Silicon-based negative electrode material and preparation method and application thereof

Abstract

The application discloses a silicon-based negative electrode material and a preparation method and application thereof. The preparation method comprises the following steps: (1) adding an inorganic silicon source into a mixed solution A comprising mesoporous silicon dioxide and a template agent, and performing a sol-gel reaction to prepare silicon dioxide balls; and (2) etching the silicon dioxide balls by using a weak alkaline solution, and the etching time is 2-5 hours to obtain the silicon-based negative electrode material. The preparation method is simple, has high repeatability and is mild in reaction; and the prepared silicon-based negative electrode material well retains the structural integrity of the yolk shell structure, and further obtains excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to a silicon-based anode material, its preparation method, and its application. Background Technology

[0002] In recent years, the rapid development of electric vehicles has driven the advancement of lithium-ion batteries. Commercially available graphite anode materials are increasingly unable to meet the demand for high-energy-density batteries due to their low capacity. Therefore, silicon-based materials have attracted researchers' attention due to their ultra-high specific capacity and safe operating voltage. In recent years, silicon-oxygen-carbon (SiOC) anodes have garnered widespread attention due to their high cycle stability, suitable potential plateau, low cost, and environmental friendliness. However, SiOC anodes still suffer from inherent problems such as low electronic conductivity, low ionic conductivity, and large volume expansion. This leads to a series of issues, such as electrode material fragmentation, loss of electrical contact with the current collector, and excessive SEI growth. These problems severely hinder the commercialization of SiOC-based anodes.

[0003] Over the past few decades, researchers have proposed various methods to address the problems associated with SiOC-based anodes. Common modification strategies include composites with carbon-based materials, nanostructure design, and surface modification. Carbon modification is considered an efficient method for solving problems related to SiOC-based anodes because it can significantly improve the conductivity of SiOC, optimize the electrochemical kinetics of SiOC materials, and partially alleviate the volume expansion of SiOC. However, repeated expansion of SiOC during long-term cycling eventually leads to the breakage and fragmentation of the active material. Nanostructure design can reduce the size of the active material or retain some void space in the active material, thereby mitigating the volume expansion and contraction of SiOC during lithiation and embrittlement. Unfortunately, nanostructured active materials usually have a large specific surface area, leading to extensive contact between the active material and the electrolyte, resulting in excessive SEI growth and reduced ICE. Surface modification to form core-shell or yolk-shell structures can effectively reduce the interfacial contact between the electrode and the electrolyte, thereby minimizing side reactions.

[0004] The yolk-shell structure has attracted widespread attention in numerous scientific research fields due to its unique structural advantages. In the research of silicon-based anodes for lithium-ion batteries, the massive volume expansion of silicon during charging and discharging leads to particle fragmentation and the formation of irregular SEI films. The cavities within the yolk-shell structure can provide space for the volume expansion of silicon, thereby improving structural stability. Traditional yolk-shell structure fabrication processes often involve etching with strong acids or bases to create these cavities, a process that significantly damages the structure and consequently reduces product performance. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the defect in existing silicon-based materials with an eggshell structure, where the structure is damaged, leading to poor electrochemical performance. This invention provides a silicon-based anode material, its preparation method, and its applications. This invention uses an alkaline etching method to prepare a silicon-based anode material with an eggshell structure. This preparation method is simple, highly reproducible, and the reaction is mild. The silicon-based anode material prepared by this invention retains the structural integrity of the eggshell structure well, further resulting in excellent electrochemical performance.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] The inventors of this application creatively use a mild, weakly alkaline solution to etch mesoporous organosilicon spheres, selectively removing the inorganic silica components in the hybrid silica spheres to obtain a unique yolk-shell structure. This structure can better preserve the integrity of the structure, effectively alleviate the structural expansion of silicon-based anode materials, and thus achieve ultra-long cycle stability.

[0008] This invention provides a method for preparing a silicon-based anode material, comprising the following steps:

[0009] (1) An inorganic silicon source was added to a mixed solution A containing mesoporous silica and a template agent to carry out a sol-gel reaction and obtain silica spheres.

[0010] (2) The silicon dioxide spheres are etched using a weak alkaline solution for 2-5 hours to obtain a silicon-based anode material.

[0011] In step (1), the silicon source used for the mesoporous silica can be an organosilicon source.

[0012] The organosilicon source may be selected from one or more of 1,4-bis(triethoxysilyl)benzene (BTEB), 3-methacryloyloxypropyltrimethoxysilane (MPTMOS), 3-mercaptopropyltrimethoxysilane (MPTMS), vinyltriethoxysilane (VTES), 3-aminopropyltriethoxysilane (APTES), phenyltrimethoxysilane (PTMS), and vinyltrimethoxysilane (VTMS), for example, one or more of 1,4-bis(triethoxysilyl)benzene (BTEB) and vinyltriethoxysilane (VTES).

[0013] In step (1), the mesoporous silica can be prepared by the sol-gel method. Preferably, the mesoporous silica is prepared by adding an organosilicon source to a mixed solution B comprising a template agent, a co-solvent, a solvent, and an alkaline catalyst, and carrying out a sol-gel reaction to obtain mesoporous silica.

[0014] In the mixed solution B, the template agent may be selected from dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), hexadecyltrimethylammonium chloride (CTAC), or octadecyltrimethylammonium chloride (STAC), for example, hexadecyltrimethylammonium bromide (CTAB).

[0015] In the mixed solution B, the mass-to-volume ratio of the template agent and the organosilicon source can be (100-3000) mg:1 mL, preferably (300-1000) mg:1 mL, for example 800 mg:1 mL.

[0016] In the mixed solution B, the co-solvent may be selected from one or more of methanol, ethanol, ethylene glycol and isopropanol, such as ethanol.

[0017] In the mixed solution B, the volume ratio of the organosilicon source to the co-solvent can be 1:(20-400), preferably 1:(100-200), for example 1:120.

[0018] In the mixed solution B, the alkaline catalyst may be selected from one or more of ammonia, triethanolamine, triethylamine, and diethylamine, such as ammonia. The concentration of the ammonia is preferably 10-30%, for example, 25%.

[0019] In the mixed solution B, the volume ratio of the organosilicon source to the alkaline catalyst can be 1:(1-40), preferably 1:(1-20), for example 1:4.

[0020] In the mixed solution B, the solvent may be deionized water.

[0021] In the mixed solution B, the volume ratio of the organosilicon source to the solvent can be 1:(50-1000), preferably 1:(100-400), for example 1:280.

[0022] In the mixed solution B, the temperature of the sol-gelation reaction can be 20-40℃, for example 35℃.

[0023] In the mixed solution B, the sol-gelation reaction time can be 5-24 hours, for example, 6 hours or 12 hours.

[0024] In step (1), the template agent in the mixed solution A can be selected from dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), hexadecyltrimethylammonium chloride (CTAC), or octadecyltrimethylammonium chloride (STAC), for example, hexadecyltrimethylammonium bromide (CTAB).

[0025] In step (1), the mass ratio of the mesoporous silica to the template agent in the mixed solution A can be 1:(0.01-1), preferably 1:(0.01-0.5), for example 1:0.04.

[0026] In step (1), the mixed solution A may also include one or more of a co-solvent, a solvent, and an alkaline catalyst.

[0027] In the mixed solution A, the co-solvent may be selected from one or more of methanol, ethanol, ethylene glycol and isopropanol, such as ethanol.

[0028] In the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the co-solvent can be 1g:(4-10)mL, for example, 1g:6mL.

[0029] In the mixed solution A, the alkaline catalyst may be selected from one or more of ammonia, triethanolamine, triethylamine, and diethylamine, such as ammonia. The concentration of the ammonia is preferably 10-30%, for example, 25%.

[0030] In the mixed solution A, the mass-to-volume ratio of the mesoporous silica and the alkaline catalyst can be 1g:(0.1-1)mL, preferably 1g:(0.1-0.5)mL, for example 1g:0.2mL.

[0031] In the mixed solution A, the solvent may be deionized water.

[0032] In the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the solvent can be 1g:(10-20)mL, for example, 1g:14mL.

[0033] In step (1), the inorganic silicon source can be selected from tetraethoxysilane (TEOS) or vinyltriethoxysilane (VTOS).

[0034] In step (1), the mass-to-volume ratio of the mesoporous silica and the inorganic silicon source in the mixed solution A can be 1g:(0.01-1)mL, preferably 1g:(0.1-0.5)mL, for example 1g:0.05mL.

[0035] In step (1), the temperature of the sol-gel reaction in the mixed solution A can be 20-40℃, for example 35℃.

[0036] In step (1), the time for the sol-gelation reaction in the mixed solution A can be 10-24h, for example 12h.

[0037] In step (2), the solute of the weakly alkaline solution may be selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and ammonia water, such as sodium carbonate or sodium bicarbonate.

[0038] In step (2), the solvent for the weakly alkaline solution can be deionized water.

[0039] In step (2), the concentration of the weakly alkaline solution can be 1-5 mol / L, for example 2.4 mol / L.

[0040] In step (2), the etching temperature can be 20-50℃, for example 35℃. Within this range, the etching effect improves with increasing temperature.

[0041] In step (2), the etching time is preferably 2-4 hours, for example 3 hours.

[0042] In this invention, the size of the internal cavity of the eggshell structure can be adjusted by controlling the parameters of the etching process. Within a suitable etching temperature and time range, damage to the product structure or incomplete etching can be effectively avoided.

[0043] In step (2), the etching process may further include a carbon coating operation. After carbon coating, the carbon source carbonizes to form amorphous carbon, which serves to support and protect the material and improve its conductivity.

[0044] The carbon coating may include the following steps: reacting a mixed solution C containing the etched product, resorcinol and formaldehyde, followed by drying and calcination to obtain a silicon-based anode material.

[0045] In the mixed solution C, the mass ratio of the etched product to the resorcinol can be 1:(0.2-0.8), for example, 1:0.47.

[0046] In the mixed solution C, the mass-to-volume ratio of resorcinol and formaldehyde can be (600-800) mg:1 mL, for example, 700 mg:1 mL.

[0047] The mixed solution C may also include surfactants and / or co-solvents.

[0048] The surfactant may be selected from dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), hexadecyltrimethylammonium chloride (CTAC), or octadecyltrimethylammonium chloride (STAC), for example, hexadecyltrimethylammonium bromide (CTAB).

[0049] In the mixed solution C, the mass ratio of the etched product to the surfactant can be 1:(0.2-0.8), for example 1:0.53.

[0050] The co-solvent may be selected from one or more of methanol, ethanol, ethylene glycol and isopropanol, such as ethanol.

[0051] In the mixed solution C, the mass-to-volume ratio of the etched product to the co-solvent can be 1 mg:(150-200) mL, for example, 1 mg:186.7 mL.

[0052] The reaction temperature can be 20-40°C, for example 35°C.

[0053] The reaction time can be 20-30 hours, for example, 24 hours.

[0054] The calcination temperature can be 600-1000℃, for example 800℃.

[0055] The calcination time can be 2-4 hours, for example, 3 hours.

[0056] The present invention also provides a silicon-based anode material, which is prepared by the above-described preparation method.

[0057] In this invention, the porosity of the silicon-based anode material can be greater than 50%.

[0058] In this invention, the average pore size of the silicon-based anode material can be 5-10 nm.

[0059] The present invention provides a silicon-based anode material, wherein the silicon-based anode material has an egg yolk shell structure, comprising a core, an outer shell, and a cavity located between the core and the outer shell; both the core and the outer shell are SiOC.

[0060] In this invention, preferably, the outer side of the outer shell also includes a carbon layer.

[0061] In this invention, the porosity of the silicon-based anode material can be greater than 50%.

[0062] In this invention, the average pore size of the silicon-based anode material can be 5-10 nm.

[0063] This invention also provides the application of the above-mentioned silicon-based anode material in lithium-ion batteries.

[0064] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0065] The reagents and raw materials used in this invention are all commercially available.

[0066] The positive and progressive effects of this invention are as follows:

[0067] This invention employs an alkaline etching method to prepare silicon-based anode materials with an eggshell structure. This preparation method is simple, highly reproducible, and involves a mild reaction. The silicon-based anode material prepared by this invention retains the structural integrity of the eggshell structure well; furthermore, it exhibits excellent electrochemical performance, such as charge specific capacity, coulombic efficiency, and capacity retention. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the synthesis of the silicon-based anode material in Example 1.

[0069] Figure 2 This is a SEM image of the silicon-based anode material prepared in Example 1.

[0070] Figure 3 This is a TEM image of the silicon-based anode material prepared in Example 1.

[0071] Figure 4 Here is a structural characterization diagram of the silicon-based anode material prepared in Example 1; wherein, Figure 4 Part 'a' in the diagram is the X-ray diffraction pattern. Figure 4 Part b in the image is the Fourier transform infrared spectrum. Figure 4 Part c in the image is the Raman spectrum. Figure 4 Part d in the diagram is a thermogravimetric analysis chart. Figure 4 Part 'e' in the diagram represents the nitrogen adsorption-desorption isotherm. Figure 4 The f part in the diagram is the aperture distribution map.

[0072] Figure 5 The graph shows the rate performance of the silicon-based anode material prepared in Example 1.

[0073] Figure 6 This is a graph showing the long-cycle performance of the silicon-based anode material prepared in Example 1. Detailed Implementation

[0074] The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of these examples. Experimental methods not specifically described in the following examples are performed according to conventional methods and conditions, or as selected according to the product instructions.

[0075] Example 1

[0076] Synthesis of YS-PMOs: 70 mL of deionized water, 30 mL of anhydrous ethanol, and 200 mg of CTAB were added to a three-necked flask. The mixture was stirred at 35 °C for 10 min, and then 1 mL of ammonia (25% by mass) was added. After reacting for 1 h, 0.25 mL of BTEB was added dropwise, and the reaction was continued for 6 h. The resulting solution was centrifuged and dried to obtain approximately 5 g of mesoporous silica. Another 30 mL of anhydrous ethanol, 70 mL of deionized water, and 200 mg of CTAB were added, and the mixture was stirred for 10 min. Then, 1 mL of ammonia (25%) was added, and the mixture was stirred at 35 °C for 1 h. Finally, 0.25 mL of TEOS was added. After reacting for 12 h, the mixture was centrifuged and dried to obtain a core-shell structure. The product was then placed in 30 mL of Na₂CO₃ solution (2.4 M), stirred at 35 °C for 3 h, and centrifuged and dried to obtain the yolk-shell structure YS-PMOs.

[0077] Synthesis of YS@C: Take 1.5g of YS-PMOs, add 280mL of deionized water and 120mL of anionless water. Aqueous ethanol and 800 mg CTAB were reacted. After 10 min, 4 mL of 25% ammonia was added. After 0.5 h, 700 mg resorcinol was added. After another 0.5 h, 1 mL of formaldehyde was added. The mixture was reacted at 35 °C for 24 h, then centrifuged and dried. The mixture was calcined at 800 °C for 3 h in a H2 / Ar mixed atmosphere to obtain YS@C.

[0078] A schematic diagram of the synthesis of silicon-based anode materials is shown below. Figure 1 As shown.

[0079] Example 2

[0080] The only difference from Example 1 is that TEOS is replaced with VTOS.

[0081] Comparative Example 1

[0082] The only difference from Example 1 is that the sodium carbonate etching time is adjusted to 1 hour.

[0083] Comparative Example 2

[0084] The only difference from Example 1 is that the sodium carbonate etching time is adjusted to 6 hours.

[0085] Comparative Example 3

[0086] The only difference from Example 1 is that the sodium carbonate etching time is adjusted to 12 hours.

[0087] Effect Example 1 Morphology

[0088] The morphology of the silicon-based anode materials prepared in Example 1 and Comparative Examples 1-3 was tested.

[0089] The integrity of the structure was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 2 and Figure 3 The images show SEM and TEM images of the silicon-based anode material prepared in Example 1. It can be seen from the images that the silicon-based anode material prepared in this invention has a complete structure, which presents an eggshell structure, including a SiOC core, a cavity, a SiOC shell, and a carbon layer. The carbon layer is on the outside of the SiOC shell.

[0090] The silicon-based anode material prepared by Comparative Example 1 is a solid sphere with only SiOC and carbon layers. The interior is not etched and has no cavity.

[0091] The silicon-based anode material prepared by Comparative Example 2 exhibits an eggshell structure, including a SiOC core, a cavity, a SiOC shell, and a carbon layer. However, the pore etching is relatively large, the cavity volume is large, and the core of the eggshell portion is small. It can be inferred that because the capacity-providing portion is excessively etched, the prepared silicon-based anode material also exhibits poor rate performance.

[0092] The silicon-based anode material prepared by Comparative Example 3 is a hollow sphere with only a SiOC shell and a carbon layer, and the internal organosilicon spheres have been completely etched.

[0093] Example 2: Physicochemical Properties

[0094] The physicochemical properties of Example 1 were tested.

[0095] Depend on Figure 4 It can be seen that YS@C and its intermediate products in the synthesis process are all amorphous.

[0096] X-ray diffraction (XRD) analysis can provide information about crystal structure, such as... Figure 4 As shown in section a, all samples exhibit the characteristics of amorphous diffraction peaks. A large, broad peak appears at 20°–30°, representing the 002 peak of carbon. A weaker, broad peak appears at 40–45°, representing the 100 peak of carbon.

[0097] Fourier transform infrared spectroscopy (FTIR) discovered ( Figure 4 (part b) In YS@C and P@C, the characteristic peak of organic matter in PMOs (3000 cm⁻¹) -1 and 1000cm -1 The disappearance of hydrogen indicates that hydrogen in the organic functional groups was removed during the high-temperature carbonization process.

[0098] Amorphous carbon in YS@C at 1340 cm⁻¹ -1and 1600cm -1 There are two Raman peaks, such as Figure 4 Part c is shown in the diagram. The peak values ​​of the D and G bands can be used to characterize the degree of graphitization of carbon materials. Calculations show that the degree of graphitization (ID / IG) of YS@C is 0.93. The reason for this phenomenon may be that the carbon in YS@C originates from BTEB and TEOS, where BTEB contains phenyl groups. During carbonization, the carbon atoms on the phenyl groups exhibit sp... 2 Hybridization is beneficial for the formation of graphitic carbon. YS@C loses a significant amount of SiO2 generated from the hydrolysis of TEOS during the etching process, resulting in a high degree of graphitization.

[0099] The carbon content of the sample was further measured using thermogravimetric analysis, such as... Figure 4 As shown in section d, YS@C has a carbon content of 75.51%. The carbon in YS@C comes from two sources: the outermost coating of phenolic resin and siloxane (styrene).

[0100] Furthermore, to investigate the surface condition of YS@C, we performed nitrogen adsorption-desorption (BET) tests on the samples. The stability of the structure can be reflected by measuring specific surface area and porosity (BET). Figure 4 As shown in part e, the material belongs to type IV curves, and the hysteresis loop is H4, indicating the presence of irregular slit pores and macropores.

[0101] The specific surface area of ​​YS@C is 17.041 m². 2 g -1 Mesopores were analyzed based on the Barret-Joyner-Halenda model. Figure 4 (in the f part), the average pore size of YS@C is 2.371.

[0102] Example 3: Electrochemical Performance

[0103] The electrochemical performance of the silicon-based anode material prepared in Example 1 was tested.

[0104] (1) Button cell manufacturing

[0105] Silicon-based anode material, conductive carbon black (SP), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were weighed out in a mass ratio of 94.5:1.5:1.5:1.5. The mixture was stirred evenly in water to prepare an anode slurry, which was then evenly coated onto copper foil using a coater to obtain the electrode sheet. The coated electrode sheet was placed in a vacuum drying oven at 110°C and vacuum dried for 4 hours before being pressed into a negative electrode. Simulated coin cell assembly was performed in an argon-filled Braun glove box from Germany. The electrolyte was 1M LiPF6 + EC:EMC:DMC = 1:1:1 (volume ratio), and a lithium metal sheet was used as the counter electrode.

[0106] (2) Electrochemical performance testing

[0107] Rate performance test: Take a button cell prepared above and cycle it five times at current densities of 0.1A / g, 0.2A / g, 0.5A / g, 1A / g and 2A / g in sequence, and then cycle it five times at a current density of 0.1A / g. Detect the charging specific capacity, coulombic efficiency and capacity retention.

[0108] The test results for charging specific capacity are as follows: Figure 5 As shown, the black circles and gray circles represent the discharge capacity and charge capacity, respectively.

[0109] Long-cycle performance test: Take two button batteries prepared above, first cycle them five times at a current density of 0.1 A / g, then cycle them 1000 times at current densities of 0.5 A / g and 1 A / g respectively, and test the charging specific capacity, coulombic efficiency and capacity retention.

[0110] The test results for charge specific capacity and coulombic efficiency are as follows: Figure 6 As shown.

[0111] The test results are shown in Table 1 below.

[0112] Table 1

[0113]

[0114] As shown in the table above, the silicon-based anode material prepared by this invention can still maintain a high charge specific capacity, coulombic efficiency and capacity retention rate as the current density increases, indicating that the silicon-based anode material of this invention has excellent rate performance.

[0115] Furthermore, when the current density reaches 0.5 A g -1 and 1Ag -1 When the silicon-based anode material of the present invention undergoes long-term cycling, it can still maintain stable electrochemical performance; after 1000 cycles, it can still maintain high charge specific capacity, coulombic efficiency and capacity retention.

Claims

1. A method for preparing a silicon-based anode material, characterized in that, It includes the following steps: (1) An inorganic silicon source is added to a mixed solution A containing mesoporous silica and a template agent, and a sol-gel reaction is carried out to obtain silica spheres; the mesoporous silica is obtained by the following method: an organosilicon source is added to a mixed solution B containing a template agent, a cosolvent, a solvent and an alkaline catalyst, and a sol-gel reaction is carried out to obtain mesoporous silica; (2) The silicon dioxide spheres are etched with a weak alkaline solution for 2-5 hours to obtain a silicon-based anode material, wherein the concentration of the weak alkaline solution is 1-5 mol / L; The silicon-based anode material has an egg yolk shell structure.

2. The method for preparing the silicon-based anode material as described in claim 1, characterized in that, In step (1), the template agent in the mixed solution A is selected from one or more of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride and octadecyltrimethylammonium chloride; And / or, in step (1), the mass ratio of the mesoporous silica to the template agent in the mixed solution A is 1:(0.01-1); And / or, in step (1), the mixed solution A further includes one or more of a co-solvent, a solvent, and an alkaline catalyst; And / or, in step (1), the inorganic silicon source is selected from tetraethoxysilane or vinyltriethoxysilane; And / or, in step (1), the mass-to-volume ratio of the mesoporous silica and the inorganic silicon source in the mixed solution A is 1 g:(0.01-1) mL; And / or, in step (1), the temperature of the sol-gelation reaction in the mixed solution A is 20-40°C; And / or, in step (1), the sol-gelation reaction time in the mixed solution A is 10-24 h.

3. The method for preparing the silicon-based anode material as described in claim 2, characterized in that, In step (1), the template agent in the mixed solution A is selected from hexadecyltrimethylammonium bromide; And / or, in the mixed solution A, the mass ratio of the mesoporous silica to the template agent is 1:(0.01-0.5); And / or, in the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the inorganic silicon source is 1 g:(0.1-0.5) mL.

4. The method for preparing the silicon-based anode material as described in claim 2, characterized in that, In the mixed solution A, the co-solvent is selected from one or more of methanol, ethanol, ethylene glycol, and isopropanol; And / or, in the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the co-solvent is 1 g:(4-10) mL; And / or, in the mixed solution A, the alkaline catalyst is selected from one or more of ammonia, triethanolamine, triethylamine, and diethylamine; And / or, in the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the alkaline catalyst is 1 g:(0.1-1) mL; And / or, in the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the solvent is 1 g:(10-20) mL.

5. The method for preparing the silicon-based anode material as described in claim 4, characterized in that, In the mixed solution A, the co-solvent is selected from ethanol; And / or, in the mixed solution A, the alkaline catalyst is selected from ammonia water; And / or, in the mixed solution A, the mass-to-volume ratio of the mesoporous silica to the alkaline catalyst is 1 g:(0.1-0.5) mL.

6. The method for preparing the silicon-based anode material as described in claim 4, characterized in that, The concentration of the ammonia water is 10-30%.

7. The method for preparing the silicon-based anode material as described in claim 6, characterized in that, The concentration of the ammonia water is 25%.

8. The method for preparing the silicon-based anode material as described in claim 1, characterized in that, The organosilicon source is selected from one or more of 1,4-bis(triethoxysilyl)benzene, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, and vinyltrimethoxysilane; And / or, in the mixed solution B, the template agent is selected from dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, or octadecyltrimethylammonium chloride; And / or, in the mixed solution B, the mass-to-volume ratio of the template agent and the organosilicon source is (100-3000) mg: 1 mL; And / or, in the mixed solution B, the co-solvent is selected from one or more of methanol, ethanol, ethylene glycol and isopropanol; And / or, in the mixed solution B, the volume ratio of the organosilicon source to the co-solvent is 1:(20-400); And / or, in the mixed solution B, the alkaline catalyst is selected from one or more of ammonia, triethanolamine, triethylamine, and diethylamine; And / or, in the mixed solution B, the volume ratio of the organosilicon source to the alkaline catalyst is 1:(1-40); And / or, in the mixed solution B, the volume ratio of the organosilicon source to the solvent is 1:(50-1000); And / or, in the mixed solution B, the temperature of the sol-gelation reaction is 20-40°C; And / or, in the mixed solution B, the sol-gelation reaction time is 5-24 h.

9. The method for preparing the silicon-based anode material as described in claim 8, characterized in that, The organosilicon source is selected from 1,4-bis(triethoxysilyl)benzene or vinyltriethoxysilane; And / or, in the mixed solution B, the template agent is selected from hexadecyltrimethylammonium bromide; And / or, in the mixed solution B, the mass-to-volume ratio of the template agent and the organosilicon source is (300-1000) mg: 1 mL; And / or, in the mixed solution B, the co-solvent is selected from ethanol; And / or, in the mixed solution B, the volume ratio of the organosilicon source to the co-solvent is 1:(100-200); And / or, in the mixed solution B, the alkaline catalyst is selected from ammonia water; And / or, in the mixed solution B, the volume ratio of the organosilicon source to the alkaline catalyst is 1:(1-20); And / or, in the mixed solution B, the volume ratio of the organosilicon source to the solvent is 1:(100-400).

10. The method for preparing the silicon-based anode material as described in claim 9, characterized in that, The concentration of the ammonia water is 10-30%.

11. The method for preparing the silicon-based anode material as described in claim 10, characterized in that, The concentration of the ammonia water is 25%.

12. The method for preparing the silicon-based anode material as described in claim 1, characterized in that, In step (2), the solute of the weakly alkaline solution is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and ammonia water; And / or, in step (2), the concentration of the weakly alkaline solution is 2.4 mol / L; And / or, in step (2), the etching temperature is 20-50°C; And / or, in step (2), the etching time is 2-4 hours; And / or, in step (2), the etching process may further include a carbon coating operation.

13. The method for preparing the silicon-based anode material as described in claim 12, characterized in that, In step (2), the solute of the weakly alkaline solution is selected from sodium carbonate or sodium bicarbonate; And / or, in step (2), the etching temperature is 35°C; And / or, in step (2), the etching time is 3 hours; And / or, the carbon coating includes the following steps: reacting a mixed solution C comprising the etched product, resorcinol and formaldehyde, followed by drying and calcination to obtain a silicon-based anode material.

14. The method for preparing the silicon-based anode material as described in claim 13, characterized in that, In the mixed solution C, the mass ratio of the etched product to the resorcinol is 1:(0.2-0.8); And / or, in the mixed solution C, the mass-to-volume ratio of the resorcinol and the formaldehyde is (600-800) mg: 1 mL; And / or, the mixed solution C further includes a surfactant and / or a cosolvent; And / or, the temperature of the reaction is 20-40°C; And / or, the reaction time is 20-30 hours; And / or, the calcination temperature is 600-1000℃; And / or, the calcination time is 2-4 hours.

15. The method for preparing the silicon-based anode material as described in claim 14, characterized in that, In the mixed solution C, the mass ratio of the etched product to the resorcinol is 1:0.47; And / or, in the mixed solution C, the mass-to-volume ratio of the resorcinol and the formaldehyde is 700 mg: 1 mL; And / or, the surfactant is selected from dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride or octadecyltrimethylammonium chloride; And / or, in the mixed solution C, the mass ratio of the etched product to the surfactant is 1:(0.2-0.8); And / or, the co-solvent is selected from one or more of methanol, ethanol, ethylene glycol and isopropanol; And / or, in the mixed solution C, the mass-to-volume ratio of the etched product to the co-solvent is 1 mg:(150-200) mL.

16. The method for preparing the silicon-based anode material as described in claim 15, characterized in that, The surfactant is selected from hexadecyltrimethylammonium bromide; And / or, in the mixed solution C, the mass ratio of the etched product to the surfactant is 1:0.53; And / or, the cosolvent is selected from ethanol; And / or, in the mixed solution C, the mass-to-volume ratio of the etched product to the co-solvent is 1 mg: 186.7 mL.

17. A silicon-based anode material, characterized in that, It is prepared by any one of the preparation methods as described in claims 1-16.

18. The silicon-based anode material as described in claim 17, characterized in that, The porosity of the silicon-based anode material is greater than 50%; And / or, the average pore size of the silicon-based anode material is 5-10 nm.

19. A silicon-based anode material, characterized in that, The silicon-based anode material has an eggshell structure, comprising a core, an outer shell, and a cavity between the core and the outer shell; both the core and the outer shell are SiOC; the outer side of the outer shell also includes a carbon layer; the porosity of the silicon-based anode material is greater than 50%; the average pore size of the silicon-based anode material is 5-10 nm.

20. The application of a silicon-based anode material as described in any one of claims 17-19 in a lithium-ion battery.

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