A spherical porous carbon, its preparation method and application

Abstract

The present invention provides a spherical porous carbon, a preparation method thereof and an application thereof, relating to the technical field of porous carbon materials. The preparation method provided by the present invention includes: spray-drying a phenolic resin solution dissolved with a lithium compound and a boron compound to obtain resin microspheres; pre-oxidizing the resin microspheres at 150°C - 300°C to obtain carbon sphere precursors; carbonizing the carbon sphere precursors in an inert atmosphere at 1000°C - 1200°C to obtain carbon microspheres; cyclically activating and pore-forming the carbon microspheres in an active atmosphere at 800°C - 1000°C to obtain porous microspheres; reducing the porous microspheres in a reducing atmosphere at 400°C - 600°C to obtain spherical porous carbon. The present invention can prepare a spherical porous carbon material with developed micropores and a high specific surface area, and at the same time has a high Coulomb efficiency and good conductivity. The used preparation method is simple and efficient, which is beneficial to large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of porous carbon materials, and in particular to a spherical porous carbon, a preparation method thereof, and an application thereof. Background Art

[0002] Due to advantages such as a large specific surface area, high chemical stability, and adjustable pore size, porous carbon materials have been widely used in environmental governance, catalysis, energy storage and other fields. In the field of lithium-ion batteries, the developed microporous structure on the surface of multi-carbon materials can accommodate nanoscale silicon particles, relieve the volume expansion during charge and discharge, and significantly improve the electrochemical performance of silicon-carbon anode materials. Spherical porous carbon has become a key research object due to its excellent isotropy and other characteristics.

[0003] Currently, the main pore-forming methods for preparing spherical porous carbon are alkali etching method, steam activation method and carbon dioxide activation method. Among them, the alkali etching method has a high reaction rate, which is not conducive to the formation of micropores, and is easy to damage the spherical morphology. At the same time, the later cleaning and removal process is complex, increasing the production cost; the reaction rate of the steam activation method is lower than that of the alkali etching method, but it is also relatively fast, tending to form micropores and mesopores, and hydrogen is generated during the activation reaction process, there are certain production safety problems; the reaction rate of the carbon dioxide activation method is the lowest among the three activation methods, and its activation process tends to form micropores, but its low reaction rate is not conducive to the formation of porous carbon materials with a high specific surface area, and its activation product CO will be adsorbed in the generated micropores, which is not conducive to subsequent reactions. At the same time, due to the problems of hard carbon materials being difficult to graphitize and having many defects, their first Coulomb efficiency is low and their conductivity is poor. Therefore, there is an urgent need to provide a solution to improve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a spherical porous carbon, a preparation method thereof, and an application thereof, which can obtain a spherical porous carbon material with developed micropore porosity and a high specific surface area, and at the same time has a high Coulomb efficiency and good conductivity. The preparation method used is simple and efficient, which is conducive to large-scale industrial production.

[0005] In the first aspect, a preparation method of a spherical porous carbon provided by the present invention includes: spray-drying a phenolic resin solution dissolved with a lithium compound and a boron compound to obtain resin microspheres; pre-oxidizing the resin microspheres at 150°C - 300°C to obtain carbon sphere precursors; carbonizing the carbon sphere precursors in an inert atmosphere at 1000°C - 1200°C to obtain carbon microspheres; circularly activating and creating pores in the carbon microspheres in an active atmosphere at 800°C - 1000°C to obtain porous microspheres; reducing the porous microspheres in a reducing atmosphere at 400°C - 600°C to obtain spherical porous carbon.

[0006] Optionally, the lithium compound includes one of lithium sulfate, lithium nitrate, lithium carbonate, and lithium oxide.

[0007] Optionally, the boron compound includes one of boric acid, boron trioxide, trimethylboron, and sodium tetraborate.

[0008] Optionally, the concentration of the phenolic resin in the phenolic resin solution is 0.1 g / mL - 0.5 g / mL.

[0009] Optionally, the concentration of the lithium compound in the phenolic resin solution is 0.1 mol / L - 0.5 mol / L.

[0010] Optionally, the concentration of the boron compound in the phenolic resin is 0.05 mol / L - 0.3 mol / L.

[0011] Optionally, spray drying is carried out at 160°C - 200°C.

[0012] Optionally, spray drying is carried out at a humidity of 80% - 90%.

[0013] Optionally, the particle size of the resin microspheres is 5 μm - 50 μm.

[0014] Optionally, after the crosslinking agent and the catalyst are stirred and dissolved in the phenolic resin solution, they are then stirred and mixed with the mixed solution in which the lithium compound and the boron compound are dissolved to obtain a phenolic resin solution in which the lithium compound and the boron compound are dissolved.

[0015] Optionally, the crosslinking agent includes one of formaldehyde, glyoxal, benzaldehyde, and hexamethylenetetramine.

[0016] Optionally, the catalyst includes one of sodium hydroxide and potassium hydroxide.

[0017] Optionally, the mass ratio of the phenolic resin in the phenolic resin solution to the crosslinking agent is 10:(1 - 2).

[0018] Optionally, the mass ratio of the phenolic resin in the phenolic resin to the catalyst is 10:(6 - 8).

[0019] Optionally, the solvent of the phenolic resin solution includes a good solvent and a non-solvent. The good solvent includes one of ethanol, acetone, dimethylacetamide, and N,N-dimethylformamide, and the non-solvent includes one of water, carbon tetrachloride, and ethyl silicate.

[0020] Optionally, pre-oxidation is carried out in an oxygen-containing atmosphere at 150°C - 300°C, and the oxygen concentration in the oxygen-containing atmosphere is 10% - 50%.

[0021] Optionally, pre-oxidation is carried out at 150°C - 300°C for 2 h - 4 h.

[0022] Optionally, the resin microspheres are heated to 150° C.-300° C. at a rate of 1° C. / min-20° C. / min.

[0023] Optionally, pre-oxidation is carried out at 150° C.-300° C. and 0.08-0.15 MPa.

[0024] Optionally, constant temperature pre-oxidation is performed within 150°C-300°C.

[0025] Optionally, the inert atmosphere includes one of nitrogen, helium, neon and argon.

[0026] Optionally, carbonization treatment is performed at 1000° C.-1200° C. for 3 h-6 h.

[0027] Optionally, the carbonization treatment is performed in an inert atmosphere of -1 kPa to 1 kPa.

[0028] Optionally, a constant temperature carbonization treatment is performed at 1000°C-1200°C.

[0029] Optionally, the carbon sphere precursor is heated at a rate of 1°C / min-20°C / min.

[0030] Optionally, the active atmosphere includes one of carbon dioxide and water vapor.

[0031] Optionally, the number of cycles is 2 to 5 times.

[0032] Optionally, the carbon microspheres are activated and pore-forming treated for 10 min to 30 min in each cycle.

[0033] Optionally, the pressure of the active atmosphere in each cycle is independently -100 kPa to 10 kPa.

[0034] Optionally, the total duration of the cyclic pore creation is 1h-2h.

[0035] Optionally, the reducing atmosphere includes a reducing gas and an inert carrier gas, and the reducing gas includes hydrogen.

[0036] Optionally, the concentration of the reducing gas in the reducing atmosphere is 10%-100%.

[0037] Optionally, the flow rate of the reducing atmosphere is 30 mL / min-100 mL / min.

[0038] Optionally, the porous microspheres are subjected to reduction treatment for 1 h to 3 h.

[0039] In a second aspect, the present invention also provides a spherical porous carbon prepared by any of the above optional preparation methods.

[0040] In a third aspect, the present invention also provides an application of the spherical porous carbon prepared by any of the above optional preparations in a lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flowchart of a method for preparing a spherical porous carbon provided by the present invention;

[0042] Figure 2 is an electron microscope image of the spherical porous carbon prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] 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. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meaning as understood by those of ordinary skill in the art in the field to which the present invention belongs.

[0044] See Figure 1 , the present invention provides a method for preparing a spherical porous carbon, including:

[0045] S1, spray-drying a phenolic resin solution dissolved with a lithium compound and a boron compound to obtain resin microspheres;

[0046] S2, pre-oxidizing the resin microspheres at 150°C - 300°C to obtain carbon sphere precursors;

[0047] S3, carbonizing the carbon sphere precursors in an inert atmosphere at 1000°C - 1200°C to obtain carbon microspheres;

[0048] S4, circularly activating and creating pores in the carbon microspheres in an active atmosphere at 800°C - 1000°C to obtain porous microspheres;

[0049] S5, reducing the porous microspheres in a reducing atmosphere at 400°C - 600°C to obtain spherical porous carbon.

[0050] In fact, the preparation method provided by the present invention can regulate the carbonization process in stages during each process of porous carbon forming, and control the morphology and distribution of the pores formed in the porous carbon, thereby effectively improving the micropores and distribution uniformity of the spherical porous carbon, and at the same time can increase the specific surface area of the spherical porous carbon, which is beneficial to the next application of the porous carbon material. In addition, the preparation method provided by the present invention has a simple process, does not require the use of complex mechanical equipment, and each intermediate product can be stored and sold separately during the production process, which is beneficial to large-scale industrial production.

[0051] Actually, when performing step S1, dissolving lithium compounds and boron compounds in the phenolic resin solution in advance is beneficial to the uniform dispersion of lithium ions, boron ions and phenolic resin. At the same time, it can also utilize the template effect of lithium ions to form resin microspheres with uniform size with phenolic resin during the spray drying process, and lithium and boron elements are also doped in the resin microspheres.

[0052] In some embodiments, when performing step S1, it includes: stirring and dissolving a crosslinking agent and a catalyst in the phenolic resin solution, and then stirring and mixing with a mixed solution dissolved with lithium compounds and boron compounds to obtain a phenolic resin solution dissolved with lithium compounds and boron compounds. Actually, by adding a crosslinking agent and a catalyst to the phenolic resin solution, the curing structure and molecular network of the phenolic resin can be effectively regulated during the spray drying process, the structural stability of the resin microspheres can be effectively improved, and at the same time, the curing structure of the phenolic resin can be optimized to improve the structural strength of the carbon microspheres, which is beneficial to the porous carbon maintaining a spherical shape during the preparation process.

[0053] In some embodiments, the crosslinking agent used includes one of formaldehyde, glyoxal, benzaldehyde, hexamethylenetetramine. Actually, adding the crosslinking agent to the phenolic resin solution in advance can not only effectively promote the covalent bond connection between the phenolic resin molecular chains to accelerate the formation of a network structure to form resin microspheres during the spray drying process, but also improve the crosslinking density of the resin microspheres to avoid structural collapse during the carbonization process.

[0054] In some embodiments, the catalyst used includes one of sodium hydroxide and potassium hydroxide. Actually, after adding the catalyst, the polycondensation reaction of the phenolic resin is adjusted to promote the branching crosslinking of the phenolic resin in an alkaline environment, which is beneficial to the formation of resin microspheres in the droplets during the spray drying process. In addition, the catalyst used will remain in the porous carbon during the subsequent carbonization process and act as a templating agent to form additional pores, further increasing the specific surface area of the porous carbon.

[0055] In some embodiments, the lithium compound used includes one of lithium sulfate, lithium nitrate, lithium carbonate, lithium oxide, and the boron compound used includes one of boric acid, boron trioxide, trimethylboron, sodium tetraborate. Actually, by pre-dissolving the lithium compound and the boron compound to make a mixed solution, the distribution uniformity of the lithium compound and the boron compound can be effectively improved. At the same time, using the mixed solution and the phenolic resin solution for liquid-liquid mixing is beneficial to improving the mixing uniformity of various raw materials, and then improving the consistency after making the resin microspheres.

[0056] In some embodiments, lithium compounds and boron compounds can be pre-dissolved in commonly used solvents in the art such as water, ethanol, dimethyl sulfoxide, dimethyl carbonate, etc. to form a mixed solution. Specifically, after uniformly mixing the phenolic resin solution with the mixed solution, the mass ratio of phenolic resin, cross-linking agent, and catalyst in the resulting solution is 10:(1 - 2):(6 - 8). In addition, the solvents in the phenolic resin solution include good solvents and non-solvents, and the good solvents include one of ethanol, acetone, dimethylacetamide, and N,N-dimethylformamide, and the non-solvents include one of water, carbon tetrachloride, and ethyl silicate.

[0057] In some embodiments, the concentration of the phenolic resin used in step S1 is 0.1 g / mL - 0.5 g / mL. In addition, the concentration of the lithium compound dissolved in the phenolic resin solution is 0.1 mol / L - 0.5 mol / L, and the concentration of the boron compound dissolved is 0.05 mol / L - 0.3 mol / L. Specifically, when performing step S1, the phenolic resin solution dissolved with lithium compounds and boron compounds can be spray-dried at 160°C - 200°C and a humidity of 80% - 90%. In addition, the particle size of the resin microspheres obtained after performing step S1 is 5 μm - 50 μm.

[0058] In some embodiments, when performing step S2, the resin microspheres are subjected to a constant-temperature pre-oxidation treatment for 2 h - 4 h in an oxygen-containing atmosphere at 150°C - 300°C and 0.08 - 0.15 MPa. In fact, the resin microspheres can be pre-placed in an atmosphere furnace, and after using an oxygen-containing atmosphere to displace the gas in the atmosphere furnace, the atmosphere furnace is heated to 150°C - 300°C at a rate of 1°C / min - 20°C / min. Specifically, the oxygen concentration in the oxygen-containing atmosphere is 10% - 50%. Further, the oxygen-containing atmosphere can be clean air.

[0059] In fact, in step S2, through the pre-oxidation treatment in an oxygen-containing atmosphere, it can promote the oxidative cross-linking of the phenolic resin molecular chains, and at the same time improve the structural stability of elements such as lithium and boron doped in the resin microspheres, which is conducive to the formation of a stable pore structure during the subsequent carbonization process. At the same time, during the pre-oxidation process, it can play a buffering role on the resin microspheres, avoiding the structural collapse caused by directly carbonizing the resin microspheres.

[0060] In some embodiments, the inert atmosphere used when performing step S3 includes one of nitrogen, helium, neon, and argon. In fact, through the carbonization treatment in an inert atmosphere, it can isolate oxygen from reacting with the carbon sphere precursor, and at the same time can regulate the pyrolysis reaction, thereby promoting the formation of a stable carbon skeleton from the un-decomposed organic chains in the carbon sphere precursor. In addition, after carbonization treatment at 1000°C - 1200°C for 3 h - 6 h, it is beneficial for the carbon layer to rearrange and graphitize, thereby effectively improving the conductivity of the porous carbon material.

[0061] In some embodiments, when performing step S3, the carbon precursor obtained by pre-oxidation can be heated to 1000°C - 1200°C at a rate of 1°C / min - 20°C / min in an inert atmosphere, and carbonization treatment is carried out in an inert atmosphere of -1 kPa to 1 kPa. In fact, during the carbonization process, boron added in step S1 can form a composite structure with carbon and be embedded in the carbon layer, thereby effectively inhibiting the high-temperature shrinkage of the carbon skeleton and effectively maintaining the spherical structure of the porous carbon.

[0062] In fact, the active atmosphere used in performing step S4 includes one of carbon dioxide and water vapor. Specifically, during the activation and pore formation process, selective etching of the carbon microspheres is carried out through a controllable gas-solid oxidation reaction, thereby improving the porosity and the uniformity of pore distribution. In addition, by performing cyclic pore formation in the active atmosphere, a multi-stage and multi-scale pore system can be constructed in the carbon microspheres. The micropores formed in multiple pore formation steps can effectively increase the porosity of the porous carbon, while avoiding structural damage to the porous carbon caused by continuous pore formation.

[0063] In some embodiments, the number of pore formation cycles in performing step S4 is 2 to 5 times. In fact, during each cyclic pore formation process, it is continuously processed for 10 min - 30 min, and the total duration of cyclic pore formation is controlled to be 1 h - 2 h. Specifically, the pressure of the active atmosphere in each cycle is independently -100 kPa to 10 kPa.

[0064] In fact, the reducing atmosphere used in step S5 includes a reducing gas and an inert carrier gas, and the reducing gas includes hydrogen, and the hydrogen concentration in the reducing atmosphere is 10% - 100%. Specifically, during the reduction process, the flow rate of the reducing atmosphere is 30 mL / min - 100 mL / min, and the porous microspheres are reductively treated in the reducing atmosphere for 1 h - 3 h so that the residual lithium in them is reduced to lithium nanoparticles, thereby realizing the pre-lithiation of the porous carbon material.

[0065] Example 1

[0066] This Example 1 provides a method for preparing spherical porous carbon, including the following steps:

[0067] S1. Stir and dissolve lithium sulfate and boric acid in ethanol to obtain a mixed solution, and stir and dissolve phenolic resin powder in an ethanol aqueous solution (volume ratio of ethanol to water is 20:1) to obtain a phenolic solution; mix the mixed solution and the phenolic solution to prepare a phenolic resin solution (phenolic resin content is 0.3 g / mL, lithium sulfate concentration is 0.2 mol / L, boric acid concentration is 0.1 mol / L), load the phenolic resin solution into a spray dryer, set the temperature in the nozzle chamber to 180°C and the humidity to 85% for spray drying, and then collect the resin microspheres;

[0068] S2. Place the resin microspheres in an atmosphere furnace. In an air atmosphere of 0.1 MPa, the atmosphere furnace is heated at a rate of 10 °C / min to 200 °C and then held at a constant temperature for 3 h to obtain carbon microspheres.

[0069] S3. Place the carbon microspheres in a graphite boat and place it in a tube furnace. After purging the tube furnace with argon, the tube furnace is heated at a rate of 10 °C / min to 1100 °C in an argon atmosphere of -1 kPa and held at a constant temperature for 5 h to obtain carbon microspheres.

[0070] S4. After the carbon microspheres in S3 are cooled to 900 °C in the tube furnace, carbon dioxide gas is introduced until the internal pressure reaches 0.1 MPa, and then the gas supply is stopped. After holding for 20 min for pore formation, carbon dioxide gas is introduced again for cyclic pore formation treatment 3 times, with a total pore formation treatment time of 60 min. After pore formation, porous microspheres are obtained.

[0071] S5. After the porous microspheres in S4 are cooled to 500 °C in the tube furnace and held at a constant temperature, a hydrogen-argon mixture (volume ratio 1:1) is introduced at a flow rate of 50 mL / min to reduce the porous microspheres for 2 h, and then cooled to room temperature in the furnace to obtain spherical porous carbon.

[0072] Example 2

[0073] This Example 2 provides a method for preparing spherical porous carbon. The difference from Example 1 is that in step S1, hexamethylenetetramine is pre-added to the phenolic resin solution, and the mass ratio of phenolic resin to hexamethylenetetramine is adjusted to 10:2, and the activation gas is water vapor.

[0074] Comparative Example 1

[0075] This Comparative Example 1 provides a method for preparing spherical porous carbon. The difference from Example 2 is that boric acid is not added in step S1.

[0076] Comparative Example 2

[0077] This Comparative Example 2 provides a method for preparing spherical porous carbon. The difference from Example 2 is that lithium sulfate is not added in step S1.

[0078] Comparative Example 3

[0079] This Comparative Example 3 provides a method for preparing spherical porous carbon. The difference from Example 2 is that a single activation pore formation is carried out for 60 min in step S4.

[0080] Comparative Example 4

[0081] Comparative Example 4 provides a method for preparing spherical porous carbon, which is different from Example 2 in that step S5 is not carried out, and spherical porous carbon is obtained in step S4.

[0082] Structural Characterization

[0083] The spherical porous carbon obtained in Example 1 was characterized by scanning electron microscopy as Figure 2 shown. It can be seen from Figure 2 that the spherical porous carbon prepared by the present invention has a high sphericity.

[0084] The spherical porous carbon was prepared into a silicon-carbon negative electrode material through a chemical vapor deposition process and assembled into a silicon-carbon negative electrode material. Using a lithium sheet as the counter electrode, after assembling into a lithium-ion battery, the first efficiency, capacity, and cycling performance were detected, as shown in Table 2 below.

[0085] Table 2 Summary of Electrochemical Performance of Silicon-Carbon Negative Electrode Materials

[0086] Initial Coulombic efficiency % Initial reversible capacity mAh / g Capacity retention rate after 100 cycles at 0.5C / 0.5C Example 1 94.2 1792.5 86.3% Example 2 93.7 1786.9 84.5% Comparative Example 1 93.6 1801.1 80.7% Comparative Example 2 90.1 1735.6 87.6% Comparative Example 3 92.9 1795.8 71.4% Comparative Example 4 89.8 1711.4 84.1%

[0087] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A method for preparing spherical porous carbon, characterized in that, Including: After stirring and dissolving a crosslinking agent and a catalyst in a phenolic resin solution, it is then stirred and mixed with a mixed solution in which a lithium compound and a boron compound are dissolved to obtain a phenolic resin solution in which the lithium compound and the boron compound are dissolved; The phenolic resin solution in which the lithium compound and the boron compound are dissolved is spray-dried to obtain resin microspheres; the resin microspheres are pre-oxidized at 150°C - 300°C to obtain carbon sphere precursors; the carbon sphere precursors are carbonized in an inert atmosphere at 1000°C - 1200°C to obtain carbon microspheres; the carbon microspheres are subjected to cyclic activation to form pores in an active atmosphere at 800°C - 1000°C to obtain porous microspheres; the porous microspheres are reduced in a reducing atmosphere at 400°C - 600°C to obtain spherical porous carbon, the reducing atmosphere includes a reducing gas and an inert carrier gas, and the reducing gas includes hydrogen.

2. The preparation method according to claim 1, characterized in that, The lithium compound includes one of lithium sulfate, lithium nitrate, lithium carbonate, and lithium oxide; and / or, the boron compound includes one of boric acid, boron trioxide, trimethylboron, and sodium tetraborate; and / or, the concentration of phenolic resin in the phenolic resin solution is 0.1 g / mL - 0.5 g / mL; and / or, the concentration of the lithium compound in the phenolic resin solution is 0.1 mol / L - 0.5 mol / L; and / or, the concentration of the boron compound in the phenolic resin is 0.05 mol / L - 0.3 mol / L; and / or, spray drying is carried out at 160°C - 200°C; and / or, spray drying is carried out at a humidity of 80% - 90%; and / or, the particle size of the resin microspheres is 5 μm - 50 μm.

3. The preparation method according to claim 1, characterized in that, The crosslinking agent includes one of formaldehyde, glyoxal, benzaldehyde, and hexamethylenetetramine; and / or, the catalyst includes one of sodium hydroxide and potassium hydroxide; and / or, the mass ratio of phenolic resin to the crosslinking agent in the phenolic resin solution is 10:(1 - 2); and / or, the mass ratio of phenolic resin to the catalyst in the phenolic resin is 10:(6 - 8); and / or, the solvent of the phenolic resin solution includes a good solvent and a non-solvent, the good solvent includes one of ethanol, acetone, dimethylacetamide, and N,N-dimethylformamide, and the non-solvent includes one of water, carbon tetrachloride, and ethyl silicate.

4. The preparation method according to claim 1, wherein, Pre-oxidation is carried out in an oxygen-containing atmosphere at 150°C - 300°C, and the oxygen concentration in the oxygen-containing atmosphere is 10% - 50%; and / or, pre-oxidation is carried out at 150°C - 300°C for 2 h - 4 h; and / or, the resin microspheres are heated to 150°C - 300°C at a rate of 1°C / min - 20°C / min; and / or, pre-oxidation is carried out at 150°C - 300°C and 0.08 - 0.15 MPa; and / or, isothermal pre-oxidation is carried out within 150°C - 300°C.

5. The preparation method according to claim 1, wherein The inert atmosphere includes one of nitrogen, helium, neon, and argon; and / or, carbonization treatment is carried out at 1000°C - 1200°C for 3 h - 6 h; and / or, carbonization treatment is carried out in an inert atmosphere of -1 kPa to 1 kPa; and / or, isothermal carbonization treatment is carried out at 1000°C - 1200°C; and / or, the carbon sphere precursors are heated at a rate of 1°C / min - 20°C / min.

6. The preparation method according to claim 1, characterized in that, The active atmosphere includes one of carbon dioxide and water vapor; and / or, the number of cycles is 2 to 5 times; and / or, in each cycle, the carbon microspheres are activated to form pores for 10 min to 30 min; and / or, in each cycle, the pressure of the active atmosphere is independently -100 kPa to 10 kPa; and / or, the total duration of cyclic pore formation is 1 h to 2 h.

7. The preparation method according to claim 1, wherein, The concentration of the reducing gas in the reducing atmosphere is 10% to 100%; and / or, the flow rate of the reducing atmosphere is 30 mL / min to 100 mL / min; and / or, the porous microspheres are reductively treated for 1 h to 3 h.

8. A spherical porous carbon prepared by the preparation method according to any one of claims 1 to 7.

9. Application of a spherical porous carbon prepared by the preparation method according to any one of claims 1 to 7 in a lithium-ion battery.

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