Petroleum pitch-based composite porous carbon, preparation method thereof and supercapacitor

Abstract

The application discloses petroleum pitch-based composite porous carbon and a preparation method and a super capacitor thereof, and belongs to the technical field of super capacitor electrode materials, and the method comprises the following steps: ball-milling blocky petroleum pitch and a dispersing agent together, then screening and drying to obtain petroleum pitch powder; then mixing and grinding the petroleum pitch powder with phenolic resin and multi-walled carbon nanotubes, adding a grinding aid, uniformly grinding, compacting, pre-carbonizing under a protective atmosphere, cooling, and obtaining a pre-carbonized product; uniformly mixing the pre-carbonized product with potassium hydroxide, carbonizing and activating under a protective atmosphere, cooling, and obtaining a crude product; sequentially performing acid washing, water washing and alcohol washing on the crude product, and drying to obtain petroleum pitch-based composite porous carbon. The composite porous carbon has the advantages of a high specific surface area micropore dominant structure, a low resistivity three-dimensional conductive network and nitrogen-doped pseudo-capacitance activity, and the synergistic improvement of the energy density, the power density and the cycle stability of the super capacitor electrode material is realized.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor electrode material technology, specifically relating to a petroleum pitch-based composite porous carbon, its preparation method, and a supercapacitor. Background Technology

[0002] Supercapacitors, as novel energy storage devices, are in high demand in fields such as new energy vehicles and smart grids due to their fast charging and discharging speeds, long cycle life, and strong environmental adaptability. Their performance hinges on the electrode materials. Porous carbon, with its large specific surface area, tunable pore structure, and excellent conductivity, has become the mainstream choice for supercapacitor electrode materials. However, existing porous carbon preparation technologies still face numerous bottlenecks, making it difficult to meet the dual demands of high performance and industrialization. Currently, porous carbon sources are mostly biomass (such as coconut shells and wood chips) or pure organic carbon sources (such as sucrose and resin). Biomass carbon sources suffer from low carbon yield and poor pore structure uniformity, while pure organic carbon sources are costly and unsuitable for large-scale applications. Although petroleum asphalt, an industrial byproduct, has high carbon content and low cost, its blocky structure easily agglomerates, requiring complex pretreatment before it can be used in porous carbon preparation. Existing pretreatment processes (such as solvent dissolution) easily introduce pollution and make it difficult to achieve uniform compounding with other components in the subsequent process. In terms of optimizing conductivity, existing technologies often add conductive enhancers such as carbon nanotubes (CNTs) and graphene. However, due to the lack of effective dispersion methods, the conductive agents tend to agglomerate and cannot form a continuous conductive network with the carbon matrix, resulting in a high volume resistivity of the material (typically >1.5Ω). The activation process, which traditionally uses strong bases such as KOH and NaOH as activators to construct porous structures, suffers from excessive reactivity that can lead to over-etching of the carbon framework, resulting in uneven pore size distribution (micropore ratio often <60%). Furthermore, subsequent purification requires large amounts of acid and alkali, causing significant pollution. Some processes attempt to perform activation and doping in steps, but improper process integration leads to uneven distribution of dopant elements such as nitrogen, making it difficult to simultaneously achieve a high specific surface area (>2000 m²). g - ¹) High doping efficiency. In addition, existing preparation processes often require high-temperature and high-pressure equipment or toxic solvents, resulting in high energy consumption and environmental costs, as well as low raw material utilization (such as adding 3-5 times the amount of activator), which further limits industrialization.

[0003] Chinese patent application CN119581238A discloses a method for preparing porous carbon using enzymatic hydrolysis of lignin as the carbon source and potassium carbonate and potassium dihydrogen citrate as a composite activator via one-step carbonization, for use as a supercapacitor electrode material. This material exhibits a specific capacitance of up to 310 F / g in 6MKOH electrolyte and good cycling stability (99.5% retention after 10,000 cycles). While the use of a dual-potassium salt composite activation avoids the use of a template agent, the activation mechanism relies on the etching effect of the potassium salt, limiting the precision of pore size control and making it difficult to accurately construct a hierarchical porous structure. Furthermore, the lack of conductivity-enhancing components means the material's conductivity depends on the carbonization process itself, which is insufficient for constructing a conductive network for high-power applications. Chinese patent application CN116721877A discloses a multi-step process for preparing nitrogen-phosphorus co-doped hierarchical porous carbon with a specific surface area as high as 3159 m², using coal tar pitch as a carbon source and involving air pre-oxidation, melamine / urea nitrogen doping, hexachlorocyclotriphosphazene phosphorus doping, and KOH activation. 2 / g, with a specific capacitance of 399.5 F / g. Although heteroatom doping was achieved, the enhanced conductivity still relies on the carbon matrix itself, without the introduction of an external conductive network, resulting in significant performance degradation at high currents.

[0004] Therefore, developing a porous carbon preparation technology that uses low-cost petroleum asphalt as raw material, can achieve uniform component compounding and precise control of pore structure, and takes into account both economy and environmental protection, has become the key to breaking through the performance bottleneck of supercapacitor electrode materials. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a petroleum pitch-based composite porous carbon, its preparation method and a supercapacitor, so as to solve the technical problems of poor bonding between the conductive components and the carbon matrix of existing porous carbon materials, difficulty in controlling the pore structure, difficulty in synergizing conductivity and pore structure and complex process.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing petroleum pitch-based composite porous carbon, comprising: Blocky petroleum asphalt and a dispersant were ball-milled together, then sieved and dried to obtain petroleum asphalt powder. The petroleum asphalt powder, phenolic resin, and multi-walled carbon nanotubes were mixed and ground together, a grinding aid was added, and after grinding evenly, the mixture was compacted to obtain a composite precursor. The composite precursor was pre-carbonized under a protective atmosphere, and after cooling, a pre-carbonized product was obtained. The pre-carbonized product was mixed evenly with potassium hydroxide, and carbonized and activated under a protective atmosphere. After cooling, a crude product was obtained. The crude product was successively acid-washed, water-washed, and alcohol-washed, and after drying, a petroleum asphalt-based composite porous carbon was obtained.

[0007] Preferably, the dispersant is sodium dodecylbenzenesulfonate or polyvinylpyrrolidone.

[0008] Preferably, the mass ratio of petroleum asphalt powder, phenolic resin and multi-walled carbon nanotubes is (2-4):(1-3):(0.05-0.1).

[0009] Preferably, the grinding aid is anhydrous ethanol; the compaction pressure is 0.3-0.6 MPa, and the holding time is 5-15 s.

[0010] Preferably, the protective atmosphere is argon; the mass ratio of potassium hydroxide to the pre-carbonized product is (3-4):1.

[0011] Preferably, the pre-carbonization heating rate is 4-6℃ / min, the temperature is 350-370℃, and the holding time is 1-2h.

[0012] Preferably, the heating rate for carbonization activation is 4-6℃ / min, the temperature is 750-800℃, and the holding time is 1-2h.

[0013] This invention discloses a petroleum asphalt-based composite porous carbon, prepared using the aforementioned method; the specific surface area of ​​the petroleum asphalt-based composite porous carbon is 2012-2310 m². 2 ·g -1 The total pore volume is 1.0-1.2 cm³. 3 ·g -1 The micropore ratio is greater than 65%, at 1 A·g -1 The specific capacitance at current density is 325-358 F·g -1 Its volume resistivity is less than 1.0 Ω·cm.

[0014] This invention discloses an electrode for a supercapacitor, using the above-mentioned petroleum asphalt-based composite porous carbon as the active material; it is prepared by mixing petroleum asphalt-based composite porous carbon with binder and conductive agent in a mass ratio of (7.5-8.5):(0.5-1):(0.5-2) and coating it onto a current collector.

[0015] The present invention discloses a supercapacitor comprising the electrodes for a supercapacitor described above.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing petroleum asphalt-based composite porous carbon. Addressing the issue of poor bonding between conductive components and the carbon matrix, the method involves solid-state grinding and compaction of petroleum asphalt powder, phenolic resin, and multi-walled carbon nanotubes (CNTs) before carbonization and activation. Physical and mechanical forces induce preliminary dispersion and embedding of CNTs within the composite precursor, laying a uniform dispersion foundation for the formation of strong chemical bonds between CNTs and the generated carbon matrix during subsequent carbonization. This effectively prevents the agglomeration of conductive agents, ensuring a continuous and efficient electron transport network within the final material and achieving a low volume resistivity (e.g., 0.85 Ω·cm in Example 1). To address the challenge of controlling the pore structure, pre-carbonization and KOH activation are performed stepwise with defined parameters. Pre-carbonization causes preliminary pyrolysis and cross-linking of unstable components in the phenolic resin and petroleum asphalt, forming a stable carbon skeleton prototype and removing some volatiles, reducing the risk of carbon skeleton collapse during subsequent high-temperature activation. Subsequent KOH activation and selective etching to create pores on this stable framework, combined with the modification effect of nitrogen-containing functional groups generated by the pyrolysis of phenolic resin on the pore walls, synergistically constructed a multi-level pore system dominated by abundant micropores (>65%) and also containing a suitable amount of mesopores (e.g., 68.2% micropore ratio in Example 1). This pore structure provides a high specific surface area (>2000 m²). 2 ·g -1 This method not only stores a large amount of charge but also optimizes ion transport kinetics. The entire approach requires no complex solvent pretreatment or expensive template agents, uses petroleum asphalt as a cheap industrial byproduct as a raw material, and employs mild process conditions. Overall, it achieves high performance while significantly reducing costs and environmental impact, demonstrating promising industrialization potential.

[0017] This invention discloses a petroleum pitch-based composite porous carbon, which successfully prepares an optimized pore structure material with extremely high specific surface area and abundant micropores dominated by electrochemically active sites using the method of this invention. This solves the problem of difficult pore structure control, providing ample charge storage space and rapid ion diffusion channels for supercapacitors. At 1 A·g -1 The specific capacitance at current density is 325-358 F·g -1 This demonstrates that the petroleum pitch-based composite porous carbon possesses excellent charge storage capacity, thanks to the synergistic effect of its high specific surface area, optimized pore structure, and nitrogen-doped pseudocapacitance introduced by phenolic resin. The volume resistivity is below 1.0 Ω·cm, indicating that this invention successfully solves the technical problem of poor bonding between conductive components and the carbon matrix. Through the pre-uniform dispersion and embedding of CNTs and subsequent carbonization bonding, a highly efficient three-dimensional conductive network is constructed in the carbon matrix, significantly reducing electron transport resistance (far lower than the 2.12 Ω·cm of Comparative Example 1), thereby ensuring the performance and efficiency of the supercapacitor under high-power charge and discharge conditions.

[0018] This invention discloses an electrode for supercapacitors, which successfully transforms the petroleum pitch-based composite porous carbon prepared in this invention into an electrode assembly that can be directly applied. Due to the excellent conductivity of the active material itself, the final electrode inherits the high specific capacitance, low internal resistance, and structural stability of porous carbon materials, providing a core component for assembling high-performance supercapacitors.

[0019] This invention discloses a supercapacitor that, due to the use of high-performance supercapacitor electrodes, exhibits superior overall performance in terms of high energy density, high power density, and long cycle life. This meets the market's urgent demand for high-performance, low-cost energy storage devices. Detailed Implementation

[0020] 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.

[0021] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0022] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0023] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0024] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0025] In this invention, unless otherwise specified, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both 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 a shortened representation of these numerical combinations.

[0026] 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.

[0027] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0028] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0029] 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.

[0030] This invention provides a method for preparing petroleum pitch-based composite porous carbon, comprising the following steps: Step 1: Pre-treatment of petroleum asphalt by ball milling Block petroleum asphalt (softening point about 105℃) was ball-milled together with dispersant sodium dodecylbenzenesulfonate (SDBS) or polyvinylpyrrolidone (PVP) using a planetary ball mill (about 600 rpm for about 3.5 h), then passed through a 200-mesh sieve and dried at 40℃ and a vacuum of about -0.095 MPa for 2 h to obtain petroleum asphalt powder.

[0031] Step 2: Preparation of composite precursor Weigh the petroleum asphalt powder, phenolic resin, and multi-walled carbon nanotubes (CNTs) obtained in step 1 at a mass ratio of (2-4): (1-3): (0.05-0.1). Place them together in a mortar, add a small amount of anhydrous ethanol as a grinding aid, and grind manually or mechanically (about 150 rpm) until they are uniformly mixed and form a fine black powder. Transfer the mixed powder to a container and compact it under a pressure of 0.3-0.6 MPa for 5-15 s to obtain a dense composite precursor.

[0032] Step 3: Pre-carbonization The composite precursor was placed in a tube furnace, and argon gas was introduced as a protective atmosphere (flow rate approximately 70 mL / min). The temperature was increased to 350-370 °C at a rate of 4-6 °C / min. The mixture was held at the target temperature for 1-2 h to perform pre-carbonization to stabilize the carbon framework and remove volatiles. After the process, the mixture was allowed to cool naturally to room temperature (<50 °C) under argon protection to obtain the pre-carbonized product (black blocky solid).

[0033] Step 4: Carbonization and activation to create pores The pre-carbonized product was mixed with potassium hydroxide (KOH) powder at a mass ratio of (3-4):1 and ground until homogeneous. The mixture was placed in a tube furnace and protected with argon gas (flow rate approximately 70 mL / min). The mixture was heated to 750-800 °C at a heating rate of 4-6 °C / min. It was held at the target temperature for 1-2 h to carry out carbonization and activation reactions, etching to form a porous structure. After the process was completed, the mixture was cooled to room temperature under argon protection to obtain a black crude product.

[0034] Step 5: Purification The crude product was stirred in 1-3 M hydrochloric acid solution at room temperature for about 1-2 hours to remove residual KOH and metallic impurities. The acid-washed solid was filtered and repeatedly washed with a large amount of deionized water until the pH of the filtrate was neutral (about 6.5-7.5). Isopropanol was added to the water-washed filter cake, and the mixture was ultrasonically dispersed for about 10-15 minutes, followed by filtration again to remove residual small organic molecule impurities. The final filter cake was dried in a vacuum oven at 70-80℃ and a vacuum of about -0.095 MPa for 5-6 hours to obtain a black powdery petroleum pitch-based composite porous carbon.

[0035] The petroleum pitch-based composite porous carbon material prepared by this invention has a specific surface area of ​​2012-2310 m². 2 ·g -1 Total pore volume: 1.0-1.2 cm³ 3 ·g -1 Micropore (pore size <2 nm) ratio: >65%; at 1 A·g -1 Mass specific capacitance at current density: 325-358 F·g -1 Volume resistivity: <1.0 Ω·cm.

[0036] The petroleum pitch-based composite porous carbon prepared according to this invention is used as the active material. The active material, binder (such as polytetrafluoroethylene emulsion), and conductive agent (such as acetylene black) are mixed at a mass ratio of (7.5-8.5):(0.5-1):(0.5-2). An appropriate amount of ethanol is added to the mixture, and it is stirred into a slurry. This slurry is coated onto a current collector (such as nickel foam), and after drying, rolling, and cutting, electrode sheets are obtained.

[0037] The supercapacitor disclosed in this invention comprises the electrodes, electrolyte, separator, and casing described above. The positive electrode, separator, and negative electrode are stacked sequentially, the electrolyte is injected, and then the device is encapsulated to obtain a symmetrical supercapacitor device.

[0038] This invention uses inexpensive petroleum asphalt as the main carbon source and solves the technical problem of balancing conductive network construction, hierarchical pore structure control, and process economy and environmental protection through phenolic resin and CNT composite and staged pyrolysis. The final product has high specific surface area, high specific capacitance, low resistivity, and long cycle life, making it suitable for the manufacture of high-performance supercapacitors.

[0039] This invention provides a petroleum pitch-based composite porous carbon and a supercapacitor, which solves the problems of poor bonding between conductive components and carbon matrix, difficulty in controlling pore structure, and difficulty in balancing process economy and environmental protection in the preparation of traditional composite porous carbon. It achieves a synergistic improvement in material specific surface area, conductivity and electrochemical stability, and meets the requirements of supercapacitors for high-performance electrode materials. This invention uses petroleum asphalt as the main carbon source, phenolic resin as an auxiliary carbon and nitrogen source, multi-walled carbon nanotubes (CNTs) as a conductivity enhancer, and potassium hydroxide (KOH) as an activator to prepare petroleum asphalt-based composite porous carbon through an integrated process of "petroleum asphalt ball milling pretreatment - composite precursor grinding and compaction - pre-carbonization and impurity removal - carbonization activation and pore formation - acid washing, water washing, and alcohol washing purification". The petroleum asphalt-based composite porous carbon is used as an electrode active material, mixed with binder and conductive agent in proportion and coated on a current collector to assemble a supercapacitor. This invention achieves synergistic regulation of multiple components, overcoming the technical bottleneck of "component dispersion-structure regulation-performance synergy" in the preparation of traditional composite porous carbon. In traditional processes, conductive components tend to agglomerate, and the reactions of the carbon source and dopant components are not synchronized, often resulting in a difficulty in simultaneously achieving both conductivity and pore structure. In this invention, sodium dodecylbenzenesulfonate (or PVP) dispersant first optimizes the dispersibility of petroleum asphalt powder. CNTs are uniformly embedded in the carbon matrix during the composite precursor preparation stage. During pre-carbonization and carbonization activation, phenolic resin decomposes to provide nitrogen doping, and KOH etching constructs the porous structure. Multiple components act step-by-step according to the process sequence while also cooperating with each other, ensuring the synergistic achievement of high specific surface area and excellent conductivity from a technical mechanism perspective. For example, the specific surface area of ​​the sample in Example 1 reaches 2156 m². 2 ·g -1The volume resistivity is only 0.85 Ω·cm. The process design is highly compatible with the performance requirements of supercapacitor electrode materials. Traditional activation processes often use high-concentration strong alkali or high-temperature treatment, which easily leads to uneven pore size distribution or carbon skeleton collapse. In this invention, the heating rate of 5℃ / min, the pre-carbonization temperature of 360℃, and the activation temperature of 780℃ match the carbon source decomposition and pore structure formation rate, which can construct a multi-level porous structure with micropores as the main component and mesopores as the auxiliary component, which is conducive to the rapid transport of electrolyte ions. Moreover, the nitrogen doping provided by the phenolic resin is mainly pyridine nitrogen and pyrrole nitrogen, which can introduce additional pseudocapacitance and significantly improve the specific capacitance of the material. For example, the specific capacitance of the sample in Example 3 reaches 358 F / g, which is better than the existing porous carbon materials prepared with a single carbon source. The economic and environmental benefits are more advantageous based on the innovative process mechanism. Existing technologies often require high-temperature and high-pressure equipment or toxic solvents, which not only consumes a lot of energy and causes significant pollution, but also increases the cost of industrialization. In this invention, ball milling pretreatment requires no special conditions, and the ratio of activator KOH to pre-carbonized products is reasonable (3.5:1), avoiding excessive waste of reagents. The purification process only uses conventional reagents such as hydrochloric acid and isopropanol, without generating any toxic byproducts. Moreover, petroleum asphalt in the raw materials is an industrial byproduct with low cost. This reduces energy consumption and pollution from the source of the process, while improving the utilization rate of raw materials, making it easier to achieve large-scale production and application.

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments 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. The components of the embodiments of the present invention shown herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments 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.

[0041] Example 1 A method for preparing petroleum pitch-based composite porous carbon includes the following steps: Step 1: Take 50g of block petroleum asphalt with a softening point of 105℃ and add it to a planetary ball mill. At the same time, add 0.12g of sodium dodecylbenzenesulfonate as a dispersant. Set the ball mill speed to 600 rpm and continue ball milling for 3.5h. After ball milling, sieve it using a 200-mesh standard sieve, collect the sieved petroleum asphalt powder, and place it in a vacuum dryer (temperature 40℃, vacuum degree -0.095MPa) to dry for 2h for later use.

[0042] Step 2: Weigh 2.0g of phenolic resin, 4.0g of petroleum asphalt powder prepared in Step 1, and 0.4g of CNTs, and place them together in a tungsten carbide mortar (100mL volume); add 3 drops of anhydrous ethanol to the mortar as a grinding aid, and manually grind at a grinding rate of 150rpm for 15min until the mixture is a uniform and fine black powder, thus obtaining the composite precursor; transfer the precursor to a quartz ceramic boat, apply a pressure of 0.5MPa using a manual tablet press, and compact the precursor for 10s.

[0043] Step 3: Place the quartz ceramic boat containing the composite precursor into a horizontal tube furnace. After closing the furnace door, introduce argon gas (99.999% purity) as a protective atmosphere, set the argon gas flow rate to 70 mL / min, and continue to ventilate for 30 min to remove air from the furnace. Then turn on the heating device and heat to 360°C at a heating rate of 5°C / min. After reaching the target temperature, hold at that temperature for 1.2 h for pre-carbonization. After pre-carbonization, turn off the heating device, keep the argon gas flowing (flow rate 70 mL / min), and wait for the furnace temperature to cool naturally to below 50°C. Remove the ceramic boat and collect the pre-carbonized product (black blocky solid).

[0044] Step 4: Weigh 1.0g of the pre-carbonized product obtained in Step 3 and place it together with 3.5g of KOH powder in a tungsten carbide mortar. Grind manually for 20 minutes until the mixture is uniform, and transfer it to a new quartz ceramic boat. Place the ceramic boat back into a horizontal tube furnace, introduce argon gas (flow rate 70mL / min), and heat to 780℃ at a heating rate of 5℃ / min. Hold at this temperature for 1.5h for carbonization activation. After activation, stop heating and continue to introduce argon gas until the furnace temperature drops to room temperature to obtain a black crude product.

[0045] Step 5: Transfer the black crude product to a 200mL glass beaker and add 45mL of 2M hydrochloric acid solution; place the beaker on a magnetic stirrer (280rpm) and stir at room temperature for 1.8h to remove residual KOH and metal oxide impurities; then, transfer the acid-washed mixture to a Buchner funnel and filter it using a vacuum filtration device, and wash the filter cake repeatedly with deionized water until the pH of the filtrate stabilizes at 6.9-7.3; add 25mL of isopropanol to the water-washed filter cake, transfer it to an ultrasonic cleaner (300W) and ultrasonically disperse it for 12min, then filter it again to remove residual phenolic resin decomposition products.

[0046] Step 6: Transfer the alcohol-washed filter cake to a vacuum drying oven, set the temperature to 75℃ and the vacuum degree to -0.095MPa, and dry for 5.5h; after drying, take out the black powder sample and name it S1.

[0047] Example 2 The preparation process of Example 2 is exactly the same as that of Example 1, except that the amount of CNTs in step 2 is adjusted to 0.3g. The other steps and parameters are exactly the same as those of Example 1. The final product is denoted as S2.

[0048] Example 3 The preparation process of Example 3 is exactly the same as that of Example 1, except that the amount of phenolic resin in step 2 is changed to 3.0g and the amount of petroleum asphalt powder is 2.0g (phenolic resin: petroleum asphalt = 3:2). The other steps and parameters are exactly the same as those in Example 1. The final product is denoted as S3.

[0049] Example 4 The preparation process of Example 4 is exactly the same as that of Example 1, except that the activation temperature in step four is increased by 40°C, that is, the temperature is raised to 820°C, and the holding time is still 1.5h. The other steps and parameters are exactly the same as those in Example 1. The final product is denoted as S4.

[0050] Example 5 The preparation process of Example 5 is exactly the same as that of Example 1, except that the heat preservation time in step 3 is adjusted to 2.0h. The other steps and parameters are exactly the same as those of Example 1. The final product is denoted as S5.

[0051] Example 6 The preparation process of Example 6 is exactly the same as that of Example 1, except that in step one, the dispersant in the petroleum asphalt pretreatment is replaced with 0.12g of polyvinylpyrrolidone. The other steps and parameters are exactly the same as those in Example 1. The final product is denoted as S6.

[0052] Example 7 The preparation process differs from that of Example 1 in that, in step two: the mass ratio of petroleum asphalt powder, phenolic resin, and multi-walled carbon nanotubes is 4.0 g : 1.0 g : 0.05 g. During pressing, the pressure is adjusted to 0.3 MPa, and the holding time is adjusted to 5 s. The final product is designated as S7.

[0053] Example 8 The difference between this preparation process and that of Example 1 is that in step two, during the pressing process, the pressure is adjusted to 0.6 MPa and the holding time is adjusted to 15 s. The final product is denoted as S8.

[0054] Example 9 The preparation process differs from that in Example 1 in step four: the mass ratio of KOH to the pre-carbonized product is adjusted to 3:1. The final product is designated as S9.

[0055] Example 10 The difference from the preparation process in Example 1 is that in step four, the mass ratio of KOH to the pre-carbonized product is adjusted to 4:1 (i.e., 1.0 g of pre-carbonized product and 4.0 g of KOH). The final product is designated as S10.

[0056] Example 11 The preparation process differs from that in Example 1 in that step three: the pre-carbonization temperature is adjusted to 350°C. The final product is designated as S11.

[0057] Example 12 The preparation process differs from that in Example 1 in that step three: the pre-carbonization temperature is adjusted to 370°C. The final product is designated as S12.

[0058] Example 13 The preparation process differs from that of Example 1 in that, in step two, the amount of multi-walled carbon nanotubes is adjusted to 0.4g (the raw material ratio corresponds to 4:2:0.1, with asphalt powder accounting for 4 parts). In step four, the carbonization activation temperature is adjusted to 750℃. The final product is designated as S13.

[0059] Comparative Example 1 The preparation process of Example 1 was followed, except that CNTs were not added in step two (only 2.0g of phenolic resin + 4.0g of petroleum asphalt); the other steps and parameters were exactly the same as in Example 1, and the final product was denoted as D1.

[0060] Comparative Example 2 The preparation process of Example 1 was followed, except that the activation temperature in step four (carbon) was reduced by 80°C, i.e., the temperature was raised to 700°C, and the holding time remained at 1.5 h; the other steps and parameters were exactly the same as in Example 1, and the final product was denoted as D2.

[0061] Table 1. Comparison of the structure and electrical properties of petroleum pitch-based composite porous carbon prepared in the examples and comparative examples.

[0062] Table 1 compares the structure and electrical properties of the petroleum pitch-based composite porous carbon prepared in the examples and comparative examples. The data in the table show that the key components and raw material ratios have a core impact on the material properties. As conductivity and pore structure modifiers, the amount of CNTs directly affects performance: Example 1 (0.4g CNTs) has a specific surface area of ​​2156 m². 2 The specific capacitance is 342 F / g, which is 144 mF / g higher than that of Example 2 (0.3 g CNTs). 2 / g, 17F / g, and a low volume resistivity of 0.13Ω·cm; while Comparative Example 1 (without CNTs) showed a significant decline in all properties, with a specific surface area of ​​only 1685m². 2With a specific capacitance of 265 F / g, CNTs can construct conductive networks and optimize pore structure. Regarding the raw material ratio, Example 3 (phenolic resin: petroleum asphalt = 3:2) achieved a micropore ratio of 70.1% (the highest among the examples) due to the high carbon yield and ease of micropore formation of phenolic resin, corresponding to a specific capacitance of 358 F / g, confirming that micropores are the core carrier for double-layer energy storage in supercapacitors. The control of performance by process parameters is also clearly defined. Regarding the activation temperature, Example 4 (820℃) had a specific surface area of ​​2310 m². 2 / g, total pore volume 1.18cm³ 3 The specific capacitance was the highest, but the micropore ratio dropped to 65.8%, and the specific capacitance of 336 F / g was lower than that of Examples 1 and 3, due to micropore merging caused by high temperature; Comparative Example 2 (700 °C) was not sufficiently activated, with a specific surface area of ​​1820 m². 2 With a specific capacitance of 298 F / g, it was verified that around 780℃ is the optimal range for balancing pore structure and carbon skeleton stability. Example 5 (2.0 h), with an extended pre-carbonization time, achieved a cycle stability of 94.1% (highest), due to the reduced structural collapse caused by the thorough removal of volatile impurities. Example 6, with the dispersant replaced by PVP, showed performance similar to Example 1 (specific capacitance 332 F / g), demonstrating the flexibility in dispersant selection. Overall, a process range of 0.3-0.4 g CNTs, phenolic resin: petroleum asphalt = 3:2, activation at 780℃, and pre-carbonization for 1.2-2.0 h can be used to prepare high-performance porous carbon for supercapacitors.

[0063] In summary, this invention provides a petroleum asphalt-based composite porous carbon, its preparation method, and a supercapacitor. This invention, through a multi-component design of petroleum asphalt / phenolic resin / CNTs and a staged pyrolysis activation process, synergistically overcomes the technical bottlenecks of simultaneously achieving conductive network construction, precise control of hierarchical pore structure, and environmentally friendly and economical processes in composite porous carbon. It successfully prepares a supercapacitor with both high specific surface area (>2000 m²) and high pore size. 2 ·g -1 High specific capacitance (325-358 F·g) -1 Electrode materials with low volume resistivity (<1.0Ω·cm) and excellent cycle stability were used to construct high-performance supercapacitors, realizing the green and high-value transformation from inexpensive industrial by-products to high-end energy storage devices.

[0064] 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 petroleum pitch-based composite porous carbon, characterized in that, include: The blocky petroleum asphalt and dispersant were ball-milled together, then sieved and dried to obtain petroleum asphalt powder; the petroleum asphalt powder, phenolic resin and multi-walled carbon nanotubes were mixed and ground together, a grinding aid was added, and after grinding evenly, it was compacted to obtain a composite precursor; the composite precursor was pre-carbonized under a protective atmosphere, and after cooling, a pre-carbonized product was obtained. The pre-carbonized product was mixed evenly with potassium hydroxide and carbonized and activated under a protective atmosphere. After cooling, a crude product was obtained. The crude product was then subjected to acid washing, water washing, and alcohol washing in sequence, and dried to obtain petroleum pitch-based composite porous carbon.

2. The method for preparing petroleum pitch-based composite porous carbon according to claim 1, characterized in that, The dispersant is sodium dodecylbenzenesulfonate or polyvinylpyrrolidone.

3. The method for preparing petroleum pitch-based composite porous carbon according to claim 1, characterized in that, The mass ratio of the petroleum asphalt powder, phenolic resin and multi-walled carbon nanotubes is (2-4):(1-3):(0.05-0.1).

4. The method for preparing petroleum pitch-based composite porous carbon according to claim 1, characterized in that, The grinding aid is anhydrous ethanol; the compaction pressure is 0.3-0.6 MPa, and the holding time is 5-15 s.

5. The method for preparing petroleum pitch-based composite porous carbon according to claim 1, characterized in that, The protective atmosphere is argon; the mass ratio of potassium hydroxide to the pre-carbonized product is (3-4):

1.

6. The method for preparing petroleum pitch-based composite porous carbon according to claim 1, characterized in that, The pre-carbonization heating rate is 4-6℃ / min, the temperature is 350-370℃, and the holding time is 1-2h.

7. The method for preparing petroleum pitch-based composite porous carbon according to claim 1, characterized in that, The carbonization activation heating rate is 4-6℃ / min, the temperature is 750-800℃, and the holding time is 1-2h.

8. A petroleum pitch-based composite porous carbon, characterized in that, The petroleum asphalt-based composite porous carbon was prepared by the method described in any one of claims 1-7; the specific surface area of ​​the petroleum asphalt-based composite porous carbon was 2012-2310 m². 2 ·g -1 The total pore volume is 1.0-1.2 cm³. 3 ·g -1 The micropore ratio is greater than 65%, at 1 A·g -1 The specific capacitance at current density is 325-358 F·g -1 Its volume resistivity is less than 1.0 Ω·cm.

9. An electrode for a supercapacitor, characterized in that, The petroleum asphalt-based composite porous carbon of claim 8 is used as the active material; it is prepared by mixing the petroleum asphalt-based composite porous carbon with a binder and a conductive agent in a mass ratio of (7.5-8.5):(0.5-1):(0.5-2) and coating it onto a current collector.

10. A supercapacitor, characterized in that, It includes the electrodes for a supercapacitor as described in claim 9.

Images