Three-dimensional mesoporous carbon composite silicon-carbon negative electrode material and preparation method and application thereof

Abstract

The application discloses a kind of three-dimensional mesoporous carbon composite silicon-carbon negative electrode materials and preparation method and application thereof, and relates to the technical field of battery.A kind of preparation method of three-dimensional mesoporous carbon composite silicon-carbon negative electrode material, comprising the following steps: additive 1 and additive 2 are dissolved in deionized water respectively, obtain solution A and solution B, in solution A is added to solution B, obtain solution C;Additive 3 is dissolved in deionized water, obtain solution D, solution C is added to solution D, obtain solution E;High-temperature calcination obtains template A;After reaction, solution G is obtained;Template B is obtained;Sample is obtained;Carbonized sample is obtained, after drying, dry sample is obtained;Dry sample is activated at high temperature in carbon dioxide gas environment, obtain three-dimensional mesoporous carbon material, then carry out chemical vapor deposition, obtain three-dimensional mesoporous carbon composite silicon-carbon negative electrode material.The application solves the problem that significant volume expansion occurs in the charge and discharge process of silicon-based negative electrode material.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a three-dimensional mesoporous carbon composite silicon-carbon anode material, its preparation method, and its application. Background Technology

[0002] In recent years, with the increasing global awareness of environmental protection and the transformation of the energy structure, the electric vehicle industry has ushered in an unprecedented period of rapid development. This trend has placed more stringent demands on the performance of lithium-ion batteries, especially in terms of energy density, cycle stability, and safety. As a core component of lithium-ion batteries, the anode material plays a decisive role in the overall performance of the battery.

[0003] Traditionally, graphite has been widely used as the anode material in commercial lithium-ion batteries due to its stable chemical properties, good conductivity, and relatively low cost. However, the theoretical specific capacity of graphite anodes is only 372 mAh / g, a value that is gradually failing to meet the market's demand for high-energy storage, especially in the context of pursuing long-range and lightweight electric vehicles. Therefore, finding and developing anode materials with higher energy density has become a research hotspot in the industry.

[0004] Among numerous potential high-energy-density anode materials, silicon-based materials are considered an ideal alternative to graphite due to their abundant natural reserves (the second most abundant element in the Earth's crust) and extremely high theoretical specific capacity (up to 4200 mAh / g), possessing enormous commercial potential. However, silicon-based materials face a severe challenge in practical applications: they undergo significant volume expansion during charge and discharge, with expansion rates reaching up to 300%. This volume effect not only leads to the crushing and shedding of silicon active materials, disrupting the integrity of the electrode structure, but also causes repeated formation and rupture of the solid electrolyte interphase (SEI) film, accelerating electrolyte consumption and Li+ ion loss, thereby severely impairing the battery's cycle performance and safety, hindering the commercialization of silicon-based anode materials.

[0005] Therefore, there is an urgent need to find a material that can alleviate the volume expansion of silicon during cycling, so as to make full use of silicon-based anode materials. Summary of the Invention

[0006] The technical problem to be solved by this invention is that existing silicon-based anode materials exhibit significant volume expansion during charge and discharge, which hinders the commercialization of silicon-based anode materials. The purpose is to provide a three-dimensional mesoporous carbon composite silicon-carbon anode material, its preparation method, and its application. By utilizing the supporting effect of the three-dimensional structure, sufficient space is provided for silicon particles to alleviate their volume expansion during charge and discharge, while maintaining the integrity and stability of the electrode structure, extending the cycle life of the battery, and promoting the commercial application of silicon-based anode materials.

[0007] This invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material, comprising the following steps:

[0009] Additive 1 and Additive 2 were dissolved in deionized water to obtain solution A and solution B respectively. Under stirring, solution A was added to solution B to obtain solution C. Additive 1 is a silicon source material.

[0010] Additive 3 was dissolved in deionized water to obtain solution D. Solution C was added to solution D while stirring to obtain solution E.

[0011] Solution E was aged and then subjected to a hydrothermal reaction to obtain the reaction product.

[0012] The supernatant of the reaction product was discarded, and the product was collected by centrifugation, dried, and calcined at high temperature to obtain template A.

[0013] Additive 4 was dissolved in solvent 1 to obtain solution F;

[0014] A carbon source solution was added dropwise to solution F, and solution G was obtained after the reaction.

[0015] Solution G was gradually permeated into template A, stirred, dried, and cured at high temperature to obtain template B;

[0016] The pore-forming agent and template B were added to deionized water, mixed evenly, and dried to obtain the sample.

[0017] The sample was calcined under oxygen-free conditions to obtain a carbonized sample;

[0018] The carbonized sample was placed in solvent 2 and stirred to disperse it. After centrifugation and drying, the dried sample was obtained.

[0019] The dried sample was activated at high temperature in a carbon dioxide gas environment to obtain a three-dimensional mesoporous carbon material;

[0020] Three-dimensional mesoporous carbon materials were subjected to chemical vapor deposition to obtain three-dimensional mesoporous carbon composite silicon-carbon anode materials.

[0021] As one possible design, the above-mentioned additive 1 is dissolved in deionized water by adding additive 1 to deionized water, heating and stirring until dissolved, and then adding hydrochloric acid to adjust the pH to 3-4 to obtain solution A; the above-mentioned additive 2 is dissolved in deionized water by repeatedly soaking and rinsing the additive 2 with hydrochloric acid to disperse it, then rinsing the additive 2 with deionized water until the pH=7, and then adding deionized water and stirring to dissolve to obtain solution B.

[0022] The additive 1 includes one or more of sodium silicate, tetraethyl orthosilicate, and methyl orthosilicate; the additive 2 is a cation exchange resin.

[0023] As one possible design, the above-mentioned additive 3 is dissolved in deionized water by adding additive 3 to deionized water, heating and stirring until dissolved, and then adding hydrochloric acid to adjust the pH to 2-4 to obtain solution D;

[0024] Additive 3 is hexadecyltrimethylammonium bromide.

[0025] As one possible design, the above-mentioned aging treatment of solution E specifically involves aging solution E at 15-35℃ for 12-24 hours.

[0026] As one possible design, the drying temperature of the above reaction products is 60-80℃, the drying time is 8-10h; the calcination temperature is 500-600℃, the calcination time is 5-6h, and the calcination heating rate is 2-5℃ / min.

[0027] As one possible design, the above-mentioned dissolving additive 4 in solvent 1 specifically involves dissolving additive 4 in solvent 1, stirring at room temperature until dissolved, and then adding hydrochloric acid to adjust the pH to 1-2 to obtain solution F;

[0028] The additive 4 is a nonionic surfactant; the solvent 1 is an aqueous ethanol solution.

[0029] As one possible design, after adding the carbon source solution to the above solution F, the mass ratio of additive 4 to carbon source is 1:(3-7); the carbon source includes one or more of phenolic resin, polyacrylonitrile, and polydopamine;

[0030] The mass ratio of the pore-forming agent to template B is 1:(1.8-2.2); the pore-forming agent includes one or more of sodium carbonate, urea, ammonium nitrate, and zinc chloride;

[0031] The solvent 2 is a NaOH solution or an HF solution;

[0032] The high-temperature activation specifically involves activating at 750-850℃ for 1-2 hours.

[0033] The three-dimensional mesoporous carbon material has an ant nest-like shape.

[0034] As one possible design, the chemical vapor deposition of the three-dimensional mesoporous carbon material specifically includes the following steps:

[0035] Three-dimensional mesoporous carbon material is uniformly spread in a quartz boat, placed in the center of a chemical vapor deposition reaction chamber, and an inert gas is introduced to clean the reaction chamber.

[0036] Mixed gas 1 is introduced into the chemical vapor deposition reaction chamber to perform a single deposition of three-dimensional mesoporous carbon material, wherein mixed gas 1 includes silicon source gas;

[0037] Mixed gas 2 is introduced into the chemical vapor deposition reaction chamber to perform secondary deposition on three-dimensional mesoporous carbon materials. Mixed gas 2 includes carbon source gas.

[0038] The three-dimensional mesoporous carbon material after secondary deposition was subjected to inert gas annealing to obtain a three-dimensional mesoporous carbon composite silicon-carbon anode material.

[0039] Secondly, the present invention provides a three-dimensional mesoporous carbon composite silicon-carbon anode material, which is prepared by the above-described preparation method.

[0040] Thirdly, the present invention provides the application of the three-dimensional mesoporous carbon composite silicon-carbon anode material prepared by the above preparation method in battery materials.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] The carbon material with an ant-nest-like three-dimensional mesoporous structure prepared by this invention achieves optimization of the hierarchical pore structure, forming a three-dimensional network system of interconnected macropores and mesopores. This not only increases the specific surface area of ​​the material but also significantly enhances the connectivity of the pores. Adjustable parameters during the preparation process allow for controllable pore size, pore distribution, and structure, enhancing the application flexibility and controllability of the material and overcoming the shortcomings of traditional single-template methods in pore size control and pore connectivity. Simultaneously, the hierarchical pore structure improves the diffusion rate of ions and molecules, resulting in higher charge-discharge efficiency and longer cycle life in electrochemical devices such as lithium batteries. Furthermore, the three-dimensional network structure endows the material with excellent mechanical strength and thermal stability, maintaining stability under high temperature or high pressure environments, thus solving the problem of easy collapse or deformation in traditional mesoporous carbon materials.

[0043] Specifically, this invention uses calcination to form mesoporous silica as a template for porous carbon, providing a basic framework for its preparation. Adding additive 4 and a carbon source promotes the formation of smaller pores in the material. Combined with the action of a pore-forming agent, an ordered mesoporous structure is further formed within the macroporous structure. The mesopores and macropores are effectively connected, forming a multi-level pore system. The combination of multiple treatments significantly increases the specific surface area of ​​the material, forming an ant-nest-like three-dimensional mesoporous structure. In this ant-nest structure, the pores often exhibit small outlets and large pore volumes. The smaller pore outlets help reduce the escape of active materials such as silicon during charging and discharging. The advantage of this structure is that even if the material undergoes expansion or contraction (such as the volume change of a silicon anode), the small pore outlets can still effectively limit material escape, while the presence of macropores and mesopores can accommodate and support the expanded material. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0045] Figure 1 The diagram shows a cross-sectional view (left) and a structural diagram (right) of the honeycomb structure of the three-dimensional mesoporous carbon composite silicon-carbon anode material of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0047] Existing silicon-based anode materials exhibit significant volume expansion during charge and discharge, hindering their commercialization. To address this issue, this invention provides a method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material. By employing a high-mechanical-strength mesoporous carbon structure as a scaffold, a three-dimensional network is constructed, effectively limiting the volume expansion of silicon particles during charge and discharge through physical constraint. The unique structure of mesoporous carbon not only endows the material with excellent mechanical stability but also provides a large specific surface area and suitable pore volume, which is beneficial for electrolyte penetration and Li... + The rapid transport of these materials improves cycle stability and optimizes the specific capacity of the material. This technological improvement not only solves key problems such as low cell cycle capacity and short cycle life caused by the volume expansion of silicon-based anode materials, but also opens up new directions for the research and development of high-performance lithium-ion battery anode materials.

[0048] A method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material includes the following steps:

[0049] S1. Dissolve additive 1 and additive 2 in deionized water to obtain solution A and solution B respectively. Add solution A to solution B while stirring to obtain solution C. The additive 1 is a silicon source material.

[0050] Preferably, the mass ratio of additive 1 to deionized water is 1:(10-20), and the mass ratio of additive 2 to deionized water is 1:(20-30).

[0051] Preferably, the volume ratio of solution A to solution B is 1:(1-1.5).

[0052] In some embodiments of the present invention, step S1 above includes the following steps:

[0053] S101. Add additive 1 to deionized water, heat and stir until melted, then add hydrochloric acid to adjust the pH to 3-4 to obtain solution A.

[0054] S102. Disperse additive 2 by repeatedly soaking and rinsing with hydrochloric acid, then rinse additive 2 with deionized water until pH=7, add deionized water and stir to dissolve to obtain solution B.

[0055] Preferably, the melting temperature is 40-60℃ and the mixer speed is 20-60 rpm / min.

[0056] S103. While stirring, slowly add solution A to solution B, and stir at room temperature (15-35℃) for 1-2 hours to avoid local precipitation, to obtain solution C.

[0057] In some embodiments of the present invention, the additive 1 includes one or more of sodium silicate, tetraethyl orthosilicate and methyl orthosilicate; the additive 2 is a cation exchange resin, preferably a hydrogen-form cation exchange resin (H+ form).

[0058] S2. Dissolve additive 3 in deionized water to obtain solution D. Add solution C to solution D while stirring to obtain solution E.

[0059] Preferably, the mass ratio of the above-mentioned additive 3 to deionized water is 1:(20-30).

[0060] Preferably, the volume ratio of solution C to solution D is 1:(1-1.5).

[0061] In some embodiments of the present invention, step S2 above includes the following steps:

[0062] S201. Add additive 3 to deionized water, heat and stir until melted, then add hydrochloric acid to adjust the pH to 2-4 to obtain solution D.

[0063] Preferably, the heating temperature is 40-60℃ and the mixer speed is 20-60 rpm / min.

[0064] S202. Under stirring, slowly add solution C to solution D, stir at room temperature for 1-2 hours to avoid local precipitation, and obtain solution E.

[0065] In some embodiments of the present invention, the additive 3 is hexadecyltrimethylammonium bromide (CTAB).

[0066] S3. Aging solution E and then carrying out a hydrothermal reaction to obtain the reaction product.

[0067] In some embodiments of the present invention, the above-mentioned aging specifically refers to aging solution E at room temperature (15-35°C) for 12-24 hours.

[0068] Preferably, the hydrothermal reaction temperature is 100-120℃ and the hydrothermal time is 6-12h.

[0069] S4. Discard the supernatant of the reaction product, collect it by centrifugation, dry it, and calcine it at high temperature to obtain template A.

[0070] Specifically, mesoporous silica is formed by calcination as a template for porous carbon. Mesoporous silica is a hard material with macroporous characteristics. Under high temperature conditions, these templates form a skeleton structure of carbon materials through carbonization or sintering. This skeleton structure has excellent mechanical strength and provides a basic framework for the preparation of porous carbon.

[0071] In some embodiments of the present invention, the drying temperature of the above reaction product is 60-80℃, the drying time is 8-10h; the calcination temperature is 500-600℃, the calcination time is 5-6h, and the calcination heating rate is 2-5℃ / min.

[0072] S5. Dissolve additive 4 in solvent 1 to obtain solution F.

[0073] Preferably, the mass ratio of the above-mentioned additive 3 to solvent 1 is 1:(10-14).

[0074] In some embodiments of the present invention, step S5 specifically involves dissolving additive 4 in solvent 1, stirring at room temperature until dissolved, and then adding hydrochloric acid to adjust the pH to 1-2 to obtain solution F.

[0075] Preferably, the additive 4 is a nonionic surfactant, preferably a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123). The addition of P123 and a carbon source can promote the formation of smaller voids in the material.

[0076] In some embodiments of the present invention, solvent 1 is an aqueous solution of ethanol.

[0077] Preferably, the mass ratio of water to ethanol in solvent 1 is (2.5-3.5):1. More preferably, the water:ethanol ratio is 3:1.

[0078] S6. Add carbon source solution dropwise to solution F, and after the reaction, solution G is obtained.

[0079] Adding additive 4 and a carbon source can promote the formation of smaller pores in the material, which is a key step in controlling the specific surface area and pore volume of the material.

[0080] Preferably, the above reaction is carried out by stirring at room temperature for 10-14 hours, preferably 12 hours.

[0081] In some embodiments of the present invention, the carbon source includes one or more of phenolic resin, polyacrylonitrile, and polydopamine.

[0082] In some embodiments of the present invention, after the above solution F is added to the carbon source solution, the mass ratio of additive 4 to carbon source is 1:(3-7).

[0083] The carbon source solution permeates and fills the pores of template A, forming a uniform carbon framework structure. As the carbon source permeates the template pores, it solidifies at high temperatures to form a highly stable carbon framework. This carbon framework is further strengthened during subsequent high-temperature calcination, thus constructing the final three-dimensional mesoporous carbon structure. If the proportion of carbon source is too high, excessive carbon deposition may occur, potentially filling the template pores and resulting in an incomplete or damaged pore structure, thereby reducing the specific surface area and pore volume of the final material. Excessive carbon deposition can also lead to pore blockage, affecting the formation of a hierarchical porous system. If the proportion of carbon source is too low, sufficient carbon framework may not be formed on the template, resulting in an incomplete or insufficiently strong porous structure. Insufficient carbon source will result in a lower specific surface area and uneven pore size in the final carbon material, affecting its mechanical and electrochemical properties. The ideal carbon source ratio should provide sufficient carbon deposition to form a stable framework while avoiding excessive pore filling. An appropriate amount of carbon source can ensure that the pores of the template remain open, forming a good three-dimensional mesoporous structure, thereby optimizing the specific surface area, pore volume, and pore connectivity. P123: Carbon source = 1:(3-7), this range can usually obtain a relatively uniform and efficient multi-level porous structure.

[0084] S7. Solution G is gradually permeated into template A, stirred, dried, and cured at high temperature to obtain template B.

[0085] Preferably, the mass ratio of the above solution G to template A is (2-3):1.

[0086] Preferably, the stirring is carried out at room temperature for 10-14 hours, more preferably 12 hours.

[0087] Preferably, the drying temperature is 60°C and the drying time is 10-14 hours, preferably 12 hours.

[0088] Preferably, the high-temperature curing temperature is 100-140℃, more preferably 120℃; the high-temperature curing time is 4-6h.

[0089] S8. Add the pore-forming agent and template B to deionized water, mix well, and dry to obtain the sample.

[0090] While templates B themselves provide a structural framework and a certain pore size, they cannot fully generate complex pore networks or completely optimize the distribution, connectivity, and morphology of pores. Therefore, pore-forming agents are still needed to further enrich and optimize the pore structure. Pore-forming agents mainly generate pores at high temperatures through chemical reactions or gas release, and these pores can refine and expand the existing pore network. Templates mainly form macropores and mesopores, and the number and morphology of pores may be limited. Adding pore-forming agents can introduce micropores, further increasing the density and diversity of pores and forming a multi-level pore structure. Pore-forming agents can precisely regulate pore formation, forming pores of different shapes and sizes through gas release, chemical reactions, etc. The pores formed by templates are often relatively fixed in size and distribution, and cannot fully meet the requirements for pore diversity and uniformity. The addition of pore-forming agents can supplement and refine these pores, optimizing their morphology and distribution.

[0091] Preferably, the mass ratio of the pore-forming agent to template B is 1:(1-3).

[0092] Preferably, step S8 involves adding the pore-forming agent and template B to deionized water and stirring for 12 hours to ensure thorough mixing, followed by drying for 10-14 hours to obtain the sample. The drying time is preferably 12 hours.

[0093] In some embodiments of the present invention, the mass ratio of the pore-forming agent to template B is 1:(1.8-2.2), preferably 1:2.

[0094] In some embodiments of the present invention, the pore-forming agent includes one or more of sodium carbonate, urea, ammonium nitrate, and zinc chloride.

[0095] Preferably, the drying temperature is 80-100℃.

[0096] S9. Calcine the sample under oxygen-free conditions to obtain a carbonized sample.

[0097] Specifically, S9 involves placing the sample in a tube furnace and calcining it in an inert gas atmosphere to obtain a carbonized sample.

[0098] The calcination temperature is 800-1000℃, the heating rate is 5℃ / min, and the calcination time is 2h; the inert gas is one or more of argon and nitrogen, and the gas flow rate is 1-5L / min.

[0099] S10. Place the carbonized sample in solvent 2, stir and disperse, and then centrifuge and dry to obtain a dry sample.

[0100] In some embodiments of the present invention, solvent 2 is a NaOH solution or an HF solution.

[0101] Preferably, solvent 2 is a 2M NaOH solution or a 5wt% HF solution; the stirring time is 10-14h, preferably 12h.

[0102] S11. The dried sample is activated at high temperature in a carbon dioxide gas environment to obtain a three-dimensional mesoporous carbon material.

[0103] Preferably, the above-mentioned high-temperature activation is specifically carried out at 750-850℃ for 1-2 hours. Preferably, the activation temperature is 800℃.

[0104] In some embodiments of the present invention, the above-mentioned three-dimensional mesoporous carbon material is ant nest shaped.

[0105] S12. Chemical vapor deposition (CVD) is performed on the three-dimensional mesoporous carbon material to obtain a three-dimensional mesoporous carbon composite silicon-carbon anode material.

[0106] In some embodiments of the present invention, S12 above includes the following steps:

[0107] S1201. The three-dimensional mesoporous carbon material is evenly spread in a quartz boat, placed in the center of the chemical vapor deposition reaction chamber, and an inert gas is introduced to clean the reaction chamber.

[0108] Preferably, the inert gas is nitrogen and / or argon; the inert gas flow rate is 200 mL / min, and the cleaning time is 15-30 min.

[0109] S1202. Mixed gas 1 is introduced into the chemical vapor deposition reaction chamber to perform a single deposition of three-dimensional mesoporous carbon material, wherein mixed gas 1 includes silicon source gas.

[0110] Preferably, the above-mentioned deposition is carried out at 400-600℃ for 30-60 minutes.

[0111] Preferably, the above-mentioned mixed gas 1 includes a silicon source gas and a carrier gas. The silicon source gas includes SiH4 and / or SiCl4; the carrier gas is nitrogen and / or argon. The silicon source gas flow rate is 10–20 mL / min; the carrier gas flow rate is 200 mL / min.

[0112] S1203. A mixed gas 2 is introduced into the chemical vapor deposition reaction chamber to perform secondary deposition of the three-dimensional mesoporous carbon material, wherein the mixed gas 2 includes a carbon source gas.

[0113] Preferably, the above-mentioned secondary deposition is carried out at 700-900℃ for 30-60 minutes.

[0114] Preferably, the above-mentioned mixed gas 2 includes a carbon source gas and a carrier gas. The carbon source gas includes C2H2, C2H4, and / or CH4. The carrier gas is nitrogen and / or argon. The flow rate of the carbon source gas is 10–20 mL / min; the flow rate of the carrier gas is 200 mL / min.

[0115] S1204. The three-dimensional mesoporous carbon material after secondary deposition is subjected to inert gas annealing treatment to obtain a three-dimensional mesoporous carbon composite silicon-carbon anode material.

[0116] Preferably, the annealing temperature is 700-900℃ and the annealing time is 1-2h.

[0117] The present invention also provides a three-dimensional mesoporous carbon composite silicon-carbon anode material, which is prepared by the above-described preparation method.

[0118] The present invention also provides the application of the three-dimensional mesoporous carbon composite silicon-carbon anode material prepared by the above preparation method in battery materials.

[0119] Example 1

[0120] S1: Weigh 66.7g of additive 1 and add it to 1000g of deionized water. Heat and stir until dissolved, then add hydrochloric acid to adjust the pH to 4 to obtain solution A. Weigh 40g of additive 2, repeatedly soak and rinse it with hydrochloric acid to disperse it, then rinse it with deionized water until the pH is 7, and add deionized water to dissolve it to obtain solution B. While stirring, add 1000mL of solution A to 1200mL of solution B, slowly adding solution A dropwise to solution B. Stir at room temperature for 2 hours to avoid local precipitation to obtain solution C. Additive 1 is sodium silicate, additive 2 is cation exchange resin (H+ type), the heating temperature is 50℃, and the stirring speed is 50rpm / min.

[0121] S2: Weigh 40g of additive 3 and add it to deionized water. Heat and stir until dissolved. Then add hydrochloric acid to adjust the pH to 4 to obtain solution D. While stirring, add 1000mL of solution C to 1200mL of solution D. Slowly add solution C to solution D and stir at room temperature for 2 hours to avoid local precipitation, to obtain solution E. Additive 3 is hexadecyltrimethylammonium bromide (CTAB). The heating temperature is 60℃ and the stirring speed is 50rpm / min.

[0122] S3: Let solution E stand at room temperature for 24 hours, then transfer it to a hydrothermal reactor for hydrothermal reaction. The reaction temperature is 120℃ and the hydrothermal time is 12 hours.

[0123] S4: Discard the supernatant of the above reaction product, collect it by centrifugation, and then dry it. Place the dried product in a muffle furnace for high-temperature calcination to obtain template A. The drying temperature is 70℃, the drying time is 10h; the calcination temperature is 600℃, the calcination time is 6h, and the heating rate is 5℃ / min.

[0124] S5: Weigh an appropriate amount of additive 4 (83.3g) and dissolve it in 1000g of solvent 1. Stir at room temperature until dissolved, then add hydrochloric acid to adjust the pH to 2 to obtain solution F. Additive 4 is P123, and the solvent is a mixture of water and ethanol with a mass ratio of water:ethanol = 3:1.

[0125] S6: Add carbon source solution dropwise to solution F and stir continuously at room temperature for 12 hours to obtain solution G. The carbon source is phenolic resin, and the mass ratio of solution P123:carbon source = 1:3.

[0126] S7: 250g of solution G was dripped into 100g of template A, stirred at room temperature for 12 hours, dried, and then cured at high temperature to obtain template B. The drying temperature was 60℃ and the drying time was 12 hours; the curing temperature was 120℃ and the curing time was 6 hours.

[0127] S8: Dissolve 100g of pore-forming agent (zinc chloride) and 200g of template B in deionized water and stir for 12 hours to ensure thorough mixing. Then dry for 12 hours to obtain the sample. The pore-forming agent is zinc chloride, and the mass ratio of pore-forming agent to template B is 1:2. The drying temperature is 80℃.

[0128] S9: The above sample was placed in a tube furnace and calcined under an inert gas atmosphere to obtain a carbonized sample. The calcination temperature was 1000℃, the heating rate was 5℃ / min, and the calcination time was 2h; the inert gas was nitrogen, and the gas flow rate was 5L / min.

[0129] S10: The carbonized sample was dispersed in a solvent at room temperature by stirring, and then centrifuged and dried to obtain the final sample. The solvent was 2M NaOH solution, and the stirring time was 12 hours.

[0130] S11: The above sample was activated at high temperature in a CO2 gas environment to obtain an ant-nest-shaped three-dimensional mesoporous carbon material. The activation temperature was 800℃ and the activation time was 2h.

[0131] S12: Spread the ant-nest-shaped three-dimensional mesoporous carbon material evenly in a quartz boat, place it in the center of the CVD reaction chamber, and purge the reaction chamber with inert gas, which is nitrogen, with a flow rate of 200 mL / min and a purging time of 30 min.

[0132] A mixed gas was introduced for high-temperature deposition. The mixed gas consisted of silicon source gas (SiH4, gas flow rate of 20 mL / min) and carrier gas (nitrogen, gas flow rate of 200 mL / min). The temperature was 600℃ and the deposition time was 60 minutes.

[0133] A mixed gas was introduced for high-temperature deposition. The mixed gas consisted of a carbon source gas (CH4, with a flow rate of 20 mL / min) and a carrier gas (nitrogen, with a flow rate of 200 mL / min). The temperature was 800 °C and the deposition time was 60 minutes.

[0134] The above samples were subjected to inert gas annealing to obtain three-dimensional mesoporous carbon composite silicon-carbon anode materials (such as...). Figure 1 As shown in the figure, the inert gas is nitrogen, the annealing temperature is 800℃, and the annealing time is 2h.

[0135] Example 2

[0136] This embodiment is basically the same as Embodiment 1, except that the mass ratio of P123 to carbon source in S6 is 1:4, and other conditions are the same.

[0137] Example 3:

[0138] This embodiment is basically the same as Embodiment 1, except that the mass ratio of P123 to carbon source in S6 is 1:5, and other conditions are the same.

[0139] Example 4

[0140] This embodiment is basically the same as Embodiment 1, except that the mass ratio of P123 to carbon source in S6 is 1:6, and other conditions are the same.

[0141] Example 5

[0142] This embodiment is basically the same as Embodiment 1, except that the mass ratio of P123 to carbon source in S6 is 1:7, and other conditions are the same.

[0143] Example 6

[0144] This embodiment is basically the same as embodiment 1, except that the pore-forming agent in S8 is urea.

[0145] Example 7

[0146] This embodiment is basically the same as that of embodiment 1, except that the pore-forming agent in S8 is ammonium nitrate.

[0147] Example 8

[0148] This embodiment is basically the same as that of embodiment 1, except that the carbon source in S6 is polydopamine.

[0149] Example 9

[0150] This embodiment is basically the same as Embodiment 1, except that: in S1, the amount of additive 1 is 100g, the amount of additive 2 is 50g, and the volume ratio of solution A to B is 1:1.5; in S2, the volume ratio of solution C to D is 1:1.5; in S4, the amount of additive 4 is 100g; in S7, the ratio of solution G to template A is 2:1; and in S8, the ratio of pore-forming agent to template B is 1:3.

[0151] Comparative Example 1:

[0152] This comparative example is basically the same as Example 1, except that: in S6, the mass ratio of P123 to carbon source is 1:5, and the pore-forming treatment in S8 is not performed, while the other conditions are the same.

[0153] Comparative Example 2:

[0154] This comparative example is basically the same as Example 1, except that: in S6, the mass ratio of P123 to carbon source is 1:6, and the pore-forming treatment in S8 is not performed, while the other conditions are the same.

[0155] Comparative Example 3

[0156] This comparative example is basically the same as Example 1, except that: in S6, the mass ratio of P123 to carbon source is 1:7, and the pore-forming treatment in S8 is not performed, while the other conditions are the same.

[0157] Comparative Example 4

[0158] This comparative example is basically the same as Example 1, except that the mass ratio of P123 to carbon source in S6 is 1:2.

[0159] Comparative Example 5

[0160] This comparative example is basically the same as Example 1, except that the mass ratio of P123 to carbon source in S6 is 1:10.

[0161] Experimental Example 1

[0162] The three-dimensional mesoporous carbon composite silicon-carbon anode materials obtained in Examples 1-5 and Comparative Examples 1-3 were used to fabricate coin cells, wherein the mass ratio of silicon-carbon, SP, CNT, CMC, and SBR was 92:2:2:1.5:2.5. The materials were mixed and stirred to form a slurry, which was then coated onto a copper foil current collector. Finally, CR2032 coin cells were fabricated and tested within a voltage window of 0.005-1.5V. The specific surface area, pore volume, specific capacity, and cycle performance of the cells were measured, and the results are shown in Table 1.

[0163] Table 1

[0164]

[0165] As shown in Table 1, when the mass ratio of P123 to carbon source is 1:5, the material exhibits the highest specific surface area, pore volume, specific capacity, and cycle performance, resulting in high battery energy density, high charge-discharge efficiency, and long battery life. Comparing Example 1 and Comparative Examples 1-3, it can be seen that even with a P123 to carbon source mass ratio of 1:5, the specific surface area decreases by nearly 500 without the use of a pore-forming agent. This indicates that both the use of a pore-forming agent and the P123 to carbon source mass ratio have a significant impact on battery performance. Further comparing Example 1 and Comparative Examples 4-5, when the P123 to carbon source mass ratio is 1:2, the specific surface area decreases to 372.1, indicating that fewer pores affect battery performance, leading to poor charge-discharge efficiency and a shorter cycle life. Similarly, when the ratio is 1:10, the specific surface area decreases to 306.2, also resulting in poor charge-discharge efficiency and a shorter cycle life. It can be seen that the performance is optimal when the mass ratio of P123 to carbon source is 1:(3-7).

[0166] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material, characterized in that, Includes the following steps: Additive 1 and Additive 2 are dissolved in deionized water to obtain solution A and solution B, respectively. Solution A is added to solution B under stirring to obtain solution C. Additive 1 includes one or more of sodium silicate, tetraethyl orthosilicate and methyl orthosilicate. Additive 2 is a cation exchange resin. Additive 3 is dissolved in deionized water to obtain solution D. Solution C is added to solution D under stirring to obtain solution E. The additive 3 is hexadecyltrimethylammonium bromide. Solution E was aged and then subjected to a hydrothermal reaction to obtain the reaction product. The supernatant of the reaction product was discarded, and the product was collected by centrifugation, dried, and calcined at high temperature to obtain template A. Additive 4 is dissolved in solvent 1 to obtain solution F, wherein additive 4 is a nonionic surfactant; A carbon source solution was added dropwise to solution F, and solution G was obtained after the reaction. Solution G was gradually permeated into template A, stirred, dried, and cured at high temperature to obtain template B; The pore-forming agent and template B were added to deionized water, mixed evenly, and dried to obtain the sample. The sample was calcined under oxygen-free conditions to obtain a carbonized sample; The carbonized sample was placed in solvent 2 and stirred to disperse it. After centrifugation and drying, the dried sample was obtained. The dried sample was activated at high temperature in a carbon dioxide gas environment to obtain a three-dimensional mesoporous carbon material; Three-dimensional mesoporous carbon materials were subjected to chemical vapor deposition to obtain three-dimensional mesoporous carbon composite silicon-carbon anode materials.

2. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, The additive 1 is dissolved in deionized water by adding the additive 1 to deionized water, heating and stirring until dissolved, and then adding hydrochloric acid to adjust the pH to 3-4 to obtain solution A; the additive 2 is dissolved in deionized water by repeatedly soaking and rinsing the additive 2 with hydrochloric acid to disperse it, then rinsing the additive 2 with deionized water until the pH=7, and then adding deionized water and stirring to dissolve to obtain solution B.

3. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, The additive 3 is dissolved in deionized water by adding additive 3 to deionized water, heating and stirring until dissolved, and then adding hydrochloric acid to adjust the pH to 2-4 to obtain solution D.

4. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, The aging process of solution E specifically involves aging solution E at 15-35℃ for 12-24 hours.

5. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, The reaction product is dried at a temperature of 60-80℃ for 8-10 hours; the calcination temperature is 500-600℃ for 5-6 hours, and the calcination heating rate is 2-5℃ / min.

6. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, The process of dissolving additive 4 in solvent 1 specifically involves dissolving additive 4 in solvent 1, stirring at room temperature until dissolved, and then adding hydrochloric acid to adjust the pH to 1-2 to obtain solution F. Solvent 1 is an aqueous solution of ethanol.

7. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, After the carbon source solution is added to solution F, the mass ratio of additive 4 to carbon source is 1:(3-7); the carbon source includes one or more of phenolic resin, polyacrylonitrile and polydopamine. The mass ratio of the pore-forming agent to template B is 1:(1.8-2.2); the pore-forming agent includes one or more of sodium carbonate, urea, ammonium nitrate, and zinc chloride; The solvent 2 is a NaOH solution or an HF solution; The high-temperature activation specifically involves activating at 750-850℃ for 1-2 hours. The three-dimensional mesoporous carbon material has an ant nest-like shape.

8. The method for preparing a three-dimensional mesoporous carbon composite silicon-carbon anode material according to claim 1, characterized in that, The chemical vapor deposition of the three-dimensional mesoporous carbon material specifically includes the following steps: Three-dimensional mesoporous carbon material is uniformly spread in a quartz boat, placed in the center of a chemical vapor deposition reaction chamber, and an inert gas is introduced to clean the reaction chamber. Mixed gas 1 is introduced into the chemical vapor deposition reaction chamber to perform a single deposition of three-dimensional mesoporous carbon material, wherein mixed gas 1 includes silicon source gas; Mixed gas 2 is introduced into the chemical vapor deposition reaction chamber to perform secondary deposition on three-dimensional mesoporous carbon materials. Mixed gas 2 includes carbon source gas. The three-dimensional mesoporous carbon material after secondary deposition was subjected to inert gas annealing to obtain a three-dimensional mesoporous carbon composite silicon-carbon anode material.

9. A three-dimensional mesoporous carbon composite silicon-carbon anode material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of a three-dimensional mesoporous carbon composite silicon-carbon anode material prepared by the preparation method according to any one of claims 1 to 8 in battery materials.

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