WO2021037266A1 - 负极片及其制备方法和锂离子电池及其制备方法和应用 - Google Patents

负极片及其制备方法和锂离子电池及其制备方法和应用 Download PDF

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WO2021037266A1
WO2021037266A1 PCT/CN2020/112604 CN2020112604W WO2021037266A1 WO 2021037266 A1 WO2021037266 A1 WO 2021037266A1 CN 2020112604 W CN2020112604 W CN 2020112604W WO 2021037266 A1 WO2021037266 A1 WO 2021037266A1
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negative electrode
active material
weight
positive electrode
negative
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PCT/CN2020/112604
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English (en)
French (fr)
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熊得军
温石龙
李冲
廖章金
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孚能科技(赣州)股份有限公司
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Publication of WO2021037266A1 publication Critical patent/WO2021037266A1/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
    • 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
    • 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
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention relates to a negative electrode sheet and a preparation method thereof, as well as a lithium ion battery and a preparation method and application thereof.
  • lithium-ion batteries As a new type of green power source, lithium-ion batteries have the advantages of low self-discharge rate, high specific energy, high open circuit voltage, and no memory effect. They are widely used in mobile phones, notebook computers and other digital products, pure electric and hybrid new energy vehicles .
  • battery energy density and charging time are two important technical indicators, and existing new energy vehicles have too long charging time, which seriously affects the customer’s car experience and restricts the promotion and popularization of new energy vehicles. .
  • Increasing the energy density of the battery, improving the endurance of the car, and realizing the rapid charging of the battery at the same time play a vital role in the development of new energy vehicles.
  • CN105932349A discloses an improved single-particle model for lithium-ion batteries, and theoretical analysis methods are used to finally obtain the lithium insertion rate on the surface of the negative electrode active material and the set threshold.
  • this is only a theoretical optimization of the charging strategy of lithium-ion batteries. It is applied to the complex chemical system in lithium-ion batteries. The effect of fast charging is unknown.
  • CN105489857A discloses a lithium ion battery for rapid charging, which is characterized in that the negative electrode active material is modified graphite with a medium particle size D50 of 3 ⁇ m to 20 ⁇ m.
  • the modified graphite uses pitch powder as a raw material and spins filaments under a magnetic field. After carbonization, a carbon fiber structure that is conducive to the rapid diffusion of lithium ions and has excellent high-current charging ability is obtained, and it is compositely embedded into carbon microspheres formed by pyrolysis and activation with phenol resin as raw material, and the back surface is formed by pyrolysis of phenol resin particles.
  • the low-crystalline carbon coating layer makes the insertion of lithium ions easier and faster, and improves the diffusion rate of lithium ions.
  • the disclosed lithium-ion battery can be charged at 30C for 2 minutes, and it can be charged to more than 90% of the battery capacity , To achieve fast charging, but the data is only for small-capacity batteries (below 3Ah), which cannot meet the fast-charging requirements of high-energy-density batteries, and it has harsh requirements for raw materials and complex preparation of raw materials.
  • CN104347880A discloses a fast-chargeable lithium ion battery, characterized in that the positive active material includes component A and component B, and component A is selected from lithium nickel cobalt aluminate, lithium nickel cobalt manganate, lithium manganate and At least one of lithium cobaltate, and component B is selected from at least one of lithium iron phosphate and lithium titanate.
  • the use of this mixed positive electrode material prolongs the time of low-voltage constant current charging and increases the charging speed, but the positive electrode used in this method
  • the active material is two materials with different properties. Only by simple blending, in the actual use process, it is easy to cause the collapse of a certain material structure, and its cycle life cannot be guaranteed.
  • the purpose of the present invention is to overcome the defects of the prior art and provide a lithium ion battery with high capacity retention rate and high mass energy density.
  • the present invention provides a negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector, the negative electrode active material layer including from the inside to the outside Three layers, in which the innermost layer is used as the first negative electrode active material layer, numbered from the inside to the outside as the second negative electrode active material layer and the third negative electrode active material layer.
  • the particle size of the negative electrode active material of the three negative electrode active material layers Different and increasing sequentially from the inside to the outside, the negative active material of the first negative active material layer is artificial graphite with a D50 of 5-10 ⁇ m, and the negative active material of the second negative active material layer is artificial graphite with a D50 of 8-12 ⁇ m.
  • the negative active material D50 of the third negative active material layer is artificial graphite of 10-15 ⁇ m.
  • the present invention provides a method for preparing the negative electrode sheet of the present invention, the method comprising: (1) preparing a first negative electrode slurry containing a first negative electrode active material and a second negative electrode active material according to a formula The second negative electrode slurry and the third negative electrode slurry containing the third negative electrode active material are ready for use;
  • the present invention provides a lithium ion battery comprising: a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, a positive electrode tab, a negative electrode tab, and an aluminum plastic film.
  • the negative electrode sheet is of the present invention.
  • the negative electrode sheet is of the present invention.
  • the present invention provides a method for preparing a lithium ion battery, the method including:
  • Preparation of the negative electrode sheet prepare the negative electrode sheet according to the method of the present invention.
  • the positive electrode active material, the positive electrode conductive agent, the positive electrode binder, the dispersion aid and the solvent are made into a positive electrode slurry according to the formula.
  • the positive electrode activity is 92- 98%, positive electrode conductive agent 1-5%, positive electrode binder 1-5%, dispersion aid 0.1-1%;
  • the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, and the coating density is controlled at 2-3.5g/100cm 2 , after drying, rolling, and punching to obtain a positive electrode sheet, the compaction of the rolling is controlled at 3.0-3.5g/cc;
  • the obtained positive electrode sheet and negative electrode sheet After drying the obtained positive electrode sheet and negative electrode sheet, they are laminated with the separator in the order of separator-negative electrode sheet-diaphragm-positive electrode sheet-diaphragm-negative electrode sheet to form a battery cell.
  • the positive electrode aluminum tab and negative electrode are plated with copper.
  • the nickel tabs are welded to the cell, and the welded cell is placed in the punched aluminum plastic film for packaging;
  • the baking conditions of the battery include: temperature 80-85°C, time 20-28h; the conditions of the battery standing still include: temperature 25-30°C, time 40-48h;
  • the activated cell is formed at a temperature of 25-30°C and a pressure of 0.05-0.5 MPa.
  • the formation step includes: first charging to 3.6-3.8V with a constant current of 0.02-0.05C, Then use 0.05-0.1C constant current to charge to 3.8-3.9V, and finally 0.1-0.2C constant current and constant voltage to charge to 3.9-4.1V, cut-off current 0.01C;
  • the cells after the formation are allowed to stand at 45 ⁇ 2°C for 24-72h before being pumped, and the cells after the end of pumping and sealing are charged and discharged at 0.33C.
  • the present invention provides the application of the lithium ion battery of the present invention in a new energy vehicle.
  • the lithium ion battery adopting the negative electrode sheet of the present invention disclosed in the present invention has the advantages of fast charging and high energy density.
  • the lithium-ion battery of the present invention can achieve rapid charging above 3.2C, and the battery mass energy density is above 260Wh/kg, and the capacity retention rate of 2000 cycles of 3.2C rapid charging cycle is above 80%, which can meet the requirements of electric vehicle charging with 80% SOC in 15 minutes. High endurance and long life cycle requirements.
  • the present invention provides a negative electrode sheet.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector.
  • the negative electrode active material layer includes three layers from the inside to the outside, wherein the innermost layer As the first negative electrode active material layer, the second negative electrode active material layer and the third negative electrode active material layer are sequentially numbered from the inside to the outside.
  • the particle diameters of the negative electrode active materials of the three negative electrode active material layers are different and increase from the inside to the outside.
  • the negative electrode active material of the first negative electrode active material layer is artificial graphite with D50 of 5-10 ⁇ m
  • the negative electrode active material of the second negative electrode active material layer is artificial graphite with D50 of 8-12 ⁇ m
  • the negative electrode of the third negative electrode active material layer The active material D50 is artificial graphite of 10-15 ⁇ m.
  • the first negative electrode active material layer is coated on the negative electrode current collector
  • the second negative electrode active material layer is coated on the first negative electrode active material layer
  • the third negative electrode active material layer is coated on The second negative electrode active material layer.
  • the compaction of the negative electrode active material layer is 1.2-1.6 g/cc, preferably 1.3-1.5 g/cc.
  • the compaction density of the negative active material layer may be 1.2g/cc, 1.21g/cc, 1.22g/cc, 1.23g/cc, 1.24g/cc, 1.25g/cc, 1.26g/cc, 1.27g/cc cc, 1.28g/cc, 1.29g/cc, 1.3g/cc, 1.31g/cc, 1.32g/cc, 1.33g/cc, 1.34g/cc, 1.35g/cc, 1.36g/cc, 1.37g/ cc, 1.38g/cc, 1.39g/cc, 1.4g/cc, 1.41g/cc, 1.42g/cc, 1.43g/cc, 1.44g/cc, 1.45g/cc, 1.46g/cc, 1.47g/ c
  • the compaction density of the negative electrode active material layer is the average compaction density of the first negative electrode active material layer, the second negative electrode active material layer, and the third negative electrode active material layer.
  • the D50 of the negative active material of the first negative active material layer may be 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, 8.5 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m.
  • the D50 of the negative active material of the second negative active material layer may be 8 ⁇ m, 8.5 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m, 10.5 ⁇ m, 11 ⁇ m, 11.5 ⁇ m, 12 ⁇ m.
  • the D50 of the negative active material of the third negative active material layer may be 10 ⁇ m, 10.5 ⁇ m, 11 ⁇ m, 11.5 ⁇ m, 12 ⁇ m, 12.5 ⁇ m, 13 ⁇ m, 13.5 ⁇ m, 14 ⁇ m, 14.5 ⁇ m, 15 ⁇ m.
  • the objectives of the present invention can be achieved according to the foregoing solutions.
  • the contents of the negative electrode active material, the negative electrode conductive agent, the negative electrode binder and the negative electrode thickener can be selected in a wide range.
  • the first active material is preferred.
  • the layer, the second active material layer and the third active material layer each include:
  • Negative active material 90-97% by weight; Negative conductive agent: 1-5% by weight; Negative binder: 1-6% by weight; Negative thickener: 1-4% by weight.
  • the first active material layer, the second active material layer, and the third active material layer may each include the negative active material at 90% by weight, 90.5% by weight, 91% by weight, 91.5% by weight, 92% by weight, 92.5% by weight. Weight%, 93% by weight, 93.5% by weight, 94% by weight, 94.5% by weight, 95% by weight, 95.5% by weight, 96% by weight, 96.5% by weight, 97% by weight.
  • Each of the first active material layer, the second active material layer, and the third active material layer may include the negative electrode conductive agent at 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, 1.5% by weight. Weight%, 1.6% by weight, 1.7% by weight, 1.8% by weight, 1.9% by weight, 2% by weight, 2.1% by weight, 2.2% by weight, 2.3% by weight, 2.4% by weight, 2.5% by weight, 2.6% by weight, and 2.7% by weight , 2.8% by weight, 2.9% by weight, 3% by weight, 3.1% by weight, 3.2% by weight, 3.3% by weight, 3.4% by weight, 3.5% by weight, 3.6% by weight, 3.7% by weight, 3.8% by weight, 3.9% by weight, 4 Weight%, 4.1% by weight, 4.2% by weight, 4.3% by weight, 4.4% by weight, 4.5% by weight, 4.6% by weight, 4.7% by weight, 4.8% by weight, 4.9% by weight, and 5% by weight.
  • the first active material layer, the second active material layer, and the third active material layer may each include a negative electrode binder of 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, or 1.5% by weight. %, 1.6% by weight, 1.7% by weight, 1.8% by weight, 1.9% by weight, 2% by weight, 2.1% by weight, 2.2% by weight, 2.3% by weight, 2.4% by weight, 2.5% by weight, 2.6% by weight, 2.7% by weight, 2.8% by weight, 2.9% by weight, 3% by weight, 3.1% by weight, 3.2% by weight, 3.3% by weight, 3.4% by weight, 3.5% by weight, 3.6% by weight, 3.7% by weight, 3.8% by weight, 3.9% by weight, 4% by weight %, 4.1% by weight, 4.2% by weight, 4.3% by weight, 4.4% by weight, 4.5% by weight, 4.6% by weight, 4.7% by weight, 4.8% by weight, 4.9% by weight, 5% by weight, 5.1% by weight, 5.2% by weight, 5.3% by weight,
  • Each of the first active material layer, the second active material layer, and the third active material layer may include a negative electrode thickener at 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, or 1.5% by weight. %, 1.6% by weight, 1.7% by weight, 1.8% by weight, 1.9% by weight, 2% by weight, 2.1% by weight, 2.2% by weight, 2.3% by weight, 2.4% by weight, 2.5% by weight, 2.6% by weight, 2.7% by weight, 2.8% by weight, 2.9% by weight, 3% by weight, 3.1% by weight, 3.2% by weight, 3.3% by weight, 3.4% by weight, 3.5% by weight, 3.6% by weight, 3.7% by weight, 3.8% by weight, 3.9% by weight, 4% by weight %.
  • well-known materials can be used for the selection of the negative electrode conductive agent, negative electrode binder, negative electrode thickener, and negative electrode current collector.
  • the negative electrode binder is styrene-butadiene rubber and/or lithium polyacrylate, and preferably the negative electrode binder is butyl-butadiene rubber. A mixture of benzene rubber and lithium polyacrylate.
  • the number average molecular weight of the lithium polyacrylate is 100,000 to 1 million.
  • the number average molecular weight of the lithium polyacrylate may be 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000 , 400,000, 410,000, 420,000, 430,000, 440,000, 450,000, 460,000, 470,000, 480,000, 490,000, 500,000, 510,000, 520,000, 530,000, 540,000, 550,000, 56 10,000, 570,000, 580,000, 590,000, 600,000, 610,000, 620,000, 630,000, 640,000, 650,000, 660,000, 670,000, 680,000, 690,000, 700,000, 710,000, 720,000, 730,000, 740,000, 750,000, 760,000, 770,000, 780,000, 790,000, 800,000, 810,000, 820,000, 830,000
  • the negative electrode conductive agent is one or more of conductive carbon black, carbon nanotubes, vapor-generated carbon fibers, Ketjen black and graphene.
  • the negative electrode thickener is one or more of sodium carboxymethyl cellulose, polyvinylidene fluoride, lithium polyacrylate and polyacrylonitrile.
  • the negative electrode current collector is copper foil.
  • the negative electrode sheet is coated with three layers of artificial graphite with different particle size ranges to significantly improve the performance of the negative electrode sheet.
  • the preferred method for manufacturing the negative electrode sheet includes:
  • the total coating density of the negative electrode slurry is preferably 1.2-2.2 g/100 cm 2 , and the preferred coating density is each 1.5-2 g/100 cm 2 .
  • the total coating density of the negative electrode slurry can be 1.2g/100cm 2 , 1.3g/100cm 2 , 1.4g/100cm 2 , 1.5g/100cm 2 , 1.6g/100cm 2 , 1.7g/100cm 2 , 1.8g /100cm 2 , 1.9g/100cm 2 , 2g/100cm 2 , 2.1g/100cm 2 , 2.2g/100cm 2 .
  • the coating density of the negative active material layer may be 1.5g/100cm 2 , 1.6g/100cm 2 , 1.7g/100cm 2 , 1.8g/100cm 2 , 1.9g/100cm 2 , 2g/100cm 2, respectively .
  • the drying temperature is 60-100°C, for example, the drying temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C.
  • step (4) it is preferred that in step (4), the number of rolling presses is 2-3 times.
  • the negative electrode sheet of the present invention has excellent performance, can achieve rapid charging above 3.2C when used in lithium ion batteries, and the battery mass energy density is above 260Wh/kg, and the capacity retention rate of 2000 cycles of 3.2C rapid charging cycle is above 80%, which can meet the requirements of electric vehicles. 15min is full of 80% SOC fast charging, high endurance and long life cycle requirements.
  • a lithium ion battery comprising: a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, a positive electrode tab, a negative electrode tab, and an aluminum plastic film.
  • the negative electrode sheet is the one described in the present invention.
  • the negative plate is the one described in the present invention.
  • the negative electrode sheet adopts the negative electrode sheet of the present invention.
  • Others such as positive electrode sheet, separator and electrolyte, positive electrode tab, negative electrode tab and aluminum plastic can all be selected according to the prior art.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on the positive electrode current collector, and the positive electrode active material layer contains: positive electrode active material: 92-98% by weight; positive electrode conductive agent: 1-5 Weight %; positive electrode binder: 1-5% by weight; dispersion aid 0.1-1% by weight.
  • the positive active material contained in the positive active material layer may be 92% by weight, 93% by weight, 94% by weight, 95% by weight, 96% by weight, 97% by weight, or 98% by weight.
  • the positive electrode conductive agent contained in the positive electrode active material layer may be 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, 1.5% by weight, 1.6% by weight, 1.7% by weight, 1.8% by weight, 1.9% by weight.
  • Weight% 2% by weight, 2.1% by weight, 2.2% by weight, 2.3% by weight, 2.4% by weight, 2.5% by weight, 2.6% by weight, 2.7% by weight, 2.8% by weight, 2.9% by weight, 3% by weight, 3.1% by weight , 3.2% by weight, 3.3% by weight, 3.4% by weight, 3.5% by weight, 3.6% by weight, 3.7% by weight, 3.8% by weight, 3.9% by weight, 4% by weight, 4.1% by weight, 4.2% by weight, 4.3% by weight, 4.4 Weight%, 4.5% by weight, 4.6% by weight, 4.7% by weight, 4.8% by weight, 4.9% by weight, and 5% by weight.
  • the positive electrode binder contained in the positive electrode active material layer may be 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, 1.5% by weight, 1.6% by weight, 1.7% by weight, 1.8% by weight, 1.9% by weight, 2% by weight, 2.1% by weight, 2.2% by weight, 2.3% by weight, 2.4% by weight, 2.5% by weight, 2.6% by weight, 2.7% by weight, 2.8% by weight, 2.9% by weight, 3% by weight, 3.1% by weight %, 3.2% by weight, 3.3% by weight, 3.4% by weight, 3.5% by weight, 3.6% by weight, 3.7% by weight, 3.8% by weight, 3.9% by weight, 4% by weight, 4.1% by weight, 4.2% by weight, 4.3% by weight, 4.4% by weight, 4.5% by weight, 4.6% by weight, 4.7% by weight, 4.8% by weight, 4.9% by weight, and 5% by weight.
  • the dispersion aid contained in the positive active material layer may be 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, 0.9% by weight, 1 weight%.
  • the compaction of the positive electrode active material layer is preferably 3-3.5 g/cc.
  • the compaction of the positive active material layer may be 3g/cc, 3.1g/cc, 3.2g/cc, 3.3g/cc, 3.4g/cc, 3.5g/cc.
  • the positive electrode active material is NCM811 and/or NCA, and the particle size D50 of the positive electrode active material is preferably in the range of 3-12 ⁇ m.
  • the particle size D50 of the positive active material may be 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, 8.5 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m, 10.5 ⁇ m , 11 ⁇ m, 11.5 ⁇ m, 12 ⁇ m.
  • NCA is preferred. According to the present invention, NCA is used as the positive electrode active material. It can be seen that a lower cobalt content ratio is used, but in fact, achieving low cobalt or even cobalt-free is an important cost reduction method, such as 91:3 :6.
  • the positive electrode conductive agent is at least one of carbon black, carbon nanotube, carbon fiber and graphene.
  • the positive electrode binder is PVDF and/or PTEF;
  • the dispersion aid is polyvinylpyrrolidone.
  • the positive electrode tab is an aluminum tab; the negative electrode tab is a copper-nickel-plated tab.
  • the diaphragm is a PP film, a PE film, a PP-PE double-layer film or a PP-PE-PP three-layer film.
  • the electrolyte is a mixed solution containing a lithium salt, an additive and an organic solvent.
  • the concentration of the lithium salt in the mixed solution is 0.8-1.2 mol/L, and the weight percentage of the additive is 0.5-4%.
  • the concentration of the lithium salt in the mixed solution may be 0.8 mol/L, 0.9 mol/L, 1 mol/L, 1.1 mol/L, 1.2 mol/L.
  • the weight percentage of the additive can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8 %, 1.9%, 2%, 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%.
  • the lithium salt is lithium hexafluorophosphate and/or lithium bis(fluorosulfonyl)imide.
  • the organic solvent is one or more of ethylene carbonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate.
  • the additives are vinylene carbonate, propyl sulfite, fluoroethylene carbonate, vinyl sulfate, 1-propylene-1,3-sultone, methyl disulfide One or more of methylene sulfonate and lithium difluorophosphate.
  • a method for preparing a lithium ion battery including:
  • Preparation of the negative electrode sheet prepare the negative electrode sheet according to the method of the present invention.
  • the positive electrode active material, the positive electrode conductive agent, the positive electrode binder, the dispersion aid and the solvent are made into a positive electrode slurry according to the formula.
  • the positive electrode activity is 92- 98%, positive electrode conductive agent 1-5%, positive electrode binder 1-5%, dispersion aid 0.1-1%;
  • the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, and the coating density is controlled at 2-3.5g/100cm 2 , after drying, rolling, and punching to obtain a positive electrode sheet, the compaction of the rolling is controlled at 3.0-3.5g/cc;
  • the obtained positive electrode sheet and negative electrode sheet After drying the obtained positive electrode sheet and negative electrode sheet, they are laminated with the separator in the order of separator-negative electrode sheet-diaphragm-positive electrode sheet-diaphragm-negative electrode sheet to form a battery cell.
  • the positive electrode aluminum tab and negative electrode are plated with copper.
  • the nickel tabs are welded to the cell, and the welded cell is placed in the punched aluminum plastic film for packaging;
  • the baking conditions of the battery include: temperature 80-85°C, time 20-28h; the conditions of the battery standing still include: temperature 25-30°C, time 40-48h;
  • the activated cell is formed at a temperature of 25-30°C and a pressure of 0.05-0.5 MPa.
  • the formation step includes: first charging to 3.6-3.8V with a constant current of 0.02-0.05C, Then use 0.05-0.1C constant current to charge to 3.8-3.9V, and finally 0.1-0.2C constant current and constant voltage to charge to 3.9-4.1V, cut-off current 0.01C;
  • the cells after the formation are allowed to stand at 45 ⁇ 2°C for 24-72h before being pumped, and the cells after the end of pumping and sealing are charged and discharged at 0.33C.
  • the lithium-ion battery prepared according to the foregoing method can fully realize fast charging above 3.2C, and the battery mass energy density is above 260Wh/kg, and the capacity retention rate of 2000 cycles of 3.2C fast charging cycle is above 80%, which can meet the requirement of 80% SOC full of electric vehicles in 15 minutes. Fast charging, high battery life and long life cycle requirements.
  • D50 refers to the corresponding particle size when the cumulative particle size distribution percentage of the material reaches 50%.
  • the invention provides the application of the lithium ion battery of the invention in a new energy vehicle.
  • Preparation of positive electrode sheet The positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 97.7 by mass percentage. %, conductive agent 1%, binder 1.1%, dispersing aid 0.1%;
  • the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 2.5g/100cm 2 , and then passed
  • the positive electrode sheet is obtained by drying, rolling, and punching, and the compaction of the rolling is controlled at 3.0 g/cc.
  • the positive active material is: a mixture of NCM811 and NCA (weight ratio is 1:1) with a particle size D50 in the range of 7.5 ⁇ m; the conductive agent is carbon black; the binder is PVDF; the dispersion aid For polyvinylpyrrolidone.
  • the first negative electrode active material artificial graphite (brand CP7M, D50 is 8.2 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate mixture (mass ratio 1:1), thickener carboxymethyl Base cellulose sodium and solvent deionized water are made into negative electrode slurry in a certain proportion.
  • the proportion of negative electrode active material is 95.5%, conductive agent 1%, and binder 2%. , Thickener 1.5%; Coat the prepared negative electrode slurry evenly on both sides of the copper foil, with the coating surface density controlled at 0.5g/100cm 2 , and dry (condition 60°C) to obtain the first coil;
  • the second negative electrode active material artificial graphite (brand QC8, D50 is 10.3 ⁇ m), conductive agent carbon nanotubes, a mixture of binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1), thickener carboxymethyl Base cellulose sodium and solvent deionized water are made into negative electrode slurry in a certain proportion.
  • the proportion of negative electrode active material is 95.5%, conductive agent 1%, and binder 2%. , Thickening agent 1.5%; evenly coat the prepared negative electrode slurry on the first roll material, the coating surface density is controlled at 0.5g/100cm 2 , and then dry (conditions 70 °C) to obtain the second roll material ;
  • the third negative electrode active material is a mixture of artificial graphite (brand EH15X, D50 is 11.9 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1, data molecular weight of lithium polyacrylate 500,000), the thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion. In the dry powder of negative electrode slurry, the proportion of negative electrode active material is 95.5% by mass.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm is made of a PP film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: a temperature of 80°C, a time of 28h, the electrolyte is a mixed solution of lithium salt, additives and an organic solvent, the concentration of the lithium salt in the mixed solution is 0.8 mol/L, and the lithium salt Lithium hexafluorophosphate, the organic solvent is ethylene carbonate, diethyl carbonate and ethyl methyl carbonate (the volume ratio of the three is 3:3:4); the additives are vinylene carbonate, propyl sulfite, and ethylene sulfate A mixture of esters and lithium difluorophosphate and 1-propylene-1,3-sultone, the volume percentage of additives in the electrolyte is 4.0% (vinylene carbonate, propyl sulfite, vinyl sulfate and two The weight ratios of lithium fluorophosphate and 1-propene-1,3-sultone are respectively 1%, 1%, 0.5%, 1% and 0.5%), and the
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand at 45 ⁇ 2°C for 48 hours and then degas, and the cells after the end of the gas and edge sealing are charged and discharged at 0.33C.
  • Preparation of positive electrode sheet The positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 96 by mass percentage. %, conductive agent 2.5%, binder 1.4%, dispersion aid 0.1%;
  • the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 3g/100cm 2 , and then dried , Rolling and punching to obtain a positive electrode sheet, and the compaction of the rolling is controlled at 3.5 g/cc.
  • the positive active material is: NCM811 with a particle size D50 in the range of 8.5 ⁇ m; the conductive agent is gas-phase-generated carbon fiber; the binder is PTEF; and the dispersion aid is polyvinylpyrrolidone (brand name PVP-K30).
  • the first negative electrode active material artificial graphite (brand CP5M, D50 is 7.2 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio is 5:1, the data molecular weight of lithium polyacrylate 500,000), the thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion.
  • the proportion of negative electrode active material is 95.5% by mass.
  • Conductive agent 1%, binder 2%, thickener 1.5% evenly coat the prepared negative electrode slurry on both sides of the copper foil, the coating surface density is controlled at 0.6g/100cm 2 , dry (conditions 65°C) to get the first roll of material;
  • the second negative electrode active material artificial graphite (brand QC8, D50 is 10.3 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and polyacrylate lithium mixture (mass ratio 1:1, data molecular weight of polyacrylate lithium 500,000), the thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion.
  • the proportion of negative electrode active material is 95.5% by mass.
  • Conductive agent 1%, binder 2%, thickener 1.5% coat the prepared negative electrode slurry evenly on the first coil, and the coating surface density is controlled at 0.6g/100cm 2 , and then dried (Condition 75°C) Obtain the second roll of material;
  • the third negative electrode active material artificial graphite (brand P15-X, D50 is 13.6 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The number average molecular weight is 500,000), the thickener sodium carboxymethyl cellulose and the solvent deionized water are made into a negative electrode slurry in a certain ratio.
  • the ratio of the negative electrode active material is as follows: 95.5%, conductive agent 1%, binder 2%, thickener 1.5%; the prepared negative electrode slurry is evenly coated on the second coil, and the coating surface density is controlled at 0.8g/100cm 2 , After drying (condition 85° C.), roll pressing 3 times, punching to obtain a negative electrode sheet, and the compaction of the roll pressing is controlled at 1.4 g/cc.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm adopts a PE film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: a temperature of 85°C, a time of 20h, the electrolyte is a mixed solution of lithium salt, additives and an organic solvent, the concentration of the lithium salt in the mixed solution is 1.2 mol/L, and the lithium salt Lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide (wherein, the concentration of lithium hexafluorophosphate is 1.0mol/L and the concentration of lithium bis(fluorosulfonyl)imide is 0.2mol/L), and the organic solvent is ethylene carbonate, carbonic acid A mixture of diethyl and ethyl methyl carbonate (volume ratio 3:3:4); the additives are vinylene carbonate, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1, A mixture of 3-sultones, the volume percentage of additives in the electrolyte is 2.5% (vinylene carbonate, propy
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand at 45 ⁇ 2°C for 48 hours and then degas, and the cells after the end of the gas and edge sealing are charged and discharged at 0.33C.
  • the positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 96 by mass percentage. %, conductive agent 2.5%, binder 1.4%, dispersing aid 0.1%; the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 2.5g/100cm 2 , and then passed
  • the positive electrode sheet is obtained by drying, rolling, and punching, and the compaction of the rolling is controlled at 3.0 g/cc.
  • the positive active material is: NCA with a particle size D50 in the range of 6.5 ⁇ m; the conductive agent is carbon black; the binder is PVDF; and the dispersion aid is polyvinylpyrrolidone.
  • the first negative active material is a mixture of artificial graphite (brand CP5M, D50 of 7.2 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1, data molecular weight of lithium polyacrylate 500,000), the thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion. In the dry powder of negative electrode slurry, the proportion of negative electrode active material is 95.5% by mass.
  • Conductive agent 1%, binder 2%, thickener 1.5% evenly coat the prepared negative electrode slurry on both sides of the copper foil, the coating surface density is controlled at 0.6g/100cm 2 , dry (conditions 70°C) to get the first roll of material;
  • the second negative electrode active material artificial graphite (brand CAG-3MT, D50 is 10.7 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The data molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5 %, conductive agent 1%, binder 2%, thickener 1.5%; coat the prepared negative electrode slurry evenly on the first coil, and the coating surface density is controlled at 0.5g/100cm 2 , and then After drying (conditions at 80°C), the second roll is obtained;
  • the third negative electrode active material artificial graphite (brand P15-X, D50 is 13.6 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The data molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5 %, conductive agent 1%, binder 2%, thickener 1.5%; evenly coat the prepared negative electrode slurry on the second coil, the coating surface density is controlled at 0.5g/100cm 2 , after After drying (condition 90° C.), rolling pressing twice, punching the sheet to obtain a negative electrode sheet, and the compaction of the rolling pressing is controlled at 1.3 g/cc.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm adopts a PP-PE-PP film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: temperature 82°C, time 25h, the electrolyte is a mixed solution of lithium salt, additives and organic solvent, the concentration of lithium salt in the mixed solution is 1 mol/L, and the lithium salt is A mixture of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide (8:2), the organic solvent is ethylene carbonate, diethyl carbonate and ethyl methyl carbonate (volume ratio 3:3:4);
  • the additives are vinylene carbonate, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone.
  • the volume percentage of the additives in the electrolyte is 3% (vinylene carbonate).
  • the weight ratios of five esters, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone are 0.5%, 1%, 0.5%, 0.5% and 0.5% respectively)
  • the conditions for the battery cell to stand still are: a temperature of 28° C., and a time of 45 hours.
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand for 45h at 45 ⁇ 2°C, and then degas, and the cells after the end of gas extraction and sealing are charged and discharged at 0.33C.
  • the positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 96 by mass percentage. %, conductive agent 2.5%, binder 1.4%, dispersing aid 0.1%; the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 2.5g/100cm 2 , and then passed
  • the positive electrode sheet is obtained by drying, rolling, and punching, and the compaction of the rolling is controlled at 3.0 g/cc.
  • the positive active material is: NCA with a particle size D50 in the range of 6.5 ⁇ m; the conductive agent is carbon black; the binder is PVDF; and the dispersion aid is polyvinylpyrrolidone.
  • the first negative active material is a mixture of artificial graphite (brand CP5M, D50 of 7.2 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1, data molecular weight of lithium polyacrylate 500,000), the thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion. In the dry powder of negative electrode slurry, the proportion of negative electrode active material is 95.5% by mass.
  • Conductive agent 1%, binder 2%, thickener 1.5% evenly coat the prepared negative electrode slurry on both sides of the copper foil, the coating surface density is controlled at 0.6g/100cm 2 , dry (conditions 70°C) to get the first roll of material;
  • the second negative electrode active material artificial graphite (brand CAG-3MT, D50 is 10.7 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The data molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5 %, conductive agent 1%, binder 2%, thickener 1.5%; coat the prepared negative electrode slurry evenly on the first coil, and the coating surface density is controlled at 0.5g/100cm 2 , and then After drying (conditions at 80°C), the second roll is obtained;
  • the third negative electrode active material artificial graphite (brand P15-X, D50 is 13.6 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The data molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5 %, conductive agent 1%, binder 2%, thickener 1.5%; evenly coat the prepared negative electrode slurry on the second coil, the coating surface density is controlled at 0.5g/100cm 2 , after After drying (condition 90° C.), rolling pressing twice, punching to obtain a negative electrode sheet, the compaction of the rolling is controlled at 1.2 g/cc.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm adopts a PP-PE-PP film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: temperature 82°C, time 25h, the electrolyte is a mixed solution of lithium salt, additives and organic solvent, the concentration of lithium salt in the mixed solution is 1 mol/L, and the lithium salt is A mixture of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide (8:2), the organic solvent is ethylene carbonate, diethyl carbonate and ethyl methyl carbonate (volume ratio 3:3:4);
  • the additives are vinylene carbonate, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone.
  • the volume percentage of the additives in the electrolyte is 3% (vinylene carbonate).
  • the weight ratios of five esters, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone are 0.5%, 1%, 0.5%, 0.5% and 0.5% respectively)
  • the conditions for the battery cell to stand still are: a temperature of 28° C., and a time of 45 hours.
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand for 45h at 45 ⁇ 2°C, and then degas, and the cells after the end of gas extraction and sealing are charged and discharged at 0.33C.
  • the positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 96 by mass percentage. %, conductive agent 2.5%, binder 1.4%, dispersing aid 0.1%; the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 2.5g/100cm 2 , and then passed
  • the positive electrode sheet is obtained by drying, rolling, and punching, and the compaction of the rolling is controlled at 3.0 g/cc.
  • the positive active material is: NCA with a particle size D50 in the range of 6.5 ⁇ m; the conductive agent is carbon black; the binder is PVDF; and the dispersion aid is polyvinylpyrrolidone.
  • the first negative active material is a mixture of artificial graphite (brand CP5M, D50 of 7.2 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1, data molecular weight of lithium polyacrylate 500,000), the thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion. In the dry powder of negative electrode slurry, the proportion of negative electrode active material is 95.5% by mass.
  • Conductive agent 1%, binder 2%, thickener 1.5% evenly coat the prepared negative electrode slurry on both sides of the copper foil, the coating surface density is controlled at 0.6g/100cm 2 , dry (conditions 70°C) to get the first roll of material;
  • the second negative electrode active material artificial graphite (brand CAG-3MT, D50 is 10.7 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The data molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5 %, conductive agent 1%, binder 2%, thickener 1.5%; coat the prepared negative electrode slurry evenly on the first coil, and the coating surface density is controlled at 0.5g/100cm 2 , and then After drying (condition 80°C), the second roll of material is obtained;
  • the third negative electrode active material artificial graphite (brand P15-X, D50 is 13.6 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and a mixture of lithium polyacrylate (mass ratio 1:1, lithium polyacrylate The data molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5 %, conductive agent 1%, binder 2%, thickener 1.5%; evenly coat the prepared negative electrode slurry on the second coil, the coating surface density is controlled at 0.5g/100cm 2 , after After drying (condition 90° C.), rolling pressing twice, punching the sheet to obtain a negative electrode sheet, and the compaction of the rolling pressing is controlled at 1.6 g/cc.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm adopts a PP-PE-PP film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: temperature 82°C, time 25h, the electrolyte is a mixed solution of lithium salt, additives and organic solvent, the concentration of lithium salt in the mixed solution is 1 mol/L, and the lithium salt is A mixture of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide (8:2), the organic solvent is ethylene carbonate, diethyl carbonate and ethyl methyl carbonate (volume ratio 3:3:4);
  • the additives are vinylene carbonate, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone.
  • the volume percentage of the additives in the electrolyte is 3% (vinylene carbonate).
  • the weight ratios of five esters, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone are 0.5%, 1%, 0.5%, 0.5% and 0.5% respectively.
  • the conditions for the battery cell to stand still are: a temperature of 28° C., and a time of 45 hours.
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand for 45h at 45 ⁇ 2°C, and then degas, and the cells after the end of gas extraction and sealing are charged and discharged at 0.33C.
  • the positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 96 by mass percentage. %, conductive agent 2.5%, binder 1.4%, dispersing aid 0.1%; the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 3.6g/100cm 2 , and then passed
  • the positive electrode sheet is obtained by drying, rolling, and punching, and the compaction of the rolling is controlled at 3.5 g/cc.
  • the positive active material is: NCM811 with a particle size D50 of 12.5 ⁇ m; the conductive agent is carbon black; the binder is PVDF; and the dispersion aid is polyvinylpyrrolidone.
  • the negative electrode active material artificial graphite (brand P15, D50 is 15.4 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber, thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion
  • the proportion of negative electrode active material is 95.5%, conductive agent 1%, binder 2%, and thickener 1.5% in terms of mass percentage
  • the prepared negative electrode slurry is uniformly Coated on the copper foil, the coating surface density is controlled at 2.4 g/100 cm 2 , then dried at 80° C., rolled once, punched out to obtain a negative electrode sheet, and the compaction of the roll press is controlled at 1.6 g/cc.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm is made of a PP film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: a temperature of 80°C, a time of 24h, the electrolyte is a mixed solution of lithium salt, additives and an organic solvent, the concentration of the lithium salt in the mixed solution is 1 mol/L, and the lithium salt is Lithium hexafluorophosphate, the organic solvent is ethylene carbonate and ethyl methyl carbonate, the ratio is 1:4; the additives are vinylene carbonate and propyl sulfite, and the volume percentages of the additives in the electrolyte are 1% and 1% respectively. 1%, the conditions for the battery cell to stand still are: a temperature of 25° C., and a time of 24 h.
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand at 45 ⁇ 2°C for 24 hours and then degas, and the cells after the end of gas extraction and sealing are charged and discharged at 0.33C.
  • the positive electrode active material, conductive agent, binder, dispersing aid and solvent are made into positive electrode slurry in a certain proportion.
  • the ratio of positive electrode active material is 96 by mass percentage. %, conductive agent 2.5%, binder 1.4%, dispersing aid 0.1%; the prepared positive electrode slurry is evenly coated on both sides of the aluminum foil, the coating surface density is controlled at 2.5g/100cm 2 , and then passed
  • the positive electrode sheet is obtained by drying, rolling, and punching, and the compaction of the rolling is controlled at 3.0 g/cc.
  • the positive active material is: NCA with a particle size D50 in the range of 6.5 ⁇ m; the conductive agent is carbon black; the binder is PVDF; and the dispersion aid is polyvinylpyrrolidone.
  • the first negative active material is a mixture of artificial graphite (brand CP5M, D50 is 15 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio is 1:1, and the data molecular weight of lithium polyacrylate is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • artificial graphite brand CP5M, D50 is 15 ⁇ m
  • conductive agent carbon nanotubes binder styrene butadiene rubber and lithium polyacrylate (mass ratio is 1:1, and the data molecular weight of lithium polyacrylate is 500,000)
  • thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain ratio.
  • the ratio of negative electrode active material is 95.5%, conductive 1% of the binder, 2% of the binder, and 1.5% of the thickener; the prepared negative electrode slurry is evenly coated on both sides of the copper foil, the coating surface density is controlled at 0.6g/100cm 2 , and dried (condition 70 °C) get the first roll of material;
  • the second negative electrode active material is a mixture of artificial graphite (brand CAG-3MT, D50 of 20 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1, data of lithium polyacrylate) (Molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion. In the dry powder of negative electrode slurry, the proportion of negative electrode active material is 95.5% by mass percentage.
  • the prepared negative electrode slurry is evenly coated on the first coil, the coating surface density is controlled at 0.5g/100cm 2 , after Dry (condition 80°C) to get the second roll of material;
  • the third negative active material is a mixture of artificial graphite (brand P15-X, D50 of 25 ⁇ m), conductive agent carbon nanotubes, binder styrene butadiene rubber and lithium polyacrylate (mass ratio 1:1, data of lithium polyacrylate) (Molecular weight is 500,000), thickener sodium carboxymethyl cellulose and solvent deionized water are made into negative electrode slurry in a certain proportion. In the dry powder of negative electrode slurry, the proportion of negative electrode active material is 95.5% by mass percentage.
  • the prepared negative electrode slurry is evenly coated on the second coil, the coating surface density is controlled at 0.5g/100cm 2 , after Dry (condition 90°C), roll pressing twice, punch the sheet to obtain a negative electrode sheet, and the compaction of the roll press is controlled at 1.6 g/cc.
  • Cell preparation After drying the obtained positive and negative sheets, stack them with the separator in the order of separator-negative sheet-diaphragm-positive sheet-diaphragm-negative sheet to form a battery, and use an ultrasonic welding machine to connect the positive aluminum tabs with The copper and nickel-plated tabs of the negative electrode are welded on the battery core, and the welded battery core is placed in a punched aluminum plastic film for packaging, and the diaphragm adopts a PP-PE-PP film.
  • Cell injection Bake the packaged cells and inject the electrolyte. Before the injection, the moisture of the cell should be controlled below 200ppm. After the injection, the cell is sealed and the cell is statically activated, so that the electrolyte can dissolve the positive and negative plates. Fully infiltrate the diaphragm.
  • the conditions for baking the battery cell are: temperature 82°C, time 25h, the electrolyte is a mixed solution of lithium salt, additives and organic solvent, the concentration of lithium salt in the mixed solution is 1 mol/L, and the lithium salt is A mixture of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide (8:2), the organic solvent is ethylene carbonate, diethyl carbonate and ethyl methyl carbonate (volume ratio 3:3:4);
  • the additives are vinylene carbonate, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone.
  • the volume percentage of the additives in the electrolyte is 3% (vinylene carbonate).
  • the weight ratios of five esters, propyl sulfite, vinyl sulfate, lithium difluorophosphate and 1-propylene-1,3-sultone are 0.5%, 1%, 0.5%, 0.5% and 0.5% respectively)
  • the conditions for the battery cell to stand still are: a temperature of 28° C., and a time of 45 hours.
  • the activated cell is formed under the conditions of a temperature of 25°C and a pressure torque of 8 Nm.
  • the process step of the formation is as follows: first use a constant current of 0.05C to charge to 3.6V, and then use a constant current of 0.1C Charge to 3.8V, finally 0.2C constant current and constant voltage charge to 3.9V, cut-off current 0.01C.
  • the cells after the formation are allowed to stand for 45h at 45 ⁇ 2°C, and then degas, and the cells after the end of gas extraction and sealing are charged and discharged at 0.33C.
  • the batteries in the examples and comparative examples were weighed and the corresponding energy density of 0.33C was calculated; then the batteries were subjected to a fast charge cycle life test, the test method was 25°C ambient temperature, and the average rate of 3.2C was quickly charged to 80% SOC, then 1C discharge, charge and discharge cycle test, while recording the cell body temperature during the cycle, the test results are shown in Table 2.
  • Table 1 shows the parameters of each embodiment and comparative example
  • Table 2 shows the performance parameters of each embodiment and comparative example
  • Example 1 and Example 2 it is shown that reducing the particle size of graphite is beneficial to increase the cycle life of the battery and reduce the temperature rise of fast charging. Comparing Examples 3, 4 and 5, the energy density of Example 3 is comparable to that of Examples 4 and 5, but the cycle life is better, and the temperature rise of fast charging is lower, indicating that a suitable negative electrode compaction design is beneficial to achieve the present invention aims.
  • the negative electrode sheet of the present invention has excellent performance, can realize fast charging above 3.2C when used in lithium ion batteries, and the battery mass energy density is above 260Wh/kg, the capacity retention rate of 2000 cycles of 3.2C fast charging cycle is above 80%, and fast charging The low temperature rise during the process is conducive to battery thermal management, and meets the requirements of fast charging, high endurance and long life cycle of electric vehicles with a full 80% SOC in 15 minutes.

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Abstract

一种负极片及其制作方法和锂离子电池及其制备方法和应用，负极片包括负极集流体和涂覆在负极集流体表面的负极活性物质层，负极活性物质层由内至外包括三层，三个负极活性物质层的负极活性物质的粒径不同且由内及外依次增大，第一负极活性物质层的负极活性物质为D50为5-10μm的人造石墨，第二负极活性物质层的负极活性物质为D50为8-12μm的人造石墨，第三负极活性物质层的负极活性物质为D50为10-15μm的人造石墨。

Description

负极片及其制备方法和锂离子电池及其制备方法和应用 技术领域
本发明涉及一种负极片及其制备方法，以及一种锂离子电池及其制备方法和应用。
背景技术
锂离子电池作为一种新型的绿色电源，具有自放电率小、比能量高，开路电压高，无记忆效应等优点，广泛运用于手机、笔记本电脑等数码产品，纯电动以及混合动力新能源汽车。对新能源汽车来说，电池的能量密度与充电时间是两个重要的技术指标，而现有的新能源汽车充电时间过长，严重影响客户的用车体验，限制着新能源汽车的推广普及。提高电池的能量密度，提升汽车的续航，同时实现电池的快速充电，对新能源汽车的发展起着至关重要的作用。
目前也有一些可实现锂离子电池快速充电的方法，如CN105932349A公开了一种通过对锂离子电池建立改进的单粒子模型，利用理论分析方法最终得出负极活性物质表面嵌锂率与设定阀值的大小关系，从而控制电池充电电流大小与充电时间实现锂离子电池的快速充电，但这仅仅是理论上优化了锂离子电池的充电策略，运用于锂离子电池内复杂的化学体系，其实际的快充效果未可知。
CN105489857A公开了一种快速充电用锂离子电池，其特征在于选用负极活性物质为中粒径D50为3μm～20μm的改性石墨，所述的改性石墨以沥青粉末为原料，在磁场下甩丝后碳化得到有利于锂离子快速扩散、具有优良的大电流充电能力的碳纤维结构，并复合镶嵌入以酚醛树脂为原料经过热解活化形成的碳微球，而后表面采用了酚醛树脂颗粒热解形成的低结晶性碳 包覆层，该包覆层使锂离子的嵌入更加容易、快速，提高了锂离子的扩散速率，公开的锂离子电池在30C充电2min，可充电至电池电量的90％以上，实现快速充电，但其数据仅仅是小容量(3Ah以下)电池的数据，并不能满足高能量密度电池的快充要求，且其对原料要求苛刻，原料制备复杂。
CN104347880A公开了一种可快充的锂离子电池，其特征在于所述正极活性物质包括组分A与组分B，组分A选用镍钴铝酸锂、镍钴锰酸锂、锰酸锂和钴酸锂的至少一种，组分B选自磷酸铁锂和钛酸锂的至少一种，该混合正极材料的使用延长低电压恒流充电的时间，提升充电速度，但该方法使用的正极活性物质为两种性质不同的材料，仅仅是通过简单的共混，在实际使用过程中，容易导致某一材料结构的坍塌，不能保证其循环寿命。
发明内容
本发明的目的是为了克服现有技术的缺陷，提供一种容量保持率高，质量能量密度高的锂离子电池。
为实现前述目的，第一方面，本发明提供一种负极片，所述负极片包括负极集流体和涂覆在负极集流体表面的负极活性物质层，所述负极活性物质层由内至外包括三层，其中，最内层作为第一负极活性物质层，由内及外依次编号为第二负极活性物质层和第三负极活性物质层，三个负极活性物质层的负极活性物质的粒径不同且由内及外依次增大，第一负极活性物质层的负极活性物质为D50为5-10μm的人造石墨，第二负极活性物质层的负极活性物质为D50为8-12μm的人造石墨，第三负极活性物质层的负极活性物质D50为10-15μm的人造石墨。
第二方面，本发明提供一种制备本发明所述负极片的制作方法，该方法包括：(1)按照配方配置好含有第一负极活性物质的第一负极浆料、含有第二负极活性物质的第二负极浆料、含有第三负极活性物质的第三负极浆料 待用；
(2)将第一负极浆料涂覆在负极集流体上，干燥得第一卷料；
(3)将第二负极浆料涂覆在第一卷料上，干燥得第二卷料；
(4)将第三负极浆料涂覆在第二卷料上，干燥、辊压、冲片得负极片。
第三方面，本发明提供一种锂离子电池，所述锂离子电池包括：正极片、负极片、隔膜和电解液、正极极耳、负极极耳和铝塑膜，所述负极片为本发明所述的负极片。
第四方面，本发明提供一种锂离子电池的制备方法，该方法包括：
负极片的制备：按照本发明所述的方法制备负极片；
正极片的制备：将正极活性物质、正极导电剂、正极粘结剂、分散助剂与溶剂按照配方制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性：92-98％，正极导电剂1-5％，正极粘结剂1-5％，分散助剂0.1-1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂覆密度控制在2-3.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0-3.5g/cc；
电芯制备：将所得的正极片、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装；
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润；优选所述电芯烘烤的条件包括：温度80-85℃，时间20-28h；所述电芯静置的条件包括：温度25-30℃，时间40-48h；
电芯化成：将活化结束的电芯在温度为25-30℃，压力0.05-0.5MPa的条件下化成，所述化成步骤包括：先用0.02-0.05C的恒流充至3.6-3.8V，后用0.05-0.1C恒流充至3.8-3.9V，最后0.1-0.2C恒流恒压充至3.9-4.1V，截止 电流0.01C；
化成结束的电芯在45±2℃的环境下静置24-72h后进行抽气，抽气封边结束后的电芯进行0.33C充放分容。
第五方面，本发明提供本发明所述的锂离子电池在新能源汽车中的应用。
与现有相关技术相比，本发明公开的采用本发明负极片的锂离子电池具有快速充电且能量密度高等优势。本发明的锂离子电池能实现3.2C以上快速充电，且电池质量能量密度在260Wh/kg以上，3.2C快速充电循环2000圈容量保持率80％以上，满足电动汽车15min充满80％SOC快速充电、高续航和长生命周期的需求。
具体实施方式
在本文中所披露的范围的端点和任何值都不限于该精确的范围或值，这些范围或值应当理解为包含接近这些范围或值的值。对于数值范围来说，各个范围的端点值之间、各个范围的端点值和单独的点值之间，以及单独的点值之间可以彼此组合而得到一个或多个新的数值范围，这些数值范围应被视为在本文中具体公开。
本发明提供了一种负极片，所述负极片包括负极集流体和涂覆在负极集流体表面的负极活性物质层，所述负极活性物质层由内至外包括三层，其中，最内层作为第一负极活性物质层，由内及外依次编号为第二负极活性物质层和第三负极活性物质层，三个负极活性物质层的负极活性物质的粒径不同且由内及外依次增大，第一负极活性物质层的负极活性物质为D50为5-10μm的人造石墨，第二负极活性物质层的负极活性物质为D50为8-12μm的人造石墨，第三负极活性物质层的负极活性物质D50为10-15μm的人造石墨。
所述第一负极活性物质层涂覆在所述负极集流体上，所述第二负极活性物质层涂覆在所述第一负极活性物质层上，所述第三负极活性物质层涂覆在 所述第二负极活性物质层。
根据本发明的一种优选实施方式，所述负极活性物质层的压实为1.2-1.6g/cc，优选为1.3-1.5g/cc。所述负极活性物质层的压实密度可以为1.2g/cc、1.21g/cc、1.22g/cc、1.23g/cc、1.24g/cc、1.25g/cc、1.26g/cc、1.27g/cc、1.28g/cc、1.29g/cc、1.3g/cc、1.31g/cc、1.32g/cc、1.33g/cc、1.34g/cc、1.35g/cc、1.36g/cc、1.37g/cc、1.38g/cc、1.39g/cc、1.4g/cc、1.41g/cc、1.42g/cc、1.43g/cc、1.44g/cc、1.45g/cc、1.46g/cc、1.47g/cc、1.48g/cc、1.49g/cc、1.5g/cc、1.51g/cc、1.52g/cc、1.53g/cc、1.54g/cc、1.55g/cc、1.56g/cc、1.57g/cc、1.58g/cc、1.59g/cc、1.6g/cc。
在本申请中，所述负极活性物质层的压实密度是第一负极活性物质层、第二负极活性物质层以及第三负极活性物质层的平均压实密度。
所述第一负极活性物质层的负极活性物质的D50可以为5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm、8.5μm、9μm、9.5μm、10μm。
所述第二负极活性物质层的负极活性物质的D50可以为8μm、8.5μm、9μm、9.5μm、10μm、10.5μm、11μm、11.5μm、12μm。
所述第三负极活性物质层的负极活性物质的D50可以为10μm、10.5μm、11μm、11.5μm、12μm、12.5μm、13μm、13.5μm、14μm、14.5μm、15μm。
根据本发明，按照前述方案均可实现本发明目的，负极活性物质，负极导电剂，负极粘结剂和负极增稠剂的含量可选范围较宽，针对本发明，优选所述第一活性物质层、第二活性物质层和第三活性物质层各自包括：
负极活性物质：90-97重量％；负极导电剂：1-5重量％；负极粘结剂：1-6重量％；负极增稠剂：1-4重量％。
所述第一活性物质层、第二活性物质层和第三活性物质层各自包括的所述负极活性物质可以为90重量％、90.5重量％、91重量％、91.5重量％、92重量％、92.5重量％、93重量％、93.5重量％、94重量％、94.5重量％、95 重量％、95.5重量％、96重量％、96.5重量％、97重量％。
所述第一活性物质层、第二活性物质层和第三活性物质层各自包括的所述负极导电剂可以为1重量％、1.1重量％、1.2重量％、1.3重量％、1.4重量％、1.5重量％、1.6重量％、1.7重量％、1.8重量％、1.9重量％、2重量％、2.1重量％、2.2重量％、2.3重量％、2.4重量％、2.5重量％、2.6重量％、2.7重量％、2.8重量％、2.9重量％、3重量％、3.1重量％、3.2重量％、3.3重量％、3.4重量％、3.5重量％、3.6重量％、3.7重量％、3.8重量％、3.9重量％、4重量％、4.1重量％、4.2重量％、4.3重量％、4.4重量％、4.5重量％、4.6重量％、4.7重量％、4.8重量％、4.9重量％、5重量％。
所述第一活性物质层、第二活性物质层和第三活性物质层各自包括的负极粘结剂可以为1重量％、1.1重量％、1.2重量％、1.3重量％、1.4重量％、1.5重量％、1.6重量％、1.7重量％、1.8重量％、1.9重量％、2重量％、2.1重量％、2.2重量％、2.3重量％、2.4重量％、2.5重量％、2.6重量％、2.7重量％、2.8重量％、2.9重量％、3重量％、3.1重量％、3.2重量％、3.3重量％、3.4重量％、3.5重量％、3.6重量％、3.7重量％、3.8重量％、3.9重量％、4重量％、4.1重量％、4.2重量％、4.3重量％、4.4重量％、4.5重量％、4.6重量％、4.7重量％、4.8重量％、4.9重量％、5重量％、5.1重量％、5.2重量％、5.3重量％、5.4重量％、5.5重量％、5.6重量％、5.7重量％、5.8重量％、5.9重量％、6重量％。
所述第一活性物质层、第二活性物质层和第三活性物质层各自包括的负极增稠剂可以为1重量％、1.1重量％、1.2重量％、1.3重量％、1.4重量％、1.5重量％、1.6重量％、1.7重量％、1.8重量％、1.9重量％、2重量％、2.1重量％、2.2重量％、2.3重量％、2.4重量％、2.5重量％、2.6重量％、2.7重量％、2.8重量％、2.9重量％、3重量％、3.1重量％、3.2重量％、3.3重量％、3.4重量％、3.5重量％、3.6重量％、3.7重量％、3.8重量％、3.9重量％、4 重量％。
根据本发明，所述负极导电剂、负极粘结剂、负极增稠剂和负极集流体的物质的选择均可以使用公知的物质。
本发明意外发现，采用下述物质种类进行组合使用能够更好的实现本发明的目的，优选所述负极粘结剂为丁苯橡胶和/或聚丙烯酸锂，优选所述负极粘结剂为丁苯橡胶和聚丙烯酸锂的混合物。
根据本发明，优选所述聚丙烯酸锂的数均分子量为10-100万。
所述聚丙烯酸锂的数均分子量可以为10万、11万、12万、13万、14万、15万、16万、17万、18万、19万、20万、21万、22万、23万、24万、25万、26万、27万、28万、29万、30万、31万、32万、33万、34万、35万、36万、37万、38万、39万、40万、41万、42万、43万、44万、45万、46万、47万、48万、49万、50万、51万、52万、53万、54万、55万、56万、57万、58万、59万、60万、61万、62万、63万、64万、65万、66万、67万、68万、69万、70万、71万、72万、73万、74万、75万、76万、77万、78万、79万、80万、81万、82万、83万、84万、85万、86万、87万、88万、89万、90万、91万、92万、93万、94万、95万、96万、97万、98万、99万、100万。
根据本发明，优选所述负极导电剂为导电炭黑、碳纳米管、气相生成碳纤维、柯琴黑和石墨烯中的一种或多种。
根据本发明，优选所述负极增稠剂为羧甲基纤维素钠、聚偏氟乙烯、聚丙烯酸锂和聚丙烯腈中的一种或多种。
根据本发明，优选负极集流体为铜箔。
按照前述设置，负极片涂覆三层不同粒径范围的人造石墨可以明显提高负极片的性能，针对本发明优选所述负极片的制作方法，包括：
(1)按照配方配置好含有第一负极活性物质的第一负极浆料、含有第 二负极活性物质的第二负极浆料、含有第三负极活性物质的第三负极浆料待用；
(2)将第一负极浆料涂覆在负极集流体上，干燥得第一卷料；
(3)将第二负极浆料涂覆在第一卷料上，干燥得第二卷料；
(4)将第三负极浆料涂覆在第二卷料上，干燥、辊压、冲片得负极片。
根据本发明，优选负极浆料的总涂覆的密度1.2-2.2g/100cm 2，优选涂覆的密度各自为1.5-2g/100cm 2。
所述负极浆料的总涂覆的密度可以1.2g/100cm 2、1.3g/100cm 2、1.4g/100cm 2、1.5g/100cm 2、1.6g/100cm 2、1.7g/100cm 2、1.8g/100cm 2、1.9g/100cm 2、2g/100cm 2、2.1g/100cm 2、2.2g/100cm 2。
所述负极活性物质层涂覆的密度各自可以为1.5g/100cm 2、1.6g/100cm 2、1.7g/100cm 2、1.8g/100cm 2、1.9g/100cm 2、2g/100cm 2。
根据本发明，优选步骤(2)-(4)中，干燥的温度各自为60-100℃，例如干燥的温度各自可以为60℃、65℃、70℃、75℃、80℃、85℃、90℃、95℃、100℃。
根据本发明，优选步骤(4)中，辊压次数为2-3次。
本发明的负极片性能优良，用于锂离子电池时能实现3.2C以上快速充电，且电池质量能量密度在260Wh/kg以上，3.2C快速充电循环2000圈容量保持率80％以上，满足电动汽车15min充满80％SOC快速充电、高续航和长生命周期的需求。
根据本发明，提供一种锂离子电池，所述锂离子电池包括：正极片、负极片、隔膜和电解液、正极极耳、负极极耳和铝塑膜，所述负极片为本发明所述的负极片。
所述负极片采用本发明的负极片，其他的例如正极片、隔膜和电解液、正极极耳、负极极耳和铝塑均可以按照现有技术选择，针对本发明，根据一 种优选的实施方式，优选所述正极片包括正极集流体和涂覆在正极集流体上的正极活性物质层，所述正极活性物质层含有：正极活性物质：92-98重量％；正极导电剂：1-5重量％；正极粘结剂：1-5重量％；分散助剂0.1-1重量％。
所述正极活性物质层含有的正极活性物质可以为92重量％、93重量％、94重量％、95重量％、96重量％、97重量％、98重量％。
所述正极活性物质层含有的正极导电剂可以为1重量％、1.1重量％、1.2重量％、1.3重量％、1.4重量％、1.5重量％、1.6重量％、1.7重量％、1.8重量％、1.9重量％、2重量％、2.1重量％、2.2重量％、2.3重量％、2.4重量％、2.5重量％、2.6重量％、2.7重量％、2.8重量％、2.9重量％、3重量％、3.1重量％、3.2重量％、3.3重量％、3.4重量％、3.5重量％、3.6重量％、3.7重量％、3.8重量％、3.9重量％、4重量％、4.1重量％、4.2重量％、4.3重量％、4.4重量％、4.5重量％、4.6重量％、4.7重量％、4.8重量％、4.9重量％、5重量％。
所述正极活性物质层含有的正极粘接剂可以为1重量％、1.1重量％、1.2重量％、1.3重量％、1.4重量％、1.5重量％、1.6重量％、1.7重量％、1.8重量％、1.9重量％、2重量％、2.1重量％、2.2重量％、2.3重量％、2.4重量％、2.5重量％、2.6重量％、2.7重量％、2.8重量％、2.9重量％、3重量％、3.1重量％、3.2重量％、3.3重量％、3.4重量％、3.5重量％、3.6重量％、3.7重量％、3.8重量％、3.9重量％、4重量％、4.1重量％、4.2重量％、4.3重量％、4.4重量％、4.5重量％、4.6重量％、4.7重量％、4.8重量％、4.9重量％、5重量％。
所述正极活性物质层含有的分散助剂可以为0.1重量％、0.2重量％、0.3重量％、0.4重量％、0.5重量％、0.6重量％、0.7重量％、0.8重量％、0.9重量％、1重量％。
根据本发明，优选所述正极活性物质层的压实为3-3.5g/cc。
所述正极活性物质层的压实可以为3g/cc、3.1g/cc、3.2g/cc、3.3g/cc、3.4g/cc、3.5g/cc。
根据本发明，优选所述正极活性物质为NCM811和/或NCA，优选正极活性物质的粒径D50范围3-12μm。
所述正极活性物质的粒径D50可以为3μm、3.5μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm、8.5μm、9μm、9.5μm、10μm、10.5μm、11μm、11.5μm、12μm。
针对本发明，优选NCA，采用本发明，使用NCA作为正极活性物质，可知使用钴含量更低的配比，而事实上实现低钴化甚至无钴化是重要的降成本方式，比如91:3:6。
根据本发明，优选所述正极导电剂为炭黑、碳纳米管、碳纤维和石墨烯中的至少一种。
根据本发明，优选所述正极粘结剂为PVDF和/或PTEF；
根据本发明，优选所述分散助剂为聚乙烯吡咯烷酮。
根据本发明的一种优选的实施方式，所述正极极耳为铝极耳；所述负极极耳为铜镀镍极耳。
根据本发明的一种优选的实施方式，所述隔膜为PP膜、PE膜、PP-PE双层膜或PP-PE-PP三层膜。
根据本发明的一种优选的实施方式，所述电解液为含有锂盐、添加剂和有机溶剂的混合溶液。
根据本发明的一种优选实施方式，所述混合溶液中锂盐的浓度为0.8-1.2mol/L，添加剂的重量百分含量为0.5-4％。
所述混合溶液中锂盐的浓度可以为0.8mol/L、0.9mol/L、1mol/L、1.1mol/L、1.2mol/L。所述添加剂的重量百分含量可以为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％、3.1％、3.2％、3.3％、3.4％、3.5％、3.6％、3.7％、3.8％、3.9％、4％。
根据本发明的一种优选实施方式，锂盐为六氟磷酸锂和/或双(氟磺酰)亚胺锂。
根据本发明的一种优选实施方式，所述有机溶剂为碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯和碳酸甲乙酯中的一种或多种。
根据本发明的一种优选实施方式，所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、氟代碳酸乙烯酯、硫酸乙烯酯、1-丙烯-1,3-磺酸内酯、甲基二磺酸亚甲酯和二氟磷酸锂中的一种或多种。
根据本发明，提供一种锂离子电池的制备方法，该方法包括：
负极片的制备：按照本发明所述的方法制备负极片；
正极片的制备：将正极活性物质、正极导电剂、正极粘结剂、分散助剂与溶剂按照配方制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性：92-98％，正极导电剂1-5％，正极粘结剂1-5％，分散助剂0.1-1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂覆密度控制在2-3.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0-3.5g/cc；
电芯制备：将所得的正极片、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装；
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润；优选所述电芯烘烤的条件包括：温度80-85℃，时间20-28h；所述电芯静置的条件包括：温度25-30℃，时间40-48h；
电芯化成：将活化结束的电芯在温度为25-30℃，压力0.05-0.5MPa的 条件下化成，所述化成步骤包括：先用0.02-0.05C的恒流充至3.6-3.8V，后用0.05-0.1C恒流充至3.8-3.9V，最后0.1-0.2C恒流恒压充至3.9-4.1V，截止电流0.01C；
化成结束的电芯在45±2℃的环境下静置24-72h后进行抽气，抽气封边结束后的电芯进行0.33C充放分容。
按照前述方法制备的锂离子电池能够充分实现3.2C以上快速充电，且电池质量能量密度在260Wh/kg以上，3.2C快速充电循环2000圈容量保持率80％以上，满足电动汽车15min充满80％SOC快速充电、高续航和长生命周期的需求。
本发明中，D50指的是材料的累计粒度分布百分数达到50％时所对应的粒径。
本发明提供了本发明所述的锂离子电池在新能源汽车中的应用。
以下将通过实施例对本发明进行详细描述。
实施例1
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：97.7％，导电剂1％，粘结剂1.1％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在2.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0g/cc。所述正极活性物质为：NCM811和NCA的混合物(重量比为1：1)，其粒径D50范围7.5μm；所述导电剂为炭黑；所述粘结剂为PVDF；所述分散助剂为聚乙烯吡咯烷酮。
负极片制备：
将第一负极活性物质人造石墨(牌号CP7M，D50为8.2μm)、导电剂 碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔的两侧，涂布面密度控制在0.5g/100cm 2，干燥(条件60℃)得第一卷料；
将第二负极活性物质人造石墨(牌号QC8，D50为10.3μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第一卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件70℃)得第二卷料；
将第三负极活性物质人造石墨(牌号EH15X，D50为11.9μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第二卷料上，涂布面密度控制在0.6g/100cm 2，后经干燥(条件80℃)，辊压2次，冲片得到负极片，所述辊压的压实控制在1.5g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装，所述隔膜采用PP膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度80℃，时间28h，所述电 解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为0.8mol/L，锂盐为六氟磷酸锂，所述有机溶剂为碳酸乙烯酯、碳酸二乙酯和碳酸甲乙酯(三者体积比为3:3:4)；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯的混合物，电解液中添加剂的体积百分含量为4.0％(碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯五者的重量比分别为1％，1％，0.5％，1％和0.5％)，所述电芯静置的条件为：温度25℃，时间48h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置48h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
实施例2
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：96％，导电剂2.5％，粘结剂1.4％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在3g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.5g/cc。所述正极活性物质为：NCM811，其粒径D50范围8.5μm；所述导电剂为气相生成碳纤维；所述粘结剂为PTEF；所述分散助剂为聚乙烯吡咯烷酮(牌号PVP-K30)。
负极片制备：
将第一负极活性物质人造石墨(牌号CP5M，D50为7.2μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为5:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一 定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔的两侧，涂布面密度控制在0.6g/100cm 2，干燥(条件65℃)得第一卷料；
将第二负极活性物质人造石墨(牌号QC8，D50为10.3μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第一卷料上，涂布面密度控制在0.6g/100cm 2，后经干燥(条件75℃)得第二卷料；
将第三负极活性物质人造石墨(牌号P15-X，D50为13.6μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数均分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第二卷料上，涂布面密度控制在0.8g/100cm 2，后经干燥(条件85℃)，辊压3次，冲片得到负极片，所述辊压的压实控制在1.4g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装，所述隔膜采用PE膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度85℃，时间20h，所述电 解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为1.2mol/L，锂盐为六氟磷酸锂和双(氟磺酰)亚胺锂(其中，六氟磷酸锂浓度为1.0mol/L，双(氟磺酰)亚胺锂浓度为0.2mol/L)，所述有机溶剂为碳酸乙烯酯、碳酸二乙酯和碳酸甲乙酯的混合物(体积比为3:3:4)；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯的混合物，电解液中添加剂的体积百分含量为2.5％(碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯五者的重量比分别为1％，0.5％，0.2％，0.5％和0.3％)，所述电芯静置的条件为：温度30℃，时间40h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置48h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
实施例3
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：96％，导电剂2.5％，粘结剂1.4％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在2.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0g/cc。所述正极活性物质为：NCA，其粒径D50范围6.5μm；所述导电剂为炭黑；所述粘结剂为PVDF；所述分散助剂为聚乙烯吡咯烷酮。
负极片制备：
将第一负极活性物质人造石墨(牌号CP5M，D50为7.2μm)、导电剂 碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔的两侧，涂布面密度控制在0.6g/100cm 2，干燥(条件70℃)得第一卷料；
将第二负极活性物质人造石墨(牌号CAG-3MT，D50为10.7μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第一卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件80℃)得第二卷料；
将第三负极活性物质人造石墨(牌号P15-X，D50为13.6μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第二卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件90℃)，辊压2次，冲片得到负极片，所述辊压的压实控制在1.3g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装，所述隔膜采用PP-PE-PP膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制 200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度82℃，时间25h，所述电解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为1mol/L，锂盐为六氟磷酸锂和双(氟磺酰)亚胺锂的混合物(8:2)，所述有机溶剂为碳酸乙烯酯、碳酸二乙酯和碳酸甲乙酯(体积比为3:3:4)；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯，电解液中添加剂的体积百分含量为3％(碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯五者的重量比分别为0.5％，1％，0.5％，0.5％和0.5％)，所述电芯静置的条件为：温度28℃，时间45h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置45h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
实施例4
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：96％，导电剂2.5％，粘结剂1.4％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在2.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0g/cc。所述正极活性物质为：NCA，其粒径D50范围6.5μm；所述导电剂为炭黑；所述粘结剂为PVDF；所述分散助剂为聚乙烯吡咯烷酮。
负极片制备：
将第一负极活性物质人造石墨(牌号CP5M，D50为7.2μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔的两侧，涂布面密度控制在0.6g/100cm 2，干燥(条件70℃)得第一卷料；
将第二负极活性物质人造石墨(牌号CAG-3MT，D50为10.7μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第一卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件80℃)得第二卷料；
将第三负极活性物质人造石墨(牌号P15-X，D50为13.6μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第二卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件90℃)，辊压2次，冲片得到负极片，所述辊压的压实控制在1.2g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装，所述隔膜采用PP-PE-PP膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度82℃，时间25h，所述电解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为1mol/L，锂盐为六氟磷酸锂和双(氟磺酰)亚胺锂的混合物(8:2)，所述有机溶剂为碳酸乙烯酯、碳酸二乙酯和碳酸甲乙酯(体积比为3:3:4)；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯，电解液中添加剂的体积百分含量为3％(碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯五者的重量比分别为0.5％，1％，0.5％，0.5％和0.5％)，所述电芯静置的条件为：温度28℃，时间45h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置45h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
实施例5
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：96％，导电剂2.5％，粘结剂1.4％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在2.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0g/cc。所述正极活性物质为：NCA，其粒径D50范围6.5μm；所述导电剂为炭黑；所述粘结剂为PVDF；所述分散助剂为聚乙烯吡咯烷酮。
负极片制备：
将第一负极活性物质人造石墨(牌号CP5M，D50为7.2μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔的两侧，涂布面密度控制在0.6g/100cm 2，干燥(条件70℃)得第一卷料；
将第二负极活性物质人造石墨(牌号CAG-3MT，D50为10.7μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第一卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件80℃)得第二卷料；
将第三负极活性物质人造石墨(牌号P15-X，D50为13.6μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第二卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件90℃)，辊压2次，冲片得到负极片，所述辊压的压实控制在1.6g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的 铝塑膜内进行封装，所述隔膜采用PP-PE-PP膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度82℃，时间25h，所述电解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为1mol/L，锂盐为六氟磷酸锂和双(氟磺酰)亚胺锂的混合物(8:2)，所述有机溶剂为碳酸乙烯酯、碳酸二乙酯和碳酸甲乙酯(体积比为3:3:4)；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯，电解液中添加剂的体积百分含量为3％(碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯五者的重量比分别为0.5％，1％，0.5％，0.5％和0.5％)，所述电芯静置的条件为：温度28℃，时间45h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置45h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
对比例1
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：96％，导电剂2.5％，粘结剂1.4％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在3.6g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.5g/cc。所述正极活性物质为：NCM811，其粒径D50为12.5μm；所述导电剂为炭黑；所述粘 结剂为PVDF；所述分散助剂为聚乙烯吡咯烷酮。
负极片制备：
将负极活性物质人造石墨(牌号P15，D50为15.4μm)、导电剂碳纳米管、粘结剂丁苯橡胶、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔上，涂布面密度控制在2.4g/100cm 2，后经80℃干燥，辊压1次，冲片得到负极片，所述辊压的压实控制在1.6g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装，所述隔膜采用PP膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度80℃，时间24h，所述电解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为1mol/L，锂盐为六氟磷酸锂，所述有机溶剂为碳酸乙烯酯和碳酸甲乙酯，比例为1:4；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯，电解液中添加剂的体积百分含量分别为1％和1％，所述电芯静置的条件为：温度25℃，时间24h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置24h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
对比例2
正极片制备：将正极活性物质、导电剂、粘结剂、分散助剂与溶剂按一定比例制成正极浆料，所述正极浆料干粉中，按质量百分比计，正极活性物质比例为：96％，导电剂2.5％，粘结剂1.4％，分散助剂0.1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂布面密度控制在2.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0g/cc。所述正极活性物质为：NCA，其粒径D50范围6.5μm；所述导电剂为炭黑；所述粘结剂为PVDF；所述分散助剂为聚乙烯吡咯烷酮。
负极片制备：
将第一负极活性物质人造石墨(牌号CP5M，D50为15μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在铜箔的两侧，涂布面密度控制在0.6g/100cm 2，干燥(条件70℃)得第一卷料；
将第二负极活性物质人造石墨(牌号CAG-3MT，D50为20μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第一卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件80℃)得第二卷料；
将第三负极活性物质人造石墨(牌号P15-X，D50为25μm)、导电剂碳纳米管、粘结剂丁苯橡胶和聚丙烯酸锂的混合物(质量比为1:1，聚丙烯 酸锂的数据分子量为50万)、增稠剂羧甲基纤维素钠与溶剂去离子水按一定比例制成负极浆料，所述负极浆料干粉中，按质量百分比计，负极活性物质比例为：95.5％，导电剂1％，粘结剂2％，增稠剂1.5％；将制得的负极浆料均匀地涂覆在第二卷料上，涂布面密度控制在0.5g/100cm 2，后经干燥(条件90℃)，辊压2次，冲片得到负极片，所述辊压的压实控制在1.6g/cc。
电芯制备：将所得的正、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，利用超声波焊接机将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装，所述隔膜采用PP-PE-PP膜。
电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润。所述电芯烘烤的条件为：温度82℃，时间25h，所述电解液为锂盐、添加剂和有机溶剂的混合溶液，所述混合溶液中锂盐的浓度为1mol/L，锂盐为六氟磷酸锂和双(氟磺酰)亚胺锂的混合物(8:2)，所述有机溶剂为碳酸乙烯酯、碳酸二乙酯和碳酸甲乙酯(体积比为3:3:4)；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯，电解液中添加剂的体积百分含量为3％(碳酸亚乙烯酯、亚硫酸丙酯、硫酸乙烯酯和二氟磷酸锂和1-丙烯-1,3-磺酸内酯五者的重量比分别为0.5％，1％，0.5％，0.5％和0.5％)，所述电芯静置的条件为：温度28℃，时间45h。
电芯化成：将活化结束的电芯在温度为25℃，压力扭矩8牛米的条件下化成，所述化成工步为：先用0.05C恒流充至3.6V，后用0.1C恒流充至3.8V，最后0.2C恒流恒压充至3.9V，截止电流0.01C。
化成结束的电芯在45±2℃的环境下静置45h后进行Degas抽气，抽气封边结束后的电芯进行0.33C充放分容。
对实施例和对比例中的电芯称重并计算对应的0.33C能量密度；然后电芯进行快充循环寿命测试，测试方法为25℃环境温度下，以平均3.2C倍率快速充电至80％SOC，之后1C放电，进行充放循环测试，同时记录循环过程中电芯本体温度，测试效果如表2所示。
表1为各实施例以及对比例的参数
Figure PCTCN2020112604-appb-000001
表2为各实施例以及对比例的性能参数
  0.33C能量密度(Wh/kg) 25℃快充循环寿命(次) 3.2C快充过程中电芯最高温(℃)
实施例1 263.3 2632 42.5
实施例2 265.4 2249 44.7
实施例3 261.8 2563 43.1
实施例4 260.6 2244 44.5
实施例5 267.2 2033 48.7
对比例1 268.6 1435 56.3
对比例2 267.2 850 65.7
小结：由表2可知，实施例的小粒径石墨和三层不同粒径石墨涂覆的搭配，相比对比例，电池的循环寿命大幅度提高，快充充电过程中的温升大幅度降低。
对比实施例1和实施例2，表明降低石墨的粒径，有利于提升电池的循环寿命和降低快充温升。对比实施例3、4和5，其中实施例3的能量密度和实施例4和5相当，但是循环寿命更好，快充温升更低，表明合适的负极压实设计有利于达到本发明的目标。
本发明的负极片性能优良，用于锂离子电池时能实现3.2C以上快速充电，且电池质量能量密度在260Wh/kg以上，3.2C快速充电循环2000圈容量保持率80％以上，而且快充过程中温升低，有利于电池热管理，满足电动汽车15min充满80％SOC快速充电、高续航和长生命周期的需求。
以上详细描述了本发明的优选实施方式，但是，本发明并不限于此。在本发明的技术构思范围内，可以对本发明的技术方案进行多种简单变型，包括各个技术特征以任何其它的合适方式进行组合，这些简单变型和组合同样应当视为本发明所公开的内容，均属于本发明的保护范围。

Claims (11)

  1. 一种负极片，所述负极片包括负极集流体和涂覆在负极集流体表面的负极活性物质层，其特征在于，所述负极活性物质层由内至外包括三层，其中，最内层作为第一负极活性物质层，由内及外依次编号为第二负极活性物质层和第三负极活性物质层，三个负极活性物质层的负极活性物质的粒径不同且由内及外依次增大，第一负极活性物质层的负极活性物质为D50为5-10μm的人造石墨，第二负极活性物质层的负极活性物质为D50为8-12μm的人造石墨，第三负极活性物质层的负极活性物质D50为10-15μm的人造石墨。
  2. 根据权利要求1所述的负极片，其中，所述负极活性物质层的压实为1.2-1.6g/cc，优选为1.3-1.5g/cc。
  3. 根据权利要求1或2所述的负极片，其中，所述第一活性物质层、第二活性物质层和第三活性物质层各自包括：
    负极活性物质：90-97重量％；
    负极导电剂：1-5重量％；
    负极粘结剂：1-6重量％；
    负极增稠剂：1-4重量％；
    所述负极粘结剂为丁苯橡胶和/或聚丙烯酸锂，优选所述负极粘结剂为丁苯橡胶和聚丙烯酸锂的混合物；
    优选所述聚丙烯酸锂的数均分子量为10-100万；
    所述负极导电剂为导电炭黑、碳纳米管、气相生成碳纤维、柯琴黑和石墨烯中的一种或多种；
    所述负极增稠剂为羧甲基纤维素钠、聚偏氟乙烯、聚丙烯酸锂和聚丙烯腈中的一种或多种；
    负极集流体为铜箔。
  4. 一种制备权利要求1-3中任意一项所述负极片的制作方法，该方法包括：
    (1)按照配方配置好含有第一负极活性物质的第一负极浆料、含有第二负极活性物质的第二负极浆料、含有第三负极活性物质的第三负极浆料待用；
    (2)将第一负极浆料涂覆在负极集流体上，干燥得第一卷料；
    (3)将第二负极浆料涂覆在第一卷料上，干燥得第二卷料；
    (4)将第三负极浆料涂覆在第二卷料上，干燥、辊压、冲片得负极片。
  5. 根据权利要求4所述的方法，其中，
    负极浆料的总涂覆的密度1.2-2.2g/100cm 2；
    步骤(2)-(4)中，干燥的温度各自为60-100℃；
    步骤(4)中，辊压次数为2-3次。
  6. 一种锂离子电池，所述锂离子电池包括：正极片、负极片、隔膜和电解液、正极极耳、负极极耳和铝塑膜，其特征在于，所述负极片为权利要求1-3中任意一项所述的负极片。
  7. 根据权利要求6所述的锂离子电池，其中，所述正极片包括正极集流体和涂覆在正极集流体上的正极活性物质层，所述正极活性物质层含有：
    正极活性物质：92-98重量％；
    正极导电剂：1-5重量％；
    正极粘结剂：1-5重量％；
    分散助剂0.1-1重量％；
    所述正极活性物质层的压实为3-3.5g/cc。
  8. 根据权利要求6或7所述的锂离子电池，其中，所述正极活性物质为NCM811和/或NCA，优选为NCA，优选正极活性物质的粒径D50范围3-12μm；
    所述正极导电剂为炭黑、碳纳米管、碳纤维和石墨烯中的至少一种；
    所述正极粘结剂为PVDF和/或PTEF；
    所述分散助剂为聚乙烯吡咯烷酮。
  9. 根据权利要求6或7所述的锂离子电池，其中，
    所述正极极耳为铝极耳；
    所述负极极耳为铜镀镍极耳；
    所述隔膜为PP膜、PE膜、PP-PE双层膜或PP-PE-PP三层膜；
    所述电解液为含有锂盐、添加剂和有机溶剂的混合溶液；
    所述混合溶液中锂盐的浓度为0.8-1.2mol/L，添加剂的重量百分含量为0.5-4％；锂盐为六氟磷酸锂和/或双(氟磺酰)亚胺锂，所述有机溶剂为碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯和碳酸甲乙酯中的一种或多种；所述添加剂为碳酸亚乙烯酯、亚硫酸丙酯、氟代碳酸乙烯酯、硫酸乙烯酯、1-丙烯-1,3-磺酸内酯、甲基二磺酸亚甲酯和二氟磷酸锂中的一种或多种。
  10. 一种锂离子电池的制备方法，该方法包括：
    负极片的制备：按照权利要求4-5任意一项所述的方法制备负极片；
    正极片的制备：将正极活性物质、正极导电剂、正极粘结剂、分散助剂与溶剂按照配方制成正极浆料，所述正极浆料干粉中，按质量百分比计，正 极活性：92-98％，正极导电剂1-5％，正极粘结剂1-5％，分散助剂0.1-1％；将制得的正极浆料均匀地涂覆在铝箔的两侧，涂覆密度控制在2-3.5g/100cm 2，后经过干燥、辊压、冲片得到正极片，所述辊压的压实控制在3.0-3.5g/cc；
    电芯制备：将所得的正极片、负极片经过干燥后，与隔膜按照隔膜-负极片-隔膜-正极片-隔膜-负极片的顺序依次叠成电芯，将正极铝极耳与负极铜镀镍极耳焊接在电芯上，并将焊接完成的电芯放入已冲坑好的铝塑膜内进行封装；
    电芯注液：将封装好的电芯烘烤后注入电解液，注液前电芯水分控制200ppm以下，注液后封口并将电芯静置活化，使电解液能将正极片、负极片与隔膜充分浸润；优选所述电芯烘烤的条件包括：温度80-85℃，时间20-28h；所述电芯静置的条件包括：温度25-30℃，时间40-48h；
    电芯化成：将活化结束的电芯在温度为25-30℃，压力0.05-0.5MPa的条件下化成，所述化成步骤包括：先用0.02-0.05C的恒流充至3.6-3.8V，后用0.05-0.1C恒流充至3.8-3.9V，最后0.1-0.2C恒流恒压充至3.9-4.1V，截止电流0.01C；
    化成结束的电芯在45±2℃的环境下静置24-72h后进行抽气，抽气封边结束后的电芯进行0.33C充放分容。
  11. 权利要求6-9中任意一项所述的锂离子电池在新能源汽车中的应用。
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