A silicon-carbon anode material, its preparation method and application

Abstract

This invention discloses a silicon-carbon anode material, its preparation method, and its applications. The silicon-carbon anode material provided by this invention includes a porous carbon matrix and a silicon material. The porous carbon matrix has a core-shell structure, with the core having micropores and the outer shell having mesopores. The ratio of the average diameter D1 of the core to the average particle size D2 of the silicon-carbon anode material, D1 / D2, is 0.2-0.9. The silicon material is distributed in the mesopores and micropores of the carbon matrix. This core-shell structure of the porous carbon matrix provides more and more stable diffusion channels for lithium ions to migrate between material particles. Simultaneously, the introduction of nano-silicon material can significantly improve the conductivity of the electrode material and alleviate the volume expansion problem of nano-silicon material, thereby enhancing electrochemical reactivity.

Description

Technical Field

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

[0002] With the rapid development of electric vehicles and portable electronic devices, the market has placed higher demands on the energy density and cycle life of lithium-ion batteries. Silicon, due to its extremely high theoretical specific capacity (approximately 4200 mAh / g), is considered the most promising choice for next-generation anode materials. However, silicon undergoes significant volume expansion (>300%) during charging and discharging, leading to electrode material structure pulverization, active material shedding, and the formation of an unstable solid electrolyte interphase (SEI) film through continuous reaction with the electrolyte. These inherent problems make pure silicon anodes difficult to apply practically. To address this challenge, silicon-carbon composites have become a mainstream research direction, aiming to suppress silicon volume expansion through the buffering effect of the carbon matrix. However, traditional silicon-carbon composites typically employ simple physical mixing or disordered composite methods, resulting in less than ideal silicon distribution and volume expansion control. How to construct an effective spatial structure in composite materials to actively regulate silicon volume expansion while maintaining excellent conductivity and structural integrity is a key technical challenge that urgently needs to be overcome in this field.

[0003] Currently, the main methods for preparing silicon-carbon anodes include: ① mechanically mixing or ball milling nanoparticles with conductive carbon (such as graphite, carbon black, and graphene); ② loading silicon onto the pores or surface of porous carbon materials (such as carbon nanotubes and porous carbon spheres) using template methods or chemical vapor deposition methods; ③ designing core-shell structures, such as silicon as the core and carbon as the shell, using the carbon layer to constrain the expansion of silicon.

[0004] The above-mentioned preparation methods have the following shortcomings: ① Mechanically mixed composites are unable to effectively suppress the huge volume expansion of the silicon phase, and the silicon-carbon interface is loosely bonded, resulting in poor electrochemical stability; ② The pore size distribution of conventional porous carbon matrices is disordered, making it impossible to directionally control the deposition behavior of silicon, leading to localized concentration of expansion stress and low utilization of structural buffer space; ③ In simple core-shell structures, the carbon shell is prone to brittle fracture under cyclic stress, losing its protective function for the active material; ④ Existing synthesis processes often involve complex templates or harsh conditions, resulting in high costs and difficulty in scaling up production. These problems collectively restrict the cycle life, rate performance, and volumetric energy density of silicon-carbon anodes in practical applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and to provide a silicon-carbon anode material, its preparation method, and its application.

[0006] The technical problem solved by this invention is achieved by the following technical solution.

[0007] This invention provides a silicon-carbon anode material, comprising a porous carbon matrix and a silicon material. The porous carbon matrix has a core-shell structure, with the core having micropores and the shell having mesopores. The ratio of the average diameter D1 of the core to the average particle size D2 of the silicon-carbon anode material, D1 / D2, is 0.2-0.9. The silicon material is distributed in the mesopores and micropores of the carbon matrix.

[0008] The present invention also provides a method for preparing the silicon-carbon anode material described above, comprising the following steps: coating a coating layer containing a template agent and resin on the surface of a small-particle-size resin curing material to obtain a core-shell structured curing material; carbonizing the core-shell structured curing material and removing the template; then activating it to obtain a porous carbon matrix; and performing a vapor deposition silicon treatment on the porous carbon matrix to obtain the silicon-carbon anode material.

[0009] The present invention also provides an application of the above-mentioned silicon-carbon anode material in the preparation of battery anodes.

[0010] The present invention has the following beneficial effects: The silicon-carbon anode material provided by this invention includes a porous carbon matrix and silicon material. The porous carbon matrix has a core-shell structure, with the core having micropores and the outer shell having mesopores. The micropores have higher silicon infiltration adsorption activity. Silicon is first dispersed in the internal micropore region and then forms silicon nanowires in the external mesopore region. The external silicon nanowires provide a good lithium-ion diffusion channel for lithium ions, improving the rate performance of silicon-carbon. Furthermore, due to the larger pore size, a certain buffer zone is provided during silicon lithium intercalation expansion. The internal micropore region is buffered by the external mesopore carbon region during lithium intercalation. Compared with pure microporous carbon, it reduces the possibility of the entire particle breaking due to silicon expansion in the wedge-shaped channels. Therefore, the micro-mesopore partitioning of the porous carbon matrix provided by this invention not only takes into account the rate performance but also reduces the problems of particle breakage and significant capacity drop caused by silicon-carbon particle expansion. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 The image shows a SEM image of the cured resin with a Dv50 of 5 μm prepared in Example 1.

[0013] Figure 2 The cross-sectional SEM image of the silicon-carbon anode material particles prepared in Example 1; Figure 3 This is a TEM image of the ordered mesoporous portion of the porous carbon particles prepared in Example 1.

[0014] Figure 4 TEM image of the microporous portion of the porous carbon particles prepared in Example 1; Figure 5 The isothermal adsorption curve of the activated material prepared in Example 1; Figure 6 The diagram shows the BJH mesopore distribution of the activated material prepared in Example 1. Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0015] The following is a detailed description of a silicon-carbon anode material, its preparation method, and its application provided by embodiments of the present invention.

[0016] In a first aspect, the present invention provides a silicon-carbon anode material, comprising a porous carbon matrix and a silicon material, wherein the porous carbon matrix has a core-shell structure, and the core has micropores and the shell has mesopores. The ratio of the average diameter D1 of the core to the average particle size D2 of the silicon-carbon anode material, D1 / D2, is 0.2-0.9. The silicon material is distributed in the mesopores and micropores of the carbon matrix.

[0017] To overcome the problems of poor cycle stability and easy structural damage caused by the volume expansion of silicon in existing silicon-carbon anode materials, this invention provides a silicon-carbon anode material in which the pore size of the porous carbon decreases from the outside to the inside. The dense inner carbon layer can tightly constrain the irregular expansion of silicon and isolate silicon from direct contact with the electrolyte, preventing silicon particle breakage and avoiding the formation of an unstable SEI film from the source. The large-pore outer carbon layer can efficiently bear the expansion stress and provide directional buffer space, while improving electrolyte wettability, widening the lithium-ion transport channel, and inducing the formation of a stable and slightly stretchable SEI film, reducing lithium and electrolyte losses. This gradient structure can also maintain a continuous three-dimensional conductive network of carbon phase, taking into account the rapid transport of electrons and lithium ions, ensuring high rate performance, while balancing the tap density and specific capacity of composite particles, improving volumetric energy density, making the particles more resistant to rolling and better bonding with binders, and adapting to industrial electrode processing. Ultimately, this achieves a comprehensive improvement in the structural stability, cycle life, rate performance, and industrial adaptability of the silicon-carbon anode.

[0018] In some alternative embodiments, the composite material further includes a coating layer covering the surface of the composite material formed from the porous carbon matrix and the silicon material, preferably having a thickness of 8-12 nm.

[0019] In some optional embodiments, the silicon content in the silicon-carbon anode material is 5-90%, preferably 30-60%.

[0020] In some alternative embodiments, the silicon-carbon anode material satisfies one of the following characteristics: a. The average diameter Dv50 of the core is 1-10 μm, preferably 3-6 μm; the radial distance is 0.5-2.0, preferably 0.6-1.0; b. The average particle size Dv50 of the silicon-carbon anode material is 3-12, preferably 5-10 μm; the diameter spacing is 0.5-2.0, preferably 0.6-1.2. c. The pore volume of the porous carbon matrix is ​​0.4-1.5 cm³. 3 / g, preferably 0.6-1.2cm 3 / g; d. The size of the mesoporous channels in the shell of the porous carbon matrix is ​​2-6 nm, and the mesoporous channels are ordered or disordered.

[0021] Secondly, the present invention provides a method for preparing the silicon-carbon anode material described above, comprising the following steps: coating a coating layer containing a template agent and resin onto the surface of a small-particle-size resin curing material to obtain a core-shell structured curing material; carbonizing the core-shell structured curing material and removing the template; then activating it to obtain a porous carbon matrix; and performing vapor deposition silicon treatment on the porous carbon matrix to obtain the silicon-carbon anode material.

[0022] In some optional embodiments, the method for preparing silicon-carbon anode materials includes the following steps: Step 1: Disperse the small-particle-size resin curing material in ethanol to obtain a resin curing material dispersion, wherein the mass of ethanol is 3-10 times the mass of the resin curing material; then add resin, hydrochloric acid and template agent to the resin curing material dispersion, and stir at 40°C for 1 h until the solution is uniformly dispersed to obtain a mixed solution. Step 2: Add the mixed solution obtained in Step 1 to heat transfer oil with a mass of 1-5 times that of the mixed solution, keep it at 40℃-80℃ for 1-10 h, and after the ethanol has completely evaporated, raise the temperature to 100-180℃ and keep it at 1-20 h, and obtain the core-shell structured solidified material by solid-liquid separation. Step 3: Calcine the core-shell structure solidified material obtained in Step 2 to remove the soft template agent, or immerse the core-shell structure solidified material in an alkaline solution or HF solution to remove the hard template agent, and then wash it with water until the ash content is less than 0.2% to obtain the carbonized material; Step 4: Activate the carbonized material obtained in Step 3 to obtain a porous carbon matrix, wherein the activation method is one or more of alkali activation, water activation, and carbon dioxide activation; Step 5: Place the porous carbon matrix obtained in Step 4 in a fluidized bed, heat it to 430°C, and purge it with 25% SiH4-N2 for 1-30 hours; then switch to N2 purging for 1 hour, then raise the temperature to 580°C, purge it with 25% C2H2-N2 for 1-30 hours, cool it down and switch to N2 to obtain a composite material in which silicon material is deposited in the pores of the porous carbon matrix.

[0023] In some optional embodiments, the small-particle-size resin curing material is obtained by spray drying a phenolic resin solution, which is prepared by mixing aldehyde raw materials, phenolic raw materials, catalyst and water; And / or, the preparation temperature of the phenolic resin is 40-100℃; And / or, the aldehyde raw materials include at least one of formaldehyde, acetaldehyde and furfural; And / or, the phenolic raw materials include at least one of phenol and resorcinol; And / or, the aldehyde raw material accounts for 60%-130% of the mass of the phenolic raw material; And / or, the catalyst includes at least one of an acidic catalyst and a basic catalyst; And / or, the catalyst accounts for 1%-5% of the mass of the phenols; And / or, the acidic catalyst includes at least one of hydrochloric acid, sulfuric acid, and oxalic acid; And / or, the alkaline catalyst includes at least one of sodium hydroxide, calcium hydroxide, and ammonia water.

[0024] In some alternative embodiments, the method further includes: depositing a coating layer on the surface of the composite material using a vapor deposition method, preferably using carbon nanotubes or conductive paste for secondary coating.

[0025] In some optional embodiments, the template agent includes one or more of a soft template agent and a hard template agent, wherein the soft template agent is selected from one or more of poloxamer F127, poloxamer P123, and CTAB, and the hard template agent is selected from one or more of tetraethyl orthosilicate, aluminum isopropoxide, silica sol, aluminum sol, and sodium silicate.

[0026] Thirdly, the present invention provides an application of the above-mentioned silicon-carbon anode material in the preparation of battery anodes.

[0027] The present invention will now be described in some optional embodiments with reference to examples.

[0028] Example 1, Soft Template Method This embodiment provides a silicon-carbon anode material, the preparation process of which is as follows: Step 1. Prepare small-particle-size resin curing material with an average particle size Dv50 = 5 μm: ① Melt 100g of phenol at 40℃, then add 2g of sodium hydroxide and 150g of 37% formaldehyde in sequence, and heat to 70℃ and keep warm for 2h to obtain solution A. ② Add 2g of commercially available PVA to 400g of water and disperse to obtain solution B. ③ Add 250g of solution A to solution B and heat to 95℃, add 5g of hexamethylenetetramine, keep warm for 3h, filter and dry to obtain resin curing material with a small particle size of 5μm. Step 2. Preparation: Add 5g of the above small particle size resin curing material to 50g of ethanol, then add 5g of the above solution A and 5g of F127 in sequence, and stir at 40℃ for 2h to obtain solution C; Step 3. Mesoporous carbon precursor curing and coating: Add 50g of the above solution to 300g of heat transfer oil, keep it at 50℃ for 3h, and after the ethanol has completely evaporated, raise the temperature to 120℃ and keep it at 4h; separate the solid and liquid, wash to obtain the core-shell structured cured material with a spherical particle size of Dv50=8μm. Step 4. Carbonization: The core-shell structure solidified material obtained above is carbonized at high temperature. The carbonization conditions are 800℃ and 3h, to obtain carbonized material. Step 5. Activation: The above carbonized material is activated with steam and kept at 820°C for 3 hours to obtain a microporous carbon matrix; Step 6. Silicon is deposited on the microporous carbon matrix using chemical vapor deposition, and then a carbon coating layer is coated using chemical vapor deposition to prepare the silicon-carbon anode material.

[0029] Example 2, reducing the weight of the coating layer Except in step 2, the mass of the 5μm curing material is changed from 5g to 8g; Everything else is the same as in Example 1.

[0030] Example 3: Improving the quality of the coating layer Except in step 2, the mass of the 5μm curing material is changed from 5g to 3g; Everything else is the same as in Example 1.

[0031] Example 4: Soft template changed to hard template In step 2, replace 5g F127 with 8g TEOS and 5g 0.2M HCl. After step 4, the carbonized material is subjected to 10% HF for 24 hours and washed with water three times. The above steps are repeated multiple times until the ash content is as low as 0.1%.

[0032] Everything else is the same as in Example 1.

[0033] Example 5 Step 1. Prepare small-particle-size resin curing material with Dv50=3μm: ① Melt 100g of phenol at 40℃, then add 2g of sodium hydroxide and 150g of 37% formaldehyde in sequence, and heat to 70℃ and keep warm for 2h to obtain solution A. ② Add 2g of commercially available PVA to 400g of water and disperse to obtain solution B. ③ Add 150g of solution A to solution B and heat to 95℃, add 5g of hexamethylenetetramine, keep warm for 3h, filter and dry to obtain small particle size resin curing material of 5μm. Everything else is the same as in Example 1.

[0034] Example 6 Step 1. Prepare small-particle-size resin curing material with Dv50=6μm: ① Melt 100g of phenol at 40℃, then add 2g of sodium hydroxide and 150g of 37% formaldehyde in sequence, and heat to 70℃ and keep warm for 2h to obtain solution A. ② Add 2g of commercially available PVA to 400g of water and disperse to obtain solution B. ③ Add 150g of solution A to solution B and heat to 95℃, add 5g of hexamethylenetetramine, keep warm for 3h, filter and dry to obtain small particle size resin curing material of 5μm. Everything else is the same as in Example 1.

[0035] Comparative Example 1, pure microporous carbon Step 1 ① Melt 100g of phenol at 40℃, then add 2g of sodium hydroxide and 150g of 37% formaldehyde in sequence, and heat to 70℃ and keep warm for 2h to obtain solution A. ② Add 2g of commercially available PVA to 100g of water and disperse to obtain solution B. ③ Add solution A to solution B and heat to 95℃, add 5g of hexamethylenetetramine, keep warm for 3h, filter and dry to obtain small particle size resin curing material of 8μm. Step 2. Carbonization; The small-particle-size resin curing material obtained above is carbonized at high temperature. The carbonization conditions are 800℃ and 3h, to obtain carbonized material. Step 3. Activation: The above carbonized material is activated with steam and kept at 820°C for 3 hours to obtain a microporous carbon matrix; Step 4. Silicon is deposited on the microporous carbon matrix using chemical vapor deposition, and then a carbon coating layer is coated using chemical vapor deposition to prepare the silicon-carbon anode material.

[0036] Comparative Example 2, pure mesoporous carbon Step 1: Melt 100g of phenol at 40℃, then add 2g of sodium hydroxide and 150g of 37% formaldehyde sequentially, and heat to 70℃ and maintain the temperature for 2 hours to obtain solution A. Step 2: Mix 50 g ethanol, 5 g solution A, 10 g F127 and 7.5 g 0.2M hydrochloric acid, and stir at 40℃ for 2 h to obtain mesoporous carbon precursor solution. Step 3: Add the above 70g mesoporous carbon precursor solution to 300g heat transfer oil, keep it at 50℃ for 3h, and after the ethanol has completely evaporated, raise the temperature to 120℃ and keep it at 4h; separate the solid and liquid, wash to obtain the core-shell structured solidified material with a spherical particle size Dv50=8μm. Step 4, Carbonization: The solidified material with the core-shell structure obtained above is subjected to high-temperature carbonization. The carbonization conditions are 800℃ for 3 hours. Step 5: Soak the carbonized material in 10% HF for 24 hours and wash it with water three times. Repeat the above steps multiple times until the ash content is as low as 0.1%. No further activation is required to obtain a porous carbon matrix. Step 6: Silicon is deposited on the porous carbon substrate using chemical vapor deposition (CVD), followed by a carbon coating layer deposited using CVD to prepare the silicon-carbon anode material. The D prepared in Example 1... v SEM images of 50=5μm small particle size resin cured material are shown below. Figure 1 As can be seen, the prepared small-particle-size resin curing material has a uniform particle size. The cross-sectional SEM image of the silicon-carbon anode material particles prepared in Example 1 is shown below. Figure 2 As can be seen, the prepared silicon-carbon anode material exhibits a distinct core-shell structure. TEM images of the ordered mesoporous portion of the porous carbon particles prepared in Example 1 are shown below. Figure 3 As can be seen, the ordered mesoporous portion of the porous carbon particles has obvious ordered channels, clear striations, and a pore size of approximately 4 nm. TEM images of the microporous portion of the porous carbon particles prepared in Example 1 are shown below. Figure 4 As can be seen, the microporous portion of the porous carbon particles lacks a distinct ordered structure. The isothermal adsorption curves of the activated material prepared in Example 1 are shown below. Figure 5 It can be seen that the nitrogen relative pressure P / P0 in the range of 0-0.2 corresponds to the microporous nitrogen adsorption of porous carbon materials, while the nitrogen relative pressure P / P0 in the range of 0.2-0.6 corresponds to the mesoporous nitrogen adsorption of porous carbon materials, showing a typical microporous + mesoporous adsorption curve; the BJH mesoporous distribution of the activated material prepared in Example 1 is shown in [reference]. Figure 6 The figure shows that the activated material exhibits a distinct small pore size peak in the 2-7 nm range. Micropore testing: The porous carbon powder was passed through a 200-mesh sieve and then tested using a Bestech surface area analyzer. Electrode and half-cell preparation and electrochemical performance testing: The composite silicon-carbon materials prepared in the examples and comparative examples were used as negative electrode active materials to prepare negative electrode sheets. The negative electrode sheets were used to prepare CR2032 coin cells using conventional methods, and the electrical performance of the cells was tested.

[0037] Half-cell assembly: Assemble CR2032 coin cells in a glove box, using lithium metal sheets as the counter electrode, polypropylene microporous membranes as the separator, and LiPF6 dissolved in a mixture of ethyl carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC∶DEC=1∶1), with a LiPF6 concentration of 1mol / L.

[0038] The battery was tested for charge and discharge using the LAND battery testing system.

[0039] Cyclic specific capacity and initial efficiency test: After the CR2032 coin cell was left to stand for 6 hours, it was discharged at 0.1C to 0.005V, and the specific capacity was recorded as Q1; then it was discharged at a constant voltage of 0.005V until the current cutoff was 0.01C, and the specific capacity was recorded as Q2; after standing for 5 minutes, it was charged at a constant current of 0.1C to 0.8V, and the specific capacity was recorded as Q3; after standing for 5 minutes, it was charged at a constant current of 0.1C to 1.5V, and the specific capacity was recorded as Q4; after standing for 5 minutes, it was discharged at a constant current of 1.0C to 0.005V, and the specific capacity was recorded as Q5; after standing for 2 hours, the thickness of the negative electrode sheet was measured sequentially, and the average value was recorded as h1. Another coated and dried electrode sheet was taken, and the thickness of the negative electrode sheet at 5 points was measured, and the average value was recorded as h2. The initial lithium delithiation specific capacity is the specific capacity (or mass specific capacity) of the electrode material, and the ratio of the initial lithium delithiation capacity to the initial lithium insertion capacity is the initial coulombic efficiency of the battery.

[0040] 0.8V initial efficiency = Q3 / (Q1 + Q2) * 100%; 1.5V initial efficiency = (Q3 + Q4) / (Q1 + Q2) * 100%; 1C rate discharge retention rate = Q5 / (Q3 + Q4) * 100%; Lithium intercalation expansion ratio = h2 / h2 * 100%; Capacity retention test: Three cells were taken, allowed to stand for 5 minutes, then discharged at 0.1C constant current and constant voltage to 0.005V, allowed to stand for 5 minutes, discharged at 0.02C to 0.005V, and charged at 0.1C constant current and constant voltage to 1.5V; allowed to stand for 5 minutes, then discharged at 0.25C to 0.005V; allowed to stand for 5 minutes, then charged at 0.25C constant current to 1.5V, and cycled 50 times at a rate of 0.25C. The specific capacity of the 50th cycle / the charging capacity of the 1st cycle × 100% was used to calculate the specific capacity retention rate. The test results are shown in Tables 1 and 2 below.

[0041] Table 1

[0042] Table 2

[0043] Combining Tables 1 and 2 above, it can be seen that the ratio of micropores to mesopores in porous carbon matrices is adjustable, depending on the size of D1 / D2. The larger the value, the greater the proportion of micropores, and vice versa. As shown in Table 2, compared with Examples 1-5 in Example 1, this indicates that when the core-shell structure D1 / D2=0.617, the mesoporous content is 42.1%, exhibiting the best specific capacity retention and a better full-charge expansion ratio. A higher D1 / D2 increases the microporous structure and decreases the first-cycle efficiency. While a higher D1 / D2 also increases the mesoporous structure, it reduces the specific capacity retention. In Comparative Example 1, pure microporous silicon-carbon also verified the above experiment. Pure microporous carbon showed a significantly lower first-cycle efficiency compared to micro-mesoporous composite porous carbon because it lacks an expansion buffer region; increased expansion leads to a significant decrease in specific capacity retention. In Comparative Example 2, pure mesoporous carbon may have higher rate performance due to larger silicon particles and the formation of continuous, interconnected channels, but its high specific capacity retention may be due to the increased possibility of electrochemical sintering during charge and discharge, leading to a further increase in silicon particles and consequently reducing cycle retention.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 silicon-carbon anode material, characterized in that, The material comprises a porous carbon matrix and a silicon material. The porous carbon matrix has a core-shell structure, with the core having micropores and the shell having mesopores. The ratio of the average diameter D1 of the core to the average particle size D2 of the silicon-carbon anode material, D1 / D2, is 0.2-0.

9. The silicon material is distributed in the mesopores and micropores of the porous carbon matrix.

2. The porous carbon matrix material according to claim 1, characterized in that, Also includes: A coating layer is applied to the surface of the composite material formed by the porous carbon matrix and the silicon material, preferably with a thickness of 8-12 nm.

3. The silicon-carbon anode material according to claim 1, characterized in that, The silicon content in the silicon-carbon anode material is 5-90%, preferably 30-60%.

4. The silicon-carbon anode material according to any one of claims 1-3, characterized in that, The silicon-carbon anode material also satisfies one of the following characteristics: a. The average diameter Dv50 of the core is 1-10 μm, preferably 3-6 μm; the radial distance is 0.5-2.0, preferably 0.6-1.0; b. The average particle size Dv50 of the silicon-carbon anode material is 3-12, preferably 5-10 μm; the diameter spacing is 0.5-2.0, preferably 0.6-1.

2. c. The pore volume of the porous carbon matrix is ​​0.4-1.5 cm³. 3 / g, preferably 0.6-1.2cm 3 / g; d. The size of the mesoporous channels in the shell of the porous carbon matrix is ​​2-6 nm, and the mesoporous channels are ordered or disordered.

5. A method for preparing a silicon-carbon anode material according to any one of claims 1-4, characterized in that, Includes the following steps: A core-shell structured cured material is obtained by coating the surface of a small-particle-size resin cured material with a coating layer containing a template agent and resin. The core-shell structured cured material is then carbonized and the template is removed. After activation treatment, a porous carbon matrix is ​​obtained. The porous carbon matrix is ​​then subjected to vapor phase deposition of silicon to obtain a silicon-carbon anode material.

6. The preparation method according to claim 5, characterized in that, Includes the following steps: Step 1: Disperse the small-particle-size resin curing material in ethanol to obtain a resin curing material dispersion, wherein the mass of ethanol is 3-10 times the mass of the resin curing material; then add resin, hydrochloric acid and template agent to the resin curing material dispersion, and stir at 40°C for 1 hour until the solution is uniformly dispersed to obtain a mixed solution. Step 2: Add the mixed solution obtained in Step 1 to heat transfer oil with a mass of 1-5 times that of the mixed solution, keep it at 40℃-80℃ for 1-10 hours, and after the ethanol has completely evaporated, raise the temperature to 100-180℃ and keep it at 1-20 hours. After solid-liquid separation, the core-shell structured solidified material is obtained. Step 3: Calcine the core-shell structure solidified material obtained in Step 2 to remove the soft template agent, or immerse the core-shell structure solidified material in an alkaline solution or HF solution to remove the hard template agent, and then wash it with water until the ash content is less than 0.2% to obtain the carbonized material; Step 4: Activate the carbonized material obtained in Step 3 to obtain a porous carbon matrix, wherein the activation method is one or more of alkali activation, water activation, and carbon dioxide activation; Step 5: Place the porous carbon matrix obtained in Step 4 in a fluidized bed, heat it to 430°C, and purge it with 25% SiH4-N2 for 1-30 hours; then switch to N2 purging for 1 hour, then raise the temperature to 580°C, purge it with 25% C2H2-N2 for 1-30 hours, cool it down and switch to N2 to obtain a composite material in which silicon material is deposited in the pores of the porous carbon matrix.

7. The preparation method according to claim 6, characterized in that, Also includes: A coating layer is deposited on the surface of the composite material using a vapor phase deposition method. Preferably, a secondary coating is performed using carbon nanotubes and conductive paste.

8. The preparation method according to claim 6, characterized in that, The small-particle-size resin curing material is obtained by polymerizing a phenolic resin solution in water. The phenolic resin solution is prepared by mixing aldehyde raw materials, phenolic raw materials, catalyst and water. And / or, the preparation temperature of the phenolic resin is 40-100℃; And / or, the aldehyde raw materials include at least one of formaldehyde, acetaldehyde and furfural; And / or, the phenolic raw materials include at least one of phenol and resorcinol; And / or, the aldehyde raw material accounts for 60%-130% of the mass of the phenolic raw material; And / or, the catalyst includes at least one of an acidic catalyst and a basic catalyst; And / or, the catalyst accounts for 1%-5% of the mass of the phenols; And / or, the acidic catalyst includes at least one of hydrochloric acid, sulfuric acid, and oxalic acid; And / or, the alkaline catalyst includes at least one of sodium hydroxide, calcium hydroxide, and ammonia water.

9. The preparation method according to claim 6, characterized in that, The template agent includes one or more of soft template agents and hard template agents. The soft template agent is selected from one or more of poloxamer F127, poloxamer P123, and CTAB, and the hard template agent is selected from one or more of tetraethyl orthosilicate, aluminum isopropoxide, silica sol, aluminum sol, and sodium silicate.

10. The application of the silicon-carbon anode material according to any one of claims 1-4 or the silicon-carbon anode material prepared by the preparation method of the silicon-carbon anode material according to any one of claims 5-9 in the preparation of battery anodes.

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