Silicon-based negative electrode material based on metal oxide coating as well as preparation and application of silicon-based negative electrode material

Abstract

The invention relates to a silicon-based negative electrode material based on metal oxide coating and preparation and application thereof, and a preparation method of the material comprises the following steps: S1, putting a silicon-based material into a solvent for ultrasonic dispersion to obtain a uniform suspension; s2, adding a metal oxide precursor into the suspension obtained in S1, and carrying out hydrolysis or condensation reaction to generate a continuous metal oxide coating layer on the surface of the silicon-based material in situ; and S3, after the reaction is finished, centrifugally separating, washing and drying the obtained product to obtain the silicon-based negative electrode material, namely a target product. Compared with the prior art, the method provided by the invention is simple in process, low in cost and good in repeatability, and the obtained coated silicon material has excellent structural stability and electrochemical performance and has a wide application prospect in high-energy-density lithium ion batteries and all-solid-state batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage materials, and relates to a silicon-based negative electrode material coated with metal oxides and preparation and application thereof. BACKGROUND

[0002] With the rapid development of portable electronic devices and electric vehicle industries, the market demand for high energy density lithium ion batteries is increasingly urgent. The actual specific capacity of the currently commercialized graphite negative electrode material has approached its theoretical limit (372 mAh / g), which is difficult to meet the demand of the next generation of high energy density batteries. Silicon material is considered as the most potential new generation of negative electrode material due to its ultra-high theoretical specific capacity (4200 mAh / g), relatively low de-lithiation potential (~0.4V vs. Li / Li + ) and abundant crustal reserves.

[0003] However, the silicon negative electrode material faces many challenges in practical application. The most prominent problem is the serious volume expansion effect in the charging and discharging process. The volume expansion of silicon in the fully lithiated state can reach more than 300%, and this huge volume change will cause the following problems: (1) the mechanical stress generated by repeated expansion and contraction causes the silicon particles to be pulverized and broken; (2) the active material loses electrical contact with the conductive network, causing rapid capacity decay; (3) the solid electrolyte interface (SEI) film is repeatedly broken and reconstructed, continuously consuming electrolyte and active lithium, resulting in reduced coulombic efficiency.

[0004] The instability of the SEI film is another key factor restricting the application of the silicon negative electrode. In the first charging and discharging process, the electrolyte is reduced on the surface of the negative electrode to form the SEI film. An ideal SEI film should have ion conductivity and electronic insulation, which can effectively prevent the further decomposition of the electrolyte. However, the huge volume change of the silicon negative electrode causes the SEI film to be constantly broken, and the newly exposed silicon surface will induce the continuous decomposition of the electrolyte, forming a new SEI film. This "breakage-reconstruction" cycle not only consumes a large amount of lithium ions, but also causes the SEI film to become thicker and thicker, which seriously hinders the transmission of lithium ions, eventually leading to battery performance degradation.

[0005] Studies have shown that the electrochemical window of the electrolyte is the energy interval between its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). When the LUMO is lower than the Fermi energy level of the negative electrode, electrons are injected from the negative electrode into the LUMO of the electrolyte, causing the solvent or lithium salt to be reduced. For the silicon negative electrode, due to its constantly updated surface, this reduction reaction will continue to occur, forming a thick and uneven SEI film. In addition, during the lithium intercalation process of silicon, the outer layer of lithium intercalation forms amorphous Li xThe silicon expands in volume, while the inner layer, which has not yet been intercalated with lithium, does not expand. This results in huge stress inside the particles, causing individual silicon particles to crack and further exacerbating the instability of the SEI film.

[0006] To address these issues, researchers have proposed various modification strategies, including nanostructuring, carbon composites, the development of novel binders, and surface coating. Among these, surface coating technology, by constructing a stable protective layer on the surface of silicon materials, can effectively buffer volume changes and stabilize the SEI film. Inorganic oxides, due to their excellent chemical stability, moderate mechanical strength, and good ionic conductivity, have become ideal coating materials.

[0007] Currently, inorganic oxide coating mainly employs techniques such as atomic layer deposition (ALD), chemical vapor deposition (CVD), and sol-gel methods. While ALD and CVD can achieve highly uniform coating, their equipment costs are high (a single unit can cost millions of yuan), the processes are complex, and the production efficiency is low (each batch can only process up to the gram level), making it difficult to meet the needs of large-scale production. Although the traditional sol-gel method is lower in cost, the precursor hydrolysis rate is difficult to control, which can easily lead to uneven coating or the formation of independent oxide particles. Summary of the Invention

[0008] The purpose of this invention is to provide a silicon-based anode material based on metal oxide coating, its preparation and application. The resulting coated silicon material has excellent structural stability and electrochemical performance, and has broad application prospects in high-energy-density lithium-ion batteries and all-solid-state batteries.

[0009] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing a silicon-based anode material based on metal oxide coating, comprising the following steps: S1. Place the silicon-based material in a solvent and disperse it ultrasonically to obtain a uniform suspension; S2. Add a metal oxide precursor to the suspension obtained in S1 and carry out hydrolysis or condensation reaction to generate a continuous metal oxide coating layer in situ on the surface of the silicon-based material. S3. After the reaction is complete, the product is centrifuged, washed, and dried to obtain the silicon-based anode material, which is the target product.

[0010] Furthermore, the silicon-based material is silicon powder, etc.

[0011] Furthermore, in S1, the ratio of silicon-based material to solvent is (1~5) mg: 1 mL.

[0012] Furthermore, in S2, the metal oxide precursor is a titanium precursor or an aluminum precursor, and the corresponding metal oxide coating layer is titanium oxide or aluminum oxide.

[0013] Furthermore, in S2, when the metal oxide precursor is a titanium precursor, the titanium precursor is titanium isopropoxide or tetrabutyl titanate, and the ratio of the titanium precursor to the silicon-based material is (250-350) μL: 60 mg.

[0014] More preferably, in S2, when the metal oxide precursor is a titanium precursor, the reaction process is as follows: Hexadecylamine was used as a surfactant and mixed with ammonia to form a transparent solution. It was first added to the uniform suspension in S1, and then titanium precursor was added dropwise. The reaction temperature was controlled at 30~50℃, preferably 35~40℃, more preferably 40℃, and the reaction was carried out for 1~3 hours. The mass of the hexadecylamine is 2 to 3 times that of the silicon-based material, and the mass fraction of the ammonia water is 25 to 28%, with the ratio of ammonia water to hexadecylamine being (300 to 400) μL: 160 mg. Preferably, the hexadecylamine is n-hexadecylamine.

[0015] Furthermore, in S2, when the metal oxide precursor is an aluminum precursor, the aluminum precursor is sodium aluminate, and its mass ratio with the silicon-based material is 2~4:1.

[0016] More preferably, in S2, when the metal oxide precursor is an aluminum precursor, the reaction process is as follows: Add sodium aluminate powder to the homogeneous suspension in S1, adjust the pH of the reaction system to 9-11, and react for 1-3 hours under open conditions at 60-80℃.

[0017] Furthermore, in S1, the particle size of the silicon-based material is 50 nm to 10 μm; In S3, the centrifugal separation speed is 8000~12000 rpm, and the drying temperature is 60~80℃.

[0018] In a second aspect, the present invention provides a silicon-based anode material based on metal oxide coating, which is prepared by the preparation method described in the first aspect above and has a core-shell structure, wherein the core layer is a silicon-based material and the shell layer is a 2-20 nm metal oxide coating layer.

[0019] In a third aspect, the present invention provides an application of a silicon-based anode material based on metal oxide coating in lithium-ion batteries or all-solid-state batteries.

[0020] Compared with the prior art, the present invention has the following advantages: 1. The process conditions are mild, the reaction is carried out under normal pressure, and the temperature is controlled within the range of 30~80℃. It does not require harsh conditions such as high temperature and high pressure, the equipment requirements are simple, and the safety is high.

[0021] 2. Low raw material costs: hexadecylamine, titanium isopropoxide, sodium aluminate, etc. are all conventional chemical raw materials that are easy to obtain, which significantly reduces production costs compared to high-end technologies such as ALD.

[0022] 3. The coating thickness is controllable. By adjusting parameters such as the amount of precursor, reaction temperature and time, the coating thickness can be precisely controlled within the range of 2~20nm to meet different application requirements.

[0023] 4. Good coating uniformity: The liquid-phase reaction system ensures full contact between silicon particles and precursors. Combined with appropriate dispersion and stirring conditions, a uniform distribution of the coating layer is achieved.

[0024] 5. The method is highly versatile and applicable to silicon materials with different particle sizes (nanometer to micrometer) and morphologies (spherical, flake, linear, etc.), demonstrating good universality.

[0025] 6. It is easy to scale up production. All process steps can be implemented in conventional chemical equipment, which facilitates the transformation from laboratory scale to industrial production. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the titanium oxide-coated silicon material prepared in Example 1; Figure 2 EDS mapping image of the titanium oxide-coated silicon material prepared in Example 1; Figure 3 This is a scanning electron microscope image of the alumina-coated silicon material prepared in Example 2; Figure 4 EDS mapping image of the alumina-coated silicon material prepared in Example 2; Figure 5 The images show the X-ray powder diffraction patterns of the materials before and after coating. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0029] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0030] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0031] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0032] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0033] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0034] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0035] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0036] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0037] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0039] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0040] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0041] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0042] In the following examples, the hexadecylamine used is n-hexadecylamine (chemical formula C). 16 H 35 N (also known as hexadecylamine) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity of ≥98%.

[0043] Unless otherwise specified, the raw materials or processing techniques are conventional commercially available materials or conventional processing techniques in this field.

[0044] Example 1: Preparation of titanium dioxide-coated silicon material Add 60 mg of commercial silica powder (average particle size 5 μm, purity 99.9%) to a 50 mL scintillation bottle containing 20 mL of anhydrous ethanol. Place the scintillation bottle in an ultrasonic cleaner and ultrasonically disperse for 30 minutes, removing and shaking it every 10 minutes to obtain a uniform gray-black suspension.

[0045] Take another 20 mL scintillation bottle, add 160 mg of hexadecylamine and 400 μL of 28% ammonia solution, place the scintillation bottle in a 35℃ water bath, and stir magnetically for 30 minutes until the hexadecylamine is completely dissolved to form a transparent solution.

[0046] The hexadecylamine solution was added to the scintillation flask containing the silica powder dispersion and mixed thoroughly. 300 μL of titanium isopropoxide was slowly added dropwise at a rate of 50 μL / min using a microsyringe, with magnetic stirring maintained during the addition. After the addition was complete, the scintillation flask was transferred to a 40°C constant temperature water bath, and the reaction was continued with magnetic stirring for 2 hours. During the reaction, the suspension was observed to lighten in color.

[0047] After the reaction was complete, the reaction solution was transferred to a centrifuge tube and centrifuged at 10,000 rpm for 5 minutes, discarding the supernatant. 20 mL of anhydrous ethanol was added to redisperse the mixture, and after sonication for 2 minutes, it was centrifuged again. The washing was repeated three times to thoroughly remove unreacted precursors and surfactants. The final product was dried in a vacuum oven at 70°C for 12 hours to obtain a gray powder of titanium dioxide-coated silicon material.

[0048] Transmission electron microscopy (TEM) revealed that the titanium oxide coating was 8-10 nm thick and uniformly distributed. Energy dispersive spectroscopy (EDS) analysis showed that Ti was uniformly distributed on the silicon particle surface. X-ray diffraction (XRD) analysis indicated that the coating was amorphous, which is beneficial for lithium-ion transport.

[0049] Example 2: Preparation of alumina-coated silicon material 60 mg of silica powder (same batch as in Example 1) was added to a 50 mL scintillation bottle containing 20 mL of deionized water and ultrasonically dispersed for 30 minutes to obtain a stable gray suspension.

[0050] Place the scintillation flask on a magnetic stirrer and adjust the speed to 600 rpm. Add 0.16 g of sodium aluminate powder at once while stirring rapidly; a small number of bubbles will be generated upon addition. Transfer the scintillation flask to a 70°C constant temperature water bath, keeping the flask open (the cap is loose but not fully opened to prevent the solution from splashing out), and continue stirring for 2 hours.

[0051] After the reaction was complete, the reaction solution was transferred to a centrifuge tube and centrifuged at 10,000 rpm for 5 minutes to collect the solid. The solid was washed with deionized water, repeated 4-5 times until the pH of the washing solution was close to neutral (using pH test paper). The product was dried in a vacuum drying oven at 70°C for 12 hours to obtain a light gray powdery alumina-coated silicon material.

[0052] Transmission electron microscopy revealed that the alumina coating was 6-8 nm thick and uniformly dense.

[0053] Example 3: Effect of reaction temperature on titanium dioxide coating Following the method of Example 1, only the water bath temperature was adjusted to 30°C, while other conditions remained unchanged. Product characterization showed that the coating layer thickness was 6-8 nm, with good uniformity, but the coating rate was slow.

[0054] Example 4: Effects of excessively high reaction temperature Following the method in Example 1, the water bath temperature was increased to 50°C, while other conditions remained unchanged. The results showed that titanium dioxide particles agglomerated in localized areas, indicating that excessively high temperatures led to an excessively rapid hydrolysis rate.

[0055] Example 5: Effect of sodium aluminate dosage on coating thickness Following the method in Example 2, the amount of sodium aluminate was reduced to 0.12 g, while other conditions remained unchanged. The coating thickness was reduced to 4-5 nm, but the coating remained uniform, making it suitable for applications requiring a thinner coating.

[0056] Example 6: For coating silicon materials of different particle sizes, nano-sized silicon powder with an average particle size of 100 nm was used instead of micron-sized silicon powder, and the coating was carried out according to the method in Example 1. Due to the increased specific surface area, the amount of titanium isopropoxide was increased to 400 μL. The coating effect was good, proving that the method is universally applicable to silicon materials of different sizes.

[0057] Structural characterization The structure and phase composition of the multi-metal oxide-coated silicon material were characterized below using transmission electron microscopy, EDS mapping, and X-ray powder diffraction. 1. Transmission electron microscopy analysis Figure 1 This is a transmission electron microscope (TEM) image of the titanium oxide-coated silicon material prepared in Example 1. As can be observed from the image, the surface of the coated silicon particles remains smooth and uniform, the titanium oxide coating layer is tightly bonded to the silicon core, and no independent oxide particles are present. The silicon particles retain their original lamellar morphology, and the coating layer is uniformly distributed on the surface of the silicon particles.

[0058] Figure 3 This is a transmission electron microscope image of the alumina-coated silicon material prepared in Example 2. The image shows that the alumina coating layer is uniformly and densely distributed on the surface of the silicon material, with smooth and intact particle surfaces. No coating layer peeling or agglomeration was observed, indicating that the aqueous coating process used can achieve uniform deposition of alumina.

[0059] 2. Energy dispersive spectroscopy (EDS) analysis Figure 2 This is the EDS mapping image of the titanium oxide-coated silicon material prepared in Example 1. The energy dispersive spectroscopy results clearly show that Ti elements are uniformly distributed on the surface of silicon particles, highly consistent with the distribution area of ​​Si elements, confirming the uniformity of the titanium oxide coating layer. Simultaneously, the distribution of O elements also corresponds to that of Ti elements, further verifying the successful preparation of the titanium oxide coating layer.

[0060] Figure 4 The image shows the EDS mapping of the alumina-coated silicon material prepared in Example 2. As can be seen from the image, Al and O elements are uniformly distributed on the surface of the silicon particles, completely overlapping with the distribution area of ​​the silicon core. This indicates that the alumina coating layer is complete and uniformly distributed, with no obvious areas of element enrichment or deficiency.

[0061] 3. X-ray diffraction analysis Figure 5 Obvious characteristic diffraction peaks of silicon (2θ = 28.4°, 47.3°, 56.1°) can be observed, corresponding to the (111), (220), and (311) crystal planes of cubic silicon. In the diffraction patterns of the coated samples (i.e., Examples 1 and 2), the intensity of the characteristic peaks of silicon is slightly reduced, but the peak positions do not change significantly, indicating that the coating process does not change the crystal structure of silicon. In the diffraction patterns of the titanium oxide and aluminum oxide coated samples, no obvious oxide crystal diffraction peaks were observed, indicating that the coating layer is amorphous or nanocrystalline. The amorphous oxide coating layer is beneficial for the rapid transport of lithium ions and can better adapt to the volume changes of silicon materials during charging and discharging.

[0062] Comparative Example 1: Uncoated silicon powder Uncoated raw silicon powder was used as a control sample for characterization analysis under the same conditions.

[0063] Comparative Example 2: Eliminating the influence of surfactants The method of Example 1 was followed, but the addition of hexadecylamine was omitted, while other conditions remained unchanged. Immediately after the addition of titanium isopropoxide, a large amount of precipitate was observed, and the reaction solution quickly became turbid. After the reaction was completed, the product was washed and dried. The surface coating of the silicon particles was uneven, with a large number of independent titanium oxide particle aggregates, with an average particle size of 50-100 nm. The distribution of titanium was extremely uneven, with some areas enriched and others lacking. This comparative example demonstrates that the surfactant hexadecylamine plays a crucial role in controlling the precursor hydrolysis rate and achieving uniform coating.

[0064] Comparative Example 3: Effects of using other surfactants Following the method of Example 1, 160 mg of n-hexadecylamine was replaced with an equal mass of hexadecyltrimethylammonium bromide (CTAB), while other conditions remained unchanged. During the reaction, a significantly accelerated coating formation rate was observed, but the coating uniformity decreased, fluctuating between 6-15 nm, with localized oxide particle aggregation. This comparative example demonstrates that although CTAB is also a surfactant, its effect on regulating the hydrolysis rate of the titanium precursor is not as good as that of n-hexadecylamine, and it cannot achieve the precise control required by this invention.

[0065] Comparative Example 4: Eliminating the impact of ammonia The method of Example 1 was followed, but the addition of ammonia was omitted, and only an ethanol solution of hexadecylamine was used, while other conditions remained unchanged. After 2 hours of reaction, the product was washed and dried, and the surface of the silicon particles showed only a very thin, discontinuous coating layer (thickness <2 nm), which was unevenly distributed, and the Ti content was much lower than in Example 1. This comparative example shows that ammonia, as an alkaline catalyst, is crucial for promoting the complete hydrolysis of the titanium precursor and the formation of the coating layer.

[0066] Comparative Example 5: Traditional sol-gel method for preparing titanium dioxide-coated silicon materials 60 mg of silicon powder was dispersed in 20 mL of anhydrous ethanol. Then, a mixture of 300 μL of titanium isopropoxide and 2 mL of deionized water was added at room temperature, and the mixture was stirred vigorously for 2 hours. During the reaction, the solution rapidly became turbid, and a white precipitate formed. After centrifugation, washing, and drying, the product showed extremely uneven coating on the silicon particles, with a large number of independent titanium dioxide nanoparticles (20-50 nm in diameter) mixed with the silicon powder. The coating thickness fluctuated drastically within the range of 2-30 nm, and some silicon particles were even uncoated. The resulting titanium oxide exhibited anatase crystal structure. This comparative example demonstrates that the traditional sol-gel method, due to the lack of precise control over the hydrolysis rate, struggles to achieve uniform and controllable coating.

[0067] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a silicon-based anode material based on metal oxide coating, characterized in that, Includes the following steps: S1. Place the silicon-based material in a solvent and disperse it ultrasonically to obtain a uniform suspension; S2. Add a metal oxide precursor to the suspension obtained in S1 and carry out hydrolysis or condensation reaction to generate a continuous metal oxide coating layer in situ on the surface of the silicon-based material. S3. After the reaction is complete, the product is centrifuged, washed, and dried to obtain the silicon-based anode material, which is the target product.

2. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 1, characterized in that, In S1, the ratio of silicon-based material to solvent is (1~5) mg: 1 mL.

3. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 1, characterized in that, In S2, the metal oxide precursor is a titanium precursor or an aluminum precursor, and the corresponding metal oxide coating layer is titanium oxide or aluminum oxide.

4. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 3, characterized in that, In S2, when the metal oxide precursor is a titanium precursor, the titanium precursor is titanium isopropoxide or tetrabutyl titanate, and the ratio of the titanium precursor to the silicon-based material is (250-350) μL: 60 mg.

5. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 4, characterized in that, In S2, when the metal oxide precursor is a titanium precursor, the reaction process is as follows: Hexadecylamine was used as a surfactant and mixed with ammonia to form a transparent solution. It was first added to the homogeneous suspension in S1, and then titanium precursor was added dropwise. The reaction temperature was controlled at 30~50℃ and the reaction was carried out for 1~3 hours. The mass of the hexadecylamine is 2 to 3 times that of the silicon-based material, the mass fraction of the ammonia water is 25 to 28%, and the ratio of its addition to the hexadecylamine is (300 to 400) μL: 160 mg.

6. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 3, characterized in that, In S2, when the metal oxide precursor is an aluminum precursor, the aluminum precursor is sodium aluminate, and its mass ratio with the silicon-based material is 2~4:

1.

7. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 6, characterized in that, In S2, when the metal oxide precursor is an aluminum precursor, the reaction process is as follows: Add sodium aluminate powder to the homogeneous suspension in S1, adjust the pH of the reaction system to 9-11, and react for 1-3 hours under open conditions at 60-80℃.

8. The method for preparing a silicon-based anode material based on metal oxide coating according to claim 1, characterized in that, In S1, the particle size of the silicon-based material is 50 nm to 10 μm; In S3, the centrifugal separation speed is 8000~12000 rpm, and the drying temperature is 60~80℃.

9. A silicon-based anode material based on metal oxide coating, characterized in that, It is prepared by the preparation method described in any one of claims 1-8 and has a core-shell structure, wherein the core layer is a silicon-based material and the shell layer is a metal oxide coating layer of 2-20 nm in an amorphous or nanocrystalline state.

10. The application of a silicon-based anode material based on metal oxide coating as described in claim 9 in lithium-ion batteries or all-solid-state batteries.

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