Preparation of cerium-doped amorphous carbon-coated silicon-carbon composite by silane pyrolysis method and its application

Abstract

The present invention discloses a method for preparing a cerium-doped amorphous carbon-coated silicon-carbon composite material by silane pyrolysis and its application, which relates to the field of preparation of lithium-ion battery materials. The cerium-doped amorphous carbon-coated silicon-carbon composite material has a core-shell structure, with a core of a nitrogen and fluorine-doped nano-silicon porous carbon material and a shell of cerium-doped amorphous carbon; the content of cerium-doped amorphous carbon in the cerium-doped amorphous carbon-coated silicon-carbon composite material is 1-5 wt%; the cerium content in the cerium-doped amorphous carbon is 20-80 wt%. In the present invention, silicon fluoride is deposited in the aminated porous carbon. Relying on the easy synergistic effect between the electron-withdrawing groups in the aminated porous carbon and the electron-donating groups in the silicon fluoride alkane, the density of the material is improved, and the expansion and high-temperature storage performance are improved. At the same time, a cerium compound is deposited on the surface of the core by plasma deposition to improve the rate performance by utilizing the characteristics of the high electron conductivity of the cerium compound.

Description

Technical Field

[0001] The present invention relates to the field of preparation of lithium ion battery materials, and particularly to a method for preparing cerium-doped amorphous carbon-coated silicon-carbon composite material by silane pyrolysis and its application. Background Art

[0002] Silane pyrolysis silicon-carbon materials are applied in fields such as high-energy density lithium ion batteries due to their high energy density, low expansion, good cycle performance, etc. However, due to the porous carbon structure of the inner core of this type of silicon-carbon, the electronic conductivity of the material is poor, which affects the rate performance. There are many measures to reduce the impedance of the material, mainly including surface coating of the material, doping to reduce the electronic impedance of the material, and the types of coating materials mainly include amorphous carbon, metal elements, and metal oxide composites. Moreover, due to the high activity of the inner core nano-silicon and poor high-temperature storage, it is necessary to improve by reducing the activity of the inner core nano-silicon and enhancing the fast charging electronic or ionic conductivity, so as to improve the power and high-temperature performance of the material. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing cerium-doped amorphous carbon-coated silicon-carbon composite material by silane pyrolysis and its application. By silane pyrolysis, a nitrogen-fluorine-doped nano-silicon porous carbon material is prepared, and then a cerium compound is deposited on its surface by plasma deposition to obtain a cerium compound-deposited nitrogen-fluorine-doped nano-silicon porous carbon material, so as to improve the high-temperature performance and power performance of the silicon-carbon material.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is a cerium-doped amorphous carbon-coated silicon-carbon composite material. The cerium-doped amorphous carbon-coated silicon-carbon composite material has a core-shell structure, the inner core is a nitrogen-fluorine-doped nano-silicon porous carbon material, and the outer shell is cerium-doped amorphous carbon; the content of cerium-doped amorphous carbon in the cerium-doped amorphous carbon-coated silicon-carbon composite material is 1-5 wt%; the cerium content in the cerium-doped amorphous carbon is 20-80 wt%.

[0006] Further, the preparation method of the nitrogen-fluorine-doped nano-silicon porous carbon material includes the following steps:

[0007] Deposit nano-silicon for 30-300 min on the aminated porous carbon in a mixed gas of fluorinated silane at a pressure of 1-2 Mpa, a temperature of 300-500 °C, and a gas flow rate of 10-100 mL / min to obtain the nitrogen-fluorine-doped nano-silicon porous carbon material.

[0008] During the preparation process of the aminated porous carbon, an organic compound is doped and coated on the surface. At a pressure of 1-2 Mpa and a temperature of 300-500 °C, the organic compound doped and coated on the surface of the aminated porous carbon is converted into amorphous carbon.

[0009] Under positive pressure conditions, the boiling point of silicon tetrafluoride decreases, the decomposition temperature is low, and the deposition efficiency is high. At the same time, under positive pressure conditions, fluorine gas is easy to be discharged from the pipeline. If the pressure is too low (≤1 Mpa), the exhaust gas cannot be discharged from the pipe. If the pressure is too high, the pressure inside the pipe is too large, which is prone to explosion, posing a safety hazard and reducing its manufacturability.

[0010] Furthermore, the silicon tetrafluoride mixed gas is a mixed gas of silicon tetrafluoride and argon, or a mixed gas of silicon difluoride and argon; the volume ratio of silicon tetrafluoride to argon is 1:1, and the volume ratio of silicon difluoride to argon is 1:1.

[0011] The reason for selecting the mixed gas and limiting the volume ratio to 1:1 is mainly to ensure the uniformity of deposition. If it is pure silicon tetrafluoride, the deposition rate will be too high, which is prone to cause deposition blockage and affect the deposition quality.

[0012] Furthermore, the preparation method of the amino-functionalized porous carbon includes the following steps:

[0013] Add the porous carbon to a mixed acid with a volume ratio of concentrated sulfuric acid: concentrated nitric acid of 1:1 and soak it, then filter, wash, and vacuum dry to obtain carboxylated porous carbon;

[0014] Add the carboxylated porous carbon to a solution of thionyl chloride in dimethylformamide and heat under reflux. After that, centrifuge, wash, centrifuge again, and vacuum dry to obtain acyl chloride-functionalized porous carbon;

[0015] Add the acyl chloride-functionalized porous carbon to a dopamine solution and heat to react. After centrifugation, wash successively with anhydrous ethanol, acetone, and dichloromethane, and dry to obtain the amino-functionalized porous carbon.

[0016] The -CO-Cl on the surface of the acyl chloride-functionalized porous carbon undergoes a chemical grafting reaction with the -NH of dopamine. If the number of -CO-Cl on the surface of the acyl chloride-functionalized porous carbon is small, the grafting effect will be reduced, the electron impedance of the amino-functionalized porous carbon is high, the tapped density is small, and the structural stability is poor.

[0017] The second technical solution of the present invention is a preparation method of the cerium-doped amorphous carbon-coated silicon-carbon composite material as described above, including the following steps:

[0018] Using plasma deposition method, with a nitrogen-fluorine-doped nano-silicon porous carbon material as the substrate and a cerium compound as the target, evacuate to a vacuum degree of 1.0×10 Pa to 9×10 Pa in chamber A; fill the working gas argon in chamber B, adjust the flow rate, and after the working gas pressure is stable, turn on the main arc power supply of the cerium compound metal target to form a cerium compound plasma in vacuum chamber A, and deposit for 10 - 60 minutes to obtain the cerium-doped amorphous carbon-coated silicon-carbon composite material.

[0019] Further, the cerium compound is one of cerium carbonate, cerium oxide, cerium trichloride, cerium carbonate, cerium fluoride, and cerium oxalate.

[0020] The third technical solution of the present invention is an application of the above-mentioned cerium-doped amorphous carbon-coated silicon-carbon composite material in the preparation of an anode material for a lithium-ion battery.

[0021] The fourth technical solution of the present invention is a lithium-ion battery anode material, including the above-mentioned cerium-doped amorphous carbon-coated silicon-carbon composite material.

[0022] The present invention discloses the following technical effects:

[0023] In the present invention, silicon fluoride is deposited in the aminated porous carbon. Relying on the easy synergistic effect between the electron-withdrawing groups in the aminated porous carbon and the electron-donating groups in the fluorosilane, the density of the material is improved, and the swelling and high-temperature storage performance are improved. At the same time, a cerium compound is deposited on the surface of its core by plasma deposition, giving play to the high electron conductivity of the cerium compound to improve the rate performance. Moreover, the plasma method has the advantages of high deposition density, controllable process, high efficiency, and no impact on the structure of the coating material.

[0024] In the present invention, the nanosilicon grains generated by the cracking of silane are deposited in the aminated porous carbon to reduce swelling, and a cerium compound is doped in its outer layer to reduce impedance and improve the specific capacity of the coating layer, and to avoid the contact between the core silicon and the external pores and electrolyte to reduce its side reactions and improve the safety performance. At the same time, the easy synergistic effect between the electron-withdrawing groups in the aminated porous carbon and the electron-donating groups in the fluorosilane improves the density of the material, and the swelling and high-temperature storage performance are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is the SEM image of the cerium-doped amorphous carbon-coated silicon-carbon composite material prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0027] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0028] It should be understood that the terms used in this invention are only for describing particular embodiments and are not intended to limit the invention. Additionally, for the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value and any intermediate value within the stated range, is also included in the invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0030] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0031] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0032] The "%" mentioned in this invention, unless otherwise specified, is calculated by mass percentage.

[0033] The raw materials used in the examples and comparative examples of this invention can be obtained from the purchase channels unless otherwise specified.

[0034] The preparation method of the aminated porous carbon used in the examples of this invention is as follows: 10 g of porous carbon (porosity 35%, pore diameter 5 nm, pore volume 2 cm 3(g) was added to 100 g of concentrated sulfuric acid / concentrated nitric acid (volume ratio 1:1) and soaked for 24 h, filtered, washed with deionized water, and vacuum dried at 80 °C for 24 h to obtain carboxylated porous carbon; then 3 g of carboxylated porous carbon was added to 100 g of a thionyl chloride solution of 5% dimethylformamide (DMF), and the mixture was heated under reflux at 80 °C (the technical effect is equivalent at 50 - 100 °C and 80 °C) for 24 hours, centrifuged, washed with tetrahydrofuran, centrifuged again, and vacuum dried at 80 °C for 24 h to obtain acyl chloride-functionalized porous carbon; then 10 g of acyl chloride-functionalized porous carbon was added to 100 g of dopamine solution and heated for reaction for 96 hours, centrifuged, and washed successively with absolute ethanol, acetone, and dichloromethane, and vacuum dried at 80 °C for 24 h to obtain amino-functionalized porous carbon (porosity 25%, pore diameter 3 nm, pore volume 1 cm 3 / g).

[0035] Example 1

[0036] Step S1: Place the amino-functionalized porous carbon in a tubular furnace, and at a pressure of 1.5 Mpa and a temperature of 400 °C, introduce a silicon fluoride gas mixture (a mixture of silicon tetrafluoride and argon, silicon tetrafluoride:argon volume ratio = 1:1) with a gas flow rate of 50 mL / min, and deposit nanosilicon in the amino-functionalized porous carbon for 60 min to obtain a nitrogen-fluorine-doped nanosilicon porous carbon material.

[0037] Step S2: Using the plasma deposition method, with the nitrogen-fluorine-doped nanosilicon porous carbon material prepared in Step S1 as the substrate and cerium carbonate as the target, evacuate to a vacuum degree of 5×10 Pa in chamber A; fill working gas argon in chamber B, adjust the flow rate, and after the working pressure stabilizes at 50×10 Pa, turn on the main arc power supply of the cerium carbonate metal target to form a cerium compound plasma in vacuum chamber A, and deposit for 30 min to obtain a cerium-deposited nitrogen-fluorine-doped nanosilicon porous carbon material (a cerium-doped amorphous carbon-coated silicon-carbon composite material, abbreviated as a silicon-carbon composite material).

[0038] Example 2

[0039] Step S1: Place the amino-functionalized porous carbon in a tubular furnace, and at a pressure of 1 Mpa and a temperature of 500 °C, introduce a silicon fluoride gas mixture (a mixture of silicon difluoride and argon, silicon difluoride:argon volume ratio = 1:1) with a gas flow rate of 10 mL / min, and deposit nanosilicon in the amino-functionalized porous carbon for 300 min to obtain a nitrogen-fluorine-doped nanosilicon porous carbon material.

[0040] Step S2: Using the plasma deposition method, with the nitrogen and fluorine doped nano-silicon porous carbon material prepared in Step S1 as the substrate, cerium fluoride as the target, and evacuating to a vacuum degree of 1.0×10 Pa in Chamber A; filling the working gas argon in Chamber B, adjusting the flow rate, and after the working pressure reaches 10×10 Pa and stabilizes, turning on the main arc power supply of the cerium fluoride metal target to form cerium fluoride plasma in Vacuum Chamber A, with a deposition time of 60 min, to obtain a cerium-deposited nitrogen and fluorine doped nano-silicon porous carbon material (cerium-doped amorphous carbon-coated silicon-carbon composite material, hereinafter referred to as silicon-carbon composite material).

[0041] Example 3

[0042] Step S1: Place the aminated porous carbon into a tubular furnace, and at a pressure of 2 Mpa and a temperature of 300 °C, introduce a silicon fluoride mixed gas (a mixed gas of silicon tetrafluoride and argon, volume ratio of silicon tetrafluoride:argon = 1:1), with a gas flow rate of 100 mL / min, and deposit nano-silicon in the aminated porous carbon for 30 min to obtain a nitrogen and fluorine doped nano-silicon porous carbon material.

[0043] Step S2: Using the plasma deposition method, with the nitrogen and fluorine doped nano-silicon porous carbon material prepared in Step S1 as the substrate, cerium oxalate as the target, and evacuating to a vacuum degree of 9×10 Pa in Chamber A; filling the working gas argon in Chamber B, adjusting the flow rate, and after the working pressure reaches 90×10 Pa and stabilizes, turning on the main arc power supply of the cerium oxalate metal target to form a cerium compound plasma in Vacuum Chamber A, with a deposition time of 10 min, to obtain a cerium-deposited nitrogen and fluorine doped nano-silicon porous carbon material (cerium-doped amorphous carbon-coated silicon-carbon composite material, hereinafter referred to as silicon-carbon composite material).

[0044] Comparative Example 1

[0045] The difference from Example 1 is only that the aminated porous carbon in Step 1 is replaced with porous carbon (porosity 35%, pore diameter 5 nm, pore volume 2 cm 3 / g).

[0046] Comparative Example 2

[0047] Dissolve 10 g of cerium carbonate in 500 g of N-methylpyrrolidone, then add 100 g of the nitrogen and fluorine doped nano-silicon porous carbon material in Step S1 of Example 1, and mix evenly, filter, and vacuum dry the filter residue at 80 °C for 24 h, then transfer it to a tubular furnace and carbonize it at 800 °C for 3 h in an argon atmosphere to obtain a cerium-coated nitrogen and fluorine doped nano-silicon porous carbon material.

[0048] Effect Verification Example

[0049] 1. SEM Test

[0050] The cerium-deposited nitrogen and fluorine-doped nano-silicon porous carbon material prepared in Example 1 was subjected to SEM testing, and the test results are as follows Figure 1 shown. The particle sizes of the materials are uniform. The surface of the material shows a light white color, which is the carbon material, and the particle size of the material is between 5 - 10 μm.

[0051] 2. Physical and chemical properties and coin cell testing

[0052] In order to compare and verify the effects of Examples 1 - 3 and Comparative Examples 1 - 2 above, the silicon-carbon composite materials obtained in Examples 1 - 3 and Comparative Examples 1 - 2 above were used as the active material raw materials for the negative electrode of the lithium-ion battery. They were respectively assembled into coin cells through the following methods, and were denoted as A1, A2, A3, B1, and B2: A binder, a conductive agent, and a solvent were added to the corresponding composite materials, stirred to make a slurry, coated on a copper foil, dried and rolled to obtain a negative electrode sheet. Among them, the binder used was LA132, the conductive agent was conductive carbon black (SP), and the solvent was N-methylpyrrolidone (NMP). The dosage ratios of the composite material, SP, LA132, and NMP were 95 g: 1 g: 4 g: 220 mL; a metal lithium sheet was used as the counter electrode, the separator was a polypropylene (PP) film, the electrolyte used LiPF6 as the electrolyte, and a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 was used as the solvent; the coin cells were assembled in a glove box filled with argon. And the electrochemical performance was tested on a Wuhan Blue Electric CT2001A battery tester. Among them, the charge and discharge conditions used during the test were: the charge and discharge voltage range was 0.005 V - 2.0 V, the charge and discharge rate was 0.1 C, and the full charge expansion of the negative electrode sheet was tested. At the same time, the specific surface area, tapped density, and cerium content of the material were tested through GB / T - 38823 "Silicon Carbon". And the powder conductivity of the powder was tested through a four-probe tester.

[0053] The test results are shown in Table 1 below:

[0054] Table 1

[0055]

[0056] It can be seen from the data in Table 1 that the powder conductivity of the cerium-deposited nitrogen and fluorine-doped nano-silicon porous carbon materials prepared in Examples 1 - 3 of the present invention is significantly better than that of Comparative Examples 1 - 2. Specifically, the cerium compounds with high electron conductivity deposited on the material surface and its amorphous carbon can both reduce the electron conductivity of the material and reduce the voltage plateau to improve the specific capacity performance.

[0057] 3. Soft-pack battery

[0058] For the negative electrode sheet prepared by using artificial graphite doped with 90 wt% (by weight percentage of the negative electrode sheet) in the cerium-deposited nitrogen and fluorine-doped nano-silicon porous carbon material as the negative electrode material, NCM532 as the positive electrode material, Celgard 2400 membrane as the separator, and the electrolyte using LiPF6 as the electrolyte and a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 as the solvent, and the concentration of LiPF6 being 1.2 mol / L; a 5 Ah soft-pack battery was prepared.

[0059] First, the negative electrode sheets corresponding to Examples 1-3 and Comparative Examples 1-2 of the present application were respectively subjected to the following performance tests, and the test results are shown in Tables 2 and 3:

[0060] A. Liquid absorption capacity test: Using a 1 mL burette, sucking V mL of the electrolyte, dropping a drop on the surface of the negative electrode sheet, and timing until the electrolyte is completely absorbed, recording the required time t, and calculating the liquid absorption rate of the electrode sheet as V / t.

[0061] B. Electrode sheet rebound rate test: First, use a thickness gauge to measure the average thickness of the rolled negative electrode sheet as D1; then charge the soft-pack battery to 100% SOC, then dissect the negative electrode sheet, and measure the thickness of the negative electrode sheet when fully charged as D2, and calculate the rebound rate according to the following formula:

[0062] Rebound rate = (D2 - D1) × 100% / D1.

[0063] C. Electrode sheet resistivity test: Use a resistivity tester to measure the resistivity of the electrode sheet.

[0064] Table 2

[0065] Liquid absorption rate (t) Pole piece bounce rate (%) Pole piece resistivity (mΩ) Example 1 56 37.6 14.5 Example 2 59 35.2 16.7 Example 3 52 39.5 12.6 Comparative Example 1 65 44.5 46.8 Comparative Example 2 72 48.2 57.1

[0066] As can be seen from Table 2, when the silicon-carbon composite materials prepared in Examples 1-3 of the present invention are used as the active material raw material of the battery negative electrode sheet, the liquid absorption capacity of the negative electrode sheet is significantly higher than that of Comparative Examples 1-2. The experimental results show that the negative electrode sheet prepared by using the composite material of the present invention (the silicon-carbon composite material prepared in Examples 1-3) has more excellent liquid absorption capacity, which is related to the high specific surface area of the material. At the same time, the rebound rate and resistivity of the negative electrode sheet in the examples are significantly lower than those of Comparative Examples 1-2. The reason may be that the metal material with high electronic conductivity on the surface of the silicon-carbon composite material of the present invention reduces the impedance, and the porous structure of the silicon-carbon composite material reduces the expansion of the material.

[0067] D. Cycle performance test: The charge and discharge conditions adopted are: with a charge and discharge rate of 1C / 1C and a voltage range of 2.8V - 4.2V, and the cycle performance of the battery is tested at a temperature of 25 ± 3°C.

[0068] E. High-temperature storage test: At room temperature, the battery capacity is measured as A1. After placing it at 55 °C for 7 days, the battery is charged to 100% SOC, and the battery capacity is measured as A2. Then, calculate the battery capacity recovery rate = A2 / A1 × 100%.

[0069] Table 3

[0070]

[0071] As can be seen from Table 3, when the silicon-carbon composite materials prepared in Examples 1-3 of the present invention are used to prepare lithium-ion batteries and their battery cycling performance and high-temperature storage performance are tested, their performance is significantly better than that of Comparative Examples 1-2. The reason may be that: the electrode sheets made of the silicon-carbon composite materials provided in the examples of the present invention have a lower expansion rate, and the structure of the electrode sheets is more stable during charge and discharge, improving their cycling performance. At the same time, the silicon-carbon composite materials provided in Examples 1-3 of the present invention have a lower expansion, resulting in less damage to the structure of the material during charge and discharge, reducing the lithium ions consumed for repairing the SEI film, and improving their high-temperature storage performance.

[0072] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A cerium-doped amorphous carbon-coated silicon-carbon composite material, characterized in that, The cerium-doped amorphous carbon-coated silicon-carbon composite material has a core-shell structure, wherein the core is a nitrogen-fluorine-doped nano-silicon porous carbon material and the shell is a cerium-doped amorphous carbon; the content of cerium-doped amorphous carbon in the cerium-doped amorphous carbon-coated silicon-carbon composite material is 1 to 5 wt%; the content of cerium in the cerium-doped amorphous carbon is 20 to 80 wt%; The preparation method of the nitrogen-fluorine doped nano-silicon porous carbon material comprises the following steps: Depositing nano-silicon on the amino-modified porous carbon in a fluorinated silane mixed gas at a pressure of 1 to 2 MPa, a temperature of 300 to 500° C., and a gas flow rate of 10 to 100 mL / min for 30 to 300 minutes to obtain the nitrogen-fluorine-doped nano-silicon porous carbon material; The preparation method of the amination porous carbon comprises the following steps: The porous carbon was added to a mixed acid of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 1:1 and then filtered, washed, and vacuum-dried to obtain carboxylated porous carbon; The carboxylated porous carbon is added to a dimethylformamide-thionyl chloride solution and heated under reflux for reaction, followed by centrifugation, washing, centrifugation, and vacuum drying to obtain chlorinated porous carbon; The acyl chloride porous carbon is added to a dopamine solution and heated for reaction. After centrifugation, the solution is washed with anhydrous ethanol, acetone and dichloromethane in sequence and dried to obtain the amino-modified porous carbon.

2. The cerium-doped amorphous carbon-coated silicon-carbon composite material according to claim 1, wherein The fluorinated silane mixed gas is a mixed gas of silicon tetrafluoride and argon, or a mixed gas of silicon difluoride and argon; the volume ratio of the silicon tetrafluoride to argon is 1:1, and the volume ratio of the silicon difluoride to argon is 1:

1.

3. A method for preparing the cerium-doped amorphous carbon-coated silicon-carbon composite material according to any one of claims 1 to 2, characterized in that, The following steps are involved: A plasma deposition method is adopted, with nitrogen and fluorine doped nano-silicon porous carbon material as a matrix and a cerium compound as a target material, and the vacuum degree of chamber A is evacuated to 1.0×10Pa-9×10Pa; argon gas is filled into chamber B, and the flow rate is adjusted. After the working gas pressure stabilizes, the main arc power supply of the cerium compound metal target is turned on to form cerium compound plasma in the vacuum chamber A, and deposition is carried out for 10-60 minutes to obtain the cerium-doped amorphous carbon-coated silicon-carbon composite material.

4. The preparation method according to claim 3, characterized in that, The cerium compound is one of cerium carbonate, cerium oxide, cerium trichloride, cerium carbonate, cerium fluoride, and cerium oxalate.

5. Use of the cerium-doped amorphous carbon-coated silicon-carbon composite material according to any one of claims 1 to 2 in preparing a negative electrode material for a lithium-ion battery.

6. A negative electrode material for a lithium-ion battery, characterized in that, The invention comprises the cerium-doped amorphous carbon-coated silicon-carbon composite material according to any one of claims 1 to 2.

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