A micro / nano-level porous carbon framework material and its preparation method

Abstract

This invention discloses a micro / nano-level porous carbon framework material and its preparation method, belonging to the technical field of thermally conductive porous carbon materials. A phenolic resin-based porous carbon material is prepared by impregnating porous foam with a phenolic resin solution, followed by curing, drying, and carbonization. A porous carbon matrix is ​​obtained by CVD deposition of a pyrolytic carbon coating layer. A porous carbon framework with a highly crystalline orientation structure is obtained through high-temperature heat treatment. Vertical graphene is then introduced onto the framework surface using CVD to construct a nanoscale pore structure, thus obtaining the micro / nano-level porous carbon framework material. By using porous foam as a template to construct micron-level interconnected channels, strengthening the framework connections through pyrolytic carbon deposition, improving intrinsic thermal conductivity through high-temperature graphitization, and constructing a nanopore network through in-situ growth of vertical graphene, a micro / nano-level porous structure is formed, connecting micron-level foam pores and nanoscale graphene pores. This structure possesses both high thermal conductivity and high mass transfer efficiency, showing broad application prospects in thermal management, catalyst supports, and electrode materials.

Description

Technical Field

[0001] This invention belongs to the field of thermally conductive porous carbon materials technology, specifically relating to a micro / nano hierarchical porous carbon framework material and its preparation method. Background Technology

[0002] Porous carbon materials are widely used in catalysis, energy storage, and adsorption due to their high specific surface area, good chemical stability, and electrical conductivity. Among these, using three-dimensional network polymers such as polyurethane foam as templates, followed by impregnation with carbon precursors such as phenolic resin and then carbonization, is a classic process for constructing macroporous (micrometer-scale) carbon frameworks. Carbon materials prepared by this method can perfectly replicate the interconnected network structure of the template, forming regular micrometer-scale fluid channels. This structure has significant advantages at the macroscopic level: the open and interconnected pore system can greatly reduce fluid flow resistance, ensuring rapid transport and efficient permeation of reactants or heat transfer media (such as air and phase change materials), which is fundamental to achieving rapid heat and mass transfer within the material. Although phenolic resin-based porous carbon materials possess a fully interconnected micrometer-scale pore structure, facilitating fluid passage and heat conduction, they generally suffer from limited specific surface area and low mass transfer efficiency. To overcome these issues of insufficient specific surface area, researchers have turned to the design of nanoporous carbon materials, for example, through metal-organic framework (MOF) derivatization, block copolymer self-assembly, or strong base chemical activation. These methods can construct nanoporous networks dominated by micropores (<2 nm) and mesopores (2-50 nm), significantly increasing the specific surface area and greatly enriching the active interfaces of the material. However, these nanoporous carbons often exist in a particulate or stacked state, lacking macroscopically interconnected skeletal support, and generally suffer from two major bottlenecks: First, although the tortuous channels dominated by micropores endow them with a high specific surface area, they significantly increase molecular diffusion resistance, resulting in low mass transport efficiency and limiting the overall reaction rate; Second, the intrinsic mechanical strength of simple nanoporous structures is poor, and they are prone to agglomeration when used as a whole material, with complex heat conduction paths and high thermal resistance, which is not conducive to constructing efficient thermal management channels.

[0003] Chinese patent application CN118405687A discloses a method for preparing porous carbon and its application in silicon-carbon anodes. This method involves spray-drying two-dimensional or three-dimensional carbon materials (such as graphene) and one-dimensional carbon materials (such as carbon nanotubes) under the action of a dispersant, followed by heat treatment, to obtain a porous carbon material with a structure similar to rambutan. While this technology constructs a composite structure of carbon framework and dispersed layer, its pore system is mainly formed by the physical stacking and assembly of carbon materials of different dimensions. It is difficult to simultaneously achieve the synergistic construction of interconnected micron-level transport channels and a high specific surface area nanopore network in a single material. Furthermore, this material primarily addresses lithium-ion transport and volume expansion buffering in silicon-carbon anodes, without addressing the dual optimization of the material's macroscopic thermal conductivity and mass transfer efficiency. Chinese patent application CN119263865A discloses a high thermal conductivity carbon skeleton resin-based composite material and its preparation method. The method uses chopped mesophase pitch-based carbon fibers to form a fiber felt preform, grows carbon nanotubes via CVD, deposits pyrolytic carbon, and then impregnates the preform with resin after graphitization to obtain the composite material. While this technology constructs a three-dimensional thermally conductive network using carbon nanotubes and pyrolytic carbon, its micron-sized channels originate from the random overlap of chopped fibers. The resulting channel system is dominated by interstitial gaps, lacking regular, continuous, and low-torsion through-flow paths. Furthermore, the final product is a dense resin-impregnated composite material, rather than a porous carbon skeleton material with through-pores, thus failing to simultaneously achieve a unified high thermal conductivity, high-flux mass transfer, and high specific surface area. Therefore, existing technologies struggle to achieve a synergistic unity of "macroscopic mass transfer" and "microscopic high activity" in a single carbon material system. While macroporous structures provide pathways for rapid heat and mass transfer, they sacrifice specific surface area and interfacial reactivity. Conversely, single nanoporous structures achieve high specific surface area and strong adsorption, but are limited by high mass transfer resistance and imperfect thermal conductivity networks. This scale-based performance disconnect—better mass transfer in macropores but lower reactivity, and higher reactivity in nanopores but poorer mass transfer—has become a key scientific problem restricting the application of porous carbon materials in next-generation high-power, high-capacity devices.

[0004] Therefore, developing a hierarchical porous carbon material that combines a through-micron-scale framework with abundant nano-scale pores, enabling it to utilize micron channels for rapid fluid transport and efficient heat conduction, while also utilizing nanopores to provide a large reaction interface and adsorption space, thereby achieving a dual improvement in thermal management and mass transfer efficiency, is of extremely important research value and practical significance for promoting the development of efficient energy storage, heterogeneous catalysis, and thermal control technologies. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a micro / nano hierarchical porous carbon framework material and its preparation method, so as to solve the problem of how to simultaneously construct through-hole micron-level channels with rapid transport capability and nano-level pore structures with high interfacial activity in the same carbon framework material, overcome the technical problem of the separation of macropore and nanopore performance at the pore scale in traditional porous carbon materials, and achieve the synergistic unity of high thermal conductivity and high mass transfer efficiency.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing micro / nano-level porous carbon framework materials, comprising: Phenolic resin-based porous carbon material is prepared by impregnating porous foam in phenolic resin solution, followed by curing, drying and carbonization. A pyrolytic carbon coating layer was deposited on a phenolic resin-based porous carbon material using chemical vapor deposition to obtain a porous carbon matrix; After high-temperature heat treatment of the porous carbon matrix, a porous carbon framework with a highly crystalline orientation structure is obtained. Vertical graphene was introduced onto the surface of a porous carbon framework with a highly crystalline orientation structure using chemical vapor deposition to construct a nanoscale pore structure and obtain a micro-nano hierarchical porous carbon framework material.

[0007] Preferably, the conditions for impregnating the porous foam in the phenolic resin solution are: vacuum impregnation for 30-60 min.

[0008] Preferably, the porous foam is polyurethane foam with a pore size of 150~250 μm and a density of 0.028~0.035 g / cm³. 3 .

[0009] Preferably, the curing conditions are: curing at 80~90℃ for 24~48 h; drying conditions are: drying at 80~100℃ under normal pressure for 10~24 h; and carbonization conditions are: heating to 600~1100℃ at 2~5℃ / min under an argon atmosphere and holding for 2~4 h.

[0010] Preferably, the chemical vapor deposition process for depositing the pyrolytic carbon coating layer is as follows: using argon as a protective gas, the temperature is increased to 900-1100℃ at a heating rate of 1-5℃ / min, followed by CH4 deposition for 60-600 min, with 5-8 deposition cycles; wherein, during the heating and cooling processes, the argon flow rate is 1-3 L / min; and during CH4 deposition, the argon flow rate is 2-5 L / min.

[0011] Preferably, the conditions for high-temperature heat treatment are as follows: in an argon atmosphere, the temperature is increased to 1600-2500℃ at a heating rate of 5-10℃ / min, and heated for 2-3 hours.

[0012] Preferably, the chemical vapor deposition process for introducing vertical graphene is as follows: under vacuum conditions, the temperature is increased to 900-1200°C at a heating rate of 1-5°C / min, followed by the introduction of CH3OH for deposition for 1-8 h; wherein, the chamber pressure is maintained at 8-9.5 kPa while the CH3OH gas is introduced.

[0013] Preferably, the preparation of the phenolic resin precursor solution includes: using resorcinol and formaldehyde as carbon precursors, using hexadecyltrimethylammonium bromide as surfactant and catalyst, and using deionized water as solvent.

[0014] The present invention also discloses a micro / nano hierarchical porous carbon framework material, which is prepared by the above-described method for preparing micro / nano hierarchical porous carbon framework materials.

[0015] Preferably, the micro / nano hierarchical porous carbon framework material has a dual-scale synergistic structure consisting of micron-level channels and nano-level pores, wherein the micron-level channels are formed by polyurethane foam templates, and the nano-level pores are formed by in-situ growth of vertical graphene on the inner wall of the micron-level channels.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing micro / nano-level porous carbon framework materials. Through a three-step process—constructing a micron-scale carbon framework, depositing a dense pyrolytic carbon layer, and growing vertical graphene nanosheets—it achieves an organic combination of micron-level channels and nanostructures. First, a polyurethane foam template is used to replicate interconnected micron-scale channels, ensuring low-resistance pathways for rapid fluid transport. Then, pyrolytic carbon is deposited using chemical vapor deposition to reinforce and densify weak areas of the framework. Finally, high-temperature heat treatment induces ordered rearrangement of the carbon matrix, forming a highly crystalline oriented structure, significantly improving intrinsic thermal conductivity (e.g., ...). Figure 5 As shown, after high-temperature heat treatment, the XRD diffraction peaks gradually become sharper and stronger, indicating a significant improvement in the degree of graphitization; finally, vertical graphene is grown in situ using chemical vapor deposition, constructing a nanoscale porous structure on the inner wall of micron-sized channels (e.g., Figure 3-4 As shown, graphene sheets are grown in a vertical orientation to form a three-dimensional interconnected porous network with a high specific surface area. This three-step synergistic process achieves a dual-scale structure where micron-sized pores dominate rapid transport and nanopores dominate interfacial reactions, resolving the contradiction in existing single-scale materials that cannot simultaneously achieve high mass transfer and high activity.

[0017] Furthermore, impregnation under vacuum conditions effectively eliminates air from the template pores, allowing the precursor solution to penetrate deeper into the three-dimensional network structure inside the template using negative pressure. Simultaneously, the 30-60 minute impregnation time ensures uniform resin loading on the template surface. This ensures that the phenolic resin precursor can fully and uniformly penetrate the internal pores of the porous foam template, avoiding skeletal defects or pore blockage caused by insufficient impregnation.

[0018] Furthermore, polyurethane foam was chosen as the sacrificial template, whose interconnected three-dimensional network structure provides low-resistance fluid channels for the carbon material; the pore size of 150~250μm ensures that the channels are large enough to reduce flow resistance without sacrificing the skeletal density per unit volume due to excessive size; the density is 0.028~0.035 g / cm³. 3 This ensures that the template frame has sufficient mechanical strength to support subsequent processes. For example... Figure 2 As shown, the porous carbon prepared using this template inherits the rich pore structure of polyurethane foam. The pores are completely interconnected by a carbon skeleton, forming a stable three-dimensional micron-scale network, which provides a structural basis for achieving high-throughput mass transfer.

[0019] Furthermore, a curing temperature of 80~90℃ allows the phenolic resin to slowly crosslink and form a uniform network structure; a slow heating rate of 2~5℃ / min helps to uniformly release thermal stress during carbonization and prevent skeleton deformation; a carbonization temperature range of 600~1100℃ ensures that the polyurethane template is completely pyrolyzed and removed, while the phenolic resin is fully carbonized to form a conductive carbon skeleton.

[0020] Furthermore, pyrolytic carbon (PyC) is deposited on the surface and inside the pores of the porous carbon framework by CVD, which can fill the weak parts of the framework and increase the structural density; the deposition temperature of 900~1100℃ ensures that methane is fully decomposed to form high-quality pyrolytic carbon; 5~8 cycles of deposition can uniformly coat the surface layer by layer, avoiding the blockage of pores caused by excessive deposition at one time. Figure 5 The XRD patterns showed a significant increase in the intensity of the diffraction peaks (PyC / C) after the deposition of pyrolytic carbon, indicating a marked enhancement in the graphitization of the framework. This provides a structural basis for achieving a highly crystalline oriented structure through subsequent high-temperature heat treatment, while the reinforcing effect of the pyrolytic carbon improves the structural stability of the material in subsequent processes.

[0021] Furthermore, high-temperature treatment at 1600–2500℃ provides carbon atoms with sufficient migration energy, allowing them to rearrange and form an ordered graphite microcrystalline structure; a heating rate of 5–10℃ / min ensures efficiency while avoiding thermal shock; and a holding time of 2–3 hours ensures sufficient crystal growth. Figure 5As shown, the XRD diffraction peaks of HT-PyC / C gradually become sharper and stronger after high-temperature heat treatment, indicating a significant improvement in the graphitization degree of the carbon framework, confirming a significant improvement in the crystal structure. This step enables the material to form a good phonon conduction path, and the overall thermal conductivity is significantly higher than that of packed-state nano-carbon materials, thus solving the problem of poor thermal conductivity in traditional porous carbon materials.

[0022] Furthermore, by selecting CH3OH as the carbon source and pyrolyzing it under vacuum conditions of 900–1200 °C and 8–9.5 kPa, vertically oriented graphene sheets can be induced to grow. This vertical graphene structure possesses a high specific surface area and open nanopores; the deposition time of 1–8 h allows for precise control of the size and density of the nanopores; such as Figure 3 As shown, with the extension of deposition time, the graphene sheets exhibit vertical orientation growth, and the sheet size gradually increases; Figure 4 Further studies show that the longer deposition time allows for bulk diffusion and local redeposition of carbon atoms at the contact points of adjacent curved sheets, forming robust nodes that connect the originally independent sheets into a more integrated mechanical network, with the pore size gradually decreasing. This step significantly increases the specific surface area of ​​the material, resulting in a material that combines high specific surface area, high thermal conductivity, high structural stability, and excellent fluid permeability.

[0023] Furthermore, resorcinol and formaldehyde undergo a condensation reaction under the catalysis of CTAB to form phenolic resin. CTAB, as a surfactant, can also reduce the surface tension of the solution and promote the uniform spreading of the resin on the template surface.

[0024] This invention discloses a micro / nano hierarchical porous carbon framework material that combines the advantages of interconnected micrometer-level channels and high specific surface area nanopores. Compared to traditional macroporous carbon materials, this material not only retains the advantages of low-resistance, high-fluidity fluid channels, but also significantly improves the specific surface area and active site density through the introduction of vertical graphene. Compared to traditional nanoporous carbon materials, it overcomes the inherent defects of high mass transfer resistance and discontinuous thermal conductivity networks. A good phonon conduction path is formed during carbonization or graphitization, enabling rapid heat extraction and introduction; simultaneously, the micrometer-level channels act as fast lanes to ensure rapid fluid medium penetration, while the nanopores attached to the pore walls provide a large, accessible reaction interface. XRD, SEM, and TEM characterization results of Examples 1-6 are shown below. Figure 2-5 This study verified that the material possesses a complete three-dimensional micron-scale network structure, highly graphitized crystal orientation, and uniformly distributed nanoscale pores.

[0025] Furthermore, the micron-sized channels (150~250μm) originate from the three-dimensional interconnected network of the polyurethane foam template, ensuring low resistance and high-flux rapid penetration of the fluid medium; the nano-sized pores are formed by the voids between the vertical graphene sheets (such as... Figure 3-4As shown in the figure, this structure provides a large specific surface area and abundant active sites. This dual-scale structure achieves a unity of efficient heat conduction at the macroscopic scale and efficient interfacial reaction at the microscopic scale, fundamentally overcoming the problems of wide pore size distribution, strong structural randomness, and low mass transfer efficiency in existing technologies. By adjusting the template parameters and precursor ratio, the size, distribution, and graphitization degree of the micro-pores and nano-pores, as well as the framework, can be independently or synergistically optimized to achieve directional structural design for different application scenarios. Attached Figure Description

[0026] Figure 1 This is a flowchart of the preparation method of the micro / nano hierarchical porous carbon framework material of the present invention; Figure 2 The phenolic resin-based porous carbon material prepared in Example 3 of this invention; Figure 3 These are comparative images of the vertical graphene morphology disclosed in Embodiment 4(a) and Embodiment 6(b) of the present invention; Figure 4 These are morphological comparison images of the vertical graphene nanoscale pore structures disclosed in Examples 4(a) and 6(b) of the present invention; Figure 5 The XRD patterns of the phenolic resin-based porous carbon material (C), the porous carbon matrix (PyC / C) after carbon deposition and pyrolysis (Example 6 of the present invention), and the porous carbon framework (HT-PyC / C) with a highly crystalline orientation structure after high-temperature heat treatment are shown. Figure 6 This is a morphology diagram of the porous carbon framework material prepared in Comparative Example 1. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0028] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0029] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0030] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0031] In this invention, unless otherwise specified, the components involved or their preferred components can be combined to form new technical solutions.

[0032] In this invention, unless otherwise specified, the numerical range "a~b" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "6~22" indicates that all real numbers between "6~22" have been listed in this document, and "6~22" is simply an abbreviation for these numerical combinations.

[0033] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0034] The term “and / or” as used in this invention refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0035] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0036] This invention discloses a method for preparing micro / nano-level porous carbon framework materials, comprising the following steps: 1) Using porous foam as a template and phenolic resin solution as a precursor, phenolic resin-based porous carbon materials are prepared after curing, drying and carbonization.

[0037] Using porous foam as a template and phenolic resin solution as a precursor, polyurethane foam with a certain pore size is impregnated into the phenolic resin precursor solution. After impregnation, the excess precursor solution is squeezed out. The impregnation method is vacuum impregnation. The impregnation time is 30~60 min.

[0038] The preparation method of phenolic resin precursor solution is as follows: using resorcinol and formaldehyde as carbon precursors, hexadecyltrimethylammonium bromide (CTAB) as surfactant and catalyst, and deionized water as solvent to prepare the precursor solution.

[0039] The ratio of resorcinol, formaldehyde solution, deionized water and hexadecyltrimethylammonium bromide was (10.0~20.0) g : (13.4~26.5) g : (16.0~30.2) mL : (0.026~0.045) g; the stirring method was magnetic stirring; the magnetic stirring time was 10~40 min; the mass concentration of formaldehyde solution was 37.5 wt%.

[0040] The template is made of polyurethane foam with a pore size of 150~250 μm and a density of 0.028~0.035 g / cm³. 3 .

[0041] The curing process is carried out in an oven at a temperature of 80-90°C for 24-48 hours. Drying is performed at atmospheric pressure and 80-100°C for 10-24 hours.

[0042] The carbonization parameters are as follows: under an argon atmosphere, the temperature is increased to 600-1100℃ at a rate of 2-5℃ / min, and held for 2-4 hours.

[0043] 2) Then, chemical vapor deposition was used to deposit a pyrolytic carbon (PyC) coating layer on the porous framework to obtain a porous carbon matrix, and the changes in pore size and surface morphology of the sample with deposition time were observed.

[0044] The parameters for the deposition pyrolysis carbon treatment are as follows: phenolic resin porous carbon material is placed in a vertical CVD furnace, and argon is used as the protective gas. The heating equipment is heated to 900~1100℃ at a heating rate of 1~5℃ / min. Then, CH4 is introduced for deposition for 60~600min. After cooling to room temperature, a porous carbon matrix is ​​obtained. During the heating and cooling processes, the argon flow rate is 1~3 L / min. During the CH4 deposition, the argon flow rate is 2~5 L / min.

[0045] In the process of obtaining a carbon matrix containing a framework of pyrolytic carbon, the deposition cycle number is 5 to 8 times.

[0046] 3) Then, a porous carbon framework with a highly crystalline orientation structure is obtained by high-temperature heat treatment.

[0047] The parameters for high-temperature heat treatment are as follows: in an argon atmosphere, the temperature is increased to 1600-2500℃ at a heating rate of 5-10℃ / min, and heated for 2-3 hours.

[0048] 4) In order to achieve micro-nano-scale porous structures, CVD process is used to introduce high specific surface area vertical graphene to construct nanoscale pore structures and prepare micro-nano-level porous carbon framework materials with both high thermal conductivity and high mass transfer efficiency.

[0049] The introduction of vertical graphene to construct nanoscale porous structures involves heating the equipment to 900–1200°C under vacuum conditions at a heating rate of 1–5 °C / min, followed by the introduction of CH3OH gas for deposition over 1–8 h. After cooling to room temperature, a micro-nano porous carbon matrix is ​​obtained. During this process, CH3OH gas is introduced while maintaining the chamber pressure at 8–9.5 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is stopped, and the prepared sample is removed after the equipment has cooled naturally.

[0050] The present invention also discloses a micro / nano hierarchical porous carbon framework material prepared by the above preparation method.

[0051] This invention discloses a method for preparing micro / nano-level porous carbon framework materials, aiming to solve the structural fragmentation problem at the pore scale of traditional porous carbon materials. The method uses polyurethane foam as a sacrificial template, constructing a framework of micron-level fluid channels with its interconnected three-dimensional network structure. A phenolic resin solution is used as a carbon precursor, uniformly loaded onto the template framework surface through an impregnation process. After curing and drying, carbonization is performed under a high-temperature inert atmosphere, resulting in the pyrolysis removal of the polyurethane template and simultaneous carbonization of the phenolic resin to form a preliminary micron-level carbon framework. Subsequently, pyrolytic carbon is deposited on the carbon framework surface and inside the pores using chemical vapor deposition (CVD) to reinforce weak areas and densify the structure. High-temperature graphitization then induces ordered rearrangement of the carbon matrix, significantly improving the intrinsic thermal conductivity of the material. Based on this, graphene nanolayers are grown in situ on the framework surface again using CVD, successfully constructing a nanoscale porous structure and highly active interfaces within the micron-level pore walls. The core innovation of this method lies in the systematic control of key process parameters (including deposition temperature, reactive gas flow rate, and deposition time) for CVD deposition of pyrolytic carbon and graphene, thereby achieving mechanical enhancement of the micron-pore framework, directional construction of nanopore structures, and precise design of pore morphology. The resulting hierarchical porous carbon material possesses high specific surface area, excellent thermal conductivity, and efficient mass transfer capabilities, overcoming the problems of wide pore size distribution, strong structural randomness, and low mass transfer efficiency in existing technologies.

[0052] This invention, through a unique template and precursor design, constructs abundant nanoporous structures in situ within and on the surface of a continuous, interconnected micron-scale carbon framework, forming a dual-scale synergistic structure where "micron-pores dominate rapid transport and nanopores dominate interfacial reactions." Compared to simple macroporous carbon materials, this invention significantly improves specific surface area and active site density while retaining the advantages of low resistance and high-fluidity fluid channels. Compared to single nanoporous carbon materials, this invention overcomes their inherent defects of high mass transfer resistance and discontinuous thermal conductivity networks, achieving a unity of efficient heat conduction at the macroscale and efficient interfacial reactions at the microscale.

[0053] Thanks to the continuous, interconnected micron-scale framework network, the carbon material of this invention forms excellent phonon conduction pathways during carbonization or graphitization, resulting in a significantly higher overall thermal conductivity than packed nanomaterials, enabling rapid heat transfer. Simultaneously, the micron-sized channels act as a "fast track," ensuring rapid fluid medium penetration, while the nanopores attached to the pore walls provide a large, accessible reaction interface. This avoids the problem of low utilization of active sites caused by the tortuous and deeply buried pores in traditional nanoporous materials, significantly improving the effective mass transfer efficiency per unit volume.

[0054] This invention allows for the independent or synergistic optimization of the size, distribution, and graphitization degree of micropores and nanopores within the framework by adjusting template parameters and precursor ratios, enabling directional structural designs for various applications. Instead of requiring additional control over the micropores of the polyurethane foam template, it directly utilizes its mature commercial specifications (150~250 μm) as rapid mass transfer channels, focusing its innovation on the in-situ construction of nanopores and the improvement of interfacial properties. The resulting material possesses high specific surface area, high thermal conductivity, high structural stability, and excellent fluid permeability, overcoming the scale-related problems of "good mass transfer in macropores but low specific surface area" and "high specific surface area in nanopores but poor mass transfer" in existing technologies. It exhibits significant technical advantages and practical value in fields such as efficient thermal management, heterogeneous catalysis, high-power energy storage, and adsorption separation.

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0056] Example 1 A method for preparing micro / nano hierarchical porous carbon framework materials includes the following steps: Step 1: Dissolve 10.0 g of resorcinol and 13.4 g of 37.5 wt% formaldehyde solution in 16.0 mL of deionized water to obtain a mixture; then add 0.026 g of cetyltrimethylammonium bromide (CTAB) to the mixture, and magnetically stir the suspension for 10 min to obtain a transparent precursor solution; Step 2: Immerse the polyurethane foam in the initial emulsion obtained in Step 1, so that the block is completely submerged, and then place it in a vacuum drying oven. Evacuate the oven until the pressure inside is below 0.09 MPa and maintain for 30 minutes. Then, heat curing, normal pressure drying and carbonization are carried out.

[0057] The heating, curing, drying and carbonization process is as follows: the porous carbon material of phenolic resin is placed in an oven and the temperature is set to 80℃ for 24 h; then it is dried at 80℃ under normal pressure for 10 h; then it is placed in a tube furnace and heated to 600℃ at 2℃ / min and held for 2 h, with argon gas introduced as a protective gas throughout the process to decompose the phenolic resin in the composite material into carbon. The selected polyurethane foam has a density of 0.028 g / cm³. 3 The pore size ranges from 250 μm.

[0058] Step 3: Place the carbonized sample in a CVD furnace, use argon as a protective gas, and heat the equipment to 900℃ at a heating rate of 2℃ / min. Then, introduce CH4 to deposit PyC for 60 min, and repeat the deposition cycle 5 times.

[0059] The carbon deposition pyrolysis process is as follows: the argon flow rate is set to 1 L / min during the heating and cooling process, and the carbon deposition pyrolysis process is 2 L / min; then the temperature is cooled to room temperature to obtain a porous carbon matrix.

[0060] Step 4, High-temperature heat treatment: The composite material (PyC / C) with deposited pyrolytic carbon was heat-treated in a high-temperature furnace to obtain HT-PyC / C composite material; The heat treatment process for the composite material is as follows: the composite material after carbon deposition and pyrolysis is placed in a high-temperature furnace, argon is introduced as a protective gas, and the equipment is heated to 1600℃ for 2 hours at a heating rate of 5℃ / min, so that the phenolic resin-based amorphous carbon is transformed into a highly oriented crystalline structure.

[0061] Step 5: Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace and heat the equipment to 900℃ at a heating rate of 1℃ / min. Then, CH3OH is introduced to deposit graphene for 1 h.

[0062] The graphene deposition process involves maintaining a vacuum throughout the heating and cooling process. CH3OH gas is introduced while the chamber pressure is maintained at 8 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is shut off, and the prepared sample is removed after the equipment has cooled naturally.

[0063] Example 2 A method for preparing micro / nano hierarchical porous carbon framework materials includes the following steps: Step 1: Dissolve 12.0 g of resorcinol and 15.8 g of 37.5 wt% formaldehyde solution in 20.0 mL of deionized water to obtain a mixture; then add 0.030 g of cetyltrimethylammonium bromide (CTAB) to the mixture, and magnetically stir the suspension for 15 min to obtain a transparent precursor solution; Step 2: Immerse the polyurethane foam in the initial emulsion obtained in Step 1, so that the block is completely submerged, and then place it in a vacuum drying oven. Evacuate the oven until the pressure inside is below 0.09 MPa and maintain for 30 minutes. Then, heat curing, normal pressure drying and carbonization are carried out.

[0064] The heating, curing, drying and carbonization process is as follows: the porous carbon material of phenolic resin is placed in an oven and the temperature is set to 85℃ for 24 hours of heating and curing; then it is dried at 85℃ under normal pressure for 10 hours; then it is placed in a tube furnace and heated to 700℃ at 3℃ / min and held for 2 hours. Argon gas is introduced as a protective gas throughout the process to decompose the phenolic resin in the composite material into carbon. The selected polyurethane foam has a density of 0.028 g / cm³. 3 The pore size ranges from 250 μm.

[0065] Step 3: Place the carbonized sample in a CVD furnace, use argon as a protective gas, and heat the equipment to 900℃ at a heating rate of 2℃ / min. Then, introduce CH4 to deposit PyC for 120 min, and repeat the deposition cycle 6 times.

[0066] The carbon deposition pyrolysis process is as follows: the argon flow rate is set to 1 L / min during the heating and cooling process, and the carbon deposition pyrolysis process is 2 L / min; then the temperature is cooled to room temperature to obtain a porous carbon matrix.

[0067] Step 4, High-temperature heat treatment: The composite material (PyC / C) with deposited pyrolytic carbon was heat-treated in a high-temperature furnace to obtain HT-PyC / C composite material; The heat treatment process for the composite material is as follows: the composite material after carbon deposition and pyrolysis is placed in a high-temperature furnace, argon is introduced as a protective gas, and the equipment is heated to 1600℃ for 2 hours at a heating rate of 6℃ / min, so that the phenolic resin-based amorphous carbon is transformed into a highly oriented crystal structure.

[0068] Step 5: Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace and heat the equipment to 1000℃ at a heating rate of 2℃ / min. Then, CH3OH is introduced to deposit graphene for 2 hours.

[0069] The graphene deposition process involves maintaining a vacuum throughout the heating and cooling process. CH3OH gas is introduced while the chamber pressure is maintained at 8.5 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is shut off, and the prepared sample is removed after the equipment has cooled naturally.

[0070] Example 3 A method for preparing micro / nano hierarchical porous carbon framework materials includes the following steps: Step 1: Dissolve 20.0 g of resorcinol and 26.5 g of 37.5 wt% formaldehyde solution in 30.2 mL of deionized water to obtain a mixture; then add 0.045 g of cetyltrimethylammonium bromide (CTAB) to the mixture, and magnetically stir the suspension for 20 min to obtain a transparent precursor solution; Step 2: Immerse the polyurethane foam in the initial emulsion obtained in Step 1, so that the block is completely submerged, and then place it in a vacuum drying oven. Evacuate the oven until the pressure inside is below 0.09 MPa and maintain for 40 minutes. Then, heat curing, normal pressure drying and carbonization are carried out.

[0071] The heating, curing, drying and carbonization process is as follows: the porous carbon material of phenolic resin is placed in an oven and the temperature is set to 90℃ for heating and curing for 36 h; then it is dried at 90℃ under normal pressure for 16 h; then it is placed in a tube furnace and heated to 800℃ at 2℃ / min and held for 3 h, with argon gas introduced as a protective gas throughout the process to decompose the phenolic resin in the composite material into carbon. The selected polyurethane foam has a density of 0.032 g / cm³. 3 The pore size ranges from 200 μm.

[0072] Step 3: Place the carbonized sample in a CVD furnace, use argon as a protective gas, and heat the equipment to 1000℃ at a heating rate of 3℃ / min. Then, introduce CH4 to deposit PyC for 240 min, and repeat the deposition cycle 7 times.

[0073] The carbon deposition pyrolysis process is as follows: the argon flow rate is set to 2 L / min during the heating and cooling process, and the carbon deposition pyrolysis process is 3 L / min; then the temperature is cooled to room temperature to obtain a porous carbon matrix.

[0074] Step 4, High-temperature heat treatment: The composite material (PyC / C) with deposited pyrolytic carbon was heat-treated in a high-temperature furnace to obtain HT-PyC / C composite material; The heat treatment process for the composite material is as follows: the composite material after carbon deposition and pyrolysis is placed in a high-temperature furnace, argon is introduced as a protective gas, and the equipment is heated to 1800℃ for 2 hours at a heating rate of 7℃ / min, so that the phenolic resin-based amorphous carbon is transformed into a highly oriented crystal structure.

[0075] Step 5: Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace and heat the equipment to 1000℃ at a heating rate of 3℃ / min. Then, CH3OH is introduced to deposit graphene for 3 hours.

[0076] The graphene deposition process involves maintaining a vacuum throughout the heating and cooling process. CH3OH gas is introduced while the chamber pressure is maintained at 9 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is shut off, and the prepared sample is removed after the equipment has cooled naturally.

[0077] Example 4 A method for preparing micro / nano hierarchical porous carbon framework materials includes the following steps: Step 1: Dissolve 15.0 g of resorcinol and 20.5 g of 37.5 wt% formaldehyde solution in 24.5 mL of deionized water to obtain a mixture; then add 0.036 g of cetyltrimethylammonium bromide (CTAB) to the mixture, and magnetically stir the suspension for 25 min to obtain a transparent precursor solution; Step 2: Immerse the polyurethane foam in the initial emulsion obtained in Step 1, so that the block is completely submerged, and then place it in a vacuum drying oven. Evacuate the oven until the pressure inside is below 0.09 MPa and maintain for 50 min. Then, heat curing, normal pressure drying and carbonization are carried out.

[0078] The heating, curing, drying and carbonization process is as follows: the porous carbon material of phenolic resin is placed in an oven at 80℃ and cured for 36 h; then it is dried at 95℃ under normal pressure for 16 h; then it is placed in a tube furnace and heated to 900℃ at 2℃ / min and held for 3 h, with argon gas introduced as a protective gas throughout the process to decompose the phenolic resin in the composite material into carbon. The selected polyurethane foam has a density of 0.032 g / cm³. 3 The pore size ranges from 200 μm.

[0079] Step 3: Place the carbonized sample in a CVD furnace, use argon as a protective gas, and heat the equipment to 1000℃ at a heating rate of 4℃ / min. Then, introduce CH4 to deposit PyC for 360 min, and repeat the deposition cycle 8 times.

[0080] The carbon deposition pyrolysis process is as follows: the argon flow rate is set to 2 L / min during the heating and cooling process, and the carbon deposition pyrolysis process is 3 L / min; then the temperature is cooled to room temperature to obtain a porous carbon matrix.

[0081] Step 4, High-temperature heat treatment: The composite material (PyC / C) with deposited pyrolytic carbon was heat-treated in a high-temperature furnace to obtain HT-PyC / C composite material; The heat treatment process for the composite material is as follows: the composite material after carbon deposition and pyrolysis is placed in a high-temperature furnace, argon is introduced as a protective gas, and the equipment is heated to 2000℃ for 3 hours at a heating rate of 8℃ / min, so that the phenolic resin-based amorphous carbon is transformed into a highly oriented crystalline structure.

[0082] Step 5: Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace and heat the equipment to 1100℃ at a heating rate of 4℃ / min. Then, CH3OH is introduced to deposit graphene for 4 hours.

[0083] The graphene deposition process involves maintaining a vacuum throughout the heating and cooling process. CH3OH gas is introduced while the chamber pressure is maintained at 9 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is shut off, and the prepared sample is removed after the equipment has cooled naturally.

[0084] Example 5 A method for preparing micro / nano hierarchical porous carbon framework materials includes the following steps: Step 1: Dissolve 13.5 g of resorcinol and 17.4 g of 37.5 wt% formaldehyde solution in 22.0 mL of deionized water to obtain a mixture; then add 0.031 g of hexadecyltrimethylammonium bromide (CTAB) to the mixture, and magnetically stir the suspension for 30 min to obtain a transparent precursor solution; Step 2: Immerse the polyurethane foam in the initial emulsion obtained in Step 1, so that the block is completely submerged, and then place it in a vacuum drying oven. Evacuate the oven until the pressure inside is below 0.09 MPa and maintain for 50 min. Then, heat curing, normal pressure drying and carbonization are carried out.

[0085] The heating, curing, drying and carbonization process is as follows: the porous carbon material of phenolic resin is placed in an oven at 85℃ and cured for 48 h; then it is dried at 100℃ under normal pressure for 24 h; then it is placed in a tube furnace and heated to 1000℃ at 4℃ / min and held for 4 h, with argon gas introduced as a protective gas throughout the process, so that the phenolic resin in the composite material is decomposed into carbon. The selected polyurethane foam has a density of 0.035 g / cm³. 3 The pore size ranges from 150 μm.

[0086] Step 3: Place the carbonized sample in a CVD furnace, use argon as a protective gas, and heat the equipment to 1100℃ at a heating rate of 4℃ / min. Then, introduce CH4 to deposit PyC for 420 min, and repeat the deposition cycle 8 times.

[0087] The carbon deposition pyrolysis process is as follows: the argon flow rate is set to 3 L / min during the heating and cooling process, and the carbon deposition pyrolysis process is 4 L / min; then the temperature is cooled to room temperature to obtain a porous carbon matrix.

[0088] Step 4, High-temperature heat treatment: The composite material (PyC / C) with deposited pyrolytic carbon was heat-treated in a high-temperature furnace to obtain HT-PyC / C composite material; The heat treatment process for the composite material is as follows: the composite material after carbon deposition and pyrolysis is placed in a high-temperature furnace, argon is introduced as a protective gas, and the equipment is heated to 2200℃ for 3 hours at a heating rate of 9℃ / min, so that the phenolic resin-based amorphous carbon is transformed into a highly oriented crystal structure.

[0089] Step 5: Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace and heat the equipment to 1200℃ at a heating rate of 5℃ / min. Then, CH3OH is introduced to deposit graphene for 6 hours.

[0090] The graphene deposition process involves maintaining a vacuum throughout the heating and cooling process. CH3OH gas is introduced while the chamber pressure is maintained at 9.5 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is shut off, and the prepared sample is removed after the equipment has cooled naturally.

[0091] Example 6 A method for preparing micro / nano hierarchical porous carbon framework materials includes the following steps: Step 1: Dissolve 15.0 g of resorcinol and 20.5 g of 37.5 wt% formaldehyde solution in 20.0 mL of deionized water to obtain a mixture; then add 0.036 g of cetyltrimethylammonium bromide (CTAB) to the mixture, and magnetically stir the suspension for 35 min to obtain a transparent precursor solution; Step 2: Immerse the polyurethane foam in the initial emulsion obtained in Step 1, so that the block is completely submerged, and then place it in a vacuum drying oven. Evacuate the oven until the pressure inside is below 0.09 MPa and maintain for 60 min. Then, heat curing, normal pressure drying and carbonization are carried out.

[0092] The heating, curing, drying and carbonization process is as follows: the porous carbon material of phenolic resin is placed in an oven at 90℃ and cured for 48 h; then it is dried at 100℃ under normal pressure for 24 h; then it is placed in a tube furnace and heated to 1100℃ at 5℃ / min and held for 4 h, with argon gas introduced as a protective gas throughout the process, so that the phenolic resin in the composite material is decomposed into carbon. The selected polyurethane foam has a density of 0.032 g / cm³. 3The pore size ranges from 150 μm.

[0093] Step 3: Place the carbonized sample in a CVD furnace, use argon as a protective gas, and heat the equipment to 1100℃ at a heating rate of 4℃ / min. Then, introduce CH4 to deposit PyC for 600 min and repeat the deposition cycle 8 times.

[0094] The carbon deposition pyrolysis process is as follows: the argon flow rate is set to 3 L / min during the heating and cooling process, and the carbon deposition pyrolysis process is 5 L / min; then the temperature is cooled to room temperature to obtain a porous carbon matrix.

[0095] Step 4, High-temperature heat treatment: The composite material (PyC / C) with deposited pyrolytic carbon was heat-treated in a high-temperature furnace to obtain HT-PyC / C composite material; The heat treatment process for the composite material is as follows: the composite material after carbon deposition and pyrolysis is placed in a high-temperature furnace, argon is introduced as a protective gas, and the equipment is heated to 2500℃ for 3 hours at a heating rate of 10℃ / min, so that the phenolic resin-based amorphous carbon is transformed into a highly oriented crystal structure.

[0096] Step 5: Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace and heat the equipment to 1200℃ at a heating rate of 5℃ / min. Then, CH3OH is introduced to deposit graphene for 8 hours.

[0097] The graphene deposition process involves maintaining a vacuum throughout the heating and cooling process. CH3OH gas is introduced while the chamber pressure is maintained at 9.5 kPa. After the deposition time is reached, the CH3OH gas is turned off, the heating program is shut off, and the prepared sample is removed after the equipment has cooled naturally.

[0098] Comparative Example 1 The high thermal conductivity porous framework C / C composite material was prepared using the same method as in Example 6, except that in the preparation of the high thermal conductivity porous framework C / C composite material, step 5 was modified from "Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace, heat the equipment to 1200°C at a heating rate of 5°C / min, and then introduce CH3OH to deposit graphene for 8 h." to "Place the heat-treated porous carbon material (HT-PyC / C) in a CVD furnace, heat the equipment to 1200°C at a heating rate of 5°C / min, and then introduce CH3OH to deposit graphene for 20 min."

[0099] Figure 1This is a flowchart illustrating the preparation method of the micro / nano-level porous carbon framework material of this invention. As shown in the diagram, porous polyurethane foam is used as a template, and phenolic resin solution is used as a precursor. After curing, drying, and carbonization, a phenolic resin-based porous carbon material is obtained. A pyrolytic carbon (PyC) coating layer is deposited on the porous framework using chemical vapor deposition (CVD) to obtain a porous carbon matrix. The changes in pore size and surface morphology of the sample with deposition time are observed. Then, a porous carbon framework with a highly crystalline orientation structure is obtained through high-temperature heat treatment. To achieve a micro / nano-level porous structure, a CVD process is used to introduce high specific surface area vertical graphene to construct a nanoscale pore structure, thus preparing the micro / nano-level porous carbon framework material.

[0100] Figure 2 This is the phenolic resin-based porous carbon material prepared in Example 3 of the present invention. As can be seen from the figure, the porous carbon successfully inherits the rich pore structure of polyurethane foam. The pores are completely interconnected by a carbon skeleton, forming a stable three-dimensional micron-scale network. At the same time, a nanoscale pore structure is formed on the carbon skeleton due to the vertical growth of graphene sheets.

[0101] Figure 3 These are comparative images of the vertical graphene morphology disclosed in Embodiments 4(a) and 6(b) of the present invention. As can be seen from the images, compared to Embodiment 6, with the extension of graphene deposition time, the graphene sheets exhibit vertical orientation growth, and the sheet size gradually increases, ultimately forming a three-dimensional interconnected porous network structure with a high specific surface area. Figure 4 The figures show a morphological comparison of the vertical graphene nanoscale porous structures disclosed in Examples 4(a) and 6(b) of this invention. As can be seen from the figures, (a) VG grows seamlessly on the surface of the porous carbon framework, forming a nanoscale porous structure, which is beneficial for enhancing the mechanical interlocking and interfacial coupling of the interface. With increasing graphene deposition time, (b) at the contact points of adjacent curved sheets, under continuous carbon source supply, bulk diffusion and local redeposition of carbon atoms occur, leading to thickening and strengthening of the contact points, forming robust nodes that connect the originally independent sheets into a more integrated mechanical network, and the pore size gradually decreases.

[0102] Figure 5 The XRD patterns of the phenolic resin-based porous carbon material (C), the porous carbon matrix (PyC / C) after pyrolytic carbon deposition, and the porous carbon framework with a highly crystalline orientation structure (HT-PyC / C) after high-temperature heat treatment are shown in Example 6 of this invention. As can be seen from the figures, the porous carbon is coated with pyrolytic carbon, resulting in a smaller pore size and a significantly increased degree of graphitization of the framework. Further high-temperature heat treatment and XRD characterization show that the diffraction peaks gradually become sharper and stronger, indicating a significant increase in the degree of graphitization of the carbon framework.

[0103] Figure 6The figure shows the morphology of the porous carbon framework material prepared in Comparative Example 1. As can be seen from the figure, compared with Example 6 of the present invention, the comparative example significantly shortened the process time of chemical vapor deposition of graphene. As shown in the figure, in the material obtained in the comparative example, the growth of graphene on the carbon framework surface is discontinuous, showing an uneven distribution phenomenon with obvious local enrichment and large-area exposed areas, and the graphene sheet structure is sparse and the coverage density is low. This structural difference directly leads to the degradation of material properties: First, the sparse and discontinuous graphene layer cannot construct a complete nanoporous network on the surface of the micron-scale carbon skeleton, which limits the increase in the specific surface area of ​​the material and fails to fully utilize the advantages of interfacial adsorption and reaction at the nanoscale; second, the non-uniformity of graphene coverage disrupts the continuity of the carbon skeleton surface, forming a large number of interfacial thermal resistance points, hindering the efficient conduction of phonons, and resulting in a significant decrease in the overall thermal conductivity of the material; thus, the present invention, by precisely controlling the CVD graphene deposition time to ensure the uniform and continuous growth of graphene on the carbon skeleton surface, is a key process step to achieve synergistic optimization of micro- and nano-level porous structures and to balance high thermal conductivity and high mass transfer efficiency.

[0104] In summary, this invention discloses a micro / nano-level porous carbon framework material and its preparation method. The method first uses porous foam as a template, impregnates it with a phenolic resin solution, and then proceeds with curing, drying, and high-temperature carbonization to obtain a phenolic resin-based porous carbon framework with a foam-like macroporous structure. Then, a pyrolytic carbon coating layer is deposited on this framework using chemical vapor deposition (CVD). By controlling the deposition time, the pore size of the framework is precisely controlled, and the connection and strengthening of the carbon fiber nodes are achieved, resulting in a structurally enhanced porous carbon matrix. Subsequently, high-temperature heat treatment transforms the carbon framework into a highly crystalline oriented structure, improving its intrinsic thermal conductivity. Finally, high-specific-surface-area vertical graphene is introduced onto the surface of the heat-treated framework using CVD to construct uniformly distributed nanoscale pores, forming a micro-nano-level porous structure that connects micron-sized foam pores and nanoscale graphene pores. The carbon framework material prepared by this invention possesses both excellent high thermal conductivity and high mass transfer efficiency, showing broad application prospects in thermal management, catalyst supports, and electrode materials.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a micro / nano hierarchical porous carbon framework material, characterized in that, include: Phenolic resin-based porous carbon material is prepared by impregnating porous foam in phenolic resin solution, followed by curing, drying and carbonization. A pyrolytic carbon coating layer was deposited on the phenolic resin-based porous carbon material using a chemical vapor deposition process to obtain a porous carbon matrix. After subjecting the porous carbon matrix to high-temperature heat treatment, a porous carbon framework with a highly crystalline orientation structure is obtained. Vertical graphene was introduced onto the surface of the porous carbon framework with a highly crystalline orientation structure using chemical vapor deposition to construct a nanoscale pore structure, thus obtaining a micro / nano-level porous carbon framework material.

2. The method for preparing micro / nano hierarchical porous carbon framework materials according to claim 1, characterized in that, The conditions for impregnating the porous foam in the phenolic resin solution are: vacuum impregnation for 30~60 min.

3. The method for preparing micro / nano-level porous carbon framework materials according to claim 1, characterized in that, The porous foam is a polyurethane foam having a pore size of 150 to 250 μm and a density of 0.028 to 0.035 g / cm 3 .

4. The method for preparing micro / nano hierarchical porous carbon framework materials according to claim 1, characterized in that, The curing conditions are: curing at 80~90℃ for 24~48 h; the drying conditions are: drying at 80~100℃ under normal pressure for 10~24 h; the carbonization conditions are: heating to 600~1100℃ at 2~5℃ / min under an argon atmosphere and holding for 2~4 h.

5. The method for preparing micro / nano hierarchical porous carbon framework materials according to claim 1, characterized in that, The chemical vapor deposition process for depositing the pyrolytic carbon coating layer is as follows: using argon as the protective gas, the temperature is increased to 900-1100℃ at a heating rate of 1-5℃ / min, followed by CH4 deposition for 60-600 min, with 5-8 deposition cycles; the argon flow rate is 1-3 L / min during the heating and cooling processes; and the argon flow rate is 2-5 L / min during CH4 deposition.

6. The method for preparing micro / nano hierarchical porous carbon framework materials according to claim 1, characterized in that, The conditions for the high-temperature heat treatment are as follows: in an argon atmosphere, the temperature is increased to 1600-2500℃ at a heating rate of 5-10℃ / min, and heated for 2-3 hours.

7. The method for preparing micro / nano-level porous carbon framework materials according to claim 1, characterized in that, The conditions for the chemical vapor deposition process of introducing vertical graphene are as follows: under vacuum conditions, the temperature is increased to 900-1200℃ at a heating rate of 1-5℃ / min, and then CH3OH is introduced for deposition for 1-8 h; wherein, the chamber pressure is maintained at 8-9.5 kPa while CH3OH gas is introduced.

8. The method for preparing micro / nano hierarchical porous carbon framework materials according to claim 1, characterized in that, The preparation of the phenolic resin precursor solution includes: using resorcinol and formaldehyde as carbon precursors, hexadecyltrimethylammonium bromide as surfactant and catalyst, and deionized water as solvent.

9. A micro / nano-level porous carbon framework material, characterized in that, The micro / nano hierarchical porous carbon framework material was prepared using the method described in any one of claims 1-8.

10. The micro / nano hierarchical porous carbon framework material according to claim 9, characterized in that, The micro / nano hierarchical porous carbon framework material has a dual-scale synergistic structure consisting of micron-level channels and nano-level pores. The micron-level channels are formed by polyurethane foam templates, and the nano-level pores are formed by in-situ growth of vertical graphene on the inner wall of the micron-level channels.

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