Three-dimensional porous carbon material, preparation method thereof and application of three-dimensional porous carbon material in supercapacitor

Abstract

The invention discloses a three-dimensional porous carbon material, a preparation method thereof and application of the three-dimensional porous carbon material in a supercapacitor. The preparation method comprises the following steps: uniformly dispersing asphalt powder and a chemical activating agent, and adsorbing through polyurethane foam, so that asphalt is fully loaded on a foam skeleton; and then pre-oxidation stabilization is carried out, and one-step high-temperature carbonization and activation are realized in an inert atmosphere. The core of the method is to perform in-situ etching on an asphalt carbon skeleton at a high temperature by virtue of a three-dimensional macroscopic template effect of polyurethane foam in combination with a chemical activator, so that a porous carbon material with a three-dimensional interconnected macroporous channel and a graded microporous / mesoporous structure is synchronously constructed. When the material is used as a supercapacitor electrode, the material has a high specific surface area, an optimized pore structure and an efficient electron / ion transmission path, and shows high specific capacitance, excellent rate capability and long-term cycle stability. The method is simple in technological process, low in raw material cost and easy for large-scale preparation, and has remarkable practical value and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of novel carbon materials technology, specifically relating to a porous carbon material with a three-dimensional interconnected hierarchical pore structure, its preparation method, and its application as an electrode material in supercapacitors. Background Technology

[0002] Supercapacitors are energy storage devices that fall between traditional capacitors and rechargeable batteries. They combine the advantages of capacitors, such as rapid charging and discharging and long lifespan, with the high energy density of rechargeable batteries. Therefore, they are widely used in new energy, military defense, and aerospace fields. Compared to rechargeable batteries, supercapacitors offer advantages such as a wider operating temperature range, higher power density, faster charging and discharging speeds, and longer cycle life.

[0003] Supercapacitors, with their high power density and long cycle life, are crucial electrochemical energy storage devices, and their performance hinges on the electrode materials. Porous carbon materials are widely used due to their high specific surface area, excellent conductivity, and stable chemical properties. An ideal porous carbon electrode should possess a high specific surface area to provide ample charge adsorption sites, while also exhibiting a hierarchical pore structure (micropores, mesopores, and macropores working in tandem) to balance ion storage and rapid transport. Currently, common methods for preparing hierarchical porous carbon, such as template methods (hard templates, soft templates), are often cumbersome, with complex template removal processes that may damage the structure, leading to high costs and difficulties in large-scale production. While simple chemical activation methods can effectively create pores, they typically struggle to independently construct a macroscopically interconnected three-dimensional framework structure, resulting in materials with poor mechanical strength and limited rate performance. Therefore, developing a novel porous carbon material preparation method that is simple, low-cost, and can integrate the construction of a macroscopically three-dimensional framework and microscopically hierarchical pores is of great significance for promoting the application of high-performance supercapacitors.

[0004] This invention introduces a method for preparing a three-dimensional porous carbon material. Using polyurethane foam as a template, a chemical activator is added, and the material undergoes preliminary heat treatment, pre-oxidation, and high-temperature activation / carbonization to obtain a three-dimensional porous carbon material with a highly interconnected pore structure. This material has a high specific surface area and a reasonable micropore / mesopore size distribution, which is beneficial for charge storage and exhibits excellent supercapacitor performance. Summary of the Invention

[0005] The primary objective of this invention is to overcome the shortcomings of the prior art and provide a three-dimensional porous carbon material that is simple to prepare and uses inexpensive raw materials.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned three-dimensional porous carbon material. This method ingeniously combines the template function of polyurethane foam with the function of asphalt carbonization to form a conductive skeleton, and uses chemical activators to simultaneously achieve in-situ pore formation, thus constructing an integrated structure of macroscopic three-dimensional interconnection and microscopic hierarchical pores in one step.

[0007] The purpose of this invention is to provide a three-dimensional porous carbon and its preparation method suitable for applications such as supercapacitors, resulting in a three-dimensional porous carbon material with high specific surface area and reasonable pore size distribution. Furthermore, this material possesses multi-field adaptability, and can be used as a high-performance adsorbent for the removal of gaseous / liquid phase pollutants, as a highly dispersed support for loading catalytically active components, and as a supporting framework for silicon-carbon anodes to suppress the volume expansion of silicon-based materials, demonstrating broad application prospects.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing a three-dimensional porous carbon material, characterized by comprising the following steps:

[0010] (1) Preparation of precursor composite foam: Asphalt powder and chemical activator are uniformly dispersed in deionized water to form a suspension; a polyurethane foam template is immersed in the suspension, and the mixture of asphalt and activator is fully adsorbed by repeated squeezing and releasing, and then dried at 60~100 ℃ to obtain precursor composite foam;

[0011] (2) Pre-oxidation stabilization: Under the protection of an inert atmosphere, the composite foam obtained in step (1) is subjected to preliminary heat treatment at 120~180 ℃ for 0.5~3 h, and then subjected to pre-oxidation treatment at 200~280 ℃ for 1~5 h in an oxygen-containing atmosphere, so that the asphalt is transformed from thermoplastic to thermosetting, and a structurally stable pre-oxidized intermediate is obtained.

[0012] (3) Carbonization and activation: Under the protection of an inert atmosphere, the pre-oxidized intermediate obtained in step (2) is heated to 600-1000 ℃ at a heating rate of 1-10 ℃ / min and carbonized at this temperature for 1-5 h. During this process, the polyurethane foam and asphalt are pyrolyzed and carbonized to form a three-dimensional conductive skeleton. At the same time, the chemical activator and asphalt undergo an in-situ activation reaction, generating abundant micropores and mesopores on the surface and inside of the skeleton.

[0013] (4) Post-processing: The carbonized sample is acid washed, water washed until neutral, and dried to obtain the three-dimensional porous carbon material.

[0014] Preferably, in step (1), the asphalt is one or more of petroleum asphalt, coal tar pitch, ethylene tar pitch, or mesophase asphalt.

[0015] Preferably, in step (1), the chemical activator is one or more of KOH, K2CO3 or ZnCl2.

[0016] Preferably, in step (1), the mass ratio of the asphalt, polyurethane foam and chemical activator is (0.5~2.5):1:(1~10).

[0017] Preferably, in step (3), the carbonization temperature is 600~1000 ℃. This temperature range is conducive to forming a carbon skeleton with moderate graphitization and good conductivity, and has high activation and pore-forming efficiency.

[0018] Compared with existing technologies, the beneficial effects of the three-dimensional porous carbon material for supercapacitors and its preparation method provided by this invention are reflected in the following aspects:

[0019] (1) Process innovation and simplification: This invention creatively combines the dual functions of polyurethane foam (physical template and carbon source) with chemical activation, realizing the simultaneous completion of "template construction-skeleton formation-in-situ pore creation" in one step. The process is simplified, the production efficiency is high, the cost is significantly reduced, and it has great potential for industrialization.

[0020] (2) Unique Material Structure: The prepared three-dimensional porous carbon material has a unique multi-level hierarchical structure. Macroscopically, it fully inherits the open-cell foam structure of polyurethane foam, forming a three-dimensional interconnected macroporous framework, providing a "highway" for rapid ion transport; microscopically, through chemical activation, a large number of micropores and mesopores are generated in situ on the carbon framework wall, providing a large specific surface area and abundant charge storage sites. This hierarchical pore system with macropores and micro / mesopores working together effectively solves the technical contradiction of balancing high specific surface area and high ion conductivity.

[0021] (3) Raw materials are economical and environmentally friendly: The main raw materials are inexpensive asphalt and commercial or waste polyurethane foam, which are widely available and meet the requirements of green and sustainable development. Attached Figure Description

[0022] Figure 1 This is a SEM image of the three-dimensional porous carbon prepared in Example 1;

[0023] Figure 2 The image shows the XRD pattern of the three-dimensional porous carbon prepared in Example 1.

[0024] Figure 3 The nitrogen adsorption / desorption curves are for the three-dimensional porous carbon prepared in Example 1.

[0025] Figure 4 The pore size distribution curve of the three-dimensional porous carbon prepared in Example 1 is shown.

[0026] Figure 5 The CV curve of the three-dimensional porous carbon prepared in Example 1 applied to a supercapacitor;

[0027] Figure 6 The GCD curve of the three-dimensional porous carbon prepared in Example 1 applied to a supercapacitor;

[0028] Figure 7 This is a SEM image of the three-dimensional porous carbon prepared in Example 2;

[0029] Figure 8 The CV curve of the three-dimensional porous carbon prepared in Example 2 applied to a supercapacitor;

[0030] Figure 9 The GCD curve of the three-dimensional porous carbon prepared in Example 2 applied to a supercapacitor;

[0031] Figure 10 This is a SEM image of the three-dimensional porous carbon prepared in Example 3;

[0032] Figure 11 The nitrogen adsorption / desorption curves are for the three-dimensional porous carbon prepared in Example 3.

[0033] Figure 12 The CV curve of the three-dimensional porous carbon prepared in Example 3 applied to a supercapacitor;

[0034] Figure 13 The GCD curve of the three-dimensional porous carbon prepared in Example 3 applied to a supercapacitor;

[0035] Figure 14 The GCD curve of the three-dimensional porous carbon prepared in Example 4 applied to a supercapacitor;

[0036] Figure 15 The image shows the SEM image of the control sample 1 prepared in Comparative Example 1.

[0037] Figure 16 The nitrogen adsorption / desorption curve of the control sample 1 prepared in Comparative Example 1 is shown.

[0038] Figure 17 The GCD curve of the control sample 1 prepared in Comparative Example 1 applied to a supercapacitor;

[0039] Figure 18 This is a SEM image of the control sample 2 prepared in Comparative Example 2;

[0040] Figure 19 The nitrogen adsorption / desorption curve of the control sample 2 prepared in Comparative Example 2 is shown.

[0041] Figure 20 The GCD curve of the control sample 2 prepared in Comparative Example 2 is obtained when it is applied to a supercapacitor. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the implementation process of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0043] The endpoints and any values ​​disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0044] In this invention, the scanning electron microscope (SEM) test is performed using a field emission scanning electron microscope.

[0045] In this invention, the specific surface area and pore size distribution curves of the sample are obtained by nitrogen adsorption / desorption test, and the specific surface area is analyzed using the BET model.

[0046] In this invention, the electrochemical testing method is as follows: Three-dimensional porous carbon, Super-p conductive carbon black, and PVDF (polyvinylidene fluoride) binder are mixed uniformly in a mass ratio of 8:1:1, and then coated onto nickel foam, controlling the areal density to be 2 mg / cm³. 2 After drying and thinning, the electrode was used as the working electrode. A three-electrode supercapacitor was assembled using a platinum sheet as the counter electrode, mercury / mercuric oxide as the reference electrode, and 6 mol / L KOH as the electrolyte. Electrochemical performance tests were then conducted on an electrochemical workstation.

[0047] Cyclic voltammetry tests at different scan rates: 5 mV / s, 10 mV / s, 20 mV / s, 50 mV / s, 100 mV / s;

[0048] Constant current charge-discharge tests at different current densities: 0.5 A / g, 1 A / g, 2 A / g, 5 A / g, 10 A / g.

[0049] Example 1

[0050] Three-dimensional porous carbon was first prepared using the following method:

[0051] Preparation of precursor composite foam: Fine petroleum asphalt powder, polyurethane (PU) foam, and K2CO3 were weighed according to a mass ratio of 2:1:6. The asphalt powder and K2CO3 were added to 20 mL of deionized water and magnetically stirred for 1 h to form a uniform suspension. The PU foam was immersed in the suspension and repeatedly squeezed / released dozens of times to ensure full adsorption. Subsequently, it was dried at 60 ℃ for 12 h to obtain the precursor composite foam.

[0052] Pre-oxidation stabilization: The dried composite foam was placed in a tube furnace and first heat-treated at 160 °C at 2 °C / min under an argon atmosphere, holding for 1 h. Then, the atmosphere was switched to oxygen, and the temperature was increased to 240 °C at 2 °C / min for pre-oxidation stabilization for 3 h. After the process, it was allowed to cool naturally to room temperature to obtain the pre-oxidized intermediate.

[0053] Carbonization and activation: Under argon protection, the pre-oxidized intermediate was heated to 800 °C at a heating rate of 5 °C / min and carbonized at this temperature for 3 h.

[0054] Post-processing: After cooling, the carbonized sample was immersed in 1 M HCl solution for 24 h to remove impurities, and then washed with deionized water until neutral. Finally, it was dried in an oven at 60 ℃ for 24 h to obtain a three-dimensional porous carbon material, denoted as 3D-PC-1.

[0055] Scanning electron microscope (SEM) and X-ray diffraction (XRD) patterns of the 3D-PC-1 in Example 1 are as follows: Figure 1 and Figure 2 As shown, 3D-PC-1 inherits the cross-linked network structure of polyurethane foam, and has many wrinkles in the pore walls and the interior of the macropores. The carbon wall surface is rough, which is caused by K2CO3 activation. 3D-PC-1 also exhibits an amorphous carbon structure.

[0056] The nitrogen adsorption / desorption curves and pore size distribution of 3D-PC-1 in Example 1 are as follows: Figure 3 and Figure 4 As shown, the specific surface area of ​​3D-PC-1 is 1550.4 m². 2 / g. The nitrogen adsorption / desorption curves show a rapid rise in the high-pressure region, indicating the presence of numerous micropores in the sample. Furthermore, the presence of hysteresis loops in the curves suggests that 3D-PC-1 also possesses a certain degree of mesoporous structure. The pore size distribution curves show that the pore structure is mainly concentrated in the 0.5-2.5 nm range, and the specific surface area provided by the micropores is 1059.2 m². 2 / g.

[0057] Furthermore, to investigate the application performance of the 3D-PC-1 prepared in this embodiment in a supercapacitor, 3D-PC-1 was used as the active material to fabricate the working electrode, and a three-electrode supercapacitor was assembled for electrochemical testing. Its CV curve and GCD curve are shown below. Figure 5 and Figure 6 As shown, at a current density of 1 A / g, its specific capacitance is 131.5 F / g. Furthermore, the shapes of the CV and GCD curves indicate that the capacitance of this supercapacitor is mainly provided by the double-layer capacitance with a small amount of pseudocapacitance, and it exhibits good electrochemical reversibility.

[0058] Example 2

[0059] Three-dimensional porous carbon was first prepared using the following method:

[0060] The steps are the same as in Example 1, the main difference being that the asphalt used is coal tar pitch, the pre-oxidation temperature is 260 ℃, and the carbonization activation temperature is 900 ℃.

[0061] Preparation of precursor composite foam: Coal tar powder, polyurethane (PU) foam, and K2CO3 were weighed according to a mass ratio of 2:1:6. The asphalt powder and K2CO3 were added to 20 mL of deionized water and magnetically stirred for 1 h to form a uniform suspension. The PU foam was immersed in the suspension and repeatedly squeezed / released dozens of times to ensure full adsorption. Subsequently, it was dried at 60 ℃ for 12 h to obtain the precursor composite foam.

[0062] Pre-oxidation stabilization: The dried composite foam was placed in a tube furnace and first heated to 160 °C at 2 °C / min under an argon atmosphere, and held at that temperature for 1 h for heat treatment. Subsequently, the atmosphere was switched to oxygen, and the temperature was raised to 260 °C for pre-oxidation stabilization treatment for 3 h. After the process was completed, it was naturally cooled to room temperature to obtain the pre-oxidized intermediate.

[0063] Carbonization and activation: Under argon protection, the pre-oxidized intermediate was heated to 900 °C at a heating rate of 5 °C / min and carbonized at this temperature for 3 h.

[0064] Post-processing: After cooling, the carbonized sample was immersed in 1 M HCl solution for 24 h to remove impurities, and then washed with deionized water until neutral. Finally, it was dried in a vacuum oven at 60 ℃ for 24 h to obtain a three-dimensional porous carbon material, denoted as 3D-PC-2.

[0065] Scanning electron microscope (SEM) image of the 3D-PC-2 in Example 2: Figure 7 As shown, 3D-PC-2 inherits the cross-linked network structure of polyurethane foam, and has many wrinkles in the pore walls and the interior of the macropores. The surface of the carbon wall is rough, which is caused by K2CO3 activation.

[0066] Furthermore, to investigate the application performance of the 3D-PC-2 prepared in this embodiment in a supercapacitor, 3D-PC-2 was used as the active material to fabricate the working electrode, and a three-electrode supercapacitor was assembled for electrochemical testing. Its CV curve and GCD curve are shown below. Figure 8 and Figure 9 As shown, at a current density of 1 A / g, its specific capacitance is 106.1 F / g. Furthermore, the shapes of the CV and GCD curves indicate that the capacitance of this supercapacitor is mainly provided by the double-layer capacitance with a small amount of pseudocapacitance, and it exhibits good electrochemical reversibility.

[0067] Example 3

[0068] Three-dimensional porous carbon was first prepared using the following method:

[0069] The steps are the same as in Example 1, the main difference being that the activator used is KOH, the ratio of petroleum asphalt, polyurethane (PU) foam and activator KOH is 2:1:4, the pre-oxidation stabilization atmosphere is air, and the temperature is 280 ℃.

[0070] Preparation of precursor composite foam: Petroleum asphalt powder, polyurethane (PU) foam, and KOH were weighed according to a mass ratio of 2:1:4. The asphalt powder and KOH were added to 20 mL of deionized water and magnetically stirred for 1 h to form a uniform suspension. The PU foam was immersed in the suspension and repeatedly squeezed / released dozens of times to ensure full adsorption. Subsequently, it was dried at 60 ℃ for 12 h to obtain the precursor composite foam.

[0071] Pre-oxidation stabilization: The dried composite foam was placed in a tube furnace and first heat-treated at 160 °C at 2 °C / min under an argon atmosphere, holding for 1 h. Then, the atmosphere was switched to air, and the temperature was increased to 280 °C at 2 °C / min for pre-oxidation stabilization for 3 h. After the process, it was allowed to cool naturally to room temperature to obtain the pre-oxidized intermediate.

[0072] Carbonization and activation: Under argon protection, the pre-oxidized intermediate was heated to 800 °C at a heating rate of 5 °C / min and carbonized at this temperature for 3 h.

[0073] Post-processing: After cooling, the carbonized sample was immersed in 1 M HCl solution for 24 h to remove impurities, and then washed with deionized water until neutral. Finally, it was dried in a vacuum oven at 60 ℃ for 24 h to obtain a three-dimensional porous carbon material, denoted as 3D-PC-3.

[0074] Scanning electron microscope (SEM) image of 3D-PC-3 in Example 3, as shown Figure 10As shown, 3D-PC-3 inherits the cross-linked network structure of polyurethane foam, and has many wrinkles in the pore walls and the interior of the macropores. The surface of the carbon wall is rough, which is caused by KOH activation.

[0075] The nitrogen adsorption / desorption curves of 3D-PC-3 in Example 3 are as follows: Figure 11 As shown, the specific surface area of ​​3D-PC-3 is 2020.5 m². 2 / g. The nitrogen adsorption / desorption curves show a rapid rise in the high-pressure region, indicating the presence of numerous micropores in the sample. Furthermore, the presence of hysteresis loops in the curves suggests that 3D-PC-3 also possesses a certain degree of mesoporous structure.

[0076] Furthermore, to investigate the application performance of the 3D-PC-3 prepared in this embodiment in a supercapacitor, 3D-PC-3 was used as the active material to fabricate the working electrode, and a three-electrode supercapacitor was assembled for electrochemical testing. Its CV and GCD curves are shown below. Figure 12 and Figure 13 As shown, at a current density of 1 A / g, its specific capacitance is 145.3 F / g. Furthermore, the shapes of the CV and GCD curves indicate that the capacitance of this supercapacitor is mainly provided by the double-layer capacitance with a small amount of pseudocapacitance, and it exhibits good electrochemical reversibility.

[0077] Example 4

[0078] Three-dimensional porous carbon was first prepared using the following method:

[0079] The steps are the same as in Example 1, the main difference being that the activator used is ZnCl2, and the ratio of petroleum asphalt, polyurethane (PU) foam, and activator ZnCl2 is 2:1:6.

[0080] Preparation of precursor composite foam: Petroleum asphalt powder, polyurethane (PU) foam, and ZnCl2 were weighed according to a mass ratio of 2:1:6. The asphalt powder and ZnCl2 were added to 20 mL of deionized water and magnetically stirred for 2 h to form a uniform suspension. The PU foam was immersed in the suspension and repeatedly squeezed / released dozens of times to ensure full adsorption. Subsequently, it was dried at 60 ℃ for 12 h to obtain the precursor composite foam.

[0081] Pre-oxidation stabilization: The dried composite foam was placed in a tube furnace and first stabilized at 160 °C at 2 °C / min under an argon atmosphere for 1 h. Then, the atmosphere was switched to oxygen, and the temperature was increased to 280 °C for pre-oxidation for 3 h. After the process, it was allowed to cool naturally to room temperature to obtain the pre-oxidized intermediate.

[0082] Carbonization and activation: Under argon protection, the pre-oxidized intermediate was heated to 800 °C at a heating rate of 5 °C / min and carbonized at this temperature for 3 h.

[0083] Post-processing: After cooling, the carbonized sample was immersed in 1 M HCl solution for 24 h to remove impurities, and then washed with deionized water until neutral. Finally, it was dried in a vacuum oven at 60 ℃ for 24 h to obtain a three-dimensional porous carbon material, denoted as 3D-PC-4.

[0084] Furthermore, to investigate the application performance of the 3D-PC-4 prepared in this embodiment in a supercapacitor, 3D-PC-4 was used as the active material to fabricate the working electrode, and a three-electrode supercapacitor was assembled for electrochemical testing. Its GCD curve is shown below. Figure 14 As shown, its specific capacitance is 70.6 F / g when the current density is 1 A / g.

[0085] Comparative Example 1

[0086] Petroleum asphalt was thoroughly ground in a mortar and sieved through a 400-mesh standard sieve to obtain fine asphalt powder. An appropriate amount of the fine petroleum asphalt powder was placed in a ceramic boat and then placed in a tube furnace. Under an argon atmosphere, the temperature was raised to 800 °C at a rate of 5 °C / min and held at this temperature for carbonization for 3 h. After cooling to room temperature, petroleum asphalt-derived carbon material was obtained, designated as control sample 1.

[0087] The scanning electron microscope (SEM) and nitrogen adsorption / desorption curve of the control sample 1 prepared in Comparative Example 1 are shown below. Figure 15 and Figure 16 As shown, it was observed to be a dense, irregular block formed by the melting and carbonization of asphalt, lacking any ordered porous framework. Nitrogen adsorption / desorption tests indicated that the specific surface area of ​​control sample 1 was 1.5 m². 2 / g, with an extremely low specific surface area and almost no well-developed pore structure.

[0088] Furthermore, to investigate the application performance of the control sample 1 prepared in this comparative example in a supercapacitor, control sample 1 was used as the active material to prepare the working electrode, and assembled into a three-electrode supercapacitor for electrochemical testing. Its GCD curve is shown below. Figure 17 As shown, it can be found that at a current density of 1 A / g, its specific capacitance is 2.8 F / g, which is almost negligible. This indicates that without template support and activation pore-forming steps, direct carbonization of asphalt cannot form an effective electrode material.

[0089] Comparative Example 2

[0090] First, comparative sample 2 was prepared according to the following preparation method:

[0091] (1) Preparation of precursor composite foam: Weigh 2.0 g of petroleum asphalt fine powder and 1.0 g of polyurethane foam (mass ratio 2:1). Disperse the asphalt fine powder in deionized water, and then use polyurethane foam to repeatedly squeeze and agitate to adsorb the suspension, so that the asphalt is loaded onto the foam skeleton. Dry at 60 ℃ for 12 h to obtain precursor composite foam.

[0092] (2) Pre-oxidation stabilization: The sample obtained in step (1) was heated to 160 °C at 2 °C / min under an argon atmosphere and heat-treated for 1 h; then it was heated to 240 °C at 2 °C / min under an oxygen atmosphere and pre-oxidated and stabilized for 3 h, and then cooled to room temperature.

[0093] (3) Carbonization: Under an argon atmosphere, the sample obtained in step (2) was heated to 800℃ at a heating rate of 5℃ / min and carbonized for 3 h. After cooling, carbon material was obtained and recorded as control sample 2.

[0094] The scanning electron microscope (SEM) and nitrogen adsorption / desorption curves of the control sample 2 prepared in Comparative Example 2 are shown below. Figure 18 and Figure 19 As shown, control sample 2 replicated the three-dimensional interconnected macroporous framework structure of polyurethane foam, but its framework surface was relatively smooth and dense, lacking rough pores. Nitrogen adsorption / desorption tests indicated that control sample 2 had a specific surface area of ​​1.3 m². 2 / g, with an extremely low specific surface area and almost no well-developed microporous structure.

[0095] Furthermore, to investigate the application performance of the control sample 2 prepared in this comparative example in a supercapacitor, control sample 2 was used as the active material to make the working electrode, and assembled into a three-electrode supercapacitor for electrochemical testing. Its GCD curve is shown in Figure 1. Figure 20 As shown, the material exhibits weak pseudocapacitive characteristics (possibly due to the introduction of the PU foam template), but the rectangular characteristics of the double-layer capacitance are not obvious. The GCD curve calculation shows a specific capacitance of 33.5 F / g at a current density of 1 A / g, far lower than that of materials such as Example 1 of this invention (131.5 F / g). This indicates that the material's charge storage capacity is severely limited due to the lack of a macroscopic macroporous framework without microscopic hierarchical channels to provide a large specific surface area and ion transport channels.

Claims

1. A method for producing a three-dimensional porous carbon material, characterized by, The method comprises the following steps: (1) Preparation of precursor composite foam: mixing pitch powder, chemical activator and polyurethane foam template in liquid phase, loading the pitch powder and chemical activator on the three-dimensional skeleton of the polyurethane foam template, and obtaining the precursor composite foam after drying; (2) Pre-oxidation treatment: heat treating the precursor composite foam obtained in step (1) at 200-280 ℃ for 1-5 h in an oxygen-containing atmosphere to heat-solidify the pitch; (3) Carbonization and activation: carbonizing the sample treated in step (2) at 600-1000 ℃ under the protection of inert atmosphere, forming a three-dimensional conductive skeleton, and simultaneously activating and pore-forming the carbonized products of pitch and polyurethane foam by using the chemical activator; (4) Purification and drying: removing the residual activator and by-products in the carbon material obtained in step (3), and obtaining the three-dimensional porous carbon material after washing and drying.

2. The production method according to claim 1, characterized by, The pitch in step (1) is one or more of petroleum pitch, coal pitch, ethylene tar pitch and mesophase pitch.

3. The preparation method according to claim 1, characterized in that, The mass ratio of pitch, polyurethane foam and chemical activator in step (1) is (0.5-2.5):1:(1-10).

4. The method of claim 1, wherein, The activator in step (3) is one or more of K2CO3, KOH and ZnCl2.

5. A three-dimensional porous carbon material produced by the production method according to any one of claims 1 to 4, characterized by, The material has a three-dimensional interconnected macroporous skeleton obtained by carbonizing polyurethane foam and pitch, and micropores and mesopores generated by chemical activation are distributed on the skeleton, forming a hierarchical porous structure.

6. An ultracapacitor, characterized by, The working electrode comprises the three-dimensional porous carbon material of claim 5.

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