Porous carbon material, preparation method thereof and silicon-carbon negative electrode material containing porous carbon material

Abstract

The invention provides a porous carbon material, a preparation method thereof and a silicon-carbon negative electrode material containing the porous carbon material. The preparation method of the porous carbon material comprises the following steps: heating and carbonizing an organic carbon source in a protective atmosphere, keeping a certain vacuum degree at least when the temperature reaches the pyrolysis temperature of the organic carbon source in the carbonization process, and then performing or not performing activation to obtain the porous carbon material. The silicon-carbon negative electrode material comprises the porous carbon material and silicon coating and filling the surface and holes of the porous carbon material. According to the preparation method provided by the invention, the content of spherical pores and macropores in the porous carbon material is reduced, the content of columnar pores and cracked pores is increased, the pressure resistance of the porous carbon material and the silicon-carbon negative electrode material is improved, collapse of the silicon-carbon negative electrode material in the process of preparing an electrode by rolling is reduced, and the service life of the silicon-carbon negative electrode material is prolonged. And the silicon-carbon negative electrode material can maintain good electrochemical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative electrode materials for lithium - ion batteries, and particularly relates to a porous carbon material, a preparation method thereof, and a silicon - carbon negative electrode material containing the same. Background Art

[0002] With the rapid development of science and technology, various electronic devices and electric vehicles, etc. have put forward higher and higher requirements for the energy storage performance of lithium - ion batteries. For the negative electrode materials of lithium - ion batteries, the currently widely used graphite - based materials can no longer meet these requirements. Silicon - carbon negative electrode materials show great application potential in the new generation of negative electrode materials for lithium - ion batteries due to their high lithium storage capacity.

[0003] Currently, the types of silicon - carbon negative electrode materials that are widely studied and applied are mainly two categories. One is to use pitch - based carbon materials to coat silicon powder twice, and the other is to deposit elemental silicon on the surface of porous carbon materials by chemical vapor deposition. The latter has received extensive attention because of its many advantages in preparation processes and electrochemical properties, and commercial products have emerged. The elemental silicon - deposited porous carbon materials currently used for the negative electrodes of lithium batteries show high specific capacity, cycle stability, and first - cycle Coulomb efficiency, so they show broad market prospects in the field of power demand.

[0004] However, during the rolling process of preparing the negative electrode sheet of such silicon - carbon negative electrode materials, it is easy to collapse, resulting in volume compression of the materials on a macroscopic scale. On the one hand, this will reduce the stability of the carbon - based skeleton structure, and on the other hand, it will also cause the silicon deposition layer to break, thereby leading to a decline in its electrochemical performance. Therefore, it is necessary to improve the preparation process of porous carbon to enhance the compressive strength of porous carbon, so as to meet the strength requirements of silicon - carbon negative electrode materials during the electrode preparation process. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a porous carbon material, a preparation method thereof, and a silicon - carbon negative electrode material containing the same. This preparation method reduces the content of spherical pores and large pores in the porous carbon material, increases the content of columnar pores and crack pores, improves the compressive strength of the porous carbon material and the silicon - carbon negative electrode material, reduces the collapse of the silicon - carbon negative electrode material during the rolling process of preparing the electrode, and enables the silicon - carbon negative electrode material to maintain good electrochemical performance.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a preparation method of a porous carbon material, and the preparation method includes the following steps:

[0008] The organic carbon source is heated and carbonized in a protective atmosphere. During the carbonization process, a certain degree of vacuum is maintained at least in the stage when the temperature reaches the pyrolysis temperature of the organic carbon source, and then activation may or may not be carried out to obtain the porous carbon material.

[0009] Those skilled in the art can easily understand that since the organic carbon source in the present invention is used to prepare the porous carbon material, it should be able to form a porous carbon structure after carbonization. Those skilled in the art can select materials suitable as the organic carbon source according to the conventional technical knowledge in the art. The activation can increase the pore size of the porous carbon material and improve the specific surface area. Usually, when preparing a porous carbon material with a relatively high specific surface area (for example, above 1500 m 2 / g), activation is required. The pyrolysis temperature range of the organic carbon source can be determined according to the thermogravimetric (TG) curve and derivative thermogravimetry (DTG) curve of the organic carbon source. In the present invention, the temperature between the two inflection points of the TG curve is used as the pyrolysis temperature range.

[0010] The present invention finds through research that during the carbonization and activation of the organic carbon source, the generated gas is prone to accumulate, inevitably generating a large number of spherical pores. The spherical pore shape itself has poor pressure-bearing capacity, and the size distribution of these spherical pores is mostly in the macropore range, and there will still be a large amount of space after silicon deposition. Therefore, it is easy to cause the collapse of the silicon-carbon negative electrode material during the rolling process of preparing the electrode.

[0011] In the present invention, during the carbonization process of the organic carbon source, a certain degree of vacuum is maintained in an appropriate temperature zone, avoiding the generation of gas bubbles to form spherical pores, increasing the content of columnar pores and crack pores (flat elliptical shape). The columnar pores and crack pores have stronger pressure-bearing capacity, thereby improving the compressive capacity of the porous carbon material and the silicon-carbon negative electrode material, reducing the collapse of the silicon-carbon negative electrode material during the rolling process of preparing the electrode, and enabling the silicon-carbon negative electrode material to maintain good electrochemical performance.

[0012] In some embodiments of the present invention, the degree of vacuum is 0.01 - 50 kPa; for example, it can be 0.01 kPa, 0.03 kPa, 0.05 kPa, 0.08 kPa, 0.1 kPa, 0.3 kPa, 0.5 kPa, 0.8 kPa, 1 kPa, 2 kPa, 3 kPa, 5 kPa, 8 kPa, 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa or 50 kPa, etc.

[0013] In the present invention, the degree of vacuum is the ambient air pressure of the organic carbon source during the carbonization process. The smaller the degree of vacuum, the more conducive it is to eliminating gas bubbles and reducing the generation of spherical pores.

[0014] In some embodiments of the present invention, the heating rate during the carbonization process is 1-10 °C / min; for example, it can be 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min, etc.

[0015] In some embodiments of the present invention, the organic carbon source is selected from one or more of polymer materials, biomass materials, coal-based materials and pitch-based materials.

[0016] In the present invention, the polymer materials include, but are not limited to, one or more of phenolic resin, melamine resin, polycarbonate, polyaniline, polyfurfuryl alcohol, covalent organic frameworks (COFs).

[0017] In the present invention, the biomass materials include, but are not limited to, one or more of starch, seed husks, dry stems of herbaceous or woody plants, sugars.

[0018] In some embodiments of the present invention, the carbonization method is a one-step carbonization method, and the temperature of the one-step carbonization method is 800-1800 °C, for example, it can be 800 °C, 820 °C, 850 °C, 880 °C, 900 °C, 920 °C, 950 °C, 980 °C, 1000 °C, 1100 °C, 1200 °C, 1300 °C, 1500 °C, 1600 °C or 1800 °C, etc.; the heat preservation time is 1-4 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, etc.

[0019] In some embodiments of the present invention, the carbonization method is a two-step carbonization method, and the two-step carbonization method includes pre-carbonization and secondary carbonization carried out in sequence;

[0020] The temperature of the pre-carbonization is 500-800 °C, for example, it can be 500 °C, 520 °C, 530 °C, 550 °C, 560 °C, 580 °C, 600 °C, 620 °C, 630 °C, 650 °C, 660 °C, 680 °C, 700 °C, 720 °C, 730 °C, 750 °C, 760 °C, 780 °C or 800 °C, etc.; the heat preservation time is 2-4 h, for example, it can be 2 h, 2.2 h, 2.3 h, 2.5 h, 2.6 h, 2.8 h, 3 h, 3.2 h, 3.3 h, 3.5 h, 3.6 h, 3.8 h or 4 h, etc.;

[0021] The temperature of the secondary carbonization is 900 - 1800 °C, for example, it can be 900 °C, 920 °C, 950 °C, 980 °C, 1000 °C, 1100 °C, 1200 °C, 1300 °C, 1500 °C, 1600 °C or 1800 °C, etc.; the heat preservation time is 1 - 4 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, etc.

[0022] It should be noted that in the present invention, the heat preservation time in the carbonization step refers to the time when the temperature reaches the preset value and remains constant, and does not include the time in the heating stage.

[0023] In some embodiments of the present invention, the activation method is a physical activation method or a chemical activation method.

[0024] The physical activation method includes: heat-treating the carbonized product in an atmosphere of a physical activator.

[0025] The chemical activation method includes: mixing the carbonized product with a chemical activator and performing heat treatment in a protective atmosphere.

[0026] In some embodiments of the present invention, the physical activator is selected from one or more of oxygen, carbon dioxide, water vapor and air.

[0027] In some embodiments of the present invention, the heat treatment temperature in the physical activation method is 500 - 1200 °C, for example, it can be 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1100 °C or 1200 °C, etc.; the time is 1 - 30 h, for example, it can be 1 h, 2 h, 3 h, 5 h, 6 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, 22 h, 25 h, 28 h or 30 h, etc.

[0028] In some embodiments of the present invention, the chemical activator is selected from one or more of hydrochloric acid, phosphoric acid, sodium hydroxide and potassium hydroxide.

[0029] In some embodiments of the present invention, the heat treatment temperature in the chemical activation method is 350 - 1100 °C, for example, it can be 350 °C, 380 °C, 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C or 1100 °C, etc.; the time is 1 - 36 h, for example, it can be 1 h, 2 h, 3 h, 5 h, 6 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, 22 h, 25 h, 28 h, 30 h, 32 h or 36 h, etc.

[0030] In some embodiments of the present invention, the preparation method further includes a post-treatment step, and the post-treatment step includes: after the carbonization or activation, infiltrating the obtained product with a soluble carbon source solution, and after drying or without drying, performing heat carbonization in a protective atmosphere.

[0031] It should be noted that the above "after the carbonization or activation" means: when the preparation method of the porous carbon material does not include activation, after carbonization; when the preparation method of the porous carbon material includes activation, after activation.

[0032] In the present invention, by infiltrating the porous carbon with a soluble carbon source solution and performing carbonization again, a relatively continuous and regular carbon layer structure can be formed on the inner walls of mesopores and macropores, improving the order and continuity of the pore walls, enhancing the strength of the pore walls, and at the same time reducing the sizes of mesopores and macropores, thereby further improving the compressive capacity of the porous carbon material framework.

[0033] In some embodiments of the present invention, the soluble carbon source is selected from one or more of chitosan, styrene, pyridine-soluble fraction of toluene-insoluble fraction of pitch, and quinoline-soluble fraction of toluene-insoluble fraction of pitch.

[0034] Among them, the solvent of chitosan can be water. Although styrene is a liquid, its viscosity is too high, so it also needs to be diluted with a solvent when used, and its solvent can be ethanol. The pyridine-soluble fraction of toluene-insoluble fraction of pitch refers to the component in pitch that is insoluble in toluene and soluble in pyridine, and its solvent can be pyridine. The quinoline-soluble fraction of toluene-insoluble fraction of pitch refers to the component in pitch that is insoluble in toluene and soluble in quinoline, and its solvent can be quinoline.

[0035] In the present invention, the type of the soluble carbon source needs to be selected according to the pore diameter and pore shape of the infiltrated carbonized product. Generally, when the pore diameter is small, a soluble carbon source with a smaller molecular weight and lower viscosity (such as chitosan, styrene) needs to be selected to facilitate the infiltration of the pore walls; when the pore diameter is large, a soluble carbon source with a larger molecular weight and higher viscosity (such as pyridine-soluble fraction of toluene-insoluble fraction of pitch, quinoline-soluble fraction of toluene-insoluble fraction of pitch) can be selected.

[0036] In some embodiments of the present invention, the concentration of the soluble carbon source solution is 1-20 g / L; for example, it can be 1 g / L, 2 g / L, 3 g / L, 5 g / L, 6 g / L, 8 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L or 20 g / L, etc. If the concentration of the soluble carbon source solution is too small, the amount of carbon layer formed in the pores of the porous carbon material after carbonization is less, and the improvement effect on the compressive capacity of the porous carbon material is weak; if the concentration of the soluble carbon source solution is too large, it is not conducive to fully infiltrating the pore walls of the porous carbon material, and the improvement effect on the compressive capacity of the porous carbon material is also weak.

[0037] In some embodiments of the present invention, the temperature of carbonization in the post-treatment step is 800 - 1000 °C, for example, it can be 800 °C, 820 °C, 830 °C, 850 °C, 860 °C, 880 °C, 900 °C, 920 °C, 930 °C, 950 °C, 960 °C, 980 °C or 1000 °C, etc.; the heat preservation time is 1 - 4 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, etc.

[0038] In some embodiments of the present invention, the specific surface area of the porous carbon material is 100 - 2000 m 2 / g, for example, it can be 100 m 2 / g, 150 m 2 / g, 200 m 2 / g, 250 m 2 / g, 300 m 2 / g, 350 m 2 / g, 400 m 2 / g, 450 m 2 / g, 500 m 2 / g, 600 m 2 / g, 700 m 2 / g, 800 m 2 / g, 900 m 2 / g, 1000 m 2 / g, 1200 m 2 / g, 1300 m 2 / g, 1500 m 2 / g, 1600 m 2 / g, 1800 m 2 / g or 2000 m 2 / g; preferably 700 - 1600 m 2 / g;

[0039] The pore size distribution is 0.7 - 100 nm, and the average pore size is 1 - 5 nm.

[0040] In a second aspect, the present invention provides a porous carbon material prepared by the preparation method described in the first aspect.

[0041] In a third aspect, the present invention provides a silicon-carbon negative electrode material, which includes the porous carbon material described in the second aspect, and silicon coated and filled on the surface and in the pores of the porous carbon material.

[0042] In some embodiments of the present invention, the silicon is deposited on the surface and in the pores of the porous carbon material by chemical vapor deposition.

[0043] Fourthly, the present invention provides a lithium-ion battery, which includes the silicon-carbon anode material as described in the third aspect.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] During the carbonization process of the organic carbon source, by maintaining a certain degree of vacuum in an appropriate temperature range, the present invention reduces the accumulation of gases generated during the carbonization process, decreases the generation of spherical pores and macropores, increases the content of columnar pores and fissure pores, improves the compressive capacity of the porous carbon material and the silicon-carbon anode material, reduces the collapse of the silicon-carbon anode material during the roll-pressing process for preparing the electrode, and enables the silicon-carbon anode material to maintain good electrochemical performance.

[0046] By further post-treating the porous carbon material, the present invention can improve the orderliness and continuity of the pore walls, enhance the strength of the pore walls, and simultaneously reduce the macropore size, thereby further improving the compressive capacity of the porous carbon material and the electrochemical performance of the silicon-carbon anode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a TG curve graph of phenolic resin, polyfurfuryl alcohol, corn starch and medium-temperature coal tar pitch used in the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The technical solutions of the present invention will be further described below in conjunction with the drawings and through specific embodiments. Those skilled in the art should understand that the specific embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0049] Perform TG tests on the organic carbon sources used in the embodiments of the present invention, with a heating rate of 5 °C / min, and determine the pyrolysis temperature range of the organic carbon sources according to the TG curves.

[0050] The test results are as Figure 1 shown, and it is concluded from Figure 1 that the pyrolysis temperature range of the phenolic resin used in Example 1 is 300 - 600 °C; the pyrolysis temperature range of the polyfurfuryl alcohol used in Example 2 is 300 - 500 °C; the pyrolysis temperature range of the corn starch used in Example 3 is 250 - 350 °C; the pyrolysis temperature range of the medium-temperature coal tar pitch used in Example 4 is 200 - 500 °C.

[0051] Example 1

[0052] This example provides a porous carbon material, and its preparation method is as follows:

[0053] 20 g of phenolic resin (purchased from Aladdin) was carbonized under nitrogen protection by heating at a rate of 5 °C / min. When the temperature rose to the range of 300 - 600 °C, a vacuum of about 5 kPa was maintained, and normal pressure was maintained in other temperature ranges. Finally, it was heated to 800 °C, held for 2 h, and then carbon dioxide gas was introduced for activation treatment for 6 h to obtain a primary product. Then, post-treatment was carried out: the primary product was immersed in a 2 g / L aqueous chitosan solution, stirred under negative pressure for 30 min, the sample was taken out and dried to obtain a secondary product; the secondary product was treated at 1400 °C for 1 h to obtain the final product.

[0054] Example 2

[0055] This example provides a porous carbon material, and its preparation method is as follows:

[0056] 20 g of polyfurfuryl alcohol (purchased from ACMEC) was carbonized under nitrogen protection by heating at a rate of 5 °C / min. When the temperature rose to the range of 300 - 500 °C, a vacuum of about 1 kPa was maintained, and normal pressure was maintained in other temperature ranges. Finally, it was heated to 800 °C, held for 4 h to obtain a primary product. Then, post-treatment was carried out: the primary product was immersed in a pyridine solution of 1 g / L of pitch toluene-insoluble pyridine-soluble matter, stirred under negative pressure for 30 min, the sample was taken out and dried to obtain a secondary product; the secondary product was treated at 1500 °C for 1 h to obtain the final product.

[0057] Example 3

[0058] This example provides a porous carbon material, and its preparation method is as follows:

[0059] 20 g of corn starch was carbonized under argon protection by heating at a rate of 10 °C / min. When the temperature rose to the range of 250 - 350 °C, a vacuum of about 50 kPa was maintained, and normal pressure was maintained in other temperature ranges. Finally, it was heated to 1200 °C, held for 2 h, then 4 g of potassium hydroxide was added, and activation treatment was carried out at 600 °C for 4 h to obtain a primary product. Then, post-treatment was carried out: the primary product was immersed in a 2 g / L aqueous chitosan solution, stirred under negative pressure for 30 min, the sample was taken out and dried to obtain a secondary product; the secondary product was treated at 1400 °C for 1 h to obtain the final product.

[0060] Example 4

[0061] This example provides a porous carbon material, and its preparation method is as follows:

[0062] Heat 20 g of medium-temperature coal tar pitch (purchased from Shenhua Research Institute) in air at a rate of 5 °C / min to 260 °C and hold for 1 h (medium-temperature coal tar pitch is soft carbon with a regular molecular arrangement, and it is not easy to form a porous structure with a high specific surface area by direct carbonization treatment. Therefore, it is first heated and cross-linked to become hard carbon).

[0063] Carry out carbonization treatment on the hard-carbonized medium-temperature coal tar pitch by heating at a rate of 1 °C / min under argon protection. When the temperature rises to the range of 200 - 500 °C, maintain a vacuum of about 10 kPa, and maintain normal pressure in other temperature sections. Finally, raise the temperature to 1500 °C, hold for 1 h, and then carry out activation treatment in a carbon dioxide atmosphere at 800 °C for 30 h to obtain the primary product. Then carry out post-treatment: Immerse the primary product in a 2 g / L chitosan aqueous solution, stir under negative pressure for 30 min, take out the sample and dry it to obtain the secondary product; treat the secondary product at 1400 °C for 1 h to obtain the final product.

[0064] Comparative Example 1

[0065] This comparative example provides a porous carbon material, which is different from Example 1 in that normal pressure is maintained during the carbonization process and no post-treatment is carried out.

[0066] Comparative Example 2

[0067] This comparative example provides a porous carbon material, which is different from Example 1 in that normal pressure is maintained during the carbonization process.

[0068] Comparative Example 3

[0069] This comparative example provides a porous carbon material, which is different from Example 2 in that normal pressure is maintained during the carbonization process.

[0070] Comparative Example 4

[0071] This comparative example provides a porous carbon material, which is different from Example 3 in that normal pressure is maintained during the carbonization process.

[0072] Comparative Example 5

[0073] This comparative example provides a porous carbon material, which is different from Example 4 in that normal pressure is maintained during the carbonization process.

[0074] Performance Test

[0075] Mix the obtained product with sodium carboxymethylcellulose in a ratio of 9.5:0.5, use water as the dispersion medium for blending, and uniformly coat it on a 30-μm copper foil by a film coater. After pressing and drying, a porous carbon film with a thickness of about 100 μm is obtained. Test the thickness change of the porous carbon film under different pressures (linear pressure) on a roll pressing tester, and the test results are shown in Table 1 below.

[0076] Table 1

[0077]

[0078] It can be seen from the test results in Table 1 that, compared with the porous carbon material without vacuum treatment during the carbonization process, the thickness change of the porous carbon material prepared in the examples is significantly smaller under different pressures, indicating that the preparation method provided by the present invention can effectively improve the compressive capacity of the porous carbon material and reduce the collapse of the silicon-carbon negative electrode material during the roller pressing process for preparing the electrode, so that the silicon-carbon negative electrode material can maintain good electrochemical performance.

[0079] By comparing the test results of Comparative Example 1 and Comparative Example 2, it can be seen that in addition to maintaining normal pressure during the carbonization process, Comparative Example 1 was not post-treated, and as a result, its compressive capacity further decreased compared to Comparative Example 1, indicating that in the preparation method provided by the present invention, the post-treatment step has the effect of further improving the compressive capacity of the porous carbon material.

[0080] The above are only specific embodiments of the present disclosure, enabling those skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments described herein, but will conform to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a porous carbon material, characterized in that, The preparation method comprises the following steps: Heat and carbonize the organic carbon source in a protective atmosphere. During the carbonization process, maintain a certain vacuum degree at least in the stage when the temperature reaches the pyrolysis temperature of the organic carbon source, and then activate or not activate to obtain the porous carbon material.

2. The preparation method according to claim 1, characterized in that, The vacuum degree is 0.01 - 50 kPa; Preferably, the heating rate during the carbonization process is 1 - 10 °C / min.

3. The preparation method according to claim 1 or 2, characterized in that, The organic carbon source is selected from one or more of polymer materials, biomass materials, coal-based materials, and pitch-based materials; Preferably, the polymer materials are selected from one or more of phenolic resin, melamine resin, polycarbonate, polyaniline, polyfurfuryl alcohol, and covalent organic framework; Preferably, the biomass materials are selected from one or more of starch, seed husk, dry stems of herbaceous or woody plants, and sugars.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The carbonization method is a one-step carbonization method, and the temperature of the one-step carbonization method is 800 - 1800 °C, and the heat preservation time is 1 - 4 h; Alternatively, the carbonization method is a two-step carbonization method, and the two-step carbonization method includes pre-carbonization and secondary carbonization carried out in sequence; The temperature of the pre-carbonization is 500 - 800 °C, and the heat preservation time is 2 - 4 h; The temperature of the secondary carbonization is 900 - 1800 °C, and the heat preservation time is 1 - 4 h.

5. The preparation method according to any one of claims 1 to 3, characterized in that, The activation method is a physical activation method or a chemical activation method; The physical activation method includes: heat-treating the carbonized product in a physical activator atmosphere; The chemical activation method includes: mixing the carbonized product with a chemical activator and heat-treating in a protective atmosphere; Preferably, the physical activator is selected from one or more of oxygen, carbon dioxide, water vapor, and air; Preferably, the heat treatment temperature in the physical activation method is 500 - 1200 °C, and the time is 1 - 30 h; Preferably, the chemical activator is selected from one or more of hydrochloric acid, phosphoric acid, sodium hydroxide, and potassium hydroxide; Preferably, the heat treatment temperature in the chemical activation method is 350 - 1100 °C, and the time is 1 - 36 h.

6. The preparation method according to any one of claims 1-5, characterized in that, The preparation method further includes a post-treatment step, and the post-treatment step includes: after the carbonization or activation, infiltrate the obtained product with a soluble carbon source solution, and after drying or not drying, heat and carbonize in a protective atmosphere; Preferably, the soluble carbon source is selected from one or more of chitosan, styrene, pyridine-soluble fraction of toluene-insoluble fraction of pitch, and quinoline-soluble fraction of toluene-insoluble fraction of pitch; Preferably, the concentration of the soluble carbon source solution is 1 - 20 g / L; Preferably, the carbonization temperature in the post-treatment step is 800 - 1500 °C, and the heat preservation time is 1 - 4 h.

7. The preparation method according to any one of claims 1-6, characterized in that, The specific surface area of the porous carbon material is 100 - 2000 m 2 / g, the pore size distribution is 0.7 - 100 nm, and the average pore size is 1 - 5 nm.

8. A porous carbon material, characterized in that, Prepared by the preparation method according to any one of claims 1 - 7.

9. A silicon-carbon anode material, characterized in that, The silicon-carbon negative electrode material includes the porous carbon material according to claim 8, and silicon coated and filled on the surface and in the pores of the porous carbon material; Preferably, the silicon is deposited on the surface and in the pores of the porous carbon material by chemical vapor deposition.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the silicon-carbon negative electrode material according to claim 9.

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