WO2023051205A1 - 负极材料及其制备方法、锂离子电池 - Google Patents

负极材料及其制备方法、锂离子电池 Download PDF

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WO2023051205A1
WO2023051205A1 PCT/CN2022/117555 CN2022117555W WO2023051205A1 WO 2023051205 A1 WO2023051205 A1 WO 2023051205A1 CN 2022117555 W CN2022117555 W CN 2022117555W WO 2023051205 A1 WO2023051205 A1 WO 2023051205A1
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silicon
carbon
negative electrode
electrode material
carbon composite
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French (fr)
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安威力
何鹏
任建国
贺雪琴
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BTR New Material Group Co Ltd
Dingyuan New Energy Technology Co Ltd
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BTR New Material Group Co Ltd
Dingyuan New Energy Technology Co Ltd
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Priority to KR1020237027119A priority Critical patent/KR102924226B1/ko
Priority to EP22874594.9A priority patent/EP4266416A4/en
Priority to JP2023547158A priority patent/JP7670275B2/ja
Priority to US18/546,083 priority patent/US20240322131A1/en
Publication of WO2023051205A1 publication Critical patent/WO2023051205A1/zh
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
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    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
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    • 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
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    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of negative electrode materials, in particular, to negative electrode materials, their preparation methods, and lithium-ion batteries.
  • Silicon is the second most abundant element in the earth's crust. It is a common semiconductor material and has become an indispensable and important technical basis for modern high-tech society. Elemental silicon has extensive and important roles in energy, semiconductor, organic silicon and metallurgical industries. Applications. At present, the anode materials of mature commercial lithium-ion batteries are mainly graphite-like carbon materials, but the theoretical lithium storage capacity of carbon materials is only 372mAh/g, which cannot meet people's needs for high energy density materials.
  • Silicon as an anode material for lithium-ion batteries, has High theoretical capacity (about 4200mAh/g), ten times the capacity of commercial graphite, has great prospects in energy storage, but the volume expansion of silicon anode materials is relatively large (>300%) during the process of deintercalating lithium , the high volume change effect leads to its poor cycle stability, which leads to a certain distance from its practical application.
  • the application proposes a negative electrode material, a preparation method thereof, and a lithium ion battery.
  • the negative electrode material of the present application has high conductivity, high capacity, can effectively suppress volume expansion, and improve the electrochemical performance of the negative electrode material as a battery.
  • an embodiment of the present application provides an anode material, the anode material includes an inner core and a porous silicon-carbon composite layer distributed on at least part of the surface of the inner core, the inner core includes a silicon-based material, and the porous silicon-carbon
  • the composite layer includes a carbon matrix and silicon particles dispersed in the carbon matrix, and the carbon matrix has holes.
  • At least some of the silicon particles are dispersed in the pores of the carbon matrix.
  • the inner core is a silicon-based material.
  • the silicon-based material includes at least one of silicon element, silicon alloy, and silicon oxide.
  • the silicon-based material includes a silicon alloy
  • the silicon alloy is at least one selected from a silicon-tin alloy, a silicon-lithium alloy, and a silicon-germanium alloy.
  • the silicon-based material includes silicon oxide, and the silicon oxide is SiO x , where 0 ⁇ x ⁇ 2.
  • the shape of the silicon-based material includes at least one of a granular shape, a spherical shape, a spherical shape, a wire shape, and a tubular shape.
  • the silicon-based material has a median particle size of 0.1 ⁇ m to 15 ⁇ m.
  • the silicon-based material has a median particle size of 0.5 ⁇ m to 5 ⁇ m.
  • the composite layer has a thickness of 0.01 ⁇ m ⁇ 10 ⁇ m.
  • the ratio of the median particle diameter of the silicon-based material to the thickness of the composite layer is (1 ⁇ 10):1.
  • the porosity of the negative electrode material is 10%-50%.
  • the mass proportion of the carbon matrix in the porous silicon-carbon composite layer is 5%-80%.
  • the carbon matrix has pores, and the pores include macropores and mesopores.
  • the carbon matrix has holes, and the holes include macropores and mesopores, and the pore volume ratio of the macropores to the mesopores is (0.5 ⁇ 5):1.
  • the median diameter of the silicon particles is 1 nm to 500 nm.
  • the silicon particles have a median diameter of 10 nm to 100 nm.
  • the mass ratio of the silicon particles to the silicon-based material is (0.3 ⁇ 0.7):1.
  • the carbon matrix includes a solid portion and holes, and at least some silicon particles are dispersed in the solid portion.
  • the carbon matrix includes a solid portion and holes, some silicon particles are dispersed in the holes, and some silicon particles are dispersed in the solid portion.
  • the carbon matrix includes a solid part and holes, some silicon particles are dispersed in the holes, and some silicon particles are dispersed in the solid part; the silicon particles dispersed in the solid part and the silicon particles dispersed in the solid part
  • the molar ratio of silicon particles in the holes is 1:(0.5-3).
  • the rebound rate of the composite layer is above 90%.
  • the negative electrode material further includes a coating layer formed on at least part of the surface of the composite layer.
  • the cladding layer includes at least one of carbon materials, metal oxides, nitrides, and conductive polymers.
  • the coating layer includes a carbon material including at least one of graphene, soft carbon, hard carbon, and amorphous carbon.
  • the cladding layer includes a metal oxide
  • the metal oxide includes at least one of titanium oxide, aluminum oxide, lithium oxide, cobalt oxide, and vanadium oxide.
  • the cladding layer includes a nitride including at least one of titanium nitride, vanadium nitride, cobalt nitride, nickel nitride, and carbon nitride.
  • the cladding layer includes a conductive polymer including polyaniline, polyacetylene, polypyrrole, polythiophene, poly-3-hexylthiophene, polyparastyrene, polypyridine, and polyphenylene at least one of vinylidene.
  • the thickness of the cladding layer is 3nm-200nm.
  • the median particle size of the negative electrode material is 0.1 ⁇ m ⁇ 20 ⁇ m.
  • the specific surface area of the negative electrode material is 1.0m 2 /g ⁇ 50m 2 /g.
  • the powder tap density of the negative electrode material is 1.0 g/cm 3 to 1.8 g/cm 3 .
  • the oxygen content in the negative electrode material is less than 20%.
  • the embodiment of the present application provides a method for preparing an anode material, comprising the following steps:
  • thermal reaction is carried out, so that at least part of the A x Si alloy is converted into an oxide of metal A, and the oxide of metal A is removed to obtain a silicon-carbon composite material.
  • the silicon-based material includes at least one of silicon element, silicon alloy, and silicon oxide.
  • the silicon-based material includes a silicon alloy
  • the silicon alloy is at least one selected from a silicon-tin alloy, a silicon-lithium alloy, and a silicon-germanium alloy.
  • the silicon-based material includes silicon oxide, and the silicon oxide is SiO x , where 0 ⁇ x ⁇ 2.
  • the shape of the silicon-based material includes at least one of a granular shape, a spherical shape, a spherical shape, a wire shape, and a tubular shape.
  • the shape of the silicon-based material is spherical or spheroidal.
  • the silicon-based material has a median particle size of 0.1 ⁇ m to 15 ⁇ m.
  • the median particle size of the silicon-based material is 1 ⁇ m ⁇ 5 ⁇ m.
  • the active metal A includes at least one of Mg, Al, Ca and Zn.
  • the molar ratio of the silicon-based material to the active metal A is 1:(0.1-3).
  • the step of preparing the composite includes: alloying the silicon-based material with the reactive metal A under a protective atmosphere.
  • the step of preparing the composite includes: performing an alloying reaction between the silicon-based material and the active wave metal A under a protective atmosphere, wherein the temperature of the alloying reaction is 400°C to 900°C, The holding time is 1h ⁇ 24h.
  • the step of preparing the composite includes: carrying out an alloying reaction between the silicon-based material and the active wave metal A under a protective atmosphere, wherein the heating rate of the alloying reaction is 1 °C/min ⁇ 10°C/min.
  • the step of preparing the composite includes: alloying the silicon-based material with active wave metal A under a protective atmosphere, wherein the protective atmosphere includes nitrogen, helium, neon, argon At least one of gas, krypton and xenon.
  • the thickness of the AxSi alloy formed on at least part of the surface of the silicon-based material is 0.05 ⁇ m ⁇ 20 ⁇ m.
  • the composite has a median particle size of 0.1 ⁇ m to 20 ⁇ m.
  • the carbon source includes an organic carbon source.
  • the carbon source includes an organic carbon source
  • the organic carbon source includes aldehydes, phenols and their corresponding halogenated compounds that are solid at room temperature and have a boiling point ⁇ 650°C.
  • the carbon source includes an inorganic carbon source.
  • the carbon source comprises an inorganic carbon source comprising a carbon-containing inorganic salt.
  • the step of thermally reacting the composite with a carbon source is carried out under a protective atmosphere, which includes nitrogen, helium, neon, argon, krypton, and xenon. at least one of .
  • the step of removing the reactive metal A in the thermal reaction product includes acid washing the thermal reaction product with an acid solution.
  • the step of removing the reactive metal A in the thermal reaction product includes pickling the thermal reaction product with an acid solution, and the acid solution includes at least one of hydrochloric acid, nitric acid and sulfuric acid.
  • the molar ratio of the complex to the carbon source is 1:(0.01 ⁇ 10).
  • the temperature of the thermal reaction is 200°C to 950°C.
  • the heat preservation time of the thermal reaction is 1 h to 24 h.
  • the heating rate of the thermal reaction is 1°C/min ⁇ 20°C/min.
  • the method further includes forming a coating layer on the surface of the silicon-carbon composite material to obtain a negative electrode material.
  • the step of forming a coating layer on the surface of the silicon-carbon composite material includes: sintering the mixture containing the silicon-carbon composite material and polymer particles under vacuum conditions to form the coating layer.
  • the polymer particles include at least one of pitch, resin, polyester-based polymer, and polyamide-based polymer.
  • the mass ratio of the polymer particles to the silicon-carbon composite material is 1:(0.1-10).
  • the sintering temperature is 600°C-1000°C.
  • the holding time for the sintering is 1 h to 24 h.
  • the heating rate of the sintering is 1° C./min ⁇ 20° C./min.
  • the vacuum degree under the vacuum condition is less than 0.1Mpa.
  • the step of forming a coating layer on the surface of the silicon-carbon composite material includes: using a chemical synthesis method to synthesize a polymer on the surface of the silicon-carbon composite material to form a coating layer.
  • the polymer comprises at least one of a resinous polymer and a polyester polymer
  • the step of forming a coating layer on the surface of the silicon-carbon composite material includes: using chemical vapor deposition of an organic carbon source to form a coating layer on the surface of the silicon-carbon composite material.
  • the present application provides a lithium ion battery, which comprises the negative electrode material described in the first aspect or the negative electrode material prepared by the preparation method described in the second aspect.
  • a porous silicon-carbon composite layer is set on the surface of the silicon-based material core as a buffer layer, and the porous silicon-carbon composite layer includes a carbon matrix and silicon particles dispersed in the carbon matrix.
  • the carbon matrix has holes, which can effectively relieve the volume expansion of the silicon-based material and act as an elastic conductor.
  • the porous silicon-carbon composite layer can provide ion and electron transmission paths, enhance the conductivity of the silicon-based material and the outside world, and improve the rate performance.
  • the silicon particles are embedded in the carbon matrix, that is, the carbon matrix is used to wrap the silicon particles, which can improve the conductivity of the silicon particles, thereby improving the rate performance of the negative electrode material, and meeting the requirements of the battery to achieve fast charging characteristics.
  • the preparation method of the negative electrode material provided by this application is to form a layer of silicon alloy A x Si on the surface of the silicon-based material by alloying the silicon-based material with the active metal A, that is, to obtain the A x Si-wrapped silicon-based material
  • the compound, the compound reacts thermally with the carbon source, so that at least part of the A x Si alloy is converted into the oxide of metal A, the oxide of metal A is removed, and a carbon matrix with holes can be formed on the surface of the silicon-based material, and the reduction can be obtained
  • the silicon particles are dispersed in the carbon matrix, and the pores of the fluffy carbon matrix can effectively relieve the volume expansion of the silicon-based material, and act as an elastic conductor, which can provide more ion and electron transmission paths, and enhance the conductivity between the silicon core and the outside world. Improve magnification performance.
  • the preparation method of the present application is simple and easy, and can effectively solve the problems of large volume expansion and poor conductivity of the silicon negative electrode, thereby improving the electrochemical performance of
  • Fig. 1 is the structural representation of negative electrode material of the present application
  • FIG. 2 is a schematic diagram of the structure of silicon particles embedded in holes 22 of the present application.
  • Figure 3 is a schematic structural diagram of the preparation process of the negative electrode material provided by an embodiment of the present application.
  • Fig. 4 is the preparation flowchart of the negative electrode material of the present application.
  • Fig. 5 is the scanning electron microscope picture of the negative electrode material that the application embodiment 1 prepares
  • Figure 6 is a Raman diagram of the negative electrode material prepared in Example 1 of the present application.
  • Fig. 7 is the XRD pattern of the negative electrode material prepared in Example 1 of the present application.
  • FIG. 8 is a cycle performance curve of the negative electrode material prepared in Example 1 of the present application.
  • the embodiment of the present application provides a negative electrode material.
  • the structural diagram of the negative electrode material is shown in Figure 1.
  • the negative electrode material has a core-shell structure.
  • the negative electrode material includes an inner core 1 and a porous silicon-carbon composite layer distributed on at least part of the surface of the inner core 1.
  • the inner core 1 includes a silicon-based material
  • the porous silicon-carbon composite layer 2 includes a carbon matrix 21 and silicon particles 23 dispersed in the carbon matrix 21
  • the carbon matrix 21 has holes 22 .
  • a porous silicon-carbon composite layer 2 is set on the surface of the silicon-based material core 1 as a buffer layer, and the porous silicon-carbon composite layer 2 includes a carbon matrix 21 and silicon particles 23 dispersed in the carbon matrix 21 , the carbon matrix 21 has a hole 22, the hole 22 can effectively relieve the volume expansion of the silicon-based material, and act as an elastic conductor, the porous silicon-carbon composite layer 2 can provide ion and electron transmission paths, and enhance the conductivity between the inner core 1 and the outside world , to improve the rate performance.
  • the silicon particles 23 are embedded in the carbon matrix 21, that is, the carbon matrix 21 is used to wrap the silicon particles 23, which can improve the conductivity of the silicon particles, thereby improving the rate performance of the negative electrode material, and meeting the requirements for fast charging characteristics of the battery.
  • the silicon particles 23 are dispersed in the carbon matrix 21, which can also avoid the problem of agglomeration of the silicon particles, resulting in stress concentration and damage to the structure of the entire negative electrode material.
  • the silicon particles 23 are dispersed in the pores 22 of the carbon matrix 21 .
  • Figure 2 it is a schematic diagram of the structure of the silicon particles dispersed in the holes 22 of the present application. It can be understood that when the silicon particles 23 are dispersed in the holes 22, the silicon particles 23 are not completely filled, and there is a certain space in the holes 22 for Alleviating the volume expansion of the silicon particles 23 can prevent the destruction of the entire negative electrode material due to volume expansion, reduce the expansion of the electrode film, and improve the safety of the battery.
  • the carbon matrix 21 includes a solid part and holes 22 distributed on the solid part, at least part of the silicon particles 23 are embedded in the solid part, and part of the silicon particles 23 are embedded in the solid part.
  • the silicon particle 23 is embedded in the solid part, that is, the solid part of the carbon matrix 21 is tightly wrapped on the surface of the silicon particle 23 .
  • some silicon particles 23 are dispersed in the holes, and some silicon particles 23 are embedded in the solid portion.
  • the silicon particles 23 can be dispersed only in the solid part of the carbon matrix 21, or only in the holes 22 of the carbon matrix 21, or there are silicon particles 23 in both the solid part and the holes 22, wherein the solid part and the holes
  • the loading capacity of silicon in the negative electrode material can be greatly increased, and the problem of uneven dispersion of silicon particles in the carbon material can be effectively solved, thereby improving the effective utilization rate of silicon particles, and then improving the efficiency of the entire negative electrode material.
  • Tap density and specific capacity increase the energy density of the entire battery material.
  • the core includes a silicon-based material.
  • the silicon-based material includes at least one of silicon element, silicon alloy and silicon oxide.
  • the silicon alloy includes at least one of a silicon-tin alloy, a silicon-lithium alloy, and a silicon-germanium alloy.
  • the silicon oxide is SiO x , 0 ⁇ x ⁇ 2.
  • the shape of the silicon-based material includes at least one of a granular shape, a spherical shape, a spherical shape, a wire shape, and a tubular shape.
  • the shape of the silicon-based material is spherical or spheroidal.
  • the median particle size of the silicon-based material is 0.1 ⁇ m to 15 ⁇ m; specifically, it can be 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 7 ⁇ m, 8 ⁇ m , 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, or 15 ⁇ m, etc.
  • the median particle size of the silicon-based material is 0.5 ⁇ m ⁇ 5 ⁇ m.
  • the thickness of the porous silicon-carbon composite layer 2 is 0.01 ⁇ m to 10 ⁇ m; specifically, the thickness of the porous silicon-carbon composite layer 2 can be 0.01 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m , 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, etc. Of course, other values within the above range can also be used, which are not limited here. When the porous silicon-carbon composite layer 2 is less than 0.01 ⁇ m, it is difficult to support silicon particles 23.
  • the thickness of the porous silicon-carbon composite layer 2 is 0.5 ⁇ m ⁇ 5 ⁇ m. It can be understood that the thickness of the porous silicon-carbon composite layer 2 of the present application is consistent with the thickness of the carbon matrix 21, and the thickness of the carbon matrix 21 is also 0.01 ⁇ m ⁇ 10 ⁇ m.
  • the ratio of the median particle size of the silicon-based material to the thickness of the porous silicon-carbon composite layer is (1-10):1, and the thickness ratio can specifically be 1:1, 2:1 , 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc. Of course, it can also be other values within the above range, which is not limited here .
  • the ratio of the median diameter of the silicon-based material 1 to the thickness of the porous silicon-carbon composite layer 2 is (1-3): 1.
  • the proportion of the median particle size can play a good conductive role in the silicon-based material 1 with a large size range, and can effectively absorb the volume expansion of the silicon-based material 1 without losing electrical contact.
  • the porosity of the negative electrode material is 10% to 50%.
  • the porosity of the negative electrode material can be 10%, 20%, 30%, 40%, 50%, etc., of course, it can also be within the above range Other values are not limited here. Controlling the porosity of the negative electrode material within the above range can satisfy the volume expansion space of the silicon particles 23 and the silicon-based material.
  • the porosity of the negative electrode material is 20%-40%. It can be understood that the porosity refers to the ratio of the volume of pores in the negative electrode material to the total volume of the negative electrode material.
  • the mass proportion of the carbon matrix in the porous silicon-carbon composite layer is 5% to 80%, specifically 5%, 10%, 20%, 30%, 40%, 50%, or 60%. , 70% and 80%, etc., of course, can also be other values within the above range, which are not limited here.
  • the negative electrode material of the present application chooses the carbon matrix 21 as the carrier of the silicon particles 23, which can increase the capacity of the negative electrode material without destroying its structure. Controlling the content of the carbon matrix 21 in the porous silicon-carbon composite layer 2 within the above range can accommodate the silicon particles 23 well, and at the same time, the porous silicon-carbon composite layer 2 can also tightly and firmly wrap the silicon-based material 1 to avoid silicon embedding. The volume change after lithium causes the silicon-based material to detach from the porous silicon-carbon composite layer 2 and lose electrical contact.
  • the molar ratio of the silicon particles embedded in the solid part to the silicon particles dispersed in the holes is 1: (0.5-3); specifically, it can be 1:0.5, 1:0.8, 1:1, 1:1.5, 1:1.8, 1:2, 1:2.5, 1:2.8 or 1:3, etc., are not limited here.
  • the silicon content of the two positions By controlling the silicon content of the two positions, the demand for high rate and low expansion silicon carbon products can be met, and the balance between high rate and low expansion can be achieved.
  • the molar ratio of the silicon particles in the solid part is relatively large, the silicon particles embedded in the solid part are completely wrapped by the carbon matrix, which can improve the conductivity of the silicon particles and improve the composite material. The rate performance meets the fast charging characteristics of the battery.
  • the rebound rate of the porous silicon-carbon composite layer when the compression rate of the porous silicon-carbon composite layer reaches 50%, the rebound rate of the porous silicon-carbon composite layer is more than 90%, and the specific rebound rate of the porous silicon-carbon composite layer can be 91%, 93%. , 95% and 98%, etc., the rebound rate of the porous silicon-carbon composite layer is controlled to more than 90%, so as to avoid the powdering of the material and the loss of electrical contact with the silicon-based material due to the volume expansion of the negative electrode material.
  • the carbon matrix 21 has pores 22, and the pores 22 include macropores and mesopores.
  • macropores are pores with a pore diameter greater than 50nm
  • mesopores are pores with a pore diameter between 2nm and 50nm
  • the pore volume ratio of macropores to mesopores is (0.5 ⁇ 5):1; specifically, macropores and The pore volume ratio of the mesopores is 0.5:1, 1:1, 2:1, 3:1, 4:1 and 5:1, etc.
  • the pores 22 in this application are rich in macropores and mesopores, the volume expansion of the silicon-based material 1 can be relieved by compressing the pores 22, and the silicon particles in the pores 22 also have enough space to relieve the volume expansion.
  • the expansion-shrinkage characteristics of silicon particles 23 after deintercalation of lithium can be well synchronized with the expansion or contraction behavior of silicon-based material 1, and always maintain good electrical contact with silicon-based material 1, ensuring Excellent electron transport properties.
  • the median diameter of the silicon particles is 1 nm to 500 nm, and the median diameter of the silicon particles can specifically be 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 400nm or 500nm, etc.
  • other values within the above range can also be used, which are not limited here.
  • the median particle size of the silicon particles within the above-mentioned range is to avoid pulverization of the material due to volume expansion during the lithium intercalation process of the silicon particles, thereby causing structural damage.
  • the median diameter of the silicon particles is 5nm-200nm. More preferably, the silicon particles have a median diameter of 10 nm to 100 nm.
  • the mass ratio of silicon particles to the silicon-based material is (0.3-0.7):1, specifically 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, etc., Of course, other values within the above range may also be used, which are not limited here. Controlling the mass ratio of silicon particles to silicon-based materials within the above range can ensure that the distribution of silicon in the negative electrode material has a certain concentration gradient, that is, the distribution of silicon in the negative electrode material gradually decreases from the inside to the outside, so that Ensure that the lithium ion diffusion has a uniform concentration gradient, and avoid the electrochemical polarization caused by the uneven concentration of lithium ion diffusion, which will eventually lead to the deterioration of electrochemical performance.
  • the negative electrode material further includes a coating layer 3 formed on at least part of the surface of the porous silicon-carbon composite layer 2 .
  • the coating layer 3 can cooperate with the composite layer 2 to relieve the volume expansion of the silicon-based material. , reduce the volume expansion of the entire negative electrode material, and reduce the swelling of the electrode sheet.
  • the cladding layer 3 includes at least one of carbon materials, metal oxides, nitrides and conductive polymers.
  • the carbon material includes at least one of graphene, soft carbon, hard carbon, and amorphous carbon.
  • the coating layer is made of carbon material
  • the porous silicon-carbon composite layer located on the inside includes carbon matrix and silicon particles
  • the coating layer located on the outside is made of carbon material.
  • the double-layer carbon layer can enhance the conductivity of the negative electrode material, making the negative electrode material exhibit It has the advantages of high capacity, long cycle life, high rate performance and low expansion, and can be widely used in the field of high-performance lithium-ion battery anodes.
  • the metal oxide includes at least one of titanium oxide, aluminum oxide, lithium oxide, cobalt oxide, and vanadium oxide.
  • the nitride includes at least one of titanium nitride, vanadium nitride, cobalt nitride, nickel nitride, and carbon nitride.
  • the cladding layer includes a conductive polymer including polyaniline, polyacetylene, polypyrrole, polythiophene, poly-3-hexylthiophene, polyparastyrene, polypyridine, and polyphenylene at least one of vinylidene.
  • the thickness of the cladding layer is 3nm-200nm, specifically 3nm, 5nm, 10nm, 50nm, 100nm, 150nm, 200nm, etc. Of course, it can also be other values within the above range, which is not limited here .
  • the thickness of the coating layer is 5 nm to 50 nm. It can be understood that the coating layer can reduce the contact between silicon and electrolyte, reduce the formation of passivation film, increase the conductivity of the negative electrode material, suppress the volume expansion of the negative electrode material, and improve the battery life. Reversible capacitance and cycle performance.
  • the porosity of the coating layer is 2% to 10%, specifically 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% and 10%, etc., Of course, other values within the above range may also be used, which are not limited here. It can be understood that the porosity of the cladding layer is less than that of the porous silicon-carbon composite layer (10% to 50%). Compared with the porous silicon-carbon composite layer, the cladding layer is a dense layer, and the cladding layer of a certain thickness It can effectively isolate the intrusion of electrolyte. Preferably, the porosity of the cladding layer is 5%-10%. In addition, the pore volume of the coating layer accounts for less than 50% of the pore volume of the entire negative electrode material, which is beneficial for the coating layer to isolate the electrolyte and reduce the swelling of the electrode sheet.
  • the median particle size of the negative electrode material is 0.1 ⁇ m to 20 ⁇ m
  • the median particle size of the negative electrode material can specifically be 0.1 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, etc., of course, can also be other values within the above range, which are not limited here.
  • the median particle size of the negative electrode material is 0.1 ⁇ m to 10 ⁇ m, and more preferably, the median particle size of the negative electrode material is 1 ⁇ m to 5 ⁇ m. It can be understood that controlling the average particle size of the negative electrode material within the above range is beneficial Improvement of cycle performance of anode materials.
  • the specific surface area of the negative electrode material is 1.0m 2 /g to 50m 2 /g, and the specific surface area of the negative electrode material can be 1.0m 2 /g, 1.5m 2 /g, 10m 2 /g, 20m 2 /g, 30m 2 /g, 40m 2 /g, 50m 2 /g, etc., of course, can also be other values within the above range, and are not limited here. It can be understood that controlling the specific surface area of the negative electrode material within the above range can suppress the volume expansion of the negative electrode material, which is beneficial to the improvement of the cycle performance of the negative electrode material.
  • the powder tap density of the negative electrode material is 1.0 g/cm 3 to 1.8 g/cm 3
  • the powder tap density of the negative electrode material can be specifically 1.0 g/cm 3 or 1.2 g/cm 3 , 1.3g/cm 3 , 1.4g/cm 3 , 1.5g/cm 3 , 1.6g/cm 3 , 1.7g/cm 3 , 1.1g/cm 3 and 1.8g/cm 3 etc.
  • the powder tap density of the negative electrode material is 1.3g/cm 3 -1.6g/cm 3 .
  • the oxygen content in the negative electrode material is less than 20%. It can be understood that if the oxygen content in the negative electrode material is too high, the primary efficiency of the negative electrode material will be reduced.
  • the embodiment of the present application provides a method for preparing an anode material, as shown in FIG. 3 and FIG. 4 , which are sequentially the structural flow chart and the preparation flow chart of the preparation of the anode material of the present application.
  • the method includes the following steps:
  • Step S120 mixing the composite with a carbon source and performing a thermal reaction, so that at least part of the A x Si alloy is converted into an oxide of metal A, and the oxide of metal A is removed to obtain a silicon-carbon composite material.
  • the preparation method of the negative electrode material provided by this application is to form a layer of silicon alloy A x Si on the surface of the silicon-based material by alloying the silicon-based material with the active metal A, that is, to obtain A x Si-wrapped
  • the silicon element in the silicon alloy A x Si will be embedded in the carbon material in situ in the form of silicon particles.
  • a fluffy and porous carbon matrix material can be formed on the surface of the silicon-based material. Silicon particles are dispersed in the carbon matrix, and the pores of the fluffy carbon matrix can effectively relieve the volume expansion of the silicon-based material, and act as an elastic conductor, which can provide more ion and electron transmission paths, enhance the conductivity of the silicon core and the outside world, and improve rate performance.
  • the preparation method of the present application is simple and easy, and can effectively solve the problems of large volume expansion and poor conductivity of the silicon negative electrode, thereby improving the electrochemical performance of the negative electrode material as a battery.
  • step S110 includes: performing an alloying reaction between the silicon-based material and the reactive metal A under a protective atmosphere. It can be understood that after the alloying reaction, the surface part of the silicon-based material reacts with the active metal A to form a layer of silicon alloy A x Si, and the inner silicon-based material does not react, so that the A x Si-wrapped silicon-based material is obtained. Complex.
  • the molar ratio of the silicon-based material to the active metal A is 1:(0.1-3); specifically, the molar ratio of the silicon-based material to the active metal A can be 1:0.1, 1: 0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc. Of course, other values within the above range can also be used, which are not limited here.
  • the thickness of the silicon alloy A x Si is controlled by controlling the molar ratio of the silicon-based material to or the active metal.
  • the silicon-based material includes at least one of silicon element, silicon alloy, and silicon oxide.
  • the silicon alloy is selected from at least one of silicon-tin alloys, silicon-lithium alloys, and silicon-germanium alloys;
  • the silicon oxide is SiO x , 0 ⁇ x ⁇ 2; specifically, it can be SiO 0.1 , SiO 0.2 , SiO 0.5 , SiO 0.8 , SiO 1.2 , SiO 1.5 , SiO 1.8 , SiO 1.9 or SiO 2.0 etc.
  • the reaction of silicon oxide and active metal A can generate silicon alloy A x Si and active metal oxide.
  • the shape of the silicon-based material includes at least one of a granular shape, a spherical shape, a spherical shape, a wire shape, and a tubular shape.
  • the silicon material of the present application can adopt silicon materials of various shapes, the process is simple, and the universality is strong.
  • the shape of the silicon-based material is spherical or spheroidal.
  • the median particle size of the silicon-based material is 0.1 ⁇ m to 15 ⁇ m; specifically, it can be 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 7 ⁇ m, 8 ⁇ m , 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, or 15 ⁇ m, etc.
  • the median particle size of the silicon-based material is 0.5 ⁇ m ⁇ 5 ⁇ m.
  • active metal A includes at least one of Mg, Al, Ca, and Zn.
  • the silicon-based material and the active wave metal A before the alloying reaction of the silicon-based material and the active wave metal A, the silicon-based material and the active wave metal A can be mixed, and the mixing method can include magnetic stirring, mechanical stirring, ultrasonic dispersion and grinding dispersion. any of the
  • the way of alloying reaction may be, for example, any one of vacuum sintering, hot pressing sintering and normal pressure sintering.
  • the temperature of the alloying reaction is 400°C to 900°C
  • the first heat treatment temperature can specifically be 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, etc., of course, it can also be within the above range Other values within are not limited here.
  • the holding time of the alloying reaction is 1h to 24h, for example, it can be 1h, 3h, 6h, 10h, 13, 15h, 18h, 20h, 24h, etc. Of course, it can also be other values within the above range, It is not limited here.
  • the heating rate of the alloying reaction is 1°C/min to 10°C/min, such as 1°C/min, 2°C/min, 3°C/min, 4°C/min, 5°C/min , 6° C./min, 7° C./min, 8° C./min, 9° C./min, 10° C./min, etc., of course, may also be other values within the above range, which are not limited here.
  • the thickness of the A x Si alloy formed on at least part of the surface of the silicon-based material is 0.05 ⁇ m to 20 ⁇ m, specifically 0.05 ⁇ m, 0.1 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 5 ⁇ m , 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 17 ⁇ m, 20 ⁇ m, etc.
  • the thickness of the silicon alloy A x Si is mainly determined by the molar ratio of the silicon-based material to the active metal A.
  • the median particle size of the complex is 0.1 ⁇ m to 20 ⁇ m, specifically, it can be 0.1 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, etc. Of course, it can also be other values within the above range, It is not limited here. It is preferably 0.5 ⁇ m to 10 ⁇ m, more preferably 1 ⁇ m to 5 ⁇ m.
  • the protective atmosphere includes at least one of nitrogen, helium, neon, argon, krypton, and xenon.
  • Step S120 mixing the composite with a carbon source and performing a thermal reaction, so that at least part of the A x Si alloy is converted into an oxide of metal A, and the oxide of metal A is removed to obtain a silicon-carbon composite material.
  • the carbon source includes an organic carbon source, wherein the organic carbon source is solid at room temperature, aldehydes, phenols, and their corresponding halogenated compounds with a boiling point ⁇ 650°C; for example, the organic carbon source can be polyhydroxy aldehydes, hydroxyl At least one of benzaldehyde, 2-bromo-5-hydroxybenzaldehyde, 2,6-dichlorophenol and p-chlorophenol.
  • the carbon source includes an inorganic carbon source
  • the inorganic carbon source is a carbon-containing inorganic salt, including carbonate and bicarbonate
  • the inorganic carbon source can be calcium carbonate, sodium carbonate, zinc carbonate, barium carbonate, carbonate at least one of sodium bicarbonate and calcium bicarbonate.
  • step S120 is performed under a protective atmosphere, and the protective atmosphere includes at least one of nitrogen, helium, neon, argon, krypton, and xenon.
  • the carbon matrix includes a solid portion and holes distributed on the solid portion, some silicon particles are dispersed in the holes, and some silicon particles are embedded in the solid portion.
  • a part of the silicon particles obtained by reduction is embedded in the solid part of the carbon matrix and completely wrapped by carbon, which can improve the conductivity of the silicon particles, improve the rate performance of the negative electrode material, and meet the requirements of the battery to achieve fast charging characteristics; the silicon particles The other part is embedded in the pores of the carbon matrix, and the silicon particles are not completely filled, leaving enough space to relieve the volume expansion of the silicon particles, avoiding the destruction of the entire material due to volume expansion, and reducing the expansion of the electrode film, improving battery performance. security.
  • the ratio of the AxSi alloy and the carbon source can be controlled to control the molar ratio of the silicon particles embedded in the solid portion and the silicon particles dispersed in the pores.
  • the pores filled with silicon particles are mainly left by the oxide of metal A after pickling.
  • the carbon source is sufficient, the complete reaction between metal A and carbon source can be guaranteed.
  • all silicon particles are dispersed in the pores; when carbon Insufficient source, part of the A x Si alloy reacts with the carbon source to generate nano-silicon particles dispersed in the pores; the rest of the A x Si alloy will decompose into A (vapor form) and silicon particles in the carbon layer, and the silicon particles are embedded in the in the solid part. Therefore, the content of silicon particles in two different positions in the carbon matrix can be adjusted by controlling the amount of carbon source, which can meet the needs of high-magnification and low-expansion silicon-carbon composite products.
  • the carbon matrix is an amorphous porous carbon material.
  • the step of removing the metal A oxide in the thermal reaction product includes acid washing the thermal reaction product with an acid solution.
  • the thermal reaction products include carbon, silicon and oxides of active metal A, and the oxides of active metal A can be removed by acid solution treatment.
  • the thermal reaction product in an acid solution with a concentration of 1 mol/L-5 mol/L for 1 h-10 h.
  • the acid solution includes at least one of hydrochloric acid, nitric acid, and sulfuric acid.
  • the concentration of the acid solution can be specifically 1mol/L, 2mol/L, 3mol/L, 4mol/L, 5mol/L, etc., of course, it can also be other values within the above range, which is not limited here .
  • the acid solution treatment time can specifically be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc., of course, it can also be other values within the above range, which is not limited here .
  • the molar ratio of the compound to the carbon source is 1: (0.01-10), specifically 1:0.01, 1:0.1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.
  • the present application changes the size and porosity of the pores in the carbon matrix by controlling the molar ratio of the composite material M to the carbon source, that is, by controlling the molar ratio of the silicon alloy A x Si to the carbon source, specifically, the silicon alloy A x The metal A in Si reacts with the oxygen in the carbon source to form a metal oxide.
  • the carbon source is carbonized into a carbon matrix during the thermal reaction. After the metal oxide is washed off by acid, holes are left in the carbon matrix to form a carbon matrix with holes.
  • the higher the silicon content in the silicon alloy A x Si the smaller the metal content, the smaller the pore diameter; the higher the silicon content in the silicon alloy A x Si, the greater the thickness of the silicon alloy, and the carbon matrix formed by it The larger the thickness, the better the conductivity of silicon particles in a larger size range.
  • the mixing method may include any one of magnetic stirring, mechanical stirring, ultrasonic dispersion and grinding dispersion.
  • the temperature of the thermal reaction is 200°C to 950°C, specifically, it can be 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 950°C, etc. Of course, it can also be within the above range Other values within are not limited here.
  • the holding time of the thermal reaction is 1h to 24h, for example, the holding time can be 1h, 3h, 6h, 10h, 13, 15h, 18h, 20h, 24h, etc., of course, it can also be other values within the above range , is not limited here.
  • the heating rate of the thermal reaction is 1°C/min to 20°C/min, such as 1°C/min, 2°C/min, 3°C/min, 4°C/min, 5°C/min, 6°C/min, 7°C/min, 8°C/min, 9°C/min, 10°C/min, 11°C/min, 12°C/min, 13°C/min, 14°C/min, 15°C/min, 16° C./min, 17° C./min, 18° C./min, 19° C./min, 20° C./min, etc., can also be other values within the above range, which are not limited here.
  • preparation method of the present application also includes:
  • Step S130 forming a coating layer on the surface of the silicon-carbon composite material to obtain a negative electrode material.
  • the surface of the silicon-carbon composite material is coated, and the surface of the silicon-based material is sequentially provided with a fluffy carbon matrix and a coating layer wrapped with silicon particles.
  • the formation of the coating layer can further solve the volume expansion of the silicon negative electrode. Large, poorly conductive puzzles.
  • the step of forming a coating layer may also be omitted.
  • step S130 includes sintering the mixture comprising the silicon-carbon composite material and the polymer particles under vacuum conditions to form a cladding layer.
  • polymer particles can be directly used to coat the negative electrode material, so as to realize the surface coating of the negative electrode material.
  • Polymer coating treatment on the one hand, can prevent the electrolyte from entering the negative electrode material and cause side reactions to reduce the first-effect capacity; on the other hand, it can cooperate with the amorphous carbon matrix to relieve the volume expansion of silicon, reduce the volume expansion of the entire composite material, and reduce the The pads are swollen.
  • the polymer particles include at least one of pitch, resin, polyester-based polymers, and polyamide-based polymers.
  • the mass ratio of the polymer particle to the silicon-carbon composite material is 1: (0.1-10); the mass ratio of the polymer particle to the silicon-carbon composite material is specifically 1:0.1, 1:1, 1:2 . , controlling the mass ratio of the polymer particles to the silicon-carbon composite material within the above-mentioned range is conducive to improving the first-time efficiency.
  • the sintering temperature is 600°C to 1000°C, for example, it can be 600°C, 700°C, 800°C, 900°C, 1000°C, etc. Of course, it can also be other values within the above range, which will not be described here. limited.
  • the holding time for sintering is 1h to 24h, for example, it can be 1h, 3h, 6h, 10h, 13, 15h, 18h, 20h, 24h, etc. Of course, it can also be other values within the above range, here No limit.
  • the heating rate of sintering is 1°C/min to 20°C/min, such as 1°C/min, 2°C/min, 3°C/min, 4°C/min, 5°C/min, 6°C/min, °C/min, 7°C/min, 8°C/min, 9°C/min, 10°C/min, 11°C/min, 12°C/min, 13°C/min, 14°C/min, 15°C/min, 16°C °C/min, 17°C/min, 18°C/min, 19°C/min, 20°C/min, etc., of course, can also be other values within the above range, which are not limited here.
  • the degree of vacuum under vacuum conditions is less than 0.1Mpa, and the specific degree of vacuum can be 0.05Mpa, 0.06Mpa, 0.07Mpa, 0.08Mpa and 0.09Mpa, and of course other values within the above-mentioned range can also be used. Do limited.
  • step S130 includes using a chemical synthesis method to synthesize a polymer on the surface of the silicon-carbon composite material to form a coating layer.
  • the chemical synthesis method includes a polymerization reaction, wherein the monomers participating in the polymerization reaction include at least one of dopamine, tannic acid, phenolic resin, glucose, starch, melamine, urethane, and acrylic acid.
  • the cladding layer includes a polymer
  • the polymer includes at least one of a resin polymer and a polyester polymer
  • the resin polymer can be epoxy resin, acrylic resin, polyester resin, Any one of amino resin and phenolic resin
  • the polyester polymer can be any one of polyurethane, thermosetting polyester and thermoplastic polyester.
  • step S130 includes using chemical vapor deposition of an organic carbon source to form a coating layer on the surface of the silicon-carbon composite material.
  • the present application provides a lithium-ion battery, which includes the above-mentioned negative electrode material.
  • FIG. 5 is a scanning electron microscope picture of the negative electrode material in Example 1; it can be seen from the scanning electron microscope picture in FIG. 5 that a dense carbon coating layer is wrapped on the surface of the negative electrode material.
  • Figure 6 is the Raman diagram of the silicon-carbon composite negative electrode material in Example 1; the Raman spectrum of Figure 6 further proves that there is a D peak and a G peak near 1350cm -1 and 1580cm -1 , which are characteristic peaks of amorphous carbon .
  • Fig. 7 is the XRD pattern of silicon-carbon composite anode material in the present embodiment 1, can find out from the XRD pattern of Fig. 7 in the three strong peaks of 28.4 °, 47.3 ° and 56.1 ° and silicon (JCPDS No.27-1402) Corresponding to the three strong peaks, there is basically no impurity phase.
  • Fig. 8 is the cycle performance curve of the silicon-carbon composite negative electrode material in Example 1, the charge and discharge current is 1000mA/g. It can be seen from Figure 8 that the material has excellent cycle performance, and there is still a capacity of 725mAh/g after 820 cycles at a high current of 1000mA/g.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is a carbon coating layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is a carbon coating layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is an amorphous carbon coating layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is an amorphous carbon coating layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is an amorphous carbon coating layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is a phenolic resin coating layer.
  • step (3) is not carried out.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix with pores.
  • Example 1 The difference from Example 1 is that the phenolic resin in step (3) is replaced by titanium oxide.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the coating layer is a titanium oxide coating layer.
  • Example 1 The difference from Example 1 is that the phenolic resin in step (3) is replaced by titanium nitride.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core. Silicon particles in a carbon matrix, the carbon matrix has holes, and the cladding layer is a titanium nitride cladding layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core.
  • the inner core includes a silicon-germanium alloy.
  • the silicon particles in the carbon matrix, the carbon matrix has holes, and the coating layer is an amorphous carbon coating layer.
  • the negative electrode material obtained in this embodiment has a core-shell structure.
  • the negative electrode material includes an inner core and a porous silicon-carbon composite layer distributed on the surface of the inner core.
  • the inner core includes silicon oxide, and the porous silicon-carbon composite layer includes a carbon matrix and is dispersed on the The silicon particles in the carbon matrix, the carbon matrix has holes, and the coating layer is a carbon coating layer.
  • the carbon coating layer is directly prepared on the surface of the silicon core, and the specific preparation steps are as follows:
  • the silicon material and the phenolic resin are uniformly mixed at a mass ratio of 5:1, they are placed in a vacuum reaction furnace with a vacuum degree of 0.05Mpa, and then the reaction furnace is heated to 900°C at a heating rate of 3°C/min and then kept for 6 hours Make it fully react to obtain the negative electrode material.
  • the mass proportion of silicon particles in the negative electrode material the surface of the negative electrode material is peeled off layer by layer by using the focused ion beam (FIB), and each section is analyzed by combining the scanning electron microscope (SEM) and the energy dispersive spectrometer (EDS). The silicon element content in the composite layer is measured, and the total mass of silicon particles in the composite layer can be obtained by counting the silicon particle content of each section.
  • the total mass of silicon particles/mass of negative electrode material is the mass ratio of silicon particles in the negative electrode material;
  • the mass ratio of the silicon-based material core in the negative electrode material the composite negative electrode material particles are peeled off layer by layer by focused ion beam (FIB), combined with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) to analyze
  • the silicon-based material core element content of each section is measured (silicon element content is measured for the single silicon core core, silicon and metal element content is measured for the silicon alloy core, silicon and oxygen element content is measured for the silicon oxide core), and silicon-based material for each section is counted
  • the total content of core elements can be used to obtain the mass ratio of the core of the silicon-based material in the negative electrode material;
  • Pore volume ratio of macropores and mesopores The pore volume ratio of macropores to mesopores is obtained by BET-BJH test method.
  • Porosity of the negative electrode material the porosity of the negative electrode material is tested by a mercury intrusion tester
  • the powder tap density of the negative electrode material it is directly tested by the powder tap density tester;
  • the mass ratio of silicon particles to silicon-based materials the content of silicon particles is obtained by test method 1, and the content of silicon-based materials is obtained by test method 2;
  • Median particle size of silicon-based materials 10 composite anode material particles were peeled off layer by layer by focused ion beam (FIB), combined with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) for each Measure the size of the silicon-based material on the cross-section.
  • the size of the irregular silicon-based material is calculated according to the average value of the maximum length and maximum width of the section, and the size of the measured silicon-based material is counted.
  • the corresponding particle size when the cumulative particle size distribution percentage reaches 50% diameter is the median particle diameter;
  • the thickness of the porous silicon-carbon composite layer SEM characterization was carried out on a transmission electron microscope with an operating voltage of 200kV, and the thickness of the porous silicon-carbon composite layer was scaled;
  • the molar ratio of the silicon particles dispersed in the solid part and the silicon particles dispersed in the pores the negative electrode material particles are peeled off layer by layer by focused ion beam (FIB), combined with scanning Electron microscope (SEM) and energy dispersive spectrometer (EDS) analyze the element content of the silicon particles in the solid part and the silicon particles dispersed in the holes, and count the content ratio of the silicon particles in the two positions, which is the molar ratio;
  • the median particle size of the negative electrode material is tested with a laser particle size analyzer Malvern MS3000, and the particle size corresponding to the statistical cumulative particle size distribution volume percentage reaching 50% is the median particle size;
  • the specific surface area of the negative electrode material is obtained by testing with the American Mike TriStar3020 specific surface tester;
  • Oxygen content of the negative electrode material tested by German Verder ONH 2000 oxygen, nitrogen and hydrogen element analyzer;
  • the charge and discharge test of the cylindrical battery is performed on the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd., under normal temperature conditions, 0.2C constant current charge and discharge, and the charge and discharge voltage is limited to 2.75 ⁇ 4.2V.
  • the first coulombic efficiency the discharge capacity of the first cycle / the charge capacity of the first cycle.
  • the negative electrode materials prepared in Examples 1 to 5 include a core-shell structure negative electrode material composed of a silicon-based material core, a porous silicon-carbon composite layer and a cladding layer, and the pores of the porous silicon-carbon composite layer can be effectively Relieve the volume expansion of the silicon core and silicon particles, and act as an elastic conductor, which can provide more ion and electron transmission paths, enhance the conductivity between the silicon core and the outside world, and improve the rate performance.
  • the setting of the coating layer can prevent the electrolyte from entering the interior and cause side reactions to reduce the first-effect capacity.
  • the composite material prepared by the invention has the advantages of high capacity, high rate performance and low expansion, and can be widely used in the field of high-performance lithium-ion battery negative electrodes.
  • Example 6 a chemical synthesis method was used to coat the polymer on the surface of the negative electrode material to obtain a coating layer, and the prepared negative electrode material also exhibited the characteristics of low volume expansion and high capacity.
  • Example 8 and Example 9 a metal oxide layer and a nitride layer were respectively prepared on the surface of the silicon-carbon composite material N, and the obtained negative electrode material can also exhibit excellent electrochemical performance.
  • Example 10 silicon-germanium alloy was used as the core material respectively, and the obtained negative electrode material can exhibit the characteristics of low volume expansion and high capacity.
  • Example 11 uses silicon oxide (SiO) as the core material, and the obtained negative electrode material can also exhibit excellent volume expansion suppression performance, and the capacity retention rate can also be maintained at a relatively high level.
  • SiO silicon oxide
  • the porous silicon-carbon composite layer was not prepared, and the volume expansion after silicon intercalation was large, resulting in material pulverization, the capacity of the negative electrode material was low, and the expansion rate of the electrode film was large.
  • the application illustrates the detailed process equipment and process flow of the application through the above-mentioned examples, but the application is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the application must rely on the above-mentioned detailed process equipment and process flow. process can be implemented.
  • Those skilled in the art should understand that any improvement to the present application, the equivalent replacement of each raw material of the product of the present application, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present application.

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Abstract

本申请涉及负极材料领域，提供一种负极材料及其制备方法、锂离子电池，所述负极材料为核壳结构，所述负极材料包括内核及分布于所述内核的至少部分表面的多孔硅碳复合层，所述内核包括硅基材料，所述多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，所述碳基体具有孔洞。本申请的负极材料导电性高、容量高、能够有效抑制体积膨胀，提高负极材料作为电池的电化学性能。

Description

负极材料及其制备方法、锂离子电池
本申请要求于2021年09月30日提交中国专利局，申请号为202111160157.7、申请名称为“负极材料及其制备方法、锂离子电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及负极材料技术领域，具体地讲，尤其涉及负极材料及其制备方法、锂离子电池。
背景技术
硅是地壳中第二大含量元素，是一种常见的半导体材料，已经成为现代高科技社会不可或缺的重要技术基础，单质硅在能源、半导体、有机硅以及冶金工业等方面有着广泛而重要的应用。目前成熟商业锂离子电池的负极材料主要为石墨类碳材料，但碳材料的理论储锂容量仅为372mA h/g，无法满足人们对高能量密度材料的需求，硅作为锂离子电池负极材料具有很高的理论容量(约4200mA h/g)，十倍于商业用石墨的容量，在能量存储方面具有非常大的前景，但是硅负极材料脱嵌锂过程中体积膨胀较大(>300％)，高的体积变化效应导致其较差的循环稳定性，导致其离实用化有一定的距离。
因此，如何制备出具有稳定结构、容量高、膨胀低、循环性能优异的负极材料是锂离子电池领域的技术难题。
申请内容
鉴于此，本申请提出了一种负极材料及其制备方法、锂离子电池，本申请的负极材料导电性高、容量高、能够有效抑制体积膨胀，提高负极材料作为电池的电化学性能。
第一方面，本申请实施例提供一种负极材料，所述负极材料包括内核及分布于所述内核的至少部分表面的多孔硅碳复合层，所述内核包括硅基材料，所述多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，所述碳基体具有孔洞。
在一些实施方式中，至少部分硅颗粒分散在所述碳基体的孔洞中。
在一些实施方式中，所述内核为硅基材料。
在一些实施方式中，所述硅基材料包括硅单质、硅合金、硅氧化物中的至少一种。
在一些实施方式中，所述硅基材料包括硅合金，所述硅合金选自硅锡合金、硅锂合金、硅锗合金中的至少一种。
在一些实施方式中，所述硅基材料包括硅氧化物，所述硅氧化物为SiO x，0＜x≤2。
在一些实施方式中，所述硅基材料的形状包括颗粒状、球状、类球状、线状和管状中的至少一种。
在一些实施方式中，所述硅基材料的中值粒径为0.1μm～15μm。
在一些实施方式中，所述硅基材料的中值粒径为0.5μm～5μm。
在一些实施方式中，所述复合层的厚度为0.01μm～10μm。
在一些实施方式中，所述硅基材料的中值粒径与所述复合层的厚度之比为(1～10)：1。
在一些实施方式中，所述负极材料的孔隙率为10％～50％。
在一些实施方式中，所述多孔硅碳复合层中碳基体的质量占比为5％～80％。
在一些实施方式中，所述碳基体具有孔洞，所述孔洞包括大孔和介孔。
在一些实施方式中，所述碳基体具有孔洞，所述孔洞包括大孔和介孔，所述大孔与所述介孔的孔体积比为(0.5～5):1。
在一些实施方式中，所述硅颗粒的中值粒径为1nm～500nm。
在一些实施方式中，所述硅颗粒的中值粒径为10nm～100nm。
在一些实施方式中，所述硅颗粒与所述硅基材料的质量比为(0.3～0.7)：1。
在一些实施方式中，所述碳基体包括实心部分及孔洞，至少部分硅颗粒分散于所述实心部分中。
在一些实施方式中，所述碳基体包括实心部分及孔洞，部分硅颗粒分散在所述孔洞中，部分硅颗粒分散于所述实心部分中。
在一些实施方式中，所述碳基体包括实心部分及孔洞，部分硅颗粒分散在所述孔洞中，部分硅颗粒分散在所述实心部分中；分散在所述实心部分中的硅颗粒和分散在所述孔洞中的硅颗粒的摩尔比为1：(0.5～3)。
在一些实施方式中，当所述复合层压缩率达到50％时，所述复合层的回弹率为90％以上。
在一些实施方式中，所述负极材料还包括形成于所述复合层至少部分表面的包覆层。
在一些实施方式中，所述包覆层包括碳材料、金属氧化物、氮化物和导电聚合物中的至少一种。
在一些实施方式中，所述包覆层包括碳材料，所述碳材料包括石墨烯、软碳、硬碳和无定型碳中的至少一种。
在一些实施方式中，所述包覆层包括金属氧化物，所述金属氧化物包括氧化钛、氧化铝、氧化锂、氧化钴和氧化钒中的至少一种。
在一些实施方式中，所述包覆层包括氮化物，所述氮化物包括氮化钛、氮化钒、氮化钴、氮化镍和氮化碳中的至少一种。
在一些实施方式中，所述包覆层包括导电聚合物，所述导电聚合物包括聚苯胺、聚乙炔、聚吡咯、聚噻吩，聚3-己基噻吩、聚对苯乙烯、聚吡啶和聚苯亚乙烯中中的至少一种。
在一些实施方式中，所述包覆层的厚度为3nm～200nm。
在一些实施方式中，所述负极材料的中值粒径为0.1μm～20μm。
在一些实施方式中，所述负极材料的比表面积为1.0m 2/g～50m 2/g。
在一些实施方式中，所述负极材料的粉体振实密度为1.0g/cm 3～1.8g/cm 3。
在一些实施方式中，所述负极材料中的氧含量小于20％。
第二方面，本申请实施例提供一种负极材料的制备方法，包括以下步骤：
制备复合物，所述复合材料包括硅基材料和形成于所述硅基材料的至少部分表面的A xSi合金，A为活波金属，X＝1～3；
将所述复合物与碳源混合后进行热反应，使得至少部分所述A xSi合金转化为金属A的氧化物，去除所述金属A的氧化物，得到硅碳复合材料。
在一些实施方式中，所述硅基材料包括硅单质、硅合金、硅氧化物中的至少一种。
在一些实施方式中，所述硅基材料包括硅合金，所述硅合金选自硅锡合金、硅锂合金、硅锗合金中的至少一种。
在一些实施方式中，所述硅基材料包括硅氧化物，所述硅氧化物为SiO x，0＜x≤2。
在一些实施方式中，所述硅基材料的形状包括颗粒状、球状、类球状、线状和管状中的至少一种。
在一些实施方式中，所述硅基材料的形状为球状或类球状。
在一些实施方式中，所述硅基材料的中值粒径为0.1μm～15μm。
在一些实施方式中，所述硅基材料的中值粒径为1μm～5μm。
在一些实施方式中，所述活泼金属A包括Mg、Al、Ca和Zn中的至少一种。
在一些实施方式中，所述硅基材料与所述活泼金属A的摩尔比为1:(0.1～3)。
在一些实施方式中，所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应。
在一些实施方式中，所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应，其中，所述合金化反应的温度为400℃～900℃，保温时间为1h～24h。
在一些实施方式中，所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应，其中，所述合金化反应的升温速率为1℃/min～10℃/min。
在一些实施方式中，所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应，其中，所述保护气氛包括氮气、氦气、氖气、氩气、氪气及氙气中的至少一种。
在一些实施方式中，所述形成于所述硅基材料的至少部分表面的A xSi合金的厚度为0.05μm～20μm。
在一些实施方式中，所述复合物的中值粒径为0.1μm～20μm。
在一些实施方式中，所述碳源包括有机碳源。
在一些实施方式中，所述碳源包括有机碳源，所述有机碳源包括常温条件下为固态、沸点＜650℃的醛类，酚类及其对应的卤代化合物。
在一些实施方式中，所述碳源包括无机碳源。
在一些实施方式中，所述碳源包括无机碳源，所述无机碳源包括含碳无机盐。
在一些实施方式中，所述将所述复合物与碳源混合后进行热反应的步骤在保护气氛下进行，所述保护气氛包括氮气、氦气、氖气、氩气、氪气及氙气中的至少一种。
在一些实施方式中，所述去除热反应产物中的活波金属A的步骤，包括利用酸溶液将热反应产物进行酸洗。
在一些实施方式中，所述去除热反应产物中的活波金属A的步骤，包括利用酸溶液将热反应产物进行酸洗，所述酸溶液包括盐酸、硝酸和硫酸中的至少一种。
在一些实施方式中，所述复合物与所述碳源的摩尔比为1：(0.01～10)。
在一些实施方式中，所述热反应的温度为200℃～950℃。
在一些实施方式中，所述热反应的保温时间为1h～24h。
在一些实施方式中，所述热反应的升温速率为1℃/min～20℃/min。
在一些实施方式中，所述方法还包括在硅碳复合材料的表面形成包覆层，得到负极材料。
在一些实施方式中，所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层。
在一些实施方式中，所述聚合物颗粒包括沥青、树脂、聚酯类聚合物、聚酰胺类聚合物中的至少一种。
在一些实施方式中，所述聚合物颗粒与所述硅碳复合材料的质量比为1：(0.1～10)。
在一些实施方式中，所述烧结的温度为600℃～1000℃。
在一些实施方式中，所述烧结的保温时间为1h～24h。
在一些实施方式中，所述烧结的升温速率为1℃/min～20℃/min。
在一些实施方式中，所述真空条件下的真空度小于0.1Mpa。
在一些实施方式中，所述在硅碳复合材料的表面形成包覆层的步骤，包括：利用化学合成方法在硅碳复合材料表面合成聚合物，形成包覆层。
在一些实施方式中，所述聚合物包括树脂类聚合物和聚酯类聚合物中的至少一种；
在一些实施方式中，所述在硅碳复合材料的表面形成包覆层的步骤，包括：利用有机碳源的化学气相沉积在硅碳复合材料表面形成包覆层。
第三方面，本申请提供一种锂离子电池，所述锂离子电池包含第一方面所述的负极材料或第二方面所述的制备方法制得的负极材料。
本申请的技术方案至少具有以下有益的效果：
(1)本申请的负极材料，在硅基材料内核的表面设置多孔硅碳复合层作为缓冲层，所述多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，所述碳基体具有孔洞，孔洞可以有效缓解硅基材料的体积膨胀，并充当弹性导电体，多孔硅碳复合层可提供离子和电子传输路径，增强硅基材料与外界的导电性，提高倍率性能。此外，硅颗粒嵌入碳基体中，即采用碳基体包裹硅颗粒的方式，可以提高硅颗粒的导电性，进而提高负极材料的倍率性能，满足电池实现快充特性的要求。
(2)本申请提供的负极材料的制备方法，通过将硅基材料与活泼金属A合金化反应，在硅基材料的表面形成一层硅合金A xSi，即得到A xSi包裹硅基材料的复合物，复合物与碳源发生热反应，使得至少部分A xSi合金转化为金属A的氧化物，去除金属A的氧化物，可在硅基材料表面形成具有孔洞的碳基体，还原得到的硅颗粒分散在碳基体内，蓬松的碳基体的孔洞可以有效缓解硅基材料的体积膨胀，并充当弹性导电体，可提供更多的离子和电子传输路径，增强硅内核与外界导电性，提高倍率性能。本申请的制备方法具有简单易行，可以有效解决硅负极体积膨胀大，导电性差的难题，从 而提升负极材料作为电池的电化学性能。
附图说明
下面结合附图和实施例对本申请进一步说明。
图1为本申请负极材料的结构示意图；
图2为本申请硅颗粒嵌入在孔洞22的结构示意图；
图3为本申请一实施例提供的负极材料的制备流程结构示意图；
图4为本申请负极材料的制备流程图；
图5是本申请实施例1制备的负极材料的扫描电镜图片；
图6为本申请实施例1制备的负极材料拉曼图；
图7为本申请实施例1制备的负极材料的XRD图；
图8为本申请实施例1制备的负极材料的循环性能曲线。
附图中：
1-硅基材料；
2-多孔硅碳复合层；
21-碳基体；
22-孔洞；
23-硅颗粒；
3-包覆层。
具体实施方式
为了更好的理解本申请的技术方案，下面结合附图对本申请实施例进行详细描述。
应当明确，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本申请保护的范围。
在本申请实施例中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请。在本申请实施例和所附权利要求书中所使用的单数形式的“一种”、“所述”和“该”也旨在包括多数形式，除非上下文清楚地表示其它含义。
应当理解，本文中使用的术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
本申请实施例提供一种负极材料，负极材料的结构示意图如图1所示，负极材料为核壳结构，负极材料包括内核1及分布于所述内核1的至少部分表面的多孔硅碳复合层2，内核1包括硅基材料，多孔硅碳复合层2包括碳基体21及分散在所述碳基体21中的硅颗粒23，所述碳基体21具有孔洞22。
在上述技术方案中，在硅基材料内核1的表面设置多孔硅碳复合层2作为缓冲层，所述多孔硅碳复合层2包括碳基体21及分散在所述碳基体21中的硅颗粒23，所述碳 基体21具有孔洞22，孔洞22可以有效缓解硅基材料的体积膨胀，并充当弹性导电体，多孔硅碳复合层2可提供离子和电子传输路径，增强内核1与外界的导电性，提高倍率性能。此外，硅颗粒23嵌入碳基体21中，即采用碳基体21包裹硅颗粒23的方式，可以提高硅颗粒的导电性，进而提高负极材料的倍率性能，满足电池实现快充特性的要求。而且，硅颗粒23分散在碳基体21中，还可以避免硅颗粒发生团聚、进而导致应力集中使得整个负极材料结构破坏的问题。
在一些实施方式中，至少部分的硅颗粒23分散在所述碳基体21的孔洞22中。如图2所示，为本申请硅颗粒分散在孔洞22的结构示意图，可以理解，硅颗粒23分散在孔洞22中时，硅颗粒23不完全填充满，孔洞22中留有一定的空间用来缓解硅颗粒23的体积膨胀，可以避免整个负极材料由于体积膨胀而破坏，同时减少电极膜的膨胀，提高电池的安全性。
在一些实施方式中，所述碳基体21包括实心部分及分布于实心部分上的孔洞22，至少部分硅颗粒23嵌设于所述实心部分中，部分硅颗粒23嵌设于实心部分中。硅颗粒23嵌设于实心部分中，即碳基体21的实心部分紧密包裹在硅颗粒23的表面。
在一些实施方式中，部分硅颗粒23分散在所述孔洞中，部分硅颗粒23嵌设于所述实心部分中。
可以理解的，硅颗粒23可以仅分散在碳基体21的实心部分中，或仅分散在碳基体21的孔洞22内，或实心部分和孔洞22中均存在硅颗粒23，其中，实心部分和孔洞22中均存在硅颗粒23时，能够大大提高负极材料中硅的载量，可有效解决硅颗粒在碳材料中分散不均的问题，从而提高硅颗粒的有效利用率，继而提高整个负极材料的振实密度和比容量，提高整个电池材料的能量密度。
本申请通过控制多孔硅碳复合层2中不同位置硅颗粒的含量，可以满足高倍率和低膨胀型负极材料产品的需求。
在一些实施方式中，所述内核包括硅基材料。
在一些实施方式中，所述硅基材料包括硅单质、硅合金和硅氧化物中的至少一种。
在一些实施方式中，所述硅合金包括硅锡合金、硅锂合金和硅锗合金中的至少一种。
在一些实施方式中，所述硅氧化物为SiO x，0＜x≤2。
在一些实施方式中，所述硅基材料的形状包括颗粒状、球状、类球状、线状和管状中的至少一种。
在一些实施方式中，所述硅基材料的形状为球状或类球状。
在一些实施方式中，所述硅基材料的中值粒径为0.1μm～15μm；具体可以是0.1μm、0.2μm、0.3μm、0.5μm、1μm、2μm、3μm、4μm、5μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm或15μm等，当然也可以是上述范围内的其他值，在此不做限定。优选地，所述硅基材料的中值粒径为0.5μm～5μm。
在一些实施方式中，所述多孔硅碳复合层2的厚度为0.01μm～10μm；具体地，多孔硅碳复合层2的厚度可以是0.01μm、0.5μm、1μm、2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm等，当然也可以是上述范围内的其他值，在此不做限定。当多孔硅碳复合层2小于0.01μm，难以负载硅颗粒23，当多孔硅碳复合层2大于10μm， 多孔硅碳复合层2厚度增大，锂离子传输效率降低，降低负极材料的综合性能。优选地，多孔硅碳复合层2的厚度为0.5μm～5μm。可以理解地，本申请的多孔硅碳复合层2的厚度与碳基体21的厚度保持一致，碳基体21的厚度也为0.01μm～10μm。
在一些实施方式中，所述硅基材料的中值粒径与所述多孔硅碳复合层的厚度之比为(1～10)：1，厚度之比具体可以是1：1、2：1、3：1、4：1、5：1、6：1、7：1、8：1、9：1或10：1等，当然也可以是上述范围内的其他值，在此不做限定。优选地，硅基材料1的中值粒径与所述多孔硅碳复合层2的厚度之比为(1～3)：1，本申请通过控制多孔硅碳复合层2厚度与硅基材料1的中值粒径比例，可以对较大尺寸范围的硅基材料1起到很好的导电作用，并可有效的吸收硅基材料1的体积膨胀而不失去电接触。
在一些实施方式中，负极材料的孔隙率为10％～50％，具体地，负极材料孔隙率可以为10％、20％、30％、40％、50％等，当然也可以是上述范围内的其他值，在此不做限定。将负极材料的孔隙率控制在上述范围中，能够满足硅颗粒23和硅基材料的体积膨胀空间。优选地，负极材料的孔隙率为20％～40％，可以理解地，孔隙率指的是负极材料中孔洞体积在负极材料总体积中的占比。
在一些实施方式中，所述多孔硅碳复合层中碳基体的质量占比为5％～80％，具体可以是5％、10％、20％、30％、40％、50％、60％、70％和80％等，当然也可以是上述范围内的其他值，在此不做限定。可以理解，本申请的负极材料选择碳基体21作为硅颗粒23的载体，能够提高负极材料的容量而不破坏其结构。将碳基体21在多孔硅碳复合层2中的含量控制在上述范围内，可以很好的容纳硅颗粒23，同时多孔硅碳复合层2还能紧密牢靠的包裹硅基材料1，避免硅嵌锂后体积变化导致硅基材料与多孔硅碳复合层2脱离失去电接触。
在一些实施方式中，嵌设于所述实心部分中的硅颗粒和分散在所述孔洞中的硅颗粒的摩尔比为1：(0.5～3)；具体可以是1:0.5、1:0.8、1:1、1:1.5、1:1.8、1:2、1:2.5、1:2.8或1:3等，在此不做限定。通过控制两种位置的硅含量，可以满足高倍率和低膨胀硅碳产品的需求，并能达到高倍率与低膨胀的平衡。特别地，在上述限定范围内，当实心部分中的硅颗粒摩尔占比较多时，嵌设于所述实心部分中的硅颗粒被碳基体完全包裹，可以提高硅颗粒的导电性，提高复合材料的倍率性能，满足电池实现快充特性。当分散在所述孔洞中的硅颗粒摩尔占比较多时，孔洞中留有一定的空间用来缓解硅颗粒的体积膨胀，可以避免整个负极材料由于体积膨胀而破坏，同时减少电极膜的膨胀，提高电池的安全性。
在一些实施方式中，当多孔硅碳复合层压缩率达到50％时，多孔硅碳复合层的回弹率为90％以上，具体多孔硅碳复合层的回弹率可以是91％、93％、95％和98％等，将多孔硅碳复合层的回弹率控制为90％以上，避免因负极材料发生体积膨胀而导致材料粉化和与硅基材料失去电接触。
在一些实施方式中，所述碳基体21具有孔洞22，所述孔洞22包括大孔和介孔。
可以理解地，大孔为孔径大于50nm的孔，介孔为孔径为2nm～50nm之间的孔，大孔与介孔的孔体积比为(0.5～5):1；具体地，大孔和介孔的孔体积比为0.5：1、1：1、2：1、3：1、4：1和5：1等，当然也可以是上述范围内的其他值，在此不做限定。 本申请孔洞22具有丰富的大孔和介孔，硅基材料1的体积膨胀可以通过压缩孔洞22来缓解，孔洞22中的硅颗粒也有足够的空间缓解体积膨胀。此外，由于孔洞22的存在，硅颗粒23在脱嵌锂后的膨胀-收缩特性可以很好与硅基材料1的膨胀行为或收缩行为同步，始终保持与硅基材料1的良好电接触，保证优异的电子传送性能。
在一些实施方式中，硅颗粒的中值粒径为1nm～500nm，硅颗粒的中值粒径具体可以是1nm、5nm、10nm、20nm、30nm、40nm、50nm、60nm、70nm、80nm、90nm、100nm、110nm、120nm、130nm、140nm、150nm、160nm、170nm、180nm、190nm、200nm、400nm或500nm等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，将硅颗粒的中值粒径控制在上述范围内，其作用是避免硅颗粒嵌锂过程中由于体积膨胀使得材料粉化，从而导致结构破坏。优选地，硅颗粒的中值粒径为5nm～200nm。更优选地，硅颗粒的中值粒径为10nm～100nm。
在一些实施方式中，硅颗粒与所述硅基材料的质量比为(0.3～0.7)：1，具体可以为0.3：1、0.4：1、0.5：1、0.6：1、0.7：1等，当然也可以是上述范围内的其他值，在此不做限定。将硅颗粒与硅基材料的质量比控制在上述范围内，能够保证负极材料中硅元素的分布具有一定的浓度梯度，即硅在负极材料中的分布是由内到外浓度逐渐降低的，从而保证锂离子扩散具有均匀的浓度梯度，避免由于锂离子扩散时的浓度不均匀而带来电化学极化，最终导致电化学性能恶化的问题。
在一些实施方式中，负极材料还包括形成于多孔硅碳复合层2至少部分表面的包覆层3。可以理解地，包覆层3的设置，一方面可以避免电解液进入负极材料内部发生副反应导致首次效率和容量降低，另一方面包覆层3可以协同复合层2缓解硅基材料的体积膨胀，降低整个负极材料的体积膨胀，减小电极片溶胀。
在一些实施方式中，所述包覆层3包括碳材料、金属氧化物、氮化物和导电聚合物中的至少一种。
在一些实施方式中，所述碳材料包括石墨烯、软碳、硬碳和无定型碳中的至少一种。当包覆层为碳材料时，位于内侧的多孔硅碳复合层包括碳基体及硅颗粒，位于外侧的包覆层为碳材料，双层碳层可以增强负极材料的导电性，使得负极材料表现出高容量、长循环寿命、高倍率性能以及低膨胀等优点，可以广泛应用于高性能锂离子电池负极领域。
在一些实施方式中，所述金属氧化物包括氧化钛、氧化铝、氧化锂、氧化钴和氧化钒中的至少一种。
在一些实施方式中，所述氮化物包括氮化钛、氮化钒、氮化钴、氮化镍和氮化碳中的至少一种。
在一些实施方式中，所述包覆层包括导电聚合物，所述导电聚合物包括聚苯胺、聚乙炔、聚吡咯、聚噻吩，聚3-己基噻吩、聚对苯乙烯、聚吡啶和聚苯亚乙烯中的至少一种。
在一些实施方式中，包覆层的厚度为3nm～200nm，具体可以是3nm、5nm、10nm、50nm、100nm、150nm、200nm等，当然也可以是上述范围内的其他值，在此不做限定。优选地，包覆层的厚度为5nm～50nm，可以理解，包覆层能够减少硅与电解液接触，减少钝化膜生成，增加负极材料的导电性，抑制负极材料的体积膨胀，提升电池的可逆 电容量及循环性能。
在一些实施方式中，包覆层的孔隙率为2％～10％，具体可以是2％、3％、4％、5％、6％、7％、8％、9％和10％等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，包覆层的孔隙率小于多孔硅碳复合层的孔隙率(10％～50％)，相对于多孔硅碳复合层而言，包覆层为致密层，一定厚度的包覆层可以有效隔绝电解液的侵入。优选地，包覆层的孔隙率为5％～10％。此外，包覆层中孔体积在整个负极材料孔体积中占比小于50％，有利于包覆层隔绝电解液，减小电极片溶胀。
在一些实施方式中，负极材料的中值粒径为0.1μm～20μm，负极材料的中值粒径具体可以是0.1μm、1μm、2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm、20μm等，当然也可以是上述范围内的其他值，在此不做限定。优选地，负极材料的中值粒径为0.1μm～10μm，更优选地，负极材料的中值粒径为1μm～5μm，可以理解，将负极材料的平均粒径控制在上述范围内，有利于负极材料循环性能的提升。
在一些实施方式中，负极材料的比表面积为1.0m 2/g～50m 2/g，负极材料的比表面积具体可以是1.0m 2/g、1.5m 2/g、10m 2/g、20m 2/g、30m 2/g、40m 2/g、50m 2/g等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，将负极材料的比表面积控制在上述范围内，能够抑制负极材料的体积膨胀，有利于负极材料循环性能的提升。
在一些实施方式中，负极材料的粉体振实密度为1.0g/cm 3～1.8g/cm 3，负极材料的粉体振实密度具体地可以是1.0g/cm 3、1.2g/cm 3、1.3g/cm 3、1.4g/cm 3、1.5g/cm 3、1.6g/cm 3、1.7g/cm 3、1.1g/cm 3和1.8g/cm 3等，当然也可以是其他数值，优选地，负极材料的粉体振实密度为1.3g/cm 3～1.6g/cm 3。
在一些实施方式中，负极材料中的氧含量小于20％，可以理解地，负极材料中的氧含量太高，会降低负极材料的首次效率。
第二方面，本申请实施例提供一种负极材料的制备方法，如图3和图4所示，依次为本申请负极材料制备的结构流程图和制备流程图，方法包括以下步骤：
步骤S110，制备复合物，所述复合物包括硅基材料和形成于所述硅基材料的至少部分表面的A xSi合金，A为活波金属，X＝1～3；
步骤S120，将所述复合物与碳源混合后进行热反应，使得至少部分所述A xSi合金转化为金属A的氧化物，去除所述金属A的氧化物，得到硅碳复合材料。
在上述技术方案中，本申请提供的负极材料的制备方法，通过将硅基材料与活泼金属A合金化反应，在硅基材料的表面形成一层硅合金A xSi，即得到A xSi包裹硅基材料的复合物，利用复合物中硅合金A xSi中金属成分高温下具有较强的还原性，复合物与碳源发生热反应，可以使碳源中的官能团或者化学键断裂重组形成碳材料，而硅合金A xSi中硅元素会以硅颗粒的形式原位地嵌入在碳材料中，去除金属A的氧化物后，可在硅基材料表面形成蓬松且具有孔洞的碳基体材料，硅颗粒分散在碳基体内，蓬松的碳基体的孔洞可以有效缓解硅基材料的体积膨胀，并充当弹性导电体，可提供更多的离子和电子传输路径，增强硅内核与外界导电性，提高倍率性能。本申请的制备方法具有简单易行，可以有效解决硅负极体积膨胀大，导电性差的难题，从而提升 负极材料作为电池的电化学性能。
以下结合实施例具体介绍本申请的制备方法：
步骤S110，制备复合物，所述复合物包括硅基材料和形成于所述硅基材料的至少部分表面的A xSi合金，A为活波金属，X＝1～3。
在一些实施方式中，步骤S110，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应。可以理解地，合金化反应后，硅基材料的表面部分与活泼金属A反应会形成一层硅合金A xSi，位于内部的硅基材料未发生反应，从而得到A xSi包裹硅基材料的复合物。
在一些实施方式中，所述硅基材料与所述活泼金属A的摩尔比为1:(0.1～3)；具体地，基硅材料与活泼金属A的摩尔比可以是1：0.1、1：0.5、1：1、1：1.5、1：2、1：2.5、1：3等，当然也可以是上述范围内的其它值，在此不做限定。本申请通过控制硅基材料与或活泼金属的摩尔比从而控制硅合金A xSi的厚度。
在一些实施方式中，所述硅基材料包括硅单质、硅合金、硅氧化物中的至少一种。
在一些实施方式中，所述硅合金选自硅锡合金、硅锂合金、硅锗合金中的至少一种；
在一些实施方式中，所述硅氧化物为SiO x，0＜x≤2；具体可以是SiO 0.1、SiO 0.2、SiO 0.5、SiO 0.8、SiO 1.2、SiO 1.5、SiO 1.8、SiO 1.9或SiO 2.0等，硅氧化物与活泼金属A反应可以生成硅合金A xSi以及活泼金属氧化物。
在一些实施方式中，所述硅基材料的形状包括颗粒状、球状、类球状、线状和管状中的至少一种。本申请的硅材料可以采用多种形貌的硅材料，工艺简单，普适性强。
在一些实施方式中，所述硅基材料的形状为球状或类球状。
在一些实施方式中，所述硅基材料的中值粒径为0.1μm～15μm；具体可以是0.1μm、0.2μm、0.3μm、0.5μm、1μm、2μm、3μm、4μm、5μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm或15μm等，当然也可以是上述范围内的其他值，在此不做限定。优选地，所述硅基材料的中值粒径为0.5μm～5μm。
在一些实施方式中，活泼金属A包括Mg、Al、Ca和Zn中的至少一种。
在一些实施方式中，在将硅基材料与活波金属A进行合金化反应之前，可以将硅基材料与活波金属A混合，混合方式可以包括磁力搅拌、机械搅拌、超声分散和研磨分散中的任意一种。
在一些实施方式中，合金化反应的方式例如可以是真空烧结、热压烧结和常压烧结中的任意一种。
在一些实施方式中，合金化反应的温度为400℃～900℃，第一热处理温度具体可以是400℃、500℃、600℃、700℃、800℃、900℃等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，合金化反应的保温时间为1h～24h，例如可以是1h、3h、6h、10h、13、15h、18h、20h、24h等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，合金化反应的升温速率为1℃/min～10℃/min，例如可以是1℃/min、2℃/min、3℃/min、4℃/min、5℃/min、6℃/min、7℃/min、8℃/min、9℃/min、 10℃/min等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，形成于所述硅基材料的至少部分表面的A xSi合金的厚度为0.05μm～20μm，具体地可以为0.05μm、0.1μm、0.5μm、1μm、2μm、3μm、5μm、8μm、10μm、12μm、15μm、17μm、20μm等，当然也可以是上述范围内的其它值，在此不做限定。可以理解地，硅合金A xSi的厚度主要通过硅基材料与活泼金属A的摩尔比例决定。
在一些实施方式中，复合物的中值粒径为0.1μm～20μm，具体可以是0.1μm、0.5μm、1μm、5μm、10μm、15μm、20μm等，当然也可以是上述范围内的其它值，在此不做限定。优选为0.5μm～10μm，进一步优选为1μm～5μm。
在一些实施方式中，所述保护气氛包括氮气、氦气、氖气、氩气、氪气及氙气中的至少一种。
步骤S120，将所述复合物与碳源混合后进行热反应，使得至少部分所述A xSi合金转化为金属A的氧化物，去除所述金属A的氧化物，得到硅碳复合材料。
在一些实施方式中，碳源包括有机碳源，其中有机碳源为常温固态，沸点＜650℃的醛类，酚类及其对应的卤代化合物；例如有机碳源可以是多羟基醛、羟基苯甲醛、2-溴-5-羟基苯甲醛、2,6-二氯苯酚和对氯苯酚中的至少一种。
在一些实施方式中，碳源包括无机碳源，无机碳源为含碳无机盐，包括碳酸盐和碳酸氢盐，例如无机碳源可以是碳酸钙、碳酸钠、碳酸锌、碳酸钡、碳酸氢钠和碳酸氢钙中的至少一种。
在一些实施方式中，步骤S120在保护气氛下进行，所述保护气氛包括氮气、氦气、氖气、氩气、氪气及氙气中的至少一种。
在一些实施方式中，所述碳基体包括实心部分及分布于实心部分上的孔洞，部分硅颗粒分散在所述孔洞中，部分硅颗粒嵌设于所述实心部分中。
可以理解地，还原得到的硅颗粒一部分嵌入在碳基体的实心部分内，被碳完全包裹，可以提高硅颗粒的导电性，提高负极材料的倍率性能，满足电池实现快充特性的要求；硅颗粒另一部分嵌入碳基体的孔洞中，且硅颗粒并未完全填充满，可以留下足够的空间缓解硅颗粒的体积膨胀，可以避免整个材料由于体积膨胀而破坏，同时减少电极膜的膨胀，提高电池的安全性。
可以控制A xSi合金和碳源的比例来控制嵌设于所述实心部分中的硅颗粒和分散在所述孔洞中的硅颗粒的摩尔比。内部填充有硅颗粒的孔洞主要是酸洗金属A的氧化物留下的，当碳源足量时，可以保证金属A与碳源完全反应，此时，硅颗粒全部分散在孔洞中；当碳源不足，部分A xSi合金与碳源反应生成分散在孔洞中的纳米硅颗粒；其余的A xSi合金会在碳层中分解成A(蒸汽形态)和硅颗粒，这个硅颗粒嵌设于实心部分中。从而可以通过控制碳源的量来调节碳基体中两种不同位置硅颗粒的含量，可以满足高倍率和低膨胀型硅碳复合产品需求。
在一些实施方式中，所述碳基体为非晶多孔碳材料。
在一些实施方式中，所述去除热反应产物中的金属A的氧化物步骤，包括利用酸溶液将热反应产物进行酸洗。具体地，热反应产物包括碳、硅单质和活泼金属A的氧化物，活泼金属A的氧化物可以通过酸溶液处理方式去除。
在一些实施方式中，将热反应产物在浓度为1mol/L～5mol/L的酸溶液中处理1h～10h即可。
在一些实施方式中，酸溶液包括盐酸、硝酸及硫酸中的至少一种。
在一些实施方式中，酸溶液的浓度具体可以是1mol/L、2mol/L、3mol/L、4mol/L、5mol/L等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，酸溶液处理时间具体可以是1h、2h、3h、4h、5h、6h、7h、8h、9h、10h等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，复合物与碳源的摩尔比为1：(0.01～10)，具体可以是1：0.01、1：0.1、1：1、1：2、1：3、1：4、1：5、1：6、1：7、1：8、1：9、1：10等，当然也可以是上述范围内的其它值，在此不做限定。可以理解地，本申请通过控制复合材料M与碳源的摩尔比，即通过控制硅合金A xSi和碳源的摩尔比来改变碳基体中孔的大小和孔隙率，具体地，硅合金A xSi中金属A与碳源中氧反应生成金属氧化物，碳源在热反应过程中碳化成碳基体，金属氧化物被酸洗掉之后在碳基体中留下孔洞，形成具有孔洞的碳基体，硅合金A xSi中硅的含量越高，金属含量越小，孔的孔径就越小；硅合金A xSi中硅的含量越高，硅合金的厚度越大，其形成的碳基体的厚度就越大，可以对较大尺寸范围的硅颗粒起到很好的导电作用。
在一些实施方式中，混合方式可以包括磁力搅拌、机械搅拌、超声分散和研磨分散中的任意一种。
在一些实施方式中，热反应的温度200℃～950℃，具体可以是200℃、300℃、400℃、500℃、600℃、700℃、800℃、950℃等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，热反应的保温时间为1h～24h，例如保温时间可以是1h、3h、6h、10h、13、15h、18h、20h、24h等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，热反应的升温速率为1℃/min～20℃/min，例如可以是1℃/min、2℃/min、3℃/min、4℃/min、5℃/min、6℃/min、7℃/min、8℃/min、9℃/min、10℃/min、11℃/min、12℃/min、13℃/min、14℃/min、15℃/min、16℃/min、17℃/min、18℃/min、19℃/min、20℃/min等，当然也可以是上述范围内的其它值，在此不做限定。
此外，本申请的制备方法还包括：
步骤S130，在硅碳复合材料的表面形成包覆层，得到负极材料。
在上述技术方案中，对硅碳复合材料表面进行包覆处理，硅基材料的表面依次设有蓬松的包裹硅颗粒的碳基体和包覆层，包覆层的形成能够进一步解决硅负极体积膨胀大，导电性差的难题。
在一些实施方式中，形成包覆层的步骤也可以省略。
在一些实施方式中，步骤S130，包括将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层。
上述技术方案中，可以直接采用聚合物颗粒对负极材料进行包覆，从而实现负极材料表面包覆。聚合物包覆处理，一方面可以避免电解液进入负极材料内部发生副反应导致首效容量降低，另一方面可以协同非晶碳基体缓解硅的体积膨胀，降低整个复 合材料的体积膨胀，减小电极片溶胀。
在一些实施方式中，聚合物颗粒包括沥青、树脂、聚酯类聚合物和聚酰胺类聚合物中至少一种。
在一些实施方式中，聚合物颗粒与硅碳复合材料的质量比为1：(0.1～10)；聚合物颗粒与硅碳复合材料的质量比具体为1：0.1、1：1、1：2、1：3、1：4、1：5、1：6、1：7、1：8、1：9和1：10等，当然也可以是上述范围内的其它值，在此不做限定，将聚合物颗粒与硅碳复合材料的质量比控制在上述范围内，有利于提升首次效率。
在一些实施方式中，烧结的温度为600℃～1000℃，例如可以是600℃、700℃、800℃、900℃、1000℃等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，烧结的保温时间为1h～24h，例如可以是1h、3h、6h、10h、13、15h、18h、20h、24h等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，烧结的升温速率为1℃/min～20℃/min，例如可以是1℃/min、2℃/min、3℃/min、4℃/min、5℃/min、6℃/min、7℃/min、8℃/min、9℃/min、10℃/min、11℃/min、12℃/min、13℃/min、14℃/min、15℃/min、16℃/min、17℃/min、18℃/min、19℃/min、20℃/min等，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，真空条件下的真空度小于0.1Mpa，具体真空度可以是0.05Mpa、0.06Mpa、0.07Mpa、0.08Mpa和0.09Mpa，当然也可以是上述范围内的其它值，在此不做限定。
在一些实施方式中，步骤S130，包括利用化学合成方法在硅碳复合材料表面合成聚合物，形成包覆层。
在一些实施方式中，所述化学合成方法包括聚合反应，其中，参与聚合反应的单体包括多巴胺、单宁酸、酚醛树脂、葡萄糖、淀粉、三聚氰胺、氨酯、丙烯酸中的至少一种。
在一些实施方式中，包覆层包括聚合物，聚合物包括树脂类聚合物和聚酯类聚合物中至少一种，例如树脂类聚合物可以是环氧树脂、丙烯酸类树脂、聚酯树脂、氨基树脂和酚醛树脂中的任意一种，聚酯类高分子聚合物可以是聚氨酯、热固性聚酯、热塑性聚酯的任意一种。
在一些实施方式中，步骤S130，包括利用有机碳源的化学气相沉积在硅碳复合材料表面形成包覆层。
第三方面，本申请提供一种锂离子电池，锂离子电池包含上述负极材料。
下面分多个实施例对本申请实施例进行进一步的说明。其中，本申请实施例不限定于以下的具体实施例。在不变主权利的范围内，可以适当的进行变更实施。
实施例1
(1)将中值粒径为1μm的硅粉与镁粉按摩尔比为1:0.5混合均匀后放入氛围炉中，然后以3℃/min的升温速率加热到600℃后保温6h，使其充分合金化反应后得到硅镁合金层包裹硅颗粒的复合物。
(2)将1mol复合物与1mol的对氯苯酚混合均匀，将所得混合物放入充满氩气氛围的密封不锈钢反应釜中，将反应釜以3℃/min的升温速率加热到750℃后保温8h使其充分反应得到反应产物；将反应产物在1mol/L的盐酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到多孔硅碳层包裹硅材料的硅碳复合材料。
(3)将酚醛树脂与硅碳复合材料按质量比为1：5进行均匀混合后，放入真空反应炉中，真空度为0.05Mpa，然后将反应炉以3℃/min的升温速率加热到1000℃后保温6h使其充分反应，得到负极材料。
图5为本实施例1中负极材料的扫描电镜图片；从图5中的扫描电镜图片可以看出，制得负极材料表面包裹一层致密的碳包覆层。
图6为本实施例1中硅碳复合负极材料的拉曼图；图6的拉曼图谱进一步证明在1350cm -1和1580cm -1附近存在一个D峰和G峰，这是非晶碳的特征峰。
图7为本实施例1中硅碳复合负极材料的XRD图，从图7的XRD图谱中可以看出在28.4°、47.3°和56.1°的三强峰与硅(JCPDS No.27-1402)的三强峰相对应，基本无杂相。
图8本实施例1中硅碳复合负极材料的循环性能曲线，充放电电流为1000mA/g。图8中可以看出材料具有优异的循环性能，在1000mA/g大电流下循环820周还有725mAh/g的容量。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为碳包覆层。
实施例2
(1)将中值粒径为3μm的硅粉与镁粉按摩尔比为1:0.1混合均匀后放入氛围炉中，然后以1℃/min的升温速率加热到650℃后保温6h，使其充分合金化反应后得到硅镁合金层包裹硅颗粒的复合物。
(2)将1mol复合物与5mol的碳酸钙混合均匀，将所得混合物放入充满氮气氛围的密封不锈钢反应釜中，将反应釜以7℃/min的升温速率加热到800℃后保温1h使其充分反应得到反应产物；将反应产物在1mol/L的硫酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到硅碳复合材料。
(3)将聚酰胺与硅碳复合材料N按质量比为1：10进行均匀混合后，放入真空反应炉中，真空度为0.01Mpa，然后将反应炉以3℃/min的升温速率加热到1000℃后保温6h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为碳包覆层。
实施例3
(1)将中值粒径为8μm的硅粉与镁粉按摩尔比为1:1.5混合均匀后放入氮气氛围炉中，然后以5℃/min的升温速率加热到750℃后保温2h，使其充分合金化反应后得 到硅镁合金层包裹硅颗粒的复合物。
(2)将1mol复合物与0.1mol的碳酸钙混合均匀，将所得混合物放入充满氪气氛围的密封不锈钢反应釜中，将反应釜以5℃/min的升温速率加热到500℃后保温6h使其充分反应得到反应产物；将反应产物在1mol/L的盐酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到多孔碳包裹硅材料的硅碳复合材料。
(3)将沥青与硅碳复合材料按质量比为2：5进行均匀混合后，放入真空反应炉中，真空度为0.01Mpa，然后将反应炉以15℃/min的升温速率加热到900℃后保温1h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为非晶碳包覆层。
实施例4
(1)将中值粒径为15μm的硅粉与锌粉按摩尔比为1:3混合均匀后放入氖气氛围炉中，然后以20℃/min的升温速率加热到500℃后保温24h，使其充分合金化反应后得到硅镁合金层包裹硅颗粒的复合物。
(2)将1mol复合物与10mol的碳酸钠混合均匀，将所得混合物放入充满氖气氛围的密封不锈钢反应釜中，将反应釜以5℃/min的升温速率加热到900℃后保温15h使其充分反应得到反应产物；将反应产物在1mol/L的硝酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到多孔碳包裹硅材料的硅碳复合材料。
(3)将酚醛树脂与硅碳复合材料按质量比为1：0.1进行均匀混合后，放入真空反应炉中，真空度为0.01Mpa，然后将反应炉以20℃/min的升温速率加热到950℃后保温6h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为非晶碳包覆层。
实施例5
(1)将中值粒径为0.2μm的硅粉与镁粉按摩尔比为1:2混合均匀后放入氮气氛围炉中，然后以10℃/min的升温速率加热到900℃后保温1h，使其充分合金化反应后得到硅镁合金层包裹硅颗粒的复合物。
(2)将1mol复合物与0.01mol的羟基苯甲醛混合均匀，将所得混合物放入充满氩气氛围的密封不锈钢反应釜中，将反应釜以15℃/min的升温速率加热到750℃后保温8h使其充分反应得到反应产物；将反应产物在1mol/L的盐酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到多孔硅碳层包裹硅材料的硅碳复合材料。
(3)将酚醛树脂与硅碳复合材料与按质量比为1：8进行均匀混合后，放入真空反应炉中，真空度为0.05Mpa，然后将反应炉以20℃/min的升温速率加热到1000℃后保温10h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为非晶碳包覆层。
实施例6
(1)将中值粒径为5μm的硅粉与铝粉按摩尔比为1:0.1混合均匀后放入氩气氛围炉中，然后以5℃/min的升温速率加热到900℃后保温1h，使其充分合金化反应后得到硅铝合金层包裹硅颗粒的复合物。
(2)将1mol复合物与5mol的羟基苯甲醛混合均匀，将所得混合物放入充满氦气氛围的密封不锈钢反应釜中，将反应釜以10℃/min的升温速率加热到950℃后保温10h使其充分反应得到反应产物；将反应产物在1mol/L的硝酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到碳基体包裹硅基材料的硅碳复合材料。
(3)将1kg硅碳复合材料分散在10L去离子水中，加入200ml氨水溶液搅拌均匀，然后加入1kg间苯二酚和100ml甲醛溶液，在室温下搅拌8h后离心干燥，将干燥后产物在反应炉中以3℃/min的升温速率加热到950℃后保温6h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为酚醛树脂包覆层。
实施例7
与实施例1不同的是，不进行步骤(3)。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞。
实施例8
与实施例1不同的是，将步骤(3)中酚醛树脂替换为氧化钛。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为氧化钛包覆层。
实施例9
与实施例1不同的是，将步骤(3)中酚醛树脂替换为氮化钛。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅单质，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为氮化钛包覆层。
实施例10
(1)将中值粒径为1μm的硅锗合金粉与镁粉按摩尔比为1:0.4混合均匀后放入氛围炉中，然后以3℃/min的升温速率加热到600℃后保温6h，使其充分合金化反应后得到硅镁合金层包裹硅锗合金颗粒的复合物。
(2)将1mol复合物与1mol的对氯苯酚混合均匀，将所得混合物放入充满氩气氛围的密封不锈钢反应釜中，将反应釜以3℃/min的升温速率加热到750℃后保温8h使其充分反应得到反应产物；将反应产物在1mol/L的盐酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到多孔硅碳层包裹硅材料的硅碳复合材料。
(3)将酚醛树脂与硅碳复合材料按质量比为1：5进行均匀混合后，放入真空反应炉中，真空度为0.05Mpa，然后将反应炉以3℃/min的升温速率加热到1000℃后保温6h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅锗合金，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为非晶碳包覆层。
实施例11
(1)将中值粒径为3μm的硅氧化物(SiO)粉与镁粉按摩尔比为1:0.8混合均匀后放入氛围炉中，然后以1℃/min的升温速率加热到650℃后保温6h，使其充分合金化反应后得到硅镁合金层包裹硅氧化物颗粒的复合物。
(2)将1mol复合物与5mol的碳酸钙混合均匀，将所得混合物放入充满氮气氛围的密封不锈钢反应釜中，将反应釜以7℃/min的升温速率加热到800℃后保温1h使其充分反应得到反应产物；将反应产物在1mol/L的硫酸溶液机械搅拌处理2h后，抽滤、洗涤、干燥后得到硅碳复合材料。
(3)将聚酰胺与硅碳复合材料N按质量比为1：10进行均匀混合后，放入真空反应炉中，真空度为0.01Mpa，然后将反应炉以3℃/min的升温速率加热到1000℃后保温6h使其充分反应，得到负极材料。
本实施例制得负极材料为核壳结构，负极材料包括内核、分布于所述内核表面的多孔硅碳复合层，所述内核包括硅氧化物，多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，碳基体具有孔洞，包覆层为碳包覆层。
对比例1
与实施例1不同的是，直接在硅内核的表面制备碳包覆层，具体制备步骤如下：
将硅材料与酚醛树脂按质量比为5:1进行均匀混合后，放入真空反应炉中，真空度为0.05Mpa，然后将反应炉以3℃/min的升温速率加热到900℃后保温6h使其充分反应，得到负极材料。
性能测试
1.硅颗粒在负极材料中的质量占比：采用聚焦离子束(FIB)对负极材料的表面进行一层层的剥离，结合扫描电子显微镜(SEM)和能谱仪(EDS)对每个断面的复合层中的硅元素含量进行测量，统计每个断面硅颗粒含量可以得到复合层中硅颗粒总质量，硅颗粒总质量/负极材料质量即为硅颗粒在负极材料中的质量占比；
2.硅基材料内核在负极材料中的质量占比：通过聚焦离子束(FIB)对复合负极材料颗粒进行一层一层的剥离，结合扫描电子显微镜(SEM)和能谱仪(EDS)对每个断面的硅基材料内核元素含量(单质硅内核测量硅元素含量，硅合金内核测量硅和金属元素含量，硅氧化物内核测量硅和氧元素含量)进行测量，统计每个断面硅基材料内核元素总含量，可以得到硅基材料内核在负极材料中的质量占比；
3.碳材料在负极材料中的质量占比：通过TG/DSC测试，测试碳材料的热重曲线，根据放热峰位置，结合TG曲线，得到碳材料的含量占比；
4.大孔和介孔的孔体积比：通过BET-BJH测试方式得到大孔与介孔的孔体积比。
5.负极材料的孔隙率：通过压汞测试仪对负极材料的孔隙率进行测试；
6.负极材料的粉体振实密度：通过粉体振实密度测试仪直接测试得出；
7.硅颗粒与硅基材料的质量比：硅颗粒含量通过测试方法1得出，硅基材料含量通过测试方法2获得；
8.硅颗粒的中值粒径：通过聚焦离子束(FIB)对10个负极材料颗粒进行一层一层断面剥离，结合扫描电子显微镜(SEM)和能谱仪(EDS)对每个断面的硅颗粒尺寸测量，统计所测硅颗粒的尺寸，不规则硅颗粒的尺寸按照切面的最大长度和最大宽度的平均值来计算，累计粒度分布百分数达到50％时所对应的粒径即为中值粒径；
9.硅基材料的中值粒径：通过聚焦离子束(FIB)对10个复合负极材料颗粒进行一层一层断面剥离，结合扫描电子显微镜(SEM)和能谱仪(EDS)对每个断面的硅基材料寸测量，不规则硅基材料的尺寸按照切面的最大长度和最大宽度的平均值来计算，统计所测硅基材料的尺寸，累计粒度分布百分数达到50％时所对应的粒径即为中值粒径；
10.多孔硅碳复合层的厚度：扫描电镜表征在透射电子显微镜上进行，操作电压为200kV，对多孔硅碳复合层的厚度进行标尺；
11.多孔硅碳复合层中，分散在实心部分中的硅颗粒和分散在孔洞中的硅颗粒的摩尔比：通过聚焦离子束(FIB)对负极材料颗粒进行一层一层断面剥离，结合扫描电子显微镜(SEM)和能谱仪(EDS)对实心部分中的硅颗粒和分散在孔洞中的硅颗进行元素含量分析，统计两种位置硅颗粒的含量比，即为摩尔比；
12.负极材料的中值粒径：采用激光粒度仪马尔文MS3000，对负极材料进行测试，统计累计粒度分布体积百分数达到50％时所对应的粒径即为中值粒径；
13.负极材料的比表面积：采用美国麦克TriStar3020比表面测试仪进行测试得出；
14.负极材料的氧含量：采用德国弗尔德ONH 2000氧氮氢元素分析仪进行测试；
15.采用以下方法测试回弹率：通过原位透射电子显微镜(Transmission Electron Microscope,简称TEM)和电化学测试系统相结合测试回弹率。通过原位透射电子显微镜对多孔硅碳复合层的压缩和回弹后的厚度测量得到回弹率。通过对负极材料施加电压后，硅基材料内核膨胀挤压多孔硅碳复合层，压缩后的厚度为He；施加反向电压后硅 基材料内核收缩多孔硅碳复合层开始回弹，此时回弹的厚度为Hd，Hi为多孔硅碳复合层原始厚度。压缩性＝(Hi-He)/Hi*100％，回弹性＝Hd/(Hi-He)*100％；
16.采用以下方法测试电化学循环性能：将实施例1～11及对比例1制备的负极材料、导电剂和粘结剂按质量百分比94：1：5将他们溶解在溶剂中混合，控制固含量在50％，涂覆于铜箔集流体上，真空烘干、制得负极极片；然后将传统成熟工艺制备的三元正极极片、1mol/L的LiPF 6/乙基纤维素+碳酸二甲酯+碳酸甲乙酯(v/v＝1:1:1)电解液、聚丙烯隔膜(Celgard2400)、外壳采用常规生产工艺装配18650圆柱单体电池。圆柱电池的充放电测试在武汉金诺电子有限公司LAND电池测试系统上，在常温条件，0.2C恒流充放电，充放电电压限制在2.75～4.2V，得到首次可逆容量、首圈充电容量和首圈放电容量。首次库伦效率＝首圈放电容量/首圈充电容量。
重复循环50周，利用千分尺测量锂离子电池此时极片的厚度为H1，电池极片初始厚度为H0，循环50圈后膨胀率＝(H1-H0)/H0×100％。
重复100周循环，记录放电容量，作为锂离子电池的剩余容量；容量保持率＝剩余容量/初始容量*100％。
上述性能测试的结果如表1所示：将实施例1～11及对比例1所制备的负极材料应用于锂离子电池中，编号分别为S1、S2、S3、S4、S5、S6、S7、S8和S9；对比例1编号为Ref-1。
表1.实施例1～11及对比例1制备的负极材料的性能参数
Figure PCTCN2022117555-appb-000001
Figure PCTCN2022117555-appb-000002
由表1可知：实施例1至实施例5制备的负极材料，包括由硅基材料内核、多孔硅碳复合层和包覆层构成的核壳结构负极材料，多孔硅碳复合层的孔洞可以有 效缓解硅内核和硅颗粒的体积膨胀，并充当弹性导电体，可提供更多的离子和电子传输路径，增强硅内核与外界导电性，提高倍率性能。包覆层的设置一方面可以避免电解液进入内部发生副反应导致首效容量降低，另一方面可以协同多孔硅碳复合层缓解硅的体积膨胀，降低整个复合材料的体积膨胀，减小电极片溶胀，本发明制备的复合材料具有高容量、高倍率性能以及低膨胀等优点，可以广泛应用于高性能锂离子电池负极领域。
实施例6采用化学合成方法将高分子聚合物包覆在负极材料表面得到包覆层，其制备的负极材料也能表现出低体积膨胀、高容量的特点。
实施例7的负极材料在制备过程中，未制备包覆层，无法降低硅与电解液的接触，容纳体积膨胀有限，导致电极膜膨胀率较大，负极材料的放电比容量较低。
实施例8和实施例9分别在硅碳复合材料N的表面制备金属氧化物层和氮化物层，得到的负极材料也能表现出优异的电化学性能。
实施例10和实施例11分别采用硅锗合金作为内核材料，得到负极材料能够表现出低体积膨胀、高容量的特点。
实施例11采用硅氧化物(SiO)作为内核材料，得到的负极材料也能表现出优秀的体积膨胀抑制性能，容量保持率也能够维持在较高的水平。
对比例1的负极材料在制备过程中，未制备多孔硅碳复合层，硅嵌锂后体积膨胀较大，导致材料粉化，负极材料容量较低、电极膜膨胀率较大。
申请人声明，本申请通过上述实施例来说明本申请的详细工艺设备和工艺流程，但本申请并不局限于上述详细工艺设备和工艺流程，即不意味着本申请必须依赖上述详细工艺设备和工艺流程才能实施。所属技术领域的技术人员应该明了，对本申请的任何改进，对本申请产品各原料的等效替换及辅助成分的添加、具体方式的选择等，均落在本申请的保护范围和公开范围之内。

Claims (13)

  1. 一种负极材料，其特征在于，所述负极材料包括内核及分布于所述内核的至少部分表面的多孔硅碳复合层，所述内核包括硅基材料，所述多孔硅碳复合层包括碳基体及分散在所述碳基体中的硅颗粒，所述碳基体具有孔洞。
  2. 根据权利要求1所述的负极材料，其特征在于，至少部分的硅颗粒分散在所述碳基体的孔洞中。
  3. 根据权利要求1或2所述的负极材料，其特征在于，所述负极材料包括如下特征(1)至(20)中的至少一种：
    (1)所述内核为硅基材料；
    (2)所述硅基材料包括硅单质、硅合金、硅氧化物中的至少一种；
    (3)所述硅基材料包括硅合金，所述硅合金选自硅锡合金、硅锂合金、硅锗合金中的至少一种；
    (4)所述硅基材料包括硅氧化物，所述硅氧化物为SiO x，0＜x≤2；
    (5)所述硅基材料的形状包括颗粒状、球状、类球状、线状和管状中的至少一种；
    (6)所述硅基材料的中值粒径为0.1μm～15μm；
    (7)所述硅基材料的中值粒径为1μm～5μm；
    (8)所述多孔硅碳复合层的厚度为0.01μm～10μm；
    (9)所述硅基材料的中值粒径与所述多孔硅碳复合层的厚度之比为(1～10)：1；
    (10)所述负极材料的孔隙率为10％～50％；
    (11)所述多孔硅碳复合层中碳基体的质量占比为5％～80％；
    (12)所述孔洞包括大孔和介孔；
    (13)所述孔洞包括大孔和介孔，所述大孔与所述介孔的孔体积比为(0.5～5):1；
    (14)所述硅颗粒的中值粒径为1nm～500nm；
    (15)所述硅颗粒的中值粒径为10nm～100nm；
    (16)所述硅颗粒与所述硅基材料的质量比为(0.3～0.7)：1；
    (17)所述碳基体包括实心部分及分布于实心部分上的孔洞，至少部分硅颗粒嵌设于所述实心部分中；
    (18)所述碳基体包括实心部分及分布于实心部分上的孔洞，部分硅颗粒分散在所述孔洞中，部分硅颗粒嵌设于所述实心部分中；
    (19)所述碳基体包括实心部分及分布于实心部分上的孔洞，部分硅颗粒分散在所述孔洞中，部分硅颗粒嵌设于所述实心部分中；嵌设于所述实心部分中的硅颗粒和分散在所述孔洞中的硅颗粒的摩尔比为1：(0.5～3)；
    (20)当所述多孔硅碳复合层压缩率达到50％时，所述多孔硅碳复合层的回弹率为90％以上。
  4. 根据权利要求1所述的负极材料，其特征在于，还包括形成于所述多孔硅碳复合层至少部分表面的包覆层。
  5. 根据权利要求4所述的负极材料，其特征在于，所述包覆层包括如下特征(1)至(7)中的至少一种：
    (1)所述包覆层包括碳材料、金属氧化物、氮化物和导电聚合物中的至少一种；
    (2)所述包覆层包括碳材料，所述碳材料包括石墨烯、软碳、硬碳和无定型碳中的至少一种；
    (3)所述包覆层包括金属氧化物，所述金属氧化物包括氧化钛、氧化铝、氧化锂、氧化钴和氧化钒中的至少一种；
    (4)所述包覆层包括氮化物，所述氮化物包括氮化钛、氮化钒、氮化钴、氮化镍和氮化碳中的至少一种；
    (5)所述包覆层包括导电聚合物，所述导电聚合物包括聚苯胺、聚乙炔、聚吡咯、聚噻吩，聚3-己基噻吩、聚对苯乙烯、聚吡啶和聚苯亚乙烯中的至少一种；
    (6)所述包覆层的厚度为3nm～200nm；
    (7)所述包覆层的孔隙率为2％～10％。
  6. 根据权利要求1～5任一项所述的负极材料，其特征在于，所述负极材料包括以下特征(1)至(4)中的至少一种：
    (1)所述负极材料的中值粒径为0.1μm～20μm；
    (2)所述负极材料的比表面积为1.0m 2/g～50m 2/g；
    (3)所述负极材料的粉体振实密度为0.2g/cm 3～1.2g/cm 3；
    (4)所述负极材料中的氧含量小于20％。
  7. 一种负极材料的制备方法，其特征在于，包括以下步骤：
    制备复合物，所述复合物包括硅基材料和形成于所述硅基材料的至少部分表面的A xSi合金，A为活波金属，X＝1～3；
    将所述复合物与碳源混合后进行热反应，使得至少部分所述A xSi合金转化为金属A的氧化物，去除所述金属A的氧化物，得到硅碳复合材料。
  8. 根据权利要求7所述的方法，其特征在于，所述方法还包括以下特征(1)至(26)中的至少一种：
    (1)所述硅基材料包括硅单质、硅合金、硅氧化物中的至少一种；
    (2)所述硅基材料包括硅合金，所述硅合金选自硅锡合金、硅锂合金、硅锗合金中的至少一种；
    (3)所述硅基材料包括硅氧化物，所述硅氧化物为SiO x，0＜x≤2；
    (4)所述硅基材料的形状包括颗粒状、球状、类球状、线状和管状中的至少一种；
    (5)所述硅基材料的形状为球状或类球状；
    (6)所述硅基材料的中值粒径为0.1μm～15μm；
    (7)所述硅基材料的中值粒径为1μm～5μm；
    (8)所述活泼金属A包括Mg、Al、Ca和Zn中的至少一种；
    (9)所述硅基材料与所述活泼金属A的摩尔比为1:(0.1～3)；
    (10)所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应；
    (11)所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应，其中，所述合金化反应的温度为400℃～900℃，保温时间为1h～24h；
    (12)所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应，其中，所述合金化反应的升温速率为1℃/min～10℃/min；
    (13)所述制备复合物的步骤，包括：在保护气氛下将硅基材料与活波金属A进行合金化反应，其中，所述保护气氛包括氮气、氦气、氖气、氩气、氪气及氙气中的至少一种；
    (14)所述形成于所述硅基材料的至少部分表面的A xSi合金的厚度为0.05μm～20μm；
    (15)所述复合物的中值粒径为0.1μm～20μm；
    (16)所述碳源包括有机碳源；
    (17)所述碳源包括有机碳源，所述有机碳源包括常温条件下为固态、沸点＜650℃的醛类，酚类及其对应的卤代化合物；
    (18)所述碳源包括无机碳源；
    (19)所述碳源包括无机碳源，所述无机碳源包括含碳无机盐；
    (20)所述将所述复合物与碳源混合后进行热反应的步骤在保护气氛下进行，所述保护气氛包括氮气、氦气、氖气、氩气、氪气及氙气中的至少一种；
    (21)所述去除热反应产物中的活波金属A的步骤，包括利用酸溶液将热反应产物进行酸洗；
    (22)所述去除热反应产物中的活波金属A的步骤，包括利用酸溶液将热反应产物进行酸洗，所述酸溶液包括盐酸、硝酸和硫酸中的至少一种；
    (23)所述复合物与所述碳源的摩尔比为1：(0.01～10)；
    (24)所述热反应的温度为200℃～950℃；
    (25)所述热反应的保温时间为1h～24h；
    (26)所述热反应的升温速率为1℃/min～20℃/min。
  9. 根据权利要求7或8所述的方法，其特征在于，所述方法还包括在硅碳复合材料的表面形成包覆层，得到负极材料。
  10. 根据权利要求9所述的方法，其特征在于，所述方法还包括以下特征(1)至(7)中的至少一种：
    (1)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；
    (2)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；所述聚合物颗粒包括沥青、树脂、聚酯类聚合物和聚酰胺类聚合物中的至少一种；
    (3)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；所述聚合物颗粒与所述硅碳复合材料的质量比为1：(0.1～10)；
    (4)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；所述烧结的温度为600℃～1000℃；
    (5)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；所述烧结的保温时间为1h～24h；
    (6)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；所述烧结的升温速率为1℃/min～20℃/min；
    (7)所述在硅碳复合材料的表面形成包覆层的步骤，包括：将包含硅碳复合材料与聚合物颗粒的混合物置于真空条件下进行烧结，形成包覆层；所述真空条件下的真空度小于0.1Mpa。
  11. 根据权利要求9所述的方法，其特征在于，所述方法还包括以下特征(1)至(2)中的至少一种：
    (1)所述在硅碳复合材料的表面形成包覆层的步骤，包括：利用化学合成方法在硅碳复合材料表面合成聚合物，形成包覆层；
    (2)所述在硅碳复合材料的表面形成包覆层的步骤，包括：利用化学合成方法在硅碳复合材料表面合成聚合物，形成包覆层，所述聚合物包括树脂类聚合物和聚酯类聚合物中的至少一种。
  12. 根据权利要求9所述的方法，其特征在于，所述在硅碳复合材料的表面形成包覆层的步骤，包括：利用有机碳源的化学气相沉积在硅碳复合材料表面形成包覆层。
  13. 一种锂离子电池，其特征在于，包括权利要求1～6任一项所述的负极材料或权利要求7～12任一项所述的制备方法制备的负极材料。
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