm - 14.3 μm, and the mass content of the sulfur-containing additive in the electrolyte is 0.1% - 1.3%.​

[0032] In any embodiment, the electrolyte further includes a carbonate additive, and the carbonate additive includes one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0033] The sulfur-containing component on the surface of the negative electrode material can improve the high-temperature stability of the SEI film while increasing the brittleness of the SEI film. The carbonate additive can evolve into an organic component in the SEI film, improve the toughness of the SEI film, and act together with the sulfur-containing component in the SEI film to improve the stability of the SEI film during the cycling process of the battery cell and improve the cycling life of the battery cell.

[0034] In any embodiment, the electrolyte includes vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0035] 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 interface film (SEI film). Vinylene carbonate (VC) has a reduction potential close to that of chain carboxylic esters, can inhibit the reaction activity of chain carboxylic esters, improve the compactness of the SEI film, and improve the cycling life of the battery cell. The combination of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) can balance the interfacial impedance of the battery and the high-temperature stability of the SEI film. By adding a sulfur-containing additive, vinylene carbonate (VC), and fluoroethylene carbonate (FEC) in combination in the electrolyte, the kinetic performance, storage stability, and cycling life of the battery cell can be more effectively balanced.

[0036] In any embodiment, based on the total mass of the electrolyte, the mass content of the carbonate additive is 2% to 10%, and can be optionally 3% to 8%.

[0037] The electrolyte with the mass content of the carbonate additive within the above range can not only improve the cycling stability of the SEI film, but also control the degree of side reactions, and comprehensively improve the cycling life of the battery cell.

[0038] In any embodiment, based on the total mass of the electrolyte, the mass content of vinylene carbonate (VC) in the electrolyte is 1.5% to 8%, and can be optionally 2% to 6.5%.

[0039] In any embodiment, based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 4%, and can be optionally 0.5% to 3%.

[0040] By adding vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in combination in the electrolyte, the kinetic performance and cycling stability of the battery cell can be effectively balanced.

[0041] In any embodiment, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes one or more of lithium-containing phosphates with an olivine structure and lithium-containing transition metal oxides.

[0042] In any embodiment, the specific surface area of the positive electrode active material is 5.0 m 2 / g to 9.4 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 2% - 6%.

[0043] In any embodiment, the specific surface area of the positive electrode active material is 9.5 m 2 / g to 18 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 3% - 8%.

[0044] The positive electrode active material with a large specific surface area has a large contact area with the electrolyte, which can improve the kinetic performance of the battery cell. However, the positive electrode active material with a large specific surface area is more likely to absorb water molecules in the air, and it is difficult for the water molecules to be discharged from the positive electrode film layer during the drying and film-forming process. During the cycling process of the battery cell, the reaction between water molecules and the electrolyte salt in the electrolyte will generate hydrofluoric acid, which corrodes the SEI film on the surface of the negative electrode material. The positive electrode active material with a high specific surface area generates a high content of hydrofluoric acid in the battery cell. The high content of the carbonate additive can improve the compactness of the SEI film on the surface of the negative electrode material, taking into account both the kinetic performance and the cycling stability of the battery cell.

[0045] In any embodiment, the positive electrode active material includes a lithium-containing phosphate with an olivine structure, and its composition general formula is as shown in Formula IV,

[0046] Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula IV,

[0047] Among them, 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.

[0048] The lithium-containing phosphate with olivine structure having the above components has good structural stability and low irreversible loss during fast charging, thereby improving the cycle stability of the battery cell.

[0049] In any embodiment, the specific surface area of the lithium-containing phosphate with olivine structure is 5.0 m 2 / g ~ 18.0 m 2 / g.

[0050] In any embodiment, the positive electrode active material includes a lithium-containing transition metal oxide, and its general composition formula is as shown in Formula V,

[0051] Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula V

[0052] Among them, 0 < x2 ≤ 2.1, 0 ≤ y2 ≤ 2.1, and 0.9 ≤ x2 + y2 ≤ 2.1; 0 ≤ a2 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ c2 ≤ 1, and 0.1 ≤ a2 + b2 + c2 ≤ 1; 1.8 ≤ z2 ≤ 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.

[0053] In any embodiment, the specific surface area of the lithium-containing transition metal oxide is 0.1 m 2 / g ~ 2 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive in the electrolyte is 1% - 5%.

[0054] In any embodiment, 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 and iron elements. Based on the total mass of the positive electrode active material, the mass percentage of the carbon element is 1% - 2%.

[0055] The above ion-conducting layer 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 kinetic performance of the battery cell.

[0056] In any embodiment, the ion-conducting layer contains a fast ion conductor having a NASICON structure as shown in Formula VI.

[0057] Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula VI

[0058] In the Formula VI, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn. Optionally, M2 is +4 valent, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, 2 ≤ y3 ≤ 4.

[0059] The fast ion conductor having a 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 the lithium-containing phosphate with a fast ion conductor containing a NASICON structure can significantly improve the transport rate of lithium ions during multiple de-lithiation / intercalation at the positive electrode end, improve the ion conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cell.

[0060] In any embodiment, the positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes one or more 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.

[0061] 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.

[0062] In any embodiment, based on the total mass of the positive electrode film layer, the mass percentage of the lithium supplement agent is 0.1% - 10%.

[0063] In any embodiment, the negative electrode material includes graphite.

[0064] In any embodiment, the graphite includes composite graphite particles, the composite graphite particles include body particles and a coating layer disposed on the surface of the body particles, the body particles include artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0065] The inclusion of secondary particles in the composite graphite particles and the inclusion of amorphous carbon in the surface coating layer 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.

[0066] 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%.

[0067] 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 solid-phase transport ability of active ions, which is beneficial to the improvement of the kinetic performance of the battery cell.

[0068] In any embodiment, the powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm.

[0069] In any embodiment, the powder compaction density of the negative electrode material under a pressure of 20000 N is 1.5 g / cm 3 to 1.8 g / cm 3 , and can be optionally 1.55 g / cm 3 to 1.75 g / cm 3 .

[0070] The negative electrode 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 kinetic performance of the battery cell during the cycling process.

[0071] In any embodiment, the negative electrode material further includes a silicon-based material, and the silicon-based material includes one or more of silicon oxides 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% - 10%, and can be optionally 1% - 6%.

[0072] 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.

[0073] In any embodiment, the negative electrode material includes a silicon-based material, and the added mass content of carbonate additives in the electrolyte is 3% - 10%.

[0074] Silicon-based materials are prone to expansion during the cycling process, resulting in the rupture of the SEI film on the surface of the negative electrode material. Therefore, the consumption of additives is greater. The carbonate additives within the above range can improve the compactness and regeneration ability of the SEI film, taking into account the energy density and cycle stability of the battery cell.

[0075] In any embodiment, the negative electrode film layer includes a first negative electrode film layer disposed on the surface of the negative electrode current collector and a second negative electrode film layer disposed on the side of the first negative electrode film layer away from the negative electrode current collector. The second negative electrode film layer includes composite graphite particles; optionally, the negative electrode material in the first negative electrode film layer includes one or more of composite graphite particles and natural graphite.

[0076] The composite graphite particles are disposed near the electrolyte side, which can take into account the energy density while improving the kinetic performance of the battery cell.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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 kinetic performance of the battery cell.

[0081] In any embodiment, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 10.8 μm, and the added mass content of the carbonate additive in the electrolyte is 3% to 8%.

[0082] In any embodiment, in the electrolyte, the added mass content of vinylene carbonate VC is 3% to 7%, and the added mass content of fluoroethylene carbonate FEC is 0.5% to 2%.

[0083] In any embodiment, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% to 7%.

[0084] A relatively small volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is beneficial to the solid-phase diffusion of lithium ions in the negative electrode active material. However, at the same time, it will increase the reaction activity between the negative electrode active material and the chain carboxylic acid ester solvent and increase the decomposition of the SEI film. By matching a relatively high content of carbonate additives, the compactness and regeneration ability of the SEI film on the surface of the negative electrode material can be improved, and the cycle stability of the battery cell can be improved.

[0085] In any embodiment, in the electrolyte, the added mass content of vinylene carbonate VC is 2% to 6%, and the added mass content of fluoroethylene carbonate FEC is 0.5% to 2.5%.

[0086] In any embodiment, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic acid ester is 25.5% - 63.75%.

[0087] In any embodiment, the chain carboxylic acid ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include at least one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms.

[0088] In any embodiment, the chain carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

[0089] The electrolyte with the mass content of the chain carboxylic acid ester within the above range has good conductivity, wettability, and chemical stability, which is beneficial to the comprehensive improvement of the kinetic performance, storage stability, and cycle stability of the battery cell.

[0090] In any embodiment, the solvent further includes a carbonate solvent. Based on the total mass of the electrolyte, the mass content ratio of the carbonate solvent is 17% - 76.5%, and can be optionally 21.25% - 59.5%.

[0091] In any embodiment, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0092] The lithium ions in the carbonate solvent and the lithium-containing electrolyte salt in the electrolyte are prone to form a solvation structure to increase the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt, thereby improving the kinetic performance of the battery cell.

[0093] In any embodiment, the carbonate solvent includes ethylene carbonate, and the mass ratio of ethylene carbonate to the chain carboxylic acid ester is 0.27:1 - 1.33:1.

[0094] Chain carboxylic acid esters 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. At the same time, the addition of chain carboxylic acid esters is also beneficial to the improvement of the electrolyte conductivity; however, chain carboxylic acid esters are prone to react with the SEI film, reducing the storage stability of the battery monomer. In the electrolyte, ethylene carbonate 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 to some extent, which has a negative impact on the conductivity of the electrolyte. The mass ratio of ethylene carbonate to the chain carboxylic acid ester within the above range enables the electrolyte to have appropriate viscosity, conductivity, good dissociation rate and wettability at the same time, which is beneficial to comprehensively improve the kinetic performance and high-temperature stability of the battery monomer.

[0095] In any embodiment, the electrolyte includes a lithium salt, and the carbonate solvent includes ethylene carbonate, wherein the mass ratio of the lithium salt to the ethylene carbonate is 0.29 - 0.72.

[0096] Ethylene carbonate in the electrolyte and lithium ions in the lithium-containing electrolyte salt within the above range can increase the dissociation rate of lithium ions and improve the kinetic performance of the battery monomer.

[0097] In any embodiment, the conductivity of the electrolyte is 13 mS / cm - 20 mS / cm; optionally, it can be 15 mS / cm - 20 mS / cm.

[0098] The electrolyte with conductivity within the above range can better balance the kinetic performance and high-temperature stability of the battery monomer.

[0099] In any embodiment, the lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate LiPF6; optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethylsulfonyl)imide LiTFSI.

[0100] Fluorosulfonylimide salts are prone to dissociation in the electrolyte solvent, which is beneficial to improving the conductivity of the electrolyte. And fluorosulfonylimide salts have high chemical stability and are not prone to decomposition during the recycling process, which can reduce the generation of hydrogen fluoride during the battery cycle, reduce the probability of side reactions on the negative electrode, and improve the cycle stability of the battery monomer. However, with the increase in the temperature of the battery monomer, the fluorosulfonylimide salt will undergo violent decomposition at a certain temperature threshold, releasing a large amount of heat, which sharply increases 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 cycle, the addition of lithium hexafluorophosphate will greatly reduce the risk of thermal runaway of the battery monomer, making the risk reduced within a controllable range and improving the safety of the battery.

[0101] In any embodiment, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6). The molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) in the electrolyte is 0.2 mol / L - 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate (LiPF6) in the electrolyte is 0.5 mol / L to 1.0 mol / L.

[0102] In any embodiment, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate (LiPF6) in the electrolyte is (2 - 5):10.

[0103] The battery cell with the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate (LiPF6) in the electrolyte within the above ranges can balance the kinetic performance and safety performance of the battery cell.

[0104] In any embodiment, 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. The thickness of the porous base film is ≤ 12 μm, and can be optionally less than or equal to 9 μm.

[0105] In any embodiment, the porosity of the porous base film in the separator is 20% - 70%, and can be optionally 35% - 60%.

[0106] In any embodiment, 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, and the second functional layer includes composite particles. The composite particles include second inorganic particles and non-fluorinated polymers. The second inorganic particles in the composite particles adhere to the surface of the non-fluorinated polymer particles and / or are dispersed inside the non-fluorinated polymer particles.

[0107] Inorganic particles can improve the heat resistance of the first functional layer and the second functional layer and improve the kinetic performance of the battery cell.

[0108] In any embodiment, the non-fluorinated polymer particles include acrylate copolymers.

[0109] In any embodiment, the liquid injection coefficient of the battery cell is 2.2 g / Ah - 3.1 g / Ah.

[0110] In any embodiment, the fast charging time of the battery cell from 10% SOC to 80% SOC is 6 min - 15 min.

[0111] The second aspect of the present application provides a battery device, including the battery cell provided by 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.

[0112] The third aspect of the present application provides an electrical device, including the battery cell provided by the first aspect of the present application. Description of the Drawings

[0113] Figure 1 It is an X-ray photoelectron spectroscopy diagram of sulfur element of the negative electrode material in an embodiment of the present application.

[0114] Figure 2 It is an X-ray photoelectron spectroscopy diagram of sulfur element of the negative electrode material in another embodiment of the present application.

[0115] Figure 3 It is a schematic diagram of a battery cell in another embodiment of the present application.

[0116] Figure 4 It is Figure 3 An exploded view of the battery cell shown in an embodiment of the present application.

[0117] Figure 5 It is a schematic diagram of a battery module in an embodiment of the present application.

[0118] Figure 6 It is a schematic diagram of a battery pack in an embodiment of the present application.

[0119] Figure 7 It is Figure 6 An exploded view of the battery pack shown in an embodiment of the present application.

[0120] Figure 8 It is a schematic diagram of an electrical device using the battery cell as a power source in an embodiment of the present application.

[0121] Description of the Reference Numerals:

[0122] 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 Embodiments

[0123] 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 drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0124] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0125] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form a new technical solution.

[0126] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0127] If there is no special instruction, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0128] If there is no special instruction, 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.

[0129] Unless otherwise specified, the term "or" is inclusive in this application. 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) and B is true (or exists); or both A and B are true (or exist).

[0130] To improve the kinetic performance of a battery cell, a solvent with high conductivity, such as a chain carboxylic acid ester solvent, is often added to the electrolyte to achieve rapid ion transport and reduce the possibility of lithium precipitation. However, high-conductivity solvents often have high activity and will continuously erode the solid electrolyte interface (SEI) film on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI film and an increase in the DC internal resistance of the battery cell during storage, thereby reducing the usage stability of the battery cell.

[0131] Based on this, this application proposes a battery cell, including a positive electrode sheet, a negative electrode sheet, and an electrolyte; the electrolyte includes a solvent, the solvent includes a chain carboxylic acid ester solvent, and the conductivity of the electrolyte is greater than or equal to 13 mS / cm; the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, the negative electrode film layer includes a negative electrode material, and the X-ray photoelectron spectroscopy (XPS) of the negative electrode material has a sulfur element 2p characteristic peak with a binding energy in the range of 162 eV to 170 eV.

[0132] In this application, the X-ray photoelectron spectroscopy (XPS) of the negative electrode material can be tested by any well-known method in the art. As an example, after disassembling the battery cell, the negative electrode sheet is cleaned with a solvent such as dimethyl carbonate (DMC) more than three times and then scraped to obtain a powder sample. The obtained powder sample of the negative electrode material is adhered to a conductive substrate, and X-ray photoelectron spectroscopy is performed using an X-ray photoelectron spectrometer (such as AXIS ULTRA). The scanning rate and time of the X-ray source are adjusted to focus and detect elements and functional groups at a depth of 5 nm to 10 nm from the surface of the negative electrode material, and an X-ray photoelectron spectroscopy (XPS) spectrum of the sample is obtained, and the element characteristic peaks are analyzed in the spectrum.

[0133] The chain carboxylic acid ester solvent refers to a chain-shaped organic molecule containing a carboxylic acid ester group. As an example, it includes but is not limited to propyl butyrate, ethyl butyrate, methyl butyrate, ethyl propionate, methyl propionate, ethyl acetate, methyl acetate, methyl formate, etc.

[0134] The types and masses of solvents in the electrolyte can be obtained by detecting the electrolyte through methods well-known to those skilled in the art. For example, the composition of 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 a diluted electrolyte solution to be tested, use a GC-MS 3100 organic component gas chromatograph, place the above-mentioned diluted electrolyte solution in the instrument for full-scan qualitative analysis, with the injection port temperature at 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.

[0135] The conductivity of the electrolyte describes the ability of the positive and negative ions dissociated in the electrolyte solution to move directionally in an electric field to form a conductive process, and can be tested by any well-known method in the art. As an example, take about 100 mL of 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 (with a deviation of ±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 a calibration solution, vertically place it into the liquid to be tested, click start to test, and record the test result after the data is stable for more than 10 s.

[0136] In some embodiments, the conductivity of the electrolyte can be selected as 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 any numerical range between any two of them.

[0137] The electrolyte including chain carboxylic ester solvents and having a conductivity of 13 mS / cm - 20 mS / cm is beneficial to improving the kinetic performance of the battery cell. However, chain carboxylic ester solvents often have high activity and will continuously erode the solid electrolyte interface (SEI film) on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI film and continuous increase in the DC internal resistance of the battery cell during storage. The SEI film on the surface of the negative electrode material of the battery cell in this application contains sulfur elements, which can improve the erosion resistance and thermal stability at high temperatures of the SEI film, taking into account the kinetic performance and storage stability of the battery cell.

[0138] In some embodiments, the sulfur element 2p characteristic peak includes at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV, a second sub-peak with a binding energy of 168.5 eV to 169.5 eV, and a third sub-peak with a binding energy of 166.5 eV to 167.5 eV. Optionally, the sulfur element 2p characteristic peak includes at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV and a third sub-peak with a binding energy of 166.5 eV to 167.5 eV, and a second sub-peak with a binding energy of 168.5 eV to 169.5 eV.

[0139] The sulfur element 2p characteristic peak can be a single peak with one peak top or a multi-peak with multiple peak tops. Whether it is a single peak or a multi-peak, the XPSpeak software can be used to perform peak fitting on the characteristic peak of the S2p energy spectrum to obtain sub-peaks. The standard spectrum and electron splitting energy level analysis show that the component corresponding to the first sub-peak with a binding energy of 162.5 eV to 164 eV is thiosulfate (S2O3 2- ), the component corresponding to the second sub-peak with a binding energy of 168.5 eV to 169.5 eV is alkoxysulfite (R-O-SO2 - ), and the component corresponding to the third sub-peak with a binding energy of 166.5 eV to 167.5 eV is sulfite (SO3 2- ). Thiosulfate and sulfite are inorganic acid radicals, which can improve the erosion resistance and thermal stability at high temperature of the SEI film on the surface of the negative electrode material; alkoxysulfite (R-O-SO2 - ) is an organic acid radical, which can improve the toughness of the SEI film on the surface of the negative electrode material. By combining the two, the kinetic performance, storage stability and cycle life of the battery monomer can be taken into account.

[0140] In some embodiments, the negative electrode material includes an inorganic sulfur-containing component with the general formula Li x S y O z and an organic sulfur-containing component of ROSO2Li, where x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

[0141] The XPS full-spectrum test of the negative electrode material shows that the main cation at a distance from the surface of the negative electrode material is lithium ion. Therefore, it can be inferred that the negative electrode material includes an inorganic sulfur-containing component with the general formula Li x S y O z and an organic sulfur-containing component of ROSO2Li at a distance from the surface.

[0142] In some embodiments, x can be optionally 1, 2, 3 or a numerical range between any two of them, y can be optionally 1, 2, 3 or a numerical range between any two of them, z can be optionally 2, 3, 4, 5, 6 or a numerical range between any two of them, and R is a substituted or unsubstituted alkyl group. R includes but is not limited to methyl, ethyl, propyl, butyl, etc.

[0143] The general formula is Li x S y O z The inorganic sulfur-containing component can improve the high-temperature stability and chemical stability of the SEI film, but it will also increase the brittleness of the SEI film, making it prone to rupture during cycling; while the organic sulfur-containing component with the general formula ROSO2Li can improve the toughness of the SEI film, thereby improving the toughness of the SEI film on the surface of the anode material. By combining the two, the kinetic performance, storage stability and cycle life of the battery monomer can be taken into account.

[0144] In some embodiments, the electrolyte includes a sulfur-containing additive. Optionally, the sulfur-containing additive includes one or more of sulfonate additives, sulfate additives, and sulfite additives. Optionally, the sulfur-containing additive includes one or more of sulfate additives and sulfite additives.

[0145] An additive refers to a component with a relatively low content in the electrolyte, generally with a mass ratio in the electrolyte not exceeding 10%. It has the characteristics of strong pertinence and small dosage, and can significantly optimize a certain aspect of the battery performance without changing the production process.

[0146] The components of the additive can be measured by any well-known method in the art. For 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 quantitative electrolyte (the dilution concentration is in the middle of the standard curve), make up the volume to 100 mL with ultrapure water, and the ion chromatograph automatically injects samples 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 organic component gas chromatograph, place the above electrolyte dilution in the instrument for full-scan qualitative analysis, the inlet temperature is 250°C, the scanning range: 35μm~270μm. After the test, the total ion current chromatogram of each organic substance is obtained, and the corresponding organic species are compared according to the peak position in the chromatogram.

[0147] In this application, sulfonate additives refer to compounds and their derivatives including a sulfonate group (-SO2-O-), and mixtures containing the above compounds and their derivatives. The compounds including a sulfonate group (-SO2-O-) can be linear compounds or cyclic compounds. Sulfonate additives can form at least one of thiosulfate (S2O3 2- ), sulfite (SO3 2- ), and alkoxysulfite (R-O-SO2 - ) in the SEI film on the surface of the negative electrode material, so that in the X-ray photoelectron spectroscopy (XPS) of the negative electrode material at a distance of 5 nm to 10 nm from the surface, there appears at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV, a third sub-peak with a binding energy of 166.5 eV to 167.5 eV, and a second sub-peak with a binding energy of 168.5 eV to 169.5 eV.

[0148] In this application, sulfate additives refer to compounds and their derivatives including a sulfate group (-O-SO2-O-), and mixtures containing the above compounds and their derivatives. The compounds including a sulfate group (-O-SO2-O-) can be linear compounds or cyclic compounds. Sulfate additives can form alkoxysulfite (R-O-SO2 - ), thiosulfate (S2O3 2- ), and sulfite (SO3 2- ) in the SEI film on the surface of the negative electrode material, so that in the X-ray photoelectron spectroscopy (XPS) of the negative electrode material at a distance of 5 nm to 10 nm from the surface, there appear a second sub-peak with a binding energy of 168.5 eV to 169.5 eV, a first sub-peak with a binding energy of 162.5 eV to 164 eV, and a third sub-peak with a binding energy of 166.5 eV to 167.5 eV.

[0149] In this application, sulfite additives refer to compounds and their derivatives including a sulfite group (-O-SO-O-), and mixtures containing the above compounds and their derivatives. The compounds including a sulfite group (-O-SO-O-) can be linear compounds or cyclic compounds. Sulfite additives can form alkoxysulfite (R-O-SO2 - ) and thiosulfate (S2O3 2- ) in the SEI film on the surface of the negative electrode material, so that in the X-ray photoelectron spectroscopy (XPS) of the negative electrode material at a distance of 5 nm to 10 nm from the surface, there appear a second sub-peak with a binding energy of 168.5 eV to 169.5 eV and a first sub-peak with a binding energy of 162.5 eV to 164 eV.

[0150] Sulfur-containing additives often have a relatively high potential. The sulfur-containing additives added to the electrolyte will preferentially react during formation or subsequent cycling processes and evolve into sulfur-containing components in the SEI film. It can be understood that in some embodiments, the sulfur-containing additives added to the electrolyte are completely converted into sulfur-containing components in the SEI film during the formation process. In some embodiments, there are still sulfur-containing additives remaining in the electrolyte, which form a strengthening effect on the SEI film during subsequent cycling of the battery cell.

[0151] The inclusion of sulfur-containing additives in the electrolyte can balance the kinetic performance and storage stability of the battery cell.

[0152] In some embodiments, the sulfur-containing additive includes a sulfur-containing additive with a cyclic structure.

[0153] A sulfur-containing additive with a cyclic structure refers to a heterocyclic compound structure in which atoms in the molecule are arranged in a ring and include sulfur atoms. The sulfur-containing additive with a cyclic structure has a suitable decomposition potential and is more likely to form a film on the surface of the negative electrode material, improving the storage stability of the battery cell.

[0154] In some embodiments, the sulfur-containing additive includes one or more of Formula I, Formula II, and Formula III.

[0155] Formula I Formula II Formula III

[0156] Each R1 independently includes one or more of -SO2-O-, C 1-3 alkylene; each of R4 and R7 independently includes C 1-3 alkylene;

[0157] Each of R2, R3, R5, R6, R8, and R9 independently includes hydrogen, C 1-3 alkyl, one or more of the following.

[0158] In this application, C 1-3 alkylene refers to alkylene including 1 to 3 carbon atoms, including but not limited to methylene, ethylene, and propylene.

[0159] In this application, C 1-3 alkyl refers to alkyl including 1 to 3 carbon atoms, including but not limited to methyl, ethyl, and propyl.

[0160] In some embodiments, based on the total mass of the electrolyte, the mass content of the sulfur-containing additive in the electrolyte of the battery cell is 0.01% to 1%.

[0161] In some embodiments, based on the total mass of the electrolyte, the mass content of the sulfur-containing additive in the electrolyte of the battery cell can be optionally 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%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or a numerical range between any two of them.

[0162] The type and mass of the sulfur-containing additive in the electrolyte can be obtained by detecting the electrolyte through methods well-known to those skilled in the art. For example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Exemplarily, an ion chromatograph (IC) is used to test the inorganic content in the electrolyte. A quantitative electrolyte (the dilution concentration is in the middle of the standard curve) is weighed and made up to 100 mL with ultrapure water, and the ion chromatograph automatically injects samples for detection. The inorganic ion chromatogram of the electrolyte is tested. According to the peak position of the chromatogram, the corresponding inorganic substance type is compared, and the percentage of the corresponding inorganic ion content is calculated according to the peak area. The above free electrolyte is diluted 3 to 10 times with acetonitrile to obtain a diluted electrolyte solution to be tested. A GC-MS 3100 gas chromatograph for organic components is used. The above diluted electrolyte solution is placed 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, the total ion current chromatogram of each organic substance is obtained. According to the peak position of the chromatogram, the corresponding organic substance type is compared, and the corresponding content percentage of each organic substance is calculated according to the peak area. The mass of the sulfur-containing additive measured is divided by the mass of the electrolyte sample to obtain the mass content of the sulfur-containing additive in the electrolyte of the battery cell. It can be understood that the mass content of the sulfur-containing additive in the electrolyte of the battery cell is slightly lower than the added mass content of the sulfur-containing additive in the electrolyte of the battery cell.

[0163] The electrolyte with the mass content of the sulfur-containing additive in the electrolyte of the battery cell within the above range is beneficial to strengthening the SEI film during the cycling process, taking into account the kinetic performance, storage stability, and cycling stability of the battery cell.

[0164] In some embodiments, the sulfonate additives include one or more of 1,3-propane sultone (PS), 1,3-propene sultone (PES), 1,4-butane sultone (1,4-BS), methylene methanedisulfonate (MMDS), and their derivatives.

[0165] In some embodiments, the sulfate ester additives include one or more of vinylene sulfate (DTD), divinylene sulfate (2-DTD), trivinylene sulfate (3-DTD), 4-methyl-vinylene sulfate, 4-ethyl-vinylene sulfate, 4-propyl-vinylene sulfate, 4-butyl-vinylene sulfate, and their derivatives.

[0166] In some embodiments, the sulfite ester additives include one or more of ethylene sulfite (ES), vinyl ethylene sulfite (VES), butene sulfite (BS), trimethylene sulfite (TMS), and their derivatives.

[0167] In some embodiments, the sulfur-containing additives include one or more of methylene methanedisulfonate (MMDS), vinylene sulfate (DTD), divinylene sulfate (2-DTD), trivinylene sulfate (3-DTD), ethylene sulfite (ES), butene sulfite (BS), and their derivatives.

[0168] In some embodiments, the volume-based particle size distribution Dv50 of the negative electrode material 负 is 7.8 μm - 14.3 μm.

[0169] The volume-based particle size distribution Dv50 of the negative electrode active material 负 has the meaning well known in the art, which represents the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%, and can be measured by instruments and methods known in the art. For example, it can be conveniently measured by referring to GB / T 19077-2016 Laser diffraction method for particle size distribution and using a laser particle size analyzer. The test instrument can be the Mastersizer 3000 type laser particle size analyzer of Malvern Instruments Limited, UK.

[0170] In some embodiments, the volume-based particle size distribution Dv50 of the negative electrode material 负 can be optionally 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9.0 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, 10.7 μm, 10.8 μm, 11.8 μm, 12.8 μm, 13.8 μm, 14.3 μm, or a numerical range between any two of them.

[0171] Dv50 负The negative electrode active material within the above range simultaneously includes a certain content of small particles and large particles, enabling the battery cell to improve the lithium-ion transmission rate through the small particles, enhance the kinetic performance, and improve the compaction density of the battery cell electrode sheet through the particle size grading of large and small particles, thereby improving the energy density of the battery cell and achieving the balance between kinetic performance and energy density.

[0172] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material 负 is 7.8 μm to 10.8 μm, and the mass content of the sulfur-containing additive in the electrolyte is 0.3% to 2%.

[0173] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material 负 can be optionally 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9.0 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, 10.7 μm, 10.8 μm or the numerical range between any two of them, and the mass content of the sulfur-containing additive in the electrolyte can be optionally 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% or the numerical range between any two of them.

[0174] The volume distribution particle size Dv50 负 The negative electrode active material within the above range can shorten the diffusion distance of lithium ions in the solid phase and improve the kinetic performance of the battery cell. However, the volume distribution particle size Dv50 负 The negative electrode active material within the above range has a relatively large surface area and surface activity, and relatively stronger reactivity with the chain carboxylic ester solvent. Therefore, a higher content of sulfur-containing additive is required in the electrolyte to balance the kinetic performance and storage stability.

[0175] In some embodiments, the volume particle size Dv50 of the negative electrode material is 10.8 μm to 14.3 μm, and the mass content of the sulfur-containing additive in the electrolyte is 0.1% to 1.3%.

[0176] In some embodiments, the volume particle size Dv50 of the negative electrode material can be selected from 10.8 μm, 10.9 μm, 11 μm, 11.1 μm, 11.2 μm, 11.3 μm, 11.4 μm, 11.5 μm, 11.6 μm, 11.7 μm, 11.8 μm, 12.8 μm, 13.8 μm, 14.3 μm, or the numerical range between any two of them, and the mass content of the sulfur-containing additive in the electrolyte can be selected from 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.

[0177] In some embodiments, the electrolyte further includes a carbonate additive, and the carbonate additive includes one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0178] In the present application, the carbonate additive refers to a compound and its derivatives including a carbonate group (-O-CO-O-), and a mixture containing the above compounds and their derivatives.

[0179] The sulfur-containing component on the surface of the negative electrode material can improve the high-temperature stability of the SEI film while increasing the brittleness of the SEI film. The carbonate additive can evolve into an organic component in the SEI film, improve the toughness of the SEI film, and cooperate with the sulfur-containing component in the SEI film to improve the stability of the SEI film during the cycling process of the battery cell and improve the cycling life of the battery cell.

[0180] In some embodiments, the electrolyte includes vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0181] 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 also eroding the solid electrolyte interface film (SEI film). Vinylene carbonate (VC) has a reduction potential close to that of chain carboxylic esters, can inhibit the reaction activity of chain carboxylic esters, improve the denseness of the SEI film, and improve the cycling life of the battery cell. The combination of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) can balance the interfacial impedance of the battery and the high-temperature stability of the SEI film. By adding a sulfur-containing additive, vinylene carbonate (VC), and fluoroethylene carbonate (FEC) in combination in the electrolyte, the kinetic performance, storage stability, and cycling life of the battery cell can be more effectively balanced.

[0182] In some embodiments, based on the total mass of the electrolyte, the mass content of the carbonate additive is 2% - 10%, and can be selected from 3% - 8%.

[0183] In some embodiments, based on the total mass of the electrolyte, the mass content of the carbonate additive may be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a numerical range between any two of them.

[0184] The electrolyte with the mass content of the carbonate additive within the above range can not only improve the cycle stability of the SEI film, but also control the degree of side reactions, comprehensively improving the cycle life of the battery cell.

[0185] In some embodiments, based on the total mass of the electrolyte, the mass content of vinylene carbonate (VC) in the electrolyte is 1.5% to 8%, and may be 2% - 6.5%.

[0186] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of vinylene carbonate (VC) in the electrolyte may be 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, or a numerical range between any two of them.

[0187] In some embodiments, based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 4%, and may be 0.5% - 3%.

[0188] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of fluoroethylene carbonate (FEC) in the electrolyte may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or a numerical range between any two of them.

[0189] By adding vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in the electrolyte, the kinetic performance and cycle stability of the battery cell can be effectively balanced.

[0190] In some embodiments, the positive electrode plate includes a positive current collector and a positive electrode film layer located on at least one surface of the positive current collector. The positive electrode film layer includes a positive active material, and the positive active material includes one or more of lithium phosphate with an olivine structure and lithium-containing transition metal oxides.

[0191] In some embodiments, the specific surface area of the positive active material is 5.0 m 2 / g - 9.4m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 2% - 6%.

[0192] In this 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, reference can be made to GB / T 19587-2017, and the nitrogen adsorption specific surface area analysis test method can be used for testing, and the BET (Brunauer Emmett Teller) method can be used for calculation. The test instrument can be the Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics Company in the United States.

[0193] In some embodiments, the specific surface area S of the positive electrode active material can be selected as 5 m 2 / g, 5.4 m 2 / g, 6 m 2 / g, 6.4 m 2 / g, 7 m 2 / g, 7.4 m 2 / g, 8 m 2 / g, 8.4 m 2 / g, 9 m 2 / g, 9.4 m 2 / g or any value range between any two of them, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte can be selected as 2%, 3%, 4%, 5%, 6% or any value range between any two of them.

[0194] In some embodiments, the specific surface area of the positive electrode active material is 9.5 m 2 / g ~ 18 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 3% - 8%.

[0195] In some embodiments, the specific surface area of the positive electrode active material can be selected as 9.5 m 2 / g, 10 m 2 / g, 10.5 m 2 / g, 11 m 2 / g, 11.5 m 2 / g, 12 m 2 / g, 12.5 m 2 / g, 13 m 2 / g, 13.5 m 2 / g, 14 m 2 / g, 14.5 m 2 / g, 15 m 2 / g, 15.5 m 2 / g, 16 m 2 / g, 16.5 m 2 / g, 17 m 2 / g, 17.5 m 2 / g, 18 m 2 / g or a numerical range between any two of them, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8% or a numerical range between any two of them.

[0196] The contact area between the cathode active material with a large specific surface area and the electrolyte is large, which can improve the kinetic performance of the battery cell. However, the cathode active material with a large specific surface area is more likely to absorb water molecules in the air, and it is difficult for the water molecules to escape from the cathode film layer during the drying and film-forming process. During the cycling process of the battery cell, the reaction between water molecules and the electrolyte salt in the electrolyte will generate hydrofluoric acid, which corrodes the SEI film on the surface of the anode material. The content of hydrofluoric acid generated by the cathode active material with a high specific surface area in the battery cell is high. By using a high content of carbonate additives, the compactness of the SEI film on the surface of the anode material can be improved, taking into account both the kinetic performance and cycling stability of the battery cell.

[0197] In some embodiments, the cathode active material includes a lithium-containing phosphate with an olivine structure, and its general composition formula is as shown in Formula IV.

[0198] Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula IV

[0199] 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.

[0200] In some embodiments, x1 can be optionally 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, or a numerical range between any two of them; y1 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, or a numerical range between any two of them; x1 + y1 can be optionally 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, or a numerical range between any two of them; a1 can be optionally 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, or a numerical range between any two of them; b1 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, or a numerical range between any two of them; a1 + b1 can be optionally 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, or a numerical range between any two of them; c1 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, or a numerical range between any two of them; z1 can be optionally 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 a numerical range between any two of them.

[0201] The lithium-containing phosphate with olivine structure having the above components has good structural stability and low irreversible loss during fast charging, thereby improving the cycle stability of the battery cell.

[0202] In some embodiments, the specific surface area of the lithium-containing phosphate with olivine structure is 5.0 m 2 / g ~ 18.0 m 2 / g.

[0203] In some embodiments, the specific surface area of the lithium-containing phosphate with olivine structure can be optionally 5.0 m 2 / g, 6.0 m 2 / g, 7.0 m 2 / g, 8.0 m 2 / g, 9.0 m 2 / g, 10.0 m 2 / g, 11.0 m 2 / g, 12.0 m 2 / g, 13.0 m 2 / g, 14.0 m 2 / g, 15.0 m 2 / g, 16.0 m 2 / g, 17.0 m 2 / g, 18.0 m 2 / g or a numerical range between any two of them.

[0204] In some embodiments, the positive electrode active material comprises a lithium-containing transition metal oxide, and its general composition formula is shown as Formula V:

[0205] Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula V

[0206] wherein, 0 < x2 ≤ 2.1, 0 ≤ y2 ≤ 2.1, and 0.9 ≤ x2 + y2 ≤ 2.1; 0 ≤ a2 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ c2 ≤ 1, and 0.1 ≤ a2 + b2 + c2 ≤ 1; 1.8 ≤ z2 ≤ 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.

[0207] In some embodiments, x2 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; y2 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 x2 + y2 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; a2 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; b2 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; c2 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 a2 + b2 + c2 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; z2 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.

[0208] In some embodiments, the specific surface area of the lithium-containing transition metal oxide is 0.1 m 2 / g to 2 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive in the electrolyte is 1% - 5%.

[0209] In some embodiments, the specific surface area of the lithium-containing transition metal oxide can be optionally 0.1 m 2 / g, 0.2 m 2 / g, 0.3 m 2 / g, 0.4 m 2 / g, 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2 m 2 / g or a numerical range between any two of them, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte can be selected as 1%, 2%, 3%, 4%, 5% or a numerical range between any two of them.

[0210] 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 and iron elements. Based on the total mass of the positive electrode active material, the mass percentage of carbon is 1% - 2%.

[0211] In some embodiments, based on the total mass of the positive electrode active material, the mass percentage of carbon can be selected as 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% or a numerical range between any two of them.

[0212] 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 iron-containing component and the carbon-containing component 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.

[0213] 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 kinetic performance of the battery monomer.

[0214] In some embodiments, the ion-conducting layer includes a fast ion conductor having a NASICON structure as shown in Formula VI.

[0215] Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula VI

[0216] In the Formula VI, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn. Optionally, M2 is +4 valence, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, 2 ≤ y3 ≤ 4.

[0217] In some embodiments, 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, x3 can be optionally 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 a numerical range between any two of them, and y3 can be optionally 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 a numerical range between any two of them.

[0218] 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.

[0219] 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 lithium deintercalation and intercalation processes. Coating the surface of the lithium-containing phosphate with a fast ion conductor containing NASICON structure can significantly improve the transport rate of lithium ions during multiple deintercalation / intercalation at the positive electrode end, improve the ion conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cell.

[0220] In some embodiments, the fast ion conductor includes one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, and Li2FeSn(PO4)3.

[0221] In some embodiments, the positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes one or more 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.

[0222] 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.

[0223] The ternary lithium supplement material refers to an oxide lithium supplement agent including one or more of nickel, cobalt, and manganese.

[0224] In some embodiments, based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplementing agent is 0.1% - 10%.

[0225] In some embodiments, based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplementing agent 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 the numerical range between any two of them.

[0226] The mass content ratio of the lithium supplementing agent added in the positive electrode film layer is calculated by dividing the added mass of the lithium supplementing agent by the total mass of the positive electrode film layer.

[0227] In some embodiments, the negative electrode active material includes graphite.

[0228] In some embodiments, the graphite includes composite graphite particles, the composite graphite particles include a main body particle and a coating layer disposed at least partially on the surface of the main body particle, the main body particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0229] Secondary particles refer to particles formed by aggregation of two or more primary particles.

[0230] 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, and contribute to the improvement of the rate performance of the battery cell.

[0231] In some embodiments, the composite graphite material further includes kinetic carbon materials.

[0232] In some embodiments, the kinetic carbon materials are located between the primary particles of the main body particle. At this time, the main body particles of the negative electrode active material include artificial graphite primary particles and kinetic carbon materials located between the primary particles.

[0233] In some embodiments, the kinetic carbon materials are located in the coating layer. At this time, the coating layer includes both amorphous carbon and kinetic carbon materials.

[0234] In some embodiments, the raw materials of the kinetic carbon materials include one or more of hard carbon, expanded graphite, and graphene.

[0235] In this article, "the raw materials of the kinetic carbon materials" and "the powder of the raw materials of the kinetic carbon materials" are completely the same in composition. "Kinetic carbon materials" refers to the product obtained by graphitization treatment and / or carbonization treatment of "the raw materials of the kinetic carbon materials".

[0236] In some embodiments, the interlayer spacing d of the crystal plane of the kinetic carbon material raw material (002) 002 ≥0.3358 nm, optionally 0.3359 nm to 0.3366 nm.

[0237] The interlayer spacing of the kinetic carbon material raw material is greater than that of conventional graphite (the interlayer spacing of conventional graphite is 0.335 nm). When the obtained kinetic carbon material is uniformly distributed in the main particles and / or the coating layer of the composite graphite particles, it is beneficial to the rapid insertion and extraction of active ions, thereby improving the transport performance of active ions and electrons, and further improving the rapid charging performance of the battery cell.

[0238] 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%.

[0239] 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.

[0240] 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 solid-phase transport ability of active ions, which is beneficial to the improvement of the kinetic performance of the battery cell.

[0241] In some embodiments, the powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm.

[0242] In some embodiments, the powder resistivity of the negative electrode material can be optionally 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.

[0243] The powder resistivity of the negative electrode material can be measured by any well-known method in the art. As an example, it can be measured with reference to the powder resistivity test method of the positive electrode active material described above. For example, a powder resistivity tester (PRCD1100) can be used to analyze and test according to standard GB / T30835-2014.

[0244] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20000 N is 1.5 g / cm 3 to 1.8 g / cm 3 , optionally 1.55 g / cm 3 to 1.75 g / cm 3 .

[0245] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20,000 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 , 1.75 g / cm 3 , 1.8 g / cm 3 or a numerical range between any two of them.

[0246] The powder compaction density of the negative electrode material under a pressure of 20,000 N has a well-known meaning in the art and can be measured by instruments and methods known in the art. For example, it can be measured by referring 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 1 g of the negative electrode active material powder, add it to a mold with a bottom area of 1.327 cm 2 , apply a pressure of 20,000 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 20,000 N.

[0247] The negative electrode material with a powder compaction density within a suitable range can make the negative electrode active layer have a higher compaction density, and thus the battery cell has a higher energy density; at the same time, during the cycling process, the original pore structure of the negative electrode active layer can be maintained, which is beneficial to improving the retention of the high kinetic performance of the battery cell during the cycling process.

[0248] In some embodiments, the negative electrode active material further includes a silicon-based material, and the silicon-based material includes at least one of silicon, silicon oxide, 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 can be selected as 1% to 6%.

[0249] In some embodiments, based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material can be selected as 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.

[0250] 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.

[0251] In some embodiments, the negative electrode material includes a silicon-based material, and the added mass content of the carbonate additive in the electrolyte is 3% - 10%.

[0252] In some embodiments, the mass content of the carbonate additive in the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the numerical range between any two of them.

[0253] Silicon-based materials are prone to swelling during cycling, resulting in the rupture of the SEI film on the surface of the negative electrode material. Therefore, the consumption of additives relatively increases. The carbonate additives within the above range can improve the compactness and regeneration ability of the SEI film, taking into account the energy density and cycle stability of the battery cell.

[0254] In some embodiments, the negative electrode film layer includes a first negative electrode film layer disposed on the surface of the negative electrode current collector and a second negative electrode film layer disposed on the side of the first negative electrode film layer away from the negative electrode current collector. The second negative electrode film layer includes composite graphite particles; optionally, the negative electrode material in the first negative electrode film layer includes one or more of composite graphite particles and natural graphite.

[0255] The composite graphite particles disposed close to the electrolyte side can take into account the energy density while improving the kinetic performance of the battery cell.

[0256] 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 3:7 to 7:3.

[0257] 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 the numerical range between any two of them.

[0258] 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.

[0259] 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 the numerical range between any two of them.

[0260] 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 can be selected as 7.8 μm to 12.8 μm.

[0261] 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 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 a numerical range between any two of them.

[0262] 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.

[0263] 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 kinetic performance of the battery cell.

[0264] In some embodiments, the volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 10.8 μm, and the added mass content of the carbonate additive in the electrolyte is 3% to 8%.

[0265] In some embodiments, the volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer may be 7.8 μm, 8 μm, 8.8 μm, 9 μm, 9.8 μm, 10 μm, 10.8 μm, or a numerical range between any two of them, and the added mass content of the carbonate additive in the electrolyte may be 3%, 4%, 5%, 6%, 7%, 8%, or a numerical range between any two of them.

[0266] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC is 3% to 7%, and the added mass content of fluoroethylene carbonate FEC is 0.5% to 2%.

[0267] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC may be 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, or a numerical range between any two of them, and the added mass content of fluoroethylene carbonate FEC may be 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%, or a numerical range between any two of them.

[0268] In some embodiments, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% to 7%.

[0269] In some embodiments, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer can be selected from 10.8 μm, 11 μm, 11.8 μm, 12 μm, 12.8 μm, 13 μm, 13.8 μm, 14 μm, 14.8 μm or the numerical range between any two of them, and the added mass content of the carbonate additive in the electrolyte can be selected from 2%, 3%, 4%, 5%, 6%, 7% or the numerical range between any two of them.

[0270] A relatively small volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is beneficial to the solid-phase diffusion of lithium ions in the negative electrode active material. However, at the same time, it will increase the reaction activity between the negative electrode active material and the chain carboxylic ester solvent and increase the decomposition of the SEI film. By matching a relatively high content of carbonate additive, the compactness and regeneration ability of the SEI film on the surface of the negative electrode material can be improved, and the cycle stability of the battery monomer can be improved.

[0271] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC is 2% to 6%, and the added mass content of fluoroethylene carbonate FEC is 0.5% to 2.5%.

[0272] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC can be selected from 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or the numerical range between any two of them, and the added mass content of fluoroethylene carbonate FEC can be selected from 0.5%, 1%, 1.5%, 2%, 2.5% or the numerical range between any two of them.

[0273] 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%.

[0274] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic ester can be selected from 25.5%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 63.75% or the numerical range between any two of them.

[0275] In some embodiments, the chain carboxylic ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include at least one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms.

[0276] "C1-C5 alkyl" refers to unbranched or branched alkyl groups having 1 to 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.

[0277] "C1-C5 haloalkyl" refers to unbranched or branched alkyl groups having 1 to 5 carbon atoms in which at least one hydrogen atom is replaced by a halogen, including but not limited to one or more of chloroalkyl, bromoalkyl, iodoalkyl.

[0278] In some embodiments, the chain carboxylic acid esters include one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, methyl formate.

[0279] The electrolyte with the mass content of the chain carboxylic acid esters within the above range has both good conductivity, wettability and chemical stability, which is beneficial to the comprehensive improvement of the kinetic performance, storage stability and cycle stability of the battery monomer.

[0280] In some embodiments, the solvent further includes a carbonate solvent. Based on the total mass of the electrolyte, the mass content of the carbonate solvent accounts for 17% - 76.5%, and can be optionally 21.25% - 59.5%.

[0281] In some embodiments, the solvent further includes a carbonate solvent. Based on the total mass of the solvents in the electrolyte, the mass content of the carbonate solvent can be optionally 17%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 76.5% or the numerical range between any two of them.

[0282] In some embodiments, the carbonate solvents include one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0283] In the electrolyte, the carbonate solvents and the lithium ions in the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of the lithium ions and anions in the lithium-containing electrolyte salt, thereby improving the kinetic performance of the battery monomer.

[0284] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of ethylene carbonate to the chain carboxylic acid ester is 0.27:1 - 1.33:1.

[0285] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the chain carboxylic acid ester can be 0.27:1, 0.30:1, 0.37:1, 0.40:1, 0.47:1, 0.50:1, 0.57:1, 0.60:1, 0.67:1, 0.70:1, 0.77:1, 0.80:1, 0.87:1, 0.90:1, 0.97:1, 1:1, 1.07:1, 1.17:1, 1.27:1, 1.33:1, or the numerical range between any two of them.

[0286] The chain carboxylic acid 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. At the same time, the addition of the chain carboxylic acid ester is also beneficial to the improvement of the electrolyte conductivity; however, the chain carboxylic acid ester is prone to react with the SEI film, reducing the storage stability of the battery monomer. And the lithium ions in the ethylene carbonate in the electrolyte and the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of the 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, having a negative impact on the conductivity of the electrolyte. The mass ratio of ethylene carbonate to the chain carboxylic acid ester within the above range enables the electrolyte to have appropriate viscosity, conductivity, good dissociation rate and wettability at the same time, which is beneficial to comprehensively improving the kinetic performance and high-temperature stability of the battery monomer.

[0287] In some embodiments, the electrolyte includes a lithium salt, and the carbonate solvent includes ethylene carbonate, wherein the mass ratio of the lithium salt to the ethylene carbonate is 0.29 - 0.72.

[0288] In some embodiments, the mass ratio of the lithium salt to the ethylene carbonate can be 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 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.

[0289] The ethylene carbonate in the electrolyte and the lithium ions in the lithium-containing electrolyte salt within the above range can increase the dissociation rate of lithium ions and improve the kinetic performance of the battery monomer.

[0290] In some embodiments, the conductivity of the electrolyte is 13 mS / cm - 20 mS / cm; it can be 15 mS / cm - 20 mS / cm.

[0291] The electrolyte with conductivity within the above range can better balance the kinetic performance and high-temperature stability of the battery monomer.

[0292] In some embodiments, the lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate LiPF6; optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0293] 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 the battery cycling process, decrease the probability of side reactions at the negative electrode, and improve the cycling stability of the battery cell. However, as the temperature of the battery cell increases, 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.

[0294] In some embodiments, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. The molar concentration of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte is 0.2 mol / L - 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is 0.5 mol / L to 1.0 mol / L.

[0295] In some embodiments, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte can be optionally 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, or the numerical range between any two of them.

[0296] In some embodiments, the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte can be optionally 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, or the numerical range between any two of them.

[0297] In some embodiments, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is (2 - 5):10.

[0298] In some embodiments, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte can be optionally 2:10, 3:10, 4:10, 5:10, or the numerical range between any two of them.

[0299] A battery cell with the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte solution and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte solution within the above ranges can balance the kinetic performance and safety performance of the battery cell.

[0300] In some embodiments, the battery cell further includes a separator, which includes a porous base film and a functional layer disposed on at least one side of the porous base film. The thickness of the porous base film is ≤12 μm, and can be optionally less than or equal to 9 μm.

[0301] In some embodiments, the thickness of the porous base film can be optionally 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm or the numerical range between any two of them.

[0302] 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 can be a single-layer film or a multi-layer composite film, without particular limitation.

[0303] In some embodiments, the porosity of the porous base film in the separator is 20%-70%, and can be optionally 35%-60%.

[0304] In some embodiments, the porosity of the porous base film in the separator can be optionally 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or the numerical range between any two of them.

[0305] In some embodiments, 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 a non-fluoropolymer, 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.

[0306] In some embodiments, the inorganic particles include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, tin oxide.

[0307] The inorganic particles can improve the heat resistance of the first functional layer and the second functional layer and improve the kinetic performance of the battery cell.

[0308] In some embodiments, the non-fluoropolymer particles include acrylate copolymers.

[0309] In some embodiments, the liquid injection coefficient of the battery cell is 2.2 g / Ah - 3.1 g / Ah.

[0310] The liquid injection coefficient of a 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 a battery cell can be obtained by testing in any well-known manner in the art. Exemplarily, the mass of the electrolyte in the battery cell can be obtained 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 immerse 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 nominal capacity of the battery, or charge at a charging rate of 0.33C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C, let it 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.

[0311] In some embodiments, the liquid injection coefficient of the battery cell can be selected as 2.2 g / Ah, 2.3 g / Ah, 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.

[0312] In some embodiments, the fast charging time of the battery cell from 10% SOC to 80% SOC is 6 min to 15 min.

[0313] The fast charging time of the battery cell from 10% SOC to 80% SOC can be obtained by testing in any well-known manner in the art. As an example, at 30 °C, charging is carried out from the 10% SOC state of the battery. It is charged from 10% SOC to 15% SOC at a constant current of 5.0C, from 15% SOC to 20% SOC at a constant current of 5.0C, from 20% SOC to 25% SOC at a constant current of 5.0C, from 25% SOC to 30% SOC at a constant current of 5.0C, from 30% SOC to 35% SOC at a constant current of 5.0C, from 35% SOC to 40% SOC at a constant current of 5.0C, from 40% SOC to 45% SOC at a constant current of 4.6C, from 45% SOC to 50% SOC at a constant current of 4.3C, from 50% SOC to 55% SOC at a constant current of 4.0C, from 55% SOC to 60% SOC at a constant current of 3.7C, from 60% SOC to 65% SOC at a constant current of 3.4C, from 65% SOC to 70% SOC at a constant current of 3.1C, from 70% SOC to 75% SOC at a constant current of 2.9C, from 75% SOC to 80% SOC at a constant current of 2.7C, and the total charging time is recorded as the fast charging time. In some embodiments, the fast charging time of the battery cell from 10% SOC to 80% SOC 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 the numerical range between any two of them.

[0314] The battery cell has good fast charging performance and can meet the demand for improving the energy replenishment efficiency of the electrical device.

[0315] In some embodiments, the battery cell may include an outer package. The outer package can be used to encapsulate the above electrode assembly and electrolyte.

[0316] 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.

[0317] This application does not particularly limit the shape of the battery cell, and it can be cylindrical, square or any other shape. For example, Figure 3 is a battery cell 5 with a square structure as an example.

[0318] In some embodiments, referring to Figure 4, the outer packaging 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 a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be disposed on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may be formed into an electrode assembly 52 by 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 included in the battery cell 5 may be one or more, and those skilled in the art can select according to specific actual requirements.

[0319] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells included in the battery module may be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0320] Figure 5 is a battery module 4 as an example. Refer to Figure 5 , in the battery module 4, a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0321] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of battery cells 5 are received in the receiving space.

[0322] In some embodiments, the above battery module can be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0323] Figure 6 and Figure 7 is a battery pack 1 as an example. Refer to Figure 6 and Figure 7 , the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be disposed on the lower box body 3 and form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any way.

[0324] 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.

[0325] In addition, the present application also provides an electrical device, and the electrical device includes the battery cell provided by 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, laptops, 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.

[0326] In some embodiments, the fast charging time of the electrical device from 10% SOC to 80% SOC is 6 min to 15 min.

[0327] In some embodiments, the fast charging time of the electrical device from 10% SOC to 80% SOC 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 the numerical range between any two of them.

[0328] As the electrical device, the battery cell, battery module, or battery pack can be selected according to its usage requirements.

[0329] Figure 8 is an electrical device as an example. 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.

[0330] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thin and light design, and a battery cell can be used as the power source.

[0331] Embodiment

[0332] In order to make the technical problems, technical solutions, and beneficial effects solved by the present application clearer, the present application will be further described in detail below in conjunction with embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0333] In the examples where specific technologies or conditions are not specified, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0334] Example 1

[0335] Preparation of the positive electrode sheet

[0336] The positive electrode sheet includes a positive current collector, a positive conductive layer on the positive current collector, and a positive electrode film layer. The positive current collector is an aluminum foil with a thickness of 10 μm.

[0337] The positive conductive layer on the positive current collector is a film layer formed by uniformly mixing a positive conductive agent, superconducting carbon, a positive binder, polyvinylidene fluoride (PVDF), and a solvent, N-methylpyrrolidone (NMP), and then coating it on the surface of the current collector and drying. The thickness is 1 μm. The mass content of the positive conductive agent in the positive conductive layer is 40%, and the mass content of the positive binder is 60%.

[0338] The positive electrode film layer includes a film layer formed by uniformly coating a positive electrode paste (with a solvent of N-methylpyrrolidone, NMP) on the surface of the positive conductive layer, followed by drying and cold pressing. The positive electrode film layer includes a positive active material, a binder, polyvinylidene fluoride (PVDF), and a conductive agent, acetylene black, with a weight ratio of 97:2:1.

[0339] The positive active material includes lithium iron phosphate and a coating layer. The coating layer is coated on the surface of the lithium iron phosphate. The coating layer includes lithium iron titanium phosphate, Li2FeTi(PO4)3, and amorphous carbon. The Dv50 of the positive active material is 1.6 μm, and the Dv10 is 0.64 μm.

[0340] The single-sided coating weight of the positive electrode film layer is 300 mg / 1540.25 mm 2 。

[0341] Preparation of the negative electrode sheet

[0342] The negative electrode sheet includes a negative current collector, a negative conductive layer on the negative current collector, and a negative electrode film layer. The negative current collector is a copper foil with a thickness of 5 μm.

[0343] The negative conductive layer on the negative current collector is a film layer formed by uniformly mixing a negative conductive agent, superconducting carbon, a negative binder, styrene-butadiene rubber (SBR), a thickening agent, sodium carboxymethyl cellulose (CMC-Na), and a solvent, water, and then coating it on the surface of the negative current collector and drying. The thickness is 1 μm. The mass content of the negative conductive agent in the negative conductive layer is 35%, the mass content of the negative binder in the negative conductive layer is 60%, and the mass content of the thickening agent in the negative conductive layer is 5%.

[0344] The negative electrode film layer is formed by uniformly coating a negative electrode slurry (with deionized water as the solvent) on the surface of the negative electrode conductive layer, followed by drying and cold pressing.

[0345] The single-sided coating weight of the negative electrode film layer is 138 mg / 1540.25 mm 2 。

[0346] The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is located on the surface of the negative electrode conductive layer, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0347] The first negative electrode film layer includes graphite particles, conductive agent acetylene black, a first lithium-containing binder (a copolymer of lithium acrylate - acrylonitrile - acrylamide - 2-hydroxyethyl acrylate, where the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose, with a mass ratio of 96.5:0.5:0.5:1.5:1. The mass content of lithium element in the first lithium-containing binder is 4.8%. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer, and the carbon coating layer covers the surface of the artificial graphite, with a mass content of 3.5%.

[0348] The second negative electrode film layer includes graphite particles, conductive agent acetylene black, a second lithium-containing binder (a copolymer of lithium acrylate - acrylonitrile - acrylamide - 2-hydroxyethyl acrylate, where the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose, with a mass ratio of 97.5:0.5:0.5:0.5:1. The mass content of lithium element in the second lithium-containing binder is 4.8%. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer, and the carbon coating layer covers the surface of the artificial graphite, with a mass content of 3.5%.

[0349] Electrolyte preparation

[0350] In an argon atmosphere glove box with a water content < 10 ppm, ethylene carbonate EC, ethyl methyl carbonate EMC, and ethyl acetate EA are uniformly mixed in a mass ratio of 35:15:50 to obtain an electrolyte solvent. Lithium hexafluorophosphate (LiPF6) is slowly added as a lithium salt and stirred thoroughly until it is completely dissolved. After returning to room temperature, additives vinylene carbonate VC at 2% by mass percentage of the total mass of the electrolyte, fluoroethylene carbonate FEC at 2%, and ethylene sulfite ES at 1% are added in sequence. After thorough mixing, an electrolyte is obtained. Based on the total mass of the electrolyte, the mass ratio of the lithium salt is 15%, and the conductivity of the electrolyte is 15.4 mS / cm.

[0351] Preparation of Separator

[0352] Use a polyethylene (PE) film coated with a first functional layer of nano-aluminum oxide coating on the negative electrode side and coated with a nano-aluminum oxide coating and an acrylate copolymer on the other side as the separator. The porosity of the porous base film PE film is 35%, and the thickness of the PE film is 7 μm.

[0353] Preparation of Battery Cell

[0354] Stack and wind the positive electrode plate, separator, and negative electrode plate in sequence to obtain a wound electrode assembly. Add the electrode assembly into a square aluminum shell for outer packaging, inject electrolyte after drying. Through processes such as encapsulation, standing, formation, aging, secondary encapsulation, and capacity, the battery cell is obtained. The liquid retention coefficient d3 / A of the battery cell is 2.9 g / Ah.

[0355] The preparation methods of Examples 2-4, 9-17 are basically the same as those of Example 1, except that the composition in the electrolyte is adjusted, as shown in Table 1 specifically.

[0356] The preparation methods of Examples 5-8 are basically the same as those of Example 1, except that the Dv50 of the negative active material and / or the electrolyte components are adjusted.

[0357] The preparation methods of Examples 18-21 are basically the same as those of Example 1, except that the Dv50 of the positive active material and / or the electrolyte components are adjusted.

[0358] The preparation method of Example 22 is basically the same as that of Example 1, except that the type of the positive active material is adjusted. The ternary positive active material in Example 22 is NCM811.

[0359] The preparation method of Comparative Example 1 is basically the same as that of Example 1, and no sulfur-containing additive is added to the electrolyte.

[0360] Testing Method

[0361] Test the battery cells in the examples and comparative examples respectively. The test results are shown in Table 1.

[0362] (1) The method for storing DCR test is as follows:

[0363] ① Battery DCR Test Method

[0364] The test method of DCR can be tested according to the method in GB / T 31467 "Performance Test Specification for High-Power Lithium-Ion Power Batteries for HEV". Specifically as follows:

[0365] At 25 °C, the lithium-ion battery is charged at a constant current of 0.33 C to 3.65 V, and then left standing for 1 min; then it is charged at a constant current of 0.1 C to 3.65 V and left standing for 30 min; it is discharged at a constant current of 0.33 C to 2.0 V, and the discharge capacity A0 at this time is recorded, with the unit of Ah. Then it is charged at a constant current of 0.33 C for 0.5A0 Ah to adjust the SOC to 50%.

[0366] After the battery is placed at 25 °C for 2 h, it is discharged at a constant current of 2 C for 10 s, and ∆U is recorded 放电 and ∆I 放电 are obtained. The discharge DCR data of the lithium-ion battery is calculated by the following formula

[0367] R 放电 = ∆U 放电 / ∆I 放电

[0368] where ∆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

[0369] ② Battery high-temperature storage test method:

[0370] First, test the DCR value before high-temperature storage of the battery as D0. Then at 25 °C, the battery cell is charged at a constant current of 0.33 C to 3.65 V, and left standing for 1 min; then it is charged at a constant current of 0.1 C to 3.65 V to adjust the charge to 100% SOC, and then the battery cell is placed at 60 °C for storage. The battery is taken out every 30 days and placed at 25 °C to measure the DCR value. This is repeated, and the DCR values after storage of the battery are recorded as D1, D2…Dn respectively. The calculation method for the growth of storage DCR is: (Dn - D0) / D0, where n is 1, 2, 3, 4……n

[0371] In this application, the DCR growth rate after storage at 60 °C for 90 days is used as the test result

[0372] (2)60 °C cycle number test:

[0373] At 60 °C, the battery is charged at a charging rate of 1 C of the nominal capacity of the battery to 3.65 V, then charged at a constant voltage of 3.65 V to 0.05 C, left standing for 10 min, and then discharged at a discharge rate of 1 C to 2.5 V, left standing for 10 min. The above one charge and discharge is one cycle, and the test is stopped until the battery capacity decays to 80% of the initial discharge capacity, which is recorded as the cycle number @80% SOH

[0374] (3)Battery thermal runaway parameter test method:

[0375] ① Charge regulation: At 25 °C, charge the lithium-ion battery at a constant current of 0.33 C until 3.65 V, then let it stand for 1 min; then charge it at a constant current of 0.1 C until 3.65 V to regulate the charge of the battery to 100% SOC state.

[0376] ② Overcharge to thermal runaway test: Attach the battery with a test fixture with a clamping force of 3000 N, and then charge it at a constant current of 1 C until the battery reaches thermal runaway. After the battery cools down to room temperature, observe the state of the thermally runaway cell. If fire or explosion occurs, the thermal runaway boundary deteriorates.

[0377] The test results are shown in Table 1 - Table 3.

[0378] Table 1

[0379]

[0380] Table 2

[0381]

[0382] Table 3

[0383]

[0384] Test results

[0385] After scraping the powder of the negative electrode film layer of the formed battery monomer to obtain a powder sample, test the X-ray photoelectron spectroscopy (XPS) of the sample. The XPS spectrum test results show that there is a sulfur element 2p characteristic peak in the spectrum at a distance of 5 nm - 10 nm from the sample surface. The sulfur element 2p characteristic peak includes at least one of the first sub-peak with a binding energy of 162.5 eV - 164 eV, the second sub-peak with a binding energy of 168.5 eV - 169.5 eV, and the third sub-peak with a binding energy of 166.5 eV - 167.5 eV; while in Comparative Examples 1 and 2, the above-mentioned sulfur-containing characteristic peaks do not appear in the X-ray photoelectron spectroscopy (XPS) diagram of sulfur element 2p electrons. Compared with the comparative examples, the battery monomer in the examples has good high-temperature stability.

[0386] The XPS sulfur element spectrum results in Example 2 are as Figure 1 shown, and the XPS sulfur element spectrum results in Example 1 are as Figure 2 shown. From the comparison of the test spectrum with the standard spectrum, it can be seen that the first sub-peak with a binding energy of 162.5 eV - 164 eV corresponds to S2O3 2- , the second sub-peak with a binding energy of 168.5 eV - 169.5 eV corresponds to R-O-SO2 - , and the third sub-peak with a binding energy of 166.5 eV - 167.5 eV corresponds to SO3 2-. Since the main cations in the XPS spectrum are lithium ions, it can be known that the negative electrode active material in the battery monomer includes an inorganic sulfur-containing component with the general formula Li x S y O z and an organic sulfur-containing component of ROSO2Li at a distance of 5 nm to 10 nm from the surface, where x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

[0387] As can be seen from the comparison between Examples 1 and 9-10, based on the total mass of the electrolyte, a mass content of 3% to 8% of the carbonate additive can further balance the high-temperature storage stability and cycle life of the secondary battery.

[0388] It should be noted that the present disclosure is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same constitution and achieving the same effects as the technical idea within the technical scope of the present disclosure are included in the technical scope of the present disclosure. In addition, within the scope not departing from the gist of the present disclosure, various modifications that can be conceived by those skilled in the art to the embodiments and other modes constructed by combining some 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, a negative electrode sheet and an electrolyte; The electrolyte includes a solvent, the solvent includes a chain carboxylic ester solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode material, and the X-ray photoelectron spectrum of the negative electrode material has a sulfur element 2p characteristic peak with a binding energy located at 162 eV to 170 eV.

2. The battery cell according to claim 1, characterized in that, The sulfur element 2p characteristic peak includes at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV, a second sub-peak with a binding energy of 168.5 eV to 169.5 eV, and a third sub-peak with a binding energy of 166.5 eV to 167.5 eV.

3. The battery cell according to claim 1, characterized in that, The sulfur element 2p characteristic peak includes at least one of a first sub-peak with a binding energy of 162.5 eV to 164 eV, a third sub-peak with a binding energy of 166.5 eV to 167.5 eV, and a second sub-peak with a binding energy of 168.5 eV to 169.5 eV.

4. The battery cell according to claim 1, characterized in that, The negative electrode material includes an inorganic sulfur-containing component with the general formula Li x S y O z and an organic sulfur-containing component of ROSO2Li, where x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

5. The battery cell according to claim 1, characterized in that, The electrolyte includes a sulfur-containing additive.

6. The battery cell according to claim 5, characterized in that, The sulfur-containing additive includes one or more of sulfonate additives, sulfate additives, and sulfite additives.

7. The battery cell according to claim 5, characterized in that, The sulfur-containing additive includes one or more of sulfate additives and sulfite additives.

8. The battery cell according to claim 5, characterized in that, The sulfur-containing additive includes a sulfur-containing additive with a cyclic structure.

9. The battery cell according to claim 5, wherein The sulfur-containing additive includes one or more of Formula I, Formula II, and Formula III. Formula I Formula II Formula III Each R1 independently includes -SO2-O-, C 1-3 one or more of alkylene; each of R4 and R7 independently includes C 1-3 alkylene; R2, R3, R5, R6, R8, and R9 each independently include hydrogen, C 1-3 alkyl or one or more of the following.

10. The battery cell according to claim 5, characterized in that, Based on the total mass of the electrolyte, the mass content of the sulfur-containing additive in the electrolyte of the battery cell is 0.01% to 1%.

11. The battery cell according to claim 6, characterized in that, The sulfonate additives include one or more of 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, methylene methanedisulfonate, and its derivatives.

12. The battery cell according to claim 6, wherein, The sulfate additives include one or more of ethylene sulfate, bis(ethylene sulfate), tris(ethylene sulfate), 4-methyl-ethylene sulfate, 4-ethyl-ethylene sulfate, 4-propyl-ethylene sulfate, 4-butyl-ethylene sulfate, and its derivatives.

13. The battery cell according to claim 6, wherein, The sulfite additives include one or more of ethylene sulfite, ethylene vinyl sulfite, butene sulfite, propene sulfite, and its derivatives.

14. The battery cell according to claim 5, wherein The sulfur-containing additive includes one or more of methylene methanedisulfonate, ethylene sulfate, bis(ethylene sulfate), tris(ethylene sulfate), ethylene sulfite, butene sulfite, and its derivatives.

15. The battery cell according to claim 1, characterized in that, The volume-based median particle size Dv50 of the negative electrode material 负 is 7.8 μm - 14.3 μm.

16. The battery cell according to claim 5, wherein The volume distribution particle size Dv50 of the negative electrode material 负 is 7.8 μm to 10.8 μm, and the mass content of the sulfur-containing additive in the electrolyte is 0.3% to 2%.

17. The battery cell according to claim 5, wherein, The volume distribution particle size Dv50 of the negative electrode material 负 is 10.8 μm to 14.3 μm, and the mass content of the sulfur-containing additive in the electrolyte is 0.1% to 1.3%.

18. The battery cell according to claim 1, characterized in that, The electrolyte further includes a carbonate additive, and the carbonate additive includes one or more of vinylene carbonate and fluoroethylene carbonate.

19. The battery cell according to claim 18, wherein, The electrolyte includes vinylene carbonate and fluoroethylene carbonate.

20. The battery cell according to claim 18, wherein Based on the total mass of the electrolyte, the mass content of the carbonate additive is 2% to 10%.

21. The battery cell according to claim 18, wherein, Based on the total mass of the electrolyte, the mass content of the carbonate additive is 3% to 8%.

22. The battery cell according to claim 18, wherein, Based on the total mass of the electrolyte, the mass content of vinylene carbonate in the electrolyte is 1.5% to 8%.

23. The battery cell according to claim 18, characterized in that, Based on the total mass of the electrolyte, the mass content of vinylene carbonate in the electrolyte is 2% to 6.5%.

24. The battery cell according to claim 18, characterized in that, Based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate in the electrolyte is 0.1% to 4%.

25. The battery cell according to claim 18, characterized in that, Based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate in the electrolyte is 0.5% to 3%.

26. The battery cell according to claim 1, wherein The positive electrode plate includes a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes one or more of lithium-containing phosphates with an olivine structure and lithium-containing transition metal oxides.

27. The battery cell according to claim 26, characterized in that, The specific surface area of the positive electrode active material is 5.0 m 2 / g to 9.4 m 2 / g; the electrolyte further includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 2% - 6%.

28. The battery cell according to claim 26, wherein The specific surface area of the positive electrode active material is 9.5 m 2 / g to 18 m 2 / g; The electrolyte further includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 3% - 8%.

29. The battery cell according to claim 26, wherein The positive electrode active material includes a lithium-containing phosphate with an olivine structure, and its composition general formula is shown as Formula IV, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula IV 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.

30. The battery cell according to claim 29, wherein The specific surface area of the olivine-structured lithium-containing phosphate is 5.0 m 2 / g to 18.0 m 2 / g.

31. The battery cell according to claim 26, wherein, The positive electrode active material includes a lithium-containing transition metal oxide, and its composition general formula is shown as Formula V, Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula V wherein, 0 < x2 ≤ 2.1, 0 ≤ y2 ≤ 2.1, and 0.9 ≤ x2 + y2 ≤ 2.1; 0 ≤ a2 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ c2 ≤ 1, and 0.1 ≤ a2 + b2 + c2 ≤ 1; 1.8 ≤ z2 ≤ 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.

32. The battery cell according to claim 31, characterized in that, The specific surface area of the lithium-containing transition metal oxide is 0.1 m 2 / g to 2 m 2 / g; the electrolyte further includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive in the electrolyte is 1% - 5%.

33. The battery cell according to claim 26, characterized in that, 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 and iron elements. Based on the total mass of the positive electrode active material, the mass percentage of carbon element is 1% to 2%.

34. The battery cell according to claim 33, characterized in that, The ion-conducting layer contains a fast ion conductor with a NASICON structure shown as Formula VI, Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula VI In the Formula VI, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, 2 ≤ y3 ≤ 4.

35. The battery cell according to claim 34, wherein M2 is +4 valence.

36. The battery cell according to claim 26, wherein The positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes one or more 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 trilithium citrate.

37. The battery cell according to claim 36, characterized in that, Based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.1% - 10%.

38. The battery cell according to claim 1, characterized in that, The negative electrode material includes graphite.

39. The battery cell according to claim 38, wherein The graphite includes composite graphite particles, the composite graphite particles include a main body particle and a coating layer disposed on the surface of the main body particle, the main body particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

40. The battery cell according to claim 39, characterized in that, 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%.

41. The battery cell according to claim 1, characterized in that, The negative electrode material satisfies at least one of the following conditions: (1) The powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm; (2)The powder compaction density of the negative electrode material under a pressure of 20,000 N is 1.5 g / cm 3 to 1.8 g / cm 3 .

42. The battery cell according to claim 41, wherein The powder compaction density of the negative electrode material under a pressure of 20,000 N is 1.55 g / cm 3 to 1.75 g / cm 3 .

43. The battery cell according to claim 1, characterized in that, The negative electrode material further includes a silicon-based material, and the silicon-based material includes one or more of a silicon oxide compound and a silicon-carbon composite; based on the total mass of the negative electrode material, the mass content of silicon element in the silicon-based material is 0.3% - 10%.

44. The battery cell according to claim 43, wherein Based on the total mass of the negative electrode material, the mass content of silicon element in the silicon-based material is 1% - 6%.

45. The battery cell according to claim 1, characterized in that, The negative electrode material includes a silicon-based material, and the added mass content of the carbonate additive in the electrolyte is 3% - 10%.

46. The battery cell according to claim 1, characterized in that, The negative electrode film layer includes a first negative electrode film layer disposed on the surface of the negative electrode current collector and a second negative electrode film layer disposed on the side of the first negative electrode film layer away from the negative electrode current collector, and the second negative electrode film layer includes composite graphite particles.

47. The battery cell according to claim 46, wherein The negative electrode material in the first negative electrode film layer includes one or more of composite graphite particles and natural graphite.

48. The battery cell according to claim 46, characterized in that, The ratio of the thickness of the second negative electrode film layer to the thickness of the first negative electrode film layer is 3:7 to 7:

3.

49. The battery cell according to claim 46, wherein, The volume average particle size Dv501 of the negative electrode material in the first negative electrode film layer is 9.5 μm to 18.5 μm.

50. The battery cell according to claim 46, characterized in that, The volume average particle size Dv501 of the negative electrode material in the first negative electrode film layer is 9.5 μm to 14.8 μm.

51. The battery cell according to claim 46, wherein, The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 14.3 μm.

52. The battery cell according to claim 46, wherein, The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 12.8 μm.

53. The battery cell according to claim 46, characterized in that, The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 10.8 μm, and the added mass content of the carbonate additive in the electrolyte is 3% - 8%.

54. The battery cell according to claim 53, characterized in that, In the electrolyte, the added mass content of vinylene carbonate is 3% to 7%, and the added mass content of fluorinated ethylene carbonate is 0.5% to 2%.

55. The battery cell according to claim 46, wherein The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% - 7%.

56. The battery cell according to claim 55, characterized in that, In the electrolyte, the added mass content of vinylene carbonate is 2% to 6%, and the added mass content of fluoroethylene carbonate is 0.5% to 2.5%.

57. The battery cell according to claim 1, characterized in that, Based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic acid ester is 25.5% - 63.75%.

58. 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 at least one of an alkyl group with C1~C5 and a halogenated alkyl group with C1~C5.

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

60. The battery cell according to claim 1, characterized in that, The solvent also includes a carbonate solvent. Based on the total mass of the electrolyte, the mass content ratio of the carbonate solvent is 17% - 76.5%.

61. The battery cell according to claim 60, characterized in that, Based on the total mass of the electrolyte, the mass content ratio of the carbonate solvent is 21.25% - 59.5%.

62. The battery cell according to claim 60, wherein, The carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

63. The battery cell according to claim 60, characterized in that, The carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the chain carboxylic acid ester is 0.27:1 - 1.33:

1.

64. The battery cell according to claim 60, wherein, The electrolyte includes a lithium salt, and the carbonate solvent includes ethylene carbonate, where the mass ratio of the lithium salt to the ethylene carbonate is 0.29 - 0.

72.

65. The battery cell according to claim 1, wherein The conductivity of the electrolyte is 13 mS / cm - 20 mS / cm.

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

67. The battery cell according to claim 64, wherein The lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate.

68. The battery cell according to claim 67, wherein, The fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide.

69. The battery cell according to claim 64, characterized in that, The lithium salt includes lithium bis(fluorosulfonyl)imide I and lithium hexafluorophosphate. The molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte is 0.2 mol / L - 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate in the electrolyte is 0.5 mol / L to 1.0 mol / L.

70. The battery cell according to claim 69, wherein, The ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate in the electrolyte is (2 - 5):

10.

71. The battery cell according to claim 1, characterized in that The battery cell also 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 ≤ 12 μm.

72. The battery cell according to claim 71, wherein The thickness of the porous base film is less than or equal to 9 μm.

73. The battery cell according to claim 71, characterized in that, The porosity of the porous base film in the separator is 20% - 70%.

74. The battery cell according to claim 71, wherein The porosity of the porous base film in the separator is 35% - 60%.

75. The battery cell according to claim 71, wherein, 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, and the second functional layer includes composite particles. The composite particles include second inorganic particles and non-fluorinated polymer particles, and the second inorganic particles in the composite particles adhere to the surface of the non-fluorinated polymer particles and / or are dispersed inside the non-fluorinated polymer particles.

76. The battery cell according to claim 75, characterized in that, The non-fluorinated polymer particles include acrylate copolymers.

77. The battery cell according to claim 1, characterized in that, The liquid injection coefficient of the battery cell is 2.2 g / Ah - 3.1 g / Ah. The battery cell according to any one of claims 1 to 77, characterized in that, The fast charging time of the battery cell from 10% state of charge to 80% state of charge is 6 min to 15 min.

79. A battery device, characterized in that, Comprising the battery cell according to any one of claims 1 to 78, the battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

80. An electric device, characterized in that, Comprising the battery cell according to any one of claims 1 to 78.

Images