A silicon-based anode material for a lithium-ion battery, a preparation method thereof, and a battery

Abstract

The present invention provides a silicon-based anode material for a lithium-ion battery, a preparation method thereof, and a battery, belonging to the technical field of electrode materials for new energy batteries. Among them, the preparation method of the silicon-based anode material for the lithium-ion battery comprises the steps of: subjecting carbon nanofibers to acid oxidation, and then performing silicon loading to obtain a CNF / Si composite material; adding aniline monomers to a xanthan gum solution, and then adding an ammonium persulfate solution until a polymerization reaction forms a dark green gel product A; adding graphene quantum dots to the gel product A, and then adding a ferric chloride solution, and stirring and reacting to obtain a gel product B; adding the CNF / Si composite material to the gel product B, heating and stirring, then dropping a borax solution for reaction, and then annealing to obtain the silicon-based anode material for the lithium-ion battery. The silicon-based anode material for the lithium-ion battery and the battery provided by the present invention have high cycle stability, high specific capacity, and a wide application range.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy battery electrode materials, and particularly relates to a silicon-based anode material for lithium-ion batteries, a preparation method thereof, and a battery. Background Art

[0002] Lithium-ion batteries are widely used in fields such as electronic products, portable power tools, and electric vehicles. With the rapid development of electronic technology and the growing new energy vehicle market, the market's demand for lithium-ion batteries with higher energy density is becoming more urgent. However, the anodes used in currently commercialized lithium-ion batteries are graphite anodes, and their theoretical specific capacity is only 372 mAh / g, which cannot meet the requirements of high-energy density batteries.

[0003] Silicon is considered an ideal choice for the next-generation anode material of lithium-ion batteries due to its relatively high specific capacity (4200 mAh / g) and low de-lithiation platform. However, the volume expansion and contraction rate of silicon anodes during the process of lithium de-insertion and insertion is greater than 300%, resulting in poor cycle performance in lithium batteries; in addition, the electronic conductivity and ionic conductivity of silicon are relatively low, resulting in poor rate performance. Therefore, the optimization and modification research of silicon-based anode materials is required by the market. Summary of the Invention

[0004] In order to solve the problems mentioned in the background art, the silicon-based anode material for lithium-ion batteries provided by the present invention has high cycle stability, high specific capacity, and a wide range of applications.

[0005] Specifically:

[0006] A preparation method of a silicon-based anode material for lithium-ion batteries includes the following steps:

[0007] Step 1: Add carbon nanofibers to nitric acid solution, ultrasonically disperse, then reflux at 80 - 85 °C for 3 - 4 h, and dry for later use;

[0008] Step 2: Add porous silicon nanoparticles to absolute ethanol, ultrasonically disperse, then add the carbon nanofibers treated in Step 1, continue to ultrasonically disperse, transfer the mixture to a vacuum filtration device, and collect the CNF / Si wet material;

[0009] Step 3: Spread the CNF / Si wet material on a quartz boat, place it in a fume hood for natural drying, then put the quartz boat into the middle of the quartz tube of a tube furnace, connect a vacuum pump and a nitrogen system, evacuate to 0.9 - 1×10 -2 Pa, then fill with nitrogen to restore normal pressure, perform the evacuation-nitrogen filling cycle 2 - 4 times, then heat up to 400 - 410 °C, keep warm for 2 - 3 h, then cool down naturally, collect the CNF / Si composite material, and seal and store it in a nitrogen-filled glove box;

[0010] Step 4: Add aniline monomer to the xanthan gum solution, stir evenly, and then gradually add ammonium persulfate solution until a dark green gel product A is formed by polymerization reaction.

[0011] Step 5: Add graphene quantum dots to the gel product A obtained in Step 4, disperse ultrasonically, and then add ferric chloride solution, stir and react for 1 - 2 h to obtain gel product B.

[0012] Step 6: Add the CNF / Si composite material obtained in Step 3 to the gel product B obtained in Step 5, raise the temperature to 60 - 65 °C, stir for 1 - 2 h, then dropwise add borax solution, lower the temperature to 50 - 55 °C, adjust the pH to 9 - 9.5, react for 0.5 - 1 h, perform vacuum filtration and drying, and then transfer to a reaction furnace and anneal at 60 - 65 °C in a nitrogen atmosphere for 2 - 3 h. After cooling, a silicon-based anode material for lithium-ion batteries is obtained.

[0013] When implementing the above embodiments, preferably, the nitric acid solution in Step 1 is 65% nitric acid; the addition ratio of carbon nanofibers to the nitric acid solution is 1 g: 20 - 25 mL.

[0014] When implementing the above embodiments, preferably, the particle size of the porous silicon nanoparticles in Step 2 is 80 - 100 nm, and the porosity is 50% - 60%.

[0015] When implementing the above embodiments, preferably, the addition ratio of the porous silicon nanoparticles to absolute ethanol in Step 2 is 1 g: 100 - 120 mL; the addition mass ratio of the porous silicon nanoparticles to carbon nanofibers is 1: 1.5 - 2.

[0016] When implementing the above embodiments, preferably, the flat thickness of the CNF / Si wet material in Step 3 is ≤ 5 mm; the nitrogen flow rate is 45 - 50 sccm; the heating rate is 4 - 5 °C / min.

[0017] When implementing the above embodiments, preferably, the addition volume ratio of aniline monomer to the xanthan gum solution in Step 4 is 4.5 - 5: 100, the mass fraction of the xanthan gum solution is 2% - 3%; the concentration of the ammonium persulfate solution is 4 - 5 M, and the dropping rate is 1 - 2 mL / min.

[0018] When implementing the above embodiments, preferably, the addition ratio of graphene quantum dots to the gel product A in Step 5 is 2 - 2.5 g: 1000 mL; the concentration of the ferric chloride solution is 0.15 - 0.2 M, and the addition volume ratio of the ferric chloride solution to the gel product A is 20: 1.

[0019] When implementing the above embodiments, preferably, in step 6, the addition ratio of the CNF / Si composite material to the gel product B is 1 g: 100 - 110 mL; the mass fraction of the borax solution is 0.5% - 0.7%, and the volume ratio of the borax solution to the gel product B is 1:5.

[0020] When implementing the above embodiments, preferably, in step 6, the drying temperature is 80 - 85 °C; the annealing heating rate is 3 - 5 °C / min.

[0021] In addition, the present invention also provides a silicon-based anode material for a lithium-ion battery, which is prepared by the above preparation method.

[0022] In addition, the present invention also provides a battery, the anode material of which is prepared by the above preparation method.

[0023] Compared with the prior art, the beneficial features of the present invention are as follows:

[0024] 1. For the silicon-based anode material of the lithium-ion battery of the present invention, linear carbon nanofibers (CNF) are used as the conductive skeleton, and silicon substances are loaded on the surface of the carbon nanofibers to improve the specific capacity of the anode material; in addition, aniline monomers react with xanthan gum and ammonium persulfate to generate polyaniline (PANI), and at the same time, graphene quantum dots (GQDs) are added to construct a xanthan gum-PANI-GQDs gel network; the CNF / Si composite material is mixed with the xanthan gum-PANI-GQDs gel network, and borax is added to crosslink CNF and xanthan gum. Moreover, due to the linear structure of CNF, it can entangle with the xanthan gum-PANI-GQDs gel network through mechanical interlocking to form a stable structure, and the xanthan gum-PANI-GQDs gel network is recombined through dynamic hydrogen bonds and borate ester bonds to buffer the volume expansion stress of silicon.

[0025] 2. For the silicon-based anode material of the lithium-ion battery of the present invention, the constructed xanthan gum-PANI-GQDs gel network introduces , and xanthan gum coordinates with to form a rigid region, inhibiting crack propagation and improving the stability of the structure. And the xanthan gum-PANI-GQDs gel network has a double conduction path, combines with CNF through π-π stacking of the PANI conjugated chain to provide an electron transport channel; GQDs are embedded in the gel network to improve the electron transition efficiency through the quantum confinement effect. In addition, the group (sulfate group) of xanthan gum promotes the migration of lithium ions, which can improve the fast charging effect. Specific Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0027] To facilitate the implementation of the present invention by those skilled in the art, some reagents used in the examples and comparative examples are described below:

[0028] Carbon nanofibers: Jiangsu Xianfeng Nano Materials Technology;

[0029] Porous silicon nanoparticles: The particle size of the porous silicon nanoparticles is 80 nm, and the porosity is 60%. Beijing Zhongke Keyou Technology;

[0030] Aniline monomer: Jinan Quansheng Chemical Industry;

[0031] Xanthan gum: Anhui Xinsheng Biotechnology;

[0032] Ammonium persulfate: Shandong Hairui New Materials;

[0033] Graphene quantum dots: Suzhou Kaifa New Materials Technology;

[0034] Ferric chloride: Jinan Xinnuo Chemical Industry;

[0035] Borax: Shandong Youwei Chemical Industry.

[0036] Example 1

[0037] A silicon-based anode material for a lithium-ion battery is prepared according to the following steps:

[0038] Step 1: Add carbon nanofibers to 65% nitric acid solution according to a solid-liquid ratio of 1 g: 20-25 mL, disperse ultrasonically, then reflux at 80-85 °C for 3-4 h, and dry for later use;

[0039] Step 2: Add porous silicon nanoparticles to absolute ethanol according to a solid-liquid ratio of 1 g: 100-120 mL, disperse ultrasonically, then add the carbon nanofibers treated in Step 1. The addition mass ratio of the porous silicon nanoparticles to the carbon nanofibers is 1: 1.5-2, continue to disperse ultrasonically for 1 h, transfer the mixture to a vacuum filtration device, filter with a 0.22 μm nylon membrane, and collect the CNF / Si wet material;

[0040] Step 3: Spread the CNF / Si wet material flat in a quartz boat with a thickness ≤ 5 mm, place it in a fume hood for natural drying, then put the quartz boat into the middle of the quartz tube of a tube furnace, connect a vacuum pump and a nitrogen system, evacuate to 0.9-1×10 -2Pa, close the vacuum valve, then fill it with nitrogen to restore normal pressure, and conduct the vacuum-purging cycle 2-4 times. Subsequently, maintain the nitrogen flow rate at 45-50 sccm throughout the process, heat it to 400-410 °C at a rate of 4-5 °C / min, keep it warm for 2-3 h, then cool it naturally, collect the CNF / Si composite material, and store it sealed in a nitrogen-filled glove box;

[0041] Step 4: Add aniline monomer to the 2%-3% xanthan gum solution at a volume ratio of 4.5-5:100, stir evenly, and then gradually add the 4-5 M ammonium persulfate solution dropwise at a rate of 1-2 mL / min until a dark green gel product A is formed by the polymerization reaction;

[0042] Step 5: Add graphene quantum dots to the gel product A obtained in Step 4 at a solid-liquid ratio of 2-2.5 g:1000 mL, disperse it by ultrasonic wave, and then add the 0.15-0.2 M ferric chloride solution to the gel product A at a volume ratio of 20:1, stir and react for 1-2 h to obtain the gel product B;

[0043] Step 6: Add the CNF / Si composite material obtained in Step 3 to the gel product B obtained in Step 5 at a solid-liquid ratio of 1 g:100-110 mL, heat it to 60-65 °C, stir for 1-2 h, then add dropwise the 0.5%-0.7% borax solution, the volume ratio of the borax solution to the gel product B is 1:5, cool it to 50-55 °C, adjust the pH to 9-9.5 (adjusted with NaOH), react for 0.5-1 h, conduct vacuum filtration, dry it at 80 °C for 2 h, then transfer it to a reaction furnace and anneal it at 60-65 °C in a nitrogen atmosphere for 2-3 h, and obtain the silicon-based anode material for lithium-ion batteries after cooling;

[0044] Example 2

[0045] A silicon-based anode material for lithium-ion batteries is prepared as follows:

[0046] Step 1: Add carbon nanofibers to 65% nitric acid solution at a solid-liquid ratio of 1 g:20-25 mL, disperse it by ultrasonic wave, then reflux it at 80-85 °C for 3-4 h, and dry it for later use;

[0047] Step 2: Add porous silicon nanoparticles to absolute ethanol at a solid-liquid ratio of 1 g:100-120 mL, disperse it by ultrasonic wave, then add the carbon nanofibers treated in Step 1, the addition mass ratio of the porous silicon nanoparticles to the carbon nanofibers is 1:1.5-2, continue to disperse it by ultrasonic wave for 1 h, transfer the mixture to a vacuum filtration device, filter it with a 0.22 μm nylon membrane, and collect the CNF / Si wet material;

[0048] Step 3: Spread the CNF / Si wet material evenly in the quartz boat with a thickness ≤ 5 mm, place it in the fume hood for natural drying, then put the quartz boat into the middle of the quartz tube of the tube furnace, connect the vacuum pump and the nitrogen system, evacuate to 0.9 - 1×10 -2 Pa, close the vacuum valve, then fill with nitrogen to restore normal pressure, perform the evacuation-nitrogen filling cycle 2 - 4 times, then keep the nitrogen flow rate at 45 - 50 sccm throughout the process, heat up to 400 - 410 °C at a rate of 4 - 5 °C / min, hold for 2 - 3 h, then cool down naturally, collect the CNF / Si composite material, and store it sealed in a nitrogen-filled glove box;

[0049] Step 4: Add aniline monomer to the 2% - 3% xanthan gum solution at a volume ratio of 4.5 - 5:100, stir evenly, then gradually add 4 - 5 M ammonium persulfate solution dropwise at a rate of 1 - 2 mL / min until a dark green gel product A is formed by the polymerization reaction;

[0050] Step 5: Add graphene quantum dots to the gel product A obtained in Step 4 at a solid-liquid ratio of 2 - 2.5 g:1000 mL, disperse by ultrasonic, then add 0.15 - 0.2 M ferric chloride solution to the gel product A at a volume ratio of 20:1, stir and react for 1 - 2 h to obtain gel product B;

[0051] Step 6: Add the CNF / Si composite material obtained in Step 3 to the gel product B obtained in Step 5 at a solid-liquid ratio of 1 g:100 - 110 mL, heat up to 60 - 65 °C, stir for 1 - 2 h, then dropwise add 0.5% - 0.7% borax solution with a volume ratio of 1:5 to the gel product B, cool down to 50 - 55 °C, adjust the pH = 9 - 9.5 (adjusted with NaOH), react for 0.5 - 1 h, perform vacuum filtration, dry at 80 °C for 2 h, then transfer to the reaction furnace and anneal at 60 - 65 °C in a nitrogen atmosphere for 2 - 3 h, and obtain the silicon-based anode material for lithium-ion batteries after cooling.

[0052] Example 3

[0053] A silicon-based anode material for lithium-ion batteries, and its preparation steps are as follows:

[0054] Step 1: Add carbon nanofibers to 65% nitric acid solution at a solid-liquid ratio of 1 g:20 - 25 mL, disperse by ultrasonic, then reflux at 80 - 85 °C for 3 - 4 h, and dry for later use;

[0055] Step 2: Add porous silicon nanoparticles to absolute ethanol at a solid-liquid ratio of 1 g:100 - 120 mL, disperse by ultrasonic, then add the carbon nanofibers treated in Step 1, with the added mass ratio of porous silicon nanoparticles to carbon nanofibers being 1:1.5 - 2, continue to disperse by ultrasonic for 1 h, transfer the mixture to a vacuum filtration device, filter with a 0.22 μm nylon membrane, and collect the CNF / Si wet material;

[0056] Step 3: Spread the CNF / Si wet material flat in the quartz boat with a thickness ≤ 5 mm, place it in the fume hood for natural drying, then put the quartz boat in the middle of the quartz tube of the tubular furnace, connect the vacuum pump and the nitrogen system, evacuate to 0.9 - 1×10 -2 Pa, close the vacuum valve, then fill with nitrogen to restore normal pressure, repeat the evacuation - nitrogen filling cycle 2 - 4 times, then keep the nitrogen flow rate at 45 - 50 sccm throughout the process, heat up to 400 - 410 °C at a rate of 4 - 5 °C / min, hold for 2 - 3 h, then cool down naturally, collect the CNF / Si composite material, and store it sealed in a nitrogen - filled glove box;

[0057] Step 4: Add aniline monomer to the 2% - 3% xanthan gum solution at a volume ratio of 4.5 - 5:100, stir evenly, then add the 4 - 5 M ammonium persulfate solution dropwise at a rate of 1 - 2 mL / min until a dark green gel product A is formed by the polymerization reaction;

[0058] Step 5: Add graphene quantum dots to the gel product A obtained in Step 4 at a solid - liquid ratio of 2 - 2.5 g:1000 mL, disperse by ultrasonic, then add the 0.15 - 0.2 M ferric chloride solution to the gel product A at a volume ratio of 20:1, stir and react for 1 - 2 h to obtain the gel product B;

[0059] Step 6: Add the CNF / Si composite material obtained in Step 3 to the gel product B obtained in Step 5 at a solid - liquid ratio of 1 g:100 - 110 mL, heat up to 60 - 65 °C, stir for 1 - 2 h, then add dropwise the 0.5% - 0.7% borax solution with a volume ratio of the borax solution to the gel product B of 1:5, cool down to 50 - 55 °C, adjust the pH = 9 - 9.5 (using NaOH to adjust), react for 0.5 - 1 h, vacuum filter, dry at 80 °C for 2 h, then transfer to the reaction furnace and anneal at 60 - 65 °C in a nitrogen atmosphere for 2 - 3 h, and obtain the silicon - based anode material for lithium - ion batteries after cooling.

[0060] Comparative Example 1

[0061] A silicon - based anode material for lithium - ion batteries, and its preparation steps are as follows:

[0062] Step 1: Add carbon nanofibers to 65% nitric acid solution at a solid - liquid ratio of 1 g:20 - 25 mL, disperse by ultrasonic, then reflux at 80 - 85 °C for 3 - 4 h, and dry for later use;

[0063] Step 2: Add porous silicon nanoparticles to absolute ethanol at a solid-liquid ratio of 1 g: 100 - 120 mL, disperse ultrasonically, and then add the carbon nanofibers treated in Step 1. The mass ratio of the added porous silicon nanoparticles to the carbon nanofibers is 1: 1.5 - 2. Continue to disperse ultrasonically for 1 h. Transfer the mixture to a vacuum filtration device, filter with a 0.22 μm nylon membrane, and collect the CNF / Si wet material.

[0064] Step 3: Spread the CNF / Si wet material flat in a quartz boat with a thickness ≤ 5 mm, place it in a fume hood to dry naturally, and then put the quartz boat in the middle of the quartz tube of a tube furnace. Connect a vacuum pump and a nitrogen system, evacuate to 0.9 - 1×10 -2 Pa, close the vacuum valve, then fill with nitrogen to restore normal pressure, perform the evacuation-nitrogen filling cycle 2 - 4 times, then keep the nitrogen flow rate at 45 - 50 sccm throughout the process, heat up to 400 - 410 °C at a rate of 4 - 5 °C / min, keep warm for 2 - 3 h, and then cool down naturally. After ball milling, a silicon-based anode material for lithium-ion batteries is obtained.

[0065] Assemble the silicon-based anode materials for lithium-ion batteries obtained in Examples 1 - 3 and Comparative Example 1 into batteries for experimental verification.

[0066] Battery assembly process: Mix the anode material, conductive agent (SP), CMC, and SBR according to a mass ratio of 95: 1.5: 1.5: 2, and coat it on a copper foil to obtain a negative electrode sheet. Mix the positive active material lithium cobaltate, conductive agent (SP), and PVDF evenly according to a mass ratio of 96.5: 2: 1.5, and then coat it on an aluminum foil to obtain a positive electrode sheet. The electrolyte is 1 mol / L LiPF6 + EC + EMC, and the separator is a polyethylene / polypropylene composite microporous membrane. Assemble them into a battery.

[0067] Test the initial discharge capacity at 0.1C; then perform a 200-week cycle test, charge and discharge at 1C, with a discharge cut-off voltage of 0.01 V and a charge cut-off voltage of 1.5 V; record the capacity retention rates after 50 weeks, 100 weeks, and 200 weeks. The test results are as follows:

[0068] Initial discharge capacity at 0.1C (mAh / g) Capacity retention after 50 cycles of charge and discharge at 1C (%) Capacity retention after 100 cycles of charge and discharge at 1C (%) Capacity retention after 200 cycles of charge and discharge at 1C (%) Example 1 3159 95.3 90.6 84.7 Example 2 3207 94.2 88.5 83.8 Example 3 3186 94.4 89.4 84.1 Comparative Example 1 2869 56.3 37.5 25.8

[0069] From the above test results, it can be seen that the capacities of Examples 1 - 3 are higher than those of carbon-based batteries, and a relatively high capacity can still be maintained after 200 weeks of cycling, indicating high cycle stability. Comparative Example 1 simulates a battery with a common carbon / silicon anode material. Although it also has a high capacity, its capacity retention rate after 200 weeks of cycling is low and the stability is poor.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a silicon-based anode material for a lithium-ion battery, characterized in that, It includes the following steps: Step 1: Add carbon nanofibers into nitric acid solution, disperse them by ultrasonic, then reflux at 80 - 85 °C for 3 - 4 h, and dry for later use; Step 2: Add porous silicon nanoparticles into absolute ethanol, disperse them by ultrasonic, then add the carbon nanofibers treated in Step 1, continue to disperse by ultrasonic, transfer the mixture to a vacuum filtration device, and collect the CNF / Si wet material; Step 3: Spread the CNF / Si wet material flat in a quartz boat, place it in a fume hood for natural drying, then put the quartz boat into the middle of the quartz tube of a tube furnace, connect the vacuum pump and the nitrogen system, evacuate to 0.9 - 1×10 -2 Pa, then fill with nitrogen to restore normal pressure, perform the evacuation - nitrogen filling cycle 2 - 4 times, then heat up to 400 - 410 °C, keep the temperature for 2 - 3 h, then cool down naturally, collect the CNF / Si composite material, and store it sealed in a nitrogen - filled glove box; Step 4: Add aniline monomer into xanthan gum solution, stir evenly, then dropwise add ammonium persulfate solution until a dark green gel product A is formed by polymerization reaction; Step 5: Add graphene quantum dots into the gel product A obtained in Step 4, disperse them by ultrasonic, then add ferric chloride solution, stir and react for 1 - 2 h to obtain gel product B; Step 6: Add the CNF / Si composite material obtained in Step 3 into the gel product B obtained in Step 5, heat up to 60 - 65 °C, stir for 1 - 2 h, then dropwise add borax solution, cool down to 50 - 55 °C, adjust the pH to 9 - 9.5, react for 0.5 - 1 h, conduct vacuum filtration and drying, then transfer to a reaction furnace and anneal at 60 - 65 °C in a nitrogen atmosphere for 2 - 3 h, and obtain the silicon-based anode material for lithium-ion batteries after cooling.

2. The preparation method according to claim 1, wherein In Step 1, the nitric acid solution is 65% nitric acid; the addition ratio of carbon nanofibers to nitric acid solution is 1 g:20 - 25 mL.

3. The preparation method according to claim 1, wherein, In Step 2, the particle size of the porous silicon nanoparticles is 80 - 100 nm, and the porosity is 50% - 60%.

4. The preparation method according to claim 1, wherein In Step 2, the addition ratio of porous silicon nanoparticles to absolute ethanol is 1 g:100 - 120 mL; the addition mass ratio of porous silicon nanoparticles to carbon nanofibers is 1:1.5 - 2.

5. The preparation method according to claim 1, characterized in that, In Step 3, the flat thickness of the CNF / Si wet material ≤ 5 mm; the nitrogen flow rate is 45 - 50 sccm; the heating rate is 4 - 5 °C / min.

6. The preparation method according to claim 1, wherein, In Step 4, the addition volume ratio of aniline monomer to xanthan gum solution is 4.5 - 5:100, the mass fraction of xanthan gum solution is 2% - 3%; the concentration of ammonium persulfate solution is 4 - 5 M, and the dropping rate is 1 - 2 mL / min.

7. The preparation method according to claim 1, characterized in that, In Step 5, the addition ratio of graphene quantum dots to gel product A is 2 - 2.5 g:1000 mL; the concentration of ferric chloride solution is 0.15 - 0.2 M, and the addition volume ratio of ferric chloride solution to gel product A is 20:

1.

8. The preparation method according to claim 1, characterized in that, In Step 6, the addition ratio of CNF / Si composite material to gel product B is 1 g:100 - 110 mL; the mass fraction of borax solution is 0.5% - 0.7%, and the volume ratio of borax solution to gel product B is 1:

5.

9. A silicon-based anode material for a lithium-ion battery, characterized in that, It is prepared by the preparation method described in any one of claims 1 - 8.

10. A battery, characterized in that, Its anode material is prepared by the preparation method described in any one of claims 1 - 8.