Silicon-based composite material containing organic flexible coating layer and preparation method therefor

Abstract

The present invention relates to a silicon-based composite material containing an organic flexible coating layer. The silicon-based composite material is of a three-layer core-shell structure and sequentially comprises a silicon-based material, an inorganic carbon coating layer and an organic flexible coating layer from inside to outside, wherein the organic flexible coating layer is a silicon-polyaniline layer formed by subjecting a silicon-based material containing an inorganic carbon coating layer to surface modification by adopting anilino silane to form a precursor, and then subjecting the precursor, aniline, an oxidizing agent and a cross-linking agent of octa-epoxy silsesquioxane to in-situ polymerization, wherein the mass ratio of the precursor, aniline, oxidizing agent and cross-linking agent of octa-epoxy silsesquioxane is 100 : (10-25) : (5-12) : (0.2-0.5); and the mass ratio of the silicon-based material containing the inorganic carbon coating layer to the anilino silane is 100 : (8-15). The organic flexible coating layer in the present invention can effectively alleviate the volume expansion and particle breakage of the silicon-based material during charging and discharging, and can play a role in the specific capacity and conductivity.

Description

Silicon-based composite material containing organic flexible coating layer and preparation method thereof TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium battery, and particularly relates to a silicon-based composite material containing an organic flexible coating layer and a preparation method thereof. BACKGROUND

[0002] Lithium ion batteries are one of the most attractive energy storage devices at present due to their high energy density, long service life and environmental friendliness. Traditional graphite negative electrodes have high stability but their capacity has reached the upper limit and cannot meet the market demand for high-energy batteries. Silicon-based negative electrode materials are attracting much attention due to their high specific capacity. However, in the actual lithium extraction / insertion process, silicon particles undergo large volume changes and even break and pulverize, the stability of the electrode structure is destroyed, and the capacity of the electrode material rapidly decays, resulting in a short cycle life. At the same time, silicon-based materials have poor electrical conductivity and poor reaction kinetics, which further affects their electrical performance. Carbon coating on the surface of silicon-based materials is a common solution to the above problems. For example, solid-phase carbon coating and chemical vapor deposition are used for carbon coating. The commonly used carbon coating layer in the prior art is an inorganic carbon layer. Since the inorganic carbon layer is rigid and brittle, it will crack to some extent during charging and discharging, and the pulverization of the electrode material is difficult to effectively alleviate, and the improvement effect on the long cycle performance of the material is not good.

[0003] Therefore, it is urgent to develop a silicon-based material with a flexible coating layer that can provide buffering for the expansion of the silicon-based material to effectively alleviate the influence of volume change of the electrode in the charging and discharging process. The applicant's previous patent CN113270586B discloses a preparation and application of a silicon-based negative electrode material modified by in-situ polymerization coating. The surface of the silicon-based material is coated with a composite coating layer of inorganic matter and polymer. The silicon-based negative electrode material is acted on by a deep eutectic solvent, so that the monomers of the polymer are in-situ polymerized on the surface of the silicon-based material to obtain a composite coating layer in which the inorganic matter is uniformly distributed in the polymer. The composite coating layer is constructed on the surface of the material by in-situ polymerization of polymer monomers doped with inorganic matter to form an organic-inorganic composite coating layer. The inorganic matter is a lithium salt, and the polymer is poly-1,3-dioxolane (PDOL), polyvinylidene carbonate (PVC), polyethylene carbonate (PEC), or polyacrylonitrile (PAN). Compared with the inorganic carbon coating layer, the negative electrode material containing the coating layer in-situ forms an organic-inorganic composite artificial solid electrolyte interface (SEI) during the initial lithiation / delithiation process, maintains the structural integrity during the lithium intercalation / deintercalation process, and the addition of lithium-rich inorganic matter reduces the irreversible consumption of lithium ions, thereby improving the initial coulombic efficiency and cycle stability of the negative electrode material. Although the inorganic lithium salt in the composite coating layer in the invention is beneficial to improving the cycle performance, a too high content of the inorganic lithium salt will affect the conductivity of the silicon-based negative electrode material; and a too high content of the organic polymer in the composite coating layer will also adversely affect the conductivity and specific capacity.

[0004] In summary, in the prior art, the inorganic carbon coating layer cannot completely and effectively alleviate the expansion problem of the silicon-based material, and the modified coating layer containing organic polymers has an adverse effect on the conductivity and specific capacity. SUMMARY

[0005] To solve the problems that the inorganic carbon coating layer in the prior art cannot completely and effectively alleviate the expansion of the silicon-based material, and the modified coating layer containing organic polymers has an adverse effect on the conductivity and specific capacity, the silicon-based composite material containing an organic flexible coating layer is formed by in-situ polymerization of the silicon-based material with an inorganic carbon coating layer after aniline-based silane surface modification. The flexible coating layer can effectively alleviate the volume expansion and particle rupture of the electrode material during the charging and discharging process, so that the silicon-based composite material has good cycle performance. At the same time, the organic polymer in the coating layer also contributes to the conductivity and specific capacity. That is, the silicon-based composite material has good comprehensive electrochemical performance when used in the negative electrode of a lithium battery.

[0006] To achieve the above-mentioned purpose, the present application adopts the following scheme:

[0007] The silicon-based composite material containing an organic flexible coating layer is a three-layer core-shell structure, from inside to outside, in turn, a silicon-based material, an inorganic carbon coating layer, and an organic flexible coating layer; the organic flexible coating layer is an organic silicon-polyaniline layer formed by in-situ polymerization of a precursor of the silicon-based material containing the inorganic carbon coating layer after surface modification by an aniline-based silane, aniline, an oxidizing agent, and a cross-linking agent octa-epoxy silsesquioxane; the mass ratio of the precursor, the aniline, the oxidizing agent, and the cross-linking agent octa-epoxy silsesquioxane is 100:(10-25):(5-12):(0.2-0.5); and the mass ratio of the silicon-based material containing the inorganic carbon coating layer and the aniline-based silane is 100:(8-15).

[0008] Further, the mass ratio of the precursor, the aniline, the oxidizing agent, and the cross-linking agent octa-epoxy silsesquioxane is 100:(15-20):(7-12):(0.2-0.5).

[0009] Further, the aniline-based silane is at least one of anilinemethyltrimethoxysilane, anilinemethyltriethoxysilane, 3-(phenylamino)propyltrimethoxysilane, and 3-(phenylamino)propyltriethoxysilane.

[0010] Further, the oxidizing agent is at least one of ammonium persulfate and benzoyl peroxide.

[0011] Further, the surface modification is achieved by hydrolysis of the aniline-based silane to generate a silicon hydroxyl group at one end of the molecular chain, and then condensation reaction with the hydroxyl group on the surface of the silicon-based material containing the inorganic carbon coating layer.

[0012] Further, the in-situ polymerization is achieved by chemical oxidation polymerization of the precursor and the aniline under the action of the oxidizing agent, and then cross-linking reaction with the cross-linking agent octa-epoxy silsesquioxane.

[0013] Further, the silicon-based material is at least one of silicon, silicon dioxide, modified silicon dioxide, silicon monoxide, silicon-carbon composite material, magnesium silicate, lithium silicate, sodium silicate, potassium silicate, and calcium silicate, and the particle size of the silicon-based material is 3-8 μm.

[0014] Further, the thickness of the inorganic carbon coating layer is 1-20 nm, preferably 5-15 nm.

[0015] In a second aspect, the application provides a preparation method of the above-mentioned silicon-based composite material containing an organic flexible coating layer, comprising the following preparation steps:

[0016] (S1) Inorganic carbon coating: coating the silicon-based material with inorganic carbon to obtain a silicon-based material containing an inorganic carbon coating layer;

[0017] (S2) surface modification: dispersing the silicon-based material with inorganic carbon coating layer in alcohol aqueous solution to obtain a dispersion liquid; dispersing aniline-based silane in water and performing hydrolysis reaction at room temperature to obtain a hydrolysis solution; adding the hydrolysis solution into the dispersion liquid and stirring and reacting at room temperature for 2-5 h to obtain a precursor;

[0018] (S3) in-situ polymerization: adding the precursor, aniline, and oxidant into an inorganic acid solution, stirring and reacting at 2-8℃ under inert atmosphere for 3-8 h; then adding crosslinking agent octa-epoxy silsesquioxane, and continuing to react at 60-80℃ for 2-5 h to obtain a silicon-based composite material coated with organosilicon-polyaniline, i.e. a silicon-based composite material with organic flexible coating layer.

[0019] In step (S1), the method for coating inorganic carbon is well known in the art, such as chemical vapor deposition or solid phase coating; preferably, chemical vapor deposition is adopted, i.e. using a gas phase carbon source to perform chemical vapor deposition on the surface of the silicon-based material to form a carbon coating layer, for example, the gas phase carbon source is selected from at least one of C1-4alkane (such as methane, ethane, propane), C2-4alkene (such as ethylene, propylene, 1-butene), C2-4alkyne (such as acetylene, propyne); the process conditions are: 800-1000℃ under inert atmosphere, and the reaction time is 2-5 h.

[0020] Further, in step (S2), the use amount ratio of the silicon-based material with inorganic carbon coating layer to alcohol aqueous solution is 100 g:(500-1000) mL, the alcohol content in the alcohol aqueous solution is 30-60 wt%, and the alcohol is selected from at least one of methanol and ethanol. The silicon-based material coated with inorganic carbon has hydrophobicity, so the dispersion effect is better when the silicon-based material with inorganic carbon coating layer is dispersed in alcohol aqueous solution in step (S2), which is more conducive to subsequent surface modification.

[0021] Further, in step (S2), the use amount ratio of aniline-based silane to water is (40-50) g:100 mL; and the hydrolysis reaction conditions are: stirring and reacting at room temperature for 15-30 min.

[0022] Further, in step (S3), the concentration of the inorganic acid solution is 0.5-1 mol / L, and the inorganic acid is at least one of hydrochloric acid, phosphoric acid, and perchloric acid; and the use amount ratio of aniline to the inorganic acid solution is 10 g:(300-500) mL.

[0023] Further, in step (S3), the inert atmosphere is at least one of nitrogen, argon, or helium.

[0024] In a third aspect, the application provides application of the above-mentioned silicon-based composite material with organic flexible coating layer in lithium ion batteries.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] (1) The present application uses aniline-based silane coupling agent to modify the surface of the silicon-based material with inorganic carbon-containing coating layer. After hydrolysis, the silicon hydroxyl group at one end of the aniline-based silane condenses with the hydroxyl group on the surface of the silicon-based material with inorganic carbon-containing coating layer, and the aniline-based silane is introduced to the surface of the silicon-based material with inorganic carbon-containing coating layer by chemical bond. The active aniline group at the other end of the aniline-based silane can be chemically oxidized and polymerized with aniline monomers under the action of an oxidizing agent, so that polyaniline is grafted in situ to the surface of the silicon-based material with inorganic carbon-containing coating layer, i.e., a uniform and stable organic silicon-polyaniline layer is formed on the surface of the silicon-based material. At the same time, the crosslinking agent octa-epoxy silsesquioxane can crosslink with the polyaniline in the organic silicon-polyaniline, thereby increasing the compactness of the organic flexible coating layer. Since the aniline-based silane and the crosslinking agent octa-epoxy silsesquioxane both contain organic silicon, a layer of organic silicon network film is formed in the structure, and the Si-O bond has high bond energy and good stability. Finally, a silicon-based composite material with a compact and stable organic flexible coating layer is obtained. The organic flexible coating layer can effectively alleviate the volume expansion and particle breakage of the electrode material during the charging and discharging process.

[0027] (2) The organic flexible coating layer of the present application contains an organic silicon group and a conductive polyaniline group, i.e., the organic flexible coating layer also plays a role in specific capacity and conductivity, so it can be used without high-temperature carbonization. Since high-temperature carbonization is not required, the size of the silicon grains can be controlled, and the silicon is in an amorphous state, avoiding the problem of silicon grain growth caused by high-temperature carbonization.

[0028] (3) When the silicon-based composite material with an organic flexible coating layer prepared by the present application is used as the negative electrode of a lithium battery, it exhibits good electrochemical performance, with a first reversible specific capacity of 1800 mAh / g, a first coulombic efficiency of more than 93%, and a cycle capacity retention rate of more than 93% after 100 cycles. In the process of preparing the negative electrode slurry, the slurry has a low gas production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a transmission electron microscope image of the silicon-based composite material with an organic flexible coating layer prepared in Example 1;

[0030] Figure 2 is the first cycle charge-discharge curve of the lithium battery assembled with the silicon-based composite material with an organic flexible coating layer prepared in Example 1 at a rate of 0.1C;

[0031] Figure 3 is a cycle number-coulombic efficiency graph of the lithium battery assembled with the silicon-based composite material with an organic flexible coating layer prepared in Example 1. DETAILED DESCRIPTION

[0032] In order to better explain the present application, the present application is described in detail with reference to the embodiments of the present application, and the main content of the present application is further illustrated by specific examples, but the content of the present application is not limited to the following examples.

[0033] Unless otherwise specified, the "parts" in the examples of the present application are all mass parts, and the reagents used are commercially available reagents in the art.

[0034] The particle size of the silicon-carbon composite material is 6.5 μm, which is a porous carbon particle of chemical vapor deposition silicon, and the silicon content is 49.7%, which is selected from Jiangxi Yijin New Energy Technology Co., Ltd.

[0035] Example 1

[0036] (S1) Inorganic carbon coating: the silicon-carbon composite material is put into a coating furnace, heated to 900℃ under a nitrogen atmosphere, and then acetylene gas is introduced at a flow rate of 3 L / min for carbon coating for 2.5 h to obtain a silicon-based material containing an inorganic carbon coating layer;

[0037] (S2) Surface modification: 200 g of the silicon-based material containing the inorganic carbon coating layer is dispersed in 1400 mL of an ethanol aqueous solution (ethanol content of 50 wt%) to obtain a dispersion liquid; 16 g of aniline silane is dispersed in 40 mL of water to obtain a hydrolysis solution by hydrolysis reaction at room temperature for 30 min; the hydrolysis solution is added to the dispersion liquid, and stirred at room temperature for 2 h; then, after suction filtration, washing with pure water, and drying in an oven at 60℃ for 12 h, a precursor is obtained;

[0038] (S3) In-situ polymerization: 100 g of the precursor, 10 g of aniline, and 5 g of the oxidant ammonium persulfate are added to 500 mL of a hydrochloric acid solution with a concentration of 0.5 mol / L, and stirred at 5±1℃ under a nitrogen atmosphere for 3 h; then, 0.2 g of the crosslinking agent octa-epoxy silsesquioxane is added, and the temperature is raised to 70℃ for further reaction for 3 h to obtain a mixed turbid liquid; then, the mixed turbid liquid is centrifuged, washed, and dried at 60℃ for 24 h to obtain a silicon-based composite material coated with organosilicon-polyaniline, i.e., a silicon-based composite material containing an organic flexible coating layer.

[0039] FIG. 1 is a transmission electron microscope image of the silicon-based composite material containing an organic flexible coating layer prepared in Example 1, and it can be seen from the figure that the silicon-based composite material containing an organic flexible coating layer prepared in Example 1 has a clear layered structure, and from the inside to the outside, it is a silicon-based material, an inorganic carbon coating layer, and an organic flexible coating layer.

[0040] Example 2

[0041] The rest is the same as Example 1, except that in step (S2), 3-(phenylamino)propyl trimethoxysilane is used instead of aniline methyl trimethoxysilane.

[0042] Example 3

[0043] The rest is the same as example 1, the difference is that in step (S2), the amount of material and reaction conditions are: 200 g of inorganic carbon coated silicon-based material is dispersed in 1400 mL of ethanol aqueous solution (ethanol content is 50 wt%) to obtain a dispersion; 30 g of aniline methyl trimethoxysilane is dispersed in 100 mL of water to carry out hydrolysis reaction at room temperature for 30 min to obtain a hydrolysis solution; the hydrolysis solution is added to the dispersion, and stirred at room temperature for 5 h; then, after suction filtration, pure water washing, and oven drying at 60℃ for 12 h, the precursor is obtained.

[0044] Example 4

[0045] The rest is the same as example 1, the difference is that in step (S3), the amount of material is: 100 g of precursor, 15 g of aniline, 7 g of oxidant ammonium persulfate, and 0.3 g of crosslinking agent octa-epoxy silsesquioxane.

[0046] Example 5

[0047] The rest is the same as example 1, the difference is that in step (S3), the amount of material is: 100 g of precursor, 20 g of aniline, 9 g of oxidant ammonium persulfate, and 0.4 g of crosslinking agent octa-epoxy silsesquioxane.

[0048] Example 6

[0049] The rest is the same as example 1, the difference is that in step (S3), the amount of material is: 100 g of precursor, 25 g of aniline, 12 g of oxidant ammonium persulfate, and 0.5 g of crosslinking agent octa-epoxy silsesquioxane.

[0050] Comparative example 1

[0051] The rest is the same as example 1, the difference is that step (S2) is omitted, that is, no aniline-based silane surface modification is carried out.

[0052] Comparative example 2

[0053] The rest is the same as example 1, the difference is that step (S3) is omitted, that is, no in-situ polymerization is carried out.

[0054] Comparative example 3

[0055] The rest is the same as example 1, the difference is that in step (S3), no crosslinking agent octa-epoxy silsesquioxane is used.

[0056] Test and analysis

[0057] The silicon-based composite material containing organic flexible coating layer prepared by the examples and comparative examples is subjected to the following electrochemical performance test:

[0058] Charge-discharge test: the prepared silicon-based composite material containing organic flexible coating layer, carbon black and polyacrylic acid (PAA) aqueous solution binder were mixed in a mass ratio of 80:10:10 to form a slurry (wherein the concentration of polyacrylic acid aqueous solution is 3.4wt%), the slurry was uniformly coated on the copper foil current collector with a certain thickness, and then the working electrode was prepared after vacuum drying for 12h; lithium sheet was used as the counter electrode, ceramic separator, and Shenzhen Xinzhoubon electrolyte, and a button cell was assembled in an argon atmosphere in a Miiller inert gas glove box. The above assembled battery was subjected to charge-discharge test on a LAND charge-discharge tester, and the test conditions were as follows: the charge-discharge interval was 0.005-1.5V, the three-stage discharge method was adopted, the discharge current density was 0.1C, 0.02C and 0.01C respectively, and the charging current density was 0.1C.

[0059] Figure 2 is the first cycle charge-discharge curve of the lithium battery assembled by the silicon-based composite material containing organic flexible coating layer prepared in Example 1 at a rate of 0.1C.

[0060] Figure 3 is a cycle number-coulombic efficiency graph of the lithium battery assembled by the silicon-based composite material containing organic flexible coating layer prepared in Example 1.

[0061] The high-temperature gas production test method is as follows: the prepared silicon-based composite material containing organic flexible coating layer, carbon black and sodium carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) composite binder are mixed in a mass ratio of 90:5:5 to form a slurry (wherein the mass ratio of CMC and SBR is 2:3), and then packaged in an aluminum plastic bag to exclude air. The initial slurry density value is tested by using a solid density meter, and then the density value is tested again after storing at 45℃ for 24h. The material gas production is calculated according to v=m / ρ, and the more the gas production value, the more serious the material damage and the worse the material stability.

[0062] The above test results are shown in Table 1.

[0063] Table 1 Performance test

[0064] As can be seen from the data in Table 1, when the silicon-based composite material containing organic flexible coating layer prepared in the embodiment of the present application is used as the negative electrode of the lithium battery, the first reversible specific capacity reaches 1800mAh / g, the first coulombic efficiency reaches more than 93%, and the cycle capacity retention rate reaches more than 93% after 100 cycles; and in the process of preparing the negative electrode slurry, the gas production of the slurry is low, which indicates that the organic flexible coating layer of the present application can effectively alleviate the volume expansion and particle crushing of the electrode material during the charge-discharge process.

[0065] In Comparative Example 1, the silicon-based material containing inorganic carbon coating layer is not subjected to surface modification by aniline-based silane, but only subjected to polymerization of aniline on its surface. The lithium battery prepared therefrom has a relatively high first coulombic efficiency, but has a low reversible specific capacity and poor cycle performance.

[0066] In Comparative Example 2, the silicon-based material containing the inorganic carbon coating layer is only surface-modified by aniline-based silane and is not subjected to in-situ polymerization. The lithium battery prepared therefrom has not only poor electrochemical performance, but also a large amount of gas generated in the slurry, indicating that an effective organic flexible coating layer is not formed.

[0067] In Comparative Example 3, the silicon-based material containing the inorganic carbon coating layer is surface-modified by aniline-based silane and is subjected to in-situ polymerization, but no crosslinking agent is added during the polymerization process. Although the first coulombic efficiency and reversible specific capacity of the lithium battery prepared therefrom are relatively high, the cycle performance is poor.

Claims

1. A silicon-based composite material containing an organic flexible coating layer, characterized in that, The three-layer core-shell structure is sequentially formed from inside to outside by a silicon-based material, an inorganic carbon coating layer, and an organic flexible coating layer; the organic flexible coating layer is formed by in-situ polymerization of a precursor, aniline, an oxidant, and a cross-linking agent octa-epoxy silsesquioxane, wherein the precursor is formed by surface modification of the silicon-based material with an aniline-based silane; a mass ratio of the precursor, the aniline, the oxidant, and the cross-linking agent octa-epoxy silsesquioxane is 100:(10-25):(5-12):(0.2-0.5); and a mass ratio of the silicon-based material with the inorganic carbon coating layer and the aniline-based silane is 100:(8-15).

2. The silicon-based composite material containing an organic flexible coating layer according to claim 1, characterized in that, The mass ratio of the precursor, the aniline, the oxidant, and the cross-linking agent octa-epoxy silsesquioxane is 100:(15-20):(7-12):(0.2-0.5).

3. The silicon-based composite material containing an organic flexible coating layer according to claim 1, characterized in that, The aniline-based silane is at least one of anilinemethyltrimethoxysilane, anilinemethyltriethoxysilane, 3-(phenylamino)propyltrimethoxysilane, and 3-(phenylamino)propyltriethoxysilane.

4. The silicon-based composite containing an organic flexible cap layer of claim 1, wherein, The oxidant is at least one of ammonium persulfate and benzoyl peroxide.

5. The silicon-based composite containing an organic flexible cap layer of claim 1, wherein, The surface modification is achieved by condensation reaction of silicon hydroxyl groups generated at one end of the molecular chain of the aniline-based silane after hydrolysis and hydroxyl groups on the surface of the silicon-based material with the inorganic carbon coating layer; and / or The in-situ polymerization is achieved by chemical oxidation polymerization of the precursor and the aniline under the action of the oxidant, and then cross-linking reaction with the cross-linking agent octa-epoxy silsesquioxane.

6. The silicon-based composite containing an organic flexible cap layer of claim 1, wherein, The silicon-based material is at least one of silicon element, silicon dioxide, modified silicon dioxide, silicon monoxide, silicon-carbon composite material, magnesium silicate, lithium silicate, sodium silicate, potassium silicate, and calcium silicate, and the particle size of the silicon-based material is 3-8 μm; and the thickness of the inorganic carbon coating layer is 1-20 nm.

7. Process for the production of a silicon-based composite material containing an organic flexible coating layer according to any one of claims 1 to 6, characterized in that, The preparation steps include: (S1) inorganic carbon coating: inorganic carbon coating is performed on the silicon-based material to obtain the silicon-based material with the inorganic carbon coating layer; (S2) surface modification: the silicon-based material with the inorganic carbon coating layer is dispersed in an alcohol aqueous solution to obtain a dispersion liquid; the aniline-based silane is dispersed in water and hydrolyzed at room temperature to obtain a hydrolysis solution; The hydrolysis solution is added to the dispersion liquid, and stirring reaction is performed at room temperature for 2-5 h to obtain the precursor; (S3) in-situ polymerization: the precursor, the aniline, and the oxidant are added to an inorganic acid solution, and stirring reaction is performed at 2-8 ℃ under an inert atmosphere for 3-8 h; then the cross-linking agent octa-epoxy silsesquioxane is added, and the temperature is increased to 60-80 ℃ for continuous reaction for 2-5 h to obtain the silicon-based composite material coated with the organic silicon-polyaniline, i.e., the silicon-based composite material with the organic flexible coating layer.

8. The preparation method according to claim 7, characterized in that, In step (S2), a use amount ratio of the silicon-based material with the inorganic carbon coating layer and the alcohol aqueous solution is 100 g:(500-1000) mL, an alcohol content in the alcohol aqueous solution is 30-60 wt%, and the alcohol is at least one selected from methanol and ethanol; and / or A use amount ratio of the aniline-based silane and water is (40-50) g:100 mL; and a hydrolysis reaction condition is stirring reaction at room temperature for 15-30 min.

9. The preparation method according to claim 7, characterized in that, In step (S3), the concentration of the inorganic acid solution is 0.5-1 mol / L, the inorganic acid is at least one of hydrochloric acid, phosphoric acid and perchloric acid; the ratio of the amount of the aniline to the inorganic acid solution is 10 g:(300-500) mL; and the inert atmosphere is at least one of nitrogen, argon and helium.

10. Use of a silicon-based composite material comprising an organic flexible coating layer according to any one of claims 1 to 6 in a lithium-ion battery.

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