Spherical porous carbon as well as preparation method and application thereof

Abstract

The invention provides spherical porous carbon as well as a preparation method and application thereof, and relates to the technical field of porous carbon materials. The preparation method provided by the invention comprises the following steps: carrying out spray drying on a phenolic resin solution in which lithiates and borides are dissolved to obtain resin microspheres; pre-oxidizing the resin microspheres at the temperature of 150-300 DEG C to obtain a carbon sphere precursor; carbonizing the carbon sphere precursor in an inert atmosphere at the temperature of 1000-1200 DEG C to obtain carbon microspheres; performing cyclic activation and pore forming on the carbon microspheres in an active atmosphere of 800-1000 DEG C to obtain porous microspheres; and reducing the porous microspheres in a reducing atmosphere of 400-600 DEG C to obtain the spherical porous carbon. The spherical porous carbon material with developed micropores and high specific surface area can be prepared, meanwhile, the coulombic efficiency is high, the conductivity is good, the used preparation method is simple and efficient, and large-scale industrial production is facilitated.

Description

Technical Field

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

[0002] Porous carbon materials have been widely used in environmental governance, catalysis, energy storage and other fields due to their large specific surface area, high chemical stability and adjustable pore size. In the field of lithium-ion batteries, the well-developed microporous structure on the surface of multi-carbon materials can accommodate nano-scale silicon particles, alleviate their volume expansion during the charging and discharging process, and significantly improve the electrochemical performance of silicon-carbon negative electrode materials. Spherical porous carbon has become the focus of research due to its excellent isotropy and other characteristics.

[0003] At present, the main pore-forming methods used in the preparation of spherical porous carbon are alkaline etching, water vapor activation and carbon dioxide activation. Among them, the alkaline 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 complicated, which increases the production cost; the reaction rate of the water vapor activation method is lower than that of the alkaline etching method, but it is also faster, tends to form micropores and mesopores, and hydrogen is generated during the activation reaction, which has certain production safety issues; 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 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, hard carbon materials are difficult to graphitize and have many defects, resulting in low first coulomb efficiency and poor conductivity. Therefore, it is urgent 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 and its preparation method and application, which can produce a spherical porous carbon material with developed micropores and high specific surface area, and at the same time has 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, the present invention provides a method for preparing spherical porous carbon, comprising: spray-drying a phenolic resin solution containing a lithium compound and a boride to obtain resin microspheres; pre-oxidizing the resin microspheres at 150°C-300°C to obtain a carbon sphere precursor; carbonizing the carbon sphere precursor at 1000°C-1200°C in an inert atmosphere to obtain carbon microspheres; cyclically activating the carbon microspheres at 800°C-1000°C in an active atmosphere to form porous microspheres; and reducing the porous microspheres at 400°C-600°C in a reducing atmosphere 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 boride includes one of boric acid, boron trioxide, trimethyl boron and sodium tetraborate.

[0008] Optionally, the concentration of 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 boride 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, the solution is stirred and mixed with the mixed solution containing the lithium compound and the boride to obtain the phenolic resin solution containing the lithium compound and the boride.

[0015] Optionally, the cross-linking 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 cross-linking agent is 10:(1-2).

[0018] Optionally, the mass ratio of the phenolic resin to the catalyst in the phenolic resin 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 performed in an oxygen-containing atmosphere at 150° C.-300° C., wherein the oxygen concentration in the oxygen-containing atmosphere is 10%-50%.

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

[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, the carbonization treatment is carried out 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-formed 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 cyclic pore creation is 1h-2h.

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

[0036] Optionally, the concentration of 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 A flowchart of a method for preparing spherical porous carbon provided by the present invention;

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

[0043] In order to make the purpose, 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. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0044] See also Figure 1 The present invention provides a method for preparing spherical porous carbon, comprising: S1, spray drying a phenolic resin solution containing a lithium compound and a boride to obtain resin microspheres; S2, pre-oxidizing the resin microspheres at 150°C-300°C to obtain carbon sphere precursors; S3, carbonizing the carbon sphere precursor at 1000° C.-1200° C. in an inert atmosphere to obtain carbon microspheres; S4, cyclically activating the carbon microspheres in an active atmosphere at 800°C-1000°C to form porous microspheres; S5. The porous microspheres are reduced in a reducing atmosphere at 400° C.-600° C. to obtain spherical porous carbon.

[0045] 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 improve the specific surface area of ​​the spherical porous carbon, which is conducive 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 conducive to large-scale industrial production.

[0046] In fact, when executing step S1, the lithium compound and the boride are dissolved in the phenolic resin solution in advance, which is conducive to the uniform dispersion of lithium ions, boron ions and phenolic resin. At the same time, the template effect of lithium ions can be used to form resin microspheres of uniform size with the phenolic resin during the spray drying process, and the resin microspheres are also doped with lithium and boron elements.

[0047] In some embodiments, when executing step S1, it includes: stirring and dissolving the cross-linking agent and the catalyst in the phenolic resin solution, and then stirring and mixing with the mixed solution in which the lithium compound and the boride are dissolved, to obtain a phenolic resin solution in which the lithium compound and the boride are dissolved. In fact, by adding the cross-linking agent and the 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 the curing structure of the phenolic resin can be optimized to improve the structural strength of the carbon microspheres, which is beneficial for the porous carbon to maintain a spherical shape during the preparation process.

[0048] In some embodiments, the crosslinking agent used includes one of formaldehyde, glyoxal, benzaldehyde, and hexamethylenetetramine. In fact, 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 increase the crosslinking density of the resin microspheres to avoid structural collapse during the carbonization process.

[0049] In some embodiments, the catalyst used includes one of sodium hydroxide and potassium hydroxide. In fact, after adding the catalyst, the polycondensation reaction of the phenolic resin is adjusted to promote the branching and cross-linking 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 in the subsequent carbonization process and form additional pores as a template agent, further increasing the specific surface area of ​​the porous carbon.

[0050] In some embodiments, the lithium compound used includes one of lithium sulfate, lithium nitrate, lithium carbonate, and lithium oxide, and the boride used includes one of boric acid, boron trioxide, trimethyl boron, and sodium tetraborate. In fact, by pre-dissolving the lithium compound and the boride to form a mixed solution, the distribution uniformity of the lithium compound and the boride can be effectively improved. At the same time, the mixed solution is used to perform liquid-liquid mixing with the phenolic resin solution, which is conducive to improving the mixing uniformity of multiple raw materials, thereby improving the consistency after the resin microspheres are made.

[0051] In some embodiments, the lithium compound and the boride may be pre-dissolved in water, ethanol, dimethyl sulfoxide, dimethyl carbonate and other commonly used solvents in the art to prepare a mixed solution. Specifically, after the phenolic resin solution and the mixed solution are uniformly mixed, the mass ratio of the phenolic resin, the cross-linking agent and the catalyst in the obtained solution is 10:(1-2):(6-8). In addition, the solvent in the phenolic resin solution includes a good solvent and a non-solvent, and 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.

[0052] In some embodiments, the concentration of the phenolic resin used in step S1 is 0.1 g / mL-0.5 g / mL, and 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 boride dissolved is 0.05 mol / L-0.3 mol / L. Specifically, when performing step S1, the phenolic resin solution containing the lithium compound and the boride can be spray dried at 160°C-200°C and 80%-90% humidity. In addition, the particle size of the resin microspheres obtained after performing step S1 is 5 μm-50 μm.

[0053] In some embodiments, when executing step S2, the resin microspheres are subjected to a constant temperature pre-oxidation treatment in an oxygen-containing atmosphere at 150°C-300°C and 0.08-0.15MPa for 2h-4h. In fact, the resin microspheres can be placed in an atmosphere furnace in advance, and after the atmosphere furnace is gas-displaced with an oxygen-containing atmosphere, 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%, and further, the oxygen-containing atmosphere can be clean air.

[0054] In fact, in step S2, by performing a pre-oxidation treatment in an oxygen-containing atmosphere, the oxidative cross-linking of the phenolic resin molecular chain can be promoted, and the structural stability of the lithium, boron and other elements doped in the resin microspheres can be improved, which is conducive to forming a stable pore structure in 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 direct carbonization of the resin microspheres.

[0055] In some embodiments, the inert atmosphere used when performing step S3 includes one of nitrogen, helium, neon, and argon. In fact, by performing carbonization in an inert atmosphere, oxygen can be isolated from the oxidation reaction of the carbon sphere precursor, and the pyrolysis reaction can be regulated, thereby promoting the undecomposed organic chains in the carbon sphere precursor to form a stable carbon skeleton. In addition, after carbonization treatment at 1000°C-1200°C for 3h-6h, it is beneficial for the carbon layer to rearrange and graphitize, thereby effectively improving the conductivity of the porous carbon material.

[0056] In some embodiments, when performing step S3, the carbonized 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 carbonized in an inert atmosphere of -1kPa~1kPa. In fact, during the carbonization process, the boron added in step S1 can form a composite structure with carbon and embed into the carbon layer, thereby effectively inhibiting the high-temperature shrinkage of the carbon skeleton and effectively maintaining the spherical structure of the porous carbon.

[0057] In fact, the active atmosphere used in executing step S4 includes one of carbon dioxide and water vapor. Specifically, the carbon microspheres are selectively etched by a controllable gas-solid oxidation reaction during the activation pore formation process, thereby improving the porosity and pore distribution uniformity. In addition, by performing cyclic pore formation in an active atmosphere, a multi-stage and multi-scale pore system can be constructed in the carbon microspheres. The micropores formed by multiple pore formation links can effectively improve the porosity of the porous carbon, while avoiding the structural damage to the porous carbon caused by continuous pore formation.

[0058] In some embodiments, the number of pore-forming cycles in step S4 is 2 to 5. In practice, each pore-forming cycle lasts for 10 to 30 minutes, and the total pore-forming cycle duration is controlled to be 1 to 2 hours. Specifically, the pressure of the active atmosphere in each cycle is independently -100 kPa to 10 kPa.

[0059] 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 concentration of hydrogen in the reducing atmosphere is 10%-100%. Specifically, the flow rate of the reducing atmosphere during the reduction process is 30mL / min-100mL / min, and the porous microspheres are reduced in the reducing atmosphere for 1h-3h so that the residual lithium therein is reduced to lithium nanoparticles, thereby achieving pre-lithium embedding of the porous carbon material.

[0060] Example 1

[0061] This embodiment 1 provides a method for preparing spherical porous carbon, comprising the following steps: S1. Stir and dissolve lithium sulfate and boric acid in ethanol to prepare a mixed solution, stir and dissolve phenolic resin powder in an ethanol aqueous solution (ethanol to water volume ratio 20:1) to prepare a phenolic solution; mix the mixed solution with the phenolic solution to prepare a phenolic resin solution (phenolic resin content 0.3 g / mL, lithium sulfate concentration 0.2 mol / L, boric acid concentration 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%, spray dry, and then collect the resin microspheres; S2, placing the resin microspheres in an atmosphere furnace, heating the atmosphere furnace to 200°C at a rate of 10°C / min in an air atmosphere of 0.1MPa, and then treating the mixture at a constant temperature for 3h to obtain carbon microspheres; S3, placing the carbon microspheres in a graphite boat and placing it in a tube furnace, replacing the gas in the tube furnace with argon, heating the tube furnace to 1100° C. at a rate of 10° C. / min under an argon atmosphere of -1 kPa, and treating the carbon microspheres at a constant temperature for 5 hours; S4, the carbon microspheres in S3 were cooled to 900°C in a tubular furnace, and then carbon dioxide gas was introduced until the internal pressure reached 0.1 MPa and then the ventilation was stopped. After pore formation at a constant temperature for 20 minutes, carbon dioxide gas was introduced again for 3 cycles of pore formation, and the pore formation treatment lasted for 60 minutes in total. After the pore formation was completed, porous microspheres were obtained; S5. The porous microspheres in S4 are cooled to 500°C in a tubular furnace and then kept at a constant temperature. A hydrogen-argon mixed gas (volume ratio of 1:1) is introduced at a flow rate of 50 mL / min to reduce the porous microspheres for 2 h. The porous microspheres are then cooled to room temperature to obtain spherical porous carbon.

[0062] Example 2

[0063] This embodiment 2 provides a method for preparing spherical porous carbon, which is different from embodiment 1 in 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.

[0064] Comparative Example 1

[0065] This comparative example 1 provides a method for preparing spherical porous carbon, which is different from that of example 2 in that boric acid is not added in step S1.

[0066] Comparative Example 2

[0067] This comparative example 2 provides a method for preparing spherical porous carbon, which is different from that of example 2 in that lithium sulfate is not added in step S1.

[0068] Comparative Example 3

[0069] This comparative example 3 provides a method for preparing spherical porous carbon, which is different from that of example 2 in that a single activation and pore formation is performed for 60 minutes in step S4.

[0070] Comparative Example 4

[0071] This comparative example 4 provides a method for preparing spherical porous carbon, which is different from that of Example 2 in that step S5 is not performed, and spherical porous carbon is prepared in step S4.

[0072] Structural characterization

[0073] The spherical porous carbon prepared in Example 1 was characterized by scanning electron microscopy. Figure 2 As shown, from Figure 2 It can be seen that the spherical porous carbon prepared by the present invention has a higher sphericity.

[0074] The spherical porous carbon was prepared as a silicon-carbon negative electrode material through a vapor deposition process and assembled into a silicon-carbon negative electrode material. A lithium sheet was used as a counter electrode. After being assembled into a lithium-ion battery, the first efficiency, capacity, and cycle performance were tested, as shown in Table 2 below.

[0075] Table 2 Summary of electrochemical properties of silicon-carbon negative electrode materials

[0076] First coulombic efficiency% First reversible capacity mAh / g 0.5C / 0.5C cycle 100 cycles capacity retention rate 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%

[0077] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for preparing spherical porous carbon, characterized in that: include: The phenolic resin solution containing the lithium compound and the boride is spray-dried to obtain resin microspheres; The resin microspheres are pre-oxidized at 150°C-300°C to obtain a carbon sphere precursor; the carbon sphere precursor is carbonized at 1000°C-1200°C in an inert atmosphere to obtain carbon microspheres; the carbon microspheres are cyclically activated at 800°C-1000°C in an active atmosphere to form porous microspheres; and the porous microspheres are reduced at 400°C-600°C in a reducing atmosphere to obtain spherical porous carbon.

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 boride includes one of boric acid, boron trioxide, trimethyl boron, and sodium tetraborate; and / or, the concentration of phenolic resin in the phenolic resin solution is 0.1g / mL-0.5g / mL; and / or, the concentration of the lithium compound in the phenolic resin solution is 0.1mol / L-0.5mol / L; and / or, the concentration of the boride in the phenolic resin is 0.05mol / L-0.3mol / L; and / or, spray drying is performed at 160°C-200°C; and / or, spray drying is performed at a humidity of 80%-90%; and / or, the particle size of the resin microspheres is 5μm-50μm.

3. The preparation method according to claim 1, characterized in that: After the crosslinking agent and the catalyst are stirred and dissolved in the phenolic resin solution, the solution is stirred and mixed with the mixed solution containing the lithium compound and the boride to obtain the phenolic resin solution containing the lithium compound and the boride.

4. The preparation method according to claim 3, characterized in that: The cross-linking 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 the phenolic resin in the phenolic resin solution to the cross-linking agent is 10:(1-2); and / or, the mass ratio of the phenolic resin in the phenolic resin to the catalyst 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.

5. The preparation method according to claim 1, characterized in that: Pre-oxidation is performed at 150°C-300°C in an oxygen-containing atmosphere, wherein the oxygen concentration in the oxygen-containing atmosphere is 10%-50%; and / or, pre-oxidation is performed at 150°C-300°C for 2h-4h; 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 performed at 150°C-300°C and 0.08-0.15MPa; and / or, constant-temperature pre-oxidation is performed within 150°C-300°C.

6. The preparation method according to claim 1, characterized in that: The inert atmosphere includes one of nitrogen, helium, neon and argon; and / or, carbonization treatment is performed at 1000°C-1200°C for 3h-6h; and / or, carbonization treatment is performed in an inert atmosphere of -1kPa~1kPa; and / or, constant temperature carbonization treatment is performed at 1000°C-1200°C; and / or, the carbon sphere precursor is heated at a rate of 1°C / min-20°C / min.

7. 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 the carbon microspheres are activated and pore-forming for 10 min to 30 min in each cycle; and / or the pressure of the active atmosphere in each cycle is independently -100 kPa to 10 kPa; and / or the total duration of the cyclic pore-forming is 1 h to 2 h.

8. The preparation method according to claim 1, characterized in that: The reducing atmosphere includes a reducing gas and an inert carrier gas, the reducing gas includes hydrogen; and / or the concentration of the reducing gas in the reducing atmosphere is 10%-100%; and / or the flow rate of the reducing atmosphere is 30mL / min-100mL / min; and / or the porous microspheres are subjected to reduction treatment for 1h-3h.

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

10. Use of the spherical porous carbon prepared by the preparation method according to any one of claims 1 to 8 in lithium ion batteries.

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