Silicon-carbon negative electrode material for lithium battery and preparation method thereof
By combining carbon nanotubes and graphene oxide with silicon powder to form a three-dimensional network structure, and combining sodium alginate and polyacrylamide, the problem of pulverization caused by volume changes during the charging and discharging process of silicon-carbon anode materials is solved, thereby improving the cycle stability and specific capacity of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CYG NEW ENERGY MATERIAL RESEARCH INSTITUTE (GUANGDONG) CO LTD
- Filing Date
- 2025-04-27
- Publication Date
- 2026-05-29
AI Technical Summary
The silicon-carbon anode material in existing lithium-ion batteries is prone to pulverization and failure during charge and discharge due to volume changes, resulting in low cycle life and poor cycle stability. Existing improvement methods have failed to effectively solve the volume expansion problem.
A mixture of carbon nanotubes and graphene oxide is combined with silicon powder and hydrothermally treated and calcined to form a three-dimensional network structure. This is then combined with sodium alginate and polyacrylamide to form a highly elastic and highly conductive silicon-carbon anode material. The stability and conductivity of the material are improved by utilizing electrostatic interactions and network hydrogen bonds.
It significantly improves the cycle stability and specific capacity of lithium-ion batteries, alleviates volume expansion during charging and discharging, enhances the conductivity and electrochemical activity of materials, and extends battery life.
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Figure CN120545351B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery technology, and in particular to a silicon-carbon anode material for lithium batteries and its preparation method. Background Technology
[0002] Lithium-ion batteries have long dominated the consumer, power, and energy storage battery markets due to their extremely high energy density. However, most existing commercial lithium-ion batteries use graphite anodes, with a theoretical specific capacity of only 370 mAh / g, which significantly limits their practical applications.
[0003] Silicon is a promising anode material for lithium-ion batteries, possessing a high theoretical specific capacity (4200 mAh / g). Silicon-carbon electrodes are a novel type of silicon-based lithium-ion battery anode material. Their microstructure is primarily a three-dimensional network formed by silicon-oxygen-carbon tetrahedra. Compared to silicon anodes, their theoretical specific capacity is lower, but still significantly higher than graphite anodes. However, during the charging and discharging process of lithium batteries, the significant volume change caused by the lithiation process makes silicon-carbon anodes prone to pulverization and failure, resulting in low battery cycle life. Currently, suitable binders are typically used to effectively bond silicon particles and conductive fillers, suppressing volume changes during lithiation and maintaining electrode integrity, thereby improving battery cycle life.
[0004] Although the expansion effect of the anode can be reduced by mixing nano-silicon coated with conductive carbon with graphite and controlling the silicon content, the volume expansion is still large, the cycle decay is fast, and the cycle stability is greatly reduced, which limits the improvement of the electrochemical performance of silicon anode and urgently needs to be solved. Summary of the Invention
[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a silicon-carbon anode material for lithium batteries and its preparation method.
[0006] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0007] S1. Add carbon nanotubes to sulfuric acid solution, stir at 30-40℃ for 10-20 min, raise the temperature to 80-90℃, continue stirring for 1-2 h, adjust the pH of the system to 6.5-7, add pretreated graphene oxide and sonicate for 1-2 h, hydrothermal reaction at 180-200℃ for 10-20 h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0008] S2. Mix the pretreated carbon nanotubes, microcrystalline cellulose, and silicon powder evenly, calcine at 300-400℃ for 10-30 minutes under nitrogen protection, cool to room temperature, pulverize, add sodium alginate and polyacrylamide to water and stir for 10-30 minutes, add nano silicon powder and graphite powder and continue stirring for 1-2 hours to obtain a slurry.
[0009] S3. Coat the slurry onto the copper foil, dry it, heat treat it at 90-100℃ for 30-60 minutes, and then cool it to room temperature.
[0010] Preferably, in S1, the mass ratio of carbon nanotubes to pretreated graphene oxide is 1-2:1-2.
[0011] Preferably, in S1, the concentration of the sulfuric acid solution is 10-14 mol / L.
[0012] Preferably, in S1, the carbon nanotubes are multi-walled carbon nanotubes with an inner diameter of 3-5 nm, an outer diameter of 8-15 nm, a length of 3-12 μm, and a specific surface area of 255-280 m². 2 / g.
[0013] Preferably, in S1, the pretreated graphene oxide is prepared by the following specific steps: adding graphene oxide and cationic surfactant to water, ultrasonically treating for 10-30 minutes, and vacuum drying.
[0014] More preferably, the cationic surfactant is hexadecyltrimethylammonium bromide, and the mass ratio of graphene oxide to cationic surfactant is 1-2:0.1-1.
[0015] More preferably, the ultrasonic frequency is 5-12 kHz.
[0016] Preferably, in S2, the particle size of silicon powder is 1-20 μm, the particle size of nano-silicon powder is 50-200 nm, and the mass ratio of pretreated carbon nanotubes, microcrystalline cellulose, silicon powder, sodium alginate, polyacrylamide, nano-silicon powder, and graphite powder is 2-4:1-2:5-10:1-2:0.1-1:1-2:1-2.
[0017] A silicon-carbon anode material for lithium batteries is prepared using the above-mentioned method for preparing silicon-carbon anode materials for lithium batteries.
[0018] A lithium battery, wherein the aforementioned silicon-carbon anode material for lithium batteries is used as the anode.
[0019] Beneficial effects:
[0020] This invention utilizes acid-treated carbon nanotubes to produce abundant active functional groups, while graphene oxide adsorbs cationic surfactants on its surface, giving it a positive charge. These are then mixed with the acid-treated carbon nanotubes, resulting in a highly stable bond due to electrostatic interactions. After hydrothermal treatment, the mixture is calcined with silicon powder in conjunction with microcrystalline cellulose. This results in excellent coating of the silicon powder surface, and the carbonized structure of the microcrystalline cellulose further enhances the three-dimensional network structure, significantly increasing lithium-ion diffusion channels and effectively buffering the volume changes of silicon during charge and discharge. Furthermore, sodium alginate and polyacrylamide are used in conjunction with nano-silicon powder. The internally coated silicon powder and the external nano-silicon powder are bonded together through an organic network, forming a product with high elasticity and high conductivity. This not only significantly alleviates the reduction in contact area caused by silicon volume expansion during charge and discharge cycles, resulting in excellent cycle performance, but also forms a polymer-carbon dot network structure between sodium alginate and polyacrylic acid. This conductive structure improves the material's conductivity and gives the product high specific capacity, electrochemical activity, and stability.
[0021] This invention utilizes sodium alginate, polyacrylamide, and nano-silicon powder to form a strong binding force during heating, resulting in a network of hydrogen bonds within and between molecules. The system has high viscosity, effectively increasing the porosity and tensile properties of the electrode, and can effectively repair electrode damage caused by volume changes during cycling of silicon-carbon anodes, thus greatly improving cycle stability.
[0022] The preparation method of this invention is simple, low-cost, and has a high yield, making it suitable for large-scale application. Attached Figure Description
[0023] Figure 1 This is a comparison chart of the tensile strength and elongation at break of the thin films obtained by coating the slurries obtained in Example 5 and Comparative Examples 1-3.
[0024] Figure 2 This is a comparison chart of the elastic modulus of the silicon-carbon anode materials obtained in Example 5 and Comparative Examples 1-3 in the dry state and in the electrolyte.
[0025] Figure 3 The graph shows a comparison of the initial discharge capacity and capacity retention rate after 100 cycles of silicon-carbon batteries made using the silicon-carbon anode materials obtained in Example 5 and Comparative Examples 1-3.
[0026] Figure 4 This is a comparison chart of the expansion rates of the silicon-carbon anode materials obtained in Example 5 and Comparative Examples 1-3 after 100 charge-discharge cycles. Detailed Implementation
[0027] The present invention will be further explained below with reference to specific embodiments.
[0028] The multi-walled carbon nanotubes used below were purchased from Shenzhen Mouyou New Energy Technology Co., Ltd., with an average inner diameter of 4 nm, an average outer diameter of 12 nm, an average length of 8 μm, and a specific surface area of 267 m². 2 / g. The micron-sized and nano-sized silicon powders used below were purchased from a rare metallurgical and chemical company in Guangzhou. The average particle size of the micron-sized silicon powder was 10μm, and the particle size of the nano-sized silicon powder was 100nm.
[0029] Example 1
[0030] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0031] S1. Add 1g of multi-walled carbon nanotubes to 20g of 10mol / L sulfuric acid solution, stir at 30℃ for 10min at a stirring speed of 500r / min, raise the temperature to 80℃, continue stirring for 1h, adjust the pH of the system to 6.5-7, add 1g of pretreated graphene oxide and sonicate for 1h, transfer to a hydrothermal reactor, hydrothermally react at 180℃ for 10h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0032] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 1g of graphene oxide and 0.1g of hexadecyltrimethylammonium bromide were added to 10g of deionized water, ultrasonically treated for 10min at an ultrasonic frequency of 5kHz, and then vacuum dried.
[0033] S2. Mix 2g of pretreated carbon nanotubes, 1g of microcrystalline cellulose, and 5g of micron-sized silica powder evenly, calcine at 300℃ for 10min under nitrogen protection, cool to room temperature, pulverize, and add 1g of sodium alginate and 0.1g of polyacrylamide to 20g of deionized water. Stir at 1000r / min for 10min, add 1g of nano-silica powder and 1g of graphite powder and continue stirring for 1h to obtain a slurry.
[0034] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 90℃ for 30 minutes, and then cool it to room temperature.
[0035] Example 2
[0036] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0037] S1. Add 2g of multi-walled carbon nanotubes to 40g of 14mol / L sulfuric acid solution, stir at 40℃ for 20min at a stirring speed of 1000r / min, raise the temperature to 90℃ and continue stirring for 2h, adjust the pH of the system to 6.5-7, add 2g of pretreated graphene oxide and sonicate for 2h, transfer to a hydrothermal reactor, hydrothermally react at 200℃ for 20h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0038] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 2g of graphene oxide and 1g of hexadecyltrimethylammonium bromide were added to 20g of deionized water, ultrasonically treated for 30min at an ultrasonic frequency of 12kHz, and then vacuum dried.
[0039] S2. Mix 4g of pretreated carbon nanotubes, 2g of microcrystalline cellulose, and 10g of micronized silica powder evenly, calcine at 400℃ for 30min under nitrogen protection, cool to room temperature, pulverize, add 2g of sodium alginate and 1g of polyacrylamide to 40g of deionized water, stir at 2000r / min for 30min, add 2g of nano-silica powder and 2g of graphite powder and continue stirring for 2h to obtain a slurry;
[0040] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 100℃ for 60 minutes, and then cool it to room temperature.
[0041] Example 3
[0042] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0043] S1. Add 1.2g of multi-walled carbon nanotubes to 35g of 11mol / L sulfuric acid solution, stir at 37℃ for 12min at a stirring speed of 900r / min, raise the temperature to 82℃, continue stirring for 100min, adjust the pH of the system to 6.5-7, add 1.2g of pretreated graphene oxide and sonicate for 100min, transfer to a hydrothermal reactor, hydrothermally react at 185℃ for 18h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0044] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 1.2g of graphene oxide and 0.7g of hexadecyltrimethylammonium bromide were added to 12g of deionized water, ultrasonically treated for 25min at an ultrasonic frequency of 6kHz, and then vacuum dried.
[0045] S2. Mix 3.5g of pretreated carbon nanotubes, 1.2g of microcrystalline cellulose, and 9g of micron-sized silica powder evenly, calcine at 330℃ for 25min under nitrogen protection, cool to room temperature, pulverize, add 1.3g of sodium alginate and 0.7g of polyacrylamide to 25g of deionized water, stir at 1800r / min for 15min, add 1.8g of nano-silica powder and 1.3g of graphite powder and continue stirring for 100min to obtain a slurry;
[0046] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 92℃ for 50 minutes, and then cool it to room temperature.
[0047] Example 4
[0048] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0049] S1. Add 1.8g of multi-walled carbon nanotubes to 25g of 13mol / L sulfuric acid solution, stir at 33℃ for 18min at a stirring speed of 700r / min, raise the temperature to 88℃, continue stirring for 80min, adjust the pH of the system to 6.5-7, add 1.8g of pretreated graphene oxide and sonicate for 80min, transfer to a hydrothermal reactor, hydrothermally react at 195℃ for 12h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0050] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 1.8g of graphene oxide and 0.3g of hexadecyltrimethylammonium bromide were added to 18g of deionized water, ultrasonically treated for 15min at an ultrasonic frequency of 9kHz, and then vacuum dried.
[0051] S2. Mix 2.5g of pretreated carbon nanotubes, 1.8g of microcrystalline cellulose, and 7g of micron-sized silica powder evenly, calcine at 370℃ for 15min under nitrogen protection, cool to room temperature, pulverize, add 1.7g of sodium alginate and 0.3g of polyacrylamide to 35g of deionized water, stir at 1200r / min for 25min, add 1.2g of nano-silica powder and 1.7g of graphite powder and continue stirring for 80min to obtain a slurry;
[0052] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 98℃ for 40 minutes, and then cool it to room temperature.
[0053] Example 5
[0054] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0055] S1. Add 1.5g of multi-walled carbon nanotubes to 30g of 12mol / L sulfuric acid solution, stir at 35℃ for 15min at a stirring speed of 800r / min, raise the temperature to 85℃, continue stirring for 90min, adjust the pH of the system to 6.5-7, add 1.5g of pretreated graphene oxide and sonicate for 90min, transfer to a hydrothermal reactor, hydrothermally react at 190℃ for 15h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0056] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 1.5g of graphene oxide and 0.5g of hexadecyltrimethylammonium bromide were added to 15g of deionized water, ultrasonically treated for 20min at an ultrasonic frequency of 7.5kHz, and then vacuum dried.
[0057] S2. Mix 3g of pretreated carbon nanotubes, 1.5g of microcrystalline cellulose, and 8g of micron-sized silica powder evenly. Calcine at 350℃ for 20min under nitrogen protection, cool to room temperature, pulverize, and add 1.5g of sodium alginate and 0.5g of polyacrylamide to 30g of deionized water. Stir at 1500r / min for 20min. Add 1.5g of nano-silica powder and 1.5g of graphite powder and continue stirring for 90min to obtain a slurry.
[0058] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 95℃ for 45 minutes, and then cool it to room temperature.
[0059] Comparative Example 1
[0060] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0061] S1. Mix 1.5g of multi-walled carbon nanotubes and 1.5g of pretreated graphene oxide evenly to obtain pretreated carbon nanotubes.
[0062] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 1.5g of graphene oxide and 0.5g of hexadecyltrimethylammonium bromide were added to 15g of deionized water, ultrasonically treated for 20min at an ultrasonic frequency of 7.5kHz, and then vacuum dried.
[0063] S2. Mix 3g of pretreated carbon nanotubes, 1.5g of microcrystalline cellulose, and 8g of micron-sized silica powder evenly. Calcine at 350℃ for 20min under nitrogen protection, cool to room temperature, pulverize, and add 1.5g of sodium alginate and 0.5g of polyacrylamide to 30g of deionized water. Stir at 1500r / min for 20min. Add 1.5g of nano-silica powder and 1.5g of graphite powder and continue stirring for 90min to obtain a slurry.
[0064] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 95℃ for 45 minutes, and then cool it to room temperature.
[0065] Comparative Example 2
[0066] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0067] S1. Add 1.5g of multi-walled carbon nanotubes to 30g of 12mol / L sulfuric acid solution, stir at 35℃ for 15min at a stirring speed of 800r / min, raise the temperature to 85℃, continue stirring for 90min, adjust the pH of the system to 6.5-7, add 1.5g of graphene oxide and sonicate for 90min, transfer to a hydrothermal reactor, hydrothermally react at 190℃ for 15h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0068] S2. Mix 3g of pretreated carbon nanotubes, 1.5g of microcrystalline cellulose, and 8g of micron-sized silica powder evenly. Calcine at 350℃ for 20min under nitrogen protection, cool to room temperature, pulverize, and add 1.5g of sodium alginate and 0.5g of polyacrylamide to 30g of deionized water. Stir at 1500r / min for 20min. Add 1.5g of nano-silica powder and 1.5g of graphite powder and continue stirring for 90min to obtain a slurry.
[0069] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 95℃ for 45 minutes, and then cool it to room temperature.
[0070] Comparative Example 3
[0071] A method for preparing a silicon-carbon anode material for lithium batteries includes the following steps:
[0072] S1. Add 1.5g of multi-walled carbon nanotubes to 30g of 12mol / L sulfuric acid solution, stir at 35℃ for 15min at a stirring speed of 800r / min, raise the temperature to 85℃, continue stirring for 90min, adjust the pH of the system to 6.5-7, add 1.5g of pretreated graphene oxide and sonicate for 90min, transfer to a hydrothermal reactor, hydrothermally react at 190℃ for 15h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes;
[0073] The above-mentioned pretreated graphene oxide was prepared by the following specific steps: 1.5g of graphene oxide and 0.5g of hexadecyltrimethylammonium bromide were added to 15g of deionized water, ultrasonically treated for 20min at an ultrasonic frequency of 7.5kHz, and then vacuum dried.
[0074] S2. Mix 3g of pretreated carbon nanotubes, 1.5g of microcrystalline cellulose, and 9.5g of micron-sized silica powder evenly, calcine at 350℃ for 20min under nitrogen protection, cool to room temperature, pulverize, add 1.5g of sodium alginate and 0.5g of polyacrylamide to 30g of deionized water, stir at 1500r / min for 20min, add 1.5g of graphite powder and continue stirring for 90min to obtain a slurry;
[0075] S3. Coat the slurry onto the copper foil, dry it, and then put it into a vacuum oven. Treat it at 95℃ for 45 minutes, and then cool it to room temperature.
[0076] The slurries obtained in Example 5 and Comparative Examples 1-3 were coated onto a clean glass surface, dried at 95°C for 45 minutes, and then removed. The tensile properties of each group of samples were determined in accordance with GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets".
[0077] like Figure 1 As shown, the sheet prepared using the slurry obtained in Example 5 has the highest tensile strength and elongation at break, which is superior to Comparative Examples 1-3 (P<0.05).
[0078] The elastic modulus of the silicon-carbon anode materials obtained in Example 5 and Comparative Examples 1-3 were measured in the dry state and in the electrolyte using the nanoindentation method.
[0079] like Figure 2 As shown, the silicon-carbon anode materials obtained in Example 5 all have the highest elastic modulus, which is better than that of Comparative Examples 1-3 (P<0.05).
[0080] The CR2032 button cell was assembled using silicon-carbon anode materials obtained in Example 5 and Comparative Examples 1-3 as the anode, lithium metal sheets as the cathode, and a PP / PE / PP (Celgard 2400) three-layer composite separator as the lithium-ion battery separator. 1 mol / L LiPF6 was dissolved in ethylene carbonate (EC) / ethyl methyl carbonate (DMC) / dimethyl carbonate (EMC) (volume ratio of 1:1:1) and 10% FEC (fluoroethylene carbonate) was added as the electrolyte. The entire assembly process was completed in a glove box, and the silicon-carbon battery was finally obtained.
[0081] Electrochemical performance tests were conducted on each group of silicon-carbon batteries at a current density of 500 mA / g. 100 charge-discharge cycles were performed, and the discharge capacity after 100 cycles was compared with the initial discharge capacity to calculate the capacity retention rate after 100 cycles.
[0082] like Figure 3As shown, the silicon-carbon battery made with the silicon-carbon anode material obtained in Example 5 has the highest initial discharge capacity, and the capacity retention rate after 100 charge-discharge cycles is also the highest, which is better than Comparative Examples 1-3 (P<0.05).
[0083] After 100 charge-discharge cycles, the silicon-carbon anode materials of each group were removed, and the volume of the silicon-carbon anode materials before and after the cycles was calculated to determine the expansion rate.
[0084] Expansion rate = (Volume after 100 cycles - Original volume) ÷ Original volume × 100%
[0085] like Figure 4 As shown, the silicon-carbon anode material obtained in Example 5 has the lowest expansion rate, which is better than that of Comparative Examples 1-3 (P<0.05).
[0086] The applicant believes that this invention is due to the fact that carbon nanotubes, after acidification treatment, contain abundant active functional groups, while graphene oxide adsorbs cationic surfactants on its surface, giving it a positive charge. These are then mixed with the acidified carbon nanotubes, resulting in a highly stable bond due to electrostatic interactions. After hydrothermal treatment, and with the assistance of microcrystalline cellulose, they are compounded with silicon powder and calcined. This results in excellent coating of the silicon powder surface, combined with the carbonized structure of the microcrystalline cellulose. The constructed three-dimensional network structure greatly increases the lithium-ion diffusion channels and effectively buffers the volume change of silicon during charge and discharge. Furthermore, with the help of sodium alginate and polyacrylamide, the silicon powder is combined with nano-silicon powder. The internally coated silicon powder and the external nano-silicon powder are bonded together through an organic network, forming a product with high elasticity and high conductivity. This not only greatly alleviates the reduction in contact area caused by silicon volume expansion during charge and discharge cycles, resulting in excellent cycle performance, but also forms a polymer-carbon dot network structure between sodium alginate and polyacrylic acid. This conductive structure improves the material's conductivity and gives the product high specific capacity, electrochemical activity, and stability. Meanwhile, this invention utilizes sodium alginate combined with polyacrylamide and nano-silicon powder to form a strong binding force during heating, forming a network of hydrogen bonds within and between molecules. The system has high viscosity, effectively increasing the porosity and tensile properties of the electrode, and can effectively repair electrode damage caused by volume changes during cycling of silicon-carbon anodes, greatly improving cycle stability.
[0087] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing a silicon-carbon anode material for lithium batteries, characterized in that, Includes the following steps: S1. Add carbon nanotubes to sulfuric acid solution, stir at 30-40℃ for 10-20 min, raise the temperature to 80-90℃, continue stirring for 1-2 h, adjust the pH of the system to 6.5-7, add pretreated graphene oxide and sonicate for 1-2 h, hydrothermal reaction at 180-200℃ for 10-20 h, cool to room temperature, centrifuge, wash, and vacuum dry to obtain pretreated carbon nanotubes; In S1, the pretreated graphene oxide is prepared using the following specific steps: graphene oxide and cationic surfactant are added to water, ultrasonically treated for 10-30 minutes at an ultrasonic frequency of 5-12 kHz, and then vacuum dried. S2. Mix the pretreated carbon nanotubes, microcrystalline cellulose, and silicon powder evenly, calcine at 300-400℃ for 10-30 minutes under nitrogen protection, cool to room temperature, pulverize, add sodium alginate and polyacrylamide to water and stir for 10-30 minutes, add nano silicon powder and graphite powder and continue stirring for 1-2 hours to obtain a slurry. In S2, the particle size of silicon powder is 1-20μm, the particle size of nano-silicon powder is 50-200nm, and the mass ratio of pretreated carbon nanotubes, microcrystalline cellulose, silicon powder, sodium alginate, polyacrylamide, nano-silicon powder, and graphite powder is 2-4:1-2:5-10:1-2:0.1-1:1-2:1-2; S3. Coat the slurry onto the copper foil, dry it, heat treat it at 90-100℃ for 30-60 minutes, and then cool it to room temperature.
2. The method for preparing silicon-carbon anode material for lithium batteries according to claim 1, characterized in that, In S1, the mass ratio of carbon nanotubes to pretreated graphene oxide is 1-2:1-2.
3. The method for preparing silicon-carbon anode material for lithium batteries according to claim 1, characterized in that, In S1, the concentration of the sulfuric acid solution is 10⁻¹⁴ mol / L.
4. The method for preparing silicon-carbon anode material for lithium batteries according to claim 1, characterized in that, In S1, the carbon nanotubes are multi-walled carbon nanotubes with an inner diameter of 3-5 nm, an outer diameter of 8-15 nm, a length of 3-12 μm, and a specific surface area of 255-280 m². 2 / g.
5. The method for preparing silicon-carbon anode material for lithium batteries according to claim 1, characterized in that, The cationic surfactant is hexadecyltrimethylammonium bromide, and the mass ratio of graphene oxide to cationic surfactant is 1-2:0.1-1.
6. A silicon-carbon anode material for lithium batteries, characterized in that, It is prepared by the method for preparing silicon-carbon anode material for lithium batteries according to any one of claims 1-5.
7. A lithium battery, characterized in that, The silicon-carbon anode material for lithium batteries as described in claim 6 is used as the anode.