Battery cell, battery device, and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device. Each battery monomer comprises a positive pole piece, a negative pole piece and an electrolyte; the electrolyte comprises a solvent, the solvent comprises a chain carboxylic ester solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; the negative electrode piece comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode material, and the X-ray photoelectron spectroscopy (XPS) of the negative electrode material has a sulfur element 2p characteristic peak with binding energy of 162eV-170eV.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to PCT patent application PCT / CN2024 / 106829, entitled “Battery Cell, Battery Device, and Electrical Device,” filed on July 22, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the technical field of battery cells, and in particular to a battery cell, a battery device and an electrical device. Background Art

[0003] In recent years, battery monomers have been widely used in energy storage power systems such as hydropower, thermal, wind and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0004] With the market's increasing demands for energy efficiency and service life in special environments, higher requirements are also placed on the dynamic performance and high-temperature stability of battery cells. However, it is difficult to achieve simultaneous improvements in the above performance in the existing technology, which has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The present application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell and an electric device that can improve the dynamic performance of the battery cell while taking into account the high temperature stability of the battery cell.

[0006] In a first aspect, the present application provides a battery cell, comprising a positive electrode plate, a negative electrode plate and an electrolyte; the electrolyte comprises a solvent, the solvent comprises a chain carboxylic acid ester solvent, and the conductivity of the electrolyte is 13mS / cm to 20mS / cm; the negative electrode plate comprises a negative electrode collector and a negative electrode film layer arranged on at least one side of the negative electrode collector, the negative electrode film layer comprises a negative electrode material, and the negative electrode material has a characteristic peak of sulfur element 2p with a binding energy of 162eV~170eV in X-ray photoelectron spectroscopy (XPS).

[0007] Electrolytes that include chain carboxylic acid ester solvents and have a conductivity of 13mS / cm-20mS / cm are beneficial to improving the kinetic performance of the battery, but chain carboxylic acid ester solvents are often highly active and will continuously corrode the solid electrolyte membrane (SEI membrane) on the surface of the negative electrode material during storage, resulting in the continuous loss and regeneration of the SEI membrane and the continuous growth of the DC internal resistance of the battery cell during storage. The SEI membrane contains sulfur, which can improve the corrosion resistance of the SEI membrane and its thermal stability at high temperatures, taking into account the kinetic performance and storage stability of the battery cell.

[0008] In any embodiment, the characteristic peak of sulfur element 2p includes at least one of a first subpeak with a binding energy of 162.5eV~164eV, a second subpeak with a binding energy of 168.5eV~169.5eV, and a third subpeak with a binding energy of 166.5eV~167.5eV. Optionally, the characteristic peak of sulfur element 2p includes at least one of a first subpeak with a binding energy of 162.5eV~164eV, a third subpeak with a binding energy of 166.5eV~167.5eV, and a second subpeak with a binding energy of 168.5eV~169.5eV.

[0009] The standard spectrum and electron splitting energy level analysis show that the first sub-peak with a binding energy of 162.5 eV to 164 eV corresponds to the component of thiosulfate (S 2 O 3 2- ), the second sub-peak with a binding energy of 168.5 eV~169.5 eV corresponds to the component of alkoxysulfite (RO-SO 2 - ), the third sub-peak with a binding energy of 166.5eV~167.5eV corresponds to the component of sulfite (SO 3 2- Thiosulfate and sulfite are inorganic acid radicals that can improve the corrosion resistance and thermal stability of the SEI film on the surface of the negative electrode material at high temperatures; alkoxysulfite (RO-SO 2 - ) is an organic acid radical that can improve the toughness of the SEI film on the surface of the negative electrode material. The combination of the two can take into account both the dynamic performance and storage stability of the battery cell.

[0010] In any embodiment, the negative electrode material comprises a general formula of Li x S y O z Inorganic sulfur components and ROSO 2 The organic sulfur-containing component of Li, wherein x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

[0011] The general formula is Li x S y O z The inorganic sulfur-containing components 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 easy to rupture during the cycle; the general formula is ROSO 2 The organic sulfur-containing components of Li will improve the toughness of the SEI film, thereby improving the toughness of the SEI film on the surface of the negative electrode material. The combination of the two can take into account both the dynamic performance and storage stability of the battery cell.

[0012] In any embodiment, the electrolyte includes a sulfur-containing additive. Optionally, the sulfur-containing additive includes one or more of a sulfonate additive, a sulfate additive, and a sulfite additive. Optionally, the sulfur-containing additive includes one or more of a sulfate additive and a sulfite additive.

[0013] Sulfur-containing additives often have a higher potential. Sulfur-containing additives added to the electrolyte will react preferentially during formation or subsequent cycles and evolve into sulfur-containing components in the SEI film. Including sulfur-containing additives in the electrolyte can take into account both the kinetic performance and storage stability of the battery cell.

[0014] In any embodiment, the sulfur-containing additive includes a cyclic structure sulfur-containing additive.

[0015] The sulfur-containing additive with a ring structure has a suitable decomposition potential and is easier to form a film on the surface of the negative electrode material, thereby improving the storage stability of the battery cell.

[0016] In any embodiment, the sulfur-containing additive comprises one or more of Formula I, Formula II, and Formula III, Formula I Formula II Formula III R 1 Each independently includes -SO 2 -O-, C 1-3 One or more of alkylene; R 4 , R 7 Each independently includes C 1-3 Alkylene; R 2 , R 3 , R 5 , R 6 , R 8 , R 9 Each independently comprises hydrogen, C 1-3 alkyl, One or more of .

[0017] 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% to 1%.

[0018] The electrolyte in which the mass content of the sulfur-containing additive in the electrolyte of the battery monomer is within the above range is beneficial to strengthening the SEI film during the cycle process, taking into account the dynamic performance and storage stability of the battery monomer.

[0019] In any embodiment, the sulfonate additive includes one or more of 1,3-propane sultone (PS), 1,3-propylene sultone (PES), 1,4-butane sultone (1,4-BS), methylene methane disulfonate (MMDS) and derivatives thereof.

[0020] In any embodiment, the sulfate ester additive includes one or more of vinyl sulfate (DTD), divinyl sulfate (2-DTD), trivinyl sulfate (3-DTD), 4-methyl-vinyl sulfate, 4-ethyl-vinyl sulfate, 4-propyl-vinyl sulfate, 4-butyl-vinyl sulfate and their derivatives.

[0021] In any embodiment, the sulfite additive includes one or more of ethylene sulfite (ES), vinyl vinyl sulfite (VES), butylene sulfite (BS), propylene sulfite (TMS) and derivatives thereof.

[0022] In any embodiment, the sulfur-containing additive includes one or more of methylene methanedisulfonate (MMDS), diethylene sulfate (DTD), diethylene disulfate (2-DTD), triethylene trisulfate (3-DTD), vinyl sulfite (ES), butylene sulfite (BS) and their derivatives.

[0023] In any embodiment, the volume distribution particle size Dv50 of the negative electrode material 负 7.8μm-14.3μm.

[0024] Dv50 负 The negative electrode active material within the above range includes a certain amount of small particles and large particles at the same time, so that the battery cell can not only improve the transmission rate of lithium ions and improve the kinetic performance through small particles, but also improve the compaction density of the battery cell pole piece through the grading of large and small particles, improve the energy density of the battery cell, and achieve a balance between kinetic performance and energy density.

[0025] In any embodiment, the volume distribution particle size Dv50 of the negative electrode material 负 The particle size 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%.

[0026] 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 dynamic performance of the battery cell. 负The negative electrode active material within the above range has a relatively large surface area and surface activity, and has a relatively stronger reaction activity with the chain carboxylic acid ester solvent. Therefore, a higher content of sulfur-containing additives is required in the electrolyte to achieve a balance between kinetic performance and storage stability.

[0027] In any embodiment, 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%.

[0028] 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.

[0029] The sulfur-containing components on the surface of the negative electrode material will increase the brittleness of the SEI film while improving the high-temperature stability of the SEI film. Carbonate additives can evolve into organic components in the SEI film, improve the toughness of the SEI film, and work together with the sulfur-containing components in the SEI film to improve the stability of the SEI film during the battery cell cycle and improve the cycle life of the battery cell.

[0030] In any embodiment, the electrolyte includes vinylene carbonate VC and fluoroethylene carbonate FEC.

[0031] Chain carboxylates are highly active, which improves the wettability between the electrolyte and the electrode, improves the conductivity of the electrolyte, and also corrodes the solid electrolyte membrane (SEI membrane). Vinylene carbonate VC has a reduction potential close to that of chain carboxylates, which can inhibit the reaction activity of chain carboxylates, improve the compactness of the SEI membrane, and improve the cycle 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 membrane. By adding sulfur-containing additives, vinylene carbonate VC and fluoroethylene carbonate FEC to the electrolyte, the dynamic performance, storage stability and cycle life of the battery cell can be more effectively taken into account.

[0032] 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%.

[0033] The electrolyte with the mass content of carbonate additives within the above range can not only improve the cycle stability of the SEI film, but also control the degree of side reactions, thereby comprehensively improving the cycle life of the battery cell.

[0034] 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%.

[0035] 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%.

[0036] By adding vinylene carbonate VC and fluoroethylene carbonate FEC to the electrolyte, the kinetic performance and cycle stability of the battery monomer can be effectively taken into account.

[0037] 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 an olivine-structured lithium-containing phosphate and a lithium-containing transition metal oxide.

[0038] In any embodiment, the specific surface area of ​​the positive electrode 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 to the electrolyte is 2%-6%.

[0039] In any embodiment, the specific surface area of ​​the positive electrode active material is 9.5 m 2 / g ~18m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte is 3%-8%.

[0040] Positive electrode active materials with large specific surface areas have large contact areas with electrolytes, which can improve the dynamic performance of battery cells. However, positive electrode active materials with large specific surface areas are more likely to absorb water molecules in the air, and water molecules are difficult to be discharged from the positive electrode film layer during the drying and film forming process. During the cycle of battery cells, water molecules react with electrolyte salts in the electrolyte to generate hydrofluoric acid, which corrodes the SEI film on the surface of the negative electrode material. Positive electrode active materials with high specific surface areas generate high levels of hydrofluoric acid in battery cells. High levels of carbonate additives can improve the compactness of the SEI film on the surface of the negative electrode material, taking into account both the dynamic performance and cycle stability of the battery cells.

[0041] In any embodiment, the positive electrode active material includes an olivine-structured lithium-containing phosphate, and its general composition formula is as shown in Formula IV: Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula IV, 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.

[0042] 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.

[0043] 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.

[0044] 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, Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula V 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.

[0045] 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%.

[0046] In any embodiment, the positive electrode active material further includes an ion conductive layer disposed on the surface of the lithium-containing phosphate, the ion conductive layer includes carbon and iron, and the mass percentage of the carbon element is 1% to 2% based on the total mass of the positive electrode active material.

[0047] The ion-conducting layer can simultaneously improve the ion conductivity and electrical conductivity of the positive electrode active material, improve the solid-phase transmission rate of ions and electrons, and improve the dynamic performance of the battery cell.

[0048] In any embodiment, the ion-conducting layer comprises a fast ion conductor having a NASICON structure as shown in 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. Optionally, M2 has a valence of +4, 0≤b3≤1, 3≤x3≤5, and 2≤y3≤4.

[0049] Fast ion conductors with NASICON structures have abundant three-dimensional lithium ion diffusion and transmission channels, and have the advantages of high ion conduction efficiency and strong structural stability during multiple lithium stripping and insertion processes. Coating fast ion conductors with NASICON structures on the surface of lithium-containing phosphates can significantly increase the transmission rate of lithium ions during multiple stripping / insertion of lithium at the positive terminal, improve the ionic conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cells.

[0050] 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, dilithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, and trilithium citrate.

[0051] Adding a lithium supplement to the positive electrode active layer can offset the irreversible lithium loss in the electrochemical process to increase the total capacity and energy density of the battery cell.

[0052] In any embodiment, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement agent is 0.1%-10%.

[0053] In any embodiment, the negative electrode material includes graphite.

[0054] In any embodiment, the graphite includes composite graphite particles, the composite graphite particles include main particles and a coating layer disposed on the surface of the main particles, the main particles include artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0055] The composite graphite particles including secondary particles and the surface coating layer including amorphous carbon are both beneficial to the infiltration of the electrolyte into the negative electrode active layer of the pole piece, and contribute to the improvement of the rate performance of the battery cell.

[0056] In any embodiment, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5% based on the total mass of the composite graphite particles.

[0057] When the content of amorphous carbon is within a suitable range, the composite graphite material can have a high gram capacity and a high active ion solid phase transport capacity, which is beneficial to the improvement of the kinetic performance of the battery cell.

[0058] In any embodiment, the powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm.

[0059] In any embodiment, the powder compaction density of the negative electrode material under a pressure of 20000N is 1.5g / cm 3 Up to 1.8g / cm 3 , optional 1.55g / cm 3 Up to 1.75g / cm 3 .

[0060] Negative electrode materials with powder compaction density within an appropriate 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, the negative electrode active layer can maintain its original pore structure during the cycle process, which is beneficial to improving the high dynamic performance of the battery cell during the cycle process.

[0061] In any embodiment, the negative electrode material also 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 active material, the mass content of silicon element in the silicon-based material is 0.3%-10%, and can be optionally 1%-6%.

[0062] The introduction of silicon-based materials is conducive to improving the energy density of battery cells. Silicon-based materials within the above mass range can take into account both the energy density and cycle stability of battery cells.

[0063] In any embodiment, the negative electrode material includes a silicon-based material, and the added mass content of the carbonate additive in the electrolyte is 3%-10%.

[0064] Silicon-based materials are prone to expansion during the cycle process, causing the SEI film on the surface of the negative electrode material to rupture, so the consumption of additives is greater. The carbonate additives within the above range can improve the density and regeneration ability of the SEI film, taking into account the energy density and cycle stability of the battery cell.

[0065] In any embodiment, the negative electrode film layer includes a first negative electrode film layer arranged on the surface of the negative electrode current collector and a second negative electrode film layer arranged 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; optionally, the negative electrode material in the first negative electrode film layer includes one or more of composite graphite particles and natural graphite.

[0066] The composite graphite particles are arranged close to the electrolyte side to improve the dynamic performance of the battery cell while taking into account the energy density.

[0067] In any embodiment, a ratio of a thickness of the second negative electrode active material layer to a thickness of the first negative electrode active material layer is 3:7 to 7:3.

[0068] In any embodiment, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active material layer is 1 It is 9.5μm~18.5μm, and can be selected as 9.5μm~14.8μm.

[0069] In any embodiment, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer 2 It is 7.8μm~14.3μm, and can be selected as 7.8μm~12.8μm.

[0070] The second negative electrode active material layer disposed on the electrolyte side includes negative electrode active materials with smaller particle sizes, which can further increase the solid-liquid transmission rate of ions in the battery pole piece and improve the dynamic performance of the battery cell.

[0071] In any embodiment, the volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer is 2 The particle size is 7.8 μm to 10.8 μm, and the added mass content of the carbonate additive in the electrolyte is 3% to 8%.

[0072] 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%.

[0073] In any embodiment, the volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer is 2The particle size is 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% to 7%.

[0074] The volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer 2 A relatively small content is conducive to the solid phase diffusion of lithium ions in the negative electrode active material, but at the same time it will increase the reactivity of the negative electrode active material with 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.

[0075] 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%.

[0076] In any embodiment, based on the total mass of the electrolyte, the mass content of the chain carboxylic acid ester accounts for 25.5%-63.75%.

[0077] In any embodiment, the chain carboxylic acid ester has R 1 -COO-R 2 The general structural formula is 1 and R 2 Each independently includes C 1 ~C 5 The alkyl and C 1 ~C 5 At least one of the halogenated alkyl groups.

[0078] In any embodiment, the linear carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

[0079] The electrolyte with a mass content of chain carboxylic acid ester within the above range has good conductivity, wettability and chemical stability, which is beneficial to the comprehensive improvement of the battery monomer kinetics, storage stability and cycle stability.

[0080] In any embodiment, the solvent further includes a carbonate solvent, and 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%.

[0081] In any embodiment, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

[0082] The carbonate solvent in the electrolyte and the lithium ions in the lithium-containing electrolyte salt easily 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 cell.

[0083] In any embodiment, the carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the linear carboxylic acid ester is 0.27:1-1.33:1.

[0084] Chain carboxylates can improve the wettability between the electrolyte and the pole piece, improve the solid-liquid transfer rate of lithium ions between the electrolyte and the pole piece, and the addition of chain carboxylates is also beneficial to the improvement of the conductivity of the electrolyte; however, chain carboxylates are easy to react with the SEI film, reducing the storage stability of the battery cell. The ethylene carbonate in the electrolyte and the lithium ions in the lithium-containing electrolyte salt are easy to form a solvation structure to increase the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt, but the viscosity of the electrolyte will also increase with the increase of the ethylene carbonate content, which has a negative impact on the conductivity of the electrolyte. The mass ratio of ethylene carbonate to the chain carboxylates within the above range allows the electrolyte to have both suitable viscosity, conductivity, good dissociation rate and wettability, which is beneficial to comprehensively improve the dynamic performance and high temperature stability of the battery cell.

[0085] 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.

[0086] 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 the lithium ions and improve the dynamic performance of the battery monomer.

[0087] In any embodiment, the conductivity of the electrolyte is 13mS / cm-20mS / cm; optionally 15mS / cm-20mS / cm.

[0088] The electrolyte with conductivity within the above range can better balance the dynamic performance and high temperature stability of the battery cell.

[0089] In any embodiment, the lithium salt comprises a fluorine-containing sulfonyl imide salt and lithium hexafluorophosphate LiPF 6 One or more of; optionally, the fluorine-containing sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0090] Fluorinated sulfonyl imide salts are easy to dissociate in electrolyte solvents, which is beneficial to improving the conductivity of the electrolyte. Fluorinated sulfonyl imide salts have high chemical stability and are not easy to decompose during recycling. They can reduce the production of hydrogen fluoride during battery cycling, reduce the probability of negative electrode side reactions, and improve the cycle stability of battery cells. However, with the increase in the temperature of the battery cells, fluorinated sulfonyl imide salts will undergo violent decomposition and release a large amount of heat at a certain temperature threshold, 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 cycle, the addition of lithium hexafluorophosphate will greatly reduce the risk of thermal runaway of battery cells, reducing the risk to a controllable range and improving the safety of the battery.

[0091] In any embodiment, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF 6 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 LiPF in the electrolyte is 0.2 mol / L-0.5 mol / L. 6 The molar concentration is 0.5 mol / L to 1.0 mol / L.

[0092] In any embodiment, the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate LiPF in the electrolyte 6 The molar concentration ratio is (2-5):10.

[0093] The molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the lithium hexafluorophosphate LiPF in the electrolyte 6 The battery monomer having a molar concentration within the above range can take into account both the dynamic performance and safety performance of the battery monomer.

[0094] In any embodiment, the battery cell further includes a separator, the separator includes a porous base membrane and a functional layer disposed on at least one side of the porous base membrane, and the thickness of the porous base membrane is ≤12 μm, and can be optionally less than or equal to 9 μm.

[0095] In any embodiment, the porosity of the porous base film in the isolation membrane is 20%-70%, and can be optionally 35%-60%.

[0096] In any embodiment, the functional layer includes a first functional layer arranged on the negative electrode side of the porous base membrane and a second functional layer arranged on the positive electrode side of the porous base membrane, the first functional layer includes first inorganic particles, the second functional layer includes composite particles, the composite particles include second inorganic particles and non-fluoropolymers, and the second inorganic particles in the composite particles are attached to the surface of the non-fluoropolymer particles and / or dispersed in the interior of the non-fluoropolymer particles.

[0097] The inorganic particles can enhance the heat resistance of the first functional layer and the second functional layer and improve the dynamic performance of the battery cell.

[0098] In any embodiment, the non-fluoropolymer particles include an acrylate copolymer.

[0099] In any embodiment, the liquid filling coefficient of the battery cell is 2.2 g / Ah-3.1 g / Ah.

[0100] In any embodiment, the fast charging time of the battery cell from 10% SOC to 80% SOC is 6 min to 15 min.

[0101] A second aspect of the present application provides a battery device, including the battery cell provided by the first aspect of the present application, and the battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0102] A third aspect of the present application provides an electrical device, comprising the battery cell provided in the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Figure 1 This is an X-ray photoelectron spectrum of sulfur element in the negative electrode material according to one embodiment of the present application.

[0104] Figure 2 This is an X-ray photoelectron spectrum of sulfur element in the negative electrode material according to another embodiment of the present application.

[0105] Figure 3 is a schematic diagram of a battery cell according to another embodiment of the present application.

[0106] Figure 4 yes Figure 3 An exploded view of a battery cell according to an embodiment of the present application is shown.

[0107] Figure 5 is a schematic diagram of a battery module according to an embodiment of the present application.

[0108] Figure 6 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0109] Figure 7 yes Figure 6 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0110] Figure 8 It is a schematic diagram of an electrical device using a battery cell according to an embodiment of the present application as a power source.

[0111] Description of reference numerals: 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0112] Hereinafter, the battery cells and the electric devices of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same 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 descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0113] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. 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 scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0114] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0115] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0116] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0117] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0118] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0119] In order to improve the dynamic performance of battery cells, solvents with high conductivity, such as chain carboxylic acid ester solvents, are often added to the electrolyte to achieve rapid ion transmission and reduce the possibility of lithium precipitation. However, high-conductivity solvents are often highly active and will continuously corrode the solid electrolyte membrane (SEI membrane) on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI membrane of the battery cell during storage, an increase in the DC internal resistance of the battery cell, and a decrease in the stability of the battery cell.

[0120] Based on this, the present application proposes a battery cell, comprising a positive electrode plate, a negative electrode plate and an electrolyte; the electrolyte comprises a solvent, the solvent comprises a chain carboxylic acid ester solvent, and the conductivity of the electrolyte is greater than or equal to 13mS / cm; the negative electrode plate comprises a negative electrode collector and a negative electrode film layer arranged on at least one side of the negative electrode collector, the negative electrode film layer comprises a negative electrode material, and the negative electrode material has a characteristic peak of sulfur element 2p with a binding energy of 162eV~170eV in its X-ray photoelectron spectrum (XPS).

[0121] In the present application, the X-ray photoelectron spectroscopy (XPS) of the negative electrode material can be tested by any known method in the art. As an example, after the battery cell is disassembled, the negative electrode plate is cleaned with a solvent such as dimethyl carbonate DMC for more than three times, and then the powder is scraped and sampled. The obtained negative electrode material sample powder is adhered to a conductive substrate, and an X-ray photoelectron spectrometer (such as AXIS ULTRA) is used to perform an X-ray photoelectron spectroscopy test, and the scanning rate and time of the X-ray source are adjusted so that it is focused and detects elements and functional groups at a depth of 5nm to 10nm from the surface of the negative electrode material, and the X-ray photoelectron spectroscopy (XPS) spectrum of the sample is obtained, and the characteristic peaks of the elements are analyzed in the spectrum.

[0122] The chain carboxylate solvent refers to a chain-shaped organic molecule containing a carboxylate group, and includes, by way of example, but is not limited to, propyl butyrate, ethyl butyrate, methyl butyrate, ethyl propionate, methyl propionate, ethyl acetate, methyl acetate, methyl formate, and the like.

[0123] The type and quality of the solvent in the electrolyte can be obtained by detecting the electrolyte by methods known to those skilled in the art. For example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible photometry, etc. Exemplarily, the battery cell is disassembled, and the free electrolyte is obtained from the battery cell. The free electrolyte in the battery cell is diluted to 3 to 10 times with acetonitrile to obtain the electrolyte dilution to be tested. The GC-MS 3100 organic component gas chromatograph is used to place the above electrolyte dilution in the instrument for full scan qualitative analysis. The injection port temperature is 250°C, and the scanning range is: 35μm~270μm. After the test is completed, the total ion flow chromatogram of each organic matter is obtained, and the corresponding organic type is compared according to the peak position of the chromatogram, and the corresponding content percentage of each organic matter is calculated according to the peak area.

[0124] The conductivity of the electrolyte is the ability to describe the conductive process formed by the directional movement of positive and negative ions dissociated from the electrolyte solution in the electric field, and can be tested by any known method in the art. As an example, take about 100mL of electrolyte sample in a dry, clean, corrosion-resistant sample bottle, seal it in a constant temperature water bath, shake the sample from time to time, and keep the temperature constant at 25°C (deviation ±5°C). After the sample temperature is constant, use a commercially available conductivity meter to test its conductivity. After the conductivity meter is wiped clean with calibration fluid, place it vertically in the liquid to be tested, click to start the test, and record the test results after the data is stable for more than 10 seconds.

[0125] In some embodiments, the conductivity of the electrolyte may be 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 range therebetween.

[0126] An electrolyte comprising a chain carboxylic acid ester solvent and having a conductivity of 13mS / cm-20mS / cm is beneficial to improving the kinetic performance of a battery cell. However, chain carboxylic acid ester solvents are often highly active and will continuously corrode the solid electrolyte membrane (SEI membrane) on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI membrane and continuous growth of the DC internal resistance during storage of the battery cell. The SEI membrane on the surface of the negative electrode material of the battery cell of the present application contains sulfur, which can improve the corrosion resistance and thermal stability of the SEI membrane at high temperatures, taking into account both the kinetic performance and storage stability of the battery cell.

[0127] In some embodiments, the characteristic peak of sulfur element 2p includes at least one of a first subpeak with a binding energy of 162.5eV~164eV, a second subpeak with a binding energy of 168.5eV~169.5eV, and a third subpeak with a binding energy of 166.5eV~167.5eV. Optionally, the characteristic peak of sulfur element 2p includes at least one of a first subpeak with a binding energy of 162.5eV~164eV, a third subpeak with a binding energy of 166.5eV~167.5eV, and a second subpeak with a binding energy of 168.5eV~169.5eV.

[0128] The characteristic peak of sulfur 2p 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 characteristic peak of S2p spectrum can be processed by XPSpeak software to obtain sub-peaks. The standard spectrum and electron splitting energy level analysis show that the first sub-peak with a binding energy of 162.5eV~164eV corresponds to the component of thiosulfate (S 2 O 3 2- ), the second sub-peak with a binding energy of 168.5 eV~169.5 eV corresponds to the component of alkoxysulfite (RO-SO 2 - ), the third sub-peak with a binding energy of 166.5eV~167.5eV corresponds to the component of sulfite (SO 3 2- Thiosulfate and sulfite are inorganic acid radicals that can improve the corrosion resistance and thermal stability of the SEI film on the surface of the negative electrode material at high temperatures; alkoxysulfite (RO-SO 2- ) is an organic acid radical that can improve the toughness of the SEI film on the surface of the negative electrode material. The combination of the two can take into account the dynamic performance, storage stability and cycle life of the battery cell.

[0129] In some embodiments, the negative electrode material includes a general formula of Li x S y O z Inorganic sulfur components and ROSO 2 The organic sulfur-containing component of Li, wherein x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

[0130] The XPS full spectrum test of the negative electrode material shows that the cations at the distance from the surface of the negative electrode material are mainly lithium ions. Therefore, it can be inferred that the negative electrode material includes the general formula Li x S y O z Inorganic sulfur components and ROSO 2 Li organic sulfur-containing components.

[0131] In some embodiments, x can be selected from 1, 2, 3 or any range therebetween, y can be selected from 1, 2, 3 or any range therebetween, z can be selected from 2, 3, 4, 5, 6 or any range therebetween, and R is a substituted or unsubstituted alkyl group, including but not limited to methyl, ethyl, propyl, butyl, etc.

[0132] The general formula is Li x S y O z The inorganic sulfur-containing components 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 easy to rupture during the cycle; the general formula is ROSO 2 The organic sulfur-containing components of Li will improve the toughness of the SEI film, thereby improving the toughness of the SEI film on the surface of the negative electrode material. The combination of the two can take into account the dynamic performance, storage stability and cycle life of the battery cell.

[0133] In some embodiments, the electrolyte includes a sulfur-containing additive. Optionally, the sulfur-containing additive includes one or more of a sulfonate additive, a sulfate additive, and a sulfite additive. Optionally, the sulfur-containing additive includes one or more of a sulfate additive and a sulfite additive.

[0134] Additives refer to components with low content in the electrolyte, which generally account for no more than 10% of the mass of the electrolyte. They are highly targeted and used in small amounts, and can significantly optimize the performance of a certain aspect of the battery without changing the production process.

[0135] The components of the additive can be obtained by testing in any known manner in the art, for example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible photometry, etc. Exemplarily, the inorganic content in the electrolyte can be tested using an ion chromatograph (IC), a quantitative electrolyte is weighed (the dilution concentration is in the middle of the standard curve), the volume is made up to 100 mL with ultrapure water, the ion chromatograph is automatically injected and tested, the inorganic ion chromatogram is tested, and the corresponding inorganic species are compared according to the peak position of the chromatogram. The above-mentioned free electrolyte is diluted to 3~10 times with acetonitrile to obtain the electrolyte dilution to be tested, and the above-mentioned electrolyte dilution is placed in the instrument for full scan qualitative analysis using a GC-MS 3100 organic component gas chromatograph, the injection port temperature is 250℃, the scanning range is: 35μm~270μm, and the total ion flow chromatogram of each organic matter is obtained after the test is completed, and the corresponding organic species are compared according to the peak position of the chromatogram.

[0136] In this application, sulfonate additives refer to additives containing sulfonate groups (-SO 2 -O-) compounds and their derivatives, and mixtures containing the above compounds and their derivatives. Including sulfonate groups (-SO 2 -O-) can be a chain compound or a cyclic compound. Sulfonate additives can form thiosulfate (S 2 O 3 2- ), sulfite (SO 3 2- ) and at least one of the alkoxysulfites (RO-SO 2 - ), so that the negative electrode material has at least one of a first subpeak with a binding energy of 162.5eV~164eV, a third subpeak with a binding energy of 166.5eV~167.5eV, and a second subpeak with a binding energy of 168.5eV~169.5eV in the X-ray photoelectron spectrum (XPS) at a distance of 5nm~10nm from the surface.

[0137] In this application, sulfate ester additives refer to those containing sulfate ester groups (-O-SO 2 -O-) compounds and their derivatives, and mixtures containing the above compounds and their derivatives. 2 -O-) can be a chain compound or a cyclic compound. Sulfate ester additives can form alkoxysulfite (RO-SO 2 - ), thiosulfate (S 2 O 32- ) and sulfite (SO 3 2- ), which results in the negative electrode material having a second subpeak with a binding energy of 168.5eV~169.5eV, a first subpeak with a binding energy of 162.5eV~164eV, and a third subpeak with a binding energy of 166.5eV~167.5eV in the X-ray photoelectron spectrum (XPS) at a distance of 5nm~10nm from the surface.

[0138] In this application, sulfite additives refer to compounds including sulfite groups (-O-SO-O-) and their derivatives, as well as mixtures containing the above compounds and their derivatives. The compounds including sulfite groups (-O-SO-O-) can be chain compounds or cyclic compounds. Sulfite additives can form alkoxysulfite groups (RO-SO 2 - ) and thiosulfate (S 2 O 3 2- ), which results in the negative electrode material having a second subpeak with a binding energy of 168.5eV~169.5eV and a first subpeak with a binding energy of 162.5eV~164eV in the X-ray photoelectron spectroscopy (XPS) at a distance of 5nm~10nm from the surface.

[0139] Sulfur-containing additives often have a higher potential. Sulfur-containing additives added to the electrolyte will react preferentially during the formation or subsequent cycle process and evolve into sulfur-containing components in the SEI film. It is understandable 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, sulfur-containing additives still remain in the electrolyte, which form a reinforcement effect on the SEI film during the subsequent battery cell cycle process.

[0140] Including sulfur-containing additives in the electrolyte can take into account both the kinetic performance and storage stability of the battery cells.

[0141] In some embodiments, the sulfur-containing additive includes a cyclic structure sulfur-containing additive.

[0142] The cyclic sulfur-containing additive refers to a heterocyclic compound structure in which the atoms in the molecule are arranged in a ring and include sulfur atoms. The cyclic sulfur-containing additive has a suitable decomposition potential and is easier to form a film on the surface of the negative electrode material, thereby improving the storage stability of the battery cell.

[0143] In some embodiments, the sulfur-containing additive comprises one or more of Formula I, Formula II, and Formula III, Formula I Formula II Formula III R 1 Each independently includes -SO 2 -O-, C 1-3 One or more of alkylene; R 4 , R 7 Each independently includes C 1-3 Alkylene; R 2 , R 3 , R 5 , R 6 , R 8 , R 9 Each independently comprises hydrogen, C 1-3 alkyl, One or more of .

[0144] In this application, C 1-3 Alkylene refers to an alkylene group comprising 1 to 3 carbon atoms, including but not limited to methylene, ethylene, and propylene.

[0145] In this application, C 1-3 Alkyl refers to an alkyl group including 1 to 3 carbon atoms, including but not limited to methyl, ethyl, and propyl.

[0146] In some embodiments, the mass content of the sulfur-containing additive in the electrolyte of the battery cell is 0.01% to 1% based on the total mass of the electrolyte.

[0147] 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 monomer may be 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 any numerical range therebetween.

[0148] The type and quality of the sulfur-containing additive in the electrolyte can be obtained by detecting the electrolyte by methods known to those skilled in the art. For example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible photometry, etc. Exemplarily, an ion chromatograph (IC) is used to test the inorganic content in the electrolyte, a quantitative electrolyte is weighed (the dilution concentration is in the middle of the standard curve), and the volume is made up to 100 mL with ultrapure water. The ion chromatograph is automatically injected for detection, and the inorganic ion chromatogram is tested. The corresponding inorganic type is compared according to the peak position of the chromatogram, and the corresponding inorganic ion content percentage is calculated according to the peak area. The above-mentioned free electrolyte was diluted to 3~10 times with acetonitrile to obtain the electrolyte dilution to be tested. The above-mentioned electrolyte dilution was placed in the instrument for full scan qualitative analysis using a GC-MS 3100 organic component gas chromatograph. The injection port temperature was 250℃, and the scanning range was 35μm~270μm. After the test was completed, the total ion flow chromatogram of each organic matter was obtained. The type of organic matter corresponding to the peak position of the chromatogram was compared, and the corresponding content percentage of each organic matter was calculated according to the peak area. The mass of the sulfur-containing additive obtained by the measurement was divided by the mass of the electrolyte sample as 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.

[0149] The electrolyte in which the mass content of the sulfur-containing additive in the electrolyte of the battery monomer is within the above range is beneficial to strengthening the SEI film during the cycle process, taking into account the dynamic performance, storage stability and cycle stability of the battery monomer.

[0150] In some embodiments, the sulfonate additive includes one or more of 1,3-propane sultone (PS), 1,3-propylene sultone (PES), 1,4-butane sultone (1,4-BS), methylene methane disulfonate (MMDS) and derivatives thereof.

[0151] In some embodiments, the sulfate ester additive includes one or more of vinyl sulfate (DTD), divinyl sulfate (2-DTD), trivinyl sulfate (3-DTD), 4-methyl-vinyl sulfate, 4-ethyl-vinyl sulfate, 4-propyl-vinyl sulfate, 4-butyl-vinyl sulfate and their derivatives.

[0152] In some embodiments, the sulfite additive includes one or more of ethylene sulfite (ES), vinyl vinyl sulfite (VES), butylene sulfite (BS), propylene sulfite (TMS) and derivatives thereof.

[0153] In some embodiments, the sulfur-containing additive includes one or more of methylene methanedisulfonate (MMDS), diethylene sulfate (DTD), diethylene disulfate (2-DTD), triethylene trisulfate (3-DTD), vinyl sulfite (ES), butylene sulfite (BS) and their derivatives.

[0154] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 负 7.8μm-14.3μm.

[0155] Volume distribution particle size Dv50 of negative electrode active material 负 It is a well-known meaning in the art, which indicates 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 a laser particle size analyzer with reference to GB / T 19077-2016 particle size distribution laser diffraction method. The test instrument can be the Mastersizer 3000 laser particle size analyzer of Malvern Instruments Ltd., UK.

[0156] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 负 Available options are 7.8μm, 7.9μm, 8μm, 8.1μm, 8.2μm, 8.3μm, 8.4μm, 8.5μm, 8.6μm, 8.7μm, 8.8μm, 8.9μm, 9.0μm, 9.1μm, 9.2μm, 9.3μm, 9. 4μm, 9.5μm, 9.6μm, 9.7μm, 9.8μm, 9.9μm, 10μm, 10.1μm, 10.2μm, 10.3μm, 10.4μm, 10.5μm, 10.6μm, 10.7μm, 10.8μm, 11.8 μm, 12.8 μm, 13.8 μm, 14.3μm or any value range in between.

[0157] Dv50 负 The negative electrode active material within the above range includes a certain amount of small particles and large particles at the same time, so that the battery cell can not only improve the transmission rate of lithium ions and improve the kinetic performance through small particles, but also improve the compaction density of the battery cell pole piece through the grading of large and small particles, improve the energy density of the battery cell, and achieve a balance between kinetic performance and energy density.

[0158] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 负 The particle size 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%.

[0159] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 负 The options are 7.8μm, 7.9μm, 8μm, 8.1μm, 8.2μm, 8.3μm, 8.4μm, 8.5μm, 8.6μm, 8.7μm, 8.8μm, 8.9μm, 9.0μm, 9.1μm, 9.2μm, 9.3μm, 9.4μm, 9.5μm, 9.6μm, 9.7μm, 9.8μm, 9.9μm, 10μm, 10.1μm, 10.2μm, 10.3μm, 10 .4μm, 10.5μm, 10.6μm, 10.7μm, 10.8μm or any numerical range therebetween, and the mass content of the sulfur-containing additive in the electrolyte can be selected as 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 any numerical range therebetween.

[0160] 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 dynamic performance of the battery cell. 负 The negative electrode active material within the above range has a relatively large surface area and surface activity, and has a relatively stronger reaction activity with the chain carboxylic acid ester solvent. Therefore, a higher content of sulfur-containing additives is required in the electrolyte to achieve a balance between kinetic performance and storage stability.

[0161] 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%.

[0162] In some embodiments, the volume particle size Dv50 of the negative electrode material can be selected as 10.8μm, 10.9μm, 11μm, 11.1um, 11.2μm, 11.3μm, 11.4μm, 11.5μm, 11.6μm, 11.7μm, 11.8 μm, 12.8 μm, 13.8 μm, 14.3μm or any range between two thereof, and the mass content of the sulfur-containing additive in the electrolyte can be selected as 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 any range between two thereof.

[0163] 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.

[0164] In the present application, carbonate additives refer to compounds including carbonate groups (—O—CO—O—) and derivatives thereof, as well as mixtures containing the above compounds and derivatives thereof.

[0165] The sulfur-containing components on the surface of the negative electrode material will increase the brittleness of the SEI film while improving the high-temperature stability of the SEI film. Carbonate additives can evolve into organic components in the SEI film, improve the toughness of the SEI film, and work together with the sulfur-containing components in the SEI film to improve the stability of the SEI film during the battery cell cycle and improve the cycle life of the battery cell.

[0166] In some embodiments, the electrolyte includes vinylene carbonate VC and fluoroethylene carbonate FEC.

[0167] Chain carboxylates are highly active, which improves the wettability between the electrolyte and the electrode, improves the conductivity of the electrolyte, and also corrodes the solid electrolyte membrane (SEI membrane). Vinylene carbonate VC has a reduction potential close to that of chain carboxylates, which can inhibit the reaction activity of chain carboxylates, improve the compactness of the SEI membrane, and improve the cycle 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 membrane. By adding sulfur-containing additives, vinylene carbonate VC and fluoroethylene carbonate FEC to the electrolyte, the dynamic performance, storage stability and cycle life of the battery cell can be more effectively taken into account.

[0168] In some embodiments, 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%.

[0169] 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 any range therebetween.

[0170] The electrolyte with the mass content of carbonate additives within the above range can not only improve the cycle stability of the SEI film, but also control the degree of side reactions, thereby comprehensively improving the cycle life of the battery cell.

[0171] 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 can be optionally 2% to 6.5%.

[0172] In some embodiments, based on the total mass of the electrolyte, the mass content 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 any numerical range therebetween.

[0173] 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 can be optionally 0.5% to 3%.

[0174] In some embodiments, based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate FEC in the electrolyte may be selected to 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 any numerical range therebetween.

[0175] By adding vinylene carbonate VC and fluoroethylene carbonate FEC to the electrolyte, the kinetic performance and cycle stability of the battery monomer can be effectively taken into account.

[0176] In some embodiments, 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 an olivine-structured lithium-containing phosphate and a lithium-containing transition metal oxide.

[0177] In some embodiments, the specific surface area of ​​the positive electrode 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 to the electrolyte is 2%-6%.

[0178] In the present application, the specific surface area of ​​the positive electrode active material 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 tested by nitrogen adsorption specific surface area analysis test method with reference to GB / T 19587-2017, and calculated by BET (Brunauer Emmett Teller) method. The test instrument can be the Tri-Star 3020 specific surface area pore size analysis tester of Micromeritics, USA.

[0179] In some embodiments, the specific surface area S of the positive electrode active material can be selected to be 5 m 2 / g, 5.4 m 2 / g, 6m 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, 9.4m 2 / g or any numerical range therebetween, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte can be selected as 2%, 3%, 4%, 5%, 6% or any numerical range therebetween.

[0180] In some embodiments, the specific surface area of ​​the positive electrode active material is 9.5 m 2 / g ~18m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte is 3%-8%.

[0181] In some embodiments, the specific surface area of ​​the positive electrode active material can be 9.5 m 2 / g, 10 m 2 / g, 10.5m 2 / g, 11 m 2 / g, 11.5 m 2 / g, 12 m 2 / g, 12.5m 2 / g, 13 m 2 / g, 13.5m 2 / g, 14 m 2 / g, 14.5m 2 / g, 15m 2 / g, 15.5 m 2 / g, 16 m 2 / g, 16.5m 2 / g, 17 m 2 / g, 17.5m 2 / g, 18m 2 / g or any numerical range therebetween, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8% or any numerical range therebetween.

[0182] Positive electrode active materials with large specific surface areas have large contact areas with electrolytes, which can improve the dynamic performance of battery cells. However, positive electrode active materials with large specific surface areas are more likely to absorb water molecules in the air, and water molecules are difficult to be discharged from the positive electrode film layer during the drying and film forming process. During the cycle of battery cells, water molecules react with electrolyte salts in the electrolyte to generate hydrofluoric acid, which corrodes the SEI film on the surface of the negative electrode material. Positive electrode active materials with high specific surface areas generate high levels of hydrofluoric acid in battery cells. High levels of carbonate additives can improve the compactness of the SEI film on the surface of the negative electrode material, taking into account both the dynamic performance and cycle stability of the battery cells.

[0183] In some embodiments, the positive electrode active material includes a lithium-containing phosphate in an olivine structure, and its general composition formula is shown in Formula IV: Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula IV, 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.

[0184] In some embodiments, x1 can be selected as 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or any range therebetween, y1 can be selected as 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 any range therebetween, x1+y1 can be selected as 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or any range therebetween, a1 can be selected as 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any range therebetween, b1 can be selected as 0, 0.1, 0.2, 0.3, 0.4, 0.5 or any range therebetween, a1+b1 can be selected as 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any range therebetween, c1 can be selected as 0, 0.1, 0.2, 0.3, 0.4, 0.5 or any range therebetween, z1 can be selected as 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 any range therebetween.

[0185] The lithium-containing phosphate with an olivine structure having the above-mentioned components has good structural stability and low irreversible loss during fast charging, thereby improving the cycle stability of the battery cell.

[0186] In some embodiments, the specific surface area of ​​the olivine-structured lithium-containing phosphate is 5.0 m 2 / g ~18.0m 2 / g.

[0187] In some embodiments, the specific surface area of ​​the olivine-structured lithium-containing phosphate can be 5.0 m 2 / g, 6.0 m 2 / g, 7.0m 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, 14.0m 2 / g, 15.0 m 2 / g, 16.0 m 2 / g, 17.0 m 2 / g, 18.0 m 2 / g or any range of values ​​between them.

[0188] In some embodiments, the positive electrode active material includes a lithium-containing transition metal oxide, and its general composition formula is shown in 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 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.

[0189] In some embodiments, x2 can be selected as 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 any range therebetween, and y2 can be selected as 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 any range therebetween, and x2+y2 can be 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 any range therebetween; a2 can be 0, 0.1, 0.2, 0.3 , 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any range therebetween, b2 may be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any range therebetween, c2 may be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any range therebetween range, and a2+b2+c2 can be selected as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any range therebetween; z2 can be selected as 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 any range therebetween.

[0190] In some embodiments, the specific surface area of ​​the lithium-containing transition metal oxide is 0.1 m 2 / g ~2m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive in the electrolyte is 1%-5%.

[0191] In some embodiments, the specific surface area of ​​the lithium-containing transition metal oxide can be 0.1 m 2 / g, 0.2 m 2 / g, 0.3 m 2 / g, 0.4 m 2 / g, 0.5m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2m 2 / g or any numerical range therebetween, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte can be selected as 1%, 2%, 3%, 4%, 5% or any numerical range therebetween.

[0192] In some embodiments, the positive electrode active material further includes an ion conductive layer disposed on the surface of the lithium-containing phosphate, the ion conductive layer includes carbon and iron elements, and the mass percentage of the carbon element is 1% to 2% based on the total mass of the positive electrode active material.

[0193] In some embodiments, based on the total mass of the positive electrode active material, the mass percentage of carbon element 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 any numerical range therebetween.

[0194] It should be noted that the ion-conducting layer can be a single-layer structure or a multi-layer structure, that is, the iron-containing component and the carbon-containing component in the ion-conducting layer can be a mixed phase or can be arranged in layers. It can be understood that the ion-conducting layer has a high ion transmission rate.

[0195] The ion-conducting layer containing carbon elements can simultaneously improve the ion conductivity and electrical conductivity of the positive electrode active material, improve the solid-phase transmission rate of ions and electrons, and improve the dynamic performance of the battery cell.

[0196] In some embodiments, the ion-conducting layer comprises a fast ion conductor having a NASICON structure as shown in 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. Optionally, M2 has a valence of +4, 0≤b3≤1, 3≤x3≤5, and 2≤y3≤4.

[0197] In some embodiments, b3 can be selected as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any range therebetween, x3 can be selected as 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 any range therebetween, and y3 can be selected as 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 any range therebetween.

[0198] The physical phase structure in the ion-conducting layer can be characterized by any known method in the art. For example, by characterizing the positive electrode active material through transmission electron microscopy, it can be seen that the ion-conducting layer and the matrix of the positive electrode active material have different physical phase structures. Combining diffraction patterns and energy spectrum analysis, the fast ion conductor component of the ion-conducting layer can be judged.

[0199] Fast ion conductors with NASICON structures have abundant three-dimensional lithium ion diffusion and transmission channels, and have the advantages of high ion conduction efficiency and strong structural stability during multiple lithium stripping and insertion processes. Coating fast ion conductors with NASICON structures on the surface of lithium-containing phosphates can significantly increase the transmission rate of lithium ions during multiple stripping / insertion of lithium at the positive terminal, improve the ionic conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cells.

[0200] In some embodiments, the fast ion conductor comprises Li 2 FeTi(PO 4 ) 3 , Li 2 FeZr(PO 4 ) 3 , Li 2 FeSn(PO 4 ) 3 One or more of .

[0201] 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, dilithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, and trilithium citrate.

[0202] Lithium replenishers usually refer to materials that decompose and release active lithium during the electrochemical process to compensate for the irreversible loss of active lithium caused by the growth of the negative electrode SEI film. Adding lithium replenishers to the positive electrode active layer can offset the irreversible lithium loss during the electrochemical process to increase the total capacity and energy density of the battery cell.

[0203] Ternary lithium supplement material refers to an oxide lithium supplement agent including one or more of nickel, cobalt and manganese.

[0204] In some embodiments, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement agent is 0.1%-10%.

[0205] In some embodiments, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement may be selected to be 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 any numerical range therebetween.

[0206] The added mass content ratio of the lithium supplement agent in the positive electrode film layer is calculated by dividing the added mass of the lithium supplement agent by the total mass of the positive electrode film layer.

[0207] In some embodiments, the negative electrode active material includes graphite.

[0208] In some embodiments, the graphite includes composite graphite particles, the composite graphite particles include a main particle and a coating layer at least partially disposed on the surface of the main particle, the main particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0209] Secondary particles are particles formed by the aggregation of two or more primary particles.

[0210] The composite graphite particles including secondary particles and the surface coating layer including amorphous carbon are both beneficial to the infiltration of the electrolyte into the negative electrode active layer of the pole piece, and contribute to the improvement of the rate performance of the battery cell.

[0211] In some embodiments, the composite graphite material further comprises a kinetic carbon material.

[0212] In some embodiments, the kinetic carbon material is located between primary particles of the bulk particles. In this case, the bulk particles of the negative electrode active material include artificial graphite primary particles and the kinetic carbon material located between the primary particles.

[0213] In some embodiments, the kinetic carbon material is located in the coating layer. In this case, the coating layer includes both amorphous carbon and the kinetic carbon material.

[0214] In some embodiments, the kinetic carbon material raw material includes one or more of hard carbon, expanded graphite, and graphene.

[0215] Herein, "kinetic carbon material raw material" and "kinetic carbon material raw material powder" are completely identical in composition. "Kinetic carbon material" refers to the product of "kinetic carbon material raw material" after graphitization and / or carbonization.

[0216] In some embodiments, the interlayer spacing d of the (002) crystal plane of the kinetic carbon material raw material is 002 ≥0.3358nm, optionally 0.3359nm~0.3366nm.

[0217] The interlayer spacing of the kinetic carbon material raw materials is larger than that of conventional graphite (the interlayer spacing of conventional graphite is 0.335nm). When the kinetic carbon material obtained therefrom is uniformly distributed in the bulk particles and / or coating layers of the composite graphite particles, it is beneficial to the rapid embedding and extraction of active ions, thereby improving the transmission performance of active ions and electrons, and further improving the rapid charging performance of the battery cells.

[0218] In some embodiments, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5% based on the total mass of the composite graphite particles.

[0219] 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 may be 2%, 3%, 4%, 5% or any range therebetween.

[0220] When the content of amorphous carbon is within a suitable range, the composite graphite material can have a high gram capacity and a high active ion solid phase transport capacity, which is beneficial to the improvement of the kinetic performance of the battery cell.

[0221] In some embodiments, the powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm.

[0222] In some embodiments, the powder resistivity of the negative electrode material may be 0.01Ω•cm, 0.02Ω•cm, 0.03Ω•cm, 0.04Ω•cm, or any range therebetween.

[0223] The powder resistivity of the negative electrode material can be tested by any known method in the art. As an example, it can be tested 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 for analysis and testing with reference to standard GB / T30835-2014.

[0224] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20000N is 1.5g / cm 3 Up to 1.8g / cm 3, optional 1.55g / cm 3 Up to 1.75g / cm 3 .

[0225] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20000N can be 1.5g / cm 3 , 1.55g / cm 3 , 1.6g / cm 3 , 1.65g / cm 3 , 1.7g / cm 3 , 1.75g / cm 3 , 1.8g / cm 3 Or any range of values ​​in between.

[0226] The compaction density of the negative electrode material powder under a pressure of 20000N is well known in the art and can be measured by instruments and methods known in the art. For example, it can be measured by an electronic pressure tester (for example, a UTM7305 electronic pressure tester) with reference to GB / T 24533-2009. An exemplary test method is as follows: weigh 1g of negative electrode active material powder and add a bottom area of ​​1.327cm 2 In the mold, the pressure is increased to 20000N, the pressure is maintained for 30s, and then the pressure is released and maintained for 10s. Then the powder compaction density of the material under the pressure of 20000N is recorded and calculated.

[0227] Negative electrode materials with powder compaction density within an appropriate 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, the negative electrode active layer can maintain its original pore structure during the cycle process, which is beneficial to improving the high dynamic performance of the battery cell during the cycle process.

[0228] In some embodiments, the negative electrode active material also includes a silicon-based material, which includes at least one of silicon, silicon oxides and silicon-carbon composites; based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material is 0.3% to 10%, and can be optionally 1% to 6%.

[0229] In some embodiments, based on the total mass of the negative electrode active material, the mass content of silicon in the silicon-based material can be selected to be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any numerical range therebetween.

[0230] The introduction of silicon-based materials is conducive to improving the energy density of battery cells. Silicon-based materials within the above mass range can take into account both the energy density and cycle stability of battery cells.

[0231] 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%.

[0232] In some embodiments, the added mass content of the carbonate additive in the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any range therebetween.

[0233] Silicon-based materials are prone to expansion during the cycle process, causing the SEI film on the surface of the negative electrode material to rupture, so the consumption of additives is relatively increased. The carbonate additives within the above range can improve the density and regeneration ability of the SEI film, taking into account the energy density and cycle stability of the battery cell.

[0234] 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, and 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.

[0235] The composite graphite particles are arranged close to the electrolyte side to improve the dynamic performance of the battery cell while taking into account the energy density.

[0236] 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.

[0237] 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 may be 3:7, 4:7, 5:7, 6:7, 1:1, 2:1, 7:3 or any range therebetween.

[0238] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active material layer is 1 It is 9.5μm~18.5μm, and can be selected as 9.5μm~14.8μm.

[0239] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the first negative electrode active material layer is 1The options can be 9.5μm, 9.8μm, 10μm, 10.8μm, 11μm, 11.8μm, 12μm, 12.8μm, 13μm, 13.8μm, 14μm, 14.8μm, 15μm, 15.8μm, 16μm, 16.8μm, 17μm, 17.8μm, 18μm, 18.5μm or any numerical range therebetween.

[0240] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active layer is 2 It is 7.8μm~14.3μm, and can be selected as 7.8μm~12.8μm.

[0241] In some embodiments, the volume average particle size Dv50 of the negative electrode active material in the second negative electrode active material layer is 2 The optional value 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 any numerical range therebetween.

[0242] The volume average particle size Dv50 of the negative electrode active material in the first negative electrode active material layer and the second negative electrode active material layer 1 、Dv50 2 The test can be carried out by referring to the test method of the volume average particle size described above.

[0243] The second negative electrode active material layer disposed on the electrolyte side includes negative electrode active materials with smaller particle sizes, which can further increase the solid-liquid transmission rate of ions in the battery pole piece and improve the dynamic performance of the battery cell.

[0244] In some embodiments, the volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer is 2 The thickness of the electrolyte is 7.8 μm to 10.8 μm, and the added mass content of the carbonate additive in the electrolyte is 3% to 8%.

[0245] In some embodiments, the volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer is 2 It can be selected as 7.8μm, 8μm, 8.8μm, 9μm, 9.8μm, 10μm, 10.8μm or any numerical range therebetween, and the added mass content of the carbonate additive in the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8% or any numerical range therebetween.

[0246] 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%.

[0247] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC can be selected as 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7% or any numerical range therebetween, and the added mass content of fluoroethylene carbonate FEC can be selected as 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 any numerical range therebetween.

[0248] In some embodiments, the volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer is 2 The particle size is 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% to 7%.

[0249] In some embodiments, the volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer is 2 It can be selected as 10.8μm, 11μm, 11.8μm, 12μm, 12.8μm, 13μm, 13.8μm, 14μm, 14.8μm or any numerical range therebetween, and the added mass content of the carbonate additive in the electrolyte can be selected as 2%, 3%, 4%, 5%, 6%, 7% or any numerical range therebetween.

[0250] The volume average particle size Dv50 of the negative electrode material in the second negative electrode film layer 2 A relatively small content is conducive to the solid phase diffusion of lithium ions in the negative electrode active material, but at the same time it will increase the reactivity of the negative electrode active material with 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.

[0251] 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%.

[0252] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC can be selected as 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or any numerical range therebetween, and the added mass content of fluoroethylene carbonate FEC can be selected as 0.5%, 1%, 1.5%, 2%, 2.5% or any numerical range therebetween.

[0253] In some embodiments, based on the total mass of the electrolyte, the mass content of the linear carboxylic acid ester accounts for 25.5%-63.75%.

[0254] In some embodiments, based on the total mass of the electrolyte, the mass content of the linear carboxylic acid ester may be 25.5%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 63.75% or any range therebetween.

[0255] In some embodiments, the linear carboxylate has R 1 -COO-R 2 The general structural formula is 1 and R 2 Each independently includes C 1 ~C 5 The alkyl and C 1 ~C 5 At least one of the halogenated alkyl groups.

[0256] "C1-C5 alkyl" refers to an unbranched or branched alkyl group 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, and 1-ethylpropyl.

[0257] “C 1 ~C 5 The term "haloalkyl" refers to an unbranched or branched alkyl group having 1 to 5 carbon atoms in which at least one hydrogen atom is substituted by a halogen, including but not limited to one or more of a chloroalkyl group, a bromoalkyl group, and an iodoalkyl group.

[0258] In some embodiments, the linear carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

[0259] The electrolyte with a mass content of chain carboxylic acid ester within the above range has good conductivity, wettability and chemical stability, which is beneficial to the comprehensive improvement of the battery monomer kinetics, storage stability and cycle stability.

[0260] 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%.

[0261] In some embodiments, the solvent also includes a carbonate solvent. Based on the total mass of the solvent in the electrolyte, the mass content of the carbonate solvent can be selected to be 17%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 76.5% or any numerical range therebetween.

[0262] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0263] The carbonate solvent in the electrolyte and the lithium ions in the lithium-containing electrolyte salt easily 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 cell.

[0264] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the linear carboxylic acid ester is 0.27:1-1.33:1.

[0265] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the linear carboxylic acid ester can be selected as 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 any numerical range therebetween.

[0266] Chain carboxylates can improve the wettability between the electrolyte and the pole piece, improve the solid-liquid transfer rate of lithium ions between the electrolyte and the pole piece, and the addition of chain carboxylates is also beneficial to the improvement of the conductivity of the electrolyte; however, chain carboxylates are easy to react with the SEI film, reducing the storage stability of the battery cell. The ethylene carbonate in the electrolyte and the lithium ions in the lithium-containing electrolyte salt are easy to form a solvation structure to increase the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt, but the viscosity of the electrolyte will also increase with the increase of the ethylene carbonate content, which has a negative impact on the conductivity of the electrolyte. The mass ratio of ethylene carbonate to the chain carboxylates within the above range allows the electrolyte to have both suitable viscosity, conductivity, good dissociation rate and wettability, which is beneficial to comprehensively improve the dynamic performance and high temperature stability of the battery cell.

[0267] 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.

[0268] In some embodiments, the mass ratio of the lithium salt to the ethylene carbonate may 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 any range therebetween.

[0269] 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 the lithium ions and improve the dynamic performance of the battery monomer.

[0270] In some embodiments, the conductivity of the electrolyte is 13mS / cm-20mS / cm; optionally 15mS / cm-20mS / cm.

[0271] The electrolyte with conductivity within the above range can better balance the dynamic performance and high temperature stability of the battery cell.

[0272] In some embodiments, the lithium salt includes a fluorinated sulfonyl imide salt and lithium hexafluorophosphate LiPF 6 One or more of; optionally, the fluorine-containing sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0273] Fluorinated sulfonyl imide salts are easy to dissociate in electrolyte solvents, which is beneficial to improving the conductivity of the electrolyte. Fluorinated sulfonyl imide salts have high chemical stability and are not easy to decompose during recycling. They can reduce the production of hydrogen fluoride during battery cycling, reduce the probability of negative electrode side reactions, and improve the cycle stability of battery cells. However, with the increase in the temperature of the battery cells, fluorinated sulfonyl imide salts will undergo violent decomposition and release a large amount of heat at a certain temperature threshold, 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 cycle, the addition of lithium hexafluorophosphate will greatly reduce the risk of thermal runaway of battery cells, reducing the risk to a controllable range and improving the safety of the battery.

[0274] In some embodiments, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF 6 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 LiPF in the electrolyte is 0.2 mol / L-0.5 mol / L. 6 The molar concentration is 0.5 mol / L to 1.0 mol / L.

[0275] In some embodiments, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte may be 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, or any range therebetween.

[0276] In some embodiments, the electrolyte contains lithium hexafluorophosphate (LiPF). 6 The molar concentration can be selected as 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 any numerical range therebetween.

[0277] In some embodiments, the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate LiPF in the electrolyte are 6 The molar concentration ratio is (2-5):10.

[0278] In some embodiments, the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate LiPF in the electrolyte are 6 The molar concentration ratio can be selected as 2:10, 3:10, 4:10, 5:10 or any range therebetween.

[0279] The molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the lithium hexafluorophosphate LiPF in the electrolyte 6The battery monomer having a molar concentration within the above range can take into account both the dynamic performance and safety performance of the battery monomer.

[0280] In some embodiments, the battery cell further includes a separator, the separator including a porous base membrane and a functional layer disposed on at least one side of the porous base membrane, and the thickness of the porous base membrane is ≤12 μm, and may be less than or equal to 9 μm.

[0281] In some embodiments, the thickness of the porous base membrane may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or any range therebetween.

[0282] In some embodiments, the porous base film includes one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The porous base film can be a single-layer film or a multi-layer composite film, without particular limitation.

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

[0284] In some embodiments, the porosity of the porous base membrane in the isolation membrane may be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or any range therebetween.

[0285] In some embodiments, the functional layer includes a first functional layer disposed on the negative electrode side of the porous base membrane and a second functional layer disposed on the positive electrode side of the porous base membrane, the first functional layer includes first inorganic particles, the second functional layer includes composite particles, the composite particles include second inorganic particles and non-fluorinated polymers, and the second inorganic particles in the composite particles are attached to the surface of the non-fluorinated polymer particles and / or dispersed inside the non-fluorinated polymer particles.

[0286] 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, and tin oxide.

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

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

[0289] In some embodiments, the battery cell filling coefficient is 2.2 g / Ah-3.1 g / Ah.

[0290] The 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 injection coefficient of a battery cell can be obtained by testing in any known manner in the art. Exemplarily, the mass of the electrolyte in a battery cell can be tested 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 sheet, negative electrode sheet, separator and mechanical parts. Use dimethyl carbonate (DMC) solvent to soak and clean the positive electrode sheet, negative electrode sheet, separator and mechanical parts. The soaking time is 24h~48h, and the soaking is repeated for more than 3 times. Place the aforementioned positive electrode sheet, negative electrode sheet, separator and mechanical parts in a 100°C oven for more than 24h until completely dried. Weigh the dried positive electrode sheet, negative electrode sheet, separator and mechanical parts, and record the mass as M1. The mass of the electrolyte in the battery cell is thus obtained as (M0-M1). The filling coefficient is calculated by (M0-M1) / rated capacity of the battery cell. The rated capacity is the nominal capacity of the battery, or charged to 3.65V at a charging rate of 0.33C, then charged to 0.05C at a constant voltage of 3.65V, left to stand for 10 minutes, and then discharged to 2.0V at a discharge rate of 0.33C, with the discharge capacity of the battery cell as the rated capacity.

[0291] In some embodiments, the battery monomer filling coefficient may be 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 range therebetween.

[0292] In some embodiments, the fast charging time of the battery cell from 10% SOC to 80% SOC is 6 min to 15 min.

[0293] The fast charge time of the battery cell from 10% SOC to 80% SOC can be tested by any known method in the art. As an example, at 30°C, charging from 10% SOC to 15% SOC at 5.0C constant current, charging from 15% SOC to 20% SOC at 5.0C constant current, charging from 20% SOC to 25% SOC at 5.0C constant current, charging from 25% SOC to 30% SOC at 5.0C constant current, charging from 30% SOC to 35% SOC at 5.0C constant current, charging from 35% SOC to 40% SOC at 5.0C constant current, charging from 40% SOC to 50% SOC at 4.6C constant current. 45% SOC, charged from 45% SOC to 50% SOC at 4.3C constant current, charged from 50% SOC to 55% SOC at 4.0C constant current, charged from 55% SOC to 60% SOC at 3.7C constant current, charged from 60% SOC to 65% SOC at 3.4C constant current, charged from 65% SOC to 70% SOC at 3.1C constant current, charged from 70% SOC to 75% SOC at 2.9C constant current, charged from 75% SOC to 80% SOC at 2.7C constant current, 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 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min or any range of values ​​between the two.

[0294] The battery cell has good fast charging performance and can meet the demand for improving the energy replenishment efficiency of electrical devices.

[0295] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0296] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0297] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 3 The battery cell 5 is a square structure as an example.

[0298] In some embodiments, reference Figure 4, the outer packaging may include a shell 51 and a top cover assembly 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0299] In some embodiments, battery cells may be assembled into a battery module. The number of battery cells contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0300] Figure 5 4 is an example of a battery module. Figure 5 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0301] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0302] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0303] Figure 6 and Figure 7 1 is a battery pack 1 as an example. 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 cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0304] A second aspect of the present application provides a battery device, including the battery cell provided by the first aspect of the present application, and the battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0305] In addition, the present application also provides an electric device, which includes a battery cell provided in the present application. The battery cell, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric 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 and satellites, energy storage systems, etc., but are not limited thereto.

[0306] In some embodiments, the fast charging time for the electric device to charge from 10% SOC to 80% SOC is 6 minutes to 15 minutes.

[0307] 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 any range therebetween.

[0308] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0309] Figure 8 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the power consumption device's requirements for high power and high energy density of battery cells, a battery pack or a battery module can be used.

[0310] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be light and thin, and a battery cell may be used as a power source.

[0311] Example 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 the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0312] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0313] Example 1 Preparation of positive electrode The positive electrode sheet includes a positive electrode current collector, a positive electrode conductive layer on the positive electrode current collector and a positive electrode film layer. The positive electrode current collector is an aluminum foil with a thickness of 10 μm.

[0314] The positive conductive layer on the positive current collector is a film layer formed by evenly mixing the positive conductive agent superconducting carbon, the positive electrode binder polyvinylidene fluoride (PVDF) and the solvent N-methylpyrrolidone NMP, and then coating it on the surface of the current collector and drying it. The thickness is 1 μm, and 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%.

[0315] The positive electrode film layer includes a film layer formed by uniformly coating the positive electrode slurry (the solvent is N-methylpyrrolidone NMP) on the surface of the positive electrode conductive layer, drying, and cold pressing. The positive electrode film layer includes a positive electrode active material, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black in a weight ratio of 97:2:1.

[0316] The positive electrode active material includes lithium iron phosphate and a coating layer, the coating layer is coated on the surface of the lithium iron phosphate, and the coating layer includes lithium titanium iron phosphate Li 2 FeTi(PO 4 ) 3 and amorphous carbon. The Dv50 of the positive electrode active material is 1.6 μm, and the Dv10 is 0.64 μm.

[0317] The single-sided coating weight of the positive electrode film is 300mg / 1540.25mm 2 .

[0318] Preparation of negative electrode The negative electrode sheet includes a negative electrode current collector, a negative electrode conductive layer on the negative electrode current collector and a negative electrode film layer. The negative electrode current collector is a copper foil with a thickness of 5 μm.

[0319] The negative electrode conductive layer on the negative electrode current collector is a film layer formed by evenly mixing a negative electrode conductive agent superconducting carbon, a negative electrode binder styrene-butadiene rubber SBR, a thickener sodium carboxymethyl cellulose (CMC-Na) and a solvent water, and then coating it on the surface of the negative electrode current collector and drying it. The thickness is 1 μm, the mass content of the negative electrode conductive agent in the negative electrode conductive layer is 35%, the mass content of the negative electrode binder in the negative electrode conductive layer is 60%, and the mass content of the thickener in the negative electrode conductive layer is 5%.

[0320] The negative electrode film layer includes a film layer formed by uniformly coating the negative electrode slurry (the solvent is deionized water) on the surface of the negative electrode conductive layer, and then drying and cold pressing.

[0321] The single-sided coating weight of the negative electrode film is 138mg / 1540.25mm 2.

[0322] The negative electrode film layer comprises a first negative electrode film layer and a second negative electrode film layer, wherein 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.

[0323] The first negative electrode film layer includes graphite particles with a mass ratio of 96.5:0.5:0.5:1.5:1, a conductive agent acetylene black, a first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose. The mass content of lithium element in the first lithium-containing binder is 4.8%, the Dv50 of the graphite particles is 11.3μm, and the graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0324] The second negative electrode film layer includes graphite particles with a mass ratio of 97.5:0.5:0.5:0.5:1, a conductive agent acetylene black, a second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), a negative electrode binder styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose. The mass content of lithium element in the second lithium-containing binder is 4.8%, the Dv50 of the graphite particles is 11.3μm, and the graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0325] Electrolyte preparation In an argon atmosphere glove box with a water content of less than 10 ppm, ethylene carbonate EC, ethyl methyl carbonate EMC, and ethyl acetate EA were uniformly mixed at a mass ratio of 35:15:50 to obtain an electrolyte solvent. Lithium hexafluorophosphate (LiPF 6 ) as lithium salt, and stir thoroughly until it is completely dissolved. After returning to room temperature, add 2% of additives vinyl carbonate VC, 2% of fluoroethylene carbonate FEC and 1% of vinyl sulfite ES in order with respect to the total mass of the electrolyte, and mix thoroughly to obtain an electrolyte. Based on the total mass of the electrolyte, the mass percentage of lithium salt is 15%, and the conductivity of the electrolyte is 15.4mS / cm.

[0326] Preparation of isolation membrane A polyethylene (PE) film with a first functional layer of nano-alumina coating coated on the negative electrode side and a nano-alumina coating and acrylate copolymer coated on the other side was used as an isolation membrane. The porosity of the porous base membrane PE film was 35% and the thickness of the PE film was 7 μm.

[0327] Preparation of battery cells The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in order to obtain a wound electrode assembly. The electrode assembly is added to the outer packaging square aluminum shell, dried and injected with electrolyte. After packaging, standing, formation, aging, secondary packaging, capacity and other processes, a battery cell is obtained. The liquid retention coefficient d3 / A of the battery cell is 2.9g / Ah.

[0328] The preparation methods of Examples 2-4 and 9-17 are basically the same as that of Example 1, except that the composition of the electrolyte is adjusted, as shown in Table 1.

[0329] The preparation methods of Examples 5-8 are substantially the same as those of Example 1, except that the Dv50 of the negative electrode active material and / or the electrolyte components are adjusted.

[0330] The preparation methods of Examples 18-21 are substantially the same as those of Example 1, except that the Dv50 of the positive electrode active material and / or the electrolyte composition are adjusted.

[0331] The preparation method of Example 22 is basically the same as that of Example 1, except that the type of positive electrode active material is adjusted. The ternary positive electrode active material in Example 22 is NCM811.

[0332] The preparation method of Comparative Example 1 is substantially the same as that of Example 1, and no sulfur-containing additive is added to the electrolyte.

[0333] Test Method The battery cells in the embodiment and the comparative example were tested respectively. The test results are shown in Table 1.

[0334] (1) The method for storing DCR test is: ①Battery DCR test method The DCR test method can refer to the method in GB / T 31467 "High Power Lithium Ion Power Battery Performance Test Specification for HEV". The details are as follows: At 25 ℃, charge the lithium-ion battery to 3.65V at a constant current of 0.33C and let it stand for 1 min; then charge it to 3.65V at a constant current of 0.1C and let it stand for 30 min; discharge it to 2.0V at a constant current of 0.33C and record the discharge capacity A0 at this time, in Ah; then charge it at a constant current of 0.33C for 0.5A0Ah and adjust the SOC to 50%.

[0335] After the battery was placed at 25 °C for 2 h, it was discharged at a constant current of 2C for 10 s and ∆U was recorded. 放电 , ∆I 放电 , the discharge DCR data of the lithium-ion battery is calculated by the following formula.

[0336] R 放电 =∆U 放电 / ∆I 放电 Among them, ∆U 放电 Indicates the voltage change within 10s after the discharge starts, ∆I 放电 Indicates the current value within 10 seconds after the discharge starts.

[0337] ②Battery high temperature storage test method: First, the DCR value of the battery before high-temperature storage is tested as D0. Then, at 25°C, the battery cell is charged to 3.65V at a constant current of 0.33 C and left to stand for 1 min; then, it is charged to 3.65 V at a constant current of 0.1 C, and the charge is adjusted to 100% SOC, and then the battery cell is stored at 60°C. Every 30 days, the battery is taken out and placed at 25°C to measure the DCR value, and this is repeated. The DCR values ​​of the battery after storage are recorded as D1, D2...Dn. The storage DCR growth calculation method is: (Dn-D0) / D0, where n is 1, 2, 3, 4...n.

[0338] In this application, the DCR growth rate after storage at 60° C. for 90 days is taken as the test result.

[0339] (2) 60℃ cycle test: At 60°C, charge the battery to 3.65V at a 1C charge rate of the nominal capacity, then charge at a constant voltage of 3.65V to 0.05C, let stand for 10 min, then discharge at a 1C discharge rate to 2.5V, let stand for 10 min. The above 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 number of cycles @80%SOH.

[0340] (3) Parameter test method for battery thermal runaway: ① Charge adjustment: At 25°C, charge the lithium-ion battery to 3.65V at a constant current of 0.33C and let it stand for 1 min; then charge it to 3.65V at a constant current of 0.1C and adjust the battery to 100% SOC.

[0341] ② Overcharge to thermal runaway test: Put the battery into the test fixture with a clamp force of 3000N, and then charge it at a constant current rate of 1C until the battery cell thermal runaway. After the battery cools to room temperature, observe the state of the thermal runaway cell. If fire or explosion occurs, the thermal runaway boundary will deteriorate.

[0342] The test results are shown in Tables 1 to 3.

[0343] Table 1

[0344] Table 2

[0345] Table 3

[0346] Test Results After the negative electrode film layer of the formed battery cell was scraped to obtain a powder sample, the X-ray photoelectron spectrum (XPS) of the sample was tested. The XPS spectrum test results show that there is a sulfur 2p characteristic peak in the spectrum at 5nm~10nm away from the sample surface, and the sulfur 2p characteristic peak includes at least one of the first sub-peak with a binding energy of 162.5eV~164eV, the second sub-peak with a binding energy of 168.5eV~169.5eV, and the third sub-peak with a binding energy of 166.5eV~167.5eV; while in Comparative Examples 1 and 2, the above-mentioned S-containing characteristic peak does not appear in the sulfur 2p electron X-ray photoelectron spectrum (XPS) diagram. Compared with the comparative example, the battery cell in the embodiment has good high temperature stability.

[0347] The XPS sulfur element spectrum results in Example 2 are as follows Figure 1 As shown, the XPS sulfur element spectrum results in Example 1 are as follows Figure 2 As shown in the figure, the comparison between the test spectrum and the standard spectrum shows that the first subpeak with a binding energy of 162.5eV~164eV corresponds to S 2 O 3 2- The second subpeak with a binding energy of 168.5eV~169.5eV corresponds to RO-SO 2 - The third sub-peak with a binding energy of 166.5 eV to 167.5 eV corresponds to SO 3 2- Since the cations in the XPS spectrum are mainly lithium ions, it can be known that the negative electrode active materials in the battery monomer include Li x S y O z Inorganic sulfur components and ROSO 2 The organic sulfur-containing component of Li, wherein x is 1 to 3, y is 1 to 3, z is 2 to 6, and R is a substituted or unsubstituted alkyl group.

[0348] From the comparison between Examples 1 and 9-10, it can be seen that, based on the total mass of the electrolyte, the mass content of the carbonate additive is 3% to 8%, which can further take into account the high temperature storage stability and cycle life of the secondary battery.

[0349] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and embodiments having substantially the same structure as the technical idea and exerting the same effects within the scope of the technical solution of the present disclosure are all included in the technical scope of the present disclosure. In addition, within the scope of the present disclosure, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present disclosure.

Claims

1. A battery cell, characterized in that: Including positive electrode sheet, negative electrode sheet and electrolyte; The electrolyte includes a solvent, the solvent includes a chain carboxylic acid ester solvent, and the conductivity of the electrolyte is 13mS / cm to 20mS / cm; The negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged 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 energy spectrum of the negative electrode material has a sulfur element 2p characteristic peak with a binding energy of 162eV~170eV.

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 a general formula of Li x S y O z The inorganic sulfur-containing component and the organic sulfur-containing component of ROSO2Li, wherein 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 ring-structured sulfur-containing additive.

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

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 additive includes one or more of 1,3-propane sultone, 1,3-propylene sultone, 1,4-butane sultone, methylene methane disulfonate and derivatives thereof.

12. The battery cell according to claim 6, characterized in that: The sulfate additive includes one or more of vinyl sulfate, vinyl disulfate, vinyl trisulfate, 4-methyl vinyl sulfate, 4-ethyl vinyl sulfate, 4-propyl vinyl sulfate, 4-butyl vinyl sulfate and derivatives thereof.

13. The battery cell according to claim 6, characterized in that: The sulfite additive includes one or more of vinyl sulfite, vinyl vinyl sulfite, butylene sulfite, propylene sulfite and derivatives thereof.

14. The battery cell according to claim 5, characterized in that: The sulfur-containing additive includes one or more of methylene methanedisulfonate, vinyl sulfate, vinyl disulfate, vinyl trisulfate, vinyl sulfite, butylene sulfite and derivatives thereof.

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

16. The battery cell according to claim 5, characterized in that: The volume distribution particle size Dv50 of the negative electrode material 负 The particle size 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, characterized in that: The volume distribution particle size Dv50 of the negative electrode material 负 The particle size 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 also includes carbonate additives, and the carbonate additives include one or more of vinylene carbonate and fluoroethylene carbonate.

19. The battery cell according to claim 18, characterized in that: The electrolyte includes vinylene carbonate and fluoroethylene carbonate.

20. The battery cell according to claim 18, characterized in that: 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, characterized in that: 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, characterized in that: The mass content of vinylene carbonate in the electrolyte is 1.5% to 8% based on the total mass of the electrolyte.

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, characterized in that: 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 ~9.4m 2 / g; the electrolyte also includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte is 2%-6%.

28. The battery cell according to claim 26, characterized in that The specific surface area of ​​the positive electrode active material is 9.5 m 2 / g ~18m 2 / g; the electrolyte also includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to 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 as shown in Formula IV, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula IV where 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, characterized in that The specific surface area of ​​the olivine-structured lithium-containing phosphate is 5.0 m 2 / g ~18.0m 2 / g.

31. The battery cell according to claim 26, characterized in that The positive electrode active material includes a lithium-containing transition metal oxide, and its composition general formula is as shown in Formula V, Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula V where 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 ~2m 2 / g; the electrolyte also 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 the 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 having a NASICON structure as shown in Formula VI, <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> 3-b3 <h2 style=";text-align:left;direction:ltr"> Fe<h2 style=";text-align:left;direction:ltr"> 2-b3 <h2 style=";text-align:left;direction:ltr"> M2<h2 style=";text-align:left;direction:ltr"> b3 <h2 style=";text-align:left;direction:ltr"> (PO<h2 style=";text-align:left;direction:ltr"> x3 <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> y3 <h2 style=";text-align:left;direction:ltr"> VI In the Formula VI, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, and 2 ≤ y3 ≤ 4.

35. The battery cell according to claim 34, characterized in that: M2 is +4 valence.

36. The battery cell according to claim 26, characterized in that 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, dilithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, 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 proportion 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, characterized in that The graphite comprises composite graphite particles, the composite graphite particles comprise main particles and a coating layer arranged on the surface of the main particles, the main particles comprise artificial graphite, the coating layer comprises amorphous carbon, and the composite graphite particles comprise secondary particles.

40. The battery cell according to claim 39, characterized in that The mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5% based on the total mass of the composite graphite particles.

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 0.04Ω•cm; (2) The powder compaction density of the negative electrode material under a pressure of 20000N is 1.5g / cm 3 Up to 1.8g / cm 3 .

42. The battery cell according to claim 41, characterized in that The powder compaction density of the negative electrode material under a pressure of 20000N is 1.55g / cm 3 Up to 1.75g / cm 3 .

43. The battery cell according to claim 1, characterized in that The negative electrode material also includes a silicon-based material, which includes one or more of a silicon-oxygen 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, characterized in that 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 carbonate additives in the electrolyte is 3%-10%.

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

47. The battery cell according to claim 46, characterized in that 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, 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 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, 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 14.3 μm.

52. 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 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% to 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 fluoroethylene carbonate is 0.5% to 2%.

55. 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 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% to 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 of the chain carboxylic acid ester accounts for 25.5%-63.75%.

58. The battery cell according to claim 1, characterized in that The chain carboxylic acid ester has a general structural formula of R1-COO-R2, wherein R1 and R2 each independently include at least one of a C1-C5 alkyl group and a C1-C5 halogenated alkyl group.

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

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 of the carbonate solvent accounts for 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 of the carbonate solvent accounts for 21.25%-59.5%.

62. The battery cell according to claim 60, characterized in that 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, characterized in that The electrolyte includes 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.

65. The battery cell according to claim 1, characterized in that 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, characterized in that The lithium salt includes one or more of a fluorine-containing sulfonyl imide salt and lithium hexafluorophosphate.

68. The battery cell according to claim 67, characterized in that The fluorine-containing sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)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, characterized in that 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 further includes a separator, wherein the separator includes a porous base membrane and a functional layer disposed on at least one side of the porous base membrane, and the thickness of the porous base membrane is ≤12 μm.

72. The battery cell according to claim 71, characterized in that 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 isolation film is 20%-70%.

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

75. The battery cell according to claim 71, characterized in that The functional layer includes a first functional layer arranged on the negative electrode side of the porous base membrane and a second functional layer arranged on the positive electrode side of the porous base membrane, the first functional layer includes first inorganic particles, 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 are attached to the surface of the non-fluorinated polymer particles and / or dispersed inside the non-fluorinated polymer particles.

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

78. 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 minutes to 15 minutes.

79. A battery device, characterized in that: Comprising the battery monomer described in any one of claims 1 to 78, the battery device comprises at least one of a battery module, a battery pack, and an energy storage battery.

80. An electrical device, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 78.

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