A composite negative electrode material and its preparation method and application

Abstract

This application belongs to the field of lithium-ion battery technology, specifically relating to a composite anode material, its preparation method, and its application. The composite anode material comprises the following raw materials in parts by weight: 3-8 parts porous nano-silicon, 25-50 parts carbon-containing resin, 0.8-1.4 parts dopamine hydrochloride, and 5-15 parts graphite. The beneficial effects of this application include: conductive carbon is uniformly dispersed in the pores of the porous nano-silicon, and a nitrogen-doped carbon layer is present on the surfaces of the porous nano-silicon and graphite, giving the composite anode material stronger conductivity and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a composite anode material, its preparation method, and its application. Background Technology

[0002] Silicon-carbon composite materials, as an emerging anode material, have attracted widespread attention in the field of lithium-ion batteries. Compared with traditional graphite anode materials, silicon-carbon composite materials have a higher theoretical capacity (up to 4200 mAh / g), making them an ideal choice for next-generation high-energy-density lithium-ion batteries. However, despite the many advantages of silicon-carbon composite anodes, their industrial application still faces some challenges. The preparation cost of silicon-carbon composite materials is relatively high, and their cycle performance needs further improvement, especially under high-rate charge-discharge conditions. Furthermore, silicon-carbon composite materials exhibit significant volume changes (up to 300%), which can lead to structural cracking and decreased cycle performance. Moreover, although carbon materials have good conductivity, the interfacial bonding between silicon and carbon is relatively weak, easily forming a poorly conductive interfacial layer, increasing the battery's internal resistance and affecting its charge-discharge performance. The preparation of silicon-carbon composite materials typically requires complex processes such as high-temperature sintering, mechanical ball milling, and chemical vapor deposition, which are not only energy-intensive and have high equipment costs, but also difficult to mass-produce. Silicon-carbon composite materials, as an emerging anode material for lithium-ion batteries, have certain advantages in terms of specific capacity and cycle stability, but they still have problems such as poor conductivity, low actual specific capacity, need to improve cycle stability, and complex preparation process. Summary of the Invention

[0003] This application provides a composite anode material, its preparation method, and its application, aiming to solve the problems of poor conductivity, low actual specific capacity, low cycle stability, and complex preparation process of existing carbon-silicon composite materials.

[0004] The first aspect of this application provides a composite negative electrode material comprising the following raw materials in parts by weight: 3-8 parts porous nano-silicon, 25-50 parts carbon-containing resin, 0.8-1.4 parts dopamine hydrochloride, and 5-15 parts graphite.

[0005] According to some embodiments of the composite negative electrode material described in this application, the carbon-containing resin includes one or more of waterborne polyurethane resin, phenolic resin, epoxy resin, and polyacrylonitrile.

[0006] A second aspect of this application provides a method for preparing the composite negative electrode material described in the first aspect of this application, comprising the following steps:

[0007] (1) Mix and heat porous nano-silicon, carbon-containing resin and first solvent to obtain porous nano-silicon doped with conductive carbon.

[0008] (2) The porous nano-silicon, graphite, dopamine hydrochloride and the second solvent obtained in step (1) are mixed and heated to obtain the composite negative electrode material.

[0009] In the preparation method described in this application, dopamine hydrochloride polymerizes on the surface of porous nano-silicon and graphite to form a polydopamine coating. This coating carbonizes at high temperatures, forming a highly conductive carbon layer. Simultaneously, nitrogen doping further enhances the conductivity and electrochemical performance of the material. Furthermore, the introduction of polydopamine strengthens the bonding between materials, improving their structural stability.

[0010] During the high-temperature carbonization process, the pores of porous nano-silicon may be adjusted due to the formation of carbon layers, resulting in a more reasonable pore distribution, which is conducive to electrolyte penetration and ion transport, thereby improving the electrochemical performance of the material.

[0011] According to some embodiments of the composite anode material preparation method described in this application, the first solvent includes ethanol and / or methanol.

[0012] According to some embodiments of the composite negative electrode material preparation method described in this application, in step (1), the temperature of the mixing and heating is 700-900℃, and the time of the mixing and heating is 3-5h.

[0013] According to some embodiments of the composite negative electrode material preparation method described in this application, in step (1), the heating rate of the mixing heating is 4-6℃ / min.

[0014] According to some embodiments of the composite anode material preparation method described in this application, the second solvent includes methanol and / or ethanol.

[0015] According to some embodiments of the composite negative electrode material preparation method described in this application, in step (2), the temperature of the mixing and heating is 700-900℃, and the time of the mixing and heating is 2-4h.

[0016] According to some embodiments of the composite negative electrode material preparation method described in this application, in step (2), the heating rate of the mixing heating is 4-6℃ / min.

[0017] According to some embodiments of the composite negative electrode material preparation method described in this application, the mixing and heating in steps (1) and (2) are carried out under an inert atmosphere; preferably, the inert atmosphere includes an argon atmosphere and / or a nitrogen atmosphere.

[0018] According to some embodiments of the composite anode material preparation method described in this application, the preparation of the porous nano-silicon includes the following steps:

[0019] a. Triethylamine, hexadecyltrimethylammonium bromide, sodium salicylate, tetraethyl orthosilicate, 1,2-bis(triethoxysilyl)ethane and a third solvent are mixed and heated. The mixed heating product is subjected to template removal treatment to obtain a porous nano-silicon material precursor.

[0020] b. Mix hexadecyltrimethylammonium bromide, porous nano-silicon precursor and fourth solvent to obtain porous nano-silicon.

[0021] According to some embodiments of the composite negative electrode material preparation method described in this application, the mass ratio of the triethylamine, the hexadecyltrimethylammonium bromide, the sodium salicylate, the tetraethyl orthosilicate, and the 1,2-bis(triethoxysilyl)ethane is (1-3):(4-9):1:(2-6):(2-6).

[0022] According to some embodiments of the composite anode material preparation method described in this application, in step a, the mixing and heating temperature is 70-90℃, and the mixing and heating time is 12-16h.

[0023] According to some embodiments of the composite anode material preparation method described in this application, in step a, the template removal process includes mixing the mixed heating product with hydrochloric acid and methanol, refluxing and stirring for 20-26 hours to remove the template.

[0024] According to some embodiments of the composite anode material preparation method described in this application, the third solvent includes methanol and hydrochloric acid.

[0025] According to some embodiments of the composite anode material preparation method described in this application, the mass ratio of the hexadecyltrimethylammonium bromide to the porous nano-silicon precursor is (3-8):3.

[0026] According to some embodiments of the composite anode material preparation method described in this application, in step b, the mixing temperature is 50-60℃ and the mixing time is 20-30h.

[0027] According to some embodiments of the composite anode material preparation method described in this application, the fourth solvent includes methanol and an aqueous solution of sodium hydroxide.

[0028] According to some embodiments of the composite anode material preparation method described in this application, the preparation of porous nano-silicon further includes precipitating a product of a mixture of hexadecyltrimethylammonium bromide, porous nano-silicon material precursor, and a fourth solvent using ammonium nitrate, followed by centrifugation to obtain the porous nano-silicon.

[0029] A third aspect of this application provides a lithium-ion battery, comprising the composite anode material described in the first aspect of this application or the composite anode material obtained by the preparation method described in the second aspect of this application. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below, and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0031] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0032] This application provides a composite negative electrode material comprising the following raw materials in parts by weight: 3-8 parts porous nano-silicon, 25-50 parts carbon-containing resin, 0.8-1.4 parts dopamine hydrochloride, and 5-15 parts graphite.

[0033] The composite anode material described in this application has a stable structure and superior electrochemical performance.

[0034] In some embodiments of this application, the carbon-containing resin includes one or more of waterborne polyurethane resin, phenolic resin, epoxy resin and polyacrylonitrile; the carbon source will carbonize at high temperature to form carbon materials with good conductivity, and these carbon materials will be uniformly dispersed in the channels of porous nano-silicon, thereby endowing porous nano-silicon with conductive properties.

[0035] The addition of dopamine hydrochloride can form a polydopamine coating on the surface of porous nano-silicon and graphite through polymerization, which can then be carbonized at high temperature to form a nitrogen-doped carbon layer, thereby enhancing the conductivity and structural stability of the material.

[0036] This application also provides a method for preparing the composite negative electrode material described in the first aspect of this application, including the following steps:

[0037] (1) Mix and heat porous nano-silicon, carbon-containing resin and first solvent to obtain porous nano-silicon doped with conductive carbon.

[0038] (2) The porous nano-silicon, graphite, dopamine hydrochloride and the second solvent obtained in step (1) are mixed and heated to obtain the composite negative electrode material.

[0039] In the preparation method described in this application, dopamine hydrochloride polymerizes on the surface of porous nano-silicon and graphite to form a polydopamine coating. This coating carbonizes at high temperatures, forming a highly conductive carbon layer. Simultaneously, nitrogen doping further enhances the conductivity and electrochemical performance of the material. Furthermore, the introduction of polydopamine strengthens the bonding between materials, improving their structural stability.

[0040] During the high-temperature carbonization process, the pores of porous nano-silicon may be adjusted due to the formation of carbon layers, resulting in a more reasonable pore distribution, which is conducive to electrolyte penetration and ion transport, thereby improving the electrochemical performance of the material.

[0041] In some embodiments of this application, the first solvent includes ethanol and / or methanol.

[0042] In some embodiments of this application, in step (1), the temperature of the mixing and heating is 700-900℃, such as 700℃, 750℃, 800℃, 860℃, 900℃, etc., and the heating time is 3-5h, such as 3h, 4h, 5h, etc. This heating temperature range can promote the uniform dispersion and effective doping of conductive carbon in porous nano-silicon, and avoid high temperature damage to the material structure.

[0043] A heating temperature of 700-900℃ ensures the decomposition and carbonization of the carbon source, forming conductive carbon. During this process, the carbon source undergoes pyrolysis and carbonization reactions at high temperatures, generating carbon materials with conductive properties. This temperature range ensures carbonization without causing excessive graphitization or burn-off of the carbon material due to excessive heat. At this temperature, conductive carbon can be uniformly dispersed within the pores of porous nano-silicon, forming a porous nano-silicon composite material doped with conductive carbon. This composite material not only retains the original properties of porous nano-silicon, such as high specific surface area, porosity, and good adsorption performance, but also endows the material with new conductive properties.

[0044] Excessive heating temperature may damage the structure of porous silicon nanoparticles, such as causing pore collapse and a reduction in specific surface area, thereby affecting the material's performance and application. Therefore, selecting a moderate heating temperature range of 700-900℃ allows for effective doping of conductive carbon while maintaining the good structure of the porous silicon nanoparticles.

[0045] In some embodiments of this application, the heating rate of the mixed heating is 4-6℃ / min, such as 4℃ / min, 5℃ / min, 6℃ / min, etc.

[0046] In some embodiments of this application, the second solvent includes methanol and / or ethanol.

[0047] In some embodiments of this application, in step (2), the temperature of the mixed heating is 700-900℃, such as 700℃, 750℃, 800℃, 860℃, 900℃, etc., and the time of the mixed heating is 2-4h; such as 2h, 3h, 4h, etc.

[0048] In some embodiments of this application, in step (2), the heating rate of the mixed heating is 4-6℃ / min; for example, 4℃ / min, 5℃ / min, 6℃ / min, etc.

[0049] In some embodiments of this application, the mixing and heating in steps (1) and (2) are carried out under an inert atmosphere; preferably, the inert atmosphere includes an argon atmosphere and / or a nitrogen atmosphere.

[0050] In some embodiments of this application, the preparation of the porous nano-silicon includes the following steps:

[0051] a. Triethylamine, hexadecyltrimethylammonium bromide, sodium salicylate, tetraethyl orthosilicate, 1,2-bis(triethoxysilyl)ethane and a third solvent are mixed and heated. The mixed heating product is subjected to template removal treatment to obtain a porous nano-silicon material precursor.

[0052] b. Mix hexadecyltrimethylammonium bromide, porous nano-silicon precursor and fourth solvent to obtain porous nano-silicon.

[0053] The method for preparing porous nano-silicon described in this application can precisely control the pore size, shape, and distribution of porous materials, so that the obtained porous nano-silicon materials have high orderliness and uniformity.

[0054] In some embodiments of this application, the mass ratio of the triethylamine, the hexadecyltrimethylammonium bromide, the sodium salicylate, the tetraethyl orthosilicate, and the 1,2-bis(triethoxysilyl)ethane is (1-3):(4-9):1:(2-6):(2-6).

[0055] In some embodiments of this application, in step a, the temperature of the mixed heating is 70-90°C, such as 70°C, 75°C, 80°C, 85°C, 90°C, etc., and the time of the mixed heating is 12-16h, such as 12h, 14h, 15h, 16h, etc.

[0056] In some embodiments of this application, in step a, the template removal process includes mixing the mixed heating product with hydrochloric acid and methanol, refluxing and stirring for 20-26 hours to remove the template;

[0057] In some embodiments of this application, the third solvent includes methanol and hydrochloric acid.

[0058] In some embodiments of this application, the mass ratio of the hexadecyltrimethylammonium bromide to the porous nano-silicon precursor is (3-8):3, for example 3:3, 4:3, 5:3, 6:3, 8:3, etc.

[0059] In some embodiments of this application, in step b, the mixing temperature is 50-60°C and the mixing time is 20-30 hours;

[0060] In some embodiments of this application, the fourth solvent includes methanol and an aqueous solution of sodium hydroxide.

[0061] In some embodiments of this application, the preparation of the porous nano-silicon further includes precipitating a product of a mixture of hexadecyltrimethylammonium bromide, a porous nano-silicon precursor, and a fourth solvent using ammonium nitrate, followed by centrifugation to obtain the porous nano-silicon.

[0062] This application also provides a lithium-ion battery, including the composite anode material described in the first aspect of this application or the composite anode material obtained by the preparation method described in the second aspect of this application.

[0063] The technical solution of this application will be further described below with reference to specific embodiments.

[0064] Example 1

[0065] A method for preparing a composite anode material includes the following steps:

[0066] (1) Preparation of porous nano-silicon: 10 g of triethylamine, 35 mL of hexadecyltrimethylammonium bromide (CTAB), and 5 mL of sodium salicylate (NaSal) were added to water and stirred at 80 °C for 2 h. Then, 20 mL of tetraethyl orthosilicate (TEOS) and 20 mL of 1,2-bis(triethoxysilyl)ethane (BTES) were mixed in a 5:5 ratio and added dropwise to the above solution, and stirred continuously at 80 °C for 12 h. The product was collected by centrifugation and washed with ethanol. The product was then dispersed in a 2 M HCl and methanol solution (hydrochloric acid and methanol volume ratio of 1:1), refluxed and stirred for 24 h to remove the template, and finally the particles were dried at 55 °C to obtain the precursor of porous nano-silicon material.

[0067] 7.5 g of hexadecyltrimethylammonium bromide was mixed with methanol, water, and sodium hydroxide solution. 7.5 g of porous nano-silicon precursor was added to the mixture, and the mixture was stirred at 60 °C for 20 h. 50 g of ammonium nitrate was added to the reaction solution to precipitate the material. The mixture was centrifuged, washed once with water, twice with ethanol, and ultrasonically dispersed for 1 h. Finally, the particles were dried at 55 °C to obtain porous nano-silicon.

[0068] (2) Mix 3g of porous nano-silicon obtained in step (1), 40g of waterborne polyurethane resin and 45ml of anhydrous ethanol. Under an argon atmosphere, heat the mixture to 800℃ at a heating rate of 5℃ / min and keep it heated for 4h. After heating is completed, cool it naturally to room temperature to obtain porous nano-silicon doped with conductive carbon.

[0069] (3) Add the porous nano-silicon doped with conductive carbon obtained in step (2) and 5g of graphite to 50ml of methanol, and ultrasonically disperse for 2h. Then add 1.4g of dopamine hydrochloride to the mixture, and heat the dried product to 800℃ at a heating rate of 5℃ / min under argon atmosphere, and keep it heated for 3h to obtain the composite negative electrode material.

[0070] Example 2

[0071] The only difference between the composite negative electrode material described in Example 2 and that in Example 1 is that the amount of waterborne polyurethane resin and graphite added in the composite negative electrode material described in Example 2 is different from that in Example 1.

[0072] The specific operating steps include:

[0073] (1) Preparation of porous nano-silicon: Refer to the preparation method of porous nano-silicon in Example 1;

[0074] (2) Mix 3g of porous nano-silicon obtained in step (1), 25g of waterborne polyurethane resin and 45ml of anhydrous ethanol. Under an argon atmosphere, heat the mixture to 800℃ at a heating rate of 5℃ / min and keep it heated for 4h. After heating is completed, cool it naturally to room temperature to obtain porous nano-silicon doped with conductive carbon.

[0075] (3) Add the porous nano-silicon doped with conductive carbon obtained in step (2) and 15g of graphite to 50ml of methanol, and ultrasonically disperse for 2h. Then add 1.4g of dopamine hydrochloride to the mixture, and heat the dried product to 800℃ at a heating rate of 5℃ / min under argon atmosphere, and keep it heated for 3h to obtain the composite negative electrode material.

[0076] Example 3

[0077] The only difference between the composite negative electrode material described in Example 3 and that in Example 1 is that the amount of waterborne polyurethane resin and graphite added in the composite negative electrode material described in Example 3 is different from that in Example 1.

[0078] The specific operating steps include:

[0079] (1) Preparation of porous nano-silicon: Refer to the preparation method of porous nano-silicon in Example 1;

[0080] (2) Mix 3g of porous nano-silicon obtained in step (1), 50g of waterborne polyurethane resin and 45ml of anhydrous ethanol. Under an argon atmosphere, heat the mixture to 800℃ at a heating rate of 5℃ / min and keep it heated for 4h. After heating is completed, cool it naturally to room temperature to obtain porous nano-silicon doped with conductive carbon.

[0081] (3) Add the porous nano-silicon doped with conductive carbon obtained in step (2) and 5g of graphite to 50ml of methanol, and ultrasonically disperse for 2h. Then add 1.4g of dopamine hydrochloride to the mixture, and heat the dried product to 800℃ at a heating rate of 5℃ / min under argon atmosphere, and keep it heated for 3h to obtain the composite negative electrode material.

[0082] Example 4

[0083] The only difference between the composite negative electrode material described in Example 4 and that in Example 1 is that the amount of waterborne polyurethane resin and graphite added in the composite negative electrode material described in Example 4 is different from that in Example 1.

[0084] The specific operating steps include:

[0085] (1) Preparation of porous nano-silicon: Refer to the preparation method of porous nano-silicon in Example 1;

[0086] (2) Mix 3g of porous nano-silicon obtained in step (1), 25g of waterborne polyurethane resin and 45ml of anhydrous ethanol. Under an argon atmosphere, heat the mixture to 800℃ at a heating rate of 5℃ / min and keep it heated for 4h. After heating is completed, cool it naturally to room temperature to obtain porous nano-silicon doped with conductive carbon.

[0087] (3) Add the porous nano-silicon doped with conductive carbon obtained in step (2) and 10g of graphite to 50ml of methanol, disperse ultrasonically for 2h, then add 1.4g of dopamine hydrochloride to the mixture, heat the dried product to 800℃ at a heating rate of 5℃ / min under argon atmosphere, and keep it heated for 3h to obtain the composite negative electrode material.

[0088] Comparative Example 1

[0089] The only difference between the composite anode material described in Comparative Example 1 and that in Example 1 is that graphite was not used for coating during the preparation of the composite anode material described in Comparative Example 1.

[0090] The specific operating steps include:

[0091] (1) Preparation of porous nano-silicon: Refer to the preparation method of porous nano-silicon in Example 1;

[0092] (2) Mix 3g of porous nano-silicon obtained in step (1), 40g of waterborne polyurethane resin and 45ml of anhydrous ethanol. Under an argon atmosphere, heat the mixture to 800°C at a heating rate of 5°C / min and keep it at that temperature for 4 hours. After heating is complete, let it cool naturally to room temperature to obtain porous nano-silicon doped with conductive carbon, which is the composite negative electrode material described in Comparative Example 1.

[0093] Comparative Example 2

[0094] The only difference between the composite anode material described in Comparative Example 2 and that in Example 1 is that the composite anode material described in Comparative Example 2 was not doped with conductive carbon during its preparation.

[0095] The specific steps include:

[0096] (1) Preparation of porous nano-silicon: Refer to the preparation method of porous nano-silicon in Example 1;

[0097] (2) Add 5g of porous nano-silicon and 5g of graphite obtained in step (1) to 50ml of methanol, disperse by ultrasonication for 2h, then add 1.4g of dopamine hydrochloride to the mixture, and heat the dried product to 800℃ at a heating rate of 5℃ / min under argon atmosphere, and keep it heated for 3h to obtain the composite negative electrode material.

[0098] Electrical performance study of the composite anode materials described in Examples 1-4 and Comparative Examples 1-2 of this application.

[0099] The composite negative electrode materials described in Examples 1-4 and Comparative Examples 1-2 were assembled with positive electrode materials, electrolytes, and separators to form lithium-ion batteries.

[0100] The test results are shown in Table 1:

[0101] Table 1

[0102] First charge / discharge efficiency (%) Capacity retention rate after 500 laps (%) 6C rate performance Example 1 88.7％ 96.77％ 99.18％ Example 2 88.5％ 95.09％ 99.04％ Example 3 87.6％ 94.89％ 98.88％ Example 4 88.1％ 96.25％ 99.15％ Comparative Example 1 86.5％ 92.89％ 94.24％ Comparative Example 2 86.2％ 92.21％ 93.75％

[0103] As can be seen from Table 1, the electrochemical performance of the composite anode materials obtained in Examples 1-4 of this application is better than that of the anode materials obtained without graphite coating or conductive carbon doping.

[0104] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A composite negative electrode material, characterized in that, The raw materials include the following parts by weight: 3-8 parts porous nano-silicon, 25-50 parts carbon-containing resin, 0.8-1.4 parts dopamine hydrochloride, and 5-15 parts graphite; The preparation method of the composite anode material includes the following steps: (1) Porous nano-silicon, carbon-containing resin and first solvent are mixed and heated at a temperature of 700-900℃ to obtain porous nano-silicon doped with conductive carbon. (2) The porous nano-silicon, graphite, dopamine hydrochloride and the second solvent obtained in step (1) are mixed and heated at a temperature of 700-900℃ to obtain the composite negative electrode material; The preparation of the porous nano-silicon includes the following steps: a. Triethylamine, hexadecyltrimethylammonium bromide, sodium salicylate, tetraethyl orthosilicate, 1,2-bis(triethoxysilyl)ethane and a third solvent are mixed and heated. The mixed heating product is subjected to template removal treatment to obtain a porous nano-silicon material precursor. b. Mix hexadecyltrimethylammonium bromide, porous nano-silicon precursor and fourth solvent to obtain porous nano-silicon.

2. The composite negative electrode material according to claim 1, characterized in that, The carbon-containing resin includes one or more of waterborne polyurethane resin, phenolic resin, epoxy resin, and polyacrylonitrile.

3. The composite negative electrode material according to claim 1, characterized in that, The first solvent includes ethanol and / or methanol; And / or, in step (1), the mixing and heating time is 3-5 hours; And / or, in step (1), the heating rate of the mixed heating is 4-6℃ / min.

4. The composite negative electrode material according to claim 1, characterized in that, The second solvent includes methanol and / or ethanol; And / or, in step (2), the mixing and heating time is 2-4 hours; And / or, in step (2), the heating rate of the mixed heating is 4-6℃ / min; And / or, the mixing heating in steps (1) and (2) is carried out under an inert atmosphere.

5. The composite negative electrode material according to claim 4, characterized in that, The inert atmosphere includes an argon atmosphere and / or a nitrogen atmosphere.

6. The composite negative electrode material according to claim 1, characterized in that, The mass ratio of the triethylamine, the hexadecyltrimethylammonium bromide, the sodium salicylate, the tetraethyl orthosilicate, and the 1,2-bis(triethoxysilyl)ethane is (1-3):(4-9):1:(2-6):(2-6). And / or, in step a, the temperature of the mixed heating is 70-90℃, and the time of the mixed heating is 12-16h; And / or, in step a, the template removal process includes mixing the mixed heating product with hydrochloric acid and methanol, refluxing and stirring for 20-26 hours to remove the template; And / or, the third solvent includes methanol and hydrochloric acid.

7. The composite negative electrode material according to claim 1, characterized in that, The mass ratio of the hexadecyltrimethylammonium bromide to the porous nano-silicon precursor is (3-8):3; And / or, in step b, the mixing temperature is 50-60°C, and the mixing time is 20-30 hours; And / or, the fourth solvent includes methanol and an aqueous solution of sodium hydroxide.

8. The composite negative electrode material according to claim 1, characterized in that, The preparation of the porous nano-silicon also includes precipitating a product of a mixture of hexadecyltrimethylammonium bromide, a porous nano-silicon precursor, and a fourth solvent using ammonium nitrate, followed by centrifugation to obtain the porous nano-silicon.

9. A lithium-ion battery, characterized in that, Includes the composite anode material as described in any one of claims 1-8.