WO2022041799A1 - 硅基复合材料、负极和锂离子电池及制备方法 - Google Patents

硅基复合材料、负极和锂离子电池及制备方法 Download PDF

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WO2022041799A1
WO2022041799A1 PCT/CN2021/088785 CN2021088785W WO2022041799A1 WO 2022041799 A1 WO2022041799 A1 WO 2022041799A1 CN 2021088785 W CN2021088785 W CN 2021088785W WO 2022041799 A1 WO2022041799 A1 WO 2022041799A1
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silicon
graphite
composite material
based composite
nano
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French (fr)
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何鹏
肖称茂
任建国
贺雪琴
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BTR New Material Group Co Ltd
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BTR New Material Group Co Ltd
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Priority to JP2021574340A priority Critical patent/JP7455870B2/ja
Priority to EP21819318.3A priority patent/EP3985759B1/en
Priority to US17/623,429 priority patent/US12288874B2/en
Priority to KR1020217041026A priority patent/KR20220029565A/ko
Publication of WO2022041799A1 publication Critical patent/WO2022041799A1/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
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    • C01B32/21—After-treatment
    • C01B32/22—Intercalation
    • C—CHEMISTRY; METALLURGY
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/0682—Silicides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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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    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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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    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to the field of negative electrode materials for lithium ion batteries, and relates to a silicon-based composite material, a negative electrode, a lithium-ion battery and a preparation method, and in particular, to a porous nano-silicon-based composite material, a negative electrode, a lithium ion battery and a preparation method.
  • Lithium-ion batteries have become the ideal portable batteries due to their high operating voltage, light weight, small self-discharge, long cycle life, no memory effect, no environmental pollution, and good safety performance.
  • Si has a high lithium intercalation capacity, up to 4200mAh ⁇ g -1 , but the silicon anode has a serious volume expansion effect, resulting in poor cycle performance and rapid decay of the material, which cannot meet the requirements of long cycle and low expansion, thus hindering Si It has been put into practical use as a negative electrode for lithium ion batteries.
  • the present disclosure provides a silicon-based composite material, the silicon-based composite material includes nano-active particles and graphite, and the nano-active particles include porous nano-silicon;
  • the graphite has a channel structure, and the nano-active particles are embedded in the channel structure of the graphite, and/or the graphite has a layered structure, and the nano-active particles are embedded in the layered structure of the graphite particle.
  • the mass ratio of the nano-active particles and the graphite is (0.5-80):(10-50).
  • the median particle size of the silicon-based composite material is 1 ⁇ m ⁇ 40 ⁇ m.
  • the specific surface area of the silicon-based composite material ranges from 1 m 2 /g to 20 m 2 /g.
  • a carbon coating layer is formed on the surface of the silicon-based composite material.
  • the median particle size of the porous nano-silicon is 1 nm to 500 nm.
  • the specific surface area of the porous nano-silicon ranges from 1 m 2 /g to 500 m 2 /g.
  • the porous nano-silicon has a porosity of 20% to 90%.
  • the pore size of the porous nano-silicon is 1 nm ⁇ 0.1 ⁇ m.
  • the nano-active particles further include a magnesium silicide layer formed on the surface of the porous nano-silicon.
  • the thickness of the magnesium silicide layer is 1 nm ⁇ 100 nm.
  • the mass fraction of the magnesium silicide layer is 0.5% to 10% based on the mass of the nano-active particles as 100%.
  • the graphite includes at least one of porous graphite and flake graphite.
  • the median particle size of the graphite is 1 ⁇ m ⁇ 10 ⁇ m.
  • the ratio of the median particle size of the graphite to the porous nano-silicon is (10-40):1.
  • the porous graphite has a porosity of 10% to 50%.
  • the pore size of the porous graphite is 10%-50% larger than the median particle size of the porous nano-silicon.
  • the interlayer spacing between the layers of the flake graphite is 10 nm to 500 nm.
  • the ratio of length:width:thickness of the flake graphite is (2-20):(0.4-3):(0.1-0.2).
  • the present disclosure provides a preparation method of a silicon-based composite material, comprising the following steps:
  • the nano-active particles and graphite are mixed in an organic solvent so that the nano-active particles are embedded in the interlayers and/or pores of the graphite to obtain a slurry, and after drying, the silicon-based composite material is obtained, and the nano-active particles are obtained.
  • the particles include porous nanosilicon.
  • the preparation method of the porous nano-silicon includes: etching a silicon alloy to obtain the porous nano-silicon.
  • the silicon alloy includes at least one of aluminum-silicon alloy, iron-silicon alloy, and silicon-zinc alloy.
  • the silicon alloy is submicron-sized particles.
  • the etchant used in the etching includes, but is not limited to, at least one of hydrochloric acid, hydrofluoric acid, sulfuric acid, and phosphoric acid.
  • the etching time ranges from 0 to 7 hours and does not include 0.
  • the mass ratio of the porous nano-silicon to the graphite is (0.5-80):(10-50).
  • the organic solvent includes but is not limited to at least one of aromatic hydrocarbons, chlorinated hydrocarbons, alcohol ethers, amine compounds, ketones, and alcohols.
  • aromatic hydrocarbons chlorinated hydrocarbons
  • alcohol ethers examples of alcohols can be R-OH, and R is C1 ⁇ At least one of C11 alkyl groups.
  • the organic solvent includes methanol, ethanol, propanol, isopropanol, butanol, amyl alcohol, acetone, toluene, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether, and triethanolamine at least one of them.
  • the preparation method of the slurry further includes: mixing the nano-active particles, a dispersant and graphite in an organic solvent to obtain the slurry.
  • the dispersing agent includes, but is not limited to, at least one of a surfactant containing a carboxyl group, a sulfonic acid group, and an amino group.
  • the dispersing agent includes, but is not limited to, n-octadecanoic acid, epoxy resin, lauric acid, polyacrylic acid, sodium dodecylbenzenesulfonate, n-eicosic acid, polyvinyl chloride and polyvinylpyrrolidone. at least one of.
  • the drying method includes at least one of vacuum drying, spray drying and rotary evaporation.
  • the preparation process of the silicon-based composite material further includes carbon coating on the product obtained after drying.
  • the carbon coating method includes: mixing the dried product with a carbon source, and sintering to obtain the silicon-based composite material.
  • the carbon source includes at least one of sugars, resins, organic acids, polymeric polyols, enols, and readily graphitizable carbon material mixtures.
  • the carbon source includes at least one of epoxy resin, citric acid, sucrose, glucose, pitch, phenolic resin, fructose, polyethylene glycol, polyvinyl alcohol, and polyvinyl chloride.
  • the temperature of the sintering is 500° C. ⁇ 1500° C., and the time is 1 h ⁇ 12 h.
  • the sintering temperature is 800° C. ⁇ 1200° C.
  • the time is 3 h ⁇ 10 h.
  • the method further includes: pulverizing, sieving, and demagnetizing the sintered product to obtain the silicon-based composite material.
  • the preparation process of the porous nano-silicon further includes: forming a magnesium silicide layer on the surface of the porous nano-silicon.
  • the preparation method for forming a magnesium silicide layer includes: subjecting the porous nano-silicon to surface coating treatment to obtain porous nano-silicon with a magnesium silicide layer formed on the surface.
  • the method for surface coating treatment includes at least one of magnetron sputtering and vacuum coating.
  • the preparation method of the silicon-based composite material includes the following steps:
  • porous nano-silicon with the magnesium silicide layer formed on the surface, an organic solvent, a dispersant and graphite are mixed to obtain a slurry, and a precursor is obtained after drying, wherein the mass ratio of the porous nano-silicon to the graphite is (0.5 ⁇ 80):(10 ⁇ 50); and
  • the precursor is mixed with a carbon source, and the silicon-based composite material is obtained after sintering.
  • the present disclosure provides a negative electrode including the silicon-based composite material.
  • the present disclosure provides a lithium-ion battery including the silicon-based composite material.
  • FIG. 1 is a schematic flowchart of a preparation process of a silicon-based composite material in an embodiment of the present disclosure.
  • Example 2 is a scanning electron microscope image of the silicon-based composite material in Example 3 of the present disclosure
  • Example 3 is an X-ray diffraction pattern of the silicon-based composite material in Example 3 of the present disclosure, wherein G represents graphite and Si represents silicon;
  • Example 4 is the first charge-discharge curve of the silicon-based composite material in Example 3 of the present disclosure
  • Example 5 is a cycle performance curve of the silicon-based composite material in Example 3 of the present disclosure.
  • Example 6 is a scanning electron microscope image of the silicon-based composite material in Example 1 of the present disclosure.
  • Example 7 is an X-ray diffraction pattern of the silicon-based composite material in Example 1 of the present disclosure, wherein G represents graphite and Si represents silicon;
  • Example 8 is the first charge-discharge curve of the silicon-based composite material in Example 1 of the present disclosure.
  • Example 9 is a cycle performance curve of the silicon-based composite material in Example 1 of the present disclosure.
  • FIG. 10 is a schematic diagram of a cross-sectional structure of a silicon-based composite material provided by some embodiments of the present disclosure.
  • FIG. 11 is a schematic diagram of a cross-sectional structure of a silicon-based composite material provided by some embodiments of the present disclosure.
  • FIG. 12 is a schematic cross-sectional structure diagram of a silicon-based composite material provided by some embodiments of the present disclosure.
  • FIG. 13 is a schematic cross-sectional structural diagram of a silicon-based composite material provided by some embodiments of the present disclosure.
  • FIG. 14 is a schematic cross-sectional structure diagram of a silicon-based composite material provided by some embodiments of the present disclosure.
  • FIG. 15 is a schematic cross-sectional structure diagram of porous nano-silicon according to some embodiments of the present disclosure, wherein (a) is the porous nano-silicon not coated with a magnesium silicide layer, and (b) is the porous nano-silicon coated with a magnesium silicide layer;
  • 16 is a schematic diagram of a cathode structure of some embodiments of the present disclosure.
  • 17 is a schematic diagram of a battery of some embodiments of the present disclosure.
  • Reference numerals 100-silicon-based composite material; 120-porous nano-silicon; 122-magnesium silicide layer; 140-porous graphite; 142-porous structure; 160-flaky graphite; 162-layered structure; 180-carbon coating layer; 200-battery; 220-positive electrode; 240-negative electrode; 242-negative electrode current collector; 244-negative electrode active material layer; 260-electrolyte solution; 280-diaphragm; 290-case.
  • One embodiment provides a silicon-based composite material to solve the problems of high expansion ratio of silicon-based negative electrode materials and low expansion ratio of pole pieces in the prior art, and to provide a silicon-based composite material with low expansion ratio and excellent cycle performance, Negative electrodes and lithium-ion batteries and methods for their preparation.
  • Another embodiment provides a preparation method of the above-mentioned silicon-based composite material.
  • Yet another embodiment provides a lithium-ion battery including the above-described silicon-based composite material.
  • the silicon-based composite material 100 includes nano-active particles and graphite; the graphite has a pore structure 142 , and the nano-active particles are embedded in the pore structure 142 of the graphite , and/or, the graphite has a layered structure 162 , and nano-active particles are embedded in the layered structure 162 of the graphite; the nano-active particles include porous nano-silicon 120 .
  • the nano-active particles comprising porous nano-silicon 120 form an embedded structure with graphite, and the porous nano-silicon 120 is embedded in the interlayer of graphite (ie, layered structure 162) and/or in the pore structure 142 of graphite. .
  • the porous nano-silicon 120 provides an expansion space for the volume expansion of silicon, and thus has a lower expansion rate.
  • the porous nano-silicon 120 is embedded in the interlayer and/or pore structure 142 of graphite, and the space between the layers and/or the pore provides sufficient expansion space for the expansion of the porous nano-silicon 120. It is disclosed that the expansion of the silicon-based composite material 100 is further controlled to obtain an ultra-low expansion silicon-based composite material 100, and the cycle performance is improved.
  • the mass ratio of nano-active particles and graphite is (0.5-80):(10-50); including but not limited to 0.5:10, 0.5:20, 0.5:35, 0.5:45, 0.5:50, 1:45, 5:40, 10:35, 20:30, 40:25, 60:20, 70:15, 80:10, 80:20, 80:35, 80: 45 or 80:50 etc.
  • the mass ratio in the above range not only makes the nano-active particles evenly distributed in the layered structure 162 and/or the pore structure 142 of the graphite, but also improves the overall performance of the negative electrode material and the battery 200 . However, if the proportion of nano-active particles is too high, it is difficult to distribute the nano-active particles evenly, and there will be nano-active particles exposed outside the graphite. The overall performance of the battery 200 is reduced.
  • the median particle size of the silicon-based composite material 100 is 1 ⁇ m ⁇ 40 ⁇ m or 5 ⁇ m ⁇ 20 ⁇ m; including but not limited to 1 ⁇ m, 2 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m or 40 ⁇ m, etc.
  • the above median particle size range will not only reduce the expansion probability of silicon volume, but also generate low industrialization cost, will not consume more irreversible lithium in the process of SEI film formation, and improve the first Coulomb efficiency.
  • the median particle size of the silicon-based composite material 100 is too large, the number and size of large particles in the particle size distribution of the composite material in the product will increase, resulting in a high volume expansion of silicon; At the same time, the specific surface area of the product is larger, and more irreversible lithium is consumed during the formation of the SEI film, resulting in a decrease in the first efficiency.
  • the specific surface area of the silicon-based composite material 100 is 1 m 2 /g ⁇ 20 m 2 /g or 1 m 2 /g ⁇ 10 m 2 /g; including but not limited to 1 m 2 /g, 2 m 2 /g, 5 m 2 /g, 8m 2 /g, 10m 2 /g, 12m 2 /g, 15m 2 /g, 18m 2 /g or 20m 2 /g, etc.
  • a carbon coating layer 180 is formed on the surface of the silicon-based composite material 100 . By carbon coating the silicon-based composite material, the electrical conductivity of the material can be further improved and the electronic conduction resistance between particles can be reduced.
  • the median particle size of the porous nano-silicon 120 is 1 nm ⁇ 500 nm, 5 nm ⁇ 250 nm or 50 nm ⁇ 200 nm; including but not limited to 1 nm, 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350nm, 400nm, 450nm or 500nm etc.
  • the median particle size in the above range not only improves the coating and granulation efficiency, but also the particles are not easily oxidized.
  • the specific surface area of the porous nano-silicon 120 is 1 m 2 /g to 500 m 2 /g, 10 m 2 /g to 400 m 2 /g, or 20 m 2 /g to 400 m 2 /g.
  • the increased specific surface area provides more contact points between lithium ions and silicon, which is more conducive to the smooth insertion and extraction of lithium ions, and the rate performance of the material is improved.
  • the porous nano-silicon 120 has a porosity of 20%-90%, 20%-80%, 40%-80%, including but not limited to 20%, 30%, 40%, 50%, 60% , 70%, 80% or 90% etc.
  • porosity not only does the irreversible capacity not increase.
  • the first reversible capacity is improved, and the volumetric energy density is also increased, thereby improving the first Coulomb efficiency and cycle efficiency of the electrode.
  • the porosity is too large, the specific surface area of the porous nano-silicon 120 will be larger, more lithium will be consumed during the formation of the SEI film, and the irreversible capacity will increase, thereby reducing the first Coulomb efficiency and reducing the tap density, which is not conducive to improvement.
  • the volume energy density in addition, if the porosity is too small, there is not enough space to buffer the expansion of the nano-silicon, and the particles will pulverize, resulting in poor circulation.
  • the pore size of the porous nano-silicon 120 is 1 nm ⁇ 0.1 ⁇ m, including but not limited to 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 0.1 ⁇ m, etc.
  • the nano-active particles further include a magnesium silicide layer 122 formed on the surface of the porous nano-silicon 120 .
  • the magnesium silicide layer 122 exists on the outer surface of the porous nano-silicon 120 particles. In at least one embodiment, the magnesium silicide layer 122 exists not only on the outer surface of the porous nano-silicon 120, but also on the porous nano-silicon 120. the inner surface of the hole.
  • the surface of the porous nano-silicon 120 is formed with a magnesium silicide layer 122, and the porous nano-silicon 120 covered with the magnesium silicide layer 122 is embedded in the interlayers and/or pores of graphite, which can solve the internal problems existing in the related art.
  • the outer cladding layer of the embedded structure is not dense, and the electrolyte 260 will infiltrate into contact with silicon during the reaction process, resulting in the problem of unstable interface.
  • the electrolyte 260 when the electrolyte 260 is in direct contact with the porous nano-silicon 120 (without being coated by the magnesium silicide layer 122 ), the SEI film will be unstable, thereby reducing the cycle times of the battery 200 and reducing the Coulombic efficiency.
  • the Coulomb efficiency during the cycle is improved, and the cycle performance is improved.
  • the magnesium silicide layer 122 on the surface of the porous nano-silicon 120 improves the contact effect between the porous nano-silicon 120 and the electrolyte 260, reduces the generation of Li 2 CO 3 during the charge and discharge process, ensures that the generated SEI film is more stable, and reduces the Irreversible lithium ion consumption, thereby improving cycle Coulomb efficiency and improving cycle performance.
  • the porous nano-silicon 120 itself has pores, and the existing pores can be used to relieve its own expansion, thereby effectively reducing the volume expansion rate of the silicon-based material.
  • the surface-coated magnesium silicide and silicon have different lithium intercalation potentials, and can act as buffer layers for each other, further reducing the volume expansion effect of silicon, thereby obtaining an ultra-low expansion effect.
  • the thickness of the magnesium silicide layer 122 is 1 nm ⁇ 100 nm, including but not limited to 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm, and the like.
  • the magnesium silicide layer in the above thickness range can effectively combine the magnesium silicide with the porous nano-silicon 120 and improve its protection performance. If the magnesium silicide layer 122 is too thick, the bonding between the magnesium silicide and the porous nano-silicon 120 will be poor, and the silicidation If the magnesium layer 122 is too thin, its protective effect is weak.
  • the mass fraction of the magnesium silicide layer 122 is 0.5% to 10% based on 100% of the mass of the nano-active particles, including but not limited to 0.5%, 1%, 3%, 5%, 7%, 9% or 10% etc.
  • the graphite includes at least one of porous graphite 140 or flake graphite 160 .
  • porous graphite 140 means that the graphite has certain pores inside.
  • porous graphite 140 is obtained by pore-forming natural graphite or artificial graphite.
  • the above-mentioned flake graphite 160 refers to graphite having a lamellar structure, and for example, the ratio of the thickness to the length in the major axis direction is greater than 2.5.
  • the median particle size of the graphite is 1 ⁇ m to 10 ⁇ m, 3 ⁇ m to 9 ⁇ m, or 4 ⁇ m to 7 ⁇ m, including but not limited to 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m or 9 ⁇ m, etc.
  • the graphite with the above particle size is used as the graphite, and the porous nano-silicon 120 is embedded in the pore structure 142 of the graphite.
  • the carbon coating layer 180 formed on the surface is It is more dense, which is beneficial to avoid the contact between the electrolyte 260 and the silicon, and improve the interface stability.
  • the ratio of the median particle size of graphite to porous nano-silicon 120 is (10-40):1, including but not limited to 10:1, 15:1, 20:1, 25:1, 30:1 1, 35:1 or 40:1 etc.
  • the porous graphite 140 has a porosity of 10% to 50%, 15% to 40%, or 25% to 35%; including but not limited to 15%, 20%, 25%, 30%, 35% , 40% or 45%, etc.
  • the effective filling amount of nano-silicon can be satisfied, thereby achieving the first reversible capacity, the first Coulomb efficiency, the improvement of the cycle capacity retention rate, and the reduction of the expansion ratio.
  • the pore size of the porous graphite 140 is 10%-50%, 15%-40%, or 25%-35% larger than the median particle size of the porous nano-silicon 120; including but not limited to 15%, 20% , 25%, 30%, 35%, 40% or 45% etc.
  • the pore size of the porous graphite 140 is an average pore size.
  • porous graphite 140 is used for graphite, and the pore size of porous graphite 140 is controlled to be 10%-50% larger than that of porous nano-silicon 120, which is beneficial for porous nano-silicon 120 to enter and be stored in the pores of porous graphite 140. , and the expansion of silicon is limited to obtain an ultra-low expansion silicon-based composite material 100 , thereby improving the cycle performance of the lithium ion battery 200 .
  • the interlayer spacing between the layers of the flake graphite 160 is 10 nm ⁇ 500 nm, including but not limited to 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500nm, etc.
  • the ratio of length:width:thickness of the flake graphite 160 is (2-20):(0.4-3):(0.1-0.2), including but not limited to 20:3:0.2, 15:2 :0.1, 10:1:0.1, 5:2:0.1, 5:0.4:0.1 or 2:0.4:0.15 etc.
  • the above-mentioned preparation method of the silicon-based composite material 100 includes steps S100 to S300, and a schematic flowchart thereof is shown in FIG. 1 .
  • Step S100 preparing nano-active particles.
  • preparing the nano-active particles includes step S110 and step S120.
  • step S110 the silicon alloy is etched to obtain porous nano-silicon 120 .
  • silicon alloys include, but are not limited to, at least one of aluminum-silicon alloys, iron-silicon alloys, and silicon-zinc alloys.
  • silicon alloys include, but are not limited to, at least one of aluminum-silicon alloys, iron-silicon alloys, silicon-zinc alloys, magnesium-silicon alloys, aluminum-magnesium-silicon alloys, silicon-manganese alloys, copper-nickel-silicon alloys, or silicon-chromium alloys kind.
  • the silicon alloys are submicron-sized particles.
  • the etchant used for etching includes at least one of hydrochloric acid, hydrofluoric acid, sulfuric acid, and phosphoric acid.
  • the etchant used for etching includes, but is not limited to, at least one of hydrochloric acid, hydrofluoric acid, sulfuric acid, phosphoric acid, acetic acid, nitric acid, sulfurous acid, perchloric acid, hydrosulfuric acid, hypochlorous acid, or benzoic acid.
  • the etching time is 0-7h and not 0, including but not limited to 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h or 7h, etc. In some embodiments, the etching time is 0.5h-5h.
  • porous nano-silicon 120 can also be purchased commercially.
  • step S120 the porous nano-silicon 120 is subjected to surface plating treatment to obtain the porous nano-silicon 120 with the magnesium silicide layer 122 formed on the surface.
  • the method of surface coating treatment includes at least one of magnetron sputtering or vacuum coating.
  • magnetron sputtering and vacuum coating are performed in magnetron sputtering equipment and vacuum coating equipment, respectively.
  • step S120 may be omitted, and in this case, the magnesium silicide layer 122 is not formed on the surface of the porous nano-silicon 120 .
  • Step S200 preparing a silicon-based composite material
  • step S200 the porous nano-silicon 120 with the magnesium silicide layer 122 formed on the surface, an organic solvent, a dispersant and graphite are mixed to obtain a slurry, and the silicon-based composite material 100 is obtained after drying.
  • the organic solvent includes, but is not limited to, at least one of aromatic hydrocarbons, chlorinated hydrocarbons, alcohol ethers, amines, ketones, or alcohols.
  • An example of the alcohol may be R—OH, where R is at least one of C1-C11 alkyl groups.
  • the aromatic hydrocarbon includes, but is not limited to, at least one of toluene, xylene, ethylbenzene, styrene, butyltoluene, vinyltoluene.
  • chlorinated hydrocarbons include, but are not limited to, perchloroethylene, dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, trichloropropane, dichloroethane, chlorobenzene, dichloromethane at least one of benzene.
  • alcohol ethers include, but are not limited to, ethylene glycol ether, diethylene glycol monomethyl ether, propylene glycol methyl ether, dipropylene glycol dimethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether. at least one.
  • the amine compound includes, but is not limited to, at least one of triethanolamine, diethanolamine, and butylamine.
  • alcohols include, but are not limited to, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isoamyl alcohol, hexanol, isohexanol, heptanol, octanol, nonanol , at least one of heptanol.
  • the ketone includes, but is not limited to, at least one of acetone, methyl butanone, methyl isobutyl ketone, cyclohexanone, toluene cyclohexanone.
  • the organic solvent includes methanol, ethanol, propanol, isopropanol, butanol, amyl alcohol, acetone, toluene, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether, and triethanolamine at least one of.
  • the above embodiment provides a preparation method of porous nano-silicon 120-based composite material.
  • the pores and/or the interlayers of the graphite obtain the silicon-based composite material 100 .
  • a person skilled in the art may add a dispersant to the slurry.
  • the dispersant acts on the surface of the porous nano-silicon 120 particles to strengthen the dispersion effect, which can obviously promote the porous nano-silicon 120 to enter the pore structure 142 of the graphite to form an embedded structure, so that the porous nano-silicon 120 is combined with graphite. , it is more uniform and compact, thereby effectively reducing the expansion rate of the silicon-based composite material 100 .
  • the dispersing agent includes, but is not limited to, at least one of a surfactant containing a carboxyl group, a sulfonic acid group, and an amino group.
  • surfactants containing carboxyl groups include, but are not limited to, n-octadecic acid, n-eicosic acid, lauric acid, polyacrylic acid, stearic acid, oleic acid, linoleic acid, palmitic acid, sodium laurate / At least one of potassium, sodium/potassium myristate, sodium/potassium palmitate, and sodium/potassium stearate.
  • surfactants containing amino groups include, but are not limited to, polyvinylpyrrolidone, sodium glutamate, sodium glycinate, sodium/ammonium lauryl sulfate, sodium lauryl sulfate At least one of ammonium, cocoyl monoethanolamide, and cocoyl diethanolamide.
  • surfactants containing sulfonic acid groups include, but are not limited to, sodium dodecylbenzenesulfonate, sodium alkylbenzenesulfonate, ⁇ -olefin sulfonate, ⁇ -sulfomonocarboxylic acid, At least one of petroleum sulfonates.
  • the dispersing agent includes at least one of n-octadecanoic acid, epoxy resin, lauric acid, polyacrylic acid, sodium dodecylbenzenesulfonate, n-eicosic acid, polyvinyl chloride, and polyvinylpyrrolidone .
  • the functional groups such as carboxyl groups and amino groups contained on the surface can react with the Si-O groups on the surface of the porous nano-silicon 120, thereby promoting the porous nano-silicon 120 to enter the pores of the graphite, forming an embedded structure, thereby reducing the expansion rate of the silicon-based composite material 100 .
  • the method of drying includes, but is not limited to, at least one of vacuum drying, spray drying, or rotary evaporation.
  • the mass ratio of porous nano-silicon 120 to graphite is (0.5-80):(10-50); including but not limited to 1:45, 5:40, 10:35, 20:30, 40: 25, 60:20, 70:15 or 80:50 etc.
  • the step of carbon coating includes: mixing the obtained product after drying with a carbon source, and sintering to obtain the silicon-based composite material 100 having the carbon coating layer 180 formed thereon.
  • the carbon source includes at least one of sugars, resins, organic acids, polymeric polyols, enols, or a mixture of readily graphitizable carbon materials.
  • the carbohydrate includes, but is not limited to, at least one of sucrose, glucose, fructose, or lactose;
  • the resin includes, but is not limited to, at least one of epoxy resin, phenolic resin, polyvinyl chloride or polyester resin;
  • the organic acid includes, but is not limited to, at least one of carboxyl, sulfonic acid, sulfinic acid, or sulfuric acid;
  • the carboxylic acid includes, but is not limited to, at least one of formic acid, acetic acid, propionic acid, butyric acid, or citric acid;
  • polymeric polyols, enols include, but are not limited to, at least one of polyethylene glycol or polyvinyl alcohol;
  • the easily graphitizable carbon material mixture includes, but is not limited to, at least one of pitch, petroleum coke, or needle coke.
  • the carbon source includes at least one of epoxy resin, citric acid, sucrose, glucose, pitch, phenolic resin, fructose, polyethylene glycol, polyvinyl alcohol, and polyvinyl chloride.
  • the sintering temperature ranges from 500°C to 1500°C, including but not limited to 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C or 1400°C, etc.
  • the sintering time can be 1h to 12h, including but not limited to 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or 11h and the like.
  • the sintering temperature ranges from 800°C to 1200°C, including but not limited to, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C or 1150°C, etc.
  • the sintering time can be 3h to 10h, including but not limited to 4h, 5h, 6h, 7h, 8h or 9h.
  • the method further includes: pulverizing, sieving, and demagnetizing the sintered product to obtain the silicon-based composite material 100 .
  • step S300 is omitted, that is, the carbon coating layer 180 is not formed on the surface of the silicon-based composite material 100 .
  • the silicon-based composite material 100 may be used as an anode active material, such as an anode active material in a lithium ion battery 200 .
  • An embodiment provides a negative electrode material, and the negative electrode material includes the above-mentioned silicon-based composite material 100 .
  • the negative electrode material further includes a binder.
  • the negative electrode material further includes a conductive agent.
  • the negative electrode material includes the above-mentioned silicon-oxygen composite material, a binder, and a conductive agent.
  • the negative electrode material further comprises graphite.
  • the negative electrode material includes the above-mentioned silicon-oxygen composite material, a binder, a conductive agent, and graphite.
  • An embodiment provides a method of preparing a negative electrode material, comprising mixing the above-mentioned components.
  • An embodiment provides a method for preparing a negative electrode material, including: mixing the silicon-based composite material 100 with a conductive agent and a binder.
  • An embodiment provides a method for preparing a negative electrode material, including: mixing the silicon-based composite material 100, a conductive agent, a binder, and graphite.
  • An embodiment provides a negative electrode 240 including the silicon-based composite material 100 .
  • the negative electrode includes: a negative electrode current collector 242 and a negative polarity material layer 244 on the negative electrode current collector 242 , wherein the negative polarity material layer 244 includes the above-mentioned negative electrode material.
  • An embodiment provides a method for preparing the negative electrode 240 , including: coating a slurry including a negative electrode material on the negative electrode current collector 242 .
  • a negative electrode comprising: a negative electrode current collector 242 and a negative electrode active material layer 244 on the negative electrode current collector 242, wherein the negative electrode active material layer 244 comprises the silicon-based composite material 100 described above.
  • the anode active material layer 244 further includes a conductive agent and a binder.
  • the anode active material layer 244 further includes graphite.
  • the mass ratio of the silicon-based composite material 100, the conductive agent and the binder is (93-98):(1.0-2.0):(1.0-5.0).
  • a method of preparing the negative electrode 240 comprising: applying a slurry including a silicon-oxygen composite negative electrode material on the negative electrode current collector 242 to form a negative electrode active material layer on the negative electrode current collector 242 244; and drying the anode active material layer 244.
  • drying may be vacuum drying.
  • the total solids content of the slurry is between 30% and 60%. In some embodiments, the total solid content of the silicon-based composite material 100, the conductive agent and the binder in the slurry is 30%-60%. In some embodiments, the total solid content of the silicon-based composite material 100, the conductive agent, the binder and the graphite in the slurry is 30-60%.
  • the following steps are included: the components in the negative electrode active material layer 244 (eg, the silicon-based composite material 100 , the conductive agent and the adhesive binder, and optionally graphite) are dispersed in a solvent to form a slurry.
  • the components in the negative electrode active material layer 244 eg, the silicon-based composite material 100 , the conductive agent and the adhesive binder, and optionally graphite
  • the anode current collector 242 may be a metal.
  • the negative electrode current collector 242 includes, but is not limited to, one of a copper foil current collector and an aluminum foil current collector.
  • the slurry may contain solvent.
  • the solvent includes, but is not limited to, water.
  • the binder can improve the bonding properties of the anode active material particles to each other and to the current collector 242 .
  • the binder includes at least one of a non-aqueous binder or an aqueous binder.
  • Non-aqueous binders include, but are not limited to, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyvinylidene fluoride, polyvinylidene At least one of ethylene, polypropylene, polyamideimide, or polyimide.
  • Aqueous binders include, but are not limited to, at least one of rubber-based binders or polymeric resin binders.
  • Conductive agents can improve the conductivity of electrodes.
  • Conductive agents include but are not limited to high conductivity materials such as gold, copper, nickel, aluminum, silver, and/or similar metal powders or metal fibers and/or similar metal-based materials; or natural graphite, artificial graphite , carbon black, acetylene black, Ketjen black, carbon fiber and/or similar carbon-based materials; or polyphenylene derivatives and/or similar conductive polymers; and/or mixtures thereof.
  • An embodiment provides a lithium-ion battery 200 , and the lithium-ion battery 200 includes the silicon-based composite material 100 .
  • the lithium-ion battery 200 of some embodiments may include a positive electrode 220 , a negative electrode 240 , and an electrolyte 260 .
  • the lithium-ion battery 200 includes: a positive electrode 220; a negative electrode 240;
  • the anode active material layer 244 includes the silicon-oxygen composite material 100 .
  • the lithium-ion battery 200 may include a separator 280 disposed between the positive electrode 220 and the negative electrode 240 .
  • the membrane 280 may be a polymeric microporous membrane, such as a polypropylene microporous membrane. Septum 280 may be commercially available.
  • the lithium-ion battery 200 may include a housing 290 .
  • the positive electrode 220 , the negative electrode 240 , the separator 280 , and the electrolyte 260 may be accommodated in the case 290 .
  • the lithium-ion battery may be a cylindrical battery, a prismatic battery, or a coin cell battery.
  • Lithium-ion batteries can be rigid case batteries or pouch batteries.
  • the positive electrode 220 may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.
  • the positive electrode active material layer includes a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions, examples of the positive electrode active material include but are not limited to LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1-xy Co x My O 2 (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x+y ⁇ 1, and M is a metal such as Al, Sr, Mg, or La), one of lithium-transition metal oxides.
  • the electrolyte 260 includes, but is not limited to, a non-aqueous organic solvent, such as at least one of carbonates, esters, ethers, or ketones.
  • carbonates include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC) , at least one of methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC) or butylene carbonate (BC).
  • Esters include but are not limited to butyrolactone (BL), decanolide, valerolactone (BL), mevalonolactone, caprolactone (BC), methyl acetate, ethyl acetate or n-propyl acetate at least one of.
  • Ethers include, but are not limited to, may include dibutyl ether.
  • Ketones include, but are not limited to, polymethyl vinyl ketone.
  • the lithium-ion battery provided by the above embodiment has the advantages of high cycle capacity retention rate and low pole piece expansion rate.
  • the Al-Si alloy with a median particle size of 20 ⁇ m is mixed with grinding balls and then loaded into a high-energy ball mill.
  • the grinding balls are selected from 3mm quenched steel balls and a 5L stainless steel tank, and then argon protective gas is introduced to carry out high-energy ball milling.
  • the rotational speed of the ball mill is 500 r/min, the mass ratio of grinding ball and powder is 100:1, and after ball milling for 40 hours, submicron Al-Si alloy particles with a median particle size (D50) of 0.5 ⁇ m are obtained;
  • Hydrochloric acid solution add submicron Al-Si alloy particles into the hydrochloric acid solution, stir for 5h, and then centrifugally dry to obtain porous nano-silicon (median particle size is 300nm, porosity is 51%, specific surface area is 229m2 / g); adding flake graphite (its length:width:thickness ratio is 20:3:0.2) in porous nano-silicon, adding organic solvent methanol, the ratio of the median particle size of graphite to the median particle size of porous nano-silicon is 10:1, stirring to form a slurry, wherein the mass ratio of porous nano-silicon to graphite is 100:40, and then drying is performed to obtain a precursor; the obtained precursor and
  • the silicon-based composite material obtained in this example includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 25%, and the mass fraction of porous nano-silicon is 61%.
  • the scanning electron microscope image of the silicon-based composite material obtained in this example is shown in FIG. 6 ; the X-ray diffraction curve thereof is shown in FIG. 7 , and the peak positions of silicon and graphite can be observed from FIG. 7 .
  • the Al-Si alloy with a median particle size of 30 ⁇ m is mixed with the grinding balls and then loaded into a planetary ball mill.
  • the grinding balls are selected from 0.5mm zirconia balls, a 5L stainless steel tank, and then argon protective gas is introduced for high-energy ball milling.
  • the speed of the ball mill is 500r/min
  • the mass ratio of grinding balls and powder is 30:1
  • submicron Al-Si alloy particles with a median particle size (D50) of 0.3 ⁇ m are obtained; /L hydrochloric acid solution, submicron Al-Si alloy particles were added to the hydrochloric acid solution, stirred for 4 hours, and then centrifuged to dry to obtain porous nano-silicon (the median particle size was 200 nm, the porosity was 66%, and the specific surface area was 300m 2 /g); adding flake graphite (its length:width:thickness ratio is 5:2:0.1) in porous nano-silicon, adding organic solvent ethanol, wherein the median particle size of graphite and the median particle size of porous nano-silicon are The diameter ratio is 40:1, and a slurry is formed by stirring, wherein the mass ratio of porous nano-silicon to graphite is 100:50, and then drying is performed
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 28%, and the mass fraction of porous nano-silicon is 57.9%.
  • the Al-Si alloy with a median particle size of 50 ⁇ m is mixed with the grinding balls and then loaded into a sand mill.
  • the grinding balls are selected from 1mm zirconia balls for high-energy ball milling, wherein the mass ratio of the grinding balls to the powder is 10: 1.
  • submicron Al-Si alloy particles with a median particle size (D50) of 0.2 ⁇ m are obtained; 1 mol/L hydrochloric acid solution is prepared, and the submicron Al-Si alloy particles are added to the hydrochloric acid solution.
  • porous nano-silicon (the median particle size was 150 nm, the porosity was 60%, and the specific surface area was 280 m 2 /g); flake graphite was added to the porous nano-silicon (its length: width: Thickness ratio is 15:2:0.1), add organic solvent propanol, wherein the ratio of the median particle size of graphite to the median particle size of porous nano-silicon is 20:1, and stir to form a slurry, wherein the ratio of porous nano-silicon and graphite is 20:1.
  • the ratio is 100:70, and then spray drying is carried out to obtain the precursor; the precursor and the polyvinyl chloride are mixed in a mass ratio of 100:60, mixed evenly, and placed in a VC mixer, the adjustment frequency is 30Hz, and the mixing is 60min; Then transfer to the fusion machine, adjust the speed to 1000rpm, the width of the tool gap to 0.1cm, and fuse for 3.5h, transfer the fusion product to a high-temperature box furnace, pass nitrogen protective gas, and heat up to 950 °C for sintering.
  • the sintering time is After 3 h, it was cooled to room temperature, and pulverized, sieved, and demagnetized to obtain the silicon-based composite material.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 36%, and the mass fraction of porous nano-silicon is 51%.
  • FIG. 2 The scanning electron microscope image of the silicon-based composite material obtained in this example is shown in FIG. 2 ; the X-ray diffraction curve thereof is shown in FIG. 3 , and the peak positions of silicon and graphite can be observed from FIG. 3 .
  • the Zn-Si alloy with a median particle size of 50 ⁇ m was mixed with the grinding balls and put into a stirring mill.
  • the grinding balls were made of 1mm zirconia balls for high-energy ball milling.
  • the mass ratio of the grinding balls to the powder was 15:1.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 39%, and the mass fraction of porous nano-silicon is 32%.
  • the Al-Si alloy with a median particle size of 20 ⁇ m is mixed with grinding balls and then loaded into a high-energy ball mill.
  • the grinding balls are selected from 3mm quenched steel balls and a 5L stainless steel tank, and then argon protective gas is introduced to carry out high-energy ball milling.
  • the rotational speed of the ball mill is 500 r/min, the mass ratio of grinding balls and powder is 100:1, and after 40 hours of ball milling, submicron Al-Si alloy particles with a median particle size (D50) of 0.5 ⁇ m are obtained;
  • Hydrochloric acid solution add submicron Al-Si alloy particles into the hydrochloric acid solution, stir for 5h, and then centrifugally dry to obtain porous nano-silicon (median particle size is 300nm, porosity is 51%, specific surface area is 229m2 / g); add flake graphite (its length:width:thickness ratio is 5:0.4:0.1) in porous nano-silicon, add organic solvent acetone, wherein the ratio of the median particle size of graphite to the median particle size of porous nano-silicon 30:1, stir to form a slurry, wherein the mass ratio of porous nano-silicon to graphite is 80:50, and then spray drying is performed to obtain a precursor; the obtained
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 35%, and the mass fraction of porous nano-silicon is 56%.
  • the Al-Si alloy with a median particle size of 20 ⁇ m is mixed with grinding balls and then loaded into a high-energy ball mill.
  • the grinding balls are selected from 3mm quenched steel balls and a 5L stainless steel tank, and then argon protective gas is introduced to carry out high-energy ball milling.
  • the rotational speed of the ball mill is 500 r/min, the mass ratio of grinding ball and powder is 100:1, and after ball milling for 40 hours, submicron Al-Si alloy particles with a median particle size (D50) of 0.5 ⁇ m are obtained;
  • Hydrochloric acid solution add submicron Al-Si alloy particles into the hydrochloric acid solution, stir for 5h, and then centrifugally dry to obtain porous nano-silicon (median particle size is 300nm, porosity is 51%, specific surface area is 229m2 / g); add flake graphite (its length:width:thickness ratio is 10:1:0.1) in porous nano-silicon, add organic solvent triethanolamine, wherein the median particle size of graphite and the median particle size of porous nano-silicon The ratio is 40:1, and a slurry is formed by stirring, wherein the mass ratio of porous nano-silicon to graphite is 85:100, and then spray drying is performed to obtain the precursor; the
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 44%, and the mass fraction of porous nano-silicon is 37%.
  • Example 2 Other parameters and conditions are the same as those in Example 1, except that n-octadecic acid is added during the mixing process of porous nano-silicon, graphite and organic solvent.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 24.5%, and the mass fraction of porous nano-silicon is 60.1%.
  • Example 2 Other parameters and conditions are the same as in Example 1, except that sodium dodecylbenzenesulfonate is added during the mixing process of porous nano-silicon, graphite and organic solvent.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 25.2%, and the mass fraction of porous nano-silicon is 61%.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 25%, and the mass fraction of porous nano-silicon is 60%.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded between the layers of the flake graphite. Taking the mass fraction of the silicon-based composite material as 100%, the mass fraction of flake graphite is 25%, and the mass fraction of porous nano-silicon is 61.1%.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, porous graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded in the pores of the porous graphite.
  • the mass fraction of porous graphite is 24.1% and the mass fraction of porous nano-silicon is 60.9% based on the mass fraction of silicon-based composite material as 100%.
  • Example 2 Other conditions and parameters are the same as in Example 1, except that the graphite used is adjusted to be porous graphite, the pore size in the graphite is 50% larger than the particle size of porous nano-silicon, and the porosity is 10%.
  • the silicon-based composite material obtained in this embodiment includes porous nano-silicon, porous graphite and a carbon coating layer on the outer surface, and porous nano-silicon is embedded in the pores of the porous graphite.
  • the mass fraction of porous graphite is 24% and the mass fraction of porous nano-silicon is 59.8% based on the mass fraction of the silicon-based composite material as 100%.
  • Example 2 Other methods and conditions are the same as in Example 1, except that the porous nano-silicon is subjected to surface coating treatment before the porous nano-silicon, graphite and organic solvent are mixed to form a magnesium silicide layer with a thickness of 5 nm on the surface of the porous nano-silicon.
  • the silicon-based composite material obtained in this example includes porous nano-silicon, flake graphite and a carbon coating layer on the outer surface.
  • the surface of the porous nano-silicon is formed with a magnesium silicide layer, and the layers of the flake graphite are embedded with porous nano-silicon. .
  • the mass fraction of the silicon-based composite material is 100%, the mass fraction of flake graphite is 25%, the mass fraction of porous nano-silicon is 58%, and the mass fraction of magnesium silicide is 1.5%.
  • Example 2 Other methods and conditions are the same as in Example 1, except that the porous nano-silicon is replaced by nano-silicon of equal particle size.
  • Example 2 The other parameters and conditions are the same as those in Example 1, except that the porous nano-silicon is directly used as the precursor and the phenolic resin is mixed in a mass ratio of 60:30 for carbon coating.
  • Example 2 Other parameters and conditions are the same as in Example 1, except that the porous nano-silicon 120 is directly used as the precursor and the glucose is mixed in a mass ratio of 60:55 for carbon coating.
  • X-ray diffractometer Manufacturer: PANalytical, Netherlands, model: X'pert PRO;
  • the setting parameters of X-ray diffractometer are: divergence slit DS: 1.0°, scanning range: 10° ⁇ 90°; anti-scatter slit SS: 1.0°, scanning speed (Scan Step): 0.02°; receiving slit: 0.4SS /mm, scan mode: step scan, voltage: 40kV, integration time per step: 2s, current: 40mA, scan time: 2 hours, 13 minutes, 20 seconds;
  • the X-ray diffraction measurement of the silicon-based composite material obtained by the preparation of the present disclosure was carried out using the above instruments and parameters.
  • the silicon-based composite material 100 and the conductive agent (super P) and the binder (styrene-butadiene) were obtained from the above-mentioned Examples 1-13 and Comparative Examples 1-3, respectively.
  • Rubber: sodium carboxymethyl cellulose 1:1 (mass ratio))
  • Sheet, 1mol/L (LiPF 6 /EC (ethyl carbonate): DMC (dimethyl carbonate): EMC (ethyl methyl carbonate) 1:1:1 (volume ratio))
  • electrolyte 260, Celgard2400 diaphragm 280 , Shell 290 using conventional production process to assemble 18650 cylindrical single battery), and assemble the battery in a glove box filled with argon gas.
  • Q 1(dis) first discharge specific capacity when charging and discharging at 0.1C rate current, (mAh/g);
  • C 1(dis) the first discharge capacity when charging and discharging at 0.1C rate current, (mAh);
  • Q 1(cha) first charge specific capacity when charging and discharging at 0.1C rate current, (mAh/g);
  • the charge and discharge test of the battery is carried out on the LAND battery test system (CT2001A) 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.
  • C2001A LAND battery test system
  • the charge specific capacity, discharge specific capacity, discharge capacity and coulombic efficiency were measured.
  • the pole piece is assembled into a battery, which is placed on the LAND battery test system (CT3001K) of Wuhan Jinnuo Electronics Co., Ltd., under normal temperature conditions, 0.2C constant current charge and discharge, the charge and discharge voltage is limited to 0.005 ⁇ 1.5V, complete one charge and One discharge is counted as one cycle.
  • C3001K LAND battery test system
  • the battery was disassembled in the glove box, and the 240-pole piece of the negative electrode was taken out.
  • the thickness of the pole piece was measured with a micrometer, which was counted as D2 microns.
  • the expansion rate t of the pole piece is calculated according to formula 3, and the size parameter of the expansion rate is obtained.
  • FIG. 3 and FIG. 7 are the X-ray diffraction patterns of the silicon-based composite materials in Example 3 and Example 1 of the present disclosure, respectively.
  • Figures 4 and 8 are the first charge-discharge curves in Example 3 and Example 1, respectively. It can be seen from Figures 4 and 8 that the first charge-discharge capacity of the silicon-based composite materials in Examples 3 and 1 is relatively high, And the first Coulomb efficiency is also higher.
  • Figures 5 and 9 correspond to the cycle performance test curves of Example 3 and Example 1, respectively. From Figures 5 and 9, it can be seen that the silicon-based composite materials in Examples 3 and 1 have excellent cycle performance, and the cycle is 150 The weekly capacity retention rates were 92.5% and 90.1%, respectively. It should be noted that other Examples 2 and 4-13 also obtained technical effects similar to those of Example 3 in terms of initial charge-discharge capacity, initial Coulomb efficiency and cycle performance.
  • the silicon-based composite material of the present disclosure has excellent cycle performance and low expansion ratio; it can be seen from the comparison of Example 1 and Examples 7 to 8 of the present disclosure that the silicon-based composite material of the present disclosure has In the preparation process of the material 100, the above-mentioned dispersant is added, and the dispersant acts on the surface of the porous nano-silicon particles to strengthen the dispersion effect, which can promote the porous nano-silicon to enter the interlayer and/or pore structure of the graphite to form an embedded structure, and When combined with graphite, it is more uniform and tight, thereby reducing the expansion rate of silicon-based composites and optimizing the cycle performance.
  • Example 1 and Examples 11 to 12 of the present disclosure it can be seen that when porous graphite is used, the silicon-based composite material has a lower expansion rate and better cycle retention; compare Example 1 and Example 1 of the present application 13 It can be seen that when the surface of the porous nano-silicon contains the magnesium silicide layer 122, the silicon-based composite material has a lower expansion rate and a better cycle retention rate.
  • Example 1 Comparing Example 1 with Comparative Example 1, it can be seen that the use of porous nano-silicon 120 in Example 1 can avoid material expansion under the same conditions, improve the expansion performance of the material, and thus improve the cycle performance of the electrode material. Using ordinary nano-silicon particles, the material expands more under the same conditions, and the cycle performance is also worse.
  • Example 1 since flake graphite is used as the second phase material, compared with the embedded structure formed by the two-dimensional material and silicon, the carbon coating formed on the surface is The layer is denser, which is beneficial to avoid the contact between the electrolyte and the silicon, improve the interface stability, and the prepared material forms an embedded structure, which improves the cycle and expansion performance of the silicon-carbon product. Without using the flake graphite 160 or the porous graphite 140 as the second phase material, the prepared material cannot form an embedded structure, and the cycle and expansion performance of the obtained silicon carbon product is poor.
  • Comparing Example 1 with Comparative Example 3 it can be seen that under the condition that the proportion of glucose is similar to that of the added amount, Comparative Example 3 also does not use flake graphite 160 or porous graphite 140 as the second phase material, and the prepared materials are the same.
  • the embedded structure could not be formed, and the first Coulomb efficiency and cycle capacity retention rate were significantly lower than those of Example 1, and its cycle and expansion performance were significantly worse than those of the silicon-based composite material prepared in Example 1.
  • the present disclosure illustrates the detailed method of the present disclosure through the above-mentioned embodiments, but the present disclosure is not limited to the above-mentioned detailed method, that is, it does not mean that the present disclosure must rely on the above-mentioned detailed method to be implemented.
  • Those skilled in the art should understand that any improvement of the present disclosure, equivalent replacement of each raw material of the disclosed product, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present disclosure.
  • the present disclosure provides a porous nano-silicon-based composite material, a negative electrode, a lithium ion battery, and a preparation method thereof.
  • the porous nano-silicon-based composite material has ultra-low expansion properties and has excellent cycle performance for improving lithium-ion batteries.

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Abstract

本公开涉及了一种多孔纳米硅基复合材料、负极和锂离子电池及其制备方法，所述硅基复合材料包括纳米活性粒子和石墨，所述纳米活性粒子包括多孔纳米硅；所述石墨具有孔道结构，所述石墨的孔道结构中内嵌有所述纳米活性粒子，及/或，所述石墨具有层状结构，所述石墨的层状结构中内嵌有所述纳米活性粒子；相较于传统碳包覆的硅负极材料，本公开所制备的硅基负极材料具有膨胀率更低的优点，提升了循环性能。

Description

硅基复合材料、负极和锂离子电池及制备方法
相关申请的交叉引用
本申请要求于2020年08月31日提交中国专利局的申请号为2020108966608、名称为“硅基复合材料、其制备方法及锂离子电池”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
本公开涉及锂离子电池负极材料领域，涉及一种硅基复合材料、负极和锂离子电池及制备方法，尤其涉及一种多孔纳米硅基复合材料、负极和锂离子电池及制备方法。
背景技术
锂离子电池以其工作电压高、重量轻、自放电小、循环寿命长、无记忆效应、无环境污染以及安全性能好等特点，成为了目前理想的便携式电池。Si有很高的嵌锂容量，高达4200mAh·g -1，但是硅负极存在严重的体积膨胀效应，导致材料循环性能差，衰减很快，无法满足长循环、低膨胀的要求，从而阻碍了Si作为锂离子电池负极投入到实际应用中。
在负极材料的改性方法中，仍然存在如硅负极材料初期的衰减迅速，表明改性方法在改善材料的循环性能、控制体积膨胀方面存在欠缺的问题，又如制备的硅基复合材料容量偏低，无法满足高容量需求，此外仍存在着膨胀率较高，且长循环衰减较快等问题。
因此，研发一种具有超低膨胀率、循环性能优异的硅基复合材料是锂离子电池领域的技术难题。
公开内容
鉴于此，本公开提供了一种硅基复合材料，所述硅基复合材料包括纳米活性粒子和石墨，所述纳米活性粒子包括多孔纳米硅；
所述石墨具有孔道结构，所述石墨的孔道结构中内嵌有所述纳米活性粒子，及/或，所述石墨具有层状结构，所述石墨的层状结构中内嵌有所述纳米活性粒子。
一些实施方式中，所述硅基复合材料中，所述纳米活性粒子和所述石墨的质量比为(0.5～80):(10～50)。
一些实施方式中，所述硅基复合材料的中值粒径为1μm～40μm。
一些实施方式中，所述硅基复合材料的比表面积为1m 2/g～20m 2/g。
一些实施方式中，所述硅基复合材料表面形成有碳包覆层。
一些实施方式中，所述多孔纳米硅的中值粒径为1nm～500nm。
一些实施方式中，所述多孔纳米硅的比表面积为1m 2/g～500m 2/g。
一些实施方式中，所述多孔纳米硅的孔隙率为20％～90％。
一些实施方式中，所述多孔纳米硅的孔径为1nm～0.1μm。
一些实施方式中，所述纳米活性粒子还包括形成于所述多孔纳米硅的表面的硅化镁层。
一些实施方式中，所述硅化镁层的厚度为1nm～100nm。
一些实施方式中，以纳米活性粒子的质量为100％计，所述硅化镁层的质量分数为0.5％～10％。
一些实施方式中，所述石墨包括多孔石墨和片状石墨中的至少一种。
一些实施方式中，所述石墨的中值粒径为1μm～10μm。
一些实施方式中，所述石墨与所述多孔纳米硅的中值粒径之比为(10～40):1。
一些实施方式中，所述多孔石墨的孔隙率为10％～50％。
一些实施方式中，所述多孔石墨的孔径比所述多孔纳米硅的中值粒径大10％～50％。
一些实施方式中，所述片状石墨的层与层之间的层间距为10nm～500nm。
一些实施方式中，所述片状石墨的长:宽:厚的比值为(2～20):(0.4～3):(0.1～0.2)。
本公开提供了一种硅基复合材料的制备方法，包括以下步骤：
将纳米活性粒子和石墨在有机溶剂中混合使所述石墨的层间和/或孔道中内嵌有所述纳米活性粒子，得到浆料，干燥后得到所述硅基复合材料，所述纳米活性粒子包括多孔纳米硅。
一些实施方式中，所述多孔纳米硅的制备方法包括：将硅合金进行腐蚀，得到所述多孔纳米硅。
一些实施方式中，所述硅合金包括铝硅合金、铁硅合金及硅锌合金中的至少一种。
一些实施方式中，所述硅合金为亚微米级颗粒。
一些实施方式中，所述腐蚀采用的腐蚀剂包括但不限于盐酸、氢氟酸、硫酸及磷酸中的至少一种。
一些实施方式中，所述腐蚀的时间为0～7h且不包括0。
一些实施方式中，所述多孔纳米硅与所述石墨的质量比为(0.5～80):(10～50)。
一些实施方式中，所述有机溶剂包括但不限于芳香烃、氯化烃、醇醚、胺类化合物、酮、醇中的至少一种，醇的实例可以为R-OH中，R为C1～C11烷基中的至少一种。
一些实施方式中，所述有机溶剂包括甲醇、乙醇、丙醇、异丙醇、丁醇、戊醇、丙酮、甲苯、苯乙烯、全氯乙烯、三氯乙烯、乙烯乙二醇醚及三乙醇胺中的至少一种。
一些实施方式中，所述浆料的制备方法还包括：将纳米活性粒子、分散剂和石墨在有机溶剂中混合得到所述浆料。
一些实施方式中，所述分散剂包括但不限于含有羧基、磺酸基、氨基基团的表面活性剂中的至少一种。
一些实施方式中，所述分散剂包括但不限于正十八酸、环氧树脂、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、聚氯乙烯及聚乙烯吡咯烷酮中的至少一种。
一些实施方式中，所述干燥的方法包括真空干燥、喷雾干燥及旋转蒸发中的至少一种。
一些实施方式中，所述硅基复合材料的制备过程中还包括对所述干燥后得到的产物进行碳包覆。
一些实施方式中，所述碳包覆的方法包括：将所述干燥后得到的产物与碳源混合，烧结后得到所述硅基复合材料。
一些实施方式中，所述碳源包括糖类、树脂、有机酸、聚合多远醇、烯醇、易石墨化碳材料混合物中的至少一种。
一些实施方式中，所述碳源包括环氧树脂、柠檬酸、蔗糖、葡萄糖、沥青、酚醛树脂、果糖、聚乙二醇、聚乙烯醇和聚氯乙烯中的至少一种。
一些实施方式中，所述烧结的温度为500℃～1500℃，时间为1h～12h。
一些实施方式中，所述烧结的温度为800℃～1200℃，时间为3h～10h。
一些实施方式中，所述烧结后还包括：将烧结产物粉碎、筛分、除磁，得到所述硅基复合材料。
一些实施方式中，所述多孔纳米硅的制备过程中还包括：在所述多孔纳米硅表面形成硅化镁层。
一些实施方式中，所述形成硅化镁层的制备方法包括：将所述多孔纳米硅进行表面镀层处理，得到表面形成有硅化镁层的多孔纳米硅。
一些实施方式中，所述表面镀层处理的方法包括磁控溅射和真空镀膜中的至少一种。
一些实施方式中，所述硅基复合材料的制备方法包括以下步骤：
将硅合金进行腐蚀，得到多孔纳米硅，其中，所述硅合金为亚微米级颗粒；
将所述多孔纳米硅进行表面镀层处理，得到表面形成有硅化镁层的多孔纳米硅；
将所述表面形成有硅化镁层的多孔纳米硅、有机溶剂、分散剂和石墨混合后得到浆料，干燥后得到前驱体，其中，所述多孔纳米硅与所述石墨的质量比为(0.5～80):(10～50)；及
将所述前驱体与碳源进行混合，烧结后得到所述硅基复合材料。
本公开提供一种负极，包含所述硅基复合材料。
本公开提供了一种锂离子电池，所述锂离子电池包含所述硅基复合材料。
附图说明
为了更清楚地说明本公开实施方式的技术方案，下面将对实施方式中所需要使用的附图作简单地介绍，应当理解，以下附图仅示例地表征本公开的实施方式，图中尺寸比例与实施方式的真实比例并不能直接对应，同时以下附图仅示出了本公开的某些实施方式，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
图1是本公开实施方式中硅基复合材料制备过程的流程示意图。
图2是本公开实施例3中硅基复合材料的扫描电子显微镜图；
图3是本公开实施例3中硅基复合材料的X射线衍射图，其中G表示石墨，Si表示硅；
图4是本公开实施例3中硅基复合材料的首次充放电曲线；
图5是本公开实施例3中硅基复合材料的循环性能曲线；
图6是本公开实施例1中硅基复合材料的扫描电子显微镜图；
图7是本公开实施例1中硅基复合材料的X射线衍射图，其中G表示石墨，Si表示硅；
图8是本公开实施例1中硅基复合材料的首次充放电曲线；
图9是本公开实施例1中硅基复合材料的循环性能曲线；
图10是本公开一些实施方式提供的硅基复合材料的切面结构示意图；
图11是本公开一些实施方式提供的硅基复合材料的切面结构示意图；
图12是本公开一些实施方式提供的硅基复合材料的切面结构示意图；
图13是本公开一些实施方式提供的硅基复合材料的切面结构示意图；
图14是本公开一些实施方式提供的硅基复合材料的切面结构示意图；
图15是本公开一些实施方式的多孔纳米硅的切面结构示意图，其中(a)为未有硅化镁层包覆的多孔纳米硅，(b)为有硅化镁层包覆的多孔纳米硅；
图16是本公开一些实施方式的阴极结构示意图；
图17是本公开一些实施方式的电池示意图；
附图标记：100-硅基复合材料；120-多孔纳米硅；122-硅化镁层；140-多孔石墨；142-孔道结构；160-片状石墨；162-层状结构；180-碳包覆层；200-电池；220-正极；240-负极；242-负极集流体；244-负极活性材料层；260-电解液；280-隔膜；290-外壳。
实施方式
下面结合附图并通过实施方式来进一步说明本公开的技术方案。
为了使本公开的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本公开进行进一步详细说明。应当理解，此处所描述的实施例仅仅用以解释本公开，并不用于限定本公开。此外，下面所描述的本公开各个实施方式中所涉及的技术特征只要彼此之间未构成冲突就可以相互组合。在不脱离本公开实施例原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本公开实施例的保护范围。
一实施方式提供了硅基复合材料，用以解决现有技术中硅基负极材料膨胀率较高、极片膨胀率低的问题，提供一种低膨胀率、循环性能优异的硅基复合材料、负极和锂离子电池以及它们的制备方法。另一实施方式提供了上述硅基复合材料的制备方法。又一实施方式提供了包含上述硅基复合材料的锂离子电池。
I.硅基复合材料
如附图10和11以及图15(a)所示，一实施方式中，硅基复合材料100包括纳米活性粒子和石墨；石墨具有孔道结构142，石墨的孔道结构142中内嵌有纳米活性粒子，及/或，石墨具有层状结构162，石墨的层状结构162中内嵌有纳米活性粒子；纳米活性粒子包括多孔纳米硅120。
上述硅基复合材料100中包含多孔纳米硅120的纳米活性粒子与石墨形成内嵌结构，多孔纳米硅120内嵌在石墨的层间(即层状结构162)和/或石墨的孔道结构142中。其具有以下优势：多孔纳米硅120由于内部孔隙的存在，为硅的体积膨胀提供了膨胀空间，因而具备更低的膨胀率。同时，多孔纳米硅120内嵌在石墨的层间和/或孔道结构142中，上述层间隙和/或孔道的空间为多孔纳米硅120的膨胀提供了充足的膨胀空间，二者共同作用使得本公开硅基复合材料100的膨胀得到进一步控制，获得超低膨胀的硅基复合材料100，提升循环性能。
在一些实施方式中，硅基复合材料100中，纳米活性粒子和石墨的质量比为(0.5～80):(10～50)；包括但不限于0.5:10、0.5:20、0.5:35、0.5:45、0.5:50、1:45、5:40、10:35、20:30、40:25、60:20、70:15、80:10、80:20、80:35、80:45或80:50等。以上范围的质量比，不仅使得纳米活性粒子均匀分布在石墨的层状结构162和/或孔道结构142，而且提高了负极材料以及电池200的整体性能。而若纳米活性粒子占比过高，则纳米活性粒子很难均匀分布，会有裸露于石墨外的纳米活性粒子存在，如果纳米活性粒子占比过低，则活性物质太少，使得负极材料以及电池200的整体性能降低。
在一些实施方式中，硅基复合材料100的中值粒径为1μm～40μm或5μm～20μm；包括但不限于1μm、2μm、5μm、10μm、15μm、20μm、25μm、30μm、35μm或40μm等。以上中值粒径范围不仅会降低硅体积的膨胀概率，而且生成的产业化成本低，不会对SEI膜形成过程中消耗更多不可逆锂，提高了首次库伦效率。而如果硅基复合材料100的中值粒径过大，会使得产品中复合材料粒度分布中的大颗粒数量及尺寸增加，导致硅的体积膨胀较高；粒径过小，则实施困难，产业化成本高，同时使得产品的比表面积更大，在SEI膜形成过程中消耗更多不可逆锂，造成首次效率下降。
在一些实施方式中，硅基复合材料100的比表面积为1m 2/g～20m 2/g或1m 2/g～10m 2/g；包括但不限于1m 2/g、2m 2/g、5m 2/g、8m 2/g、10m 2/g、12m 2/g、15m 2/g、18m 2/g或20m 2/g等。如图12和13所示，在一些实施方式中，硅基复合材料100表面形成有碳包覆层180。通过对硅基复合材料进行碳包覆，可以进一步提高材料的导电性，减轻颗粒间的电子传导阻力。
(A)多孔纳米硅
在一些实施方式中，多孔纳米硅120的中值粒径为1nm～500nm，5nm～250nm或50nm～200nm；包括但不限于1nm、10nm、20nm、50nm、100nm、150nm、200nm、250nm、300nm、350nm、400nm、450nm或500nm等。以上范围的中值粒径不仅提高包覆、造粒效率，而且粒子不易氧化。而若中值粒径过 小，会造成粒子容易氧化，技术实施困难；中值粒径过大，则包覆困难，成型造粒过难。在一些实施方式中，多孔纳米硅120的比表面积为1m 2/g～500m 2/g，10m 2/g～400m 2/g或20m 2/g～400m 2/g。包括但不限于1m 2/g、5m 2/g、10m 2/g、30m 2/g、50m 2/g、100m 2/g、150m 2/g、200m 2/g、250m 2/g、300m 2/g、350m 2/g、400m 2/g、450m 2/g或500m 2/g等。在以上比表面积范围内，比表面积增加，提供锂离子与硅接触点更多，从而更加有利于锂离子的顺利嵌入和脱出，材料的倍率性能得以提升。
在一些实施方式中，多孔纳米硅120的孔隙率为20％～90％，20％～80％，40％～80％，包括但不限于20％、30％、40％、50％、60％、70％、80％或90％等。在以上孔隙率的范围内，不仅不会增加不可逆容量。从而提升了首次可逆容量，而且还提高了体积能量密度，从而提高了电极的首次库伦效率和循环效率。而如果孔隙率过大，则使得多孔纳米硅120的比表面积更大，在SEI膜形成过程中消耗锂更多，不可逆容量增加，从而降低首次库伦效率，同时降低了振实密度，不利于提升体积能量密度，此外，孔隙率过小，则没有足够的空间缓冲纳米硅的膨胀，颗粒会粉化，导致循环变差。
在一些实施方式中，多孔纳米硅120的孔径为1nm～0.1μm，包括但不限于1nm、5nm、10nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm、90nm或0.1μm等。如附图14和15(b)所示，在一些实施方式中，纳米活性粒子还包括形成于多孔纳米硅120的表面的硅化镁层122。
在一些实施方式中，硅化镁层122存在是多孔纳米硅120颗粒的外表面，至少在一个实施方式中，硅化镁层122不仅存在于多孔纳米硅120的外表面，还存在于多孔纳米硅120的孔内表面。
上述实施方式中，多孔纳米硅120的表面形成有硅化镁层122，覆盖有硅化镁层122的多孔纳米硅120内嵌入石墨的层间和/或孔道中，其能解决相关技术中存在的内嵌结构外层包覆层不致密，反应过程中电解液260会浸润进入与硅接触，导致出现界面不稳定的问题。不受理论约束，电解液260在直接接触多孔纳米硅120(未经过硅化镁层122包覆)的情况下，会使得SEI膜是不稳定的，从而导致电池200的循环次数降低，库伦效率降低。本公开实施例中通过对多孔纳米硅120表面进行修饰，沉积硅化镁层122，利用硅化镁改善与电解液260的接触，提升了循环过程中的库伦效率，提升循环性能。
可以理解的是，多孔纳米硅120表面的硅化镁层122改善了多孔纳米硅120与电解液260的接触效果，减少充放电过程中Li 2CO 3生成，保证生成的SEI膜更加稳定，减少了不可逆锂离子消耗，从而提高循环库伦效率，提升循环性能。同时，多孔纳米硅120自身存在孔隙，可以利用已有的孔隙来缓解自身的膨胀，从而有效降低硅基材料的体积膨胀率。此外表面包覆的硅化镁与硅的嵌锂电位不同，可以互相充当彼此的缓冲层，进一步降低硅的体积膨胀效应，从而获得超低膨胀效果。
在一些实施方式中，硅化镁层122的厚度为1nm～100nm，包括但不限于5nm、10nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm或90nm等。在以上厚度范围的硅化镁层可以使得硅化镁与多孔纳米硅120有效结合，提高其保护性能，硅化镁层122过厚，则会导致硅化镁与多孔纳米硅120的结合性较差，而硅化镁层122过太薄，则其保护的作用性较弱。
在一些实施方式中，以纳米活性粒子的质量为100％计，硅化镁层122的质量分数为0.5％～10％，包括但不限于0.5％、1％、3％、5％、7％、9％或10％等。
(B)石墨
在一些实施方式中，石墨包括多孔石墨140或片状石墨160中的至少一种。
需要说明的是，上述多孔石墨140是指石墨内部具备一定孔隙。在一些实施方式中，通过对天然石墨或人造石墨进行造孔处理而获得多孔石墨140。上述片状石墨160是指具备片层结构的石墨，例如其厚度与长轴方向的长度比值＞2.5。
在一些实施方式中，石墨的中值粒径为1μm～10μm，3μm～9μm，或4μm～7μm，包括但不限于2μm、 3μm、4μm、5μm、6μm、7μm、8μm或9μm等。
上述实施方式中石墨采用上述粒径的石墨，多孔纳米硅120内嵌于石墨的孔道结构142中，其相较于二维材料与硅形成的内嵌结构，其表面形成的碳包覆层180更加致密，进而有利于避免电解液260与硅的接触，提升界面稳定性。
在一些实施方式中，石墨与多孔纳米硅120的中值粒径之比为(10～40):1，包括但不限于10:1、15:1、20:1、25:1、30:1、35:1或40:1等。
在一些实施方式中，多孔石墨140的孔隙率为10％～50％，15％～40％，或25％～35％；包括但不限于15％、20％、25％、30％、35％、40％或45％等。在上述孔隙率的范围内，可以满足纳米硅的有效填充量，从而实现首次可逆容量、首次库伦效率、循环容量保持率的提高，以及膨胀率的降低。
在一些实施方式中，多孔石墨140的孔径比多孔纳米硅120的中值粒径大10％～50％，15％～40％，或25％～35％；包括但不限于15％、20％、25％、30％、35％、40％或45％等。其中，多孔石墨140的孔径为平均孔径。
上述实施方式中，石墨采用多孔石墨140，并控制多孔石墨140的孔径较多孔纳米硅120的粒径大10％～50％，其有利于多孔纳米硅120进入并储存在多孔石墨140的孔道中，并限制硅的膨胀，得到超低膨胀的硅基复合材料100，进而改善锂离子电池200的循环性能。
在一些实施方式中，片状石墨160的层与层之间的层间距为10nm～500nm，包括但不限于10nm、20nm、50nm、100nm、150nm、200nm、250nm、300nm、350nm、400nm、450nm或500nm等。
在一些实施方式中，片状石墨160的长:宽:厚的比值为(2～20):(0.4～3):(0.1～0.2)，包括但不限于20:3:0.2、15:2:0.1、10:1:0.1、5:2:0.1、5:0.4:0.1或2:0.4:0.15等。
II.硅基复合材料的制备
上述硅基复合材料100的制备方法，包括步骤S100～S300，其流程示意图如图1所示。
步骤S100：制备纳米活性粒子。
在一些实施方式中，制备纳米活性粒子包括步骤S110和步骤S120。
在步骤S110，将硅合金进行腐蚀，得到多孔纳米硅120。
在一些实施方式中，硅合金包括但不限于铝硅合金、铁硅合金及硅锌合金中的至少一种。在一些实施方式中，硅合金包括但不限于铝硅合金、铁硅合金、硅锌合金、镁硅合金、铝镁硅合金、硅锰合金、铜镍硅合金、或硅铬合金中的至少一种。在一些实施方式中，硅合金为亚微米级颗粒。
在一些实施方式中，腐蚀采用的腐蚀剂包括盐酸、氢氟酸、硫酸及磷酸中的至少一种。
在一些实施方式中，腐蚀采用的腐蚀剂包括但不限于盐酸、氢氟酸、硫酸、磷酸、醋酸、硝酸、亚硫酸、高氯酸、氢硫酸、次氯酸或苯甲酸中的至少一种。
在一些实施方式中，腐蚀的时间为0～7h且不为0，包括但不限于0.1h、0.5h、1h、1.5h、2h、2.5h、3h、3.5h、4h、4.5h、5h、5.5h、6h、6.5h或7h等。一些实施方式中，腐蚀的时间为0.5h～5h。
在一些实施方式中，，多孔纳米硅120也可以通过商业途径购买得到。
步骤S120、将多孔纳米硅120进行表面镀层处理，得到表面形成有硅化镁层122的多孔纳米硅120。
在一些实施方式中，表面镀层处理的方法包括磁控溅射或真空镀膜中的至少一种。
一些实施方式中，磁控溅射和真空镀膜分别在磁控溅射设备和真空镀膜设备中进行。
在一些实施方式中，步骤S120可以省略，此时多孔纳米硅120表面没有形成硅化镁层122。
步骤S200：制备硅基复合材料
在步骤S200，将上述表面形成有硅化镁层122的多孔纳米硅120、有机溶剂、分散剂和石墨混合后得 到浆料，干燥后得到硅基复合材料100。
在一些实施方式中，有机溶剂包括但不限于芳香烃、氯化烃、醇醚、胺类化合物、酮或醇中的至少一种。醇的实例可以为R-OH中，R为C1～C11烷基中的至少一种。在一些实施方式中，芳香烃包括但不限于甲苯、二甲苯、乙苯、苯乙烯、丁基甲苯、乙烯基甲苯中的至少一种。
在一些实施方式中，氯化烃包括但不限于全氯乙烯、二氯甲烷、氯仿、四氯化碳、三氯乙烯、四氯乙烯、三氯丙烷、二氯乙烷、氯苯、二氯苯中的至少一种。
在一些实施方式中，醇醚包括但不限于乙烯乙二醇醚、二乙二醇单甲醚、丙二醇甲醚、二丙二醇二甲醚、乙二醇单乙醚、乙二醇单丁醚中的至少一种。
在一些实施方式中，胺类化合物包括但不限于三乙醇胺、二乙醇胺、丁胺中的至少一种。
在一些实施方式中，醇包括但不限于甲醇、乙醇、丙醇、异丙醇、丁醇、异丁醇、戊醇、异戊醇、己醇、异己醇、庚醇、辛醇、壬醇、庚醇中的至少一种。
在一些实施方式中，酮包括但不限于丙酮、甲基丁酮、甲基异丁酮、环己酮、甲苯环己酮中的至少一种。
在一些实施方式中，有机溶剂包括甲醇、乙醇、丙醇、异丙醇、丁醇、戊醇、丙酮、甲苯、苯乙烯、全氯乙烯、三氯乙烯、乙烯乙二醇醚及三乙醇胺中的至少一种。
上述实施方式提供了一种多孔纳米硅120基复合材料的制备方法，其技术原理主要是：以硅合金为原料进行腐蚀，得到多孔纳米硅120，之后在有机溶剂条件下使得多孔纳米硅120进入石墨的孔道和/或层间，得到硅基复合材料100。
需要说明的是，上述实施方式提供的硅基复合材料100的制备方法中，本领域技术人员可以在浆料中加入分散剂。存在分散剂时，分散剂作用于多孔纳米硅120粒子表面，加强分散效果，其能明显促进多孔纳米硅120进入石墨的孔道结构142中，形成内嵌结构，这样多孔纳米硅120在和石墨结合的时候，更加均匀和紧密，进而有效降低硅基复合材料100的膨胀率。
在一些实施方式中，分散剂包括但不限于含有羧基、磺酸基、氨基基团的表面活性剂中的至少一种。
一些实施方式中，含有羧基基团的表面活性剂包括但不限于正十八酸、正二十酸、月桂酸、聚丙烯酸、硬脂酸、油酸、亚油酸、棕榈酸、月桂酸钠/钾、肉豆蔻酸钠/钾、棕榈酸钠/钾、硬脂酸钠/钾中的至少一种。
一些实施方式中，含有氨基基团的的表面活性剂包括但不限于聚乙烯吡咯烷酮、谷氨酸钠、甘氨酸钠、十二烷基聚氧乙烯醚硫酸酯钠/铵、十二烷基硫酸钠铵、椰油酰单乙醇酰胺、椰油酰二乙醇酰胺中的至少一种。
一些实施方式中，含有磺酸基基团的表面活性剂包括但不限于十二烷基苯磺酸钠、烷基苯磺酸钠、α-烯烃磺酸盐、α-磺基单羧酸、石油磺酸盐中的至少一种。在一些实施方式中，分散剂包括正十八酸、环氧树脂、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、聚氯乙烯及聚乙烯吡咯烷酮中的至少一种。
可以理解的是，采用上述分散剂，其表面含有的羧基、氨基等功能团能与多孔纳米硅120表面的Si-O基团反应，进而促使多孔纳米硅120进入石墨的孔道中，形成内嵌结构，进而降低硅基复合材料100的膨胀率。
在一些实施方式中，干燥的方法包括但不限于真空干燥、喷雾干燥或旋转蒸发中的至少一种。
在一些实施方式中，多孔纳米硅120与石墨的质量比为(0.5～80):(10～50)；包括但不限于1:45、5:40、10:35、20:30、40:25、60:20、70:15或80:50等。
步骤S300、碳包覆
在一些实施方式中，碳包覆的步骤包括：将干燥后得到的产物与碳源混合，烧结后得到形成有碳包 覆层180的硅基复合材料100。
一些实施方式中，碳源包括糖类、树脂、有机酸、聚合多元醇、烯醇或易石墨化碳材料混合物中的至少一种。
在一些实施方式中，糖类包括但不限于蔗糖、葡萄糖、果糖或乳糖中的至少一种；
在一些实施方式中，树脂包括但不限于环氧树脂、酚醛树脂、聚氯乙烯或聚酯树脂中的至少一种；
在一些实施方式中，有机酸包括但不限于羧基、磺酸、亚磺酸或硫羧酸中的至少一种；
在一些实施方式中，羧酸包括但不限于甲酸、乙酸、丙酸、丁酸或柠檬酸中的至少一种；
在一些实施方式中，聚合多元醇、烯醇包括但不限于聚乙二醇或聚乙烯醇中的至少一种；
在一些实施方式中，易石墨化碳材料混合物包括但不限于沥青、石油焦或针状焦中的至少一种。
在一些实施方式中，碳源包括环氧树脂、柠檬酸、蔗糖、葡萄糖、沥青、酚醛树脂、果糖、聚乙二醇、聚乙烯醇和聚氯乙烯中的至少一种。
在一些实施方式中，烧结的温度为500℃～1500℃，包括但不限于600℃、700℃、800℃、900℃、1000℃、1100℃、1200℃、1300℃或1400℃等。烧结的时间可以为1h～12h，包括但不限于2h、3h、4h、5h、6h、7h、8h、9h、10h或11h等。
在一些实施方式中，烧结的温度为800℃～1200℃，包括但不限于，可以为850℃、900℃、950℃、1000℃、1050℃、1100℃或1150℃等。烧结的时间可以为3h～10h，包括但不限于4h、5h、6h、7h、8h或9h等。
在一些实施方式中，烧结后还包括：将烧结产物粉碎、筛分、除磁，得到硅基复合材料100。
如图10和11所示，在一些实施方式，步骤S300省略，即硅基复合材料100表面未形成碳包覆层180。
III.负极材料及负极
硅基复合材料100可以用作负极活性材料，例如锂离子电池200中的负极活性材料。一实施方式提供了负极材料，负极材料包含上述硅基复合材料100。
在一些实施方式中，负极材料还包含粘结剂。
在一些实施方式中，负极材料还包含导电剂。在一些实施方式中，负极材料包含上述硅氧复合材料、粘结剂和导电剂。
在一些实施方式中，负极材料还包含石墨。在一些实施方式中，负极材料包含上述硅氧复合材料、粘结剂、导电剂和石墨。
一实施方式提供了制备负极材料的方法，包括将上述组分混合。一实施方式提供了制备负极材料的方法，包括：将硅基复合材料100以及导电剂和粘结剂混合。一实施方式提供了制备负极材料的方法，包括：将硅基复合材料100、导电剂、粘结剂和石墨混合。
一实施方式提供了负极240，包括硅基复合材料100。
如图16所示，在一些实施方式中，负极包括：负极集流体242以及在负极集流体242上的负极性材料层244，其中，负极性材料层244包含上述负极材料。
一实施方式提供了制备负极240的方法，包括：将包括负极材料的浆料涂覆于负极集流体242上。
在一些实施方式中，提供了负极，包括：负极集流体242以及在负极集流体242上的负极活性材料层244，其中，负极活性材料层244包含上述硅基复合材料100。在一些实施方式中，负极活性材料层244还包含导电剂和粘结剂。在一些实施方式中，负极活性材料层244还包含石墨。
在一些实施方式中，硅基复合材料100、导电剂和粘结剂的质量比为(93～98):(1.0～2.0):(1.0～5.0)。
在一些实施方式中，提供了制备负极240的方法，包括：将包括硅氧复合负极材料的浆料施加于所述 负极集流体242上，以在所述负极集流体242上形成负极活性材料层244；以及干燥所述负极活性材料层244。
在一些实施方式中，干燥可以是真空干燥。一些实施方式中，浆料的总固含量在30％～60％。一些实施方式中，浆料中硅基复合材料100、导电剂和粘结剂的总固含量在30％～60％。一些实施方式中，浆料中硅基复合材料100、导电剂、粘结剂和石墨的总固含量在30～60％。
在一些实施方式中，在将浆料施加于所述负极集流体(242)上之前，包括以下步骤：将负极活性材料层244中的各组分(例如硅基复合材料100、导电剂和粘结剂，以及可选的石墨)分散在溶剂中，以形成浆料。
在一些实施方式中，负极集流体242可以是金属。在一些实施方式中，负极集流体242包括但不限于：铜箔集流体、铝箔集流体中的一种。
浆料可以包含溶剂。在一些实施方式中，该溶剂包括但不限于为水。
不受理论的约束，据信粘结剂可以改善负极活性物质颗粒彼此以及与集流体242的粘结性质。在一些实施方式中，粘结剂包括非水性粘结剂或水性粘结剂中的至少一种。非水性粘结剂包括但不限于聚氯乙烯、羧化聚氯乙烯、聚氟乙烯、包含亚乙基氧的聚合物、聚乙烯基吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏氟乙烯、聚乙烯、聚丙烯、聚酰胺酰亚胺、或聚酰亚胺中的至少一种。水性粘结剂包括但不限于基于橡胶的粘结剂或者聚合物树脂粘结剂中的至少一种。
导电剂可以提升电极的导电性。导电剂包括但不限于高导电率的材料，例如为金、铜、镍、铝、银、和/或类似的金属粉末或金属纤维和/或类似的基于金属的材料；或者天然石墨、人造石墨、炭黑、乙炔黑、科琴黑、碳纤维和/或类似的基于碳的材料；或者聚亚苯基衍生物和/或类似的导电聚合物；和/或其混合物。
IV.锂离子电池
一实施方式提供一种锂离子电池200，所述锂离子电池200包含所述的硅基复合材料100。
一些实施方式的锂离子电池200可以包括：正极220、负极240，以及电解液260。
一些实施方式中，锂离子电池200包括：正极220；负极240；以及电解液260，其中，负极240包括负极集流体242和设置在所述负极集流体242上的负极活性材料层244，所述负极活性材料层244包括所述硅氧复合材料100。
如图17所示，在一些实施方式中，锂离子电池200可以包括设置在正极220和负极240之间的隔膜280。隔膜280可以是聚合物微孔膜，例如聚丙烯微孔膜。隔膜280可以是商购的。
在一些实施方式中，锂离子电池200可以包括外壳290。正极220、负极240、隔膜280、电解液260可以容纳在外壳290中。
一些实施方式中，锂离子电池可以是圆柱形电池、方形电池或纽扣电池。锂离子电池可以是刚性外壳电池或者软包电池。
一些实施方式中，正极220可以包括正极集流体和设置在正极集流体上的正极活性材料层。正极活性材料层包括能够可逆地嵌入和解嵌锂离子的正极活性材料，正极活性材料的实例包括但不限于LiCoO 2、LiNiO 2、LiMnO 2、LiMn 2O 4、LiNi 1-x-yCo xM yO 2(0≤x≤1，0≤y≤1，0≤x+y≤1，且M是诸如Al、Sr、Mg或La的金属)、锂-过渡金属氧化物中的一种。
一些实施方式中，电解液260包括但不限于非水有机溶剂，例如碳酸酯、酯、醚或酮中的至少一种。一些实施方式中，碳酸酯包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)、碳酸亚乙酯(EC)、碳酸亚丙酯(PC)或碳酸亚丁酯(BC)中的至少一种。酯包括但不限于丁内酯(BL)、癸内酯、戊内酯(BL)、甲瓦龙酸内酯、己内酯(BC)、乙酸甲 酯、乙酸乙酯或乙酸正丙酯中的至少一种。醚包括但不限于可包括二丁基醚。酮包括但不限于聚甲基乙烯基酮。
本公开实施方式的优点将会在下面的说明书中部分阐明，一部分根据说明书是显而易见的，或者可以通过本公开实施例的部分实施例而获得。
上述实施方式提供的锂离子电池具有循环容量保持率高、极片膨胀率低的优点。
为更好地说明本公开，便于理解本公开的技术方案，下面对本公开进一步详细说明。当然，下面的实施例仅仅是本公开的简易例子，并不代表或限制本公开的权利保护范围，本公开保护范围以权利要求书为准。需要说明的是，在不冲突的情况下，本公开的实施方式中的特征可以相互结合。
实施例
实施例1
将中值粒径为20μm的Al-Si合金与磨球混合后装入高能球磨机中，磨球选用3mm的淬火钢球，5L不锈钢罐，然后通入氩气保护气体，进行高能球磨，其中，球磨机转速为500r/min，磨球和粉末的质量比为100:1，球磨40h后，得到中值粒径(D50)为0.5μm的亚微米级Al-Si合金颗粒；配置好1mol/L的盐酸溶液，将亚微米级Al-Si合金颗粒加入到盐酸溶液中，搅拌5h，然后离心干燥处理，获得多孔纳米硅(中值粒径为300nm，孔隙率为51％，比表面积为229m 2/g)；在多孔纳米硅中添加片状石墨(其长:宽:厚比值为20:3:0.2)，加入有机溶剂甲醇，石墨的中值粒径与多孔纳米硅的中值粒径比为10:1，搅拌形成浆料，其中，多孔纳米硅与石墨的质量比为100:40，之后进行干燥获得前驱体；将所得前躯体与葡萄糖按质量比60:55进行配比，混合均匀后置于VC混合机中，调节频率为30Hz，混合60min，之后转移至融合机中，调节转速为2000rpm，融合2h，将融合产物转移至高温箱式炉中，通入氮气保护气体，升温至850℃进行烧结，烧结时间为5h，之后冷却至室温，进行粉碎、筛分、除磁，得到所述硅基复合材料。
本实施例所得的硅基复合材料中，包括多孔纳米硅，片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为25％，多孔纳米硅的质量分数为61％。
本实施例得到的硅基复合材料的扫描电子显微镜图如图6所示；其X射线衍射曲线如图7所示，由图7可以观察到硅和石墨的峰位。
实施例2
将中值粒径为30μm的Al-Si合金与磨球混合后装入行星式球磨机中，磨球选用0.5mm的二氧化锆球，5L不锈钢罐，然后通入氩气保护气体，进行高能球磨，其中，球磨机转速为500r/min，磨球和粉末的质量比为30:1，球磨30h后，得到中值粒径(D50)为0.3μm的亚微米级Al-Si合金颗粒；配置好2mol/L的盐酸溶液，将亚微米级Al-Si合金颗粒加入到盐酸溶液中，搅拌4h，然后离心干燥处理，获得多孔纳米硅(中值粒径为200nm，孔隙率为66％，比表面积为300m 2/g)；在多孔纳米硅中添加片状石墨(其长:宽:厚比值为5:2:0.1)，加入有机溶剂乙醇，其中石墨中值粒径与多孔纳米硅的中值粒径比为40:1，搅拌形成浆料，其中，多孔纳米硅与石墨的质量比为100:50，然后进行干燥获得前驱体；将前躯体与蔗糖按质量比60:30进行配比，混合均匀后置于VC混合机中，调节频率为30Hz，混合60min；之后转移至融合机中，调节转速为1500rpm，融合3h，将融合产物转移至高温箱式炉中，通入氮气保护气体，升温至850℃进行烧结，烧结时间为5h，之后冷却至室温，进行粉碎、筛分、除磁，得到所述硅基复合材料。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为28％，多孔纳米硅的质量分数为57.9％。
实施例3
将中值粒径为50μm的Al-Si合金与磨球混合后装入砂磨机中，磨球选用1mm的二氧化锆球，进行高能球磨，其中，磨球和粉末的质量比为10:1，球磨10h后，得到中值粒径(D50)为0.2μm的亚微米级Al-Si合金颗粒；配置好1mol/L的盐酸溶液，将亚微米级Al-Si合金颗粒加入到盐酸溶液中，搅拌2h，离心干燥处理，获得多孔纳米硅(中值粒径为150nm，孔隙率为60％，比表面积为280m 2/g)；在多孔纳米硅中添加片状石墨(其长:宽:厚比值为15:2:0.1)，加入有机溶剂丙醇，其中石墨的中值粒径与多孔纳米硅的中值粒径比为20:1，搅拌形成浆料，其中多孔纳米硅与石墨的配比为100:70，然后进行喷雾干燥获得前驱体；将前躯体与聚氯乙烯按质量比100:60进行配比，混合均匀后置于VC混合机中，调节频率为30Hz，混合60min；之后转移至融合机中，调节转速为1000rpm，刀具间隙宽度为0.1cm，融合3.5h，将融合产物转移至高温箱式炉中，通入氮气保护气体，升温至950℃进行烧结，烧结时间为3h，之后冷却至室温，进行粉碎、筛分、除磁，得到所述硅基复合材料。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为36％，多孔纳米硅的质量分数为51％。
本实施例得到的硅基复合材料的扫描电子显微镜图如图2所示；其X射线衍射曲线如图3所示，由图3可以观察到硅和石墨的峰位。
实施例4
将中值粒径为50μm的Zn-Si合金与磨球混合后装入搅拌磨中，磨球选用1mm的二氧化锆球，进行高能球磨，其中，磨球和粉末的质量比为15:1，球磨15h后，得到中值粒径(D50)为0.4μm的亚微米级Zn-Si合金颗粒；配置好1mol/L的盐酸溶液，将亚微米级Zn-Si合金颗粒加入到盐酸溶液中，搅拌6h，离心干燥处理，获得多孔纳米硅(中值粒径为250nm，孔隙率为70％，比表面积为250m 2/g)；在多孔纳米硅中添加片状石墨(其长:宽:厚比值为2:0.4:0.15)，加入有机溶剂甲苯，其中石墨的中值粒径与多孔纳米硅的中值粒径比为15:1，搅拌形成浆料，其中，多孔纳米硅与石墨的质量配比为80:100，之后进行喷雾干燥，获得前驱体；将前躯体与酚醛树脂按质量比50:50进行配比，混合均匀后置于VC混合机中，调节频率为30Hz，混合40min，之后转移至融合机中，调节转速为1600rpm，刀具间隙宽度为0.1cm，融合2.5h，将融合产物转移至高温箱式炉中，通入氮气保护气体，升温至950℃进行烧结，烧结时间为5h，之后冷却至室温，进行粉碎、筛分、除磁，得到所述硅基复合材料。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为39％，多孔纳米硅的质量分数为32％。
实施例5
将中值粒径为20μm的Al-Si合金与磨球混合后装入高能球磨机中，磨球选用3mm的淬火钢球，5L不锈钢罐，然后通入氩气保护气体，进行高能球磨，其中，球磨机转速为500r/min，磨球和粉末的质量比为100:1，球磨40h后，得到中值粒径(D50)为0.5μm的亚微米级Al-Si合金颗粒；配置好2mol/L的盐酸溶液，将亚微米级Al-Si合金颗粒加入到盐酸溶液中，搅拌5h，然后离心干燥处理，获得多孔纳米硅(中值粒径为300nm，孔隙率为51％，比表面积为229m 2/g)；在多孔纳米硅中添加片状石墨(其长:宽:厚比值为5:0.4:0.1)，加入有机溶剂丙酮，其中石墨的中值粒径与多孔纳米硅的中值粒径比为30:1，搅拌形成浆料，其中，多孔纳米硅与石墨的质量比为80:50，之后进行喷雾干燥获得前驱体；将所得前躯体与聚丙烯酸按质量比90:45进行配比，混合均匀后置于VC混合机中，调节频率为30Hz，混合60min，之后转移至 融合机中，调节转速为2000rpm，刀具间隙宽度为0.1cm，融合2h，将融合产物转移至高温箱式炉中，通入氮气保护气体，升温至1500℃进行烧结，烧结时间为1h，之后冷却至室温，进行粉碎、筛分、除磁，得到所述硅基复合材料。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为35％，多孔纳米硅的质量分数为56％。
实施例6
将中值粒径为20μm的Al-Si合金与磨球混合后装入高能球磨机中，磨球选用3mm的淬火钢球，5L不锈钢罐，然后通入氩气保护气体，进行高能球磨，其中，球磨机转速为500r/min，磨球和粉末的质量比为100:1，球磨40h后，得到中值粒径(D50)为0.5μm的亚微米级Al-Si合金颗粒；配置好1mol/L的盐酸溶液，将亚微米级Al-Si合金颗粒加入到盐酸溶液中，搅拌5h，然后离心干燥处理，获得多孔纳米硅(中值粒径为300nm，孔隙率为51％，比表面积为229m 2/g)；在多孔纳米硅中添加片状石墨(其长:宽:厚比值为10:1:0.1)，加入有机溶剂三乙醇胺，其中石墨的中值粒径与多孔纳米硅的中值粒径比为40:1，搅拌形成浆料，其中，多孔纳米硅与石墨的质量比为85:100，之后进行喷雾干燥获得前驱体；将所得前躯体与酚醛树脂按质量比110:100进行配比，混合均匀后置于VC混合机中，调节频率为30Hz，混合60min，之后转移至融合机中，调节转速为2000rpm，刀具间隙宽度为0.1cm，融合2h，将融合产物转移至高温箱式炉中，通入氮气保护气体，升温至500℃进行烧结，烧结时间为12h，之后冷却至室温，进行粉碎、筛分、除磁，得到所述硅基复合材料。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为44％，多孔纳米硅的质量分数为37％。
实施例7
除了多孔纳米硅、石墨和有机溶剂的混合过程中加入正十八酸外，其他参数和条件与实施例1相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为24.5％，多孔纳米硅的质量分数为60.1％。
实施例8
除了多孔纳米硅、石墨和有机溶剂的混合过程中加入十二烷基苯磺酸钠外，其他参数和条件与实施例1相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为25.2％，多孔纳米硅的质量分数为61％。
实施例9
除了调整球磨和盐酸腐蚀的条件使得所得多孔纳米硅的中值粒径为240nm，孔隙率为59％，比表面积为230m 2/g，其他条件和参数与实施例1中相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为25％，多孔纳米硅的质量分数为60％。
实施例10
除了调整球磨和盐酸腐蚀的条件使得所得多孔纳米硅的中值粒径为190nm，孔隙率为63％，比表面积为280m 2/g，其他条件和参数与实施例1中相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅、片状石墨及外表面的碳包覆层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为25％，多孔纳米硅的质量分数为61.1％。
实施例11
除了调整采用的石墨为多孔石墨，石墨中的孔径较多孔纳米硅的粒径大10％，孔隙率为50％外，其他条件和参数与实施例1中相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅、多孔石墨及外表面的碳包覆层，多孔石墨的孔道中内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，多孔石墨的质量分数为24.1％，多孔纳米硅的质量分数为60.9％。
实施例12
除了调整采用的石墨为多孔石墨，石墨中的孔径较多孔纳米硅的粒径大50％，孔隙率为10％外，其他条件和参数与实施例1中相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅、多孔石墨及外表面的碳包覆层，多孔石墨的孔道中内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，多孔石墨的质量分数为24％，多孔纳米硅的质量分数为59.8％。
实施例13
除了在将多孔纳米硅、石墨及有机溶剂混合前对多孔纳米硅进行表面镀层处理，在多孔纳米硅表面形成厚度为5nm的硅化镁层外，其他方法和条件与实施例1相同。
本实施例所得的硅基复合材料中，包括多孔纳米硅，片状石墨及外表面的碳包覆层，多孔纳米硅表面形成有硅化镁层，片状石墨的层间内嵌有多孔纳米硅。以硅基复合材料的质量为100％计，片状石墨的质量分数为25％，多孔纳米硅的质量分数为58％，硅化镁的质量分数为1.5％。
对比例1
除了将多孔纳米硅替换为等粒径的纳米硅，其他方法和条件与实施例1相同。
对比例2
除了直接将多孔纳米硅作为前驱体与酚醛树脂按质量比60:30进行配比，进行碳包覆外，其他参数和条件与实施例1相同。
对比例3
除了直接将多孔纳米硅120作为前驱体与葡萄糖按质量比60:55进行配比，进行碳包覆外，其他参数和条件与实施例1相同。
性能测试：
I.样品的X射线衍测定
X射线衍射仪：厂家：荷兰帕纳科，型号：X′pert PRO；
X射线衍射仪设置参数为：发散狭缝D.S.：1.0°，扫描范围：10°～90°；防散射狭缝S.S.：1.0°，扫描速度(Scan Step)：0.02°；接收狭缝：0.4S.S./mm，扫描模式：步进扫描，电压：40kV，每步积分时间：2s，电流：40mA，扫描时间：2小时13分20秒；
采用以上仪器和参数对本公开的制备获得的硅基复合材料的进行X射线衍射测定。
II.比表面积测试
比表面积(m 2/g)：《硅炭》GB/T 38823-2020；
III.锂离子电池制作:
如附图16和17的阴极以及电池的示意图所示，分别将上述实施例1-13、对比例1-3中获得硅基复合材料100以及导电剂(super P)和粘结剂(丁苯橡胶：羧甲基纤维素钠＝1：1(质量比))按照质量比94:1:5的配比溶剂在溶剂水中混合，控制固含量在50％，涂覆于铜箔集流体242上，真空烘干，将干燥后的极片冲裁成16mm直径的圆，制得负极240极片，负极240极片上层形成负极活性材料层244；然后将传统成熟工艺制备的三元正极220极片、1mol/L的(LiPF 6/EC(碳酸乙酯):DMC(碳酸二甲酯):EMC(碳酸甲乙酯)＝1:1:1(体积比))电解液260、Celgard2400隔膜280、外壳290(采用常规生产工艺装配18650圆柱单体电池)，在充满氩气的手套箱中组装得到电池。
其中，三元正极220极片的制备如下：正极(NCM523)、导电剂(SP：KS-6)、粘结剂(solef5130-PVDF)按照质量比NCM：solef5130-PVDF：SP：KS-6＝96.8：1.2：1.0：1.0比例溶解在NMP中，固含量控制在50％，然后涂敷在Al箔集流体上，真空干燥、获得正极片。
IV.电化学循环性能测试：
(1)首次可逆比容量(mAh/g)：(即首次放电比容量，Q 1(dis))，由武汉金诺电子有限公司LAND电池测试系统测定得出数据；
(2)首次库伦效率(％)：
首次库伦效率E 1＝Q 1(dis)/Q 1(cha)×100％  (公式1)
Q 1(dis)：以0.1C倍率电流充放电时首次放电比容量，(mAh/g)；
C 1(dis)：以0.1C倍率电流充放电时首次放电容量，(mAh)；
Q 1(cha)：以0.1C倍率电流充放电时首次充电比容量，(mAh/g)；
C 1(cha)：以0.1C倍率电流充放电时首次充电容量，(mAh)；
m：活性物质质量，(g)；
(参照《硅炭》GB/T 38823-2020的公式D.3)；
(3)150次循环容量保持率(％)：
150次循环容量保持率(％)＝第150次的放电比容量/首次放电比容量×100％  (公式2)
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(CT2001A)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。测定充电比容量、放电比容量、放电容量以及库伦效率等。
(4)150周极片膨胀率(％)：
150周极片膨胀率(％)t＝(D2-D1)/D1×100％  (公式3)
使用万分尺测试冲裁为圆形的极片，测试其厚度，计为D1微米。然后将极片组装成为电池，放置于武汉金诺电子有限公司LAND电池测试系统(CT3001K)上，在常温条件，0.2C恒流充放电，充放电电压限制在0.005～1.5V，完成一次充电和一次放电计为1个循环，循环150周后，将电池在手套箱中拆解，取出负极240极片，用万分尺测试极片的厚度，计为D2微米。极片的膨胀率t根据公式3计算，获得所述的膨胀率大小参数。
V、测试结果图3和图7分别为本公开实施例3和实施例1中硅基复合材料的X射线衍射图。
图4和图8分别为实施例3和实施例1中首次充放电曲线，由图4和图8分别可以看出本实施例3和1所述硅基复合材料的首次充放电容量较高，且首次库伦效率也较高。图5和图9分别对应为实施例3和实施例1循环性能测试曲线，由图5和图9可以看出本实施例3和1中所述硅基复合材料具有优异的循环 性能，循环150周容量保持率分别为92.5％和90.1％。需要说明的是其他实施例2、4-13在首次充放电容量、首次库伦效率、循环性能上同样获得了同实施例3相近的技术效果。
表1
Figure PCTCN2021088785-appb-000001
由上表1可以看出，本公开所述硅基复合材料具有优异的循环性能和低的膨胀率；对比本公开实施例1、实施例7～8可以看出，本公开所述硅基复合材料100的制备过程中，加入上述分散剂，分散剂作用于多孔纳米硅粒子表面，加强分散效果，其能促使多孔纳米硅进入石墨的层间和/或孔道结构中，形成内嵌结构，且在和石墨结合的时候，更加均匀和紧密，进而降低硅基复合材料的膨胀率，优化循环性能。对比本公开实施例1、实施例11～12可以看出，当采用多孔石墨，所述硅基复合材料具有更低的膨胀率和更优的循环保持率；对比本申请实施例1和实施例13可以看出，当多孔纳米硅表面含有硅化镁层122时，其所述硅基复合材料具有更低的膨胀率和更优的循环保持率。
实施例1和对比例1相比较可以看到，实施例1采用多孔纳米硅120可以避免同等条件下的材料膨胀，改善了材料的膨胀性能，从而提高了电极材料的循环性能等。采用普通的纳米硅粒子，在同等条件下材料的膨胀更大，循环性能也更差。
实施例1和对比例2比较可以看到，实施例1中，由于使用片状石墨作为第二相材料，其相较于二维材料与硅形成的内嵌结构，其表面形成的碳包覆层更加致密，进而有利于避免电解液与硅的接触，提升界面稳定性，制备得到的材料形成内嵌结构，提高了硅碳产品的循环和膨胀性能。而没有使用片状石墨160或者多孔石墨140作为第二相材料，制备得到的材料无法形成内嵌结构，获得硅碳产品的循环和膨胀性能较差。
实施例1与对比例3比较可以看到，在葡萄糖按添加量占比相近的条件下，对比例3同样在没有使用片状石墨160或者多孔石墨140作为第二相材料，制备得到的材料同样无法形成内嵌结构，在首次库伦效 率、循环容量保持率上显著低于实施例1，其循环和膨胀性能上明显差于实施例1制备的硅基复合材料。
申请人声明，本公开通过上述实施例来说明本公开的详细方法，但本公开并不局限于上述详细方法，即不意味着本公开必须依赖上述详细方法才能实施。所属技术领域的技术人员应该明了，对本公开的任何改进，对本公开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，均落在本公开的保护范围和公开范围之内。
工业实用性
综上所述，本公开提供了一种多孔纳米硅基复合材料、负极和锂离子电池以及它们的制备方法。该多孔纳米硅基复合材料具有超低膨胀特性，具有改善锂离子电池的优异循环性能。

Claims (15)

  1. 一种硅基复合材料(100)，所述硅基复合材料(100)包括纳米活性粒子和石墨，所述纳米活性粒子包括多孔纳米硅(120)；
    所述石墨具有孔道结构(142)，所述石墨的孔道结构(142)中内嵌有所述纳米活性粒子，及/或，
    所述石墨具有层状结构(162)，所述石墨的层状结构(162)中内嵌有所述纳米活性粒子。
  2. 根据权利要求1所述的硅基复合材料(100)，其中，所述硅基复合材料(100)中，包括如下特征(1)～(4)至少一项：
    (1)所述纳米活性粒子和所述石墨的质量比为(0.5～80):(10～50)；
    (2)所述硅基复合材料(100)的中值粒径为1μm～40μm；
    (3)所述硅基复合材料(100)的比表面积为1m 2/g～20m 2/g；
    (4)所述硅基复合材料(100)表面形成有碳包覆层(180)。
  3. 根据权利要求1或2所述的硅基复合材料(100)，其中，包括如下特征(1)～(4)至少一项：
    (1)所述多孔纳米硅(120)的中值粒径为1nm～500nm；
    (2)所述多孔纳米硅(120)的比表面积为1m 2/g～500m 2/g；
    (3)所述多孔纳米硅(120)的孔隙率为20％～90％；
    (4)所述多孔纳米硅(120)的孔径为1nm～0.1μm。
  4. 根据权利要求1或2或3所述的硅基复合材料(100)，其中，包括如下特征(1)～(3)至少一项：
    (1)所述纳米活性粒子还包括形成于所述多孔纳米硅(120)的表面的硅化镁层(122)；
    (2)所述硅化镁层(122)的厚度为1nm～100nm；
    (3)以纳米活性粒子的质量为100％计，所述硅化镁层(122)的质量分数为0.5％～10％。
  5. 根据权利要求1～4任一项所述的硅基复合材料(100)，其中，包括如下特征(1)～(7)至少一项：
    (1)所述石墨包括多孔石墨(140)和片状石墨(160)中的至少一种；
    (2)所述石墨的中值粒径为1μm～10μm；
    (3)所述石墨与所述多孔纳米硅(120)的中值粒径之比为(10～40):1；
    (4)所述多孔石墨(140)的孔隙率为10％～50％；
    (5)所述多孔石墨(140)的孔径比所述多孔纳米硅(120)的中值粒径大10％～50％；
    (6)所述片状石墨(160)的层与层之间的层间距为10nm～500nm；
    (7)所述片状石墨(160)的长:宽:厚的比值为(2～20):(0.4～3):(0.1～0.2)。
  6. 一种硅基复合材料(100)的制备方法，其中，包括以下步骤：
    将纳米活性粒子和石墨在有机溶剂中混合使所述石墨的层间和/或孔道中内嵌有所述纳米活性粒子，得到浆料，干燥后得到所述硅基复合材料(100)，所述纳米活性粒子包括多孔纳米硅(120)。
  7. 根据权利要求6所述的方法，其中，所述多孔纳米硅(120)的制备方法包括：将硅合金进行腐蚀，得到所述多孔纳米硅(120)。
  8. 根据权利要求7所述的方法，其中，包括如下特征(1)～(5)至少一项：
    (1)所述硅合金包括铝硅合金、铁硅合金及硅锌合金中的至少一种；
    (2)所述硅合金为亚微米级颗粒；
    (3)所述腐蚀采用的腐蚀剂包括盐酸、氢氟酸、硫酸及磷酸中的至少一种；
    (4)所述腐蚀的时间为0～7h且不包括0；
    (5)所述多孔纳米硅(120)与所述石墨的质量比为(0.5～80):(10～50)。
  9. 根据权利要求6～8任一所述的方法，其中，所述有机溶剂包括芳香烃、氯化烃、醇醚、胺类化合物、酮、醇中的至少一种，优选地，所述醇为R-OH中，R为C1～C11烷基中的至少一种；及/或
    所述分散剂包括含有羧基、磺酸基、氨基基团的表面活性剂中的至少一种。
  10. 根据权利要求6～9任一所述的方法，其中，所述硅基复合材料(100)的制备过程中还包括对所述干燥后得到的产物进行碳包覆；及/或
    所述碳包覆的方法包括：将所述干燥后得到的产物与碳源混合，烧结后得到所述硅基复合材料(100)；及/或
    所述碳源包括糖类、树脂、有机酸、聚合多远醇、烯醇、易石墨化碳材料或混合物中的至少一种。
  11. 根据权利要求6～10任一所述的方法，其中，包括如下特征(1)～(10)至少一项：
    (1)所述有机溶剂包括甲醇、乙醇、丙醇、异丙醇、丁醇、戊醇、丙酮、甲苯、苯乙烯、全氯乙烯、三氯乙烯、乙烯乙二醇醚及三乙醇胺中的至少一种；
    (2)所述浆料的制备方法还包括：将纳米活性粒子、分散剂和石墨在有机溶剂中混合得到所述浆料；
    (3)所述分散剂包括正十八酸、环氧树脂、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、聚氯乙烯及聚乙烯吡咯烷酮中的至少一种；
    (4)所述干燥的方法包括真空干燥、喷雾干燥及旋转蒸发中的至少一种；
    (5)所述硅基复合材料(100)的制备过程中还包括对所述干燥后得到的产物进行碳包覆；
    (6)所述碳包覆的方法包括：将所述干燥后得到的产物与碳源混合，烧结后得到所述硅基复合材料(100)；
    (7)所述碳源包括环氧树脂、柠檬酸、蔗糖、葡萄糖、沥青、酚醛树脂、果糖、聚乙二醇、聚乙烯醇和聚氯乙烯中的至少一种；
    (8)所述烧结的温度为500℃～1500℃，时间为1h～12h；
    (9)所述烧结的温度为800℃～1200℃，时间为3h～10h；
    (10)所述烧结后还包括：将烧结产物粉碎、筛分、除磁，得到所述硅基复合材料(100)。
  12. 根据权利要求6～11任一项所述的方法，其中，所述多孔纳米硅(120)的制备过程中还包括：在所述多孔纳米硅(120)表面形成硅化镁层(122)；及/或
    所述形成硅化镁层(122)的制备方法包括：将所述多孔纳米硅(120)进行表面镀层处理，得到表面形成有硅化镁层(122)的多孔纳米硅(120)；及/或
    所述表面镀层处理的方法包括磁控溅射和真空镀膜中的至少一种。
  13. 根据权利要求6～12任一项所述的方法，其中，包括以下步骤：
    将硅合金进行腐蚀，得到多孔纳米硅(120)，其中，所述硅合金为亚微米级颗粒；
    将所述多孔纳米硅(120)进行表面镀层处理，得到表面形成有硅化镁层(122)的多孔纳米硅(120)；
    将所述表面形成有硅化镁层(122)的多孔纳米硅(120)、有机溶剂、分散剂和石墨混合后得到浆料，干燥后得到前驱体，其中，所述多孔纳米硅(120)与所述石墨的质量比为(0.5～80):(10～50)；及
    将所述前驱体与碳源进行混合，烧结后得到所述硅基复合材料(100)。
  14. 一种负极(240)，包含如权利要求1～5任一项所述的硅基复合材料(100)。
  15. 一种锂离子电池(200)，包含如权利要求1～5任一项所述的硅基复合材料(100)。
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