Preparation method of carbon-silicon negative electrode material and application of carbon-silicon negative electrode material in lithium ion battery
By coating the silicon surface with polybenzoxazine resin and silicon dioxide grids to form a grid carbon layer, the problems of volume expansion and poor conductivity of silicon-based anode materials are solved, thus improving the electrochemical performance of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-01-16
- Publication Date
- 2026-05-01
AI Technical Summary
Silicon-based anode materials suffer from reduced electrode performance due to volume expansion and poor conductivity, which limits their application in lithium-ion batteries.
By coating a silicon surface with polybenzoxazine resin to form a grid carbon layer, combined with a silicon dioxide fence structure, a continuous conductive network is formed to alleviate volume expansion and improve electron transport efficiency.
It significantly improves the electrochemical performance of silicon-based anode materials, enhances cycle stability and rate performance, and achieves high specific capacity and long lifetime.
Smart Images
Figure CN121964583A_ABST
Abstract
Description
A method for preparing a carbon-silicon anode material and its application in lithium-ion batteries Technical Field
[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a method for preparing a carbon-silicon anode material and its application in lithium-ion batteries. Background Technology
[0002] With the rapid development of electric vehicles and mobile electronic devices, lithium-ion batteries must have higher energy densities. However, traditional graphite-based anode materials are limited by their low theoretical capacity, making it difficult to meet the energy storage requirements of high-performance lithium-ion batteries, thus restricting further improvements in overall battery performance. Silicon-based anode materials, due to their high theoretical capacity (Li... 22 The Si5 alloy has a corresponding capacity of 4200 mAh / g, which is significantly better than commercial graphite anodes; at the same time, its lithiation potential is low (approximately 0.4 V vs. Li / Li). + Silicon, while meeting the requirement of high battery operating voltage, can also prevent lithium dendrite formation, resulting in higher safety, and is therefore considered an ideal anode material for next-generation high-energy-density lithium-ion batteries. However, as a semiconductor material, silicon has a relatively low intrinsic conductivity (approximately 6.7 × 10⁻⁻⁴). 4 The rate capability of silicon anodes is limited by their capacity (S / cm). Furthermore, during charge and discharge, silicon undergoes intense alloying / dealloying reactions, leading to severe volume changes (up to 300%), resulting in particle fragmentation, electrode surface cracking, and repeated SEI film growth. This, in turn, causes rapid capacity decay and shortened cycle life. These two critical issues severely restrict the development of silicon-based anodes in commercial applications.
[0003] To address the severe volume expansion and poor conductivity issues of silicon-based anode materials in lithium-ion batteries, researchers have proposed various improvement strategies, primarily including material nanostructuring, silicon-carbon composites, binder optimization, and electrolyte composition design. Among these, the structural design of silicon-carbon composite materials has received widespread attention. The earliest core-shell structure buffered volume expansion by directly coating the silicon surface with a carbon layer; however, the carbon layer's effectiveness was limited, and it was prone to cracking during repeated charge-discharge cycles, leading to exposed silicon and decreased cycle performance. The subsequently proposed yolk-shell structure, a hollow design, effectively accommodated silicon volume changes and suppressed expansion. However, due to the limited contact points between silicon and the carbon layer, the material's conductivity was insufficient, affecting rate performance. Summary of the Invention
[0004] To address the problems existing in the prior art, the present invention aims to provide a method for preparing a carbon-silicon anode material and its application in lithium-ion batteries. This grid-like carbon layer provides ample space to mitigate volume expansion and forms a continuous conductive network, thereby improving ion / electron transport efficiency and comprehensively enhancing electrochemical performance.
[0005] To achieve the above objectives, the present invention provides the following technical solutions: In the first aspect, the present invention provides a method for preparing a carbon-silicon anode material, comprising the following steps: (1) Preparation of silicon surface coated polybenzoxazine resin material: nano-silicon, alkane-based amine compound, phenolic compound, formaldehyde and ammonia are mixed evenly, and after reaction, the mixture is heated and aged to obtain silicon surface coated polybenzoxazine resin material; (2) Preparation of silicon dioxide and polybenzoxazine layered coated silicon material precursor: the material obtained in step (1) is dispersed in ammonia ethanol solution. Then, a cationic surfactant was added, and after stirring evenly, tetraethyl orthosilicate was injected. After the reaction, a silicon dioxide and polybenzoxazine layered coated silicon material precursor was obtained; (3) confined pyrolysis: the precursor powder obtained in step (2) was placed in a tube furnace for carbonization and naturally cooled to room temperature in an argon atmosphere; (4) alkaline etching: the sample obtained in step (3) was immersed in an etching solution to wash away the outer layer of silicon dioxide and obtain a carbon silicon anode material; the thickness of the polybenzoxazine resin in the silicon surface coated polybenzoxazine resin material is ≥40 nm. The thickness of the polybenzoxazine resin ≥40 nm will form a grid carbon structure in the subsequent confined pyrolysis.
[0006] In step (1), the mass ratio of the nano-silicon, the alkane-amine compound, and the phenolic compound is 3-10:2-4:1-2; the molar ratio of formaldehyde to ammonia is 0.1-2. Further, the diameter of the nano-silicon is 100-200 nm, the mass ratio of the nano-silicon, the alkane-amine compound, and the phenolic compound is 5:2-4:1-2; and the molar ratio of formaldehyde to ammonia is 0.3-1.
[0007] In step (1), the alkylamine type compound includes short-chain polyamine compounds and / or monoamine type compounds; the phenol type compound includes polyphenol compounds and / or monophenol compounds with a molecular weight of 100-300 g / mol. Further, the short-chain polyamine compound includes one or more of ethylenediamine, propylenediamine, and 1,6-hexanediamine; the monoamine type compound includes ethylamine and / or propylamine; the polyphenol compound includes resorcinol and / or catechol; and the monophenol compound includes phenol and / or eugenol.
[0008] In step (1), the reaction temperature is 10-50 ℃ and the reaction time is 10-120 min; the aging temperature is 60-120 ℃ and the aging time is 4-24 h.
[0009] In step (2), the mass ratio of nano-silicon, tetraethyl orthosilicate, and cationic surfactant is 1.2:1-4:1-4.
[0010] In step (2), the stirring temperature and the reaction temperature are both 10-60 ℃, and the reaction time is 4-36 h.
[0011] In step (3), the carbonization temperature is 600-1000 ℃ and the carbonization time is 1-6 h. The temperature is increased from room temperature to 600-1000 ℃ in an argon atmosphere at a rate of 1-10 ℃ / min.
[0012] In step (4), the etching temperature is 30-80 ℃, the etching time is 4-36 h, and the etching solution is one or more of hydrofluoric acid, sodium hydroxide and potassium hydroxide solution.
[0013] Secondly, the present invention provides the application of the carbon-silicon anode material in lithium-ion batteries, wherein the carbon-silicon anode material serves as the anode material of lithium-ion batteries.
[0014] Compared with existing technologies, this invention has at least the following beneficial effects: This invention utilizes hydrogen bonding to in-situ coat a polybenzoxazine layer of a certain thickness onto the silicon surface, followed by an outer layer of silica barrier. During confined pyrolysis, small molecule gases can activate the polymer carbon layer internally, forming a mesh carbon-coated nano-silicon structure. The porous nature of this mesh carbon layer provides an effective buffer space for the significant volume expansion of silicon during lithium intercalation, while the three-dimensional conductive network enhances the material's electronic conductivity. This structural design simultaneously improves the material's mechanical stability and ion / electron transport kinetics, thereby significantly improving its electrochemical performance.
[0015] The carbon-silicon anode material obtained by this invention, as an anode material for lithium-ion batteries, can maintain a specific capacity of 1000 mAh / g after 200 cycles at a current density of 0.5 A / g, and achieve a specific capacity of 480 mAh / g at a current density of 5 A / g, with an initial coulombic efficiency of 85%. Compared with existing silicon-based anode materials, its comprehensive electrochemical performance is greatly improved. Attached Figure Description
[0016] Figure 1 shows the XRD pattern of the silicon-carbon anode composite material prepared in Example 1 of this invention.
[0017] Figure 2 shows the Raman spectra of the original silicon material in Example 1 and Comparative Example 1 of the present invention.
[0018] Figure 3 is a scanning electron microscope image of the silicon-carbon anode composite material prepared in Example 1 of the present invention.
[0019] Figure 4 is a transmission electron microscope image of the silicon-carbon anode composite material prepared in Example 1 of the present invention.
[0020] Figure 5 shows a transmission electron microscope image of the silicon-carbon anode composite material prepared in Comparative Example 1.
[0021] Figure 6 shows a transmission electron microscope image of the silicon-carbon anode composite material prepared in Comparative Example 2.
[0022] Figure 7 shows the cycling performance of the silicon-carbon anode composite material prepared in Example 1 and Comparative Example 1 of the present invention and the original silicon sample at a current density of 0.5 A / g.
[0023] Figure 8 shows the rate performance of the silicon-carbon anode composite material prepared in Example 1 and Comparative Example 1 of the present invention and the original silicon sample at different current densities. Detailed Implementation
[0024] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.
[0025] Example 1 A method for preparing a carbon silicon anode material, comprising the following steps: (1) Preparation of polybenzoxazine resin material coated on silicon surface: Silicon with a diameter of 200 nm is dispersed in deionized water, and then resorcinol, 1,6-hexanediamine and 800 uL of ammonia solution are added sequentially under stirring at 25 °C. Then, 25 mL of dilute formaldehyde solution with a concentration of 0.065 mol / L is slowly added dropwise. The mass ratio of nano-silicon, resorcinol and 1,6-hexanediamine is 5:3.5:1, and the molar ratio of ammonia and formaldehyde is 0.7. After reacting for 30 min, the temperature was raised to 80 °C and aged for 4 h to obtain silicon surface coated polybenzoxazine resin material; (2) Preparation of silicon dioxide and polybenzoxazine layered coated silicon material precursor: The material obtained in step (1) was dispersed in 120 mL ammonia ethanol solution, the system temperature was maintained at 30 °C, and stirred for 10 min. Then 5 mL hexadecyltrimethylammonium bromide aqueous solution was added, stirred for 30 min, and finally 193 μL tetraethyl orthosilicate was added. The reaction was carried out at 30 °C for 16 h to obtain silicon dioxide polybenzoxazine layered coated silicon material precursor; (3) Confined pyrolysis: The precursor powder obtained in step (2) was placed in a tube furnace and heated from room temperature to 1000 °C at 5 °C / min in an argon atmosphere and held for 2 h. h, after being cooled naturally to room temperature under an argon atmosphere, silicon dioxide grid carbon layered coated silicon-based anode material is obtained; (4) Alkali etching: take the sample obtained in step (3) and immerse it in sodium hydroxide solution for 12 h at an immersion temperature of 50 ℃ to wash away the outer layer of silicon dioxide and obtain carbon silicon anode material.
[0026] Example 2: A method for preparing a carbon-silicon anode material, comprising the following steps: (1) Preparation of polybenzoxazine resin material coated on silicon surface: Silicon with a diameter of 200 nm is dispersed in deionized water, and then resorcinol, 1,6-hexanediamine, and 800 uL of ammonia solution are added sequentially under stirring at 25 °C, followed by slow dropwise addition of 25 mL of dilute formaldehyde solution with a concentration of 0.065 mol / L. The mass ratio of nano-silicon, resorcinol, and 1,6-hexanediamine is 5:3.5:1, and the molar ratio of ammonia to formaldehyde is 0.7. After reacting for 30 min, the temperature was raised to 80 °C and aged for 4 h to obtain silicon surface coated polybenzoxazine resin material; (2) Preparation of silicon dioxide and polybenzoxazine layered coated silicon material precursor: The material obtained in step (1) was dispersed in 120 mL ammonia ethanol solution, the system temperature was maintained at 30 °C, stirred for 10 min, then 5 mL hexadecyltrimethylammonium bromide aqueous solution was added, stirred for 30 min, and finally 193 μL tetraethyl orthosilicate was added, and reacted at 30 °C for 16 h to obtain silicon dioxide polybenzoxazine layered coated silicon material precursor; (3) Confined pyrolysis: The precursor powder obtained in step (2) was placed in a tube furnace, heated from room temperature to 800 °C at 5 °C / min in an argon atmosphere and kept at 2 h, and then cooled naturally to room temperature in an argon atmosphere to obtain silicon dioxide grid carbon layered coated silicon-based anode material; (4) Alkali etching: The sample obtained in step (3) was immersed in sodium hydroxide solution for 12 The outer layer of silicon dioxide was washed away by soaking at 50 °C to obtain a carbon-silicon anode material.
[0027] Example 3: A method for preparing a carbon-silicon anode material, comprising the following steps: (1) Preparation of polybenzoxazine resin material coated on silicon surface: Silicon with a diameter of 200 nm is dispersed in deionized water, and then resorcinol, 1,6-hexanediamine, and 800 μL of ammonia solution are added sequentially under stirring at 25 °C, followed by slow dropwise addition of 25 mL of dilute formaldehyde solution with a concentration of 0.065 mol / L. The mass ratio of nano-silicon, resorcinol, and 1,6-hexanediamine is 5:3.5:1, and the molar ratio of ammonia to formaldehyde is 0.7. After reacting for 30 min, the temperature was raised to 80 °C and aged for 4 h to obtain silicon surface coated polybenzoxazine resin material; (2) Preparation of silicon dioxide and polybenzoxazine layered coated silicon material precursor: The material obtained in step (1) was dispersed in 120 mL ammonia ethanol solution, the system temperature was maintained at 30 °C, stirred for 10 min, then 5 mL hexadecyltrimethylammonium bromide aqueous solution was added, stirred for 30 min, and finally 193 μL tetraethyl orthosilicate was added, and reacted at 30 °C for 16 h to obtain silicon dioxide polybenzoxazine layered coated silicon material precursor; (3) Confined pyrolysis: The precursor powder obtained in step (2) was placed in a tube furnace, heated from room temperature to 600 °C at 5 °C / min in an argon atmosphere and kept at 2 h, and then cooled naturally to room temperature in an argon atmosphere to obtain silicon dioxide grid carbon layered coated silicon-based anode material; (4) Alkali etching: The sample obtained in step (3) was immersed in sodium hydroxide solution for 12 The outer layer of silicon dioxide was washed away by soaking at 50 °C to obtain a carbon-silicon anode material.
[0028] The difference between Comparative Example 1 and Example 1 is that the silicon surface coated with polybenzoxazine resin material is used as a carbon precursor, without involving silicon dioxide coating and alkaline etching processes, and includes the following steps: (1) Preparation of silicon surface coated with polybenzoxazine resin material: Silicon with a diameter of 200 nm is dispersed in deionized water, and then resorcinol, 1,6-hexanediamine, and 800 uL of ammonia solution are added sequentially under stirring at 25 ℃, followed by slow dropwise addition of 25 mL of dilute formaldehyde solution with a concentration of 0.065 mol / L. Among them, the mass ratio of nano-silicon, resorcinol, and 1,6-hexanediamine is 5:3.5:1, and the molar ratio of ammonia and formaldehyde is 0.7. After reacting for 30 min, continue stirring and heating to 80 ℃ for 4 h to obtain silicon surface coated polybenzoxazine resin material; (2) carbonization pyrolysis: place the precursor powder obtained in step (2) in a tube furnace, heat it from room temperature to 1000 ℃ at 5 ℃ / min in an argon atmosphere and keep it at that temperature for 2 h, and then cool it naturally to room temperature in an argon atmosphere to obtain silicon carbon anode material.
[0029] The difference between Comparative Example 2 and Example 1 is that when the nano-silicon surface is coated with polybenzoxazine resin material, except that the mass of nano-silicon remains unchanged, the amount of other raw materials resorcinol, 1,6-hexanediamine and dilute formaldehyde is half that of Example 1, including the following steps: (1) Preparation of polybenzoxazine resin material coated on silicon surface: Silicon with a diameter of 200 nm is dispersed in deionized water, and then resorcinol, 1,6-hexanediamine and 800 uL of ammonia solution are added in sequence under stirring at 25 ℃, and then 12.5 mL of dilute formaldehyde solution with a concentration of 0.065 mol / L is slowly added dropwise. Among them, the mass ratio of nano-silicon, resorcinol and 1,6-hexanediamine is 5:1.75:0.5, and the molar ratio of ammonia and formaldehyde is 1.4. After reacting for 30 min, the temperature was raised to 80 °C and aged for 4 h to obtain silicon surface coated polybenzoxazine resin material; (2) Preparation of silicon dioxide and polybenzoxazine layered coated silicon material: The material obtained in step (1) was dispersed in 120 mL ammonia ethanol solution, the system temperature was maintained at 30 °C, stirred for 10 min, then 5 mL hexadecyltrimethylammonium bromide aqueous solution was added, stirred for 30 min, and finally 193 μL tetraethyl orthosilicate was added, and reacted at 30 °C for 16 h to obtain silicon dioxide polybenzoxazine layered coated silicon material precursor; (3) Confined pyrolysis: The precursor powder obtained in step (2) was placed in a tube furnace, heated from room temperature to 1000 °C at 5 °C / min in an argon atmosphere and kept at 2 h, and then cooled naturally to room temperature in an argon atmosphere to obtain silicon dioxide grid carbon layered coated silicon-based anode material; (4) Alkali etching: The sample obtained in step (3) was immersed in sodium hydroxide solution for 12 The outer layer of silicon dioxide was washed away by soaking at 50 °C to obtain silicon-carbon anode material.
[0030] The silicon-carbon anode materials obtained in the above embodiments and comparative examples were analyzed. The XRD diffraction patterns in Figure 1 show the crystal structure information of Example 1, Comparative Example 1, and the original silicon material. In addition to the silicon diffraction peaks, the materials of Example 1 and Comparative Example 1 also exhibit carbon diffraction peaks at approximately 22°. Furthermore, Raman spectroscopy characterization was performed on all three materials. As shown in Figure 2, the samples of Example 1 and Comparative Example 1 show peaks at approximately 510 cm⁻¹. −1 The peak at 1350 cm⁻¹ is a characteristic peak for nano-silicon, indicating that silicon nanoparticles have been encapsulated in the composite material. −1 and 1590 cm −1 The nearby characteristic peaks correspond to the carbon D band and graphite G band of carbon materials, respectively, and correspond to the vibrational characteristics of disordered carbon atoms and sp² hybridized carbon atoms, respectively. Among them, the I band of Example 1... D / I GThe ratio is slightly higher than that of Comparative Example 1, indicating lower orderliness of its carbon components and more defects in the grid carbon layer produced by confined pyrolysis. Figures 3 and 4 are SEM and TEM images of Example 1, respectively. The silicon particles are tightly wrapped by the carbon layer, with relatively aggregated particles, and the silicon is distributed inside the grid carbon layer, with a carbon layer thickness of approximately 40 nm. Figure 5 is a TEM image of Comparative Example 1, with a carbon layer thickness of approximately 30 nm. Figure 6 is a TEM image of Comparative Example 2, with a carbon layer thickness of approximately 25 nm. The comparison shows that the silica barrier on the outer layer of polybenzoxazine can promote the formation of a grid carbon structure in the polymer during pyrolysis. However, if the outer layer is too thin, the small molecule gases inside will escape rapidly during confined pyrolysis, failing to continuously act on the polymer interior for activation, and making it difficult to form a grid carbon structure. This study confirms that a grid carbon structure can only be effectively formed when the outer layer thickness of polybenzoxazine is ≥40 nm.
[0031] In specific embodiments of the present invention, Example 1, Comparative Example 1, and the original nano-silicon material were assembled into button half-cells, and their electrochemical performance was tested. For electrode fabrication, active material, conductive carbon black (SP), and binder were mixed in an 8:1:1 ratio to form an electrode, wherein the binder was 3 wt% of a CMC+SBR aqueous binder (where CMC:SBR=6:4). For the electrolyte, 1.0 M lithium hexafluorophosphate (LiPF6) was dissolved in a 1:1 volume ratio mixture of ethylene carbonate (EC) and diethyl carbonate (DEC), with 5 wt% of fluoroethylene carbonate (FEC) added. The battery assembly process was carried out in an argon-filled glove box to ensure the stability and consistency of the assembly environment. Finally, the charge-discharge experiments of the lithium-ion battery were conducted on the Xinwei Battery Testing System to ensure the accuracy and reliability of the test results. The electrochemical performance of the silicon-carbon anode composite material and the original silicon sample prepared in Example 1 and Comparative Example 1 of this invention is shown in Table 1. The cycle performance and rate performance results are shown in Figures 7 and 8.
[0032] As shown in Table 1, Figure 7, and Figure 8, the silicon-carbon anode material of this invention has a specific capacity of ~2223 mAh / g, an initial coulombic efficiency of ~85%, and a specific capacity of approximately 1000 mAh / g after 200 cycles at a current density of 0.5 A / g, reaching 480 mAh / g at a current density of 5 A / g. In contrast, the silicon-carbon anode composite material prepared in Comparative Example 1, while exhibiting an initial coulombic efficiency as high as 89%, only had a specific capacity of 277 mAh / g after 70 cycles at a current density of 0.5 A / g, approaching 0 mAh / g at a current density of 1 A / g. The original silicon sample had an initial coulombic efficiency of only 77%, and a specific capacity of only 589 mAh / g after 70 cycles at a current density of 0.5 A / g, approaching 0 mAh / g at a current density of 5 A / g. The excellent cycle and rate performance of the silicon-carbon anode composite material of the present invention is due to the grid carbon coating layer formed by polymer confined pyrolysis. This layer not only improves the conductivity of the material, but also provides a buffer space for the huge volume expansion during silicon lithium intercalation, thereby achieving high capacity and cycle stability.
[0033] Table 1. Comparison of electrochemical performance of silicon-carbon anode composite materials prepared in Example 1 and the comparative example of the present invention with that of the original silicon sample. The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be included within the scope of protection of the invention.
Claims
1. A method for preparing a carbon-silicon anode material, characterized in that: Includes the following steps: (1) Preparation of silicon surface coated polybenzoxazine resin material: nano silicon, alkane-based amine compound, phenolic compound, formaldehyde and ammonia are mixed evenly, and aged at high temperature after reaction to obtain silicon surface coated polybenzoxazine resin material; (2) Preparation of silicon material precursor with silicon dioxide and polybenzoxazine layer coating: the material obtained in step (1) is dispersed in ammonia ethanol solution, then cationic surfactant is added, stirred evenly and then tetraethyl orthosilicate is injected, and silicon dioxide and polybenzoxazine layer coating silicon material precursor is obtained after reaction; (3) confined pyrolysis: the precursor powder obtained in step (2) is placed in a tube furnace for carbonization and naturally cooled to room temperature in argon atmosphere; (4) alkaline etching: the sample obtained in step (3) is immersed in etching solution to wash away the outer silicon dioxide to obtain carbon silicon anode material; the thickness of polybenzoxazine resin in the silicon surface coated polybenzoxazine resin material is ≥40 nm.
2. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (1), the mass ratio of the nano-silicon, alkane-based amine compound and phenolic compound is 3-10:2-4:1-2; the molar ratio of formaldehyde and ammonia is 0.1-2.
3. The method for preparing a carbon-silicon anode material as described in claim 2, characterized in that: In step (1), the mass ratio of the nano-silicon, the alkane-based amine compound, and the phenolic compound is 5:2-4:1-2; the molar ratio of formaldehyde and ammonia is 0.3-1; and the diameter of the nano-silicon is 100-200 nm.
4. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (1), the alkane-amine type compound includes short-chain polyamine compounds and / or monoamine type compounds; the phenol type compound includes polyphenol compounds and / or monophenol compounds with a molecular weight of 100-300 g / mol.
5. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (1), the reaction temperature is 10-50 ℃ and the reaction time is 10-120 min; the aging temperature is 60-120 ℃ and the aging time is 4-24 h.
6. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (2), the mass ratio of nano-silicon, tetraethyl orthosilicate and cationic surfactant is 1.2:1-4:1-4.
7. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (2), the stirring temperature and reaction temperature are 10-60 ℃, and the reaction time is 4-36 h.
8. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (3), the carbonization temperature is 600-1000 ℃ and the carbonization time is 1-6 h.
9. The method for preparing a carbon-silicon anode material as described in claim 1, characterized in that: In step (4), the etching temperature is 30-80 ℃, the etching time is 4-36 h, and the etching solution is one or more of hydrofluoric acid, sodium hydroxide and potassium hydroxide solution.
10. The application of the carbon-silicon anode material obtained by the method of claim 1 in a lithium-ion battery, characterized in that: The carbon-silicon anode material is used as the anode material for lithium-ion batteries.