Silicon-carbon negative electrode material with curved graphite layer structure and preparation method thereof

Abstract

A silicon-carbon anode material with a curved graphite layer structure and its preparation method are disclosed, belonging to the field of battery anode materials. The specific solution is as follows: A silicon-carbon anode material with a curved graphite layer structure comprises a silicon phase and a carbon phase. The carbon phase is a partially graphitized carbon matrix, which includes multiple multilayer curved graphite layer units. Micropores are formed between these multiple multilayer curved graphite layer units, and an interconnected pore network is formed between the arched cavities of the multilayer curved graphite layers and the micropores. The silicon phase is distributed on the surface of the multilayer curved graphite layer units, inside the arched cavities, and within the micropores. In this invention, the arched cavities formed by the multiple multilayer curved graphite layer units are interconnected with the micropores, providing effective pores to alleviate silicon expansion while also providing an effective pathway for subsequent ion transport.

Description

Technical Field

[0001] This invention belongs to the field of battery anode materials, and particularly relates to a silicon-carbon anode material with a curved graphite layer structure and its preparation method. Background Technology

[0002] With the rapid growth of the global population and the high-speed development of society, the global demand for energy is increasing day by day. The depletion of traditional fossil fuels and other non-renewable resources, coupled with the resulting environmental problems such as global warming and air pollution, seriously restricts the progress of human society. In recent years, countries around the world have been exploring new energy sources such as solar, wind, and geothermal energy; however, these are greatly affected by real-time environmental factors in different regions. Therefore, efficient energy conversion and storage devices have attracted widespread attention, with lithium-ion batteries becoming a research hotspot in the new energy field due to their advantages such as high operating voltage, high specific energy, and no memory effect. Currently, commercially available lithium-ion battery anode materials mainly use carbon materials, which are highly stable, safe, low-cost, and widely available; however, their capacity is nearing its limit and cannot meet the high energy density demands of modern society. Silicon materials have an ultra-high theoretical specific capacity of 4200 mAh / g, approximately 10 times that of graphite anodes; the operating voltage of silicon anodes is relatively low (approximately 0.2-0.3V vs. Li / Li). + Silicon helps reduce lithium deposition and offers excellent safety; it is an abundant and low-cost material with good environmental friendliness. Considering all these advantages, silicon is an ideal choice for next-generation lithium-ion battery anode materials.

[0003] Novel silicon-carbon anode materials are lithium-ion battery anode materials obtained by uniformly depositing silicon nanoparticles within a porous carbon material framework. Compared to traditional silicon-oxygen anode materials, they significantly improve the battery's first-cycle efficiency, energy density, cycle performance, and cell expansion. Silicon-carbon composite materials, by combining silicon and carbon materials, utilize the carbon material as a buffer layer to mitigate the volume changes of silicon during lithiation and delithiation processes, while simultaneously improving the material's conductivity. In recent years, researchers have conducted extensive research and exploration in silicon-carbon anode materials, achieving remarkable results. Further development of high-performance silicon-carbon anode materials and their application in practical production are of great significance. Summary of the Invention

[0004] To address the impact of silicon expansion on battery rate performance and cycle life, this invention aims to provide a silicon-carbon anode material with a curved graphite layer structure and its preparation method. By constructing multiple high-curvature curved graphite layer units in a partially graphitized carbon matrix, these units form an arched cavity that communicates with micropores of 0.5-2 mm. This buffers the volume expansion of silicon during the lithiation process while ensuring good electron / ion transport pathways and mechanical stability, thereby improving the specific capacity, rate performance, and cycle life of the silicon-carbon anode material.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A silicon-carbon anode material with a curved graphite layer structure, the silicon-carbon anode material comprising a silicon phase and a carbon phase, the carbon phase being a partially graphitized carbon matrix, the partially graphitized carbon matrix comprising multiple multilayer curved graphite layer units, micropores being formed between the partially multilayer curved graphite layer units, and an interconnected pore network being formed between the arched cavities of the multilayer curved graphite layer units and the micropores, the silicon phase being distributed on the surface of the multilayer curved graphite layer units, inside the arched cavities, and inside the micropores.

[0007] The surface density of non-six-membered ring topological defects in the multilayer curved graphite unit is 0.2-2.0%, and the volume density of the micropores is 0.2-1 cm³. 3 ·g -1 The stripe length L of the multilayer curved graphite layer unit a The value is 1.5-12nm, the radius of curvature r is 2-6nm, and L satisfies a The value of / r is 2-6; the diameter of the micropore is 0.5-2.0 nm.

[0008] The multilayer curved graphite unit is obtained through one or more of the following methods: metal ion modulation, heteroatom doping, irradiation, and thermal excitation.

[0009] The metal ions used in the metal ion control method correspond to metal elements including iron, nickel, cobalt, manganese, copper, zinc, aluminum, vanadium, titanium, tungsten, and molybdenum, or a mixture of one or more of these elements in any proportion; the doping elements used in the heteroatom doping method include nitrogen, boron, phosphorus, sulfur, oxygen, fluorine, chlorine, bromine, and iodine, or a mixture of these elements; the irradiation method is one or a combination of electron irradiation and ion irradiation; and the thermal excitation method is lightning Joule heating.

[0010] The silicon phase is nano-silicon with an average particle size of 0.5-2nm and a mass fraction of 20-70wt% of the total mass of the silicon-carbon anode material.

[0011] A method for preparing a silicon-carbon anode material with a curved graphite layer structure includes the following steps:

[0012] Step 1: Disperse the metal salt, dispersant, and catalyst in deionized water to obtain a dispersion. Step 2: Add phenolic substances and aldehyde solutions to the dispersion, and carry out a dissolution-condensation reaction under alkaline catalysis. After vacuum drying, obtain a precursor resin material. Then, subject the precursor resin material to preliminary heat treatment, activation treatment, and carbonization treatment, and wash with concentrated nitric acid to remove metal elements until neutral. Step 3: Deposit silicon nanoparticles into a carbon matrix using CVD vapor deposition to obtain a silicon-carbon material with a multilayered curved graphite layer structure. Then, anneal in an inert atmosphere to stabilize the material's structure and interface.

[0013] In step one, the metal salt comprises one or more of the following metal elements in any proportion: iron, nickel, cobalt, manganese, copper, zinc, aluminum, vanadium, titanium, tungsten, and molybdenum; the metal salt comprises one or more of the following metal nitrates and chlorides in any proportion; the mass fraction of the introduced metal ions is 0.5-3 wt% of the sum of the masses of the phenolic substances and aldehyde solutions; the dispersant comprises one or more of the following chitosan, polyethyleneimine, and polyvinyl alcohol in any proportion; its mass fraction is 1-5 wt% of the sum of the masses of the phenolic substances and aldehyde solutions; the catalyst comprises one or more of the following acetic acid, acetic acid, and oxalic acid in any proportion; its mass fraction is 1-3 wt% of the sum of the masses of the phenolic substances and aldehyde solutions.

[0014] In step two, the phenolic substances include any mixture of one or more of phenol, catechol, resorcinol, aminophenol, and hydroquinone; the aldehyde solution includes any mixture of one or more of formaldehyde, acetaldehyde, and glutaraldehyde, with a molar ratio of phenolic substances to aldehyde solution of 1:1 to 1:5; the alkaline catalyst used for alkaline catalysis includes any mixture of one or more of sodium hydroxide, potassium hydroxide, ammonia, and sodium carbonate, with a molar ratio of alkaline catalyst to phenolic substances of 1:5 to 1:20.

[0015] In step two, the preliminary heat treatment temperature is 300-600℃, the time is 2-6 h, the heating rate is 1-10℃ / min, and the atmosphere is one of argon, a hydrogen-argon mixture, or nitrogen; the carbonization treatment temperature is 600-900℃, the time is 2-6 h, the heating rate is 2-10℃ / min, and the atmosphere is one of argon, a hydrogen-argon mixture, or nitrogen; the volume ratio of hydrogen to argon in the hydrogen-argon mixture is 5:95; the activation treatment includes physical activation and / or chemical activation, the physical activation method is activation in an oxidizing gas at 300-700℃ for 1-4 h, and the chemical activation method is activation by immersion in KOH or NaOH chemical reagents for 4-24 h; the mass fraction of concentrated nitric acid is 60-80 wt%.

[0016] In step three, the gas phase of the CVD is SiH4 or SiCl4 / H2, wherein the volume ratio of SiCl4 to H2 in SiCl4 / H2 is 0.01-1; the CVD treatment temperature is 550-900℃ and the time is 5-30 min; the annealing treatment temperature is 700-1000℃ and the time is 0.5-2 h.

[0017] The electrode using the silicon-carbon anode material with the curved graphite layer structure is applied to a secondary battery, wherein the secondary battery is a lithium-ion battery.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention provides a silicon-carbon anode material with a curved graphite layer structure. By constructing high-curvature multilayer curved graphite units within a carbon matrix, these units are arranged in an arched shape, forming an arched cavity. When silicon undergoes volume expansion during lithiation, the multilayer curved graphite layers can elastically bend, dispersing and transferring localized volume expansion stress along the arched cavity and adjacent multilayer curved graphite layers. This avoids through-cracks at the silicon-carbon interface and within the carbon skeleton, significantly mitigating silicon pulverization and overall electrode structural damage.

[0020] This invention provides a silicon-carbon anode material with a curved graphite layer structure. The arched cavity formed by multiple multilayer curved graphite layer units is connected to the micropores, which not only provides an effective cavity to alleviate silicon expansion, but also provides an effective pathway for subsequent ion transport.

[0021] Thanks to the above structural design, the silicon-carbon anode material prepared by this invention can still maintain good reversible specific capacity and coulombic efficiency under high silicon loading conditions, and maintain excellent rate performance and long-cycle stability at medium and high rates. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the material structure of Embodiment 1 of the present invention;

[0023] Figure 2 These are the GCD curves of Embodiment 1 and Comparative Example 1 of the present invention;

[0024] Figure 3 These are the rate performance curves of Embodiment 1 and Comparative Example 1 of the present invention;

[0025] Figure 4 These are the long-cycle performance curves of Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1:

[0028] A method for preparing a silicon-carbon anode material with a curved graphite layer structure, comprising the following steps:

[0029] Step 1: Add 0.673g Fe(NO3)3·9H2O, 0.45g chitosan and 0.6mL glacial acetic acid to 30mL deionized water in sequence, stir magnetically and sonicate to obtain a uniform brownish-yellow solution;

[0030] Step 2: Add 1.88g of phenol and 3mL of formaldehyde solution to the above solution, and add 2mL of 1M NaOH solution as an alkaline catalyst to maintain the pH of the system at 9-11. Stir the reaction at 70-80℃ for 4 hours, then raise the temperature to 120℃ and hold for 8 hours to complete the nucleation of phenolic resin. Obtain the sample by centrifugation, wash the sample with 60℃ deionized water until the sample is neutral, and vacuum dry at 100℃ to obtain the carbonized precursor resin material. After grinding the carbonized precursor resin material evenly, pre-heat treat the powder at 400℃ for 2 hours under an argon atmosphere, with a heating rate of 5℃ / min. Place the obtained material in 2M KOH solution, stir for 12 hours, separate the solid sample, dry it in an 80℃ vacuum oven for 12 hours, and then carbonize the obtained sample at 700℃ for 2 hours under an argon atmosphere, with a heating rate of 5℃ / min. After obtaining the sample, it was placed in concentrated nitric acid (68 wt%) at 70℃ and stirred for 12 h to dissolve and remove the metal and its compounds. The solid was collected by centrifugation, washed repeatedly with deionized water until pH≈7, and dried under vacuum at 60℃ for 24 h to obtain a carbon matrix with multiple curved graphite layers, denoted as FPFC.

[0031] Step 3: 1 gram of FPFC was placed in a rotary tube furnace, followed by three vacuum treatments and refilling with argon. A silane mixture (Vsilane / Vargon = 5 / 95; flow rate: 100 sccm) was injected into the rotary tube furnace, and heating began when the temperature reached 430°C. After 90 minutes of chemical vapor deposition, the silane supply was stopped, and the temperature was raised to 600°C. At this point, acetylene gas (flow rate: 30 sccm) was introduced into the rotary tube furnace, while argon was used as the carrier gas (flow rate: 120 sccm), and carbon film deposition was completed for 11 minutes. Subsequently, the silicon source was turned off, and the temperature was raised to 800°C and held for 30 minutes under an argon atmosphere for annealing. After cooling, a silicon-carbon composite material with a multilayer curved graphite layer unit structure was obtained, denoted as FPFC-Si. The system was allowed to cool naturally to room temperature while maintaining a continuous argon supply.

[0032] The process for assembling lithium-ion batteries is as follows: 94% negative electrode active material FPFC-Si + 2% CMC + 2% SB + 2% Super P, the separator is PP separator, and the electrolyte is lithium battery electrolyte (KLD-LP38) (1.0M LiPF6 in FEC:EC:DEC=10:45:45wt%).

[0033] Example 2

[0034] A method for preparing a silicon-carbon anode material with a curved graphite layer structure, comprising the following steps:

[0035] Step 1: Add 0.485g Co(NO3)3·6H2O, 0.45g chitosan and 0.6mL glacial acetic acid to 30mL deionized water in sequence, stir magnetically and sonicate to obtain a uniform purple-red solution;

[0036] Step 2: Add 1.882g of phenol and 3mL of formaldehyde solution to the above solution, and add 2mL of 1M NaOH solution as an alkaline catalyst to maintain the pH of the system at 9-11. Stir the reaction at 70-80℃ for 4 hours, then raise the temperature to 120℃ and hold for 8 hours to complete the nucleation of phenolic resin. Obtain the sample by centrifugation, wash the sample with 60℃ deionized water until the sample is neutral, and vacuum dry at 100℃ to obtain the carbonized precursor resin material. After grinding the carbonized precursor resin material evenly, pre-heat treat the powder at 400℃ for 2 hours under an argon atmosphere, with a heating rate of 5℃ / min. Place the obtained material in 2M KOH solution, stir for 12 hours, separate the solid sample, dry it in an 80℃ vacuum oven for 12 hours, and then carbonize the obtained sample at 700℃ for 2 hours under an argon atmosphere, with a heating rate of 5℃ / min. After obtaining the sample, it was placed in concentrated nitric acid (68 wt%) at 70 °C and stirred for 12 h to dissolve and remove the metal and its compounds. The solid was collected by centrifugation, washed repeatedly with deionized water until pH≈7, and dried under vacuum at 60 °C for 24 h to obtain a carbon matrix with multiple curved graphite layers, denoted as CPFC.

[0037] Step 3: 1 gram of CPFC was placed in a rotary tube furnace, followed by three vacuum treatments and refilling with argon. A silane mixture (Vsilane / Vargon = 5 / 95; flow rate: 100 sccm) was injected into the rotary tube furnace, and heating began when the temperature reached 430°C. After 90 minutes of chemical vapor deposition, the silane supply was stopped, and the temperature was raised to 600°C. At this point, acetylene gas (flow rate: 30 sccm) was introduced into the rotary tube furnace, while argon was used as the carrier gas (flow rate: 120 sccm), and carbon film deposition was completed for 11 minutes. Subsequently, the silicon source was turned off, and the temperature was raised to 800°C and held for 30 minutes under an argon atmosphere for annealing. After cooling, a silicon-carbon composite material with a multilayer curved graphite layer unit structure was obtained, denoted as CPFC-Si. The system was allowed to cool naturally to room temperature while maintaining a continuous argon supply.

[0038] Example 3

[0039] A method for preparing a silicon-carbon anode material with a curved graphite layer structure, comprising the following steps:

[0040] Step 1: Add 0.486g Ni(NO3)3·6H2O, 0.45g chitosan and 0.6mL glacial acetic acid to 30mL deionized water in sequence, stir magnetically and sonicate to obtain a uniform light green solution;

[0041] Step 2: Add 1.882 g of phenol and 3 mL of formaldehyde solution to the above solution, and add 2 mL of 1M NaOH solution as an alkaline catalyst to maintain the pH of the system at 9-11. Stir the reaction at 70-80℃ for 4 h, then raise the temperature to 120℃ and hold for 8 h to complete the nucleation of phenolic resin. Obtain the sample by centrifugation, wash the sample with 60℃ deionized water until the sample is neutral, and vacuum dry at 100℃ to obtain the carbonized precursor resin material. After grinding the carbonized precursor resin material evenly, pre-heat treat the powder at 400℃ for 2 h under an argon atmosphere, with a heating rate of 5℃ / min. Place the obtained material in 2M KOH solution, stir for 12 h, separate the solid sample, dry it in an 80℃ vacuum oven for 12 h, and then carbonize the obtained sample at 700℃ for 2 h under an argon atmosphere, with a heating rate of 5℃ / min. After obtaining the sample, it was placed in concentrated nitric acid (68 wt%) at 70 °C and stirred for 12 h to dissolve and remove the metal and its compounds. The solid was collected by centrifugation, washed repeatedly with deionized water until pH≈7, and dried under vacuum at 60 °C for 24 h to obtain a carbon matrix with multiple curved graphite layers, denoted as NPFC.

[0042] Step 3: 1 gram of NPFC was placed in a rotary tube furnace, followed by three vacuum treatments and refilling with argon. A silane mixture (Vsilane / Vargon = 5 / 95; flow rate: 100 sccm) was injected into the rotary tube furnace, and heating began when the temperature reached 430°C. After 90 minutes of chemical vapor deposition, the silane supply was stopped, and the temperature was raised to 600°C. At this point, acetylene gas (flow rate: 30 sccm) was introduced into the rotary tube furnace, while argon was used as the carrier gas (flow rate: 120 sccm), and carbon film deposition was completed for 11 minutes. Subsequently, the silicon source was turned off, and the temperature was raised to 800°C and held for 30 minutes under an argon atmosphere for annealing. After cooling, a silicon-carbon composite material with a multilayer curved graphite layer unit structure was obtained, denoted as NPFC-Si. The system was allowed to cool naturally to room temperature while maintaining a continuous argon supply.

[0043] Comparative Example 1

[0044] A method for preparing a silicon-carbon composite material includes the following steps:

[0045] Step 1: Mix 1.882g of phenol and 3mL of formaldehyde solution evenly, add 2mL of 1M NaOH solution as an alkaline catalyst, maintain the pH of the system at 9-11, stir the reaction at 70-80℃ for 4 h, then raise the temperature to 120℃ and hold for 8 h to complete the nucleation of phenolic resin. Obtain the sample by centrifugation, wash the sample with 60℃ deionized water until the sample is neutral, and vacuum dry at 100℃ to obtain the carbonized precursor resin material. After grinding the carbonized precursor resin material evenly, pre-heat treat the powder at 400℃ for 2 h under an argon atmosphere, with a heating rate of 5℃ / min. Place the obtained material in 2M KOH solution, stir for 12 h, separate the solid sample, dry it in an 80℃ vacuum oven for 12 h, and then carbonize the obtained sample at 700℃ for 2 h under an argon atmosphere, with a heating rate of 5℃ / min. The carbon matrix was obtained by repeatedly washing with deionized water until pH≈7 and then vacuum drying at 60℃ for 24h, and denoted as PFC.

[0046] Step 2: 1 gram of PFC was placed in a rotary tube furnace, followed by three vacuum treatments and refilling with argon. A silane mixture (Vsilane / Vargon = 5 / 95; flow rate: 100 sccm) was injected into the rotary tube furnace, and heating began when the temperature reached 430°C. After 90 minutes of chemical vapor deposition, the silane supply was stopped, and the temperature was raised to 600°C. At this point, acetylene gas (flow rate: 30 sccm) was introduced into the rotary tube furnace, while argon was used as the carrier gas (flow rate: 120 sccm), completing 11 minutes of carbon film deposition. Subsequently, the silicon source was turned off, and the temperature was raised to 800°C and held for 30 minutes under an argon atmosphere for annealing. After cooling, a silicon-carbon composite material, denoted as PFC-Si, was obtained. The system was allowed to cool naturally to room temperature while maintaining a continuous argon supply.

[0047] The silicon-carbon anodes assembled from the FPFC-Si and PFC-Si materials prepared in Example 1 and Comparative Example 1, respectively, were used in lithium-ion batteries. The charge-discharge curves of the batteries at 0.1C are shown below. Figure 2 As shown, FPFC-Si exhibits a lithium storage capacity of 1626 mAh / g, while PFC-Si has a lithium storage capacity of only 1469 mAh / g.

[0048] The silicon-carbon anodes assembled from the FPFC-Si and PFC-Si materials prepared in Example 1 and Comparative Example 1, respectively, were used in lithium-ion batteries. The charge-discharge curves of the batteries at different rates are shown below. Figure 3As shown, the multilayered curved graphite layers increase the mechanical stability of the material, thereby improving the rate performance of FPFC-Si material. The lithium-ion battery assembled with FPFC-Si exhibits a lithium storage capacity of 525 mAh / g at a high current density of 3C, while the lithium-ion battery assembled with PFC-Si has a lithium storage capacity of only 426 mAh / g.

[0049] The silicon-carbon anodes assembled from the FPFC-Si and PFC-Si materials prepared in Example 1 and Comparative Example 1, respectively, are used in lithium-ion batteries. The batteries exhibit long-cycle performance at 1C as follows: Figure 4 As shown, the lithium-ion battery assembled with FPFC-Si retains 86% of its capacity after 100 cycles, while the lithium-ion battery assembled with PFC-Si retains only 73% of its capacity after 100 cycles.

[0050] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A silicon-carbon anode material with a curved graphite layer structure, characterized in that: The silicon-carbon anode material comprises a silicon phase and a carbon phase. The carbon phase is a partially graphitized carbon matrix, which includes multiple multilayer curved graphite layer units. Micropores are formed between the multilayer curved graphite layer units. The arched cavities of the multilayer curved graphite layer units and the micropores form a connected pore network. The silicon phase is distributed on the surface of the multilayer curved graphite layer units, inside the arched cavities, and inside the micropores.

2. The silicon-carbon anode material with a curved graphite layer structure according to claim 1, characterized in that: The surface density of non-six-membered ring topological defects in the multilayer curved graphite unit is 0.2-2.0%, and the volume density of the micropores is 0.2-1 cm³. 3 ·g -1 The stripe length L of the multilayer curved graphite layer unit a The value is 1.5-12nm, the radius of curvature r is 2-6nm, and L satisfies a The value of / r is 2-6; the diameter of the micropore is 0.5-2.0 nm.

3. The silicon-carbon anode material with a curved graphite layer structure according to claim 1, characterized in that: The multilayer curved graphite unit is obtained through one or more of the following methods: metal ion modulation, heteroatom doping, irradiation, and thermal excitation.

4. A silicon-carbon anode material with a curved graphite layer structure according to claim 3, characterized in that: The metal ions used in the metal ion control method correspond to metal elements including iron, nickel, cobalt, manganese, copper, zinc, aluminum, vanadium, titanium, tungsten, and molybdenum, or a mixture of one or more of these elements in any proportion; the doping elements used in the heteroatom doping method include nitrogen, boron, phosphorus, sulfur, oxygen, fluorine, chlorine, bromine, and iodine, or a mixture of these elements; the irradiation method is one or a combination of electron irradiation and ion irradiation; and the thermal excitation method is lightning Joule heating.

5. A silicon-carbon anode material with a curved graphite layer structure according to claim 1, characterized in that: The silicon phase is nano-silicon with an average particle size of 0.5-2nm and a mass fraction of 20-70wt% of the total mass of the silicon-carbon anode material.

6. A method for preparing a silicon-carbon anode material with a curved graphite layer structure, characterized in that, Includes the following steps: Step 1: Disperse the metal salt, dispersant, and catalyst in deionized water to obtain a dispersion; Step 2: Add phenolic substances and aldehyde solutions to the dispersion, carry out a dissolution-condensation reaction under alkaline catalysis, and vacuum dry the product to obtain a precursor resin material. Subsequently, the precursor resin material undergoes preliminary heat treatment, activation treatment, and carbonization treatment, and is washed with concentrated nitric acid to remove metal elements until neutral. Step 3: Silicon nanoparticles are deposited into a carbon matrix using CVD vapor deposition to obtain a silicon-carbon material with a multilayer curved graphite layer structure. The material is then annealed in an inert atmosphere to stabilize its structure and interface.

7. The preparation method according to claim 6, characterized in that: In step one, the metal salt comprises one or more of the following metal elements in any proportion: iron, nickel, cobalt, manganese, copper, zinc, aluminum, vanadium, titanium, tungsten, and molybdenum; the metal salt comprises one or more of the following metal nitrates and chlorides in any proportion, wherein the mass fraction of the metal ions is 0.5-3 wt% of the sum of the mass of the phenolic and aldehyde substances; the dispersant comprises one or more of the following chitosan, polyethyleneimine, and polyvinyl alcohol in any proportion, wherein its mass fraction is 1-5 wt% of the sum of the mass of the phenolic and aldehyde substances; the catalyst comprises one or more of the following acetic acid, acetic acid, and oxalic acid in any proportion, wherein its mass fraction is 1-3 wt% of the sum of the mass of the phenolic and aldehyde substances.

8. The preparation method according to claim 6, characterized in that: In step two, the phenolic substances include any mixture of one or more of phenol, catechol, resorcinol, aminophenol, and hydroquinone; the aldehyde solution includes any mixture of one or more of formaldehyde, acetaldehyde, and glutaraldehyde, with a molar ratio of phenolic substances to aldehyde solution of 1:1 to 1:5; the alkaline catalyst used for alkaline catalysis includes any mixture of one or more of sodium hydroxide, potassium hydroxide, ammonia, and sodium carbonate, with a molar ratio of alkaline catalyst to phenolic substances of 1:5 to 1:

20.

9. The preparation method according to claim 6, characterized in that: In step two, the preliminary heat treatment temperature is 300-600℃, the time is 2-6 h, the heating rate is 1-10℃ / min, and the atmosphere is one of argon, a hydrogen-argon mixture, or nitrogen; the carbonization treatment temperature is 600-900℃, the time is 2-6 h, the heating rate is 2-10℃ / min, and the atmosphere is one of argon, a hydrogen-argon mixture, or nitrogen; the volume ratio of hydrogen to argon in the hydrogen-argon mixture is 5:95; the activation treatment includes physical activation and / or chemical activation, the physical activation method is activation in an oxidizing gas at 300-700℃ for 1-4 h, and the chemical activation method is activation by immersion in KOH or NaOH chemical reagents for 4-24 h; the mass fraction of concentrated nitric acid is 60-80 wt%.

10. The preparation method according to claim 6, characterized in that: In step three, the gas phase of the CVD is SiH4 or SiCl4 / H2, wherein the volume ratio of SiCl4 to H2 in SiCl4 / H2 is 0.01-1; the CVD treatment temperature is 550-900℃ and the time is 5-30 min; the annealing treatment temperature is 700-1000℃ and the time is 0.5-2 h.

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