Silicon-carbon negative electrode material, and preparation method therefor and use thereof

Abstract

A silicon-carbon negative electrode material, and a preparation method therefor and a use thereof. The preparation method comprises the following steps: (1) mixing a silicon source, a carbon source, and a binder with a solvent, and carrying out spray drying to obtain silicon-carbon composite particles; (2) pre-polymerizing 1,3,5-tris(4-aminophenyl)benzene, terephthalaldehyde, and benzenetricarboxaldehyde, mixing with the silicon-carbon composite particles obtained in the step (1), and reacting to obtain a precursor; and (3) carrying out high-temperature carbonization treatment on the precursor to obtain a silicon-carbon negative electrode material. The silicon-carbon negative electrode material prepared by the method has good conductivity and good rate performance, and keeps the particle size unchanged in the cycle process, so that fall-off of the electrode sheet and powdering thereof can be avoided in the cycle process to a great extent, and thus the cycle performance is stable.

Description

A silicon-carbon negative electrode material and its preparation method and application Technical Field

[0001] The present application relates to the technical field of battery materials, for example, a silicon-carbon negative electrode material and its preparation method and application. Background Art

[0002] Silicon, as the negative electrode material for lithium-ion batteries, boasts a theoretical specific capacity of 4000 mAh / g, making it the highest known specific capacity lithium-ion battery negative electrode material and, as such, has attracted widespread attention from researchers. However, due to its significant volume expansion, silicon electrode materials are prone to pulverization after expansion, resulting in detachment from the negative electrode current collector, leading to a loss of electrical connection between the negative electrode active material and the current collector. This drawback of silicon materials has led to extensive research efforts to address this issue.

[0003] The most common method is to composite silicon materials with carbon materials to prepare silicon-carbon negative electrode materials, and use the carbon material coating to inhibit the volume expansion of the silicon material and improve its conductivity, but this method is difficult to effectively improve the cycle performance and rate performance of the material.

[0004] In addition, CN109216693A discloses a method for preparing silicon-carbon negative electrode materials for lithium-ion batteries, which uses nano-Si and CNTs to grow in situ on MOF-5 and obtain a silicon-carbon composite material after high-temperature carbonization. Since the nano-Si is evenly coated with a carbonized layer, the expansion of Si can be inhibited; in addition, adding CNTs to the negative electrode material can act as a conductive network structure, greatly improving the electronic conductivity of the silicon-carbon negative electrode, thereby improving the first efficiency and rate capability of the silicon-carbon negative electrode charge and discharge cycle.

[0005] Although the above method can inhibit the expansion of silicon-based negative electrode materials to a certain extent to improve their electrochemical performance, MOF materials generally have poor stability. Long-term high-temperature treatment will cause their structure to collapse, destroying the protective layer that inhibits the expansion of nano-silicon and affecting the electrochemical performance of the material.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] The present application provides a silicon-carbon negative electrode material, a preparation method and an application thereof. The silicon-carbon negative electrode material prepared by the method described in the present application has good conductivity, good rate performance, and the particle volume remains unchanged during the cycle. Therefore, it can largely prevent the negative electrode material from falling off during the cycle, thereby improving the stability of the material's cycle performance.

[0009] In a first aspect, the present application provides a method for preparing a silicon-carbon negative electrode material, the preparation method comprising the following steps:

[0010] (1) mixing a silicon source, a carbon source, and a binder with a solvent, and spray drying to obtain silicon-carbon composite particles;

[0011] (2) prepolymerizing 1,3,5-tris(4-aminophenyl)benzene (TAPB), terephthalaldehyde (PDA) and trimesic acid (BTCA), and then mixing the mixture with the silicon-carbon composite particles obtained in step (1) to react and obtain a precursor;

[0012] (3) subjecting the precursor to high-temperature carbonization treatment to obtain the silicon-carbon negative electrode material.

[0013] This application uses 1,3,5-tris(4-aminophenyl)benzene (TAPB), terephthalaldehyde (PDA) and trimesic acid (BTCA) as raw materials to polymerize into COF cages. The COF cages can have high thermal stability and can stably exist in a lithium-ion electrolyte environment. The pore structure of the generated COF provides a large surface area, which is conducive to the diffusion of electrolyte and lithium ions to the silicon-carbon core, thereby improving the initial efficiency and rate performance of the material. The COF cage can place elemental silicon in a "cage" and provide sufficient buffer space for the volume effect of elemental silicon. The overall volume of the resulting Si / C@COF negative electrode material remains basically unchanged during the charge and discharge process. Therefore, it is possible to fully utilize the specific capacity of the silicon negative electrode while ensuring the cyclic stability of the material.

[0014] In one embodiment, the silicon source in step (1) comprises nano-silicon particles.

[0015] In one embodiment, the median particle size D50 of the silicon source is 100-500 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm or 500 nm.

[0016] In one embodiment, the carbon source includes any one of an organic carbon source, carbon nanotubes, carbon nanofibers or graphene, or a combination of at least two thereof.

[0017] In one embodiment, the binder includes any one of melamine formaldehyde resin, carboxymethyl cellulose, polyethylene oxide, or polyvinyl alcohol, or a combination of at least two thereof.

[0018] In one embodiment, the solvent includes any one of water, methanol or ethanol, or a combination of at least two of them.

[0019] In one embodiment, the mass ratio of the silicon source, carbon source and binder in step (1) is 50:(4-6):(0.8-1.5), for example: 50:4:0.8, 50:5:1, 50:4:0.9, 50:6:0.8 or 50:6:1.5, etc.

[0020] In one embodiment, the spray drying temperature is 100-200°C, for example, 100°C, 120°C, 150°C, 180°C or 200°C.

[0021] In one embodiment, the median particle size D50 of the silicon-carbon composite particles is 0.5-1.5 μm, for example, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm or 1.5 μm.

[0022] In one embodiment, the prepolymerization in step (2) comprises stirring 1,3,5-tris(4-aminophenyl)benzene, terephthalaldehyde and trimesic acid in a mixed solution of aniline and benzaldehyde.

[0023] In one embodiment, the stirring time is 3 to 5 minutes, for example, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes.

[0024] In one embodiment, during the prepolymerization process, the concentration of amino groups in 1,3,5-tris(4-aminophenyl)benzene in the system is 20 to 40 mmol / L.

[0025] In one embodiment, during the prepolymerization process, the total concentration of aldehyde groups in terephthalaldehyde and trimesic acid in the system is 20 to 40 mmol / L.

[0026] In one embodiment, during the prepolymerization process, the total concentration of amino groups in aniline and aldehyde groups in benzaldehyde in the system is 100-150 mmol / L.

[0027] In one embodiment, the molar ratio of terephthalaldehyde to trimesaldehyde is (1-3):2, for example: 1:2, 1.5:2, 2:2, 2.5:2 or 3:2.

[0028] In one embodiment, the solid-to-liquid ratio of the silicon-carbon composite particles and the prepolymerized reactants in step (2) is 0.01 to 0.05 g / mL, for example, 0.01 g / mL, 0.02 g / mL, 0.03 g / mL, 0.04 g / mL or 0.05 g / mL.

[0029] In one embodiment, stirring is performed during the mixing process.

[0030] In one embodiment, the stirring speed is 100-1500 rpm, for example, 100 rpm, 500 rpm, 1000 rpm, 1200 rpm or 1500 rpm.

[0031] In one embodiment, the reaction temperature in step (2) is 20-40°C, for example, 20°C, 25°C, 30°C, 35°C or 40°C.

[0032] In one embodiment, the reaction time is 30 to 80 hours, for example, 30 hours, 40 hours, 50 hours, 60 hours or 80 hours.

[0033] In one embodiment, the precursor includes a coating layer.

[0034] In one embodiment, the coating layer has a thickness of 10 to 100 nm, for example, 10 nm, 20 nm, 50 nm, 80 nm or 100 nm.

[0035] In one embodiment, the temperature of the high-temperature carbonization treatment in step (3) is 650-800°C, for example, 650°C, 680°C, 700°C, 750°C or 800°C.

[0036] In one embodiment, the high-temperature carbonization treatment time is 0.5 to 1 h, for example, 0.5 h, 0.6 h, 0.8 h, 0.9 h or 1 h.

[0037] This application further improves the conductivity of the negative electrode material by simply carbonizing a portion of the COF cage at high temperature. The COF material exhibits excellent thermal stability, and even short heat treatments do not cause its structure to collapse. Furthermore, the synthesized COF material has abundant amino groups on its surface, which can increase the material's electron density and conductivity. Furthermore, it can provide certain lithium insertion sites, thereby increasing the material's discharge capacity.

[0038] In a second aspect, the present application provides a silicon-carbon negative electrode material, which is prepared by the method described in the first aspect.

[0039] In a third aspect, the present application provides a negative electrode plate, which comprises the silicon-carbon negative electrode material as described in the second aspect.

[0040] In a fourth aspect, the present application provides a lithium-ion battery, wherein the lithium-ion battery comprises the negative electrode sheet as described in the third aspect.

[0041] Compared with the related art, this application has the following beneficial effects:

[0042] (1) The present application uses specific raw materials to make a COF cage with high thermal stability. The pore structure of COF provides a large surface area, which is conducive to the diffusion of electrolyte and lithium ions into the silicon-carbon core, thereby improving the initial efficiency and rate performance of the material. The COF cage can place elemental silicon in a "cage" and provide sufficient buffer space to adapt to the volume effect of elemental silicon. Short-term high-temperature carbonization can avoid structural collapse while further improving the conductivity of the material.

[0043] (2) The 0.1C discharge capacity of the battery made of the silicon-carbon negative electrode material described in this application can reach more than 2324.65mAh / g, the 100-cycle capacity retention rate can reach more than 97.98%, and the 2C / 0.1C capacity retention rate can reach more than 53.87%.

[0044] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0046] FIG1 is a schematic diagram of the synthesis of the silicon-carbon negative electrode material according to an embodiment of the present application. DETAILED DESCRIPTION

[0047] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0048] Example 1

[0049] This embodiment provides a silicon-carbon negative electrode material. The synthesis schematic diagram of the silicon-carbon material is shown in FIG1 . The preparation method of the silicon-carbon negative electrode material is as follows:

[0050] (1) Nano-silicon particles with a D50 of 200 nm, carboxymethyl cellulose, and carbon nanotubes are uniformly dispersed in water at a mass ratio of 50:1:5 to prepare a slurry, and spray-dried at 150° C. to obtain spherical and / or quasi-spherical silicon-carbon composite particles with a D50 of 0.8 μm;

[0051] (2) TAPB (1,3,5-tris(4-aminophenyl)benzene), PDA (terephthalaldehyde), and BTCA (tris-benzene trimethylene aldehyde) were mixed and stirred in a mixed solution of aniline and benzaldehyde for 3 minutes for prepolymerization. The concentration of amino groups in TAPB and the concentration of aldehyde groups in BTCA and PDA in the mixture were maintained at 30 mmol / L. The concentration of amino groups and aldehyde groups in the mixed solution of aniline and benzaldehyde was 120 mmol / L. The molar ratio of PDA and BTCA was 3:2. The silicon-carbon composite particles obtained in step (1) were then added to the above mixed solution. The solid-liquid ratio of the silicon-carbon composite particles to the reactants was 0.03 g / mL. The reaction was stirred at a speed of 300 rpm and reacted at 25°C for 60 hours, so that the surface reactants and the core of the silicon-carbon negative electrode presented a core-cage structure. The coating thickness was 50 nm. The reaction solution was then filtered, washed, and dried to obtain a precursor.

[0052] (3) reacting the precursor at 750° C. for 40 min to carbonize part of the COF cage at high temperature for a short time to obtain the silicon-carbon negative electrode material.

[0053] Example 2

[0054] This embodiment provides a silicon-carbon negative electrode material. The synthesis schematic diagram of the silicon-carbon material is shown in FIG1 . The preparation method of the silicon-carbon negative electrode material is as follows:

[0055] (1) Nano-silicon particles with a D50 of 500 nm, carboxymethyl cellulose, and carbon nanotubes are uniformly dispersed in water at a mass ratio of 50:1.5:6 to prepare a slurry, and spray-dried at 150° C. to obtain spherical and / or quasi-spherical silicon-carbon composite particles with a D50 of 1.5 μm;

[0056] (2) TAPB (1,3,5-tris(4-aminophenyl)benzene), PDA (terephthalaldehyde), and BTCA (tris-benzene trimethylene aldehyde) were mixed and stirred in a mixed solution of aniline and benzaldehyde for 4 minutes for prepolymerization. The concentration of amino groups in TAPB and the concentration of aldehyde groups in BTCA and PDA in the mixture were maintained at 20 mmol / L. The concentration of amino groups and aldehyde groups in the mixed solution of aniline and benzaldehyde was 100 mmol / L. The molar ratio of PDA and BTCA was 1:2. The silicon-carbon composite particles obtained in step (1) were then added to the above mixed solution. The solid-liquid ratio of silicon-carbon composite particles to reactants was 0.05 g / mL. The mixture was stirred at a speed of 1000 rpm during the reaction and reacted at 25°C for 30 hours, so that the surface reactants and the core of the silicon-carbon negative electrode presented a core-cage structure. The coating layer thickness was 80 nm. The reaction solution was then filtered, washed, and dried to obtain a precursor.

[0057] (3) reacting the precursor at 650° C. for 60 min to carbonize part of the COF cage at high temperature for a short time to obtain the silicon-carbon negative electrode material.

[0058] Example 3

[0059] This embodiment provides a silicon-carbon negative electrode material. The synthesis schematic diagram of the silicon-carbon material is shown in FIG1 . The preparation method of the silicon-carbon negative electrode material is as follows:

[0060] (1) Nano-silicon particles with a D50 of 100 nm, carboxymethyl cellulose, and carbon nanotubes are uniformly dispersed in water at a mass ratio of 50:0.8:4 to prepare a slurry, and spray-dried at 100° C. to obtain spherical and / or quasi-spherical silicon-carbon composite particles with a D50 of 0.5 μm;

[0061] (2) TAPB (1,3,5-tris(4-aminophenyl)benzene), PDA (terephthalaldehyde), and BTCA (tris-benzene trimethylene aldehyde) were mixed and stirred in a mixed solution of aniline and benzaldehyde for 5 minutes for prepolymerization. The concentration of amino groups in TAPB and the concentration of aldehyde groups in BTCA and PDA in the mixture were maintained at 40 mmol / L. The concentration of amino groups and aldehyde groups in the mixed solution of aniline and benzaldehyde was 150 mmol / L. The molar ratio of PDA and BTCA was 2:2. The silicon-carbon composite particles obtained in step (1) were then added to the above mixed solution. The solid-liquid ratio of silicon-carbon composite particles to reactants was 0.01 g / mL. The reaction was stirred at a speed of 100 rpm and reacted at 25°C for 80 hours, so that the surface reactants and the core of the silicon-carbon negative electrode presented a core-cage structure. The coating layer thickness was 20 nm. The reaction solution was then filtered, washed, and dried to obtain a precursor.

[0062] (3) The precursor is reacted at 800° C. for 30 min to carbonize part of the COF cage at high temperature for a short time to obtain the silicon-carbon negative electrode material.

[0063] Example 4

[0064] The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of the silicon-carbon composite particles and the reactants obtained by prepolymerization is 0.005 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0065] Example 5

[0066] The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of the silicon-carbon composite particles and the reactants obtained by prepolymerization is 0.1 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0067] Example 6

[0068] The only difference between this embodiment and embodiment 1 is that the molar ratio of terephthalaldehyde to trimesic acid is 3:1, and other conditions and parameters are exactly the same as those in embodiment 1.

[0069] Example 7

[0070] The only difference between this embodiment and embodiment 1 is that the molar ratio of terephthalaldehyde to trimesaldehyde is 1:3, and other conditions and parameters are exactly the same as those in embodiment 1.

[0071] Example 8

[0072] The only difference between this embodiment and embodiment 1 is that the reaction time of step (2) is 10 h, and the other conditions and parameters are exactly the same as those of embodiment 1.

[0073] Example 9

[0074] The only difference between this embodiment and embodiment 1 is that the time for high-temperature carbonization treatment in step (3) is 2 hours, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0075] Comparative Example 1

[0076] In this comparative example, the silicon-carbon composite particles were prepared directly using step (1) without performing steps (2) and (3).

[0077] Comparative Example 2

[0078] The only difference between this comparative example and Example 1 is that the high-temperature carbonization treatment in step (3) is not performed, and the other conditions and parameters are exactly the same as those in Example 1.

[0079] Performance testing:

[0080] The silicon-carbon negative electrode materials prepared in the above examples and comparative examples were uniformly mixed with acetylene black and polyacrylic acid at a mass ratio of 80:10:10, ground for 30 minutes, and then evenly coated onto copper foil. The mixture was vacuum-dried at 90°C and roller-pressed to produce a negative electrode sheet. A button-type battery was prepared using a lithium metal sheet as the counter electrode, a polypropylene film as the separator, and 1M lithium hexafluorophosphate as the electrolyte.

[0081] The test conditions are: test temperature is 25℃, 0.1C charge-discharge cycle performance test and 2C rate performance test are carried out in the voltage range of 0.05V-2V. The test results are shown in Table 1:

[0082] Table 1

[0083] As can be seen from Table 1, from Examples 1-3, the 0.1C discharge capacity of the battery made of the silicon-carbon negative electrode material described in this application can reach more than 2324.65 mAh / g, the 100 cycle capacity retention rate can reach more than 97.98%, and the 2C / 0.1C capacity retention rate can reach more than 53.87%.

[0084] By comparing Example 1 with Examples 4-5, it can be seen that in the preparation process of the silicon-carbon negative electrode material described in the present application, the solid-liquid ratio of the silicon-carbon composite particles and the reactants obtained by prepolymerization will affect its performance. The solid-liquid ratio of the silicon-carbon composite particles and the reactants obtained by prepolymerization is controlled at 0.01 to 0.05 g / mL, and the silicon-carbon negative electrode material obtained has better performance. If the solid-liquid ratio is too large, the COF outer layer formed is too thin and the material strength is low. If the solid-liquid ratio is too small, the COF outer layer formed by the reaction is too thick, which affects the material capacity.

[0085] By comparing Example 1 and Examples 6-7, it can be seen that in the preparation process of the silicon-carbon negative electrode material described in the present application, the molar ratio of terephthalaldehyde and trimesic acid will affect its performance. The molar ratio of terephthalaldehyde and trimesic acid is controlled at (1-3):2, and the silicon-carbon negative electrode material with better performance is obtained. If the proportion of terephthalaldehyde is too large, a hollow core-cage structure cannot be formed, and the silicon-carbon negative electrode cannot be given sufficient volume expansion space, which affects the stability of the material. If the proportion of terephthalaldehyde is too small, the cage layer formed is too thin, there are too many pores, the strength is low, and it is easy to break during the reaction process.

[0086] From the comparison between Example 1 and Example 8, it can be seen that the reaction time of step (2) will affect the performance of the prepared silicon-carbon negative electrode material. If the reaction time is too short, the cage structure cannot be generated and only a general coating layer is formed, which cannot provide sufficient volume expansion space for the silicon-carbon negative electrode, affecting the stability of the material.

[0087] By comparing Example 1 and Example 9, it can be seen that the high-temperature carbonization time in step (3) will affect the performance of the silicon-carbon negative electrode material. If the high-temperature carbonization time is too long, the cage layer formed will be too thin, have too many pores, have low strength, and be easily broken during the reaction process.

[0088] By comparison of Example 1 and Comparative Example 1, it can be seen that the present application uses 1,3,5-tris(4-aminophenyl)benzene (TAPB), terephthalaldehyde (PDA) and trimesic acid (BTCA) as raw materials to polymerize into COF cages. The COF cages can have high thermal stability and can stably exist in a lithium ion electrolyte environment. The pore structure of the generated COF provides a large surface area, which is conducive to the diffusion of electrolyte and lithium ions to the silicon-carbon core, thereby improving the initial efficiency and rate performance of the material. The COF cage can place elemental silicon in a "cage", providing sufficient buffer space to adapt to the volume effect of elemental silicon. The overall volume of the resulting Si / C@COF negative electrode material remains essentially unchanged during the charge and discharge process. Therefore, it is possible to fully utilize the specific capacity of the silicon negative electrode while ensuring the cyclic stability of the material.

[0089] Comparison of Example 1 and Comparative Example 2 demonstrates that the present invention further enhances the conductivity of the negative electrode material by simply carbonizing a portion of the COF cage at high temperature. Furthermore, the COF material exhibits excellent thermal stability, and even short heat treatments do not cause structural collapse. Furthermore, the presence of abundant amino groups on the surface of the synthesized COF material increases the material's electron density and conductivity, while also providing lithium insertion sites and improving the material's discharge capacity.

[0090] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A method for preparing a silicon-carbon negative electrode material, comprising the following steps: (1) mixing a silicon source, a carbon source and a binder with a solvent, and spray drying to obtain silicon-carbon composite particles; (2) prepolymerizing 1,3,5-tri(4-aminophenyl)benzene, terephthalaldehyde and trimesic acid aldehyde, and mixing the mixture with the silicon-carbon composite particles obtained in step (1) to obtain a precursor; (3) Carrying out high-temperature carbonization treatment on the precursor to obtain the silicon-carbon negative electrode material.

2. The preparation method according to claim 1, wherein The silicon source in step (1) includes nano-silicon particles.

3. The preparation method according to claim 1 or 2, wherein: The median particle size D50 of the silicon source is 100-500 nm.

4. The preparation method according to any one of claims 1 to 3, wherein The carbon source includes any one of an organic carbon source, carbon nanotubes, carbon nanofibers or graphene, or a combination of at least two of them.

5. The preparation method according to any one of claims 1 to 4, wherein: The binder includes any one of melamine formaldehyde resin, carboxymethyl cellulose, polyethylene oxide or polyvinyl alcohol, or a combination of at least two of them.

6. The preparation method according to any one of claims 1 to 5, wherein: The solvent includes a combination of at least two of any one of water, methanol or ethanol.

7. The preparation method according to claims 1-6, wherein: The mass ratio of the silicon source, the carbon source and the binder in step (1) is 50:(4-6):(0.8-1.5); Optionally, the spray drying temperature is 100 to 200°C; Optionally, the median particle size D50 of the silicon-carbon composite particles is 0.5-1.5 μm.

8. The preparation method according to any one of claims 1 to 7, wherein: The prepolymerization in step (2) comprises stirring 1,3,5-tris(4-aminophenyl)benzene, terephthalaldehyde and trimesic acid in a mixed solution of aniline and benzaldehyde; Optionally, the stirring time is 3 to 5 minutes; Optionally, during the prepolymerization process, the concentration of the amino group of 1,3,5-tris(4-aminophenyl)benzene in the system is 20 to 40 mmol / L; Optionally, during the prepolymerization process, the total concentration of aldehyde groups in terephthalaldehyde and trimesic acid in the system is 20 to 40 mmol / L; Optionally, during the prepolymerization process, the total concentration of amino groups in aniline and aldehyde groups in benzaldehyde in the system is 100-150 mmol / L; Optionally, the molar ratio of terephthalaldehyde to trimesaldehyde is (1-3):

2.

9. The preparation method according to any one of claims 1 to 8, wherein: The solid-to-liquid ratio of the silicon-carbon composite particles and the prepolymerized reactants in step (2) is 0.01 to 0.05 g / mL; Optionally, stirring is performed during the mixing process; Optionally, the stirring speed is 100-1500 rpm.

10. The preparation method according to any one of claims 1 to 9, wherein: The reaction temperature in step (2) is 20-40°C; Optionally, the reaction time is 30 to 80 hours.

11. The preparation method according to any one of claims 1 to 10, wherein: The precursor includes a coating layer; Optionally, the coating layer has a thickness of 10 to 100 nm.

12. The preparation method according to any one of claims 1 to 11, wherein: The temperature of the high temperature carbonization treatment in step (3) is 650-800°C; Optionally, the high temperature carbonization treatment time is 0.5 to 1 hour.

13. A silicon-carbon negative electrode material, wherein: The silicon-carbon negative electrode material is prepared by the method according to any one of claims 1 to 12.

14. A negative electrode sheet, wherein: The negative electrode plate comprises the silicon-carbon negative electrode material as claimed in claim 13.

15. A lithium ion battery, wherein: The lithium-ion battery comprises the negative electrode sheet as claimed in claim 14.

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