Battery cell, battery device, and electrical device

Abstract

The present application provides a battery cell, a battery device, and an electrical device. The battery cell includes a positive electrode plate, a negative electrode plate, and an electrolytic solution; the electrolytic solution includes a solvent, the solvent includes a chain carboxylic acid ester solvent, and the conductivity of the electrolytic solution is 13 mS / cm to 20 mS / cm; the negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector, the negative electrode film layer includes a negative electrode material, and the X-ray photoelectron spectroscopy (XPS) of the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy located at 132 eV to 138 eV.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of PCT patent application PCT / CN2024 / 106835 titled "Battery Cell, Battery Device and Electrically - powered Device" filed on July 22, 2024, the entire content of which is incorporated herein by reference. Technical field

[0003] This application relates to the technical field of battery cells, and particularly to a battery cell, a battery device and an electrically - powered device. Background art

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

[0005] With the dual increase in the market's demand for the charging efficiency of electrically - powered devices and the service life in special environments, higher requirements are also put forward for the kinetic performance, high - temperature stability, etc. of battery cells. However, it is difficult to simultaneously improve the above - mentioned performances in the prior art, which has become a technical problem that urgently needs to be solved in this field. Summary of the invention

[0006] This application is made in view of the above - mentioned problems, and its purpose is to provide a battery cell and an electrically - powered device that can improve the high - temperature stability of the battery cell while taking into account the kinetic performance of the battery cell.

[0007] In a first aspect of this application, a battery cell is provided, which includes a positive electrode tab, a negative electrode tab and an electrolyte; the electrolyte includes a solvent, the solvent includes a chain - like carboxylic acid ester solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; the negative electrode tab includes a negative current collector and a negative electrode film layer provided on at least one side of the negative current collector, the negative electrode film layer includes a negative electrode material, and the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy in the range of 132 eV to 138 eV in X - ray photoelectron spectroscopy (XPS).

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

[0009] In any embodiment, the 2p characteristic peak of the phosphorus element includes a first phosphorus-containing sub-peak with a binding energy of 133 eV to 134.5 eV and / or a second phosphorus-containing sub-peak with a binding energy of 136 eV to 137.5 eV.

[0010] The 2p characteristic peak of the phosphorus element can be a single peak with one peak top or a multi-peak with multiple peak tops. Whether it is a single peak or a multi-peak, the XPSpeak software can be used to perform peak fitting on the characteristic peak of the P2p energy spectrum to obtain sub-peaks. The standard spectrum and the electron splitting energy level analysis show that the first sub-peak with a binding energy of 133 eV to 134.5 eV corresponds to the phosphorus element in x PO y F z and the second sub-peak with a binding energy of 136 eV to 137.5 eV corresponds to the phosphorus element in x0 PF z0 , where x is from 1 to 3, y is from 2 to 6, z is from 0 to 6, x0 is from 1 to 3, and z0 is from 1 to 6. The phosphorus-containing components in the above SEI film can improve the erosion resistance and thermal stability at high temperature of the SEI film on the surface of the negative electrode material, and improve the kinetic performance and storage stability of the battery cell.

[0011] In any embodiment, the X-ray photoelectron spectroscopy (XPS) of the negative electrode material has a fluorine element 1s characteristic peak with a binding energy located at 684.5 eV to 686 eV.

[0012] The standard spectrum and the electron splitting energy level analysis show that the fluorine-containing sub-peak with a binding energy of 684.5 eV to 686 eV corresponds to the fluorine element in x PO y F z or x0 PF z0 . The above fluorine-containing components in the SEI film can improve the erosion resistance and thermal stability at high temperature of the SEI film on the surface of the negative electrode material, and improve the kinetic performance and storage stability of the battery cell.

[0013] In any embodiment, on the surface of the negative electrode film layer away from the negative electrode current collector, there are included inorganic phosphorus-containing components with the general formula of x PO y F z and / or with the general formula of x0 PF z0 , where x is from 1 to 3, y is from 2 to 6, z is from 0 to 6, x0 is from 1 to 3, and z0 is from 1 to 6.

[0014] In any embodiment, the electrolyte includes a phosphorus-containing additive. Optionally, the phosphorus-containing additive includes one or more of lithium difluoro(oxalato)phosphate (LiODFP), lithium difluorophosphate (LiPO2F2), tris(trimethylsilyl) phosphate (TMSP), triphenylphosphine oxide (TPPO), pentafluoro(phenoxy)cyclotriphosphazene (PFPN), N-(triphenylphosphoranylidene)aniline (TPPA), diethyl phenylphosphonate (DEPP), triphenyl phosphite (TPPi), methyl diphenylphosphite (MDP), triethyl phosphite (TEP), and N,N-diallyl-diethoxyphosphoramide (DADEPA).

[0015] In any embodiment, the phosphorus-containing additive includes one or more of lithium difluoro(oxalato)phosphate (LiODFP), lithium difluorophosphate (LiPO2F2), pentafluoro(phenoxy)cyclotriphosphazene (PFPN), N-(triphenylphosphoranylidene)aniline (TPPA), diethyl phenylphosphonate (DEPP), and triphenyl phosphite (TPPi).

[0016] Phosphorus-containing additives often have a relatively high potential. The phosphorus-containing additives added to the electrolyte will react preferentially during formation or subsequent cycling, evolving into phosphorus-containing components in the SEI film and improving the storage stability of the battery cell. It can be understood that, in some embodiments, the phosphorus-containing additives added to the electrolyte are completely converted into phosphorus-containing components in the SEI film during formation. In some embodiments, there are still residual phosphorus-containing additives in the electrolyte, which form a reinforcing effect on the SEI film during subsequent cycling of the battery cell.

[0017] In any embodiment, the phosphorus-containing additive further includes fluorine. Optionally, the phosphorus-containing additive includes one or more of lithium difluoro(oxalato)phosphate (LiODFP), lithium difluorophosphate (LiPO2F2), and pentafluoro(phenoxy)cyclotriphosphazene (PFPN).

[0018] The above-mentioned phosphorus-containing additives include both phosphorus and fluorine elements, and are prone to evolving into inorganic phosphorus-containing components with the general formula Li x PO y F z and / or inorganic phosphorus-containing components with the general formula Li x0 PF z0 in the SEI film during formation and initial cycling, effectively taking into account the kinetic performance and high-temperature stability of the battery cell.

[0019] In any embodiment, based on the total mass of the electrolyte, the mass content of the phosphorus-containing additive in the electrolyte of the battery cell is 0.1% - 3%.

[0020] An electrolyte with the mass content of the phosphorus-containing additive in the electrolyte of the battery cell within the above range is beneficial to strengthening the SEI film during cycling, taking into account the kinetic performance and storage stability of the battery cell.

[0021] In any embodiment, the volume distribution particle size Dv50 of the negative electrode material 负 is 7.8 μm - 14.3 μm.

[0022] Dv50 负 The negative electrode active material within the above range simultaneously includes a certain content of small particles and large particles, enabling the battery cell to improve the lithium-ion transmission rate through small particles, improve the kinetic performance, and improve the compaction density of the battery cell electrode sheet through the particle size grading of large and small particles, improve the energy density of the battery cell, and achieve a balance between kinetic performance and energy density.

[0023] In any embodiment, the volume distribution particle size Dv50 of the negative electrode material 负 is 7.8 μm - 10.8 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.3% - 1.8%.

[0024] Volume distribution particle size Dv50 负 The negative electrode active material within the above range can shorten the diffusion distance of lithium ions in the solid phase and improve the kinetic performance of the battery cell. However, the negative electrode active material with the volume distribution particle size Dv50 负 within the above range has a relatively large surface area and surface activity, and a relatively stronger reaction activity with chain carboxylic ester solvents. Therefore, a higher content of phosphorus-containing additive is required in the electrolyte to achieve both kinetic performance and storage stability.

[0025] In any embodiment, the volume distribution particle size Dv50 of the negative electrode active material 负 is 10.8 μm - 14.3 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.1% - 1.3%.

[0026] 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.

[0027] The phosphorus-containing component on the surface of the negative electrode material increases the brittleness of the SEI film while improving the high-temperature stability of the SEI film. The carbonate additive can evolve into an organic component in the SEI film, improve the toughness of the SEI film, act together with the phosphorus-containing component in the SEI film, improve the stability of the SEI film during the cycling of the battery cell, and improve the cycle life of the battery cell.

[0028] In any embodiment, the electrolyte includes vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0029] Chain carboxylic esters have high activity. While improving the wettability between the electrolyte and the electrode sheet and the conductivity of the electrolyte, they will also erode the solid electrolyte interface (SEI) film. Vinylene carbonate (VC) has a reduction potential close to that of chain carboxylic esters, which can inhibit the reaction activity of chain carboxylic esters, improve the compactness of the SEI film, 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 film. By adding a phosphorus-containing additive, vinylene carbonate (VC), and fluoroethylene carbonate (FEC) to the electrolyte, the kinetic performance, storage stability, and cycle life of the battery cell can be more effectively balanced.

[0030] 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%.

[0031] The electrolyte with the mass content of the carbonate additive within the above range can not only improve the cycle stability of the SEI film, but also control the degree of side reactions, and comprehensively improve the cycle life of the battery cell.

[0032] 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%.

[0033] 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%.

[0034] By adding vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the electrolyte, the kinetic performance and cycle stability of the battery cell can be effectively balanced.

[0035] In any embodiment, the positive electrode sheet includes a positive current collector and a positive electrode film layer located on at least one surface of the positive current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes one or more of lithium phosphate with an olivine structure and lithium-containing transition metal oxides.

[0036] In any embodiment, the specific surface area of the positive electrode active material is 5.0 m 2 / g to 9.4 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 2% - 6%.

[0037] In any embodiment, the specific surface area of the positive electrode active material is 9.5 m 2 / g to 18 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 3% - 8%.

[0038] The positive electrode active material with a large specific surface area has a large contact area with the electrolyte, which can improve the kinetic performance of the battery cell. However, the positive electrode active material with a large specific surface area is more likely to absorb water molecules in the air, and it is difficult for the water molecules to be discharged from the positive electrode film layer during the drying and film-forming process. During the cycling of the battery cell, the water molecules react with the electrolyte salt in the electrolyte to generate hydrofluoric acid, which corrodes the SEI film on the surface of the negative electrode material. The content of hydrofluoric acid generated by the positive electrode active material with a high specific surface area in the battery cell is high. The high content of the carbonate additive can improve the compactness of the SEI film on the surface of the negative electrode material, taking into account the kinetic performance and cycling stability of the battery cell.

[0039] In any embodiment, the positive electrode active material includes a lithium-containing phosphate with an olivine structure, and its compositional general formula is shown in Formula I,

[0040] Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I,

[0041] wherein, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.7 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, and 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

[0042] The lithium-containing phosphate with an olivine structure having the above components has good structural stability and low irreversible loss during fast charging, so as to improve the cycling stability of the battery cell.

[0043] In any embodiment, the specific surface area of the lithium-containing phosphate with an 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 shown in Formula II,

[0045] Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula II

[0046] 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 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, Ce; Y includes one or more of O and F.

[0047] 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%.

[0048] In any embodiment, the positive electrode active material further includes an ion-conducting layer disposed on the surface of the lithium-containing phosphate. The ion-conducting layer includes carbon and iron elements. Based on the total mass of the positive electrode active material, the mass percentage of carbon element is 1% - 2%.

[0049] The above ion-conducting layer can simultaneously improve the ion conductivity and electrical conductivity of the positive electrode active material, improve the solid-phase transport rate of ions and electrons, and improve the kinetic performance of the battery cell.

[0050] In any embodiment, the ion-conducting layer contains a fast ion conductor having a NASICON structure as shown in Formula III,

[0051] Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula III,

[0052] In the formula III, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn. Optionally, M2 is +4-valent, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, and 2 ≤ y3 ≤ 4.

[0053] The fast ion conductor with NASICON structure has rich three-dimensional lithium ion diffusion and transport channels, and has advantages such as high ion conduction efficiency and strong structural stability during multiple lithium deintercalation and intercalation processes. Coating the lithium-containing phosphate surface with an ion conductor containing NASICON structure can significantly improve the transport rate of lithium ions during multiple deintercalation / intercalation at the positive electrode, improve the ion conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cell.

[0054] In any embodiment, the positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes one or more of ternary lithium supplement materials, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and lithium citrate.

[0055] Adding a lithium supplement agent to the positive electrode active layer can offset the irreversible lithium loss during the electrochemical process to improve the total capacity and energy density of the battery cell.

[0056] In any embodiment, based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.1% - 10%.

[0057] In any embodiment, the negative electrode material includes graphite. [[ID=1,7]]

[0058] In any embodiment, the graphite includes composite graphite particles, the composite graphite particles include a main body particle and a coating layer disposed on the surface of the main body particle, the main body particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0059] The composite graphite particles including secondary particles and the surface coating layer including amorphous carbon are both beneficial to the infiltration of the electrolyte in the negative electrode active layer of the electrode sheet, and contribute to the improvement of the rate performance of the battery cell.

[0060] In any embodiment, based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5%.

[0061] When the content of amorphous carbon is within a suitable range, the composite graphite material can have high specific capacity while also having high active ion solid-phase transport ability, which is beneficial to the improvement of the kinetic performance of the battery cell.

[0062] In any embodiment, the powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm.

[0063] In any embodiment, the powder compaction density of the negative electrode material under a pressure of 20,000 N is 1.5 g / cm 3 to 1.8 g / cm 3 and may be optionally 1.55 g / cm 3 to 1.75 g / cm 3 .

[0064] The negative electrode material with a powder compaction density within a suitable range can make the negative electrode active layer have a higher compaction density, and thus the battery cell has a higher energy density; meanwhile, during the cycling process, the original pore structure of the negative electrode active layer can be maintained, which is beneficial to improving the retention of the high kinetic performance of the battery cell during the cycling process.

[0065] In any embodiment, the negative electrode material further includes a silicon-based material, and the silicon-based material includes one or more of silicon oxides and silicon-carbon composites; based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material is 0.3% - 10%, and may be optionally 1% - 6%.

[0066] The introduction of the silicon-based material is beneficial to improving the energy density of the battery cell. The silicon-based material within the above mass range can balance the energy density and cycle stability of the battery cell.

[0067] In any embodiment, the negative electrode material includes a silicon-based material, and the added mass content of carbonate additives in the electrolyte is 3% - 10%.

[0068] The silicon-based material is prone to expand during the cycling process, resulting in the rupture of the SEI film on the surface of the negative electrode material. Therefore, it consumes more additives. The carbonate additives within the above range can improve the compactness and regeneration ability of the SEI film, and balance the energy density and cycle stability of the battery cell.

[0069] In any embodiment, the negative electrode film layer includes a first negative electrode film layer disposed on the surface of the negative electrode current collector and a second negative electrode film layer disposed on the side of the first negative electrode film layer away from the negative electrode current collector, 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.

[0070] The arrangement of the composite graphite particles near the electrolyte side can balance the energy density while improving the kinetic performance of the battery cell.

[0071] In any embodiment, the ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer is 3:7 to 7:3.

[0072] In any embodiment, the volume-average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 μm to 18.5 μm, and may be optionally 9.5 μm to 14.8 μm.

[0073] In any embodiment, the volume-average particle size Dv502 of the negative electrode active material in the second negative electrode active layer is 7.8 μm to 14.3 μm, and may be optionally 7.8 μm to 12.8 μm.

[0074] The second negative electrode active material layer disposed on the electrolyte side includes negative electrode active materials with smaller particle sizes, which can further improve the solid-liquid transport rate of ions in the battery electrode sheet and improve the kinetic performance of the battery monomer.

[0075] In any embodiment, 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%.

[0076] 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%.

[0077] In any embodiment, 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%.

[0078] A relatively small volume-average particle size Dv502 of the negative electrode material in the second negative electrode film layer is beneficial to the solid-phase diffusion of lithium ions in the negative electrode active material. However, at the same time, it will increase the reaction activity between the negative electrode active material and the chain carboxylic 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 monomer can be improved.

[0079] 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%.

[0080] In any embodiment, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic ester is 25.5% - 63.75%.

[0081] In any embodiment, the chain carboxylic ester has a structural general formula of R1-COO-R2, where R1 and R2 each independently include at least one of an alkyl group with C1 to C5 and a halogenated alkyl group with C1 to C5.

[0082] In any embodiment, the chain carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

[0083] The electrolyte with the mass content of the chain carboxylic acid ester within the above range has good conductivity, wettability, and chemical stability, which is beneficial to the comprehensive improvement of the kinetic performance, storage stability, and cycle stability of the battery cell.

[0084] In any embodiment, the solvent further includes a carbonate solvent. Based on the total mass of the electrolyte, the mass content ratio of the carbonate solvent is 17% - 76.5%, and can be optionally 21.25% - 59.5%.

[0085] In any embodiment, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0086] In the electrolyte, the carbonate solvent and the lithium ions in the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of the lithium ions and anions in the lithium-containing electrolyte salt, thereby improving the kinetic performance of the battery cell.

[0087] In any embodiment, the carbonate solvent includes ethylene carbonate, and the mass ratio of ethylene carbonate to the chain carboxylic acid ester is 0.27:1 - 1.33:1.

[0088] The chain carboxylic acid ester can improve the wettability between the electrolyte and the electrode sheet, improve the solid-liquid transport rate of lithium ions between the electrolyte and the electrode sheet. At the same time, the addition of the chain carboxylic acid ester is also beneficial to the increase of the electrolyte conductivity; however, the chain carboxylic acid ester is prone to react with the SEI film, reducing the storage stability of the battery cell. And the ethylene carbonate in the electrolyte and the lithium ions in the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of the lithium ions and anions in the lithium-containing electrolyte salt. However, with the increase of the content of ethylene carbonate, the viscosity of the electrolyte will also increase, having a negative impact on the conductivity of the electrolyte. The mass ratio of ethylene carbonate to the chain carboxylic acid ester within the above range enables the electrolyte to have appropriate viscosity, conductivity, good dissociation rate, and wettability, which is beneficial to the comprehensive improvement of the kinetic performance and high-temperature stability of the battery cell.

[0089] 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 ethylene carbonate is 0.29 - 0.72.

[0090] 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 kinetic performance of the battery cell.

[0091] In any embodiment, the conductivity of the electrolyte is 15 mS / cm-20 mS / cm.

[0092] The electrolyte with a conductivity within the above range can better balance the dynamic performance and high-temperature stability of the battery cell.

[0093] In any embodiment, the lithium salt includes one or more of a fluorine-containing sulfonyl imide salt and lithium hexafluorophosphate LiPF6; alternatively, the fluorine-containing sulfonyl imide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0094] 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, as the temperature of the battery cells rises, the 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 and produce hydrofluoric acid during the secondary cycle, the addition of lithium hexafluorophosphate will greatly reduce the risk of thermal runaway of the battery cells, reducing the risk to a controllable range and improving the safety of the battery.

[0095] In any embodiment, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte is 0.2 mol / L-0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is 0.5 mol / L to 1.0 mol / L.

[0096] In any embodiment, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is (2-5):10.

[0097] The battery cell having the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte within the above ranges can take into account both the kinetic performance and safety performance of the battery cell.

[0098] In any embodiment, the battery cell further includes a separator, which includes a porous base membrane and a functional layer provided on at least one side of the porous base membrane. The thickness of the porous base membrane is ≤12 μm, and can be optionally less than or equal to 9 μm.

[0099] In any embodiment, the porosity of the porous base film in the separator film is 20% - 70%, optionally 35% - 60%.

[0100] In any embodiment, the functional layer includes a first functional layer disposed on the negative electrode side of the porous base film and a second functional layer disposed on the positive electrode side of the porous base film. The first functional layer includes first inorganic particles, and the second functional layer includes composite particles. The composite particles include second inorganic particles and non-fluoropolymer particles, and the second inorganic particles in the composite particles are attached to the surface of the non-fluoropolymer particles and / or dispersed inside the non-fluoropolymer particles.

[0101] Inorganic particles can improve the heat resistance of the first functional layer and the second functional layer and improve the kinetic performance of the battery cell.

[0102] In any embodiment, the non-fluoropolymer particles include acrylate copolymers.

[0103] In any embodiment, the injection coefficient of the battery cell is 2.2 g / Ah - 3.1 g / Ah.

[0104] In any embodiment, the fast charging time of the battery cell from 10% SOC to 80% SOC is 6 min - 15 min.

[0105] In a second aspect of the present application, there is provided a battery device, including the battery cell provided in the first aspect of the present application. The battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0106] In a third aspect of the present application, there is provided an electrical device, including the battery cell provided in the first aspect of the present application. Description of the Drawings

[0107] Figure 1 is the X-ray photoelectron spectroscopy diagram of phosphorus element of the negative electrode material in an embodiment of the present application.

[0108] Figure 2 is the X-ray photoelectron spectroscopy diagram of fluorine element of the negative electrode material in an embodiment of the present application.

[0109] Figure 3 is a schematic diagram of a battery cell in another embodiment of the present application.

[0110] Figure 4 is Figure 3 the exploded view of the battery cell shown in an embodiment of the present application.

[0111] Figure 5 is a schematic diagram of a battery module in an embodiment of the present application.

[0112] Figure 6 It is a schematic diagram of a battery pack according to an embodiment of the present application.

[0113] Figure 7 is Figure 6 An exploded view of the battery pack according to an embodiment of the present application shown.

[0114] 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.

[0115] Explanation of reference numerals:

[0116] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Specific embodiments

[0117] Hereinafter, embodiments of the battery cell and the electrical device of the present application specifically disclosed will be described in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to prevent the following description from becoming unnecessarily long and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0118] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the smallest range values 1 and 2 are listed, and if the largest range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

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

[0120] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0121] Unless otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0122] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present application mean open-ended or may also be closed-ended. For example, the "comprising" and "including" may mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0123] Unless otherwise specified, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0124] In order to improve the kinetic performance of a battery cell, a solvent with high conductivity, such as a chain carboxylic acid ester solvent, is often added to the electrolyte to achieve rapid ion transport and reduce the possibility of lithium precipitation. However, high-conductivity solvents often have high activity and will continuously erode the solid electrolyte interface (SEI) film on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI film in the battery cell during storage, and an increase in the DC internal resistance of the battery cell, thus reducing the use stability of the battery cell.

[0125] Based on this, the present application proposes a battery cell, including a positive electrode plate, a negative electrode plate, and an electrolyte; the electrolyte includes a solvent, the solvent includes a chain carboxylic ester solvent, and the conductivity of the electrolyte is greater than or equal to 13 mS / cm; the negative electrode plate includes a negative current collector and a negative electrode film layer provided on at least one side of the negative current collector, the negative electrode film layer includes a negative electrode material, and the X-ray photoelectron spectroscopy (XPS) of the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy located at 132 eV to 138 eV.

[0126] In the present application, the X-ray photoelectron spectroscopy (XPS) of the negative electrode material can be tested by any well-known method in the art. As an example, after disassembling the battery cell, the negative electrode plate is washed with a solvent such as dimethyl carbonate (DMC) more than three times and then powder is scraped for sampling. The obtained negative electrode material sample powder is adhered to a conductive substrate, and X-ray photoelectron spectroscopy is performed using an X-ray photoelectron spectrometer (such as AXIS ULTRA). The scanning rate and time of the X-ray source are adjusted to make it focused and detect elements and functional groups at a depth of 5 nm to 10 nm from the surface of the negative electrode material, and the X-ray photoelectron spectroscopy (XPS) spectrum of the sample is obtained. The element characteristic peaks are analyzed in the spectrum. The chain carboxylic ester solvent refers to a chain-like organic molecule containing a carboxylic ester group. As an example, it includes but is not limited to ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, methyl formate, etc.

[0127] The types and masses of the solvents in the electrolyte can be obtained by detecting the electrolyte by methods well-known to those skilled in the art. For example, the composition in the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Exemplarily, the battery cell is disassembled, and the free electrolyte is obtained from the battery cell. The free electrolyte in the battery cell is diluted with acetonitrile by 3 to 10 times to obtain a diluted electrolyte solution to be tested. Using a GC-MS 3100 organic component gas chromatograph, the above diluted electrolyte solution is placed in the instrument for full-scan qualitative analysis. The inlet temperature is 250 °C, and the scanning range is 35 μm to 270 μm. After the test is completed, the total ion current chromatogram of each organic substance is obtained. The types of the corresponding organic substances are compared according to the peak positions in the chromatogram, and the corresponding content percentages of each organic substance are calculated according to the peak areas.

[0128] The conductivity of the electrolyte is the ability to describe the conductive process formed by the directional movement of positive and negative ions dissociated in the electrolyte solution in an electric field, and can be tested by any well-known method in the art. As an example, take about 100 mL of electrolyte sample with a dry, clean and corrosion-resistant sample bottle, seal it and place it in a constant temperature water bath, shake the sample from time to time, and keep the temperature constant at 25 °C (deviation ±5 °C). After the temperature of the sample is constant, use a commercially available conductivity meter to test its conductivity. After wiping the conductivity meter clean with the calibration solution, vertically place it into the liquid to be tested, click to start the test, and record the test result after the data is stable for more than 10 s. In some embodiments, the conductivity of the electrolyte can be selected as 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, 20 mS / cm, 21 mS / cm, 22 mS / cm, 23 mS / cm, 24 mS / cm, 25 mS / cm or the numerical range between any two of them.

[0129] The electrolyte including chain carboxylic ester solvents and having a conductivity of 13 mS / cm - 20 mS / cm is beneficial to improving the kinetic performance of the battery cell. However, chain carboxylic ester solvents often have high activity and will continuously erode the solid electrolyte interface (SEI film) on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI film and continuous increase of the DC internal resistance of the battery cell during storage. The SEI film on the surface of the negative electrode material of the battery cell in this application contains phosphorus element, which can improve the erosion resistance of the SEI film and its thermal stability at high temperature, taking into account both the kinetic performance and storage stability of the battery cell.

[0130] In some embodiments, the 2p characteristic peak of the phosphorus element includes a first phosphorus-containing sub-peak with a binding energy of 133 eV - 134.5 eV and / or a second phosphorus-containing sub-peak with a binding energy of 136 eV - 137.5 eV.

[0131] The 2p characteristic peak of the phosphorus element can be a single peak with one peak top or a multi-peak with multiple peak tops. Whether it is a single peak or a multi-peak, the XPSpeak software can be used to perform peak fitting processing on the characteristic peak of the P2p energy spectrum to obtain sub-peaks. The standard spectrum and electron splitting energy level analysis show that the first sub-peak with a binding energy of 133 eV - 134.5 eV corresponds to the phosphorus element in x Li y PO z F, and the second sub-peak with a binding energy of 136 eV - 137.5 eV corresponds to the phosphorus element in x0 Li z0wherein x is 1 to 3, y is 2 to 6, z is 0 to 6, x0 is 1 to 3, and z0 is 1 to 6. The phosphorus-containing component in the SEI film can improve the corrosion resistance and thermal stability of the SEI film on the surface of the negative electrode material at high temperatures, thereby improving the dynamic performance and storage stability of the battery cell.

[0132] In some embodiments, the negative electrode material has a 1s characteristic peak of fluorine element with a binding energy between 684.5 eV and 686 eV in X-ray photoelectron spectroscopy (XPS).

[0133] In some embodiments, the negative electrode material exhibits a 1s characteristic peak of fluorine with a binding energy between 684.5 and 686 eV in X-ray photoelectron spectroscopy (XPS) at a depth of 5 nm to 10 nm from the surface. The presence of a 1s characteristic peak of fluorine with a binding energy between 684.5 and 686 eV in the X-ray photoelectron spectroscopy (XPS) of the negative electrode material indicates that the SEI film on the surface of the negative electrode material includes fluorine. This fluorine-containing component in the SEI film can enhance the corrosion resistance and thermal stability of the SEI film on the surface of the negative electrode material at high temperatures, thereby improving the dynamic performance and storage stability of the battery cell.

[0134] In some embodiments, the negative electrode film layer includes a general formula of Li on the surface away from the negative electrode current collector. x PO y F z Inorganic phosphorus-containing components and / or general formula Li x0 PF z0 The inorganic phosphorus-containing components, wherein x is 1-3, y is 2-6, z is 0-6, x0 is 1-3, and z0 is 1-6. The XPS full spectrum test of the negative electrode material shows that the cations at a depth of 5nm-10nm from the surface of the negative electrode material are mainly lithium ions. Therefore, it can be inferred that the negative electrode material at a depth of 5nm-10nm from the surface includes the general formula Li x PO y F z Inorganic phosphorus-containing components and / or general formula Li x0 PF z0 Inorganic phosphorus components.

[0135] In some embodiments, x can be selected as 1, 2, 3 or a numerical range between any two thereof, y can be selected as 2, 3, 4, 5, 6 or a numerical range between any two thereof, z can be selected as 0, 1, 2, 3, 4, 5, 6 or a numerical range between any two thereof, x0 can be selected as 1, 2, 3 or a numerical range between any two thereof, and z0 can be selected as 1, 2, 3, 4, 5, 6 or a numerical range between any two thereof.

[0136] In some embodiments, the electrolyte includes a phosphorus-containing additive. Optionally, the phosphorus-containing additive includes one or more of lithium bis(oxalato)difluorophosphate (LiODFP), lithium difluorophosphate (LiPO2F2), tris(trimethylsilyl) phosphate (TMSP), triphenylphosphine oxide (TPPO), pentafluoro(phenoxy)cyclotriphosphazene (PFPN), N-(triphenylphosphoranylidene)aniline (TPPA), diethyl phenylphosphonate (DEPP), triphenyl phosphite (TPPi), methyl diphenyl phosphite (MDP), triethyl phosphite (TEP), and N,N-diallyl-N,N-diethoxyphosphoramidate (DADEPA).

[0137] In some embodiments, the phosphorus-containing additive includes one or more of lithium bis(oxalato)difluorophosphate (LiODFP), lithium difluorophosphate (LiPO2F2), pentafluoro(phenoxy)cyclotriphosphazene (PFPN), N-(triphenylphosphoranylidene)aniline (TPPA), diethyl phenylphosphonate (DEPP), and triphenyl phosphite (TPPi).

[0138] An additive refers to a component with a relatively low content in the electrolyte, generally with a mass ratio in the electrolyte not exceeding 10%. It has the characteristics of strong pertinence and small dosage, and can significantly optimize a certain aspect of the battery performance without changing the production process.

[0139] The components of the additive can be measured by any well-known method in the art. For example, the composition in the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Exemplarily, an ion chromatograph (IC) can be used to test the content of inorganic substances in the electrolyte. Weigh a certain amount of electrolyte (the dilution concentration is in the middle of the standard curve), dilute it to 100 mL with ultrapure water, and automatically inject the sample into the ion chromatograph for detection. Test the ion chromatogram of inorganic substances, and compare the corresponding inorganic substance types according to the peak positions in the chromatogram. Dilute the above free electrolyte with acetonitrile by 3 to 10 times to obtain a diluted electrolyte solution to be tested. Use a GC-MS 3100 organic component gas chromatograph, place the above diluted electrolyte solution in the instrument for full-scan qualitative analysis, with the inlet temperature at 250 °C and the scanning range: 35 μm to 270 μm. After the test, obtain the total ion current chromatogram of each organic substance, and compare the corresponding organic substance types according to the peak positions in the chromatogram.

[0140] Phosphorus-containing additives often have a relatively high potential. The phosphorus-containing additives added to the electrolyte will react preferentially during formation or subsequent cycling processes, evolving into phosphorus-containing components in the SEI film, thereby improving the storage stability of the battery cell. It can be understood that, in some embodiments, the phosphorus-containing additives added to the electrolyte are completely converted into phosphorus-containing components in the SEI film during the formation process. In some embodiments, there are still residual phosphorus-containing additives in the electrolyte, which form a reinforcing effect on the SEI film during subsequent cycling of the battery cell.

[0141] In some embodiments, the phosphorus-containing additive further includes fluorine element. Optionally, the phosphorus-containing additive includes one or more of lithium difluorobis(oxalato)phosphate (LiODFP), lithium difluorophosphate (LiPO2F2), and pentafluoro(phenoxy)cyclotriphosphazene (PFPN).

[0142] The above phosphorus-containing additive includes both phosphorus element and fluorine element, and is liable to evolve into an inorganic phosphorus-containing component with the general formula Li x PO y F z in the SEI film and / or an inorganic phosphorus-containing component with the general formula Li x0 PF z0 during formation and the initial cycling process, effectively taking into account the kinetic performance and high-temperature stability of the battery cell.

[0143] In some embodiments, based on the total mass of the electrolyte, the mass content of the phosphorus-containing additive in the electrolyte of the battery cell is 0.1% - 3%.

[0144] In some embodiments, based on the total mass of the electrolyte, the mass content of the phosphorus-containing additive can be optionally 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%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3% or the numerical range between any two of them.

[0145] The types and quality of the phosphorus-containing additives in the electrolyte can be obtained by detecting the electrolyte through methods well-known to those skilled in the art. For example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Exemplarily, an ion chromatograph (IC) is used to test the content of inorganic substances in the electrolyte. A quantitative electrolyte (the dilution concentration is in the middle of the standard curve) is weighed and fixed to 100 mL with ultrapure water, and the ion chromatograph automatically injects samples for detection to test the ion chromatogram of inorganic substances. According to the peak position of the chromatogram, the corresponding types of inorganic substances are compared, and the percentage of the content of the corresponding inorganic ions is calculated according to the peak area. The above free electrolyte is diluted 3 to 10 times with acetonitrile to obtain a diluted electrolyte to be tested. Using a GC-MS 3100 gas chromatograph for organic components, the above diluted electrolyte is placed in the instrument for full-scan qualitative analysis. The inlet temperature is 250 °C, and the scanning range is 35 μm to 270 μm. After the test is completed, the total ion current chromatogram of each organic substance is obtained. According to the peak position of the chromatogram, the corresponding types of organic substances are compared, and the percentage of the content of each organic substance is calculated according to the peak area. The mass of the phosphorus-containing additive measured is divided by the mass of the electrolyte sample as the mass content of the phosphorus-containing additive in the electrolyte of the battery cell. It can be understood that the mass content of the phosphorus-containing additive in the electrolyte of the battery cell is slightly lower than the added mass content of the phosphorus-containing additive in the electrolyte of the battery cell.

[0146] The electrolyte with the mass content of the phosphorus-containing additive in the electrolyte of the battery cell within the above range is beneficial to reinforcing the SEI film during the cycling process, taking into account the kinetic performance and storage stability of the battery cell.

[0147] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material 负 is 7.8 μm - 14.3 μm.

[0148] The volume distribution particle size Dv50 of the negative electrode material 负 has the meaning well-known in the art, which represents the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%, and can be measured by instruments and methods known in the art. For example, it can be conveniently measured with a laser particle size analyzer by referring to GB / T 19077-2016 Laser diffraction method for particle size distribution. The test instrument can be a Mastersizer 3000 type laser particle size analyzer of Malvern Instruments Limited, UK.

[0149] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material 负It can be optionally 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 the numerical range between any two of them.

[0150] Dv50 负 The negative electrode active material within the above range includes a certain content of small particles and large particles at the same time, so that the battery cell can improve the lithium ion transmission rate and the kinetic performance through small particles, and can improve the compaction density of the battery cell electrode sheet and the energy density of the battery cell through the particle size grading of large and small particles, realizing the balance between kinetic performance and energy density.

[0151] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material 负 is 7.8μm to 10.8μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.3% to 1.8%.

[0152] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material 负 can be optionally 7.8μm, 7.9μm, 8μm, 8.1μm, 8.2μm, 8.3μm, 8.4μm, 8.5μm, 8.6μm, 8.7μm, 8.8μm, 8.9μm, 9μm, 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 the numerical range between any two of them, and the mass content of the phosphorus-containing additive in the electrolyte can be optionally 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8% or the numerical range between any two of them.

[0153] Volume distribution particle size Dv50 负 The negative electrode active material within the above range can shorten the diffusion distance of lithium ions in the solid phase and improve the kinetic performance of the battery cell. However, the volume distribution particle size Dv50 负The negative electrode active material within the above range has a relatively large surface area and surface activity, and is relatively more reactive with chain carboxylate solvents. Therefore, a higher content of phosphorus-containing additives is required in the electrolyte to achieve a balance between kinetic performance and storage stability.

[0154] In some embodiments, the volume distribution particle size Dv50 of the negative electrode active material is 负 The particle size is 10.8 μm to 14.3 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.1% to 1.3%.

[0155] The volume distribution particle size Dv50 of the negative electrode active material 负 The phosphorus-containing additive may be present in an electrolyte solution of 10.8 μm, 10.9 μm, 11 μm, 11.1 μm, 11.2 μm, 11.3 μm, 11.4 μm, 11.5 μm, 11.6 μm, 11.7 μm, 11.8 μm, 12.8 μm, 13.8 μm, 14.3 μm or any range therebetween, and the mass content of the phosphorus-containing additive in the electrolyte may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3% or any range therebetween.

[0156] 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.

[0157] In the present application, carbonate additives refer to compounds including carbonate groups (—O—CO—O—) and their derivatives, as well as mixtures containing the above compounds and their derivatives.

[0158] The phosphorus-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, improving the toughness of the SEI film and working together with the phosphorus-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.

[0159] In some embodiments, the electrolyte includes vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0160] Chain carboxylic acid esters have high activity. While improving the wettability between the electrolyte and the electrode sheet and the conductivity of the electrolyte, they will also erode the solid electrolyte interface (SEI) film. Vinylene carbonate (VC) has a reduction potential close to that of chain carboxylic acid esters, can inhibit the reaction activity of chain carboxylic acid esters, improve the compactness of the SEI film, and improve the cycle life of the battery monomer. The combination of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) can balance the interfacial impedance of the battery and the high-temperature stability of the SEI film. By adding phosphorus-containing additives, vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the electrolyte, the kinetic performance, storage stability and cycle life of the battery monomer can be more effectively balanced.

[0161] 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%.

[0162] In some embodiments, based on the total mass of the electrolyte, the mass content of the carbonate additive can be optionally 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or the numerical range between any two of them.

[0163] The electrolyte with the mass content of the carbonate additive within the above range can not only improve the cycle stability of the SEI film, but also control the degree of side reactions, and comprehensively improve the cycle life of the battery monomer.

[0164] 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%.

[0165] In some embodiments, based on the total mass of the electrolyte, the mass content of vinylene carbonate (VC) in the electrolyte can be optionally 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% or the numerical range between any two of them.

[0166] 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%.

[0167] In some embodiments, based on the total mass of the electrolyte, the mass content of fluoroethylene carbonate (FEC) in the electrolyte can be optionally 0.1%, 0.2%, 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 the numerical range between any two of them.

[0168] By adding vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the electrolyte, the kinetic performance and cycle stability of the battery cell can be effectively balanced.

[0169] In some embodiments, the positive electrode sheet 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.

[0170] In some embodiments, the specific surface area of the positive electrode active material is 5.0 m 2 / g to 9.4 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte is 2% - 6%.

[0171] In the present application, the specific surface area of the positive electrode active material has the meaning well-known in the art and can be measured by instruments and methods known in the art. For example, it can be measured by the nitrogen adsorption specific surface area analysis test method with reference to GB / T 19587 - 2017 and calculated by the BET (Brunauer Emmett Teller) method. The test instrument can be the Tri-Star 3020 specific surface area and pore size analyzer of Micromeritics, USA.

[0172] In some embodiments, the specific surface area S of the positive electrode active material can be selected as 5 m 2 / g, 5.4 m 2 / g, 6 m 2 / g, 6.4 m 2 / g, 7 m 2 / g, 7.4 m 2 / g, 8 m 2 / g, 8.4 m 2 / g, 9 m 2 / g, 9.4 m 2 / g or any value range between any two of them, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte can be selected as 2%, 3%, 4%, 5%, 6% or any value range between any two of them.

[0173] In some embodiments, the specific surface area of the positive electrode active material is 9.5 m 2 / g to 18 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte is 3% - 8%.

[0174] In some embodiments, the specific surface area of the positive electrode active material may be selected from 9.5 m 2 / g, 10 m 2 / g, 10.5 m 2 / g, 11 m 2 / g, 11.5 m 2 / g, 12 m 2 / g, 12.5 m 2 / g, 13 m 2 / g, 13.5 m 2 / g, 14 m 2 / g, 14.5 m 2 / g, 15 m 2 / g, 15.5 m 2 / g, 16 m 2 / g, 16.5 m 2 / g, 17 m 2 / g, 17.5 m 2 / g, 18 m 2 / g or a numerical range between any two of them, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte may be selected from 3%, 4%, 5%, 6%, 7%, 8% or a numerical range between any two of them.

[0175] The positive electrode active material with a large specific surface area has a large contact area with the electrolyte, which can improve the kinetic performance of the battery cell. However, the positive electrode active material with a large specific surface area is more likely to absorb water molecules in the air, and it is difficult for the water molecules to be discharged from the positive electrode film layer during the drying and film-forming process. During the cycling of the battery cell, the water molecules react with the electrolyte salt in the electrolyte to generate hydrofluoric acid, which corrodes the SEI film on the surface of the negative electrode material. The content of hydrofluoric acid generated by the positive electrode active material with a high specific surface area in the battery cell is high. By using a high content of carbonate additive, the compactness of the SEI film on the surface of the negative electrode material can be improved, taking into account both the kinetic performance and the cycling stability of the battery cell.

[0176] In some embodiments, the positive electrode active material includes a lithium-containing phosphate with an olivine structure, and its general composition formula is as shown in Formula I,

[0177] Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I,

[0178] 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.

[0179] In some embodiments, x1 can be selected from 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or the numerical range between any two of them, y1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or the numerical range between any two of them, x1 + y1 can be selected from 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or the numerical range between any two of them, a1 can be selected from 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or the numerical range between any two of them, b1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5 or the numerical range between any two of them, a1 + b1 can be selected from 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or the numerical range between any two of them, c1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5 or the numerical range between any two of them, z1 can be selected from 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or the numerical range between any two of them.

[0180] 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.

[0181] In some embodiments, the specific surface area of the lithium-containing phosphate with olivine structure is 5.0 m 2 / g ~ 18.0m 2 / g.

[0182] In some embodiments, the specific surface area of the lithium-containing phosphate with olivine structure can be selected from 5.0 m 2 / g, 6.0 m 2 / g, 7.0m2 / g, 8.0 m 2 / g, 9.0 m 2 / g, 10.0 m 2 / g, 11.0 m 2 / g, 12.0 m 2 / g, 13.0 m 2 / g, 14.0 m 2 / g, 15.0 m 2 / g, 16.0 m 2 / g, 17.0 m 2 / g, 18.0 m 2 / g or a numerical range between any two of them.

[0183] In some embodiments, the positive electrode active material comprises a lithium-containing transition metal oxide, and its general composition formula is as shown in Formula II,

[0184] Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula II

[0185] Wherein, 0 ≤ x2 ≤ 2.1, 0 ≤ y2 ≤ 2.1, and 0.9 ≤ x2 + y2 ≤ 2.1; 0 ≤ a'2 ≤ 1, 0 ≤ b'2 ≤ 1, 0 ≤ c'2 ≤ 1, and 0.1 ≤ a'2 + b'2 + c'2 ≤ 1; 1.8 ≤ z2 ≤ 3.5; A comprises one or more of Na, K, Mg; M comprises 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, Ce; Y comprises one or more of O, F.

[0186] In some embodiments, x2 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or a numerical range between any two of them; y2 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or a numerical range between any two of them; and x2 + y2 can be optionally 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or a numerical range between any two of them; a2 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; b2 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; c2 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; and a2 + b2 + c2 can be optionally 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them; z2 can be optionally 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 or a numerical range between any two of them.

[0187] In some embodiments, the specific surface area of the lithium-containing transition metal oxide is 0.1 m 2 / g to 2 m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive in the electrolyte is 1% - 5%.

[0188] In some embodiments, the specific surface area of the lithium-containing transition metal oxide can be optionally 0.1 m 2 / g, 0.2 m 2 / g, 0.3 m 2 / g, 0.4 m 2 / g, 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1 m 2 / g, 1.1 m 2 / g, 1.2 m 2 / g, 1.3 m 2 / g, 1.4 m 2 / g, 1.5 m 2 / g, 1.6 m 2 / g, 1.7 m 2 / g, 1.8 m 2 / g, 1.9 m 2 / g, 2 m 2 / g or a numerical range between any two of them, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte can be optionally 1%, 2%, 3%, 4%, 5% or a numerical range between any two of them.

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

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

[0191] It should be noted that the ion-conducting layer can be a single-layer structure or a multi-layer structure. That is to say, the iron-containing component and the carbon-containing component in the ion-conducting layer can be a mixed phase or layered. It can be understood that the ion-conducting layer has a high ion transport rate. The above ion-conducting layer containing carbon can simultaneously improve the ion conductivity and electrical conductivity of the positive electrode active material, improve the solid-phase transport rate of ions and electrons, and improve the kinetic performance of the battery cell.

[0192] In some embodiments, the ion-conducting layer contains a fast ion conductor having a NASICON structure as shown in Formula III.

[0193] Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula III

[0194] In the Formula III, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn. Optionally, M2 is +4 valence, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, 2 ≤ y3 ≤ 4.

[0195] In some embodiments, b3 can be optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a numerical range between any two of them, x3 can be optionally 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or a numerical range between any two of them, and y3 can be optionally 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4 or a numerical range between any two of them.

[0196] The phase structure in the ion-conducting layer can be characterized by any well-known method in the art. For example, by characterizing the positive electrode active material through a transmission electron microscope, it can be seen that there are different phase structures in the ion-conducting layer and the matrix of the positive electrode active material. Combining the diffraction pattern and energy spectrum analysis can judge the fast ion conductor components in the ion-conducting layer.

[0197] The fast ion conductor with NASICON structure has rich three-dimensional lithium ion diffusion and transport channels, and has advantages such as high ion conduction efficiency and strong structural stability during multiple lithium deintercalation and intercalation processes. Coating the surface of the lithium-containing phosphate with a fast ion conductor containing NASICON structure can significantly improve the transport rate of lithium ions during multiple deintercalation / intercalation at the positive electrode end, improve the ion conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery monomer.

[0198] In some embodiments, the fast ion conductor includes one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, and Li2FeSn(PO4)3.

[0199] In some embodiments, the positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes one or more of a ternary lithium supplement material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and lithium citrate.

[0200] The lithium supplement agent generally refers to a material that decomposes and releases active lithium during the electrochemical process to make up for the irreversible loss of active lithium caused by the growth of the negative electrode SEI film. Adding a lithium supplement agent to the positive electrode active layer can offset the irreversible lithium loss during the electrochemical process to improve the total capacity and energy density of the battery monomer.

[0201] The ternary lithium supplement material refers to an oxide lithium supplement agent including one or more of nickel, cobalt, and manganese. In some embodiments, based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.1% - 10%.

[0202] In some embodiments, based on the total mass of the positive electrode film layer, the mass percentage of the lithium supplement agent may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or any value range between any two of them.

[0203] The mass content percentage of the lithium supplement agent added to 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.

[0204] In some embodiments, the negative electrode active material includes graphite.

[0205] In some embodiments, the graphite includes composite graphite particles. The composite graphite particles include a main body particle and a coating layer disposed at least partially on the surface of the main body particle. The main body particle includes artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

[0206] A secondary particle refers to a particle formed by aggregation of two or more primary particles.

[0207] The composite graphite particles including secondary particles and the surface coating layer including amorphous carbon are both beneficial to the infiltration of the electrolyte in the negative electrode active layer of the electrode sheet, and contribute to the improvement of the rate performance of the battery cell.

[0208] In some embodiments, the composite graphite material further includes kinetic carbon materials.

[0209] In some embodiments, the kinetic carbon material is located between the primary particles of the main body particle. At this time, the main body particles of the negative electrode active material include artificial graphite primary particles and kinetic carbon materials located between the primary particles.

[0210] In some embodiments, the kinetic carbon material is located in the coating layer. At this time, the coating layer includes both amorphous carbon and kinetic carbon materials.

[0211] In some embodiments, the raw material of the kinetic carbon material includes one or more of hard carbon, expanded graphite, and graphene.

[0212] In this article, the "raw material of the kinetic carbon material" and the "powder of the raw material of the kinetic carbon material" are completely the same in composition. The "kinetic carbon material" refers to the product obtained by graphitization treatment and / or carbonization treatment of the "raw material of the kinetic carbon material".

[0213] In some embodiments, the interlayer spacing d002 of the crystal plane of the kinetic carbon material raw material (002) is ≥ 0.3358 nm, and optionally 0.3359 nm to 0.3366 nm.

[0214] The interlayer spacing of the kinetic carbon material raw material is larger than that of conventional graphite (the interlayer spacing of conventional graphite is 0.335 nm). When the kinetic carbon material obtained therefrom is uniformly distributed in the main body particles and / or the coating layer of the composite graphite particles, it is beneficial to the rapid insertion and extraction of active ions, thereby improving the transport performance of active ions and electrons, and further improving the rapid charging performance of the battery cell.

[0215] In some embodiments, based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5%.

[0216] In some embodiments, based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles can be optionally 2%, 3%, 4%, 5% or the numerical range between any two of them.

[0217] When the content of amorphous carbon is within a suitable range, the composite graphite material can have a high specific capacity while also having a high solid-phase transport ability of active ions, which is beneficial to the improvement of the kinetic performance of the battery cell.

[0218] In some embodiments, the powder resistivity of the negative electrode material is less than or equal to 0.04 Ω•cm.

[0219] In some embodiments, the powder resistivity of the negative electrode material can be optionally 0.01 Ω•cm, 0.02 Ω•cm, 0.03 Ω•cm, 0.04 Ω•cm or the numerical range between any two of them.

[0220] The powder resistivity of the negative electrode material can be measured by any well-known method in the art. As an example, it can be measured with reference to the powder resistivity test method of the positive electrode active material described above. For example, it can be analyzed and tested using a powder resistivity tester (PRCD1100) with reference to standard GB / T30835-2014.

[0221] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20000 N is 1.5 g / cm 3 to 1.8 g / cm 3 , and can be optionally 1.55 g / cm 3 to 1.75 g / cm 3 .

[0222] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20,000 N can be selected as 1.5 g / cm 3 、1.55 g / cm 3 、1.6 g / cm 3 、1.65 g / cm 3 、1.7 g / cm 3 、1.75 g / cm 3 、1.8 g / cm 3 or a numerical range between any two of them.

[0223] The powder compaction density of the negative electrode material under a pressure of 20,000 N has a well-known meaning in the art and can be measured by instruments and methods known in the art. For example, it can be measured by referring to GB / T 24533-2009 through an electronic pressure testing machine (such as a UTM7305 type electronic pressure testing machine). An exemplary test method is as follows: Weigh 1 g of the negative electrode active material powder, add it to a mold with a bottom area of 1.327 cm 2 , apply a pressure of 20,000 N, keep the pressure for 30 s, then release the pressure, keep it for 10 s, and then record and calculate the powder compaction density of the material under a pressure of 20,000 N.

[0224] The negative electrode material with a powder compaction density within a suitable range can make the negative electrode active layer have a higher compaction density, and thus the battery cell has a higher energy density; at the same time, during the cycling process, the original pore structure of the negative electrode active layer can be maintained, which is beneficial to improving the retention of the high kinetic performance of the battery cell during the cycling process.

[0225] In some embodiments, the negative electrode active material further includes a silicon-based material, and the silicon-based material includes at least one of silicon, silicon oxide compounds, and silicon-carbon composites; based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material is 0.3% to 10%, and can be selected as 1% to 6%.

[0226] In some embodiments, based on the total mass of the negative electrode active material, the mass content of silicon element in the silicon-based material can be selected as 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a numerical range between any two of them.

[0227] The introduction of the silicon-based material is beneficial to improving the energy density of the battery cell. The silicon-based material within the above mass range can balance the energy density and cycle stability of the battery cell.

[0228] 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%.

[0229] In some embodiments, the mass content of the carbonate additive in the electrolyte may be selected from 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a numerical range between any two of them.

[0230] Silicon-based materials are prone to expansion during cycling, resulting in the rupture of the SEI film on the surface of the negative electrode material. Therefore, the consumption of additives relatively increases. The carbonate additives within the above range can improve the compactness and regeneration ability of the SEI film, taking into account the energy density and cycling stability of the battery cell.

[0231] In some embodiments, the negative electrode film layer includes a first negative electrode film layer disposed on the surface of the negative electrode current collector and a second negative electrode film layer disposed on the side of the first negative electrode film layer away from the negative electrode current collector. The second negative electrode film layer includes composite graphite particles; optionally, the negative electrode material in the first negative electrode film layer includes one or more of composite graphite particles and natural graphite.

[0232] The arrangement of the composite graphite particles close to the electrolyte side can take into account the energy density while improving the kinetic performance of the battery cell.

[0233] In some embodiments, the ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer is from 3:7 to 7:3.

[0234] 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 selected from 3:7, 4:7, 5:7, 6:7, 1:1, 2:1, 7:3, or a numerical range between any two of them.

[0235] In some embodiments, the volume average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 μm to 18.5 μm, and may be selected from 9.5 μm to 14.8 μm.

[0236] In some embodiments, the volume average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer may be selected from 9.5 μm, 9.8 μm, 10 μm, 10.8 μm, 11 μm, 11.8 μm, 12 μm, 12.8 μm, 13 μm, 13.8 μm, 14 μm, 14.8 μm, 15 μm, 15.8 μm, 16 μm, 16.8 μm, 17 μm, 17.8 μm, 18 μm, 18.5 μm, or a numerical range between any two of them.

[0237] In some embodiments, the volume average particle size Dv502 of the negative electrode active material in the second negative electrode active layer is 7.8 μm to 14.3 μm, and may be selected from 7.8 μm to 12.8 μm.

[0238] In some embodiments, the volume average particle diameter Dv502 of the negative electrode active material in the second negative electrode active material layer can be selected from 7.8 μm, 8 μm, 8.8 μm, 9 μm, 9.8 μm, 10 μm, 10.8 μm, 11 μm, 11.8 μm, 12 μm, 12.8 μm, 13 μm, 13.8 μm, 14 μm, 14.3 μm, or the numerical range between any two of them.

[0239] The volume average particle diameters Dv501 and Dv502 of the negative electrode active material in the first negative electrode active material layer and the second negative electrode active material layer can be tested with reference to the test method of the volume average particle diameter described above.

[0240] The second negative electrode active material layer disposed on the electrolyte side includes negative electrode active materials with smaller particle diameters, which can further improve the solid-liquid transport rate of ions in the battery electrode sheet and improve the kinetic performance of the battery monomer.

[0241] In some embodiments, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 10.8 μm, and the added mass content of the carbonate additive in the electrolyte is 3% to 8%.

[0242] In some embodiments, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer can be selected from 7.8 μm, 8 μm, 8.8 μm, 9 μm, 9.8 μm, 10 μm, 10.8 μm, or the numerical range between any two of them, and the added mass content of the carbonate additive in the electrolyte can be selected from 3%, 4%, 5%, 6%, 7%, 8%, or the numerical range between any two of them.

[0243] 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%.

[0244] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC can be selected from 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, or the numerical range between any two of them, and the added mass content of fluoroethylene carbonate FEC can be selected from 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or the numerical range between any two of them.

[0245] In some embodiments, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is 10.8 μm to 14.8 μm, and the added mass content of the carbonate additive in the electrolyte is 2% to 7%.

[0246] In some embodiments, the volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer can be selected from 10.8 μm, 11 μm, 11.8 μm, 12 μm, 12.8 μm, 13 μm, 13.8 μm, 14 μm, 14.8 μm or the numerical range between any two of them, and the added mass content of the carbonate additive in the electrolyte can be selected from 2%, 3%, 4%, 5%, 6%, 7% or the numerical range between any two of them.

[0247] A relatively small volume average particle diameter Dv502 of the negative electrode material in the second negative electrode film layer is beneficial to the solid-phase diffusion of lithium ions in the negative electrode active material. However, at the same time, it will increase the reaction activity between the negative electrode active material and the chain carboxylic ester solvent and increase the decomposition of the SEI film. By matching a relatively high content of the carbonate additive, the compactness and regeneration ability of the SEI film on the surface of the negative electrode material can be improved, and the cycle stability of the battery cell can be improved.

[0248] 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%.

[0249] In some embodiments, in the electrolyte, the added mass content of vinylene carbonate VC can be selected from 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or the numerical range between any two of them, and the added mass content of fluoroethylene carbonate FEC can be selected from 0.5%, 1%, 1.5%, 2%, 2.5% or the numerical range between any two of them.

[0250] In some embodiments, based on the total mass of the electrolyte, the mass content ratio of the chain carboxylic ester is 25.5% - 63.75%.

[0251] In some embodiments, based on the total mass of the solvents in the electrolyte, the mass content ratio of the chain carboxylic ester can be selected from 25.5%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 63.75% or the numerical range between any two of them.

[0252] In some embodiments, the chain carboxylic ester has a structural general formula of R1-COO-R2, wherein R1 and R2 each independently include at least one of an alkyl group having 1 to 5 carbon atoms and a halogenated alkyl group having 1 to 5 carbon atoms.

[0253] "C1-C5 alkyl" refers to an unbranched or branched alkyl group having 1-5 carbon atoms; including but not limited to one or more of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl.

[0254] "Halogenated C1-C5 alkyl" refers to an unbranched or branched alkyl group having 1-5 carbon atoms in which at least one hydrogen atom is replaced by a halogen, including but not limited to one or more of chloroalkyl, bromoalkyl, iodoalkyl.

[0255] In some embodiments, the chain carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, methyl formate.

[0256] The electrolyte with the mass content of the chain carboxylic acid ester within the above range has both good conductivity, wettability and chemical stability, which is beneficial to the comprehensive improvement of the kinetic performance, storage stability and cycle stability of the battery monomer.

[0257] 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%.

[0258] In some embodiments, the solvent further includes a carbonate solvent. Based on the total mass of the solvents in the electrolyte, the mass content of the carbonate solvent can be optionally 17%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 76.5% or the numerical range between any two of them.

[0259] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

[0260] In the electrolyte, the carbonate solvent and the lithium ions in the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of the lithium ions and anions in the lithium-containing electrolyte salt, thereby improving the kinetic performance of the battery monomer.

[0261] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of ethylene carbonate to the chain carboxylic acid ester is 0.27:1 - 1.33:1.

[0262] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the chain carboxylic acid ester can be 0.27:1, 0.30:1, 0.37:1, 0.40:1, 0.47:1, 0.50:1, 0.57:1, 0.60:1, 0.67:1, 0.70:1, 0.77:1, 0.80:1, 0.87:1, 0.90:1, 0.97:1, 1:1, 1.07:1, 1.17:1, 1.27:1, 1.33:1, or a numerical range between any two of them.

[0263] The chain carboxylic acid ester can improve the wettability between the electrolyte and the electrode sheet, and improve the solid-liquid transfer rate of lithium ions between the electrolyte and the electrode sheet. At the same time, the addition of the chain carboxylic acid ester is also beneficial to the improvement of the electrolyte conductivity; however, the chain carboxylic acid ester is prone to react with the SEI film, reducing the storage stability of the battery monomer. The lithium ions in the ethylene carbonate in the electrolyte and the lithium-containing electrolyte salt are prone to form a solvation structure to increase the dissociation rate of the lithium ions and anions in the lithium-containing electrolyte salt. However, with the increase in the content of ethylene carbonate, the viscosity of the electrolyte will also increase, having a negative impact on the conductivity of the electrolyte. The mass ratio of ethylene carbonate to the chain carboxylic acid ester within the above range enables the electrolyte to have appropriate viscosity, conductivity, good dissociation rate and wettability at the same time, which is beneficial to comprehensively improving the kinetic performance and high-temperature stability of the battery monomer.

[0264] 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.

[0265] In some embodiments, the mass ratio of the lithium salt to ethylene carbonate can be 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, or a numerical range between any two of them.

[0266] The ethylene carbonate in the electrolyte and the lithium ions in the lithium-containing electrolyte salt within the above range can increase the dissociation rate of lithium ions and improve the kinetic performance of the battery monomer.

[0267] In some embodiments, the conductivity of the electrolyte is 15 S / cm - 20 mS / cm.

[0268] The electrolyte with conductivity within the above range can better balance the kinetic performance and high-temperature stability of the battery monomer.

[0269] In some embodiments, the lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate LiPF6; optionally, the fluorosulfonylimide salt includes one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium bis(trifluoromethanesulfonyl)imide LiTFSI.

[0270] Fluorosulfonylimide salts are prone to dissociation in the electrolyte solvent, which is beneficial to improving the conductivity of the electrolyte. Moreover, fluorosulfonylimide salts have high chemical stability and are not easily decomposed during the recycling process. They can reduce the generation of hydrogen fluoride during battery cycling, decrease the probability of side reactions occurring at the negative electrode, and improve the cycle stability of the battery cell. However, as the temperature of the battery cell increases, the fluorosulfonylimide salt will undergo violent decomposition at a certain temperature threshold, releasing a large amount of heat and sharply increasing the risk of thermal runaway of the battery. This safety risk is more significant in fast-charging batteries. Although lithium hexafluorophosphate will gradually decompose to produce hydrofluoric acid during the secondary cycling process, the addition of lithium hexafluorophosphate will greatly reduce the risk of thermal runaway of the battery cell, keeping the risk within a controllable range and improving the safety of the battery.

[0271] In some embodiments, the lithium-containing electrolyte salt includes lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. The molar concentration of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte is 0.2 mol / L - 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is 0.5 mol / L to 1.0 mol / L.

[0272] In some embodiments, the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte can be selected as 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, or the numerical range between any two of them.

[0273] In some embodiments, the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte 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 the numerical range between any two of them.

[0274] In some embodiments, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is (2 - 5):10.

[0275] In some embodiments, the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte can be selected as 2:10, 3:10, 4:10, 5:10, or the numerical range between any two of them.

[0276] A battery cell in which the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte are within the above ranges can balance the kinetic performance and safety performance of the battery cell.

[0277] In some embodiments, the battery cell further includes a separator, the separator includes a porous base film and a functional layer disposed on at least one side of the porous base film, and the thickness of the porous base film is ≤ 12 μm, and can be selected to be less than or equal to 9 μm.

[0278] In some embodiments, the thickness of the porous base film can be selected to be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm or the numerical range between any two of them.

[0279] 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, and there is no particular limitation.

[0280] In some embodiments, the porosity of the porous base film in the separator is 20% - 70%, and can be selected to be 35% - 60%.

[0281] In some embodiments, the porosity of the porous base film in the separator can be selected to be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or the numerical range between any two of them.

[0282] In some embodiments, the functional layer includes a first functional layer disposed on the negative electrode side of the porous base film and a second functional layer disposed on the positive electrode side of the porous base film. The first functional layer includes first inorganic particles, the second functional layer includes composite particles, the composite particles include second inorganic particles and non-fluoropolymer particles, and the second inorganic particles in the composite particles adhere to the surface of the non-fluoropolymer particles and / or are dispersed inside the non-fluoropolymer particles.

[0283] 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.

[0284] The inorganic particles can improve the heat resistance of the first functional layer and the second functional layer and improve the kinetic performance of the battery cell.

[0285] In some embodiments, the non-fluoropolymer particles include acrylate copolymers.

[0286] In some embodiments, the liquid injection coefficient of the battery cell is 2.2 g / Ah - 3.1 g / Ah.

[0287] The liquid injection coefficient of a battery cell refers to the ratio of the mass of the electrolyte inside the battery cell to the battery capacity. The liquid injection coefficient of a battery cell can be obtained by testing in any well-known manner in the art. Exemplarily, the mass of the electrolyte in the battery cell can be obtained by the following method: Weigh the battery, and record the mass as M0. Disassemble the battery cell and pour out the free electrolyte. Take out the internal electrode assembly and separate the positive electrode plate, negative electrode plate, separator, and mechanical parts. Immerse and clean the positive electrode plate, negative electrode plate, separator, and mechanical parts with dimethyl carbonate (DMC) solvent for 24 h to 48 h, and soak repeatedly for more than 3 times. Place the aforementioned positive electrode plate, negative electrode plate, separator, and mechanical parts in an oven at 100 °C for more than 24 h until completely dried. Weigh the dried positive electrode plate, negative electrode plate, separator, and mechanical parts, and record the mass as M1. Thus, the mass of the electrolyte in the battery cell is (M0 - M1). The liquid injection coefficient is calculated by (M0 - M1) / the rated capacity of the battery cell. The rated capacity is the nominal capacity of the battery, or charge at a charging rate of 0.33C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C, let it stand for 10 min, and then discharge at a discharge rate of 0.33C to 2.0V, and use the discharge capacity of the battery cell as the rated capacity.

[0288] In some embodiments, the liquid injection coefficient of the battery cell can be selected as 2.2 g / Ah, 2.3 g / Ah, 2.4 g / Ah, 2.5 g / Ah, 2.6 g / Ah, 2.7 g / Ah, 2.8 g / Ah, 2.9 g / Ah, 3.0 g / Ah, 3.1 g / Ah, or any value range between any two of them.

[0289] In some embodiments, the fast charging time of the battery cell from 10% SOC to 80% SOC is 6 min to 15 min.

[0290] The fast charging time of the battery cell from 10% SOC to 80% SOC can be obtained by testing through any well-known method in the art. As an example, disassemble the battery cell, take out the positive electrode sheet, negative electrode sheet and free electrolyte, soak and clean them with dimethyl carbonate (DMC) solvent for more than 72 hours. After the electrolyte solvent, lithium salt and additive are completely leached out, dry the positive electrode sheet and negative electrode sheet in a vacuum oven. Then, use a copper wire as a reference electrode, add the free electrolyte in the battery cell, and assemble the positive electrode sheet and negative electrode sheet into a stacked three-electrode battery core. At 30 °C, charge the stacked three-electrode battery core at a constant current of 0.33C until the charging cut-off voltage of 3.65V, then charge at a constant voltage until the current is 0.05C, let it stand for 5 minutes, and then discharge at a constant current of 0.33C until the discharge cut-off voltage of 2.5V, and record its actual capacity as C0. Then, charge the battery cell at constant currents of 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, 4.5C0, 5C0, 5.5C0, 6C0 in sequence until the potential of the reference electrode drops to 0 mV, and record the maximum charging rate at this SOC. Taking 5% SOC as an increasing interval, test the maximum charging rate at every 5% SOC, such as 5% SOC, 10% SOC, 15% SOC to 100% SOC, and the maximum charging rates are correspondingly recorded as C5%SOC, C10%SOC, C15%SOC to C100%SOC. Calculate the continuous charging time from 10% to 80% SOC according to the maximum charging rates obtained by this test, which is the fast charging time.

[0291] In some embodiments, the fast charging time of the battery cell from 10% SOC to 80% SOC can be selected as 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min or the numerical range between any two of them.

[0292] The battery cell has good kinetic performance and can meet the demand for improving the energy replenishment efficiency of the electrical device.

[0293] In some embodiments, the battery cell may include an outer package. The outer package can be used to encapsulate the above electrode assembly and electrolyte.

[0294] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate and polybutylene succinate can be listed, etc.

[0295] This application has no particular limitation on the shape of the battery cell, and it can be cylindrical, square or any other arbitrary shape. For example,Figure 3 The battery cell 5 in the shape of a square is taken as an example.

[0296] In some embodiments, referring to Figure 4 , the outer packaging may include a housing 51 and a cover plate 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and those skilled in the art can select according to specific actual needs.

[0297] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells included in the battery module may be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.

[0298] Figure 5 The battery module 4 is taken as an example. Referring to Figure 5 , in the battery module 4, a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0299] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of battery cells 5 are received in the receiving space.

[0300] In some embodiments, the above battery module can be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.

[0301] Figure 6 and Figure 7 The battery pack 1 is taken as an example. Referring to Figure 6 and Figure 7 , the battery pack 1 may include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can be covered on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any way.

[0302] The second aspect of the present application provides a battery device, including the battery cell provided in the first aspect of the present application. The battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0303] In addition, the present application also provides an electrical device, and the electrical device includes the battery cell provided by the present application. The battery cell, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0304] In some embodiments, the fast charging time of the electrical device from 10% SOC to 80% SOC is 6 min to 15 min.

[0305] In some embodiments, the fast charging time of the electrical device from 10% SOC to 80% SOC can be selected as 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min or the numerical range between any two of them.

[0306] As the electrical device, the battery cell, battery module or battery pack can be selected according to its usage requirements.

[0307] Figure 8 Shown is an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the battery cell, a battery pack or a battery module can be adopted.

[0308] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thin and light design, and a battery cell can be used as the power source.

[0309] Embodiment

[0310] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in conjunction with embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restrictive of the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0311] In the examples where specific technologies or conditions are not specified, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product instructions. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0312] Example 1

[0313] Preparation of the positive electrode sheet:

[0314] The positive electrode sheet includes a positive current collector, a positive conductive layer on the positive current collector, and a positive electrode film layer. The positive current collector is an aluminum foil with a thickness of 10 μm.

[0315] The positive conductive layer on the positive current collector is a film layer formed by uniformly mixing a positive conductive agent, superconducting carbon, a positive binder, polyvinylidene fluoride (PVDF), and a solvent, N-methylpyrrolidone (NMP), and then coating and drying on the surface of the current collector. The thickness is 1 μm. The mass content of the positive conductive agent in the positive conductive layer is 40%, and the mass content of the positive binder is 60%.

[0316] The positive electrode film layer includes a film layer formed by uniformly coating a positive electrode paste (with a solvent of N-methylpyrrolidone, NMP) on the surface of the positive conductive layer, followed by drying and cold pressing. The positive electrode film layer includes a positive active material, a binder polyvinylidene fluoride (PVDF), and a conductive agent acetylene black with a weight ratio of 97:2:1.

[0317] The positive active material includes lithium iron phosphate with a coating layer. The coating layer covers the surface of the lithium iron phosphate. The coating layer includes lithium titanium iron phosphate, Li2FeTi(PO4)3, and amorphous carbon. The Dv50 of the positive active material is 1.6 μm, and the Dv10 is 0.64 μm.

[0318] The single-sided coating weight of the positive electrode film layer is 300 mg / 1540.25 mm 2 .

[0319] Preparation of the negative electrode sheet:

[0320] The negative electrode sheet includes a negative current collector, a negative conductive layer on the negative current collector, and a negative electrode film layer. The negative current collector is a copper foil with a thickness of 5 μm.

[0321] The negative conductive layer on the negative current collector is a film layer formed by uniformly mixing a negative conductive agent, superconducting carbon, a negative binder, styrene-butadiene rubber (SBR), a thickening agent, sodium carboxymethyl cellulose (CMC-Na), and a solvent, water, and then coating and drying on the surface of the negative current collector. The thickness is 1 μm. The mass content of the negative conductive agent in the negative conductive layer is 35%, the mass content of the negative binder in the negative conductive layer is 60%, and the mass content of the thickening agent in the negative conductive layer is 5%.

[0322] The negative electrode film layer is formed by uniformly coating the surface of the negative electrode conductive layer with a negative electrode slurry (the solvent is deionized water), followed by drying and cold pressing.

[0323] The single-sided coating weight of the negative electrode film layer is 138 mg / 1540.25 mm 2 。

[0324] The negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer. The first negative electrode film layer is located on the surface of the negative electrode conductive layer, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.

[0325] The first negative electrode film layer includes graphite particles, conductive agent acetylene black, a first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-2-hydroxyethyl acrylate copolymer, where the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose in a mass ratio of 96.5:0.5:0.5:1.5:1. The mass content of lithium element in the first lithium-containing binder is 4.8%. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer, and the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%.

[0326] The second negative electrode film layer includes graphite particles, conductive agent acetylene black, a second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-^{}2-hydroxyethyl acrylate copolymer, where the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and 2-hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickening agent sodium carboxymethyl cellulose in a mass ratio of 97.5:0.5:0.5:0.5:1. The mass content of lithium element in the second lithium-containing binder is 4.8%. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer, and the carbon coating layer is coated on the surface of the artificial graphite, and the mass content of the carbon coating layer is 3.5%. Preparation of electrolyte

[0327] In an argon atmosphere glove box with a water content < 10 ppm, ethylene carbonate EC, ethyl methyl carbonate EMC, and ethyl acetate EA are uniformly mixed in a mass ratio of 35:15:50 to obtain an electrolyte solvent. Lithium hexafluorophosphate (LiPF6) is slowly added as a lithium salt and stirred thoroughly until it is completely dissolved. After returning to room temperature, additives vinylene carbonate VC at 2% by mass percentage of the total mass of the electrolyte, fluoroethylene carbonate FEC at 2%, and lithium difluorophosphate LiPO2F2 at 1% are added in sequence. After thorough mixing, an electrolyte is obtained. Based on the total mass of the electrolyte, the mass ratio of the lithium salt is 15%, and the conductivity of the electrolyte is 15.4 mS / cm.

[0328] Preparation of Separator

[0329] Use a nano-aluminum oxide coating as the first functional layer on the negative electrode side, and a polyethylene (PE) film coated with a nano-aluminum oxide coating and polyacrylic acid on the other side as the separator. The porosity of the porous base film PE film is 35%, and the thickness of the PE film is 7 μm.

[0330] Preparation of Battery Cell

[0331] Stack and wind the positive electrode sheet, separator, and negative electrode sheet in sequence to obtain a wound electrode assembly. Add the electrode assembly into a square aluminum shell for outer packaging, inject the electrolyte after drying. After processes such as encapsulation, standing, formation, aging, secondary encapsulation, and capacity measurement, the battery cell is obtained. The liquid retention coefficient d3 / A of the battery cell is 2.9 g / Ah.

[0332] The preparation methods of Examples 2-4, 9-17 are basically the same as that of Example 1, except that the composition in the electrolyte is adjusted, as shown in Table 1 specifically.

[0333] The preparation methods of Examples 5-8 are basically the same as that of Example 1, except that the Dv50 of the negative electrode active material and / or the electrolyte components are adjusted.

[0334] The preparation methods of Examples 18-21 are basically the same as that of Example 1, except that the Dv50 of the positive electrode active material and / or the electrolyte components are adjusted.

[0335] The preparation method of Example 22 is basically the same as that of Example 1, except that the type of the positive electrode active material is adjusted. The ternary positive electrode active material in Example 22 is NCM811.

[0336] The preparation method of Comparative Example 1 is basically the same as that of Example 1, and no phosphorus-containing additive is added to the electrolyte.

[0337] Testing Method

[0338] Test the battery cells in the examples and comparative examples respectively. The test results are shown in Table 1.

[0339] (1) The method for high-temperature storage DCR test is as follows:

[0340] The test method for the battery DCR can refer to the method in GB / T 31467 "Performance Test Specification for High-Power Lithium-Ion Power Batteries for HEV" for testing. Specifically as follows:

[0341] At 25 °C, the lithium-ion battery is charged at a constant current of 0.33 C to 3.65 V, and then left standing for 1 min; then charged at a constant current of 0.1 C to 3.65 V and left standing for 30 min; discharged at a constant current of 0.33 C to 2.0 V, and the discharge capacity A0 at this time is recorded, with the unit of Ah. Then, it is charged at a constant current of 0.33 C for 0.5A0 Ah to adjust the SOC to 50%.

[0342] After the battery is placed at 25 °C for 2 h, it is discharged at a constant current of 2C for 10 s, and ∆U is recorded 放电 and ∆I 放电 . The discharge DCR data of the lithium-ion battery are calculated through the following formula

[0343] R 放电 = ∆U 放电 / ∆I 放电

[0344] where ∆U 放电 represents the voltage change within 10 s at the start of discharge, and ∆I 放电 represents the current value within 10 s at the start of discharge

[0345] 2. Battery high-temperature storage test method: First, the DCR value before high-temperature storage of the battery is tested as D0. Then, at 25 °C, the lithium-ion battery monomer is charged at a constant current of 0.33 C to 3.65 V and left standing for 1 min; then charged at a constant current of 0.1 C to 3.65 V, and the charge is adjusted to 100% SOC. Subsequently, the lithium-ion battery monomer is stored at 60 °C. The battery is taken out every 30 days and placed at 25 °C to measure the DCR value. This is repeated, and the DCR values after battery storage are recorded as D1, D2…Dn respectively. The calculation method for the increase in storage DCR is: (Dn - D0) / D0, where n is 1, 2, 3, 4……n

[0346] In this application, the DCR growth rate after storage at 60 °C for 90 days is used as the test result

[0347] (2)60 °C cycle number test

[0348] At 60 °C, the battery is charged at a charge rate of 1C of the nominal capacity to 3.65 V, then charged at a constant voltage of 3.65 V to 0.05 C, left standing for 10 min, and then discharged at a discharge rate of 1C to 2.5 V and left standing for 10 min. The above one charge and discharge is one cycle, and the test is stopped until the battery capacity decays to 80% of the initial discharge capacity, which is recorded as the cycle number @80% SOH

[0349] (3)Battery thermal runaway parameter test method

[0350] ①Charge regulation: At 25 °C, charge the lithium-ion battery at a constant current of 0.33 C until 3.65 V, and let it stand for 1 min; then charge it at a constant current of 0.1 C until 3.65 V to regulate the charge of the battery to 100% SOC state.

[0351] ②Overcharge to thermal runaway test: Fix the battery with a test fixture with a force of 3000 N, and then charge it at a constant current of 1 C until the battery core reaches thermal runaway. After the battery cools down to room temperature, observe the state of the thermally runaway battery core. If fire or explosion occurs, the thermal runaway boundary deteriorates. The test results are shown in Tables 1 - 3.

[0352] Table 1

[0353]

[0354]

[0355] Table 2

[0356]

[0357] Table 3

[0358]

[0359] Test results

[0360] Perform XPS test on the surface of the negative electrode film layer of the formed battery monomer. Characteristic peaks appear at 132 eV - 138 eV in the X-ray photoelectron spectroscopy (XPS) spectrum of the 2p electrons of phosphorus element in the negative electrode plate of the example; while no characteristic peaks appear in the X-ray photoelectron spectroscopy (XPS) spectrum of the 2p electrons of phosphorus element in Comparative Examples 1 and 2. Compared with the comparative examples, the battery monomer in the example has good high-temperature stability.

[0361] Except for Example 4, characteristic peaks also appear at 684.5 eV - 686 eV in the X-ray photoelectron spectroscopy (XPS) spectrum of the 1s electrons of fluorine element in the negative electrode plates of other examples.

[0362] The above tests show that the surface of the negative electrode film layer of the battery monomer in the example, which is far from the negative electrode current collector, includes an inorganic phosphorus-containing component with the general formula Li x PO y F z and / or an inorganic phosphorus-containing component with the general formula Li x0 PF z0 , where x is 1 - 3, y is 2 - 6, z is 0 - 6, x0 is 1 - 3, and z0 is 1 - 6.

[0363] As can be seen from the comparison of Examples 1, 9 - 11, when the added mass content of vinylene carbonate in the electrolyte is 2% to 6% and the added mass content of fluoroethylene carbonate is 0.5% to 2.5%, the battery cell can better balance good high - temperature storage performance and cycle stability.

[0364] It should be noted that the present disclosure is not limited to the above - mentioned embodiments. The above - mentioned embodiments are only examples, and embodiments having the same structure and the same effect as the technical idea within the scope of the technical solution of the present disclosure are included in the technical scope of the present disclosure. In addition, within the scope of not departing from the gist of the present disclosure, various modifications that can be thought of by those skilled in the art to the embodiments, and other ways constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present disclosure.

Claims

1. A battery cell, characterized in that, It includes a positive electrode plate, a negative electrode plate and an electrolyte; The electrolyte includes a solvent, the solvent includes a chain carboxylic acid ester solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; The negative electrode plate includes a negative current collector and a negative electrode film layer provided on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode material. The SEI film on the surface of the negative electrode material contains phosphorus element, and the X-ray photoelectron spectrum of the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy located at 132 eV to 138 eV.

2. The battery cell according to claim 1, wherein The phosphorus element 2p characteristic peak includes a first phosphorus-containing sub-peak with a binding energy of 133 eV to 134.5 eV and / or a second phosphorus-containing sub-peak with a binding energy of 136 eV to 137.5 eV.

3. The battery cell according to claim 1, wherein The X-ray photoelectron spectrum of the negative electrode material has a fluorine element 1s characteristic peak with a binding energy located at 684.5 eV to 686 eV.

4. The battery cell according to claim 1, characterized in that, On the surface of the negative electrode film layer away from the negative electrode current collector, there is an inorganic phosphorus-containing component with the general formula Li x PO y F z and / or with the general formula Li x0 PF z0 , where x is from 1 to 3, y is from 2 to 6, z is from 0 to 6, x0 is from 1 to 3, and z0 is from 1 to 6.

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

6. The battery cell according to claim 5, characterized in that, The phosphorus-containing additive includes one or more of lithium difluorobis(oxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl) phosphate, pentafluoro(phenoxy)cyclotriphosphazene, N-(triphenylphosphoranylidene)aniline, diethyl phenylphosphonate, triphenyl phosphite, methyl diphenyl phosphite, triethyl phosphite, N,N-diallyl-diethoxyphosphoramide.

7. The battery cell according to claim 5, characterized in that The phosphorus-containing additive includes one or more of lithium difluorobis(oxalato)phosphate, lithium difluorophosphate, pentafluoro(phenoxy)cyclotriphosphazene, N-(triphenylphosphoranylidene)aniline, diethyl phenylphosphonate, triphenyl phosphite.

8. The battery cell according to claim 5, characterized in that, The phosphorus-containing additive further includes fluorine element.

9. The battery cell according to claim 8, wherein, The phosphorus-containing additive includes one or more of lithium difluorobis(oxalato)phosphate, lithium difluorophosphate, pentafluoro(phenoxy)cyclotriphosphazene.

10. The battery cell according to claim 1, characterized in that, The electrolyte includes a phosphorus-containing additive; based on the total mass of the electrolyte, the mass content of the phosphorus-containing additive in the electrolyte of the battery cell is 0.1% to 3%.

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

12. The battery cell according to claim 11, characterized in that, The volume-based median particle size Dv50 of the negative electrode material 负 is 7.8 μm to 10.8 μm; the electrolyte includes a phosphorus-containing additive, and the mass content of the phosphorus-containing additive in the electrolyte is 0.3% to 1.8%.

13. The battery cell according to claim 11, characterized in that, The volume distribution particle size Dv50 of the negative electrode material 负 is 10.8 μm to 14.3 μm; the electrolyte includes a phosphorus-containing additive, and the mass content of the phosphorus-containing additive in the electrolyte is 0.1% to 1.3%.

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

15. The battery cell according to claim 14, wherein, The electrolyte includes vinylene carbonate and fluoroethylene carbonate.

16. The battery cell according to claim 14, wherein Based on the total mass of the electrolyte, the mass content of the carbonate additive is 2% to 10%.

17. The battery cell according to claim 14, wherein Based on the total mass of the electrolyte, the mass content of the carbonate additive is 3% to 8%.

18. The battery cell according to claim 14, wherein, Based on the total mass of the electrolyte, the mass content of vinylene carbonate in the electrolyte is 1.5% to 8%.

19. The battery cell according to claim 14, wherein, Based on the total mass of the electrolyte, the mass content of vinylene carbonate in the electrolyte is 2% to 6.5%.

20. The battery cell according to claim 14, 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%.

21. The battery cell according to claim 14, 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%.

22. The battery cell according to claim 1, wherein The positive electrode plate includes a positive current collector and a positive electrode film layer located on at least one surface of the positive current collector. The positive electrode film layer includes a positive 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.

23. The battery cell according to claim 22, wherein, The specific surface area of the positive electrode active material is 5.0 m 2 / g to 9.4 m 2 / g; and, the electrolyte includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 2% - 6%.

24. The battery cell according to claim 22, wherein The specific surface area of the positive electrode active material is 9.5 m 2 / g to 18 m 2 / g; and, the electrolyte includes a carbonate additive, and based on the total mass of the electrolyte, the mass content of the carbonate additive added in the electrolyte is 3% - 8%.

25. The battery cell according to claim 22, characterized in that, The positive electrode active material includes a lithium-containing phosphate with an olivine structure, and its composition general formula is shown in Formula I. Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I Wherein, 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, and 0.7 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, and 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

26. The battery cell according to claim 25, wherein The specific surface area of the lithium-containing phosphate with olivine structure is 5.0 m 2 / g to 18.0 m 2 / g.

27. The battery cell according to claim 22, wherein, The positive electrode active material includes a lithium-containing transition metal oxide, and its composition general formula is shown in Formula II. Li x2 A y2 Ni a2 Co b2 Mn c2 M2 (1-a2-b2-c2) Y z2 Formula II Wherein, 0 ≤ x2 ≤ 2.1, 0 ≤ y2 ≤ 2.1, and 0.9 ≤ x2 + y2 ≤ 2.1; 0 ≤ a2 ≤ 1, 0 ≤ b2 ≤ 1, 0 ≤ c2 ≤ 1, and 0.1 ≤ a2 + b2 + c2 ≤ 1; 1.8 ≤ z2 ≤ 3.5; A includes one or several of Na, K, and Mg; M includes one or several of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y includes one or several of O and F.

28. The battery cell according to claim 27, wherein The specific surface area of the lithium-containing transition metal oxide is 0.1 m 2 / g to 2 m 2 / g; and, the electrolyte 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%.

29. The battery cell according to claim 22, 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% - 2%.

30. The battery cell according to claim 29, wherein, The ion-conducting layer contains an ion conductor with a NASICON structure shown in Formula III. Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula Ⅲ In Formula III, M2 includes one or more of Ti, Zr, Hf, Ge, and Sn, 0 ≤ b3 ≤ 1, 3 ≤ x3 ≤ 5, and 2 ≤ y3 ≤ 4.

31. The battery cell according to claim 30, characterized in that, M2 is +4 valence.

32. The battery cell according to claim 22, wherein The positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes one or more of a ternary lithium supplement material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganate, lithium tartrate, and lithium citrate.

33. The battery cell according to claim 32, wherein, Based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.1% - 10%.

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

35. The battery cell according to claim 34, characterized in that, The graphite includes composite graphite particles, the composite graphite particles include body particles and a coating layer disposed on the surface of the body particles, the body particles include artificial graphite, the coating layer includes amorphous carbon, and the composite graphite particles include secondary particles.

36. The battery cell according to claim 35, wherein Based on the total mass of the composite graphite particles, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5%.

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

38. The battery cell according to claim 37, wherein, The powder compaction density of the negative electrode material under a pressure of 20,000 N is 1.55 g / cm 3 to 1.75 g / cm 3 .

39. The battery cell according to claim 1, characterized in that, The negative electrode material further includes a silicon-based material, the silicon-based material includes one or more of silicon oxides and silicon-carbon composites; 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%.

40. The battery cell according to claim 39, 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%.

41. 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%.

42. The battery cell according to claim 1, wherein, 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.

43. The battery cell according to claim 42, wherein The negative electrode material in the first negative electrode film layer includes one or more of composite graphite particles and natural graphite.

44. The battery cell according to claim 42, 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.

45. The battery cell according to claim 42, 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.

46. The battery cell according to claim 45, wherein, 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.

47. The battery cell according to claim 42, 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.

48. The battery cell according to claim 47, wherein The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 12.8 μm.

49. The battery cell according to claim 42, wherein 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 carbonate additives in the electrolyte is 3% - 8%.

50. The battery cell according to claim 49, wherein, In the electrolyte, the added mass content of vinylene carbonate is 3% to 7%, and the added mass content of fluorinated ethylene carbonate is 0.5% to 2%.

51. The battery cell according to claim 42, 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 carbonate additives in the electrolyte is 2% - 7%.

52. The battery cell according to claim 51, wherein, In the electrolyte, the added mass content of vinylene carbonate is 2% to 6%, and the added mass content of fluorinated ethylene carbonate is 0.5% to 2.5%.

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

54. The battery cell according to claim 1, wherein, The chain carboxylic ester has a structural general formula of R1-COO-R2, wherein R1 and R2 each independently include at least one of C1 - C5 alkyl groups and C1 - C5 haloalkyl groups.

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

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

57. The battery cell according to claim 56, wherein Based on the total mass of the electrolyte, the mass content ratio of the carbonate solvent is 21.25% - 59.5%.

58. The battery cell according to claim 56, characterized in that, The carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

59. The battery cell according to claim 56, wherein The carbonate solvent includes ethylene carbonate, and the mass ratio of ethylene carbonate to the chain carboxylic acid ester is 0.27:1 - 1.33:

1.

60. The battery cell according to claim 56, wherein, The electrolyte includes a lithium salt, and the carbonate solvent includes ethylene carbonate, wherein the mass ratio of the lithium salt to ethylene carbonate is 0.29 - 0.

72.

61. The battery cell according to claim 1, wherein, The conductivity of the electrolyte is 15 mS / cm - 20 mS / cm.

62. The battery cell according to claim 60, characterized in that, The lithium salt includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate.

63. The battery cell according to claim 62, characterized in that, The fluorosulfonylimide salts include one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide.

64. The battery cell according to claim 60, characterized in that, The lithium salt includes lithium bis(fluorosulfonyl)imide 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.

65. The battery cell according to claim 64, wherein, The ratio of the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte to the molar concentration of lithium hexafluorophosphate in the electrolyte is (2 - 5):

10.

66. The battery cell according to claim 1, characterized in that, The battery cell further includes a separator. The separator includes a porous base film and a functional layer provided on at least one side of the porous base film, and the thickness of the porous base film ≤ 12 μm.

67. The battery cell according to claim 66, characterized in that, The thickness of the porous base film is less than or equal to 9 μm.

68. The battery cell according to claim 66, wherein The porosity of the porous base film in the separator is 20% - 70%.

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

70. The battery cell according to claim 66, characterized in that, The functional layer includes a first functional layer provided on the negative electrode side of the porous base film and a second functional layer provided on the positive electrode side of the porous base film. The first functional layer includes first inorganic particles, and the second functional layer includes composite particles. The composite particles include second inorganic particles and non-fluoropolymer particles, and the second inorganic particles in the composite particles adhere to the surface of the non-fluoropolymer particles and / or are dispersed inside the non-fluoropolymer particles.

71. The battery cell according to claim 70, characterized in that, The non-fluoropolymer particles include acrylate copolymers.

72. The battery cell according to claim 1, wherein, The liquid injection coefficient of the battery cell is 2.2 g / Ah - 3.1 g / Ah.

73. The battery cell according to any one of claims 1 to 72, characterized in that, The fast charging time of the battery cell from 10% state of charge to 80% state of charge is 6 min - 15 min.

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

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

Images