A nano-silicon@SiOx / MXene composite anode material and its preparation method

Abstract

This invention provides a nano-silicon@SiO x This invention relates to the field of silicon cutting waste recycling technology, specifically the MXene composite anode material and its preparation method. The invention involves oxidizing silicon cutting waste to obtain nano-silicon@SiO₂. x Then, nano-silicon@SiO x When mixed with a pH buffer solution, negatively charged nano-silicon@SiO₂ is obtained. x The precursor was MAX etched to obtain MXene. MXene was mixed with a cationic surfactant solution to obtain positively charged MXene. Finally, negatively charged nano-silicon@SiO2 was added. x Positively charged MXene and pH buffer solution were mixed to obtain nano-silicon@SiO. x / MXene composite anode material. Nano-silicon@SiO2 prepared in this invention. x The MXene composite anode material overcomes the problems of volume expansion and poor conductivity of silicon materials during the charging and discharging process of lithium-ion batteries, and significantly improves the electrochemical performance of silicon-based anode materials.

Description

Technical Field

[0001] This invention relates to the field of silicon cutting waste recycling technology, and particularly to a nano-silicon@SiO2 method. x / MXene composite anode material and its preparation method. Background Technology

[0002] Currently, advancements in silicon-based photovoltaic (PV) technology have significantly reduced power generation costs, making large-scale solar energy applications possible. However, the intermittency and volatility of solar power generation severely limit its further development. Therefore, the integration of PV power generation with advanced energy storage is considered the ultimate solution for future energy needs. Global PV power generation is growing at a rate exceeding 35% annually, leading to a steady increase in silicon wafer consumption. In the PV industry, silicon wafers are produced through diamond wire slicing of solar-grade silicon ingots. During the production process, approximately 35% of SoG-Si is cut into silicon cutting waste. Currently, my country's annual output of silicon cutting waste exceeds 400,000 tons, and the effective recycling of silicon cutting waste faces significant challenges.

[0003] The most common strategy for recycling silicon cutting waste is to use it directly as a high-purity silicon raw material. However, recent studies have recognized difficulties in melting and impurity removal from silicon cutting waste due to the naturally occurring ultrafine-grained amorphous silicon oxide layer. Silicon materials possess a high theoretical specific capacity (4200 mAh·g). -1 ), and the discharge potential is relatively low (for lithium / lithium + With its advantages such as a discharge potential of <0.5V and abundant reserves on Earth, silicon has become one of the most attractive anode materials for lithium-ion batteries (LIBs), providing another value-added pathway for the recycling of silicon cutting waste. However, past research has mainly focused on traditional loose abrasive slurry sawing of waste silicon, while research on using current diamond wire-cut silicon waste is relatively limited.

[0004] With the increasing demand for high-energy-density energy storage, silicon is one of the most promising anode materials for lithium-ion batteries. However, the main challenge facing silicon-based anodes is their enormous volume expansion (approximately 300%), which causes silicon particles to fission or turn into powder, resulting in loss of contact between the active material and the conductor during lithiation / delithiation. Furthermore, the repeated formation and thickening of the solid electrolyte interphase (SEI) layer and the low conductivity of silicon lead to rapid capacity loss, low initial coulombic efficiency (ICE), and poor electrochemical performance, which have become major limiting factors for silicon-based anodes. Therefore, this study investigates a nano-silicon@SiO2 anode. x The discovery of MXene composite anode materials and their preparation methods is of great significance for improving the initial coulombic efficiency and electrochemical performance of silicon-based anodes. Summary of the Invention

[0005] The purpose of this invention is to provide a nano-silicon@SiOx The invention relates to MXene composite anode materials and their preparation methods, aiming to address the problems of severe volume expansion, low initial coulombic efficiency, and poor electrochemical performance in existing silicon-based anodes.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a nano-silicon@SiO x The preparation method of / MXene composite anode material includes the following steps:

[0008] (1) Oxidize silicon cutting waste to obtain nano-silicon@SiO x ;

[0009] (2) Nano-silicon@SiO x When mixed with a pH buffer solution, negatively charged nano-silicon@SiO₂ is obtained. x ;

[0010] (3) The precursor MAX was etched to obtain MXene. MXene was mixed with a cationic surfactant solution to obtain positively charged MXene.

[0011] (4) Negatively charged nano-silicon@SiO x Positively charged MXene and pH buffer solution were mixed to obtain nano-silicon@SiO. x / MXene composite anode material.

[0012] Preferably, in step (1), the oxidation treatment is carried out in an oxidizing atmosphere; the temperature of the oxidation treatment is 100 to 1500°C, and the time of the oxidation treatment is 0.1 to 48 hours.

[0013] Preferably, in step (2), nano-silicon@SiO x The mass-to-volume ratio of the pH buffer solution is 1–5 g: 100–1000 mL.

[0014] Preferably, in step (2), the mixing time is 0.1 to 48 hours.

[0015] Preferably, the pH buffer solution independently comprises one or more of the following: phosphate buffer, glycine-hydrochloric acid buffer, phthalic acid-hydrochloric acid buffer, disodium hydrogen phosphate-citric acid buffer, citrate-sodium hydroxide-hydrochloric acid buffer, citrate-sodium citrate buffer, acetate-sodium acetate buffer, potassium dihydrogen phosphate-sodium hydroxide buffer, sodium barbital-hydrochloric acid buffer, and Tris-hydrochloric acid buffer; the pH value of the pH buffer solution is independently 6.6 to 7.4; and the concentration of the pH buffer solution is independently 0.05 to 30 mol / L.

[0016] Preferably, the precursor MAX comprises Ti3AlC2, Ti2AlC, Ta4AlC3, TiNbAlC, (V 0.5 Cr 0.5 )3AlC2, V2AlC, Nb2AlC, Nb4AlC3, Ti3AlCN, Ti3SiC2, Ti2SiC, Ta4SiC3, TiNbSiC, (V 0.5 Cr 0.5 One or more of 3SiC2, V2SiC, Nb2SiC, Nb4SiC3 and Ti3SiCN.

[0017] Preferably, the solute of the cationic surfactant solution comprises one or more of tetramethylammonium acetate, tetraethylammonium bromide, tetrabutylammonium fluoride, and tetramethylammonium chloride, and the solvent comprises one or more of water, anhydrous ethanol, acetone, methanol, toluene, butanone, and ethyl acetate; the mass percentage concentration of the cationic surfactant solution is 0.01-90%.

[0018] Preferably, in step (3), the mass-to-volume ratio of the precursor MAX and the cationic surfactant solution is 1 g: 100-300 mL; and the mixing time is 0.1-48 h.

[0019] Preferably, in step (4), negatively charged nano-silicon@SiO x The mass ratio of positively charged MXene to negatively charged silicon nanoparticles (SiO2) is 1–4:0.5–1. x The ratio of the total mass of positively charged MXene to the volume of the pH buffer solution is 1.5–5 g : 100–1000 mL; the mixing time is 0.1–48 h.

[0020] This invention provides the above-described nano-silicon@SiO x Nano-silicon@SiO₂ prepared by the preparation method of MXene composite anode material x / MXene composite anode material.

[0021] The beneficial effects of this invention are:

[0022] (1) Preparation of nano-silicon@SiO in this invention x The method for producing MXene composite anode materials is simple to operate and easy to scale up for production. It can not only effectively solve the problem of difficult recycling of silicon cutting waste in the photovoltaic industry, but also prepare high-performance silicon-based anode materials.

[0023] (2) This invention uses surface modification technology to attach positively charged groups to the surface of MXene, and uses surface oxidation treatment to attach a uniform silicon suboxide buffer layer to the surface of silicon cutting waste. The zeta potential of silicon suboxide is different at different pH values ​​(the isoelectric point of SiO2 is pH=2.99, and the zeta potential is negative at pH>2.99, exhibiting electronegativity). Electrostatic self-adsorption of nano-silicon@SiO2 is achieved by utilizing the mutual attraction of positive and negative charges. x Inserted into sheet-like MXene, effectively embedded nano-silicon@SiO3 within the MXene structure x This not only increases the conductivity of silicon-based materials, but also effectively alleviates the problem of volume expansion during the charging and discharging process of Si.

[0024] (3) This invention uses surface modification technology to prepare silicon cutting waste into a novel silicon-based anode material with nanostructure, which can effectively overcome the problems of volume expansion and poor conductivity of silicon material during the charging and discharging process of lithium-ion batteries, and significantly improve the electrochemical performance of silicon-based anode material. Attached Figure Description

[0025] Figure 1 Nano-silicon@SiO prepared in Example 1 x / Ti2C3 composite anode material, nano-silicon@SiO x Electrochemical performance test graphs of Ti2C3;

[0026] Figure 2 Nano-silicon@SiO prepared in Example 1 x / Ti2C3 composite anode material, nano-silicon@SiO x XRD diffraction spectra of Ti2C3;

[0027] Figure 3 Nano-silicon@SiO prepared in Example 1 x Electron micrograph of the MXene composite anode material;

[0028] Figure 4 Nano-silicon@SiO prepared in Example 2 x Electron micrograph of the MXene composite anode material;

[0029] Figure 5 Nano-silicon@SiO prepared in Example 3 x Electron micrograph of the MXene composite anode material. Detailed Implementation

[0030] This invention provides a nano-silicon@SiO x The preparation method of / MXene composite anode material includes the following steps:

[0031] (1) Oxidize silicon cutting waste to obtain nano-silicon@SiO x ;

[0032] (2) Nano-silicon@SiO x When mixed with a pH buffer solution, negatively charged nano-silicon@SiO₂ is obtained. x ;

[0033] (3) The precursor MAX was etched to obtain MXene. MXene was mixed with a cationic surfactant solution to obtain positively charged MXene.

[0034] (4) Negatively charged nano-silicon@SiO x Positively charged MXene and pH buffer solution were mixed to obtain nano-silicon@SiO. x / MXene composite anode material.

[0035] In this invention, in step (1), the oxidation process is carried out in an oxidizing atmosphere, which is an air atmosphere or an oxygen atmosphere, preferably an oxygen atmosphere.

[0036] In this invention, the oxidation treatment temperature is 100-1500℃, preferably 200-1200℃, more preferably 300-1000℃, and the oxidation treatment time is 0.1-48h, preferably 1-40h, more preferably 3-30h.

[0037] In this invention, in step (2), nano-silicon@SiO x The mass-to-volume ratio of the pH buffer solution is 1–5 g: 100–1000 mL, preferably 2–4 g: 150–800 mL, and more preferably 3 g: 200–600 mL.

[0038] In this invention, in step (2), mixing is preferably carried out under stirring conditions, with a stirring speed of 50 to 3000 rpm, preferably 200 to 1000 rpm, and more preferably 300 to 800 rpm; the mixing time is 0.1 to 48 h, preferably 5 to 40 h, and more preferably 10 to 30 h.

[0039] In this invention, the pH buffer solution independently comprises one or more of the following: phosphate buffer, glycine-hydrochloric acid buffer, phthalic acid-hydrochloric acid buffer, disodium hydrogen phosphate-citric acid buffer, citrate-sodium hydroxide-hydrochloric acid buffer, citrate-sodium citrate buffer, acetic acid-sodium acetate buffer, potassium dihydrogen phosphate-sodium hydroxide buffer, sodium barbital-hydrochloric acid buffer, and Tris-hydrochloric acid buffer, preferably phosphate buffer, disodium hydrogen phosphate-citric acid buffer, citrate-sodium hydroxide-hydrochloric acid buffer, citrate-sodium citrate buffer, and acetic acid-sodium acetate buffer. The pH buffer solution comprises one or more of the following: acid-sodium acetate buffer, potassium dihydrogen phosphate-sodium hydroxide buffer, and sodium barbital-hydrochloric acid buffer; more preferably, one or more of the following: phosphate buffer, disodium hydrogen phosphate-citric acid buffer, acetate-sodium acetate buffer, and potassium dihydrogen phosphate-sodium hydroxide buffer; the pH value of the pH buffer solution is independently 6.6 to 7.4, preferably 6.6 or 7.4; the concentration of the pH buffer solution is independently 0.05 to 30 mol / L, preferably 0.1 to 20 mol / L, more preferably 1 to 10 mol / L.

[0040] In this invention, the precursor MAX comprises Ti3AlC2, Ti2AlC, Ta4AlC3, TiNbAlC, (V 0.5 Cr 0.5 )3AlC2, V2AlC, Nb2AlC, Nb4AlC3, Ti3AlCN, Ti3SiC2, Ti2SiC, Ta4SiC3, TiNbSiC, (V 0.5 Cr 0.5 The active ingredient is one or more of Ti3AlC2, V2SiC, Nb2SiC, Nb4SiC3 and Ti3SiCN, preferably one or more of Ti3AlC2, Ti2AlC, Ta4AlC3, Ti3AlCN, Ti3SiC2, Ti2SiC and Ta4SiC3, and more preferably one or more of Ti3AlC2, Ta4AlC3, Ti2AlC, Ti3SiC2 and Ti2SiC.

[0041] In this invention, lithium fluoride and hydrochloric acid are preferably mixed and then added to the precursor MAX for etching to obtain MXene; the mass-to-volume ratio of lithium fluoride to hydrochloric acid is 1-2 g: 20-40 mL, preferably 1.2-1.8 g: 25-35 mL; the concentration of hydrochloric acid is 10-15 mol / L, preferably 11-14 mol / L, more preferably 12-13 mol / L; the mass-to-volume ratio of precursor MAX to hydrochloric acid is 1 g: 20-40 mL, preferably 1 g: 25-35 mL; the etching is carried out under stirring conditions, the stirring speed is 100-500 rpm, preferably 200-400 rpm, more preferably 300 rpm; the etching time is 20-28 h, preferably 22-26 h, more preferably 23-25 ​​h.

[0042] In this invention, the solute of the cationic surfactant solution comprises one or more of tetramethylammonium acetate, tetraethylammonium bromide, tetrabutylammonium fluoride, and tetramethylammonium chloride, preferably one or more of tetramethylammonium acetate, tetraethylammonium bromide, and tetramethylammonium chloride, more preferably tetramethylammonium acetate and / or tetramethylammonium chloride; the solvent comprises one or more of water, anhydrous ethanol, acetone, methanol, toluene, butanone, and ethyl acetate, preferably one or more of water, anhydrous ethanol, and ethyl acetate, more preferably water; the mass percentage concentration of the cationic surfactant solution is 0.01-90%, preferably 1-50%, more preferably 5-15%.

[0043] In this invention, in step (3), the mass-to-volume ratio of the precursor MAX and the cationic surfactant solution is 1g:100-300mL, preferably 1g:150-250mL, and more preferably 1g:200mL; the mixing is preferably carried out under stirring conditions, with a stirring speed of 50-3000rpm, preferably 200-1000rpm, and more preferably 300-800rpm; the mixing time is 0.1-48h, preferably 3-40h, and more preferably 10-30h.

[0044] In this invention, in step (4), negatively charged nano-silicon@SiO x The mass ratio of the positively charged MXene to the negatively charged silicon nanoparticles is 1–4:0.5–1, preferably 1.5–3.5:0.6–0.9, and more preferably 1.8–3.0:0.7–0.8; xThe ratio of the total mass of positively charged MXene to the volume of the pH buffer solution is 1.5–5 g: 100–1000 mL; the mixing is preferably carried out under stirring conditions, with a stirring speed of 50–3000 rpm, preferably 200–1000 rpm, and more preferably 300–800 rpm; the mixing time is 0.1–48 h, preferably 5–40 h, and more preferably 10–30 h.

[0045] This invention provides the above-described nano-silicon@SiO x Nano-silicon@SiO₂ prepared by the preparation method of MXene composite anode material x / MXene composite anode material.

[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] Silicon cutting waste was placed in a muffle furnace, oxygen was introduced, and it was oxidized at 300°C for 48 hours to obtain nano-silicon@SiO. x ; 3g of nano-silicon@SiO x Dispersed in 200 mL of phosphate buffer (0.05 mol / L, pH 6.6), and stirred at 300 rpm for 24 h, negatively charged nano-silicon@SiO₂ was obtained. x .

[0049] 1.2 g of lithium fluoride and 25 mL of hydrochloric acid (concentration of 12 mol / L) were mixed and stirred at 300 rpm for 3 h. Then, 1 g of precursor Ti3AlC2 was added and stirred at 300 rpm for 24 h for etching. After washing with deionized water, Ti3C2 was obtained by vacuum filtration. Ti3C2 was mixed with 100 mL of tetramethylammonium acetate aqueous solution (concentration of 15%) and stirred at 300 rpm for 3 h. Finally, Ti3C2 was washed with deionized water and filtered to obtain positively charged Ti3C2.

[0050] 2.5g of negatively charged nano-silicon@SiO x 0.8 g of positively charged Ti3C2 and 200 mL of phosphate buffer (0.05 mol / L, pH 6.6) were mixed and stirred at 300 rpm for 12 h. Finally, the mixture was vacuum filtered to obtain nano-silicon@SiO2. x / Ti3C2 composite anode material.

[0051] Example 2

[0052] Silicon cutting waste was placed in a muffle furnace, oxygen was introduced, and it was oxidized at 800℃ for 10 hours to obtain nano-silicon@SiO. x ; 5g of nano-silicon@SiO x Dispersed in 500 mL of potassium dihydrogen phosphate-sodium hydroxide buffer (concentration 0.05 mol / L, pH 7.4), and stirred at 800 rpm for 48 h, negatively charged nano-silicon@SiO₂ was obtained. x .

[0053] 1.2 g of lithium fluoride and 25 mL of hydrochloric acid (concentration of 12 mol / L) were mixed and stirred at 800 rpm for 3 h. Then, 1 g of precursor Ta4AlC3 was added and stirred at 800 rpm for 48 h for etching. After washing with deionized water, Ta4C3 was obtained by vacuum filtration. Ta4C3 was mixed with 200 mL of tetramethylammonium chloride aqueous solution (concentration of 30%) and stirred at 800 rpm for 48 h. Finally, it was washed with deionized water and filtered to obtain positively charged Ta4C3.

[0054] 1.0g of negatively charged nano-silicon@SiO x 0.5 g of positively charged Ta₄C₃ and 100 mL of potassium dihydrogen phosphate-sodium hydroxide buffer (concentration 0.05 mol / L, pH 7.4) were mixed and stirred at 800 rpm for 24 h. Finally, the mixture was vacuum filtered to obtain nano-silicon@SiO₂. x / Ta4C3 composite anode material.

[0055] Example 3

[0056] Silicon cutting waste was placed in a muffle furnace, oxygen was introduced, and it was oxidized at 1500℃ for 1 hour to obtain nano-silicon@SiO. x ; 1g of nano-silicon@SiO x Dispersed in 100 mL of phosphate buffer (0.05 mol / L, pH 6.6), and stirred at 500 rpm for 5 h, negatively charged nano-silicon@SiO₂ was obtained. x .

[0057] 1.2 g of lithium fluoride and 25 mL of hydrochloric acid (concentration of 12 mol / L) were mixed and stirred at 500 rpm for 3 h. Then, 1 g of precursor Ti3SiC2 was added and stirred at 500 rpm for 5 h for etching. After washing with deionized water, Ti3C2 was obtained by vacuum filtration. Ti3C2 was then mixed with 300 mL of tetraethylammonium bromide aqueous solution (concentration of 10%) and stirred at 500 rpm for 5 h. Finally, Ti3C2 was washed with deionized water and filtered to obtain positively charged Ti3C2.

[0058] 4.0g of negatively charged nano-silicon@SiO x 1 g of positively charged Ti3C2 and 800 mL of phosphate buffer (0.05 mol / L, pH 6.6) were mixed and stirred at 500 rpm for 5 h. Finally, the mixture was vacuum filtered to obtain nano-silicon@SiO2. x / Ti3C2 composite anode material.

[0059] Performance verification:

[0060] Nano-silicon@SiO prepared in Example 1 x / Ti3C2 composite anode material, nano-silicon@SiO x Electrochemical performance tests were conducted on Ti3C2: The active materials (nano-silicon@SiO2) were mixed at a mass ratio of 3:1:1. x / Ti3C2 composite anode material, nano-silicon@SiO x A slurry with a solid content of 50% was obtained by mixing Ti3C2, carbon black, sodium alginate binder, and deionized oil. The slurry was then uniformly coated onto copper foil (a 12mm diameter disc with a coating thickness of 50μm). After coating, the foil was dried in a vacuum oven at 80℃ for 12 hours to obtain the working electrode. Lithium metal foil and polyethylene film served as the counter electrode and separator, respectively. The electrolyte was a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC:DEC = 1:1), with a LiPF6 concentration of 1 mol / L. Electrochemical testing was performed on all batteries at different current densities (Li / Li ratio comparison) within a voltage range of 2.0–0.01V using an electrochemical testing system (XWJ Neware Tech.Co., BTS3000, China). + The test was conducted according to the national standard SJ / T11807-2022, with a charge-discharge test performed at a current density of 0.5 A / g. The test results are as follows. Figure 2 As shown, using nano-silicon@SiO x Lithium-ion batteries made with Ti3C2 composite anode material as the active material exhibit an initial discharge capacity of 2085.592 mAh / g and an initial coulombic efficiency of 77.6%. After 200 cycles, the reversible capacity is 1205.467 mAh / g, with a capacity retention of 57.8%. This demonstrates the effectiveness of nano-silicon@SiO2. x Batteries made with Ti3C2 composite anode materials show significantly improved electrochemical performance and cycle stability; through Figure 3 The XRD diffraction spectrum shows a decrease in the intensity of the silicon peak in the nano-silicon@SiOx / Ti3C2 composite anode material. This may be because the oxidation process transforms crystalline silicon into amorphous silicon suboxide, leading to a decrease in the crystallinity of silicon. Figure 4Electron microscopy images show that the Ti3C2 layers have large interlayer voids, and the nano-silicon@SiO2 layers are relatively porous. x Successfully entering the interlayer voids of Ti3C2 can effectively alleviate the problem of silicon particle volume expansion.

[0061] Figure 4 Nano-silicon@SiO prepared in Example 2 x Electron micrograph of the Ta4C3 composite anode material, from Figure 4 It can be seen that the interlayer porosity of Ta4C3 is relatively large, and the nano-silicon@SiO x Successfully entering the interlayer voids of Ta4C3 can effectively alleviate the problem of silicon particle volume expansion.

[0062] Figure 5 Nano-silicon@SiO prepared in Example 3 x Electron micrograph of the Ti3C2 composite anode material, from Figure 5 It can be seen that the interlayer porosity of Ti3C2 is relatively large, and the nano-silicon@SiO x Successfully entering the interlayer voids of Ti3C2 can effectively alleviate the problem of silicon particle volume expansion.

[0063] As can be seen from the above embodiments, the present invention provides a nano-silicon@SiO x The invention relates to a method for preparing MXene composite anode materials, specifically by oxidizing silicon cutting waste to obtain nano-silicon@SiO₂. x Then, nano-silicon@SiO x When mixed with a pH buffer solution, negatively charged nano-silicon@SiO₂ is obtained. x The precursor was MAX etched to obtain MXene. MXene was mixed with a cationic surfactant solution to obtain positively charged MXene. Finally, negatively charged nano-silicon@SiO2 was added. x Positively charged MXene and pH buffer solution were mixed to obtain nano-silicon@SiO. x / MXene composite anode material. This invention solves the problem of difficult recycling of silicon cutting waste, and prepares nano-silicon@SiO x The MXene composite anode material overcomes the problems of volume expansion and poor conductivity of silicon materials during the charging and discharging process of lithium-ion batteries, and significantly improves the electrochemical performance of silicon-based anode materials.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A nano-silicon@SiO x The method for preparing MXene composite anode material is characterized by... Includes the following steps: (1) Oxidize silicon cutting waste to obtain nano-silicon@SiO x ; (2) Nano-silicon@SiO x When mixed with a pH buffer solution, negatively charged nano-silicon@SiO₂ is obtained. x ; (3) The precursor MAX was etched to obtain MXene. MXene was mixed with a cationic surfactant solution to obtain positively charged MXene. (4) Negatively charged nano-silicon@SiO x Positively charged MXene and pH buffer solution were mixed to obtain nano-silicon@SiO. x / MXene composite anode material; The negatively charged nano-silicon@SiO x The mass ratio of positively charged MXene to MXene is 1–4:0.5–1.

2. The nano-silicon@SiO according to claim 1 x The method for preparing MXene composite anode material is characterized by... In step (1), the oxidation process is carried out in an oxidizing atmosphere; the temperature of the oxidation process is 100 to 1500°C, and the time of the oxidation process is 0.1 to 48 hours.

3. The nano-silicon@SiO according to claim 2 x The method for preparing MXene composite anode material is characterized by... In step (2), nano-silicon@SiO x The mass-to-volume ratio of the pH buffer solution is 1–5 g: 100–1000 mL.

4. The nano-silicon@SiO according to any one of claims 1 to 3 x The method for preparing MXene composite anode material is characterized by... In step (2), the mixing time is 0.1 to 48 hours.

5. The nano-silicon@SiO according to claim 4 x The method for preparing MXene composite anode material is characterized by... The pH buffer solution independently comprises one or more of the following: phosphate buffer, glycine-hydrochloric acid buffer, phthalic acid-hydrochloric acid buffer, disodium hydrogen phosphate-citric acid buffer, citrate-sodium hydroxide-hydrochloric acid buffer, citrate-sodium citrate buffer, acetic acid-sodium acetate buffer, potassium dihydrogen phosphate-sodium hydroxide buffer, sodium barbital-hydrochloric acid buffer, and Tris-hydrochloric acid buffer; the pH value of the pH buffer solution is independently 6.6 to 7.4; and the concentration of the pH buffer solution is independently 0.05 to 30 mol / L.

6. The nano-silicon@SiO according to claim 2, 3, or 5 x The method for preparing MXene composite anode material is characterized by... The precursor MAX comprises Ti3AlC2, Ti2AlC, Ta4AlC3, TiNbAlC, (V 0.5 Cr 0.5 )3AlC2, V2AlC, Nb2AlC, Nb4AlC3, Ti3AlCN, Ti3SiC2, Ti2SiC, Ta4SiC3, TiNbSiC, (V 0.5 Cr 0.5 One or more of 3SiC2, V2SiC, Nb2SiC, Nb4SiC3 and Ti3SiCN.

7. The nano-silicon@SiO according to claim 6 x The method for preparing MXene composite anode material is characterized by... The solute of the cationic surfactant solution includes one or more of tetramethylammonium acetate, tetraethylammonium bromide, tetrabutylammonium fluoride, and tetramethylammonium chloride, and the solvent includes one or more of water, anhydrous ethanol, acetone, methanol, toluene, butanone, and ethyl acetate; the mass percentage concentration of the cationic surfactant solution is 0.01-90%.

8. The nano-silicon@SiO according to claim 5 or 7 x The method for preparing MXene composite anode material is characterized by... In step (3), the mass-to-volume ratio of the precursor MAX and the cationic surfactant solution is 1g:100-300mL; the mixing time is 0.1-48h.

9. The nano-silicon@SiO according to claim 8 x The method for preparing MXene composite anode material is characterized by... In step (4), negatively charged nano-silicon@SiO x The ratio of the total mass of positively charged MXene to the volume of the pH buffer solution is 1.5–5 g : 100–1000 mL; the mixing time is 0.1–48 h.

10. The nano-silicon@SiO according to any one of claims 1 to 9 x Nano-silicon@SiO₂ prepared by the preparation method of MXene composite anode material x / MXene composite anode material.

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