Silicon material surface solid electrolyte membrane and preparation method and application thereof

Abstract

The invention discloses a silicon material surface solid electrolyte membrane and a preparation method and application thereof. The method comprises the following steps: firstly, carrying out hydroxylation treatment on a silicon material by adopting a mixed solution of hydrogen peroxide and concentrated sulfuric acid; then carrying out hydrolytic polymerization reaction on a hydrolyzable silane compound on the hydroxylated surface to form a layer of flexible organic film; and finally, infiltrating with a lithium ion battery electrolyte, and forming a compact solid electrolyte membrane on the surface of the silicon material in situ to obtain a silicon / solid electrolyte integrated structure. And the hydrolysable silane compound comprises alkoxy silane and chlorosilane. The solid electrolyte interface layer which is firm in combination, flexible and ion-conducting is constructed on the surface of the silicon material through a simple three-step method, the problem of volume expansion of the silicon-based negative electrode is effectively solved, and the cycling stability and the capacity retention ratio of the battery are improved. The method is simple in process, low in cost, environment-friendly and easy for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte technology, specifically relating to a solid electrolyte film on the surface of silicon material, its preparation method and application. Background Technology

[0002] Solid-state electrolytes are key materials in solid-state batteries. Serving as an intermediate structure connecting the positive and negative electrode materials, they transport ions and prevent direct contact between the materials. Compared to liquid electrolytes used in current lithium-ion batteries, solid-state electrolytes offer advantages such as fewer side reactions, higher safety, a wider operating temperature range, and better flexibility. These advantages can significantly improve battery safety and energy density, and expand their application scenarios.

[0003] Currently, research on solid electrolytes mainly focuses on systems suitable for lithium metal interfaces. For example, CN202511405151.X discloses a plasma in-situ construction method for a solid electrolyte interface layer for lithium metal anodes. This method uses lithium metal as the reaction matrix and organic-inorganic-alloy component precursors as the reaction source, combining low-pressure, low-temperature plasma technology to in-situ construct an artificial solid electrolyte interface layer with organic-inorganic-alloy gradient stratification on the lithium metal surface. CN202210481420.0 discloses a method for preparing polymer solid electrolytes, mainly optimizing the failure of lithium metal interfaces and lithium dendrite growth. In addition, some studies have focused on inorganic solid electrolytes. For example, CN202511281362.7 discloses a sulfide solid electrolyte that can maintain high ionic conductivity and good air stability, achieving synergistic optimization between mechanical reliability and electrochemical performance. CN202211008437.0 discloses a solid electrolyte with the chemical formula Li-(3+x)M-2PA-4P-2O-7 and its preparation method, wherein x takes the value of 0 to 0.3, M is at least one of Fe, Al, and Ti, and A is at least one of O, S, and Se.

[0004] Research on solid-state electrolytes for silicon anode materials is relatively limited. For example, CN202510871491.5 discloses a solid-state electrolyte-coated silicon-carbon composite material. This method utilizes metal-doped porous carbon, deposits nano-silicon via vapor deposition, and finally coats the surface with a solid-state electrolyte using a liquid-phase method, followed by carbonization to obtain the composite material. However, such methods for preparing solid-state electrolytes for silicon-based anode materials generally suffer from problems such as high raw material costs, complex preparation processes, demanding equipment requirements, harsh process conditions, severe pollution, difficulties in mass production, or electrochemical performance that fails to meet commercial needs, thus hindering industrial application.

[0005] Therefore, there is an urgent need for a solid electrolyte and its preparation method that is suitable for silicon anode materials, has a simple preparation process, and is clean and efficient, in order to promote the practical application of silicon-based solid-state batteries. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by providing a solid electrolyte membrane on the surface of silicon materials, its preparation method, and its application. It aims to solve the problems of poor contact between the interface of existing solid electrolytes and silicon-based anodes, complex processes, high costs, and difficulty in adapting to the large volume expansion of silicon materials.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing a solid electrolyte film on a silicon material surface, comprising the following steps: (1) Hydroxylation treatment: The silicon material is mixed and stirred with a mixed aqueous solution of hydrogen peroxide and sulfuric acid to hydroxylate the surface of the silicon material; (2) Hydrolysis polymerization: The surface hydroxylated silicon material obtained in step (1) is brought into contact with a hydrolyzable silane compound, so that the silane compound undergoes a hydrolysis polymerization reaction on the surface of the silicon material to obtain a silicon material with an organic film on the surface. (3) Electrolyte wetting: The silicon material with an organic film on its surface is contacted and wetted with the lithium-ion battery electrolyte to form the solid electrolyte film on the surface of the silicon material.

[0008] This invention uses a mixed aqueous solution of hydrogen peroxide and sulfuric acid to treat silicon materials. Through thorough mixing and stirring, hydroxyl functional groups are introduced onto the surface of the silicon material to achieve surface hydroxylation. Subsequently, a hydrolyzable silane compound undergoes a hydrolytic polymerization reaction on the hydroxylated silicon surface, thereby forming a flexible organic film. Finally, the silicon material coated with the organic film is immersed in a lithium-ion battery electrolyte. After thorough immersion and interaction, a solid electrolyte film is formed on the surface of the silicon material, resulting in an integrated structure in which the silicon material and the solid electrolyte are tightly bonded together by a dense flexible film.

[0009] Further, in step (1), the silicon material is a silicon wafer or silicon powder, and the silicon powder has a size of nanometer, micrometer or millimeter.

[0010] Further, in step (1), the mixed aqueous solution of hydrogen peroxide and sulfuric acid is obtained by mixing hydrogen peroxide, sulfuric acid, and purified water; the volume ratio of the purified water to the total volume of hydrogen peroxide and sulfuric acid is 0.1:20~50:0.1, for example 0.1:20, 0.1:10, 1:20, 1:10, 1:5, 1:2, 1:1, 10: 1. 15:1, 30:1, 50:1, 50:0.1; preferably 1:5~50:1; the concentration of the hydrogen peroxide is 20%~70%, preferably 30-50%; the concentration of the sulfuric acid is 50%~99.5%; the volume ratio of the hydrogen peroxide to the sulfuric acid is 0.1:20~20:0.1, for example 0.1:20, 0.1:10, 1:20, 1:10, 2:5, 2:1, 5:1, 10:1, 20:1, 20:0.5, 20:0.2, 20:0.1.

[0011] Furthermore, in step (2), the hydrolyzable silane compound is selected from alkoxysilanes or chlorosilanes. Both chlorosilanes and alkoxysilanes can be hydrolyzed to generate silanol intermediates, which can then be polycondensed to form a polymer film with a Si-O-Si backbone. Therefore, both can be used as precursors for forming organic films in this invention.

[0012] Furthermore, the alkoxysilane is selected from one or a combination of several of monofunctional alkoxysilanes, difunctional alkoxysilanes, trifunctional alkoxysilanes, and tetrafunctional alkoxysilanes.

[0013] Furthermore, the alkoxysilane is selected from one or a combination of several of alkyl-type alkoxysilanes, aryl-type alkoxysilanes, and alkoxysilanes containing functional groups.

[0014] Furthermore, the alkoxysilane is selected from one or a combination of several of methoxysilane, ethoxysilane, and propoxysilane.

[0015] Furthermore, the chlorosilane is an alkylchlorosilane; preferably dimethyldichlorosilane or methylchlorosilane.

[0016] Further, in step (2), the hydrolysis polymerization reaction is carried out in the presence of any one or a mixture of at least two of water, water vapor, methanol, ethanol, ethylene glycol or fatty alcohol; preferably in the presence of water and / or ethanol.

[0017] Further, in step (3), the lithium-ion battery electrolyte contains lithium salt and organic solvent; the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate; the organic solvent is selected from one or more of carbonate solvents, ether solvents, and nitrile solvents.

[0018] Further, the hydroxylation treatment in step (1) is performed for 0.05 hours to 20 hours, for example, 0.05h, 0.1h, 0.2h, 0.5h, 1h, 2h, 3h, 5h, 10h, 20h.

[0019] The hydrolysis-polymerization reaction in step (2) takes 0.01 hours to 20 hours, for example, 0.01h, 0.05h, 0.1h, 0.2h, 0.5h, 1h, 2h, 3h, 5h, 10h, 20h; preferably 0.5 hours to 20 hours. The electrolyte soaking time in step (3) is 0.05 hours to 20 hours, for example 0.05h, 0.1h, 0.5h, 1h, 2h, 3h, 5h, 10h, 15h, 20h.

[0020] This invention effectively regulates the chemical composition, thickness, and density of the final solid electrolyte membrane by controlling process parameters such as hydroxylation treatment time, silane compound hydrolysis and polymerization time, electrolyte wetting time, hydrogen peroxide / concentrated sulfuric acid / pure water ratio, type of silane compound, composition of lithium-ion battery electrolyte, and morphology and size of silicon material. Specifically, appropriately extending the hydrolysis and wetting time, or increasing the lithium salt concentration in the electrolyte, generally helps to increase the lithium-ion content and thickness of the solid electrolyte membrane. Furthermore, post-processing techniques can further control the crystallinity, interface structure, and pore characteristics of the membrane.

[0021] The second aspect of the present invention provides a solid electrolyte membrane on a silicon material surface, the membrane being formed on the surface of a silicon substrate by the above method, and having a thickness of 1 nm to 500 μm, for example 10 nm, 50 nm, 100 nm, 300 nm, 500 nm, 1 μm, 30 μm, 80 μm, 170 μm, 300 μm, 400 μm, or 480 μm.

[0022] A third aspect of the present invention provides a silicon / solid electrolyte composite material, comprising a silicon matrix and a solid electrolyte membrane formed on the surface of the silicon matrix, wherein the composite material is prepared by the method described above.

[0023] A fourth aspect of the present invention provides an electrode comprising the above-described silicon / solid electrolyte composite material as an active material.

[0024] A fifth aspect of the present invention provides a battery comprising the electrodes described above.

[0025] Compared with the prior art, the present invention has the following beneficial effects: 1. Excellent interface bonding and high cycle stability: This invention achieves close contact between silicon and electrolyte at the atomic level by constructing a solid electrolyte membrane in situ on the surface of silicon material, forming an integrated composite structure. This flexible solid electrolyte membrane can effectively adapt to and buffer the huge volume expansion of the silicon anode during charging and discharging, thereby significantly improving the electrochemical cycle stability of the battery.

[0026] 2. Simplified process and easy electrode preparation: This method combines the preparation of solid electrolyte membranes with the surface modification of silicon anode materials, achieving integrated preparation of silicon materials and solid electrolytes. This process eliminates the need for subsequent complex electrode coating processes, simplifying the electrode manufacturing process.

[0027] 3. Controllable structure and performance with flexible control methods: By adjusting various process parameters, including raw material ratio, reaction time, and material type, key performance indicators such as the thickness, ionic conductivity, interface structure, and degree of crystallization of the solid electrolyte membrane can be precisely controlled.

[0028] 4. Low overall cost, green and scalable: The raw materials required for the entire production process are readily available, the conditions are mild, the operation is simple, and the environment is friendly. It has the outstanding advantages of low production cost, no pollution, and easy to scale up production. Attached Figure Description

[0029] Figure 1 This is a scanning electron microscope image of the silicon raw material (silicon wafer) used in Example 1 of the present invention.

[0030] Figure 2 The image shows the XRD pattern of the integrated silicon / solid electrolyte material structure prepared in Example 1 of this invention.

[0031] Figure 3 This is a scanning electron microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 1 of the present invention.

[0032] Figure 4 The infrared spectrum of the silicon / solid electrolyte material integrated structure prepared in Example 1 of this invention.

[0033] Figure 5 An atomic force microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 1 of this invention.

[0034] Figure 6 This is a scanning electron microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 2 of the present invention.

[0035] Figure 7 This is a scanning electron microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 3 of the present invention.

[0036] Figure 8This is a scanning electron microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 4 of the present invention.

[0037] Figure 9 This is a scanning electron microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 5 of the present invention. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, it is worth noting that the raw materials involved in the present invention are all commercially available products unless otherwise specified.

[0039] Example 1 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: 5 ml of 30% hydrogen peroxide, 5 ml of 98% concentrated sulfuric acid, and 40 ml of purified water were mixed in a glass beaker to obtain a mixed aqueous solution with a total volume of 50 ml. 5 g of a clean silicon wafer was added to this solution, and the mixture was magnetically stirred at 500 rpm for 10 minutes at room temperature (25°C). After the reaction was complete, the reaction solution was discarded, and the silicon wafer was repeatedly washed 5 times with deionized water until the washing solution was neutral. Then, it was dried in a 60°C oven for 30 minutes to obtain a surface-hydroxylated silicon material.

[0040] (2) Hydrolysis polymerization: Measure 20 ml of dimethyldichlorosilane and 5 ml of anhydrous ethanol, mix them evenly in a beaker to obtain a silane solution. Immerse the surface-hydroxylated silicon material obtained in step (1) into the solution, transfer it to a self-adsorption coating machine, and spin coat it at a speed of 3000 rpm for 1 minute to form a uniform organic film on the silicon wafer surface.

[0041] (3) Electrolyte Immersion: The silicon wafer with an organic thin film coated on its surface obtained in step (2) is completely immersed in a container filled with lithium-ion battery electrolyte. The electrolyte is a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) with 1 mol / L lithium hexafluorophosphate (LiPF6) (volume ratio 1:1). The wafer is allowed to stand at 25°C for 0.5 hours. After immersion, the silicon wafer is removed, and excess liquid droplets are gently wiped off with filter paper to obtain an integrated silicon / solid electrolyte material structure with a solid electrolyte film attached to its surface.

[0042] The surface morphology of the silicon / solid electrolyte material integrated structure prepared in Example 1 was observed using a JSM6700 field emission scanning electron microscope manufactured by Nippon Electronics Corporation; the crystal form of the material was tested using an X′Pert PROMPD multi-functional X-ray diffractometer manufactured by Panalytical in the Netherlands.

[0043] Figure 1 This is a scanning electron microscope image of the silicon raw material (silicon wafer) used in Example 1 of the present invention.

[0044] Figure 2 The image shows the XRD pattern of the integrated silicon / solid electrolyte material structure prepared in Example 1 of this invention.

[0045] Figure 3 This is a scanning electron microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 1 of the present invention.

[0046] Figure 4 The infrared spectrum of the silicon / solid electrolyte material integrated structure prepared in Example 1 of this invention.

[0047] Figure 5 This is an atomic force microscope image of the integrated silicon / solid electrolyte material structure prepared in Example 1 of the present invention.

[0048] from Figure 1 It can be observed that the original silicon wafer has a dense, smooth surface. Figure 3 A flexible thin film can be observed on the silicon surface. XRD patterns before and after solid-state electrolyte fabrication on silicon wafers are shown. Figure 2 The infrared spectrum shows that the crystalline structure of the silicon wafer remains unchanged. The integrated silicon / solid electrolyte material exhibits a wave packet between 20-30 degrees, which is analyzed as a diffraction peak of the polymer solid electrolyte. Figure 4 Organic bonds such as Si-O, CO, C=O, CH, and OH can be observed in polymer solid electrolytes. Figure 5 This is an atomic force microscope image of an integrated silicon / solid electrolyte material structure, from which the flexibility of the solid electrolyte can be observed.

[0049] Example 2 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 1 ml of 30% hydrogen peroxide, 4 ml of 98% concentrated sulfuric acid, and 20 ml of purified water, and mix them in a 50 ml glass beaker to obtain a mixed aqueous solution with a total volume of 25 ml. Add 3 g of silicon powder to this solution and magnetically stir at 500 rpm for 30 minutes at room temperature (25°C). After the reaction is complete, discard the supernatant. Redisperse the precipitated silicon powder with deionized water and centrifuge. Repeat this washing process 5 times until the pH of the supernatant is neutral. Finally, place the silicon powder in a vacuum drying oven at 60°C and dry for 1 hour to obtain surface-hydroxylated silicon powder material.

[0050] (2) Hydrolysis polymerization: Measure 10 ml of dimethyldichlorosilane and 2 ml of anhydrous ethanol, stir and mix them evenly with a glass rod to obtain a silane solution. Add the surface-hydroxylated silicon powder material obtained in step (1) to the solution, so that the silicon powder is fully wetted and contacted with the solution, and then let it stand for 2 minutes to react.

[0051] (3) Electrolyte wetting: Pour the mixture from step (2) into a centrifuge tube and centrifuge at 8000 rpm for 5 minutes. Discard the supernatant to obtain a silicon material with an organic film coating on its surface. Transfer the material to a glass bottle containing 10 ml of lithium-ion battery electrolyte (with the same composition as in Example 1), ensuring that the electrolyte completely submerges the material, and let it stand for 1 hour to wet. After wetting, centrifuge again to separate the materials, discard the excess electrolyte, and obtain an integrated silicon / solid electrolyte material structure.

[0052] The surface morphology of the integrated silicon / solid electrolyte material structure prepared in Example 2 was observed using a JSM6700 field emission scanning electron microscope manufactured by Japan Electronics Corporation. Figure 6 As shown.

[0053] Figure 6 A flexible solid electrolyte film can be observed on the silicon surface.

[0054] Example 3 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 10 ml of 30% hydrogen peroxide, 1 ml of 98% concentrated sulfuric acid, and 20 ml of purified water, and mix them in a 100 ml glass beaker to obtain a mixed aqueous solution with a total volume of 31 ml. Add 10 g of clean silicon wafer to this solution, and magnetically stir at 500 rpm for 50 minutes at room temperature (25°C). After the reaction is complete, rinse the silicon wafer surface 6 times with deionized water, and dry it in an oven at 60°C for 40 minutes to obtain surface-hydroxylated silicon material.

[0055] (2) Hydrolysis polymerization: Measure 30 ml of dimethyldichlorosilane and 5 ml of anhydrous ethanol and mix them. Immerse the surface-hydroxylated silicon material obtained in step (1) completely in the solution and let it stand at 25°C for 30 minutes.

[0056] (3) Electrolyte wetting: The silicon wafer was removed from the silane solution, its surface was rinsed with a small amount of ethanol, and then it was immersed in the electrolyte (the composition is the same as in Example 1) and allowed to stand for 2 hours. After wetting, the silicon wafer was removed to obtain an integrated silicon / solid electrolyte material structure.

[0057] The surface morphology of the silicon / solid electrolyte material integrated structure prepared in Example 3 was observed using a JSM6700 field emission scanning electron microscope manufactured by Japan Electronics Corporation. Figure 7 As shown.

[0058] Figure 7 A flexible solid electrolyte film can be observed on the silicon surface.

[0059] Example 4 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: 1 ml of 30% hydrogen peroxide, 2 ml of 98% concentrated sulfuric acid, and 30 ml of purified water were mixed in a 100 ml glass beaker to obtain a mixed aqueous solution with a total volume of 33 ml. 3 g of a clean silicon wafer was added to this solution, and the mixture was magnetically stirred at 500 rpm for 60 minutes at room temperature (25°C). After the reaction was complete, the wafer was rinsed with deionized water and dried in an oven at 60°C for 45 minutes to obtain a surface-hydroxylated silicon material.

[0060] (2) Hydrolysis polymerization: Measure 5 ml of methylchlorosilane and 1 ml of anhydrous ethanol and mix them evenly. Immerse the surface-hydroxylated silicon material obtained in step (1) into the solution, and then immediately fix it on the sample stage of the self-adsorption coating machine. Set the coating machine speed to 1000 rpm, start the coating program, and spin-coat for 2 minutes to obtain a flexible organic film on the silicon surface.

[0061] (3) Electrolyte wetting: Immerse the silicon wafer treated in step (2) in 15 ml of electrolyte (with the same composition as in Example 1) and let it stand for 1 hour. After wetting, remove the silicon wafer and drain the excess electrolyte to obtain an integrated silicon / solid electrolyte material structure.

[0062] The surface morphology of the silicon / solid electrolyte material integrated structure prepared in Example 4 was observed using a JSM6700 field emission scanning electron microscope manufactured by Japan Electronics Corporation. Figure 8 As shown.

[0063] Figure 8 A flexible solid electrolyte film can be observed on the silicon surface.

[0064] Example 5 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 20 ml of 50% hydrogen peroxide, 10 ml of 98% concentrated sulfuric acid, and 10 ml of purified water, and mix them in a 200 ml glass beaker to obtain a mixed aqueous solution with a total volume of 40 ml. Add 10 g of clean silicon wafer to this solution, and magnetically stir at 500 rpm for 2 hours at room temperature (25°C). After the reaction is complete, rinse the silicon wafer 5 times with deionized water, transfer it to a drying oven at 60°C, and dry it for 1 hour to obtain surface-hydroxylated silicon material.

[0065] (2) Hydrolysis polymerization: Measure 20 ml of 3-aminopropyltriethoxysilane and 10 ml of anhydrous ethanol and mix them. Immerse the surface-hydroxylated silicon material obtained in step (1) into the solution and stir slowly at 200 rpm for 2 hours at 25°C to carry out a mild solution polymerization reaction. After the reaction is completed, remove the silicon wafer and rinse the surface with anhydrous ethanol 3 times. Finally, let the silicon wafer dry in an 80°C oven for 40 minutes.

[0066] (3) Electrolyte immersion: The silicon wafer obtained in step (2) was immersed in 50 ml of lithium-ion battery electrolyte (the composition is the same as in Example 1) and left to stand for 5 hours. After immersion, the silicon wafer was removed to obtain an integrated silicon / solid electrolyte material structure.

[0067] The surface morphology of the integrated silicon / solid electrolyte material structure prepared in Example 5 was observed using a JSM6700 field emission scanning electron microscope manufactured by Japan Electronics Corporation. Figure 9 As shown.

[0068] Figure 9 A flexible solid electrolyte film can be observed on the silicon surface.

[0069] Example 6 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 10 ml of 30% hydrogen peroxide, 20 ml of 98% concentrated sulfuric acid, and 30 ml of purified water, and mix them to obtain a mixed aqueous solution with a total volume of 60 ml. Add 20 g of clean silicon wafer to this solution, and magnetically stir at 500 rpm for 5 hours at room temperature (25°C). After the reaction is complete, remove the silicon wafer, rinse it with deionized water, and dry it in a vacuum drying oven at 60°C for 2 hours to obtain surface-hydroxylated silicon material.

[0070] (2) Hydrolysis polymerization: Measure 20 ml of 3-mercaptopropyltrimethoxysilane and 1 ml of anhydrous ethanol, and stir to mix. Immerse the surface-hydroxylated silicon material obtained in step (1) into the solution for 5 seconds, then remove it and quickly fix it on a self-adsorption coating machine. Start the coating machine and coat at a speed of 7000 rpm for 2 minutes to obtain a flexible organic film on the silicon surface.

[0071] (3) Electrolyte wetting: Immerse the silicon wafer treated in step (2) in 30 ml of electrolyte (with the same composition as in Example 1) and let it stand for 1 hour. Remove the silicon wafer to obtain an integrated silicon / solid electrolyte material structure.

[0072] Example 7 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 1 ml of 30% hydrogen peroxide, 5 ml of 98% concentrated sulfuric acid, and 50 ml of purified water, mix them to obtain a mixed aqueous solution with a total volume of 56 ml. Add 4 g of clean silicon wafer to this solution, and magnetically stir at 500 rpm for 20 hours at room temperature (25°C). After the reaction is complete, remove the silicon wafer, wash it with deionized water, and dry it at room temperature for 12 hours to obtain surface-hydroxylated silicon material.

[0073] (2) Hydrolysis polymerization: Measure 10 ml of vinyltriethoxysilane and 1 ml of anhydrous ethanol, mix them, immerse the hydroxylated silicon wafer obtained in step (1) into the solution, ensure complete wetting, then use tweezers to remove it and quickly fix it on the sample stage of the coating machine. Set the coating machine to a constant speed of 1000 rpm for 5 minutes. After spin coating is completed, dry the sample.

[0074] (3) Electrolyte wetting: Immerse the silicon wafer treated in step (2) in 20 ml of electrolyte (the composition is the same as in Example 1) and let it stand for 1 hour. After wetting, remove the silicon wafer to obtain an integrated silicon / solid electrolyte material structure.

[0075] Example 8 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 10 ml of 40% hydrogen peroxide, 2 ml of 98% concentrated sulfuric acid, and 5 ml of purified water, and mix them to obtain a mixed aqueous solution with a total volume of 34 ml. Add 2 g of silicon powder to this solution and magnetically stir at 500 rpm for 2.5 hours at room temperature (25°C). After the reaction is complete, wash the silicon powder and dry it for 3 hours to obtain hydroxylated silicon powder.

[0076] (2) Hydrolysis polymerization: Measure 20 ml of tetraethoxysilane and 5 ml of anhydrous ethanol, add the hydroxylated silicon powder obtained in step (1), and stir continuously at 300 rpm for 20 hours.

[0077] (3) Electrolyte wetting: After the reaction was completed, the supernatant was discarded by centrifugation, and the material was transferred to 25 ml of electrolyte (with the same composition as in Example 1) and wetted for 2 hours. After wetting, the material was separated by centrifugation to obtain an integrated silicon / solid electrolyte material structure.

[0078] Example 9 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 20 ml of 40% hydrogen peroxide, 2 ml of 98% concentrated sulfuric acid, and 15 ml of purified water, and mix them to obtain a mixed aqueous solution with a total volume of 37 ml. Add 8 g of clean silicon wafer to this solution, and magnetically stir at 500 rpm for 0.5 hours at room temperature (25°C). After the reaction is complete, wash and dry the silicon wafer to obtain surface-hydroxylated silicon material.

[0079] (2) Hydrolysis polymerization: Measure 50 ml of dimethyldimethoxysilane and 5 ml of anhydrous ethanol and mix well. Add the surface-hydroxylated silicon material from step (1) and stir for 10 hours to obtain a flexible organic film on the silicon surface.

[0080] (3) Electrolyte wetting: Immerse the silicon material from step (2) in 10 ml of electrolyte (with the same composition as in Example 1) and let it stand for 2 hours. After wetting, remove the material to obtain an integrated silicon / solid electrolyte material structure.

[0081] Example 10 This embodiment provides a method for preparing an integrated silicon / solid electrolyte material structure, including the following steps: (1) Hydroxylation treatment: Measure 10 ml of 40% hydrogen peroxide, 20 ml of 98% concentrated sulfuric acid, and 50 ml of purified water, and mix them to obtain a mixed aqueous solution with a total volume of 80 ml. Add 20 g of silicon powder to this solution and magnetically stir at 500 rpm for 1.5 hours at room temperature (25°C). After the reaction is complete, centrifuge, wash, and dry the slurry to obtain surface-hydroxylated silicon material.

[0082] (2) Hydrolysis polymerization: Measure 30 ml of methyltriethoxysilane and 5 ml of anhydrous ethanol, mix them, add the surface hydroxylated silicon material obtained in step (1), and continuously stir mechanically at a speed of 300 rpm for 10 hours.

[0083] (3) Electrolyte wetting: The slurry obtained after the reaction was filtered, and the filter cake was added to 40 ml of electrolyte (with the same composition as in Example 1) for wetting for 2 hours. After wetting, it was removed to obtain an integrated silicon / solid electrolyte material structure.

[0084] Comparative Example 1 The difference between this comparative example and Example 8 is that in step (2), tetraethoxysilane and ethanol are not added. Instead, 20 mg of polyvinylidene fluoride (PVDF) is dissolved in 5 ml of N-methylpyrrolidone (NMP) to prepare a solution. The hydroxylated silicon powder obtained in step (1) is added to this PVDF solution and stirred at 25°C for 6 hours to allow the PVDF to be fully adsorbed. The mixture is then centrifuged, and the resulting solid is dried in a vacuum drying oven at 80°C for 12 hours to remove the solvent and allow the PVDF to coat the surface of the silicon powder, resulting in a physically coated silicon material. The remaining steps are the same as in Example 8.

[0085] Comparative Example 2 The difference between this comparative example and Example 8 is that in step (1), instead of using a hydrogen peroxide / concentrated sulfuric acid mixed solution, 2g of silicon powder was placed in an oxygen plasma cleaner and treated for 10 minutes at 100W power and 50Pa pressure to obtain surface-activated silicon powder. The subsequent steps are the same as in Example 8.

[0086] Comparative Example 3 The difference between this comparative example and Example 8 is that step (1) is omitted, and 2g of untreated raw silicon powder is directly taken for steps (2) and (3).

[0087] Performance testing The silicon / solid electrolyte composite materials obtained in Examples 1-10 and Comparative Examples 1-3 were used as active materials to prepare working electrodes and assembled into coin cells for electrochemical testing. In the examples, silicon wafers were used as the raw material (e.g., Examples 1, 3-7, 9) to prepare integrated silicon / solid electrolyte structures, which could be directly assembled into half-cells using lithium sheets as counter electrodes in an inert atmosphere glove box. Silicon powder was used as the raw material to prepare integrated silicon / solid electrolyte structures, which could be first pressed into sheets, then assembled into half-cells using lithium sheets as counter electrodes in an inert atmosphere glove box. The assembled half-cells were tested using a 2001A charge / discharge tester manufactured by Wuhan Landian Company (test conditions: room temperature, voltage range 0.01-1.5V vs. Li). + / Li) was used to evaluate its electrochemical performance. Specific test data are shown in Table 1: Table 1 Performance Test Data The test data above demonstrate that the preparation method provided by this invention can successfully construct a solid electrolyte membrane on the surface of silicon material, forming an integrated composite structure. This structure exhibits excellent electrochemical performance and good cycle stability. In particular, Example 8 achieved the best overall performance, with an initial discharge capacity as high as 3500 mAh / g, and a capacity retention rate of up to 95% after 100 cycles. This fully demonstrates that the integrated interface constructed by the method of this invention has extremely high stability and can effectively adapt to the volume changes of the silicon anode during cycling, thereby significantly improving the cycle life of the battery.

[0088] In Comparative Example 1, the physically coated PVDF layer lacked strong chemical bonding with the silicon substrate, resulting in weak interfacial adhesion. Under the stress of repeated expansion and contraction of silicon particles, the coating layer was prone to cracking and peeling, leading to continuous exposure of the silicon surface and side reactions with the electrolyte, while simultaneously disrupting ion transport channels. Consequently, cycle stability decreased sharply. In Comparative Example 2, although plasma treatment could activate the surface, the resulting surface functional groups (such as hydroxyl groups) might be uneven, unstable, or insufficient in concentration. This resulted in incomplete and uneven hydrolysis and polycondensation reactions of tetraethoxysilane, leading to poor density and adhesion of the formed organic film. In Comparative Example 3, the hydroxylation step was completely omitted, preventing the silane from effectively undergoing hydrolysis, polycondensation, and chemical bonding on the original silicon surface. The resulting "film" was actually loosely adsorbed or stacked silane oligomers, with extremely poor adhesion to the substrate and high porosity. This caused severe corrosion of the silicon surface by the electrolyte during the first wetting step, and the inability to restrain volume expansion during cycling, resulting in rapid capacity decay.

[0089] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a solid electrolyte film on a silicon material surface, comprising the following steps: (1) Hydroxylation treatment: The silicon material is mixed and stirred with a mixed aqueous solution of hydrogen peroxide and sulfuric acid to hydroxylate the surface of the silicon material; (2) Hydrolysis polymerization: The surface hydroxylated silicon material obtained in step (1) is brought into contact with a hydrolyzable silane compound, so that the silane compound undergoes a hydrolysis polymerization reaction on the surface of the silicon material to obtain a silicon material with an organic film on the surface. (3) Electrolyte wetting: The silicon material with an organic film on its surface is contacted and wetted with the lithium-ion battery electrolyte to form the solid electrolyte film on the surface of the silicon material.

2. The preparation method according to claim 1, characterized in that: In step (1), the silicon material is a silicon wafer or silicon powder, and the size of the silicon powder is nanometer, micrometer or millimeter.

3. The preparation method according to claim 1, characterized in that: In step (1), the mixed aqueous solution of hydrogen peroxide and sulfuric acid is obtained by mixing hydrogen peroxide, sulfuric acid and purified water; the volume ratio of purified water to hydrogen peroxide and sulfuric acid is 0.1:20~50:0.1, preferably 1:5~50:1; the concentration of hydrogen peroxide is 20%~70%, preferably 30-50%; the concentration of sulfuric acid is 50%~99.5%; and the volume ratio of hydrogen peroxide to sulfuric acid is 0.1:20~20:0.

1.

4. The preparation method according to claim 1, characterized in that: In step (2), the hydrolyzable silane compound is selected from alkoxysilanes or chlorosilanes; Preferably, the alkoxysilane is selected from one or a combination of several of monofunctional alkoxysilanes, difunctional alkoxysilanes, trifunctional alkoxysilanes, and tetrafunctional alkoxysilanes; the chlorosilane is an alkylchlorosilane; More preferably, the alkoxysilane is selected from one or a combination of several of alkyl alkoxysilanes, aryl alkoxysilanes, and alkoxysilanes containing functional groups; More preferably, the alkoxysilane is selected from one or a combination of several of methoxysilane, ethoxysilane, and propoxysilane.

5. The preparation method according to claim 1, characterized in that: In step (3), the lithium-ion battery electrolyte contains lithium salt and organic solvent; the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium tetrafluoroborate; the organic solvent is selected from one or more of carbonate solvents, ether solvents, and nitrile solvents.

6. The preparation method according to claim 1, characterized in that: The hydroxylation treatment in step (1) takes 0.05 hours to 20 hours; the hydrolysis polymerization reaction in step (2) takes 0.01 hours to 20 hours; and the electrolyte wetting time in step (3) takes 0.05 hours to 20 hours.

7. A solid electrolyte membrane on a silicon material surface, characterized in that, The electrolyte membrane is formed on the surface of the silicon material by the method described in any one of claims 1-6, and has a thickness of 1 nm to 500 μm.

8. A silicon / solid electrolyte composite material, characterized in that, The composite material includes a silicon material and a solid electrolyte membrane formed on the surface of the silicon material, and the composite material is prepared by the method according to any one of claims 1-6.

9. An electrode, characterized in that, The electrode comprises the silicon / solid electrolyte composite material of claim 8 as the active material.

10. A battery, characterized in that, The battery comprises the electrode as described in claim 9.

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