Asphalt-based spherical porous carbon as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of carbon materials, and particularly relates to pitch-based spherical porous carbon as well as a preparation method and application thereof. A three-dimensional through pore channel structure is distributed in the porous carbon; the surface area of the porous carbon is 800-2500 m / g, the pore volume is 0.5-2.0 cm / g, the particle size D50 is 5-50 [mu] m, and the sphericity is greater than 0.9; the preparation method comprises the following steps: heating and mixing asphalt and a self-template agent, and forming asphalt-based microspheres through an emulsification method; then sequentially carrying out oxidation stabilization, carbonization and activation treatment; in the carbonization treatment process, a self-template agent is thermally decomposed to form pores in a carbon frame, and then an activating agent is used for etching and chambering, so that a three-dimensional through pore channel structure is cooperatively constructed. When the composite material is used as a carrier for a silicon-carbon negative electrode of a lithium ion battery, efficient and uniform loading of an active substance can be realized, a hole sealing phenomenon is effectively avoided, and the electrochemical performance of the battery is remarkably improved. The method is simple in process, low in cost and easy for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, specifically relating to a pitch-based spherical porous carbon, its preparation method, and its application. Background Technology

[0002] Porous carbon materials are widely used in energy storage, adsorption separation, and catalysis due to their high specific surface area, tunable pore structure, and good chemical stability. Among them, spherical porous carbon is highly favored in the field of electrochemical energy storage because of its advantages such as high packing density, good flowability, and uniform electrode slurry coating.

[0003] As a cheap and readily available carbon precursor, pitch is an ideal raw material for preparing carbon materials. Currently, porous carbon is often prepared using template methods (such as hard templates and soft templates) combined with activation processes. However, hard template methods suffer from cumbersome template removal steps and high costs; soft template methods have specific requirements for the molecular structure of the precursor, and the template structure is easily destroyed at high temperatures. Furthermore, the porous carbon prepared by the above methods has internal pores that are mostly blind or closed, with poor connectivity. When this material is used as a carrier, for example, for loading nano-silicon through chemical vapor deposition (CVD), the silane precursor gas has difficulty effectively diffusing into the interior of the particles, resulting in silicon mainly depositing on the surface of the spheres. This not only wastes the internal space of the carrier, but the excessive deposition on the surface can also easily clog the pores, forming a "sealing" effect, which seriously affects the transport of lithium ions and thus impairs the fast-charging performance and cycle stability of the battery. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a pitch-based spherical porous carbon, its preparation method, and its application. The pitch-based spherical porous carbon provided by this invention has a three-dimensional interconnected pore structure, which is achieved by constructing a three-dimensional interconnected pore network inside the carbon spheres through the synergistic effect of a self-templating agent and an activation process. The preparation process is simple and efficient.

[0005] The present invention is specifically implemented through the following technical solutions.

[0006] The first objective of this invention is to provide a pitch-based spherical porous carbon, wherein the porous carbon has a spherical structure and a three-dimensional interconnected pore structure distributed within it; the surface area of ​​the porous carbon is 800~2500 m² / g, the pore volume is 0.5~2.0 cm³ / g, the particle size D50 is 5~50 μm, and the sphericity is greater than 0.9.

[0007] Further preferred options are porous carbon with a BET specific surface area of ​​1500 m² / g to 2500 m² / g and a total pore volume of 1.0 cm³ / g to 2.0 cm³ / g.

[0008] After heating and mixing asphalt with a self-tempering agent, it is formed into asphalt-based microspheres by emulsification. Subsequently, oxidation stabilization treatment, carbonization treatment and activation treatment are carried out in sequence. During the carbonization treatment, the self-tempering agent is thermally decomposed to create pores inside the carbon framework. Then, the pores are enlarged by etching during the activation treatment with an activator, thus synergistically constructing a three-dimensional through-hole structure.

[0009] A second objective of this invention is to provide a method for preparing the above-mentioned pitch-based spherical porous carbon, comprising the following steps: After heating and mixing asphalt with a self-tempering agent, a homogeneous mixture is obtained. The homogeneous mixture is then molded into asphalt-based microspheres by an emulsification method.

[0010] Under the action of an oxidizing agent, asphalt-based microspheres are subjected to oxidative stabilization treatment to obtain oxidized microspheres. Specifically, the reaction process involves the oxidation and condensation reaction of aromatic components and resins in asphalt to obtain oxidized microspheres with high softening point and high structural stability.

[0011] Under a protective atmosphere, the oxide microspheres are carbonized. During the carbonization process, the self-templating agent is thermally decomposed to create pores inside the carbon framework, thus obtaining carbonized microspheres.

[0012] An activator is used to activate, etch, and expand the pores of carbonized microspheres to obtain spherical porous carbon.

[0013] Preferably, the emulsification method specifically includes the following steps: A homogeneous mixture is heated to a molten state or dissolved in an organic solvent to form a dispersed phase; The dispersed phase is added to a continuous phase containing a surfactant and emulsified under shear force to form emulsion droplets with a particle size distribution of 5 μm to 50 μm. The emulsion droplets are solidified into solid microspheres by cooling or solvent evaporation. The solid microspheres are separated from the continuous phase, washed, and dried to obtain asphalt-based microspheres.

[0014] Preferably, the asphalt is at least one of petroleum asphalt, coal tar pitch, and mesophase asphalt; the self-tempering agent is at least one of phenolic resin, sucrose, glucose, lignin, polyethylene oxide, and polyvinylpyrrolidone; the mass ratio of the self-tempering agent to the asphalt is 0.1 to 1:1, and the heating and mixing temperature is 150°C to 350°C.

[0015] Preferably, the continuous phase is water, silicone oil, or liquid paraffin; the surfactant is at least one selected from Span, Tween, polyvinyl alcohol, and sodium dodecyl sulfate.

[0016] Preferably, the oxidizing agent is hydrogen peroxide or an oxygen-containing atmosphere, wherein the oxygen-containing atmosphere is air or a mixture of ozone and air; the mass ratio of asphalt-based microspheres to hydrogen peroxide is 0.2~5:1; the temperature of the oxidation stabilization treatment is 200℃~400℃, the heating rate is 0.5℃ / min~5℃ / min, and the holding time is 1~10 hours.

[0017] Preferably, the carbonization temperature is 600℃~1200℃, and the holding time is 0.5~10 hours; the protective atmosphere is nitrogen or argon.

[0018] Preferably, the activator is water vapor or carbon dioxide; the activation temperature for etching and expanding the hole is 700℃~1000℃, and the time is 0.5~10 hours.

[0019] The third objective of this invention is to provide the application of the above-mentioned pitch-based spherical porous carbon in the silicon-carbon composite anode of lithium-ion batteries. Pitch-based spherical porous carbon is used as a carrier, and silicon is deposited in the carrier by CVD. The nano-silicon particles are uniformly distributed in the interior and surface of the spherical porous carbon, thereby obtaining the silicon-carbon composite anode of lithium-ion batteries.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a pitch-based spherical porous carbon with a three-dimensional interconnected pore structure. The porous carbon has a BET specific surface area of ​​800 m² / g to 2500 m² / g, a total pore volume of 0.5 cm³ / g to 2.0 cm³ / g, a particle size D50 of 5 to 50 μm, and a sphericity greater than 0.9. This unique interconnected pore structure allows silane precursor gas to penetrate uniformly and deeply into the interior of the spheres when used as a nano-silicon carrier, achieving uniform silicon loading and effectively avoiding the "pore sealing" phenomenon caused by excessively rapid surface deposition. This significantly improves the electrochemical performance of the material as a silicon-carbon anode.

[0021] This invention proposes an innovative pore design method that cleverly utilizes the thermal decomposition of a self-templating agent during carbonization to generate internal pores (pore creation), and then uses an activation reaction to etch and expand the pore walls (pore expansion). The two work together to achieve a "internal and external linkage" pore creation mechanism, ultimately forming highly developed three-dimensional through-pores inside the spherical carbon.

[0022] The present invention features a simple and low-cost process: it adopts a "self-templating" strategy, avoiding complex and cumbersome template removal steps; it uses inexpensive asphalt as the main raw material, combined with mature emulsification, oxidation, carbonization and activation processes, with a clear route and easy industrial-scale production.

[0023] The morphology and structure of the product of this invention are controllable. The sphericity and particle size distribution of the product can be precisely controlled by the emulsification method. By adjusting the type and proportion of the self-templating agent and the activation process parameters, the specific surface area, pore volume and pore size distribution of the material can be precisely controlled.

[0024] Therefore, this invention obtains pitch-based spherical porous carbon with a three-dimensional interconnected pore structure through a simple pore-forming method, which is beneficial for the industrial production and application of spherical porous carbon. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope (SEM) image of the pitch-based spherical porous carbon prepared in Example 1 of the present invention.

[0026] Figure 2 This is a nitrogen adsorption isotherm curve of the pitch-based spherical porous carbon prepared in Example 1 of the invention.

[0027] Figure 3 This is a test diagram of the cycle stability of silicon-carbon anode material prepared using spherical porous carbon as a carrier. Detailed Implementation

[0028] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention. Unless otherwise specified, the experimental methods and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials described are commercially available.

[0029] The sources of raw materials used in the following examples and comparative examples: Mesophase pitch: Jining Chaolian New Material Technology Co., Ltd., softening point 200~250℃, content 95%.

[0030] Phenolic resin: Hebei Ruitan New Energy Technology Co., Ltd., solid content ≥75%.

[0031] Polyvinyl alcohol: Merck, molecular weight ~31,000.

[0032] Coal tar pitch: Ningxia Xitai Coal Chemical Co., Ltd., softening point 120~220℃.

[0033] Sucrose: Guangxi Fengtang Liutang Sugar Manufacturing Co., Ltd., content ≥99%, moisture ≤0.5%.

[0034] Liquid paraffin: China National Petroleum Corporation Fushun Petrochemical, standard: NB / SH / T 0417-2024.

[0035] Span-80: Shaanxi Chenming Biotechnology Co., Ltd., content ≥99%.

[0036] Petroleum asphalt: Liaoning Xinde New Material Technology Co., Ltd., softening point 200~280℃.

[0037] Glucose: Shandong Fuyang Biotechnology Co., Ltd., content ≥99.5%.

[0038] Example 1 A method for preparing pitch-based spherical porous carbon includes the following steps: Step 1, Mixing: Heat and stir 50g of mesophase pitch and 25g of phenolic resin (mass ratio 1:0.5) at 250℃ for 2 hours to obtain a homogeneous mixture.

[0039] Step 2, Forming the ball: a. Keep the above mixture in a molten state at 200°C as the dispersed phase.

[0040] b. Use an aqueous solution containing 1 wt% polyvinyl alcohol as the continuous phase and preheat it to 80°C.

[0041] c. Under high-speed shearing (10000 rpm), the dispersed phase is added dropwise to the continuous phase at a volume ratio of 1:25, and emulsification is carried out for 20 minutes to form an emulsion.

[0042] d. Cool the emulsion to room temperature to solidify the droplets. After filtration, washing with deionized water, and vacuum drying at 80°C for 12 hours, asphalt-based microspheres with a particle size D50 of approximately 15 μm were obtained.

[0043] Step 3, Oxidative Stabilization: The obtained pitch-based microspheres are placed in a converter and heated to 300°C at a rate of 1°C / min under air atmosphere, and held at that temperature for 5 hours to obtain oxidized microspheres.

[0044] Step 4, carbonization: Place the oxide microspheres in a tube furnace, and under nitrogen protection, heat to 800℃ at 5℃ / min, carbonize and hold for 2 hours, and then naturally cool to obtain carbonized microspheres.

[0045] Step 5, Activation: Place the carbonized microspheres in a rotary kiln and introduce a mixture of water vapor and nitrogen (water vapor partial pressure is 50%). Activate at 850℃ for 2 hours to obtain the final product, pitch-based spherical porous carbon.

[0046] Characterization showed that the product has a BET specific surface area of ​​1850 m² / g, a total pore volume of 1.63 cm³ / g, a particle size D50 of 16 μm, and excellent sphericity. Figure 1 This is a scanning electron microscope (SEM) image of the pitch-based spherical porous carbon prepared in Example 1 of the present invention. Figure 2This is a nitrogen adsorption isotherm curve of the pitch-based spherical porous carbon prepared in Example 1 of the invention. The morphology diagram clearly shows that the material exhibits a regular spherical morphology, and the adsorption diagram shows a large number of micro / mesopores on the surface, indicating that it has a well-developed pore structure inside.

[0047] Example 2 A method for preparing pitch-based spherical porous carbon includes the following steps: Step 1, Mixing: Heat and stir 50g of coal tar pitch and 15g of sucrose (mass ratio 1:0.3) at 200℃ for 1.5 hours.

[0048] Step 2, Pelletization: Similar to Step 2 of Example 1, but using liquid paraffin as the continuous phase and Span-80 as the surfactant, curing is performed via solvent evaporation. The specific steps are as follows:

[0049] a. Keep the above mixture in a molten state at 200°C as the dispersed phase.

[0050] b. Use liquid paraffin containing 1 wt% Span-80 as the continuous phase and preheat it to 80°C.

[0051] c. Under high-speed shearing (10000 rpm), the dispersed phase is added dropwise to the continuous phase at a volume ratio of 1:20, and emulsification is carried out for 20 minutes to form an emulsion.

[0052] d. The droplets were solidified by evaporating the solvent at 130°C. After filtration, washing with deionized water, and vacuum drying at 80°C for 12 hours, pitch-based microspheres with a particle size D50 of approximately 28 μm were obtained.

[0053] Step 3, Oxidative Stabilization: The asphalt-based microspheres are immersed in 30% hydrogen peroxide (the mass ratio of microspheres to hydrogen peroxide is 1:2), treated at 60°C for 6 hours, filtered and dried, and then treated in air at 250°C for 2 hours.

[0054] Step 4, carbonization: Under an argon atmosphere, heat to 1000℃ at a rate of 5℃ / min and carbonize for 1 hour.

[0055] Step 5, Activation: In a fluidized bed, carbon dioxide is introduced and activated at 900°C for 3 hours.

[0056] The obtained product has a BET specific surface area of ​​2100 m² / g and a total pore volume of 1.75 cm³ / g.

[0057] Example 3 A method for preparing pitch-based spherical porous carbon includes the following steps: Step 1, Mixing: Heat and stir 50g of petroleum asphalt and 20g of glucose (mass ratio 1:0.4) at 180℃ for 1 hour to form a homogeneous mixture.

[0058] Step 2, Spheroidization: The mixture was dissolved in N-methylpyrrolidone (NMP) to form a 50 wt% solution as the dispersed phase. This solution was then added dropwise to an aqueous solution containing 2 wt% sodium dodecyl sulfate (SDS), with a dispersed phase to continuous phase volume ratio of 1:20, and emulsified under 8000 rpm shear. The droplets were solidified by evaporating the solvent by heating to 90°C. After separation, washing, and drying, asphalt-based microspheres with a particle size D50 of approximately 25 μm were obtained.

[0059] Step 3, Oxidation Stabilization: Place the microspheres in a converter, introduce air containing 5% ozone, heat to 280℃ at 2℃ / min, and hold for 4 hours.

[0060] Step 4, carbonization: Under a nitrogen atmosphere, heat to 700℃ at a rate of 3℃ / min and carbonize for 3 hours.

[0061] Step 5, Activation: In a rotary kiln, steam (partial pressure 30%) is introduced and activated at 750°C for 4 hours.

[0062] Example 4 A method for preparing pitch-based spherical porous carbon includes the following steps: Step 1, Mixing: Heat and stir 50g of coal tar pitch and 30g of lignin (mass ratio 1:0.6) at 220℃ for 2.5 hours.

[0063] Step 2, Spheroidization: The method is similar to Step 2 of Example 1, using silicone oil as the continuous phase and Tween-85 as the surfactant to obtain pitch-based microspheres with a particle size D50 of approximately 35 μm.

[0064] Step 3, Oxidative Stabilization: Immerse the microspheres in 50% hydrogen peroxide (mass ratio 1:3), treat at 80℃ for 3 hours, then filter and dry.

[0065] Step 4, carbonization: Under an argon atmosphere, the temperature is increased to 900℃ at a rate of 10℃ / min, and carbonization is maintained at this temperature for 1.5 hours.

[0066] Step 5, Activation: In a fluidized bed, carbon dioxide is introduced and activated at 950°C for 1 hour.

[0067] Example 5 A method for preparing pitch-based spherical porous carbon includes the following steps: Step 1, Mixing: Heat and stir 50g of mesophase asphalt and 5g of polyethylene oxide (PEO, Mw=100,000) (mass ratio 1:0.1) at 170℃ for 1 hour.

[0068] Step 2, Spheroidization: The method is similar to Step 2 of Example 1, but the shear rate is increased to 15000 rpm to obtain fine asphalt-based microspheres with a particle size D50 of about 8 μm.

[0069] Step 3, Oxidation Stabilization: In air, slowly heat to 350°C at a rate of 0.5°C / min and hold for 8 hours.

[0070] Step 4, carbonization: Under a nitrogen atmosphere, heat to 1100℃ at a rate of 5℃ / min and hold for 0.5 hours.

[0071] Step 5, Activation: In a rotary kiln, introduce steam (partial pressure 60%) and activate at 900°C for 1 hour.

[0072] Example 6 A method for preparing pitch-based spherical porous carbon includes the following steps: Step 1, Mixing: Heat and stir 50g of petroleum asphalt and 50g of polyvinylpyrrolidone (PVP, K30) (mass ratio 1:1) at 150℃ for 3 hours.

[0073] Step 2, Spheroidization: The method is similar to that in Example 3. After forming the dispersed phase, emulsification is performed to obtain asphalt-based microspheres with a particle size D50 of approximately 20 μm.

[0074] Step 3, Oxidative Stabilization: In air, heat to 200°C at a rate of 5°C / min and hold for 10 hours.

[0075] Step 4, carbonization: Under a nitrogen atmosphere, heat to 600℃ at a rate of 5℃ / min and hold for 5 hours.

[0076] Step 5, Activation: In a rotary kiln, carbon dioxide is introduced and activated at 1000℃ for 0.5 hours.

[0077] Comparative Example 1 Without adding a self-tempering agent, only mesophase bitumen is used, and the remaining steps are exactly the same as in Example 1. Specifically, the following steps are included:

[0078] Step 1, Forming the ball: a. Keep 50g of mesophase asphalt in a molten state at 200℃ as the dispersed phase.

[0079] b. Use an aqueous solution containing 1 wt% polyvinyl alcohol as the continuous phase and preheat it to 80°C.

[0080] c. Under high-speed shearing (10000 rpm), the dispersed phase is added dropwise to the continuous phase and emulsified for 20 minutes to form an emulsion.

[0081] d. Cool the emulsion to room temperature to solidify the droplets. After filtration, washing with deionized water, and vacuum drying at 80°C for 12 hours, asphalt-based microspheres with a particle size D50 of approximately 15 μm were obtained.

[0082] Step 2, Oxidative Stabilization: The obtained pitch-based microspheres are placed in a converter and heated to 300°C at a rate of 1°C / min under air atmosphere, and held at that temperature for 5 hours to obtain oxidized microspheres.

[0083] Step 3, carbonization: Place the oxide microspheres in a tube furnace, and under nitrogen protection, heat to 800℃ at 5℃ / min, carbonize and hold for 2 hours, and then naturally cool to obtain carbonized microspheres.

[0084] Step 4, Activation: Place the carbonized microspheres in a rotary kiln, introduce a mixture of water vapor and nitrogen (water vapor partial pressure is 50%), and activate at 850℃ for 2 hours to obtain the final product.

[0085] Results: The specific surface area of ​​the obtained carbon spheres was only 1350 m² / g, and the nitrogen adsorption isotherm showed that they were mainly microporous with poor pore connectivity.

[0086] Comparative Example 2 Compared to Example 1, no activation is performed. Specifically, the following steps are included:

[0087] Step 1, Mixing: Heat and stir 50g of mesophase pitch and 25g of phenolic resin (mass ratio 1:0.5) at 250℃ for 2 hours to obtain a homogeneous mixture.

[0088] Step 2, Forming the ball: a. Keep the above mixture in a molten state at 200°C as the dispersed phase.

[0089] b. Use an aqueous solution containing 1 wt% polyvinyl alcohol as the continuous phase and preheat it to 80°C.

[0090] c. Under high-speed shearing (10000 rpm), the dispersed phase is added dropwise to the continuous phase and emulsified for 20 minutes to form an emulsion.

[0091] d. Cool the emulsion to room temperature to solidify the droplets. After filtration, washing with deionized water, and vacuum drying at 80°C for 12 hours, asphalt-based microspheres with a particle size D50 of approximately 15 μm were obtained.

[0092] Step 3, Oxidative Stabilization: The obtained pitch-based microspheres are placed in a converter and heated to 300°C at a rate of 1°C / min under air atmosphere, and held at that temperature for 5 hours to obtain oxidized microspheres.

[0093] Step 4, carbonization: Place the oxide microspheres in a tube furnace, and under nitrogen protection, heat to 800℃ at 5℃ / min, carbonize and hold for 2 hours, and then naturally cool to obtain carbonized microspheres.

[0094] The product parameters prepared in the above embodiments and comparative examples are shown in Table 1. The particle size D50 was obtained using a laser particle size analyzer, the specific surface area and total pore volume were obtained using a physical adsorption analyzer, and the sphericity was obtained using a dynamic image method.

[0095] Table 1. Product parameters prepared in the examples and comparative examples As can be seen from Table 1, compared with Comparative Example 1 and Comparative Example 2, the product prepared by the present invention has a more developed pore structure.

[0096] Application Examples Using the spherical porous carbon obtained in Example 1 as a carrier and silane as a silicon source, silicon nanoparticles were deposited in a fluidized bed at 510°C via CVD. The temperature was then increased to 700°C, and a protective layer was formed on the surface of the silicon-carbon material by thermally decomposing acetylene. The study showed that the nano-silicon particles were uniformly distributed inside and on the surface of the spherical porous carbon, and the pores remained open. The carbon was then assembled into a battery for testing. Figure 3 The silicon-carbon anode material prepared using spherical porous carbon as a carrier exhibits good cycle stability.

[0097] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A pitch-based spherical porous carbon, characterized in that, The porous carbon has a spherical structure with three-dimensional interconnected channels distributed within it. The specific surface area of ​​the porous carbon is 800 m² / g to 2500 m² / g, the total pore volume is 0.5 cm³ / g to 2.0 cm³ / g, the particle size D50 is 5 μm to 50 μm, and the sphericity is greater than 0.

9. After heating and mixing asphalt with a self-tempering agent, it is formed into asphalt-based microspheres by emulsification. Subsequently, oxidation stabilization treatment, carbonization treatment and activation treatment are carried out in sequence. During the carbonization treatment, the self-tempering agent is thermally decomposed to create pores inside the carbon framework. Then, the pores are enlarged by etching during the activation treatment with an activator, thus synergistically constructing a three-dimensional through-hole structure.

2. The pitch-based spherical porous carbon according to claim 1, characterized in that, The BET specific surface area of ​​porous carbon is 1500m² / g to 2500m² / g, and the total pore volume is 1.0cm³ / g to 2.0cm³ / g.

3. A method for preparing pitch-based spherical porous carbon according to claim 1, characterized in that, Includes the following steps: After heating and mixing asphalt with a self-tempering agent, a homogeneous mixture is obtained. The homogeneous mixture is then molded into asphalt-based microspheres by an emulsification method. Under the action of an oxidizing agent, asphalt-based microspheres are subjected to oxidative stabilization treatment to obtain oxidized microspheres; Under a protective atmosphere, the oxide microspheres are carbonized. During the carbonization process, the self-templating agent is thermally decomposed to create pores inside the carbon framework, thus obtaining carbonized microspheres. An activator is used to activate, etch, and expand the pores of carbonized microspheres to obtain spherical porous carbon.

4. The preparation method according to claim 3, characterized in that, The emulsification method specifically includes the following steps: A homogeneous mixture is heated to a molten state or dissolved in an organic solvent to form a dispersed phase; The dispersed phase is added to a continuous phase containing a surfactant and emulsified under shear force to form emulsion droplets with a particle size distribution of 5 μm to 50 μm. The emulsion droplets are solidified into solid microspheres by cooling or solvent evaporation. The solid microspheres are separated from the continuous phase, washed, and dried to obtain asphalt-based microspheres.

5. The preparation method according to claim 3, characterized in that, asphalt It is at least one of petroleum asphalt, coal tar pitch, and mesophase asphalt; the self-tempering agent is at least one of phenolic resin, sucrose, glucose, lignin, polyethylene oxide, and polyvinylpyrrolidone; the mass ratio of the self-tempering agent to asphalt is 0.1 to 1:

1.

6. The preparation method according to claim 4, characterized in that, The continuous phase is water, silicone oil, or liquid paraffin; the surfactant is at least one of Span, Tween, polyvinyl alcohol, and sodium dodecyl sulfate.

7. The preparation method according to claim 3, characterized in that, The oxidizing agent is hydrogen peroxide or an oxygen-containing atmosphere, which is air or a mixture of ozone and air; the mass ratio of asphalt-based microspheres to hydrogen peroxide is 0.2~5:1; the temperature for oxidation stabilization treatment is 200℃~400℃, and the holding time is 1~10 hours.

8. The preparation method according to claim 3, characterized in that, The carbonization temperature is 600℃~1200℃, and the holding time is 0.5~10 hours.

9. The preparation method according to claim 3, characterized in that, The activator is water vapor or carbon dioxide; the activation temperature for etching and expanding the hole is 700℃~1000℃, and the time is 0.5~10 hours.

10. The application of the pitch-based spherical porous carbon according to claim 1 in the silicon-carbon composite anode of lithium-ion batteries, characterized in that, Using pitch-based spherical porous carbon as a carrier, silicon is deposited in the carrier by CVD. The nano-silicon particles are uniformly distributed inside and on the surface of the spherical porous carbon, thus obtaining a silicon-carbon composite anode for lithium-ion batteries.

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