Battery cell, battery device and electric device

Abstract

The present application provides a battery cell, a battery device and an electric device. The battery cell comprises a positive electrode sheet, a negative electrode sheet and an electrolyte solution. The electrolyte solution comprises a solvent, which comprises a chain carboxylate solvent; and the conductivity of the electrolyte solution is 13 mS / cm to 20 mS / cm. The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode material, and the X-ray photoelectron spectrum (XPS) of the negative electrode material has a phosphorus 2p characteristic peak at binding energy ranging from 132 eV to 138 eV.

Description

Battery cell, battery device, and electric device TECHNICAL FIELD

[0001] The present application relates to the technical field of battery cells, and in particular to a battery cell, a battery device, and an electric device. BACKGROUND

[0002] In recent years, battery cells are widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0003] With the dual improvement of the market's demand for the power efficiency of electric devices and the service life in special environments, higher requirements are also placed on the kinetic performance and high-temperature stability of battery cells. However, it is difficult to improve the above-mentioned performance at the same time in the prior art, which has become a technical problem that needs to be solved in the field.

[0004] SUMMARY

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

[0006] The first aspect of the present application provides a battery cell, comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte; the electrolyte comprises a solvent, the solvent comprises a chain carboxylate solvent, and the conductivity of the electrolyte is 13 mS / cm to 20 mS / cm; the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, and the negative electrode film layer comprises a negative electrode material, and the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy of 132 eV to 138 eV in X-ray photoelectron spectroscopy (XPS).

[0007] [Corrected according to Rule 91 on 30.10.2024] The electrolyte comprising a chain carboxylate solvent and having a conductivity of 13 mS / cm to 20 mS / cm is beneficial to improve the kinetic performance of the battery, but the chain carboxylate solvent often has high activity and continuously erodes 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 and continuous growth of the direct current resistance of the battery cell during storage. The SEI film contains phosphorus elements, which can improve the corrosion resistance and thermal stability of the SEI film at high temperatures, and take into account the kinetic performance and storage stability of the battery cell.

[0008] In any embodiment, the phosphorus element 2p characteristic peak comprises 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.

[0009] The phosphorus element 2p characteristic peak can be a single peak with one peak top or a multi-peak with multiple peak tops. Whether it is a single peak or a multi-peak, the XPSpeak software can be used to perform peak fitting processing on the characteristic peak of the P2p spectrum to obtain a sub-peak. The standard spectrum and 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 Li 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 Li x0 PF z0 , wherein 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 at high temperatures of the SEI film on the surface of the negative electrode material, and improve the kinetic performance and storage stability of the battery cell.

[0010] In any embodiment, the negative electrode material has a fluorine element 1s characteristic peak with a binding energy of 684.5 eV to 686 eV in the X-ray photoelectron spectroscopy (XPS).

[0011] The standard spectrum and 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 Li x PO y F z or Li x0 PF z0 . The above-mentioned fluorine-containing component in the SEI film can improve the corrosion resistance and thermal stability at high temperatures of the SEI film on the surface of the negative electrode material, and improve the kinetic performance and storage stability of the battery cell.

[0012] In any embodiment, the negative electrode film layer includes an inorganic phosphorus-containing component with a general formula of Li x PO y F z and / or a general formula of Li x0 PF z0 , wherein 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, on the surface of the negative electrode current collector.

[0013] In any embodiment, the electrolyte comprises a phosphorus-containing additive, which optionally comprises one or more of lithium difluorobis(oxalato)phosphate LiODFP, lithium difluorophosphate LiPO2F2, tris(trimethylsilyl)phosphate TMSP, triphenyl phosphine oxide TPPO, pentafluoro(phenoxy)cyclotriphosphazene PFPN, N-(triphenylphosphinyl)aniline TPPA, diethyl phenylphosphonate DEPP, triphenyl phosphite TPPi, methyl diphenyl phosphite MDP, triethyl phosphite TEP, N,N-diallyl-diethoxyphosphoramide DADEPA.

[0014] In any embodiment, the phosphorus-containing additive comprises one or more of lithium difluorobis(oxalato)phosphate LiODFP, lithium difluorophosphate LiPO2F2, pentafluoro(phenoxy)cyclotriphosphazene PFPN, N-(triphenylphosphinyl)aniline TPPA, diethyl phenylphosphonate DEPP, triphenyl phosphite TPPi.

[0015] The phosphorus-containing additive tends to have a high potential, and the phosphorus-containing additive added in the electrolyte is preferentially reacted in the formation or subsequent cycle process, evolves into a phosphorus-containing component in the SEI film, and improves the storage stability of the battery cell. It can be understood that in some embodiments, the phosphorus-containing additive added in the electrolyte is completely converted into a phosphorus-containing component in the SEI film in the formation process. In some embodiments, the phosphorus-containing additive remains in the electrolyte, and forms a reinforcing effect on the SEI film in the subsequent cycle process of the battery cell.

[0016] In any embodiment, the phosphorus-containing additive further comprises fluorine element, which optionally comprises one or more of lithium difluorobis(oxalato)phosphate LiODFP, lithium difluorophosphate LiPO2F2, pentafluoro(phenoxy)cyclotriphosphazene PFPN.

[0017] The above-mentioned phosphorus-containing additive simultaneously comprises phosphorus element and fluorine element, and is easily evolved into an inorganic phosphorus-containing component with a general formula of Li x PO y F z and / or an inorganic phosphorus-containing component with a general formula of Li x0 PF z0 in the SEI film in the formation and initial cycle process, effectively balancing the kinetic performance and high-temperature stability of the battery cell.

[0018] In any embodiment, the mass content of the phosphorus-containing additive in the electrolyte of the battery cell is 0.1% to 3% based on the total mass of the electrolyte.

[0019] 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 cycle process, and balances the kinetic performance and storage stability of the battery cell.

[0020] In any embodiment, the volume distribution particle size Dv50 of the negative electrode material is 7.8 μm-10.8 μm. 负 7.8 μm-10.8 μm.

[0021] Dv50 负 The negative electrode active material within the above range simultaneously includes a certain content of small particles and large particles, so that the battery cell can improve the lithium ion transmission rate and the kinetic performance by the small particles, and improve the compaction density of the battery cell pole piece and the energy density of the battery cell by the size particle grading, to achieve the balance of the kinetic performance and the energy density.

[0022] In any embodiment, the volume distribution particle size Dv50 of the negative electrode material is 7.8 μm-10.8 μm. 负 7.8 μm-10.8 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.3%-1.8%.

[0023] The volume distribution particle size Dv50 of the negative electrode active material is 7.8 μm-10.8 μm. 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 of the negative electrode active material is relatively large. 负 The negative electrode active material within the above range has a relatively large surface area and surface activity, and the reaction activity with the chain carboxylic acid ester solvent is relatively stronger, so a higher content of the phosphorus-containing additive is required in the electrolyte to achieve the balance of the kinetic performance and the storage stability.

[0024] In any embodiment, the volume distribution particle size Dv50 of the negative electrode active material is 10.8 μm-14.3 μm. 负 10.8 μm-14.3 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.1%-1.3%.

[0025] 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.

[0026] [Corrected according to Rule 91 on 30.10.2024] 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, and the carbonate additive can evolve into an organic component in the SEI film to improve the toughness of the SEI film. Together with the phosphorus-containing component in the SEI film, it improves the stability of the SEI film during the cycle process of the battery cell, and improves the cycle life of the battery cell.

[0027] In any embodiment, the electrolyte comprises vinylene carbonate VC and fluoroethylene carbonate FEC.

[0028] [Corrected according to Rule 91 on 30.10.2024] Chain carboxylate ester has high activity, which brings improvement of electrolyte wettability between electrolyte and electrode sheet, electrolyte conductivity, but also causes erosion to solid electrolyte membrane (SEI membrane). Vinylene carbonate VC has a reduction potential close to chain carboxylate ester, which can inhibit the reactivity of chain carboxylate ester, and improve the compactness of SEI membrane, and improve the cycle life of battery cell. The combination of vinylene carbonate VC and fluoroethylene carbonate FEC can balance the interface impedance of the battery and the high temperature stability of the SEI membrane. By adding phosphorus-containing additives, vinylene carbonate VC and fluoroethylene carbonate FEC in the electrolyte, the kinetic performance, storage stability and cycle life of the battery cell can be more effectively balanced.

[0029] In any embodiment, the mass content of the carbonate additive is 2% to 10%, optionally 3% to 8%, based on the total mass of the electrolyte.

[0030] The electrolyte with the mass content of the carbonate additive in the above range can not only improve the cycle stability of the SEI membrane, but also control the degree of side reaction, and comprehensively improve the cycle life of the battery cell.

[0031] In any embodiment, the mass content of vinylene carbonate VC in the electrolyte is 1.5% to 8%, optionally 2% to 6.5%, based on the total mass of the electrolyte.

[0032] In any embodiment, the mass content of fluoroethylene carbonate FEC in the electrolyte is 0.1% to 4%, optionally 0.5% to 3%, based on the total mass of the electrolyte.

[0033] By adding vinylene carbonate VC and fluoroethylene carbonate FEC in the electrolyte, the kinetic performance and cycle stability of the battery cell can be effectively balanced.

[0034] In any embodiment, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising one or more of lithium-containing phosphate with olivine structure, lithium-containing transition metal oxide.

[0035] 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 the mass content of the carbonate-based additive added in the electrolyte is 2%-6% based on the total mass of the electrolyte.

[0036] In any embodiment, the specific surface area of the positive electrode active material is 9.5 m 2 / g~18 m 2 / g, and the mass content of the carbonate-based additive added in the electrolyte is 3%-8% based on the total mass of the electrolyte.

[0037] 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 monomer. However, the positive electrode active material with a large specific surface area is more prone to absorbing water molecules in the air, and the water molecules are difficult to be discharged from the positive electrode film layer during the film drying process. During the battery monomer cycle, the reaction of water molecules with electrolyte salts in the electrolyte generates hydrofluoric acid, which corrodes the SEI film on the surface of the negative electrode material. The positive electrode active material with a high specific surface area generates a high content of hydrofluoric acid in the battery monomer, and a high content of carbonate-based additives can improve the compactness of the SEI film on the surface of the negative electrode material, and the kinetic performance and cycle stability of the battery monomer.

[0038] In any embodiment, the positive electrode active material comprises a lithium-containing phosphate with an olivine structure, the composition general formula is shown as formula I, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I,

[0039] 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 comprises one or more of Na, K, Mg; Me comprises one or more of Mn, Fe, Co, Ni; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X comprises one or more of S, Si, Cl, B, C, N; Y comprises one or more of O, F.

[0040] The lithium-containing phosphate with an olivine structure having the above components has good structural stability, low irreversible loss during fast charging, and improved cycle stability of the battery monomer.

[0041] In any embodiment, the lithium-containing phosphate of olivine structure has a specific surface area of 5.0 m 2 / g to 18.0 m 2 / g.

[0042] In any embodiment, the positive electrode active material comprises a lithium-containing transition metal oxide, the composition of which is represented by Formula II, Li x2 A y2 Ni a2 Co b2 Mn c2 M2(1-a2-b2-c2)Y z2 Formula II

[0043] 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 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; and Y comprises one or more of O, F.

[0044] In any embodiment, the lithium-containing transition metal oxide has a specific surface area of 0.1 m 2 / g to 2 m 2 / g, and the mass content of the carbonate additive in the electrolyte is 1% to 5% based on the total mass of the electrolyte.

[0045] In any embodiment, the positive electrode active material further comprises an ion-conducting layer disposed on the surface of the lithium-containing phosphate, the ion-conducting layer comprising carbon and iron, and the mass percentage of carbon is 1% to 2% based on the total mass of the positive electrode active material.

[0046] The ion-conducting layer described above can simultaneously improve the ion conductivity and the electronic conductivity of the positive electrode active material, improve the solid-phase transmission rate of ions and electrons, and improve the kinetic performance of the battery cell.

[0047] In any embodiment, the ion-conducting layer comprises a fast ion conductor with a NASICON structure, represented by Formula III, Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula III,

[0048] In the formula III, M2 includes one or more of Ti, Zr, Hf, Ge and Sn, and optionally, M2 is in +4 valence, 0≤b3≤1, 3≤x3≤5, and 2≤y3≤4.

[0049] The fast ion conductor with the NASICON structure has abundant three-dimensional lithium ion diffusion and transmission channels, and has the advantages of high ion conduction efficiency and strong structural stability during multiple lithium extraction and insertion. Coating the ion conductor containing the NASICON structure on the surface of the lithium-containing phosphate can significantly improve the transmission rate of lithium ions during multiple lithium extraction / insertion at the positive electrode end, improve the ion conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cell.

[0050] In any embodiment, the positive electrode film layer includes a lithium supplementing agent, and the lithium supplementing agent includes one or more of a ternary lithium supplementing material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganite, lithium tartrate, and trilithium citrate.

[0051] The addition of the lithium supplementing agent to the positive electrode active layer can offset the irreversible lithium loss during the electrochemical process, thereby improving the total capacity and energy density of the battery cell.

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

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

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

[0055] The composite graphite particles and the surface coating layer including amorphous carbon are both conducive to the infiltration of the electrolyte into the negative electrode active layer of the electrode sheet, and help to improve the rate capability of the battery cell.

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

[0057] The content of amorphous carbon within the appropriate range can enable the composite graphite material to have high gravimetric capacity while also having high active ion solid-phase transmission capacity, which is conducive to improving the kinetic performance of the battery cell.

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

[0059] In any embodiment, the powder compaction density of the negative electrode material under a pressure of 20000N is 1.5g / cm3 to 1.8g / cm3. 3 to 1.8g / cm3. 3 , optionally 1.55g / cm3. 3 to 1.75g / cm3. 3 .

[0060] The negative electrode material with the powder compaction density in the appropriate range can make the negative electrode active layer have a higher compaction density, and thus the battery monomer has a higher energy density; at the same time, the negative electrode active layer can maintain the original pore structure in the cycle process, which is beneficial to improve the maintenance of the high kinetic performance of the battery monomer in the cycle process.

[0061] In any embodiment, the negative electrode material further comprises a silicon-based material, the silicon-based material comprises one or more of silicon oxide compound and silicon-carbon composite; the mass content of silicon element in the silicon-based material is 0.3%-10%, optionally 1%-6%, based on the total mass of the negative electrode active material.

[0062] The introduction of the silicon-based material is beneficial to improve the energy density of the battery monomer. The silicon-based material in the above mass range can balance the energy density and cycle stability of the battery monomer.

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

[0064] The silicon-based material is prone to swelling in the cycle process, which causes the rupture of the SEI film on the surface of the negative electrode material, and thus the consumption of the additive is larger. The carbonate additive in the above range can improve the compactness and regeneration capacity of the SEI film, and balance the energy density and cycle stability of the battery monomer.

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

[0066] The composite graphite particles arranged close to the electrolyte side can improve the kinetic performance of the battery monomer while balancing the energy density.

[0067] 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.

[0068] In any embodiment, the volume average particle size Dv501 of the negative active material in the first negative active material layer is 9.5 μm to 18.5 μm, optionally 9.5 μm to 14.8 μm.

[0069] In any embodiment, the volume average particle size Dv502 of the negative active material in the second negative active material layer is 7.8 μm to 14.3 μm, optionally 7.8 μm to 12.8 μm.

[0070] The second negative active material layer disposed on the electrolyte side includes negative active material with a smaller particle size, which can further improve the solid-liquid transport rate of ions in the battery electrode sheet and improve the kinetic performance of the battery cell.

[0071] In any embodiment, the volume average particle size Dv502 of the negative active material in the second negative active material 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%.

[0072] In any embodiment, the added mass content of vinylene carbonate VC in the electrolyte is 3% to 7%, and the added mass content of fluoroethylene carbonate FEC in the electrolyte is 0.5% to 2%.

[0073] In any embodiment, the volume average particle size Dv502 of the negative active material in the second negative active material 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%.

[0074] The relatively small volume average particle size Dv502 of the negative active material in the second negative active material layer is conducive to the solid-phase diffusion of lithium ions in the negative active material, but at the same time, it increases the reactivity of the negative active material with the chain carboxylic acid ester solvent, increasing the decomposition of the SEI film. By matching a relatively high content of carbonate additives, the compactness and regenerative capacity of the SEI film on the surface of the negative active material can be improved, and the cycle stability of the battery cell can be improved.

[0075] In any embodiment, the added mass content of vinylene carbonate VC in the electrolyte is 2% to 6%, and the added mass content of fluoroethylene carbonate FEC in the electrolyte is 0.5% to 2.5%.

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

[0077] In any embodiment, the chain carboxylic acid ester has a general structure of R1-COO-R2, where R1 and R2 each independently includes at least one of a C1 to C5 alkyl group and a C1 to C5 halogenated alkyl group.

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

[0079] The electrolyte with the chain carboxylic acid ester in the above range has good conductivity, wettability, and chemical stability, which is conducive to the comprehensive improvement of the battery cell's kinetic performance, storage stability, and cycle stability.

[0080] In any embodiment, the solvent further comprises a carbonate solvent, and the mass content of the carbonate solvent accounts for 17%-76.5%, or 21.25%-59.5%, based on the total mass of the electrolyte.

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

[0082] The carbonate solvent in the electrolyte is prone to form a solvation structure with lithium ions in the lithium-containing electrolyte salt to increase the dissociation speed of lithium ions and anions in the lithium-containing electrolyte salt, thereby improving the kinetic performance of the battery cell.

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

[0084] The chain carboxylic acid ester can improve the wettability between the electrolyte and the pole piece, improve the solid-liquid transmission rate of lithium ions between the electrolyte and the pole piece, and also improve the conductivity of the electrolyte. However, the chain carboxylic acid ester is prone to react with the SEI film, which reduces the storage stability of the battery cell. The vinyl carbonate in the electrolyte is prone to form a solvation structure with lithium ions in the lithium-containing electrolyte salt to increase the dissociation speed of lithium ions and anions in the lithium-containing electrolyte salt, but the viscosity of the electrolyte also increases with the increase of the content of the vinyl carbonate, which has a negative impact on the conductivity of the electrolyte. The mass ratio of the vinyl carbonate to the chain carboxylic acid ester in the above range makes the electrolyte have appropriate viscosity, conductivity, and good dissociation rate and wettability, which is conducive to the comprehensive improvement of the kinetic performance and high-temperature stability of the battery cell.

[0085] In any embodiment, the electrolyte comprises a lithium salt and the carbonate solvent comprises vinyl carbonate, and the mass ratio of the lithium salt to the vinyl carbonate is 0.29-0.72.

[0086] The vinyl carbonate in the electrolyte and lithium ions in the lithium-containing electrolyte salt in the above range can increase the dissociation speed of lithium ions, thereby improving the kinetic performance of the battery cell.

[0087] In any embodiment, the electrolyte has an electrical conductivity of 13 mS / cm to 20 mS / cm, optionally 15 mS / cm to 20 mS / cm.

[0088] The electrolyte with the electrical conductivity in the above range can better balance the kinetic performance and high-temperature stability of the battery cell.

[0089] In any embodiment, the lithium salt comprises one or more of a fluorine-containing sulfimide salt and lithium hexafluorophosphate LiPF6; optionally, the fluorine-containing sulfimide salt comprises one or more of lithium bisfluorosulfimide LiFSI and lithium bis-trifluoromethanesulfonimide LiTFSI.

[0090] The fluorine-containing sulfimide salt is prone to dissociation in the electrolyte solvent, which is conducive to improving the electrical conductivity of the electrolyte, and the fluorine-containing sulfimide salt has high chemical stability and is not prone to decomposition during cyclic use, which can reduce the generation of hydrogen fluoride during battery cycling and reduce the probability of occurrence of negative electrode side reactions, thereby improving the cycle stability of the battery cell. However, as the temperature of the battery cell increases, the fluorine-containing sulfimide salt will decompose violently at a certain temperature threshold and release a large amount of heat, which will sharply increase the risk of thermal runaway of the battery, and this safety risk is more significant in fast-charging batteries. Although lithium hexafluorophosphate will gradually decompose to generate hydrofluoric acid during secondary cycling, the addition of lithium hexafluorophosphate can greatly reduce the risk of thermal runaway of the battery cell, so that the risk is reduced within a controllable range and the safety of the battery is improved.

[0091] In any embodiment, the lithium-containing electrolyte salt comprises lithium bisfluorosulfimide LiFSI and lithium hexafluorophosphate LiPF6, the molar concentration of lithium bisfluorosulfimide LiFSI in the electrolyte is 0.2 mol / L to 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.

[0092] In any embodiment, the ratio of the molar concentration of lithium bisfluorosulfimide in the electrolyte to the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte is (2-5):10.

[0093] The battery cell with the molar concentration of lithium bisfluorosulfimide in the electrolyte and the molar concentration of lithium hexafluorophosphate LiPF6 in the electrolyte in the above range can balance the kinetic performance and safety performance of the battery cell.

[0094] In any embodiment, the battery cell further comprises a separator film, the separator film comprises a porous base film and a functional layer arranged on at least one side of the porous base film, and the thickness of the porous base film is ≤12 μm, optionally ≤9 μm.

[0095] In any embodiment, the porosity of the porous base film in the separator film is 20% to 70%, optionally 35% to 60%.

[0096] 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 including second inorganic particles and a non-fluoropolymer, the second inorganic particles in the composite particles being attached to the surface of the non-fluoropolymer particles and / or dispersed in the interior of the non-fluoropolymer particles.

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

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

[0099] In any embodiment, the battery cell has a liquid injection coefficient of 2.2 g / Ah to 3.1 g / Ah.

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

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

[0102] The third aspect of the present application provides a power utilization device, including the battery cell provided by the first aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0103] FIG. 1 is a phosphorus element X-ray photoelectron spectrum of a negative electrode material according to an embodiment of the present application.

[0104] FIG. 2 is a fluorine element X-ray photoelectron spectrum of a negative electrode material according to an embodiment of the present application.

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

[0106] FIG. 4 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG. 3.

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

[0108] FIG. 6 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0109] FIG. 7 is an exploded view of the battery pack shown in FIG. 6.

[0110] FIG. 8 is a schematic view of a power consuming device using the battery cell as a power source according to an embodiment of the present application.

[0111] BRIEF DESCRIPTION OF DRAWINGS 1: battery pack; 2: upper case; 3: lower case; 4: battery module; 5: battery cell; 51: case; 52: electrode assembly; 53: top cover assembly. DETAILED DESCRIPTION

[0112] Hereinafter, embodiments of the battery cell and the power consuming device according to the present application will be specifically described with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known well and repeated description of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0113] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., 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 particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is 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, a numerical range "a-b" represents a shorthand manner of describing each and every numerical value that is contained in the range between "a" and "b," wherein "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand manner of describing these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

[0114] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0115] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0116] If not specified, all steps of the present application can be performed in sequence or randomly, preferably in sequence. For example, the method comprises steps (a) and (b), indicating that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), indicating that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0117] If not specified, the present application refers to "including" and "containing" as open or closed. For example, "including" and "containing" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0118] If not 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 one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0119] In order to improve the kinetic performance of the battery monomer, a solvent with high conductivity, such as a chain carboxylate solvent, is often added to the electrolyte to achieve fast ion transmission and reduce the possibility of lithium precipitation. However, high-conductivity solvents tend to have high activity, which will continuously erode the solid electrolyte membrane (SEI film) on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI film during storage of the battery monomer, growth of the direct current resistance of the battery monomer, and decline in the use stability of the battery monomer.

[0120] Based on this, the present application provides a battery monomer, comprising a positive electrode sheet, a negative electrode sheet and an electrolyte; the electrolyte comprises a solvent, the solvent comprises a chain carboxylate solvent, and the electrolyte has an electrical conductivity greater than or equal to 13 mS / cm; the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, and the negative electrode film layer comprises a negative electrode material, wherein the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy of 132 eV-138 eV in X-ray photoelectron spectroscopy (XPS).

[0121] In the present application, the X-ray photoelectron spectroscopy (XPS) of the negative electrode material can be tested by any method known in the art. As an example, after the battery cell is disassembled, the negative electrode sheet is cleaned with a solvent such as dimethyl carbonate (DMC) for more than three times, and then the powder is scraped and sampled. The obtained negative electrode material sample powder is adhered to a conductive substrate, and an X-ray photoelectron spectrometer (such as AXIS ULTRA) is used to perform X-ray photoelectron spectroscopy test. The scanning rate and time of the X-ray source are adjusted so that it focuses and detects elements and functional groups within 5-10 nm depth from the surface of the negative electrode material. The X-ray photoelectron spectroscopy (XPS) spectrum of the sample is obtained, and the characteristic peaks of the elements in the spectrum are analyzed. The chain carboxylate solvent refers to an organic molecule in a chain form containing a carboxylate group. As an example, it includes but is not limited to butyl acetate, ethyl propionate, ethyl acetate, methyl acetate, methyl formate, etc.

[0122] The type and mass of the solvent in the electrolyte can be obtained by testing the electrolyte by methods known to those skilled in the art. For example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. As an example, the battery cell is disassembled to obtain free electrolyte from the battery cell. The free electrolyte in the battery cell is diluted to 3-10 times with acetonitrile to obtain an electrolyte diluent to be tested. The electrolyte diluent is placed in a GC-MS 3100 organic component gas chromatograph for full scan qualitative analysis. The injection port temperature is 250°C, and the scanning range is 35 μm-270 μm. The total ion current chromatogram of each organic matter is obtained after the test is completed. The corresponding organic matter type is compared according to the peak position of the chromatogram, and the content percentage of each organic matter is calculated according to the peak area.

[0123] The conductivity of the electrolyte is the ability of the dissociated positive and negative ions in the electrolyte solution to move directionally in an electric field to form a conductive process. It can be tested by any method known in the art. As an example, about 100 mL of electrolyte sample is taken with a dry and clean corrosion-resistant sample bottle, sealed in a constant temperature water bath, and shaken from time to time. The temperature is constant at 25°C (deviation ±5°C). After the temperature of the sample is constant, the conductivity of the electrolyte is tested by using a commercially available conductivity meter. After the conductivity meter is clearly wiped dry with a calibration liquid, it is vertically placed in the liquid to be tested, and the start test is clicked. The test result is recorded after the data is stable for more than 10 seconds. In some embodiments, the conductivity of the electrolyte can be selected as 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, 20 mS / cm, 21 mS / cm, 22 mS / cm, 23 mS / cm, 24 mS / cm, 25 mS / cm, or any numerical range between any two of them.

[0124] The electrolyte including a chain carboxylate solvent and having a conductivity of 13 mS / cm-20 mS / cm is beneficial to improve the kinetic performance of the battery monomer, but the chain carboxylate solvent often has high activity, which continuously erodes the solid electrolyte membrane (SEI membrane) on the surface of the negative electrode material during storage, resulting in continuous loss and regeneration of the SEI membrane and continuous increase of the direct current resistance of the battery monomer during storage. The SEI membrane on the surface of the negative electrode material of the battery monomer of the application contains phosphorus elements, which can improve the corrosion resistance and thermal stability of the SEI membrane at high temperature, and balance the kinetic performance and storage stability of the battery monomer.

[0125] In some embodiments, the phosphorus element 2p characteristic peak 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.

[0126] The phosphorus element 2p characteristic peak can be a single peak with one peak top or a multi-peak with multiple peak tops. Whether it is a single peak or a multi-peak, sub-peaks can be obtained by peak fitting processing of the P2p energy spectrum using XPSpeak software. 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 Li x PO y F z The second sub-peak with a binding energy of 136 eV-137.5 eV corresponds to the phosphorus element in Li x0 PF z0 , wherein x is 1-3, y is 2-6, z is 0-6, x0 is 1-3, and z0 is 1-6. The phosphorus-containing component in the above SEI membrane can improve the corrosion resistance and thermal stability of the SEI membrane on the surface of the negative electrode material at high temperature, and improve the kinetic performance and storage stability of the battery monomer.

[0127] In some embodiments, the negative electrode material has a fluorine element 1s characteristic peak with a binding energy of 684.5 eV-686 eV in the X-ray photoelectron spectroscopy (XPS).

[0128] In some embodiments, the negative electrode material has a fluorine element 1s characteristic peak with a binding energy of 684.5 eV-686 eV in the X-ray photoelectron spectroscopy (XPS) at a depth of 5-10 nm from the surface. The fluorine element 1s characteristic peak with a binding energy of 684.5 eV-686 eV in the X-ray photoelectron spectroscopy (XPS) of the negative electrode material indicates that the SEI membrane on the surface of the negative electrode material includes fluorine elements. The above fluorine-containing component in the SEI membrane can improve the corrosion resistance and thermal stability of the SEI membrane on the surface of the negative electrode material at high temperature, and improve the kinetic performance and storage stability of the battery monomer.

[0129] In some embodiments, the negative electrode film layer comprises an inorganic phosphorus-containing component of the general formula Li x PO y F z and / or an inorganic phosphorus-containing component of the general formula Li x0 PF z0 wherein x is 1-3, y is 2-6, and z is 0-6, x0 is 1-3, and z0 is 1-6. XPS full spectrum testing of the negative electrode material shows that the cations in the depth of 5-10 nm from the surface of the negative electrode material are mainly lithium ions, and thus it can be inferred that the negative electrode material comprises an inorganic phosphorus-containing component of the general formula Li x PO y F z and / or an inorganic phosphorus-containing component of the general formula Li x0 PF z0 in the depth of 5-10 nm from the surface of the negative electrode material.

[0130] In some embodiments, x can be selected as 1, 2, 3, or any numerical range between any two of them, y can be selected as 2, 3, 4, 5, 6, or any numerical range between any two of them, z can be selected as 0, 1, 2, 3, 4, 5, 6, or any numerical range between any two of them, x0 can be selected as 1, 2, 3, or any numerical range between any two of them, and z0 can be selected as 1, 2, 3, 4, 5, 6, or any numerical range between any two of them.

[0131] In some embodiments, the electrolyte comprises a phosphorus-containing additive, which can optionally comprise one or more of lithium difluorobis(oxalato)phosphate LiODFP, lithium difluorophosphate LiPO2F2, tris(trimethylsilyl)phosphate TMSP, triphenyl phosphine 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-diethoxyphosphoramide DADEPA.

[0132] In some embodiments, the phosphorus-containing additive comprises one or more of lithium difluorobis(oxalato)phosphate LiODFP, lithium difluorophosphate LiPO2F2, pentafluoro(phenoxy)cyclotriphosphazene PFPN, N-(triphenylphosphoranylidene)aniline TPPA, diethyl phenylphosphonate DEPP, and triphenyl phosphite TPPi.

[0133] An additive refers to a component with a low content in the electrolyte, generally accounting for no more than 10% by mass in the electrolyte, and has the characteristics of strong pertinence and small dosage, and can significantly optimize the performance of a certain aspect of the battery without changing the production process.

[0134] The components of the additive can be tested in any manner known in the art, for example, the composition of the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Illustratively, the inorganic content of the electrolyte can be tested using an ion chromatograph (IC), a quantitative electrolyte is weighed (the dilution concentration is in the middle of the standard curve), and is diluted to 100 mL with ultrapure water, and is automatically injected for detection by ion chromatography, and the inorganic ion chromatogram is tested, and the corresponding inorganic species is compared according to the peak position of the chromatogram. The above free electrolyte is diluted 3-10 times with acetonitrile to obtain an electrolyte diluent to be tested, and the electrolyte diluent is placed in a GC-MS 3100 organic component gas chromatograph for full scan qualitative analysis, the injection port temperature is 250°C, the scanning range is 35 μm-270 μm, and the total ion current chromatogram of each organic compound is obtained after the test is completed, and the corresponding organic species is compared according to the peak position of the chromatogram.

[0135] The phosphorus-containing additive often has a high potential, and the phosphorus-containing additive added in the electrolyte will preferentially react during formation or subsequent cycling, evolving into a phosphorus-containing component in the SEI film, thereby improving the storage stability of the battery cell. It can be understood that, in some embodiments, the phosphorus-containing additive added in the electrolyte is completely converted into a phosphorus-containing component in the SEI film during formation. In some embodiments, the phosphorus-containing additive remains in the electrolyte, and forms a reinforcing effect on the SEI film during subsequent cycling of the battery cell.

[0136] In some embodiments, the phosphorus-containing additive further comprises fluorine elements, and optionally, the phosphorus-containing additive comprises one or more of lithium difluorobisoxalate phosphate LiODFP, lithium difluorophosphate LiPO2F2, and pentafluoro(phenoxy)cyclotriphosphazene PFPN.

[0137] The above phosphorus-containing additive simultaneously comprises phosphorus elements and fluorine elements, and is easily evolved into an inorganic phosphorus-containing component of the general formula Li x PO y F z and / or an inorganic phosphorus-containing component of the general formula Li x0 PF z0 during formation and initial cycling, effectively balancing the kinetic performance and high-temperature stability of the battery cell.

[0138] In some embodiments, the mass content of the phosphorus-containing additive in the electrolyte of the battery cell is 0.1%-3% based on the total mass of the electrolyte.

[0139] In some embodiments, the mass content of the phosphorus-containing additive can be selected from 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 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 any numerical range between any two of the above values, based on the total mass of the electrolyte.

[0140] The type and mass of the phosphorus-containing additive in the electrolyte can be obtained by detecting the electrolyte by methods known to those skilled in the art. For example, the composition in the electrolyte can be measured by liquid chromatography, ultraviolet spectrophotometry, ultraviolet-visible spectrophotometry, etc. Illustratively, the inorganic content in the electrolyte is tested using an ion chromatograph (IC), a quantitative electrolyte is weighed (the diluent concentration is in the middle of the standard curve), and is diluted to 100 mL with ultrapure water, and is automatically injected for detection by ion chromatography. The inorganic ion chromatogram is tested, the corresponding inorganic species is compared according to the peak position of the chromatogram, and the percentage of the corresponding inorganic ion content is calculated according to the peak area. The above free electrolyte is diluted to 3-10 times using acetonitrile to obtain an electrolyte diluent to be tested, and the electrolyte diluent is placed in a GC-MS 3100 organic component gas chromatograph for full scan qualitative analysis. The injection port temperature is 250°C, the scanning range is 35 μm-270 μm, and the total ion flow chromatogram of each organic matter is obtained after the test is completed. The corresponding organic species is compared according to the peak position of the chromatogram, and the percentage of the corresponding content of each organic matter is calculated according to the peak area. The mass of the phosphorus-containing additive obtained by calculation is divided by the mass of the electrolyte sample to obtain 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.

[0141] The electrolyte with the mass content of the phosphorus-containing additive in the electrolyte of the battery cell in the above range is beneficial to reinforcing the SEI film during the cycle process, and balances the kinetic performance and storage stability of the battery cell.

[0142] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 7.8 μm-14.3 μm. 负 for example, 7.8 μm-14.3 μm.

[0143] The volume distribution particle size Dv50 of the negative electrode material is 7.8 μm-14.3 μm. 负For the meaning well known in the art, it represents the particle size corresponding to the cumulative volume distribution percentage of 50%, which can be determined by using the instruments and methods known in the art. For example, it can be conveniently determined by using a laser particle size analyzer according to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method. The testing instrument can be a Mastersizer 3000 laser particle size analyzer of Malvern Instruments Ltd., UK.

[0144] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 7.8 μm to 10.8 μm. 负 may be 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9.0 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, 10.7 μm, 10.8 μm, 11.8 μm, 12.8 μm, 13.8 μm, 14.3 μm, or any numerical range between any two of them.

[0145] Dv50 负 The negative electrode active material within the above range contains both small particles and large particles, so that the battery cell can improve the lithium ion transmission rate and the kinetic performance by the small particles, and improve the compaction density of the battery cell electrode sheet and the energy density of the battery cell by the size grading of the particles, so as to achieve the balance of kinetic performance and energy density.

[0146] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 7.8 μm to 10.8 μm. 负 7.8 μm to 10.8 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.3% to 1.8%.

[0147] In some embodiments, the volume distribution particle size Dv50 of the negative electrode material is 7.8 μm to 10.8 μm. 负Optionally, the volume distribution particle size Dv50 of the negative electrode active material is 7.8 μm, 7.9 μm, 8 μm, 8.1 μm, 8.2 μm, 8.3 μm, 8.4 μm, 8.5 μm, 8.6 μm, 8.7 μm, 8.8 μm, 8.9 μm, 9 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm, 9.9 μm, 10 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, 10.7 μm, 10.8 μm, or any numerical range between any two of the above values, and the mass content of the phosphorus-containing additive in the electrolyte is 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 any numerical range between any two of the above values.

[0148] 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 monomer. However, the volume distribution particle size Dv50 of the negative electrode active material is relatively large 负 The negative electrode active material within the above range has a relatively large surface area and surface activity, and a relatively strong reactivity with the chain carboxylic acid ester solvent. Therefore, a higher content of the phosphorus-containing additive is required in the electrolyte to achieve a balance between the kinetic performance and the storage stability.

[0149] In some embodiments, the volume distribution particle size Dv50 of the negative electrode active material 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%. 负

[0150] The volume distribution particle size Dv50 of the negative electrode active material 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%. 负 Optionally, the volume distribution particle size Dv50 of the negative electrode active material is 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 numerical range between any two of the above values, and the mass content of the phosphorus-containing additive in the electrolyte is 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 numerical range between any two of the above values.

[0151] In some embodiments, the electrolyte further comprises a carbonate additive, and the carbonate additive comprises one or more of vinylene carbonate VC and fluoroethylene carbonate FEC.

[0152] ​In the present application, carbonate-based additives refer to compounds comprising a carbonate group (-O-CO-O-) and derivatives thereof, as well as mixtures containing the above-mentioned compounds and derivatives thereof.

[0153] The phosphorus-containing component on the surface of the negative material can increase the high-temperature stability of the SEI film while also increasing the brittleness of the SEI film. The carbonate-based additive can evolve into an organic component in the SEI film, thereby improving the toughness of the SEI film. The phosphorus-containing component and the carbonate-based additive in the SEI film can jointly improve the stability of the SEI film during the cycling process of the battery cell, thereby improving the cycle life of the battery cell.

[0154] In some embodiments, the electrolyte comprises vinylene carbonate VC and fluoroethylene carbonate FEC.

[0155] The chain carboxylate has high activity, which can improve the wettability between the electrolyte and the electrode sheet and the conductivity of the electrolyte, but also can erode the solid electrolyte film (SEI film). Vinylene carbonate VC has a reduction potential close to that of the chain carboxylate, which can inhibit the reactivity of the chain carboxylate and improve the compactness of the SEI film, thereby improving 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. The combination of the phosphorus-containing additive, vinylene carbonate VC and fluoroethylene carbonate FEC in the electrolyte can more effectively balance the kinetic performance, storage stability and cycle life of the battery cell.

[0156] In some embodiments, the mass content of the carbonate-based additive is 2% to 10%, and optionally 3% to 8%, based on the total mass of the electrolyte.

[0157] In some embodiments, the mass content of the carbonate-based additive is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any numerical range between any two of the above values, based on the total mass of the electrolyte.

[0158] The electrolyte with the mass content of the carbonate-based additive in the above range can improve the cycle stability of the SEI film and control the degree of side reactions, thereby comprehensively improving the cycle life of the battery cell.

[0159] In some embodiments, the mass content of vinylene carbonate VC in the electrolyte is 1.5% to 8%, and optionally 2% to 6.5%, based on the total mass of the electrolyte.

[0160] In some embodiments, the mass content of vinylene carbonate VC in the electrolyte can be selected from 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, or any numerical range between any two of them, based on the total mass of the electrolyte.

[0161] In some embodiments, the mass content of fluoroethylene carbonate FEC in the electrolyte can be 0.1% to 4%, or selected from 0.5% to 3%, based on the total mass of the electrolyte.

[0162] In some embodiments, the mass content of fluoroethylene carbonate FEC in the electrolyte can be selected from 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or any numerical range between any two of them, based on the total mass of the electrolyte.

[0163] The addition of vinylene carbonate VC and fluoroethylene carbonate FEC in the electrolyte can effectively balance the kinetic performance and cycle stability of the battery cell.

[0164] In some embodiments, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising one or more of lithium-containing olivine-type phosphates, lithium-containing transition metal oxides.

[0165] In some embodiments, the specific surface area of the positive electrode active material is 5.0m 2 / g to 9.4m 2 / g, and the mass content of the carbonate additive in the electrolyte is 2% to 6%, based on the total mass of the electrolyte.

[0166] In this application, the specific surface area of the positive electrode active material is the meaning known in the art, which can be measured by instruments and methods known in the art. For example, it can be tested by the nitrogen adsorption specific surface area analysis test method according to GB / T 19587-2017, and calculated by the BET (Brunauer Emmett Teller) method. The testing instrument can be a Tri-Star 3020 type specific surface area and pore size analyzer of the United States Micromeritics company.

[0167] In some embodiments, the specific surface area S of the positive electrode active material can be selected from 5m 2 / g, 5.4m 2 / g, 6m 2 / g, 6.4 m 2 / g, 7 m 2 / g, 7.4 m 2 / g, 8 m 2 / g, 8.4 m 2 / g, 9 m 2 / g, 9.4 m 2 / g, or any numerical range formed by any two of the aforementioned values, and the mass content of the carbonate additive added in the electrolyte can be 2%, 3%, 4%, 5%, 6%, or any numerical range formed by any two of the aforementioned values, based on the total mass of the electrolyte.

[0168] In some embodiments, the specific surface area of the positive electrode active material can be 9.5 m 2 / g to 18 m 2 / g, and the mass content of the carbonate additive added in the electrolyte is 3% to 8%, based on the total mass of the electrolyte.

[0169] In some embodiments, the specific surface area of the positive electrode active material can be 9.5 m 2 / g, 10 m 2 / g, 10.5 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 any numerical range formed by any two of the aforementioned values, and the mass content of the carbonate additive added in the electrolyte can be 3%, 4%, 5%, 6%, 7%, 8%, or any numerical range formed by any two of the aforementioned values, based on the total mass of the electrolyte.

[0170] The positive electrode active material with large specific surface area has large contact area with electrolyte, which can improve the kinetic performance of the battery cell. However, the positive electrode active material with large specific surface area is more likely to absorb water molecules in the air, and the water molecules are difficult to be discharged from the positive electrode film layer during the film baking process. During the battery cell cycle, 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 positive electrode active material with high specific surface area generates high content of hydrofluoric acid in the battery cell, and the high content of carbonate additives can improve the compactness of the SEI film on the surface of the negative electrode material, and the kinetic performance and cycle stability of the battery cell.

[0171] In some embodiments, the positive electrode active material comprises a lithium-containing phosphate with olivine structure, the composition general formula is shown as formula I, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula I,

[0172] 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 comprises one or more of Na, K, Mg; Me comprises one or more of Mn, Fe, Co, Ni; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X comprises one or more of S, Si, Cl, B, C, N; Y comprises one or more of O, F.

[0173] 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 any 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 any 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 any 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 any numerical range between any two of them, b1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, or any 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 any numerical range between any two of them, c1 can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, or any numerical range between any two of them, and 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 any numerical range between any two of them.

[0174] The lithium-containing phosphate with olivine structure having the above components has good structural stability and low irreversible loss in fast charging, thereby improving the cycle stability of the battery cell.

[0175] In some embodiments, the specific surface area of the lithium-containing phosphate with olivine structure can be selected from 5.0 m2 / g to 18.0 m2 / g. 2 2 / g.

[0176] In some embodiments, the specific surface area of the lithium-containing phosphate with olivine structure can be selected from 5.0 m2 / g, 6.0 m2 / g, 7.0 m2 / g, 8.0 m2 / g, 9.0 m2 / g, 10.0 m2 / g, 11.0 m2 / g, 12.0 m2 / g, 13.0 m2 / g, 14.0 m2 / g, 15.0 m2 / g, 16.0 m2 / g, 17.0 m2 / g, 18.0 m2 / g, or any numerical range between any two of them. 2 2 2 2 2 2 2 2 2 2 2 2 2 2

[0177] ​​​​​​​​​​​​​​​In some embodiments, the positive electrode active material comprises a lithium-containing transition metal oxide with the general formula shown in Formula II, Li x2 A y2 Ni a2 Co b2 Mn c2 M2(1-a2-b2-c2)Y z2 Formula II

[0178] Wherein, 0≤x²≤2.1, 0≤y²≤2.1, and 0.9≤x²+y²≤2.1; 0≤a²≤1, 0≤b²≤1, 0≤c²≤1, and 0.1≤a²+b²+c²≤1; 1.8≤z²≤3.5; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y includes one or more of O and F.

[0179] In some implementations, x2 can be selected as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, or any value between two of these. y2 can be selected as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, The values ​​are 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, or any range between two of these values, and x² + y² can be selected from 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, or any range between two of these values; a² can be selected from 0, 0.1, 0.2, 0.3. The values ​​b2 and c2 can be 0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any two of these values. The range of values ​​is defined as follows: a² + b² + c² can be selected from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any two of these values; z² can be selected from 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, or any two of these values.

[0180] In some embodiments, the specific surface area of ​​the lithium-containing transition metal oxide is 0.1 m². 2 / g~2m 2 / g, and based on the total mass of the electrolyte, the mass content of the carbonate additive in the electrolyte is 1%-5%.

[0181] In some embodiments, the specific surface area of ​​the lithium-containing transition metal oxide may be selected as 0.1 m². 2 / g, 0.2m 2 / g, 0.3m 2 / g, 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1m 2 / g, 1.1m 2 / g, 1.2m2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g、2m 2 / g or any value between the two, and based on the total mass of the electrolyte, the mass content of the carbonate additive added to the electrolyte can be selected as 1%, 2%, 3%, 4%, 5% or any value between the two.

[0182] In some embodiments, the positive electrode active material further includes an ion-conducting layer disposed on the surface of the lithium phosphate, the ion-conducting layer comprising carbon and iron elements, wherein the carbon element accounts for 1% to 2% of the total mass of the positive electrode active material.

[0183] In some embodiments, the mass percentage of carbon element, based on the total mass of the positive electrode active material, can be selected as 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any value range between the two.

[0184] It should be noted that the ion-conducting layer can be a single-layer structure or a multi-layer structure. That is, the iron-containing and carbon-containing components in the ion-conducting layer can be a mixed phase or separated into layers. It is understood that the ion-conducting layer has a high ion transport rate. The aforementioned carbon-containing 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 enhance the kinetic performance of the battery cell.

[0185] In some embodiments, the ion-conducting layer comprises a fast ion conductor with a NASICON structure as shown in Formula III, Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula III,

[0186] In the above 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.

[0187] In some implementations, b3 can be selected as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any value range between two of them; x3 can be selected as 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, or any value range between two of them; y3 can be selected as 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, or any value range between two of them.

[0188] The phase structure in the ion-conducting layer can be characterized by any known method in the art. For example, by characterizing the positive electrode active material by transmission electron microscopy, it can be seen that the ion-conducting layer and the matrix of the positive electrode active material have different phase structures. Combined with diffraction patterns and energy dispersive spectroscopy analysis, the fast ion conductor component of the ion-conducting layer can be determined.

[0189] Fast ion conductors with a NASICON structure possess abundant three-dimensional lithium-ion diffusion and transport channels, exhibiting advantages such as high ion conductivity and strong structural stability during multiple lithium deintercalation and insertion processes. Coating the surface of lithium phosphate with a fast ion conductor containing a NASICON structure can significantly improve the lithium-ion transport rate during multiple lithium deintercalation / insertion processes at the positive electrode, enhance the ionic conductivity of the positive electrode active material, and improve the kinetic performance of the corresponding battery cell.

[0190] In some embodiments, the fast ion conductor includes one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, and Li2FeSn(PO4)3.

[0191] In some embodiments, the positive electrode film layer includes a lithium replenishing agent, which includes one or more of the following: ternary lithium replenishing materials, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganate, lithium tartrate, and lithium trilithium citrate.

[0192] Lithium replenishment agents typically refer to materials that decompose and release active lithium during electrochemical processes to compensate for the irreversible loss of active lithium caused by the growth of the SEI film on the negative electrode. Adding lithium replenishment agents to the positive electrode active layer can counteract the irreversible lithium loss during electrochemical processes, thereby improving the total capacity and energy density of the battery cell.

[0193] Ternary lithium-ion supplementary materials refer to lithium-ion supplementary agents comprising one or more oxides of nickel, cobalt, and manganese. In some embodiments, the mass percentage of the lithium-ion supplementary agent is 0.1%-10% based on the total mass of the positive electrode film.

[0194] In some embodiments, based on the total mass of the positive electrode film, the mass percentage of the lithium replenishing agent can be selected as 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 the two.

[0195] The percentage of lithium replenishing agent by mass in the positive electrode film is calculated by dividing the mass of lithium replenishing agent by the total mass of the positive electrode film.

[0196] In some embodiments, the negative electrode active material includes graphite.

[0197] In some embodiments, the graphite includes composite graphite particles, the composite graphite particles including bulk particles and a coating layer at least partially disposed on the surface of the bulk particles, the bulk particles including artificial graphite, the coating layer including amorphous carbon, and the composite graphite particles including secondary particles.

[0198] Secondary particles are particles formed by the aggregation of two or more primary particles.

[0199] Composite graphite particles, including secondary particles and surface coatings including amorphous carbon, are beneficial for the wetting of electrolyte in the negative electrode active layer of the electrode, which helps to improve the rate performance of the battery cell.

[0200] In some embodiments, the composite graphite material further includes a kinetic carbon material.

[0201] In some embodiments, the kinetic carbon material is located between the primary particles of the bulk material. In this case, the bulk particles of the negative electrode active material include artificial graphite primary particles and the kinetic carbon material located between the primary particles.

[0202] In some embodiments, kinetic carbon material is located within the coating layer. In this case, the coating layer comprises both amorphous carbon and kinetic carbon material.

[0203] In some implementations, the kinetic carbon material raw material includes one or more of hard carbon, expanded graphite, and graphene.

[0204] In this article, "kinetic carbon material raw material" and "kinetic carbon material raw material powder" are completely identical in composition. "Kinetic carbon material" refers to the product of "kinetic carbon material raw material" after graphitization and / or carbonization treatment.

[0205] In some embodiments, the interlayer spacing d of the crystal planes of the kinetic carbon material raw material (002) is... 002 ≥0.3358nm, optionally 0.3359nm~0.3366nm.

[0206] 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 from it is uniformly distributed in the bulk particles and / or coating layers of composite graphite particles, it is conducive to the rapid insertion and extraction of active ions, thereby improving the transport performance of active ions and electrons, and thus improving the fast charging performance of battery cells.

[0207] In some embodiments, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5% based on the total mass of the composite graphite particles.

[0208] 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 selected as 2%, 3%, 4%, 5%, or any value range between the two.

[0209] When the content of amorphous carbon is within a suitable range, composite graphite materials can have both high specific capacity and high active ion solid-phase transport capability, which is beneficial to improving the dynamic performance of battery cells.

[0210] In some embodiments, the resistivity of the negative electrode material powder is less than or equal to 0.04 Ω·cm.

[0211] In some embodiments, the powder resistivity of the negative electrode material can be selected as 0.01 Ω·cm, 0.02 Ω·cm, 0.03 Ω·cm, 0.04 Ω·cm, or any value range between the two.

[0212] The powder resistivity of the negative electrode material can be tested by any method known in the art. As an example, the powder resistivity test method for the positive electrode active material described above can be used for testing. For example, a powder resistivity tester (PRCD1100) can be used to analyze and test the material according to the standard GB / T30835-2014.

[0213] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20000N is 1.5 g / cm³. 3 Up to 1.8 g / cm 3 1.55g / cm³ is an optional value. 3 Up to 1.75 g / cm 3 .

[0214] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 20000N can be selected as 1.5 g / cm³. 3 1.55g / cm 3 1.6g / cm 3 1.65g / cm 3 1.7g / cm 3 1.75g / cm 3 1.8g / cm 3 Or the range of values ​​between any two.

[0215] The compacted density of the negative electrode material powder under 20,000 N pressure is a well-known concept in the art and can be determined using instruments and methods known in the art. For example, it can be determined using an electronic pressure testing machine (e.g., a UTM7305 type electronic pressure testing machine) according to GB / T 24533-2009. An exemplary test method is as follows: Weigh 1 g of negative electrode active material powder and add it to a container with a bottom area of ​​1.327 cm². 2 In the mold, the pressure is increased to 20000N, held for 30s, then the pressure is released and held for 10s. The compaction density of the material under 20000N pressure is then recorded and calculated.

[0216] Anode materials with a powder compaction density within a suitable range can enable the anode active layer to have a high compaction density, thereby enabling the battery cell to have a high energy density. At the same time, the anode active layer can maintain its original pore structure during cycling, which is beneficial to maintaining the high dynamic performance of the battery cell during cycling.

[0217] In some embodiments, the negative electrode active material further includes a silicon-based material, which includes at least one of silicon, silicon oxide, and silicon-carbon composite; based on the total mass of the negative electrode active material, the silicon content in the silicon-based material is 0.3% to 10%, optionally 1% to 6%.

[0218] 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 any value range between the two.

[0219] The introduction of silicon-based materials is beneficial for improving the energy density of individual battery cells. Silicon-based materials within the aforementioned mass range can balance the energy density and cycle stability of individual battery cells.

[0220] In some embodiments, the negative electrode material includes a silicon-based material, and the electrolyte contains 3%-10% carbonate additives by mass.

[0221] In some embodiments, the mass content of carbonate additives in the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value range between the two.

[0222] Silicon-based materials are prone to expansion during cycling, which can cause the SEI film on the surface of the negative electrode material to rupture. Therefore, the consumption of additives increases relatively. Carbonate additives within the above range can improve the density and regeneration capacity of the SEI film, while taking into account the energy density and cycle stability of the battery cell.

[0223] 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, wherein 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.

[0224] Placing composite graphite particles close to the electrolyte side can improve the dynamic performance of individual battery cells while maintaining energy density.

[0225] In some embodiments, the thickness ratio 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.

[0226] In some embodiments, the ratio of the thickness of the second negative electrode active material layer to the thickness of the first negative electrode active material layer can be selected as 3:7, 4:7, 5:7, 6:7, 1:1, 2:1, 7:3 or any range between the two.

[0227] In some embodiments, the volume average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer is 9.5 μm to 18.5 μm, and can be selected as 9.5 μm to 14.8 μm.

[0228] In some embodiments, the volume average particle size Dv501 of the negative electrode active material in the first negative electrode active material layer can be selected as 9.5μm, 9.8μm, 10μm, 10.8μm, 11μm, 11.8μm, 12μm, 12.8μm, 13μm, 13.8μm, 14μm, 14.8μm, 15μm, 15.8μm, 16μm, 16.8μm, 17μm, 17.8μm, 18μm, 18.5μm or any value range between the two.

[0229] In some embodiments, the volume average particle size Dv502 of the negative electrode active material in the second negative electrode active layer is 7.8 μm to 14.3 μm, and can be selected as 7.8 μm to 12.8 μm.

[0230] In some embodiments, the volume average particle size Dv502 of the negative electrode active material in the second negative electrode active material layer can be selected as 7.8 μm, 8 μm, 8.8 μm, 9 μm, 9.8 μm, 10 μm, 10.8 μm, 11 μm, 11.8 μm, 12 μm, 12.8 μm, 13 μm, 13.8 μm, 14 μm, 14.3 μm or any value range between the two.

[0231] The volume average particle sizes Dv501 and Dv502 of the negative electrode active materials in the first and second negative electrode active material layers can be tested using the volume average particle size test method described above.

[0232] The second negative electrode active material layer disposed on the electrolyte side, including negative electrode active materials with smaller particle size, can further improve the solid-liquid transport rate of ions in the battery electrode and improve the kinetic performance of the battery cell.

[0233] In some embodiments, the volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm to 10.8 μm, and the mass content of carbonate additives in the electrolyte is 3% to 8%.

[0234] In some embodiments, the volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer can be selected as 7.8 μm, 8 μm, 8.8 μm, 9 μm, 9.8 μm, 10 μm, 10.8 μm or any value range between the two, and the mass content of carbonate additives in the electrolyte can be selected as 3%, 4%, 5%, 6%, 7%, 8% or any value range between the two.

[0235] In some embodiments, the electrolyte contains 3% to 7% by mass of vinylene carbonate (VC) and 0.5% to 2% by mass of fluoroethylene carbonate (FEC).

[0236] In some embodiments, the mass content of vinylene carbonate (VC) in the electrolyte can be selected as 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, or any range between two values, and the mass content of fluoroethylene carbonate (FEC) can be selected as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any range between two values.

[0237] In some embodiments, 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 mass content of carbonate additives in the electrolyte is 2% to 7%.

[0238] In some embodiments, the volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer can be selected as 10.8 μm, 11 μm, 11.8 μm, 12 μm, 12.8 μm, 13 μm, 13.8 μm, 14 μm, 14.8 μm or any value range between the two, and the mass content of carbonate additives in the electrolyte can be selected as 2%, 3%, 4%, 5%, 6%, 7% or any value range between the two.

[0239] The relatively small volume average particle size (Dv502) of the anode material in the second anode film layer is beneficial for the solid-phase diffusion of lithium ions in the anode active material. However, it also increases the reactivity of the anode active material with chain carboxylic acid ester solvents, leading to increased SEI film decomposition. By matching a relatively high content of carbonate additives, the density and regeneration capacity of the SEI film on the surface of the anode material can be improved, thereby enhancing the cycle stability of the battery cell.

[0240] In some embodiments, the electrolyte contains 2% to 6% by mass of vinylene carbonate (VC) and 0.5% to 2.5% by mass of fluoroethylene carbonate (FEC).

[0241] In some embodiments, the mass content of vinylene carbonate (VC) in the electrolyte can be selected as 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, or any range between two values, and the mass content of fluoroethylene carbonate (FEC) can be selected as 0.5%, 1%, 1.5%, 2%, 2.5%, or any range between two values.

[0242] In some embodiments, the chain carboxylic acid ester accounts for 25.5%-63.75% of the total mass of the electrolyte.

[0243] In some embodiments, the mass content of the chain carboxylic acid ester can be selected as 25.5%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 63.75%, or any range between the two, based on the total mass of the solvent in the electrolyte.

[0244] In some embodiments, the chain carboxylic acid ester has the general structural formula R1-COO-R2, wherein R1 and R2 each independently comprise at least one of a C1-C5 alkyl group and a C1-C5 haloalkyl group.

[0245] "C1-C5 alkyl" refers to unbranched or branched alkyl groups 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, and 1-ethylpropyl.

[0246] "C1 to C5 haloalkyl" refers to an unbranched or branched alkyl group having 1 to 5 carbon atoms in which at least one hydrogen atom is replaced by a halogen, including but not limited to one or more of chloroalkyl, bromoalkyl, and iodoalkyl.

[0247] In some embodiments, the chain carboxylic acid ester includes one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

[0248] Electrolytes with a chain carboxylic acid ester content within the above range exhibit good conductivity, wettability, and chemical stability, which is beneficial for the comprehensive improvement of battery cell dynamic performance, storage stability, and cycle stability.

[0249] In some embodiments, the solvent further includes a carbonate solvent, wherein the carbonate solvent accounts for 17%-76.5% of the total mass of the electrolyte, and optionally 21.25%-59.5%.

[0250] In some embodiments, the solvent further includes carbonate solvents, and the mass content of the carbonate solvents can be selected as 17%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 76.5% or any range between the two, based on the total mass of the solvents in the electrolyte.

[0251] In some embodiments, the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0252] Carbonate solvents in the electrolyte readily form solvation structures with lithium ions in lithium-containing electrolyte salts, thereby increasing the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salts and thus improving the kinetic performance of the battery cell.

[0253] In some embodiments, the carbonate solvent includes ethylene carbonate, and the mass ratio of the ethylene carbonate to the chain carboxylic acid ester is 0.27:1 to 1.33:1.

[0254] 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 selected from 0.27:1, 0.30:1, 0.37:1, 0.40:1, 0.47:1, 0.50:1, 0.57:1, 0.60:1, 0.67:1, 0.70:1, 0.77:1, 0.80:1, 0.87:1, 0.90:1, 0.97:1, 1:1, 1.07:1, 1.17:1, 1.27:1, 1.33:1, or any range between the two.

[0255] Chain-like carboxylic esters can improve the wettability between the electrolyte and the electrode, and enhance the solid-liquid transport rate of lithium ions between them. The addition of chain-like carboxylic esters also improves the conductivity of the electrolyte. However, chain-like carboxylic esters readily react with the SEI film, reducing the storage stability of the battery cell. Ethylene carbonate in the electrolyte readily forms a solvation structure with lithium ions in the lithium-containing electrolyte salt, increasing the dissociation rate between lithium ions and anions. However, with the increase of ethylene carbonate content, the electrolyte viscosity also increases, negatively impacting the electrolyte conductivity. Maintaining a mass ratio of ethylene carbonate to the chain-like carboxylic ester within the aforementioned range allows the electrolyte to simultaneously possess suitable viscosity, conductivity, and good dissociation rate and wettability, which is beneficial for comprehensively improving the kinetic performance and high-temperature stability of the battery cell.

[0256] 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.

[0257] In some embodiments, the mass ratio of the lithium salt to ethylene carbonate can be selected as 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, or any value range between the two.

[0258] Within the aforementioned range, ethylene carbonate in the electrolyte and lithium ions in lithium-containing electrolyte salts can increase the dissociation rate of lithium ions and improve the kinetic performance of battery cells.

[0259] In some embodiments, the conductivity of the electrolyte is 13 mS / cm-20 mS / cm; optionally, it is 15 mS / cm-20 mS / cm.

[0260] Electrolytes with conductivity within the above range can better balance the kinetic performance and high-temperature stability of battery cells.

[0261] In some embodiments, the lithium salt includes one or more of fluorosulfonyl imide salts and lithium hexafluorophosphate (LiPF6); optionally, the fluorosulfonyl imide salt includes one or more of lithium bisfluorosulfonyl imide (LiFSI) and lithium bistrifluoromethanesulfonate (LiTFSI).

[0262] Fluorosulfonyl imide salts readily dissociate in electrolyte solvents, which is beneficial for improving electrolyte conductivity. Furthermore, fluorosulfonyl imide salts exhibit high chemical stability and are not prone to decomposition during cycling, reducing hydrogen fluoride generation during battery cycling, decreasing the probability of negative electrode side reactions, and improving the cycle stability of individual battery cells. However, as the temperature of the battery cell increases, fluorosulfonyl imide salts undergo violent decomposition at a certain temperature threshold, releasing a large amount of heat and drastically increasing the risk of thermal runaway. This safety risk is even more pronounced in fast-charging batteries. Although lithium hexafluorophosphate gradually decomposes to produce hydrofluoric acid during secondary cycling, the addition of lithium hexafluorophosphate significantly reduces the risk of thermal runaway in individual battery cells, keeping the risk within a controllable range and improving battery safety.

[0263] In some embodiments, the lithium-containing electrolyte salt comprises lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6), wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) in the electrolyte is 0.2 mol / L to 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.

[0264] 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 any value range between the two.

[0265] 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 any value range between the two.

[0266] In some embodiments, the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte and the molar concentration of lithium hexafluorophosphate (LiPF6) in the electrolyte are (2-5):10.

[0267] In some embodiments, the ratio of the molar concentration of lithium difluorosulfonylimide 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 any value range between the two.

[0268] Battery cells with molar concentrations of lithium bis(fluorosulfonyl)imide in the electrolyte and lithium hexafluorophosphate (LiPF6) in the electrolyte within the above-mentioned ranges can balance the kinetic performance and safety performance of the battery cells.

[0269] In some embodiments, the battery cell further includes a separator, the separator comprising a porous base film and a functional layer disposed on at least one side of the porous base film, the thickness of the porous base film being ≤12μm, optionally less than or equal to 9μm.

[0270] In some embodiments, the thickness of the porous base film can be selected as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm or any value range between the two.

[0271] In some embodiments, the porous base membrane includes one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The porous base membrane can be a single-layer film or a multi-layer composite film, without particular limitation.

[0272] In some embodiments, the porosity of the porous base membrane in the separator is 20%-70%, optionally 35%-60%.

[0273] In some embodiments, the porosity of the porous base membrane in the isolation membrane can be selected as 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any value range between the two.

[0274] In some embodiments, the functional layer includes a first functional layer disposed on the negative electrode side of the porous base membrane and a second functional layer disposed on the positive electrode side of the porous base membrane. The first functional layer includes first inorganic particles, and the second functional layer includes composite particles. The composite particles include second inorganic particles and a non-fluoropolymer. 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.

[0275] 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.

[0276] Inorganic particles can improve the heat resistance of the first and second functional layers and improve the dynamic performance of the battery cells.

[0277] In some embodiments, the non-fluoropolymer particles comprise acrylate copolymers.

[0278] In some embodiments, the electrolyte injection coefficient of the battery cell is 2.2 g / Ah-3.1 g / Ah.

[0279] The electrolyte filling coefficient of a battery cell refers to the ratio of the mass of electrolyte inside the battery cell to the battery capacity. The electrolyte filling coefficient of a battery cell can be obtained by any method known in the art. For example, the mass of electrolyte in a 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. Remove the internal electrode assembly and separate the positive electrode, negative electrode, separator, and mechanical components. Soak the positive electrode, negative electrode, separator, and mechanical components in dimethyl carbonate (DMC) solvent for 24-48 hours, repeating the soaking process at least three times. Place the aforementioned positive electrode, negative electrode, separator, and mechanical components in a 100°C oven for at least 24 hours until completely dried. Weigh the dried positive electrode, negative electrode, separator, and mechanical components, and record the mass as M1. The mass of electrolyte in the battery cell is thus obtained as (M0-M1). The electrolyte filling coefficient is calculated by dividing (M0-M1) by the rated capacity of the battery cell. The rated capacity is the nominal capacity of the battery, or the rated capacity is obtained by charging the battery to 3.65V at a charging rate of 0.33C, then charging it to 0.05C at a constant voltage of 3.65V, letting it stand for 10 minutes, and then discharging it to 2.0V at a discharging rate of 0.33C.

[0280] In some embodiments, the electrolyte injection coefficient of the battery cell can be selected as 2.2g / Ah, 2.3g / Ah, 2.4g / Ah, 2.5g / Ah, 2.6g / Ah, 2.7g / Ah, 2.8g / Ah, 2.9g / Ah, 3.0g / Ah, 3.1g / Ah, or any value range between the two.

[0281] In some embodiments, the fast charging time for the battery cell from 10% SOC to 80% SOC is 6 min to 15 min.

[0282] The fast charging time for a single battery cell from 10% SOC to 80% SOC can be tested using any method known in the art. As an example, the battery cell is disassembled, and the positive electrode, negative electrode, and free electrolyte are removed. The cells are then soaked and cleaned in dimethyl carbonate (DMC) solvent for at least 72 hours. After the electrolyte solvent, lithium salt, and additives are completely leached out, the positive and negative electrode plates are dried in a vacuum oven. Then, using copper wire as a reference electrode, the free electrolyte from the battery cell is added, and the positive and negative electrode plates are assembled into a stacked three-electrode cell. At 30°C, the stacked three-electrode cell is charged at a constant current of 0.33C to the charging cutoff voltage of 3.65V, then charged at a constant voltage to a current of 0.05C, allowed to stand for 5 minutes, and then discharged at a constant current of 0.33C to the discharge cutoff voltage of 2.5V. Its actual capacity is recorded as C0. Then, the battery cells were sequentially charged at a constant current of 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, 4.5C0, 5C0, 5.5C0, and 6C0 until the reference electrode potential dropped to 0mV. The maximum charging rate at this SOC was recorded. Using 5% SOC as an increment, the maximum charging rate at each 5% SOC was tested, such as 5% SOC, 10% SOC, 15% SOC to 100% SOC. The corresponding maximum charging rates were recorded as C5% SOC, C10% SOC, C15% SOC to C100% SOC. The continuous charging time from 10% SOC to 80% SOC, calculated based on the maximum charging rates obtained from this test, is the fast charging time.

[0283] In some embodiments, the fast charging time for 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 any value range between the two.

[0284] The battery cell has good dynamic performance and can meet the needs of improving the energy replenishment efficiency of electrical devices.

[0285] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0286] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0287] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 shows a square battery cell 5 as an example.

[0288] In some embodiments, referring to FIG4, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0289] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0290] Figure 5 shows a battery module 4 as an example. Referring to Figure 5, in the battery module 4, multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 5 can be fixed in place using fasteners.

[0291] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0292] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0293] Figures 6 and 7 illustrate a battery pack 1 as an example. Referring to Figures 6 and 7, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0294] The second aspect of this application provides a battery device including the battery cell provided in the first aspect of this application. The battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0295] In addition, this application also provides an electrical device, which includes the battery cell provided in this application. The battery cell, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0296] In some embodiments, the fast charging time for the electrical device from 10% SOC to 80% SOC is 6 to 15 minutes.

[0297] In some embodiments, the fast charging time of the electrical device from 10% SOC to 80% SOC can be selected as 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, or any value range between the two.

[0298] As the electrical device, a single battery cell, a battery module, or a battery pack can be selected according to its usage requirements.

[0299] Figure 8 shows an example of an electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the individual battery cells, a battery pack or battery module can be used.

[0300] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0301] Example

[0302] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0303] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0304] Example 1

[0305] Preparation of the positive electrode sheet:

[0306] The positive electrode includes a positive current collector, a positive conductive layer on the positive current collector, and a positive film layer. The positive current collector is an aluminum foil with a thickness of 10 μm.

[0307] The positive electrode conductive layer on the positive electrode current collector is a film formed by uniformly mixing the positive electrode conductive agent superconducting carbon, the positive electrode binder polyvinylidene fluoride (PVDF), and the solvent N-methylpyrrolidone (NMP), coating it on the surface of the current collector, and drying it. The thickness is 1 μm. The positive electrode conductive layer contains 40% positive electrode conductive agent by mass and 60% positive electrode binder by mass.

[0308] The positive electrode film layer comprises a film layer formed by uniformly coating a positive electrode slurry (solvent being N-methylpyrrolidone, NMP) onto the surface of a positive electrode conductive layer, followed by drying and cold pressing. The positive electrode film layer comprises positive electrode active material, binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black in a weight ratio of 97:2:1.

[0309] The positive electrode active material includes lithium iron phosphate with a coating layer. The coating layer is coated on the surface of the lithium iron phosphate and includes lithium titanium iron phosphate (Li2FeTi(PO4)3) and amorphous carbon. The Dv50 of the positive electrode active material is 1.6 μm, and the Dv10 is 0.64 μm.

[0310] The single-sided coating weight of the positive electrode film is 300 mg / 1540.25 mm. 2 .

[0311] Preparation of negative electrode sheet:

[0312] The negative electrode sheet includes a negative current collector, a negative conductive layer on the negative current collector, and a negative film layer. The negative current collector is a copper foil with a thickness of 5μm.

[0313] The negative electrode conductive layer on the negative electrode current collector is a film formed by uniformly mixing the negative electrode conductive agent superconducting carbon, the negative electrode binder styrene-butadiene rubber SBR, the thickener sodium carboxymethyl cellulose (CMC-Na), and the solvent water, coating it on the surface of the negative electrode current collector, and drying it. The thickness is 1 μm. The negative electrode conductive agent has a mass content of 35% in the negative electrode conductive layer, the negative electrode binder has a mass content of 60% in the negative electrode conductive layer, and the thickener has a mass content of 5% in the negative electrode conductive layer.

[0314] The negative electrode film layer comprises a film layer formed by uniformly coating a negative electrode slurry (with deionized water as the solvent) onto the surface of a negative electrode conductive layer, followed by drying and cold pressing.

[0315] The single-sided coating weight of the negative electrode film is 138 mg / 1540.25 mm.2 .

[0316] 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.

[0317] The first negative electrode film layer comprises graphite particles in a mass ratio of 96.5:0.5:0.5:1.5:1, conductive agent acetylene black, a first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose. The lithium content in the first lithium-containing binder is 4.8% by mass. The Dv50 of the graphite particles is 11.3 μm. The graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer coats the surface of the artificial graphite, and the carbon coating layer has a mass content of 3.5%.

[0318] The second negative electrode film layer comprises graphite particles in a mass ratio of 97.5:0.5:0.5:0.5:1, conductive agent acetylene black, a second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose. The lithium content in the second lithium-containing binder is 4.8% by mass. The graphite particles have a Dv50 of 11.3 μm and include artificial graphite and a carbon coating layer. The carbon coating layer coats the surface of the artificial graphite and has a carbon coating layer content of 3.5% by mass. Electrolyte preparation.

[0319] In an argon-atmospheric glove box with a water content of <10 ppm, ethylene carbonate EC, ethyl methyl carbonate (EMC), and ethyl acetate (EA) were uniformly mixed at a mass ratio of 35:15:50 to obtain the electrolyte solvent. Lithium hexafluorophosphate (LiPF6) was slowly added as the lithium salt, and stirred thoroughly until completely dissolved. After returning to room temperature, 2% (by mass) of vinylene carbonate (VC), 2% (by mass) of fluoroethylene carbonate (FEC), and 1% (by mass) of lithium difluorophosphate (LiPO2F2) were added sequentially, and the mixture was thoroughly mixed to obtain the electrolyte. Based on the total mass of the electrolyte, the lithium salt content was 15%, and the conductivity of the electrolyte was 15.4 mS / cm.

[0320] Preparation of the separating membrane

[0321] The first functional layer, a nano-alumina coating, is applied to the negative electrode side, while the other side is coated with a nano-alumina coating and a polyethylene (PE) membrane made of polyacrylic acid as a separator. The porous PE membrane has a porosity of 35% and a thickness of 7 μm.

[0322] Preparation of battery cells

[0323] The positive electrode, separator, and negative electrode are stacked and wound in sequence to obtain a wound electrode assembly. The electrode assembly is then placed in a square aluminum outer casing, dried, and injected with electrolyte. After processes including encapsulation, settling, formation, aging, secondary encapsulation, and capacity testing, a single battery cell is obtained. The electrolyte retention coefficient d3 / A of the single battery cell is 2.9 g / Ah.

[0324] The preparation methods of Examples 2-4 and 9-17 are basically the same as those of Example 1, except that the composition of the electrolyte is adjusted, as shown in Table 1.

[0325] The preparation methods of Examples 5-8 are basically the same as those of Example 1, except that the Dv50 of the negative electrode active material and / or the electrolyte composition are adjusted.

[0326] The preparation methods of Examples 18-21 are basically the same as those of Example 1, except that the Dv50 of the positive electrode active material and / or the electrolyte composition are adjusted.

[0327] The preparation method of Example 22 is basically the same as that of Example 1, except that the type of positive electrode active material is adjusted. The ternary positive electrode active material in Example 22 is NCM811.

[0328] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that no phosphorus-containing additives are added to the electrolyte.

[0329] Test methods

[0330] The individual battery cells in the examples and comparative examples were tested separately. The test results are shown in Table 1.

[0331] (1) The method for high-temperature storage DCR testing is as follows:

[0332] 1. Battery DCR Test Method

[0333] The DCR test method can be found in GB / T 31467 "Performance Test Specification for High-Power Lithium-ion Power Batteries for HEVs". Details are as follows:

[0334] At 25°C, the lithium-ion battery was charged to 3.65V with a constant current of 0.33C and allowed to stand for 1 minute; then charged to 3.65V with a constant current of 0.1C and allowed to stand for 30 minutes; then discharged to 2.0V with a constant current of 0.33C and the discharge capacity A0 (in Ah) was recorded. Then, the battery was charged to 0.5A0Ah with a constant current of 0.33C and the SOC was adjusted to 50%.

[0335] After placing the battery at 25°C for 2 hours, it was discharged at a constant current of 2C for 10 seconds, and ΔU was recorded. 放电 ΔI 放电 The discharge DCR data of lithium-ion batteries can be calculated using the following formula. 放电 =ΔU 放电 / ΔI 放电

[0336] Wherein, ΔU 放电 ΔI represents the voltage change within 10 seconds of the start of discharge. 放电 This indicates the current value within 10 seconds of the start of discharge.

[0337] 2. Battery High-Temperature Storage Test Method: First, test the DCR value of the battery before high-temperature storage as D0. Then, at 25℃, charge the lithium-ion battery cell to 3.65V with a constant current of 0.33C and let it stand for 1 minute; then charge it to 3.65V with a constant current of 0.1C, adjust the charge to 100% SOC, and then store the lithium-ion battery cell at 60℃. Every 30 days, remove the battery and measure the DCR value at 25℃, repeating this process. Record the DCR values ​​after storage as D1, D2, ..., Dn. The storage DCR growth method is: (Dn - D0) / D0, where n is 1, 2, 3, 4...n.

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

[0339] (2) Cycle count test at 60℃:

[0340] At 60℃, charge the battery to 3.65V at a 1C charging rate (1C of the battery's nominal capacity), then charge it to 0.05C at 3.65V, let it rest for 10 minutes, and then discharge it to 2.5V at a 1C discharging rate, let it rest for 10 minutes. One charge-discharge cycle is recorded as one cycle. Continue the test until the battery capacity decreases to 80% of its initial discharge capacity, and this number is recorded as the cycle number @ 80% SOH.

[0341] (3) Parameter testing methods for battery thermal runaway:

[0342] ① Charge adjustment: At 25℃, charge the lithium-ion battery to 3.65V with a constant current of 0.33C and let it stand for 1 minute; then charge it to 3.65V with a constant current of 0.1C to adjust the battery to 100% SOC state.

[0343] ② Overcharge to thermal runaway test: The battery is placed with a test fixture with a clamping force of 3000N, and then charged at a constant current rate of 1C until the cell thermal runaway occurs. After the battery cools to room temperature, the state of the thermal runaway cell is observed. If fire or explosion occurs, the thermal runaway boundary deteriorates. The test results are shown in Tables 1-3.

[0344] Table 1

[0345] Table 2

[0346] Table 3

[0347] Test Results

[0348] XPS testing was performed on the surface of the negative electrode film of the formed battery cell. The negative electrode in the example showed a characteristic peak in the 2p electron X-ray photoelectron spectroscopy (XPS) spectrum of phosphorus in the range of 132 eV to 138 eV; while no characteristic peak was found in the 2p electron X-ray photoelectron spectroscopy (XPS) spectrum of phosphorus in Comparative Examples 1 and 2. Compared with the comparative examples, the battery cell in the example exhibits good high-temperature stability.

[0349] Except for Example 4, the negative electrode in other examples also showed characteristic peaks in the 684.5 eV to 686 eV range in the 1s electron X-ray photoelectron spectrum (XPS) of fluorine.

[0350] The above tests show that the negative electrode film layer in the battery cell of the embodiment includes Li on the surface away from the negative electrode current collector. x PO y F z and / or the general formula is 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.

[0351] As can be seen from the comparison of Examples 1 and 9-11, when the mass content of vinylene carbonate added to the electrolyte is 2% to 6% and the mass content of fluoroethylene carbonate added is 0.5% to 2.5%, the battery cell can better balance good high-temperature storage performance and cycle stability.

[0352] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same essential structure and achieving the same effect as the technical concept within the scope of this disclosure are included in the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included in the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A battery cell, characterized by The positive electrode sheet, the negative electrode sheet and the electrolyte solution; The electrolyte solution comprises a solvent, and the solvent comprises a chain carboxylic acid ester solvent, and the electrolyte solution has an electrical conductivity of 13 mS / cm to 20 mS / cm. The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, and the negative electrode film layer comprises a negative electrode material, and the negative electrode material has a phosphorus element 2p characteristic peak with a binding energy of 132 eV to 138 eV in X-ray photoelectron spectroscopy (XPS).

2. The battery cell of claim 1, wherein, The phosphorus element 2p characteristic peak comprises 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 of claim 1, wherein, The negative electrode material has a fluorine element 1s characteristic peak with a binding energy of 684.5 eV to 686 eV in X-ray photoelectron spectroscopy (XPS).

4. The battery cell according to any one of claims 1 to 3, characterized in that, The negative electrode film layer comprises an inorganic phosphorus-containing component of the general formula Li x PO y F z and / or the general formula Li x0 PF z0 wherein 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, on the surface of the negative electrode current collector away from the negative electrode current collector.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The electrolyte solution comprises a phosphorus-containing additive, and optionally, the phosphorus-containing additive comprises one or more of lithium difluorobis(oxalato)phosphate, lithium difluorophosphate tris(trimethylsilyl) phosphate, triphenyl phosphine oxide, pentafluoro(phenoxy)cyclotriphosphazene, N-(triphenylphosphoranylidene)aniline, diethyl phenylphosphonate, triphenyl phosphite, methyl diphenyl phosphite, triethyl phosphite, and N,N-diallyl-diethoxyphosphoramide.

6. The battery cell of claim 5, wherein, The phosphorus-containing additive comprises one or more of lithium difluorobis(oxalato)phosphate, lithium difluorophosphate, pentafluoro(phenoxy)cyclotriphosphazene, N-(triphenylphosphoranylidene)aniline, diethyl phenylphosphonate, and triphenyl phosphite.

7. The battery cell according to claim 5 or 6, characterized in that, The phosphorus-containing additive further comprises fluorine element, and optionally, the phosphorus-containing additive comprises one or more of lithium difluorobis(oxalato)phosphate, lithium difluorophosphate, and pentafluoro(phenoxy)cyclotriphosphazene.

8. The battery cell of any one of claims 1 to 7, wherein, The mass content of the phosphorus-containing additive in the electrolyte solution of the battery cell is 0.1% to 3% based on the total mass of the electrolyte solution.

9. The battery cell of any one of claims 1 to 8, wherein, The volume distribution particle size Dv50 of the negative electrode material 负 is 7.8 pm - 14.3 pm.

10. The battery cell of claim 9, wherein, The volume distribution particle size Dv50 of the negative electrode material 负 7.8 μm to 10.8 μm, and the mass content of the phosphorus-containing additive in the electrolyte is 0.3% to 1.8%.

11. The battery cell of claim 9, wherein, The volume distribution particle size Dv50 of the negative electrode active material 负 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%.

12. The battery cell of any one of claims 1 to 11, wherein, The electrolyte solution further comprises a carbonate additive, and the carbonate additive comprises one or more of vinylene carbonate and fluoroethylene carbonate.

13. The battery cell of claim 12, wherein, The electrolyte solution comprises vinylene carbonate and fluoroethylene carbonate.

14. The battery cell according to claim 12 or 13, characterized in that, The mass content of the carbonate additive is 2% to 10%, and optionally 3% to 8%, based on the total mass of the electrolyte solution.

15. The battery cell of any one of claims 12 to 14, wherein, The mass content of vinylene carbonate in the electrolyte solution is 1.5% to 8%, and optionally 2% to 6.5%, based on the total mass of the electrolyte solution.

16. The battery cell of any one of claims 12 to 15, wherein, The mass content of fluoroethylene carbonate in the electrolyte solution is 0.1% to 4%, and optionally 0.5% to 3%, based on the total mass of the electrolyte solution.

17. The battery cell of any one of claims 1 to 16, wherein, The positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises one or more of lithium-containing phosphate with olivine structure and lithium-containing transition metal oxide.

18. The battery cell of claim 17, wherein, The specific surface area of the positive electrode active material is 5.0 m 2 / g ~ 9.4 m 2 The specific surface area of the positive electrode active material is 5.0 m The mass content of the carbonate-based additive added in the electrolyte is 2% - 6% based on the total mass of the electrolyte.

19. The battery cell of claim 17, wherein, The specific surface area of the positive electrode active material is 9.5 m 2 / g ~ 18 m 2 / g, and the mass content of the carbonate-based additive added in the electrolyte is 3% - 8% based on the total mass of the electrolyte.

20. The battery cell of any one of claims 17-19, wherein, The positive electrode active material comprises a lithium-containing phosphate of olivine structure, the composition of which is represented by 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 comprises one or more of Na, K, and Mg; Me comprises one or more of Mn, Fe, Co, and Ni; M comprises 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 comprises one or more of S, Si, Cl, B, C, and N; Y comprises one or more of O and F.

21. The battery cell of claim 20, wherein, The specific surface area of the lithium-containing phosphate of olivine structure is 5.0 m 2 / g to 18.0 m 2 / g.

22. The battery cell of any one of claims 17-19, wherein, The positive electrode active material includes a lithium-containing transition metal oxide having a general composition as 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 comprises one or more of Na, K, and 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, and Ce; Y comprises one or more of O and F.

23. The battery cell of claim 22, wherein, The specific surface area of the lithium-containing transition metal oxide is 0.1 m 2 / g ~ 2 m 2 / g, and the mass content of the carbonate-based additive in the electrolyte is 1% - 5% based on the total mass of the electrolyte.

24. The battery cell of any one of claims 17-23, wherein, The positive electrode active material further comprises an ion-conducting layer disposed on the surface of the lithium-containing phosphate, the ion-conducting layer comprising carbon and iron, the mass percentage of carbon being 1% to 2% based on the total mass of the positive electrode active material.

25. The battery cell of claim 24, wherein, The ion-conducting layer comprises an ion conductor having a NASICON structure as shown in Formula III, Li 3-b3 Fe 2-b3 M2 b3 (PO x3 ) y3 Formula III, In the formula III, M2 comprises one or more of Ti, Zr, Hf, Ge, and Sn, and optionally, M2 is in a +4 valence, 0≤b3≤1, 3≤x3≤5, and 2≤y3≤4.

26. The battery cell of any one of claims 17-25, wherein, The positive electrode film layer comprises a lithium supplementing agent, the lithium supplementing agent comprising one or more of a ternary lithium supplementing material, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium manganite, lithium tartrate, and trilithium citrate.

27. The battery cell of claim 26, wherein, The mass percentage of the lithium supplementing agent is 0.1% to 10% based on the total mass of the positive electrode film layer.

28. The battery cell of any one of claims 1-27, wherein, The negative electrode material comprises graphite.

29. The battery cell of claim 28, wherein, The graphite comprises composite graphite particles, the composite graphite particles comprising a bulk particle and a coating layer disposed on the surface of the bulk particle, the bulk particle comprising artificial graphite, and the coating layer comprising amorphous carbon, the composite graphite particles comprising secondary particles, and optionally, the mass content of amorphous carbon in the coating layer of the composite graphite particles is 2% to 5% based on the total mass of the composite graphite particles.

30. The battery cell of any one of claims 1-29, 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 20000N pressure is 1.5g / cm 3 to 1.8g / cm 3 , optionally 1.55g / cm 3 to 1.75g / cm 3 .

31. The battery cell of any one of claims 1-30, wherein, The negative electrode material further comprises a silicon-based material, the silicon-based material comprising one or more of a silicon oxide compound and a silicon-carbon composite; the silicon-based material having a mass content of silicon element of 0.3%-10%, or 1%-6%, based on the total mass of the negative electrode active material.

32. The battery cell of any one of claims 1-31, wherein, The negative electrode material comprises a silicon-based material, and the mass content of the carbonate-based additive in the electrolyte is 3%-10%.

33. The battery cell of any one of claims 1-32, wherein, The negative electrode film layer comprises a first negative electrode film layer arranged on the surface of the negative electrode current collector and a second negative electrode film layer arranged on the side of the first negative electrode film layer away from the negative electrode current collector, the second negative electrode film layer comprising composite graphite particles; optionally, the negative electrode material in the first negative electrode film layer comprises one or more of composite graphite particles and natural graphite.

34. The battery cell of claim 33, wherein, The thickness ratio of the second negative electrode film layer to the first negative electrode film layer is 3:7 to 7:

3.

35. The battery cell of claim 33 or 34, wherein, The volume average particle size Dv501 of the negative electrode material in the first negative electrode film layer is 9.5 μm-18.5 μm, or 9.5 μm-14.8 μm.

36. The battery cell of any one of claims 33-35, wherein, The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm-14.3 μm, or 7.8 μm-12.8 μm.

37. The battery cell of any one of claims 33-36, wherein, The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 7.8 μm-10.8 μm, and the mass content of the carbonate-based additive in the electrolyte is 3%-8%.

38. The battery cell of claim 37, wherein, In the electrolyte, the mass content of vinylene carbonate is 3%-7%, and the mass content of fluoroethylene carbonate is 0.5%-2%.

39. The battery cell of any one of claims 33-38, wherein, The volume average particle size Dv502 of the negative electrode material in the second negative electrode film layer is 10.8 μm-14.8 μm, and the mass content of the carbonate-based additive in the electrolyte is 2%-7%.

40. The battery cell of claim 39, wherein, In the electrolyte, the mass content of vinylene carbonate is 2%-6%, and the mass content of fluoroethylene carbonate is 0.5%-2.5%.

41. The battery cell of any one of claims 1-40, wherein, The mass content of the chain carboxylic acid ester accounts for 25.5%-63.75% based on the total mass of the electrolyte.

42. The battery cell of any one of claims 1-41, wherein, The chain carboxylic acid ester has a general structure of R1-COO-R2, wherein R1 and R2 each independently comprises at least one of C1-C5 alkyl and C1-C5 halogenated alkyl.

43. The battery cell of any one of claims 1-42, wherein, The chain carboxylic acid ester comprises one or more of ethyl butyrate, ethyl propionate, ethyl acetate, methyl acetate, and methyl formate.

44. The battery cell of any one of claims 1-43, wherein, The solvent further comprises a carbonate-based solvent, and the mass content of the carbonate-based solvent accounts for 17%-76.5%, or 21.25%-59.5%, based on the total mass of the electrolyte.

45. The battery cell of claim 44, wherein, The carbonate-based solvent comprises one or more of vinylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

46. The battery cell of either claim 44 or 45, wherein, The carbonate-based solvent comprises vinylene carbonate, and the mass ratio of the vinylene carbonate to the chain carboxylic acid ester is 0.27:1-1.33:

1.

47. The battery cell of either claim 44 or 45, wherein, The electrolyte comprises a lithium salt, and the carbonate-based solvent comprises vinylene carbonate, wherein the mass ratio of the lithium salt to the vinylene carbonate is 0.29-0.

72.

48. The battery cell of any one of claims 1-47, wherein, The electrolyte has an electrical conductivity of 13 mS / cm to 20 mS / cm, and optionally 15 mS / cm to 20 mS / cm.

49. The battery cell of any one of claims 47-48, wherein, The lithium salt comprises one or more of a fluorine-containing sulfimide salt and lithium hexafluorophosphate; optionally, the fluorine-containing sulfimide salt comprises one or more of lithium bisfluorosulfimide and lithium bistrifluoromethylsulfonimide.

50. The battery cell of any one of claims 47-49, wherein, The lithium salt comprises lithium bisfluorosulfimide and lithium hexafluorophosphate, the molar concentration of lithium bisfluorosulfimide in the electrolyte is 0.2 mol / L to 0.5 mol / L, and the molar concentration of lithium hexafluorophosphate in the electrolyte is 0.5 mol / L to 1.0 mol / L.

51. The battery cell of claim 50, wherein, The ratio of the molar concentration of lithium bisfluorosulfimide in the electrolyte to the molar concentration of lithium hexafluorophosphate in the electrolyte is (2-5):

10.

52. The battery cell of any one of claims 1-51, wherein, The battery cell further comprises a separator film, the separator film comprises a porous base film and a functional layer arranged on at least one side of the porous base film, the thickness of the porous base film is ≤12 μm, and optionally ≤9 μm.

53. The battery cell of claim 52, wherein, The porosity of the porous base film in the separator film is 20% to 70%, and optionally 35% to 60%.

54. The battery cell of either claim 52 or 53, wherein, The functional layer comprises a first functional layer arranged on the negative side of the porous base film and a second functional layer arranged on the positive side of the porous base film, the first functional layer comprises first inorganic particles, and the second functional layer comprises composite particles, the composite particles comprise second inorganic particles and non-fluorinated polymers, and the second inorganic particles in the composite particles are attached to the surface of the non-fluorinated polymer particles and / or dispersed in the interior of the non-fluorinated polymer particles.

55. The battery cell of claim 54, wherein, The non-fluorinated polymer particles comprise an acrylate copolymer.

56. The battery cell of any one of claims 1-55, wherein, The battery cell has a liquid injection coefficient of 2.2 g / Ah to 3.1 g / Ah.

57. The battery cell of any one of claims 1-56, wherein, The battery cell has a fast charging time of 6 min to 15 min for charging the battery cell from 10% state of charge (SOC) to 80% state of charge (SOC).

58. A battery device, comprising: The battery device comprises at least one of a battery module, a battery pack, and an energy storage battery, and comprises the battery cell of any one of claims 1 to 57.

59. An electrical device, comprising: The battery cell of any one of claims 1 to 57.

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