WO2024067290A1 - 锂电池及用电设备 - Google Patents

锂电池及用电设备 Download PDF

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Publication number
WO2024067290A1
WO2024067290A1 PCT/CN2023/120029 CN2023120029W WO2024067290A1 WO 2024067290 A1 WO2024067290 A1 WO 2024067290A1 CN 2023120029 W CN2023120029 W CN 2023120029W WO 2024067290 A1 WO2024067290 A1 WO 2024067290A1
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Prior art keywords
negative electrode
lithium battery
active material
electrode active
battery according
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PCT/CN2023/120029
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English (en)
French (fr)
Inventor
张伟
李红红
金菁
雷裕东
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比亚迪股份有限公司
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Publication of WO2024067290A1 publication Critical patent/WO2024067290A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of battery technology, and in particular to a lithium battery and electrical equipment.
  • Lithium-ion batteries also known as “lithium batteries” are widely used in mobile electronic devices, electric vehicles, drones, etc. due to their high voltage, long life, and no memory effect. With the continuous development of products powered by lithium-ion batteries, people have put forward higher requirements for the energy density, cycle performance, and safety performance of lithium-ion batteries.
  • the negative electrode active material is constantly inserting and removing lithium, which causes the solid electrolyte interface (SEI) on the surface of the negative electrode active material to continuously rupture and generate new interfaces, causing the negative electrode active material to directly contact the electrolyte, thereby inducing side reactions and causing the loss of active lithium, thereby reducing the energy density and cycle life of the battery.
  • SEI solid electrolyte interface
  • the stability of the SEI film formed on the negative electrode surface will also directly affect the furnace temperature test stability of the lithium-ion battery, which is directly related to the safety performance of the lithium-ion battery.
  • the present application provides a lithium-ion battery and electrical equipment, which can ensure that the lithium-ion battery has a long cycle life and good 130°C furnace temperature performance by defining the relative relationship between the thickness of the negative electrode active material layer, the particle size of the negative electrode active material, and the electrolyte.
  • the present application provides a lithium battery.
  • the lithium battery comprises a positive electrode plate, a negative electrode plate, a separator, and an electrolyte
  • the negative electrode plate comprises a current collector and a negative electrode active material layer disposed on at least one side surface of the current collector
  • the electrolyte comprises a lithium salt, an organic solvent, and an additive
  • the additive comprises a fluorocarbonate and a nitrile substance
  • the thickness of the negative electrode active material layer is D 1 ⁇ m
  • the particle size corresponding to the volume cumulative distribution percentage of the negative electrode active material contained in the negative electrode active material layer when it reaches 50% is D v 50 ⁇ m
  • the particle size corresponding to the volume cumulative distribution percentage of the negative electrode active material contained in the negative electrode active material layer when it reaches 90% is D v 90 ⁇ m
  • the mass content of the fluorocarbonate is W 0 %
  • the mass content of the nitrile substance is W 1 %
  • the battery performance factor k is defined, and by controlling k in the range of 0.5-3, the purpose of jointly improving the cycle performance and furnace temperature performance of the lithium battery can be achieved.
  • the value range of k is: 1.0 ⁇ k ⁇ 2.0.
  • the value range of W 0 is: 2 ⁇ W 0 ⁇ 16.
  • the value range of W 0 is: 5 ⁇ W 0 ⁇ 10.
  • the value range of W 1 is: 2 ⁇ W 1 ⁇ 10.
  • the ratio of W 0 to W 1 satisfies: 0.5 ⁇ W 0 /W 1 ⁇ 4.
  • the ratio of W 0 to W 1 satisfies: 1.5 ⁇ W 0 /W 1 ⁇ 3.0.
  • the value range of D 1 is: 30 ⁇ D 1 ⁇ 90.
  • the value range of D 1 is: 40 ⁇ D 1 ⁇ 80.
  • the particle size of the negative electrode active material satisfies: 8 ⁇ D v 50 ⁇ D v 90 ⁇ 40.
  • the ratio of the D 1 to the D v 90 is greater than or equal to 1.
  • the fluorocarbonate includes at least one of fluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4,5,5-tetrafluoroethylene carbonate, and 4-trifluoromethylethylene carbonate; and the nitrile substance includes at least one of succinonitrile, adiponitrile, glutaronitrile, butene dinitrile, 1,4-dicyano-2-butene, 3,3'-oxydipropionitrile, ethylene glycol diethyl cyanide, 1,2,3-tris(2-cyanoxy)propane, 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile and 1,3,6-hexanetricarbonitrile.
  • the nitrile substance includes at least one of succinonitrile, adiponitrile, glutaronitrile, butene dinitrile, 1,4-dicyano-2-butene, 3,3'-oxydipropionitrile, ethylene glycol dieth
  • the organic solvent includes a carboxylate substance, wherein the carboxylate substance includes at least one of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, ethyl haloacetate, ethyl halopropionate, propyl halopropionate, butyl halopropionate and pentyl halopropionate.
  • the carboxylate substance includes at least one of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, ethyl haloacetate, ethyl halopropionate, propyl halopropionate, butyl halopropionate and pentyl halopropionate.
  • the organic solvent further comprises a cyclic carbonate.
  • the organic solvent further comprises a linear carbonate substance.
  • the total mass content of the carboxylic acid ester substances is W 2 %, and W 2 /W 0 ⁇ 2.
  • the ratio of W 2 to W 0 satisfies: 2.5 ⁇ W 2 /W 0 ⁇ 8.
  • the additive further comprises at least one of 1,3-propane sultone, vinylene carbonate, and vinyl ethylene carbonate.
  • the present application provides an electrical device, wherein the electrical device comprises the lithium battery as described in the first aspect of the present application.
  • the battery of the electrical equipment Due to the adoption of the lithium battery, the battery of the electrical equipment has a strong endurance, good cycle performance and high safety.
  • FIG. 1 is a schematic structural diagram of a lithium battery according to an embodiment of the present application.
  • FIG. 2 is a schematic diagram of the structure of an electrical device according to an embodiment of the present application.
  • the lithium battery 10 includes a positive electrode plate 110, a negative electrode plate 120, a separator 130, and an electrolyte 140
  • the negative electrode plate 120 includes a negative electrode current collector 121 and a negative electrode active material layer 122 disposed on at least one side of the negative electrode current collector 121
  • the electrolyte includes a lithium salt, an organic solvent, and an additive
  • the additive includes a fluorocarbonate and a nitrile substance, wherein the thickness of the negative electrode active material layer 122 is D 1 ⁇ m, the volume cumulative distribution percentage of the negative electrode active material contained in the negative electrode active material layer 122 reaches 50% and the corresponding particle size is D v 50 ⁇ m, and the volume cumulative distribution percentage of the negative electrode active material contained in the negative electrode active material layer 122 reaches 90% and the corresponding particle size is D v 90 ⁇ m; based on the total mass of the electrolyte 140, the mass content of the fluorocarbonate is W
  • the positive electrode sheet 110 includes a positive electrode current collector 111 and a positive electrode current collector 112 disposed on the positive electrode
  • the current collector 111 includes a positive electrode active material layer 112 on at least one surface thereof.
  • nitrile substances can be complexed at the positive electrode interface to form a protective film, isolating the electrolyte and the positive electrode active material, reducing the dissolution of positive electrode metal ions, reducing the oxidation and decomposition of the electrolyte by the positive electrode active material, and improving the furnace temperature performance of the battery.
  • the two types of additives, fluorocarbonate and nitrile substances are used together to make the functions of the two complement each other, and the content of the two is also connected with the particle size of the negative electrode active material and the thickness of the negative electrode active material layer, and the battery performance factor k is defined, and k is controlled in the range of 0.5-3, which can ensure that the lithium battery can better take into account long cycle life and good furnace temperature performance.
  • the above D 1 /D v 90 can reflect the degree of fragmentation of the negative electrode active particles during the rolling process of the negative electrode sheet to a certain extent.
  • the above D v 50 reflects the overall size of the negative electrode active material particles, for example, it can specifically reflect the number of surface active sites of the negative electrode active material particles and the degree of particle fragmentation during the rolling process. The rupture of the negative electrode active particles will produce more active interfaces, resulting in a larger consumption of electrolyte during the formation and circulation process, and causing the negative electrode active material to lose capacity and easily precipitate lithium on the negative electrode surface during the charging process.
  • the above fluorinated carbonate can form a stable SEI film at the negative electrode, which is conducive to circulation, but it is easy to oxidize and produce gas at the positive electrode interface.
  • Nitrile substances can form a protective film at the positive electrode interface to isolate the electrolyte and the positive electrode active material, but the compatibility of the negative electrode active material is not very good, which has a certain impact on the cycle performance.
  • the influence of the above parameters on battery performance is multifaceted, intertwined and difficult to quantify.
  • (2D 1 /D v 90 + D v 50) / (W 0 + W 1 ) can reflect the comprehensive influence of the negative electrode plate and the electrolyte on the battery's cycle performance, furnace temperature performance, lithium precipitation, etc.
  • Controlling (2D 1 /D v 90 + D v 50) / (W 0 + W 1 ) in the range of 0.5-3 can better balance the battery's cycle performance, as well as safety performance such as furnace temperature and lithium precipitation, so as to improve the battery's comprehensive performance.
  • the above-mentioned D v 90 and D v 50 of the negative electrode active material can be tested by the following method: the negative electrode plate disassembled from the battery is soaked in dimethyl carbonate (DMC) for 1 hour, then taken out, and rinsed with DMC twice to remove the electrolyte remaining on the surface of the plate, and naturally air-dried.
  • the air-dried plate is immersed in deionized water until the negative electrode material is separated from the current collector, and then placed in an oven at a temperature of 100°C to dry to remove moisture.
  • the dried negative electrode material is heat-treated at 800°C for 6 hours in a tubular furnace under helium protection to remove the binder and thickener in the negative electrode material to obtain the negative electrode active material.
  • the obtained negative electrode active material is subjected to a particle size distribution test based on the laser diffraction method.
  • the above-mentioned D v 90 and D v 50 can be obtained from the obtained particle size distribution diagram.
  • the test method can refer to GB/T 19077-2016/ISO 13320:2009 particle size distribution laser diffraction method.
  • the instrument used to test D v 90 and D v 50 is generally a laser particle size analyzer (such as Malvern 3000 laser particle size analyzer).
  • the particle size D v 50 corresponding to the volume cumulative distribution percentage of the negative electrode active material reaches 50% can also be called the "median particle size" of the material.
  • the above W 0 and W 1 can be obtained by analyzing the components of the electrolyte, and the above D 1 can be obtained by directly or indirectly measuring the thickness of the negative electrode active material layer, which refers to the thickness of the single-sided negative electrode active material layer.
  • the parameter k is in the range of 1.0-2.0.
  • the lithium battery can better balance the cycle performance, furnace temperature performance, etc., so as to have better comprehensive performance.
  • the fluorinated carbonate includes a fluorinated cyclic carbonate, wherein the fluorinated cyclic carbonate may specifically include one or more of fluorinated ethylene carbonate, 4,5-difluoroethylene carbonate, 4,4,5,5-tetrafluoroethylene carbonate, and 4-trifluoromethylethylene carbonate.
  • W 0 has a value range of: 2 ⁇ W 0 ⁇ 16.
  • the mass content of the fluorocarbonate is 2%-16%.
  • the mass content may be 2.1%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5.5%, 6%, 8%, 9%, 11%, 12%, 14%, 15% or 15.5%, etc., that is, W 0 may be 2.1, 2.5, 3, 3.5, 4, 4.5, 5.5, 6, 8, 9, 11, 12, 14, 15 or 15.5, etc.
  • the above parameter k is in the preferred range of 1-2, which is conducive to the battery having a lower cell expansion rate and better furnace temperature test results while ensuring that the battery has a higher cycle capacity retention rate.
  • the battery can take into account both a lower cell expansion rate and a better furnace temperature test result.
  • the content W0 of the fluorocarbonate in the electrolyte is controlled within a suitable range, which is conducive to forming a stable SEI film on the surface of the negative electrode, ensuring the long cycle capacity of the battery, and avoiding the unstable SEI film from causing the furnace temperature performance of the battery to fail easily; it can also reduce the oxidation and decomposition of the fluorocarbonate at the positive electrode to produce gas, avoid obvious expansion of the battery core thickness, and ensure good furnace temperature performance of the battery.
  • the value range of W0 is 5 ⁇ W0 ⁇ 10 . When W0 is within this range, the lithium battery can minimize battery bloating while taking into account the long cycle performance.
  • the nitrile substance includes one or more of succinonitrile, adiponitrile, glutaronitrile, butene dinitrile, 1,4-dicyano-2-butene, 3,3'-oxydipropionitrile, ethylene glycol diethyl cyanide, 1,2,3-tris(2-cyanoxy)propane, 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile and 1,3,6-hexanetricarbonitrile and 1,2,3-tris(2-cyanoxy)propane.
  • the value range of W 1 is: 2 ⁇ W 1 ⁇ 10. That is, based on the total mass of the electrolyte, the mass content of the nitrile substance is 2%-10%. Specifically, the mass content can be 2%, 2.5%, 3%, 3.3%, 4%, 4.6%, 5%, 5.5%, 6%, 7%, 8%, 9%, 10%, etc.
  • the content W1 of nitrile substances in the electrolyte is controlled within an appropriate range, which can not only fully protect the positive electrode interface, prevent the electrolyte from being easily oxidized and decomposed to produce gas, and make the furnace temperature performance and cycle performance of the battery better; it can also ensure that the viscosity of the electrolyte is appropriate, the lithium ion transfer rate is appropriate, and the battery impedance will not increase significantly.
  • the negative electrode is not easy to precipitate lithium during a long cycle, the battery capacity retention rate is high, and the thickness of the battery cell does not increase significantly.
  • the ratio of W0 to W1 satisfies: 0.5 ⁇ W0 / W1 ⁇ 4 . That is, the mass ratio of fluorocarbonate to nitrile is in the range of 0.5-4. This can ensure that a stable and uniform SEI film can be formed on the surface of the negative electrode during the cycle, and the positive electrode interface can be effectively protected, so that the battery can take into account good cycle performance, furnace temperature performance, and no obvious expansion of the battery core.
  • W0 / W1 can be 0.8, 1.0, 1.2, 1.5, 1.6, 1.7, 1.8, 2.0, 2.2, 2.3, 2.5, 2.6, 2.8, 3.0, 3.5, etc. In some embodiments, W0 / W1 is in the range of 1.5-3.0, at which time, the lithium battery can better take into account long cycle performance and good furnace temperature performance. Further, W0 / W1 is in the range of 1.5-2.5.
  • the electrolyte of the lithium battery in the present application includes a lithium salt, an organic solvent and an additive.
  • the additive contains at least the above-mentioned fluorocarbonate and nitrile substances.
  • the organic solvent includes a carboxylic acid ester substance.
  • the carboxylic acid ester substance is generally a linear ester, which is conducive to reducing the viscosity of the electrolyte, ensuring its good fluidity, and ensuring the wettability of the electrolyte to the electrode and the diaphragm and the low-temperature discharge performance of the battery.
  • the carboxylic acid ester substance includes one or more of ethyl acetate, propyl acetate, ethyl propionate, propyl propionate (PP), butyl propionate, pentyl propionate, ethyl halogenate, ethyl halogenate, propyl halogenate, butyl halogenate and pentyl halogenate.
  • the organic solvent also includes cyclic carbonate. That is, the organic solvent at this time includes carboxylic acid esters and cyclic carbonates. Cyclic carbonates help to increase the dissociation of lithium salts in the electrolyte and ensure the good ionic conductivity of the electrolyte; the presence of carboxylic acid esters is conducive to reducing the viscosity of the electrolyte, improving the wetting performance of the electrolyte, and is conducive to the formation of a uniform and stable SEI film. It is also conducive to the improvement of ionic conductivity, which can improve the rate performance and cycle performance of the battery.
  • the cyclic carbonate can include at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, halogenated ethylene carbonate, halogenated propylene carbonate, etc.
  • the organic solvent further includes linear carbonates. That is, the organic solvent at this time includes carboxylic acid esters, cyclic carbonates, and linear carbonates.
  • the presence of linear carbonates can further reduce the viscosity of the electrolyte and ensure its wettability to the electrode and the diaphragm.
  • the linear carbonates can include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), At least one of ethyl propyl ester, dimethyl halogenated carbonate, ethyl methyl halogenated carbonate, diethyl halogenated carbonate, etc.
  • the lithium battery can take into account good electrolyte wettability and kinetic properties, and is more conducive to the formation of a uniform SEI film of fluorocarbonate on the surface of the negative electrode active material, which is conducive to the battery having a lower cell expansion rate and better capacity retention rate.
  • W 2 /W 0 can be 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.5, 4.0, 5.0, 6.0, 6.5, 7.0, 7.5 or 7.9, etc. Further, in some embodiments, W 2 /W 0 is in the range of 3.0-7.0.
  • the additives in the electrolyte may include one or more of 1,3-propane sultone (PS), vinylene carbonate (VC), vinyl carbonate (VEC), etc. in addition to the above-mentioned fluorocarbonate and nitrile substances.
  • PS 1,3-propane sultone
  • VC vinylene carbonate
  • VEC vinyl carbonate
  • 1,3-propane sultone is particularly helpful in improving the high temperature resistance of lithium batteries, such as furnace temperature performance.
  • the above-mentioned lithium salts include one or more of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium hexafluorosilicate (Li 2 SiF 6 ), lithium hexafluoroantimonate (LiSbF 6 ), lithium perchlorate (LiClO 4 ), lithium bis(oxalatoborate) (abbreviated as LiBOB), lithium difluorooxalatoborate (abbreviated as LiDFOB), lithium bis(fluorosulfonyl)imide (abbreviated as LiFSI, with a molecular formula of LiN(SO 2 F) 2 ), lithium bis(trifluoromethylsulfonyl)imide (abbreviated as LiTFSI, with a molecular formula of LiN(SO 2 CF 3 ) 2
  • the mass percentage of lithium salt in the electrolyte can be 12%-18%. In this case, it can be ensured that the transmission resistance of lithium ions in the electrolyte is not too large to make the battery rate performance poor, and the viscosity of the electrolyte is not too large to effectively infiltrate the positive/negative electrodes and affect the battery performance.
  • the value range of the above D 1 is: 30 ⁇ D 1 ⁇ 90. That is, the thickness of the negative electrode active material layer is in the range of 30 ⁇ m-90 ⁇ m. It should be noted that, regardless of whether the negative electrode active material layer is provided on one side or both sides of the negative electrode sheet, D 1 here refers to the thickness of the single-sided negative electrode active material layer. At this time, the thickness of the negative electrode active material layer is appropriate, which is conducive to the battery having good room temperature cycle performance and furnace temperature performance.
  • the negative electrode active material layer of appropriate thickness can facilitate the electrolyte to infiltrate it, and facilitate the formation of a uniform and stable SEI film on the surface of the negative electrode active material, thereby reducing the impedance of lithium ion transmission at the negative electrode, and making it easier for the battery to pass the furnace temperature test; the negative electrode active material layer of appropriate thickness can also avoid the incomplete SEI film causing the electrolyte to be continuously reduced during the battery cycle, resulting in the thickening of the negative electrode SEI film and the consumption of active lithium, which is conducive to the battery maintaining a high capacity retention rate.
  • the negative electrode active material layer of appropriate thickness can also ensure that the load amount of the negative electrode active material in the battery is appropriate, and ensure the high energy density of the battery.
  • the above D1 is in the range of 40-80.
  • the particle size of the negative electrode active material satisfies: 8 ⁇ D v 50 ⁇ D v 90 ⁇ 40.
  • the particle size D v 50 of the negative electrode active material can reflect the overall particle distribution.
  • the appropriate particle size D v 50 can ensure that the specific surface area of the negative electrode active material is appropriate, and then the consumption of the electrolyte, especially the consumption of the fluorocarbonate, during the battery cycle will not be too fast, and the negative electrode side reaction will not be too intense, so that the battery can have a high capacity retention rate during a long cycle.
  • the appropriate particle size D v 50 of the negative electrode active material is also conducive to the negative electrode active material layer having a suitable porosity, reducing the resistance of ion liquid phase diffusion and migration, and ultimately facilitating the battery's rate performance and cycle performance.
  • 8 ⁇ D v 50 ⁇ 36 for example, specifically 8, 10, 12, 14, 16, 18, 20, 21, 23, 25, 27, 30, 32, 34, 35, etc.
  • D v 50 is in the range of 8-30, preferably in the range of 8-20.
  • the particle size D v 90 of the negative electrode active material can reflect the situation of its large particle size. Controlling D v 90 not more than 40 ⁇ m can make the processing difficulty of the negative electrode plate lower, the flatness of the negative electrode active material layer good, the negative electrode active material is not easy to be crushed to produce more active fracture surfaces, and the consumption of electrolyte and fluorocarbonate during the formation and circulation process is less, thereby ensuring good cycle performance of the battery.
  • D v 90 is within the range of 10-40, and can be further In the range of 12-40, preferably in the range of 15-35. Generally, the above D 1 is greater than or equal to 1 times of D v 90. This can help ensure that the negative electrode active material is not crushed during the rolling process of the negative electrode sheet, thereby reducing the stability of the negative electrode sheet, deteriorating the cycle performance of the battery, and increasing the expansion of the battery cell.
  • the negative electrode active material may include, but is not limited to, one or more of carbon materials, silicon-based materials, tin-based materials, and lithium titanate.
  • the carbon material includes one or more of soft carbon, hard carbon, carbon fiber, graphitized carbon microspheres, artificial graphite, and natural graphite.
  • Silicon-based materials may include one or more of elemental silicon, silicon alloys, silicon oxides, silicon-carbon composite materials, silicon carbide, etc.
  • Tin-based materials may include one or more of elemental tin, tin oxides, tin-based alloys, tin-carbon compounds, etc.
  • the negative electrode active material includes multiple materials (for example, graphite and elemental silicon are included at the same time), the above-mentioned D v 90 and D v 50 refer to the relevant particle size values of the mixed negative electrode active materials.
  • the negative electrode active material layer also includes a binder.
  • the negative electrode active material layer may further include a conductive agent.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyacrylate (such as polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, etc.), polyolefin (such as polypropylene, polyethylene, etc.), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), sodium alginate, etc.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVA polyvinyl alcohol
  • PAN polyacrylonitrile
  • PI polyimide
  • PAA
  • the first conductive agent and the second conductive agent may be independently selected from one or more of conductive carbon black (such as acetylene black, Ketjen black, Supper P, 350G carbon black, etc.), furnace black, carbon fiber, carbon nanotubes, graphene, etc., but not limited to this.
  • the current collector carrying the negative electrode active material (specifically the negative electrode current collector) may include but is not limited to copper foil, stainless steel foil, copper alloy foil, carbon-coated copper foil or copper-plated film, etc.
  • the above-mentioned negative electrode sheet can be obtained by coating a negative electrode slurry containing a negative electrode active material, a binder and an optional conductive agent on a current collector, drying and rolling.
  • the current collector can be coated on one side or on both sides.
  • the negative electrode active material layer can be on one side of the current collector, or on both sides of the negative current collector.
  • the thickness D 1 ⁇ m of the above-mentioned negative electrode active material layer refers to the thickness of the negative electrode active material layer on one side.
  • the thickness of the negative electrode active material layer on both sides of the negative current collector can be the same or different, and the negative electrode active material layer on each side of the negative current collector satisfies the parameter k in the above-mentioned range.
  • the above-mentioned lithium battery specifically includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator located between the positive electrode sheet and the negative electrode sheet.
  • the positive electrode active material in the positive electrode sheet is a material that can reversibly release and embed lithium ions.
  • the positive electrode active material may include but is not limited to lithium monooxide (such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, etc.), lithium binary oxide (such as lithium nickel manganese oxide, lithium nickel cobalt oxide, lithium cobalt manganese oxide, etc.), lithium ternary oxide (such as lithium nickel cobalt manganese oxide ternary material, lithium nickel cobalt aluminum oxide ternary material, etc.) or lithium multi-electron oxide, lithium-containing phosphate (such as lithium iron phosphate, lithium manganese iron phosphate) and the like one or more.
  • the separator can use any separator material in the existing battery.
  • the separator can include but is not limited to single-layer PP (polypropylene) film, single-layer PE (polyethylene) film, double-layer film PP/PE, double-layer film PP/PP and three-layer PP/PE/PP and other polymer separators, or non-woven fabrics, etc.
  • single-layer PP polypropylene
  • PE polyethylene
  • double-layer film PP/PE double-layer film PP/PP
  • three-layer PP/PE/PP and other polymer separators or non-woven fabrics, etc.
  • the present application also provides an electric device.
  • the electric device 1 includes the lithium battery 10 described above in the present application.
  • the electrical equipment includes, but is not limited to, mobile phones, laptop computers, tablet computers, pen-input computers, portable fax machines, portable copiers, portable printers, transceivers, video recorders, cameras, televisions, radios, portable recorders, portable CD players, mini-discs, e-book players, electronic notepads, wearable devices (such as smart watches, smart bracelets, head-mounted stereo headphones, Bluetooth headphones), portable cleaners, calculators, memory cards, backup power supplies, cars, motorcycles, bicycles (such as power-assisted bicycles), lighting fixtures (such as flashlights), toys, game consoles, clocks, power tools, large household batteries, lithium-ion capacitors, etc.
  • the electrical equipment includes, but is not limited to, mobile phones, laptop computers, tablet computers, pen-input computers, portable fax machines, portable copiers, portable printers, transceivers, video recorders, cameras, televisions, radios, portable recorders, portable CD players, mini-discs, e-book players, electronic notepads, wearable devices (such
  • the battery of the electrical equipment Due to the adoption of the lithium battery, the battery of the electrical equipment has a strong endurance, good cycle performance and high safety.
  • a method for preparing a lithium ion battery comprising:
  • the positive electrode active material (specifically lithium cobalt oxide ( LiCoO2 )), the conductive agent (specifically carbon nanotubes (CNT)), and the binder (specifically polyvinylidene fluoride) are mixed in a mass ratio of 95:2:3, the mixed powder is placed in a vacuum mixer, a solvent - N-methylpyrrolidone (NMP) is added, and the mixture is stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is then coated on a positive electrode current collector aluminum foil, dried at 85°C, cold rolled, cut and slit, and then dried under vacuum conditions at 85°C for 4 hours to obtain a positive electrode sheet.
  • NMP solvent - N-methylpyrrolidone
  • the negative electrode active material (specifically graphite, whose particle size and size parameters are shown in Table 1) and the binder (specifically styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na), the mass ratio is 2:3) are mixed in ionized water at a mass ratio of 95:5, and stirred evenly in a vacuum mixer to obtain a negative electrode slurry; then the negative electrode slurry is coated on the opposite sides of the negative electrode current collector copper foil, and dried, cold rolled, and cut to obtain a negative electrode sheet.
  • the negative electrode sheet includes a copper foil and a negative electrode active material layer disposed on the opposite sides of the copper foil, and the thickness of each negative electrode active material layer is also summarized in Table 1.
  • the positive electrode sheet, polyethylene (PE) separator, and negative electrode sheet are stacked in order to obtain a battery cell; the stacked battery cell is then wound and placed in an aluminum-plastic film outer packaging foil, and then the prepared electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, the preparation of the lithium battery is completed.
  • the calculation results of the above-mentioned performance factor k of the obtained lithium battery are also summarized in Table 1.
  • lithium batteries of other examples and comparative examples were prepared according to the parameters listed in Table 1.
  • Table 1 Lithium battery parameters of each embodiment and comparative example Note: In Table 1 above, EC represents cyclic carbonate solvent ethylene carbonate, PC represents cyclic carbonate solvent propylene carbonate, DEC represents linear carbonate solvent diethyl carbonate, and PP represents carboxylic acid ester solvent propyl propionate. PS represents the additive 1,3-propane sultone.
  • W0 specifically represents the mass proportion of fluoroethylene carbonate in the electrolyte
  • W1 specifically represents the total mass proportion of 1,3,6-hexanetrinitrile and succinonitrile in the electrolyte
  • W0 specifically represents the mass proportion of fluoroethylene carbonate in the electrolyte
  • W represents the mass proportion of 4,5-difluoroethylene carbonate in the electrolyte
  • W0 specifically represents the mass proportion of 4,4,5,5-tetrafluoroethylene carbonate in the electrolyte.
  • W1 represents the total mass proportion of 1,3,6-hexanetrinitrile and succinonitrile in the electrolyte.
  • W0 specifically represents the mass proportion of fluoroethylene carbonate in the electrolyte.
  • W1 in Example 29 represents the total mass proportion of 1,3,6-hexanetrinitrile and adiponitrile in the electrolyte.
  • W1 in Example 30 represents the mass proportion of succinonitrile in the electrolyte.
  • W1 in Example 31 specifically represents the mass proportion of adiponitrile in the electrolyte.
  • Table 2 Summary of performance test results of lithium batteries in various embodiments and comparative examples Note: In Table 2, “/” means that the cycle life of the lithium battery does not reach 1000 times.
  • the performance factor k When the ratio of (2D 1 /D v 90+D v 50)/(W 0 +W 1 ) (i.e., the performance factor k) is less than 0.5 or greater than 3 (Comparative Examples 1-3), the long cycle performance and furnace temperature performance of the lithium battery are poor, which is significantly inferior to Example 4 with the same characteristic parameters of its negative electrode plate and the same organic solvent composition. In addition, when the electrolyte of the lithium battery does not contain fluorinated carbonate or nitrile additives, the performance of the battery is poor. Even if the above parameter k can be in the range of 0.5-3 (Comparative Example 5), the cycle life of the lithium battery is very poor, such as the number of cycles is difficult to reach 1000 times, and the pass rate of the furnace temperature test is as low as 0.
  • the thickness D1 of the negative electrode active material layer, the particle size parameters of the negative electrode active material, the organic solvent of the electrolyte, and the additive PS are the same, but the content W0 of the fluorinated carbonate and the content W1 of the nitrile substance are different. From the comparison of Examples 18-23, it can be seen that under the same conditions, when the content W0 of the fluorinated carbonate in the system is in the range of 2-16, the cycle performance of the battery is well balanced, especially the expansion resistance is good. In particular, when W0 is in the preferred range of 6-12, and W0 / W1 is in the more preferred range of 1.5-3.0, k can be in the more preferred range of 1-2, and the comprehensive performance of the battery is excellent.
  • the organic solvent of the comparative electrolyte is a pure carbonate system (such as Example 34 containing only EC, PC and DEC), and the introduction of carboxylic acid ester is conducive to improving the long cycle performance of the battery, that is, the cycle performance of Examples 4 and 33 is better than that of Example 34.
  • carboxylic acid ester solvent which is conducive to reducing the viscosity of the electrolyte, improving its wetting ability to the negative electrode, and forming a uniform and stable SEI film, which is conducive to improving the capacity retention rate and reducing the thickness expansion rate during the cycle.
  • Example 4 Furthermore, from the comparison of Example 4 and Example 32, it can be seen that when the additives in the electrolyte simultaneously contain fluorocarbonate and nitrile additives of the same composition, and the parameters of the organic solvent and the negative electrode plate are the same, the introduction of the additive 1,3-propane sultone (PS) can further improve the high temperature resistance of the battery.
  • PS 1,3-propane sultone

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Abstract

一种锂电池及用电设备。该锂电池包括正极极片、负极极片、隔膜、和电解液，负极极片包括集流体和设置在集流体表面的负极活性材料层，电解液包括锂盐、有机溶剂、和添加剂，添加剂包含氟代碳酸酯和腈类物质，其中，负极活性材料层的厚度为D1μm，负极活性材料层中含有的负极活性材料的体积累积分布百分数达到50％时对应的粒径为Dv50μm，以及负极活性材料层中含有的负极活性材料的体积累积分布百分数达到90％时对应的粒径为Dv90μm；基于电解液的总质量，氟代碳酸酯的质量含量为W0％，腈类物质的质量含量为W1％，锂电池的性能因子k＝(2D1/Dv90+Dv50)/(W0+W1)，且k在0.5-3的范围内。

Description

锂电池及用电设备
本申请要求于2022年9月26日提交中国专利局、申请号为202211169554.5、申请名称为“锂电池及用电设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池技术领域，具体涉及一种锂电池及用电设备。
背景技术
锂离子电池(又称“锂电池”)因具有电压高、寿命长、无记忆效应等特点而广泛应用于移动电子设备、电动汽车、无人机等领域。随着使用锂离子电池供电的产品的不断发展，人们对锂离子电池的能量密度、循环性能、和安全性能提出了更高要求。
在锂离子电池的充电和放电过程中，负极活性材料不断地进行嵌锂和脱锂，这使得负极活性材料表面的固态电解质膜(solid electrolyte interface，SEI)会持续地破裂并产生新的界面，导致负极活性材料直接接触电解液从而引发副反应，造成活性锂的损失，进而降低了电池的能量密度和循环寿命。另外，负极表面形成的SEI膜的稳定性也会直接影响锂离子电池的炉温测试稳定性，直接关系到锂离子电池的安全性能。
目前，还未有行之有效的技术方案可使电池切实兼顾良好的长循环能力和安全性能等。
发明内容
鉴于此，本申请提供了一种锂离子电池及用电设备，通过定义负极活性材料层的厚度、负极活性材料的粒径、及电解液之间的相对关系，可以保证锂离子电池具有较长的循环寿命及良好的130℃炉温性能。
第一方面，本申请提供了一种锂电池。所述锂电池包括正极极片、负极极片、隔膜、和电解液，所述负极极片包括集流体和设置在所述集流体至少一侧表面上的负极活性材料层，所述电解液包括锂盐、有机溶剂、和添加剂，所述添加剂包含氟代碳酸酯和腈类物质，其中，所述负极活性材料层的厚度为D1μm，所述负极活性材料层中含有的负极活性材料的体积累积分布百分数达到50％时对应的粒径为Dv50μm，以及所述负极活性材料层中含有的负极活性材料的体积累积分布百分数达到90％时对应的粒径为Dv90μm；基于所述电解液的总质量，所述氟代碳酸酯的质量含量为W0％，所述腈类物质的质量含量为W1％，所述锂电池的性能因子k满足以下关系式：k＝(2D1/Dv90+Dv50)/(W0+W1)，且0.5≤k≤3.0。
通过向电解液中同时添加氟代碳酸酯和腈类物质作添加剂，有助于在负极形成稳定且致密的SEI膜，及在正极形成耐氧化的保护膜以避免电解液在正极分解产气，依靠这2种添加剂的协同配合作用，并同时借助它们的含量与负极厚度、负极活性材料的粒径之间建立的定量联系，定义出电池性能因子k，并通过控制k在0.5-3的范围，可达到锂电池的循环性能、炉温性能等共同提升的目的。
在一些实施方式中，所述k取值范围为：1.0≤k≤2.0。
在一些实施方式中，所述W0的取值范围为：2≤W0≤16。
在一些实施方式中，所述W0的取值范围为：5≤W0≤10。
在一些实施方式中，所述W1的取值范围为：2≤W1≤10。
在一些实施方式中，所述W0与所述W1的比值满足：0.5≤W0/W1≤4。
在一些实施方式中，所述W0与所述W1的比值满足：1.5≤W0/W1≤3.0。
在一些实施方式中，所述D1的取值范围为：30≤D1≤90。
在一些实施方式中，所述D1的取值范围为：40≤D1≤80。
在一些实施方式中，所述负极活性材料的粒径满足：8≤Dv50＜Dv90≤40。
在一些实施方式中，所述D1与所述Dv90的比值大于或等于1。
在一些实施方式中，所述氟代碳酸酯包括氟代碳酸乙烯酯、4,5-二氟代碳酸乙烯酯、4,4,5,5-四氟代碳酸乙烯酯、4-三氟甲基碳酸乙烯酯中的至少一种；以及所述腈类物质包括丁二腈、己二腈、戊二腈、丁烯二腈、1,4-二氰基-2-丁烯、3,3’-氧二丙腈、乙二醇二乙氰醚、1,2,3-三(2-氰氧基)丙烷、1,3,5-戊三甲腈、1,2,3-丙三甲腈和1,3,6-己烷三腈中的至少一种。
在一些实施方式中，所述有机溶剂包括羧酸酯类物质，其中，所述羧酸酯类物质包括乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丙酸戊酯、卤代乙酸乙酯、卤代丙酸乙酯、卤代丙酸丙酯、卤代丙酸丁酯和卤代丙酸戊酯中的至少一种。
在一些实施方式中，所述有机溶剂还包括环状碳酸酯。
在一些实施方式中，所述有机溶剂还包括线性碳酸酯类物质。
在一些实施方式中，基于所述电解液的总质量，所述羧酸酯类物质的总质量含量为W2％，且W2/W0≥2。
在一些实施方式中，所述W2与所述W0的比值满足：2.5≤W2/W0≤8。
在一些实施方式中，所述添加剂还包含1,3-丙烷磺内酯、碳酸亚乙烯酯、乙烯基碳酸乙烯酯中的至少一种。
第二方面，本申请提供了一种用电设备。所述用电设备包括如本申请第一方面所述的锂电池。
由于采用了上述锂电池，该用电设备的电池的续航能力强，循环性能好，安全性高。
附图说明
图1是根据本申请实施例的锂电池的结构示意图。
图2是根据本申请实施例的用电设备的结构示意图。
附图标记说明：
1-用电设备，10-锂电池，110-正极极片，111-正极集流体，112-正极活性材料层，120-
负极极片，121-负极集流体，122-负极活性材料层，130-隔膜，140-电解液。
具体实施方式
下面对本申请实施例的技术方案进行详细说明。
本申请实施例提供了一种锂电池。如图1所示，锂电池10包括正极极片110、负极极片120、隔膜130、和电解液140，负极极片120包括负极集流体121和设置在负极集流体121至少一侧表面上的负极活性材料层122，电解液包括锂盐、有机溶剂、和添加剂，添加剂包含氟代碳酸酯和腈类物质，其中，负极活性材料层122的厚度为D1μm，负极活性材料层122中含有的负极活性材料的体积累积分布百分数达到50％时对应的粒径为Dv50μm，以及负极活性材料层122中含有的负极活性材料的体积累积分布百分数达到90％时对应的粒径为Dv90μm；基于电解液140的总质量，氟代碳酸酯的质量含量为W0％，腈类物质的质量含量为W1％，锂电池10的性能因子k满足以下关系式：
且k在0.5-3.0的范围内。
本申请一些实施方式中，如图1所示，正极极片110包括正极集流体111和设置在正极 集流体111至少一侧表面上的正极活性材料层112。
本申请中，通过向锂电池的电解液中同时添加氟代碳酸酯和腈类物质作添加剂，可以借助氟代碳酸酯与负极活性材料的高亲和力而在负极表面形成稳定且致密的SEI膜，避免SEI膜的不断破裂-重建，进而可减少电解液的分解和活性锂的消耗，提升电池的循环性能；但氟代碳酸酯在锂电池正极界面易被氧化产气，在引入腈类物质后，腈类物质可在正极界面络合形成保护膜，隔绝电解液和正极活性材料，减少正极金属离子的溶出，降低正极活性材料对电解液的氧化分解，提升电池的炉温性能。因此，本申请在将氟代碳酸酯和腈类物质这两类添加剂搭配使用，使二者功能相互补充的情况下，还将二者的含量与负极活性材料的颗粒尺寸、负极活性材料层的厚度建立联系，定义出电池性能因子k，并控制k在0.5-3的范围，可保证锂电池能较好地兼顾长循环寿命及良好的炉温性能等。
申请人经分析，推测其原因可能是：上述D1/Dv90可在一定程度上可反映负极极片在辊压过程中负极活性颗粒碎裂的程度。上述Dv50反映了负极活性材料颗粒的整体尺寸情况，例如可具体反映负极活性材料颗粒的表面活性位点的多少，及其在辊压过程中的颗粒碎裂程度等。而负极活性颗粒的破裂会产生较多活性界面，导致在化成及循环过程中对电解液的消耗量变大，并使负极活性材料损失容量、在充电过程中负极表面易析锂。上述氟代碳酸酯可在负极形成稳定SEI膜，利于循环，但其在正极界面易氧化产气，腈类物质可在正极界面形成保护膜，隔绝电解液和正极活性材料，但其负极活性材料的兼容性不是很好，对循环性能有一定影响。上述各参数对电池性能的影响是多方面的、交错，且较难量化的，但本申请人通过一系列研究，发现(2D1/Dv90+Dv50)/(W0+W1)可反映负极极片和电解液对电池的循环性能、炉温性能、析锂等的综合影响，控制(2D1/Dv90+Dv50)/(W0+W1)在0.5-3的范围，能较好地平衡电池的循环性能，以及炉温、析锂等安全性能，以提升电池的综合性能。
本申请中，负极活性材料的上述Dv90、Dv50可以通过以下方法测试得到：将从电池上拆解下来的负极极片用碳酸二甲酯(DMC)浸泡1h后取出，并用DMC冲洗2次，去除极片表面残留的电解液，并自然风干。将风干后的极片浸入去离子水中至负极料脱离集流体，然后置于烤箱中于温度100℃下烘干以除去水分。接着将干燥后的负极料在氦气保护下的管式炉中，于800℃下热处理6h，除去负极料中的粘结剂和增稠剂，得到负极活性材料。最后对得到的负极活性材料进行基于激光衍射法的粒度分布测试，从得到的粒度分布图可获知上述Dv90、Dv50，测试方法可参见GB/T 19077-2016/ISO 13320:2009粒度分布激光衍射法。测试Dv90、Dv50所用的仪器一般是激光粒度仪(如马尔文3000型号的激光粒度仪)。其中，负极活性材料的体积累积分布百分数达到50％时对应的粒径Dv50又可称为该材料的“中值粒径”。此外，上述W0、W1可通过对电解液的成分进行成分分析获知，上述D1可通过对负极活性材料层的厚度进行直接测量或间接测量获知，其是指单面负极活性材料层的厚度。
本申请一些实施方式中，上述参数k在1.0-2.0的范围内。此时，上述锂电池能更好地平衡循环性能、炉温性能等，以具有更优的综合性能。
本申请实施方式中，氟代碳酸酯包括氟代环状碳酸酯。其中，氟代环状碳酸酯可具体包括氟代碳酸乙烯酯、4,5-二氟代碳酸乙烯酯、4,4,5,5-四氟代碳酸乙烯酯、4-三氟甲基碳酸乙烯酯中的一种或多种。
本申请一些实施方式中，W0的取值范围为：2≤W0≤16。换句话说，基于电解液的总质量，氟代碳酸酯的质量含量为2％-16％。具体地，该质量含量可以是2.1％、2.5％、3％、3.5％、4％、4.5％、5.5％、6％、8％、9％、11％、12％、14％、15％或15.5％等，即，W0具体可为2.1、2.5、3、3.5、4、4.5、5.5、6、8、9、11、12、14、15或15.5等。在一些实施例中，6≤W0≤12。此 时，可利于上述参数k在优选范围1-2内，在保证电池具有较高循环容量保持率的情况下，较利于电池具有较低的电芯膨胀率及较好的炉温测试结果。在另一些实施例中，8≤W0≤10，电池能兼顾更低的电芯膨胀率及更优异的炉温测试结果。
其中，氟代碳酸酯在电解液中的含量W0控制在合适的范围，既有利于在负极表面形成稳定的SEI膜，保证电池的长循环能力，以及避免不稳定的SEI膜使电池的炉温性能易失效；又可以降低氟代碳酸酯在正极被氧化分解产气、避免电芯厚度膨胀明显，保证电池的良好炉温性能。在一些实施方式中，W0的取值范围是5≤W0≤10。当W0在该范围内时，锂电池可在兼顾长循环性能的同时，尽可能减少电池胀气现象。
本申请实施方式中，腈类物质包括丁二腈、己二腈、戊二腈、丁烯二腈、1,4-二氰基-2-丁烯、3,3’-氧二丙腈、乙二醇二乙氰醚、1,2,3-三(2-氰氧基)丙烷、1,3,5-戊三甲腈、1,2,3-丙三甲腈和1,3,6-己烷三腈和1,2,3-三(2-氰氧基)丙烷中的一种或多种。
本申请一些实施方式中，W1的取值范围为：2≤W1≤10。即，基于电解液的总质量，腈类物质的质量含量为2％-10％。具体地，该质量含量可以是2％、2.5％、3％、3.3％、4％、4.6％、5％、5.5％、6％、7％、8％、9％、10％等。
其中，腈类物质在电解液中的含量W1控制在合适的范围，既可以使正极界面得到充分保护、电解液不易氧化分解产气，使电池的炉温性能及循环性能较好；又可以保证电解液的粘度合适、锂离子传输速率合适，且电池阻抗不会明显增加，长循环过程中负极不易析锂，电池容量保持率较高，电芯厚度增加不明显等。
本申请一些实施方式中，W0与W1的比值满足：0.5≤W0/W1≤4。即，氟代碳酸酯与腈类物质的质量之比在0.5-4的范围内。这样既能保证在循环过程中，负极表面可形成稳定均匀的SEI膜，又可保证正极界面得到有效保护，从而使电池兼顾良好的循环性能、炉温性能、电芯膨胀不明显等。具体地，W0/W1可以是0.8、1.0、1.2、1.5、1.6、1.7、1.8、2.0、2.2、2.3、2.5、2.6、2.8、3.0、3.5等。在一些实施方式中，W0/W1在1.5-3.0的范围内，此时，锂电池能更好地兼顾长循环性能和良好炉温性能。进一步地，W0/W1在1.5-2.5的范围内。
本申请中锂电池的电解液包括锂盐、有机溶剂和添加剂。其中，添加剂至少包含上述氟代碳酸酯和腈类物质。本申请一些实施方式中，有机溶剂包括羧酸酯类物质。其中，羧酸酯类物质一般是线性酯，其利于降低电解液的粘度，保证其良好流动性，及保证电解液对极片、隔膜的浸润性和电池的低温放电性能。其中，羧酸酯类物质包括乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸丙酯(PP)、丙酸丁酯、丙酸戊酯、卤代乙酸乙酯、卤代丙酸乙酯、卤代丙酸丙酯、卤代丙酸丁酯和卤代丙酸戊酯中的一种或多种。
本申请一些实施方式中，有机溶剂还包括环状碳酸酯。即，此时的有机溶剂包括羧酸酯类物质及环状碳酸酯。环状碳酸酯有助于增加锂盐在电解液中的解离，保证电解液的良好离子电导率；羧酸酯类物质的存在利于电解液粘度的降低，提升电解液的浸润性能，利于形成均匀稳定的SEI膜，还利于离子电导率的提高，可提升电池的倍率性能及循环性能，二者的配合更利于电解液保持较低的粘度及锂盐在其中的溶解性。其中，环状碳酸酯可以包括碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸丁烯酯、卤代碳酸乙烯酯、卤代碳酸丙烯酯等中的至少一种。
在一些实施方式中，有机溶剂还包括线性碳酸酯类物质。即，此时的有机溶剂包括羧酸酯类物质、环状碳酸酯线性碳酸酯类物质。线性碳酸酯类物质的存在可进一步降低电解液的粘度，保证其对极片、隔膜的浸润性。其中，线性碳酸酯类物质可以包括碳酸二甲酯(DMC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸 乙丙酯、卤代碳酸二甲酯、卤代碳酸甲乙酯、卤袋碳酸二乙酯等中的至少一种。
本申请实施方式中，基于电解液的总质量，羧酸酯类物质的总质量含量为W2％，则W2/W0≥2。这利于电池在循环过程中膨胀率的降低。在一些实施方式中，2.5≤W2/W0≤8。此时，锂电池能兼顾良好的电解液浸润性和动力学性能，更有利于氟代碳酸酯在负极活性材料表面形成均匀的SEI膜，利于电池具有较低的电芯膨胀率及较好的容量保持率等。具体地，W2/W0可以为2.6、2.7、2.8、2.9、3.0、3.1、3.2、3.5、4.0、5.0、6.0、6.5、7.0、7.5或7.9等。进一步地，在一些实施例中，W2/W0在3.0-7.0的范围内。
本申请一些实施方式中，电解液中的添加剂除了包含上述氟代碳酸酯和腈类物质外，还可以包括1,3-丙烷磺内酯(PS)、碳酸亚乙烯酯(VC)、乙烯基碳酸乙烯酯(VEC)等中的一种或多种。这些助剂也有助于电池循环过程中稳定SEI膜的形成。特别地，1,3-丙烷磺内酯特别有助于提升锂电池的耐高温性能，如炉温性能。
上述锂盐包括六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、六氟砷酸锂(LiAsF6)、六氟硅酸锂(Li2SiF6)、六氟锑酸锂(LiSbF6)、高氯酸锂(LiClO4)、二草酸硼酸锂(简写为LiBOB)、二氟草酸硼酸锂(简写为LiDFOB)、双氟磺酰亚胺锂(简写为LiFSI，分子式为LiN(SO2F)2)，双(三氟甲基磺酰)亚胺锂(简写为LiTFSI，分子式为LiN(SO2CF3)2)、二(全氟乙基磺酰)亚胺锂(LiN(C2F5SO2)2)、三氟甲基磺酸锂(LiCF3SO3)、全氟丁基磺酸锂(LiC4F9SO3)等中的一种或多种。
可选地，锂盐在电解液中的质量百分含量可以是12％-18％。此时，可以保证锂离子在电解液中的传输阻力不会过大而使电池的倍率性能较差，及保证电解液的粘度不会过大而不能有效地浸润正/负极，影响电池性能发挥。
本申请一些实施方式中，上述D1的取值范围为：30≤D1≤90。即，负极活性材料层的厚度在30μm-90μm的范围内。需要说明的是，无论负极极片上是一面还是两面设有负极活性材料层，这里的D1是指单面负极活性材料层的厚度。此时，负极活性材料层的厚度合适，利于电池具有良好的常温循环性能和炉温性能。具体地，合适厚度的负极活性材料层可利于电解液将其浸润，利于负极活性材料表面形成均匀且稳定的SEI膜，进而降低锂离子在负极传递的阻抗，以及使电池较易通过炉温测试；合适厚度的负极活性材料层还可避免不完整的SEI膜使电解液在电池循环过程中不断被还原而导致负极SEI膜增厚、消耗活性锂，利于电池保持较高的容量保持率。此外，合适厚度的负极活性材料层还可保证电池中负极活性材料的负载量合适，保证电池的较高能量密度。在一些实施方式中，上述D1在取值范围为40-80。
本申请一些实施方式中，负极活性材料的粒径满足：8≤Dv50＜Dv90≤40。其中，负极活性材料的粒径Dv50可体现整体颗粒分布情况，合适的粒径Dv50可保证负极活性材料比表面积合适，进而在电池循环过程中对电解液的消耗，特别是对氟代碳酸酯的消耗不会过快，负极副反应不会太剧烈，从而可使电池在长循环过程中容量保持率较高。此外，负极活性材料的合适粒径Dv50还利于负极活性材料层具有合适的孔隙率，降低离子液相扩散与迁移的阻力，最终利于电池的倍率性能与循环性能发挥。在一些实施方式中，8≤Dv50＜36，例如具体为8、10、12、14、16、18、20、21、23、25、27、30、32、34、35等。在一些实施例中，Dv50在8-30的范围内，优选在8-20的范围内。
其中，负极活性材料的粒径Dv90可反映其大粒径颗粒的情况，控制Dv90不超过40μm，可使负极极片的加工难度较低、负极活性材料层的平整度良好，负极活性材料不易被压碎而产生较多的活性断裂面，在化成及循环过程中对电解液的消耗量、对氟代碳酸酯的消耗较少等，保证电池的循环性能良好。在一些实施方式中，Dv90在10-40的范围内，进一步可以在 12-40的范围内，优选在15-35的范围内。一般地，上述D1大于或等于Dv90的1倍。这样可利于保证在负极极片的辊压过程中，负极活性材料不被压碎，而减低负极极片的稳定性，劣化电池的循环性能、增大电芯膨胀等。
本申请实施方式中，负极活性材料可以包括但不限于碳材料、硅基材料、锡基材料、钛酸锂中的一种或多种。其中，碳材料包括软碳、硬碳、碳纤维、石墨化碳微球、人造石墨、天然石墨中的一种或多种。硅基材料可以包括单质硅、硅合金、硅氧化物、硅碳复合材料、碳化硅等中的一种或多种。锡基材料可以包括单质锡、锡氧化物、锡基合金、锡碳化合物等中的一种或多种。其中，当负极活性材料包括多种材料时(例如同时包括石墨和单质硅)，上述Dv90、Dv50是指混合后的负极活性材料的相关粒度值。
本申请实施方式中，负极活性材料层还包括粘结剂。在一些情况下，负极活性材料层还可以进一步包括导电剂。其中，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇(PVA)、聚丙烯腈(PAN)、聚酰亚胺(PI)、聚丙烯酸(PAA)、聚丙烯腈(PAN)、聚丙烯酸酯(如聚甲基丙烯酸甲酯、聚丙烯酸甲酯、聚丙烯酸乙酯等)、聚烯烃(如聚丙烯、聚乙烯等)、丁苯橡胶(SBR)、羧甲基纤维素(CMC)、羧甲基纤维素钠(CMC-Na)、海藻酸钠等的一种或多种，但不限于此。第一导电剂、第二导电剂可以各自独立地选自导电炭黑(如乙炔黑、科琴黑、Supper P、350G炭黑等)、炉黑、碳纤维、碳纳米管、石墨烯等中的一种或多种，但不限于此。承载负极活性材料的集流体(具体是负极集流体)可以包括但不仅限于铜箔、不锈钢箔、铜合金箔、涂炭铜箔或镀铜膜等。
上述负极极片可以通过将含负极活性材料、粘结剂及可选的导电剂的负极浆料涂覆在集流体上，经干燥、辊压获得。其中，集流体上可以是单面涂布，或者双面涂布。换句话说，可以是集流体的一侧表面具有负极活性材料层，也可以是负极集流体的相对两侧表面上均具有负极活性材料层。当负极集流体是双面涂布时，上述负极活性材料层的厚度D1μm是指单侧负极活性材料层的厚度，此时负极集流体两侧的负极活性材料层的厚度可以相同或者不同，负极集流体每一侧表面上的负极活性材料层均满足参数k在前述范围。
本申请中，上述锂电池具体包括正极极片、负极极片、电解液以及位于正极极片与负极极片之间的隔膜。其中，正极极片中的正极活性材料为能够可逆脱出和嵌入锂离子的材料。对锂电池来说，其正极活性材料可以包括但不限于为锂的一元氧化物(如锂钴氧化物、锂镍氧化物、锂锰氧化物等)、锂的二元氧化物(如锂镍锰氧化物、锂镍钴氧化物、锂钴锰氧化物等)、锂的三元氧化物(如镍钴锰酸锂三元材料、镍钴铝酸锂三元材料等)或锂的多元氧化物，含锂的磷酸盐(如磷酸铁锂、磷酸锰铁锂)等中的一种或多种。其中，隔膜可以使用现有电池中的任何隔膜材料，示例性的，隔膜可以包括但不限于单层PP(聚丙烯)膜、单层PE(聚乙烯)膜、双层膜PP/PE、双层膜PP/PP和三层PP/PE/PP等聚合物隔膜，或无纺布等。
本申请实施例还提供了一种用电设备。如图2所示，用电设备1包括本申请实施例上述的锂电池10。
本申请中，对采用上述锂电池的用电设备没有特别限制。示例性地，该用电设备包括但不限于，手机、笔记本电脑、平板电脑、笔输入型计算机、便携式传真机、便携式复印机、便携式打印机、收发机、录像机、照相机、电视机、收音机、便携式录音机、便携CD机、迷你光盘、电子书播放器、电子记事本、可穿戴设备(如智能手表、智能手环、头戴式立体声耳机、蓝牙耳机)、手提式清洁器、计算器、存储卡、备用电源、汽车、摩托车、自行车(如助力自行车)、照明器具(如闪光灯)、玩具、游戏机、钟表、电动工具、家庭用大型蓄电池、锂离子电容器等。
由于采用了上述锂电池，该用电设备的电池的续航能力强，循环性能好，安全性高。
下面结合多个具体实施例对本申请的技术方案进行进一步的说明。
实施例1
一种锂离子电池的制备方法，包括：
1)配置电解液：在含水量<1ppm和含氧量<1ppm的充满氩气的手套箱，按表1中的配方将各非水有机溶剂混合，并向其中加入干燥的锂盐LiPF6及添加剂，配置得到成LiPF6浓度为14.5％的电解液。
2)制备正极极片：
将正极活性材料(具体为钴酸锂(LiCoO2))、导电剂(具体是碳纳米管(CNT))、粘结剂(具体是聚偏二氟乙烯)按照95：2：3的质量比混合，将混合后的粉料置于真空搅拌机中，加入溶剂—N-甲基吡咯烷酮(NMP)，搅拌均匀得到正极浆料；然后将该正极浆料涂布在正极集流体铝箔上，经85℃烘干、冷式辊压、裁片、分切后，在85℃的真空条件下干燥4h，得到正极极片。
3)制备负极极片：
将负极活性材料(具体是石墨，其粒径及尺寸参数如表1所示)与粘结剂(具体是丁苯橡胶(SBR)和羧甲基纤维素钠(CMC-Na)，质量比是2:3)按照95：5的质量比混合在离子水中，在真空搅拌机中搅拌均匀，得到负极浆料；然后将该负极浆料涂覆在负极集流体铜箔的相对两侧表面上，经烘干、冷式辊压、分切，得到负极极片。其中，该负极极片包括铜箔和设置在铜箔相对两侧表面上的负极活性材料层，每一负极活性材料层的厚度也汇总在表1中。
4)组装电池：
在充满氩气的手套箱中，将上述正极极片、聚乙烯(PE)隔膜、负极极片按顺序叠好，得到电芯；然后将叠好的电芯卷绕后置于铝塑膜外包装箔中，然后注入上述配制好的电解液，经过真空封装、静置、化成、整形等工序后，完成锂电池的制备。所得锂电池的前述性能因子k的计算结果也汇总在表1中。
需要说明的是，在本申请中对锂离子电池的制备方法涉及的某些操作的执行顺序不做限定。例如，操作1)、2)、和3)可能同时执行，也可能按照描述顺序不一致的顺序执行。
其他实施例
参照实施例1的电池的制备方法，根据表1所列参数，制备其余实施例及对比例的锂电池。
表1各实施例及对比例的锂电池参数


注：上表1中，EC代表环状碳酸酯类溶剂碳酸乙烯酯，PC代表环状碳酸酯类溶剂碳酸丙烯
酯，DEC代表线性碳酸酯类溶剂碳酸二乙酯，以及PP代表羧酸酯类溶剂丙酸丙酯。PS代表添加剂1,3-丙烷磺内酯。
实施例1-26、32-34及对比例1-5中，W0具体代表氟代碳酸乙烯酯在电解液中的质量占比，W1具体代表1,3,6-己烷三腈和丁二腈在电解液中的总质量占比；实施例27中，W0具体 代表4,5-二氟代碳酸乙烯酯在电解液中的质量占比，实施例28中，W0具体代表4,4,5,5-四氟代碳酸乙烯酯在电解液中的质量占比，实施例27-28中，W1代表1,3,6-己烷三腈和丁二腈在电解液中的总质量占比；实施例29-31中，W0具体代表氟代碳酸乙烯酯在电解液中的质量占比，实施例29中的W1代表1,3,6-己烷三腈和己二腈在电解液中的总质量占比，实施例30中的W1代表丁二腈在电解液中的质量占比，实施例31中的W1具体代表己二腈在电解液中的质量占比。
为对本申请的有益效果进行有力支持，测试以上各实施例及对比例的锂电池的以下电化学性能，结果汇总在下表2中。
1)常温循环性能的测试：
取5支待测的各锂电池，在常温下(25±3℃)以1C倍率恒流充电至截止电压4.48V，接着在4.48V下恒压充电至截止电流0.05C，使电池达到满电状态，之后搁置5min；然后以1C倍率恒流放电至3.0V，搁置5min。以此为一个充放电循环。记录常温循环1000次后的容量保持率和厚度膨胀率。其中，循环1000次后的容量保持率＝(循环1000次后的放电容量/首次放电容量)*100％；电池厚度膨胀率＝(循环1000次满电时的电池厚度/首次满电的电池厚度)*100％。
2)130℃炉温性能的测试：
每组取5支锂电池进行测试，先在常温下(25±3℃)以1C倍率恒流充电至截止电压4.48V，接着在4.48V下恒压充电至截止电流0.05C，使电池充满电，然后充满电后的12～24h内进行炉温测试(注意充满电后一定要搁置12h以上，不要立即开始测试)。采用对流方式或循环热空气箱对各锂电池从起始温度25±3℃进行加热，控制升温速率为5±2℃/min，升温时间在25-28min，升温至130±2℃，恒温保持60min后结束试验，观察各锂电池是否产烟、起火或爆炸。若锂电池没有发生上述现象，则认为锂电池通过炉温测试，记作OK；若锂电池发生上述现象，则认为锂电池未通过炉温测试，记作NG，记录每组5支电池中通过该炉温测试的电池支数。
表2各实施例及对比例的锂电池的性能测试结果汇总


注：表2中，“/”代表锂电池的循环寿命未能达到1000次。
结合表1和表2可以获知，当锂电池的电解液中的添加剂同时含有氟代碳酸酯和腈类添加剂时，且电池的构成使得其性能因子k在0.5-3.0的范围内，该锂电池的常温循环性能较好，容量保持较高，电芯厚度膨胀率较低；并可通过130℃炉温性能。特别地，当k在1.0-2.0时，电池能更好地兼顾各方面的性能。而当(2D1/Dv90+Dv50)/(W0+W1)的比值(即，性能因子k)低于0.5或大于3时(对比例1-3)，锂电池的长循环性能和炉温性能较差，明显劣于与其负极极片的特性参数及有机溶剂构成相同的实施例4。此外，当锂电池的电解液中不含氟代碳酸酯或腈类添加剂时，电池的各项性能均较差，即使上述参数k可以在0.5-3的范围内(对比例5)，但是锂电池的循环寿命很差，如循环次数难以达到1000次，对炉温测试的通过率低至0。
另外，从实施例1-5与实施例6-7的对比可以获知，在负极活性材料层的厚度D1不同、其他条件相同的情况下，在满足上述k在0.5-3时，当负极活性材料层的厚度D1在30-90μm范围内时(即，2D1在60-180μm范围内)，电池的各项性能参数均较好，特别是D1在30-75μm 内(即，2D1在60-150μm范围内)时。
实施例18-26中，在负极活性材料层的厚度D1、负极活性材料的粒径参数及电解液有机溶剂、添加剂PS相同，而氟代碳酸酯的含量W0、腈类物质的含量W1不尽相同。从实施例18-实施例23的比较可以获知，在同等条件下，当体系中氟代碳酸酯的含量W0在2-16范围内时，电池的循环性能各项性能均衡得较好，特别是耐膨胀性较好，特别地，当W0在优选范围6-12时，且W0/W1在更优选范围1.5-3.0时，k可在更优选范围1-2内，电池的综合性能较优异，若W2/W0进一步≥2时，则电池的综合性能更好。此外，从实施例26与实施例4、24-25的对比可以获知，当其他条件相同，体系中腈类添加剂的含量W1在优选范围2-10时，电池可以保持良好的炉温性能，同时电解液的粘度合适，电池阻抗较小，电池的循环性能较优、厚度膨胀率较小。
另外，从实施例4、实施例33-34的对比可以获知，对比电解液的有机溶剂是纯碳酸酯体系(如仅含EC、PC和DEC的实施例34)，羧酸酯的引入有利于提升电池的长循环性能，即，实施例4、33的循环性能优于实施例34，这主要是由于羧酸酯溶剂的加入，利于降低电解液的粘度、提升其对负极的浸润能力，有利于形成均匀稳定的SEI膜，进而利于循环过程的容量保持率提升、厚度膨胀率的降低。再者，从实施例4与实施例32的对比可知，当电解液中的添加剂同时含有相同组成的氟代碳酸酯和腈类添加剂、有机溶剂及负极极片的参数相同时，添加剂1,3-丙烷磺内酯(PS)的引入可进一步提升电池的耐高温性能。
以上所述是本申请的示例性实施方式，但并不能因此而理解为对本申请范围的限制。应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本申请的保护范围。

Claims (19)

  1. 一种锂电池(10)，其特征在于，包括正极极片(110)、负极极片(120)、隔膜(130)、和电解液(140)，所述负极极片包括集流体和设置在所述集流体至少一侧表面上的负极活性材料层(122)，所述电解液包括锂盐、有机溶剂、和添加剂，所述添加剂包含氟代碳酸酯和腈类物质，其中，所述负极活性材料层的厚度为D1μm，所述负极活性材料层中含有的负极活性材料的体积累积分布百分数达到50％时对应的粒径为Dv50μm，以及所述负极活性材料层中含有的负极活性材料的体积累积分布百分数达到90％时对应的粒径为Dv90μm；基于所述电解液的总质量，所述氟代碳酸酯的质量含量为W0％，所述腈类物质的质量含量为W1％，所述锂电池的性能因子k满足以下关系式：k＝(2D1/Dv90+Dv50)/(W0+W1)，且0.5≤k≤3.0。
  2. 如权利要求1所述的锂电池，其特征在于，所述k取值范围为：1.0≤k≤2.0。
  3. 如权利要求1或2所述的锂电池，其特征在于，所述W0的取值范围为：2≤W0≤16。
  4. 如权利要求1或2所述的锂电池，其特征在于，所述W0的取值范围为：5≤W0≤10。
  5. 如权利要求1-4任一项所述的锂电池，其特征在于，所述W1的取值范围为：2≤W1≤10。
  6. 如权利要求1或2所述的锂电池，其特征在于，所述W0与所述W1的比值满足：0.5≤W0/W1≤4。
  7. 如权利要求1或2所述的锂电池，其特征在于，所述W0与所述W1的比值满足：1.5≤W0/W1≤3.0。
  8. 如权利要求1-7任一项所述的锂电池，其特征在于，所述D1的取值范围为：30≤D1≤90。
  9. 如权利要求1-7任一项所述的锂电池，其特征在于，所述D1的取值范围为：40≤D1≤80。
  10. 如权利要求1-9任一项所述的锂电池，其特征在于，所述负极活性材料的粒径满足：8≤Dv50＜Dv90≤40。
  11. 如权利要求1-7任一项所述的锂电池，其特征在于，所述D1与所述Dv90的比值大于或等于1。
  12. 如权利要求1-11任一项所述的锂电池，其特征在于，所述氟代碳酸酯包括氟代碳酸乙烯酯、4,5-二氟代碳酸乙烯酯、4,4,5,5-四氟代碳酸乙烯酯、4-三氟甲基碳酸乙烯酯中的至少一种；以及所述腈类物质包括丁二腈、己二腈、戊二腈、丁烯二腈、1,4-二氰基-2-丁烯、3,3’-氧二丙腈、乙二醇二乙氰醚、1,2,3-三(2-氰氧基)丙烷、1,3,5-戊三甲腈、1,2,3-丙三甲腈和1,3,6-己烷三腈中的至少一种。
  13. 如权利要求1-12任一项所述的锂电池，其特征在于，所述有机溶剂包括羧酸酯类物质，其中，所述羧酸酯类物质包括乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丙酸戊酯、卤代乙酸乙酯、卤代丙酸乙酯、卤代丙酸丙酯、卤代丙酸丁酯和卤代丙酸戊酯中的至少一种。
  14. 如权利要求13所述的锂电池，其特征在于，所述有机溶剂还包括环状碳酸酯。
  15. 如权利要求14所述的锂电池，其特征在于，所述有机溶剂还包括线性碳酸酯类物质。
  16. 如权利要求13-15任一项所述的锂电池，其特征在于，基于所述电解液的总质量，所述羧酸酯类物质的总质量含量为W2％，且W2/W0≥2。
  17. 如权利要求16所述的锂电池，其特征在于，所述W2与所述W0的比值满足：2.5≤W2/W0≤8。
  18. 如权利要求1-17任一项所述的锂电池，其特征在于，所述添加剂还包含1,3-丙烷磺内酯、碳酸亚乙烯酯、乙烯基碳酸乙烯酯中的至少一种。
  19. 一种用电设备(1)，其特征在于，所述用电设备包括如权利要求1-18任一项所述的锂电池(10)。
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