WO2023016047A1 - 负极材料及其制备方法、锂离子电池 - Google Patents

负极材料及其制备方法、锂离子电池 Download PDF

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WO2023016047A1
WO2023016047A1 PCT/CN2022/094963 CN2022094963W WO2023016047A1 WO 2023016047 A1 WO2023016047 A1 WO 2023016047A1 CN 2022094963 W CN2022094963 W CN 2022094963W WO 2023016047 A1 WO2023016047 A1 WO 2023016047A1
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Prior art keywords
carbon
treatment
aggregate
negative electrode
active material
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English (en)
French (fr)
Inventor
何鹏
肖称茂
郭锷明
任建国
贺雪琴
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BTR New Material Group Co Ltd
Dingyuan New Energy Technology Co Ltd
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BTR New Material Group Co Ltd
Dingyuan New Energy Technology Co Ltd
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Priority to US18/043,189 priority Critical patent/US20230378474A1/en
Priority to KR1020227043814A priority patent/KR20230025399A/ko
Priority to EP22855033.1A priority patent/EP4187642A4/en
Priority to JP2022573360A priority patent/JP2023539978A/ja
Publication of WO2023016047A1 publication Critical patent/WO2023016047A1/zh
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Priority to MA64626A priority patent/MA64626A1/fr
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    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H—ELECTRICITY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
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    • 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
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
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    • 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
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    • H01M4/00—Electrodes
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
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    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
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    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/5835—Comprising fluorine or fluoride salts
    • H—ELECTRICITY
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    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of negative electrode materials, in particular, to negative electrode materials, their preparation methods, and lithium-ion batteries.
  • lithium-ion batteries have been widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life and low environmental pollution.
  • silicon-carbon anode materials have been partially used in power and other fields, but the first-time efficiency requirements of the anode are relatively high in full-battery applications.
  • the initial efficiency of graphite anodes is generally above 93%, and the initial efficiency of silicon anode materials is usually around 80% to 85%, which leads to poor performance of the negative electrode gram capacity in the design of finished batteries.
  • the present application provides negative electrode materials and preparation methods thereof, and lithium-ion batteries, which are beneficial to improving the primary efficiency of negative electrode materials, and the preparation method can simplify the process and reduce production costs.
  • the embodiment of the present application provides a negative electrode material, including an aggregate, and the aggregate includes an active material, a carbon material, and a doping element;
  • the obtained Raman image shows that the G band is observed from 1530 cm -1 to 1630 cm -1 and the D band is observed from 1280 cm -1 to 1380 cm -1 , and the peak intensity ID of the D band is the same as that of the G band I
  • the ratio I D /I G between G is 1-2.5.
  • the embodiment of the present application provides a negative electrode material, including aggregates, the aggregates include active materials, carbon materials, and doping elements, and the doping elements can induce the carbon materials to generate Lewis acid active sites , at least part of the active material is combined with the carbon material through the Lewis acid active site.
  • the doping element includes at least one of fluorine, nitrogen and phosphorus.
  • At least one of the active material and the carbon material contains the doping element.
  • the doping element is distributed on the surface and/or inside of the active material.
  • the doping element is distributed on the surface and/or inside of the carbon material.
  • the content of the doping element in the aggregate is 50 ppm ⁇ 20000 ppm.
  • pores are formed between the carbon materials, and at least part of the active material is filled in the pores.
  • the pore volume of the carbon material is ⁇ 0.35 cm 3 /g.
  • the active material is distributed between or on the surface of the carbon materials.
  • the active material includes active particles.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, Fe, Mg, Ti, Zn, Al, P, Cu and SiOx , wherein, 0 ⁇ x ⁇ 2.
  • the median particle size of the active material is 1 nm to 300 nm.
  • the carbon material includes at least one of crystalline carbon, amorphous carbon, artificial graphite, natural graphite, soft carbon, hard carbon, amorphous carbon, carbon nanotube, carbon fiber and graphene.
  • the mass ratio of the active material to the carbon material is (90-10):(10-90).
  • the aggregates further include metal oxides.
  • At least part of the metal oxide is filled in the pores between the carbon materials.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, At least one of Mg, Al, Ca and Zn.
  • the metal oxide includes any one of GeO 2 , SnO 2 , ZnO, TiO 2 , Fe 3 O 4 , MgO, SiO 2 and CuO.
  • the mass ratio of the active material to the metal oxide is (30-100):(0.5-10).
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2.
  • the shortest distance between the metal oxides is greater than or equal to 100 nm.
  • the aggregate further includes a conductivity enhancer.
  • At least part of the conductivity enhancer is filled in pores between the carbon materials.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • the conductivity enhancer includes at least one of an alloy material and conductive carbon
  • the conductive carbon includes at least one of carbon nanotubes, carbon fibers and graphite fibers.
  • the electrical conductivity of the electrical conductivity enhancer is 10 0 S/m ⁇ 10 8 S/m.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the mass ratio of the conductivity enhancer to the active material is (0.01-15):(50-100).
  • the aspect ratio of the conductivity enhancer is 2-5000.
  • the negative electrode material further includes a carbon layer covering at least part of the surface of the aggregate.
  • the material of the carbon layer includes amorphous carbon.
  • the thickness of the carbon layer is 10 nm to 5000 nm.
  • the mass ratio of the aggregates to the carbon layer is (90-10):(10-90).
  • the negative electrode material further includes an oxide layer formed on at least part of the surface of the active material.
  • the thickness of the oxide layer is 1 nm ⁇ 100 nm.
  • the oxide layer has pores.
  • the median particle size of the negative electrode material is 0.5 ⁇ m-30 ⁇ m.
  • the specific surface area of the negative electrode material is ⁇ 10m 2 /g.
  • the porosity of the aggregate is ⁇ 10%.
  • the compressive hardness of the aggregate is ⁇ 100 MPa.
  • the aggregate density satisfies the following relationship: ( ⁇ 1- ⁇ 2)/ ⁇ 2 ⁇ 5%, wherein ⁇ 1 is the test density of the aggregate, ⁇ 2 is the average density of the aggregate, and the ⁇ 2 is The sum of the mass percentage of each component in the aggregate * the theoretical density of each component in the aggregate.
  • the embodiment of the present application provides a method for preparing an anode material, the method comprising the following steps:
  • the precursor is subjected to a heat treatment at 800° C. to 980° C. to obtain aggregates.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, Fe, Mg, Ti, Zn, Al, P, Cu and SiOx , wherein, 0 ⁇ x ⁇ 2.
  • the dopant includes at least one of a fluorine source, a phosphorus source and a nitrogen source.
  • the dopant includes at least one of a fluorine source, a phosphorus source, and a nitrogen source
  • the fluorine source includes fluoride
  • the fluoride includes hydrogen fluoride, lithium fluoride, fluoride Ammonium, potassium fluoride, aluminum fluoride, magnesium fluoride, sodium fluoride, calcium fluoride, tetrabutylammonium fluoride, triethylmethoxymethylammonium fluoride, ammonium fluoroborate and tetrabutylammonium fluoroborate at least one of the
  • the dopant includes at least one of a fluorine source, a phosphorus source, and a nitrogen source
  • the phosphorus source includes triphenylphosphine, tetraphenylphosphine bromide, 1-butyl - at least one of 3-methylimidazole sodium hexafluorophosphate, phosphine, sodium phosphate, sodium phosphite, elemental phosphorus, sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium hydrogen phosphite and phosphoric acid.
  • the dopant includes at least one of a fluorine source, a phosphorus source, and a nitrogen source
  • the nitrogen source includes ammonia gas, ammonium chloride, ammonium carbonate, ammonium bicarbonate, urea, At least one of thiourea, lithium nitride, melamine and hydrazine hydrate.
  • the first carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polycyclic At least one of oxyethane, polyvinylidene fluoride, polyacrylonitrile, polyvinyl chloride and asphalt.
  • the mass ratio of the active material, the dopant and the first carbon source is (30-120):(0.9-20):(10-50).
  • the solvent includes an organic solvent.
  • the solvent includes an organic solvent
  • the organic solvent includes at least one of ethanol, ethylene glycol, propanol, butanol and n-pentanol.
  • the step of mixing the active material, the dopant, the first carbon source and the solvent is specifically: dispersing the active material in the solvent and then adding the dopant and the first carbon source .
  • additives are also added in the step of mixing the active material, the dopant, the first carbon source and the solvent.
  • the additive includes at least one of a surfactant and a coupling agent.
  • the additive includes a surfactant, and the surfactant includes n-octadecanoic acid, lauric acid, polyacrylic acid, sodium dodecylbenzenesulfonate, n-eicosic acid, palmitic acid , myristic acid, undecanoic acid, cetyltrimethylammonium bromide and at least one of polyvinylpyrrolidone.
  • the surfactant includes n-octadecanoic acid, lauric acid, polyacrylic acid, sodium dodecylbenzenesulfonate, n-eicosic acid, palmitic acid , myristic acid, undecanoic acid, cetyltrimethylammonium bromide and at least one of polyvinylpyrrolidone.
  • the additive includes a coupling agent, and the coupling agent includes a silane coupling agent, and the silane coupling agent includes ⁇ -aminopropyltriethoxysilane, ⁇ -glycidol At least one of etheroxypropyltrimethoxysilane and ⁇ -methacryloxypropyltrimethoxysilane.
  • the mass ratio of the additive to the active substance is (0.01-5): (50-100).
  • At least one of a metal oxide and a conductivity enhancer is further added in the step of mixing the active material, the dopant, the first carbon source and the solvent.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, At least one of Mg, Al, Ca and Zn.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2.
  • the mass ratio of the metal oxide to the active material is (0.5-10):(30-100).
  • the mass ratio of the conductivity enhancer to the active material is (0.01-15):(50-100).
  • the electrical conductivity of the electrical conductivity enhancer is 10 0 S/m ⁇ 10 8 S/m.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the aspect ratio of the conductivity enhancer is 2-5000.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • the step of preparing the precursor further includes mixing the active material, the dopant, the first carbon source, and the solvent, and then performing at least one of dispersion treatment and drying treatment.
  • the dispersion treatment includes at least one of mechanical stirring, ultrasonic dispersion and grinding dispersion.
  • the temperature of the drying treatment is 30°C-400°C.
  • the time for the drying treatment is 1 hour to 15 hours.
  • the precursor before performing a heat treatment on the precursor, it further includes performing a densification treatment on the precursor, so that the porosity of the aggregate is ⁇ 10% and the compressive hardness is ⁇ 100 MPa.
  • the densification treatment includes at least one of fusion treatment, kneading and extrusion treatment, molding treatment, isostatic pressing treatment and dipping treatment.
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment and dipping treatment, and the fusion treatment is mechanical fusion.
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment and dipping treatment, the fusion treatment is mechanical fusion, and the mechanical The rotating speed of the fusion machine used for fusion is 500r/min ⁇ 3000r/min.
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment and dipping treatment, the fusion treatment is mechanical fusion, and the mechanical The fusion machine tool gap width used for fusion is 0.01cm-0.5cm.
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment and dipping treatment, the fusion treatment is mechanical fusion, and the mechanical The fusion time is at least 0.5h.
  • the time for the one heat treatment is 1 h to 5 h.
  • the primary heat treatment is performed in a first protective atmosphere.
  • the primary heat treatment is carried out in a first protective atmosphere
  • the gas in the first protective atmosphere includes at least one of nitrogen, helium, neon, argon and krypton .
  • the method further includes performing carbon coating treatment on the aggregate.
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source for secondary heat treatment.
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source for secondary heat treatment, and the second carbon source includes sucrose, glucose, polyethylene, poly At least one of vinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polyvinyl chloride and asphalt.
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source for secondary heat treatment, the mass ratio of the aggregate to the second carbon source being (20 ⁇ 100): (10 ⁇ 80).
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source to perform secondary heat treatment, the temperature of the secondary heat treatment being 800°C-900°C.
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source to perform a second heat treatment, and the time of the second heat treatment is 1 hour to 5 hours.
  • the step of the carbon coating treatment includes: mixing the aggregate with a second carbon source to perform a secondary heat treatment, and the secondary heat treatment is performed in a second protective atmosphere.
  • the step of the carbon coating treatment includes: mixing the aggregate with a second carbon source for secondary heat treatment, the secondary heat treatment is performed in a second protective atmosphere, the The gas of the second protective atmosphere includes at least one of nitrogen, helium, neon, argon and krypton.
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source for secondary heat treatment, and after the secondary heat treatment, crushing, sieving and removing at least one of magnetic;
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source for secondary heat treatment, and after the secondary heat treatment, crushing, sieving and removing At least one of magnetic, the mesh size of the sieve is ⁇ 500 mesh.
  • the embodiment of the present application provides a lithium-ion battery
  • the lithium-ion battery includes the negative electrode material described in the first aspect or the second aspect, or the negative electrode material prepared by the preparation method described in the third aspect.
  • the addition of doping elements can promote the combination of the carbon material and the active material, and can increase the degree of graphitization of the carbon material, thereby improving electrical conductivity.
  • Doping elements induce active sites with high activity and selectivity in carbon materials. On the one hand, these active sites are easier to combine with the surface of the active material to form a more stable connection; on the other hand, due to the increased activity, the energy The barrier is reduced, the rearrangement resistance of carbon atoms is reduced, and it is easier to form an ordered arrangement during the high-temperature heat treatment process, which is manifested by an increase in the local short-range order and a partial increase in the degree of graphitization.
  • the preparation method provided by the present application is simple to operate and can be applied to scale-up production.
  • the prepared negative electrode material can effectively improve the stability of lithium battery charging and discharging cycles and effectively reduce the expansion rate of the negative electrode material.
  • FIG. 1 is a flowchart of a method for preparing an anode material according to an embodiment.
  • the negative electrode material of one embodiment comprises aggregates, and aggregates comprise active material, carbon material and dopant element, and carbon material is shown in the Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532nm, at 1530cm -1 to 1630cm -1 observed the G band and 1280cm -1 to 1380cm -1 observed the D band, and the ratio between the peak intensity ID of the D band and the peak intensity I G of the G band I D / I G is 1 ⁇ 2.5.
  • the doping elements in this embodiment induce active sites with high activity and selectivity in the carbon material.
  • these active sites are more easily combined with the surface of the active material to form a more stable connection; on the other hand, due to The activity increases, the energy barrier decreases, the rearrangement resistance of carbon atoms decreases, and it is easier to form an ordered arrangement during the high-temperature heat treatment process, which is manifested as an increase in the local short-range order degree, and a partial increase in the degree of graphitization, thereby improving the conductivity of the carbon material.
  • I D / IG may be 1, 1.2, 1.5, 1.7, 1.8, 2, 2.1, 2.2 or 2.5, and of course may also be other values within the above range, which are not limited herein.
  • ID / IG is 1.7-2.3, and carbon materials with a degree of graphitization within this range have better electronic conductivity.
  • An anode material in one embodiment includes an aggregate, the aggregate includes an active material, a carbon material, and a doping element, the doping element can induce the carbon material to generate a Lewis acid active site, and at least part of the active material interacts with the Lewis acid active site through the Lewis acid active site. combination of carbon materials.
  • doping elements can promote the combination of carbon materials and active materials, and in addition can increase the degree of graphitization of carbon materials, thereby improving electrical conductivity.
  • the electronegativity difference between the doping element and the carbon atom is very large, the introduction of the doping element makes the charge distribution of the carbon atom uneven, generates Lewis acid sites, and induces high activity and selectivity in the carbon material.
  • these active sites are easier to combine with the surface of active substances to form a more stable connection. Based on this principle, the closer the doping element is to the surface of the carbon material or active material, the easier it is to induce the carbon material to generate Lewis acid sites.
  • the doping elements exist in the aggregates in the form of atoms, and the doping elements in the form of atoms can be observed with a transmission electron microscope and a high-angle annular dark-field scanning transmission electron microscope.
  • the doping element includes at least one of fluorine, nitrogen and phosphorus; it can be understood that the doping element can be fluorine, nitrogen or phosphorus; it can also be a combination of fluorine and nitrogen or a combination of fluorine and phosphorus or A combination of nitrogen and phosphorus; it can also contain fluorine, nitrogen and phosphorus at the same time.
  • the content of the dopant element in the aggregate is 50 ppm to 20000 ppm.
  • the content of doping elements can be specifically 50ppm, 100ppm, 500ppm, 1000ppm, 2000ppm, 4000ppm, 5000ppm, 10000ppm, 20000ppm, etc.; of course, it can also be other values within the above range, which is not limited here. Within this range, the degree of graphitization of the carbon material can be effectively improved, which is beneficial to improving the stability of the interface of the active material, thereby improving the cycle stability of the material; the initial efficiency, expansion rate, and cycle life of the negative electrode material are all improved.
  • the content of doping elements can be obtained by testing methods such as ion chromatography, component analysis or energy spectrum analysis (EDX analysis).
  • At least one of the active material and the carbon material contains a doping element.
  • the dopant element is distributed on the surface and/or inside the active material.
  • the doping elements are located inside the distributed active material, part of the doping elements replace the atoms in the crystal structure of the material and form valence bonds with adjacent atoms, and part of the doping elements are distributed in the lattice defects in the crystal structure.
  • fluorine elements replace silicon atoms in the silicon crystal structure, and form fluorine-silicon bonds with adjacent silicon atoms, and can also be distributed in lattice defects in the crystal structure of silicon-based materials.
  • the doping elements are distributed on the surface and/or inside the carbon material.
  • part of the doping element replaces the atoms in the crystal structure of the carbon material and forms a valence bond with the adjacent carbon atom, and part of the doping element is distributed in the lattice defects in the carbon crystal structure middle.
  • the dopant element is not only distributed on the surface and/or inside of the active material, but also on the surface and/or inside of the carbon material.
  • doping content of doping elements is extremely low, it is not enough to form a long-range ordered structure, and will not cause major changes in the crystal structure of the material itself, so that the structural stability of the material can be better maintained.
  • the active material in the aggregate, is distributed between or on the surface of the carbon materials, preferably, the active material is uniformly dispersed in the carbon material.
  • pores are formed between the carbon materials, and the pores are filled with at least part of the active material; this filling method can effectively utilize the pores formed between the carbon materials, so that the active material dispersed in the pores is filled.
  • the discharge volume changes, it has a certain deformation space, which reduces the stress damage caused by the volume change.
  • the carbon material has a pore volume > 0.35 cm 3 /g.
  • the pore volume of the carbon material includes the pore volume of the pore structure formed between the carbon material and the pore volume of the porous carbon material (the porous structure of the carbon material itself). It has a pore volume of not less than 0.35cm 3 /g.
  • the internal pores can well accommodate the active material and reserve space for the expansion of the active material; on the other hand, the appropriate pore volume can be used in the subsequent carbon coating In the process, more channels are provided for the infiltration of carbon coated on the surface, which is beneficial to the coating of carbon.
  • the pore volume of carbon materials was tested by the gas adsorption BET method.
  • the active material includes active particles.
  • the active material refers to a material that can react with lithium to perform lithium intercalation and deintercalation.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, Fe, SiO x (0 ⁇ x ⁇ 2), Mg, Ti, Zn, Al, P, and Cu; the active material can be It is a single metal.
  • the active material can specifically be Si particles, Sn particles, Ge particles, and Al particles.
  • the active material can also be silicon-lithium alloys, silicon-magnesium alloys, etc. Of course, it needs to be explained Yes, in some cases, active materials include elemental particles and alloys.
  • the median diameter of the active material is 1 nm to 300 nm. Specifically, it can be 1nm, 5nm, 10nm, 50nm, 75nm, 100nm, 150nm, 200nm, 250nm, 300nm, etc., without limitation.
  • the carbon material includes at least one of crystalline carbon, amorphous carbon, artificial graphite, natural graphite, soft carbon, hard carbon, amorphous carbon, carbon nanotube, carbon fiber, and graphene.
  • the mass ratio of the active material to the carbon material is (90-10):(10-90). Specifically, it can be 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, etc., without limitation.
  • the porosity of the aggregate is ⁇ 10%, and the compressive hardness of the aggregate is ⁇ 100 MPa.
  • the porosity of the aggregate is low, that is, its compactness is high, which helps to increase the energy density of the composite material on the one hand, and on the other hand, even if the surface layer of the high-density material is damaged, the electrolyte is not easy to penetrate into it.
  • the highly dense aggregate has a high compressive hardness, which can hedge The stress effect brought by the expansion improves the structural stability of the negative electrode material, which can effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • Porosity was measured by mercury intrusion porosimetry using a mercury porosimeter. The porosity is measured at least three times, and the arithmetic mean of the at least three times is used as the measurement result.
  • the compressive hardness is tested by a nano-indenter, using a load of 0.6N and an indentation depth of 0.5 ⁇ m.
  • the porosity of the aggregate is ⁇ 10%
  • the porosity of the aggregate may specifically be 10%, 9%, 9.5%, 8%, 8.5%, 7.5%, 7%, 6.5%, 6%, or 5% and so on, of course, can also be other values within the above range, which are not limited here.
  • the low porosity of the aggregates that is, their high density, is conducive to the formation of a stable solid electrolyte film and reduces the contact between the electrolyte and the active material.
  • the porosity of the aggregates is ⁇ 5%, more preferably, the porosity of the aggregates is ⁇ 3%.
  • the compressive hardness of the aggregate is ⁇ 100MPa; the compressive hardness of the aggregate can be 100MPa, 150MPa, 250MPa, 300MPa, 450MPa, 500MPa, 750MPa, 900MPa, 1150MPa, 1200MPa or 1250MPa, etc., of course, it can also be within the above range Other values are not limited here. Because of its strong rigidity and strong particle structure stability, it can resist a certain volume expansion stress, thereby reducing expansion and improving battery cycle stability.
  • the compressive hardness of the aggregate is ⁇ 200 MPa, more preferably, the compressive hardness of the aggregate is ⁇ 400 MPa.
  • the aggregate density satisfies the following relationship: the difference between the tested density of aggregates and the average density of aggregates is ⁇ 5%. The closer the density of the aggregate particles is to the average density, the smaller the difference, indicating that the pores inside the particles are less and denser, which is conducive to the formation of a stable solid electrolyte film and reduces the contact between the electrolyte and the active material.
  • the aggregate density is calculated as follows: ( ⁇ 1- ⁇ 2)/ ⁇ 2 ⁇ 5%, where ⁇ 1 is the test density of the aggregate, and ⁇ 2 is the average density of the aggregate;
  • ⁇ 2 is the sum of the value of the mass percentage content of each component in the aggregate * the theoretical density of each component in the aggregate.
  • ⁇ 2 mass percentage of active material in the aggregate*theoretical density of active material+mass percentage of carbon material in the aggregate*carbon material theory density.
  • the fluorine element is also distributed inside or on the surface of the metal oxide; when the F element is located inside the distributed metal oxide, part of the F element replaces the metal oxide in the crystal structure of the metal oxide. Atoms, and form valence bonds with neighboring atoms, part of the doping elements are distributed in lattice defects in the metal oxide crystal structure. Specifically, if the metal oxide is SnO 2 , it replaces Sn atoms in the crystal structure of SnO 2 and forms valence bonds with adjacent atoms, or it can be distributed in lattice defects of the crystal structure.
  • At least a portion of the metal oxide fills the pores between the carbon materials.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, Mg, Al, Ca and at least one of Zn; specifically, the metal oxide may be any one of GeO 2 , SnO 2 , ZnO, TiO 2 , Fe 3 O 4 , MgO, SiO 2 and CuO.
  • the mass ratio of the active material to the metal oxide is (30-100): (0.5-10). Specifically, it can be 30:0.5, 40:1, 50:2, 60:2, 70:3, 80:6, 90:7.5, 100:10 or 100:2, etc. Of course, it can also be other within the above range value, which is not limited here.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2. It should be noted that when the metal oxide is elongated, the aspect ratio specifically refers to the ratio of the length of the particle to the particle diameter of the particle, and the particle diameter here refers to the diameter perpendicular to the length direction of the elongated metal oxide. The maximum linear distance between two points on the periphery of the cross section; when the metal oxide is in the form of flakes, the aspect ratio specifically refers to the ratio of the length to the width of the flake metal oxide. Specifically, the aspect ratio of the metal oxide can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 12, 15, 17, 18, 22, etc. Of course, it can also be Other values within the above range are not limited here. According to many tests, it has been found that when the aspect ratio of the metal oxide is greater than 2, the physical binding force between the metal oxide and the active material can be improved, thereby buffering the volume expansion change of the active material and improving the cycle performance.
  • the shortest distance between metal oxides and metal oxides is > 100 nm.
  • the shortest distance control can make the metal oxides can be filled with active materials, and the metal oxides can be used as structural supports to enhance the stability of the material, thereby buffering the volume expansion change of the active materials and improving cycle performance. Specifically, it can be 100nm, 150nm, 200nm, 250nm, 300nm or 400nm, etc.
  • the shortest distance between metal oxides in this embodiment refers to the shortest linear distance between any two metal oxide particles.
  • the distance between the metal oxides is > 200 nm.
  • the distance test method is as follows: take any metal oxide to make a section sample, select the particles in it, test the shortest distance between any two metal oxides in the test particles, measure no less than 50 times, and take the average value.
  • the aggregate also includes a conductivity enhancer, which can provide more transport channels for carriers on the one hand, thereby enhancing the transport of carriers inside the material; on the other hand, it can also With excellent mechanical properties, it can be used as a structural support to enhance the stability of the material.
  • a conductivity enhancer which can provide more transport channels for carriers on the one hand, thereby enhancing the transport of carriers inside the material; on the other hand, it can also With excellent mechanical properties, it can be used as a structural support to enhance the stability of the material.
  • the fluorine element is also distributed inside or on the surface of the conductive enhancer material; when the F element is located inside the distributed conductive enhancer material, part of the F element replaces the crystal of the conductive enhancer material Atoms in the structure, and form valence bonds with adjacent atoms, and some doping elements are distributed in the lattice defects in the crystal structure of the conductivity enhancer material.
  • ⁇ 2 mass percentage of active material in aggregate%*active material theoretical density+mass percentage of conduction enhancer in aggregate*conduction enhancement
  • ⁇ 2 mass percentage of active materials in aggregates%*theoretical density of active materials+mass percentage of metal oxides in aggregates Content*theoretical density of metal oxide+mass percentage of conductive enhancer in aggregate*theoretical density of conductive enhancer+mass percentage of carbon material in aggregate*theoretical density of carbon material.
  • At least a portion of the conductivity enhancer is filled in the pores between the carbon materials.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon; wherein, the alloy material may include at least one of zinc alloy, aluminum alloy, copper alloy, silicon alloy, nickel alloy and titanium alloy,
  • the conductive carbon may include at least one of carbon nanotubes, carbon fibers, and graphite fibers.
  • the conductivity enhancer has a conductivity of 10 0 S/m ⁇ 10 8 S/m.
  • the conductivity of the conductivity enhancer may be 1 S/m, 10 S/m, 100 S/m, 10 3 S/m, 10 4 S/m, 10 5 S/m or 10 8 S/m, etc. Conductivity of the anode material using a powder resistivity tester.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the mass ratio of the conductivity enhancer to the active material is (0.01-15):(50-100). Specifically, it can be 0.01:50, 15:50, 0.05:55, 0.1:60, 1:50, 5:60, 7.5:75, 10:80 or 15:100, etc. Of course, it can also be other within the above range value, which is not limited here.
  • the aspect ratio of the conductivity enhancer is 2-5000. It should be noted that when the conductivity enhancer is strip-shaped, the aspect ratio specifically refers to the ratio of the length of the particle to the particle diameter of the particle, where the particle diameter refers to the length perpendicular to the length direction of the strip-shaped conductivity enhancer. The maximum linear distance between two points on the periphery of the section; when the conductivity enhancer is in the form of a sheet, the aspect ratio specifically refers to the ratio of the length to the width of the sheet-like conductivity enhancer.
  • the aspect ratio of the conductivity enhancer can be 2, 30, 46, 150, 360, 670, 800, 900, 1500, 2000, 3000, 4000, 5000, etc., of course, it can also be other values within the above range , is not limited here. According to many tests, it has been found that the conductivity enhancer with the aspect ratio within this range has excellent mechanical properties, and can be used as a structural support to enhance the stability of the material, thereby buffering the volume expansion change of the active material and improving cycle performance.
  • the negative electrode material further includes a carbon layer coating at least part of the surface of the aggregate.
  • the carbon layer is distributed over the surface of the aggregate. The carbon layer can reduce the contact between the active material and the electrolyte, reduce the formation of passivation film, and increase the reversible capacity of the battery.
  • the material of the carbon layer includes amorphous carbon.
  • the thickness of the carbon layer is 10nm-5000nm, specifically, the thickness of the carbon layer can be 10nm, 50nm, 100nm, 400nm, 500nm, 750nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, 4000nm, 5000nm, etc. etc.
  • the thickness of the carbon layer can be 10nm, 50nm, 100nm, 400nm, 500nm, 750nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, 4000nm, 5000nm, etc. etc.
  • other values within the above range can also be used, which are not limited here.
  • the carbon layer is too thick, it is not conducive to high-rate charge and discharge of the material, and reduces the overall performance of the negative electrode material; if the carbon layer is too thin, it is not conducive to increasing the conductivity of the negative electrode material and has weak inhibition on the volume expansion of the material, resulting in a price difference in long-cycle performance.
  • the median particle size of the negative electrode material is 0.5 ⁇ m to 30 ⁇ m, specifically 0.5 ⁇ m, 1.5 ⁇ m, 3 ⁇ m, 10 ⁇ m, 16 ⁇ m, 26 ⁇ m, etc., of course, it can also be other values within the above range. This is not limited. It can be understood that controlling the median particle size of the negative electrode material within the above range is beneficial to the improvement of the cycle performance of the negative electrode material. Preferably, the median particle size of the negative electrode material is 1.5 ⁇ m ⁇ 15 ⁇ m.
  • the specific surface area of the negative electrode material is ⁇ 10m 2 /g, specifically 10m 2 /g, 7m 2 /g, 6m 2 /g, 4m 2 /g, 2m 2 /g, 1m 2 /g etc.
  • other values within the above range may also be used, which are not limited here. It can be understood that controlling the specific surface area of the negative electrode material within the above range is beneficial to suppress volume expansion and improve the cycle performance of the negative electrode material.
  • the specific surface area of the negative electrode material is ⁇ 5m 2 /g. The specific surface area of the anode material was tested using a McRae surface area analyzer.
  • the mass ratio of the aggregate to the carbon layer is (90-10):(10-90), specifically 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, etc., there is no specific limit.
  • the negative electrode material further includes an oxide layer formed on at least part of the surface of the active material; when the active material is silicon particles, the oxide layer is silicon oxide.
  • the thickness of the oxide layer is 1nm to 100nm, and the thickness of the oxide layer can be 1nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc. Of course, it can also be the above Other values within the range are not limited here.
  • the oxide layer has pores, thereby providing space for the active material to expand, reducing the volume expansion effect of the active material.
  • the negative electrode materials in the above embodiments can be combined arbitrarily if there is no conflict with each other, for example, the compressive hardness, porosity and density of the aggregates are limited in combination.
  • the preparation method of the negative electrode material of another embodiment comprises the following steps:
  • Step S100 preparing a precursor after mixing the active material, dopant, first carbon source and solvent;
  • Step S200 performing a heat treatment on the precursor at 800°C to 980°C to obtain aggregates
  • step S300 the aggregate is subjected to carbon coating treatment to obtain the negative electrode material.
  • the negative electrode material prepared by the preparation method of this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include active materials, carbon materials and doping elements.
  • the Raman diagram obtained by Mann spectroscopy shows that the G band is observed at 1530 cm -1 to 1630 cm -1 and the D band is observed at 1280 cm -1 to 1380 cm -1 , and the peak intensity ID of the D band is the same as that of the G band
  • the ratio I D /I G between the peak intensities I G is 1 to 2.5.
  • the addition of the dopant can promote the combination of the carbon material and the active material, and in addition, it can increase the degree of graphitization of the carbon material, thereby improving the electrical conductivity.
  • Doping elements induce active sites with high activity and selectivity in carbon materials. On the one hand, these active sites are easier to combine with the surface of the active material to form a more stable connection; on the other hand, due to the increased activity, the energy The barrier is reduced, the rearrangement resistance of carbon atoms is reduced, and it is easier to form an ordered arrangement during the high-temperature heat treatment process, which is manifested by an increase in the local short-range order and a partial increase in the degree of graphitization.
  • the addition of dopants is beneficial to improve the stability of the interface of the active material, thereby improving the cycle stability of the material; the initial efficiency, expansion rate, and cycle life of the negative electrode material are all improved.
  • Step S100 preparing a precursor after mixing the active material, the dopant, the first carbon source and the solvent.
  • the median diameter of the active material is 1 nm to 300 nm. Specifically, it can be 1nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 120nm, 150nm, 200nm, 250nm, 300nm, etc. Of course, it can also be other values within the above range, which will not be done here limited.
  • the median particle size of the active material is controlled within the above range, which is beneficial to the improvement of the cycle performance of the negative electrode material.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, SiOx (0 ⁇ x ⁇ 2), Fe, Mg, Ti, Zn, Al, P or Cu;
  • the active material may be a simple metal.
  • the active material can specifically be Si particles, Sn particles, Ge particles, and Al particles.
  • the active material can also be silicon-lithium alloys, silicon-magnesium alloys, etc. Of course, it needs to be explained Yes, in some cases, active materials include elemental particles and alloys.
  • the addition of fluoride can effectively promote the disproportionation of SiO x to form Si and SiO 2 , thereby forming A more uniform SiO 2 coating is conducive to the stability and improvement of the silicon interface and improves the cycle stability of the material; and the fluoride will etch the oxide layer on the silicon surface to obtain pores, thus providing space for silicon expansion , reducing the volume expansion effect of silicon.
  • the dopant includes at least one of a fluorine source, a phosphorus source, and a nitrogen source.
  • a fluorine source a phosphorus source
  • a nitrogen source a nitrogen source.
  • the electronegativity difference between doped atoms and carbon atoms is very large, and the introduction of doped atoms makes the charge distribution of carbon atoms uneven, resulting in Lewis acid sites.
  • these active sites are more It is easy to combine with the surface of the active material to form a more stable connection; on the other hand, due to the increase in activity, the energy barrier is reduced, and the rearrangement resistance of carbon atoms is reduced. The order degree increases, and the degree of graphitization is partially improved.
  • the addition of doping elements is beneficial to improve the stability of the interface of the active material, thereby improving the cycle stability of the material; the initial efficiency, expansion rate, and cycle life of the negative electrode material are all improved.
  • the fluorine source includes fluoride, including hydrogen fluoride, lithium fluoride, ammonium fluoride, potassium fluoride, aluminum fluoride, magnesium fluoride, sodium fluoride, calcium fluoride, tetrabutyl fluoride, At least one of ammonium, triethylmethoxymethylammonium fluoride, ammonium fluoroborate and tetrabutylammonium fluoroborate.
  • the phosphorus source includes triphenylphosphine, tetraphenylphosphorus bromide, 1-butyl-3-methylimidazolium sodium hexafluorophosphate, phosphine, sodium phosphate, sodium phosphite, elemental phosphorus, At least one of sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium hydrogen phosphite and phosphoric acid.
  • the nitrogen source includes at least one of ammonia gas, ammonium chloride, ammonium carbonate, ammonium bicarbonate, urea, thiourea, lithium nitride, melamine, and hydrazine hydrate.
  • the first carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, polyethylene At least one of vinylidene fluoride, polyacrylonitrile, polyvinyl chloride and asphalt.
  • the mass ratio of the active material, the dopant and the first carbon source is (30-120):(0.9-20):(10-50).
  • the mass ratio of active material, dopant and first carbon source can be 30:0.9:10, 40:5:15, 70:10:20, 60:12:30, 80:20:50, 100 : 10: 10, 110: 5: 20, 120: 3: 15, etc.
  • it can also be other values within the above range, which are not limited here.
  • the solvent includes an organic solvent.
  • the organic solvent includes at least one of methanol, ethanol, ethylene glycol, propanol, isopropanol, glycerol, n-butanol, isobutanol and pentanol. Adding each component into an organic solvent for wet ball milling can improve the mixing uniformity of the components and facilitate rapid drying.
  • the step of mixing the active material, the dopant, the first carbon source, and the solvent specifically includes: dispersing the active material in an organic solvent, and then adding the dopant and the first carbon source.
  • the step of preparing the precursor further includes at least one of dispersion treatment and drying treatment after mixing the active material, dopant, first carbon source and solvent.
  • the active material, the dopant, the first carbon source and the solvent are mixed, followed by dispersion treatment and drying treatment in sequence.
  • the dispersion treatment includes at least one of mechanical stirring, ultrasonic dispersion, and grinding dispersion; particle agglomeration can be avoided, and the active substance can be dispersed into smaller nanoparticles.
  • the temperature of the drying treatment is 30°C to 400°C
  • the time of the drying treatment is 1h to 15h; specifically, it can be 30°C, 40°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 250°C, 280°C, 300°C or 400°C, etc.
  • the drying time is 1h to 15h, specifically 1h, 3h, 5h, 7h, 9h, 10h, 12h or 15h, etc.
  • the drying treatment method can be, for example, furnace drying, freeze drying, stirring and evaporation to dryness, spray drying, etc.
  • the drying treatment in this embodiment can remove the solvent in the precursor solution as much as possible.
  • additives are added during the step of mixing the active material, the dopant, the first carbon source and the solvent.
  • the additive in this embodiment can effectively enhance the connection stability of the active material and the carbon material, thereby forming a firm system.
  • the additive includes at least one of a surfactant and a coupling agent. It has been found through experiments that the use of this type of additive can effectively enhance the connection stability between the active material and the carbon material to form a firm system and reduce the porosity; thereby reducing the expansion rate of the negative electrode material and increasing the cycle stability.
  • surfactants include, but are not limited to, octadecanoic acid, lauric acid, polyacrylic acid (PAA), sodium dodecylbenzenesulfonate (SDBS), n-eicosic acid, palmitic acid, myristic acid, At least one of monoalkanoic acid, cetyltrimethylammonium bromide and polyvinylpyrrolidone (PVP).
  • PAA polyacrylic acid
  • SDBS sodium dodecylbenzenesulfonate
  • PVP polyvinylpyrrolidone
  • Coupling agents include silane coupling agents, specifically, silane coupling agents include but are not limited to ⁇ -aminopropyltriethoxysilane, ⁇ -glycidyl etheroxypropyl trimethoxysilane and ⁇ -methacryloyl At least one of oxypropyltrimethoxysilane.
  • the mass ratio of the active substance to the additive is (50-100): (0.01-5).
  • At least one of a metal oxide and a conductivity enhancer is added in the step of mixing the active material, the dopant, the first carbon source and the solvent.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, Mg, Al, Ca and at least one of Zn.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2.
  • the mass ratio of the conductivity enhancer to the active material is (0.01-15):(50-100).
  • the conductivity enhancer has a conductivity of 10 0 S/m ⁇ 10 8 S/m.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the aspect ratio of the conductivity enhancer is 2-5000.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • the precursor before the precursor is subjected to a heat treatment, it also includes densifying the precursor, so that the porosity of the aggregate is ⁇ 10% and the compressive hardness is ⁇ 100MPa;
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment, and impregnation treatment;
  • the fusion treatment is mechanical fusion; the fusion treatment of the precursor is used to improve the compressive hardness of the negative electrode material, and then a heat treatment is performed to enhance the stability of the particle structure, and at the same time, the active material and the first carbon source can be strengthened. The stability of the connection between them reduces the porosity.
  • other methods can also be used for densification treatment, such as molding, isostatic pressing, impregnation and other processes, as long as the porosity of the aggregate is ⁇ 10% and the compressive hardness is ⁇ 100MPa.
  • the rotation speed of the fusion machine used for mechanical fusion is 500r/min-3000r/min;
  • the fusion machine tool gap width used for mechanical fusion is 0.01cm-0.5cm;
  • the mechanofusion time is at least 0.5 h.
  • step S200 the precursor is subjected to a heat treatment at 800° C. to 980° C. to obtain aggregates.
  • the primary heat treatment may be, for example, vacuum sintering, hot pressing sintering or normal pressure sintering.
  • the temperature of the primary heat treatment is 800°C to 980°C, specifically 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920° C., 930° C., 940° C., 950° C., 960° C., 970° C., 980° C., etc., of course, may also be other values within the above range, which are not limited here.
  • one treatment time is 1 h to 5 h, specifically 1 h, 2 h, 3 h, 4 h, 5 h, etc., of course, it can also be other values within the above range, which is not limited here.
  • the primary heat treatment is performed in the first protective atmosphere; specifically, the gas in the first protective atmosphere includes at least one of nitrogen, helium, neon, argon, and krypton.
  • a pulverization operation is performed, and the pulverization method is any one of a mechanical pulverizer, a jet pulverizer, and a low-temperature pulverizer.
  • step S300 the aggregate is subjected to carbon coating treatment to obtain the negative electrode material.
  • step S300 may be omitted.
  • the specific steps of the carbon coating treatment may include: mixing the aggregates with a second carbon source, and performing secondary heat treatment.
  • the second carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, polyethylene glycol, At least one of vinylidene fluoride, polyacrylonitrile, polyvinyl chloride and asphalt.
  • the mass ratio of aggregates to the second carbon source is (20-100): (10-80).
  • the mass ratio of the aggregate to the second carbon source can be 20:10, 30:15, 50:60, 80:30, 90:20, 100:10, etc., of course, it can also be other values within the above range. This is not limited.
  • the way of the secondary heat treatment may be, for example, vacuum sintering, hot pressing sintering or normal pressure sintering.
  • the temperature of the secondary heat treatment is 800°C to 900°C. Specifically, it can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, etc. Of course, it can also be other values within the above range. This is not limited.
  • the time for the secondary heat treatment is 1 h to 5 h; specifically, it can be 1 h, 2 h, 3 h, 4 h, 5 h, etc., of course, it can also be other values within the above range, which is not limited here.
  • the secondary heat treatment is performed in a second protective atmosphere; the gas in the second protective atmosphere includes at least one of nitrogen, helium, neon, argon, and krypton.
  • At least one of crushing, sieving and demagnetization is further performed; preferably, after the secondary heat treatment, crushing, sieving and demagnetization are also performed sequentially.
  • the pulverization method is any one of a mechanical pulverizer, a jet pulverizer, and a low-temperature pulverizer.
  • the screening method is any one of a fixed screen, a drum screen, a resonance screen, a roller screen, a vibrating screen, and a chain screen, and the screening mesh is ⁇ 500 mesh.
  • the screening mesh The mesh number can be 500 mesh, 600 mesh, 700 mesh, 800 mesh, etc., and the particle size of the negative electrode material is controlled within the above range, which is conducive to the improvement of the cycle performance of the negative electrode material.
  • the demagnetization equipment is any one of permanent magnetic drum magnetic separator, electromagnetic iron remover, and pulsating high-gradient magnetic separator.
  • the purpose of demagnetization is to finally control the magnetic content of the negative electrode material and avoid The discharge effect of substances on lithium-ion batteries and the safety of batteries during use.
  • the present application also provides a lithium-ion battery, which comprises the above-mentioned negative electrode material, or the negative-electrode material prepared by the above-mentioned preparation method.
  • the median particle size mentioned in the present disclosure refers to the average particle size, and its physical meaning is the particle size corresponding to when the cumulative particle size distribution percentage of the particles reaches 50%, which is tested by a Malvern particle size analyzer.
  • the Malvern Particle Size Analyzer uses the light scattering phenomenon of particles to comprehensively convert the particle size distribution of the measured particles according to the distribution of scattered light energy.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 600ppm; Shown, the G band observed at 1530 cm -1 to 1630 cm -1 and the D band observed at 1280 cm -1 to 1380 cm -1 , and the peak intensity ID of the D band and the peak intensity I G of the G band The ratio I D /I G was 2.01.
  • the aggregate particles were tested by mercury porosimetry, and the porosity of the aggregates was 10.6%.
  • the aggregate particles were tested by a nano-indenter, and the average compressive hardness of the aggregates was 45MPa.
  • the difference between the tested density of the aggregate and the average density of silicon powder and carbon material is 2.1%.
  • the aggregates and phenolic resin are mixed according to the mass ratio of 30:40, stirred and dispersed evenly, and then dried, and then the dried materials are added to a high-temperature box furnace, and nitrogen gas is introduced , heat-treated at 890° C. for 3 h, crushed, and sieved through a 500-mesh sieve to obtain the negative electrode material.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 12.1 ⁇ m, the specific surface area is 3.2m 2 /g, the average thickness of the carbon layer is 739nm, and the fluorine element content of the aggregate is 920ppm; the Raman diagram of the carbon material obtained by Raman spectroscopy using a measuring light source with a wavelength of 532nm Shown in , the G band observed at 1530 cm -1 to 1630 cm -1 and the D band observed at 1280 cm -1 to 1380 cm -1 , and the peak intensity ID of the D band and the peak intensity I G of the G band are between The ratio I D /I G is 1.99.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 12.1 ⁇ m, the specific surface area is 5.2m 2 /g, the average thickness of the carbon layer is 5.7nm, and the fluorine element content of the aggregate is 1030ppm.
  • the figure shows that the G band observed at 1530 cm -1 to 1630 cm -1 and the D band observed at 1280 cm -1 to 1380 cm -1 , and the peak intensity ID of the D band and the peak intensity I G of the G band The ratio I D /I G between them is 1.94.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 9.1 ⁇ m, the specific surface area is 4.2m 2 /g, the average thickness of the carbon layer is 5.7nm, and the fluorine element content of the aggregate is 590ppm.
  • the figure shows that the G band observed at 1530 cm -1 to 1630 cm -1 and the D band observed at 1280 cm -1 to 1380 cm -1 , and the peak intensity ID of the D band and the peak intensity I G of the G band The ratio I D /I G between them is 2.05.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 15.1 ⁇ m, the specific surface area is 2.2m 2 /g, the average thickness of the carbon layer is 667nm; the fluorine element content of the aggregate is 15060ppm.
  • the carbon material is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm -1 to 1630 cm -1 and a D band observed at 1280 cm -1 to 1380 cm -1 band, and the ratio I D /I G between the peak intensity I G of the D band and the peak intensity ID of the G band is 1.85.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 10.1 ⁇ m, the specific surface area is 2.0m 2 /g, the average thickness of the carbon layer is 967nm; the fluorine element content of the aggregate is 9620ppm.
  • the carbon material is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm -1 to 1630 cm -1 and a D band observed at 1280 cm -1 to 1380 cm -1 band, and the ratio ID/I G between the peak intensity ID of the D band and the peak intensity I G of the G band is 1.9.
  • the speed of the fusion machine is 500r/min
  • the width of the tool gap of the fusion machine used for mechanical fusion is 0.05cm
  • the mechanical fusion time is 0.5h
  • the fused material is placed in a heat treatment furnace, Then pass argon gas under the condition of 900 ° C, conduct a heat treatment, keep the temperature for 3 hours, and obtain aggregates;
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 13 ⁇ m, the specific surface area is 6.2m 2 /g, the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 600ppm.
  • the carbon material is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm - 1 to 1630 cm -1 and a D band observed at 1280 cm -1 to 1380 cm -1 band, and the ratio ID/I G between the peak intensity ID of the D band and the peak intensity I G of the G band is 2.49.
  • the aggregate particles were tested by mercury porosimetry, and the porosity of the aggregates was 4.4%.
  • the aggregate particles were tested by a nano-indentation instrument, and the average compressive hardness of the aggregates was 223MPa. The difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 2.1%.
  • the fused material is placed in a heat treatment furnace, and then Introduce nitrogen gas at 900°C, conduct heat treatment once, keep warm for 3 hours, and obtain aggregates;
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 12 ⁇ m, the specific surface area is 5.9m 2 /g, and the average thickness of the carbon layer is 102nm; the fluorine element content of the aggregate is 8040ppm; the aggregate particles are tested by mercury porosimetry, and the porosity of the aggregate is 4.3%.
  • the aggregate particles were tested by a nano indenter, and the average compressive hardness of the aggregate was 198MPa.
  • the measured density of the aggregates was 1.8% different from the average density of the silicon powder and carbon material.
  • step 1) is different, and step 1) adds additives.
  • the specific step 1) is to disperse silicon particles with a median particle size of 50nm in an ethanol solution (volume percentage concentration 40%), and then add triethylmethoxymethylammonium fluoride, phenolic resin, and lauric acid to mix evenly, Among them, the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, and lauric acid is 50:4.3:24.5:3.3; and then dry at 150°C for 5 hours to obtain the precursor body;
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 602ppm; the aggregate particles are tested by mercury porosimetry, and the porosity of the aggregate is 11.5%.
  • the aggregate particles were tested by a nanoindenter, and the average compressive hardness of the aggregate was 69MPa. The difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 2.6%.
  • step 1) is different, and step 1) adds additives.
  • the specific step 1) is to disperse silicon particles with a median particle size of 50nm in an ethanol solution (volume percentage concentration 40%), and then add triethylmethoxymethyl ammonium fluoride, phenolic resin, ⁇ -aminopropyl Triethoxysilane is mixed evenly, wherein the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, and ⁇ -aminopropyltriethoxysilane is 50:4.3:24.5:3.3; then Perform drying treatment at a drying temperature of 150° C. for 5 hours to obtain a precursor.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, carbon materials, and fluorine doped in carbon materials and silicon powders.
  • the median particle size of the negative electrode materials is The diameter is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 605ppm; the aggregate particles are tested by mercury porosimetry, and the porosity of the aggregate is 3.6%.
  • the aggregate particles were tested by a nano-indentation instrument, and the average compressive hardness of the aggregate was 365MPa.
  • the measured density of the aggregates was 2.2% different from the average density of the silicon powder and carbon material.
  • step 1) is different, and step 1) adds metal oxide.
  • Concrete step 1) is to disperse silicon particles that the median particle diameter is 50nm in ethanol solution (volume percentage concentration 40%), then add triethylmethoxymethylammonium fluoride, phenolic resin, aspect ratio is 12
  • the GeO 2 particles are mixed evenly, wherein the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, and GeO 2 particles is 50:4.3:24.5:1.9; then dry treatment, the drying temperature is 150 °C for 5 hours to obtain the precursor.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, GeO2 particles and carbon materials and fluorine doped in carbon materials, GeO2 particles and silicon powder element, the median particle size of the negative electrode material is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 601ppm; The porosity of the aggregate is 10.2%.
  • the aggregate particle is tested by a nano-indenter, and the average compressive hardness of the aggregate is 78MPa. The difference between the tested density of aggregates and the average density of silicon powder and carbon material is 2.3%, and the minimum value of the spacing between metal oxides is 26 nm.
  • step 1) is different, and step 1) adds a metal oxide.
  • Step 1) is specifically 1) dispersing silicon particles with a median diameter of 50nm in an ethanol solution (40% concentration by volume), then adding triethylmethoxymethylammonium fluoride, phenolic resin, and an aspect ratio of 8 ZnO particles are mixed evenly, and the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, and ZnO particles is 50:4.3:24.5:3.6; then drying treatment is carried out at a drying temperature of 150°C , the time is 5h, and the precursor is obtained.
  • the negative electrode material prepared in this embodiment includes an aggregate and a carbon layer coated on the surface of the aggregate.
  • the aggregate includes silicon powder, carbon material, ZnO particles and fluorine element doped in the carbon material, silicon powder and ZnO particles.
  • the median particle size of the negative electrode material is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine content of the aggregate is 608ppm; the aggregate particles are tested by mercury porosimetry, and the pores of the aggregate The ratio is 5.0%; the aggregate particles are tested by a nano indenter, and the average compressive hardness of the aggregate is 284MPa.
  • the difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 1.9%.
  • the minimum pitch of the metal oxide is 106 nm.
  • step 1) is different, and step 1) adds a conductivity enhancer.
  • Concrete step 1) is to disperse the silicon particle that median particle diameter is 50nm in ethanol solution (volume percent concentration 40%), then add triethylmethoxymethyl ammonium fluoride, phenolic resin, diameter 20nm, major diameter Carbon nanotubes (CNTs) with a ratio of 500 are mixed evenly, wherein the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, and CNTs is 50:4.3:24.5:0.5; then dry, The drying temperature is 150° C. and the drying time is 5 hours to obtain the precursor.
  • CNTs Carbon nanotubes
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, CNT, carbon materials, and fluorine doped in carbon materials, CNTs, and silicon powders.
  • the negative electrode material The median particle size is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 600ppm; the aggregate particles are tested by mercury porosimetry, and the porosity of the aggregate is 10.7%; the aggregate particle is tested by a nano-indenter, and the average compressive hardness of the aggregate is 62MPa.
  • the difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 3.6%.
  • step 1) is different, and step 1) adds a conductivity enhancer.
  • Step 1) is specifically 1) dispersing silicon particles with a median particle size of 50nm in an ethanol solution (40% concentration by volume), and then adding triethylmethoxymethylammonium fluoride, phenolic resin, and an aspect ratio of 18
  • the FeSi 2 is mixed evenly, wherein the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, and FeSi 2 is 50:4.3:24.5:2.1; then dry treatment, the drying temperature is 150 ° C, The time is 5h, and the precursor is obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, FeSi 2 , carbon materials and fluorine elements doped in carbon materials, FeSi 2 and silicon powders,
  • the median particle size of the negative electrode material is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine content of the aggregate is 610ppm; the aggregate particles are tested by mercury porosimetry, and the pores of the aggregate The ratio is 4.5%; the aggregate particles are tested with a nano-indentation instrument, and the average compressive hardness of the aggregate is 205 MPa.
  • the difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 1.2%.
  • step 1) is different, and step 1) adds a conductivity enhancer and a metal oxide.
  • Concrete step 1) is to disperse the silicon particle that median particle diameter is 50nm in ethanol solution (volume percent concentration 40%), then add triethylmethoxymethyl ammonium fluoride, phenolic resin, aspect ratio is 22 SiO particles with a diameter of 20nm are mixed evenly, wherein the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, SiO particles, and CNTs is 50:4.3:24.5:2.9:0.3; and then Drying treatment, the drying temperature is 150° C., and the drying time is 5 hours to obtain the precursor.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder, SiO particles, CNT, and carbon materials and are doped in carbon materials, SiO particles, CNT, and silicon powder.
  • fluorine element the median particle size of the negative electrode material is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 590ppm; the aggregate particles are tested by mercury porosimetry, The porosity of the aggregate is 12.9%.
  • the aggregate particles are tested by a nano-indenter, and the average compressive hardness of the aggregate is 99MPa.
  • the difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 2.1%.
  • step 1) is different, and step 1) adds metal oxide and conductivity enhancer.
  • Step 1) is specifically 1) dispersing silicon particles with a median diameter of 50nm in an ethanol solution (40% concentration by volume), then adding triethylmethoxymethylammonium fluoride, phenolic resin, and an aspect ratio of 17 TiO 2 particles, the nickel-silicon alloy with an aspect ratio of 50 are uniformly mixed, wherein the mass ratio of silicon particles, triethylmethoxymethylammonium fluoride, phenolic resin, TiO 2 particles to the nickel-silicon alloy is 50: 4.3: 24.5: 3.9: 1.1; then perform drying treatment at a temperature of 150° C. for 5 hours to obtain a precursor.
  • the negative electrode material prepared in this embodiment includes aggregates and carbon layers coated on the surface of the aggregates.
  • the aggregates include silicon powder, TiO2 particles, nickel-silicon alloys, carbon materials and doped carbon materials, TiO2 particles, nickel
  • the fluorine element in silicon alloy and silicon powder the median particle size of the negative electrode material is 13 ⁇ m, the specific surface area is 6.2m 2 /g, and the average thickness of the carbon layer is 559nm; the fluorine element content of the aggregate is 598ppm;
  • the aggregate particle was tested, and the porosity of the aggregate was 10.9%.
  • the aggregate particle was tested by a nano indenter, and the average compressive hardness of the aggregate was 229MPa. The difference between the measured density of the aggregate and the average density of silicon powder and carbon material is 1.9%.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include Al powder, carbon material and fluorine element doped in carbon material, Al powder and silicon powder.
  • the negative electrode material The median particle size is 11 ⁇ m, the specific surface area is 3.9m 2 /g, the average thickness of the carbon layer is 98nm; the fluorine content of the aggregate is 2190ppm.
  • the negative electrode material prepared in this embodiment includes aggregates, the aggregates include silicon powder, carbon material and fluorine element doped in carbon material and silicon powder, the median particle size of the negative electrode material is 13 ⁇ m, and the specific surface area is 26.2 m 2 /g; the fluorine element content of the aggregate is 890ppm.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 5, except that the fluorine content in the aggregate was 20,000 ppm, and the heat treatment temperature in step 2) was 980°C.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1 The D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 1.5.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 5, except that the fluorine content in the aggregate was 21890 ppm, followed by heat treatment.
  • the negative electrode material prepared in this example includes an aggregate and a carbon layer coated on the surface of the aggregate.
  • the aggregate includes silicon powder, carbon material and fluorine element.
  • the mass ratio of silicon powder and carbon material is 63.0:37.0.
  • the median particle size is 13.8 ⁇ m, the specific surface area is 6.6m 2 /g, the average thickness of the carbon layer is 565nm; the fluorine content of the aggregate is 21890ppm.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1
  • the D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 1.8.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 5, except that the fluorine content in the aggregate was 50 ppm, and the heat treatment temperature in step 2) was 980°C.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1 The D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 2.1.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 5, except that the fluorine content in the aggregate was 39 ppm, followed by heat treatment.
  • the negative electrode material prepared in this example includes an aggregate and a carbon layer coated on the surface of the aggregate.
  • the aggregate includes silicon powder, carbon material and fluorine element.
  • the mass ratio of silicon powder and carbon material is 62.5:37.5.
  • the median particle size is 12.8 ⁇ m, the specific surface area is 5.9m 2 /g, the average thickness of the carbon layer is 549nm; the fluorine content of the aggregate is 39ppm.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1
  • the D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 2.31.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 1, except that the dopant used was triphenylphosphine, and the content of doping elements was the same as in Example 1.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1 The D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 2.1.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 1, except that the dopant used was tetraphenylphosphine bromide, and the content of doping elements was the same as in Example 1.
  • the I D / IG of this example was 2.05.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 1, except that the dopant used was lithium nitride, and the content of doping elements was the same as in Example 1.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1 The D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 1.9.
  • the nano-silicon-based composite negative electrode material was prepared in the same manner as in Example 1, except that the dopant used was thiourea, and the content of the doping elements was the same as in Example 1.
  • the carbon material in this example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1 The D band was observed, and the ratio ID / I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 1.85.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include silicon powder and carbon material.
  • the mass ratio of silicon powder and carbon material is 63.3:36.7.
  • the median particle size of the negative electrode material is The diameter is 13.5 ⁇ m, the specific surface area is 6.3m 2 /g, the average thickness of the carbon layer is 561nm; the fluorine element content of the aggregate is 0ppm.
  • the carbon material in this comparative example is shown in a Raman map obtained by Raman spectroscopy using a measuring light source with a wavelength of 532 nm, a G band observed at 1530 cm ⁇ 1 to 1630 cm ⁇ 1 and a G band observed at 1280 cm ⁇ 1 to 1380 cm ⁇ 1
  • the D band was observed, and the ratio ID/I G between the peak intensity ID of the D band and the peak intensity I G of the G band was 2.5.
  • the charge and discharge test of the cylindrical battery is performed on the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd., under normal temperature conditions, 0.2C constant current charge and discharge, and the charge and discharge voltage is limited to 2.75 ⁇ 4.2V.
  • the first coulombic efficiency the discharge capacity of the first cycle / the charge capacity of the first cycle.
  • the negative electrode materials prepared in Examples 1-26 can obtain carbon materials with higher degree of graphitization by adding doping elements in the aggregates, thereby improving the conductivity of the negative electrode materials and providing silicon expansion. The space is reduced, and the volume expansion effect of silicon is reduced.
  • Example 19 the addition of fluorine-containing components higher than 20,000 ppm, the first-time efficiency, expansion rate, and cycle life are not as good as the examples of the present application, and the performance is deteriorated.
  • Example 22 the fluorine-containing component was added below 50 ppm, and the graphitization effect of the carbon material was not good, so that the first-time efficiency, expansion rate, and cycle life of the electrode plate made of the prepared negative active material were not as good as the examples of the present application, and the performance deteriorated.
  • the application illustrates the detailed process equipment and process flow of the application through the above-mentioned examples, but the application is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the application must rely on the above-mentioned detailed process equipment and process flow. process can be implemented.
  • Those skilled in the art should understand that any improvement to the present application, the equivalent replacement of each raw material of the product of the present application, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present application.

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Abstract

一种负极材料及其制备方法、锂离子电池，负极材料包括聚集体，聚集体包括活性物质、碳材料及掺杂元素，碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到G带和在1280cm -1至1380cm -1观察到D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1～2.5。负极材料的首次效率得到显著提升，循环性能稳定性有较大提升。

Description

负极材料及其制备方法、锂离子电池
本申请要求于2021年08月12日提交中国专利局，申请号为2021109242947，申请名称为“负极材料及其制备方法、锂离子电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及负极材料技术领域，具体地讲，尤其涉及负极材料及其制备方法、锂离子电池。
背景技术
近年来，锂离子电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而被广泛应用于电动汽车以及消费类电子产品中。如硅碳负极材料已经部分应用于动力类等领域，但是，全电池应用中对负极首次效率要求比较高。当前石墨负极首次效率普遍在93％以上，硅负极材料首次效率通常在80％～85％左右，在成品电池设计的时候导致负极克容量发挥差。需要通过一些手段来提高首次效率，比如负极预锂等技术，但是现有补锂手段工艺复杂、危险性大以及对设备要求高，需要通过其他的方法提高硅基材料的首次效率，因此限制了硅负极的进一步应用。
因此，如何提高首次效率的同时简化工艺、降低成本是目前急需解决的问题。
申请内容
本申请为了克服上述缺陷，提供负极材料及其制备方法、锂离子电池，有利于提高负极材料的首次效率，该制备方法可简化工艺、降低制作成本。
第一方面，本申请实施例提供一种负极材料，包括聚集体，所述聚集体包括活性物质、碳材料及掺杂元素；所述碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到G带和在1280cm -1至1380cm -1观察到D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1～2.5。
第二方面，本申请实施例提供一种负极材料，包括聚集体，所述聚集体包括活性物质、碳材料及掺杂元素，所述掺杂元素能够诱导所述碳材料产生路易斯酸活性位点，至少部分所述活性物质通过所述路易斯酸活性位点与所述碳材料结合。
在一种可行的实施方式中，所述掺杂元素包括氟、氮及磷中的至少一种。
在一种可行的实施方式中，所述活性物质及碳材料中的至少一种含有所述掺杂元素。
在一种可行的实施方式中，所述掺杂元素分布于所述活性物质的表面和/或内部。
在一种可行的实施方式中，所述掺杂元素分布于所述碳材料的表面和/或内部。
在一种可行的实施方式中，所述掺杂元素在所述聚集体中的含量为50ppm～20000ppm。
在一种可行的实施方式中，所述碳材料之间形成有孔隙，至少部分所述活性物质填充于所述孔隙。
在一种可行的实施方式中，所述碳材料的孔容≥0.35cm 3/g。
在一种可行的实施方式中，所述活性物质分布于碳材料之间或表面。
在一种可行的实施方式中，所述活性物质包括活性粒子。
在一种可行的实施方式中，所述活性物质包括Li、Na、K、Sn、Ge、Si、Fe、Mg、Ti、Zn、Al、P、Cu及SiO x中的至少一种，其中，0＜x≤2。
在一种可行的实施方式中，所述活性物质的中值粒径为1nm～300nm。
在一种可行的实施方式中，所述碳材料包括结晶碳、非晶碳、人造石墨、天然石墨、软碳、硬碳、无定形碳、碳纳米管、碳纤维及石墨烯中至少一种。
在一种可行的实施方式中，所述活性物质与所述碳材料的质量比为(90～10)：(10～90)。
在一种可行的实施方式中，所述聚集体还包括金属氧化物。
在一种可行的实施方式中，至少部分所述金属氧化物填充于所述碳材料之间的孔隙中。
在一种可行的实施方式中，所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种。
在一种可行的实施方式中，所述金属氧化物包括GeO 2、SnO 2、ZnO、TiO 2、Fe 3O 4、 MgO、SiO 2和CuO中的任意一种。
在一种可行的实施方式中，所述活性物质与所述金属氧化物的质量比为(30～100)：(0.5～10)。
在一种可行的实施方式中，所述金属氧化物呈片状和/或长条状。
在一种可行的实施方式中，所述金属氧化物的长径比值大于2。
在一种可行的实施方式中，所述金属氧化物与金属氧化物之间的最短距离≥100nm。
在一种可行的实施方式中，所述聚集体还包括导电增强剂。
在一种可行的实施方式中，至少部分所述导电增强剂填充于所述碳材料之间的孔隙中。
在一种可行的实施方式中，所述导电增强剂包括合金材料及导电碳中的至少一种。
在一种可行的实施方式中，所述导电增强剂包括合金材料及导电碳中的至少一种，所述导电碳包括碳纳米管、碳纤维和石墨纤维中的至少一种。
在一种可行的实施方式中，所述导电增强剂的电导率为10 0S/m～10 8S/m。
在一种可行的实施方式中，所述导电增强剂呈片状和/或长条状。
在一种可行的实施方式中，所述导电增强剂与所述活性物质的质量比为(0.01～15):(50～100)。
在一种可行的实施方式中，所述导电增强剂的长径比为2～5000。
在一种可行的实施方式中，所述负极材料还包括包覆所述聚集体的至少部分表面的碳层。
在一种可行的实施方式中，所述碳层的材料包括无定形碳。
在一种可行的实施方式中，所述碳层的厚度为10nm～5000nm。
在一种可行的实施方式中，所述聚集体与所述碳层的质量比为(90～10)：(10～90)。
在一种可行的实施方式中，所述负极材料还包括形成于所述活性物质至少部分表面的氧化层。
在一种可行的实施方式中，所述氧化层的厚度为1nm～100nm。
在一种可行的实施方式中，所述氧化层具有孔隙。
在一种可行的实施方式中，所述负极材料的中值粒径为0.5μm～30μm。
在一种可行的实施方式中，所述负极材料的比表面积为≤10m 2/g。
在一种可行的实施方式中，所述聚集体的孔隙率≤10％。
在一种可行的实施方式中，所述聚集体的耐压硬度≥100MPa。
在一种可行的实施方式中，所述聚集体密度满足以下关系：(ρ1-ρ2)/ρ2≤5％，其中ρ1为聚集体的测试密度，ρ2为聚集体的平均密度，所述ρ2为聚集体中各组分在聚集体中的质量百分含量*各组分的理论密度的值的总和。
第三方面，本申请实施例提供一种负极材料的制备方法，所述方法包括以下步骤：
将活性物质、掺杂剂、第一碳源和溶剂混合后制备前驱体；及
对所述前驱体在800℃～980℃进行一次热处理，得到聚集体。
在一种可行的实施方式中，所述活性物质包括Li、Na、K、Sn、Ge、Si、Fe、Mg、Ti、Zn、Al、P、Cu及SiO x中的至少一种，其中，0＜x≤2。
在一种可行的实施方式中，所述掺杂剂包括氟源、磷源及氮源中的至少一种。
在一种可行的实施方式中，所述掺杂剂包括氟源、磷源及氮源中的至少一种，所述氟源包括氟化物，所述氟化物包括氟化氢、氟化锂、氟化铵、氟化钾、氟化铝、氟化镁、氟化钠、氟化钙、四丁基氟化铵、三乙基甲氧甲基氟化铵、氟硼酸铵及四丁基氟硼酸铵中的至少一种。
在一种可行的实施方式中，所述掺杂剂包括氟源、磷源及氮源中的至少一种，所述磷源包括三苯基膦、四苯基溴化磷、1-丁基-3-甲基咪唑六氟磷酸钠、磷化氢、磷酸钠、亚磷酸钠、单质磷、磷酸氢钠、磷酸二氢钠、亚磷酸氢钠及磷酸中的至少一种。
在一种可行的实施方式中，所述掺杂剂包括氟源、磷源及氮源中的至少一种，所述氮源包括氨气、氯化铵、碳酸铵、碳酸氢铵、尿素、硫脲、氮化锂、三聚氰胺及水合肼中的至少一种。
在一种可行的实施方式中，所述第一碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种。
在一种可行的实施方式中，所述活性物质、掺杂剂和第一碳源的质量比为 (30～120)：(0.9～20)：(10～50)。
在一种可行的实施方式中，所述溶剂包括有机溶剂。
在一种可行的实施方式中，所述溶剂包括有机溶剂，所述有机溶剂包括乙醇、乙二醇、丙醇、丁醇及正戊醇中的至少一种。
在一种可行的实施方式中，所述将活性物质、掺杂剂、第一碳源和溶剂混合的步骤具体为：将所述活性物质分散在溶剂中再加入掺杂剂和第一碳源。
在一种可行的实施方式中，所述将活性物质、掺杂剂、第一碳源和溶剂混合的步骤中还加入了添加剂。
在一种可行的实施方式中，所述添加剂包括表面活性剂及偶联剂中的至少一种。
在一种可行的实施方式中，所述添加剂包括表面活性剂，所述表面活性剂包括正十八酸、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、棕榈酸、十四烷酸、十一烷酸、十六烷基三甲基溴化胺及聚乙烯吡咯烷酮中的至少一种。
在一种可行的实施方式中，所述添加剂包括偶联剂，所述偶联剂包括硅烷偶联剂，所述硅烷偶联剂包括γ-氨丙基三乙氧基硅烷、γ-缩水甘油醚氧丙基三甲氧基硅烷及γ-甲基丙烯酰氧基丙基三甲氧基硅烷中的至少一种。
在一种可行的实施方式中，所述添加剂与活性物质的质量比为(0.01～5)：(50～100)。
在一种可行的实施方式中，所述将活性物质、掺杂剂、第一碳源和溶剂混合的步骤中还加入了金属氧化物及导电增强剂中的至少一种。
在一种可行的实施方式中，所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种。
在一种可行的实施方式中，所述金属氧化物呈片状和/或长条状。
在一种可行的实施方式中，所述金属氧化物的长径比大于2。
在一种可行的实施方式中，所述金属氧化物与活性物质的质量比为(0.5～10)：(30～100)。
在一种可行的实施方式中，所述导电增强剂与活性物质的质量比为(0.01～15):(50～100)。
在一种可行的实施方式中，所述导电增强剂的电导率为10 0S/m～10 8S/m。
在一种可行的实施方式中，所述导电增强剂呈片状和/或长条状。
在一种可行的实施方式中，所述导电增强剂的长径比为2～5000。
在一种可行的实施方式中，所述导电增强剂包括合金材料及导电碳中的至少一种。
在一种可行的实施方式中，所述制备所述前驱体的步骤还包括将活性物质、掺杂剂、第一碳源、溶剂混合后进行分散处理和干燥处理中的至少一种。
在一种可行的实施方式中，所述分散处理包括机械搅拌、超声分散及研磨分散中的至少一种。
在一种可行的实施方式中，所述干燥处理的温度为30℃～400℃。
在一种可行的实施方式中，所述干燥处理的时间为1h～15h。
在一种可行的实施方式中，所述前驱体进行一次热处理之前，还包括对所述前驱体进行密实化处理，使得所述聚集体的孔隙率≤10％且耐压硬度≥100MPa。
在一种可行的实施方式中，所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种。
在一种可行的实施方式中，所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合。
在一种可行的实施方式中，所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合，所述机械融合所用的融合机的转速为500r/min～3000r/min。
在一种可行的实施方式中，所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合，所述机械融合所用的融合机刀具间隙宽度为0.01cm～0.5cm。
在一种可行的实施方式中，所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合，所述机械融合时间至少为0.5h。
在一种可行的实施方式中，所述一次热处理的时间为1h～5h。
在一种可行的实施方式中，所述一次热处理在第一保护性气氛中进行。
在一种可行的实施方式中，所述一次热处理在第一保护性气氛中进行，所述第一 保护性气氛的气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
在一种可行的实施方式中，所述方法还包括对所述聚集体进行碳包覆处理。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述第二碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述聚集体与所述第二碳源的质量比为(20～100)：(10～80)。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理的温度为800℃～900℃。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理的时间为1h～5h。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理在第二保护性气氛中进行。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理在第二保护性气氛中进行，所述第二保护性气氛的气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理后，还进行粉碎、筛分和除磁中的至少一种；
在一种可行的实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理后，还进行粉碎、筛分和除磁中的至少一种，所述筛分的目数为≥500目。
第四方面，本申请实施例提供一种锂离子电池，所述锂离子电池包含第一方面或第二方面所述的负极材料，或第三方面所述的制备方法制得的负极材料。
本申请的技术方案至少具有以下有益的效果：掺杂元素加入可以促进碳材料的与活性物质的结合，此外可以提升碳材料的石墨化度，从而提高导电性。掺杂元素在 碳材料中诱导产生了具有高活性和选择性的活性位点，这些活性位点一方面更加容易与活性物质表面结合，形成更加稳固的连接；另一方面，由于活性增加，能垒降低，碳原子的重排阻力降低，在高温热处理过程中更加容易形成有序排列，表现为局部短程有序度增加，石墨化度得到部分提高。
本申请提供的制备方法操作简单，能够适用于扩大化生产，制备得到负极材料能够有效提高锂电池充放电循环的稳定性，有效降低负极材料的膨胀率。
附图说明
图1为一实施方式的负极材料的制备方法流程图。
具体实施方式
为了更好的理解本申请的技术方案，下面结合附图对本申请实施例进行详细描述。
应当明确，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本申请保护的范围。
在本申请实施例中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请。在本申请实施例和所附权利要求书中所使用的单数形式的“一种”、“所述”和“该”也旨在包括多数形式，除非上下文清楚地表示其它含义。
应当理解，本文中使用的术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
一实施方式的负极材料，包括聚集体，聚集体包括活性物质、碳材料及掺杂元素，碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到G带和在1280cm -1至1380cm -1观察到D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1～2.5。
本实施方式的掺杂元素在碳材料中诱导产生了具有高活性和选择性的活性位点， 这些活性位点一方面更加容易与活性物质表面结合，形成更加稳固的连接；另一方面，由于活性增加，能垒降低，碳原子的重排阻力降低，在高温热处理过程中更加容易形成有序排列，表现为局部短程有序度增加，石墨化度得到部分提高，从而提高碳材料导电性。
具体地，I D/I G可以为1、1.2、1.5、1.7、1.8、2、2.1、2.2或2.5，当然也可以是上述范围内的其他值，在此不做限定。优选地，I D/I G为1.7～2.3，石墨化度在此范围内的碳材料具有较好的电子导电性。
一实施方式的负极材料，包括聚集体，聚集体包括活性物质、碳材料及掺杂元素，掺杂元素能够诱导碳材料产生路易斯酸活性位点，至少部分活性物质通过路易斯酸活性位点与所述碳材料结合。
掺杂元素加入可以促进碳材料的与活性物质的结合，此外可以提升碳材料的石墨化度，从而提高导电性。该掺杂元素和碳原子的电负性差异极大，掺杂元素的引入使得碳原子的电荷分布不均，产生路易斯酸位点，在碳材料中诱导产生了具有高活性和选择性的活性位点，这些活性位点一方面更加容易与活性物质表面结合，形成更加稳固的连接。基于该原理，掺杂元素越趋近于碳材料或活性物质的表面，越容易诱导碳材料产生路易斯酸位点。
需要说明的是，掺杂元素是以原子形式存在于聚集体中，可以采用透射电镜和高角度环形暗场扫描透射电镜观察到原子形式的掺杂元素。
在一些实施方式中，掺杂元素包括氟、氮及磷中的至少一种；可以理解，掺杂元素可以为氟、氮或磷；也可以是氟、氮的组合或氟、磷的组合或氮、磷的组合；也可以同时含有氟、氮及磷。
在一些实施方式中，掺杂元素在聚集体中的含量为50ppm～20000ppm。掺杂元素的含量具体可以为50ppm、100ppm、500ppm、1000ppm、2000ppm、4000ppm、5000ppm、10000ppm、20000ppm等等；当然也可以是上述范围内的其他值，在此不做限定。在此范围内，能够有效提升碳材料的石墨化度，有利于提高活性物质的界面的稳定性，进而提高材料的循环稳定性；负极材料的首次效率、膨胀率、循环寿命均得到改善。掺杂元素含量可以通过离子色谱法、成分分析法或能谱分析法(EDX分析法)等测试方法获得。
在一些实施方式中，活性物质及碳材料中的至少一种含有掺杂元素。
在一些实施方式中，掺杂元素分布于活性物质的表面和/或内部。当掺杂元素位于分布活性物质的内部时，部分的掺杂元素取代材料晶体结构中的原子，并与邻近的原子形成价键，部分掺杂元素分布在晶体结构中的晶格缺陷中。如Si材料，氟元素取代硅晶体结构中的硅原子，并与邻近的硅原子形成氟-硅键，也可以是分布在硅基材料晶体结构的晶格缺陷中。
在另一些实施方式中，掺杂元素分布于碳材料的表面和/或内部。当掺杂元素位于分布碳材料的内部时，部分的掺杂元素取代碳材料晶体结构中的原子，并与邻近的碳原子形成价键，部分掺杂元素分布在碳晶体结构中的晶格缺陷中。
当然，在一些实施方式中，掺杂元素既分布于活性物质的表面和/或内部，还分布于碳材料的表面和/或内部。
需要说明的是，由于掺杂元素掺杂含量极低，不足以构成长程有序结构，不会使材料本身的晶体结构产生大的改变，从而能够更好地保持材料的结构稳定性。
在一些实施方式中，在聚集体中，活性物质分布于碳材料之间或表面，优选地，活性物质均匀分散在碳材料中。
在一些实施方式中，碳材料之间形成有孔隙，孔隙中填充有至少部分活性物质；这种填充的方式能够有效的利用碳材料之间形成的孔隙，使得分散在孔隙中的活性物质在充放电发生体积变化时具有一定的形变空间，降低了因为体积变化造成的应力的破坏。
在一些实施方式中，碳材料的孔容≥0.35cm 3/g。其中碳材料的孔容包括碳材料与碳材料之间形成的孔隙结构的孔容以及多孔碳材料(碳材料本身多孔结构)的孔容。具备不低于0.35cm 3/g孔容大小，一方面内部存在的孔隙可以很好地容纳活性物质，为活性物质的膨胀预留空间；另一方面适当的孔容可以在后续的碳包覆过程中，为表面包覆的碳渗透提供更多的通道，有利于碳的包覆。碳材料的孔容通过气体吸附BET方法进行测试。
在一些实施方式中，活性物质包括活性粒子。
在一些实施方式中，活性物质指的是可以与锂反应，进行脱嵌锂的物质。具体地，活性物质包括Li、Na、K、Sn、Ge、Si、Fe、SiO x(0＜x≤2)、Mg、Ti、Zn、Al、P及 Cu中的至少一种；活性物质可以是金属单质。在一些实施方式中，活性物质具体可以是Si颗粒、Sn颗粒、Ge颗粒、Al颗粒，在另外的一些实施方式中，活性物质也可以是硅锂合金、硅镁合金等，当然，需要说明的是，在一些情况下，活性物质包括单质颗粒和合金。
在一些实施方式中，活性物质的中值粒径为1nm～300nm。具体可以是1nm、5nm、10nm、50nm、75nm、100nm、150nm、200nm、250nm、300nm等等，具体不做限制，
在一些实施方式中，碳材料包括结晶碳、非晶碳、人造石墨、天然石墨、软碳、硬碳、无定型碳、碳纳米管、碳纤维及石墨烯中至少一种。
在一些实施方式中，活性物质与碳材料的质量比为(90～10)：(10～90)。具体可以是90：10、80：20、70：30、60：40、50：50、40：60、30：70、20：80、10：90等等，具体不做限制。
在一些实施方式中，聚集体的孔隙率≤10％，聚集体的耐压硬度≥100MPa。
此时，聚集体的孔隙率较低，即其密实度很高，一方面有助于提高复合材料的能量密度，另一方面高密实度的材料即使表层被破坏，电解液也不容易渗透进聚集体内部，有利于保护内部的活性物质颗粒，减少电解液与活性物质的接触几率，从而有利于形成稳定的固体电解质膜；并且高密实化的聚集体具有较高的耐压硬度，能够对冲膨胀所带来的应力效应，提高负极材料的结构稳定性，可以有效抑制负极材料体积膨胀，降低膨胀率，提升电池循环性能。
使用压汞仪通过压汞法测定孔隙率。孔隙率至少测定三次，采用至少三次的算术平均作为测定结果。
耐压硬度通过纳米压痕仪测试，采用载荷0.6N，压痕深度0.5μm的方法测得。
在一些实施方式中，聚集体的孔隙率≤10％，聚集体的孔隙率具体可以是10％、9％、9.5％、8％、8.5％、7.5％、7％、6.5％、6％或5％等等，当然也可以是上述范围内的其它值，在此不做限定。可以理解地，聚集体的孔隙率较低，即其密实度很高，有利于形成稳定的固体电解质膜，减少电解液与活性物质的接触。优选地，聚集体的孔隙率≤5％，更优选地，聚集体的孔隙率≤3％。
聚集体的耐压硬度≥100MPa；聚集体的耐压硬度具体可以是100MPa、150MPa、 250MPa、300MPa、450MPa、500MPa、750MPa、900MPa、1150MPa、1200MPa或1250MPa等等，当然也可以是上述范围内的其它值，在此不做限定。因为其具有较强的刚性，粒子结构稳定性强，可以抵御一定的体积膨胀应力，从而降低膨胀，提升电池循环稳定性。优选地，聚集体的耐压硬度≥200MPa，更优选地，聚集体的耐压硬度≥400MPa。
在一些实施方式中，聚集体密度满足以下关系：聚集体的测试密度与聚集体的平均密度的差值≤5％。聚集体颗粒的密度与平均密度越接近，相差越小，说明颗粒内部的孔隙越少，越密实，有利于形成稳定的固体电解质膜，减少电解液与活性物质的接触。
具体地，聚集体密度计算如下：(ρ1-ρ2)/ρ2≤5％，其中ρ1为聚集体的测试密度，ρ2为聚集体的平均密度；
其中，ρ2为聚集体中各组分在聚集体的质量百分含量*各组分的理论密度的值的总和。
具体的示例中，当聚集体包括活性物质和碳材料时，ρ2＝活性物质在聚集体中的质量百分含量*活性物质理论密度+碳材料在聚集体中的质量百分含量*碳材料理论密度。
在一些实施方式中，聚集体还包括金属氧化物，将金属氧化物与活性物质进行复合，可以降低活性物质的膨胀，提升长循环性能，且聚集体有更高的耐压硬度。需要说明的是，此时聚集体的平均密度ρ2＝活性物质在聚集体中的质量百分含量*活性物质理论密度+金属氧化物在聚集体中的质量百分含量*金属氧化物理论密度+碳材料在聚集体中的质量百分含锂*碳材料理论密度。
此时，当聚集体还包括金属氧化物时，氟元素还分布于金属氧化物的内部或表面；当F元素位于分布金属氧化物的内部时，部分的F元素取代金属氧化物晶体结构中的原子，并与邻近的原子形成价键，部分掺杂元素分布在金属氧化物晶体结构中的晶格缺陷中。具体如金属氧化物为SnO 2，则是取代SnO 2中晶体结构中的Sn原子，并与邻近的原子形成价建，也可以是分布在晶体结构的晶格缺陷中。
在一些实施方式中，至少部分金属氧化物填充于碳材料之间的孔隙中。
在一些实施方式中，金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包 括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种；具体地，金属氧化物可以是GeO 2、SnO 2、ZnO、TiO 2、Fe 3O 4、MgO、SiO 2及CuO中任意一种。
在一些实施方式中，活性物质与金属氧化物的质量比为(30～100)：(0.5～10)。具体可以是30：0.5、40：1、50：2、60：2、70：3、80：6、90：7.5、100：10或100：2等等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，金属氧化物呈片状和/或长条状。
在一些实施方式中，金属氧化物的长径比值大于2。需要说明的是，当金属氧化物为长条状时，长径比具体是指颗粒的长度与颗粒的粒径的比值，这里的粒径指的是垂直于长条状金属氧化物长度方向的截面周缘上的两点之间的最大直线距离；当金属氧化物为片状时，长径比具体是指片状金属氧化物的长度与宽度的比值。具体地，金属氧化物的长径比值可以是2、2.5、3、3.5、4、4.5、5、6、7、8、9、12、15、17、18、22等等，当然也可以是上述范围内的其他值，在此不做限定。根据多次试验发现，金属氧化物的长径比大于2时，可以提升金属氧化物与活性物质的物理结合力，从而缓冲活性物质的体积膨胀变化，提升循环性能。
在一些实施方式中，金属氧化物与金属氧化物之间的最短距离≥100nm。最短距离控制可以使得金属氧化物之间能够填充活性物质，可以将金属氧化物作为结构的支撑体增强材料的稳定性，从而缓冲活性物质的体积膨胀变化，提升循环性能。具体可以是100nm、150nm、200nm、250nm、300nm或400nm等等，本实施方式的金属氧化物与金属氧化物之间的最短距离指的是任意的两个金属氧化物颗粒的最短直线距离。优选地，金属氧化物的间距≥200nm。距离测试方法如下：以任意金属氧化物进行切面制样，任选其中的颗粒，测试颗粒中，任意两个金属氧化物的之间的最短距离，测量不低于50次，取平均值。
在一些实施方式中，聚集体中还包括导电增强剂，该导电增强剂一方面可以提供更多的载流子的传输通道，进而增强载流子在材料内部的传输；另一方面，同时还具备优异的机械性能，可以作为结构的支撑体增强材料的稳定性。
此时，当聚集体还包括导电增强剂时，氟元素还分布于导电增强剂材料的内部或表面；当F元素位于分布导电增强剂材料的内部时，部分的F元素取代导电增强剂材料晶体结构中的原子，并与邻近的原子形成价键，部分掺杂元素分布在导电增强剂 材料晶体结构中的晶格缺陷中。
当聚集体包括活性物质、导电增强剂和碳材料时，ρ2＝活性物质在聚集体中的质量百分含量％*活性物质理论密度+导电增强剂在聚集体中的质量百分含量*导电增强剂的理论密度+碳材料在聚集体中的质量百分含量*碳材料理论密度。
当聚集体包括活性物质、金属氧化物、导电增强剂和碳材料时，ρ2＝活性物质在聚集体中的质量百分含量％*活性物质理论密度+金属氧化物在聚集体中的质量百分含量*金属氧化物理论密度+导电增强剂在聚集体中的质量百分含量*导电增强剂的理论密度+碳材料在聚集体中的质量百分含量*碳材料理论密度。
在一些实施方式中，至少部分导电增强剂填充于碳材料之间的孔隙中。
在一些实施方式中，导电增强剂包括合金材料及导电碳中的至少一种；其中，合金材料可以包括锌合金、铝合金、铜合金、硅合金、镍合金和钛合金中的至少一种，导电碳可以包括碳纳米管、碳纤维、石墨纤维中的至少一种。
在一些实施方式中，导电增强剂的电导率为10 0S/m～10 8S/m。具体地，导电增强剂的电导率可以为1S/m、10S/m、100S/m、10 3S/m、10 4S/m、10 5S/m或10 8S/m等。使用粉末电阻率测试仪负极材料的电导率。
在一些实施方式中，导电增强剂呈片状和/或长条状。
在一些实施方式中，导电增强剂与活性物质的质量比为(0.01～15):(50～100)。具体可以是0.01：50、15：50、0.05：55、0.1：60、1：50、5：60、7.5：75、10：80或15：100等等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，导电增强剂的长径比为2～5000。需要说明的是，当导电增强剂为长条状时，长径比具体是指颗粒的长度与颗粒的粒径的比值，这里的粒径指的是垂直于长条状导电增强剂长度方向的截面周缘上的两点之间的最大直线距离；当导电增强剂为片状时，长径比具体是指片状导电增强剂的长度与宽度的比值。具体地，导电增强剂的长径比值可以是2、30、46、150、360、670、800、900、1500、2000、3000、4000、5000等等，当然也可以是上述范围内的其他值，在此不做限定。根据多次试验发现，长径比在该范围内的导电增强剂，具有较优异的机械性能，可以作为结构的支撑体增强材料的稳定性，从而缓冲活性物质的体积膨胀变化，提升循环性能。
在一些实施方式中，负极材料还包括包覆于聚集体的至少部分表面的碳层。优选地，碳层分布于聚集体的表面。碳层能够减少活性物质与电解液接触，减少钝化膜生成，提升电池可逆电容量。
在一些实施方式中，碳层的材料包括无定形碳。
在一些实施方式中，碳层的厚度为10nm～5000nm，具体地，碳层的厚度可以是10nm、50nm、100nm、400nm、500nm、750nm、1000nm、1500nm、2000nm、2500nm、3000nm、4000nm、5000nm等等，当然也可以是上述范围内的其他值，在此不做限定。碳层过厚，不利于材料大倍率充放电，降低负极材料的综合性能；碳层过薄，不利于增加负极材料的导电性且对材料的体积膨胀抑制性能较弱，导致长循环性能价差。
在一些实施方式中，负极材料的中值粒径为0.5μm～30μm，具体可以是0.5μm、1.5μm、3μm、10μm、16μm、26μm等等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，负极材料的中值粒径控制在上述范围内，有利于负极材料循环性能的提升。优选地，负极材料的中值粒径为1.5μm～15μm。
在一些实施方式中，负极材料的比表面积为≤10m 2/g，具体可以是10m 2/g、7m 2/g、6m 2/g、4m 2/g、2m 2/g、1m 2/g等等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，负极材料的比表面积控制在上述范围内，有利于抑制体积膨胀，有利于负极材料循环性能的提升，优选地，负极材料的比表面积为≤5m 2/g。使用麦克比表面积分析仪测试负极材料的比表面积。
在一些实施方式中，聚集体与碳层的质量比为(90～10)：(10～90)，具体可以是90：10、80：20、70：30、60：40、50：50、40：60、30：70、20：80、10：90等等，具体不做限制。
在一些实施方式中，负极材料还包括形成于活性物质至少部分表面的氧化层；当活性物质为硅粒子时，氧化层为氧化硅。
在一些实施方式中，氧化层的厚度为1nm～100nm，氧化层的厚度可以是1nm、10nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm、90nm、100nm等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，氧化层具有孔隙，从而为活性物质膨胀提供了空间，降低了 活性物质的体积膨胀效应。
需要说明的是，上述各个实施方式的负极材料在不相互矛盾的情况下，可以任意进行组合，比如聚集体的耐压硬度、孔隙率与密度进行组合限定等。
如图1所示，另一实施方式的负极材料的制备方法，包括以下步骤：
步骤S100，将活性物质、掺杂剂、第一碳源及溶剂混合后制备前驱体；
步骤S200，对前驱体在800℃～980℃进行一次热处理，得到聚集体；
步骤S300，将聚集体进行碳包覆处理，得到负极材料。
本实施方式的制备方法制备得到的负极材料包括聚集体和包覆于聚集体表面的碳层，聚集体包括活性物质、碳材料和掺杂元素，碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到G带和在1280cm -1至1380cm -1观察到D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1～2.5。
通过在活性物质、碳源中加入掺杂剂，掺杂剂加入可以促进碳材料的与活性物质的结合，此外可以提升碳材料的石墨化度，从而提高导电性。掺杂元素在碳材料中诱导产生了具有高活性和选择性的活性位点，这些活性位点一方面更加容易与活性物质表面结合，形成更加稳固的连接；另一方面，由于活性增加，能垒降低，碳原子的重排阻力降低，在高温热处理过程中更加容易形成有序排列，表现为局部短程有序度增加，石墨化度得到部分提高。而且掺杂剂的加入，有利于提高活性物质的界面的稳定性，进而提高材料的循环稳定性；负极材料的首次效率、膨胀率、循环寿命均得到改善。
以下结合实施例具体介绍本申请的制备方法：
步骤S100，将活性物质、掺杂剂、第一碳源及溶剂混合后制备前驱体。
在一些实施方式中，活性物质的中值粒径为1nm～300nm。具体可以是1nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm、90nm、100nm、120nm、150nm、200nm、250nm、300nm等等，当然也可以是上述范围内的其他值，在此不做限定。活性物质的中值粒径控制在上述范围内，有利于负极材料循环性能的提升。
在一些实施方式中，活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x≤2)、Fe、Mg、Ti、Zn、Al、P或Cu中的至少一种；活性物质可以是金属单质。在一些实 施方式中，活性物质具体可以是Si颗粒、Sn颗粒、Ge颗粒、Al颗粒，在另外的一些实施方式中，活性物质也可以是硅锂合金、硅镁合金等，当然，需要说明的是，在一些情况下，活性物质包括单质颗粒和合金。
在一些实施方式中，活性物质为SiO x(0＜x≤2)时，掺杂剂为氟化物时，氟化物的加入，能有效促进SiO x的歧化转变，形成Si和SiO 2，从而形成更加均匀的SiO 2包覆层，有利于硅的界面的稳定和改善，提高材料的循环稳定性；而且氟化物会对硅表层的氧化层进行刻蚀，获得孔隙，从而为硅膨胀提供了空间，降低了硅的体积膨胀效应。
在一些实施方式中，掺杂剂包括氟源、磷源及氮源中的至少一种。采用该种类的掺杂剂，掺杂的原子和碳原子的电负性差异极大，掺杂原子的引入使得碳原子的电荷分布不均，产生路易斯酸位点，这些活性位点一方面更加容易与活性物质表面结合，形成更加稳固的连接；另一方面，由于活性增加，能垒降低，碳原子的重排阻力降低，在高温热处理过程中更加容易形成有序排列，表现为局部短程有序度增加，石墨化度得到部分提高。而且掺杂元素的加入，有利于提高活性物质的界面的稳定性，进而提高材料的循环稳定性；负极材料的首次效率、膨胀率、循环寿命均得到改善。
在一些实施方式中，氟源包括氟化物，氟化物包括氟化氢、氟化锂、氟化铵、氟化钾、氟化铝、氟化镁、氟化钠、氟化钙、四丁基氟化铵、三乙基甲氧甲基氟化铵、氟硼酸铵及四丁基氟硼酸铵中的至少一种。
在一些实施方式中，磷源包括三苯基膦、四苯基溴化磷、1-丁基-3-甲基咪唑六氟磷酸钠、磷化氢、磷酸钠、亚磷酸钠、单质磷、磷酸氢钠、磷酸二氢钠、亚磷酸氢钠及磷酸中的至少一种。
在一些实施方式中，氮源包括氨气、氯化铵、碳酸铵、碳酸氢铵、尿素、硫脲、氮化锂、三聚氰胺及水合肼中的至少一种。
在一些实施方式中，第一碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种。
在一些实施方式中，活性物质、掺杂剂和第一碳源的质量比为(30～120)：(0.9～20)：(10～50)。具体地，活性物质、掺杂剂和第一碳源的质量比可以是30：0.9：10、40： 5：15、70：10：20、60：12：30、80：20：50、100：10：10、110：5：20、120：3：15等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，溶剂包括有机溶剂。具体地，有机溶剂包括甲醇、乙醇、乙二醇、丙醇、异丙醇、丙三醇、正丁醇、异丁醇及戊醇中的至少一种。将各个组分加入有机溶剂中进行湿法球磨，可以提高组分混合均匀度，并且有利于快速干燥。
在一些实施方式中，将活性物质、掺杂剂、第一碳源、溶剂混合的步骤具体为：将活性物质分散在有机溶剂中再加入掺杂剂和第一碳源。
在一些实施方式中，制备前驱体的步骤还包括将活性物质、掺杂剂、第一碳源、溶剂混合后进行分散处理、干燥处理中的至少一种。
优选地，将活性物质、掺杂剂、第一碳源和溶剂混合后依次进行分散处理、干燥处理。
在一些实施方式中，分散处理包括机械搅拌、超声分散及研磨分散中的至少一种；避免粒子发生团聚，并且可以使得活性物质分散为较小的纳米颗粒。
在一些实施方式中，干燥处理的温度为30℃～400℃，干燥处理的时间为1h～15h；具体可以是30℃、40℃、50℃、80℃、100℃、120℃、150℃、180℃、200℃、250℃、280℃、300℃或400℃等等，干燥处理的时间为1h～15h，具体可以是1h、3h、5h、7h、9h、10h、12h或15h等等，干燥处理方式例如可以是炉内烘干、冷冻干燥、搅拌蒸干、喷雾干燥等，本实施例中的干燥处理可以尽可能地将前驱体溶液中的溶剂去除。
在一些实施方式中，活性物质、掺杂剂、第一碳源和溶剂混合的步骤中还加入了添加剂。该实施方式中的添加剂，可以有效增强活性物质与碳材料的连接稳定性，从而形成牢固的体系。
在一些实施方式中，添加剂包括表面活性剂及偶联剂中的至少一种。经试验发现，采用此种类的添加剂能够有效增强活性物质与碳材料的连接稳定性，以形成牢固的体系，降低孔隙率；从而使得负极材料的膨胀率降低，循环稳定性增高。
具体地，表面活性剂包括但不限于正十八酸、月桂酸、聚丙烯酸(PAA)、十二烷基苯磺酸钠(SDBS)、正二十酸、棕榈酸、十四烷酸、十一烷酸、十六烷基三甲基溴化胺及聚乙烯吡咯烷酮(PVP)中的至少一种。
偶联剂包括硅烷偶联剂，具体地，硅烷偶联剂包括但不限于γ-氨丙基三乙氧基硅烷、γ-缩水甘油醚氧丙基三甲氧基硅烷及γ-甲基丙烯酰氧基丙基三甲氧基硅烷中的至少一种。
在一些实施方式中，活性物质与添加剂的质量比为(50～100)：(0.01～5)。
在一些实施方式中，将活性物质、掺杂剂、第一碳源和溶剂混合的步骤中还加入了金属氧化物及导电增强剂中的至少一种。
在一些实施方式中，金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种。
在一些实施方式中，金属氧化物呈片状和/或长条状。
在一些实施方式中，金属氧化物的长径比大于2。
在一些实施方式中，导电增强剂与活性物质的质量比为(0.01～15):(50～100)。
在一些实施方式中，导电增强剂的电导率为10 0S/m～10 8S/m。
在一些实施方式中，导电增强剂呈片状和/或长条状。
在一些实施方式中，导电增强剂的长径比为2～5000。
在一些实施方式中，导电增强剂包括合金材料及导电碳中的至少一种。
在一些实施方式中，前驱体进行一次热处理之前，还包括对前驱体进行密实化处理，使得聚集体的孔隙率≤10％且耐压硬度≥100MPa；
在一些实施方式中，密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理、及浸渍处理中的至少一种；
在一些实施方式中，融合处理为机械融合；利用对前驱体进行融合处理，提高负极材料的耐压硬度，再进行一次热处理，增强颗粒结构的稳定性，同时可以增强活性物质与第一碳源之间的连接稳定性，降低孔隙率。当然，在其他的实施方式中，还可以采用其他方法进行密实化处理，比如模压、等静压、浸渍等工艺，只要能使得聚集体的孔隙率≤10％且耐压硬度≥100MPa即可。
在一些实施方式中，机械融合所用的融合机的转速为500r/min～3000r/min；
在一些实施方式中，机械融合所用的融合机刀具间隙宽度为0.01cm～0.5cm；
在一些实施方式中，机械融合时间至少为0.5h。
步骤S200，对前驱体在800℃～980℃进行一次热处理，得到聚集体。
在一些实施方式中，一次热处理的方式例如可以是真空烧结、热压烧结或者常压烧结。一次热处理的温度为800℃～980℃，具体可以是800℃、810℃、820℃、830℃、840℃、850℃、860℃、870℃、880℃、890℃、900℃、910℃、920℃、930℃、940℃、950℃、960℃、970℃、980℃等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，一次处理时间为1h～5h，具体可以是1h、2h、3h、4h、5h等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，一次热处理在第一保护性气氛中进行；具体地，第一保护性气氛的气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
在一些实施方式中，一次热处理后，还进行粉碎操作，粉碎方式为机械式粉碎机、气流粉碎机和低温粉碎机中任意一种。
步骤S300，将聚集体进行碳包覆处理，得到负极材料。
需要说明的是，本实施方式的负极材料可以不进行碳包覆，此时，步骤S300可以省略。
在一些实施方式中，碳包覆处理的具体步骤可以为：将聚集体与第二碳源进行混合进行、二次热处理。
在一些实施方式中，第二碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种。
在一些实施方式中，聚集体与第二碳源的质量比为(20～100)：(10～80)。聚集体与第二碳源的质量比可以为20：10、30：15、50：60、80：30、90：20、100：10等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，二次热处理的方式例如可以是真空烧结、热压烧结或者常压烧结。二次热处理的温度为800℃～900℃。具体可以是800℃、810℃、820℃、830℃、840℃、850℃、860℃、870℃、880℃、890℃、900℃等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，二次热处理的时间为1h～5h；具体可以是1h、2h、3h、4h、5h等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，二次热处理在第二保护性气氛中进行；第二保护性气氛的气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
在一些实施方式中，二次热处理后，还进行粉碎、筛分和除磁中的至少一种；优选地，二次热处理后，还依次进行粉碎、筛分和除磁。
在一些实施方式中，粉碎方式为机械式粉碎机、气流粉碎机、低温粉碎机中任意一种。
在一些实施方式中，筛分的方式为固定筛、滚筒筛、共振筛、滚轴筛、振动筛、链条筛中任意一种，筛分的目数为≥500目，具体地，筛分的目数可以是500目、600目、700目、800目等等，负极材料的粒径控制在上述范围内，有利于负极材料循环性能的提升。
在一些实施方式中，除磁的设备为永磁筒式磁选机、电磁除铁机、脉动高梯度磁选机中任意一种，除磁是为了最终控制负极材料的磁性物质含量，避免磁性物质对锂离子电池的放电效果以及电池在使用过程中的安全性。
本申请还提供一种锂离子电池，锂离子电池包含上述负极材料，或上述制备方法制得的负极材料。
本公开中所述中值粒径指的是平均粒径，其物理意义是颗粒的累计粒度分布百分数达到50％时所对应的粒径，通过马尔文粒度仪测试。马尔文粒度仪利用颗粒对光的散射现象，根据散射光能的分布综合换算出被测颗粒的粒径分布。
下面分多个实施例对本申请实施例进行进一步的说明。其中，本申请实施例不限定于以下的具体实施例。在不变主权利的范围内，可以适当的进行变更实施。
实施例1
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵与酚醛树脂的质量比为50:4.3：24.5；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体；
2)前驱体放置于热处理炉中，通入氩气，升温至900℃，反应3h，获得聚集体；
3)将聚集体、沥青按质量比40：30进行混合，搅拌、分散均匀后，然后进行干 燥处理，干燥温度为150℃，时间为5h，将干燥物料加入到高温箱式炉中，通入氮气，在890℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为600ppm；碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm - 1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.01。
采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为10.6％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为45MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为2.1％。
实施例2
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为70nm的硅颗粒分散在乙醇溶液(体积百分比浓度为40％)中，然后加入三乙基甲氧甲基氟化铵和蔗糖混合均匀，其中，硅颗粒、四丁基氟硼酸铵和葡萄糖的质量比为39:1.3：38.4，然后进行干燥处理，干燥温度为200℃，时间为3.5h，获得前驱体；
2)将前驱体放置于热处理炉中，通入氩气，升温至920℃，反应4h，获得聚集体；
3)然后将聚集体粉碎后，聚集体与酚醛树脂按质量比30：40进行配比，搅拌、分散均匀后，然后进行干燥处理，随后将干燥物料加入到高温箱式炉中，通入氮气，在890℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为12.1μm，比表面积为3.2m 2/g，碳层平均厚度为739nm，聚集体的氟元素含量为920ppm；碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.99。
实施例3
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为30nm的硅颗粒分散在乙二醇中，然后超声10min，之后添加1.5wt％H 2O 2添加剂，超声20min，干燥后与LiF、果糖混合获得前驱体；其中，硅颗粒、LiF与果糖的质量比为30:3：35；
2)将前驱体放置于热处理炉中，通入氩气，升温至800℃，反应5h，获得聚集体；
3)然后将聚集体、沥青按质量比40：35进行配比，搅拌、分散均匀后，然后在100℃干燥处理5h，随后将干燥物料加入到高温箱式炉中，通入氮气，在900℃条件下热处理2h后，进行粉碎、通过500目筛过筛，获得所述负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为12.1μm，比表面积为5.2m 2/g，碳层平均厚度为5.7nm，聚集体的氟元素含量为1030ppm，碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.94。
实施例4
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为80nm的硅颗粒分散在丙醇中，然后超声10min，然后加入MgF 2、葡萄糖混合均匀，硅颗粒、MgF 2和沥青的质量比为45:1.3：33.5，在250℃干燥2h后获得前驱体；
2)将前驱体放置于热处理炉中，通入氩气，升温至900℃，反应3h，获得聚集体。
3)然后将聚集体、沥青按质量比40：37进行配比，搅拌、分散均匀后，然后在250℃干燥2h后，随后将干燥物料加入到高温箱式炉中，通入氮气，在800℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得所述负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为9.1μm，比 表面积为4.2m 2/g，碳层平均厚度为5.7nm，聚集体的氟元素含量为590ppm，碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm - 1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.05。
实施例5
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为20nm的硅颗粒分散在丁醇中，然后加入四丁基氟化铵、聚氯乙烯混合均匀，硅颗粒、四丁基氟化铵和聚氯乙烯的质量比为30:0.9：33.5，在300℃干燥1h后获得前驱体；
2)将前驱体放置于热处理炉中，通入氩气，升温至880℃，反应3h，获得聚集体；
3)然后将聚集体、酚醛树脂按质量比55：65进行配比，搅拌、分散均匀后，然后进行干燥处理，随后将干燥物料加入到高温箱式炉中，通入氮气，在800℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得所述负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为15.1μm，比表面积为2.2m 2/g，碳层平均厚度为667nm；聚集体的氟元素含量为15060ppm。碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I G与G带的峰强度I D之间的比值I D/I G为1.85。
实施例6
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为120nm的硅颗粒分散在正戊醇中，然后加入氟硼酸铵、葡萄糖混合均匀，硅颗粒、氟硼酸铵和葡萄糖的质量比为30:2.0：48.5，在300℃干燥1h后获得前驱体；
2)将前驱体放置于热处理炉中，通入氩气，升温至980℃，反应3h，获得聚集体。
3)然后将聚集体、酚醛树脂按质量比44：50进行配比，搅拌、分散均匀后，然 后进行干燥处理，随后将干燥物料加入到高温箱式炉中，通入氮气，在900℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为10.1μm，比表面积为2.0m 2/g，碳层平均厚度为967nm；聚集体的氟元素含量为9620ppm。碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.9。
实施例7
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵与酚醛树脂的质量比为50:4.3：24.5；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体；
2)将前驱体放置融合机中，融合机的转速为500r/min，机械融合所用的融合机刀具间隙宽度为0.05cm，机械融合时间为0.5h；将融合后的物料置于热处理炉中，然后通入氩气在900℃条件下，进行一次热处理，保温3h，获得聚集体；
3)将聚集体、沥青按质量比40：30进行混合，搅拌、分散均匀后，然后进行干燥处理，干燥温度为150℃，时间为5h，将干燥物料加入到高温箱式炉中，通入氮气，在890℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为600ppm。碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm - 1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.49。采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为4.4％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为223MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为 2.1％。
实施例8
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为20nm的Ge颗粒分散在丁醇中，然后加入四丁基氟化铵、聚氯乙烯混合均匀，Ge颗粒、四丁基氟化铵和聚氯乙烯的质量比为100:20：50，在300℃干燥1h后获得前驱体；
2)将前驱体放置融合机中，融合机的转速为1500r/min，机械融合所用的融合机刀具间隙宽度为0.3cm，机械融合时间为1h；将融合后的物料置于热处理炉中，然后通入氮气在900℃条件下，进行一次热处理，保温3h，获得聚集体；
3)将聚集体、沥青按质量比50：10进行混合，搅拌、分散均匀后，然后进行干燥处理，干燥温度为150℃，时间为5h，将干燥物料加入到高温箱式炉中，通入氮气，在890℃条件下热处理3h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为12μm，比表面积为5.9m 2/g，碳层平均厚度为102nm；聚集体的氟元素含量为8040ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为4.3％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为198MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为1.8％。
实施例9
本实施例与实施例1的区别在于，步骤1)的不同，步骤1)加入添加剂。
具体的步骤1)为将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、月桂酸混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、月桂酸的质量比为50:4.3：24.5：3.3；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体；
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为602ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为11.5％；采用纳米压痕仪对聚集体 颗粒进行测试，得到聚集体的耐压硬度平均为69MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为2.6％。
实施例10
本实施例与实施例7的区别在于，步骤1)的不同，步骤1)加入添加剂。
具体的步骤1)为将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、γ-氨丙基三乙氧基硅烷混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、γ-氨丙基三乙氧基硅烷的质量比为50:4.3：24.5：3.3；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为605ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为3.6％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为365MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为2.2％。
实施例11
本实施例与实施例1区别在于，步骤1)的不同，步骤1)加入金属氧化物。
具体的步骤1)为将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、长径比为12的GeO 2颗粒混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、GeO 2颗粒的质量比为50:4.3：24.5：1.9；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、GeO 2颗粒及碳材料和掺杂于碳材料、GeO 2颗粒和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为601ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为10.2％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为78MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为2.3％，金属氧化物之间的间距的最 小值为26nm。
实施例12
本实施例与实施例7区别在于，步骤1)的不同，步骤1)加入金属氧化物。
步骤1)具体为1)将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、长径比为8的ZnO颗粒混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、ZnO颗粒的质量比为50:4.3：24.5：3.6；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料、ZnO颗粒和掺杂于碳材料、硅粉和ZnO颗粒中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为608ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为5.0％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为284MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为1.9％。金属氧化物的间距的最小值为106nm。
实施例13
本实施例与实施例1区别在于，步骤1)的不同，步骤1)加入导电增强剂。
具体的步骤1)为将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、直径20nm、长径比为500的碳纳米管(CNT)混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、CNT的质量比为50:4.3：24.5：0.5；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、CNT、碳材料和掺杂于碳材料、CNT和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为600ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为10.7％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为62MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为3.6％。
实施例14
本实施例与实施例7区别在于，步骤1)的不同，步骤1)加入导电增强剂。
步骤1)具体为1)将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、长径比18的FeSi 2混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、FeSi 2的质量比为50:4.3：24.5：2.1；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、FeSi 2、碳材料和掺杂于碳材料、FeSi 2及硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为610ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为4.5％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为205MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为1.2％。
实施例15
本实施例与实施例1区别在于，步骤1)的不同，步骤1)加入导电增强剂、金属氧化物。
具体的步骤1)为将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、长径比为22的SiO颗粒、直径20nm的CNT混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、SiO颗粒、CNT的质量比为50:4.3：24.5：2.9：0.3；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、SiO颗粒、CNT、碳材料和掺杂于碳材料、SiO颗粒、CNT、硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为590ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为12.9％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为99MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为2.1％。
实施例16
本实施例与实施例7区别在于，步骤1)的不同，步骤1)加入金属氧化物、导 电增强剂。
步骤1)具体为1)将中值粒径为50nm的硅颗粒分散在乙醇溶液(体积百分比浓度40％)中，然后加入三乙基甲氧甲基氟化铵、酚醛树脂、长径比为17的TiO 2颗粒、长径比为50的镍硅合金混合均匀，其中，硅颗粒、三乙基甲氧甲基氟化铵、酚醛树脂、TiO 2颗粒与镍硅合金的质量比为50:4.3：24.5：3.9：1.1；然后进行干燥处理，干燥温度为150℃，时间为5h，获得前驱体。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、TiO 2颗粒、镍硅合金、碳材料和掺杂于碳材料、TiO 2颗粒、镍硅合金和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为6.2m 2/g，碳层平均厚度为559nm；聚集体的氟元素含量为598ppm；采用压汞法对聚集体颗粒进行测试，聚集体的孔隙率为10.9％；采用纳米压痕仪对聚集体颗粒进行测试，得到聚集体的耐压硬度平均为229MPa。聚集体的测试密度与硅粉及碳材料的平均密度差为1.9％。
实施例17
本实施例的负极材料的制备方法，包括以下步骤：
1)将中值粒径为50nm的Al颗粒分散在乙二醇中，然后超声10min，之后添加1.5wt％H 2O 2添加剂混合均匀，超声20min，干燥后与氟化铝、果糖混合获得前驱体；其中，Al颗粒、LiF与果糖的质量比为120:10：50；
2)将前驱体放置于热处理炉中，通入氩气，升温至950℃，反应1.5h，获得聚集体；
3)然后将聚集体、沥青按质量比100：15进行配比，搅拌、分散均匀后，然后在100℃干燥处理5h，随后将干燥物料加入到高温箱式炉中，通入氮气，在900℃条件下热处理2h后，进行粉碎、通过500目筛过筛，获得所述负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括Al粉、碳材料和掺杂于碳材料、Al粉和硅粉中的氟元素，负极材料的中值粒径为11μm，比表面积为3.9m 2/g，碳层平均厚度为98nm；聚集体的氟元素含量为2190ppm。
实施例18
本实施例与实施例1区别在于，不进行碳包覆，即不包括步骤3)。
本实施例制得的负极材料包括聚集体，聚集体包括硅粉、碳材料和掺杂于碳材料和硅粉中的氟元素，负极材料的中值粒径为13μm，比表面积为26.2m 2/g；聚集体的氟元素含量为890ppm。
实施例19
按照与实施例5基本相同的方法制备纳米硅基复合负极材料，区别在于聚集体中氟含量为20000ppm，步骤2)中热处理温度为980℃。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.5。
实施例20
按照与实施例5基本相同的方法制备纳米硅基复合负极材料，区别在于聚集体中氟含量为21890ppm，然后热处理。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料以及氟元素，硅粉、碳材料的质量比为63.0：37.0，负极材料的中值粒径为13.8μm，比表面积为6.6m 2/g，碳层平均厚度为565nm；聚集体的氟元素含量为21890ppm。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm - 1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.8。
实施例21
按照与实施例5基本相同的方法制备纳米硅基复合负极材料，区别在于聚集体中氟含量为50ppm，步骤2)中热处理温度为980℃。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm - 1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.1。
实施例22
按照与实施例5基本相同的方法制备纳米硅基复合负极材料，区别在于聚集体中氟含量为39ppm，然后热处理。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括 硅粉、碳材料以及氟元素，硅粉、碳材料的质量比为62.5：37.5，负极材料的中值粒径为12.8μm，比表面积为5.9m 2/g，碳层平均厚度为549nm；聚集体的氟元素含量为39ppm。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.31。
实施例23
按照与实施例1基本相同的方法制备纳米硅基复合负极材料，区别在于采用的掺杂剂为三苯基膦，掺杂元素含量与实施例1相同。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm - 1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.1。
实施例24
按照与实施例1基本相同的方法制备纳米硅基复合负极材料，区别在于采用的掺杂剂为四苯基溴化磷，掺杂元素含量与实施例1相同。本实施例的I D/I G为2.05。
实施例25
按照与实施例1基本相同的方法制备纳米硅基复合负极材料，区别在于采用的掺杂剂为氮化锂，掺杂元素含量与实施例1相同。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.9。
实施例26
按照与实施例1基本相同的方法制备纳米硅基复合负极材料，区别在于采用的掺杂剂为硫脲掺杂元素含量与实施例1相同。本实施例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1.85。
对比例1
按照与实施例1基本相同的方法制备纳米硅基复合负极材料，区别在于未添加 氟化物直接混合，然后热处理。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉、碳材料，硅粉、碳材料的质量比为63.3：36.7，负极材料的中值粒径为13.5μm，比表面积为6.3m 2/g，碳层平均厚度为561nm；聚集体的氟元素含量为0ppm。该对比例中碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到的G带和在1280cm -1至1380cm -1观察到的D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为2.5。
性能测试
采用以下方法测试电化学循环性能：将实施例1～26及对比例1制备的负极材料、导电剂和粘结剂按质量百分比94：1：5将它们溶解在溶剂中混合，控制固含量在50％，涂覆于铜箔集流体上，真空烘干、制得负极极片；然后将传统成熟工艺制备的三元正极极片、1mol/L的LiPF 6/乙基纤维素+碳酸二甲酯+碳酸甲乙酯(v/v＝1:1:1)电解液、Celgard2400隔膜、外壳采用常规生产工艺装配18650圆柱单体电池。圆柱电池的充放电测试在武汉金诺电子有限公司LAND电池测试系统上，在常温条件，0.2C恒流充放电，充放电电压限制在2.75～4.2V，得到首次可逆容量、首圈充电容量和首圈放电容量。首次库伦效率＝首圈放电容量/首圈充电容量。
重复循环50周，利用千分尺测量锂离子电池此时极片的厚度为H1，循环50圈后膨胀率＝(H1-H0)/H0×100％。
重复100周循环，记录放电容量，作为锂离子电池的剩余容量；容量保持率＝剩余容量/初始容量*100％。
性能测试的结果如下：
表1.性能比对结果表
Figure PCTCN2022094963-appb-000001
Figure PCTCN2022094963-appb-000002
如表1所示，实施例1～26制备的负极材料，通过在聚集体中加入掺杂元素，能够获得石墨化程度更高的碳材料，从而提高负极材料的导电性，从而为硅膨胀提供了空间，降低了硅的体积膨胀效应。
实施例19加入含氟组成成分高于20000ppm，首次效率、膨胀率、循环寿命不如本申请实施例，性能劣化。
实施例22加入含氟组分低于50ppm，其碳材料石墨化效果不佳，使得制备的负极活性物质制造的电极板的首次效率、膨胀率、循环寿命不如本申请实施例，性能劣化。
对比例1中不加氟化物制备的负极材料，负极材料的首次库伦效率以及循环容量保持率下降。
申请人声明，本申请通过上述实施例来说明本申请的详细工艺设备和工艺流程，但本申请并不局限于上述详细工艺设备和工艺流程，即不意味着本申请必须依赖上述详细工艺设备和工艺流程才能实施。所属技术领域的技术人员应该明了，对本申请的任何改进，对本申请产品各原料的等效替换及辅助成分的添加、具体方式的选择等，均落在本申请的保护范围和公开范围之内。

Claims (18)

  1. 一种负极材料，其特征在于，包括聚集体，所述聚集体包括活性物质、碳材料及掺杂元素；所述碳材料在使用波长为532nm的测量光源通过拉曼光谱法获得的拉曼图中示出，在1530cm -1至1630cm -1观察到G带和在1280cm -1至1380cm -1观察到D带，并且D带的峰强度I D与G带的峰强度I G之间的比值I D/I G为1～2.5。
  2. 一种负极材料，其特征在于，包括聚集体，所述聚集体包括活性物质、碳材料及掺杂元素，所述掺杂元素能够诱导所述碳材料产生路易斯酸活性位点，至少部分所述活性物质通过所述路易斯酸活性位点与所述碳材料结合。
  3. 根据权利要求1或2所述的负极材料，其特征在于，包括如下特征(1)～(8)中的至少一个：
    (1)所述掺杂元素包括氟、氮及磷中的至少一种；
    (2)所述活性物质及碳材料中的至少一种含有所述掺杂元素；
    (3)所述掺杂元素分布于所述活性物质的表面和/或内部；
    (4)所述掺杂元素分布于所述碳材料的表面和/或内部；
    (5)所述掺杂元素在所述聚集体中的含量为50ppm～20000ppm；
    (6)所述碳材料之间形成有孔隙，至少部分所述活性物质填充于所述孔隙；
    (7)所述碳材料的孔容≥0.35cm 3/g；
    (8)所述活性物质分布于碳材料之间或表面。
  4. 根据权利要求1～3任一项所述的负极材料，其特征在于，包含以下特征(1)～(5)中的至少一种：
    (1)所述活性物质包括活性粒子；
    (2)所述活性物质包括Li、Na、K、Sn、Ge、Si、Fe、Mg、Ti、Zn、Al、P、Cu及SiO x中的至少一种，其中，0＜x≤2；
    (3)所述活性物质的中值粒径为1nm～300nm；
    (4)所述碳材料包括结晶碳、非晶碳、人造石墨、天然石墨、软碳、硬碳、无定形碳、碳纳米管、碳纤维及石墨烯中至少一种；
    (5)所述活性物质与所述碳材料的质量比为(90～10)：(10～90)。
  5. 根据权利要求3所述的负极材料，其特征在于，所述聚集体还包括金属氧化 物，所述金属氧化物包含以下特征(1)～(7)中的至少一种：
    (1)至少部分所述金属氧化物填充于所述碳材料之间的孔隙中；
    (2)所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种；
    (3)所述金属氧化物包括GeO 2、SnO 2、ZnO、TiO 2、Fe 3O 4、MgO、SiO 2和CuO中的任意一种；
    (4)所述活性物质与所述金属氧化物的质量比为(30～100)：(0.5～10)；
    (5)所述金属氧化物呈片状和/或长条状；
    (6)所述金属氧化物的长径比值大于2；
    (7)所述金属氧化物与金属氧化物之间的最短距离≥100nm。
  6. 根据权利要求3所述的负极材料，其特征在于，所述聚集体还包括导电增强剂，所述导电增强剂包含以下特征(1)至(7)中的至少一种：
    (1)至少部分所述导电增强剂填充于所述碳材料之间的孔隙中；
    (2)所述导电增强剂包括合金材料及导电碳中的至少一种；
    (3)所述导电增强剂包括合金材料及导电碳中的至少一种，所述导电碳包括碳纳米管、碳纤维和石墨纤维中的至少一种；
    (4)所述导电增强剂的电导率为10 0S/m～10 8S/m；
    (5)所述导电增强剂呈片状和/或长条状；
    (6)所述导电增强剂与所述活性物质的质量比为(0.01～15):(50～100)；
    (7)所述导电增强剂的长径比为2～5000。
  7. 根据权利要求1～6任一项所述的负极材料，其特征在于，所述负极材料还包括包覆所述聚集体的至少部分表面的碳层，所述碳层包括以下特征(1)至(3)中的至少一个：
    (1)所述碳层的材料包括无定形碳；
    (2)所述碳层的厚度为10nm～5000nm；
    (3)所述聚集体与所述碳层的质量比为(90～10)：(10～90)。
  8. 根据权利要求1～6任一项所述的负极材料，其特征在于，所述负极材料还包括形成于所述活性物质至少部分表面的氧化层，所述氧化层包括以下特征(1)至(2) 中的至少一个：
    (1)所述氧化层的厚度为1nm～100nm；
    (2)所述氧化层具有孔隙。
  9. 根据权利要求1～8任一项所述的负极材料，其特征在于，所述负极材料包括以下特征(1)至(5)中的至少一个：
    (1)所述负极材料的中值粒径为0.5μm～30μm；
    (2)所述负极材料的比表面积为≤10m 2/g；
    (3)所述聚集体的孔隙率≤10％；
    (4)所述聚集体的耐压硬度≥100MPa；
    (5)所述聚集体密度满足以下关系：(ρ1-ρ2)/ρ2≤5％，其中ρ1为聚集体的测试密度，ρ2为聚集体的平均密度，所述ρ2为聚集体中各组分在聚集体中的质量百分含量*各组分的理论密度的值的总和。
  10. 一种负极材料的制备方法，其特征在于，所述方法包括以下步骤：
    将活性物质、掺杂剂、第一碳源和溶剂混合后制备前驱体；及
    对所述前驱体在800℃～980℃进行一次热处理，得到聚集体。
  11. 根据权利要求10所述的制备方法，其特征在于，所述方法包括以下特征(1)至(10)中的至少一个：
    (1)所述活性物质包括Li、Na、K、Sn、Ge、Si、Fe、Mg、Ti、Zn、Al、P、Cu及SiO x中的至少一种，其中，0＜x≤2；
    (2)所述掺杂剂包括氟源、磷源及氮源中的至少一种；
    (3)所述掺杂剂包括氟源、磷源及氮源中的至少一种，所述氟源包括氟化物，所述氟化物包括氟化氢、氟化锂、氟化铵、氟化钾、氟化铝、氟化镁、氟化钠、氟化钙、四丁基氟化铵、三乙基甲氧甲基氟化铵、氟硼酸铵及四丁基氟硼酸铵中的至少一种；
    (4)所述掺杂剂包括氟源、磷源及氮源中的至少一种，所述磷源包括三苯基膦、四苯基溴化磷、1-丁基-3-甲基咪唑六氟磷酸钠、磷化氢、磷酸钠、亚磷酸钠、单质磷、磷酸氢钠、磷酸二氢钠、亚磷酸氢钠及磷酸中的至少一种；
    (5)所述掺杂剂包括氟源、磷源及氮源中的至少一种，所述氮源包括氨气、氯 化铵、碳酸铵、碳酸氢铵、尿素、硫脲、氮化锂、三聚氰胺及水合肼中的至少一种；
    (6)所述第一碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种；
    (7)所述活性物质、掺杂剂和第一碳源的质量比为(30～120)：(0.9～20)：(10～50)；
    (8)所述溶剂包括有机溶剂；
    (9)所述溶剂包括有机溶剂，所述有机溶剂包括乙醇、乙二醇、丙醇、丁醇及正戊醇中的至少一种；
    (10)所述将活性物质、掺杂剂、第一碳源和溶剂混合的步骤具体为：将所述活性物质分散在溶剂中再加入掺杂剂和第一碳源。
  12. 根据权利要求10所述的制备方法，其特征在于，所述将活性物质、掺杂剂、第一碳源和溶剂混合的步骤中还加入了添加剂，所述添加剂包括以下特征(1)至(4)中的至少一个：
    (1)所述添加剂包括表面活性剂及偶联剂中的至少一种；
    (2)所述添加剂包括表面活性剂，所述表面活性剂包括正十八酸、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、棕榈酸、十四烷酸、十一烷酸、十六烷基三甲基溴化胺及聚乙烯吡咯烷酮中的至少一种；
    (3)所述添加剂包括偶联剂，所述偶联剂包括硅烷偶联剂，所述硅烷偶联剂包括γ-氨丙基三乙氧基硅烷、γ-缩水甘油醚氧丙基三甲氧基硅烷及γ-甲基丙烯酰氧基丙基三甲氧基硅烷中的至少一种；
    (4)所述添加剂与活性物质的质量比为(0.01～5)：(50～100)。
  13. 根据权利要求10所述的制备方法，其特征在于，所述将活性物质、掺杂剂、第一碳源和溶剂混合的步骤中还加入了金属氧化物及导电增强剂中的至少一种，所述方法包括以下特征(1)至(9)中的至少一个：
    (1)所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种；
    (2)所述金属氧化物呈片状和/或长条状；
    (3)所述金属氧化物的长径比大于2；
    (4)所述金属氧化物与活性物质的质量比为(0.5～10)：(30～100)；
    (5)所述导电增强剂与活性物质的质量比为(0.01～15):(50～100)；
    (6)所述导电增强剂的电导率为10 0S/m～10 8S/m；
    (7)所述导电增强剂呈片状和/或长条状；
    (8)所述导电增强剂的长径比为2～5000；
    (9)所述导电增强剂包括合金材料及导电碳中的至少一种。
  14. 根据权利要求10所述的制备方法，其特征在于，所述制备所述前驱体的步骤还包括将活性物质、掺杂剂、第一碳源、溶剂混合后进行分散处理和干燥处理中的至少一种，所述方法包括以下特征(1)至(3)中的至少一个：
    (1)所述分散处理包括机械搅拌、超声分散及研磨分散中的至少一种；
    (2)所述干燥处理的温度为30℃～400℃；
    (3)所述干燥处理的时间为1h～15h。
  15. 根据权利要求10所述的制备方法，其特征在于，所述前驱体进行一次热处理之前，还包括对所述前驱体进行密实化处理，使得所述聚集体的孔隙率≤10％且耐压硬度≥100MPa，所述方法包括以下特征(1)至(5)中的至少一个：
    (1)所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种；
    (2)所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合；
    (3)所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合，所述机械融合所用的融合机的转速为500r/min～3000r/min；
    (4)所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合，所述机械融合所用的融合机刀具间隙宽度为0.01cm～0.5cm；
    (5)所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种，所述融合处理为机械融合，所述机械融合时间至少为0.5h。
  16. 根据权利要求10所述的制备方法，其特征在于，所述方法包括以下特征(1) 至(3)中的至少一个：
    (1)所述一次热处理的时间为1h～5h；
    (2)所述一次热处理在第一保护性气氛中进行；
    (3)所述一次热处理在第一保护性气氛中进行，所述第一保护性气氛的气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
  17. 根据权利要求10所述的制备方法，其特征在于，所述方法还包括对所述聚集体进行碳包覆处理，所述方法包括以下特征(1)至(9)中的至少一个：
    (1)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理；
    (2)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述第二碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种；
    (3)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述聚集体与所述第二碳源的质量比为(20～100)：(10～80)；
    (4)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理的温度为800℃～900℃；
    (5)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理的时间为1h～5h；
    (6)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理在第二保护性气氛中进行；
    (7)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理在第二保护性气氛中进行，所述第二保护性气氛的气体包括氮气、氦气、氖气、氩气及氪气中的至少一种；
    (8)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理后，还进行粉碎、筛分和除磁中的至少一种；
    (9)所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合进行二次热处理，所述二次热处理后，还进行粉碎、筛分和除磁中的至少一种，所述筛分的目数为 ≥500目。
  18. 一种锂离子电池，其特征在于，所述锂离子电池包含如权利要求1～9任一项所述的负极材料或根据权利要求10～17任一项所述的制备方法制得的负极材料。
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