High-capacity self-supporting porous carbon supercapacitor electrode materials, preparation and applications

Abstract

The application discloses a high surface capacity self-supporting porous carbon supercapacitor electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: taking diaminodiphenyl ether and pyromellitic dianhydride as monomers, and polymerizing in N,N-dimethylformamide in the presence of sodium carbonate to obtain a modified polyamide acid colloid; a nickel mesh is immersed in the colloid, vacuum soaking and hanging drying are performed, and a polyamide acid-nickel mesh three-dimensional composite material is formed; then, a programmed temperature thermal imidization treatment, high-temperature carbonization, alkali activation and acid pickling procedures are sequentially performed to obtain the electrode material; the application realizes the integration of the current collector, the conductive network and the active material, and exhibits high surface capacity, excellent rate performance and cycle stability; the process has strong controllability, the raw material cost is relatively low, and an advanced electrode material solution scheme is provided for the preparation of high-performance supercapacitors.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor electrode technology, specifically relating to high areal capacity self-supporting porous carbon supercapacitor electrode materials, their preparation and application. Background Technology

[0002] As a highly efficient and environmentally friendly energy storage device, the performance improvement of supercapacitors highly depends on the innovation of electrode materials. Traditional supercapacitor electrodes mostly adopt a process of coating powdered carbon materials (such as activated carbon) with binders (such as polytetrafluoroethylene and carboxymethyl cellulose) onto a metal current collector. However, this method has significant drawbacks: the insulating properties of the binder lead to increased internal resistance of the electrode and limited power performance; the binder and current collector account for 20%-30% of the total electrode mass, reducing the active material loading per unit volume / area; powdered electrodes are prone to particle shedding during cycling, leading to capacity decay; and multiple high-temperature carbonization / activation steps are required, resulting in high energy consumption and difficulty in controlling the pore structure.

[0003] In recent years, self-supporting porous carbon electrodes have become a research hotspot due to their advantages such as no need for binders, direct exposure of active sites, and strong structural stability. For example, the sol-gel method based on chitosan can prepare three-dimensional porous carbon, but uneven distribution of activators can easily lead to pore blockage, and two-step high-temperature treatment (pre-carbonization + activation) is required, making the process cumbersome. Biomass carbon sources (such as wood and nutshells) are inexpensive, but their pore structure is uncontrollable, making it difficult to achieve high areal capacity (>300 mF / cm²). To address these challenges, green and efficient one-step methods for preparing self-supporting porous carbon have become a breakthrough direction. For example, the molten salt method or template method can quickly construct hierarchical pore structures, but traditional processes rely on corrosive activators or high-energy-consuming carbonization equipment. Although nitrogen / sulfur co-doping can optimize the electronic structure of carbon materials and improve pseudocapacitive contribution, controlling the uniformity of doping remains a challenge. The application of flexible substrates (such as carbon cloth and carbon paper) provides new ideas for wearable devices, but the synergy between high mechanical strength and high conductivity still needs to be optimized. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the purpose of this invention is to provide high areal capacity self-supporting porous carbon supercapacitor electrode materials, their preparation and application, which have the characteristics of being binder-free, agent-free, having a three-dimensional conductive network, being self-supporting and integrated, having an adjustable structure and simple process.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: N,N-dimethylformamide solvent was added to a three-necked flask, diaminodiphenyl ether was added to the three-necked flask, and a certain amount of Na2CO3 was added. After it was fully dissolved, pyromellitic dianhydride was added in batches to carry out the polymerization reaction to obtain polyamic acid colloid. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material.

[0006] Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in a 40% KOH solution and dried at 80°C for 12 hours. The dried polyimide-derived carbon-nickel mesh three-dimensional composite material was then placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove heteroatoms. It was then washed with deionized water until neutral and dried to obtain the high areal capacity self-supporting porous carbon supercapacitor electrode material.

[0007] In step 1, the amount of N,N-dimethylformamide solvent is 35-40 mL, the amount of diaminodiphenyl ether is 2.8-3.2 g, the amount of Na2CO3 added is 0.06-0.35 g, and the addition of pyromellitic dianhydride in batches is specifically as follows: it is added in four batches, with the masses of the four batches being 0.5-1.5 g, 0.5-1.5 g, 0.5-1.5 g, and 0.1-0.5 g, respectively; the stirring time after each addition is 15-25 min, 15-25 min, 15-25 min, and 60-90 min, respectively.

[0008] In step 2, the vacuum level of the vacuum environment is -0.08 ~ -0.1 MPa; the temperature of the suspension drying is 80-120℃, and the time is 8-12 hours.

[0009] In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: the first stage: holding at 100℃-150℃ for 1-3 hours; the second stage: holding at 200℃-250℃ for 1-3 hours; and the third stage: holding at 300℃-350℃ for 1-3 hours.

[0010] In step 4, the high-temperature heat treatment is performed at a temperature of 500-700℃, a heating rate of 2℃ / min, and a holding time of 1-3 hours.

[0011] In step 5, the alkali is KOH; the activation heat treatment temperature is 700-900℃, the heating rate is 5℃ / min, and the holding time is 1-3 hours.

[0012] In step 6, the acid washing is performed by soaking in an HCl solution with a concentration of 0.5-2 mol / L for 1-3 hours.

[0013] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0014] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material.

[0015] Compared with the prior art, the high areal capacity self-supporting porous carbon supercapacitor electrode material and its preparation method provided by the present invention have the following significant advantages: The core of the method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode material of the present invention lies in constructing a three-dimensional porous structure through a nickel mesh template method and optimizing the material performance by combining gradient heat treatment process. This method breaks through the limitation of the dense structure of traditional carbon electrodes and significantly improves ion storage performance through pore control.

[0016] In terms of the preparation process, the vacuum drying stage employs a specific vacuum level of -0.08 to -0.1 MPa. By reducing the system pressure, the boiling point of the solvent decreases by approximately 30-50°C, effectively accelerating the evaporation rate of the polyamic acid solvent. The drying temperature window of 80-120°C and the duration of 8-12 hours ensure sufficient migration of solvent molecules (diffusion coefficient reaching 1.2 × 10⁻⁻⁻⁶). 6 (cm² / s), while avoiding the thermal decomposition of polyamic acid segments (activation energy threshold >200kJ / mol).

[0017] The innovation of the carbonization process lies in the gradient heating (2℃ / min to 600℃). Under this condition, the graphitization degree of the carbon precursor can be controlled within the range of 25-45%, forming a composite pore system dominated by micropores (<2nm) and secondary mesopores (2-50nm). Treatment at 600℃ improves the orientation degree of the carbon layer by 41%. The innovation of the KOH activation process lies in immersing the sample in KOH solution, drying for 12h, uniformly adhering to the sample surface, ensuring sufficient alkali activation, and using HCl solution (0.5-2mol / L) in the acid washing stage. The acid washing time of 1-3h was optimized by kinetic simulation, with a mass loss rate of <2%. Electrochemical tests show that the material has a specific capacity of 48F / g at a current density of 0.1A / g.

[0018] This invention achieves a perfect combination of high areal capacity and excellent rate performance: Through a clever design combining in-situ polymerization, thermal imidization, and alkali activation, a nitrogen-doped carbon material with abundant hierarchical pore structures (micropores and mesopores) and high specific surface area is successfully constructed on a nickel mesh framework. The abundant micropores greatly increase the charge storage sites, ensuring an ultra-high areal capacity (up to 5.35 F cm⁻²); simultaneously, the interconnected mesopores and macropores provide a "highway" for the rapid transport of electrolyte ions, ensuring that the electrode maintains excellent capacitance retention at high scan rates or high current densities, i.e., high rate performance, effectively solving the technical problem of poor rate performance in traditional high-capacity carbon materials.

[0019] This invention features a unique self-supporting electrode structure that simplifies device manufacturing and enhances overall performance: Active materials are grown in situ directly on a three-dimensional porous nickel mesh substrate, resulting in a self-supporting electrode. This structure eliminates the need for conductive agents, binders, and complex processes such as coating and rolling required in traditional electrode fabrication. This not only simplifies the production process and reduces costs but also fundamentally avoids the covering of active sites and the blockage of internal pores by inactive substances (binders and conductive agents). Simultaneously, the strong chemical bond between the nickel mesh framework and the carbon material ensures excellent interfacial conductivity and structural stability, reducing charge transport impedance and facilitating rapid charge-discharge and long cycle life.

[0020] The process is green and economical, and easy to scale up: This invention uses commercially available nickel mesh as a substrate, and the polyimide precursor can be synthesized from inexpensive diamine and dianhydride monomers, with widely available and low-cost raw materials. The entire preparation process requires no special or expensive equipment, the process flow is simple, and the conditions are highly controllable, making it very suitable for scale-up and industrial production, with significant economic benefits and application prospects.

[0021] Innovative Material Structure Design and Superior Overall Electrochemical Performance: The electrode material prepared in this invention is a three-dimensional integrated structure that combines a current collector (nickel mesh), a conductive network (graphitized carbon), and an active material (porous carbon). This unique structural design enables efficient transport of both electrons and ions within the material, resulting in significantly higher areal capacitance, energy density, and power density compared to traditional coated electrodes. Furthermore, the material maintains high capacitance retention even after thousands of charge-discharge cycles, demonstrating excellent cycle stability. Attached Figure Description

[0022] Figure 1 Flowchart for the preparation of polyimide-derived activated carbon-nickel mesh three-dimensional composite materials.

[0023] Figure 2 This is a multi-scan rate CV curve of the sample in Example 2 of the present invention.

[0024] Figure 3 This is a constant current charge-discharge curve of the sample in Example 2 of the present invention.

[0025] Figure 4 This is a low-resolution SEM image of the sample from Example 1 of this invention.

[0026] Figure 5 This is a high-resolution SEM image of the sample from Example 1 of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Example 1

[0028] See Figure 1 A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3 g of diaminodiphenyl ether to the flask, and then add 0.0634 g of Na2CO3. After dissolving completely, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction to obtain polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 1 g, 1 g, 1 g, and 0.278 g, respectively. The stirring time after each addition is 20 min, 20 min, 20 min, and 60 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.08 MPa; the temperature of the suspension drying is 80℃ and the time is 12 hours.

[0029] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 100℃ for 1 hour; second stage: holding at 200℃ for 1 hour; third stage: holding at 300℃ for 1 hour; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 800°C at 5°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking in a 0.5 mol / L HCl solution for 1 hour.

[0030] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0031] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material.

[0032] Nitrogen adsorption-desorption tests (77 K) showed that the porous carbon obtained in Example 1 had a specific surface area of ​​1400 m² / g, a total pore volume of 0.5 cm³ / g, and a micropore volume of 0.3 cm³ / g, exhibiting a hierarchical pore structure of micropores-mesopores-macropores. Electrochemical tests (1 MTEATFB / organic system) showed a specific capacitance of 45 F / g at a current density of 0.1 A / g. Example 2

[0033] A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 35 mL of N,N-dimethylformamide solvent to a three-necked flask, add 2.8 g of diaminodiphenyl ether to the flask, then add 0.1942 g of Na2CO3. After dissolving completely, add 3 g of pyromellitic dianhydride in batches to carry out the polymerization reaction to obtain polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 1.4 g, 1 g, 0.5 g, and 0.1 g, respectively. The stirring time after each addition is 15 min, 20 min, 25 min, and 75 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.09 MPa; the temperature of the suspension drying is 100℃ and the time is 8 hours. Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 125℃ for 1 hour; second stage: holding at 225℃ for 1 hour; third stage: holding at 325℃ for 1 hour; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 3°C / min and held for 1 hour, then heated to 800°C at 3°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking the sample in a 1 mol / L HCl solution for 2 hours.

[0034] The specific surface area of ​​the obtained porous carbon decreased slightly (1280 m² / g), but the degree of graphitization increased (ID / IG: 0.7), making it suitable for supercapacitor electrode materials. Example 3

[0035] A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 40 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3.2 g of diaminodiphenyl ether to the flask, then add 0.3304 g of Na2CO3. After fully dissolving, add 3.5 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition, and the masses of the four additions are 1.5 g, 1.3 g, 0.5 g, and 0.2 g, respectively; the stirring time after each addition is 15 min, 25 min, 25 min, and 80 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.09 MPa; the temperature of the suspension drying is 90℃ and the time is 10 hours. Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 125℃ for 2 hours; second stage: holding at 225℃ for 2 hours; third stage: holding at 325℃ for 2 hours.

[0036] Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkali activation furnace, heated to 600°C at 2°C / min and held for 1 hour, then heated to 800°C at 2°C / min and held for 2 hours. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking the sample in a 2 mol / L HCl solution for 1 hour. Example 4

[0037] See Figure 1A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3 g of diaminodiphenyl ether to the flask, then add 0.0634 g of Na2CO3. After fully dissolving, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 1.5 g, 1 g, 0.6 g, and 0.178 g, respectively. The stirring time after each addition is 20 min, 15 min, 15 min, and 60 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.1 MPa; the temperature of the suspension drying is 120℃ and the time is 8 hours.

[0038] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 150℃ for 3 hours; second stage: holding at 250℃ for 3 hours; third stage: holding at 350℃ for 1 hour.

[0039] Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 500°C, a heating rate of 5°C / min, and a holding time of 3 hours. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkali activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 700°C at 5°C / min and held for 3 hours. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the pickling is performed by soaking in a 0.5 mol / L HCl solution for 2 hours.

[0040] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0041] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material. Example 5

[0042] See Figure 1 A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3 g of diaminodiphenyl ether to the flask, then add 0.0634 g of Na2CO3. After fully dissolving, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 1 g, 1.2 g, 0.978 g, and 0.1 g, respectively. The stirring time after each addition is 15 min, 15 min, 15 min, and 60 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.1 MPa; the temperature of the suspension drying is 100℃ and the time is 10 hours.

[0043] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 150℃ for 1 hour; second stage: holding at 250℃ for 2 hours; third stage: holding at 300℃ for 3 hours.

[0044] Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 700°C, a heating rate of 4°C / min, and a holding time of 2 hours. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 900°C at 5°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the pickling is performed by soaking in a 0.5 mol / L HCl solution for 3 hours.

[0045] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0046] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material. Example 6

[0047] See Figure 1 A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3 g of diaminodiphenyl ether to the flask, then add 0.05 g of Na2CO3. After fully dissolving, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 0.5 g, 1.5 g, 0.5 g, and 0.5 g, respectively. The stirring time after each addition is 25 min, 20 min, 20 min, and 90 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.08 MPa; the temperature of the suspension drying is 80℃ and the time is 12 hours.

[0048] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 100℃ for 1 hour; second stage: holding at 200℃ for 1 hour; third stage: holding at 300℃ for 1 hour; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 800°C at 5°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking in a 0.5 mol / L HCl solution for 1 hour.

[0049] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0050] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material.

[0051] Nitrogen adsorption-desorption tests (77 K) showed that the porous carbon obtained in Example 1 had a specific surface area of ​​1400 m² / g, a total pore volume of 0.5 cm³ / g, and a micropore volume of 0.3 cm³ / g, exhibiting a hierarchical pore structure of micropores-mesopores-macropores. Electrochemical tests (1 MTEATFB / organic system) showed a specific capacitance of 45 F / g at a current density of 0.1 A / g. Example 7

[0052] See Figure 1 A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3.1 g of diaminodiphenyl ether to the flask, then add 0.35 g of Na₂CO₃. After fully dissolving, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 0.5 g, 1.5 g, 1 g, and 0.1 g, respectively. The stirring time after each addition is 25 min, 20 min, 20 min, and 60 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.08 MPa; the temperature of the suspension drying is 80℃ and the time is 12 hours.

[0053] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 100℃ for 1 hour; second stage: holding at 200℃ for 1 hour; third stage: holding at 300℃ for 1 hour; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 800°C at 5°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking in a 0.5 mol / L HCl solution for 1 hour.

[0054] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0055] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material. Example 8

[0056] See Figure 1 A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3.2 g of diaminodiphenyl ether to the flask, then add 0.35 g of Na₂CO₃. After fully dissolving, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 0.5 g, 1 g, 1.5 g, and 0.2 g, respectively. The stirring time after each addition is 25 min, 20 min, 20 min, and 60 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.08 MPa; the temperature of the suspension drying is 80℃ and the time is 12 hours.

[0057] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 100℃ for 1 hour; second stage: holding at 200℃ for 1 hour; third stage: holding at 300℃ for 1 hour; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 800°C at 5°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking in a 0.5 mol / L HCl solution for 1 hour.

[0058] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0059] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material. Example 9

[0060] See Figure 1 A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode materials includes the following steps: Step 1, Preparation of modified polyamic acid: Add 37.53 mL of N,N-dimethylformamide solvent to a three-necked flask, add 3.2 g of diaminodiphenyl ether to the flask, then add 0.35 g of Na₂CO₃. After fully dissolving, add 3.278 g of pyromellitic dianhydride in batches to carry out the polymerization reaction, obtaining polyamic acid colloid. In step 1, the batch addition of pyromellitic dianhydride is specifically as follows: it is added in four batches, with an interval of 20 min between each addition. The masses of the four additions are 1 g, 0.5 g, 1.5 g, and 0.2 g, respectively. The stirring time after each addition is 25 min, 20 min, 20 min, and 60 min, respectively. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry. It was hung in a beaker and placed in a vacuum drying oven to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. In step 2, the vacuum level of the vacuum environment is -0.08 MPa; the temperature of the suspension drying is 80℃ and the time is 12 hours.

[0061] Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment (thermal imidization treatment) to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material; In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: first stage: holding at 100℃ for 1 hour; second stage: holding at 200℃ for 1 hour; third stage: holding at 300℃ for 1 hour; Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. In step 4, the high-temperature heat treatment is performed at a temperature of 600°C, a heating rate of 2°C / min, and a holding time of 1 hour. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. In step 5, the KOH solution has a mass fraction of 40%; the nickel mesh with polyimide-derived activated carbon prepared in step 4 is placed in an alkaline activation furnace, heated to 600°C at 5°C / min and held for 1 hour, then heated to 800°C at 5°C / min and held for 1 hour. After natural cooling, the activated nickel mesh with polyimide-derived activated carbon is obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove impurities. It was then washed with deionized water until neutral and dried to obtain the high surface capacity self-supporting porous carbon supercapacitor electrode material. In step 6, the acid washing involves soaking in a 0.5 mol / L HCl solution for 1 hour.

[0062] A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the aforementioned method.

[0063] A supercapacitor comprising the aforementioned high areal capacity self-supporting porous carbon supercapacitor electrode material.

[0064] Comparative Example 1 No filler Na2CO is added during the synthesis of polyamic acid. 3， The specific steps for preparing pure polyamic acid comparative samples are as follows: Step 1: Add 37.53 mL of N,N-dimethylformamide to a three-necked flask. Add 3 g of diaminodiphenyl ether to the three-necked flask and dissolve it completely. Then add 3.278 g of pyromellitic dianhydride in four portions, with an interval of 20 min between each addition. Stir thoroughly for 60-90 min after the last addition. Step 2: Immerse the nickel mesh in the polyamic acid (PAA) prepared in Step 1, and vacuum for 5 hours. Then, take out the nickel mesh with polyamic acid and place it in a vacuum drying oven to dry at 80°C for 12 hours. Step 3, thermal imidization: Place the dried sample in a precision high-temperature oven and heat in stages (to avoid bubble formation): Stage 1: 100℃, hold for 1 hour; Stage 2: 150℃, hold for 1 hour; Stage 3: 200℃, hold for 1 hour; Stage 4: 250℃, hold for 1 hour; Stage 5: 300℃, hold for 1 hour; Stage 6: 350℃, hold for 1 hour (complete cyclization, imide ring formation); After natural cooling, a nickel mesh coated with polyimide is obtained. Step 4, high-temperature carbonization: The nickel mesh with polyimide coating prepared in step 3 is placed in a tube furnace and heated to 600℃ at 2℃ / min, held for 1 hour, and then naturally cooled to obtain a nickel mesh with polyimide-derived activated carbon. Step 5, KOH activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 is immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material is placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material is obtained. Step 6, acid washing: The activated nickel mesh with polyimide-derived activated carbon prepared in step 5 is immersed in 0.5 mol / L dilute hydrochloric acid solution for 1 hour (to remove impurities), and then washed with deionized water until neutral.

[0065] See Figure 2The figure shows the constant current charge-discharge curve of the sample in Example 2 of this invention. At a current of 0.1 A / g, the calculated specific capacitance is as high as 48 F / g. The curve exhibits a typical symmetrical isosceles triangle shape with no significant voltage drop or charge-discharge plateau. This is a characteristic behavior of double-layer capacitor electrode materials, indicating that charge storage in the electrode material mainly relies on the rapid adsorption and desorption of electrolyte ions at the electrode / electrolyte interface, with low contribution from Faraday pseudocapacitance and efficient and reversible charge transport and ion migration. At a low current density of 0.1 A / g, the specific capacitance reaches 48 F / g according to the formula C=I×Δt / (m×ΔV). Even with increased current density, the charge-discharge curve maintains good symmetry, with only a slight decrease in discharge time as current density increases, demonstrating excellent rate performance and charge-discharge reversibility of the material. Compared with existing technologies, the specific capacitance of traditional coated porous carbon electrodes is mostly between 20 and 35 F / g under the same test conditions. The curve is prone to distortion and capacitance decay when the current density is increased. Biomass-based self-supporting carbon electrodes, due to their uncontrollable pore structure, typically have a specific capacitance below 30 F / g at 0.1 A / g. The material of this invention achieves a significant breakthrough in specific capacitance performance because its multi-level pores provide efficient channels for ion transport, and its self-supporting integrated structure reduces charge transport impedance.

[0066] See Figure 3 , Figure 3 The CV curves of the sample in Example 2 of this invention, with their near-rectangular shape, indicate that double-layer behavior is dominant and charge storage exhibits high electrochemical reversibility. As the scan rate increases, the rectangular outline of the CV curve shows no significant distortion, only a slight increase in the enclosed area, and no obvious polarization, indicating that electrolyte ions can migrate rapidly within the pores of the electrode material. This demonstrates that the electrode material prepared by this invention has excellent ion transport rate and rate adaptability. In the prior art, self-supporting carbon electrodes prepared by the sol-gel method are prone to distorted CV curves and loss of rectangular characteristics after increasing the scan rate due to pore blockage; nitrogen-doped carbon electrodes, due to the high contribution of pseudocapacitance, exhibit significant redox peaks in their CV curves and severe polarization at high scan rates. The CV curve characteristics of the material of this invention are superior to those of traditional materials, thanks to the microporous-mesoporous hierarchical pore structure constructed by gradient carbonization and uniform alkali activation processes, as well as the good interfacial conductivity brought by the self-supporting structure.

[0067] See Figure 4This is a low-magnification SEM image of the sample from Example 1 of this invention. The observation scale ranges from macroscopic to mesoscopic, clearly showing that the material retains the three-dimensional mesh framework structure of the nickel mesh substrate. The original pores of the nickel mesh are not completely filled by the activated carbon material, forming an interconnected, uniformly distributed macroporous structure (pore size > 50 nm), with a complete framework connection. A thin film of carbon material is uniformly coated on the surface of the nickel mesh metal framework, and the carbon material is tightly bonded to the nickel mesh substrate, achieving an integrated combination of the current collector (nickel mesh) and the active material (porous carbon). The three-dimensional mesh macroporous structure provides ample channels for rapid electrolyte penetration, allowing the electrolyte to fully contact the internal active sites, solving the problem of low utilization rate of active materials in traditional coated electrodes. Overall, the three-dimensional porous structure of the material under low-magnification SEM is regular, without agglomeration or dense clumps, proving that the in-situ polymerization and vacuum immersion process of this invention can achieve uniform loading of carbon material on the nickel mesh substrate, laying the structural foundation for the material's high areal capacity and excellent cycle stability.

[0068] See Figure 5 , Figure 5 This is a high-resolution SEM image of the sample from Example 1 of this invention. At the microscale, the carbon material coating the nickel mesh skeleton exhibits a rough, porous morphology with abundant micropores and mesopores, forming a typical hierarchical pore structure. The micropores and mesopores are interconnected, uniformly distributed, and unblocked. This microporous morphology is formed by a combination of gradient thermal imidization, high-temperature carbonization, and KOH alkaline activation processes: KOH etches out a large number of micropores and mesopores, while gradient heating avoids excessive etching and collapse of the pores, ensuring the integrity of the pore structure. Abundant micropores increase the specific surface area of ​​the electrode material, providing numerous active sites, which is the core reason for the material's high areal capacity; interconnected mesopores accelerate ion migration, improving the material's rate performance. No obvious amorphous carbon aggregates were observed under high-magnification SEM, demonstrating excellent graphitization and pore structure control of the carbon material, forming a good structure-performance correspondence with the electrochemical test results.

Claims

1. A method for preparing high-area-capacity self-supporting porous carbon supercapacitor electrode material, characterized in that, Includes the following steps: Step 1, Preparation of modified polyamic acid: N,N-dimethylformamide solvent was added to a three-necked flask, diaminodiphenyl ether was added to the three-necked flask, and a certain amount of Na2CO3 was added. After it was fully dissolved, pyromellitic dianhydride was added in batches to carry out the polymerization reaction to obtain polyamic acid colloid. Step 2, Soaking and Drying The nickel mesh was immersed in the polyamic acid colloid prepared in step 1 under vacuum. Then the nickel mesh with polyamic acid attached was taken out and hung to dry, thus obtaining a three-dimensional polyamic acid-nickel mesh composite material. Step 3, thermal imidization treatment: The polyamic acid-nickel mesh three-dimensional composite material described in step 2 is subjected to programmed temperature rise heat treatment to cyclize polyamic acid into polyimide, thereby obtaining polyimide-nickel mesh three-dimensional composite material. Step 4, high-temperature carbonization: The polyimide-nickel mesh three-dimensional composite material prepared in step 3 was placed in a tube furnace and heat-treated under an inert atmosphere to obtain a polyimide-derived carbon-nickel mesh three-dimensional composite material. Step 5, Alkali activation: The polyimide-derived carbon-nickel mesh three-dimensional composite material prepared in step 4 was immersed in KOH solution and dried. Then, the dried polyimide-derived carbon-nickel mesh three-dimensional composite material was placed in an alkali activation furnace and heat-treated under an inert atmosphere. After natural cooling, the polyimide-derived activated carbon-nickel mesh three-dimensional composite material was obtained. Step 6, pickling: The polyimide-derived activated carbon-nickel mesh three-dimensional composite material prepared in step 5 was immersed in HCl solution and acid-washed to remove heteroatoms. It was then washed with deionized water until neutral and dried to obtain the high areal capacity self-supporting porous carbon supercapacitor electrode material.

2. The method for preparing the high areal capacity self-supporting porous carbon supercapacitor electrode material according to claim 1, characterized in that, In step 1, the amount of N,N-dimethylformamide solvent is 35-40 mL, the amount of diaminodiphenyl ether is 2.8 g-3.2 g, the amount of Na2CO3 added is 0.05-0.35 g, and the addition of pyromellitic dianhydride in batches of 3 g-3.5 g is specifically as follows: it is added in four batches, with the masses of the four batches being 0.5-1.5 g, 0.5-1.5 g, 0.5-1.5 g, and 0.1-0.5 g, respectively; the stirring time after each addition is 15-25 min, 15-25 min, 15-25 min, and 60-90 min, respectively.

3. The method for preparing the high areal capacity self-supporting porous carbon supercapacitor electrode material according to claim 1, characterized in that, In step 2, the vacuum level of the vacuum environment is -0.08 ~ -0.1 MPa; the temperature of the suspension drying is 80-120℃, and the time is 8-12 hours.

4. The method for preparing the high areal capacity self-supporting porous carbon supercapacitor electrode material according to claim 1, characterized in that, In step 3, the programmed temperature rise heat treatment is a gradient temperature rise, including: the first stage: holding at 100℃-150℃ for 1-3 hours; the second stage: holding at 200℃-250℃ for 1-3 hours; and the third stage: holding at 300℃-350℃ for 1-3 hours.

5. The method for preparing the high areal capacity self-supporting porous carbon supercapacitor electrode material according to claim 1, characterized in that, In step 4, the high-temperature heat treatment is performed at a temperature of 500-700℃, a heating rate of 2-5℃ / min, and a holding time of 1-3 hours.

6. The method for preparing the high areal capacity self-supporting porous carbon supercapacitor electrode material according to claim 1, characterized in that, In step 5, the KOH solution has a mass fraction of 40%; the activation heat treatment temperature is 700-900℃, the heating rate is 2-5℃ / min, and the holding time is 1-3 hours.

7. The method for preparing the high areal capacity self-supporting porous carbon supercapacitor electrode material according to claim 1, characterized in that, In step 6, the acid washing involves soaking in an HCl solution with a concentration of 0.5-2 mol / L for 1-3 hours.

8. A high-area-capacity self-supporting porous carbon supercapacitor electrode material prepared by the preparation method according to any one of claims 1-7.

9. A supercapacitor, characterized in that, It includes the high areal capacity self-supporting porous carbon supercapacitor electrode material as described in claim 8.

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