Material based on nanosilicon composite porous carbon matrix and preparation method and application thereof

Abstract

This invention relates to a material based on a nano-silicon composite porous carbon matrix, its preparation method, and its application. The material based on the nano-silicon composite porous carbon matrix includes a core and a shell. The core comprises a porous carbon matrix and nano-silicon particles embedded within it. The porous carbon matrix is ​​composed of a high-temperature resistant polymer and a carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer. The nano-silicon particles fill the pores of the porous carbon matrix, forming the nano-silicon composite porous carbon matrix core. The shell covers the core, forming a coating structure. The high-temperature resistant polymer includes polybenzimidazole and its derivatives; the shell is a carbon coating layer; the particle size D50 of the porous carbon matrix is ​​between 20 nm and 100 μm; the pore size of the porous carbon matrix is ​​between 0.4 nm and 200 nm; and the specific surface area of ​​the porous carbon matrix is ​​300 m². 2 / g-3000m 2 / g; the pore volume of the porous carbon-based matrix is ​​0.1cm³. 3 / g-6.0cm 3 / g.

Description

Technical Field

[0001] This invention relates to the field of new energy materials technology, and in particular to a material based on a nano-silicon composite porous carbon matrix, its preparation method, and its application. Background Technology

[0002] Anode materials are a crucial component of lithium-ion batteries, directly impacting energy density, cycle life, charge / discharge rate, and storage performance. Currently, graphite is the mainstream anode material, with a theoretical specific capacity of 372 mAh / g. However, as various applications demand increasingly higher battery performance, particularly in terms of energy density, graphite's limitations are becoming more apparent. Silicon, with its theoretical specific capacity as high as 4200 mAh / g, significantly outperforms graphite, making high-capacity and abundant silicon-based anode materials increasingly sought after. However, the volume expansion of silicon-based anodes exceeding 300% during charge / discharge poses a significant challenge to their commercial application.

[0003] Compared to traditional grinding methods, chemical vapor deposition (CVD) for preparing silicon-carbon anode materials can effectively reduce the size of silicon nanoparticles by utilizing steric hindrance, thereby mitigating many problems caused by volume expansion to some extent. Although reducing the size of silicon nanoparticles can alleviate the negative effects of expansion, the volume change of silicon during charge and discharge processes still exists, making it difficult for its cycle performance to meet the requirements of power batteries and energy storage batteries.

[0004] Currently, mainstream CVD processes for preparing silicon-carbon anode materials typically use porous carbon as the matrix. Nanoscale silicon particles are deposited within this porous structure, and then a layer of carbon material is coated onto the surface using vapor deposition. Therefore, the performance of the porous carbon matrix is ​​crucial to the final performance of the silicon-carbon anode. However, existing porous carbon materials generally suffer from insufficient mechanical strength and toughness, as well as low electrical conductivity. This leads to particle breakage during the rolling process in electrode fabrication, causing the highly active nanoscale silicon particles to oxidize upon exposure to air or undergo side reactions upon contact with the electrolyte, thereby reducing initial discharge efficiency and cycle life. Furthermore, the insufficient electrical conductivity of the porous carbon matrix results in poor charge-discharge rate performance of the anode material, limiting the practical application of silicon-carbon anode materials and the batteries they fabricate.

[0005] Therefore, the development of technologies targeting high-strength porous carbon-based substrates is key to further improving the actual capacity of nano-silicon anodes and the cycle performance of lithium-ion batteries. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a material based on a nano-silicon composite porous carbon matrix, its preparation method, and its applications. This material is obtained by combining a porous carbon matrix formed by the thermal decomposition of a high-temperature resistant polymer (polybenzimidazole and its derivatives) with a conductive material, and then combining this core with nano-silicon particles, followed by carbon coating. The resulting material utilizes the high strength, high stiffness, and high creep resistance of the high-temperature resistant polymer to improve the stress resistance of the matrix and enhance its pressure resistance. Furthermore, the porous carbon matrix formed through partial decomposition of the polymer improves the electrical conductivity of the matrix, strengthens the contact between the nano-silicon particles and the matrix, and further improves the charge / discharge rate performance.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a material based on a nano-silicon composite porous carbon matrix, the material comprising a core and a shell;

[0008] The core comprises a porous carbon matrix and nano-silicon particles embedded in the matrix; the porous carbon matrix is ​​composed of a high-temperature resistant polymer and a carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer, and the nano-silicon particles fill the pores of the porous carbon matrix to form a nano-silicon composite porous carbon matrix core.

[0009] The outer shell covers the core, forming an encapsulation structure;

[0010] The high-temperature resistant polymer includes polybenzimidazole and its derivatives; the outer shell is a carbon coating layer.

[0011] The particle size D50 of the porous carbon matrix is ​​between 20 nm and 100 μm; the pore size of the porous carbon matrix is ​​between 0.4 nm and 200 nm; and the specific surface area of ​​the porous carbon matrix is ​​300 m². 2 / g-3000m 2 / g; the pore volume of the porous carbon-based matrix is ​​0.1cm³. 3 / g-6.0cm 3 / g.

[0012] Preferably, the mass ratio of the porous carbon matrix to the nano-silicon particles is 9:1-4:6;

[0013] The mass ratio of the core to the outer shell is 99.95:0.05-90:10;

[0014] In the porous carbon matrix, the mass ratio of the high-temperature resistant polymer to the carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer is 2:8-7:3;

[0015] The weight-average molecular weight of the polybenzimidazole and its derivatives ranges from 0.20 × 10⁻⁶.5 ~9.98×10 6 between.

[0016] More preferably, the mass ratio of the high-temperature resistant polymer to the carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer is 2:8-5:5.

[0017] Preferably, the carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer is specifically a carbon material formed by thermal decomposition of the high-temperature resistant polymer at a temperature of 650℃-1200℃ for 0.1 hours to 10 hours.

[0018] In a second aspect, embodiments of the present invention provide a method for preparing the material based on a nano-silicon composite porous carbon matrix as described in the first aspect above, the preparation method comprising:

[0019] A high-temperature resistant polymer and a pore-forming agent are added to a solvent and ground to obtain a slurry; wherein the high-temperature resistant polymer includes polybenzimidazole and its derivatives;

[0020] The slurry is subjected to heat treatment. By controlling the temperature and time of the heat treatment, some of the high-temperature polymers undergo thermal decomposition during the heat treatment process to form carbon-based conductive materials, while the other part of the high-temperature polymers remains in an undecomposed state, thus obtaining a precursor of porous carbon-based matrix materials.

[0021] The precursor of the porous carbon matrix material is purified by acid washing or alkaline washing to obtain the porous carbon matrix.

[0022] Under an inert atmosphere, the porous carbon matrix is ​​vapor-deposited using a silicon source gas to obtain a nano-silicon composite porous carbon matrix.

[0023] The nano-silicon composite porous carbon matrix is ​​subjected to carbon coating treatment to form a carbon coating layer on the surface of the nano-silicon composite porous carbon matrix, thereby obtaining the material based on the nano-silicon composite porous carbon matrix.

[0024] Preferably, the porogen includes one or more of SiO2, Al2O3, MgO, and TiO2; the average particle size of the porogen is 1 nm to 100 nm.

[0025] Preferably, the heat treatment of the slurry specifically includes: spray drying the slurry to obtain a powder; and then subjecting the powder to high-temperature treatment in an inert atmosphere; wherein the inlet temperature of the spray dryer is 120℃-400℃ and the outlet temperature is 60℃-250℃; the high-temperature treatment temperature is 650℃-1200℃, preferably 650℃-950℃, and the time is 0.1 hours-10 hours.

[0026] Preferably, the vapor deposition temperature is 300℃-900℃, and the time is 1 hour-15 hours; the silicon source gas includes one or more of chlorosilanes or silane-containing hydrocarbons.

[0027] The carbon coating treatment is performed at a temperature of 400℃-900℃ for 1 hour to 20 hours; the carbon source used for the carbon coating includes one or more of alkanes, alkenes, and alkynes.

[0028] Thirdly, embodiments of the present invention provide a negative electrode sheet, including a negative electrode material using the material based on a nano-silicon composite porous carbon matrix as described in the first aspect above.

[0029] Fourthly, embodiments of the present invention provide a lithium-ion battery comprising the negative electrode sheet described in the third aspect above.

[0030] The material based on a nano-silicon composite porous carbon matrix provided in this invention has a core and a carbon-coated shell composed of a porous carbon matrix formed by the composite of a high-temperature resistant polymer (polybenzimidazole and its derivatives) and a conductive material formed by its thermal decomposition, and nano-silicon particles. The high strength, high stiffness, and high creep resistance of the high-temperature resistant polymer improve the stress that the matrix can withstand, enhancing the material's pressure resistance. Furthermore, the porous carbon matrix formed by its partial high-temperature decomposition further enhances the mechanical strength of the matrix, while also increasing its electrical conductivity and strengthening the contact between the nano-silicon particles and the matrix, further improving charge-discharge rate performance. This provides stable structural support for the nano-silicon particles deposited in the porous structure of the matrix, reducing the risk of particle breakage and oxidation during rolling, resulting in excellent structural stability and pressure resistance, capable of withstanding the high pressure during battery fabrication and operation. In addition, the outer shell coating reduces the specific surface area of ​​the negative electrode material, minimizing side reactions and helping to improve the initial coulombic efficiency and cycle life of the lithium-ion battery. Attached Figure Description

[0031] Figure 1 A flowchart illustrating the preparation method of a material based on a nano-silicon composite porous carbon matrix provided in an embodiment of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] This invention provides a material based on a nano-silicon composite porous carbon matrix, comprising a core and a shell.

[0034] The core comprises a porous carbon matrix and nano-silicon particles embedded in the matrix. The porous carbon matrix is ​​composed of a high-temperature resistant polymer and a carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer. The nano-silicon particles fill the pores of the porous carbon matrix, forming a nano-silicon composite porous carbon matrix core. The high-temperature resistant polymer includes polybenzimidazole and its derivatives. In the porous carbon matrix, the mass ratio of the high-temperature resistant polymer to the carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer is 2:8-7:3; the mass ratio of the porous carbon matrix to the nano-silicon particles is 9:1-4:6.

[0035] The outer shell covers the core, forming a coating structure; the outer shell is specifically a carbon coating layer; the mass ratio of the core to the outer shell is 99.95:0.05-90:10;

[0036] The particle size D50 of the porous carbon matrix is ​​between 20 nm and 100 μm; the average pore size of the porous carbon matrix is ​​between 0.4 nm and 200 nm; and the specific surface area of ​​the porous carbon matrix is ​​300 m². 2 / g-3000m 2 / g; the pore volume of the porous carbon-based matrix is ​​0.1cm³. 3 / g-6.0cm 3 / g.

[0037] The aforementioned materials based on nano-silicon composite porous carbon matrix can be obtained through the following preparation method.

[0038] The main process is as follows Figure 1 As shown:

[0039] Step 110: Add the high-temperature resistant polymer and pore-forming agent to the solvent and grind them to obtain a slurry.

[0040] The high-temperature resistant polymer includes polybenzimidazole and its derivatives; the porogen includes one or more of SiO2, Al2O3, MgO, and TiO2; the average particle size of the porogen is 1 nm-100 nm. The solvent may include at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), dimethylacetamide (DMA), and dimethyl sulfoxide (DMSO).

[0041] The mass ratio of the high-temperature resistant polymer to the pore-forming agent is preferably 1:4 to 1:0.35, and more preferably 1:3 to 1:0.8.

[0042] The grinding process can be either a one-time mixing of the high-temperature resistant polymer and the pore-forming agent in a solvent followed by grinding, or a combination of mixing and grinding in stages. The preferred method is a combination of mixing and grinding in stages: first, the high-temperature resistant polymer is added to the solvent and milled in a sand mill for a certain period to ensure complete dissolution; then, the pore-forming agent is added and milling continues for a period to ensure uniform mixing of the polymer and agent, thereby forming a uniform porous structure during subsequent heat treatment.

[0043] Step 120: Heat-treat the slurry. By controlling the temperature and time of the heat treatment, some of the high-temperature polymers undergo thermal decomposition during the heat treatment process to form carbon-based conductive materials, while the other part of the high-temperature polymers remains in an undecomposed state, thus obtaining a precursor for porous carbon-based matrix materials.

[0044] Specifically, the heat treatment of the slurry includes two steps: spray drying and high-temperature treatment.

[0045] First, the slurry is spray-dried to obtain a powder; then, the powder is subjected to high-temperature treatment under an inert atmosphere. The inlet temperature of the spray dryer is 120℃-400℃, and the outlet temperature is 60℃-250℃.

[0046] The main purpose of spray drying is to rapidly evaporate the liquid components in the slurry, quickly converting a large batch of slurry into powdery material to facilitate high-temperature processing. At the same time, spray drying produces relatively uniform powder particles, which helps improve uniformity and ensures the consistency of the final material properties.

[0047] The high-temperature treatment can be carried out in a high-temperature furnace. The inert atmosphere can be one or more of nitrogen, argon, and helium, with a gas flow rate of 3 L / min-10 L / min, preferably 5 L / min-8 L / min. The heating rate of the high-temperature furnace is 2℃ / min-8℃ / min, preferably 3℃ / min-6℃ / min. The high-temperature treatment temperature is 650℃-1200℃, preferably 650℃-950℃; the time is 0.1 hours-10 hours, preferably 0.5 hours-8 hours.

[0048] In this invention, the weight-average molecular weight range of polybenzimidazole and its derivatives is preferably 0.20 × 10⁻⁶. 5 ~9.98×10 6 Between 650℃ and 650℃, polybenzimidazole undergoes thermal decomposition, with some chemical bonds in the molecular chain breaking. The higher the temperature, the more violent the thermal decomposition. The polymer structure of polybenzimidazole is destroyed, and some of it undergoes a carbonization reaction, transforming into a carbon-based conductive material with high conductivity and thermal stability.

[0049] By reasonably setting the temperature and time, the thermal decomposition conversion rate of polybenzimidazole can be effectively controlled. In the lower temperature range of 650℃-1200℃, such as 650℃-950℃ or even lower 650℃-850℃, a longer high-temperature treatment process can be maintained. Conversely, in the temperature range of 950℃-1200℃, a shorter high-temperature treatment time can be used. This allows for the regulation of the ratio of carbon-based conductive material generated from the thermal decomposition of the high-temperature resistant polymer, ultimately controlling the mass ratio of the high-temperature resistant polymer to the carbon-based conductive material generated from its thermal decomposition to be 2:8-7:3. The specific control of the above temperature and time can be achieved by those skilled in the art according to the technical path of this invention.

[0050] Step 130: The precursor of the porous carbon-based matrix material is purified by acid washing or alkali washing to obtain the porous carbon-based matrix.

[0051] Specifically, the porous carbon-based matrix material precursor is immersed in an acid solution or alkaline solution at a temperature of 20℃-150℃ (preferably 25℃-90℃) for 1 hour to 72 hours (preferably 4 hours to 48 hours), then washed with deionized water until neutral, and baked to remove moisture to obtain the porous carbon-based matrix.

[0052] The acid solution includes, but is not limited to, one or more of hydrochloric acid, sulfuric acid, acetic acid, citric acid, and hydrofluoric acid; the alkaline solution includes, but is not limited to, sodium hydroxide and / or potassium hydroxide; the molar mass of the acid solution or alkaline solution is 0.1 mol / L to 3.0 mol / L, preferably 0.5 mol / L to 2.0 mol / L.

[0053] The purpose of acid washing or alkaline washing purification is to remove residual pore-forming agents and impurities in porous carbon-based matrix material precursors, thereby improving the purity of the material.

[0054] Step 140: Under an inert atmosphere, a porous carbon-based matrix is ​​vapor-deposited using a silicon source gas to obtain a nano-silicon composite porous carbon-based matrix.

[0055] The silicon source gas includes one or more of chlorosilanes or silane-containing hydrocarbons; the inert atmosphere can be one or more of nitrogen, argon, and helium. Vapor deposition can be carried out in a deposition furnace.

[0056] Specifically, a porous carbon-based substrate is placed in a vapor deposition furnace, and an inert atmosphere is continuously introduced into the furnace at a certain gas flow rate (e.g., 10 L / min). The temperature is then raised to 300℃-600℃ (preferably 350℃-580℃) at a heating rate of 2℃ / min-8℃ / min (preferably 3℃ / min-6℃ / min), and held for 20min-60min to stabilize the temperature. Afterward, silicon source gas and inert carrier gas are introduced into the vapor deposition furnace together in a preset ratio, and the temperature is held for 0.5 hours-25 hours (preferably 1 hour-20 hours) to perform vapor deposition.

[0057] The inert carrier gas includes one or more of nitrogen, argon, and helium. The silicon source gas includes one or more of chlorosilanes or silane-containing hydrocarbons; for example, including but not limited to: silane (SiH4), silane (H6Si2), chlorosilane (SiH3Cl), dichlorosilane (SiH2Cl2), trichlorosilane (SiHCl3), tetrachlorosilane (SiCl4), hexachlorosilane (Si2Cl6), etc.; among which, trichlorosilane (SiHCl3), tetrachlorosilane (SiCl4), and hexachlorosilane (Si2Cl6) are gases formed after high-temperature vaporization.

[0058] The preset ratio of silicon source gas to inert carrier gas is a volume ratio of [1:6] to [5:6], preferably [1:5] to [4:5].

[0059] The nano-silicon composite porous carbon matrix core was prepared through steps 110-140 above. The high-temperature resistant polymer exhibits high stability, high strength, high stiffness, and high creep resistance at high temperatures. The carbon matrix formed in situ by the decomposition of some of the high-temperature resistant polymer further enhances the mechanical strength of the matrix, while also improving its electrical conductivity and strengthening the contact between the nano-silicon particles and the matrix, thus further improving the charge-discharge rate performance. These characteristics enable the nano-silicon composite porous carbon matrix core to withstand the pressure during material deposition, battery processing, and charge-discharge cycles, providing stable structural support for the nano-silicon particles deposited in the porous structure of the matrix. This reduces the risk of particle breakage and oxidation during rolling, resulting in excellent structural stability and pressure resistance, ensuring high initial reversible capacity, first-cycle coulombic efficiency, and long cycle life in anode material applications.

[0060] Step 150: Carbon coating treatment is performed on the nano-silicon composite porous carbon matrix to form a carbon coating layer on the surface of the nano-silicon composite porous carbon matrix, thereby obtaining a material based on the nano-silicon composite porous carbon matrix.

[0061] Specifically, the nano-silicon composite porous carbon matrix is ​​placed in a carbon coating furnace and heated to 300℃-600℃ under an inert atmosphere. Then, a mixture of inert carrier gas and carbon source gas is introduced into the carbon coating furnace and kept at that temperature for 0.5 hours to 20 hours.

[0062] Preferably, the coating temperature is 400℃-580℃, and the coating time is 1 hour-16 hours. The coating thickness can be 2nm-50nm.

[0063] The carbon source gas is one or more of alkanes, alkenes, and alkynes. The volume ratio of the inert carrier gas to the carbon source gas is [1:12]-[5:6], preferably [1:8]-[4:5].

[0064] Surface coating treatment further improves the electronic conductivity of the negative electrode material and enhances its charge-discharge rate performance. At the same time, the carbon coating layer can reduce the specific surface area of ​​the negative electrode material, reduce the occurrence of side reactions in contact with the electrolyte, and thus improve the electronic conductivity and interface stability of the negative electrode material.

[0065] The material based on nano-silicon composite porous carbon matrix described above is used as a negative electrode material and applied to the negative electrode sheet of lithium-ion batteries.

[0066] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0067] Example 1

[0068] The first step is to weigh 12.0 kg of polybenzimidazole, with a molecular weight of 8.21*10. 6 The mixture was added to a sand mill along with 240 kg of N-methylpyrrolidone (NMP) and ground for 2 hours; then 15.0 kg of nano titanium dioxide was added and the mixture was ground for another 6 hours to obtain a slurry.

[0069] The second step involves first spray drying the slurry at an inlet temperature of 220°C and an outlet temperature of 80°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 5 L / min and heated to 670°C at a rate of 3°C / min, held for 8 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1 mol / L hydrochloric acid solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0070] The third step involves placing 1.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a gas flow rate of 10 L / min, and heating the furnace to 350 °C at a heating rate of 6 °C / min. The furnace is then held at this temperature for 30 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 10 L / min: 50 L / min, and the furnace is held at this temperature for another 2 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0071] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 400°C under the same atmosphere. A mixture of nitrogen and acetylene is introduced into the furnace at a ratio of 10 L / min: 20 L / min, and the furnace is held at this temperature for 16 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0072] Subsequently, the prepared nano-silicon composite porous carbon matrix material was used as the negative electrode material to fabricate a lithium-ion battery electrode, and this electrode was used to assemble a coin cell for testing, as detailed below:

[0073] Step 1: The above-mentioned negative electrode material, conductive agent Super P, and binder sodium carboxymethyl cellulose were added to a mortar and ground initially in a mass ratio of 8:1:1. Then, deionized water was added, and the mixture was transferred to a pulping machine and stirred to form a slurry. The obtained slurry was then coated onto a copper foil current collector. Afterward, it was dried in a vacuum oven at 80°C for 12 hours. The dried electrode was then cut into circular pieces with a diameter of 14 mm to serve as the electrode for the coin cell. At this stage, the electrode was not rolled and was designated as electrode 1. Two identical electrode 1s were prepared in this step.

[0074] Step 2: After drying, one of the electrode sheets 1 is rolled at a pressure of 14 MPa to obtain a rolled electrode sheet, which is denoted as electrode sheet 2.

[0075] Step 3: Assemble the electrodes 1 and 2 into coin cells in an argon-filled glove box. The electrolyte is a non-aqueous electrolyte, the lithium salt is 1 mol / L lithium hexafluorophosphate (LiPF6), and the solvent is a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1; the counter electrode is a lithium sheet.

[0076] Step 4: Conduct tests on the Blue Battery Testing System to evaluate the electrochemical performance of the two coin cells. The test temperature is 25℃, and the test voltage window is 0.01V-2V.

[0077] Example 2

[0078] The first step is to weigh 28.0 kg of polybenzimidazole, with a molecular weight of 4.57*10. 6 The mixture was added to a sand mill along with 260 kg of N,N-dimethylformamide (DMF) and ground for 2 hours; then 15.0 kg of nano silica was added and the mixture was ground for another 6 hours to obtain a slurry.

[0079] The second step involves first spray drying the slurry at an inlet temperature of 180°C and an outlet temperature of 100°C to obtain a powder. Then, under a nitrogen flow rate of 5 L / min, the powder is placed in a high-temperature furnace, and the furnace is heated to 700°C at a rate of 3°C / min, and held at that temperature for 6 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1 mol / L sodium hydroxide aqueous solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0080] The third step involves placing 2.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 9 L / min, and heating the furnace to 400°C at a rate of 5°C / min. The furnace is then held at this temperature for 30 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 10 L / min: 45 L / min, and the furnace is held at this temperature for another 4 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0081] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 460°C under the same atmosphere. A mixture of nitrogen and acetylene is introduced into the furnace at a ratio of 10 L / min: 24 L / min, and the furnace is held at this temperature for 12 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0082] The assembly and testing of the button cell are the same as in Example 1.

[0083] Example 3

[0084] The first step is to weigh 18.0 kg of polybenzimidazole, with a molecular weight of 9.12*10. 5 The mixture was added to a sand mill along with 280 kg of dimethyl sulfoxide (DMSO) and ground for 2 hours; then 15.0 kg of nano magnesium oxide was added and the mixture was ground for another 6 hours to obtain a slurry.

[0085] The second step involves first spray drying the slurry at an inlet temperature of 210°C and an outlet temperature of 120°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 5 L / min and heated to 750°C at a rate of 4°C / min, held for 5 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1 mol / L hydrochloric acid solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0086] The third step involves placing 3.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 8 L / min, and heating the furnace to 450°C at a heating rate of 4°C / min. The furnace is then held at this temperature for 30 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 8 L / min: 40 L / min, and the furnace is held at this temperature for another 8 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0087] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 500°C under a nitrogen atmosphere. A mixture of nitrogen and acetylene is introduced into the furnace at a ratio of 10 L / min: 18 L / min, and the furnace is held at this temperature for 14 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0088] The assembly and testing of the button cell are the same as in Example 1.

[0089] Example 4

[0090] The first step is to weigh 10.0 kg of polybenzimidazole, with a molecular weight of 7.72*10. 5 Add 300 kg of tetrahydrofuran to a sand mill and grind for 2 hours; then add 15.0 kg of nano aluminum oxide and continue grinding for 6 hours to obtain a slurry.

[0091] The second step involves first spray drying the slurry at an inlet temperature of 180°C and an outlet temperature of 140°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 6 L / min and heated to 800°C at a rate of 4°C / min, held for 4.0 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 0.8 mol / L hydrochloric acid solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0092] The third step involves placing 5.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 10 L / min, and heating the furnace to 500 °C at a rate of 6 °C / min. The temperature is then maintained for 45 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 15 L / min: 45 L / min, and the temperature is maintained for another 6 hours. This allows the porous carbon material to undergo vapor deposition with silane, resulting in a nano-silicon composite porous carbon matrix.

[0093] Fourthly, under a nitrogen atmosphere, the nano-silicon composite porous carbon matrix was placed in a coating furnace. The furnace was heated to 520°C under nitrogen atmosphere, and then a mixture of nitrogen and methane was introduced into the furnace at a ratio of 10 L / min:32 L / min. The furnace was then held at this temperature for 10 hours to obtain the material based on the nano-silicon composite porous carbon matrix. The assembly and testing of the coin cell were the same as in Example 1.

[0094] Example 5

[0095] The first step is to weigh 40.0 kg of polybenzimidazole, with a molecular weight of 4.39*10. 5 The mixture was added to a sand mill along with 320 kg of dimethylacetamide and ground for 2 hours; then 15.0 kg of nano-silica was added and the mixture was ground for another 6 hours to obtain a slurry.

[0096] The second step involves first spray drying the slurry at an inlet temperature of 200°C and an outlet temperature of 150°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 6 L / min and heated to 850°C at a rate of 4°C / min, held for 3.0 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 2.0 mol / L sodium hydroxide aqueous solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0097] The third step involves placing 6.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 6 L / min, and heating the furnace to 550 °C at a rate of 5 °C / min. The temperature is then maintained for 45 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 6 L / min: 12 L / min, and the temperature is maintained for another 16 hours. This allows the porous carbon material to undergo vapor deposition with silane, resulting in a nano-silicon composite porous carbon matrix.

[0098] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 560°C under a nitrogen atmosphere. A mixture of nitrogen and propane is introduced into the furnace at a ratio of 8 L / min: 12 L / min, and the furnace is held at this temperature for 8 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0099] The assembly and testing of the button cell are the same as in Example 1.

[0100] Example 6

[0101] The first step is to weigh 12.0 kg of polybenzimidazole, with a molecular weight of 3.19*10. 5 The mixture was added to a sand mill along with 360 kg of dimethyl sulfoxide (DMSO) and ground for 2 hours; then 10.0 kg of nano magnesium oxide was added and the mixture was ground for another 6 hours to obtain a slurry.

[0102] The second step involves spray drying the slurry at an inlet temperature of 210°C and an outlet temperature of 130°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 6 L / min and heated to 900°C at a rate of 5°C / min, held for 2.0 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1.8 mol / L acetic acid aqueous solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0103] The third step involves placing 8.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 6 L / min, and heating the furnace to 600°C at a rate of 3°C / min. The temperature is then maintained for 40 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 5 L / min: 12 L / min, and the furnace is maintained for another 24 hours to allow the porous carbon material to undergo vapor deposition with silane, resulting in a nano-silicon composite porous carbon matrix.

[0104] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 600°C under the same nitrogen atmosphere. A mixture of nitrogen and ethane is introduced into the furnace at a ratio of 10 L / min: 16 L / min, and the furnace is held at this temperature for 6 hours to obtain the material based on the nano-silicon composite porous carbon matrix.

[0105] The assembly and testing of the button cell are the same as in Example 1.

[0106] Example 7

[0107] The first step is to weigh 30.0 kg of polybenzimidazole, with a molecular weight of 2.57*10. 5 360 kg of N,N-dimethylformamide was added to a sand mill and ground for 2 hours; then 12.0 kg of nano-silica was added and ground for another 6 hours to obtain a slurry.

[0108] The second step involves spray drying the slurry at an inlet temperature of 200°C and an outlet temperature of 110°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 8 L / min and heated to 950°C at a rate of 5°C / min, held for 2.0 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1.5 mol / L KOH aqueous solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0109] The third step involves placing 10.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 6 L / min, and heating the furnace to 650 °C at a heating rate of 3 °C / min. The furnace is then held at this temperature for 30 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 16 L / min: 25 L / min, and the furnace is held at this temperature for 11 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0110] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 640°C under a nitrogen atmosphere. A mixture of nitrogen and ethane is introduced into the furnace at a ratio of 6 L / min: 10 L / min, and the furnace is held at this temperature for 4 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0111] The assembly and testing of the button cell are the same as in Example 1.

[0112] Example 8

[0113] The first step is to weigh 14.0 kg of polybenzimidazole, with a molecular weight of 1.07*10. 5 It is added together with 400 kg of tetrahydrofuran into a sand mill and ground for 2 hours; then 12.0 kg of nano magnesium oxide is added and ground for another 6 hours to obtain a slurry.

[0114] The second step involves spray drying the slurry at an inlet temperature of 180°C and an outlet temperature of 110°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 8 L / min and heated to 1000°C at a rate of 5°C / min, held for 2 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 2 mol / L citric acid aqueous solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0115] The third step involves placing 12.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a gas flow rate of 10 L / min, and heating the furnace to 700 °C at a heating rate of 4 °C / min. The furnace is then held at this temperature for 45 min. Next, a mixture of chlorosilane and nitrogen gas is introduced at a ratio of 12 L / min: 48 L / min, and the furnace is held at this temperature for another 14 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0116] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 680°C under a nitrogen atmosphere. A mixture of nitrogen and ethylene is introduced into the furnace at a ratio of 8 L / min: 30 L / min, and the furnace is held at this temperature for 2 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0117] The assembly and testing of the button cell are the same as in Example 1.

[0118] Example 9

[0119] The first step is to weigh 22.0 kg of polybenzimidazole, with a molecular weight of 0.79*10. 5 Add 200 kg of dimethylacetamide to a sand mill and grind for 2 hours; then add 12.0 kg of nano aluminum oxide and continue sand milling for 6 hours to obtain a slurry.

[0120] The second step involves first spray drying the slurry at an inlet temperature of 190°C and an outlet temperature of 110°C to obtain a powder. Then, the powder is placed in a high-temperature furnace at a nitrogen flow rate of 8 L / min and heated to 1050°C at a rate of 6°C / min, held for 2 hours to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1.25 mol / L hydrochloric acid solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0121] The third step involves placing 16.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 10 L / min, and heating the furnace to 750 °C at a heating rate of 3 °C / min. The furnace is then held at this temperature for 35 min. Next, a mixture of chlorosilane and nitrogen gas is introduced at a ratio of 24 L / min: 50 L / min, and the furnace is held at this temperature for another 12 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0122] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 720°C under a nitrogen atmosphere. A mixture of nitrogen and propylene gas is introduced into the furnace at a ratio of 10 L / min: 26 L / min, and the furnace is held at this temperature for 1 hour to obtain a material based on the nano-silicon composite porous carbon matrix.

[0123] The assembly and testing of the button cell are the same as in Example 1.

[0124] Example 10

[0125] The first step is to weigh 20.0 kg of polybenzimidazole, with a molecular weight of 0.23*10. 5 The mixture was added to a sand mill along with 240 kg of N,N-dimethylacetamide (DMF) and ground for 2 hours; then 12.0 kg of nano titanium dioxide was added and the mixture was ground for another 6 hours to obtain a slurry.

[0126] The second step involves first spray drying the slurry at an inlet temperature of 180°C and an outlet temperature of 110°C to obtain a powder. Then, under a nitrogen flow rate of 8 L / min, the powder is placed in a high-temperature furnace and heated to 1100°C at a rate of 65°C / min, held for 1 hour to obtain a precursor material for the porous carbon-based matrix. The precursor material is then soaked in a 1 mol / L hydrochloric acid solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the porous carbon-based matrix.

[0127] The third step involves placing 20.0 kg of porous matrix material into a deposition furnace, introducing nitrogen gas into the furnace at a gas flow rate of 10 L / min, and heating the furnace to 800 °C at a heating rate of 4 °C / min. The furnace is then held at this temperature for 50 min. Next, a mixture of chlorosilane and nitrogen gas is introduced at a ratio of 15 L / min: 50 L / min, and the furnace is held at this temperature for another 20 hours to perform vapor phase deposition, thereby obtaining a nano-silicon composite porous carbon matrix.

[0128] The fourth step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 760°C under the same atmosphere. A mixture of nitrogen and acetylene is introduced into the furnace at a ratio of 5 L / min to 40 L / min, and the furnace is held at this temperature for 2 hours to obtain the material based on the nano-silicon composite porous carbon matrix.

[0129] The assembly and testing of the button cell are the same as in Example 1.

[0130] To better verify the technical effects of the present invention, the following comparative examples are provided for comparison.

[0131] Comparative Example 1

[0132] The first step is to weigh 12.0 kg of polybenzimidazole, with a molecular weight of 8.21*10. 6 The mixture was added to a sand mill along with 240 kg of N-methylpyrrolidone (NMP) and ground for 2 hours; then 15.0 kg of nano titanium dioxide was added and the mixture was ground for another 6 hours to obtain a slurry.

[0133] The second step involves spray drying the slurry at an inlet temperature of 220°C and an outlet temperature of 80°C to obtain a powder. Then, the precursor material is soaked in a 1 mol / L hydrochloric acid solution at 25°C for 24 hours. Finally, it is washed with deionized water until neutral and baked in a 100°C oven for 12 hours to obtain the matrix material.

[0134] The third step involves placing 1.0 kg of the substrate material into a deposition furnace, introducing nitrogen gas into the furnace at a flow rate of 10 L / min, and heating the furnace to 350 °C at a heating rate of 6 °C / min. The furnace is then held at this temperature for 30 min. Next, a mixture of silane and nitrogen gas is introduced at a ratio of 10 L / min: 50 L / min, and the furnace is held at this temperature for another 2 hours to perform vapor phase deposition, thereby obtaining the nano-silicon composite substrate.

[0135] The fourth step involves placing the nano-silicon composite matrix in a coating furnace under a nitrogen atmosphere. The furnace is then heated to 400°C under the same atmosphere. A mixture of nitrogen and acetylene is introduced into the furnace at a ratio of 10 L / min to 20 L / min, and the furnace is held at this temperature for 16 hours to obtain the negative electrode material of Comparative Example 1.

[0136] The assembly and testing of the button cell are the same as in Example 1.

[0137] Comparative Example 2

[0138] 1.0 kg of conventional commercial porous carbon matrix material was placed in a deposition furnace. Nitrogen gas was introduced into the deposition furnace at a gas flow rate of 10 L / min, and the temperature of the deposition furnace was increased to 350 °C at a heating rate of 6 °C / min. The temperature was held for 30 min, and then a mixture of silane and nitrogen gas was introduced at a ratio of 10 L / min: 50 L / min. The temperature was held for another 2 hours to perform vapor phase deposition and obtain nano-silicon composite porous carbon matrix.

[0139] The second step involves placing the nano-silicon composite porous carbon matrix in a coating furnace under a nitrogen atmosphere. Then, a mixture of nitrogen and acetylene is introduced into the coating furnace at a ratio of 10 L / min: 20 L / min, and the furnace is heated to 400°C and held at this temperature for 16 hours to obtain a material based on the nano-silicon composite porous carbon matrix.

[0140] The assembly and testing of the button cell are the same as in Example 1.

[0141] Table 1 shows the comparative data of the first-week coulombic efficiency of the coin half-cells prepared in Examples 1-10 and Comparative Examples 1-2.

[0142]

[0143]

[0144] Table 1

[0145] As shown in Table 1, compared with Comparative Examples 1 and 2, the button half-cell of the present invention exhibits excellent pressure resistance performance, and the coulombic efficiency in the first week does not decrease significantly before and after rolling.

[0146] A comparison with Comparative Example 1 shows that the reversible capacity and first-cycle coulombic efficiency of each embodiment are significantly higher than those of Comparative Example 1. This is because Comparative Example 1 did not undergo high-temperature treatment, but only used spray drying, thus failing to effectively achieve the thermal decomposition and carbonization reaction of polybenzimidazole, and therefore failing to effectively form a porous carbon-based matrix structure.

[0147] Furthermore, the reversible capacity of Example 7 is significantly higher than that of Examples 6 and 8, which used similar high-temperature treatments, because the proportion of nano-silicon deposited in Example 7 is higher. The proportion of nano-silicon directly affects the specific capacity (i.e., charge storage capacity per unit mass) of the anode material. Since the theoretical specific capacity of silicon is much higher than that of carbon materials, adjusting and increasing the proportion of nano-silicon can significantly improve the overall specific capacity of the composite material. In practical applications, those skilled in the art can adjust the proportions according to actual needs.

[0148] Table 2 shows the capacity retention data of the coin half-cells prepared in Examples 1-10 and Comparative Examples 1-2 after 100 cycles at a current density of 0.1C and a temperature of 25°C.

[0149]

[0150]

[0151] Table 2

[0152] As shown in Table 2, compared with Comparative Examples 1 and 2, the unrolled and rolled electrodes prepared in the embodiments of the present invention maintain a cycle retention rate of over 82% for coin half-cells under the test conditions. This is because the present application utilizes the high strength, high stiffness, and high creep resistance of high-temperature resistant polymers under high-temperature conditions, enabling the porous carbon matrix to withstand the pressure of nano-silicon anode materials during deposition, battery processing, and charge-discharge cycles, thus improving the pressure resistance of the material. Through high-temperature treatment, some of the high-temperature resistant polymers decompose to form a carbon matrix, and a silicon-carbon composite structure is formed in situ through vapor deposition, further improving the matrix strength. At the same time, the formed carbon increases the conductivity of the matrix, which can further improve the rate performance of the anode material, reduce overpotential, and ensure that the anode material has a long cycle life before and after rolling.

[0153] 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 material based on a nano-silicon composite porous carbon matrix, characterized in that, The material based on nano-silicon composite porous carbon matrix includes a core and a shell; The core comprises a porous carbon matrix and nano-silicon particles embedded in the matrix; the porous carbon matrix is ​​composed of a high-temperature resistant polymer and a carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer, wherein the mass ratio of the high-temperature resistant polymer to the carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer in the porous carbon matrix is ​​2:8-7:3; the nano-silicon particles fill the pores of the porous carbon matrix to form a nano-silicon composite porous carbon matrix core; The method for preparing the porous carbon-based matrix includes: grinding the high-temperature resistant polymer and the pore-forming agent in a solvent to obtain a slurry; subjecting the slurry to heat treatment, and by controlling the temperature and time of the heat treatment, causing part of the high-temperature resistant polymer to undergo thermal decomposition during the heat treatment to form a carbon-based conductive material, while another part of the high-temperature resistant polymer remains in an undecomposed state, thereby obtaining a precursor of the porous carbon-based matrix material; and purifying the precursor of the porous carbon-based matrix material by acid washing or alkali washing to obtain the porous carbon-based matrix. The outer shell covers the core, forming an encapsulation structure; The high-temperature resistant polymer includes polybenzimidazole and its derivatives; the outer shell is a carbon coating layer. The particle size D50 of the porous carbon matrix is ​​between 20 nm and 100 μm; the pore size of the porous carbon matrix is ​​between 0.4 nm and 200 nm; and the specific surface area of ​​the porous carbon matrix is ​​300 m². 2 / g-3000m 2 / g; the pore volume of the porous carbon-based matrix is ​​0.1 cm³. 3 / g-6.0 cm 3 / g; The material is used in the negative electrode of lithium-ion batteries.

2. The material according to claim 1, characterized in that, In the core, the mass ratio of the porous carbon matrix to the nano-silicon particles is 9:1-4:6; The mass ratio of the core to the outer shell is 99.95:0.05-90:10; The weight-average molecular weight of the polybenzimidazole and its derivatives ranges from 0.20 × 10⁻⁶. 5 ~9.98×10 6 between.

3. The material according to claim 2, characterized in that, The mass ratio of the high-temperature resistant polymer to the carbon-based conductive material generated by the thermal decomposition of the high-temperature resistant polymer is 2:8-5:

5.

4. The material according to claim 1, characterized in that, The carbon-based conductive material generated by the thermal decomposition of high-temperature resistant polymer is specifically a carbon material formed by thermal decomposition of high-temperature resistant polymer at a temperature of 650℃-1200℃ for 0.1 hours to 10 hours.

5. A method for preparing a material based on a nano-silicon composite porous carbon matrix as described in any one of claims 1-4, characterized in that, The preparation method includes: A high-temperature resistant polymer and a pore-forming agent are added to a solvent and ground to obtain a slurry; wherein the high-temperature resistant polymer includes polybenzimidazole and its derivatives; The slurry is subjected to heat treatment. By controlling the temperature and time of the heat treatment, some of the high-temperature resistant polymers undergo thermal decomposition during the heat treatment process to form carbon-based conductive materials, while the other part of the high-temperature resistant polymers remain in an undecomposed state, thus obtaining a precursor for a porous carbon-based matrix material. The precursor of the porous carbon matrix material is purified by acid washing or alkaline washing to obtain the porous carbon matrix. Under an inert atmosphere, the porous carbon matrix is ​​vapor-deposited using a silicon source gas to obtain a nano-silicon composite porous carbon matrix. The nano-silicon composite porous carbon matrix is ​​subjected to carbon coating treatment to form a carbon coating layer on the surface of the nano-silicon composite porous carbon matrix, thereby obtaining the material based on the nano-silicon composite porous carbon matrix.

6. The preparation method according to claim 5, characterized in that, The porogen includes one or more of SiO2, Al2O3, MgO, and TiO2; the average particle size of the porogen is 1 nm to 100 nm.

7. The preparation method according to claim 5, characterized in that, The heat treatment of the slurry specifically includes: spray drying the slurry to obtain a powder; then, subjecting the powder to high-temperature treatment in an inert atmosphere; wherein the inlet temperature of the spray dryer is 120℃-400℃ and the outlet temperature is 60℃-250℃; the high-temperature treatment is performed at a temperature of 650℃-1200℃ for a time of 0.1 hours-10 hours.

8. The preparation method according to claim 5, characterized in that, The vapor deposition temperature is 300℃-900℃, and the time is 1 hour-15 hours; the silicon source gas includes one or more of chlorosilanes or silane-containing hydrocarbons. The carbon coating treatment is performed at a temperature of 400℃-900℃ for 1 hour to 20 hours; the carbon source used for the carbon coating includes one or more of alkanes, alkenes, and alkynes.

9. A negative electrode sheet, characterized in that, The negative electrode sheet includes a negative electrode material based on a nano-silicon composite porous carbon matrix as described in any one of claims 1-4.

10. A lithium-ion battery comprising the negative electrode sheet as described in claim 9.

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