Porous carbon material, regulation and control method and application of pore structure of porous carbon material, and preparation method of silicon-carbon negative electrode material

Abstract

The invention belongs to the technical field of porous materials, and particularly relates to a porous carbon material, a regulation and control method and application of a pore structure of the porous carbon material, and a preparation method of a silicon-carbon negative electrode material. By controlling the surface tension and viscosity of the carbon precursor solution, the carbon precursor solution can better enter the pore structure of the porous carbon material, and the carbon precursor solution in the target pore structure can be removed through solid-liquid separation (i.e., the carbon precursor solution can form capillary condensation with the unexpected pore structure); and by limiting the comprehensive residual carbon rate, the carbon precursor can be ensured to realize an effective sealing effect on an unexpected pore structure in the carbonization process, so that regulation and control of the pore structure are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous materials, and particularly relates to a porous carbon material, a method for regulating its pore structure and applications thereof, and a method for preparing a silicon-carbon anode material. Background Art

[0002] The synthesis of porous materials is usually accompanied by the researchers' need for precise regulation of pore structure. The template method can be used to obtain porous materials with a uniform pore size distribution. However, the template method generally has disadvantages such as high cost, large pollution, and difficulty in scaling up. Therefore, the activation method is more commonly used in industry to obtain porous materials. The principle of the activation method is to use an activator, a substance that can react with the substrate at high temperature, to etch pores in the bulk structure of the substrate. However, the reaction at high temperature is usually intense and difficult to control. Therefore, the porous materials obtained by the activation method usually have a very wide pore size distribution, and an overly wide pore size distribution usually has a negative impact in actual engineering applications. For the overly wide pore structure distribution, it is necessary to shrink its pore size distribution curve or selectively close some unnecessary pores through post-treatment. In the field of porous carbon materials, carbon precursor solutions are commonly used to fill pores, and there is no selectivity in the regulation of the pore structure in porous materials. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the above defects existing in the regulation of the pore structure of porous carbon materials in the prior art, so as to provide a porous carbon material, a method for regulating its pore structure and applications thereof, and a method for preparing a silicon-carbon anode material.

[0004] To this end, the present invention provides the following technical solutions:

[0005] The present invention provides a method for regulating the pore structure of a porous carbon material, comprising the following steps,

[0006] S1, preparing a carbon precursor solution, and by regulating the surface tension, viscosity and comprehensive carbon residue rate, impregnating it inside the pore structure to be blocked;

[0007] S2, performing solid-liquid separation and carbonization.

[0008] In the present invention, the size of the pore structure to be blocked can be micropores, mesopores, or any other pore structure with an undesired size.

[0009] Optionally, controlling the surface tension of the carbon precursor solution to be 32.55×10 -3 N / m to 140×10 -3 N / m, the viscosity at 20°C is 6 - 40 mP·s, and the comprehensive carbon residue rate of the carbon precursor solution > 4%.

[0010] The above limitations on the surface tension, viscosity, and comprehensive carbon residue rate of the carbon precursor solution enable the carbon precursor solution to fully infiltrate micropores or mesopores during the impregnation process and remain in the pores to be plugged. Through subsequent carbonization steps, the plugging of micropores or mesopores can be achieved. If the viscosity of the carbon precursor solution is too high, it cannot fully diffuse into the pores of the porous carbon material and is only adsorbed on the outside of the particles of the porous carbon material. To reduce the viscosity, measures such as reducing the concentration of the carbon precursor solution are usually taken, but this will result in a relatively small comprehensive carbon residue rate and cannot play a good role in plugging pores after carbonization.

[0011] Optionally, when the surface tension of the carbon precursor solution is 32.55×10 -3 N / m to 110×10 -3 N / m, at this time, the carbon precursor solution can enter micropores with a pore diameter less than 2 nm, and most of the carbon precursor solution in mesopores around 2 - 20 nm can be removed in the solid-liquid separation step, enabling the plugging of micropores and the retention of mesopores. Preferably, the surface tension of the carbon precursor solution is 60×10 -3 N / m to 110×10 -3 N / m, the viscosity at 20 °C is 15 - 35 mP·s, and the comprehensive carbon residue rate of the carbon precursor solution is 4 - 12%, which can further improve the selectivity of micropore plugging.

[0012] Optionally, when the surface tension of the carbon precursor solution is 110×10 -3 N / m to 140×10 -3 N / m, at this time, the carbon precursor solution is difficult to enter micropores with a pore diameter less than 2 nm and aggregates in mesopores around 2 - 20 nm. The carbon precursor solution in mesopores larger than 20 nm can be removed in the solid-liquid separation step, so the plugging of 2 - 20 nm mesopores can be achieved. Preferably, the viscosity of the carbon precursor solution at 20 °C is 15 - 35 mP·s, and the comprehensive carbon residue rate is 4 - 12%, which can further improve the selectivity of 2 - 20 nm mesopore plugging.

[0013] In the present invention, the comprehensive carbon residue rate of the carbon precursor solution = the mass concentration of the carbon precursor solution × the carbon residue rate of the carbon precursor.

[0014] In the present invention, any solution that can infiltrate the porous carbon material and leave the carbon precursor inside the porous carbon material after separation and drying can be selected. Or rather, as long as capillary condensation can occur between the pore size of the porous carbon material to be treated and the carbon precursor solution.

[0015] Optionally, in the carbon precursor solution, the residual carbon rate of the carbon precursor is greater than 20%. Optionally, the carbon precursor includes at least one of glucose, sucrose, lignin, furfural, furfuryl alcohol, phenolic resin, and water-soluble resin. Any carbon-containing material that has a high residual carbon rate and can be dissolved in the following solvents can be selected.

[0016] Optionally, the solvent in the carbon precursor solution includes at least one of water, ethanol, methanol, acetonitrile, cyclohexane, benzene, kerosene, ether, propanol, and acetone. These solvents have different surface tension values, and their surface tension can be adjusted within a certain range by compounding.

[0017] Optionally, the carbonization step further includes a drying step;

[0018] The drying temperature in the present invention is not particularly limited, and a temperature that allows the solvent to volatilize can be selected. Optionally, the drying temperature is 60-200°C.

[0019] In the present invention, drying is performed before carbonization, so as to avoid as much as possible the damage to the pore structure of the porous carbon material caused by water vapor generated by rapid temperature rise during the carbonization process.

[0020] The immersion time in the present invention is conventional in the art, as long as the carbon precursor solution can be fully impregnated into the pore structure to be blocked. Optionally, in step S2, the immersion time is 0.5-24 hours.

[0021] In the present invention, the carbonization temperature is conventional in the field. Optionally, in step S2, the carbonization step is performed under an inactive atmosphere;

[0022] And / or, the carbonization temperature is 400-1000° C., the carbonization time is 0.5-8 h, and the heating rate is 1-15° C. / min.

[0023] Optionally, the porous carbon material to be treated is a carbon-based material with a certain microporous and / or mesoporous structure, including at least one of activated carbon, activated carbon fiber, mesoporous carbon, carbon molecular sieve, and carbon aerogel. Optionally, the specific surface area of ​​the porous carbon material to be treated is 600 to 2000 m 2 / g, total pore volume 0.3~1.4cm 3 / g, the proportion of mesopore volume to total pore volume is 0-70%, and the proportion of micropore volume to total pore volume is 0-70%.

[0024] And / or, the contact angle between the porous carbon material to be treated and pure water is 30-60°. When the contact angle is too small, it is a super hydrophilic material, and it is difficult to control the carbon precursor solution to remain in the space with the selected pore size; when the contact angle is too large, the material tends to be hydrophobic, and it is difficult for the carbon precursor solution to enter the selected pore size space. The porous carbon material with a contact angle of 30-60° with pure water can be used as a better object for regulating the pore structure.

[0025] The present invention also provides a method for selectively plugging microporous structures of porous carbon materials, comprising the following steps:

[0026] S1. Prepare a carbon precursor solution, adjust the surface tension of the carbon precursor solution to be 32.55×10 -3 N / m - 110×10 -3 N / m, with a viscosity of 15 - 35 mP·s at 20°C and a comprehensive residual carbon rate of 4 - 12%, and immerse it inside the pore structure to be plugged;

[0027] S2. Perform solid-liquid separation and carbonization.

[0028] The present invention also provides a method for selectively plugging mesoporous structures of porous carbon materials, comprising the following steps:

[0029] S1. Prepare a carbon precursor solution, adjust the surface tension of the carbon precursor solution to be 110×10 -3 N / m - 140×10 -3 N / m, with a viscosity of 15 - 35 mP·s at 20°C and a comprehensive residual carbon rate of 4 - 12%, and immerse it inside the pore structure to be plugged;

[0030] S2. Perform solid-liquid separation and carbonization.

[0031] The present invention also provides a regulated porous carbon material obtained by the above regulation method.

[0032] The present invention also provides an application of the above-regulated porous carbon material in the field of the negative electrode of secondary batteries or adsorption separation.

[0033] The specific application method is conventional in the field and is not specifically limited herein. Optionally, the application of the regulated porous carbon material in the negative electrode of secondary batteries includes being used for preparing a silicon-carbon negative electrode material.

[0034] The present invention also provides a method for preparing a silicon-carbon negative electrode material, comprising: depositing silicon-containing particles in the above-regulated porous carbon material to obtain a silicon-carbon negative electrode material.

[0035] After the pore structure of the porous carbon material is regulated by the present invention, in the field of the negative electrode of secondary batteries, silicon-containing gas requires mesoporous channels to promote its diffusion in the porous carbon structure, which is beneficial to fully depositing silicon particles to fill the internal pores; meanwhile, micropores are beneficial to controlling the size of silicon particles, but too small micropores will cause the silicon-containing gas to be difficult to diffuse and decompose and deposit silicon particles in advance at the entrance to block the pores. Therefore, by appropriately closing too small micropores through the present method, the deposition efficiency of the silicon-containing gas can be improved, as well as the deposition rate of the silicon-containing gas inside the porous carbon can be increased, side reactions and volume expansion can be reduced, and the capacity and cycle times of battery products can be improved.

[0036] In the field of adsorption separation, due to size matching, pore structures with different pore diameters have specific adsorption properties corresponding one by one to molecules with different molecular kinetic diameters. Therefore, by specifically closing irrelevant pore structures such as micropores or overly large mesopores through this method, the adsorption ratio of molecules with a certain molecular kinetic diameter can be specifically increased, while the adsorption performance for irrelevant molecules is reduced.

[0037] In the present invention, the principle of regulating the pore structure of the porous carbon material is as follows:

[0038] Due to the contact problem between the liquid or solution and the phase interface of the porous material, the impregnation effect of heterogeneous liquids or solutions in the pore structures with different pore diameters of the porous material is affected by factors such as liquid tension and viscosity. Based on this influence, liquids with different surface tensions and viscosities can be formulated to selectively enter and remain in the pore structures with specific pore diameters in the substrate. By defining the comprehensive residual carbon rate, these pore structures can be closed during the subsequent carbonization process, while keeping other required pore structures open.

[0039] The technical solution of the present invention has the following advantages:

[0040] The method for regulating the pore structure of the porous carbon material provided by the present invention includes the following steps: S1, preparing a carbon precursor solution, and by regulating the surface tension, viscosity, and comprehensive residual carbon rate, impregnating it inside the pore structures to be blocked; S2, solid-liquid separation and carbonization. By controlling the surface tension and viscosity of the carbon precursor solution, the present invention can enable the carbon precursor solution to better enter the pore structure of the porous carbon material. Through solid-liquid separation, most of the carbon precursor solution in the pore structure can be removed, and the carbon precursor solution in the pore structures to be blocked is retained (i.e., the carbon precursor solution can form a capillary condensation effect with the pore structures to be blocked). By defining the comprehensive residual carbon rate, it can be ensured that the carbon precursor effectively closes the undesired pore structures during the subsequent carbonization process, thereby achieving the regulation of the pore structure.

[0041] The method for regulating the pore structure of the porous carbon material provided by the present invention controls the surface tension of the carbon precursor solution to be 32.55×10 -3 N / m~140×10 -3N / m, with a viscosity of 6 - 40 mPa·s at 20°C, and the comprehensive residual carbon rate of the carbon precursor solution > 4%. By controlling the surface tension and viscosity of the carbon precursor solution, the present invention enables the carbon precursor solution to fully infiltrate micropores or mesopores during the impregnation process and remain in the pores to be blocked, and realizes the blocking of micropores or mesopores through subsequent carbonization steps. If the viscosity of the carbon precursor solution is too high, it cannot fully diffuse into the pores inside the porous carbon material and is only adsorbed on the outside of the particles of the porous carbon material. In order to reduce the viscosity, measures such as reducing the concentration of the carbon precursor solution are usually taken, but this will result in a relatively small comprehensive residual carbon rate and cannot play a good role in plugging pores after carbonization. Specifically, by defining the surface tension of the carbon precursor solution as 60×10 -3 N / m to 110×10 -3 N / m, the carbon precursor solution can fully infiltrate micropores during the impregnation process and remain in the micropores, and realizes the blocking of micropores and the retention of mesopores through subsequent carbonization steps. By defining the surface tension of the carbon precursor solution as 110×10 -3 N / m to 140×10 -3 N / m, the blocking of mesopores about 2 - 20 nm can be realized and the micropores are retained.

[0042] The pore structure regulation method of the porous carbon material provided by the present invention can realize the regulation of surface tension, viscosity and comprehensive residual carbon rate by defining the composition of the carbon precursor solution, thereby expanding the applicable range of the regulation method and better realizing the regulation of the pore structure.

[0043] The application of the regulated porous carbon material provided by the present invention in the negative electrode of secondary batteries or the field of adsorption separation. Using the regulated porous carbon material as a substrate, after depositing silicon with a silicon-containing gas, a silicon-carbon negative electrode material is prepared, which has a higher silicon content, higher capacity and better cycle performance when used in lithium batteries. When used in the field of adsorption separation, by selectively closing too large or too small pores, the selective adsorption separation of molecules with a certain molecular kinetic diameter can be selectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 are the gas adsorption and desorption curves of activated carbon before and after regulation in Examples 1 - 3 and Examples 9 - 10 of the present invention;

[0046] Figure 2 It is the pore size distribution diagrams of the activated carbon before and after regulation in Embodiments 1-3 and Embodiments 9-10 of the present invention. Detailed implementation manners

[0047] The following embodiments are provided to better further understand the present invention. They are not limited to the described optimal implementation manners, and do not constitute limitations on the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other prior arts falls within the protection scope of the present invention.

[0048] For those embodiments where specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0049] Embodiment 1

[0050] This embodiment provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0051] (1) Prepare a carbon precursor solution with ethanol, glucose and water, and the specific parameters are shown in Table 1;

[0052] (2) Immerse the activated carbon material (specific surface area is 1251 m 2 / g, total pore volume 0.8 cm 3 / g, micropore volume 0.34 cm 3 / g, mesopore volume 0.46 cm 3 / g, contact angle with pure water is 44°) into the above carbon precursor solution, and the immersion time is 8 h;

[0053] (3) Filter, dry at 100 °C, and in an inert gas environment, heat up to 550 °C at a heating rate of 10 °C / min and carbonize for 4 h to obtain the regulated activated carbon (AC-10).

[0054] Embodiment 2

[0055] This embodiment provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0056] (1) Prepare a carbon precursor solution with ethanol, glucose and water, and the specific parameters are shown in Table 1;

[0057] (2) Immerse the activated carbon material (the same as in Embodiment 1) into the above carbon precursor solution, and the immersion time is 8 h;

[0058] (3) Filter, dry at 120 °C, and in an inert gas environment, heat to 550 °C at a heating rate of 5 °C / min and carbonize for 4 h to obtain the regulated activated carbon (AC-20).

[0059] Example 3

[0060] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0061] (1) Prepare a carbon precursor solution with ethanol, glucose, and water. The specific parameters are shown in Table 1;

[0062] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0063] (3) Filter, dry at 120 °C, and in an inert gas environment, heat to 600 °C at a heating rate of 10 °C / min and carbonize for 6 h to obtain the regulated activated carbon (AC-40).

[0064] Example 4

[0065] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0066] (1) Prepare a carbon precursor solution with resol (water-soluble resin PF9701-4 from Shengquan), ethanol, and water. The specific parameters are shown in Table 1;

[0067] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0068] (3) Filter, dry at 180 °C, and in an inert gas environment, heat to 800 °C at a heating rate of 10 °C / min and carbonize for 4 h to obtain the regulated activated carbon.

[0069] Example 5

[0070] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0071] (1) Prepare a carbon precursor solution with ethanol, furfuryl alcohol, and water. The specific parameters are shown in Table 1;

[0072] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0073] (3) Filter, dry at 120 °C, and in an inert gas environment, heat to 800 °C at a heating rate of 10 °C / min and carbonize for 4 h to obtain the regulated activated carbon.

[0074] Example 6

[0075] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0076] (1) Prepare a carbon precursor solution with ethanol, sucrose, and water. The specific parameters are shown in Table 1;

[0077] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0078] (3) Filter, dry at 100 °C, and in an inert gas environment, heat to 600 °C at a heating rate of 5 °C / min and carbonize for 4 h to obtain the regulated activated carbon.

[0079] Example 7

[0080] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0081] (1) Prepare a carbon precursor solution with ethanol, glucose, and water. The specific parameters are shown in Table 1;

[0082] (2) Immerse the mesoporous carbon material (specific surface area of 830 m 2 / g, total pore volume of 0.77 cm 3 / g, micropore volume of 0.14 cm 3 / g, mesopore volume of 0.63 cm 3 / g, contact angle with pure water of 30°) in the above carbon precursor solution for 8 h;

[0083] (3) Filter, dry at 120 °C, and in an inert gas environment, heat to 550 °C at a heating rate of 10 °C / min and carbonize for 4 h to obtain the regulated activated carbon.

[0084] Example 8

[0085] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0086] (1) Prepare a carbon precursor solution with ethanol, glucose, and water. The specific parameters are shown in Table 1;

[0087] (2) Immerse the activated carbon material (specific surface area of 1425 m 2 / g, total pore volume of 0.6 cm 3 / g, micropore volume of 0.24 cm 3 / g, mesopore volume of 0.36 cm 3 / g, contact angle with pure water of 60°) in the above carbon precursor solution for 8 h;

[0088] (3) Filtration, drying at 120 °C, heating to 550 °C at a heating rate of 10 °C / min in an inert gas environment, and carbonizing for 4 h to obtain the regulated activated carbon.

[0089] Example 9

[0090] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0091] (1) Prepare a carbon precursor solution with glucose and water, and the specific parameters are shown in Table 1;

[0092] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0093] (3) Filtration, drying at 100 °C, heating to 550 °C at a heating rate of 10 °C / min in an inert gas environment, and carbonizing for 4 h to obtain the regulated activated carbon (AC-0).

[0094] Example 10

[0095] This example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0096] (1) Prepare a carbon precursor solution with glucose, ethanol and water, and the specific parameters are shown in Table 1;

[0097] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0098] (3) Filtration, drying at 100 °C, heating to 550 °C at a heating rate of 10 °C / min in an inert gas environment, and carbonizing for 4 h to obtain the regulated activated carbon (AC-5).

[0099] Comparative Example 1

[0100] This comparative example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0101] (1) Prepare a carbon precursor solution with ethanol, glucose and water, and the specific parameters are shown in Table 1;

[0102] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 h;

[0103] (3) Filtration, drying at 100 °C, heating to 550 °C at a heating rate of 10 °C / min in an inert gas environment, and carbonizing for 4 h to obtain the regulated activated carbon.

[0104] Comparative Example 2

[0105] This comparative example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0106] (1) Prepare a carbon precursor solution with glucose and water, and the specific parameters are shown in Table 1;

[0107] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 hours;

[0108] (3) Filter, dry at 100 °C, and in an inert gas environment, heat up to 550 °C at a heating rate of 10 °C / min and carbonize for 4 hours to obtain the regulated activated carbon.

[0109] Comparative Example 3

[0110] This comparative example provides a method for regulating the pore structure of a porous carbon material, and its specific steps and operating parameters are as follows:

[0111] (1) Prepare a carbon precursor solution with polyvinyl alcohol (Maclean P875078) and water, and the specific parameters are shown in Table 1;

[0112] (2) Immerse the activated carbon material (the same as in Example 1) in the above carbon precursor solution for 8 hours;

[0113] (3) Filter, dry at 100 °C, and in an inert gas environment, heat up to 550 °C at a heating rate of 10 °C / min and carbonize for 4 hours to obtain the regulated activated carbon.

[0114] Test Example

[0115] Test the pore structures of the porous carbon materials before and after regulation provided in the examples and comparative examples of the present invention, as well as the parameters of the carbon precursor solution. The specific test methods are as follows:

[0116] Specific surface area and pore volume (i.e., pore volume): The pore size distribution and specific surface area of the porous carbon material are measured by gas adsorption and desorption experiments. Specifically, place the porous carbon material in an environment of 150 °C - 300 °C and a pressure < 10 -6 Bar for degassing for 1 hour - 6 hours (in this test example, degassing at 200 °C for 6 hours); then introduce nitrogen at liquid nitrogen temperature, slowly restore the pressure to normal pressure and then degas again to 10 -6 Bar, record the data to obtain the adsorption and desorption isotherm, calculate the pore size distribution and pore volume data of the porous carbon material according to the density functional theory (DFT) model, and calculate the specific surface area data of the porous carbon using the BET model. The total pore volume, micropore volume, and mesopore volume are taken at 50 nm, 2 nm, and the difference between the first two in the cumulative graph of gas physical adsorption and desorption pore volume against pore size, respectively.

[0117] Viscosity: The measurement method of viscosity follows the rotational method test in the national standard GB / T 10247-2008.

[0118] Surface tension: The test of surface tension follows the industry standard SY / T 5370-2018.

[0119] Residual carbon rate of carbon precursor: The carbon precursor is heated to the carbonization temperature of the carbon precursor under the protection of inert gas, and the residual carbon rate is obtained by dividing the mass of the obtained carbon by the mass of the carbon precursor. The comprehensive residual carbon rate of the carbon precursor solution = the mass concentration of the carbon precursor solution × the residual carbon rate of the carbon precursor.

[0120] The specific test results are shown in Table 1 and Table 2 below:

[0121] Table 1

[0122]

[0123]

[0124] Table 2

[0125]

[0126] From the test data in the above table, it can be seen that using a carbon precursor solution with appropriate viscosity and surface tension and a residual carbon rate > 4% can effectively seal micropores and / or mesopores and reduce the micropore and / or mesopore volume in the porous carbon material. However, using a carbon precursor solution with a residual carbon rate < 4% cannot effectively seal the micropores and / or mesopores. When the surface tension is too large, the liquid cannot wet the surface of the carbon material well and cannot fully enter the pores inside the carbon material. When the viscosity is too large, it is difficult for the liquid to enter the inside of the carbon material, or the liquid in the pore structure that does not need to be blocked is also difficult to escape from the inside of the carbon material during the filtration process, resulting in the inability to seal the pore structure or the inability to specifically seal the pore structure; while when the viscosity is too small, the liquid cannot stay in the pores to be blocked, resulting in the inability to seal the pore structure. Figure 1 It is the gas adsorption and desorption curves of activated carbon before (AC) and after regulation in Examples 1-3 and Examples 9-10 of the present invention; it can be seen that after regulation in Examples 1-3, the adsorption capacity in the low-pressure region (P / P0 < 0.01) of the adsorption and desorption curve decreases significantly, indicating a significant reduction in the micropore volume. In Examples 9-10, the area of the hysteresis loop in the range of P / P0 = 0.4 - 0.8 decreases, indicating a significant reduction in the mesopore volume; Figure 2It is the pore size distribution diagrams of activated carbon before (AC) and after regulation in Embodiments 1-3 and 9-10 of the present invention. It can be seen that compared with AC, the mesopore volume of AC-0 at around 10 nm is significantly reduced, and there is selectivity in the closure of mesopores in this region. After adding an appropriate amount of ethanol, the surface tension of the carbon precursor solution decreases and it can enter smaller pore structures. Therefore, it can be seen from the pore size distribution diagram that compared with AC-0, the mesopore volume of AC-5 at around 3 nm has significantly decreased. After increasing the ethanol content and modulating the surface tension and viscosity, the pore closure range of AC-10, AC-20, and AC-40 moves to the micropore region, and it can be seen that the micropore volume with a pore size <2 nm is significantly reduced.

[0127] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A method for regulating the pore structure of a porous carbon material, characterized in that, It includes the following steps: S1. Prepare a carbon precursor solution, and by regulating the surface tension, viscosity and comprehensive residual carbon rate, impregnate it inside the pore structure to be plugged; S2. Perform solid-liquid separation and carbonization.

2. The method for regulating the pore structure of a porous carbon material according to claim 1, characterized in that, In step S1, control the surface tension of the carbon precursor solution to be 32.55×10 -3 N / m to 140×10 -3 N / m, with a viscosity of 6 - 40 mP·s at 20°C, and the comprehensive residual carbon rate of the carbon precursor solution > 4%.

3. The method for regulating the pore structure of a porous carbon material according to claim 2, characterized in that, It satisfies at least one of the following characteristics (1)-(4): (1) The surface tension of the carbon precursor solution is 32.55×10 -3 N / m to 110×10 -3 N / m; (2) The surface tension of the carbon precursor solution is 110×10 -3 N / m to 140×10 -3 N / m; (3) The viscosity of the carbon precursor solution at 20 °C is 15-35 mP·s; (4) The comprehensive residual carbon rate of the carbon precursor solution is 4-12%.

4. The method for regulating the pore structure of a porous carbon material according to any one of claims 1-3, characterized in that, The carbon precursor solution satisfies at least one of the following characteristics (1)-(3): (1) The residual carbon rate of the carbon precursor > 20%; (2) The carbon precursor includes at least one of glucose, sucrose, lignin, furfural, furfuryl alcohol, and water-soluble resin; (3) The solvent in the carbon precursor solution includes at least one of water, ethanol, methanol, acetonitrile, cyclohexane, benzene, kerosene, ether, propanol, and acetone.

5. The method for regulating the pore structure of a porous carbon material according to any one of claims 1-4, characterized in that, It satisfies at least one of the following characteristics (1)-(8): (1) A drying step is further included before the carbonization step; (2) A drying step is further included before the carbonization step, and the drying temperature is the solvent evaporation temperature; (3) A drying step is further included before the carbonization step, and the drying temperature is 60-200 °C; (4) In step S1, the impregnation time is 0.5-24 h; (5) The carbonization step is carried out in an inert atmosphere; (6) The carbonization temperature is 400-1000 °C; (7) The carbonization time is 0.5-8 h; (8) The carbonization heating rate is 1-15 °C / min.

6. The method for regulating the pore structure of a porous carbon material according to any one of claims 1-5, characterized in that, The porous carbon material to be treated satisfies at least one of the following characteristics (1)-(6): (1) The porous carbon material to be treated includes at least one of activated carbon, activated carbon fiber, mesoporous carbon, carbon molecular sieve, and carbon aerogel; (2) The contact angle of the porous carbon material to be treated with pure water is 30-60°; (3) The specific surface area of the porous carbon material to be processed is 600 to 2000 m 2 / g; (4) The total pore volume of the porous carbon material to be processed is 0.3 to 1.4 cm 3 / g; (5) The proportion of the mesoporous pore volume in the total pore volume of the porous carbon material to be treated is 0-70%; (6) The proportion of the microporous pore volume in the total pore volume of the porous carbon material to be treated is 0-70%.

7. A method for selectively plugging micropore structures of a porous carbon material, characterized in that, It includes the following steps: S1. Prepare a carbon precursor solution, adjust the surface tension of the carbon precursor solution to be 32.55×10 -3 N / m to 110×10 -3 N / m, with a viscosity of 15 - 35 mP·s at 20°C and a comprehensive residual carbon rate of 4 - 12%, and immerse it inside the pore structure to be plugged; S2. Perform solid-liquid separation and carbonization.

8. A method for selectively plugging mesoporous structures of porous carbon materials, characterized in that, It includes the following steps: S1. Prepare a carbon precursor solution, and adjust the surface tension of the carbon precursor solution to be 110×10 -3 N / m to 140×10 -3 N / m; the viscosity at 20°C is 15 - 35 mP·s, and the comprehensive residual carbon rate is 4 - 12%, and immerse it inside the pore structure to be plugged; S2. Perform solid-liquid separation and carbonization.

9. A regulated porous carbon material obtained by the method according to any one of claims 1-8.

10. An application of the regulated porous carbon material according to claim 9 in the field of negative electrodes of secondary batteries or adsorption separation.

11. A method for preparing a silicon-carbon negative electrode material, characterized in that, It includes: Deposit silicon-containing particles in the regulated porous carbon material as described in claim 9 to obtain a silicon-carbon negative electrode material.

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