Porous carbon having oriented slit pores and method of making and use thereof

Abstract

This invention belongs to the field of porous carbon materials and lithium-ion battery technology, specifically relating to a porous carbon with directional slit pores, its preparation method, and its applications. This invention uses easily graphitizable carbon materials with layered molecular orientation as the carbon source. First, it performs mild and selective pre-oxidation, introducing oxygen-containing functional groups at defect sites and interlayer regions of the carbon material. Subsequently, the pre-oxidized carbon material is subjected to high-temperature activation treatment under a weak oxidizing atmosphere, preferentially etching the pre-oxidized and weakened regions to form directional slit pores arranged along the carbon layer direction. The obtained porous carbon has a D50 particle size of 5 μm to 50 μm and a specific surface area of ​​500 m². 2 / g~2500m 2 / g, with a highly anisotropic pore structure. This porous carbon can serve as an excellent support material for silicon-carbon anodes, as its slit-pore structure provides a rapid transport channel for lithium ions, significantly improving the electrochemical performance of silicon-carbon anode materials.

Description

Technical Field

[0001] This invention belongs to the field of porous carbon anode materials and lithium-ion battery technology, specifically relating to a porous carbon with directional slit pores, its preparation method and application. Background Technology

[0002] Porous carbon materials, especially activated carbon with high specific surface area, are widely used in energy storage, adsorption separation, and catalysis due to their excellent electrical conductivity, chemical stability, and abundant pore structure. In the field of lithium-ion batteries, porous carbon is often used as a carrier for active materials such as silicon and sulfur to mitigate their volume changes during charging and discharging and improve the conductivity of the electrodes.

[0003] Traditional activated carbon preparation methods typically use biomass, coal, and polymers as precursors, directly producing activated carbon through physical or chemical activation. For example, physical activation mainly utilizes water vapor or CO2; chemical activation mainly utilizes KOH or ZnCl2. The porous carbon obtained by these methods often has an isotropic sponge-like or random worm-like micropore structure, with tortuous channels and poor connectivity. When such traditional porous carbon is used as a silicon-carbon anode support, although it can buffer the volume effect of silicon to some extent, its tortuous channels severely restrict the rapid transport of lithium ions, resulting in rapid capacity decay and poor rate performance of the electrode material under high-rate performance and high-current charge-discharge conditions.

[0004] To obtain more regular pore structures, researchers have developed template methods, such as hard templates or soft templates. However, template methods are complex and costly, and template removal during post-processing may introduce impurities or damage the carbon skeleton, making large-scale industrial production difficult. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a porous carbon with directional slit pores, its preparation method, and its applications. Through a synergistic design of "pre-oxidation labeling" and "directional activation," this invention achieves, for the first time, precise and selective etching of interlayer regions in easily graphitized carbon sources. This successfully prepares highly anisotropic directional slit pores arranged along the carbon layer direction, solving the problems of isotropic random pores with tortuous channels and poor connectivity in porous carbon obtained by existing activation methods, as well as the high cost of existing template methods and the potential for template removal to introduce impurities or damage the carbon framework, thus affecting electrode material performance.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] The first aspect of this invention provides a method for preparing porous carbon with directional slit pores, comprising the following steps:

[0008] Using easily graphitizable carbon materials with layered molecular orientation as carbon sources, the carbon sources are selectively pre-oxidized to obtain pre-oxidized carbon materials. The pre-oxidized carbon materials are then activated in an oxidizing atmosphere and cooled to obtain porous carbon with anisotropic oriented slit pores arranged along the carbon layer direction. The selective pre-oxidation treatment involves selectively introducing oxygen-containing functional groups at crystal defect sites, grain boundaries, and graphite microcrystal edges of the carbon source. The oxidizing atmosphere is a mixture of one or more of water vapor and carbon dioxide with an inert gas. The activation temperature is 700℃~1100℃.

[0009] In this invention, the oxidizing atmosphere is a mixture of one or more of water vapor and carbon dioxide with an inert gas; wherein, water vapor and carbon dioxide are weak oxidants, which can remove amorphous carbon while preserving crystalline carbon as much as possible from being destroyed.

[0010] In this invention, the activation temperature is 700℃~1100℃; too high a temperature may damage the crystalline carbon, and too low a temperature may result in poor pore-forming effect.

[0011] In this invention, the mild selective pre-oxidation treatment is an oxidation process that selectively introduces oxygen-containing functional groups at crystal defect sites, grain boundaries, and graphite crystallite edges of easily graphitizable carbon raw materials without significantly destroying their overall layered framework structure. The key conditions for selectively introducing oxygen-containing functional groups are the oxidant and temperature. Excessive oxidation intensity, such as using a strong oxidant or high temperature, will cause all carbon structures (including crystalline carbon) to be oxidized; insufficient oxidation intensity will not achieve the desired pre-oxidation effect. Therefore, the preferred conditions of this invention are: an oxidation atmosphere consisting of one or more of water vapor and carbon dioxide mixed with an inert gas; and an activation treatment temperature of 700℃ to 1100℃.

[0012] This invention involves high-temperature activation of pre-oxidized carbon materials under a weak oxidizing atmosphere, followed by cooling to obtain porous carbon with directional slit pores. The preparation method of this invention can simply and efficiently utilize the layered structure of easily graphitizable carbon sources to prepare porous carbon with anisotropic pore height.

[0013] Preferably, the selective pre-oxidation treatment is liquid-phase pre-oxidation or gas-phase pre-oxidation; the first oxidant used in the liquid-phase pre-oxidation is a solution of one or more of nitric acid, sulfuric acid, hydrogen peroxide, potassium permanganate and hypochlorous acid; the temperature of the liquid-phase pre-oxidation is 50℃~120℃.

[0014] In this invention, the preferred temperature for liquid phase pre-oxidation is 50℃ to 120℃; excessively high temperatures may cause crystalline carbon to be oxidized; excessively low temperatures may cause amorphous carbon to be incompletely oxidized, affecting the subsequent activation etching effect.

[0015] More preferably, the first oxidant is a 65wt% nitric acid solution, a 30wt% hydrogen peroxide solution, or a 5wt% KMnO4 dilute sulfuric acid solution; the ratio of the first oxidant to the carbon source is 200mL:15g~25g.

[0016] The second oxidant used in the gas-phase pre-oxidation is one or more of air, oxygen, and ozone mixed with an inert gas; the temperature of the gas-phase pre-oxidation is 100℃~400℃.

[0017] More preferably, the second oxidant is air or a mixture of ozone and argon; when the second oxidant is air, the air flow rate is 80 mL / min to 100 mL / min; when the second oxidant is a mixture of ozone and argon, the ozone concentration is 100 g / m³. 3 ±5g / m 3 .

[0018] Preferably, the specific operation for liquid-phase pre-oxidation of the carbon source is as follows:

[0019] The carbon source and the first oxidant are subjected to liquid-phase pre-oxidation at 50℃~120℃ to obtain pre-oxidized carbon material.

[0020] Preferably, the specific operation for gas-phase pre-oxidation of the carbon source is as follows:

[0021] The carbon source is subjected to gas-phase pre-oxidation at 100℃~400℃ under a second oxidant atmosphere to obtain pre-oxidized carbon material.

[0022] Preferably, the selective pre-oxidation treatment time is 0.5h to 10h; the activation treatment time is 0.5h to 5h.

[0023] Preferably, the easily graphitized carbon material is one or more of needle coke, petroleum coke, pitch coke, mesophase carbon microspheres, and graphite.

[0024] Preferably, the D50 particle size of the easily graphitized carbon material is 10 μm to 40 μm;

[0025] Preferably, the oxygen-containing functional group is a carboxyl group, hydroxyl group, carbonyl group, epoxy group, quinone group, lactone group, ether group or anhydride group.

[0026] The second aspect of the present invention provides a porous carbon with directional slit pores, which is prepared by the method for preparing porous carbon with directional slit pores described in the first aspect.

[0027] Preferably, the porous carbon has a D50 particle size of 5 μm to 50 μm and a specific surface area of ​​500 m². 2 / g~2500m 2 / g; the directional slit pores of the porous carbon are slit-shaped pores arranged along the orientation of carbon layered molecules; the pore walls of the directional slit pores are composed of graphitized carbon layers, which have good electronic conductivity.

[0028] The third aspect of the present invention provides the application of porous carbon with directional slit pores in the preparation of silicon-carbon anode materials for lithium-ion batteries. The silicon-carbon anode material for lithium-ion batteries includes silicon-based materials and the porous carbon with directional slit pores described in the second aspect. The silicon-based materials are loaded in and on the surface of the porous carbon with directional slit pores.

[0029] The lithium-ion battery silicon-carbon anode material further includes a solvent and a binder. The preparation method of the lithium-ion battery silicon-carbon anode material is as follows:

[0030] A silicon-based material is loaded into the directional slit pores and surface of the porous carbon with directional slit pores. Then, a solvent and binder are added, and the mixture is ball-milled, coated, dried, and rolled to prepare a silicon-carbon anode sheet for lithium-ion batteries. The silicon-based material is nano-silicon powder.

[0031] This invention provides the application of the above-mentioned porous carbon material in lithium-ion batteries, particularly as a silicon-carbon anode support material, to solve the problems of volume expansion and low intrinsic conductivity of silicon anodes, while providing a fast ion transport channel, thereby significantly improving the rate performance and cycle stability of the battery.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. This invention, through the synergistic design of "pre-oxidation labeling" and "directional activation," achieves for the first time precise and selective etching of interlayer regions in easily graphitized carbon sources, successfully preparing highly anisotropic directional slit pores aligned along the carbon layer direction. This is fundamentally different from the random and tortuous pore structure of traditional activated carbon, solving the problems of isotropic random pores with tortuous channels and poor connectivity in porous carbon obtained by existing activation methods, as well as the high cost of existing template methods and the potential for template removal to introduce impurities or damage the carbon skeleton, thus affecting the performance of electrode materials.

[0034] 2. This invention cleverly utilizes the structural characteristics of easily graphitized carbon raw materials, achieving precise control over pore location and channel orientation through a two-step method (pre-oxidation + weak oxidation activation). This method eliminates the need for complex templates, features a simple process flow, mild conditions, and low cost, making it highly suitable for large-scale industrial production.

[0035] 3. When this porous carbon is used as a silicon-carbon anode support, it exhibits excellent electrochemical performance, specifically: the well-developed interlayer pores provide ample buffer space for the huge volume expansion (~300%) of silicon particles during charging and discharging, maintaining the integrity of the electrode structure and extending cycle life; the oriented slit channels provide a near-linear rapid diffusion path for lithium ions, greatly reducing ion transport resistance and thus endowing the electrode material with excellent rate performance; the pore walls themselves are composed of graphitized carbon layers with good conductivity and are in close contact with silicon materials, forming a stable three-dimensional conductive network, ensuring the high conductivity of the electrode.

[0036] 4. By adjusting the degree of pre-oxidation (temperature, time, oxidant concentration) and activation process parameters, this invention can precisely control the specific surface area, pore volume, and slit size of the final product to meet the needs of different application scenarios. Attached Figure Description

[0037] Figure 1 This is a scanning electron microscope image of the porous carbon with directional slit pores prepared in Example 1 of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Some easily graphitizable carbon raw materials with layered structures, such as needle coke and mesophase carbon microspheres, are composed of highly oriented graphite microcrystals and contain numerous grain boundaries and interlayer gaps. If pores can be preferentially created in these natural interlayer regions, it is possible to form slit-shaped pores with oriented channels. This structure is similar to a "molecular-level highway," providing extremely low transport resistance for ions in the direction parallel to the carbon layers. However, conventional activation methods act randomly and uniformly, failing to precisely identify and preferentially etch these interlayer regions, ultimately resulting in isotropic random pores.

[0041] To obtain more regular pore structures, researchers have developed template methods, such as hard templates or soft templates. However, template methods are complex and costly, and template removal during post-processing may introduce impurities or damage the carbon skeleton, making large-scale industrial production difficult.

[0042] The technical solution of the present invention will be further described below through specific embodiments.

[0043] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0044] Example 1

[0045] A method for preparing porous carbon with directional slit pores includes the following steps:

[0046] Raw material: petroleum coke, D50=20μm.

[0047] Liquid-phase pre-oxidation treatment: Weigh 20g of petroleum coke powder and slowly add it to 200mL of 65% concentrated nitric acid solution. Stir and reflux the mixture in an 80℃ water bath for 6 hours. After the reaction is complete, cool and filter the mixture. Wash the filtrate with deionized water until it is neutral. Finally, dry the filtrate under vacuum at 120℃ for 12 hours to obtain pre-oxidized petroleum coke.

[0048] Activation treatment: The pre-oxidized petroleum coke was transferred to a high-temperature activation furnace and heated to 900°C at a rate of 5°C / min under a mixed atmosphere of nitrogen and carbon dioxide (volume ratio of nitrogen to carbon dioxide 1:1), and held at that temperature for 2 hours. After the reaction was completed, it was cooled to room temperature under nitrogen protection to obtain porous carbon with directional slit pores, denoted as A1. A scanning electron microscope image of the porous carbon with directional slit pores from Example 1 is shown below. Figure 1 As shown.

[0049] A method for preparing a silicon-carbon composite anode material includes the following steps:

[0050] Raw materials: Porous carbon A1 with directional slit pores prepared in Example 1 and nano-silica powder, in a mass ratio of 6:4. The D50 particle size of porous carbon A1 is 18 μm.

[0051] The porous carbon A1 with directional slit pores prepared in Example 1 was deposited with nano-silicon powder into the pores of the porous carbon A1 in a fluidized bed using CVD to obtain a composite powder. The composite powder, conductive agent acetylene black, and binder sodium carboxymethyl cellulose were added to deionized water at a mass ratio of 8:1:1 and mixed evenly to form a slurry. This slurry was then coated onto a copper foil current collector and dried at 80°C for 12 hours to obtain an electrode sheet.

[0052] Example 2

[0053] A method for preparing porous carbon with directional slit pores includes the following steps:

[0054] Raw material: mesophase carbon microspheres, denoted as MCMB, D50=15μm.

[0055] Vapor-phase pre-oxidation treatment: MCMB was spread evenly in a quartz boat and placed in a tube furnace. The temperature was increased to 300°C at a rate of 3°C / min in a flowing air atmosphere (air flow rate of 100 mL / min) and held for 3 hours. It was then allowed to cool naturally to room temperature in air to obtain pre-oxidized MCMB.

[0056] Activation treatment: Pre-oxidized MCMB was activated at 950℃ for 1.5h in a mixed atmosphere of water vapor and nitrogen (water vapor partial pressure approximately 50%). After cooling, porous carbon with directional slit pores was obtained, denoted as A2. The D50 particle size of porous carbon A2 was 14μm.

[0057] A method for preparing a silicon-carbon composite anode material is carried out according to the method for preparing a silicon-carbon composite anode material in Example 1, except that porous carbon A2 with directional slit pores prepared in Example 2 is used.

[0058] Example 3

[0059] A method for preparing porous carbon with directional slit pores includes the following steps:

[0060] Raw material: needle coke, D50=40μm.

[0061] Gas-phase pre-oxidation treatment: A mixture of ozone and argon generated in an ozone generator (ozone concentration ~100g / m³). 3 In a process, needle coke was treated at 150°C for 5 hours. It was then naturally cooled to room temperature in air to obtain pre-oxidized needle coke.

[0062] Activation treatment: Pre-oxidized needle coke was activated at 1000℃ for 1 hour under a pure carbon dioxide atmosphere. After cooling, porous carbon with directional slit pores was obtained, denoted as A3. The D50 particle size of porous carbon A3 was 38 μm.

[0063] A method for preparing a silicon-carbon composite anode material is carried out according to the method for preparing a silicon-carbon composite anode material in Example 1, except that porous carbon A3 with directional slit pores prepared in Example 3 is used.

[0064] Example 4

[0065] A method for preparing porous carbon with directional slit pores includes the following steps:

[0066] Raw material: pitch coke, D50=25μm.

[0067] Liquid-phase pre-oxidation treatment: 30% hydrogen peroxide solution was used as the oxidant; 20g of pitch coke was weighed and slowly added to 200mL of 30% hydrogen peroxide solution. The pitch coke was subjected to liquid-phase pre-oxidation treatment at 60℃ for 8h. After the reaction was completed, the mixture was cooled, filtered, and washed with deionized water until the filtrate was neutral. Finally, it was vacuum dried at 120℃ for 12h to obtain pre-oxidized pitch coke.

[0068] Activation treatment: The pre-oxidized pitch coke was transferred to a high-temperature activation furnace and heated to 800℃ at a rate of 5℃ / min under a mixed atmosphere of nitrogen and carbon dioxide (volume ratio of nitrogen to carbon dioxide 1:1), and held at that temperature for 2 hours. After the reaction was completed, it was cooled to room temperature under nitrogen protection to obtain porous carbon with directional slit pores, denoted as A4. The D50 particle size of porous carbon A4 is 23 μm.

[0069] A method for preparing a silicon-carbon composite anode material is carried out according to the method for preparing a silicon-carbon composite anode material in Example 1, except that porous carbon A4 with directional slit pores prepared in Example 4 is used.

[0070] Example 5

[0071] A method for preparing porous carbon with directional slit pores includes the following steps:

[0072] Raw material: graphite, D50=10μm.

[0073] Liquid-phase pre-oxidation treatment: Acidic potassium permanganate solution (dilute sulfuric acid solution containing 5wt% KMnO4) was used as the oxidant; 20g of graphite was weighed and slowly added to 200mL of dilute sulfuric acid solution with a concentration of 5wt% KMnO4. The graphite was subjected to liquid-phase pre-oxidation treatment at 50℃ for 4h. After the reaction was completed, the graphite was cooled, filtered, and washed with deionized water until the filtrate was neutral. Finally, it was vacuum dried at 120℃ for 12h to obtain pre-oxidized graphite.

[0074] Activation treatment: The pre-oxidized petroleum coke was transferred to a high-temperature activation furnace and heated to 750°C at a rate of 5°C / min under a mixed atmosphere of nitrogen and carbon dioxide (volume ratio of nitrogen to carbon dioxide 1:1), and held at that temperature for 2 hours. After the reaction was completed, the mixture was cooled to room temperature under nitrogen protection to obtain porous carbon with directional slit pores, denoted as A5. The D50 particle size of porous carbon A5 is 9 μm.

[0075] A method for preparing a silicon-carbon composite anode material is carried out according to the method for preparing a silicon-carbon composite anode material in Example 1, except that porous carbon A5 with directional slit pores prepared in Example 5 is used.

[0076] Example 6

[0077] A method for preparing porous carbon with directional slit pores includes the following steps:

[0078] Raw material: petroleum coke, D50=20μm.

[0079] Liquid-phase pre-oxidation treatment: Same as in Example 1, but the pre-oxidation temperature is increased to 120℃ and the time is shortened to 2h. Weigh 20g of petroleum coke powder and slowly add it to 200mL of 65% concentrated nitric acid solution. Stir and reflux in a 120℃ water bath for 2h. After the reaction is complete, cool, filter, wash with deionized water until the filtrate is neutral, and finally vacuum dry at 120℃ for 12h to obtain pre-oxidized petroleum coke.

[0080] Activation treatment: Same as in Example 1, but the activation temperature was increased to 1050℃. The pre-oxidized petroleum coke was transferred to a high-temperature activation furnace, and under a mixed atmosphere of nitrogen and carbon dioxide (volume ratio of nitrogen to carbon dioxide 1:1), the temperature was increased to 1050℃ at a rate of 5℃ / min and held for 2 hours. After the reaction was completed, it was cooled to room temperature under nitrogen protection to obtain porous carbon with directional slit pores, denoted as A6. The D50 particle size of porous carbon A6 was 17 μm.

[0081] A method for preparing a silicon-carbon composite anode material is carried out according to the method for preparing a silicon-carbon composite anode material in Example 1, except that porous carbon A6 with directional slit pores prepared in Example 6 is used.

[0082] Comparative Example 1

[0083] A method for preparing porous carbon includes the following steps:

[0084] Raw material: petroleum coke, D50=20μm.

[0085] Processing procedure: Without any pre-oxidation treatment, the raw petroleum coke was directly activated under the same activation conditions as in Example 1 (nitrogen and carbon dioxide volume ratio of 1:1, temperature increased to 900℃ at 5℃ / min, and held for 2h) to obtain porous carbon, which was used as control sample D1.

[0086] A method for preparing a silicon-carbon composite anode material is disclosed, which follows the method described in Example 1, except that porous carbon D1 prepared in Comparative Example 1 is used. The D50 particle size of the porous carbon D1 is 19 μm.

[0087] Table 1 Structural characteristic parameters of porous carbon

[0088]

[0089] As shown in Table 1, the D50 of the raw material decreased slightly after pre-oxidation and activation treatment. This is due to the particle shrinkage caused by the oxidation etching process. Compared with Comparative Example 1, the sample obtained in Example 1 with the pre-oxidation treatment step has a larger specific surface area and total pore volume. This is because the pre-oxidation process can better oxidize the amorphous carbon structure, making it easier to be etched in the subsequent activation step, forming more abundant slit pores, and increasing the specific surface area and total pore volume of the sample.

[0090] The porous carbon prepared according to the above embodiments and comparative examples was used to prepare silicon-carbon composite negative electrode materials (electrode sheets), and lithium-ion batteries were assembled. The capacity retention rate of the lithium-ion batteries at 0.5C / 100 cycles was tested.

[0091] Battery assembly conditions: The dried electrode sheets were cut into 12mm round pieces and assembled into CR2032 coin cell half-cells in an argon-protected glove box. The electrolyte for the half-cells was lithium hexafluorophosphate (LiPF6, 1mol / L), and the solvents were ethylene carbonate (EC) and dimethyl carbonate (DMC), with a volume ratio of EC to DMC of 1:1. The counter electrode was a lithium sheet. The half-cells were allowed to stand for 8 hours and then subjected to charge-discharge tests at 25°C using a battery testing system (Blue Electric, CT2001A). The test conditions were as follows: initial coulombic efficiency was tested at 0.1C rate, with a charging cutoff voltage of 3V and a discharging cutoff voltage of 0V; subsequent charge-discharge cycle tests were conducted at 0.5C rate.

[0092] Table 2 Battery performance of CR2032 button cell

[0093]

[0094] As shown in Table 2, compared to the coin cell assembled in Comparative Example 1, the coin cells in Examples 1-6 using silicon-carbon composite anode materials exhibit higher cycle capacity retention. This is because the silicon-carbon composite anode materials in the battery electrodes of Examples 1-6 of this invention possess highly anisotropic and directionally interconnected pores in the porous carbon, which is beneficial for improving the stability of silicon nanoparticles during charge and discharge processes.

[0095] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing porous carbon with directional slit pores, characterized in that, Includes the following steps: Using easily graphitized carbon materials with layered molecular orientation as carbon sources, the carbon sources are selectively pre-oxidized to obtain pre-oxidized carbon materials. The pre-oxidized carbon material was activated in an oxidizing atmosphere and then cooled to obtain porous carbon with anisotropic directional slit pores arranged along the carbon layer direction. The selective pre-oxidation treatment selectively introduces oxygen-containing functional groups at crystal defect sites, grain boundaries, and graphite crystallite edges of the carbon source. The oxidizing atmosphere is a mixture of one or more of water vapor and carbon dioxide with an inert gas; the activation temperature is 700℃~1100℃; The selective pre-oxidation treatment is either liquid-phase pre-oxidation or gas-phase pre-oxidation; The first oxidant used in the liquid-phase pre-oxidation is a solution of one or more of nitric acid, sulfuric acid, hydrogen peroxide, potassium permanganate, and hypochlorous acid; the temperature of the liquid-phase pre-oxidation is 50℃~120℃; The second oxidant used in the gas-phase pre-oxidation is a mixture of one or more of air, oxygen, and ozone with an inert gas; the temperature of the gas-phase pre-oxidation is 100℃~400℃; The specific steps for liquid-phase pre-oxidation of the carbon source are as follows: The carbon source and the first oxidant are subjected to liquid-phase pre-oxidation at 50℃~120℃ to obtain pre-oxidized carbon material; The specific steps for gas-phase pre-oxidation of the carbon source are as follows: The carbon source was pre-oxidized in the gas phase at 100℃~400℃ under a second oxidant atmosphere to obtain a pre-oxidized carbon material. The easily graphitized carbon material is one or more of needle coke, petroleum coke, pitch coke, mesophase carbon microspheres, and graphite.

2. The method for preparing porous carbon with directional slit pores according to claim 1, characterized in that, The selective pre-oxidation treatment lasts for 0.5 h to 10 h; the activation treatment lasts for 0.5 h to 5 h.

3. The method for preparing porous carbon with directional slit pores according to claim 1, characterized in that, The D50 particle size of the easily graphitized carbon material is 10μm to 40μm.

4. The method for preparing porous carbon with directional slit pores according to claim 1, characterized in that, The oxygen-containing functional group is a carboxyl group, hydroxyl group, carbonyl group, epoxy group, quinone group, lactone group, ether group or acid anhydride group.

5. A porous carbon with directional slit pores, characterized in that, The porous carbon with directional slit pores is prepared by any one of claims 1 to 4.

6. The porous carbon with directional slit pores according to claim 5, characterized in that, The porous carbon has a D50 particle size of 5μm to 50μm and a specific surface area of ​​500m². 2 / g~2500m 2 / g; the directional slit pores of the porous carbon are slit-shaped pores arranged along the orientation of carbon layered molecules; the pore walls of the directional slit pores are composed of graphitized carbon layers.

7. The application of a porous carbon with directional slit pores in the preparation of silicon-carbon anode materials for lithium-ion batteries, characterized in that, The lithium-ion battery silicon-carbon anode material includes a silicon-based material and the porous carbon with directional slit pores as described in claim 5 or 6, wherein the silicon-based material is loaded in and on the surface of the porous carbon with directional slit pores.

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