WO2022188818A1 - Graphite composite material and preparation method therefor, and lithium-ion battery - Google Patents

Graphite composite material and preparation method therefor, and lithium-ion battery Download PDF

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WO2022188818A1
WO2022188818A1 PCT/CN2022/079995 CN2022079995W WO2022188818A1 WO 2022188818 A1 WO2022188818 A1 WO 2022188818A1 CN 2022079995 W CN2022079995 W CN 2022079995W WO 2022188818 A1 WO2022188818 A1 WO 2022188818A1
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composite material
graphite
carbon
coating layer
graphite composite
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PCT/CN2022/079995
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French (fr)
Chinese (zh)
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夏路
刘若琦
王为
任建国
贺雪琴
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贝特瑞新材料集团股份有限公司
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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
    • 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
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • 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
    • 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

Definitions

  • the present disclosure relates to the technical field of graphite anode materials, in particular to a graphite composite material, a preparation method thereof and a lithium ion battery.
  • Graphite anode materials have the characteristics of high energy density, good cycle performance, mature preparation technology, and low manufacturing cost, and are widely used in lithium-ion batteries. With the increasing application of lithium-ion batteries, higher and higher requirements are also placed on graphite anode materials. Therefore, it has become an urgent problem to propose a graphite anode material with high charge-discharge capacity and good fast charge performance.
  • the present disclosure provides a graphite composite material, the graphite composite material has a core-shell structure, and the graphite composite material includes a secondary particle inner core and a second hard carbon coating layer coated on the surface of the secondary particle inner core;
  • the secondary particle core includes primary particles and amorphous carbon, and the primary particles include graphite and a first hard carbon coating layer coated on the surface of the graphite;
  • the first hard carbon coating layer and the second hard carbon coating layer include a carbon framework material.
  • the carbon framework material is uniformly distributed in the first hard carbon coating layer and the second hard carbon coating layer.
  • the content of the carbon framework material in the first hard carbon coating layer is 1% to 10%.
  • the content of the carbon framework material in the second hard carbon coating layer is 1% to 10%.
  • the graphite includes at least one of artificial graphite and natural graphite.
  • the amorphous carbon comprises soft carbon.
  • the amorphous carbon is filled between the primary particles.
  • the carbon framework material includes at least one of carbon nanotubes and carbon fibers.
  • the quantity of carbon framework material contained in the unit cross-sectional area of the first hard carbon coating layer is 2 pieces/ ⁇ m 2 to 5 pieces/ ⁇ m 2 .
  • the quantity of carbon framework material contained in the unit cross-sectional area of the second hard carbon coating layer is 2 pieces/ ⁇ m 2 to 5 pieces/ ⁇ m 2 .
  • the aspect ratio of the carbon framework material is 200-5000.
  • the hardness of the first hard carbon coating layer is 50N/mm 2 to 100N/mm 2 .
  • the hardness of the second hard carbon coating layer is 50N/mm 2 to 100N/mm 2 .
  • n is the first hard carbon
  • H is the hardness of the first hard carbon coating layer.
  • the electrical conductivity of the graphite composite material is 200 S/m ⁇ 400 S/m.
  • the median particle size D50 of the graphite composite material is 13 ⁇ m ⁇ 24 ⁇ m.
  • the particle size distribution (D90-D10)/D50 of the graphite composite material is 0.75-1.0.
  • the specific surface area of the graphite composite material is 0.8 m 2 /g ⁇ 2.0 m 2 /g.
  • the orientation degree I 004 /I 110 of the graphite composite material is 2.0-8.0.
  • the Raman ID/ IG of the graphite composite material is 1.0-2.0 .
  • the thickness of both the first hard carbon coating layer and the second hard carbon coating layer is 50 nm ⁇ 200 nm.
  • the present disclosure also provides a preparation method of the graphite composite material, comprising the following steps:
  • the secondary particles and the solution containing the carbon skeleton material and the polymer are mixed and granulated to form a second polymer precursor coating layer on the surface of the secondary particles, and the graphite composite material is obtained after graphitization.
  • the solution containing the carbon skeleton material and the polymer is prepared by dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a solution containing the carbon skeleton material and the polymer.
  • the carbon framework material includes at least one of carbon nanotubes and carbon fibers.
  • the polymer includes at least one of phenolic resin, polypropylene resin and polyurethane.
  • the solvent includes at least one of organic solvent and water.
  • the solid content of the polymer precursor is 40%-60%.
  • the step of preparing the primary particle precursor is:
  • the graphite raw material particles formed with the first polymer precursor coating layer are dried.
  • the graphite raw material particles include at least one of natural graphite particles and soft carbon particles.
  • the tumbling speed of the graphite raw material particles is 5 r/min to 30 r/min.
  • the temperature of the drying treatment is 80°C to 95°C, and the time is 20 min to 40 min.
  • the step of preparing the secondary particles is:
  • Carbonizing the primary particle precursor to which the carbon source is bound is bound.
  • the carbon source includes easily graphitizable raw materials.
  • the carbon source includes pitch.
  • the tumbling speed of the primary particle precursor is 5 r/min to 30 r/min.
  • the temperature of the carbonization treatment is 450°C to 750°C, and the time is 1 h to 5 h.
  • the step of preparing the graphite composite material is:
  • the secondary particles formed with the second polymer precursor coating layer are graphitized.
  • the particle size of the secondary particles is 13 ⁇ m ⁇ 24 ⁇ m, and the particle size distribution (D90-D10)/D50 is 0.75 ⁇ 1.0.
  • the tumbling speed of the secondary particles ranges from 5 r/min to 30 r/min.
  • the temperature of the graphitization treatment is 2400° C. ⁇ 3000° C., and the time is 1 h ⁇ 6 h.
  • the present disclosure also provides a lithium-ion battery, the lithium-ion battery includes the above-mentioned graphite composite material; and/or, the lithium-ion battery includes the graphite composite material prepared by the above-mentioned preparation method.
  • FIG. 1 is a schematic structural diagram of some embodiments of the disclosed graphite composite material
  • Fig. 2 is the flow chart of the preparation method of the disclosed graphite composite material
  • FIG. 3 is a production process diagram of the preparation method of the disclosed graphite composite material.
  • a graphite composite material 100 has a core-shell structure, and the graphite composite material 100 includes a core of secondary particles 10 and is formed (coated) on the secondary particles 10 a second hard carbon coating layer 20 on the surface of the inner core;
  • the secondary particles 10 include primary particles 11 and amorphous carbon 12, and the primary particles 11 include graphite 111 and a first hard carbon coating layer 112 formed (coated) on the surface of the graphite 111;
  • the first hard carbon coating layer 112 and the second hard carbon coating layer 20 include a carbon framework material.
  • the graphite composite material 100 when used as the graphite negative electrode material, since the graphite 111 has the characteristics of high charge and discharge capacity, the charge and discharge capacity of the graphite negative electrode material is improved.
  • the second hard carbon coating layer 20 is coated on the surface of the inner core of the secondary particle 10, the secondary particle 10 includes the primary particle 11 and the amorphous carbon 12, and the first hard carbon coating layer 112 in the primary particle 11 is coated on graphite
  • the second hard carbon coating layer 20 and the first hard carbon coating layer 112 are formed by hard carbon material, and the hard carbon material has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material.
  • the carbon nanotubes in the hard carbon coating can improve the electrical conductivity, stabilize the structure of the coating, and reduce the polarization internal resistance of the material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
  • the electrolyte since the amorphous carbon inside the particle will shrink to generate pores and cracks during the graphitization process, the electrolyte will enter the particle core through the pores and cracks, and directly contact with the core particles, which will cause the composite material to cause excessive circulation during the cycle.
  • the electrochemical performance of the battery such as fast charge performance, 1C double charge retention rate and 50-cycle capacity retention rate
  • the first hard carbon coating layer 112 amorphous carbon in the graphite composite 100 of the present disclosure 12.
  • the structure of the second hard carbon coating layer 20 enables the graphite composite material 100 to effectively prevent the direct contact between the electrolyte and the primary particles 11, thereby effectively protecting the graphite composite material 100 from proper expansion and contraction during battery cycling.
  • the electrochemical properties of the graphite composite material 100 of the present disclosure such as fast charge performance, 1C double charge retention rate, and 50-cycle capacity retention rate, are improved.
  • the amorphous carbon 12 may be a structure formed by graphitization of soft carbon.
  • the secondary particles 10 may include one primary particle 11 , or may include a plurality of primary particles 11 . A plurality of primary particles 11 are contained within the amorphous carbon 12, thereby further increasing the capacity of the prepared graphite composite material.
  • the second hard carbon coating layer 20 coats the surface of the amorphous carbon 12, the hard carbon material has high electrical conductivity, effectively reduces the polarization internal resistance during charging and discharging, and the hard carbon
  • the coating layer can speed up the desolvation process of lithium ions during charging, so that lithium ions can be quickly embedded in graphite, thus greatly improving the fast charging performance of graphite anode materials.
  • the carbon framework material is uniformly distributed in the first hard carbon coating layer 112 and the second hard carbon coating layer 20.
  • the carbon skeleton material is evenly distributed in the first hard carbon coating layer 112 and the second hard carbon coating layer 20, and the carbon skeleton material can be carbon nanotubes, or carbon fiber, carbon skeleton material. It has high conductivity, thereby reducing the polarization internal resistance during the charging and discharging process of the graphite composite material 100, thereby ensuring the rate performance and low temperature charging and discharging performance of the graphite composite material 100.
  • the content of the carbon framework material in the first hard carbon coating layer is 1% to 10%, for example, 1% to 8%. %, 2%-10% or 2%-8%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%.
  • the content of the carbon framework material uniformly distributed in the first hard carbon coating layer is 1% to 10%.
  • the first hard carbon coating layer 112 can be formed to uniformly coat the surface of the graphite 111, and at the same time, the first hard carbon coating layer 112 can be further improved.
  • the electrical conductivity of the graphite composite material 100 is high, which reduces the polarization internal resistance during the charging and discharging process of the graphite composite material 100, thereby ensuring the rate performance and low temperature charging and discharging performance of the graphite composite material 100.
  • the content of the carbon framework material in the second hard carbon coating layer is 1% to 10%, for example, 2% to 6%. %, 1%-9% or 2%-7%, such as 1%, 1.5%, 2.5%, 3.5%, 4.5%, 5.5%, 6.5%, 7.5%, 8.5%, 9.5%, 10%.
  • the content of the carbon framework material uniformly distributed in the second hard carbon coating layer is 1% to 10%.
  • the formed second hard carbon coating layer 20 further improves the second hard carbon coating layer 20 while achieving uniform coating on the surface of the secondary particles 10 .
  • the electrical conductivity of the graphite composite material 100 is high, which reduces the polarization internal resistance during the charging and discharging process of the graphite composite material 100, thereby ensuring the rate performance and low temperature charging and discharging performance of the graphite composite material.
  • the graphite 111 includes at least one of artificial graphite and natural graphite. It should be noted that the graphite 111 can be natural graphite or artificial graphite made by graphitization of soft carbon material. Both of the above two kinds of graphite have the characteristics of high charge and discharge capacity, which ensures the charge and discharge capacity of the graphite composite material 100 .
  • the amorphous carbon 12 includes soft carbon. It should be noted that the present disclosure coats the surface of the primary particles 11 with soft carbon, which reduces the defects on the surface of the primary particles 11 , and in the subsequent graphitization treatment, makes the prepared spherical particles more compact, thereby improving the vibration of the graphite composite material 100 . In terms of compaction and compaction performance, the more important point is that the volume expansion of the primary particles 11 can be suppressed during the high-temperature carbonization process, and the deformation of the secondary particles 10 during the graphitization process can be prevented.
  • amorphous carbon is filled between the primary particles 11 . In an embodiment of the present disclosure, the amorphous carbon is filled between primary particles. It should be noted that, since the second hard carbon coating layer 20 and the first hard carbon coating layer 112 have a turbostratic carbon structure, and the carbon atomic layer spacing is relatively large, in the embodiment of the present disclosure, the amorphous carbon 12 is sandwiched between Between the second hard carbon coating layer 20 and the first hard carbon coating layer 112 , in this way, lithium ions can be rapidly inserted and inserted, which improves the rate performance of the graphite composite material and the charge-discharge performance in a low temperature environment.
  • the carbon skeleton material is selected from at least one of carbon nanotubes and carbon fibers. It should be noted that carbon nanotubes and carbon fibers have high electrical conductivity, which improves the electrical conductivity of the hard carbon coating layer, thereby reducing the polarization internal resistance during the charging and discharging process of the graphite composite material, thereby ensuring the graphite composite material. Rate performance and low temperature charge-discharge performance.
  • the first hard carbon coating layer 112 is formed by carbonization of a mixture of carbon skeleton material and polymer.
  • the carbon skeleton material includes carbon nanotubes and carbon fibers, and carbon nanotubes and carbon fibers have high electrical conductivity, thereby reducing the polarization internal resistance during the charging and discharging process of the graphite composite material, thereby ensuring the graphite composite material 100. Rate performance and low temperature charge-discharge performance.
  • the polymer can be soluble in organic solvents, liquid at room temperature (about 15°C to 30°C), and carbon content ⁇ 15% (mass percent), such as resin-based polymers or polyurethane-based polymers.
  • the second hard carbon coating layer 20 is formed by carbonization of a mixture of carbon skeleton material and polymer.
  • the carbon skeleton material includes carbon nanotubes and carbon fibers. Carbon nanotubes and carbon fibers have high electrical conductivity, which improves the electrical conductivity of the hard carbon shell and reduces the polarization internal resistance during the charging and discharging process of the graphite composite material, thereby The rate performance and low-temperature charge-discharge performance of the graphite composite material 100 are guaranteed.
  • the polymer can be soluble in organic solvents, liquid at room temperature (about 15°C to 30°C), and carbon content ⁇ 15% (mass percent), such as resin polymers or polyurethane polymers.
  • the amorphous carbon 12 is graphitized from pitch. It should be noted that the amorphous carbon 12 is filled between the second hard carbon coating layer 20 and the first hard carbon coating layer 112, and the amorphous carbon 12 is formed by pitch graphitization.
  • the pitch Acting as a binder, the pitch has a certain fluidity, so that the pitch is filled in the defects of the second hard carbon coating layer 20 and the first hard carbon coating layer 112, reducing the specific surface area of the hard carbon coating layer and increasing the The granulation effect of the secondary particles 10 is improved, the secondary particles 10 are more spherical, the OI orientation of the material is reduced, and the high first efficiency, low expansion and rate performance of the graphite composite material are ensured.
  • the asphalt serves as a filling layer with little deformation, thereby improving the compactness of the graphite composite material 100, improving the material's vibrating and compacting properties, and improving its coating processability.
  • the amorphous carbon 12 coats the graphite 111 coated with the first hard carbon coating layer 112, so that the first hard carbon coating layer 112 is coated inside the amorphous carbon 12, thereby avoiding The volume expansion of the polymer used to form the first hard carbon coating layer 112 during the graphitization process prevents the prepared graphite composite material 100 from being deformed.
  • the amorphous carbon 12 is formed by graphitization of easily graphitizable raw materials.
  • the easily graphitizable raw material may be at least one of pitch, petroleum coke, anthracite, pitch coke, coal-based coke, resin, grease, alkane, alkene, alkyne, and aromatic hydrocarbon.
  • the pitch is selected from at least one of coal pitch, petroleum pitch, mesophase pitch, or modified pitch.
  • “easy graphitization raw material” mainly refers to a raw material of amorphous carbon that is easily converted into graphite at high temperature such as ⁇ 2000°C.
  • the soft carbon is graphitized from readily graphitizable raw materials.
  • the easily graphitizable raw material may be at least one of pitch, petroleum coke, anthracite, pitch coke, coal-based coke, resin, grease, alkane, alkene, alkyne, and aromatic hydrocarbon.
  • the resin may be selected from one of epoxy resins or phenolic resins.
  • the pitch is selected from at least one of coal pitch, petroleum pitch, mesophase pitch, or modified pitch.
  • the first hard carbon coating layer 112 is formed by carbonization of a mixture of carbon framework material and polymer; the second hard carbon coating layer 20 is formed by carbonization of a mixture of carbon framework material and polymer,
  • the carbon skeleton material includes at least one of nanofibers and carbon nanotubes.
  • the number of carbon framework materials contained in the unit cross-sectional area of the first hard carbon coating layer 112 is 2 pieces/ ⁇ m 2 to 5 pieces/ ⁇ m 2 , for example, 2 pieces/ ⁇ m 2 , 3 pieces/ ⁇ m 2 , 4 pieces/ ⁇ m 2 , 5 pieces/ ⁇ m 2 .
  • the amount of carbon framework material contained in the unit cross-sectional area of the second hard carbon coating layer 20 is 2 pieces/ ⁇ m 2 to 5 pieces/ ⁇ m 2 , for example, 2 pieces/ ⁇ m 2 , 3 pieces/ ⁇ m 2 , 4 pieces/ ⁇ m 2 , 5 pieces/ ⁇ m 2 .
  • the percentage of the interface (eg hard carbon cladding interface) of the carbon framework material (represented by A in the context of this disclosure), ie in the carbon framework material at the cladding interface, the carbon framework material's ability to increase the cladding strength and the The percentage of the effective contact area of toughness, which also characterizes the uniformity of the carbon skeleton in the polymer dispersion.
  • carbon skeleton materials such as carbon nanotubes or carbon fibers, when they are dispersed on the interface, the carbon skeleton material is mainly disordered between individuals. state, the carbon framework material can be embedded in the interface (for example, the aspect ratio of the carbon framework material is large) or dispersed on the interface as a whole (for example, the aspect ratio of the carbon framework material is small);
  • the range of A is 10% to 60%, the range of A may be, for example, 25% to 60%, 25% to 50% or 20% to 55%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%.
  • the range of A is selected in the range of 10%-60%, which can ensure the uniform dispersion of the carbon skeleton material, and at the same time can increase the strength and toughness of the coating layer, and improve the strength and conductivity of the material, thereby improving the battery fast charging capacity and cycle. performance.
  • a ⁇ 10% it means that the effective contact area of the carbon skeleton material to enhance the strength is small.
  • the content of the carbon skeleton material is too small and the dispersion is uneven, which will affect the strength and conductivity of the material, resulting in a decrease in the fast charging capacity and cycle performance of the battery.
  • a > 60% it means that the content of carbon skeleton material is too much, which means that the effective contact area of carbon skeleton material to enhance the strength is large at the same time, and at the same time, the material strength is too large and the specific surface area is too high, which will affect the energy density of the battery;
  • the difference between the percentage (A) of the interface of the carbon framework material (for example, the interface of the hard carbon coating layer), the number of carbon framework materials contained in the unit cross-sectional area of the hard carbon coating layer (n), and the hardness of the hard carbon coating layer can be represented by the following formula:
  • n is the quantity of the carbon skeleton material contained in the unit cross-sectional area of the hard carbon coating layer described above;
  • H represents the hardness of the corresponding hard carbon coating
  • 0.7 is the strength coefficient, indicating that the gain coefficient of the carbon skeleton to the frontal compressive strength of the shell is 0.7.
  • the amount of carbon framework material contained in a unit cross-sectional area, and H is the hardness of the first hard carbon coating layer.
  • the quantity of carbon framework material contained in the unit cross-sectional area of , H is the hardness of the second hard carbon coating layer.
  • n can be measured directly, or can be derived from the hardness ranges described below.
  • n derived from the above formula or the range of n in the above embodiment not only makes the carbon skeleton material evenly dispersed, but also effectively improves the electrical conductivity of the hard carbon coating layer, thereby ensuring the performance of the graphite composite material 100 Rate performance (such as 1C charge retention rate) and low-temperature charge-discharge performance; at the same time, this quantity can also satisfy the thickness and hardness of the corresponding carbon coating layer.
  • the aspect ratio of the carbon framework material is 200-5000, for example, it can be 300-5000, 200-4000 or 500-5000, such as 200, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 or 5000.
  • the aspect ratio of the carbon skeleton material of the present disclosure is within the above range, which can further ensure the high electronic conductivity and a certain coating layer strength of the carbon skeleton material, and further improve the fast charging and cycle performance of the material; at the same time, the carbon skeleton material can be further improved. Dispersion effect in polymer solution, thereby improving the cycling performance of graphite composites.
  • the aspect ratio of the carbon skeleton material is too small, the electronic conductivity of the carbon skeleton material will be too low and the strength of the coating layer will be too low, which will affect the fast charging and cycle performance of the graphite composite; if the aspect ratio is too large, it will affect the carbon
  • the dispersion effect of the skeleton material in the polymer solution is easy to agglomerate, which will lead to uneven strength of the coating layer, thus affecting the cycle performance of the graphite composite material.
  • the respective hardnesses of the first hard carbon coating layer 112 and the second hard carbon coating layer 20 may be 50 N/mm 2 to 100 N/mm 2 , for example, the hardness is 60 N/mm 2 to 60 N/mm 2 .
  • 100N/ mm2 , 65N/ mm2 ⁇ 90N/ mm2 or 65N/ mm2 ⁇ 85N/ mm2 such as 51N/ mm2 , 55N/ mm2 , 60N/ mm2 , 65N/ mm2 , 70N/ mm2 , 75N/mm 2 , 80N/mm 2 , 85N/mm 2 , 90N/mm 2 , 95N/mm 2 , 99N/mm 2 , 100N/mm 2 .
  • Both the first hard carbon coating layer 112 and the second hard carbon coating layer 20 of the present disclosure are within the above ranges, which can further improve the battery cycle performance of the composite material, the battery charging rate, and ensure the overall energy density of the battery. If the hardness of the coating layer is less than 50N/mm 2 , it is difficult for the coating layer to suppress the volume expansion of the particle core during the lithium intercalation process, and the particles are easily broken, resulting in poor battery cycle performance; if the hardness of the coating layer is greater than 100N /mm 2 , which means that the coating layer is too dense, which affects the penetration rate of the electrolyte, which will affect the charging rate of the battery.
  • the coating layer is too hard, which reduces the compaction density of the material and affects the overall energy density of the battery.
  • the solid content of the polymer precursor and the amount of carbon skeleton material contained in the unit cross-sectional area of the corresponding hard carbon coating layer are the main factors affecting the hardness of the coating layer.
  • the electrical conductivity of the graphite composite material 100 is 200S/m ⁇ 400S/m, such as 2300S/m ⁇ 400S/m, 200S/m ⁇ 3600S/m, or 280S/m ⁇ 320S/m, such as 200S/m, 220S/m, 240S/m, 260S/m, 280S/m, 300S/m, 320S/m, 340S/m, 360S/m, 380S/m, 400S/m;
  • the electrical conductivity of the graphite composite material 100 of the present disclosure is within the above range, the charge-discharge capacity of the composite material can be further improved, and the 1C double charge retention rate can be improved. If the electrical conductivity is too low, the 1C double charge retention rate will be reduced. If the electrical conductivity is too large, it means that the carbon skeleton material is covered too much (that is, the hard carbon coating layer is too thick), which will affect the battery capacity and decrease the first Coulomb efficiency.
  • the median particle size D50 of the graphite composite material 100 is 13 ⁇ m ⁇ 24 ⁇ m, and the particle size distribution (D90-D10)/D50 is 0.75 ⁇ 1.0.
  • the median particle size of the graphite composite material 100 is within the above range, which can further ensure higher first Coulomb efficiency and fast charging performance of the material. If the median particle size of the material is too large, it will increase the migration distance of Li+ in the material and affect the fast charging performance of the material; if the particle size is too small, the specific surface area of the product will be larger, and the compaction density of the material will decrease, causing the battery The energy density drops.
  • the specific surface area of the graphite composite material 100 is 0.8 m 2 /g ⁇ 2.0 m 2 /g.
  • the specific surface area of the graphite composite material 100 is within the above range, which can further ensure higher first coulombic efficiency and 1C double charge retention rate. If the specific surface area is too large, the first coulomb efficiency will be reduced, and if the specific surface area is too small, the 1C double charge retention rate will be maintained. rate is poor.
  • the graphite composite material 100 has a peak area ratio of the orientation degree I 004 /I 110 of 2.0 to 8.0 at a compaction density of 1.0 g/cm 3 to 2.0 g/cm 3 .
  • the orientation degree of the graphite composite material 100 is within the above range, which can further ensure a higher 1C double charge retention rate and a 50-cycle capacity retention rate. If the orientation is too large, it is easy to cause the material expansion rate to be too large, and thus the 50-cycle capacity retention rate.
  • the size of the graphite raw material particles and the degree of granulation are the main factors affecting the degree of orientation of the graphite composite material 100 .
  • the Raman ID/ IG of the graphite composite material 100 is 1.0 ⁇ 2.0 .
  • the thickness of both the first hard carbon coating layer 112 and the second hard carbon coating layer 20 is 50 nm ⁇ 200 nm.
  • the battery cycle performance of the material can be further ensured and the 1C double charge retention rate of the material can be improved.
  • the thickness of the graphite composite material 100 is too thin, it is difficult for the coating layer to suppress the volume expansion of the particle core during the lithium intercalation process, and the particles are easily broken, resulting in poor battery cycle performance; if the coating layer is too thick, the coating If the coating is too dense, it affects the penetration rate of the electrolyte, thereby affecting the 1C double charge retention rate of the material. At the same time, if the coating is too thick, the compaction density of the material is reduced, which affects the overall energy density of the battery.
  • the solid content of the polymer precursor and the treatment time are the main factors affecting the hardness of the coating layer.
  • a method for preparing a graphite composite material includes the following steps: S10, dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a polymer precursor (that is, containing solution of carbon framework material and polymer); S20, mixing and granulating graphite raw material particles and polymer precursors to form a first polymer precursor coating layer on the surfaces of the graphite raw material particles to obtain primary particle precursors; S30, granulating The primary particle precursor and the carbon source are mixed, and the secondary particles are obtained after carbonization; S40, the secondary particles and the polymer precursor are mixed and granulated to form a coating layer of the second polymer precursor on the surface of the secondary particles, and after graphitization A graphite composite material is obtained.
  • a polymer precursor that is, containing solution of carbon framework material and polymer
  • S20 mixing and granulating graphite raw material particles and polymer precursors to form a first polymer precursor coating layer on the surfaces of the graphite raw material particles to obtain
  • the present disclosure can form a first hard carbon coating layer on the surface of graphite to realize the preparation of primary particles through high-temperature graphitization, and at the same time of high-temperature graphitization, the carbon source on the surface of the primary particles forms soft carbon to realize secondary particles and the second hard carbon coating layer is formed on the surface of the secondary particles, so as to realize the preparation of the graphite composite material. It is added that through the graphitization treatment, the degree of graphitization of the secondary particles reaches more than 93%, which improves the charge-discharge capacity of the graphite composite.
  • the solution containing the carbon skeleton material and the polymer is prepared by dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a solution containing the carbon skeleton material and the polymer.
  • the carbon framework material includes at least one of carbon nanotubes and carbon fibers.
  • the polymer includes at least one of phenolic resin, polypropylene resin and polyurethane.
  • the solvent includes at least one of an organic solvent and water.
  • the carbon skeleton material and the polymer are uniformly dispersed in an organic solvent to obtain a solution containing the carbon skeleton material and the polymer.
  • the organic solvent includes at least one of ethanol and water.
  • the solid content of the polymer precursor is 40%-60%, for example, the solid content is 40%-50%, 50%-60% or 45%-60%, such as 40%, 42% , 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%.
  • the carbon skeleton material and the polymer are added to the organic solution and stirred to disperse the carbon skeleton material and the polymer in the organic solvent.
  • the carbon framework material may be carbon nanotubes and carbon fibers.
  • the lengths of the carbon nanotubes and carbon fibers are 100 nm-300 nm, and the diameters are 5 nm-10 nm.
  • the mass ratio of the carbon skeleton material to the polymer is (1-10):(90-99).
  • the organic solvent may be ethanol, as long as it can achieve dissolution or dispersion of the carbon skeleton material and the polymer.
  • the solid content of the mixed solution of the carbon skeleton material and the polymer is 40% to 60%.
  • Embodiments of the present disclosure use a mixture of a carbon framework material and a polymer to prepare the first hard carbon coating layer and the second hard carbon coating layer, so that the first hard carbon coating layer and the second hard carbon coating layer are in graphite After the high temperature treatment, the hard carbon structure can still be maintained, and the ultra-high temperature of the graphitization process can greatly reduce the specific surface area of the graphite composite material, avoiding the disadvantages of excessive side reactions and large irreversible capacity for the first time due to excessive specific surface area. , which improves the coulombic efficiency of the first charge and discharge of the graphite anode material.
  • step S20 may be: S21, spraying the polymer precursor onto the surface of the graphite raw material particles; S22, rolling the graphite raw material particles to form a first polymer precursor coating layer on the surface of the graphite raw material particle; S23, drying the graphite raw material particles formed with the first polymer precursor coating layer.
  • the tumbling speed of the graphite feedstock particles is 5 r/min to 30 r/min, such as 10 r/min to 30 r/min, 15 r/min to 30 r/min, or 5 r/min to 25 r/min, such as 5 r/min , 8r/min, 10r/min, 12r/min, 15r/min, 17r/min, 20r/min, 22r/min, 25r/min, 27r/min, 30r/min.
  • the drying temperature ranges from 80°C to 95°C, such as 80°C, 82°C, 85°C, 87°C, 90°C, 92°C, and 95°C; the drying time ranges from 20min to 40min. Times such as 20min, 22min, 25min, 27min, 30min, 32min, 35min, 37min, 40min.
  • tumbling may refer to the term “tumbling”, referring to the rolling, turning and/or spinning of particles.
  • tumbling can be the rolling forward and reciprocating motion of the graphite raw material in a circular shape along the circular furnace wall.
  • the polymer precursor is transferred to a coating device, the coating device is a drum spray coating device, the drum rotation speed of the coating device is adjusted to be 5r/min-30r/min, and the polymerization is carried out through a two-fluid nozzle.
  • the precursor is sprayed onto the surface of the tumbling graphite raw material particles, and dried under hot air.
  • the drying temperature is 80°C to 95°C, and the coating treatment time is 20min to 40min. It should be noted that the present disclosure can appropriately adjust the coating treatment time according to the rotation speed of the drum, as long as the uniform coating of the polymer precursor on the surface of the graphite raw material particles is ensured.
  • the present disclosure can also adopt other coating equipment, such as Fluid bed coaters, press coating equipment, etc., the present disclosure is not limited thereto, and the above are all within the protection scope of the present disclosure.
  • the graphite raw material particles may be natural graphite particles or soft carbon particles.
  • the soft carbon particles include petroleum coke, needle coke, carbon fiber, anthracite, carbon microspheres, and the like.
  • needle coke includes oil-based needle coke and coal-based needle coke, the above embodiments of the present disclosure are not limited thereto, and the above are all within the protection scope of the embodiments of the present disclosure.
  • the method before step S21, further includes pulverizing the graphite raw material to obtain graphite raw material particles.
  • the particle size distribution of the graphite raw material particles is: D10: 3-8 ⁇ m, D50: 5-12 ⁇ m, D90: 12-18 ⁇ m, D max ⁇ 30 ⁇ m, and the particle diameters in the particle size distribution are all median diameters.
  • the graphite raw material is added to a crusher, and the graphite raw material is pulverized by the crusher to obtain a crushed material with a particle size of less than 5 mm, and the crushed material is then mechanically ground to a particle size of D10:3-8 ⁇ m, D50: 5 ⁇ 12 ⁇ m, D90: 12 ⁇ 18 ⁇ m, D max ⁇ 30 ⁇ m, to obtain graphite raw material particles, in this way, after graphitization treatment, the first hard carbon coating layer is uniformly coated on the graphite surface formed by the graphite raw material particles, thereby The charge-discharge performance of the prepared graphite anode material is guaranteed.
  • step S30 may be: S31, spray the carbon source on the surface of the primary particle precursor; S32, roll the primary particle precursor to bond the primary particle precursors through the carbon source; S33, carbonize The carbon source-bonded primary particle precursor is processed.
  • the carbon source is a graphitizable feedstock.
  • the easily graphitizable raw material may be at least one of pitch, petroleum coke, anthracite, pitch coke, coal-based coke, resin, grease, alkane, alkene, alkyne, and aromatic hydrocarbon.
  • the resin may be selected from one of epoxy resins or phenolic resins.
  • the pitch is selected from at least one of coal pitch, petroleum pitch, mesophase pitch, or modified pitch.
  • the carbon source is pitch.
  • the equipment used for the preparation can be selected such as a drum furnace and a rotary furnace.
  • the tumbling speed of the primary particle precursor is 5r/min to 30r/min, such as 5r/min, 12r/min, 15r/min, 18r/min, 20r/min, 22r/min, 25r/min , 28r/min, 30r/min.
  • the temperature of the carbonization treatment is 450°C to 750°C, such as 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C; and the time is 1h to 5h, such as 1h, 1.5h , 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h.
  • step S30 is performed in a drum furnace, the temperature of the material in the drum is raised to 150°C-250°C, the molten asphalt is sprayed on the surface of the primary particle precursor through a two-fluid nozzle, and the drum rotational speed is adjusted to 5r/min ⁇ 30r/min, the asphalt spraying flow is 80mL/min ⁇ 120mL/min, and the spraying time is 10min ⁇ 30min.
  • the drum speed adjust the drum speed to 20r/min ⁇ 40r/min, and at the same time, the material in the drum is 2h ⁇ 8h liters. to 450°C ⁇ 750°C, keep the temperature for 1h ⁇ 5h, and cool down to obtain secondary particles.
  • the median particle diameter D50 of the prepared secondary particles is 13 ⁇ m ⁇ 24 ⁇ m, and the particle size distribution Span is 0.75 ⁇ 1.0.
  • the asphalt is melted and then sprayed onto the surface of the primary particle precursor, thereby reducing the proportion of the amount of asphalt used, increasing the granulation effect, and improving the The consistency of the granulation of the secondary particles makes the OI orientation of the secondary particles lower and reduces the expansion degree of lithium intercalation of the prepared graphite composites.
  • step S40 may be: S41, spraying the polymer precursor onto the surface of the secondary particles; S42, rolling the secondary particles to form a second polymer precursor coating layer on the surface of the secondary particles; S43, graphitizing the secondary particles formed with the coating layer of the second polymer precursor.
  • the median particle size of the secondary particles is 13 ⁇ m to 24 ⁇ m, such as 13 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 22 ⁇ m, 24 ⁇ m; the particle size distribution (D90-D10)/D50 is 0.75 to 1.0, such as 0.75, 0.8 , 0.85, 0.9, 0.95, 1.
  • the tumbling speed of the secondary particles is 5 r/min to 30 r/min, such as 5 r/min, 8 r/min, 10 r/min, 15 r/min, 20 r/min, 25 r/min, 30 r/min.
  • the graphitization temperature is 2400°C to 3000°C, such as 2500°C to 3000°C, 2400°C to 2600°C, or 2500°C to 2900°C; the graphitization time is 1h to 6h, such as 1h, 2h, 3h, 4h, 5h, 6h.
  • the equipment used for the preparation can be selected such as coating equipment, fluidized bed coater, press coating equipment and the like.
  • step S40 is carried out in the coating equipment, the rotation speed of the drum is adjusted to 5r/min ⁇ 30r/min, and the polymer precursor is sprayed on the tumbling two-fluid nozzle at a speed of 30mL/min ⁇ 80mL/min through a two-fluid nozzle
  • the spray coating treatment time is 20min to 40min, and the secondary particles sprayed with the polymer precursor are put into a graphitization furnace for high-temperature graphitization.
  • the graphitization furnace is an inner string furnace or an Acheson furnace.
  • the graphitization temperature is 2400°C ⁇ 3000°C, and the graphitization time is 1h ⁇ 6h to obtain the graphite composite material.
  • the embodiments of the present disclosure can adjust the graphitization conditions according to the actual situation, and the embodiments of the present disclosure are not limited thereto, and the above are all within the protection scope of the embodiments of the present disclosure.
  • the surface of the graphite raw material particles and the surface of the secondary particles are coated with a polymer precursor containing a carbon framework material and a polymer, and the polymer precursor is converted into a hard carbon coating similar to a reinforced cement concrete structure after graphitization.
  • layer wherein the carbon skeleton material acts as a skeleton in both the second hard carbon coating layer and the first hard carbon coating layer, effectively increasing the mechanical strength of the second hard carbon coating layer and the first hard carbon coating layer,
  • the Young's modulus and conductance are beneficial to the stable accumulation of the graphite composite material into a spherical structure, thereby improving the long-term cycle performance of the graphite anode material.
  • the coating, granulation and coating of the graphite raw material particles can be achieved in one step, which greatly shortens the manufacturing cycle of the graphite negative electrode material and reduces the The production cost is convenient for large-scale production.
  • the present disclosure also provides a lithium-ion battery, where the lithium-ion battery includes the above-mentioned graphite composite material; and/or, the lithium-ion battery includes the graphite composite material prepared by the above-mentioned preparation method.
  • the graphite composite material is used as the graphite negative electrode material, the charge and discharge capacity of the graphite negative electrode material is improved due to the high charge and discharge capacity of graphite.
  • the second hard carbon coating layer is coated on the surface of the inner core of the secondary particles, the secondary particles include primary particles and amorphous carbon, and the first hard carbon coating layer is coated on the surface of the graphite in the primary particles, and the second hard carbon coating is
  • the coating layer and the first hard carbon coating layer are formed by the hard carbon material, and the hard carbon material has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
  • the prior art discloses the following graphite negative electrode materials: the first graphite negative electrode material, the graphite raw material particles are pulverized to a certain particle size, the granulation of secondary particles is realized by kneading, and the graphite negative electrode material is obtained by graphitization; the defects of this structure exist It is difficult to take into account the capacity and fast charging performance. If you choose easy graphitization raw materials, the capacity can be guaranteed but the fast charging performance is poor; if you choose difficult graphitization raw materials, the fast charging performance is good but the capacity is low.
  • the second type of graphite anode material coats the graphite surface with a hard carbon layer or a soft carbon layer. Although the surface coating can reduce the interface impedance and improve the fast charging performance.
  • the disadvantage of this structure is that it has not undergone graphitization treatment, and the coating layer on the surface will affect the graphite capacity. If the coating is pitch-based soft carbon, the fast charging performance of the material is not as good as that of hard carbon.
  • the secondary particles are easily deformed and pulverized, the coating layer is unstable, the particle size is uneven, the lithium ion transmission ability is poor, and the rate performance does not meet the requirements.
  • the present disclosure provides a graphite composite material, which aims to improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
  • the charge and discharge capacity of the graphite negative electrode material is improved because the graphite has the characteristics of high charge and discharge capacity.
  • the second hard carbon coating layer is coated on the surface of the inner core of the secondary particles, the secondary particles include primary particles and amorphous carbon, and the first hard carbon coating layer is coated on the surface of the graphite in the primary particles, and the second hard carbon coating is The coating layer and the first hard carbon coating layer are formed by the hard carbon material, and the hard carbon material has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
  • Step 1 use a crusher to roughly crush the oil-based needle coke raw material to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 4-6 ⁇ m, D50: 7-8 ⁇ m, D90: 14-16 ⁇ m, D max ⁇ 28 ⁇ m graphite raw material particles, carbon nanotubes and phenolic resin were added to ethanol at a mass ratio of 1:19, the solid content was controlled to be 45%, and stirred to dissolve the carbon nanotubes and phenolic resin in ethanol to obtain Carbon nanotube-phenolic resin mixture, wherein the average aspect ratio of carbon nanotubes is 3125;
  • step 2 the graphite raw material particles are transferred to the drum spray coating equipment, and the rotating speed of the drum is 15r/min, and the mixed solution of carbon nanotube-phenolic resin is sprayed on the surface of the tumbling graphite raw material particles at a speed of 50 mL/min through a two-fluid nozzle. , and dried under hot air at 90°C, and the coating treatment time was 30min to obtain the primary particle precursor;
  • Step 3 raising the temperature of the material in the drum to 200°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum speed to 15r/min, the asphalt spraying flow rate to 100mL/min, and the spraying time to 20min. After stopping spraying, adjust the rotation speed of the drum to 30r/min, and at the same time raise the material in the drum to 600°C for 4h, keep the temperature for 2h, and cool down to obtain secondary particles.
  • the median particle size D50 of the secondary particles is 18 ⁇ m, and the particle size distribution Span is 0.8;
  • Step 4 adjust the rotating speed of the drum to 15r/min, spray the mixture of carbon nanotube-phenolic resin on the surface of the tumbling spherical secondary particles at a speed of 50mL/min through a two-fluid nozzle, and dry it under hot air at 90°C, spray
  • the coating treatment time is 30min, and the obtained secondary particles coated with carbon nanotube-phenolic resin are subjected to high-temperature graphitization. 2h ⁇ 4h, the graphite composite material is obtained.
  • the graphite composite material has a core-shell structure, which includes a secondary particle inner core and a second hard carbon coating on the surface of the secondary particle inner core (from step 4 carbon nanotube-phenolic resin preparation);
  • the secondary particles include primary particles (that is, the precursor of the primary particles in step 2) and amorphous carbon (obtained from the molten pitch in step 3), and the primary particles include graphite and the first hard carbon coated on the surface of the graphite Coating layer (formed by carbon nanotube-phenolic resin preparation in step 1); carbon nanotubes are uniformly distributed in the first hard carbon coating layer and the second hard carbon coating layer.
  • Step 1 use a crusher to roughly crush the coal-based needle coke raw material to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 4-6 ⁇ m, D50: 6-7 ⁇ m, D90: 13-15 ⁇ m, D max ⁇ 28 ⁇ m graphite raw material particles, carbon nanotubes and polyacrylonitrile were added to ethanol in a mass ratio of 7:93, the solid content was controlled to 50%, and stirred to dissolve carbon nanotubes and polyacrylonitrile in ethanol , to obtain a mixture of carbon nanotubes-polyacrylonitrile, wherein the average aspect ratio of carbon nanotubes is 714;
  • Step 2 the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the carbon nanotube-polyacrylonitrile mixed solution is sprayed on the tumbling graphite raw material particles at a speed of 60 mL/min through a two-fluid nozzle.
  • the surface was dried under hot air at 95°C, and the coating treatment time was 35min to obtain the primary particle precursor;
  • Step 3 raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum speed to 20r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min, After stopping spraying, adjust the rotation speed of the drum to 30r/min, and at the same time raise the material in the drum to 650°C for 5h, keep the temperature for 3h, and cool down to obtain secondary particles.
  • the median particle size D50 of the secondary particles is 16 ⁇ m, and the particle size distribution Span is 0.85;
  • Step 4 adjust the rotating speed of the drum to 18r/min, spray the mixture of carbon nanotube-polyacrylonitrile at a speed of 60mL/min on the surface of the tumbling spherical secondary particles through a two-fluid nozzle, and dry it under hot air at 95°C,
  • the spray coating treatment time is 35min, and the secondary particles coated with carbon nanotube-polyacrylonitrile are subjected to high temperature graphitization. composite material.
  • the graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from carbon nanotube-polyacrylonitrile in step 4; The carbon coating layer is formed by preparing carbon nanotubes-polyacrylonitrile in step one.
  • Step 1 use a crusher to roughly crush the raw material of petroleum coke to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 5-7 ⁇ m, D50: 8-9 ⁇ m, D90: 15-17 ⁇ m, D max ⁇ 28 ⁇ m graphite raw material particles, carbon nanotubes and polyurethane were added to ethanol at a mass ratio of 2:23, the solid content was controlled to 55%, and the carbon nanotubes and polyurethane were stirred to dissolve in ethanol to obtain carbon nanotube-polyurethane
  • the mixed solution wherein the average aspect ratio of carbon nanotubes is 2836;
  • Step 2 the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the carbon nanotube-polyurethane mixed solution is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle, And dried under hot air at 90°C, the coating treatment time is 40min, and the primary particle precursor is obtained;
  • Step 3 raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650°C for 5h, keep the temperature for 3h, and cool down to obtain secondary particles.
  • the median particle size D50 of the secondary particles is 19 ⁇ m, and the particle size distribution Span is 0.75;
  • Step 4 Adjust the rotating speed of the drum to 18r/min, spray the carbon nanotube-polyurethane mixture on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90°C.
  • the coating treatment time is 40min, and the carbon nanotube-polyurethane-coated secondary particles are subjected to high-temperature graphitization.
  • the graphitization furnace is an Acheson furnace, the graphitization temperature is 2900°C, and the graphitization time is 4h to obtain a graphite composite material.
  • the graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from carbon nanotube-polyurethane in step 4; The coating is formed by the carbon nanotube-polyurethane preparation in step one.
  • Step 1 use a crusher to coarsely crush the petroleum coke raw material to obtain crushed material with a particle size of less than 5mm, and then use a mechanical mill to pulverize to a particle size of: D10: 3 ⁇ 4 ⁇ m, D50: 5 ⁇ 7 ⁇ m, D90: 12 ⁇ 15 ⁇ m, D max ⁇ 25 ⁇ m graphite raw material particles, carbon fiber and polyvinyl alcohol were added to ethanol at a mass ratio of 2:23, and the solid content was controlled to 55%, and stirred to dissolve carbon fiber and polyvinyl alcohol in ethanol to obtain carbon fiber-polyvinyl alcohol
  • the mixed solution in which the average aspect ratio of carbon fiber is 480;
  • Step 2 the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the mixed solution of carbon fiber-polyvinyl alcohol is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle, And dried under hot air at 90°C, the coating treatment time is 40min, and the primary particle precursor is obtained;
  • Step 3 raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650°C for 5h, keep the temperature for 3h, and cool down to obtain secondary particles.
  • the median particle size D50 of the secondary particles is 15 ⁇ m, and the particle size distribution Span is 0.85;
  • Step 4 adjust the rotating speed of the drum to 18r/min, spray the mixture of carbon fiber-polyvinyl alcohol on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90 ° C, spray the bag.
  • the coating treatment time is 40min, and the carbon fiber-polyvinyl alcohol-coated secondary particles are subjected to high temperature graphitization.
  • the graphitization furnace is an Acheson furnace, the graphitization temperature is 2900°C, and the graphitization time is 4h to obtain a graphite composite material.
  • the graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from step 4 carbon fiber-polyvinyl alcohol; the first hard carbon coating layer is formed.
  • the cladding layer is formed by carbon fiber-polyvinyl alcohol preparation in step 1; the carbon fibers are uniformly distributed in the first hard carbon cladding layer and the second hard carbon cladding layer.
  • Step 1 use a crusher to coarsely crush the petroleum coke raw material to obtain crushed material with a particle size of less than 5mm, and then use a mechanical mill to pulverize to a particle size of: D10: 3 ⁇ 4 ⁇ m, D50: 5 ⁇ 7 ⁇ m, D90: 12 ⁇ 15 ⁇ m, D max ⁇ 25 ⁇ m graphite raw material particles, carbon nanotubes and polyurethane were added to ethanol at a mass ratio of 1:99, and the solid content was controlled to 55%, and stirred to dissolve carbon nanotubes and polyurethane in ethanol to obtain carbon nanotube-polyurethane
  • the mixed solution wherein the average aspect ratio of carbon nanotubes is 3128;
  • Step 2 the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the carbon nanotube-polyurethane mixed solution is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle, And dried under hot air at 90°C, the coating treatment time is 40min, and the primary particle precursor is obtained;
  • Step 3 raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650°C for 5h, keep the temperature for 3h, and cool down to obtain secondary particles.
  • the median particle size D50 of the secondary particles is 16 ⁇ m, and the particle size distribution Span is 0.85;
  • Step 4 Adjust the rotating speed of the drum to 18r/min, spray the carbon nanotube-polyurethane mixture on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90°C.
  • the coating treatment time is 40min, and the carbon nanotube-polyurethane-coated secondary particles are subjected to high-temperature graphitization.
  • the graphitization furnace is an Acheson furnace, the graphitization temperature is 2900°C, and the graphitization time is 4h to obtain a graphite composite material.
  • the graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from carbon nanotube-polyurethane in step 4; The coating is formed by the carbon nanotube-polyurethane preparation in step one.
  • Step 1 use a crusher to roughly crush the coal-based needle coke raw material to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 3-4 ⁇ m, D50: 5-7 ⁇ m, D90: 12-15 ⁇ m, D max ⁇ 25 ⁇ m graphite raw material particles, carbon nanotubes and phenolic resin were added to ethanol at a mass ratio of 1:9, the solid content was controlled to 55%, and stirred to dissolve the carbon nanotubes and phenolic resin in ethanol to obtain Carbon nanotube-phenolic resin mixture, wherein the average aspect ratio of carbon nanotubes is 3800;
  • step 2 the graphite raw material particles are transferred to the drum spray coating equipment, and the rotating speed of the drum is 18r/min, and the mixed solution of carbon nanotube-phenolic resin is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle. , and dried under hot air at 90°C, and the coating treatment time was 40min to obtain the primary particle precursor;
  • Step 3 raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650°C for 5h, keep the temperature for 3h, and cool down to obtain secondary particles.
  • the median particle size D50 of the secondary particles is 19 ⁇ m, and the particle size distribution Span is 0.75;
  • Step 4 adjust the rotating speed of the drum to 18r/min, spray the mixture of carbon nanotube-phenolic resin on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90°C.
  • the coating treatment time is 40min, and the carbon nanotube-phenolic resin-coated secondary particles are graphitized at high temperature.
  • the structure of the graphite composite material obtained in this example is similar to that of Example 1.
  • Example 1 The difference from Example 1 is that the solid content of the polymer (ie, the polymer precursor) in the control step 1 is 35%.
  • the structure of the graphite composite material obtained in this example is similar to that of Example 1.
  • Example 1 The difference from Example 1 is that the solid content of the polymer (ie, the polymer precursor) in the control step 1 is 65%.
  • the structure of the graphite composite material obtained in this example is similar to that of Example 1.
  • the reaction kettle is a heating and stirring reaction kettle, and the heating conditions are: 4h normal temperature temperature to 650°C, keep the temperature for 2h, then cool down and cool down, the stirring speed of the whole reaction process is 15r/min, and the N 2 flow rate is 4L/min; the particle size of the secondary particles obtained after granulation: D10 is 8 ⁇ m, D50 is 18 ⁇ m, D90 is 28 ⁇ m, Dmax is 33 ⁇ m;
  • the secondary particles are subjected to graphitization treatment for 3 hours, the graphitization furnace is an inner string furnace, and the graphitization temperature is 2900° C. After the graphitization treatment, a graphite composite material is obtained.
  • the graphite composite material obtained in this comparative example only includes graphite and amorphous carbon formed on the surface of the graphite.
  • Example 1 The difference from Example 1 is that Step 3 and Step 4 are not performed.
  • the graphite composite material obtained in this comparative example only includes graphite and a first hard carbon coating layer (formed by carbon nanotube-phenolic resin preparation in step 1) coated on the surface of the graphite.
  • step 4 is not performed.
  • the graphite composite material obtained in this example only includes the core of secondary particles, and the structure of the secondary particles is the same as that of the embodiment.
  • the particle size analysis laser diffraction method was used to measure.
  • the measurement was performed using a Macbee 3020 instrument using the gas adsorption BET method.
  • the Renishaw inVia Raman instrument was used for measurement using the Map image acquisition method.
  • the hardness is measured. It should be noted that in the embodiment of the present disclosure, the hardness of the first hard carbon coating layer and the second hard carbon coating layer are the same or similar. . Under the high-resolution microscope (Dynamic Ultra Micro Hardness Tester DUH-211S from Shimadzu, Japan), under the action of the load force P of the nano-indenter, the indenter presses a circular indentation on the surface of the particle.
  • the test was carried out under the microscope of Hitachi SU9000 ultra-high-resolution emission scanning electron microscope.
  • the rate test conditions are: 10.1C to 0.01V, constant voltage for 5h; 0.1C to 1.5V; 20.2C to 0.01V, constant voltage 0.01C ; 0.2C to 1.5V; 30.2C to 0.01V, constant voltage 0.01C; 2C to 1.5V, 0.2C to 1.5V; 40.2C to 0.01V, constant voltage 0.01C; 0.2C to charge 51C to 0.01V, constant voltage 0.01C; 0.2C to 1.5V; 62C to 0.01V; cycle test conditions: 0.2C rate charge and discharge, voltage range 0.01V ⁇ 1.5V.
  • the first-week charging specific capacity, the first-week efficiency, and the 50-week derating cycle stability were respectively tested, and the 1C (CC/0.2C CC+CV) double charge and 50-week capacity retention rate were calculated.
  • the test results are shown in Table 2 below:
  • Examples 1 to 6 of the present disclosure show that in Comparative Examples 1, 2 and 3 there is also an amorphous carbon (that is, formed from molten pitch) structure, and Comparative Examples 1 and 2
  • the amorphous carbon in the composite materials prepared by and 3 will generate holes due to shrinkage during the cycle of the battery, so that there will be gaps and holes inside the composite material, so the electrolyte will enter the particle core through the holes and cracks, directly with the core particles. contact, resulting in excessive expansion and shrinkage of the composite during cycling, thereby reducing the electrochemical performance of the battery, such as fast charge performance, 1C double charge retention, 50-cycle capacity retention, and -20°C low-temperature discharge capacity retention.
  • the present disclosure due to the existence of the first hard carbon coating layer on the primary particles of the composite material, the direct contact between the electrolyte and the primary particles is prevented, thereby effectively protecting the material in the battery cycle process. Therefore, the electrochemical performance of the composite material of the present disclosure is improved, thereby further ensuring the high capacity retention rate and excellent fast charging performance of the graphite negative electrode material.
  • the thickness and hardness of the hard carbon coating layer of the materials prepared in the examples of the present disclosure are within the scope of the present disclosure, It can further ensure that the material avoids volume expansion during the charging and discharging process, thereby further improving the cycle performance of the material, such as the 50-cycle capacity retention rate.
  • the thickness and hardness of the hard carbon coating layer of the materials prepared in the examples of the present disclosure can ensure a higher energy density of the battery and effectively improve the battery's performance. Gram capacity and first coulombic efficiency.
  • the graphite composite material provided by the present disclosure is used as a graphite negative electrode material, since graphite has the characteristics of high charge and discharge capacity, the charge and discharge capacity of the graphite negative electrode material is improved.
  • the hard carbon material in the graphite composite material of the present disclosure has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material, and has excellent application value.

Abstract

The present disclosure provides a graphite composite material and a preparation method therefor, and a lithium-ion battery. The graphite composite material is of a core-shell structure, and comprises a secondary particle core and a second hard carbon coating layer formed on the surface of the secondary particle core; a secondary particle comprises a primary particle and amorphous carbon, and the primary particle comprises graphite and a first hard carbon coating layer formed on the surface of the graphite; and the first hard carbon coating layer and the second hard carbon coating layer respectively comprise a carbon skeleton material. That is, the technical solution of the present disclosure can improve the fast charging performance of a graphite negative electrode material while increasing the capacitance of the graphite negative electrode material.

Description

石墨复合材料、其制备方法与锂离子电池Graphite composite material, its preparation method and lithium ion battery
相关申请的交叉引用CROSS-REFERENCE TO RELATED APPLICATIONS
本公开要求于2021年03月10日提交中国专利局的申请号为“CN 202110263669.X”名称为“石墨复合材料、其制备方法与锂离子电池”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。This disclosure claims the priority of the Chinese patent application with the application number "CN 202110263669.X" and the title "graphite composite material, its preparation method and lithium ion battery" filed with the China Patent Office on March 10, 2021, the entire contents of which are Incorporated in this disclosure by reference.
技术领域technical field
本公开涉及石墨负极材料技术领域，特别涉及一种石墨复合材料、其制备方法与锂离子电池。The present disclosure relates to the technical field of graphite anode materials, in particular to a graphite composite material, a preparation method thereof and a lithium ion battery.
背景技术Background technique
石墨负极材料具有能量密度高、循环性能好、制备技术成熟、制造成本低等特点，广泛应用于锂离子电池。随着锂离子电池应用领域的日益广泛，对石墨负极材料也提出了越来越高的要求，因此，提出一种充放电容量高且快充性能好的石墨负极材料成为了亟待解决的问题。Graphite anode materials have the characteristics of high energy density, good cycle performance, mature preparation technology, and low manufacturing cost, and are widely used in lithium-ion batteries. With the increasing application of lithium-ion batteries, higher and higher requirements are also placed on graphite anode materials. Therefore, it has become an urgent problem to propose a graphite anode material with high charge-discharge capacity and good fast charge performance.
发明内容SUMMARY OF THE INVENTION
本公开提供了一种石墨复合材料，所述石墨复合材料为核壳结构，所述石墨复合材料包括二次颗粒内核和包覆于所述二次颗粒内核表面的第二硬炭包覆层；The present disclosure provides a graphite composite material, the graphite composite material has a core-shell structure, and the graphite composite material includes a secondary particle inner core and a second hard carbon coating layer coated on the surface of the secondary particle inner core;
所述二次颗粒内核包括一次颗粒和无定型炭，所述一次颗粒包括石墨和包覆于所述石墨表面的第一硬炭包覆层；The secondary particle core includes primary particles and amorphous carbon, and the primary particles include graphite and a first hard carbon coating layer coated on the surface of the graphite;
所述第一硬炭包覆层和所述第二硬炭包覆层包括碳骨架材料。The first hard carbon coating layer and the second hard carbon coating layer include a carbon framework material.
可选地，所述碳骨架材料均匀分布在所述第一硬炭包覆层和所述第二硬炭包覆层中。Optionally, the carbon framework material is uniformly distributed in the first hard carbon coating layer and the second hard carbon coating layer.
可选地，以所述第一硬炭包覆层的质量为100％计，所述第一硬炭包覆层中的碳骨架材料的含量为1％～10％。Optionally, based on the mass of the first hard carbon coating layer as 100%, the content of the carbon framework material in the first hard carbon coating layer is 1% to 10%.
可选地，以所述第二硬炭包覆层的质量为100％计，所述第二硬炭包覆层中的碳骨架材料的含量为1％～10％。Optionally, based on the mass of the second hard carbon coating layer as 100%, the content of the carbon framework material in the second hard carbon coating layer is 1% to 10%.
可选地，所述石墨包括人造石墨和天然石墨中的至少一种。Optionally, the graphite includes at least one of artificial graphite and natural graphite.
可选地，所述无定型炭包括软炭。Optionally, the amorphous carbon comprises soft carbon.
可选地，所述一次颗粒之间填充有所述无定型炭。Optionally, the amorphous carbon is filled between the primary particles.
可选地，所述碳骨架材料包括碳纳米管和碳纤维中的至少一种。Optionally, the carbon framework material includes at least one of carbon nanotubes and carbon fibers.
可选地，所述第一硬炭包覆层的单位截面积中所含碳骨架材料的数量为2根/μm 2～5根/μm 2。 Optionally, the quantity of carbon framework material contained in the unit cross-sectional area of the first hard carbon coating layer is 2 pieces/μm 2 to 5 pieces/μm 2 .
可选地，所述第二硬炭包覆层的单位截面积中所含碳骨架材料的数量为2根/μm 2～5根/μm 2。 Optionally, the quantity of carbon framework material contained in the unit cross-sectional area of the second hard carbon coating layer is 2 pieces/μm 2 to 5 pieces/μm 2 .
可选地，所述碳骨架材料的长径比为200～5000。Optionally, the aspect ratio of the carbon framework material is 200-5000.
可选地，所述第一硬炭包覆层硬度为50N/mm 2～100N/mm 2。 Optionally, the hardness of the first hard carbon coating layer is 50N/mm 2 to 100N/mm 2 .
可选地，所述第二硬炭包覆层硬度为50N/mm 2～100N/mm 2。 Optionally, the hardness of the second hard carbon coating layer is 50N/mm 2 to 100N/mm 2 .
可选地，所述第一硬炭包覆层中，所述碳骨架材料的界面百分比A为10％～60％，其中A＝H/(n×0.7)，n为所述第一硬炭包覆层的单位截面积中所含碳骨架材料的数量，H为所述第一硬炭包覆层的硬度。Optionally, in the first hard carbon coating layer, the interface percentage A of the carbon framework material is 10% to 60%, where A=H/(n×0.7), and n is the first hard carbon The quantity of carbon framework material contained in the unit cross-sectional area of the coating layer, and H is the hardness of the first hard carbon coating layer.
可选地，所述第二硬炭包覆层中，所述碳骨架材料的界面百分比A为10％～60％，其中A＝H/(n×0.7)，n为所述第二硬炭包覆层的单位截面积中所含碳骨架材料的数量，H为所述第二硬炭包覆层的硬度。Optionally, in the second hard carbon coating layer, the interface percentage A of the carbon framework material is 10% to 60%, where A=H/(n×0.7), and n is the second hard carbon The amount of carbon skeleton material contained in the unit cross-sectional area of the coating layer, and H is the hardness of the second hard carbon coating layer.
可选地，所述石墨复合材料的电导率为200S/m～400S/m。Optionally, the electrical conductivity of the graphite composite material is 200 S/m˜400 S/m.
可选地，所述石墨复合材料的中值粒度D50为13μm～24μm。Optionally, the median particle size D50 of the graphite composite material is 13 μm˜24 μm.
可选地，所述石墨复合材料的粒度分布(D90-D10)/D50为0.75～1.0。Optionally, the particle size distribution (D90-D10)/D50 of the graphite composite material is 0.75-1.0.
可选地，所述石墨复合材料的比表面积为0.8m 2/g～2.0m 2/g。 Optionally, the specific surface area of the graphite composite material is 0.8 m 2 /g˜2.0 m 2 /g.
可选地，所述石墨复合材料的取向度I 004/I 110为2.0～8.0。 Optionally, the orientation degree I 004 /I 110 of the graphite composite material is 2.0-8.0.
可选地，所述石墨复合材料的拉曼I D/I G为1.0～2.0。 Optionally, the Raman ID/ IG of the graphite composite material is 1.0-2.0 .
可选地，所述第一硬炭包覆层和所述第二硬炭包覆层两者的厚度为50nm～200nm。Optionally, the thickness of both the first hard carbon coating layer and the second hard carbon coating layer is 50 nm˜200 nm.
本公开还提供了一种石墨复合材料的制备方法，包括以下步骤：The present disclosure also provides a preparation method of the graphite composite material, comprising the following steps:
将石墨原料颗粒与含有碳骨架材料和聚合物的溶液混合造粒以在所述石墨原料颗粒表面形成第一聚合物前驱体包覆层，得到一次颗粒前驱体；Mixing and granulating the graphite raw material particles with a solution containing a carbon framework material and a polymer to form a first polymer precursor coating layer on the surface of the graphite raw material particles to obtain a primary particle precursor;
将所述一次颗粒前驱体和碳源混合，炭化后得到二次颗粒；mixing the primary particle precursor and the carbon source, and carbonizing to obtain secondary particles;
将所述二次颗粒和所述含有碳骨架材料和聚合物的溶液混合造粒以在所述二次颗粒表面形成第二聚合物前驱体包覆层，石墨化后得到石墨复合材料。The secondary particles and the solution containing the carbon skeleton material and the polymer are mixed and granulated to form a second polymer precursor coating layer on the surface of the secondary particles, and the graphite composite material is obtained after graphitization.
可选地，所述含有碳骨架材料和聚合物的溶液通过以下制备：将碳骨架材料和聚合物在溶剂中分散均匀，得到含有碳骨架材料和聚合物的溶液。Optionally, the solution containing the carbon skeleton material and the polymer is prepared by dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a solution containing the carbon skeleton material and the polymer.
可选地，所述碳骨架材料包括碳纳米管和碳纤维中的至少一种。Optionally, the carbon framework material includes at least one of carbon nanotubes and carbon fibers.
可选地，所述聚合物包括酚醛树脂、聚丙烯树脂及聚氨酯中的至少一种。Optionally, the polymer includes at least one of phenolic resin, polypropylene resin and polyurethane.
可选地，所述溶剂包括有机溶剂和水中的至少一种。Optionally, the solvent includes at least one of organic solvent and water.
可选地，所述聚合物前驱体的固含量为40％～60％。Optionally, the solid content of the polymer precursor is 40%-60%.
可选地，制备所述一次颗粒前驱体的步骤为：Optionally, the step of preparing the primary particle precursor is:
将所述聚合物前驱体喷洒至石墨原料颗粒表面；spraying the polymer precursor onto the surface of the graphite raw material particles;
翻滚所述石墨原料颗粒以在所述石墨原料颗粒表面形成第一聚合物前驱体包覆层；tumbling the graphite raw material particles to form a first polymer precursor coating layer on the surface of the graphite raw material particles;
干燥处理形成有第一聚合物前驱体包覆层的所述石墨原料颗粒。The graphite raw material particles formed with the first polymer precursor coating layer are dried.
可选地，所述石墨原料颗粒包括天然石墨微粒和软炭微粒中的至少一种。Optionally, the graphite raw material particles include at least one of natural graphite particles and soft carbon particles.
可选地，所述石墨原料颗粒的翻滚速度为5r/min～30r/min。Optionally, the tumbling speed of the graphite raw material particles is 5 r/min to 30 r/min.
可选地，所述干燥处理的温度80℃～95℃，时间为20min～40min。Optionally, the temperature of the drying treatment is 80°C to 95°C, and the time is 20 min to 40 min.
可选地，制备所述二次颗粒的步骤为：Optionally, the step of preparing the secondary particles is:
将碳源喷洒至所述一次颗粒前驱体表面；spraying a carbon source onto the surface of the primary particle precursor;
翻滚所述一次颗粒前驱体以使所述一次颗粒前驱体之间通过所述碳源粘结；tumbling the primary particle precursors to bond the primary particle precursors through the carbon source;
炭化处理粘结有所述碳源的所述一次颗粒前驱体。Carbonizing the primary particle precursor to which the carbon source is bound.
可选地，所述碳源包括易石墨化原料。Optionally, the carbon source includes easily graphitizable raw materials.
可选地，所述碳源包括沥青。Optionally, the carbon source includes pitch.
可选地，所述一次颗粒前驱体的翻滚速度为5r/min～30r/min。Optionally, the tumbling speed of the primary particle precursor is 5 r/min to 30 r/min.
可选地，所述炭化处理的温度450℃～750℃，时间为1h～5h。Optionally, the temperature of the carbonization treatment is 450°C to 750°C, and the time is 1 h to 5 h.
可选地，制备所述石墨复合材料的步骤为：Optionally, the step of preparing the graphite composite material is:
将所述聚合物前驱体喷洒至所述二次颗粒表面；spraying the polymer precursor onto the surface of the secondary particles;
翻滚所述二次颗粒以在所述二次颗粒表面形成第二聚合物前驱体包覆层；tumbling the secondary particles to form a second polymer precursor coating layer on the surfaces of the secondary particles;
石墨化处理形成有所述第二聚合物前驱体包覆层的所述二次颗粒。The secondary particles formed with the second polymer precursor coating layer are graphitized.
可选地，所述二次颗粒的粒径为13μm～24μm，粒度分布(D90-D10)/D50为0.75～1.0。Optionally, the particle size of the secondary particles is 13 μm˜24 μm, and the particle size distribution (D90-D10)/D50 is 0.75˜1.0.
可选地，所述二次颗粒的翻滚速度为5r/min～30r/min。Optionally, the tumbling speed of the secondary particles ranges from 5 r/min to 30 r/min.
可选地，所述石墨化处理的温度2400℃～3000℃，时间为1h～6h。Optionally, the temperature of the graphitization treatment is 2400° C.˜3000° C., and the time is 1 h˜6 h.
本公开还提供一种锂离子电池，所述锂离子电池包括上述的石墨复合材料；和/或，所述锂离子电池包括上述的制备方法制备而成的石墨复合材料。The present disclosure also provides a lithium-ion battery, the lithium-ion battery includes the above-mentioned graphite composite material; and/or, the lithium-ion battery includes the graphite composite material prepared by the above-mentioned preparation method.
附图说明Description of drawings
为了更清楚地说明本公开实施方式、实施例或现有技术中的技术方案，下面将对实施方式、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公开的一些实施方式、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示出的结构获得其他的附图。In order to more clearly illustrate the implementation manners, examples or technical solutions in the prior art of the present disclosure, the following briefly introduces the accompanying drawings that are required in the description of the implementation manners, examples or prior art. Obviously, the following The drawings in the description are only some embodiments and examples of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts. .
图1为本公开石墨复合材料的一些实施方式的结构示意图；1 is a schematic structural diagram of some embodiments of the disclosed graphite composite material;
图2为本公开石墨复合材料的制备方法的流程图；Fig. 2 is the flow chart of the preparation method of the disclosed graphite composite material;
图3为本公开石墨复合材料的制备方法的生产工艺图。FIG. 3 is a production process diagram of the preparation method of the disclosed graphite composite material.
附图标记：Reference number:
100-石墨复合材料，10-二次颗粒，11-一次颗粒，12-无定型炭，111-石墨，112-第一硬炭包覆层，20-第二硬炭包覆层。100-graphite composite material, 10-secondary particles, 11-primary particles, 12-amorphous carbon, 111-graphite, 112-first hard carbon coating, 20-second hard carbon coating.
本公开目的实现、功能特点及优点将结合实施方式和实施例，参照附图做进一步说明。The realization, functional features and advantages of the present disclosure will be further described with reference to the accompanying drawings in conjunction with the embodiments and examples.
具体实施方式Detailed ways
下面将对本公开实施方式和实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施方式和实施例仅仅是本公开的一部分实施方式和实施例，而不是全部的实施方式和实施例。基于本公开中的实施方式和实施例，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方式和实施例，都属于本公开保护的范围。The technical solutions in the implementation manners and examples of the present disclosure will be described clearly and completely below. Obviously, the described implementation manners and examples are only a part of implementation manners and examples of the present disclosure, rather than all implementation manners and implementations. example. Based on the implementations and examples in the present disclosure, all other implementations and examples obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present disclosure.
I.石墨复合材料的结构组成I. Structural composition of graphite composites
参见图1所示，在本公开一实施方式中，一种石墨复合材料100，石墨复合材料100为核壳结构，石墨复合材料100包括二次颗粒10内核和形成(包覆)于二次颗粒10内核表面的第二硬炭包覆层20；Referring to FIG. 1 , in an embodiment of the present disclosure, a graphite composite material 100 has a core-shell structure, and the graphite composite material 100 includes a core of secondary particles 10 and is formed (coated) on the secondary particles 10 a second hard carbon coating layer 20 on the surface of the inner core;
二次颗粒10包括一次颗粒11和无定型炭12，一次颗粒11包括石墨111和形成(包覆)于石墨111表面的第一硬炭包覆层112；The secondary particles 10 include primary particles 11 and amorphous carbon 12, and the primary particles 11 include graphite 111 and a first hard carbon coating layer 112 formed (coated) on the surface of the graphite 111;
第一硬炭包覆层112和第二硬炭包覆层20包括碳骨架材料。The first hard carbon coating layer 112 and the second hard carbon coating layer 20 include a carbon framework material.
本公开的技术方案，石墨复合材料100作为石墨负极材料时，由于石墨111具有高充放电容量的特质，以此提高了石墨负极材料的充放电容量。并且，第二硬炭包覆层20包覆于二次颗粒10内核表面，二次颗粒10包括一次颗粒11和无定型炭12，一次颗粒11中第一硬炭包覆层112包覆于石墨111表面，第二硬炭包覆层20和第一硬炭包覆层112作为硬炭材料所成型的结构，硬炭材料具有良好的快充性能，从而提高了石墨负极材料的快充性能。硬炭包覆层中的碳纳米管能提高电导率，稳定包覆层结构，降低材料的极化内阻。即本公开的技术方案能够在提高石墨负极材料的电容量的同时，提升石墨负极材料的快充性能。同时，由于颗粒内部的无定型炭在石墨化过程中，会收缩产生孔洞与裂缝，因此电解液会通过孔洞与裂缝进入颗粒内核，与内核颗粒直接接触，从而导致复合材料在循环过程中引起过度膨胀和收缩，从而降低电池的电化学性能，诸如快充性能、1C倍充保持率和50周容量保持率，由于本公开的石墨复合材料100中第一硬炭包覆层112、无定型炭12、第二硬炭包覆层20的结构，使得石墨复合材料100有效阻止了电解液与一次颗粒11的直接接触，进而有效保护了石墨复合材料100在电池循环过程中适当地膨胀和收缩，从而提高了本公开石墨复合材料100的电化学性能，诸如快充性能、1C倍充保持率和50周容量保持率。In the technical solution of the present disclosure, when the graphite composite material 100 is used as the graphite negative electrode material, since the graphite 111 has the characteristics of high charge and discharge capacity, the charge and discharge capacity of the graphite negative electrode material is improved. In addition, the second hard carbon coating layer 20 is coated on the surface of the inner core of the secondary particle 10, the secondary particle 10 includes the primary particle 11 and the amorphous carbon 12, and the first hard carbon coating layer 112 in the primary particle 11 is coated on graphite On the surface of 111 , the second hard carbon coating layer 20 and the first hard carbon coating layer 112 are formed by hard carbon material, and the hard carbon material has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. The carbon nanotubes in the hard carbon coating can improve the electrical conductivity, stabilize the structure of the coating, and reduce the polarization internal resistance of the material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material. At the same time, since the amorphous carbon inside the particle will shrink to generate pores and cracks during the graphitization process, the electrolyte will enter the particle core through the pores and cracks, and directly contact with the core particles, which will cause the composite material to cause excessive circulation during the cycle. expansion and contraction, thereby reducing the electrochemical performance of the battery, such as fast charge performance, 1C double charge retention rate and 50-cycle capacity retention rate, due to the first hard carbon coating layer 112, amorphous carbon in the graphite composite 100 of the present disclosure 12. The structure of the second hard carbon coating layer 20 enables the graphite composite material 100 to effectively prevent the direct contact between the electrolyte and the primary particles 11, thereby effectively protecting the graphite composite material 100 from proper expansion and contraction during battery cycling. Thus, the electrochemical properties of the graphite composite material 100 of the present disclosure, such as fast charge performance, 1C double charge retention rate, and 50-cycle capacity retention rate, are improved.
需要说明的是，在一些实施方式中，无定型炭12可以为软炭石墨化所形成的结构。在一些实施方式中，二次颗粒10可以包括一个一次颗粒11，也可以包括多个一次颗粒11。多个一次颗粒11包含于无定型炭12内，以此进一步提高了所制备石墨复合材料的容量。据信，不受理论的约束，第二硬炭包覆层20包覆于无定型炭12的表面，硬炭材料具有高电导，有效减少了充放电过程中的极化内阻，且硬炭包覆层能够加快充电时锂离子去溶剂化过程，使得锂离子能够快速嵌入到石墨中，因此能极大地提高石墨负极材料的快充性能。在本公开一实施方式中，碳骨架材料均匀分布在第一硬炭包覆层112和第二 硬炭包覆层20中。需要说明的是，本公开将碳骨架材料均匀分布在第一硬炭包覆层112和第二硬炭包覆层20中，碳骨架材料可以为碳纳米管，也可以为碳纤维，碳骨架材料具有高电导，以此减少了石墨复合材料100的充放电过程中的极化内阻，从而保证了石墨复合材料100的倍率性能和低温充放电性能。It should be noted that, in some embodiments, the amorphous carbon 12 may be a structure formed by graphitization of soft carbon. In some embodiments, the secondary particles 10 may include one primary particle 11 , or may include a plurality of primary particles 11 . A plurality of primary particles 11 are contained within the amorphous carbon 12, thereby further increasing the capacity of the prepared graphite composite material. It is believed, without being bound by theory, that the second hard carbon coating layer 20 coats the surface of the amorphous carbon 12, the hard carbon material has high electrical conductivity, effectively reduces the polarization internal resistance during charging and discharging, and the hard carbon The coating layer can speed up the desolvation process of lithium ions during charging, so that lithium ions can be quickly embedded in graphite, thus greatly improving the fast charging performance of graphite anode materials. In one embodiment of the present disclosure, the carbon framework material is uniformly distributed in the first hard carbon coating layer 112 and the second hard carbon coating layer 20. It should be noted that, in the present disclosure, the carbon skeleton material is evenly distributed in the first hard carbon coating layer 112 and the second hard carbon coating layer 20, and the carbon skeleton material can be carbon nanotubes, or carbon fiber, carbon skeleton material. It has high conductivity, thereby reducing the polarization internal resistance during the charging and discharging process of the graphite composite material 100, thereby ensuring the rate performance and low temperature charging and discharging performance of the graphite composite material 100.
在本公开一实施方式中，以第一硬炭包覆层112的质量为100％计，第一硬炭包覆层中的碳骨架材料的含量为1％～10％，例如1％～8％、2％～10％或2％～8％，诸如1％、2％、3％、4％、5％、6％、7％、8％、9％、10％。在一些实施方式中，以第一硬炭包覆层112的质量为100％计，均匀分布在第一硬炭包覆层中的碳骨架材料的含量为1％～10％。需要说明的是，本公开通过调节碳骨架材料的含量，使得所形成的第一硬炭包覆层112在实现对石墨111表面均匀包覆的同时，进一步提高了第一硬炭包覆层112的电导率，减少了石墨复合材料100的充放电过程中的极化内阻，以此保证了石墨复合材料100的倍率性能和低温充放电性能。In an embodiment of the present disclosure, based on the mass of the first hard carbon coating layer 112 as 100%, the content of the carbon framework material in the first hard carbon coating layer is 1% to 10%, for example, 1% to 8%. %, 2%-10% or 2%-8%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. In some embodiments, based on 100% of the mass of the first hard carbon coating layer 112 , the content of the carbon framework material uniformly distributed in the first hard carbon coating layer is 1% to 10%. It should be noted that, in the present disclosure, by adjusting the content of the carbon skeleton material, the first hard carbon coating layer 112 can be formed to uniformly coat the surface of the graphite 111, and at the same time, the first hard carbon coating layer 112 can be further improved. The electrical conductivity of the graphite composite material 100 is high, which reduces the polarization internal resistance during the charging and discharging process of the graphite composite material 100, thereby ensuring the rate performance and low temperature charging and discharging performance of the graphite composite material 100.
在本公开一实施方式中，以第二硬炭包覆层20的质量为100％计，第二硬炭包覆层中的碳骨架材料的含量为1％～10％，例如2％～6％、1％～9％或2％～7％，诸如1％、1.5％、2.5％、3.5％、4.5％、5.5％、6.5％、7.5％、8.5％、9.5％、10％。在一些实施方式中，以第二硬炭包覆层20的质量为100％计，均匀分布在第二硬炭包覆层中的碳骨架材料的含量为1％～10％。同理，本公开通过调节碳骨架材料的含量，使得所形成的第二硬炭包覆层20在实现对二次颗粒10表面均匀包覆的同时，进一步提高了第二硬炭包覆层20的电导率，减少了石墨复合材料100的充放电过程中的极化内阻，以此保证了石墨复合材料的倍率性能和低温充放电性能。In an embodiment of the present disclosure, based on the mass of the second hard carbon coating layer 20 as 100%, the content of the carbon framework material in the second hard carbon coating layer is 1% to 10%, for example, 2% to 6%. %, 1%-9% or 2%-7%, such as 1%, 1.5%, 2.5%, 3.5%, 4.5%, 5.5%, 6.5%, 7.5%, 8.5%, 9.5%, 10%. In some embodiments, based on 100% of the mass of the second hard carbon coating layer 20, the content of the carbon framework material uniformly distributed in the second hard carbon coating layer is 1% to 10%. Similarly, in the present disclosure, by adjusting the content of the carbon skeleton material, the formed second hard carbon coating layer 20 further improves the second hard carbon coating layer 20 while achieving uniform coating on the surface of the secondary particles 10 . The electrical conductivity of the graphite composite material 100 is high, which reduces the polarization internal resistance during the charging and discharging process of the graphite composite material 100, thereby ensuring the rate performance and low temperature charging and discharging performance of the graphite composite material.
II.石墨复合材料的材料组成II. MATERIAL COMPOSITION OF GRAPHITE COMPOSITES
在本公开一实施方式中，石墨111包括人造石墨和天然石墨中的至少一种。需要说明的是，石墨111可以为天然石墨，也可以为软炭材料石墨化所制成的人造石墨，以上两种石墨均具有高充放电容量的特质，保证了石墨复合材料100的充放电容量。In an embodiment of the present disclosure, the graphite 111 includes at least one of artificial graphite and natural graphite. It should be noted that the graphite 111 can be natural graphite or artificial graphite made by graphitization of soft carbon material. Both of the above two kinds of graphite have the characteristics of high charge and discharge capacity, which ensures the charge and discharge capacity of the graphite composite material 100 .
在本公开一实施方式中，无定型炭12包括软炭。需要说明的是，本公开在一次颗粒11表面包覆软炭，减少了一次颗粒11表面的缺陷，在后续石墨化处理中，使得制备的球形颗粒更加密实，从而提高了石墨复合材料100的振实和压实性能，更重要的一点是能够抑制一次颗粒11在高温炭化过程中体积膨胀，防止二次颗粒10在石墨化过程中的变形。In one embodiment of the present disclosure, the amorphous carbon 12 includes soft carbon. It should be noted that the present disclosure coats the surface of the primary particles 11 with soft carbon, which reduces the defects on the surface of the primary particles 11 , and in the subsequent graphitization treatment, makes the prepared spherical particles more compact, thereby improving the vibration of the graphite composite material 100 . In terms of compaction and compaction performance, the more important point is that the volume expansion of the primary particles 11 can be suppressed during the high-temperature carbonization process, and the deformation of the secondary particles 10 during the graphitization process can be prevented.
在本公开一实施方式中，无定型炭填充在一次颗粒11之间。在本公开一实施方式中，一次颗粒之间填充有所述无定型炭。需要说明的是，由于第二硬炭包覆层20与第一硬炭包覆层112具有乱层炭结构，且碳原子层间距比较大，本公开实施方式通过将无定型炭12夹设于第二硬炭包覆层20与第一硬炭包覆层112之间，如此，使得锂离子能够快速嵌入嵌出，提升了石墨复合材料的倍率性能以及低温环境下的充放电性能。In an embodiment of the present disclosure, amorphous carbon is filled between the primary particles 11 . In an embodiment of the present disclosure, the amorphous carbon is filled between primary particles. It should be noted that, since the second hard carbon coating layer 20 and the first hard carbon coating layer 112 have a turbostratic carbon structure, and the carbon atomic layer spacing is relatively large, in the embodiment of the present disclosure, the amorphous carbon 12 is sandwiched between Between the second hard carbon coating layer 20 and the first hard carbon coating layer 112 , in this way, lithium ions can be rapidly inserted and inserted, which improves the rate performance of the graphite composite material and the charge-discharge performance in a low temperature environment.
在本公开一实施方式中，碳骨架材料选自碳纳米管和碳纤维中的至少一种。需要说明的是，碳纳米管和碳纤维具有高电导，提升了硬炭包覆层的电导率，以此减少了石墨复合材料的充放电过程中的极化内阻，从而保证了石墨复合材料的倍率性能和低温充放电性能。In an embodiment of the present disclosure, the carbon skeleton material is selected from at least one of carbon nanotubes and carbon fibers. It should be noted that carbon nanotubes and carbon fibers have high electrical conductivity, which improves the electrical conductivity of the hard carbon coating layer, thereby reducing the polarization internal resistance during the charging and discharging process of the graphite composite material, thereby ensuring the graphite composite material. Rate performance and low temperature charge-discharge performance.
在本公开一实施方式中，第一硬炭包覆层112由碳骨架材料和聚合物的混合物炭化而成。需要说明的是，碳骨架材料包括碳纳米管和碳纤维，碳纳米管和碳纤维具有高电导，以此减少了石墨复合材料的充放电过程中的极化内阻，从而保证了石墨复合材料100的倍率性能和低温充放电性能。该聚合物可以为能溶于有机溶剂，室温下(约15℃～30℃)液态，含碳量≥15％(质量百分比)的聚合物，诸如树脂类聚合物或聚氨酯类聚合物。In an embodiment of the present disclosure, the first hard carbon coating layer 112 is formed by carbonization of a mixture of carbon skeleton material and polymer. It should be noted that the carbon skeleton material includes carbon nanotubes and carbon fibers, and carbon nanotubes and carbon fibers have high electrical conductivity, thereby reducing the polarization internal resistance during the charging and discharging process of the graphite composite material, thereby ensuring the graphite composite material 100. Rate performance and low temperature charge-discharge performance. The polymer can be soluble in organic solvents, liquid at room temperature (about 15°C to 30°C), and carbon content ≥ 15% (mass percent), such as resin-based polymers or polyurethane-based polymers.
在本公开一实施方式中，第二硬炭包覆层20由碳骨架材料和聚合物的混合物炭化而成。需要说明的是，碳骨架材料包括碳纳米管和碳纤维，碳纳米管和碳纤维具有高电导，提升了硬炭壳电导率以此减少了石墨复合材料的充放电过程中的极化内阻，从而保证了石墨复合材料100的倍率性能和低温充放电性能。该聚合物可以为能溶于有机溶剂，室温下(约15℃～30℃)液态，含碳量≥15％(质量百分比)的聚 合物，诸如树脂类聚合物或聚氨酯类聚合物。In an embodiment of the present disclosure, the second hard carbon coating layer 20 is formed by carbonization of a mixture of carbon skeleton material and polymer. It should be noted that the carbon skeleton material includes carbon nanotubes and carbon fibers. Carbon nanotubes and carbon fibers have high electrical conductivity, which improves the electrical conductivity of the hard carbon shell and reduces the polarization internal resistance during the charging and discharging process of the graphite composite material, thereby The rate performance and low-temperature charge-discharge performance of the graphite composite material 100 are guaranteed. The polymer can be soluble in organic solvents, liquid at room temperature (about 15°C to 30°C), and carbon content ≥ 15% (mass percent), such as resin polymers or polyurethane polymers.
在本公开一实施方式中，无定型炭12由沥青石墨化而成。需要说明的是，无定型炭12填充于第二硬炭包覆层20和第一硬炭包覆层112之间，无定型炭12通过沥青石墨化而成型得到，在沥青石墨化之前，沥青充当于粘结剂，沥青具有一定的流动性，以此使得沥青填充于第二硬炭包覆层20与第一硬炭包覆层112的缺陷内，减少硬炭包覆层比表面积，增加了二次颗粒10造粒效果，使得二次颗粒10更加球形化，降低材料OI取向，保证了石墨复合材料的高首效、低膨胀性和倍率性能。并且，在后续石墨化处理的过程中，沥青作为填充层变形小，以此提高了石墨复合材料100的密实性，提高材料振实和压实性能，改善了其涂布加工性能。更重要的是，无定型炭12将包覆有第一硬炭包覆层112的石墨111包覆，以此使得第一硬炭包覆层112包覆于无定型炭12的内部，从而避免了成型第一硬炭包覆层112的聚合物在石墨化处理的过程中发生体积膨胀，防止了所制备石墨复合材料100发生变形。In an embodiment of the present disclosure, the amorphous carbon 12 is graphitized from pitch. It should be noted that the amorphous carbon 12 is filled between the second hard carbon coating layer 20 and the first hard carbon coating layer 112, and the amorphous carbon 12 is formed by pitch graphitization. Before the pitch graphitization, the pitch Acting as a binder, the pitch has a certain fluidity, so that the pitch is filled in the defects of the second hard carbon coating layer 20 and the first hard carbon coating layer 112, reducing the specific surface area of the hard carbon coating layer and increasing the The granulation effect of the secondary particles 10 is improved, the secondary particles 10 are more spherical, the OI orientation of the material is reduced, and the high first efficiency, low expansion and rate performance of the graphite composite material are ensured. In addition, in the subsequent graphitization process, the asphalt serves as a filling layer with little deformation, thereby improving the compactness of the graphite composite material 100, improving the material's vibrating and compacting properties, and improving its coating processability. More importantly, the amorphous carbon 12 coats the graphite 111 coated with the first hard carbon coating layer 112, so that the first hard carbon coating layer 112 is coated inside the amorphous carbon 12, thereby avoiding The volume expansion of the polymer used to form the first hard carbon coating layer 112 during the graphitization process prevents the prepared graphite composite material 100 from being deformed.
在本公开一实施方式中，无定型炭12由易石墨化原料经石墨化而成。在一些实施方式中，易石墨化原料可以为沥青、石油焦、无烟煤，沥青焦，煤系焦、树脂、油脂、烷烃、烯烃、炔烃和芳烃中的至少一种。例如，沥青选自煤沥青、石油沥青、中间相沥青或改质沥青中的至少一种。其中，在上下文中，“易石墨化原料”主要是指在高温下诸如≥2000℃容易转化成石墨的无定形碳的原料。In an embodiment of the present disclosure, the amorphous carbon 12 is formed by graphitization of easily graphitizable raw materials. In some embodiments, the easily graphitizable raw material may be at least one of pitch, petroleum coke, anthracite, pitch coke, coal-based coke, resin, grease, alkane, alkene, alkyne, and aromatic hydrocarbon. For example, the pitch is selected from at least one of coal pitch, petroleum pitch, mesophase pitch, or modified pitch. Wherein, in the context, "easy graphitization raw material" mainly refers to a raw material of amorphous carbon that is easily converted into graphite at high temperature such as ≥2000°C.
在一些实施方式中，软炭由易石墨化原料经石墨化而成。在一些实施方式中，易石墨化原料可以为沥青、石油焦、无烟煤，沥青焦，煤系焦、树脂、油脂、烷烃、烯烃、炔烃和芳烃中的至少一种。例如，树脂可以选自环氧树脂或酚醛树脂中的一种。例如，沥青选自煤沥青、石油沥青、中间相沥青或改质沥青中的至少一种。In some embodiments, the soft carbon is graphitized from readily graphitizable raw materials. In some embodiments, the easily graphitizable raw material may be at least one of pitch, petroleum coke, anthracite, pitch coke, coal-based coke, resin, grease, alkane, alkene, alkyne, and aromatic hydrocarbon. For example, the resin may be selected from one of epoxy resins or phenolic resins. For example, the pitch is selected from at least one of coal pitch, petroleum pitch, mesophase pitch, or modified pitch.
III.石墨复合材料的性能特征III. Properties of graphite composites
在本公开一实施方式中，第一硬炭包覆层112由碳骨架材料和聚合物的混合物炭化而成；第二硬炭包覆层20由碳骨架材料和聚合物的混合物炭化而成，碳骨架材料包括纳米纤维和碳纳米管中的至少一种。在一些实施方式中，第一硬炭包覆层112的单位截面积中所含碳骨架材料的数量为2根/μm 2～5根/μm 2，例如2根/μm 2、3根/μm 2、4根/μm 2、5根/μm 2。在一些实施方式中，第二硬炭包覆层20的单位截面积中所含碳骨架材料的数量为2根/μm 2～5根/μm 2，例如2根/μm 2、3根/μm 2、4根/μm 2、5根/μm 2。 In an embodiment of the present disclosure, the first hard carbon coating layer 112 is formed by carbonization of a mixture of carbon framework material and polymer; the second hard carbon coating layer 20 is formed by carbonization of a mixture of carbon framework material and polymer, The carbon skeleton material includes at least one of nanofibers and carbon nanotubes. In some embodiments, the number of carbon framework materials contained in the unit cross-sectional area of the first hard carbon coating layer 112 is 2 pieces/μm 2 to 5 pieces/μm 2 , for example, 2 pieces/μm 2 , 3 pieces/μm 2 , 4 pieces/μm 2 , 5 pieces/μm 2 . In some embodiments, the amount of carbon framework material contained in the unit cross-sectional area of the second hard carbon coating layer 20 is 2 pieces/μm 2 to 5 pieces/μm 2 , for example, 2 pieces/μm 2 , 3 pieces/μm 2 , 4 pieces/μm 2 , 5 pieces/μm 2 .
碳骨架材料的界面(例如硬炭包覆层界面)百分比(在本公开上下文中由A表示)，即在碳骨架材料在包覆层界面中，碳骨架材料的能起增加包覆层强度与韧性的有效接触面积的百分比，同时表征碳骨架在聚合物分散均匀程度，已知碳骨架材料诸如碳纳米管或碳纤维，当其分散在界面上，碳骨架材料个体与个体之间主要呈现无序状态，碳骨架材料可以嵌入界面中(例如碳骨架材料的长径比较大)或整体分散在界面上(例如碳骨架材料的长径比较小)；The percentage of the interface (eg hard carbon cladding interface) of the carbon framework material (represented by A in the context of this disclosure), ie in the carbon framework material at the cladding interface, the carbon framework material's ability to increase the cladding strength and the The percentage of the effective contact area of toughness, which also characterizes the uniformity of the carbon skeleton in the polymer dispersion. It is known that carbon skeleton materials such as carbon nanotubes or carbon fibers, when they are dispersed on the interface, the carbon skeleton material is mainly disordered between individuals. state, the carbon framework material can be embedded in the interface (for example, the aspect ratio of the carbon framework material is large) or dispersed on the interface as a whole (for example, the aspect ratio of the carbon framework material is small);
A的范围为10％～60％，A的范围可以为例如25％～60％、25％～50％或20％～55％，诸如10％、15％、20％、25％、30％、35％、40％、45％、50％、55％、60％。A的范围选择在10％-60％的范围内，可以保证碳骨架材料的均匀分散性，同时可以增加包覆层强度与韧性，提高材料的强度和电导率，从而提高电池快充能力和循环性能。当A＜10％，代表碳骨架材料起增强强度的有效接触面积较小，同时碳骨架材料含量过少以及分散不均匀，则会影响材料强度和电导率，导致电池快充能力和循环性能下降；当A＞60％，代表碳骨架材料含量过多，代表同时碳骨架材料起增强强度的有效接触面积较大，同时导致材料强度太大和比表面积过高，则会影响电池能量密度；The range of A is 10% to 60%, the range of A may be, for example, 25% to 60%, 25% to 50% or 20% to 55%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%. The range of A is selected in the range of 10%-60%, which can ensure the uniform dispersion of the carbon skeleton material, and at the same time can increase the strength and toughness of the coating layer, and improve the strength and conductivity of the material, thereby improving the battery fast charging capacity and cycle. performance. When A<10%, it means that the effective contact area of the carbon skeleton material to enhance the strength is small. At the same time, the content of the carbon skeleton material is too small and the dispersion is uneven, which will affect the strength and conductivity of the material, resulting in a decrease in the fast charging capacity and cycle performance of the battery. ; When A > 60%, it means that the content of carbon skeleton material is too much, which means that the effective contact area of carbon skeleton material to enhance the strength is large at the same time, and at the same time, the material strength is too large and the specific surface area is too high, which will affect the energy density of the battery;
碳骨架材料的界面(例如硬炭包覆层界面)百分比(A)和硬炭包覆层的单位截面积中所含碳骨架材料的数量(n)、硬炭包覆层的硬度之间的关系可以由以下公式表示：The difference between the percentage (A) of the interface of the carbon framework material (for example, the interface of the hard carbon coating layer), the number of carbon framework materials contained in the unit cross-sectional area of the hard carbon coating layer (n), and the hardness of the hard carbon coating layer. The relationship can be represented by the following formula:
A＝H/(n×0.7)        公式(1)；A=H/(n×0.7) Formula (1);
其中，n为对应上文所述的硬炭包覆层的单位截面积的所含碳骨架材料的数量；Wherein, n is the quantity of the carbon skeleton material contained in the unit cross-sectional area of the hard carbon coating layer described above;
H表示对应硬炭包覆层的硬度；H represents the hardness of the corresponding hard carbon coating;
0.7为强度系数，表示碳骨架对壳层正面抗压强度增益系数为0.7。0.7 is the strength coefficient, indicating that the gain coefficient of the carbon skeleton to the frontal compressive strength of the shell is 0.7.
一些实施方式中，在第一硬炭包覆层中，碳骨架材料的界面百分比A为10％～60％，其中A＝H/(n×0.7)，n为第一硬炭包覆层的单位截面积中所含碳骨架材料的数量，H为第一硬炭包覆层的硬度。In some embodiments, in the first hard carbon coating layer, the interface percentage A of the carbon framework material is 10% to 60%, wherein A=H/(n×0.7), and n is the first hard carbon coating layer. The amount of carbon framework material contained in a unit cross-sectional area, and H is the hardness of the first hard carbon coating layer.
在一些实施方式中，在第二硬炭包覆层中，碳骨架材料的界面百分比A为10％～60％，其中A＝H/(n×0.7)，n为第二硬炭包覆层的单位截面积中所含碳骨架材料的数量，H为第二硬炭包覆层的硬度。In some embodiments, in the second hard carbon coating layer, the interface percentage A of the carbon framework material is 10%-60%, wherein A=H/(n×0.7), and n is the second hard carbon coating layer The quantity of carbon framework material contained in the unit cross-sectional area of , H is the hardness of the second hard carbon coating layer.
在一些实施方式中，n可以直接测量得出，或者也可以通过下文所述的硬度范围推导得出。In some embodiments, n can be measured directly, or can be derived from the hardness ranges described below.
在本公开中，通过上述公式推导得出的n或者上述实施方式中n的范围不仅使得碳骨架材料分散均匀，而且有效提升了硬炭包覆层的电导率，进而保证了石墨复合材料100的倍率性能(诸如1C倍充保持率)和低温充放电性能；同时该数量也可以满足对应炭包覆层的厚度和硬度。In the present disclosure, n derived from the above formula or the range of n in the above embodiment not only makes the carbon skeleton material evenly dispersed, but also effectively improves the electrical conductivity of the hard carbon coating layer, thereby ensuring the performance of the graphite composite material 100 Rate performance (such as 1C charge retention rate) and low-temperature charge-discharge performance; at the same time, this quantity can also satisfy the thickness and hardness of the corresponding carbon coating layer.
在本公开一实施方式中，碳骨架材料的长径比为200～5000，例如可以为300～5000、200～4000或500～5000，诸如200、500、1000、1500、2000、2500、3000、3500、4000、4500或5000。本公开的碳骨架材料的长径比在上述范围内，可以进一步保证碳骨架材料的高电子电导和一定的包覆层强度，进一步提供材料的快充和循环性能；同时可以进一步提高碳骨架材料在聚合物溶液中的分散效果，从而提高石墨复合材料的循环性能。而如果碳骨架材料的长径比过小，则碳骨架材料的电子电导太低以及导致包覆层强度太低，影响石墨复合材料快充和循环性能；如果长径比过大，则影响碳骨架材料在聚合物溶液中的分散效果，容易团聚，会导致包覆层强度不均匀，故影响石墨复合材料的循环性能。In an embodiment of the present disclosure, the aspect ratio of the carbon framework material is 200-5000, for example, it can be 300-5000, 200-4000 or 500-5000, such as 200, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 or 5000. The aspect ratio of the carbon skeleton material of the present disclosure is within the above range, which can further ensure the high electronic conductivity and a certain coating layer strength of the carbon skeleton material, and further improve the fast charging and cycle performance of the material; at the same time, the carbon skeleton material can be further improved. Dispersion effect in polymer solution, thereby improving the cycling performance of graphite composites. However, if the aspect ratio of the carbon skeleton material is too small, the electronic conductivity of the carbon skeleton material will be too low and the strength of the coating layer will be too low, which will affect the fast charging and cycle performance of the graphite composite; if the aspect ratio is too large, it will affect the carbon The dispersion effect of the skeleton material in the polymer solution is easy to agglomerate, which will lead to uneven strength of the coating layer, thus affecting the cycle performance of the graphite composite material.
在本公开一实施方式中，第一硬炭包覆层112和第二硬炭包覆层20两者各自的硬度可以为50N/mm 2～100N/mm 2，例如硬度为60N/mm 2～100N/mm 2、65N/mm 2～90N/mm 2或65N/mm 2～85N/mm 2，诸如51N/mm 2、55N/mm 2、60N/mm 2、65N/mm 2、70N/mm 2、75N/mm 2、80N/mm 2、85N/mm 2、90N/mm 2、95N/mm 2、99N/mm 2、100N/mm 2。 In an embodiment of the present disclosure, the respective hardnesses of the first hard carbon coating layer 112 and the second hard carbon coating layer 20 may be 50 N/mm 2 to 100 N/mm 2 , for example, the hardness is 60 N/mm 2 to 60 N/mm 2 . 100N/ mm2 , 65N/ mm2 ～90N/ mm2 or 65N/ mm2 ～85N/ mm2 , such as 51N/ mm2 , 55N/ mm2 , 60N/ mm2 , 65N/ mm2 , 70N/ mm2 , 75N/mm 2 , 80N/mm 2 , 85N/mm 2 , 90N/mm 2 , 95N/mm 2 , 99N/mm 2 , 100N/mm 2 .
本公开的第一硬炭包覆层112和第二硬炭包覆层20两者在上述范围内，可以进一步提高复合材料的电池循环性能、电池充电速率以及保证电池的整体能量密度。若包覆层硬度＜50N/mm 2，包覆层难以抑制颗粒内核在嵌锂过程中的发生的体积膨胀，颗粒容易破碎，则性能表现为电池循环性能变差；若包覆层硬度＞100N/mm 2，表示包覆层过于致密，影响了电解液的渗透速率，则会影响电池充电速率，再者，包覆层过硬，导致材料压实密度降低，影响电池的整体能量密度。本公开在制备复合材料的过程中，聚合物前驱体的固含量、对应硬炭包覆层的单位截面积中所含碳骨架材料的数量是影响包覆层硬度的主要因素。 Both the first hard carbon coating layer 112 and the second hard carbon coating layer 20 of the present disclosure are within the above ranges, which can further improve the battery cycle performance of the composite material, the battery charging rate, and ensure the overall energy density of the battery. If the hardness of the coating layer is less than 50N/mm 2 , it is difficult for the coating layer to suppress the volume expansion of the particle core during the lithium intercalation process, and the particles are easily broken, resulting in poor battery cycle performance; if the hardness of the coating layer is greater than 100N /mm 2 , which means that the coating layer is too dense, which affects the penetration rate of the electrolyte, which will affect the charging rate of the battery. Furthermore, the coating layer is too hard, which reduces the compaction density of the material and affects the overall energy density of the battery. In the process of preparing the composite material of the present disclosure, the solid content of the polymer precursor and the amount of carbon skeleton material contained in the unit cross-sectional area of the corresponding hard carbon coating layer are the main factors affecting the hardness of the coating layer.
在本公开一实施方式中，石墨复合材料100的电导率为200S/m～400S/m，例如2300S/m～400S/m、200S/m～3600S/m或280S/m～320S/m，诸如200S/m、220S/m、240S/m、260S/m、280S/m、300S/m、320S/m、340S/m、360S/m、380S/m、400S/m；In an embodiment of the present disclosure, the electrical conductivity of the graphite composite material 100 is 200S/m˜400S/m, such as 2300S/m˜400S/m, 200S/m˜3600S/m, or 280S/m˜320S/m, such as 200S/m, 220S/m, 240S/m, 260S/m, 280S/m, 300S/m, 320S/m, 340S/m, 360S/m, 380S/m, 400S/m;
本公开的石墨复合材料100的电导率在上述范围内，可以进一步提高复合材料的充放电容量，提高了1C倍充保持率，若电导率过低，则会使得1C倍充保持率降低，若电导率过大，则说明碳骨架材料包覆过多(即硬炭包覆层过厚)，则会影响电池容量和首次库伦效率下降。If the electrical conductivity of the graphite composite material 100 of the present disclosure is within the above range, the charge-discharge capacity of the composite material can be further improved, and the 1C double charge retention rate can be improved. If the electrical conductivity is too low, the 1C double charge retention rate will be reduced. If the electrical conductivity is too large, it means that the carbon skeleton material is covered too much (that is, the hard carbon coating layer is too thick), which will affect the battery capacity and decrease the first Coulomb efficiency.
在本公开一实施方式中，石墨复合材料100的中值粒度D50为13μm～24μm，粒度分布(D90-D10)/D50为0.75～1.0。石墨复合材料100的中值粒度在以上范围内，可以进一步保证材料的较高的首次库伦效率与快充性能。而如果材料的中值粒径过大，会增加Li+在材料中的迁移距离，影响材料的快充性能；粒径过小，同时使得产品的比表面积更大，材料压实密度下降，造成电池能量密度下降。In an embodiment of the present disclosure, the median particle size D50 of the graphite composite material 100 is 13 μm˜24 μm, and the particle size distribution (D90-D10)/D50 is 0.75˜1.0. The median particle size of the graphite composite material 100 is within the above range, which can further ensure higher first Coulomb efficiency and fast charging performance of the material. If the median particle size of the material is too large, it will increase the migration distance of Li+ in the material and affect the fast charging performance of the material; if the particle size is too small, the specific surface area of the product will be larger, and the compaction density of the material will decrease, causing the battery The energy density drops.
在本公开一实施方式中，石墨复合材料100的比表面积为0.8m 2/g～2.0m 2/g。石墨复合材料100的比表面积在上述范围内，可以进一步保证较高的首次库伦效率和1C倍充保持率，比表面积过大，则会降低首次库伦效率，比表面积过小，则1C倍充保持率较差。 In an embodiment of the present disclosure, the specific surface area of the graphite composite material 100 is 0.8 m 2 /g˜2.0 m 2 /g. The specific surface area of the graphite composite material 100 is within the above range, which can further ensure higher first coulombic efficiency and 1C double charge retention rate. If the specific surface area is too large, the first coulomb efficiency will be reduced, and if the specific surface area is too small, the 1C double charge retention rate will be maintained. rate is poor.
在本公开一实施方式中，石墨复合材料100在1.0g/cm 3～2.0g/cm 3的压实密度下，取向度I 004/I 110峰面积比为2.0～8.0。石墨复合材料100的取向度在上述范围内，可以进一步保证较高的1C倍充保持率和50周容量保持率。若取向度过大则容易造成材料膨胀率偏大，从而50周容量保持率。下文中石墨原料 颗粒的大小以及造粒程度是影响石墨复合材料100的取向度的主要因素。 In an embodiment of the present disclosure, the graphite composite material 100 has a peak area ratio of the orientation degree I 004 /I 110 of 2.0 to 8.0 at a compaction density of 1.0 g/cm 3 to 2.0 g/cm 3 . The orientation degree of the graphite composite material 100 is within the above range, which can further ensure a higher 1C double charge retention rate and a 50-cycle capacity retention rate. If the orientation is too large, it is easy to cause the material expansion rate to be too large, and thus the 50-cycle capacity retention rate. Hereinafter, the size of the graphite raw material particles and the degree of granulation are the main factors affecting the degree of orientation of the graphite composite material 100 .
在本公开一实施方式中，石墨复合材料100的拉曼I D/I G为1.0～2.0。 In an embodiment of the present disclosure, the Raman ID/ IG of the graphite composite material 100 is 1.0˜2.0 .
在本公开一实施方式中，第一硬炭包覆层112和第二硬炭包覆层20两者的厚度为50nm～200nm。In an embodiment of the present disclosure, the thickness of both the first hard carbon coating layer 112 and the second hard carbon coating layer 20 is 50 nm˜200 nm.
石墨复合材料100的厚度在上述范围内，可以进一步保证材料的电池循环性能和提高材料的1C倍充保持率。若石墨复合材料100的厚度过薄，则包覆层难以抑制颗粒内核在嵌锂过程中的发生的体积膨胀，颗粒容易破碎，从而导致电池循环性能变差；若包覆层过厚，则包覆层过于致密，影响了电解液的渗透速率，从而影响材料1C倍充保持率，同时，包覆层过厚，则导致材料压实密度降低，影响电池的整体能量密度。本公开在制备复合材料的过程中，聚合物前驱体的固含量和处理时间是影响包覆层硬度的主要因素。When the thickness of the graphite composite material 100 is within the above range, the battery cycle performance of the material can be further ensured and the 1C double charge retention rate of the material can be improved. If the thickness of the graphite composite material 100 is too thin, it is difficult for the coating layer to suppress the volume expansion of the particle core during the lithium intercalation process, and the particles are easily broken, resulting in poor battery cycle performance; if the coating layer is too thick, the coating If the coating is too dense, it affects the penetration rate of the electrolyte, thereby affecting the 1C double charge retention rate of the material. At the same time, if the coating is too thick, the compaction density of the material is reduced, which affects the overall energy density of the battery. In the process of preparing the composite material of the present disclosure, the solid content of the polymer precursor and the treatment time are the main factors affecting the hardness of the coating layer.
IV.石墨复合材料的制备方法IV. Preparation method of graphite composite material
参见图2所示，在本公开一实施方式中，一种石墨复合材料的制备方法，包括以下步骤：S10、将碳骨架材料和聚合物在溶剂中分散均匀，得到聚合物前驱体(即含有碳骨架材料和聚合物的溶液)；S20、将石墨原料颗粒和聚合物前驱体混合造粒以在石墨原料颗粒表面形成第一聚合物前驱体包覆层，得到一次颗粒前驱体；S30、将一次颗粒前驱体和碳源混合，炭化后得到二次颗粒；S40、将二次颗粒和聚合物前驱体混合造粒以在二次颗粒表面形成第二聚合物前驱体包覆层，石墨化后得到石墨复合材料。需要说明的是，本公开可以通过高温石墨化使得在石墨表面形成第一硬炭包覆层实现一次颗粒的制备，在高温石墨化的同时，一次颗粒表面的碳源形成软炭实现二次颗粒的制备，并且，二次颗粒表面形成第二硬炭包覆层，以此实现石墨复合材料的制备。补充说明，通过石墨化处理，二次颗粒的石墨化程度达到93％以上，提高了石墨复合材料的充放电容量。Referring to Fig. 2, in an embodiment of the present disclosure, a method for preparing a graphite composite material includes the following steps: S10, dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a polymer precursor (that is, containing solution of carbon framework material and polymer); S20, mixing and granulating graphite raw material particles and polymer precursors to form a first polymer precursor coating layer on the surfaces of the graphite raw material particles to obtain primary particle precursors; S30, granulating The primary particle precursor and the carbon source are mixed, and the secondary particles are obtained after carbonization; S40, the secondary particles and the polymer precursor are mixed and granulated to form a coating layer of the second polymer precursor on the surface of the secondary particles, and after graphitization A graphite composite material is obtained. It should be noted that the present disclosure can form a first hard carbon coating layer on the surface of graphite to realize the preparation of primary particles through high-temperature graphitization, and at the same time of high-temperature graphitization, the carbon source on the surface of the primary particles forms soft carbon to realize secondary particles and the second hard carbon coating layer is formed on the surface of the secondary particles, so as to realize the preparation of the graphite composite material. It is added that through the graphitization treatment, the degree of graphitization of the secondary particles reaches more than 93%, which improves the charge-discharge capacity of the graphite composite.
步骤S10：Step S10:
在本公开一实施方式中，所述含有碳骨架材料和聚合物的溶液通过以下制备：将碳骨架材料和聚合物在溶剂中分散均匀，得到含有碳骨架材料和聚合物的溶液。在本公开一实施方式中，碳骨架材料包括碳纳米管和碳纤维中的至少一种。在本公开一实施方式中，聚合物包括酚醛树脂、聚丙烯树脂及聚氨酯中的至少一种。在本公开一实施方式中，溶剂包括有机溶剂和水中的至少一种。在本公开一实施方式中，将碳骨架材料和聚合物在有机溶剂中分散均匀，得到含有碳骨架材料和聚合物的溶液。在本公开一实施方式中，有机溶剂包括乙醇和水中的至少一种。在本公开一实施方式中，聚合物前驱体的固含量为40％～60％，例如固含量为40％～50％、50％～60％或45％～60％，诸如40％、42％、44％、46％、48％、50％、52％、54％、56％、58％、60％。在本公开一实施方式中，将碳骨架材料和聚合物加入到有机溶液中并进行搅拌，以使碳骨架材料和聚合物分散于有机溶剂。在本公开一实施方式中，碳骨架材料可以为碳纳米管和碳纤维。在本公开一实施方式中，碳纳米管和碳纤维的长度为100nm～300nm，管径为5nm～10nm。在本公开一实施方式中，碳骨架材料与聚合物的质量比为(1～10):(90～99)。在本公开一实施方式中，有机溶剂可以为乙醇，只要能够实现碳骨架材料和聚合物的溶解或者分散即可。在本公开一实施方式中，碳骨架材料和聚合物的混合液的固含量为40％～60％。本公开不受限于此，本公开实施方式可以根据需要调整碳骨架材料和聚合物的用量，以上均在本公开实施方式的保护范围之内。本公开实施方式采用碳骨架材料和聚合物的混合物制备第一硬炭包覆层和第二硬炭包覆层，以此使得第一硬炭包覆层和第二硬炭包覆层在石墨化高温处理之后，还能保持硬炭结构，且石墨化过程的超高温度能够极大降低石墨复合材料的比表面积，避免了因比表面积过大导致副反应过多，首次不可逆容量大的缺点，提升了石墨负极材料的首次充放电库伦效率。In an embodiment of the present disclosure, the solution containing the carbon skeleton material and the polymer is prepared by dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a solution containing the carbon skeleton material and the polymer. In an embodiment of the present disclosure, the carbon framework material includes at least one of carbon nanotubes and carbon fibers. In an embodiment of the present disclosure, the polymer includes at least one of phenolic resin, polypropylene resin and polyurethane. In an embodiment of the present disclosure, the solvent includes at least one of an organic solvent and water. In an embodiment of the present disclosure, the carbon skeleton material and the polymer are uniformly dispersed in an organic solvent to obtain a solution containing the carbon skeleton material and the polymer. In an embodiment of the present disclosure, the organic solvent includes at least one of ethanol and water. In an embodiment of the present disclosure, the solid content of the polymer precursor is 40%-60%, for example, the solid content is 40%-50%, 50%-60% or 45%-60%, such as 40%, 42% , 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%. In an embodiment of the present disclosure, the carbon skeleton material and the polymer are added to the organic solution and stirred to disperse the carbon skeleton material and the polymer in the organic solvent. In an embodiment of the present disclosure, the carbon framework material may be carbon nanotubes and carbon fibers. In an embodiment of the present disclosure, the lengths of the carbon nanotubes and carbon fibers are 100 nm-300 nm, and the diameters are 5 nm-10 nm. In an embodiment of the present disclosure, the mass ratio of the carbon skeleton material to the polymer is (1-10):(90-99). In an embodiment of the present disclosure, the organic solvent may be ethanol, as long as it can achieve dissolution or dispersion of the carbon skeleton material and the polymer. In an embodiment of the present disclosure, the solid content of the mixed solution of the carbon skeleton material and the polymer is 40% to 60%. The present disclosure is not limited thereto, and the embodiments of the present disclosure can adjust the amounts of carbon skeleton materials and polymers as required, and the above are all within the protection scope of the embodiments of the present disclosure. Embodiments of the present disclosure use a mixture of a carbon framework material and a polymer to prepare the first hard carbon coating layer and the second hard carbon coating layer, so that the first hard carbon coating layer and the second hard carbon coating layer are in graphite After the high temperature treatment, the hard carbon structure can still be maintained, and the ultra-high temperature of the graphitization process can greatly reduce the specific surface area of the graphite composite material, avoiding the disadvantages of excessive side reactions and large irreversible capacity for the first time due to excessive specific surface area. , which improves the coulombic efficiency of the first charge and discharge of the graphite anode material.
步骤S20：Step S20:
在本公开一实施方式中，步骤S20可以为：S21、将聚合物前驱体喷洒至石墨原料颗粒表面；S22、翻滚石墨原料颗粒以在石墨原料颗粒表面形成第一聚合物前驱体包覆层；S23、干燥处理形成有第一聚合物前驱体包覆层的石墨原料颗粒。在一些实施方式中，石墨原料颗粒的翻滚速度为5r/min～30r/min， 例如10r/min～30r/min、15r/min～30r/min或5r/min～25r/min，诸如5r/min、8r/min、10r/min、12r/min、15r/min、17r/min、20r/min、22r/min、25r/min、27r/min、30r/min。在一些实施方式中，干燥处理的温度为80℃～95℃，温度诸如为80℃、82℃、85℃、87℃、90℃、92℃、95℃；干燥处理的时间为20min～40min，时间诸如为20min、22min、25min、27min、30min、32min、35min、37min、40min。In an embodiment of the present disclosure, step S20 may be: S21, spraying the polymer precursor onto the surface of the graphite raw material particles; S22, rolling the graphite raw material particles to form a first polymer precursor coating layer on the surface of the graphite raw material particle; S23, drying the graphite raw material particles formed with the first polymer precursor coating layer. In some embodiments, the tumbling speed of the graphite feedstock particles is 5 r/min to 30 r/min, such as 10 r/min to 30 r/min, 15 r/min to 30 r/min, or 5 r/min to 25 r/min, such as 5 r/min , 8r/min, 10r/min, 12r/min, 15r/min, 17r/min, 20r/min, 22r/min, 25r/min, 27r/min, 30r/min. In some embodiments, the drying temperature ranges from 80°C to 95°C, such as 80°C, 82°C, 85°C, 87°C, 90°C, 92°C, and 95°C; the drying time ranges from 20min to 40min. Times such as 20min, 22min, 25min, 27min, 30min, 32min, 35min, 37min, 40min.
据信，不受理论的约束，术语“翻滚”可以是指术语“翻滚”，指颗粒的滚动、转动和/或旋转。例如，“翻滚”可以是石墨原料沿圆形炉壁呈圆周式向前滚动往复运动。It is believed, without being bound by theory, that the term "tumbling" may refer to the term "tumbling", referring to the rolling, turning and/or spinning of particles. For example, "tumbling" can be the rolling forward and reciprocating motion of the graphite raw material in a circular shape along the circular furnace wall.
在一些实施方式中，将聚合物前驱体转移至包衣设备中，包衣设备为滚筒喷雾包衣设备，调节包衣设备的滚筒转速为5r/min～30r/min，通过二流体喷嘴将聚合物前驱体喷洒至翻滚的石墨原料颗粒表面，并在热风下进行干燥处理，干燥处理的温度为80℃～95℃，包衣处理的时间为20min～40min。需要说明的是，本公开可以根据滚筒转速适当调整包衣处理的时间，只要保证聚合物前驱体在石墨原料颗粒表面的均匀包覆即可，当然，本公开还可以采用其他包衣设备，诸如流化床包衣机、压制包衣设备等，本公开不受限于此，以上均在本公开的保护范围之内。在本公开一实施方式中，石墨原料颗粒可以为天然石墨微粒，也可以为软炭微粒。在一些实施方式中，软炭微粒包括石油焦、针状焦、碳纤维、无烟煤及碳微球等。在一些实施方式中，针状焦包括油系针状焦和煤系针状焦，本公开的上述实施方式不受限于此，以上均在本公开实施方式的保护范围之内。In some embodiments, the polymer precursor is transferred to a coating device, the coating device is a drum spray coating device, the drum rotation speed of the coating device is adjusted to be 5r/min-30r/min, and the polymerization is carried out through a two-fluid nozzle. The precursor is sprayed onto the surface of the tumbling graphite raw material particles, and dried under hot air. The drying temperature is 80°C to 95°C, and the coating treatment time is 20min to 40min. It should be noted that the present disclosure can appropriately adjust the coating treatment time according to the rotation speed of the drum, as long as the uniform coating of the polymer precursor on the surface of the graphite raw material particles is ensured. Of course, the present disclosure can also adopt other coating equipment, such as Fluid bed coaters, press coating equipment, etc., the present disclosure is not limited thereto, and the above are all within the protection scope of the present disclosure. In an embodiment of the present disclosure, the graphite raw material particles may be natural graphite particles or soft carbon particles. In some embodiments, the soft carbon particles include petroleum coke, needle coke, carbon fiber, anthracite, carbon microspheres, and the like. In some embodiments, needle coke includes oil-based needle coke and coal-based needle coke, the above embodiments of the present disclosure are not limited thereto, and the above are all within the protection scope of the embodiments of the present disclosure.
在一些实施方式中，步骤S21之前，还包括粉碎石墨原料，得到石墨原料颗粒。在一些实施方式中，石墨原料颗粒的粒度分布为：D10:3～8μm，D50:5～12μm，D90:12～18μm，D max＜30μm，该粒度分布中粒径均为中值粒径。在一些实施方式中，将石墨原料加入到破碎机中，利用破碎机对石墨原料进行粉碎，以此得到粒度小于5mm的破碎料，破碎料再利用机械粉磨至粒度为D10:3～8μm，D50:5～12μm，D90:12～18μm，D max＜30μm，得到石墨原料颗粒，这样，经过石墨化处理后，第一硬炭包覆层均匀包覆于石墨原料颗粒形成的石墨表面，从而保证了所制备石墨负极材料的充放电性能。 In some embodiments, before step S21, the method further includes pulverizing the graphite raw material to obtain graphite raw material particles. In some embodiments, the particle size distribution of the graphite raw material particles is: D10: 3-8 μm, D50: 5-12 μm, D90: 12-18 μm, D max <30 μm, and the particle diameters in the particle size distribution are all median diameters. In some embodiments, the graphite raw material is added to a crusher, and the graphite raw material is pulverized by the crusher to obtain a crushed material with a particle size of less than 5 mm, and the crushed material is then mechanically ground to a particle size of D10:3-8 μm, D50: 5～12μm, D90: 12～18μm, D max <30μm, to obtain graphite raw material particles, in this way, after graphitization treatment, the first hard carbon coating layer is uniformly coated on the graphite surface formed by the graphite raw material particles, thereby The charge-discharge performance of the prepared graphite anode material is guaranteed.
步骤S30：Step S30:
在本公开一实施方式中，步骤S30可以为：S31、将碳源喷洒至一次颗粒前驱体表面；S32、翻滚一次颗粒前驱体以使一次颗粒前驱体之间通过碳源粘结；S33、炭化处理粘结有碳源的一次颗粒前驱体。In an embodiment of the present disclosure, step S30 may be: S31, spray the carbon source on the surface of the primary particle precursor; S32, roll the primary particle precursor to bond the primary particle precursors through the carbon source; S33, carbonize The carbon source-bonded primary particle precursor is processed.
在一些实施方式中，碳源为易石墨化原料。在一些实施方式中，易石墨化原料可以为沥青、石油焦、无烟煤，沥青焦，煤系焦、树脂、油脂、烷烃、烯烃、炔烃和芳烃中的至少一种。例如，树脂可以选自环氧树脂或酚醛树脂中的一种。例如，沥青选自煤沥青、石油沥青、中间相沥青或改质沥青中的至少一种。在一些实施方式中，碳源为沥青。在步骤S30中，制备所用设备可以选择诸如滚筒炉、旋转炉中进行。在一些实施方式中，一次颗粒前驱体的翻滚速度为5r/min～30r/min，诸如5r/min、12r/min、15r/min、18r/min、20r/min、22r/min、25r/min、28r/min、30r/min。在一些实施方式中，炭化处理的温度为450℃～750℃，诸如450℃、500℃、550℃、600℃、650℃、700℃、750℃；时间为1h～5h，诸如1h、1.5h、2h、2.5h、3h、3.5h、4h、4.5h、5h。In some embodiments, the carbon source is a graphitizable feedstock. In some embodiments, the easily graphitizable raw material may be at least one of pitch, petroleum coke, anthracite, pitch coke, coal-based coke, resin, grease, alkane, alkene, alkyne, and aromatic hydrocarbon. For example, the resin may be selected from one of epoxy resins or phenolic resins. For example, the pitch is selected from at least one of coal pitch, petroleum pitch, mesophase pitch, or modified pitch. In some embodiments, the carbon source is pitch. In step S30, the equipment used for the preparation can be selected such as a drum furnace and a rotary furnace. In some embodiments, the tumbling speed of the primary particle precursor is 5r/min to 30r/min, such as 5r/min, 12r/min, 15r/min, 18r/min, 20r/min, 22r/min, 25r/min , 28r/min, 30r/min. In some embodiments, the temperature of the carbonization treatment is 450°C to 750°C, such as 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C; and the time is 1h to 5h, such as 1h, 1.5h , 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h.
在一些实施方式中，在滚筒炉中进行步骤S30，升高滚筒内物料温度至150℃～250℃，将熔融沥青通过二流体喷嘴喷洒于一次颗粒前驱体的表面，调节滚筒转速为5r/min～30r/min，沥青喷洒流量为80mL/min～120mL/min，喷洒时间为10min～30min，停止喷洒后，将滚筒转速调整至20r/min～40r/min，同时将滚筒内物料2h～8h升至450℃～750℃，并保温1h～5h，冷却降温得到二次颗粒。在一些实施方式中，制备得到的二次颗粒的中值粒径D50为13μm～24μm，粒度分布Span为0.75～1.0。本公开实施方式通过将沥青熔融后喷洒至一次颗粒前驱体表面，以此在保证沥青对一次颗粒前驱体充分包覆的前提下，减少了沥青的用量比例，增大了造粒效果，提高了二次颗粒造粒的一致性，使得二次颗粒OI取向更低，降低了所制备石墨复合材料的嵌锂膨胀度。In some embodiments, step S30 is performed in a drum furnace, the temperature of the material in the drum is raised to 150°C-250°C, the molten asphalt is sprayed on the surface of the primary particle precursor through a two-fluid nozzle, and the drum rotational speed is adjusted to 5r/min ～30r/min, the asphalt spraying flow is 80mL/min～120mL/min, and the spraying time is 10min～30min. After stopping spraying, adjust the drum speed to 20r/min～40r/min, and at the same time, the material in the drum is 2h～8h liters. to 450℃～750℃, keep the temperature for 1h～5h, and cool down to obtain secondary particles. In some embodiments, the median particle diameter D50 of the prepared secondary particles is 13 μm˜24 μm, and the particle size distribution Span is 0.75˜1.0. In the embodiment of the present disclosure, the asphalt is melted and then sprayed onto the surface of the primary particle precursor, thereby reducing the proportion of the amount of asphalt used, increasing the granulation effect, and improving the The consistency of the granulation of the secondary particles makes the OI orientation of the secondary particles lower and reduces the expansion degree of lithium intercalation of the prepared graphite composites.
步骤S40：Step S40:
在本公开一实施方式中，步骤S40可以为：S41、将聚合物前驱体喷洒至二次颗粒表面；S42、翻 滚二次颗粒以在二次颗粒表面形成第二聚合物前驱体包覆层；S43、石墨化处理形成有第二聚合物前驱体包覆层的二次颗粒。在一些实施方式中，二次颗粒的中值粒径为13μm～24μm，诸如13μm、15μm、18μm、20μm、22μm、24μm；粒度分布(D90-D10)/D50为0.75～1.0，诸如0.75、0.8、0.85、0.9、0.95、1。在一些实施方式中，二次颗粒的翻滚速度为5r/min～30r/min，诸如5r/min、8r/min、10r/min、15r/min、20r/min、25r/min、30r/min。在一些实施方式中，石墨化温度2400℃～3000℃，例如2500℃～3000℃、2400℃～2600℃或2500℃～2900℃；石墨化时间1h～6h，诸如1h、2h、3h、4h、5h、6h。在步骤S40中，制备所用设备可以选择诸如包衣设备、流化床包衣机、压制包衣设备等。在一些实施方式中，在包衣设备中进行步骤S40，调整滚筒转速至5r/min～30r/min，通过二流体喷嘴将聚合物前驱体以30mL/min～80mL/min速度喷洒在翻滚的二次颗粒表面，喷雾包衣处理时间为20min～40min，将喷洒有聚合物前驱体的二次颗粒放入至石墨化炉中进行高温石墨化，石墨化炉为内串炉或艾奇逊炉，石墨化温度2400℃～3000℃，石墨化时间1h～6h，得到石墨复合材料。本公开实施方式可以根据实际情况调整石墨化条件，本公开实施方式不受限于此，以上均在本公开实施方式的保护范围之内。In an embodiment of the present disclosure, step S40 may be: S41, spraying the polymer precursor onto the surface of the secondary particles; S42, rolling the secondary particles to form a second polymer precursor coating layer on the surface of the secondary particles; S43, graphitizing the secondary particles formed with the coating layer of the second polymer precursor. In some embodiments, the median particle size of the secondary particles is 13 μm to 24 μm, such as 13 μm, 15 μm, 18 μm, 20 μm, 22 μm, 24 μm; the particle size distribution (D90-D10)/D50 is 0.75 to 1.0, such as 0.75, 0.8 , 0.85, 0.9, 0.95, 1. In some embodiments, the tumbling speed of the secondary particles is 5 r/min to 30 r/min, such as 5 r/min, 8 r/min, 10 r/min, 15 r/min, 20 r/min, 25 r/min, 30 r/min. In some embodiments, the graphitization temperature is 2400°C to 3000°C, such as 2500°C to 3000°C, 2400°C to 2600°C, or 2500°C to 2900°C; the graphitization time is 1h to 6h, such as 1h, 2h, 3h, 4h, 5h, 6h. In step S40, the equipment used for the preparation can be selected such as coating equipment, fluidized bed coater, press coating equipment and the like. In some embodiments, step S40 is carried out in the coating equipment, the rotation speed of the drum is adjusted to 5r/min～30r/min, and the polymer precursor is sprayed on the tumbling two-fluid nozzle at a speed of 30mL/min～80mL/min through a two-fluid nozzle On the surface of the secondary particles, the spray coating treatment time is 20min to 40min, and the secondary particles sprayed with the polymer precursor are put into a graphitization furnace for high-temperature graphitization. The graphitization furnace is an inner string furnace or an Acheson furnace. The graphitization temperature is 2400℃～3000℃, and the graphitization time is 1h～6h to obtain the graphite composite material. The embodiments of the present disclosure can adjust the graphitization conditions according to the actual situation, and the embodiments of the present disclosure are not limited thereto, and the above are all within the protection scope of the embodiments of the present disclosure.
补充说明，石墨原料颗粒的表面和二次颗粒的表面均包覆包含有碳骨架材料和聚合物的聚合物前驱体，聚合物前驱体石墨化后转换成类似钢筋水泥混凝土结构的硬炭包覆层，其中，碳骨架材料在第二硬炭包覆层和第一硬炭包覆层中均充当骨架，有效增加了第二硬炭包覆层和第一硬炭包覆层的机械强度、杨氏模量及电导，有利于稳定堆积成球形结构的石墨复合材料，以此提高了石墨负极材料的长期循环性能。并且，本公开实施方式通过采用不同的组分作为包衣剂，以此实现了对石墨原料颗粒的包覆、造粒及包覆的一步到位，极大缩短了石墨负极材料的制造周期，减少生产成本，便于规模化生产。Supplementary note, the surface of the graphite raw material particles and the surface of the secondary particles are coated with a polymer precursor containing a carbon framework material and a polymer, and the polymer precursor is converted into a hard carbon coating similar to a reinforced cement concrete structure after graphitization. layer, wherein the carbon skeleton material acts as a skeleton in both the second hard carbon coating layer and the first hard carbon coating layer, effectively increasing the mechanical strength of the second hard carbon coating layer and the first hard carbon coating layer, The Young's modulus and conductance are beneficial to the stable accumulation of the graphite composite material into a spherical structure, thereby improving the long-term cycle performance of the graphite anode material. Moreover, by using different components as coating agents in the embodiments of the present disclosure, the coating, granulation and coating of the graphite raw material particles can be achieved in one step, which greatly shortens the manufacturing cycle of the graphite negative electrode material and reduces the The production cost is convenient for large-scale production.
本公开还提出一种锂离子电池，锂离子电池包括上述的石墨复合材料；和/或，锂离子电池包括上述的制备方法制备而成的石墨复合材料。石墨复合材料作为石墨负极材料时，由于石墨具有高充放电容量的特质，以此提高了石墨负极材料的充放电容量。并且，第二硬炭包覆层包覆于二次颗粒内核表面，二次颗粒包括一次颗粒和无定型炭，一次颗粒中第一硬炭包覆层包覆于石墨表面，第二硬炭包覆层和第一硬炭包覆层作为硬炭材料所成型的结构，硬炭材料具有良好的快充性能，从而提高了石墨负极材料的快充性能。即本公开的技术方案能够在提高石墨负极材料的电容量的同时，提升石墨负极材料的快充性能。The present disclosure also provides a lithium-ion battery, where the lithium-ion battery includes the above-mentioned graphite composite material; and/or, the lithium-ion battery includes the graphite composite material prepared by the above-mentioned preparation method. When the graphite composite material is used as the graphite negative electrode material, the charge and discharge capacity of the graphite negative electrode material is improved due to the high charge and discharge capacity of graphite. In addition, the second hard carbon coating layer is coated on the surface of the inner core of the secondary particles, the secondary particles include primary particles and amorphous carbon, and the first hard carbon coating layer is coated on the surface of the graphite in the primary particles, and the second hard carbon coating is The coating layer and the first hard carbon coating layer are formed by the hard carbon material, and the hard carbon material has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
现有技术公开了如下石墨负极材料：第一种石墨负极材料，将石墨原料颗粒粉碎到至一定粒度，通过捏合实现二次颗粒的造粒，石墨化得到石墨负极材料；这种结构存在的缺陷是很难兼顾容量和快充性能，如果选择易石墨化原料，容量可以保证但快充性能差；如果选择难石墨化原料，快充性能较好但容量较低。第二种石墨负极材料，在石墨表面包覆硬炭层或软炭层，表面包覆虽然能够降低界面阻抗提升快充性能。这种结构存在的缺陷是没有经过石墨化处理，表面的包覆层会影响石墨容量，若包覆物为沥青类软炭时，对材料快充性能提升不如硬炭。The prior art discloses the following graphite negative electrode materials: the first graphite negative electrode material, the graphite raw material particles are pulverized to a certain particle size, the granulation of secondary particles is realized by kneading, and the graphite negative electrode material is obtained by graphitization; the defects of this structure exist It is difficult to take into account the capacity and fast charging performance. If you choose easy graphitization raw materials, the capacity can be guaranteed but the fast charging performance is poor; if you choose difficult graphitization raw materials, the fast charging performance is good but the capacity is low. The second type of graphite anode material coats the graphite surface with a hard carbon layer or a soft carbon layer. Although the surface coating can reduce the interface impedance and improve the fast charging performance. The disadvantage of this structure is that it has not undergone graphitization treatment, and the coating layer on the surface will affect the graphite capacity. If the coating is pitch-based soft carbon, the fast charging performance of the material is not as good as that of hard carbon.
上述负极材料在大倍率充放电时，二次颗粒容易变形与粉化，包覆层不稳定，颗粒大小不均匀，锂离子传输能力较差，倍率性能不符合需求。When the above-mentioned negative electrode material is charged and discharged at a high rate, the secondary particles are easily deformed and pulverized, the coating layer is unstable, the particle size is uneven, the lithium ion transmission ability is poor, and the rate performance does not meet the requirements.
本公开提供了一种石墨复合材料，旨在提高石墨负极材料的电容量的同时，提升石墨负极材料的快充性能。The present disclosure provides a graphite composite material, which aims to improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
本公开的技术方案，石墨复合材料作为石墨负极材料时，由于石墨具有高充放电容量的特质，以此提高了石墨负极材料的充放电容量。并且，第二硬炭包覆层包覆于二次颗粒内核表面，二次颗粒包括一次颗粒和无定型炭，一次颗粒中第一硬炭包覆层包覆于石墨表面，第二硬炭包覆层和第一硬炭包覆层作为硬炭材料所成型的结构，硬炭材料具有良好的快充性能，从而提高了石墨负极材料的快充性能。即本公开的技术方案能够在提高石墨负极材料的电容量的同时，提升石墨负极材料的快充性能。In the technical solution of the present disclosure, when the graphite composite material is used as the graphite negative electrode material, the charge and discharge capacity of the graphite negative electrode material is improved because the graphite has the characteristics of high charge and discharge capacity. In addition, the second hard carbon coating layer is coated on the surface of the inner core of the secondary particles, the secondary particles include primary particles and amorphous carbon, and the first hard carbon coating layer is coated on the surface of the graphite in the primary particles, and the second hard carbon coating is The coating layer and the first hard carbon coating layer are formed by the hard carbon material, and the hard carbon material has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material.
下面结合实施例来说明本公开的技术方案。应当理解的是，此处所描述的实施例仅用于解释本公开， 并不构成对本公开保护范围的限定。The technical solutions of the present disclosure will be described below with reference to the embodiments. It should be understood that the embodiments described herein are only used to explain the present disclosure, and do not limit the protection scope of the present disclosure.
实施例Example
本公开实施例1～6中石墨复合材料的制备工艺参见图3，以下实施例中粒径若无特殊说明，则均为中值粒径。The preparation process of the graphite composite material in Examples 1 to 6 of the present disclosure is shown in FIG. 3 , and the particle diameters in the following examples are all median diameters unless otherwise specified.
实施例1Example 1
步骤一，利用破碎机对油系针状焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:4～6μm，D50:7～8μm，D90:14～16μm，D max﹤28μm的石墨原料颗粒，将碳纳米管和酚醛树脂按质量比1:19，分别加入到乙醇中，控制固含量为45％，搅拌以使碳纳米管和酚醛树脂溶解于乙醇，得到碳纳米管-酚醛树脂的混合液，其中碳纳米管的平均长径比为3125； Step 1, use a crusher to roughly crush the oil-based needle coke raw material to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 4-6 μm, D50: 7-8 μm, D90: 14-16 μm, D max < 28μm graphite raw material particles, carbon nanotubes and phenolic resin were added to ethanol at a mass ratio of 1:19, the solid content was controlled to be 45%, and stirred to dissolve the carbon nanotubes and phenolic resin in ethanol to obtain Carbon nanotube-phenolic resin mixture, wherein the average aspect ratio of carbon nanotubes is 3125;
步骤二，将石墨原料颗粒转移至滚筒喷雾包衣设备中，滚筒转速为15r/min，通过二流体喷嘴将碳纳米管-酚醛树脂的混合液以50mL/min速度喷洒在翻滚的石墨原料颗粒表面，并在90℃下热风下干燥，包衣处理时间为30min，得到一次颗粒前驱体；In step 2, the graphite raw material particles are transferred to the drum spray coating equipment, and the rotating speed of the drum is 15r/min, and the mixed solution of carbon nanotube-phenolic resin is sprayed on the surface of the tumbling graphite raw material particles at a speed of 50 mL/min through a two-fluid nozzle. , and dried under hot air at 90°C, and the coating treatment time was 30min to obtain the primary particle precursor;
步骤三，升高滚筒内物料温度至200℃，将熔融沥青通过二流体喷嘴喷洒在一次颗粒前驱体的表面，调节滚筒转速为15r/min，沥青喷洒流量为100mL/min，喷洒时间为20min，停止喷洒后，将滚筒转速调整至30r/min，同时将滚筒内物料4h升至600℃，并保温2h，冷却降温得到二次颗粒，二次颗粒的中值粒径D50为18μm，粒度分布Span为0.8；Step 3, raising the temperature of the material in the drum to 200°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum speed to 15r/min, the asphalt spraying flow rate to 100mL/min, and the spraying time to 20min. After stopping spraying, adjust the rotation speed of the drum to 30r/min, and at the same time raise the material in the drum to 600℃ for 4h, keep the temperature for 2h, and cool down to obtain secondary particles. The median particle size D50 of the secondary particles is 18μm, and the particle size distribution Span is 0.8;
步骤四，调整滚筒转速至15r/min，通过二流体喷嘴将碳纳米管-酚醛树脂的混合液以50mL/min速度喷洒在翻滚球形的二次颗粒表面，并在90℃下热风下干燥，喷雾包衣处理时间为30min，将所得到的包覆有碳纳米管-酚醛树脂的二次颗粒进行高温石墨化，石墨化炉为艾奇逊炉，石墨化温度2800℃～3000℃，石墨化时间2h～4h，得到石墨复合材料。 Step 4, adjust the rotating speed of the drum to 15r/min, spray the mixture of carbon nanotube-phenolic resin on the surface of the tumbling spherical secondary particles at a speed of 50mL/min through a two-fluid nozzle, and dry it under hot air at 90°C, spray The coating treatment time is 30min, and the obtained secondary particles coated with carbon nanotube-phenolic resin are subjected to high-temperature graphitization. 2h～4h, the graphite composite material is obtained.
本实施例得到的石墨复合材料中，石墨复合材料为核壳结构，其包括二次颗粒内核和包覆于二次颗粒内核的表面第二硬炭包覆层(由步骤四碳纳米管-酚醛树脂制备形成)；二次颗粒包括一次颗粒(即步骤二的一次颗粒前驱体)和无定型炭(由步骤三熔融沥青制备获得)，一次颗粒包括石墨和包覆于石墨表面的第一硬炭包覆层(由步骤一碳纳米管-酚醛树脂制备形成)；碳纳米管均匀分布在第一硬炭包覆层和第二硬炭包覆层中。In the graphite composite material obtained in this example, the graphite composite material has a core-shell structure, which includes a secondary particle inner core and a second hard carbon coating on the surface of the secondary particle inner core (from step 4 carbon nanotube-phenolic resin preparation); the secondary particles include primary particles (that is, the precursor of the primary particles in step 2) and amorphous carbon (obtained from the molten pitch in step 3), and the primary particles include graphite and the first hard carbon coated on the surface of the graphite Coating layer (formed by carbon nanotube-phenolic resin preparation in step 1); carbon nanotubes are uniformly distributed in the first hard carbon coating layer and the second hard carbon coating layer.
实施例2Example 2
步骤一，利用破碎机对煤系针状焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:4～6μm，D50:6～7μm，D90:13～15μm，D max﹤28μm的石墨原料颗粒，将碳纳米管和聚丙烯腈按质量比7:93，分别加入到乙醇中，控制固含量为50％，搅拌以使碳纳米管和聚丙烯腈溶解于乙醇，得到碳纳米管-聚丙烯腈的混合液，其中碳纳米管的平均长径比为714； Step 1, use a crusher to roughly crush the coal-based needle coke raw material to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 4-6 μm, D50: 6-7 μm, D90: 13-15 μm, D max < 28μm graphite raw material particles, carbon nanotubes and polyacrylonitrile were added to ethanol in a mass ratio of 7:93, the solid content was controlled to 50%, and stirred to dissolve carbon nanotubes and polyacrylonitrile in ethanol , to obtain a mixture of carbon nanotubes-polyacrylonitrile, wherein the average aspect ratio of carbon nanotubes is 714;
步骤二，将石墨原料颗粒转移至滚筒喷雾包衣设备中，滚筒转速为18r/min，通过二流体喷嘴将碳纳米管-聚丙烯腈的混合液以60mL/min速度喷洒在翻滚的石墨原料颗粒表面，并在95℃下热风下干燥，包衣处理时间为35min，得到一次颗粒前驱体；Step 2, the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the carbon nanotube-polyacrylonitrile mixed solution is sprayed on the tumbling graphite raw material particles at a speed of 60 mL/min through a two-fluid nozzle. The surface was dried under hot air at 95°C, and the coating treatment time was 35min to obtain the primary particle precursor;
步骤三，升高滚筒内物料温度至250℃，将熔融沥青通过二流体喷嘴喷洒在一次颗粒前驱体的表面，调节滚筒转速为20r/min，沥青喷洒流量为90mL/min，喷洒时间为30min，停止喷洒后，将滚筒转速调整至30r/min，同时将滚筒内物料5h升至650℃，并保温3h，冷却降温得二次颗粒，二次颗粒的中值粒径D50为16μm，粒度分布Span为0.85；Step 3, raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum speed to 20r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min, After stopping spraying, adjust the rotation speed of the drum to 30r/min, and at the same time raise the material in the drum to 650℃ for 5h, keep the temperature for 3h, and cool down to obtain secondary particles. The median particle size D50 of the secondary particles is 16μm, and the particle size distribution Span is 0.85;
步骤四，调整滚筒转速至18r/min，通过二流体喷嘴将碳纳米管-聚丙烯腈的混合液以60mL/min速度喷洒在翻滚球形的二次颗粒表面，并在95℃下热风下干燥，喷雾包衣处理时间为35min，将包覆有碳纳米管-聚丙烯腈的二次颗粒进行高温石墨化，石墨化炉为艾奇逊炉，石墨化温度2800℃，石墨化时间3h，得到石墨复合材料。 Step 4, adjust the rotating speed of the drum to 18r/min, spray the mixture of carbon nanotube-polyacrylonitrile at a speed of 60mL/min on the surface of the tumbling spherical secondary particles through a two-fluid nozzle, and dry it under hot air at 95°C, The spray coating treatment time is 35min, and the secondary particles coated with carbon nanotube-polyacrylonitrile are subjected to high temperature graphitization. composite material.
本实施例得到的石墨复合材料中在结构上与实施例1相近，与实施例1材料组成不同的是第二硬炭 包覆层由步骤四碳纳米管-聚丙烯腈制备形成；第一硬炭包覆层由步骤一碳纳米管-聚丙烯腈制备形成。The graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from carbon nanotube-polyacrylonitrile in step 4; The carbon coating layer is formed by preparing carbon nanotubes-polyacrylonitrile in step one.
实施例3Example 3
步骤一，利用破碎机对石油焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:5～7μm，D50:8～9μm，D90:15～17μm，D max﹤28μm的石墨原料颗粒，将碳纳米管和聚氨酯按质量比2:23，分别加入到乙醇中，控制固含量为55％，搅拌以使碳纳米管和聚氨酯溶解于乙醇，得到碳纳米管-聚氨酯的混合液，其中碳纳米管的平均长径比为2836； Step 1, use a crusher to roughly crush the raw material of petroleum coke to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 5-7 μm, D50: 8-9 μm, D90: 15-17 μm, D max ﹤ 28μm graphite raw material particles, carbon nanotubes and polyurethane were added to ethanol at a mass ratio of 2:23, the solid content was controlled to 55%, and the carbon nanotubes and polyurethane were stirred to dissolve in ethanol to obtain carbon nanotube-polyurethane The mixed solution, wherein the average aspect ratio of carbon nanotubes is 2836;
步骤二，将石墨原料颗粒转移至滚筒喷雾包衣设备中，滚筒转速为18r/min，通过二流体喷嘴将碳纳米管-聚氨酯的混合液以55mL/min速度喷洒在翻滚的石墨原料颗粒表面，并在90℃下热风下干燥，包衣处理时间为40min，得到一次颗粒前驱体；Step 2, the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the carbon nanotube-polyurethane mixed solution is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle, And dried under hot air at 90°C, the coating treatment time is 40min, and the primary particle precursor is obtained;
步骤三，升高滚筒内物料温度至250℃，将熔融沥青通过二流体喷嘴喷洒在一次颗粒前驱体的表面，调节滚筒转速为30r/min，沥青喷洒流量为90mL/min，喷洒时间为30min，停止喷洒后，将滚筒转速调整至40r/min，同时将滚筒内物料5h升至650℃，并保温3h，冷却降温得到二次颗粒，二次颗粒的中值粒径D50为19μm，粒度分布Span为0.75；Step 3, raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650℃ for 5h, keep the temperature for 3h, and cool down to obtain secondary particles. The median particle size D50 of the secondary particles is 19μm, and the particle size distribution Span is 0.75;
步骤四，调整滚筒转速至18r/min，通过二流体喷嘴将碳纳米管-聚氨酯的混合液以60mL/min速度喷洒在翻滚球形的二次颗粒表面，并在90℃下热风下干燥，喷雾包衣处理时间为40min，将包覆有碳纳米管-聚氨酯的二次颗粒进行高温石墨化，石墨化炉为艾奇逊炉，石墨化温度2900℃，石墨化时间4h，得到石墨复合材料。Step 4: Adjust the rotating speed of the drum to 18r/min, spray the carbon nanotube-polyurethane mixture on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90°C. The coating treatment time is 40min, and the carbon nanotube-polyurethane-coated secondary particles are subjected to high-temperature graphitization. The graphitization furnace is an Acheson furnace, the graphitization temperature is 2900°C, and the graphitization time is 4h to obtain a graphite composite material.
本实施例得到的石墨复合材料中在结构上与实施例1相近，与实施例1材料组成不同的是第二硬炭包覆层由步骤四碳纳米管-聚氨酯制备形成；第一硬炭包覆层由步骤一碳纳米管-聚氨酯制备形成。The graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from carbon nanotube-polyurethane in step 4; The coating is formed by the carbon nanotube-polyurethane preparation in step one.
实施例4Example 4
步骤一，利用破碎机对石油焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:3～4μm，D50:5～7μm，D90:12～15μm，D max﹤25μm的石墨原料颗粒，将碳纤维和聚乙烯醇按质量比2:23，分别加入到乙醇中，控制固含量为55％，搅拌以使碳纤维和聚乙烯醇溶解于乙醇，得到碳纤维-聚乙烯醇的混合液，其中碳纤维的平均长径比为480； Step 1, use a crusher to coarsely crush the petroleum coke raw material to obtain crushed material with a particle size of less than 5mm, and then use a mechanical mill to pulverize to a particle size of: D10: 3～4μm, D50: 5～7μm, D90: 12～15μm, D max ﹤ 25μm graphite raw material particles, carbon fiber and polyvinyl alcohol were added to ethanol at a mass ratio of 2:23, and the solid content was controlled to 55%, and stirred to dissolve carbon fiber and polyvinyl alcohol in ethanol to obtain carbon fiber-polyvinyl alcohol The mixed solution, in which the average aspect ratio of carbon fiber is 480;
步骤二，将石墨原料颗粒转移至滚筒喷雾包衣设备中，滚筒转速为18r/min，通过二流体喷嘴将碳纤维-聚乙烯醇的混合液以55mL/min速度喷洒在翻滚的石墨原料颗粒表面，并在90℃下热风下干燥，包衣处理时间为40min，得到一次颗粒前驱体；Step 2, the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the mixed solution of carbon fiber-polyvinyl alcohol is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle, And dried under hot air at 90°C, the coating treatment time is 40min, and the primary particle precursor is obtained;
步骤三，升高滚筒内物料温度至250℃，将熔融沥青通过二流体喷嘴喷洒在一次颗粒前驱体的表面，调节滚筒转速为30r/min，沥青喷洒流量为90mL/min，喷洒时间为30min，停止喷洒后，将滚筒转速调整至40r/min，同时将滚筒内物料5h升至650℃，并保温3h，冷却降温得到二次颗粒，二次颗粒的中值粒径D50为15μm，粒度分布Span为0.85；Step 3, raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650℃ for 5h, keep the temperature for 3h, and cool down to obtain secondary particles. The median particle size D50 of the secondary particles is 15μm, and the particle size distribution Span is 0.85;
步骤四，调整滚筒转速至18r/min，通过二流体喷嘴将碳纤维-聚乙烯醇的混合液以60mL/min速度喷洒在翻滚球形的二次颗粒表面，并在90℃下热风下干燥，喷雾包衣处理时间为40min，将包覆有碳纤维-聚乙烯醇的二次颗粒进行高温石墨化，石墨化炉为艾奇逊炉，石墨化温度2900℃，石墨化时间4h，得到石墨复合材料。 Step 4, adjust the rotating speed of the drum to 18r/min, spray the mixture of carbon fiber-polyvinyl alcohol on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90 ° C, spray the bag. The coating treatment time is 40min, and the carbon fiber-polyvinyl alcohol-coated secondary particles are subjected to high temperature graphitization. The graphitization furnace is an Acheson furnace, the graphitization temperature is 2900°C, and the graphitization time is 4h to obtain a graphite composite material.
本实施例得到的石墨复合材料中在结构上与实施例1相近，与实施例1材料组成不同的是第二硬炭包覆层由步骤四碳纤维-聚乙烯醇制备形成；第一硬炭包覆层由步骤一碳纤维-聚乙烯醇制备形成；碳纤维均匀分布在第一硬炭包覆层和第二硬炭包覆层中。The graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from step 4 carbon fiber-polyvinyl alcohol; the first hard carbon coating layer is formed. The cladding layer is formed by carbon fiber-polyvinyl alcohol preparation in step 1; the carbon fibers are uniformly distributed in the first hard carbon cladding layer and the second hard carbon cladding layer.
实施例5Example 5
步骤一，利用破碎机对石油焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:3～4μm，D50:5～7μm，D90:12～15μm，D max﹤25μm的石墨原料颗粒，将碳纳米管和聚氨酯按质量比1:99，分别加入到乙醇中，控制固含量为55％，搅拌以使碳纳米管和聚氨酯溶解于乙醇，得到碳纳 米管-聚氨酯的混合液，其中碳纳米管平均长径比为3128； Step 1, use a crusher to coarsely crush the petroleum coke raw material to obtain crushed material with a particle size of less than 5mm, and then use a mechanical mill to pulverize to a particle size of: D10: 3～4μm, D50: 5～7μm, D90: 12～15μm, D max ﹤ 25μm graphite raw material particles, carbon nanotubes and polyurethane were added to ethanol at a mass ratio of 1:99, and the solid content was controlled to 55%, and stirred to dissolve carbon nanotubes and polyurethane in ethanol to obtain carbon nanotube-polyurethane The mixed solution, wherein the average aspect ratio of carbon nanotubes is 3128;
步骤二，将石墨原料颗粒转移至滚筒喷雾包衣设备中，滚筒转速为18r/min，通过二流体喷嘴将碳纳米管-聚氨酯的混合液以55mL/min速度喷洒在翻滚的石墨原料颗粒表面，并在90℃下热风下干燥，包衣处理时间为40min，得到一次颗粒前驱体；Step 2, the graphite raw material particles are transferred to the drum spray coating equipment, the drum rotation speed is 18r/min, and the carbon nanotube-polyurethane mixed solution is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle, And dried under hot air at 90°C, the coating treatment time is 40min, and the primary particle precursor is obtained;
步骤三，升高滚筒内物料温度至250℃，将熔融沥青通过二流体喷嘴喷洒在一次颗粒前驱体的表面，调节滚筒转速为30r/min，沥青喷洒流量为90mL/min，喷洒时间为30min，停止喷洒后，将滚筒转速调整至40r/min，同时将滚筒内物料5h升至650℃，并保温3h，冷却降温得到二次颗粒，二次颗粒的中值粒径D50为16μm，粒度分布Span为0.85；Step 3, raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650℃ for 5h, keep the temperature for 3h, and cool down to obtain secondary particles. The median particle size D50 of the secondary particles is 16μm, and the particle size distribution Span is 0.85;
步骤四，调整滚筒转速至18r/min，通过二流体喷嘴将碳纳米管-聚氨酯的混合液以60mL/min速度喷洒在翻滚球形的二次颗粒表面，并在90℃下热风下干燥，喷雾包衣处理时间为40min，将包覆有碳纳米管-聚氨酯的二次颗粒进行高温石墨化，石墨化炉为艾奇逊炉，石墨化温度2900℃，石墨化时间4h，得到石墨复合材料。Step 4: Adjust the rotating speed of the drum to 18r/min, spray the carbon nanotube-polyurethane mixture on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90°C. The coating treatment time is 40min, and the carbon nanotube-polyurethane-coated secondary particles are subjected to high-temperature graphitization. The graphitization furnace is an Acheson furnace, the graphitization temperature is 2900°C, and the graphitization time is 4h to obtain a graphite composite material.
本实施例得到的石墨复合材料中在结构上与实施例1相近，与实施例1材料组成不同的是第二硬炭包覆层由步骤四碳纳米管-聚氨酯制备形成；第一硬炭包覆层由步骤一碳纳米管-聚氨酯制备形成。The graphite composite material obtained in this example is similar in structure to Example 1, and the material composition of Example 1 is different in that the second hard carbon coating layer is prepared from carbon nanotube-polyurethane in step 4; The coating is formed by the carbon nanotube-polyurethane preparation in step one.
实施例6Example 6
步骤一，利用破碎机对煤系针状焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:3～4μm，D50:5～7μm，D90:12～15μm，D max﹤25μm的石墨原料颗粒，将碳纳米管和酚醛树脂按质量比1:9，分别加入到乙醇中，控制固含量为55％，搅拌以使碳纳米管和酚醛树脂溶解于乙醇，得到碳纳米管-酚醛树脂的混合液，其中碳纳米管的平均长径比为3800； Step 1, use a crusher to roughly crush the coal-based needle coke raw material to obtain crushed material with a particle size of less than 5 mm, and then use a mechanical mill to pulverize to a particle size of: D10: 3-4 μm, D50: 5-7 μm, D90: 12-15 μm, D max < 25μm graphite raw material particles, carbon nanotubes and phenolic resin were added to ethanol at a mass ratio of 1:9, the solid content was controlled to 55%, and stirred to dissolve the carbon nanotubes and phenolic resin in ethanol to obtain Carbon nanotube-phenolic resin mixture, wherein the average aspect ratio of carbon nanotubes is 3800;
步骤二，将石墨原料颗粒转移至滚筒喷雾包衣设备中，滚筒转速为18r/min，通过二流体喷嘴将碳纳米管-酚醛树脂的混合液以55mL/min速度喷洒在翻滚的石墨原料颗粒表面，并在90℃下热风下干燥，包衣处理时间为40min，得到一次颗粒前驱体；In step 2, the graphite raw material particles are transferred to the drum spray coating equipment, and the rotating speed of the drum is 18r/min, and the mixed solution of carbon nanotube-phenolic resin is sprayed on the surface of the tumbling graphite raw material particles at a speed of 55mL/min through a two-fluid nozzle. , and dried under hot air at 90°C, and the coating treatment time was 40min to obtain the primary particle precursor;
步骤三，升高滚筒内物料温度至250℃，将熔融沥青通过二流体喷嘴喷洒在一次颗粒前驱体的表面，调节滚筒转速为30r/min，沥青喷洒流量为90mL/min，喷洒时间为30min，停止喷洒后，将滚筒转速调整至40r/min，同时将滚筒内物料5h升至650℃，并保温3h，冷却降温得到二次颗粒，二次颗粒的中值粒径D50为19μm，粒度分布Span为0.75；Step 3, raising the temperature of the material in the drum to 250°C, spraying the molten asphalt on the surface of the primary particle precursor through a two-fluid nozzle, adjusting the drum rotation speed to 30r/min, the asphalt spraying flow rate to 90mL/min, and the spraying time to 30min. After stopping spraying, adjust the rotation speed of the drum to 40r/min, and at the same time raise the material in the drum to 650℃ for 5h, keep the temperature for 3h, and cool down to obtain secondary particles. The median particle size D50 of the secondary particles is 19μm, and the particle size distribution Span is 0.75;
步骤四，调整滚筒转速至18r/min，通过二流体喷嘴将碳纳米管-酚醛树脂的混合液以60mL/min速度喷洒在翻滚球形的二次颗粒表面，并在90℃下热风下干燥，喷雾包衣处理时间为40min，将包覆有碳纳米管-酚醛树脂的二次颗粒进行高温石墨化，石墨化炉为内窜炉，石墨化温度2900℃，石墨化时间4h，得到石墨复合材料。 Step 4, adjust the rotating speed of the drum to 18r/min, spray the mixture of carbon nanotube-phenolic resin on the surface of the tumbling spherical secondary particles at a speed of 60mL/min through a two-fluid nozzle, and dry it under hot air at 90°C. The coating treatment time is 40min, and the carbon nanotube-phenolic resin-coated secondary particles are graphitized at high temperature.
本实施例得到的石墨复合材料中在结构上与实施例1相近。The structure of the graphite composite material obtained in this example is similar to that of Example 1.
实施例7Example 7
与实施例1的区别在于，控制步骤一中聚合物固含量(即聚合物前驱体)为35％。The difference from Example 1 is that the solid content of the polymer (ie, the polymer precursor) in the control step 1 is 35%.
本实施例得到的石墨复合材料中在结构上与实施例1相近。The structure of the graphite composite material obtained in this example is similar to that of Example 1.
实施例8Example 8
与实施例1的区别在于，控制步骤一中聚合物固含量(即聚合物前驱体)为65％。The difference from Example 1 is that the solid content of the polymer (ie, the polymer precursor) in the control step 1 is 65%.
本实施例得到的石墨复合材料中在结构上与实施例1相近。The structure of the graphite composite material obtained in this example is similar to that of Example 1.
对比例1Comparative Example 1
利用破碎机对油系针状生焦原料粗破，得到粒度小于5mm破碎料，再利用机械磨粉碎至粒度为：D10:5μm，D50:9μm，D90:917μm，D max﹤25μm的石墨原料颗粒； Use a crusher to roughly crush the oil-based needle-shaped green coke raw materials to obtain crushed materials with a particle size of less than 5mm, and then use a mechanical mill to pulverize to the particle size of D10: 5μm, D50: 9μm, D90: 917μm, D max <25μm graphite raw material particles ;
按质量比22:3称取石墨原料颗粒与熔融沥青，石墨原料颗粒与熔融沥青混合30min后，投入到加 热反应釜内进行造粒，反应釜为加热搅拌反应釜，加热条件为：4h常温升温至650℃，保温2h后降温冷却，整个反应过程搅拌速度为15r/min，N 2流量为4L/min；造粒后得到二次颗粒的粒度：D10为8μm，D50为18μm，D90为28μm，Dmax为33μm； Weigh the graphite raw material particles and the molten pitch at a mass ratio of 22:3. After mixing the graphite raw material particles and the molten pitch for 30 minutes, put them into a heating reaction kettle for granulation. The reaction kettle is a heating and stirring reaction kettle, and the heating conditions are: 4h normal temperature temperature to 650°C, keep the temperature for 2h, then cool down and cool down, the stirring speed of the whole reaction process is 15r/min, and the N 2 flow rate is 4L/min; the particle size of the secondary particles obtained after granulation: D10 is 8 μm, D50 is 18 μm, D90 is 28 μm, Dmax is 33μm;
将二次颗粒进行石墨化处理3h，石墨化炉为内串炉，石墨化温度为2900℃，经过石墨化处理后，得到石墨复合材料。The secondary particles are subjected to graphitization treatment for 3 hours, the graphitization furnace is an inner string furnace, and the graphitization temperature is 2900° C. After the graphitization treatment, a graphite composite material is obtained.
该对比例得到的石墨复合材料中，石墨复合材料仅包括石墨和形成于石墨表面的无定型炭。In the graphite composite material obtained in this comparative example, the graphite composite material only includes graphite and amorphous carbon formed on the surface of the graphite.
对比例2Comparative Example 2
与实施例1的区别在于，不进行步骤三和步骤四。The difference from Example 1 is that Step 3 and Step 4 are not performed.
该对比例得到的石墨复合材料中，石墨复合材料仅包括石墨和包覆于石墨表面的第一硬炭包覆层(由步骤一碳纳米管-酚醛树脂制备形成)。In the graphite composite material obtained in this comparative example, the graphite composite material only includes graphite and a first hard carbon coating layer (formed by carbon nanotube-phenolic resin preparation in step 1) coated on the surface of the graphite.
对比例3Comparative Example 3
与实施例1的区别在于，不进行步骤四。The difference from Example 1 is that step 4 is not performed.
本实施例得到的石墨复合材料中，石墨复合材料仅包括二次颗粒内核，二次颗粒结构与实施例相同。In the graphite composite material obtained in this example, the graphite composite material only includes the core of secondary particles, and the structure of the secondary particles is the same as that of the embodiment.
将以上实施例的对比例制备的石墨复合材料进行以下测试：The graphite composites prepared by the comparative examples of the above embodiments are subjected to the following tests:
(一)材料性能测试(1) Material performance test
针对以下实施例和对比例制备得到的石墨复合材料，进行石墨复合材料性能的测定，测定方法如下：For the graphite composite materials prepared by the following examples and comparative examples, the performance of the graphite composite materials was measured, and the measuring method was as follows:
(1)石墨复合材料中值粒径D50、粒度分布span((D90-D10)/D50)的测定：(1) Determination of median particle size D50 and particle size distribution span ((D90-D10)/D50) of graphite composite materials:
采用马尔文3000型号粒度仪，利用粒度分析激光衍射方法进行测量。Using a Malvern 3000 particle size analyzer, the particle size analysis laser diffraction method was used to measure.
(2)石墨复合材料的比表面积测定：(2) Determination of specific surface area of graphite composites:
采用麦克比表3020仪器，利用气体吸附BET方法进行测量。The measurement was performed using a Macbee 3020 instrument using the gas adsorption BET method.
(3)石墨复合材料的取向度I 004/I 110测定： (3) Determination of orientation degree I 004 /I 110 of graphite composite material:
在1.65g/cm 3的压实密度下，利用XRD测试石墨复合材料的取向度I 004/I 110，XRD测试采用荷兰-帕纳科X'pert PRO型号仪器进行测量。 Under the compaction density of 1.65 g/cm 3 , the degree of orientation I 004 /I 110 of the graphite composite material was tested by XRD, and the XRD test was measured by the Netherlands-PANalytical X'pert PRO model instrument.
(4)石墨复合材料的硬炭包覆层厚度测定：(4) Determination of hard carbon coating thickness of graphite composites:
采用日本日立S4800型号仪器，观察颗粒的截面，测试包覆层截面。Using Japan's Hitachi S4800 model instrument, the cross section of the particles was observed and the cross section of the coating layer was tested.
(5)石墨复合材料的拉曼I D/I G的测定： (5) Determination of Raman ID/ IG of graphite composites:
采用Renishaw inVia拉曼仪，利用Map image acquisition方法进行测量。The Renishaw inVia Raman instrument was used for measurement using the Map image acquisition method.
(6)石墨复合材料表面的硬炭包覆层硬度测定：(6) Hardness determination of hard carbon coating on the surface of graphite composite material:
以石墨复合材料表面的硬炭包覆层为例，测定其硬度，需要说明的是本公开实施例中，第一硬炭包覆层和所述第二硬炭包覆层的硬度相同或者相近。在高分辨显微镜(日本岛津的动态超显微硬度计DUH-211S)下，纳米压头载载荷力P的作用下，压头在颗粒表面压出一个地面为圆形的压痕，测定圆形的直径R，则硬度H等于所用载荷与压痕面积的比值H＝1.8544×(P/(π×0.25R 2))其中P为施加载荷力，单位为mN；R为圆形压痕直径，单位为μm；1.8544为修正系数，π为圆周常数。 Taking the hard carbon coating layer on the surface of the graphite composite material as an example, the hardness is measured. It should be noted that in the embodiment of the present disclosure, the hardness of the first hard carbon coating layer and the second hard carbon coating layer are the same or similar. . Under the high-resolution microscope (Dynamic Ultra Micro Hardness Tester DUH-211S from Shimadzu, Japan), under the action of the load force P of the nano-indenter, the indenter presses a circular indentation on the surface of the particle. The diameter R of the shape, then the hardness H is equal to the ratio of the applied load to the indentation area H=1.8544×(P/(π×0.25R 2 )) where P is the applied load force, in mN; R is the diameter of the circular indentation , the unit is μm; 1.8544 is the correction coefficient, and π is the circular constant.
(7)硬炭包覆层的单位截面积中所含碳骨架材料的数量测定：(7) Determination of the quantity of carbon skeleton material contained in the unit cross-sectional area of the hard carbon coating:
在日本日立SU9000超高分辨率发射扫描电子显微镜镜下进行测试。The test was carried out under the microscope of Hitachi SU9000 ultra-high-resolution emission scanning electron microscope.
(8)石墨复合材料的电导率测定：采用上下平面可控压探头(厦门元能科技粉末电导仪)直接测量极片，获得极片厚度方向的整体电阻及电阻率，计算公式：σ＝L/RS，其中L为极片厚度，S为测试点面积，R为测试阻值。(8) Determination of electrical conductivity of graphite composite materials: Use the upper and lower plane controllable pressure probes (Xiamen Yuanneng Technology Powder Conductivity Meter) to directly measure the pole piece to obtain the overall resistance and resistivity in the thickness direction of the pole piece, the calculation formula: σ=L /RS, where L is the thickness of the pole piece, S is the area of the test point, and R is the test resistance value.
石墨复合材料性能测试结果参加下表1：The performance test results of graphite composite materials are shown in Table 1 below:
表1石墨复合材料性能测试Table 1 Graphite composite material performance test
Figure PCTCN2022079995-appb-000001
Figure PCTCN2022079995-appb-000001
(二)电化学性能测试：(2) Electrochemical performance test:
将本公开各实施例和对比例得到的石墨复合材料作为负极活性物质，按照负极活性物质：导电炭黑：CMC：SBR＝95.3:1.5:1.4:1.8的质量比混合，以去离子水为溶剂混浆后涂布于铜箔上，涂布面密度为6.5±0.1mg/cm 2，经过90℃真空干燥后，得到负极极片，并将负极极片辊压至压实密度为1.65±0.02g/cc；将负极极片、锂片、电解液(1mol/L的LiPF 6，EC:EMC＝1:1)和Celgard2400隔膜组装成2016型扣式电池：将得到的电池在25±2℃和-20±2℃环境下进行倍率和循环测试，倍率测试条件为：①0.1C放至0.01V，恒压5h；0.1C充至1.5V；②0.2C放至0.01V，恒压0.01C；0.2C充至1.5V；③0.2C放至0.01V，恒压0.01C；2C充至1.5V，0.2C充至1.5V；④0.2C放至0.01V，恒压0.01C；0.2C充至1.5V；⑤1C放至0.01V，恒压0.01C；0.2C充至1.5V；⑥2C放至0.01V；循环测试条件为：0.2C倍率充放电，电压区间0.01V～1.5V。分别测试首周充电比容量、首周效率和50周扣电循环稳定性，并计算1C(CC/0.2C CC+CV)倍充和50周容量保持率，测试结果如下表2所示： The graphite composite materials obtained in the examples and comparative examples of the present disclosure were used as the negative electrode active material, mixed according to the mass ratio of negative electrode active material: conductive carbon black: CMC: SBR=95.3:1.5:1.4:1.8, and deionized water was used as the solvent After mixing the slurry, coat it on the copper foil, and the coating surface density is 6.5±0.1mg/cm 2 . After vacuum drying at 90°C, a negative electrode pole piece is obtained, and the negative pole piece is rolled to a compacted density of 1.65±0.02 g/cc; assemble the negative pole piece, lithium piece, electrolyte (1mol/L LiPF 6 , EC:EMC=1:1) and Celgard2400 separator into a 2016 type button cell: store the obtained battery at 25±2℃ The rate and cycle test are carried out in the environment of -20±2℃. The rate test conditions are: ①0.1C to 0.01V, constant voltage for 5h; 0.1C to 1.5V; ②0.2C to 0.01V, constant voltage 0.01C ; 0.2C to 1.5V; ③0.2C to 0.01V, constant voltage 0.01C; 2C to 1.5V, 0.2C to 1.5V; ④0.2C to 0.01V, constant voltage 0.01C; 0.2C to charge ⑤1C to 0.01V, constant voltage 0.01C; 0.2C to 1.5V; ⑥2C to 0.01V; cycle test conditions: 0.2C rate charge and discharge, voltage range 0.01V ~ 1.5V. The first-week charging specific capacity, the first-week efficiency, and the 50-week derating cycle stability were respectively tested, and the 1C (CC/0.2C CC+CV) double charge and 50-week capacity retention rate were calculated. The test results are shown in Table 2 below:
表2石墨复合材料的电化学性能测试Table 2 Electrochemical performance test of graphite composites
Figure PCTCN2022079995-appb-000002
Figure PCTCN2022079995-appb-000002
Figure PCTCN2022079995-appb-000003
Figure PCTCN2022079995-appb-000003
根据上表2，通过与对比例1～3对比分析可知，本公开实施例1～6所制备的石墨复合材料具有良好的容量保持率，提升了石墨负极材料的快充性能。并且，分别与对比例1、对比例2及对比例3对比分析可知，由此说明本公开实施例第二硬炭包覆层和第一硬炭包覆层的设置，减少了充放电过程中的内阻，有利于锂离子快速嵌入嵌出，以此使得石墨负极材料具有良好的容量保持率，甚至在-20℃的极低温度下的较高的放电容量保持率。本公开的实施例1～6分别和对比例1、2和3的对比可知，在对比例1、2和3中，同样存在无定型炭(即由熔融沥青形成)结构，对比例1、2和3制备的复合材料中的无定型炭在电池的循环过程中，因收缩会产生孔洞，从而复合材料内部会产生缝隙和孔洞，因此电解液会通过孔洞与裂缝进入颗粒内核，与内核颗粒直接接触，从而导致复合材料在循环过程中引起过度膨胀和收缩，从而降低电池的电化学性能，诸如快充性能、1C倍充保持率、50周容量保持率和-20℃低温放电容量保持率。在同样的上述环境下，在本公开中，由于复合材料的一次颗粒存在第一硬炭包覆层，从而阻止了电解液与一次颗粒的直接接触，进而有效保护了材料在电池循环过程中适当地膨胀和收缩，从而提高了本公开复合材料的电化学性能，从而进一步保证石墨负极材料较高的容量保持率和优异的快充性能。同时，结合表1和表2可以看出，本公开的实施例1～6与实施例7相比，本公开实施例制备的材料的硬炭包覆层厚度和硬度在本公开的范围内，可以进一步保证材料避免在充放电过程中的体积膨胀，从而进一步提高了材料的循环性能，如50周容量保持率所有提高。同时本公开的实施例1～6与实施例8相比可以看出，本公开实施例制备的材料的硬炭包覆层厚度和硬度，可以保证电池的较高的能量密度，有效提高电池的克容量和首次库伦效率。以上仅为本公开可选的实施例，并非因此限制本公开的专利范围，凡是在本公开的申请构思下，利用本公开说明书所作的等效结构变换，或直接/间接运用在其他相关的技术领域均包括在本公开的专利保护范围内。According to Table 2 above, it can be seen from the comparative analysis with Comparative Examples 1 to 3 that the graphite composite materials prepared in Examples 1 to 6 of the present disclosure have good capacity retention and improve the fast charging performance of the graphite negative electrode material. In addition, it can be seen from the comparative analysis with Comparative Example 1, Comparative Example 2 and Comparative Example 3, which illustrate the arrangement of the second hard carbon coating layer and the first hard carbon coating layer in the embodiment of the present disclosure, which reduces the number of times during the charging and discharging process. The high internal resistance is conducive to the rapid intercalation and intercalation of lithium ions, so that the graphite anode material has a good capacity retention rate, and even a high discharge capacity retention rate at an extremely low temperature of -20 °C. The comparison of Examples 1 to 6 of the present disclosure with Comparative Examples 1, 2 and 3 respectively shows that in Comparative Examples 1, 2 and 3, there is also an amorphous carbon (that is, formed from molten pitch) structure, and Comparative Examples 1 and 2 The amorphous carbon in the composite materials prepared by and 3 will generate holes due to shrinkage during the cycle of the battery, so that there will be gaps and holes inside the composite material, so the electrolyte will enter the particle core through the holes and cracks, directly with the core particles. contact, resulting in excessive expansion and shrinkage of the composite during cycling, thereby reducing the electrochemical performance of the battery, such as fast charge performance, 1C double charge retention, 50-cycle capacity retention, and -20°C low-temperature discharge capacity retention. Under the same above-mentioned environment, in the present disclosure, due to the existence of the first hard carbon coating layer on the primary particles of the composite material, the direct contact between the electrolyte and the primary particles is prevented, thereby effectively protecting the material in the battery cycle process. Therefore, the electrochemical performance of the composite material of the present disclosure is improved, thereby further ensuring the high capacity retention rate and excellent fast charging performance of the graphite negative electrode material. At the same time, it can be seen from Table 1 and Table 2 that, compared with Example 7, the thickness and hardness of the hard carbon coating layer of the materials prepared in the examples of the present disclosure are within the scope of the present disclosure, It can further ensure that the material avoids volume expansion during the charging and discharging process, thereby further improving the cycle performance of the material, such as the 50-cycle capacity retention rate. At the same time, comparing Examples 1 to 6 of the present disclosure with Example 8, it can be seen that the thickness and hardness of the hard carbon coating layer of the materials prepared in the examples of the present disclosure can ensure a higher energy density of the battery and effectively improve the battery's performance. Gram capacity and first coulombic efficiency. The above are only optional embodiments of the present disclosure, and are not intended to limit the scope of the present disclosure. Under the application concept of the present disclosure, the equivalent structural transformations made by the description of the present disclosure are used, or directly/indirectly applied to other related technologies. All fields are included within the scope of patent protection of the present disclosure.
工业实用性Industrial Applicability
本公开提供的石墨复合材料作为石墨负极材料时，由于石墨具有高充放电容量的特质，以此提高了石墨负极材料的充放电容量。并且，本公开的石墨复合材料中的硬炭材料具有良好的快充性能，从而提高了石墨负极材料的快充性能。即本公开的技术方案能够在提高石墨负极材料的电容量的同时，提升石墨负极材料的快充性能，具有优异的应用价值。When the graphite composite material provided by the present disclosure is used as a graphite negative electrode material, since graphite has the characteristics of high charge and discharge capacity, the charge and discharge capacity of the graphite negative electrode material is improved. In addition, the hard carbon material in the graphite composite material of the present disclosure has good fast charging performance, thereby improving the fast charging performance of the graphite negative electrode material. That is, the technical solution of the present disclosure can improve the fast charging performance of the graphite negative electrode material while improving the electric capacity of the graphite negative electrode material, and has excellent application value.

Claims (19)

  1. 一种石墨复合材料，其特征在于，所述石墨复合材料为核壳结构，所述石墨复合材料包括二次颗粒内核和包覆于所述二次颗粒内核表面的第二硬炭包覆层；A graphite composite material, characterized in that the graphite composite material has a core-shell structure, and the graphite composite material comprises a secondary particle inner core and a second hard carbon coating layer coated on the surface of the secondary particle inner core;
    所述二次颗粒内核包括一次颗粒和无定型炭，所述一次颗粒包括石墨和包覆于所述石墨表面的第一硬炭包覆层；The secondary particle core includes primary particles and amorphous carbon, and the primary particles include graphite and a first hard carbon coating layer coated on the surface of the graphite;
    所述第一硬炭包覆层和所述第二硬炭包覆层包括碳骨架材料。The first hard carbon coating layer and the second hard carbon coating layer include a carbon framework material.
  2. 如权利要求1所述的石墨复合材料，其特征在于，所述石墨复合材料包括如下特征(1)至(3)中的至少一个：The graphite composite material according to claim 1, wherein the graphite composite material comprises at least one of the following features (1) to (3):
    (1)所述碳骨架材料均匀分布在所述第一硬炭包覆层和所述第二硬炭包覆层中；(1) The carbon framework material is uniformly distributed in the first hard carbon coating layer and the second hard carbon coating layer;
    (2)以所述第一硬炭包覆层的质量为100％计，所述第一硬炭包覆层中的碳骨架材料的含量为1％～10％；(2) Taking the mass of the first hard carbon coating layer as 100%, the content of the carbon framework material in the first hard carbon coating layer is 1% to 10%;
    (3)以所述第二硬炭包覆层的质量为100％计，所述第二硬炭包覆层中的碳骨架材料的含量为1％～10％。(3) Based on the mass of the second hard carbon coating layer as 100%, the content of the carbon skeleton material in the second hard carbon coating layer is 1% to 10%.
  3. 如权利要求1或2所述的石墨复合材料，其特征在于，所述石墨复合材料包括如下特征(1)至(3)中的至少一个：The graphite composite material according to claim 1 or 2, wherein the graphite composite material comprises at least one of the following features (1) to (3):
    (1)所述石墨包括人造石墨和天然石墨中的至少一种；(1) described graphite comprises at least one in artificial graphite and natural graphite;
    (2)所述无定型炭包括软炭；(2) the amorphous carbon includes soft carbon;
    (3)所述一次颗粒之间填充有所述无定型炭。(3) The amorphous carbon is filled between the primary particles.
  4. 如权利要求1-3中任一项所述的石墨复合材料，其特征在于，所述碳骨架材料包括碳纳米管和碳纤维中的至少一种。The graphite composite material according to any one of claims 1-3, wherein the carbon skeleton material comprises at least one of carbon nanotubes and carbon fibers.
  5. 如权利要求4所述的石墨复合材料，其特征在于，所述石墨复合材料包括如下特征(1)至(3)中的至少一个：The graphite composite material according to claim 4, wherein the graphite composite material comprises at least one of the following features (1) to (3):
    (1)所述第一硬炭包覆层的单位截面积中所含碳骨架材料的数量为2根/μm 2-5根/μm 2； (1) the number of carbon framework materials contained in the unit cross-sectional area of the first hard carbon coating layer is 2 pieces/μm 2 -5 pieces/μm 2 ;
    (2)所述第二硬炭包覆层的单位截面积中所含碳骨架材料的数量为2根/μm 2-5根/μm 2； (2) the number of carbon framework materials contained in the unit cross-sectional area of the second hard carbon coating layer is 2 pieces/μm 2 -5 pieces/μm 2 ;
    (3)所述碳骨架材料的长径比为200～5000。(3) The aspect ratio of the carbon skeleton material is 200-5000.
  6. 如权利要求1-5中任一项所述的石墨复合材料，其特征在于，所述石墨复合材料包括如下特征(1)至(2)中的至少一个：The graphite composite material according to any one of claims 1-5, wherein the graphite composite material comprises at least one of the following features (1) to (2):
    (1)所述第一硬炭包覆层的硬度为50N/mm 2～100N/mm 2； (1) The hardness of the first hard carbon coating layer is 50N/mm 2 to 100N/mm 2 ;
    (2)所述第二硬炭包覆层的硬度为50N/mm 2～100N/mm 2。 (2) The hardness of the second hard carbon coating layer is 50 N/mm 2 to 100 N/mm 2 .
  7. 如权利要求1-6中任一项所述的石墨复合材料，其特征在于，所述石墨复合材料包括如下特征(1)至(2)中的至少一个：The graphite composite material according to any one of claims 1-6, wherein the graphite composite material comprises at least one of the following features (1) to (2):
    (1)所述第一硬炭包覆层中，所述碳骨架材料的界面百分比A为10％～60％，其中A＝H/(n×0.7)，n为所述第一硬炭包覆层的单位截面积中所含碳骨架材料的数量，H为所述第一硬炭包覆层的硬度；(1) In the first hard carbon coating layer, the interface percentage A of the carbon framework material is 10% to 60%, where A=H/(n×0.7), and n is the first hard carbon coating the quantity of carbon skeleton material contained in the unit cross-sectional area of the coating, and H is the hardness of the first hard carbon coating;
    (2)所述第二硬炭包覆层中，所述碳骨架材料的界面百分比A为10％～60％，其中A＝H/(n×0.7)， n为所述第二硬炭包覆层的单位截面积中所含碳骨架材料的数量，H为所述第二硬炭包覆层的硬度。(2) In the second hard carbon coating layer, the interface percentage A of the carbon framework material is 10% to 60%, where A=H/(n×0.7), and n is the second hard carbon coating The amount of carbon skeleton material contained in the unit cross-sectional area of the coating, and H is the hardness of the second hard carbon coating.
  8. 如权利要求1-7中任一项所述的石墨复合材料，其特征在于，所述石墨复合材料的电导率为200S/m～400S/m。The graphite composite material according to any one of claims 1-7, wherein the electrical conductivity of the graphite composite material is 200 S/m to 400 S/m.
  9. 如权利要求1-8中任一项所述的石墨复合材料，其特征在于，所述石墨复合材料包括如下特征(1)至(6)中的至少一个：The graphite composite material according to any one of claims 1-8, wherein the graphite composite material comprises at least one of the following features (1) to (6):
    (1)所述石墨复合材料的中值粒度D50为13μm～24μm；(1) The median particle size D50 of the graphite composite material is 13 μm to 24 μm;
    (2)所述石墨复合材料的粒度分布(D90-D10)/D50为0.75～1.0；(2) The particle size distribution (D90-D10)/D50 of the graphite composite material is 0.75-1.0;
    (3)所述石墨复合材料的比表面积为0.8m 2/g～2.0m 2/g； (3) the specific surface area of the graphite composite material is 0.8m 2 /g～2.0m 2 /g;
    (4)所述石墨复合材料的取向度I 004/I 110为2.0～8.0； (4) The orientation degree I 004 /I 110 of the graphite composite material is 2.0 to 8.0;
    (5)所述石墨复合材料的拉曼I D/I G为1.0～2.0； (5) Raman ID/ IG of the graphite composite material is 1.0-2.0 ;
    (6)所述第一硬炭包覆层和所述第二硬炭包覆层两者的厚度为50nm～200nm。(6) The thicknesses of both the first hard carbon coating layer and the second hard carbon coating layer are 50 nm to 200 nm.
  10. 一种石墨复合材料的制备方法，其特征在于，包括以下步骤：A method for preparing a graphite composite material, comprising the following steps:
    将石墨原料颗粒与含有碳骨架材料和聚合物的溶液混合造粒以在所述石墨原料颗粒表面形成第一聚合物前驱体包覆层，得到一次颗粒前驱体；Mixing and granulating the graphite raw material particles with a solution containing a carbon framework material and a polymer to form a first polymer precursor coating layer on the surface of the graphite raw material particles to obtain a primary particle precursor;
    将所述一次颗粒前驱体和碳源混合，炭化后得到二次颗粒；及mixing the primary particle precursor and the carbon source, and carbonizing to obtain secondary particles; and
    将所述二次颗粒和所述含有碳骨架材料和聚合物的溶液混合造粒以在所述二次颗粒表面形成第二聚合物前驱体包覆层，石墨化后得到石墨复合材料。The secondary particles and the solution containing the carbon skeleton material and the polymer are mixed and granulated to form a second polymer precursor coating layer on the surface of the secondary particles, and the graphite composite material is obtained after graphitization.
  11. 如权利要求10所述的石墨复合材料的制备方法，其特征在于，所述含有碳骨架材料和聚合物的溶液通过以下制备：将碳骨架材料和聚合物在溶剂中分散均匀，得到含有碳骨架材料和聚合物的溶液。The method for preparing a graphite composite material according to claim 10, wherein the solution containing the carbon skeleton material and the polymer is prepared by dispersing the carbon skeleton material and the polymer uniformly in a solvent to obtain a solution containing the carbon skeleton material and the polymer. Solutions of materials and polymers.
  12. 如权利要求11所述的石墨复合材料的制备方法，其特征在于，所述石墨复合材料的制备方法包括如下特征(1)至(4)中的至少一个：The preparation method of the graphite composite material according to claim 11, wherein the preparation method of the graphite composite material comprises at least one of the following features (1) to (4):
    (1)所述碳骨架材料包括碳纳米管和碳纤维中的至少一种；(1) The carbon skeleton material includes at least one of carbon nanotubes and carbon fibers;
    (2)所述聚合物包括酚醛树脂、聚丙烯树脂及聚氨酯中的至少一种；(2) the polymer comprises at least one of phenolic resin, polypropylene resin and polyurethane;
    (3)所述溶剂包括有机溶剂和水中的至少一种；(3) described solvent comprises at least one of organic solvent and water;
    (4)所述聚合物前驱体的固含量为40％～60％。(4) The solid content of the polymer precursor is 40% to 60%.
  13. 如权利要求10-12中任一项所述的石墨复合材料的制备方法，其特征在于，制备所述一次颗粒前驱体的步骤为：The method for preparing a graphite composite material according to any one of claims 10-12, wherein the step of preparing the primary particle precursor is:
    将所述聚合物前驱体喷洒至石墨原料颗粒表面；spraying the polymer precursor onto the surface of the graphite raw material particles;
    翻滚所述石墨原料颗粒以在所述石墨原料颗粒表面形成第一聚合物前驱体包覆层；tumbling the graphite raw material particles to form a first polymer precursor coating layer on the surface of the graphite raw material particles;
    干燥处理形成有第一聚合物前驱体包覆层的所述石墨原料颗粒。The graphite raw material particles formed with the first polymer precursor coating layer are dried.
  14. 如权利要求13所述的石墨复合材料的制备方法，其特征在于，所述石墨复合材料的制备方法包括如下特征(1)至(3)中的至少一个：The preparation method of the graphite composite material according to claim 13, wherein the preparation method of the graphite composite material comprises at least one of the following features (1) to (3):
    (1)所述石墨原料颗粒包括天然石墨微粒和软炭微粒中的至少一种；(1) the graphite raw material particles include at least one of natural graphite particles and soft carbon particles;
    (2)所述石墨原料颗粒的翻滚速度为5r/min～30r/min；(2) The tumbling speed of the graphite raw material particles is 5r/min～30r/min;
    (3)所述干燥处理的温度为80℃～95℃，时间为20min～40min。(3) The temperature of the drying treatment is 80°C to 95°C, and the time is 20min to 40min.
  15. 如权利要求10-14中任一项所述的石墨复合材料的制备方法，其特征在于，制备所述二次颗粒的步骤为：The preparation method of graphite composite material according to any one of claims 10-14, wherein the step of preparing the secondary particles is:
    将碳源喷洒至所述一次颗粒前驱体表面；spraying a carbon source onto the surface of the primary particle precursor;
    翻滚所述一次颗粒前驱体以使所述一次颗粒前驱体之间通过所述碳源粘结；tumbling the primary particle precursors to bond the primary particle precursors through the carbon source;
    炭化处理粘结有所述碳源的所述一次颗粒前驱体。Carbonizing the primary particle precursor to which the carbon source is bound.
  16. 如权利要求15所述的石墨复合材料的制备方法，其特征在于，所述石墨复合材料的制备方法包括如下特征(1)至(4)中的至少一个：The preparation method of the graphite composite material according to claim 15, wherein the preparation method of the graphite composite material comprises at least one of the following features (1) to (4):
    (1)所述碳源包括易石墨化原料；(1) the carbon source includes easily graphitized raw materials;
    (2)所述碳源包括沥青；(2) the carbon source includes pitch;
    (3)所述一次颗粒前驱体的翻滚速度为5r/min～30r/min；(3) The tumbling speed of the primary particle precursor is 5r/min～30r/min;
    (4)所述炭化处理的温度为450℃～750℃，时间为1h～5h。(4) The temperature of the carbonization treatment is 450℃～750℃, and the time is 1h～5h.
  17. 如权利要求10-16中任一项所述的石墨复合材料的制备方法，其特征在于，制备所述石墨复合材料的步骤为：The preparation method of the graphite composite material according to any one of claims 10-16, wherein the step of preparing the graphite composite material is:
    将所述聚合物前驱体喷洒至所述二次颗粒表面；spraying the polymer precursor onto the surface of the secondary particles;
    翻滚所述二次颗粒以在所述二次颗粒表面形成第二聚合物前驱体包覆层；tumbling the secondary particles to form a second polymer precursor coating layer on the surfaces of the secondary particles;
    石墨化处理形成有所述第二聚合物前驱体包覆层的所述二次颗粒。The secondary particles formed with the second polymer precursor coating layer are graphitized.
  18. 如权利要求17所述的石墨复合材料的制备方法，其特征在于，所述石墨复合材料的制备方法包括如下特征(1)至(3)中的至少一个：The preparation method of the graphite composite material according to claim 17, wherein the preparation method of the graphite composite material comprises at least one of the following features (1) to (3):
    (1)所述二次颗粒的中值粒径为13μm～24μm，粒度分布(D90-D10)/D50为0.75～1.0；(1) The median particle size of the secondary particles is 13 μm to 24 μm, and the particle size distribution (D90-D10)/D50 is 0.75 to 1.0;
    (2)所述二次颗粒的翻滚速度为5r/min～30r/min；(2) The tumbling speed of the secondary particles is 5r/min～30r/min;
    (3)所述石墨化处理的温度2400℃～3000℃，时间为1h～6h。(3) The temperature of the graphitization treatment is 2400°C to 3000°C, and the time is 1h to 6h.
  19. 一种锂离子电池，其特征在于，所述锂离子电池包括权利要求1至9中任一项所述的石墨复合材料；和/或，所述锂离子电池包括权利要求10至18中任一项所述的制备方法制备而成的石墨复合材料。A lithium ion battery, characterized in that the lithium ion battery comprises the graphite composite material according to any one of claims 1 to 9; and/or, the lithium ion battery comprises any one of claims 10 to 18 The graphite composite material prepared by the preparation method described in the item.
PCT/CN2022/079995 2021-03-10 2022-03-09 Graphite composite material and preparation method therefor, and lithium-ion battery WO2022188818A1 (en)

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