Sieving carbon, its manufacturing method and applications

Abstract

The present invention discloses a sieving carbon and its manufacturing method and application. A primary carbon deposition is deposited on the pore opening of the sieving carbon, and a secondary carbon deposition is deposited at the pore opening position on the surface of the primary carbon deposition. Neither of the two deposited carbons enters the pore chamber, and the diameter of the pore opening after the two depositions is smaller than 0.33 nm. The specific surface area of ​​the sieving carbon according to the CO2 adsorption and desorption test is 0-10 m 2 / g. The present invention maintains the original pore size while adjusting the pore opening to less than 0.33 nm through two chemical vapor deposition processes, effectively improving the initial coulombic efficiency of the carbon material.

Description

[Technical Field]

[0001] The present invention relates to the field of electrode material technology, and in particular to sieved carbon and its manufacturing method and application. [Background technology]

[0002] Amorphous carbon materials are the most commercially promising battery anode materials due to their low cost, low operating potential, and excellent cycling stability. However, amorphous carbon materials currently face the main problem of low initial coulombic efficiency, which has significantly hindered their commercialization.

[0003] The electrochemical performance of amorphous carbon materials is closely related to their microstructure. In particular, the pore structure of a carbon material directly affects its initial coulombic efficiency. Chinese patent application publication number CN116553547A, "High-energy and high-power carbon material and manufacturing method thereof, and sodium ion battery," discloses a high-energy and high-power carbon material with a pore diameter of 0.1 to 0.4 nm. However, a pore diameter of 0.4 nm is still too large and is unfavorable to the initial coulombic efficiency, so the pore size needs to be further adjusted.

[0004] The present invention discloses a sieving carbon and its manufacturing method and application, and its pores can be made smaller than 0.33 nm after two size adjustments, and there are no pores between 0.33 nm and 0.4 nm, and its initial Coulomb efficiency is significantly improved. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a sieving carbon to address the problem of oversized pore size in carbon materials present in the prior art.

[0006] Another object of the present invention is to provide a method for producing the above sieving carbon.

[0007] A further object of the present invention is to provide an application of said sieved carbon in battery electrodes. [Means for solving the problem]

[0008] In order to achieve the object of the present invention, the technical solutions used are as follows.

[0009] A sieving carbon is obtained by depositing primary carbon deposits on the pore openings and the periphery of the pore openings of the sieving carbon, and depositing secondary carbon deposits on the pore openings on the surface of the primary carbon deposits. Neither of the two deposited carbon deposits enters the pore chambers, and the diameters of the pore openings after the two depositions are both smaller than 0.33 nm. The specific surface area of ​​the sieving carbon obtained by CO2 adsorption and desorption tests is 0-10 m 2 / g.

[0010] In the above technical solution, the pore diameter of the sieving carbon is 0.5 to 10 nm.

[0011] According to another aspect of the present invention, a method for producing sieved carbon includes the steps of: The pores are rapidly reduced by the first chemical vapor deposition. That is, the porous carbon is placed in a chemical vapor deposition apparatus, and a protective gas is passed through at a predetermined flow rate, and the temperature is raised to 1100-1300°C. Then, the first chemical vapor deposition is passed through at a predetermined flow rate. Step 1: Passing a carbon source gas through the reactor and performing the first incubation; Step 2: finishing the hole openings by a second chemical vapor deposition until the diameter is smaller than 0.33 nm, i.e., after the first heat-holding is completed, the first carbon source gas is turned off, the temperature is lowered to 600-800°C, and a second carbon source gas is passed through at a predetermined flow rate, and a second heat-holding is performed; and step 3, stopping the second carbon source gas and lowering the temperature to room temperature at a predetermined rate to obtain the sieved carbon.

[0012] As shown in Figure 17, the temperature for the first chemical vapor deposition (rapid hole shrinkage) is 1100-1300°C. At this temperature, the carbon source gas rapidly decomposes and deposits, sacrificing the selectivity of the carbon source gas deposited at the hole mouth (some deposition occurs outside the hole), thereby rapidly shrinking the hole mouth. The hole mouth is a defective site, and the rapidly decomposed carbon source gas mainly deposits at the hole mouth, with a small amount deposited outside the hole. If the temperature is lower than 1100°C, the goal of rapidly shrinking the hole mouth cannot be achieved, and the hole mouth shrinkage speed is relatively slow, causing the deposited carbon to enter the hole. If the temperature is higher than 1300°C, the deposition speed is too fast, which may cause the hole mouth to be instantly blocked, resulting in excessive ineffective carbon deposition.

[0013] The second chemical vapor deposition (finishing the pore openings to a diameter less than 0.33 nm) is performed at a temperature of 600-800°C. At this temperature, the decomposition rate of the carbon source gas is slow, allowing selective deposition at the pore openings with no deposition outside the pores, further refining the pore opening size to less than 0.33 nm. If the temperature is higher than 800°C, the finishing goal cannot be achieved and excessive carbon deposition occurs outside the pores. If the temperature is lower than 600°C, the carbon source gas decomposes and cannot be deposited.

[0014] In the above technical solution, the porous carbon in step 1 is walnut shell-based porous carbon, bamboo-based activated carbon, coconut shell-based porous carbon, peanut shell-based porous carbon, petroleum coke-based porous carbon, needle coke-based porous carbon, or activated carbon fiber.

[0015] In the above technical solution, the first carbon source gas in step 1 is methane, benzene vapor, toluene vapor, xylene vapor, ethane, propane or acetylene; the second carbon source gas in step 2 is methane, benzene vapor, toluene vapor, xylene vapor, ethane, propane, or acetylene; Preferably, the first carbon source gas is the same as the second carbon source gas.

[0016] In the above technical solution, the flow rate of the first carbon source gas in step 1 is 10 to 500 mL / min. If the flow rate of the carbon source gas is too small, the hole opening size remaining after the first chemical vapor deposition will be relatively large, resulting in a large amount of deposited carbon entering the hole during hole opening finishing in step 2. If the flow rate of the carbon source gas is too large, the hole will be over-blocked, resulting in a large amount of ineffective deposited carbon at the hole opening, and the initial coulomb efficiency during sodium storage will be low.

[0017] In the above technical solution, the first incubation time in step 1 is 0-30 minutes, but not 0. The purpose of the first chemical vapor deposition is to rapidly shrink the pore opening and prevent deposited carbon from entering the pores. If the incubation time is too long, excessive deposition will occur, which will affect the initial coulomb efficiency of sodium storage.

[0018] In the above technical proposal, after completing step 1, the size of the pores can be adjusted so that most of the pores cannot allow N2 to enter but can allow CO2 to enter, i.e., the specific surface area according to the N2 adsorption and desorption test is 0-100m2. 2 / g, and the specific surface area measured by CO2 adsorption and desorption tests is 100-2000 m 2 / g, and the diameter of most of the pores is 0.33~0.364nm.

[0019] In the above technical solution, the flow rate of the second carbon source gas in step 2 is ≧10 mL / min. If the flow rate of the carbon source gas is too low, it will take a relatively long time to complete the hole opening.

[0020] In the above technical solution, the second incubation time in step 2 is ≥ 3 hours, and the second deposition is performed at a relatively low deposition temperature, so deposition occurs selectively only at the pore openings. After the pore openings are finished, no deposition occurs. If the deposition time is < 3 hours, the effect of pore opening finishing cannot be achieved, resulting in a relatively low initial Coulomb efficiency and a relatively low sodium storage capacity. Step 2 is performed at a relatively low reaction temperature, so the decomposition and deposition of the carbon source gas must occur at a position with a low energy barrier. In the case of porous carbon, the position with a low energy barrier is the pore opening with many defects. After all the pore opening positions are occupied by deposited carbon, there are no positions available for the decomposition and deposition of the carbon source gas, so even if the time is further extended, no deposition will occur.

[0021] In the above technical solution, after the hole opening is completed in step 2, the hole opening size of all holes is closed until CO2 cannot enter, that is, the specific surface area in the CO2 adsorption and desorption test is 0~10m 2 / g, and the pore opening diameter of all pores is smaller than 0.33 nm.

[0022] In the above technical solution, the pore size of the sieving carbon obtained in step 3 is the same as the pore size of the porous carbon in step 1.

[0023] In the above technical solution, the temperature drop rate in step 3 is 5 to 20°C / min.

[0024] Another aspect of the present invention further includes the application of the sieved carbon in a battery negative electrode.

[0025] In the above technical solution, the sodium storage capacity of the battery negative electrode is 350-600mAh / g, and the initial coulomb efficiency is 91-95%.

[0026] According to another aspect of the present invention, the battery further includes a negative electrode based on sieved carbon, the negative electrode including a negative electrode active material, a conductive agent, and an adhesive, wherein the negative electrode active material is the sieved carbon, the conductive agent is SUPER-P, KS-6, conductive graphite, carbon nanotubes, graphene, carbon fiber VGCF, acetylene black, or Ketjen black, and the adhesive is PVDF, CMC, SBR, PTFE, SA, PAA, or PAN.

[0027] According to another aspect of the present invention, there is provided a battery comprising a positive electrode, a negative electrode based on the sieved carbon described above, and an electrolyte, The positive electrode active material is a layered transition metal oxide, a sodium polyanion compound, Prussian blue, or Prussian white.

[0028] The electrolyte includes an organic solvent and a sodium salt, where the organic solvent includes EC, PC, DMC, DEC, EMC, EA, FEC, or VC, and the sodium salt includes NaClO4, NaPF6, NaBF4, NaFSI, or NaTFSI. [Effects of the Invention]

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses two chemical vapor deposition processes at different temperatures to produce sieve-type carbon. The first chemical vapor deposition process in step 1 rapidly seals the pores at high temperatures (1100-1300°C), preventing the deposited carbon from entering the pore chambers and rapidly shrinking the pore openings to a relatively small size at a relatively fast rate. This rapid shrinkage of the pore openings actually improves the efficiency of pore sealing at the expense of the selectivity of the deposition reaction at the pore openings, resulting in deposited carbon on the periphery of the pore openings. The second chemical vapor deposition process in step 2 is performed at low temperatures (600-800°C) to refine the pore openings to a diameter of less than 0.33 nm. Since the pore openings have already reached a relatively small extent after completing step 1, the second chemical vapor deposition process prevents the second chemical vapor deposition carbon from entering the pores. The low-temperature deposition in step 2 is selective deposition that occurs only at the pore openings and does not result in further deposited carbon outside the pores. 2. By using two chemical vapor deposition processes, the present invention can maintain the original pore size (in the two-step deposition process, none of the deposited carbon enters the pore chambers) while adjusting the pore diameter to less than 0.33 nm, effectively improving the initial Coulomb efficiency of the carbon material and facilitating the commercial application of sieving-type carbon materials. [Brief explanation of the drawings]

[0030] [Figure 1] 1 shows the small-angle X-ray scattering pattern of Example 1. [Figure 2] 1 shows a nitrogen gas adsorption and desorption test diagram for Example 1. [Figure 3] 1 shows a carbon dioxide adsorption and desorption test diagram for Example 1. [Figure 4] 1 shows TEM patterns before and after the first chemical vapor deposition of Example 1. [Figure 5] 1 shows the correlation curve between reaction time and weight gain in the second chemical vapor deposition process of Example 1. [Figure 6] 1 shows TEM patterns of the porous carbon of Example 1 and the sieving-type carbon obtained in Example 1. [Figure 7] 1 shows the initial charge-discharge curve of the sodium ion battery negative electrode of Example 1. [Figure 8] 1 shows the small-angle X-ray scattering pattern of Comparative Example 1. [Figure 9] 1 shows a nitrogen gas adsorption and desorption test diagram for Comparative Example 1. [Figure 10] 1 shows a carbon dioxide adsorption and desorption test diagram for Comparative Example 1. [Figure 11] 1 shows a TEM pattern of the carbon material of Comparative Example 1. [Figure 12] 1 shows the initial charge-discharge curve of the sodium ion battery negative electrode of Comparative Example 1. [Figure 13] 1 shows the small-angle X-ray scattering pattern of Comparative Example 2. [Figure 14] 1 shows a carbon dioxide adsorption and desorption test diagram for Comparative Example 2. [Figure 15] 1 shows a TEM pattern of the carbon material of Comparative Example 2. [Figure 16]1 shows the initial charge-discharge curve of the sodium ion battery negative electrode of Comparative Example 2. [Figure 17] FIG. 1 is a schematic diagram of a two-step chemical vapor deposition process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be described in more detail below with reference to specific examples. It should be understood that the specific examples described here are merely for the purpose of illustrating the present invention and are not intended to limit the present invention.

[0032] Example 1 The method for producing sieved carbon is as follows: The porous carbon with abundant pore structure was placed in a tube furnace after the first chemical vapor deposition to rapidly reduce the pore size. The porous carbon was activated carbon fiber, and the specific surface area was 1420 m2 according to the small angle scattering test. 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 1380 m 2 / g, and the large specific surface area of ​​the porous carbon indicates that it has a large number of pores and a large internal space, so it is a large-pore raw material. Next, argon gas is passed through as a protective gas at a flow rate of 90mL / min, and the temperature is raised to a final temperature of 1200°C at a rate of 10°C / min. At the final temperature of 1200°C, methane gas is passed through at a flow rate of 30mL / min, and the reaction is continued for 25 minutes, causing the pores to rapidly shrink. Step 1: Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., turning off the methane gas, lowering the temperature to 700°C, passing methane gas at a flow rate of 10 mL / min, and reacting continuously for 300 minutes to further refine the pore openings to reduce the diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0033] As shown in Figure 1, the specific surface area of ​​the porous carbon in step 1 measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 1415 m 2 / g, which indicates that none of the deposited carbon enters the pore chambers during the two chemical vapor depositions, achieving the effect of selectively adjusting the pore openings.

[0034] As shown in Figure 2, the specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption in step 1 was 1380 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area is 30 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area is 5 m 2 / g, indicating that after the first chemical vapor deposition, the pore diameter of most of the pores was already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the second chemical vapor deposition, the pore diameter of all pores was smaller than 0.364 nm.

[0035] As shown in Figure 3, the specific surface area measured by carbon dioxide adsorption and desorption of porous carbon in step 1 was 1358 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 600 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 6m 2 / g indicates that after the pore size was rapidly reduced by step 1, the diameter of most of the pores was still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pores were finished by step 2, the diameter of all the pores was smaller than 0.330 nm.

[0036] During the first chemical vapor deposition, the rapidly decomposed carbon source gas was deposited mainly at the pore mouth, with a small amount deposited outside the pores. As shown in Figure 4, the porous carbon surface did not change significantly before and after the first chemical vapor deposition, indicating that there was no excess carbon deposited outside the pores.

[0037] During the second chemical vapor deposition, the decomposition rate of the carbon source gas was slow, and it was deposited selectively at the pore openings, not outside the pores. As shown in Figure 5, in the case of the secondary deposition, the weight gain of the deposited carbon sealed the pore openings until it was less than 0.33 nm. However, even if the reaction time was extended, the weight gain did not increase, indicating that the deposition reaction occurred only at the pore openings.

[0038] As shown in Figure 6, the structure inside the pore channel did not change before and after the two chemical vapor depositions, and the deposited carbon did not enter the pore chamber, which had a selective effect.

[0039] The sieving mold was used to prepare a battery negative electrode, and the preparation method was as follows. The sieved carbon was used as the negative electrode active material, polyvinylidene fluoride (PVDF) as the adhesive, and acetylene black as the conductive agent. The mixture was uniformly mixed in a mass ratio of 90:5:5 with NMP (N-methylpyrrolidone) solvent, applied to an electrode film, placed in a vacuum drying box and dried at 120°C for 12 hours, then roll pressed and punched to obtain sieved carbon negative electrode pieces. A metallic sodium sheet was used as the counter electrode, and 1 mol / L NaPF6 (EC:DEC = 1:1) was used as the electrolyte. The sieved carbon negative electrode pieces obtained above were assembled into a 2032 button cell battery in a glove box, and its electrochemical performance was measured.

[0040] As shown in FIG. 7, the sodium ion battery negative electrode prepared in this example had an initial Coulombic efficiency of 93% and a reversible specific capacity of 354 mAh / g, where the low potential platform specific capacity was found to be 280 mAh / g.

[0041] Example 2 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, i.e., the porous carbon (specific surface area measured by small-angle scattering analysis was 802 m 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 798 m 2Step 1: Put walnut shell porous carbon (as the raw material for the small pores) into a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat it up to a final temperature of 1200°C at a heating rate of 10°C / min. At the final temperature of 1200°C, pass methane gas at a flow rate of 30 mL / min, and react continuously for 25 minutes to rapidly shrink the pores. Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., turning off the methane gas, lowering the temperature to 700°C, passing methane gas at a flow rate of 10 mL / min, and reacting continuously for 300 minutes to further refine the pore openings so that the diameters of all the pore openings are less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0042] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by small-angle X-ray scattering was 802 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering is 800 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0043] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption and was 798 m 2 / g, and after the first chemical vapor deposition, the specific surface area is 15m 2 / g, and after the second chemical vapor deposition, the specific surface area was reduced to 5m 2 / g indicates that after the first chemical vapor deposition, the pore diameter of most of the pores was already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the second chemical vapor deposition, i.e., hole-finishing, the pore diameter of all pores was smaller than 0.364 nm.

[0044] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by carbon dioxide adsorption and desorption and was 780 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 310 m2 / g, and after the second chemical vapor deposition, the specific surface area was 3 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0045] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0046] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 94% and a reversible specific capacity of 278 mAh / g, where the low potential platform specific capacity was 150 mAh / g.

[0047] Example 3 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, resulting in a porous carbon with a rich pore structure (specific surface area of ​​1420 m2 measured by small-angle scattering). 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 1380m 2 Step 1: Place activated carbon fiber (of which the carbon content is 1 / g) in a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat it up to a final temperature of 1300°C at a heating rate of 10°C / min. At the final temperature of 1300°C, pass methane gas at a flow rate of 30 mL / min for 25 minutes to react continuously, thereby rapidly sealing the pores on the porous carbon surface. Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., turning off the methane gas, lowering the temperature to 700°C, passing methane gas at a flow rate of 10 mL / min, and reacting continuously for 300 minutes to further refine the pore openings to reduce the diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0048] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by small angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 1408 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0049] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption to be 1380 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 21 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 5 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.364 nm.

[0050] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by carbon dioxide adsorption and desorption and was 1358 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 520 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 6 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0051] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0052] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 92.5% and a reversible specific capacity of 348 mAh / g, where the low potential platform specific capacity was 272 mAh / g.

[0053] Example 4 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, resulting in a porous carbon with a rich pore structure (specific surface area of ​​1800 m2 measured by small-angle scattering). 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 1802 m 2 Step 1: Place coconut shell activated carbon (coconut shell activated carbon with a flow rate of 90 mL / min) in a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat the furnace at a rate of 10 °C / min to a final temperature of 1200 °C. At the final temperature of 1200 °C, pass methane gas at a flow rate of 30 mL / min for 25 minutes to react continuously, rapidly sealing the pores on the porous carbon surface. Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., turning off the methane gas, lowering the temperature to 800°C, passing methane gas at a flow rate of 10 mL / min, and reacting continuously for 300 minutes to further refine the pore openings to reduce the diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0054] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by small-angle X-ray scattering was 1800 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 1760 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0055] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption to be 1802 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 45 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 4.8 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.364 nm.

[0056] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by carbon dioxide adsorption and desorption and was 1770 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 820 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 7 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0057] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0058] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 94% and a reversible specific capacity of 402 mAh / g, where the low potential platform specific capacity was 325 mAh / g.

[0059] Example 5 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, resulting in a porous carbon with a rich pore structure (specific surface area of ​​1650 m2 measured by small-angle scattering). 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 1632 m 2 Step 1: Place the bamboo-based activated carbon (e.g., bamboo-based activated carbon (e.g., 0.1g / g) in a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat it up to a final temperature of 1200°C at a heating rate of 10°C / min. At the final temperature of 1200°C, pass methane gas at a flow rate of 30 mL / min for 15 minutes, and rapidly seal the pores on the porous carbon surface. Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., turning off the methane gas, lowering the temperature to 800°C, passing methane gas at a flow rate of 10 mL / min, and reacting continuously for 300 minutes to further refine the pore openings to reduce the diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0060] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by small angle X-ray scattering was 1650 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 1642 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0061] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption to be 1632 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 68 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 5 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.364 nm.

[0062] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by carbon dioxide adsorption and desorption and was 1624 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 614 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 5 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0063] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0064] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 93% and a reversible specific capacity of 367 mAh / g, where the low potential platform specific capacity was 290 mAh / g.

[0065] Example 6 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, resulting in a porous carbon with a rich pore structure (specific surface area of ​​2140 m2 measured by small-angle scattering). 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 2125 m 2 Step 1: Place the activated carbon (petroleum coke-based activated carbon (p / g)) in a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat it at a rate of 10 °C / min to a final temperature of 1200 °C. At the final temperature of 1200 °C, pass methane gas at a flow rate of 30 mL / min for 25 minutes to react continuously, and rapidly seal the pores on the porous carbon surface. Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., turning off the methane gas, lowering the temperature to 800°C, passing methane gas at a flow rate of 10 mL / min, and reacting continuously for 240 minutes to further refine the pore openings to reduce the diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0066] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by small-angle X-ray scattering and was 2140 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 2122 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0067] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption to be 2125 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 75 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 5 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the pore finishing in step 2, the pore size of all pores is smaller than 0.364 nm.

[0068] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by carbon dioxide adsorption and desorption was 2100 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 821 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 5 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0069] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0070] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 94% and a reversible specific capacity of 425 mAh / g, where the low potential platform specific capacity was 350 mAh / g.

[0071] Example 7 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, resulting in a porous carbon with a rich pore structure (specific surface area of ​​1800 m2 measured by small-angle scattering). 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 1802 m 2Step 1: Place coconut shell activated carbon (coconut shell activated carbon with a flow rate of 90 mL / min) in a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat the furnace at a rate of 10 °C / min to a final temperature of 1200 °C. At the final temperature of 1200 °C, pass natural gas at a flow rate of 30 mL / min for 25 minutes to react continuously, rapidly sealing the pores on the porous carbon surface. Step 2: finishing the hole opening by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., cutting off the natural gas, lowering the temperature to 800°C, passing natural gas at a flow rate of 10 mL / min, and reacting continuously for 240 minutes to further refine the hole opening to reduce the hole opening diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0072] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by small-angle X-ray scattering was 1800 m 2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 1795 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0073] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption to be 1802 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 76 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 3.5 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.364 nm.

[0074] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by carbon dioxide adsorption and desorption and was 1770 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 350 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 3 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0075] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0076] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 95% and a reversible specific capacity of 410 mAh / g, where the low potential platform specific capacity was 330 mAh / g.

[0077] Example 8 The method for producing sieved carbon is as follows: The first chemical vapor deposition rapidly reduced the pore size, resulting in a porous carbon with a rich pore structure (specific surface area of ​​1800 m2 measured by small-angle scattering). 2 / g, and the specific surface area measured by nitrogen gas adsorption and desorption tests was 1802 m 2 Step 1: Place coconut shell activated carbon (coconut shell activated carbon with a flow rate of 90 mL / min) in a tubular furnace, pass argon gas as a protective gas at a flow rate of 90 mL / min, and heat the furnace to a final temperature of 1200°C at a heating rate of 10°C / min. At the final temperature of 1200°C, pass ethane at a flow rate of 30 mL / min for 25 minutes to react continuously, rapidly sealing the pores on the porous carbon surface. Step 2: Finishing the pore openings by a second chemical vapor deposition to reduce the diameter to less than 0.33 nm, i.e., cutting off the ethane, lowering the temperature to 800°C, passing ethane gas at a flow rate of 10 mL / min, and reacting continuously for 240 minutes to further refine the pore openings to reduce the diameter to less than 0.33 nm; and step 3 of stopping the carbon source gas and lowering the temperature to room temperature at a rate of 10°C / min to obtain the sieved carbon.

[0078] In this example, the specific surface area of ​​the porous carbon used in step 1 measured by small-angle X-ray scattering was 1800 m2 / g, and the specific surface area of ​​the sieved carbon obtained in step 3 measured by small-angle X-ray scattering was 1772 m 2 / g, which indicates that the carbon deposited by the two chemical vapor depositions does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0079] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by nitrogen gas adsorption and desorption to be 1802 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 46 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 3.9 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after the pore finishing in step 2, the pore size of all pores is smaller than 0.364 nm.

[0080] In this example, the specific surface area of ​​the porous carbon used in step 1 was measured by carbon dioxide adsorption and desorption and was 1770 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 632 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 4 m 2 / g indicates that after the rapid pore shrinkage in step 1, the pore diameter of most pores is still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the pore finishing in step 2, the pore diameter of all pores is smaller than 0.330 nm.

[0081] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0082] The sodium ion battery negative electrode prepared in this example had an initial coulombic efficiency of 93.5% and a reversible specific capacity of 408 mAh / g, where the low potential platform specific capacity was 312 mAh / g.

[0083] (Comparative Example 1) Comparing this comparative example with Example 1, the difference was that in Comparative Example 1, step 2 was not performed.

[0084] The small-angle X-ray scattering pattern of the carbon material obtained in Comparative Example 1 is shown in FIG. 8. The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after reducing the pore size by the above steps was 1418 m2 as measured by small angle X-ray scattering. 2 / g, indicating that after rapid deposition at high temperature, the pore structure of the material does not change and the deposited carbon does not enter the pore chambers to shrink the pore openings.

[0085] The nitrogen gas adsorption and desorption test diagram of the carbon material provided in Comparative Example 1 is shown in FIG. 9. The specific surface area measured by nitrogen gas adsorption and desorption of the porous carbon was 1380 m 2 / g, and the specific surface area of ​​the carbon material after reducing the pore size by the above steps is 30 m 2 / g, and most of the pore diameters were already smaller than 0.364 nm (the molecular dynamic diameter of N2).

[0086] The carbon dioxide adsorption and desorption test diagram of the carbon material provided in Comparative Example 1 is shown in FIG. 10. The specific surface area measured by carbon dioxide adsorption and desorption of the porous carbon was 1358 m 2 / g, and the specific surface area of ​​the carbon material after reducing the pore size by the above steps is 600 m 2 / g, indicating that after the rapid reduction in pore size by Step 1, the majority of pore diameters were still larger than 0.330 nm (the molecular kinetic diameter of CO2).

[0087] The TEM pattern of the carbon material provided by Comparative Example 1 is shown in Figure 11. It can be seen that the structure inside the pores remains unchanged before and after reducing the pore size, and the deposited carbon does not enter the pore chambers, achieving a selective effect.

[0088] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0089] The initial charge-discharge curve of the sodium ion battery negative electrode prepared in this comparative example is shown in FIG. 12. It was found that the prepared sodium ion battery sieved carbon negative electrode material had an initial Coulombic efficiency of only 78% and a reversible specific capacity of 258 mAh / g, where the low potential platform specific capacity was 101 mAh / g.

[0090] (Comparative Example 2) Comparing this comparative example with Example 1, the difference was that in Comparative Example 2, the continuous reaction time when performing Step 1 was 1 hour, and Step 2 was not performed.

[0091] As shown in Figure 13, the specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after treatment by the steps of Comparative Example 2 was 689 m as measured by small angle X-ray scattering. 2 / g indicates that after rapid deposition at high temperature, the pore structure of the material changes, and some of the deposited carbon that shrinks the pore openings enters the pores, filling them and reducing the pore volume.

[0092] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and the specific surface area of ​​the carbon material after partially shrinking the pore size through the above steps is 18m 2 / g indicated that the pore diameter of most of the pores was already smaller than 0.364 nm (the molecular dynamic diameter of N2).

[0093] As shown in Figure 14, the specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and the specific surface area of ​​the carbon material after partially shrinking the pore size by the above steps is 500 m 2 / g indicates that some pore sizes are still larger than 0.330 nm (the molecular dynamic diameter of CO2), and at the same time, the interior of the pore structure is filled with deposited carbon, resulting in a decrease in pore volume and an obvious decrease in internal specific surface area.

[0094] The TEM patterns before and after the preparation of porous carbon are shown in Figure 15. It was found that the structure inside the pores changed obviously before and after the pore mouth shrinkage, and part of the deposited carbon entered the pore chamber, resulting in low deposition selectivity.

[0095] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0096] The initial charge-discharge curve of the sodium ion battery negative electrode prepared in this comparative example is shown in FIG. 16. It was found that the carbon material obtained in this comparative example had an initial Coulombic efficiency of only 45%, a reversible specific capacity of 210 mAh / g, and a low potential platform specific capacity of 54 mAh / g.

[0097] (Comparative Example 3) Comparing this comparative example with Example 1, the difference was that in Comparative Example 3, the continuous reaction time when performing Step 1 was 2 hours, and Step 2 was not performed.

[0098] The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after partial shrinkage of the pore size by the above steps was 294 m as measured by small angle X-ray scattering. 2 / g indicates that after rapid deposition at high temperature, the pore structure of the material changes, and some of the deposited carbon that shrinks the pore openings enters the pores, filling them and reducing the pore volume.

[0099] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and the specific surface area of ​​the carbon material after partially shrinking the pore size through the above steps is 7m 2 / g indicated that the pore diameter of most of the pores was already smaller than 0.364 nm (the molecular dynamic diameter of N2).

[0100] The specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and the specific surface area of ​​the carbon material after partially shrinking the pore size through the above steps is 16 m 2 / g indicated that only very few pore sizes were larger than 0.330 nm (the molecular dynamic diameter of CO2).

[0101] Similar to Comparative Example 2, the internal structure changed obviously before and after the pore mouth contraction, and a large amount of deposited carbon entered the pore chamber, and a large amount of the pore structure disappeared.

[0102] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0103] The sodium-ion battery negative electrode prepared in this comparative example had an initial coulombic efficiency of only 45% and a reversible specific capacity of 170 mAh / g, where the low potential platform specific capacity was 34 mAh / g.

[0104] Comparative Example 4 The difference between this comparative example and Example 1 is that in Comparative Example 4, the first chemical vapor deposition temperature in Step 1 was 900°C and the reaction was continued for 25 minutes, while Step 2 was the same as in Example 1, and the second chemical vapor deposition temperature was 700°C and the reaction was continued for 300 minutes.

[0105] The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after partial shrinkage of the pore size by the above steps was 1410 m as measured by small angle X-ray scattering. 2 / g indicates that the deposited carbon that shrinks the pore mouth does not enter the pore chamber, achieving the effect of selectively adjusting the pore mouth.

[0106] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area of ​​the carbon material is 500 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area is 21 m 2 / g indicates that after the step 1 treatment, the majority of pore diameters are still larger than 0.364 nm (the molecular dynamic diameter of N2), and after the step 2 treatment, the pore diameter of some pores is still larger than 0.364 nm.

[0107] The specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area of ​​the carbon material is 900 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area is 40 m 2 / g indicates that after the step 1 treatment, the majority of pore diameters were still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the step 2 treatment, the pore diameter of some pores was still larger than 0.330 nm.

[0108] Similar to Comparative Example 1, the internal structure remained unchanged before and after the pore mouth contraction, and the deposited carbon did not enter the pore chamber, achieving a selective effect.

[0109] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0110] The sodium-ion battery negative electrode prepared in this comparative example had an initial coulombic efficiency of only 82% and a reversible specific capacity of 304 mAh / g, where the low potential platform specific capacity was 230 mAh / g.

[0111] (Comparative Example 5) The difference between this comparative example and Example 1 is that in Comparative Example 5, the first chemical vapor deposition temperature in Step 1 was 1000°C and the reaction was continued for 25 minutes, while Step 2 was the same as in Example 1, and the second chemical vapor deposition temperature was 700°C and the reaction was continued for 300 minutes.

[0112] The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material obtained after the above steps was 1412 m as measured by small-angle X-ray scattering. 2 / g, which indicates that the carbon deposited by the two-step chemical vapor deposition process does not enter the pore chambers, achieving the effect of selectively adjusting the pore openings.

[0113] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 395 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 16 m 2 / g, and after the first chemical vapor deposition, some pore sizes were still larger than 0.364 nm (the molecular dynamic diameter of N2). After the second chemical vapor deposition, the pore sizes of a small number of pores were still larger than 0.364 nm.

[0114] The specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 647 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 29 m 2 / g indicates that after the treatment in step 1, the pore opening diameter of most of the carbon material obtained is still larger than 0.330 nm (the molecular dynamic diameter of CO), and after the treatment in step 2, the pore opening size of a small amount of pores is still larger than 0.330 nm.

[0115] After two chemical vapor depositions, similar to Comparative Example 1, the internal structure remained unchanged, and the deposited carbon did not enter the pores, achieving a selective effect.

[0116] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0117] The sodium ion battery negative electrode prepared in this comparative example had an initial coulombic efficiency of 87% and a reversible specific capacity of 332 mAh / g, where the low potential platform specific capacity was 253 mAh / g.

[0118] (Comparative Example 6) Comparing this comparative example with Example 1, step 1 was the same as in Example 1, except that the second chemical vapor deposition in step 2 was carried out at a temperature of 700° C. for 2 hours.

[0119] The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after treatment by the steps of Comparative Example 6 measured by small angle X-ray scattering was 1420 m 2 / g indicates that the deposited carbon that shrinks the pore mouth does not enter the pore chamber, achieving the effect of selectively adjusting the pore mouth.

[0120] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 35 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 16 m 2 / g indicates that after step 1, the majority of pore sizes are already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after step 2, a small number of pores still have pore sizes larger than 0.364 nm.

[0121] The specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and after the first chemical vapor deposition, the specific surface area was 632 m 2 / g, and after the second chemical vapor deposition, the specific surface area was 241 m 2 / g indicates that after the step 1 treatment, the majority of pore diameters were still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after the step 2 treatment, a significant portion of the pores still had opening sizes larger than 0.330 nm.

[0122] Similar to Comparative Example 1, the internal structure remains unchanged after the two chemical vapor depositions, and the deposited carbon does not enter the pores, achieving a selective effect.

[0123] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0124] The sodium ion battery negative electrode prepared in this comparative example had an initial coulombic efficiency of 79% and a reversible specific capacity of 301 mAh / g, where the low potential platform specific capacity was 212 mAh / g.

[0125] (Comparative Example 7) Comparing this comparative example with Example 1, step 1 was the same as Example 1, except that the second chemical vapor deposition temperature in step 2 was 900°C and the reaction was continued for 5 hours.

[0126] The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after partial shrinkage of the pore size by the above steps was 1023 m as measured by small angle X-ray scattering. 2 / g indicates that part of the deposited carbon for shrinking the pore mouth enters the pore interior and does not achieve the effect of selectively adjusting the pore mouth.

[0127] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area was 37 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area is 3 m 2 / g, and after step 1, the pore opening size of most of the pores was already smaller than 0.364 nm (the molecular dynamic diameter of N2), and after step 2, the pore opening size of all pores was smaller than 0.364 nm.

[0128] The specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area was 612 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area is 4 m 2 / g, and after step 1, the pore diameter of most pores was still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after step 2, the pore diameter of all pores was smaller than 0.330 nm.

[0129] Similar to Comparative Example 2, the internal structure changed before and after the pore mouth contraction, and the deposited carbon entered the pore chamber, and no selective effect was achieved.

[0130] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0131] The sodium ion battery negative electrode prepared in this comparative example had an initial Coulombic efficiency of 73%, and all pore diameters were smaller than 0.330 nm. However, due to excessive carbon deposition, the initial Coulombic efficiency was also reduced, and the reversible specific capacity was 278 mAh / g, where the low potential platform specific capacity was 139 mAh / g.

[0132] (Comparative Example 8) Comparing this comparative example with Example 1, step 1 was the same as Example 1, except that the second chemical vapor deposition temperature in step 2 was 500°C and the reaction was continued for 5 hours.

[0133] The specific surface area of ​​the porous carbon measured by small-angle X-ray scattering was 1420 m 2 / g, and the specific surface area of ​​the carbon material after partial shrinkage of the pore size by the above steps was 1407 m as measured by small angle X-ray scattering. 2 / g indicated that deposited carbon did not enter the pore chambers to shrink the pore mouths.

[0134] The specific surface area of ​​the porous carbon measured by nitrogen gas adsorption and desorption was 1380 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area was 37 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area was 29 m 2 / g indicated that after the treatment in step 1, the majority of the pore size was already smaller than 0.364 nm (the molecular dynamic diameter of N2).

[0135] The specific surface area of ​​porous carbon measured by carbon dioxide adsorption and desorption was 1358 m 2 / g, and after the first chemical vapor deposition in step 1, the specific surface area was 596 m 2 / g, and after the second chemical vapor deposition in step 2, the specific surface area was 274 m 2 / g, indicating that after step 1, the pore diameter of most pores was still larger than 0.330 nm (the molecular dynamic diameter of CO2), and after step 2, the pore diameter of some pores was still larger than 0.330 nm, and the pore sealing effect of the low-temperature deposition process was relatively low, and the pore size could not be reduced efficiently.

[0136] Using the same method as in Example 1, a 2032 button cell was assembled and its electrochemical performance was measured.

[0137] The sodium ion battery negative electrode prepared in this comparative example had an initial coulombic efficiency of 82% and a reversible specific capacity of 285 mAh / g, where the low potential platform specific capacity was 124 mAh / g.

[0138] It should be noted that the above description is merely a preferred embodiment of the present invention, and that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of the claims of the present invention.

[0139] (Addendum) (Appendix 1) A method for producing sieved carbon, comprising: Step 1: rapidly reducing the pore size by a first chemical vapor deposition, i.e., placing the porous carbon in a chemical vapor deposition apparatus, passing a protective gas at a predetermined flow rate, and heating to 1100-1300°C, then passing a first carbon source gas at a predetermined flow rate so that the flow rate is 10-500 mL / min, and performing the first heat-keeping time of 0-30 min, but not 0 min; Step 2: finishing the hole opening by a second chemical vapor deposition until the diameter is smaller than 0.33 nm, i.e., after the first heat-keeping is completed, the first carbon source gas is cut off, the temperature is lowered to 600 to 800°C, a second carbon source gas is passed through at a predetermined flow rate so that the flow rate is 10 mL / min or more, and a second heat-keeping time is set to 3 hours or more; and step 3 of stopping the second carbon source gas and lowering the temperature to room temperature at a predetermined temperature drop rate to obtain the sieved carbon. A manufacturing method characterized by:

[0140] (Appendix 2) The porous carbon in step 1 is walnut shell-based porous carbon, bamboo-based activated carbon, coconut shell-based porous carbon, peanut shell-based porous carbon, petroleum coke-based porous carbon, needle coke-based porous carbon, or activated carbon fiber. 2. A method for producing sieved carbon according to claim 1,

[0141] (Appendix 3) the first carbon source gas in step 1 is methane, benzene vapor, toluene vapor, xylene vapor, ethane, propane, or acetylene; The second carbon source gas in step 2 is methane, benzene vapor, toluene vapor, xylene vapor, ethane, propane, or acetylene. 2. A method for producing sieved carbon according to claim 1,

[0142] (Appendix 4) After completing step 1, the specific surface area measured by N2 adsorption and desorption tests was 0-100 m 2 / g, and the specific surface area measured by CO2 adsorption and desorption tests is 100-2000 m 2 / g, and the pore diameter is 0.33~0.364nm. 2. A method for producing sieved carbon according to claim 1,

[0143] (Appendix 5) After the hole openings are completed in step 2, the hole opening sizes of all holes are closed until CO2 cannot enter, and the specific surface area measured by CO2 adsorption and desorption tests is 0 to 10 m 2 / g, and the pore diameters are all less than 0.33 nm. 2. A method for producing sieved carbon according to claim 1,

[0144] (Appendix 6) The pore size of the sieved carbon obtained in step 3 is identical to the pore size of the porous carbon in step 1. 2. A method for producing sieved carbon according to claim 1,

[0145] (Appendix 7) A sieving carbon obtained by the production method according to any one of Supplementary Notes 1 to 6, The primary carbon deposit is deposited on the pore openings and the periphery of the pore openings of the sieving carbon, and the secondary carbon deposit is deposited at the pore opening positions on the surface of the primary carbon deposit. Neither of the two deposited carbons enters the pore chambers. The diameter of the pore openings after the two depositions is smaller than 0.33 nm. The specific surface area of ​​the sieving carbon determined by CO2 adsorption and desorption tests is 0-10 m. 2 / g, A sieving carbon characterized by:

[0146] (Appendix 8) The pore diameter of the sieving carbon is 0.5 to 10 nm. 8. The sieving carbon according to claim 7,

[0147] (Appendix 9) Use of the sieved carbon according to claim 7 in a battery anode.

Claims

1. A method for producing sieved carbon, comprising: Step 1: rapidly reducing the pore size by a first chemical vapor deposition, i.e., placing the porous carbon in a chemical vapor deposition apparatus, passing a protective gas at a predetermined flow rate, and heating the temperature to 1100-1300°C, and then passing a first carbon source gas at a predetermined flow rate of 10-500 mL / min, and performing the first heat-keeping time of 0-30 min, but not 0 min; Step 2: finishing the hole opening by a second chemical vapor deposition until the diameter is smaller than 0.33 nm, i.e., after the first heat-keeping is completed, the first carbon source gas is cut off, the temperature is lowered to 600 to 800°C, a second carbon source gas is passed through at a predetermined flow rate so that the flow rate is 10 mL / min or more, and a second heat-keeping time is set to 3 hours or more; and step 3: stopping the second carbon source gas and lowering the temperature to room temperature at a predetermined temperature drop rate to obtain the sieved carbon. A manufacturing method characterized by:

2. The porous carbon in step 1 is walnut shell-based porous carbon, bamboo-based activated carbon, coconut shell-based porous carbon, peanut shell-based porous carbon, petroleum coke-based porous carbon, needle coke-based porous carbon, or activated carbon fiber.

2. The method for producing sieving carbon according to claim 1 .

3. the first carbon source gas in step 1 is methane, benzene vapor, toluene vapor, xylene vapor, ethane, propane, or acetylene; The second carbon source gas in step 2 is methane, benzene vapor, toluene vapor, xylene vapor, ethane, propane, or acetylene.

2. The method for producing sieving carbon according to claim 1 .

4. After completing step 1, ２ The specific surface area measured by adsorption and desorption tests is 0 to 100 m ２ / g, and CO ２ The specific surface area measured by adsorption and desorption tests is 100 to 2000 m ２ / g, and the pore diameter is 0.33 to 0.364 nm.

2. The method for producing sieving carbon according to claim 1 .

5. After the hole openings are finished in step 2, the hole opening sizes of all holes are CO ２ is closed until CO ２ The specific surface area measured by adsorption and desorption tests is 0 to 10 m ２ / g, and the pore diameters are all smaller than 0.33 nm.

2. The method for producing sieving carbon according to claim 1 .

6. The pore size of the sieved carbon obtained in step 3 is identical to the pore size of the porous carbon in step 1.

2. The method for producing sieving carbon according to claim 1 .

7. A sieving carbon obtained by the production method according to any one of claims 1 to 6, The primary carbon deposit is deposited on the pore openings and the periphery of the pore openings of the sieving carbon, and the secondary carbon deposit is deposited at the pore opening positions on the surface of the primary carbon deposit. Neither of the two deposited carbons enters the pore chambers, and the diameters of the pore openings after the two depositions are both smaller than 0.33 nm. ２ The specific surface area measured by adsorption and desorption tests is 0 to 10 m ２ / g, A sieving carbon characterized by:

8. The pore diameter of the sieving carbon is 0.5 to 10 nm; 8. Sieving carbon according to claim 7.

9. Use of the sieved carbon according to claim 7 in a battery negative electrode.

Images