WO2023217240A1 - 一种空腔定制化碳硅复合材料及其制备方法和应用 - Google Patents

一种空腔定制化碳硅复合材料及其制备方法和应用 Download PDF

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WO2023217240A1
WO2023217240A1 PCT/CN2023/093591 CN2023093591W WO2023217240A1 WO 2023217240 A1 WO2023217240 A1 WO 2023217240A1 CN 2023093591 W CN2023093591 W CN 2023093591W WO 2023217240 A1 WO2023217240 A1 WO 2023217240A1
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carbon
particles
silicon
cavity
customized
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PCT/CN2023/093591
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English (en)
French (fr)
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秦望
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陕西埃普诺新能源科技有限公司
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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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • 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
    • 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
    • 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
    • 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

  • This application relates to the technical field of negative electrode materials for lithium ion batteries, to a carbon-silicon composite material and its preparation method and application, and in particular to a cavity-customized carbon-silicon composite material and its preparation method and application.
  • Silicon with extremely high charge-discharge specific capacity, is a lithium-ion battery negative active material that can replace graphite and has great industrialization prospects.
  • silicon is accompanied by huge volume changes during the charge and discharge process, and the mechanical stress generated causes the active material to pulverize, the structure collapses, and the material is separated from the current collector, resulting in rapid capacity attenuation and reduced cycle performance.
  • due to this volume expansion effect it is difficult for silicon to form a stable solid electrolyte interface film in the electrolyte, resulting in reduced charge and discharge efficiency and accelerated deterioration of cycle performance.
  • cavities such as egg yolk-eggshell (Liu, N. et al. A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes. Nature Nanotechnology 2014, 9, 187), etc.
  • the purpose of the present invention is to overcome the above-mentioned defects of the existing technology and provide a cavity-customized carbon-silicon composite material and its preparation method and application.
  • the gradient integrated three-phase coated carbon structure can not only buffer the volume expansion effect of silicon particles, but also has a more stable structure, maximizing volume capacity and energy density while effectively improving cycle stability.
  • the present invention provides a cavity-customized carbon-silicon composite material, which includes a core structure and a third-phase carbon coating layer covering the core structure.
  • the core structure is formed by removing the first intermediate product particles.
  • the core structure has a customized cavity formed after the pore-forming agent particles are removed.
  • the first intermediate product particles are composed of silicon particles, the pore-forming agent particles, and the first Composite particles formed by phase carbon and second phase carbon;
  • the first phase carbon is a carbon nanomaterial with a network structure
  • the second phase carbon is a carbon substance of an organic compound
  • the third phase carbon is carbon material of tar and/or pitch.
  • the present invention provides a method for preparing the above-mentioned cavity customized carbon-silicon composite material, which includes the following processes:
  • precursor solution is spray-dried to obtain precursor particles, which are mixture particles of the silicon particles, the first phase carbon, the pore-forming agent particles and the organic compound;
  • the precursor particles are subjected to a first heat treatment in a non-oxidizing atmosphere, so that the organic compound is derived into a carbon substance to form a second phase of carbon, and the first intermediate product particles are obtained;
  • the second intermediate product particles are subjected to a second heat treatment in a non-oxidizing atmosphere to convert the tar and/or asphalt into carbon substances to form a third phase carbon coating layer to obtain third intermediate product particles;
  • the pore-forming agent particles in the third intermediate product particles are removed with water to obtain the cavity-customized carbon-silicon composite material.
  • the present invention provides the above-mentioned cavity customized carbon-silicon composite material or the cavity-customized carbon-silicon composite material prepared by the above-mentioned preparation method, which can be used as an anode active material, anode, an electrochemical energy storage device or an electrochemical storage device. applications in energy systems.
  • the present invention can form accurately predetermined customized cavities.
  • the cavities can provide buffer space for the expansion of silicon particles to avoid structural collapse and surface interface instability problems.
  • the cavities can provide buffer space for the expansion of silicon particles and avoid structural collapse and surface instability problems.
  • pore-forming agents to form customized cavities, a suitable cavity can be formulated according to the expansion volume of silicon particles to avoid cavities that are too large or too small. If a cavity is too small, there will still be risks of structural collapse and surface instability. If the cavity is too large, the volumetric specific capacity and volumetric energy density will be sacrificed.
  • the present invention uses continuous three-phase carbon of different materials and internal flexible carbon nanomaterials with a network structure to coat the silicon particles, which can better absorb the expansion tension of the silicon particles and maintain the stability of the structure.
  • the outermost layer The coating layer generated by high-temperature carbonization of tar or asphalt has better heat resistance, acid and alkali resistance, and impact resistance, which can make the structure more stable.
  • the carbon material derived from the organic compound in the middle serves as the first phase to connect
  • the bridging role of carbon and third-phase carbon enables the carbon structure to form a gradient integrated carbon structure from "soft" to "rigid” from the inside to the outside, which not only provides a continuous carbonaceous electron transmission channel, but also makes the particle structure more stable , which maximizes volume capacity and energy density while effectively improving cycle stability, which is conducive to its application as an anode active material in lithium-ion batteries.
  • the carbon-silicon composite material of the present invention is very suitable for lithium-ion battery electrode active materials that are restricted by volume expansion, and the silicon-based battery produced has excellent charge-discharge volume specific capacity and cycle stability.
  • the preparation method of the present invention not only has low cost, simple process, safety and low energy consumption, but is also compatible with industrial equipment and can realize large-scale production.
  • Figure 1 is a schematic structural diagram of a cavity-customized carbon-silicon composite material according to a specific embodiment of the present invention, which shows a partial enlarged structural view of a single-particle interface in the cavity-customized carbon-silicon composite material.
  • Figure 2 is a schematic structural diagram of the carbon-silicon composite material prepared in Comparative Example 1 or Comparative Example 2, which shows a partial enlarged structural diagram of the single-particle interface in the carbon-silicon composite material.
  • Figure 3 is a scanning electron microscope photograph of spray-dried composite particles during the preparation process of a cavity-customized carbon-silicon composite material according to a specific embodiment of the present invention.
  • Figure 4 is a scanning electron microscope photo of heat-treated composite particles during the preparation process of the cavity-customized carbon-silicon composite material of the present invention.
  • Figure 5 is a low-magnification scanning electron microscope photograph of a cavity-customized carbon-silicon composite material produced in a specific embodiment of the present invention.
  • Figure 6 is a high-magnification scanning electron microscope photograph of a cavity-customized carbon-silicon composite material produced in a specific embodiment of the present invention.
  • Figure 7 is a scanning electron microscope photograph of the composite particles of the first heat treatment during the preparation of the carbon-silicon composite material of Comparative Example 2.
  • Figure 8 is a scanning electron microscope photograph of the carbon-silicon composite material prepared in Comparative Example 2.
  • the present invention discloses a cavity-customized carbon-silicon composite material, the structural schematic diagram of which is shown in Figure 1.
  • the figure shows a local enlarged structure of a single particle interface in the cavity-customized carbon-silicon composite material.
  • the cavity-customized carbon-silicon composite material of the present invention includes a core structure and a third-phase carbon coating layer covering the core structure.
  • the core structure is a structure formed by removing the pore-forming agent particles from the first intermediate product particles.
  • the core structure has A customized cavity formed after the removal of pore-forming agent particles.
  • the first intermediate product particles are composite particles formed by silicon particles, pore-forming agent particles, first-phase carbon and second-phase carbon; the first-phase carbon is composed of Carbon nanomaterials with a network structure; the second phase carbon is a carbon substance derived from organic compounds; the third phase carbon is a carbon substance coating layer converted from tar and/or asphalt.
  • the customized cavity can be uniformly and accurately predetermined and constructed by introducing pore-forming agent particles according to the volume expansion of the silicon particles (for example, the customized cavity in Figure 1 can accommodate 300% of the volume expansion of silicon).
  • the cavities can provide buffer space for the expansion of silicon particles to avoid structural collapse and surface interface instability problems.
  • the cavities can
  • pore-forming agents to form customized cavities, a suitable cavity can be formulated according to the expansion volume of silicon particles to avoid cavities that are too large or too small. If a cavity is too small, there will still be risks of structural collapse and surface instability. If the cavity is too large, the volumetric specific capacity and volumetric energy density will be sacrificed.
  • the internal flexible carbon nanomaterials with a network structure coat the silicon particles, which can better absorb the expansion tension of the silicon particles and maintain the stability of the structure.
  • the outermost layer is made of tar or asphalt.
  • the coating layer generated after high-temperature carbonization has better heat resistance, acid and alkali resistance, and impact resistance, which can make the structure more stable.
  • the carbon material derived from the organic compound in the middle serves to connect the first phase carbon and the third phase.
  • the bridging role of carbon causes the outer-coated carbon structure to form a gradient integrated carbon structure from "soft" to "rigid” from the inside to the outside, which not only provides a continuous carbonaceous electron transmission channel, but also makes the particle structure more stable.
  • the carbon-silicon composite material of the present invention is entirely composed of silicon active materials and lightweight carbon materials. There are no other auxiliary materials, and the relative content of silicon and the weight specific capacity of the material can be increased as much as possible.
  • the carbon-silicon composite material of the present invention is very suitable for lithium-ion battery electrode active materials that are restricted by volume expansion, and the silicon-based battery produced has excellent charge-discharge volume specific capacity and cycle stability.
  • the mass percentage of silicon particles is 50%-99%, for example, 50%, 55%, 60%, 62.5 %, 65%, 68%, 72%, 75%, 77%, 78%, 80%, 83%, 85%, 87.5%, 90%, 91%, 93%, 95%, 96.5%, 98% or 99% etc.
  • the mass percentage of the first phase carbon is 0.1%-49%
  • the mass percentage of the second phase carbon is 0.1%-49%
  • the mass percentage of three-phase carbon is 0.1%-49%.
  • the silicon particles include one or more of micron-sized silicon particles, nano-sized silicon particles, silicon nanowires and silicon nanotubes.
  • Micron-level silicon particles can specifically be micron-level silicon of 1 micron to 20 microns
  • nano-level silicon particles can be nano-level silicon particles of 1 nanometer to 1000 nanometers
  • silicon nanowires can have a diameter of 1 nanometer to 1000 nanometers and a length of 10 Nano to 10 microns
  • the diameter of silicon nanotubes can be 1 nanometer to 1000 nanometers
  • the length is 10 nanometers to 10 microns.
  • the silicon particles can be silicon particles of different sizes.
  • the silicon particles are not limited to the silicon particles listed above, and other silicon particles commonly used in this field can also be used in the present invention.
  • the carbon nanomaterials include one of carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, nanocarbon fibers, bacterial cellulose carbon fibers, and bacterial cellulose carbon cilia, or Two or more types.
  • the organic compound includes one or more of ascorbic acid, citric acid, glucose, sucrose, fructose, maltose, chitosan, urea, starch and protein.
  • ascorbic acid, citric acid glucose, sucrose, fructose, maltose, chitosan, urea, starch and protein.
  • typical but non-limiting examples of the mixture are: a mixture of ascorbic acid and sucrose, a mixture of ascorbic acid and glucose, a mixture of sucrose and citric acid, a mixture of fructose, chitosan and urea, ascorbic acid, maltose A mixture of starch, ascorbic acid, sucrose, citric acid and protein, etc.
  • Tar includes coal tar and/or petroleum tar
  • pitch includes coal pitch and/or petroleum pitch.
  • typical but non-limiting examples of the combination include: a combination of petroleum asphalt and petroleum tar, a combination of coal tar and petroleum asphalt, etc.
  • the present invention also provides a method for preparing the above-mentioned cavity customized carbon-silicon composite material, which includes the following processes:
  • the silicon particles and pore-forming agent particles are easily combined with the first phase carbon in the solution.
  • the above-mentioned organic The compound also serves as a dispersant in the present invention to fully and uniformly disperse the silicon particles, first phase carbon, and pore-forming agent particles in the solvent.
  • the solvent is water.
  • the mass percentage of the solvent in the precursor solution is 2% to 99.9%.
  • the pore-forming agent particles are water-soluble salt substances with a melting point between 710°C and 1000°C.
  • the salt substances include sodium chloride (801°C), potassium chloride ( 770°C), calcium chloride (772°C), magnesium chloride (714°C), sodium carbonate (851°C), potassium carbonate (891°C), sodium sulfate (884°C), etc.
  • sodium chloride 801°C
  • potassium chloride 770°C
  • magnesium chloride 714°C
  • sodium carbonate (851°C
  • sodium sulfate (884°C) sodium sulfate
  • the volume ratio of silicon particles to pore-forming agent particles is 1:0.1-9, preferably 1:1-4.
  • precursor particles which are mixture particles of silicon particles, first phase carbon, pore-forming agent particles and organic compounds.
  • spray drying is to atomize the precursor solution into droplets through any one of pressure atomizer, airflow atomizer, rotary atomizer, ultrasonic atomizer, etc., and then dry it. Precursor particles are obtained.
  • the feed rate is 0.5 mL/min-100 mL/min, such as 0.5 mL/min, 1 mL/min, 5 mL/min, 10 mL/min, 20 mL/min, 30 mL/min.
  • the inlet air temperature is 100-300°C, such as 100°C, 150°C, 180°C, 210°C, 250°C, 275°C and 300°C, etc.
  • the outlet air temperature is automatically adjusted by the equipment, and the carrier gas is air.
  • the precursor particles are subjected to a first heat treatment in a non-oxidizing atmosphere to convert the organic compounds into carbon substances to form second phase carbon and obtain the first intermediate product particles.
  • the temperature of the first heat treatment is lower than the melting point of the pore-forming agent particles to avoid melting loss of the pore-forming agent particles at high temperatures and failure of cavity customization.
  • the organic compounds melt and migrate to the particle surface along the gap between the embedded silicon particles and the pore-forming agent particles driven by the thermal expansion of the air inside the particles.
  • the organic compounds denature and interact.
  • the method of the present invention connects the second phase carbon and the first phase carbon through covalent bonds.
  • the temperature of the first heat treatment is 300°C-700°C, such as 300°C, 350°C, 400°C, 425°C, 500°C, 575°C, 650°C, 700°C, etc.
  • the time of the first heat treatment is 1h-24h, for example, 1h, 2h, 3h, 5h, 7h, 10h, 12h, 13h, 15h, 16h, 18h, 20h, 21h, 22h, 23h or 24h, etc.
  • the organic compound-derived carbon layer has been formed on the surface of the first intermediate product particles, and the pore-forming agent particles are not removed at this time, molten tar and/or asphalt will not penetrate into the interior of the particles, thereby achieving the third step.
  • the two-phase carbon is connected to the first-phase carbon
  • the third-phase carbon is connected to the second-phase carbon, which is a gradient structure from the inside out from "soft" to "rigid".
  • coating is performed in a non-oxidizing atmosphere to avoid the introduction of impurities.
  • the first intermediate product particles can be dispersed in molten tar and/or asphalt, and stirred and mixed in a non-oxidizing atmosphere for 1h to 24h, such as 1h, 2h, 3h, 5h, 7h, 10h , 12h, 13h, 15h, 16h, 18h, 20h, 21h, 22h, 23h or 24h, etc.
  • the second intermediate product particles are subjected to a second heat treatment in a non-oxidizing atmosphere to convert tar and/or asphalt into a carbon coating layer to form a third phase carbon coating layer to obtain the third intermediate product particles.
  • the temperature of the second heat treatment is 600°C-1400°C, for example, 600°C, 650°C, 700°C, 725°C, 750°C, 760°C, 780°C, 800°C, 850°C, 880°C, 900°C, 925°C, 950°C, 975°C, 1050°C, 1150°C, 1200°C, 1250°C, 1300°C or 1400°C, etc.
  • the time of the second heat treatment is 1h-24h, for example, 1h, 2h, 3h, 5h, 7h, 10h, 12h, 13h, 15h, 16h, 18h, 20h, 21h, 22h, 23h or 24h, etc.
  • the third intermediate product particles can be washed with water and dried to obtain a cavity-customized carbon-silicon composite material.
  • the non-oxidizing atmosphere in the above steps includes one or more of nitrogen atmosphere, argon atmosphere, hydrogen atmosphere and helium atmosphere.
  • nitrogen atmosphere argon atmosphere
  • hydrogen atmosphere hydrogen atmosphere
  • helium atmosphere typical but non-limiting examples of the combination include: argon/hydrogen mixed atmosphere , helium/hydrogen mixed atmosphere, etc.
  • the above preparation method of the present invention is not only low in cost, simple in process, safe and low in energy consumption, but also compatible with industrial equipment and can achieve large-scale production.
  • the present invention also provides the above-mentioned cavity customized carbon-silicon composite material or the cavity-customized carbon-silicon composite material prepared by the above-mentioned preparation method in anode active material, anode, electrochemical energy storage device or electrochemical energy storage system. applications in.
  • the cavity-customized carbon-silicon composite material When used as a negative electrode active material, the cavity-customized carbon-silicon composite material can be used alone as a negative electrode active material or mixed with other negative electrode active materials. , the amount of cavity customized carbon-silicon composite material is not less than 1% of the total mass of the total negative active material.
  • other negative active materials include artificial graphite, natural graphite, single-walled carbon nanotubes, few-layer carbon nanotubes, multi-walled carbon nanotubes, graphene, reduced graphene oxide, hard carbon materials, and materials that can occur with lithium Metals and their precursors for alloying reactions (tin, germanium, aluminum, cobalt, etc.), transition metal compounds that can undergo transformation reactions with lithium (iron oxide, etc.), and lithium-embedded transition metal oxides (lithium titanate, etc.).
  • the negative active material may be a lithium ion battery negative active material.
  • the negative electrode When the cavity-customized carbon-silicon composite material is applied to the negative electrode, the negative electrode includes the above-mentioned cavity-customized carbon-silicon composite material as the negative electrode active material.
  • the negative electrode may be, for example, a lithium-ion battery negative electrode.
  • the electrochemical energy storage device or electrochemical energy storage system includes the above-mentioned cavity-customized carbon-silicon composite material.
  • the "electrochemical energy storage device or electrochemical energy storage system” mentioned in the present invention can be, for example, a lithium-ion battery, a capacitor, etc.
  • the particle size of the obtained cavity customized carbon-silicon composite material is about 5 ⁇ m, and the results are shown in Figures 5 and 6; among them, based on the total mass of the cavity customized carbon-silicon composite material, the mass percentage of silicon is 99 %.
  • the cavity-customized carbon-silicon composite material of this embodiment is used as the negative active material.
  • the negative active material, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black are evenly mixed in N-methylpyrrolidone (NMP). Mix and prepare a slurry, then apply it on the copper foil current collector, dry it under vacuum at 120°C for 12 hours, and then roll it to form a negative electrode piece.
  • NMP N-methylpyrrolidone
  • the negative electrode piece was used as the test electrode, and the metal lithium foil was used as the counter electrode.
  • the electrolyte was 1M LiPF6/EC:DEC (1:1; v/v) with added FEC, that is, ethylene carbonate and diethyl carbonate dissolved with lithium hexafluorophosphate.
  • FEC ethylene carbonate and diethyl carbonate dissolved with lithium hexafluorophosphate.
  • a mixed solution of esters with a Celgard 2400 separator was assembled into a coin-type lithium-ion battery in a glove box with an oxygen and water content of less than 1 ppm.
  • the coin-type lithium-ion battery has a specific capacity of up to 2150 mAh/ cm3 and can be cycled stably for 550 times.
  • the cavity-customized carbon-silicon composite material of this embodiment is used as the negative active material to prepare a negative electrode and is further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery are the same as in Example 1.
  • the coin-type lithium-ion battery has a specific capacity of up to 1875 mAh/ cm3 and can be stably cycled 465 times.
  • the cavity-customized carbon-silicon composite material of this embodiment is used as the negative active material to prepare a negative electrode and is further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery are the same as in Example 1.
  • the coin-type lithium-ion battery has a specific capacity of up to 1560 mAh/ cm3 and can be stably cycled 510 times.
  • the cavity customized carbon-silicon composite material is obtained; the particle size of the customized carbon-silicon composite material is about 10 ⁇ m; among them, based on the total mass of the cavity customized carbon-silicon composite material, the mass percentage of silicon particles is 75% .
  • the cavity-customized carbon-silicon composite material of this embodiment is used as the negative active material to prepare a negative electrode and is further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery are the same as in Example 1.
  • the coin-type lithium-ion battery has a specific capacity of up to 1750 mAh/ cm3 and can be stably cycled 460 times.
  • the cavity-customized carbon-silicon composite material of this embodiment is used as the negative active material to prepare a negative electrode and is further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery are the same as in Example 1.
  • the coin-type lithium-ion battery has a specific capacity of up to 1680 mAh/ cm3 and can be stably cycled 480 times.
  • the cavity-customized carbon-silicon composite material of this embodiment is used as the negative active material to prepare a negative electrode and is further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery are the same as in Example 1.
  • the coin-type lithium-ion battery has a specific capacity of up to 2050 mAh/ cm3 and can be cycled stably for 525 times.
  • Comparative Example 1 did not use pore-forming agent particles. The details are as follows:
  • Carbon-silicon composite particles disperse the porous particles in molten petroleum asphalt (mass ratio is 1:0.1), stir in a modified mixer under a nitrogen atmosphere for 6 hours, and further program the temperature to 250°C and 550°C in a nitrogen atmosphere. and 850°C for 2 hours each, then cooled to room temperature, washed and dried with deionized water to obtain the cavity non-customized carbon-silicon composite material; the particle size of the obtained non-customized carbon-silicon composite material is about 3.5 ⁇ m; among them, carbon Based on the total mass of silicon composite materials, the mass percentage of silicon particles is 92%.
  • FIG. 2 The schematic structural diagram of the carbon-silicon composite material of this comparative example is shown in Figure 2, which shows a partial enlarged structural view of the single-particle interface in the carbon-silicon composite material, where 2 represents the carbon-silicon composite material and 20 represents non-customized For pores, 21 represents silicon and 22 represents carbon.
  • 2 represents the carbon-silicon composite material and 20 represents non-customized For pores
  • 21 represents silicon
  • 22 represents carbon.
  • the carbon-silicon composite material of this comparative example was used as the negative active material to prepare a negative electrode and was further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery were the same as in Example 1.
  • Carbon-silicon composite particles (Figure 7); disperse the particles in molten petroleum asphalt, stir for 6 hours under a nitrogen atmosphere in a modified mixer, and further heat up to 250°C, 550°C, and 850°C in a nitrogen atmosphere. After 2 hours, it was cooled to room temperature, washed and dried with deionized water to obtain a non-cavity customized carbon-silicon composite material (Figure 8); the particle size of the obtained carbon-silicon composite material was about 4 ⁇ m; among them, the total mass of the carbon-silicon composite material As a benchmark, the mass percentage of silicon particles is 95%.
  • FIG. 2 The schematic structural diagram of the carbon-silicon composite material of this comparative example is shown in Figure 2, which shows a partial enlarged structural view of the single-particle interface in the carbon-silicon composite material, where 2 represents the carbon-silicon composite material and 20 represents non-customized For pores, 21 represents silicon and 22 represents carbon.
  • the pores inside the particles are random and cannot provide accurate and necessary space for the volume expansion of the silicon particles.
  • the carbon-silicon composite material of this comparative example was used as the negative active material to prepare a negative electrode and was further assembled to obtain a battery.
  • the method and conditions for preparing the negative electrode and battery were the same as in Example 1.

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Abstract

本申请公开了一种空腔定制化碳硅复合材料及其制备方法和应用，空腔定制化碳硅复合材料，包括核结构和包覆所述核结构的第三相碳包覆层，所述核结构为第一中间产物颗粒脱除造孔剂颗粒后形成的结构，所述核结构具有所述造孔剂颗粒脱除后形成的定制化空腔，所述第一中间产物颗粒是由硅颗粒、所述造孔剂颗粒、第一相碳和第二相碳形成的复合物颗粒；所述第一相碳为具有网络结构的碳纳米材料；所述第二相碳为有机化合物衍生的碳物质；所述第三相碳为焦油和/或沥青转化的碳物质。本发明的空腔定制化碳硅复合材料不仅能缓冲硅颗粒的体积膨胀效应，而且结构更稳定，最大化体积容量及能量密度的同时有效提升循环稳定性。

Description

一种空腔定制化碳硅复合材料及其制备方法和应用 技术领域
本申请涉及锂离子电池负极材料技术领域，涉及一种碳硅复合材料及其制备方法和应用，尤其涉及一种空腔定制化碳硅复合材料及其制备方法和应用。
 背景技术
硅，具有极高的充放电比容量，是一种可代替石墨的、极具产业化前景的锂离子电池负极活性材料。然而，硅在充放电过程中伴有巨大的体积变化，产生的机械应力导致活性材料粉化、结构崩塌及材料与集流体脱离，造成容量迅速衰减和循环性能降低。此外，由于这种体积膨胀效应，硅在电解液中难以形成稳定的固体电解质界面膜，导致充放电效率减低，加速循环性能的恶化。将硅材料纳米结构化、进而与碳（纳米）材料结合构筑复合材料，尤其是，构筑内含空腔的硅-碳核壳复合结构（比如，蛋黄-蛋壳（Liu, N. et al. A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes. Nature Nanotechnology 2014, 9, 187）等），可在一定程度上同时解决硅在充放电过程中由于体积膨胀效应引起的结构及表界面不稳定性问题，从而改善其充放电循环性能。
 技术问题
然而，在绝大多数情况下，现有复合方法严重依赖于高含量的非活性辅材、大幅减低硅的相对含量及材料的重量比容量；与此同时，复合方法往往无法实现颗粒内空腔的均匀、精准构建。通常的空腔模板（如，二氧化硅层，二氧化硅颗粒等）或使预留空腔过大，牺牲体积比容量及体积能量密度，或使预留空腔过小导致体积效应犹存、降低循环稳定性。此外，现有复合结构中，空腔构建往往导致硅相与碳相处于一种不稳定的“点”或不高效的“线”接触模式。另外，这类复合材料制备依赖于高危险性的甲硅烷等气态硅源，或成本高昂的结构化纳米硅，或氢氟酸等高腐蚀性化学试剂，或苛刻耗能复杂的工艺。综上，材料结构和制备方法均严重制约该类材料性能发挥和实际应用。
 技术解决方案
本发明的目的在于克服现有技术存在的上述缺陷，提供一种空腔定制化碳硅复合材料及其制备方法和应用，通过定制化空腔和由内到外的从“柔”到“刚”的梯度式一体化三相包覆碳结构，不仅能缓冲硅颗粒的体积膨胀效应，而且结构更稳定，最大化体积容量及能量密度的同时有效提升循环稳定性。
为实现上述目的，本发明的技术方案如下：
第一方面，本发明提供一种空腔定制化碳硅复合材料，包括核结构和包覆所述核结构的第三相碳包覆层，所述核结构为第一中间产物颗粒脱除造孔剂颗粒后形成的结构，所述核结构具有所述造孔剂颗粒脱除后形成的定制化空腔，所述第一中间产物颗粒是由硅颗粒、所述造孔剂颗粒、第一相碳和第二相碳形成的复合物颗粒；
所述第一相碳为具有网络结构的碳纳米材料；
所述第二相碳为有机化合物的碳物质；
所述第三相碳为焦油和/或沥青的碳物质。
第二方面，本发明提供一种上述空腔定制化碳硅复合材料的制备方法，包括以下过程：
将硅颗粒、第一相碳、造孔剂颗粒、有机化合物分散于溶剂中，得到前驱体溶液；其中，所述造孔剂颗粒为可溶于水的盐类物质，所述第一相碳为具有网络结构的碳纳米材料，
将所述前驱体溶液进行喷雾干燥，得到前驱体颗粒，所述前驱体颗粒为所述硅颗粒、所述第一相碳、所述造孔剂颗粒和所述有机化合物的混合物颗粒；
将所述前驱体颗粒在非氧化气氛下进行第一次热处理，使所述有机化合物衍生为碳物质，形成第二相碳，得到第一中间产物颗粒；
将所述第一中间产物颗粒用熔融态焦油和/或沥青进行包覆，得到第二中间产物颗粒；
将所述第二中间产物颗粒在非氧化气氛下进行第二次热处理，使所述焦油和/或沥青转化为碳物质，形成第三相碳包覆层，得到第三中间产物颗粒；
用水脱除所述第三中间产物颗粒中的所述造孔剂颗粒，得到所述空腔定制化碳硅复合材料。
第三方面，本发明提供了一种上述空腔定制化碳硅复合材料或上述制备方法制得的空腔定制化碳硅复合材料在负极活性材料、负极、电化学储能器件或电化学储能系统中的应用。
 有益效果
实施本发明实施例，将具有如下有益效果：
（1）本发明通过使用造孔剂颗粒，可以形成精确预定的定制化空腔，一方面，空腔可以为硅颗粒的膨胀提供缓冲空间，避免结构坍塌及表界面不稳定性问题，另一方面，通过造孔剂形成定制化空腔，可以根据硅颗粒的膨胀体积制定适合的空腔，避免空腔过大或过小，空腔过小仍有结构坍塌及表界面不稳定的风险，空腔过大会牺牲体积比容量及体积能量密度。
（2）本发明通过采用不同材料的连续三相碳，内部柔性的具有网络结构的碳纳米材料包覆硅颗粒，能更好的吸收硅颗粒的膨胀张力，保持结构的稳定性，最外层的由焦油或沥青高温碳化后生成的包覆层具有较佳的耐热性、耐酸碱性以及抗冲击性，能使结构更稳定，中间的有机化合物衍生的碳物质起到连接第一相碳和第三相碳的桥梁作用，使碳结构形成由内到外的从“柔”到“刚”的梯度式一体化碳结构，不仅提供连续碳质电子传输通道，而且使颗粒结构更稳定，最大化体积容量及能量密度的同时有效提升循环稳定性，有利于其作为负极活性材料应用于锂离子电池。
本发明的碳硅复合材料非常适合受体积膨胀牵制的锂离子电池电极活性材料，制得的硅基电池具有优异的充放电体积比容量和循环稳定性。
本发明的制备方法不仅成本低廉、工艺简单、安全、能耗低，而且与工业化装备兼容，可实现规模化生产。
 附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，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的附图。
其中：
图1是本发明一具体实施例的空腔定制化碳硅复合材料的结构示意图，其中给出了空腔定制化碳硅复合材料中的单颗粒界面处的局部放大结构图。
图2是对比例1或对比例2制得的碳硅复合材料的结构示意图，其中给出了碳硅复合材料中的单颗粒界面处的局部放大结构图。
图3是本发明一具体实施例的空腔定制化碳硅复合材料制备过程中喷雾干燥的复合微粒的扫描电镜照片。
图4是本发明的空腔定制化碳硅复合材料制备过程中热处理的复合微粒的扫描电镜照片。
图5是本发明一具体实施例制得的空腔定制化碳硅复合材料的低倍扫描电镜照片。
图6是本发明一具体实施例制得的空腔定制化碳硅复合材料的高倍扫描电镜照片。
图7是对比例2的碳硅复合材料制备过程中第一次热处理的复合微粒的扫描电镜照片。
图8是对比例2制得的碳硅复合材料的扫描电镜照片。
 本发明的实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
第一方面，本发明公开了一种空腔定制化碳硅复合材料，其结构示意图如图1所示，图中给出了空腔定制化碳硅复合材料中单个颗粒界面处的局部放大结构图，其中，1代表空腔定制化碳硅复合材料，10代表定制化空腔，11代表硅颗粒，12代表第一相碳，13代表第二相碳，14代表第三相碳。本发明的空腔定制化碳硅复合材料包括核结构和包覆核结构的第三相碳包覆层，核结构为第一中间产物颗粒脱除造孔剂颗粒后形成的结构，核结构具有造孔剂颗粒脱除后形成的定制化空腔，第一中间产物颗粒是由硅颗粒、造孔剂颗粒、第一相碳和第二相碳形成的复合物颗粒；第一相碳为具有网络结构的碳纳米材料；第二相碳为有机化合物衍生的碳物质；第三相碳为焦油和/或沥青转化的碳物质包覆层。
在本发明中，定制化空腔可根据硅颗粒的体积膨胀引入造孔剂颗粒进行均匀、精确的预定及构建（比如，图1中定制化空腔可容纳硅的300%的体积膨胀）。
上述技术方案中，通过使用造孔剂颗粒，可以形成精确预定的定制化空腔，一方面，空腔可以为硅颗粒的膨胀提供缓冲空间，避免结构坍塌及表界面不稳定性问题，另一方面，通过造孔剂形成定制化空腔，可以根据硅颗粒的膨胀体积制定适合的空腔，避免空腔过大或过小，空腔过小仍有结构坍塌及表界面不稳定的风险，空腔过大会牺牲体积比容量及体积能量密度。
通过采用不同材料的连续三相碳，内部柔性的具有网络结构的碳纳米材料包覆硅颗粒，能更好的吸收硅颗粒的膨胀张力，保持结构的稳定性，最外层的由焦油或沥青高温碳化后生成的包覆层具有较佳的耐热性、耐酸碱性以及抗冲击性，能使结构更稳定，中间的有机化合物衍生的碳物质起到连接第一相碳和第三相碳的桥梁作用，使外层包覆的碳结构形成由内到外的从“柔”到“刚”的梯度式一体化碳结构，不仅提供连续碳质电子传输通道，而且使颗粒结构更稳定，最大化体积容量及能量密度的同时有效提升循环稳定性，有利于其作为负极活性材料应用于锂离子电池。另，本发明的碳硅复合材料全部由硅活性材料和轻质碳材料构成，不存在其它辅材，能尽可能的提高硅的相对含量及材料的重量比容量。
本发明的碳硅复合材料非常适合受体积膨胀牵制的锂离子电池电极活性材料，制得的硅基电池具有优异的充放电体积比容量和循环稳定性。
在一具体实施例中，以空腔定制化碳硅复合材料的总质量为100%计，硅颗粒的质量百分含量为50%-99%，例如为50%、55%、60%、62.5%、65%、68%、72%、75%、77%、78%、80%、83%、85%、87.5%、90%、91%、93%、95%、96.5%、98%或99%等。
以空腔定制化碳硅复合材料的总质量为100%计，第一相碳的质量百分含量为0.1%-49%，第二相碳的质量百分含量为0.1%-49%，第三相碳的质量百分含量为0.1%-49%。
在一具体实施例中，硅颗粒包括微米级硅粒子、纳米级硅粒子、硅纳米线和硅纳米管中的一种或两种以上。微米级硅粒子具体可以为1微米~20微米的微米级硅，纳米级硅粒子可以为1纳米~1000纳米的纳米级硅粒子，硅纳米线的直径可以为1纳米~1000纳米，长度为10纳米~10微米，硅纳米管的直径可以为1纳米~1000纳米，长度为10纳米~10微米。硅颗粒可以是不同尺度的硅颗粒。硅颗粒并不限于上述列举的硅颗粒，其他本领域常用的硅颗粒也可用于本发明。
在一具体实施例中，碳纳米材料包括碳纳米管、石墨烯、石墨烯氧化物、还原的石墨烯氧化物、纳米碳纤维、细菌纤维素类碳纤维和细菌纤维素类碳纤毛中的一种或两种以上。
有机化合物包括抗坏血酸、柠檬酸、葡萄糖、蔗糖、果糖、麦芽糖、壳聚糖、尿素、淀粉和蛋白质中的一种或两种以上。当包括两种以上的混合物时，混合物典型但非限制性实例有：抗坏血酸和蔗糖的混合物，抗坏血酸和葡萄糖的混合物，蔗糖和柠檬酸的混合物，果糖、壳聚糖和尿素的混合物，抗坏血酸、麦芽糖和淀粉的混合物，抗坏血酸、蔗糖、柠檬酸和蛋白质的混合物等。
焦油包括煤焦油和/或石油焦油，沥青包括煤沥青和/或石油沥青。当使用两种以上混合物时，组合典型但非限制性实例有：石油沥青和石油焦油的组合，煤焦油和石油沥青的组合等。
第二方面，本发明还提供了一种上述空腔定制化碳硅复合材料的制备方法，包括以下过程：
1）将硅颗粒、第一相碳、造孔剂颗粒、有机化合物分散于溶剂中，得到前驱体溶液；其中，造孔剂颗粒为可溶于水的盐类物质，第一相碳为具有网络结构的碳纳米材料。
在本步骤中，由于第一相碳为具有网络结构的碳纳米材料，具有强吸附性，因此，在溶液中，硅颗粒、造孔剂颗粒易与第一相碳相结合，上述列举的有机化合物在本发明中也作为分散剂，使硅颗粒、第一相碳、造孔剂颗粒充分均匀分散在溶剂中。
在一具体实施例中，溶剂为水。
在一具体实施例中，前驱体溶液中，溶剂的质量百分含量为2%~99.9%。
在一具体实施例中，造孔剂颗粒为熔点在710℃到1000℃之间的可溶于水的盐类物质，具体的，盐类物质包括氯化钠（801℃）、氯化钾（770℃）、氯化钙（772℃）、氯化镁（714℃）、碳酸钠（851℃）、碳酸钾（891℃）、硫酸钠（884℃）等中的一种或两种以上，但并不限于上述列举。
在一具体实施例中，硅颗粒与造孔剂颗粒的体积比为1：0.1～9，优选为1:1~4。
2）将前驱体溶液进行喷雾干燥，得到前驱体颗粒，前驱体颗粒为硅颗粒、第一相碳、造孔剂颗粒和有机化合物的混合物颗粒。
在本步骤中，喷雾干燥是将前驱体溶液通过压力式雾化器、气流式雾化器、旋转式雾化器、超声波雾化器等中的任意一种雾化成液滴，再进行干燥，得到前驱体颗粒。
在一具体实施例中，进料速度为0.5 mL/min-100 mL/min，例如0.5 mL/min、1 mL/min、5 mL/min、10 mL/min、20 mL/min、30 mL/min、35 mL/min、40 mL/min、47.5 mL/min、50 mL/min、60 mL/min、70 mL/min、77 mL/min、80 mL/min、90 mL/min和100 mL/min等，进风温度为100-300℃，例如100℃、150℃、180℃、210℃、250℃、275℃和300℃等，出风温度为设备自动调节，载气为空气。
3）将前驱体颗粒在非氧化气氛下进行第一次热处理，使有机化合物转化为碳物质，形成第二相碳，得到第一中间产物颗粒。
第一次热处理的温度低于造孔剂颗粒的熔点，以避免造孔剂颗粒在高温下的熔化流失及空腔定制的失效。在加热过程中，有机化合物熔融，并在颗粒内部空气受热膨胀的驱动下沿着包埋硅颗粒与造孔剂颗粒之间的间隙向颗粒表面迁移，随着达到热处理温度，有机化合物变性、交联和/或碳化，形成于颗粒表面。本发明的方法使第二相碳与第一相碳之间通过共价键相连接。
在一具体实施例中，第一次热处理的温度为300℃-700℃，例如为300℃、350℃、400℃、425℃、500℃、575℃、650℃、700℃等。第一次热处理的时间为1h-24h，例如为1h、2h、3h、5h、7h、10h、12h、13h、15h、16h、18h、20h、21h、22h、23h或24h等。
4）将第一中间产物颗粒用熔融态焦油和/或沥青进行包覆，得到第二中间产物颗粒。
在本步骤中，由于第一中间产物颗粒的表面已形成有机化合物衍生碳层，且此时未去除造孔剂颗粒，因此，熔融态焦油和/或沥青不会渗入颗粒内部，由此实现第二相碳连接第一相碳、第三相碳连接第二相碳的由内而外的从“柔”至“刚”的梯度结构。
优选的，在非氧化气氛下进行包覆，避免引入杂质。
在本步骤中，具体的，可以将第一中间产物颗粒分散在熔融态焦油和/或沥青中，在非氧化气氛下进行搅拌混合1h~24h，例如1h、2h、3h、5h、7h、10h、12h、13h、15h、16h、18h、20h、21h、22h、23h或24h等。
5）将第二中间产物颗粒在非氧化气氛下进行第二次热处理，使焦油和/或沥青转化为碳包覆层，形成第三相碳包覆层，得到第三中间产物颗粒。
在本步骤中，第二次热处理的温度为600℃-1400℃，例如为600℃、650℃、700℃、725℃、750℃、760℃、780℃、800℃、850℃、880℃、900℃、925℃、950℃、975℃、1050℃、1150℃、1200℃、1250℃、1300℃或1400℃等。第二次热处理的时间为1h-24h，例如为1h、2h、3h、5h、7h、10h、12h、13h、15h、16h、18h、20h、21h、22h、23h或24h等。
6）用水脱除第三中间产物颗粒中的造孔剂颗粒，得到空腔定制化碳硅复合材料。
在本步骤中，可以用水洗涤第三中间产物颗粒，烘干后得到空腔定制化碳硅复合材料。
上述步骤中的非氧化气氛包括氮气气氛、氩气气氛、氢气气氛和氦气气氛中的一种或两种以上，当组合使用时，组合典型但非限制性实例有：氩气/氢气混合气氛，氦气/氢气混合气氛等。
本发明的上述制备方法不仅成本低廉、工艺简单、安全、能耗低，而且与工业化装备兼容，可实现规模化生产。
第三方面，本发明还提供了上述空腔定制化碳硅复合材料或上述制备方法制备的空腔定制化碳硅复合材料在负极活性材料、负极、电化学储能器件或电化学储能系统中的应用。
当空腔定制化碳硅复合材料应用于负极活性材料时，空腔定制化碳硅复合材料可以单独作为负极活性材料，也可以与其他的负极活性材料混合使用，当与其他负极活性材料混合使用时，空腔定制化碳硅复合材料的用量不低于总负极活性材料总质量的1%。
上述“其他的负极活性材料”包括人造石墨、天然石墨、单壁碳纳米管、少层碳纳米管、多壁碳纳米管、石墨烯、还原的氧化石墨烯、硬碳材料、与锂可发生合金化反应的金属及其前体（锡、锗、铝、钴等）、与锂可发生转化反应的过渡金属化合物（氧化铁等）及嵌锂型过渡金属氧化物（钛酸锂等）。
负极活性材料可以是锂离子电池负极活性材料。
当空腔定制化碳硅复合材料应用于负极时，负极包括上述的空腔定制化碳硅复合材料作为负极活性材料，所述负极例如可以是锂离子电池负极。
当空腔定制化碳硅复合材料应用于电化学储能器件或电化学储能系统时，电化学储能器件或电化学储能系统包含上述空腔定制化碳硅复合材料。
本发明所述“电化学储能器件或电化学储能系统”，例如，可以是锂离子电池和电容器等。
以下为具体实施例。
实施例1
制备空腔定制化碳硅复合材料：
将1微米~3微米的硅颗粒与适量浓度的氯化钠、碳纳米管和抗坏血酸的水溶液搅拌混合（质量比：1：3：0.05：0.3），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为15wt%；喷雾干燥时，进料速度为20mL/min，进风温度为220℃，出风温度为110℃，载气为空气；获得的粉体（图3）在550℃氮气气氛下热处理2h，制得抗坏血酸转化的第二相碳于表面的碳硅复合微粒（图4）；将微粒分散于熔化的石油沥青中（质量比：1：0.1），在改性混合机中氮气气氛下搅拌6h，进一步在氮气气氛下依次程序升温至250℃、550℃和850℃各保温2h后冷却至室温，经去离子水洗涤烘干后得到空腔定制化碳硅复合材料；所得的空腔定制化碳硅复合材料的粒度在5μm左右，结果如图5和6所示；其中，以空腔定制化碳硅复合材料总质量为基准，硅的质量百分含量为99%。
制备负极：
采用本实施例的空腔定制化碳硅复合材料作为负极活性材料，将负极活性材料、粘结剂聚偏二氟乙烯（PVDF）、导电剂乙炔黑在N-甲基吡咯烷酮（NMP）中均匀混合配制成浆料，然后将其涂于铜箔集流体上，在120℃真空干燥12h后辊压制成负极极片。
制备电池：
以负极极片为测试电极，以金属锂箔为对电极，电解液是添加FEC的1M LiPF6/EC:DEC（1:1；v/v），即溶解有六氟磷酸锂的碳酸乙烯酯和碳酸二乙酯的混合溶液，隔膜为Celgard 2400，在氧和水含量均小于1ppm的手套箱中组装成纽扣式锂离子电池。
电池性能测试结果：
在0.5C的电流密度下，纽扣式锂离子电池具有高达2150 mAh/cm 3的比容量，可稳定循环550次。
实施例2
制备空腔定制化碳硅复合材料：
将3微米~5微米的硅与适量浓度的硫酸钠、石墨烯氧化物和葡萄糖的水溶液搅拌混合（质量比为1：0.15：0.001：0.5），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为85wt%；喷雾干燥时，进料速度为0.5mL/min，进风温度为100℃，出风温度为80℃，载气为空气；获得的粉体在300℃氢气气氛下热处理24h，制得葡萄糖转化的第二相碳于表面的碳硅复合微粒；将微粒分散于熔化的煤沥青和石油沥青的混合物中（质量比为1：0.1：0.2），在改性混合机中氮气气氛下搅拌24h，进一步在氢气气氛下依次程序升温至250℃、550℃和600℃各保温2h，2h，和24h后冷却至室温，经去离子水洗涤烘干后得到空腔定制化碳硅复合材料；所得的定制化碳硅复合材料的粒度在8μm左右；其中，以空腔定制化碳硅复合材料总质量为基准，硅颗粒的质量百分含量为87%。
采用本实施例的空腔定制化碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，纽扣式锂离子电池具有高达1875 mAh/cm 3的比容量，可稳定循环465次。
实施例3
制备空腔定制化碳硅复合材料：
将1微米~3微米的硅与适量浓度的碳酸钾、还原的氧化石墨烯和淀粉的水溶液搅拌混合（质量比为1：4：0.2：0.5），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为0.1wt%；喷雾干燥时，进料速度为100mL/min，进风温度为300℃，出风温度为160℃，载气为空气；获得的粉体在475℃氩气/氢气气氛下热处理10h，制得淀粉转化的第二相碳于表面的碳硅复合微粒；将微粒分散于石油焦油中（质量比为1：2），在改性混合机中氮气/氩气气氛下搅拌1h，进一步在氩气/氢气气氛下依次程序升温至250℃、550℃和1400℃各保温2h，2h，和1h后冷却至室温，经去离子水洗涤烘干后得到空腔定制化碳硅复合材料；所得的定制化碳硅复合材料的粒度在4μm左右；其中，以空腔定制化碳硅复合材料总质量为基准，硅颗粒的质量百分含量为50%。
采用本实施例的空腔定制化碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，纽扣式锂离子电池具有高达1560 mAh/cm 3的比容量，可稳定循环510次。
实施例4
制备空腔定制化碳硅复合材料：
将3微米~5微米的硅与适量浓度的氯化钾/氯化钠、碳纳米管、尿素和蛋白质的水溶液搅拌混合（质量比为1：0.1：0.1：0.25：0.3：0.2），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为35wt%；喷雾干燥时，进料速度为10mL/min，进风温度为275℃，出风温度为140℃，载气为空气；获得的粉体在700℃氮气气氛下热处理1h，制得尿素和蛋白质转化的第二相碳于表面的碳硅复合微粒；将密封的微粒分散于煤焦油中（质量比为1：0.65），在改性混合机中氩气气氛下搅拌12h，进一步在氩气气氛下依次程序升温至250℃、550℃和1050℃各保温2h，2h和6h后冷却至室温，经去离子水洗涤烘干后得到空腔定制化碳硅复合材料；所得的定制化碳硅复合材料的粒度在10μm左右；其中，以空腔定制化碳硅复合材料总质量为基准，硅颗粒的质量百分含量为75%。
采用本实施例的空腔定制化碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，纽扣式锂离子电池具有高达1750 mAh/cm 3的比容量，可稳定循环460次。
实施例5
制备空腔定制化碳硅复合材料：
将直径约100纳米的硅纳米线与适量浓度的氯化钙/碳酸钠、碳纳米管、石墨烯氧化物、抗坏血酸和柠檬酸的水溶液搅拌混合（质量比为1：4：2：0.5：0.2：0.1：0.2），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为55wt%；喷雾干燥时，进料速度为5mL/min，进风温度为165℃，出风温度为100℃，载气为空气；获得的粉体在650℃氩气气氛下热处理4h，制得抗坏血酸和柠檬酸转化的碳密封的碳硅复合微粒；将密封的微粒分散于熔化的煤沥青中（质量比为1：1），在改性混合机中氮气气氛下搅拌18h，进一步在氢气气氛下依次程序升温至250℃、550℃和750℃各保温2h，2h和15h后冷却至室温，经去离子水洗涤烘干后得到空腔定制化碳硅复合材料；所得的定制化碳硅复合材料的粒度在7μm左右；其中，以空腔定制化碳硅复合材料总质量为基准，硅颗粒的质量百分含量为65%。
采用本实施例的空腔定制化碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，纽扣式锂离子电池具有高达1680 mAh/cm 3的比容量，可稳定循环480次。
实施例6
制备空腔定制化碳硅复合材料：
将50纳米的硅纳米粒子与适量浓度的氯化钠、碳纳米管和抗坏血酸的水溶液搅拌混合（质量比为1：2：0.5：0.5），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为2wt%；喷雾干燥时，进料速度为65mL/min，进风温度为255℃，出风温度为120℃，载气为空气；获得的粉体在420℃氩气/氮气气氛下热处理16h，制得葡萄糖转化的第二相碳于表面的碳硅复合微粒；将密封的微粒分散于熔化的石油沥青中（质量比为1：0.15），在改性混合机中氮气气氛下搅拌3h，进一步在氢气气氛下依次程序升温至250℃、550℃和1200℃各保温2h、2h和4h后冷却至室温，经去离子水洗涤烘干后得到空腔定制化碳硅复合材料；所得的定制化碳硅复合材料的粒度在6μm左右；其中，以空腔定制化碳硅复合材料总质量为基准，硅颗粒的质量百分含量为95%。
采用本实施例的空腔定制化碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，纽扣式锂离子电池具有高达2050 mAh/cm 3的比容量，可稳定循环525次。
对比例1
对比例1与实施例1相比，未使用造孔剂颗粒。具体的如下：
将1微米~3微米的硅与适量浓度碳纳米管和抗坏血酸的水溶液搅拌混合，作为喷雾干燥的前驱体溶液（质量比为1：0.05：0.3）；该前驱体溶液中，溶质浓度为15wt%；喷雾干燥时，进料速度为10mL/min，进风温度为220℃，出风温度为110℃，载气为空气；获得的粉体在550℃氮气气氛下热处理2h，制得多孔结构的碳硅复合微粒；将多孔微粒分散于熔化的石油沥青中（质量比为1：0.1），在改性混合机中氮气气氛下搅拌6h，进一步在氮气气氛下依次程序升温至250℃、550℃和850℃各保温2h后冷却至室温，经去离子水洗涤烘干后得到空腔非定制化碳硅复合材料；所得的非定制化碳硅复合材料的粒度在3.5μm左右；其中，以碳硅复合材料总质量为基准，硅颗粒的质量百分含量为92%。
本对比例的碳硅复合材料的结构示意图参见图2，图中给出了碳硅复合材料中的单颗粒界面处的局部放大结构图，其中，2代表碳硅复合材料，20代表非定制化孔隙，21代表硅，22代表碳。由图可以看出，第一，在无造孔剂条件下形成多孔微粒，其内部孔隙是随机的，无法为硅颗粒的体积膨胀提供必要的空间；第二，多孔微粒的开放式孔结构导致碳包覆过程中第三相碳的由外而内渗透、形成一种颗粒内外非梯度式一体化碳结构，直接包裹在硅表面。这不仅阻碍甚至限制空隙空间容纳硅颗粒的体积膨胀，还构成一种不稳定的全“刚”性导电网络，其在充放电过程中极易随着硅颗粒的体积膨胀发生裂开及脱落。
采用本对比例的碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，其具有1350 mAh/cm 3的比容量，但仅可循环35次。
对比例2
将1微米~3微米的硅与适量浓度的氯化钠、碳纳米管和抗坏血酸的水溶液搅拌混合（相同于实施例1），作为喷雾干燥的前驱体溶液；该前驱体溶液中，溶质浓度为15wt%；喷雾干燥时，进料速度为20mL/min，进风温度为220℃，出风温度为110℃，载气为空气；获得的粉体在850℃氮气气氛下热处理2h，制得多孔碳硅复合微粒（图7）；将微粒分散于熔化的石油沥青中，在改性混合机中氮气气氛下搅拌6h，进一步在氮气气氛下依次程序升温至250℃、550℃和850℃各保温2h后冷却至室温，经去离子水洗涤烘干后得到非空腔定制化碳硅复合材料（图8）；所得的碳硅复合材料的粒度在4μm左右；其中，以碳硅复合材料总质量为基准，硅颗粒的质量百分含量为95%。
本对比例的碳硅复合材料的结构示意图参见图2，图中给出了碳硅复合材料中的单颗粒界面处的局部放大结构图，其中，2代表碳硅复合材料，20代表非定制化孔隙，21代表硅，22代表碳。由图可以看出，第一，微粒内部的孔隙是随机的，无法为硅颗粒的体积膨胀提供精确和必要的空间，这主要源于其制备过程中热处理温度超过造孔剂熔点，使得造孔剂流失及空腔定制失效；第二，造孔剂流失使得热处理微粒具有开放式孔（见图7），其在包覆过程中允许第三相碳自外而内渗透，从而形成一种非梯度式一体化碳结构，直接包裹在硅表面。这不仅阻碍甚至限制孔隙空间容纳硅颗粒的体积膨胀，还构成一种不稳定的全“刚”性导电网络，其在充放电过程中极易随着硅颗粒的体积膨胀发生裂开及脱落。
采用本对比例的碳硅复合材料作为负极活性材料制备负极并进一步组装得到电池，制备负极和电池的方法和条件与实施例1相同。
电池性能测试结果：
在0.5C的电流密度下，其具有1430 mAh/cm 3的比容量，但仅可循环57次。
以上所述实施例仅表达了本发明的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些都属于本发明的保护范围。因此，本发明专利的保护范围应以所附权利要求为准。

Claims (10)

  1. 一种空腔定制化碳硅复合材料，其特征在于，包括核结构和包覆所述核结构的第三相碳包覆层，所述核结构为第一中间产物颗粒脱除造孔剂颗粒后形成的结构，所述核结构具有所述造孔剂颗粒脱除后形成的定制化空腔，所述第一中间产物颗粒是由硅颗粒、所述造孔剂颗粒、第一相碳和第二相碳形成的复合物颗粒；
    所述第一相碳为具有网络结构的碳纳米材料；
    所述第二相碳为有机化合物的碳物质；
    所述第三相碳为焦油和/或沥青的碳物质。
  2. 根据权利要求1所述的空腔定制化碳硅复合材料，其特征在于，以所述空腔定制化碳硅复合材料的总质量为100%计，所述硅颗粒的质量百分含量为50%-99%。
  3. 根据权利要求2所述的空腔定制化碳硅复合材料，其特征在于，以所述空腔定制化碳硅复合材料的总质量为100%计，所述第一相碳的质量百分含量为0.1%-49%，所述第二相碳的质量百分含量为0.1%-49%，所述第三相碳的质量百分含量为0.1%-49%。
  4. 根据权利要求1~3中任意一项所述的空腔定制化碳硅复合材料，其特征在于，所述硅颗粒包括微米级硅粒子、纳米级硅粒子、硅纳米线和硅纳米管中的一种或两种以上；
    所述碳纳米材料包括碳纳米管、石墨烯、石墨烯氧化物、还原的石墨烯氧化物、纳米碳纤维、细菌纤维素类碳纤维和细菌纤维素类碳纤毛中的一种或两种以上；
    所述有机化合物包括抗坏血酸、柠檬酸、葡萄糖、蔗糖、果糖、麦芽糖、壳聚糖、尿素、淀粉和蛋白质中的一种或两种以上；
    所述焦油包括煤焦油和/或石油焦油；
    所述沥青包括煤沥青和/或石油沥青。
  5. 一种空腔定制化碳硅复合材料的制备方法，其特征在于，包括以下过程：
    将硅颗粒、第一相碳、造孔剂颗粒、有机化合物分散于溶剂中，得到前驱体溶液；其中，所述造孔剂颗粒为可溶于水的盐类物质，所述第一相碳为具有网络结构的碳纳米材料，
    将所述前驱体溶液进行喷雾干燥，得到前驱体颗粒，所述前驱体颗粒为所述硅颗粒、所述第一相碳、所述造孔剂颗粒和所述有机化合物的混合物颗粒；
    将所述前驱体颗粒在非氧化气氛下进行第一次热处理，使所述有机化合物转化为碳物质，形成第二相碳，得到第一中间产物颗粒；
    将所述第一中间产物颗粒用熔融态焦油和/或沥青进行包覆，得到第二中间产物颗粒；
    将所述第二中间产物颗粒在非氧化气氛下进行第二次热处理，使所述焦油和/或沥青转化为碳物质，形成第三相碳包覆层，得到第三中间产物颗粒；
    用水脱除所述第三中间产物颗粒中的所述造孔剂颗粒，得到所述空腔定制化碳硅复合材料。
  6. 根据权利要求5所述的空腔定制化碳硅复合材料的制备方法，其特征在于，所述硅颗粒和所述造孔剂颗粒的体积比为1：0.1～9。
  7. 根据权利要求5所述的空腔定制化碳硅复合材料的制备方法，其特征在于，所述喷雾干燥的进料速度为0.5mL/min-100mL/min，进风温度为100℃-300℃；
    所述第一次热处理的温度为300℃-700℃；
    所述第一次热处理的时间为1h-24h；
    所述第二次热处理的温度为600℃-1400℃；
    所述第二次热处理的时间为1h~24h。
  8. 根据权利要求5所述的空腔定制化碳硅复合材料的制备方法，其特征在于，所述非氧化气氛包括氮气气氛、氩气气氛、氢气气氛和氦气气氛中的一种或两种以上；
    所述盐类物质包括氯化钠、氯化钾、氯化钙、氯化镁、碳酸钠、碳酸钾和硫酸钠中的一种或两种以上。
  9. 根据权利要求5所述的空腔定制化碳硅复合材料的制备方法，其特征在于，所述溶剂包括水；
    所述前驱体溶液中，所述溶剂的质量百分含量为2%~99.9%。
  10. 如权利要求1~4中任意一项所述的空腔定制化碳硅复合材料或如权利要求5~9中任意一项所述的制备方法制备的空腔定制化碳硅复合材料在负极活性材料、负极、电化学储能器件或电化学储能系统中的应用。
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