A negative electrode material, a preparation method and application thereof

Abstract

The application provides a negative electrode material and a preparation method and application thereof. The preparation method comprises the following steps: mixing metal lithium and an organic solvent in an inert atmosphere to obtain a mixed solution; then, the mixed solution is in a form of spraying and is subjected to one-time temperature fluidization with a silicon-oxygen material, and then is subjected to two-time temperature fluidization and three-time temperature fluidization in sequence, and carbon coating is simultaneously performed in the three-time temperature fluidization process, wherein the whole process of fluidization is performed in an inert atmosphere to obtain the negative electrode material. The lithium organic solution is in a form of spraying and is subjected to fluidization with the silicon-oxygen material, so that uniform doping of lithium metal in the silicon-oxygen material is realized, the doping efficiency of the lithium metal is improved, and double-layer carbon coating of the silicon-oxygen material is realized at the same time, so that the initial efficiency, capacity and cycle life of the negative electrode material are improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and relates to a negative electrode material, its preparation method, and its application. Background Technology

[0002] Silicon-based anode materials, with their ultra-high specific capacity, are among the most promising anode materials for future development. However, pure silicon materials exhibit significant volume expansion, while silicon-oxygen materials, due to their unique structural characteristics, can mitigate this volume expansion problem to some extent. The main structure of silicon-oxygen materials consists of silicon nanocrystals dispersed in silicon dioxide. During the initial charge-discharge cycle, silicon dioxide consumes lithium salts, leading to a decrease in the material's initial efficiency. Therefore, improving the initial efficiency of silicon-oxygen materials is crucial. Pre-doping with lithium can achieve a pre-reaction between lithium and silicon dioxide during the initial treatment process, forming lithium silicate salts. This reduces the irreversible lithium salt consumption during the initial discharge cycle.

[0003] CN104993098A discloses a lithium-replenishing negative electrode sheet and its preparation method, a lithium-ion supercapacitor, and a lithium-ion battery, belonging to the field of energy storage device technology. A lithium-replenishing negative electrode sheet includes a negative electrode sheet composed of a negative electrode current collector and a negative electrode material coating coated on the surface of the current collector. The surface of the negative electrode material coating is coated with a lithium powder layer, which comprises uniformly mixed lithium powder and a binder, with a weight ratio of lithium powder to binder of 60-98:2-4. However, due to the high reactivity of lithium metal, the above-mentioned pre-lithiation methods all require a dry, oxygen-free environment, which is difficult to operate, and the degree and precision of pre-lithiation are difficult to control precisely.

[0004] CN101047234A discloses a silicon-silicon oxide-lithium composite material, comprising a silicon-silicon oxide composite material with a structure in which silicon particles of size within 0.5-50 nm are dispersed within silicon oxide, and the silicon-silicon oxide composite material is doped with lithium. A method of solid-state sintering silicon oxide powder with a lithium source is used to achieve pre-expansion and pre-lithiation of the silicon oxide material. This method effectively addresses the defects of high expansion and low first-time efficiency of silicon oxide at the material scale; however, the lack of an internal buffer structure means that the material still faces interfacial instability and poor cycling performance during volume expansion and contraction.

[0005] Therefore, how to provide an efficient method for lithium doping in silicon-oxygen anode materials to improve the electrochemical performance of the anode materials is an urgent technical problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an anode material, its preparation method, and its applications. This invention fluidizes a lithium organic solution with a silicon-oxygen material via spraying, achieving uniform doping of lithium metal in the silicon-oxygen material and improving the lithium metal doping efficiency. Simultaneously, fluidization also achieves a double-layer carbon coating on the silicon-oxygen material, enhancing the initial efficiency, capacity, and cycle life of the anode material.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a negative electrode material, the method comprising:

[0009] Lithium metal and an organic solvent are mixed under an inert atmosphere to obtain a mixed solution. The mixed solution is then sprayed onto a silicon oxide material and subjected to a first heating fluidization, followed by a second heating fluidization and a third heating fluidization. Carbon coating is carried out simultaneously during the three heating fluidization processes. The entire fluidization process is carried out under an inert atmosphere to obtain the negative electrode material.

[0010] This invention fluidizes an organic lithium solution with a silicon-oxygen material via spraying, achieving uniform doping of lithium metal in the silicon-oxygen material without requiring specific limits on the lithium metal particle size. This improves the doping efficiency of lithium metal and simultaneously achieves a double-layer carbon coating on the silicon-oxygen material, thereby enhancing the initial efficiency, capacity, and cycle life of the anode material.

[0011] In this invention, during the single-stage heating and fluidization process, the mixed solution is fluidized with the silicon-oxygen material in the form of a spray, so that the lithium metal solution can be uniformly coated on the surface of the silicon-oxygen particles. Unlike the embedding of conventional impregnation methods, the coated droplets and silicon-oxygen material in this invention are suspended and collide, resulting in efficient and uniform contact. During this process, the lithium metal dissolved in the organic solvent can be uniformly coated on the surface of the silicon-oxygen material, and the process is gentle, which is beneficial for lithium doping in the later stages.

[0012] During the secondary heating fluidization process, silicon-oxygen particles react with organic lithium materials to achieve lithium doping. In this process, because the reaction between organic lithium and silicon-oxygen is in a mild state, the growth of silicon grain size inside the silicon-oxygen particles can be effectively suppressed. Moreover, the reaction can be completed in a relatively short time, which greatly increases the efficiency compared with the general impregnation experiment and allows for precise control of the degree of organic lithium doping. In addition, during this process, some organic materials are gradually transformed into carbon layer materials to coat the surface of silicon-oxygen particles, forming a pre-coated carbon layer structure.

[0013] During the three-stage heating and fluidization process, the uniform coating of the carbon layer is further achieved. Due to the construction of the pre-coating layer structure in the early stage, the subsequent carbon coating structure can more effectively achieve carbon capture and carbon molecule arrangement on the material surface, forming a uniform carbon coating layer structure.

[0014] Through a three-stage heating and fluidization process, a high-efficiency silicon-oxygen anode material doped with lithium metal was obtained. This material combines the characteristics of high initial efficiency, high capacity, and long cycle life.

[0015] In this invention, if the mixed solution and the silicon-oxygen material are not fluidized in the form of a spray during the single-heating fluidization process, it will be detrimental to the uniform distribution of the lithium source on the surface of the silicon-oxygen material.

[0016] In this invention, both the mixing process and the fluidization process must be carried out under an inert atmosphere, such as a helium atmosphere, a neon atmosphere, an argon atmosphere, a krypton atmosphere, or a xenon atmosphere. If a non-inert atmosphere, such as a nitrogen atmosphere, is used, it will react with lithium, increasing the consumption of reactants.

[0017] Preferably, the organic solvent includes polycyclic aromatic compounds and ether organic compounds.

[0018] The polycyclic aromatic compounds referred to in this invention are compounds in which two or more benzene rings are connected in a fused ring form. This invention selects polycyclic aromatic compounds and ether organic compounds as organic solvents. During the single-stage heating and fluidization process, the low-boiling-point ether solvents can partially evaporate, ensuring that the organolithium formed by lithium and polycyclic aromatic compounds is more tightly bonded to the silicon-oxygen material.

[0019] Preferably, the mass ratio of the polycyclic aromatic compound to the ether organic compound is (1-10):100, for example.

[0020] Preferably, the polycyclic aromatic compounds include any one or a combination of at least two of biphenyl, naphthalene, terphenyl, anthracene, phenanthrene, tetraphenyl, pentaphenyl, pyrene, styrene, triphenylene or benzoxene and their derivatives.

[0021] The derivatives referred to in this invention are derivatives of any one of biphenyl, naphthalene, terphenyl, anthracene, phenanthrene, tetraphenyl, pentaphenyl, pyrene, styrene, triphenylene, or benzoxene.

[0022] Preferably, the ether organic compound includes any one or a combination of at least two of dimethyl ether, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, or tetraethylene glycol dimethyl ether, and more preferably any one or a combination of at least two of tetrahydrofuran, dioxane, or 1,2-dimethoxyethane.

[0023] In this invention, tetrahydrofuran, dioxane, or 1,2-dimethoxyethane are selected as ether-based organic compounds, which is more conducive to the preparation of organolithium metal solutions.

[0024] Preferably, the mixing process includes: stirring the polycyclic aromatic compound and the ether organic solvent once, and then adding lithium metal and stirring a second time.

[0025] Preferably, the stirring time for one stirring session is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0026] Preferably, the secondary stirring time is 3 to 15 hours, such as 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours.

[0027] Preferably, the mass concentration of the mixed solution is 1 to 200 g / L, such as 1 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L, or 200 g / L.

[0028] In this invention, if the mass concentration of the mixed solution is too high, it will increase the difficulty of the reaction.

[0029] Preferably, the temperature of the first heating fluidization is 30 to 100°C, such as 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C.

[0030] Preferably, the secondary heating and fluidization time is 0.5 to 2 hours, for example, 0.5 hours, 1 hour, 1.5 hours or 2 hours.

[0031] Preferably, the temperature of the secondary heating fluidization is 300-600℃, such as 300℃, 350℃, 400℃, 450℃, 500℃, 550℃ or 600℃.

[0032] In this invention, during the secondary heating and fluidization within the aforementioned temperature range, organic lithium and silicon-oxygen materials can react, thereby achieving lithium doping of the silicon-oxygen materials and preparing high-efficiency silicon-oxygen anode materials.

[0033] Preferably, the secondary heating and fluidization time is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0034] Preferably, the temperature of the three-stage heating fluidization is 700-1100℃, such as 700℃, 800℃, 900℃, 1000℃ or 1100℃.

[0035] Preferably, the time for the three heating and fluidization processes is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0036] Preferably, the carbon coating includes gaseous carbon coating.

[0037] This invention uses gas-phase carbon coating, which can achieve more uniform coating of silicon-oxygen materials. In contrast, liquid-phase carbon coating or other types of carbon coating methods are not conducive to building a uniform and thin carbon coating layer on the surface of silicon-oxygen materials.

[0038] Preferably, the carbon source for gas-phase carbon coating includes any one or a combination of at least two of methane, ethane, propane, ethylene, propylene, acetylene, toluene, or benzene.

[0039] As a preferred technical solution, the preparation method includes:

[0040] Under an inert atmosphere, polycyclic aromatic compounds and ether organic compounds are first stirred for 1-5 hours at a mass ratio of (1-10):100, and then lithium metal is added and stirred for 3-15 hours to obtain a mixed solution with a mass concentration of 1-200 g / L. The mixed solution is then sprayed with silicon oxide material and subjected to a first heating fluidization at 30-100°C for 0.5-2 hours, followed by a second heating fluidization at 300-600°C for 1-5 hours, and finally a third heating fluidization at 700-1100°C for 1-5 hours. During the three heating fluidization processes, gas-phase carbon coating is carried out simultaneously. The entire fluidization process is carried out under an inert atmosphere to obtain the negative electrode material.

[0041] In a second aspect, the present invention provides a negative electrode material, which is prepared by the method for preparing a negative electrode material as described in the first aspect; the negative electrode material includes a core and a double-layer carbon coating layer covering the surface of the core, wherein the core is a lithium metal-doped silicon-oxygen material.

[0042] Thirdly, the present invention also provides a lithium-ion battery, the lithium-ion battery comprising the negative electrode material as described in the second aspect.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] This invention achieves uniform doping of lithium metal in silicon-oxygen materials by spraying an organic solution of lithium into a segmented fluidization process. This improves the doping efficiency of lithium metal and simultaneously achieves a double-layer carbon coating on the silicon-oxygen materials, thereby enhancing the initial efficiency, capacity, and cycle life of the anode material. The battery provided by this invention can achieve a discharge specific capacity of over 1358 mAh / g at 0.1C, an initial efficiency of over 84.2%, and a capacity retention rate of over 87.8% after 100 cycles at 1C. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be construed as limiting the invention.

[0046] Example 1

[0047] This embodiment provides a negative electrode material, which includes a core and a double-layer carbon coating layer covering the surface of the core. The core is a lithium metal-doped silicon-oxygen material.

[0048] The preparation method of the negative electrode material is as follows:

[0049] (1) Under an argon atmosphere, biphenyl and tetrahydrofuran were stirred at a mass ratio of 5:100 for 3 hours, then lithium metal was added and stirring was continued for 10 hours to obtain a mixed solution with a mass concentration of 95 g / L.

[0050] (2) Add silicon oxide material to the fluidized bed equipment, heat to 50°C, use argon gas as carrier, and add the mixed solution in step (1) into the fluidized bed furnace area in the form of spray for 1 hour;

[0051] (3) Based on step (2), raise the temperature of the fluidized bed equipment to 500℃ and continue fluidization for 2.5h;

[0052] (4) Based on step (3), continue to heat to 980°C, introduce methane for gas phase carbon coating for 2 hours, and obtain the negative electrode material.

[0053] Example 2

[0054] This embodiment provides a negative electrode material, which includes a core and a double-layer carbon coating layer covering the surface of the core. The core is a lithium metal-doped silicon-oxygen material.

[0055] The preparation method of the negative electrode material is as follows:

[0056] (1) Under a neon atmosphere, pentanebenzene and 1,2-dimethoxyethane were stirred at a mass ratio of 10:100 for 5 h, then lithium metal was added and stirring was continued for 15 h to obtain a mixed solution with a mass concentration of 200 g / L.

[0057] (2) Add silicon-oxygen materials into the fluidized bed equipment, heat to 100°C, use neon gas as a carrier, and add the mixed solution in step (1) into the fluidized bed furnace area in the form of spray for fluidization for 0.5h;

[0058] (3) Based on step (2), raise the temperature of the fluidized bed equipment to 600°C and continue fluidization for 1 hour;

[0059] (4) Based on step (3), continue to heat to 800°C, introduce acetylene for gas phase carbon coating for 1 hour, and obtain the negative electrode material.

[0060] Example 3

[0061] This embodiment provides a negative electrode material, which includes a core and a double-layer carbon coating layer covering the surface of the core. The core is a lithium metal-doped silicon-oxygen material.

[0062] The preparation method of the negative electrode material is as follows:

[0063] (1) Under an argon atmosphere, triphenylene and dioxane were stirred at a mass ratio of 1:100 for 1 h, then lithium metal was added and stirring was continued for 3 h to obtain a mixed solution with a mass concentration of 10 g / L.

[0064] (2) Add silicon oxide material to the fluidized bed equipment, heat to 30°C, use argon gas as carrier, and add the mixed solution in step (1) into the fluidized bed furnace area in the form of spray for 2 hours;

[0065] (3) Based on step (2), raise the temperature of the fluidized bed equipment to 300°C and continue fluidization for 5 hours;

[0066] (4) Based on step (3), continue to heat to 700°C, introduce acetylene for gas phase carbon coating for 5 hours, and obtain the negative electrode material.

[0067] Example 4

[0068] The difference between this embodiment and embodiment 1 is that the ether organic compound in step (1) of this embodiment is diethylene glycol dimethyl ether.

[0069] The remaining preparation methods and parameters are consistent with those in Example 1.

[0070] Example 5

[0071] The difference between this embodiment and Embodiment 1 is that the organic solvent in step (1) of this embodiment is terphenyl.

[0072] The remaining preparation methods and parameters are consistent with those in Example 1.

[0073] Example 6

[0074] The difference between this embodiment and Embodiment 1 is that the organic solvent in step (1) of this embodiment is tetrahydrofuran.

[0075] The remaining preparation methods and parameters are consistent with those in Example 1.

[0076] Example 7

[0077] The difference between this embodiment and embodiment 1 is that in step (3) of this embodiment, the temperature is 250℃.

[0078] The remaining preparation methods and parameters are consistent with those in Example 1.

[0079] Example 8

[0080] The difference between this comparative example and Example 1 is that in this example, terphenyl, tetrahydrofuran and lithium metal are stirred simultaneously for 15 hours.

[0081] The remaining preparation methods and parameters are consistent with those in Example 1.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that in this comparative example, the silicon-oxygen material is not doped with lithium metal and is directly coated with carbon in step (4) on a fluidized bed.

[0084] The remaining preparation methods and parameters are consistent with those in Example 1.

[0085] Comparative Example 2

[0086] The difference between this comparative example and Example 1 is that in this comparative example, lithium metal and silicon oxide materials are directly mixed without the need to prepare a mixed solution or perform fluidization.

[0087] The remaining preparation methods and parameters are consistent with those in Example 1.

[0088] Comparative Example 3

[0089] The difference between this comparative example and Example 1 is that gas phase carbon coating is not performed in step (4) of this comparative example.

[0090] The remaining preparation methods and parameters are consistent with those in Example 1.

[0091] (1) Material capacity and first-efficiency testing: The negative electrode materials obtained in Examples 1-8 and Comparative Examples 1-3 were mixed uniformly with SBR, CMC, and SP in a ratio of 85:3.2:1.8:10, coated onto copper foil, and prepared into electrode sheets with a diameter of 12 mm after drying, rolling, and cutting. These were then assembled with lithium metal sheets to form coin cells. The electrolyte was a conventional lithium-ion battery electrolyte, and the separator was a PP separator. Electrochemical performance was tested using a standard battery charge-discharge tester. The capacity of the negative electrode material is the half-cell delithiation mass specific capacity measured at a rate of 0.1C.

[0092] (2) The test scheme for the cycle performance of the material is as follows: First, the obtained negative electrode material is mixed with a commercial graphite negative electrode material with a capacity of 350 mAh / g to form a silicon-oxygen / graphite composite negative electrode material with a capacity of 500 mAh / g. Then, the composite material is mixed evenly with SBR, CMC, and SP in a ratio of 94.5:2.5:1.5:1.5, coated on copper foil, dried, rolled, and cut to prepare an electrode sheet with a diameter of 12 mm. This electrode sheet is then assembled with a lithium metal sheet to form a coin cell battery. The electrolyte is a conventional lithium-ion battery electrolyte, and the separator is a PP separator. Electrochemical performance testing was performed using a Blue Electric Tester with conventional battery charge and discharge.

[0093] The results are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] The data results from Examples 1 and 4 show that when tetrahydrofuran, dioxane, or 1,2-dimethoxyethane are not selected as ether organic compounds, the doping effect of lithium in silicon-oxygen materials will be poor, reducing the first efficiency of the material and affecting the cycle performance of the material.

[0098] The data from Examples 1, 5, and 6 show that the presence of only polycyclic aromatic compounds or ether-based organic compounds in the organic solvent leads to poor lithium doping and deterioration of subsequent cycle performance.

[0099] The data from Examples 1 and 7 show that if the temperature is too low during the second heating process, it will not be conducive to the doping effect of lithium in silicon-oxygen materials.

[0100] The data from Examples 1 and 8 show that when preparing the mixed solution, simultaneous stirring of lithium metal and organic solvent is not conducive to the uniform dispersion of lithium metal in the liquid phase, thus affecting the subsequent doping of organic lithium in silicon-oxygen materials.

[0101] The data from Example 1 and Comparative Example 1 show that without lithium metal doping, simple fluidized carbon coating cannot achieve the preparation of high-efficiency silicon-oxygen materials.

[0102] The data results from Example 1 and Comparative Example 2 show that directly mixing lithium metal with silicon-oxygen materials without dispersing lithium metal will severely affect the reaction between lithium and silicon-oxygen materials, which is not conducive to lithium doping of silicon-oxygen materials, thus resulting in the inability to effectively improve the first efficiency of the material.

[0103] The data from Example 1 and Comparative Example 3 show that without carbon coating, the prepared negative electrode material has poor conductivity, which is not conducive to improving the cycle stability of the battery material.

[0104] In summary, this invention achieves uniform doping of lithium metal in silicon-oxygen materials by spraying an organic solution of lithium into a segmented fluidization process. This improves the doping efficiency of lithium metal and simultaneously achieves a double-layer carbon coating on the silicon-oxygen materials, enhancing the initial efficiency, capacity, and cycle life of the anode material. The battery provided by this invention can achieve a discharge specific capacity of over 1358 mAh / g at 0.1C, an initial efficiency of over 84.2%, and a capacity retention rate of over 87.8% after 100 cycles at 1C.

[0105] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for producing a negative electrode material, characterized by, The preparation method comprises: mixing metal lithium and an organic solvent under an inert atmosphere to obtain a mixed solution; then spraying the mixed solution in a form of spray and performing one-time temperature fluidization on a silicon-oxygen material, and then sequentially performing secondary temperature fluidization and tertiary temperature fluidization, and simultaneously performing carbon coating in the tertiary temperature fluidization process, wherein the whole process of fluidization is performed under an inert atmosphere to obtain the negative electrode material; the one-time temperature fluidization enables the mixed solution to be coated on the surface of the silicon-oxygen material; and in the secondary temperature fluidization process, the silicon-oxygen material reacts with organic lithium substances in the mixed solution to perform lithium doping; the temperature of the one-time temperature fluidization is 30-100 ℃, the temperature of the secondary temperature fluidization is 300-600 ℃, and the temperature of the tertiary temperature fluidization is 700-1100 ℃.

2. The method of producing a negative electrode material according to claim 1, characterized by, The organic solvent comprises a polycyclic aromatic compound and an ether organic substance.

3. The method of producing a negative electrode material according to claim 2, characterized by, The mass ratio of the polycyclic aromatic compound to the ether organic substance is (1-10):

100.

4. The method of claim 2, wherein the method further comprises a step of adding a binder to the mixture. The polycyclic aromatic compound comprises any one or a combination of at least two of biphenyl, naphthalene, terphenyl, anthracene, phenanthrene, tetracene, pentacene, pyrene, chrysene, triphenylene or coronene, and derivatives thereof.

5. The method of claim 2, wherein the method further comprises the step of adding a binder to the mixture. The ether organic substance comprises any one or a combination of at least two of dimethyl ether, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.

6. The method of producing a negative electrode material according to claim 5, wherein The ether organic substance is any one or a combination of at least two of tetrahydrofuran, dioxane or 1,2-dimethoxyethane.

7. The method of claim 2, wherein the method further comprises a step of adding a binder to the mixture. The mixing comprises: stirring the polycyclic aromatic compound and the ether organic solvent for one time, and then stirring the polycyclic aromatic compound and the ether organic solvent for two times after adding metal lithium.

8. The method of claim 7, wherein the method further comprises a step of mixing the carbon material and the binder. The stirring time for one time is 1-5 h.

9. The method of claim 7, wherein the method further comprises a step of mixing the carbon material and the metal compound. The stirring time for two times is 3-15 h.

10. The method of claim 2, wherein the method further comprises the step of: 5 heating the mixture to a temperature of 300-600°C. The mass concentration of the mixed solution is 1-200 g / L.

11. The method of claim 1, wherein the method is characterized by: The one-time temperature fluidization time is 0.5-2 h.

12. The method of claim 1, wherein the method is characterized by: The secondary temperature fluidization time is 1-5 h.

13. The method of claim 1, wherein the method is characterized by: The tertiary temperature fluidization time is 1-5 h.

14. The method of claim 1, wherein the method is characterized by: The carbon coating comprises gas-phase carbon coating.

15. The method of claim 14, wherein the method further comprises a step of mixing the carbon material and the metal compound. The carbon source of the gas-phase carbon coating comprises any one or a combination of at least two of methane, ethane, propane, ethylene, propylene, acetylene, toluene or benzene.

16. The method of claim 1, wherein the method is performed in a glove box. The preparation method comprises: under an inert atmosphere, stirring the polycyclic aromatic compound and the ether organic substance for one time for 1-5 h at a mass ratio of (1-10):100, and then stirring the polycyclic aromatic compound and the ether organic substance for two times for 3-15 h after adding metal lithium to obtain a mixed solution with a mass concentration of 1-200 g / L; then spraying the mixed solution in a form of spray and performing one-time temperature fluidization on a silicon-oxygen material at 30-100 ℃ for 0.5-2 h, and then performing secondary temperature fluidization at 300-600 ℃ for 1-5 h, and finally performing tertiary temperature fluidization at 700-1100 ℃ for 1-5 h, and simultaneously performing gas-phase carbon coating in the tertiary temperature fluidization process, wherein the whole process of fluidization is performed under an inert atmosphere to obtain the negative electrode material.

17. A negative electrode material, characterized by, The negative electrode material is prepared by the method for preparing a negative electrode material according to any one of claims 1-16; the negative electrode material comprises an inner core and a double-layer carbon coating layer coated on the surface of the inner core, and the inner core is a lithium metal-doped silicon-oxygen material.

18. A lithium-ion battery, characterized by, The lithium ion battery comprises the negative electrode material according to claim 17.

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