A hierarchical structured capacitor electrode material and a method for preparing the same

Abstract

This invention discloses a hierarchical capacitor electrode material and its preparation method, relating to the field of electrode materials. In preparing the hierarchical capacitor electrode material, this invention involves microwave carbonization of dried and pulverized buckwheat hulls, polyphosphoric acid, and sulfuric acid to obtain phosphorus-doped porous carbon; reacting the phosphorus-doped porous carbon with 2,6-diaminoanthraquinone and trialdehyde-resorcinol to obtain composite porous carbon; and reacting the composite porous carbon with sodium 1H-pyrrole-3-sulfonate and pyrrole to obtain the hierarchical capacitor electrode material. The hierarchical capacitor electrode material prepared by this invention exhibits excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of electrode materials, specifically to a layered capacitor electrode material and its preparation method. Background Technology

[0002] Against the backdrop of rapid economic development, the increasing scarcity of non-renewable fossil fuels such as oil, natural gas, and coal, coupled with environmental problems caused by greenhouse gas emissions, has led to a growing demand for pollution-free, high-energy-density, renewable energy sources and related energy storage and conversion technologies and equipment. The development and utilization of green and clean energy sources such as solar, wind, tidal, and nuclear energy are expanding. However, these energy sources are susceptible to seasonal and regional variations, and the continuity and stability of their use cannot be guaranteed. Therefore, developing and using high-performance, sustainable energy conversion and storage devices in conjunction with these sources can effectively solve the transportation problems of these clean energy sources. Since the 20th century, various novel energy storage devices, such as fuel cells, lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, solar cells, and supercapacitors, have been extensively researched.

[0003] Supercapacitors are mainly classified into three types according to their energy storage mechanisms: (1) electric double-layer capacitors: energy storage is achieved by accumulating charge at the interface of electrode materials; (2) pseudocapacitors: energy storage is achieved through a fast and reversible Faraday reaction process; and (3) hybrid capacitors: energy storage is achieved by utilizing both of the above mechanisms simultaneously. A capacitor consists of three parts: electrode materials, electrolyte, and separator. Among them, the electrode materials are the key part, directly affecting the specific capacitance, energy density, power density, and cycle stability of the device.

[0004] Electrode materials are mainly classified into three categories: carbon-based materials, transition metal oxides, and conductive polymers. High-specific-surface-area carbon-based materials often achieve rapid ion adsorption and desorption through the electric double-layer mechanism, exhibiting excellent cycle life and high power characteristics. Transition metal oxides / hydroxides rely on pseudocapacitive reactions to achieve higher specific capacitance and energy density within a smaller volume, but improvements in conductivity and structural stability are needed. Conductive polymers can achieve high specific capacitance through reversible redox reactions; however, their cycle life is easily affected by volume expansion / contraction. Therefore, this invention provides a high-specific-capacitance hierarchical capacitor electrode material and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a layered capacitor electrode material and its preparation method to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A hierarchical capacitor electrode material is obtained by reacting composite porous carbon, sodium 1H-pyrrole-3-sulfonate, and pyrrole.

[0007] As an optimization, the composite porous carbon is obtained by reacting phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, and trialdehyde phloroglucinol.

[0008] As an optimization, the phosphorus-doped porous carbon is obtained by microwave carbonization of dried and pulverized buckwheat hulls, polyphosphoric acid, and sulfuric acid.

[0009] As an optimization, the dried and pulverized buckwheat hulls are sourced from Taizhen Mineral Products Processing Plant in Lingshou County.

[0010] A hierarchical capacitor electrode material and its preparation method, comprising the following preparation steps: (1) Dry and crushed buckwheat hulls, polyphosphoric acid and sulfuric acid solution with a mass fraction of 98%~99% are mixed at a mass ratio of 1:(3.3~3.4):(0.6~0.7), and reacted in a microwave at 20~30℃ and 700~900W for 1~3 min. The mixture is washed 3~5 times with deionized water and anhydrous ethanol respectively, and dried at 55~65℃ for 11~13 h to obtain phosphorus-doped porous carbon. (2) Phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, trialdehyde phloroglucinol and N,N-dimethylformamide were mixed at a mass ratio of 1:(0.9~1.1):(2.3~2.5):(300~500), sonicated for 10~20s, and acetic acid solution of 37~38 times the mass of phosphorus-doped porous carbon (5~7mol / L) was added. The mixture was degassed by freezing and thawing 2~4 times in a nitrogen atmosphere, heated to 85~95℃ and reacted for 47~49h. After cooling, the mixture was filtered, washed 3~5 times with anhydrous ethanol, and dried at 75~85℃ for 11~13h to obtain composite porous carbon. (3) The composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.1~0.3mol / L hydrochloric acid solution and 0.3~0.4mol / L pyrrole ethanol solution are mixed at a mass ratio of 1:(0.7~0.9):(62~63):(24~26). The mixture is stirred at 20~30℃ and 300~400rpm for 35~45min. 15~25 times the mass of nanoporous carbon ammonium persulfate solution of 0.9~1.1mol / L is added uniformly within 30~40min. After standing at -2~0℃ for 11~13h, the mixture is filtered and washed 3~5 times with deionized water and anhydrous ethanol respectively. The mixture is dried at 55~65℃ for 11~13h to obtain the layered structure capacitor electrode material.

[0011] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing the layered capacitor electrode material, this invention involves microwave carbonization of dried and pulverized buckwheat hulls, polyphosphoric acid, and sulfuric acid to obtain phosphorus-doped porous carbon; reaction of the phosphorus-doped porous carbon with 2,6-diaminoanthraquinone and trialdehyde-resorcinol to obtain composite porous carbon; and reaction of the composite porous carbon with sodium 1H-pyrrole-3-sulfonate and pyrrole to obtain the layered capacitor electrode material.

[0012] First, dried and pulverized buckwheat hulls, polyphosphoric acid, and sulfuric acid are microwave-carbonized to obtain phosphorus-doped porous carbon. Utilizing the dehydrating ability of concentrated sulfuric acid, the carbonization temperature of the buckwheat hulls is lowered, reacting with the hot pyrolytic carbon to generate large amounts of CO2, SO2, and H2O gases, further etching the carbon skeleton to create more pores. Simultaneously, concentrated sulfuric acid, a strong inorganic acid with excellent microwave absorption, can assist the polyphosphoric acid heating reaction system, introducing phosphorus atoms into the carbon skeleton, improving the wettability and conductivity of the electrode material, accelerating ion and electron transport, and increasing defect sites, thus endowing the porous carbon with additional pseudocapacitive effects and improving the specific capacity of the electrode material.

[0013] Secondly, a composite porous carbon was obtained by reacting phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, and trialdehyde phloroglucinol. A covalent organic framework containing anthraquinone structure was prepared on the surface of the porous carbon using a solvothermal in-situ composite method to form physical spacers and enhance the dispersibility of the porous carbon. The regular channels of the covalent organic framework can cooperate with the porous carbon for ion transport, and the conjugated structure of the covalent organic framework can assist in electron conduction. At the same time, the quinone group (C=O) in the anthraquinone molecular structure can be reversibly oxidized and reduced to provide additional pseudocapacitance and further improve the specific capacity of the electrode material.

[0014] Finally, composite porous carbon, sodium 1H-pyrrole-3-sulfonate, and pyrrole were reacted to obtain a hierarchical capacitor electrode material. Using ammonium persulfate as an oxidant and doped with hydrochloric acid, pyrrole and sodium 1H-pyrrole-3-sulfonate monomers were polymerized on the surface of porous carbon via chemical oxidation to form conductive polypyrrole long chains with sulfonic acid groups in the side chains, which enhanced electronic conductivity. The strong hydrophilicity of the sulfonic acid groups in the side chains can promote the wetting of the electrode material by the electrolyte, enhance the rapid transport of electrolyte ions inside the electrode, and improve the ion conductivity of the electrode material. At the same time, the steric hindrance of the side chains is used to prevent polymerization from blocking the pore structure and maintain ion transport efficiency. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] The raw materials used in the following examples and comparative examples are all commercially available: The dried and pulverized buckwheat hulls came from Taizhen Mineral Products Processing Plant in Lingshou County.

[0017] Example 1:

[0018] A hierarchical capacitor electrode material and its preparation method thereof, the hierarchical capacitor electrode material and its preparation method comprising the following preparation steps: (1) The dried and crushed buckwheat hulls, polyphosphoric acid and sulfuric acid solution with a mass fraction of 98% were mixed at a mass ratio of 1:3.3:0.65, and reacted in a microwave at 20℃ and 700W for 3 min. The mixture was washed three times with deionized water and anhydrous ethanol respectively, and dried at 55℃ for 13 h to obtain phosphorus-doped porous carbon. (2) Phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, trialdehyde phloroglucinol and N,N-dimethylformamide were mixed at a mass ratio of 1:0.9:2.3:300 and sonicated for 20s. Then, acetic acid solution of 37 times the mass of phosphorus-doped porous carbon (5 mol / L) was added. The mixture was degassed twice by freezing and thawing under a nitrogen atmosphere. The mixture was heated to 85℃ and reacted for 49h. After cooling, the mixture was filtered, washed three times with anhydrous ethanol, and dried at 75℃ for 13h to obtain composite porous carbon. (3) The composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.1 mol / L hydrochloric acid solution and 0.3 mol / L pyrrole ethanol solution were mixed at a mass ratio of 1:0.8:62:24 and stirred at 20℃ and 300 rpm for 45 min. Then, 0.9 mol / L ammonium persulfate solution, which was 15 times the mass of the nanoporous carbon, was added at a uniform rate within 30 min. After standing at -2℃ for 13 h, the mixture was filtered, washed three times with deionized water and anhydrous ethanol, and dried at 55℃ for 13 h to obtain the layered structure capacitor electrode material.

[0019] Example 2:

[0020] A hierarchical capacitor electrode material and its preparation method thereof, the hierarchical capacitor electrode material and its preparation method comprising the following preparation steps: (1) The dried and crushed buckwheat hulls, polyphosphoric acid and sulfuric acid solution with a mass fraction of 98.5% were mixed at a mass ratio of 1:3.35:0.65, reacted at 25℃ and 800W microwave for 2 min, washed 4 times with deionized water and anhydrous ethanol respectively, and dried at 60℃ for 12 h to obtain phosphorus-doped porous carbon. (2) Phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, trialdehyde phloroglucinol and N,N-dimethylformamide were mixed in a mass ratio of 1:1:2.4:400 and sonicated for 15s. Then, acetic acid solution of 6 mol / L with a mass of 37.5 times that of phosphorus-doped porous carbon was added. The mixture was degassed three times by freezing and thawing in a nitrogen atmosphere. The mixture was heated to 90℃ and reacted for 48h. After cooling, the mixture was filtered, washed four times with anhydrous ethanol, and dried at 80℃ for 12h to obtain composite porous carbon. (3) The composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.2 mol / L hydrochloric acid solution and 0.35 mol / L pyrrole ethanol solution were mixed at a mass ratio of 1:0.8:62.5:25 and stirred at 25℃ and 350 rpm for 40 min. Then, 20 times the mass of the nanoporous carbon and 1 mol / L ammonium persulfate solution were added uniformly within 35 min. After standing at -1℃ for 12 h, the mixture was filtered and washed 4 times with deionized water and anhydrous ethanol, respectively. The mixture was then dried at 60℃ for 12 h to obtain the layered structure capacitor electrode material.

[0021] Example 3:

[0022] A hierarchical capacitor electrode material and its preparation method thereof, the hierarchical capacitor electrode material and its preparation method comprising the following preparation steps: (1) The dried and crushed buckwheat hulls, polyphosphoric acid and sulfuric acid solution with a mass fraction of 99% were mixed at a mass ratio of 1:3.4:0.65, and reacted in a microwave at 30℃ and 900W for 1 min. The mixture was washed 5 times with deionized water and anhydrous ethanol respectively, and dried at 65℃ for 11 h to obtain phosphorus-doped porous carbon. (2) Phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, trialdehyde phloroglucinol and N,N-dimethylformamide were mixed in a mass ratio of 1:1.1:2.5:500 and sonicated for 20s. Then, acetic acid solution of 38 times the mass of phosphorus-doped porous carbon (7 mol / L) was added. The mixture was degassed 4 times in a nitrogen atmosphere by freezing and thawing. The mixture was heated to 95℃ and reacted for 47h. After cooling, the mixture was filtered, washed 5 times with anhydrous ethanol, and dried at 85℃ for 11h to obtain composite porous carbon. (3) The composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.3 mol / L hydrochloric acid solution and 0.4 mol / L pyrrole ethanol solution were mixed at a mass ratio of 1:0.8:63:26 and stirred at 30℃ and 400 rpm for 35 min. 1.1 mol / L ammonium persulfate solution with a mass of 25 times that of the nanoporous carbon was added at a uniform rate within 40 min. After standing at 0℃ for 11 h, the mixture was filtered and washed 5 times with deionized water and anhydrous ethanol, respectively. The mixture was dried at 65℃ for 11 h to obtain the layered structure capacitor electrode material.

[0023] Comparative Example 1: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 1 and Example 2 lies only in step (1). Step (1) is modified as follows: dried and pulverized buckwheat hulls and polyphosphoric acid are mixed at a mass ratio of 1:4, reacted in a microwave at 25°C and 800W for 2 minutes, washed four times with deionized water and anhydrous ethanol respectively, and dried at 60°C for 12 hours to obtain phosphorus-doped porous carbon. The remaining steps are the same as in Example 2.

[0024] Comparative Example 2: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 2 and Example 2 lies only in step (2). Step (2) is modified as follows: phosphorus-doped porous carbon, p-phenylenediamine, trialdehyde-resorcinol, and N,N-dimethylformamide are mixed in a mass ratio of 1:1:2.4:400, sonicated for 15 seconds, and then acetic acid solution of 37.5 times the mass of phosphorus-doped porous carbon (6 mol / L) is added. The mixture is then subjected to three cycles of freeze-thaw degassing under a nitrogen atmosphere, heated to 90°C, and reacted for 48 hours. After cooling, the mixture is filtered, washed four times with anhydrous ethanol, and dried at 80°C for 12 hours to obtain composite porous carbon. The remaining steps are the same as in Example 2.

[0025] Comparative Example 3: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 3 and Example 2 lies only in step (3). Step (3) is modified as follows: composite porous carbon, 0.2 mol / L hydrochloric acid solution, and 0.35 mol / L pyrrole ethanol solution are mixed at a mass ratio of 1:62.5:40, stirred at 25°C and 350 rpm for 40 min, and then 20 times the mass of nanoporous carbon in 1 mol / L ammonium persulfate solution is added uniformly over 35 min. After standing at -1°C for 12 h, the mixture is filtered, washed four times with deionized water and anhydrous ethanol, and dried at 60°C for 12 h to obtain the hierarchical capacitor electrode material. The remaining steps are the same as in Example 2.

[0026] Comparative Example 4: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 4 and Example 2 lies only in step (1). Step (1) is modified as follows: dried and pulverized buckwheat hulls, polyphosphoric acid, and a 98.5% sulfuric acid solution are mixed at a mass ratio of 1:3:0.65, reacted in a microwave at 25°C and 800W for 2 minutes, washed four times with deionized water and anhydrous ethanol respectively, and dried at 60°C for 12 hours to obtain phosphorus-doped porous carbon. The remaining steps are the same as in Example 2.

[0027] Comparative Example 5: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 5 and Example 2 lies only in step (1). Step (1) is modified as follows: dried and pulverized buckwheat hulls, polyphosphoric acid, and a 98.5% sulfuric acid solution are mixed at a mass ratio of 1:4:0.65, reacted in a microwave at 25°C and 800W for 2 minutes, washed four times with deionized water and anhydrous ethanol respectively, and dried at 60°C for 12 hours to obtain phosphorus-doped porous carbon. The remaining steps are the same as in Example 2.

[0028] Comparative Example 6: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 6 and Example 2 lies only in step (3). Step (3) is modified as follows: composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.2 mol / L hydrochloric acid solution, and 0.35 mol / L pyrrole ethanol solution are mixed at a mass ratio of 1:0.8:62.5:10 and stirred at 25°C and 350 rpm for 40 min. Then, 20 times the mass of the nanoporous carbon in 1 mol / L ammonium persulfate solution is added uniformly over 35 min. After standing at -1°C for 12 h, the mixture is filtered, washed four times with deionized water and anhydrous ethanol, and dried at 60°C for 12 h to obtain the hierarchical capacitor electrode material. The remaining steps are the same as in Example 2.

[0029] Comparative Example 7: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 7 and Example 2 lies only in step (3). Step (3) is modified as follows: composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.2 mol / L hydrochloric acid solution, and 0.35 mol / L pyrrole ethanol solution are mixed at a mass ratio of 1:0.8:62.5:15 and stirred at 25°C and 350 rpm for 40 min. Then, 20 times the mass of the nanoporous carbon in 1 mol / L ammonium persulfate solution is added uniformly over 35 min. After standing at -1°C for 12 h, the mixture is filtered, washed four times with deionized water and anhydrous ethanol, and dried at 60°C for 12 h to obtain the hierarchical capacitor electrode material. The remaining steps are the same as in Example 2.

[0030] Comparative Example 8: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 8 and Example 2 lies only in step (3). Step (3) is modified as follows: composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.2 mol / L hydrochloric acid solution, and 0.35 mol / L pyrrole ethanol solution are mixed at a mass ratio of 1:0.8:62.5:35 and stirred at 25°C and 350 rpm for 40 min. Then, 20 times the mass of the nanoporous carbon in 1 mol / L ammonium persulfate solution is added uniformly over 35 min. After standing at -1°C for 12 h, the mixture is filtered, washed four times with deionized water and anhydrous ethanol, and dried at 60°C for 12 h to obtain the hierarchical capacitor electrode material. The remaining steps are the same as in Example 2.

[0031] Comparative Example 9: The difference between the hierarchical capacitor electrode material and its preparation method in Comparative Example 9 and Example 2 lies only in step (3). Step (3) is modified as follows: composite porous carbon, sodium 1H-pyrrole-3-sulfonate, 0.2 mol / L hydrochloric acid solution, and 0.35 mol / L pyrrole ethanol solution are mixed at a mass ratio of 1:0.8:62.5:40 and stirred at 25°C and 350 rpm for 40 min. Then, 20 times the mass of the nanoporous carbon in 1 mol / L ammonium persulfate solution is added uniformly over 35 min. After standing at -1°C for 12 h, the mixture is filtered, washed four times with deionized water and anhydrous ethanol, and dried at 60°C for 12 h to obtain the hierarchical capacitor electrode material. The remaining steps are the same as in Example 2.

[0032] Test Example 1: Dosage of polyphosphoric acid: Test Method: The layered capacitor electrode material obtained in the examples and comparative examples was mixed with acetylene black at a mass ratio of 8:1, ground with an agate mortar, and then mixed with 0.12-0.13 times the mass of the layered capacitor electrode material in polytetrafluoroethylene and coated onto a carbon rod. Ag / AgCl was used as the reference electrode, platinum electrode (Pt) as the counter electrode, and 1 mol / L H₂SO₄ as the electrolyte. Constant current charge-discharge tests were performed in the potential range of 0-0.8V using a CHI760E electrochemical workstation and a LAND battery testing system. The specific capacitance of the electrode was calculated as (discharge current × discharge time during charge-discharge process) / (total working potential × mass).

[0033] Table 1 A comparison of the experimental data from Examples 1-3 and Comparative Examples 4-5 in Table 1 reveals that the layered capacitor electrode material prepared by this invention has good specific capacitance.

[0034] By comparison, Examples 1, 2, and 3 showed higher specific capacitance than Comparative Examples 4 and 5, indicating that phosphorus atoms were successfully doped into the carbon framework, providing additional pseudocapacitance. Excessive polyphosphoric acid would lead to over-etching of the carbon framework, structural collapse, and loss of some double-layer capacitance.

[0035] Test Example 2: Pyrrole dosage: Test Method: The layered capacitor electrode material obtained in the examples and comparative examples was mixed with acetylene black at a mass ratio of 8:1, ground with an agate mortar, and then mixed with 0.12-0.13 times the mass of the layered capacitor electrode material in polytetrafluoroethylene and coated onto a carbon rod. Ag / AgCl was used as the reference electrode, platinum electrode (Pt) as the counter electrode, and 1 mol / L H₂SO₄ as the electrolyte. Constant current charge-discharge tests were performed in the potential range of 0-0.8V using a CHI760E electrochemical workstation and a LAND battery testing system. The specific capacitance of the electrode was calculated as (discharge current × discharge time during charge-discharge process) / (total working potential × mass).

[0036] Table 2 A comparison of the experimental data from Examples 1-3 and Comparative Examples 6-9 in Table 2 reveals that the layered capacitor electrode material prepared by this invention has good specific capacitance.

[0037] By comparison, Examples 1, 2, and 3 showed higher specific capacitance than Comparative Examples 6-9, indicating that doping with polypyrrole increased the pseudocapacitance of porous carbon and improved the specific capacitance of the material. However, excessive polypyrrole can agglomerate on the surface of carbon materials, which can actually reduce the performance of the electrode materials.

[0038] Specific surface area of ​​test example 3: Test method: The nitrogen adsorption capacity of the hierarchical capacitor electrode materials obtained in each embodiment and comparative example was determined by a gas physical adsorption instrument at a test temperature of 77K, and the specific surface area was calculated using the BET (Brunauer-Emmett-Teller) method.

[0039] Table 3 A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 3 reveals that the layered capacitor electrode material prepared by this invention has a good specific surface area.

[0040] Comparative Example 1 did not involve the addition of sulfuric acid in microwave carbonization. By comparison, Examples 1, 2, and 3 had a larger total specific surface area than Comparative Example 1, indicating that the dehydration ability of concentrated sulfuric acid was used to lower the carbonization temperature of buckwheat hulls. The hulls reacted with the hot pyrolytic carbon to generate a large amount of CO2, SO2, and H2O gases, which further etched the carbon skeleton to create more pores and increase the specific surface area.

[0041] Comparative Example 3 did not contain sodium 1H-pyrrole-3-sulfonate. By comparison, Examples 1, 2, and 3 had a larger total specific surface area than Comparative Example 3, indicating that by using chemical oxidation to polymerize pyrrole and sodium 1H-pyrrole-3-sulfonate monomers on the porous carbon surface, conductive polypyrrole long chains with sulfonic acid groups in the side chains are formed, and the steric hindrance of the side chains is used to avoid polymerization clogging the pore structure.

[0042] Test Example 4: Electron Conductivity Test Method: The hierarchical capacitor electrode material obtained in the examples and comparative examples was mixed with acetylene black at a mass ratio of 8:1, ground in an agate mortar, and then mixed with 0.12-0.13 times the mass of the hierarchical capacitor electrode material in polytetrafluoroethylene and coated onto a carbon rod. Ag / AgCl was used as the reference electrode, platinum electrode (Pt) as the counter electrode, and 1 mol / L H₂SO₄ as the electrolyte. The test was conducted using a CHI760E electrochemical workstation and a LAND battery testing system at a frequency range of 10... 5 ~10 -2 Electrochemical impedance spectroscopy was performed under the conditions of Hz and AC amplitude of 5mV to compare charge transfer resistance (the semi-circle radius of the high-frequency part in the Nyquist figure).

[0043] Table 4 A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 4 reveals that the layered capacitor electrode material prepared by this invention has good electronic conductivity.

[0044] Comparative Example 1 did not involve the addition of sulfuric acid for microwave carbonization. By comparison, Examples 1, 2, and 3 showed lower charge transfer resistance than Comparative Example 1, indicating that the use of concentrated sulfuric acid to absorb microwaves and assist polyphosphoric acid in heating the reaction system introduces phosphorus atoms into the carbon skeleton, thereby improving the conductivity of the electrode material and accelerating electron transport.

[0045] Comparative Example 2 did not use 2,6-diaminoanthraquinone; by comparison, Examples 1, 2, and 3 had lower charge transfer resistance than Comparative Example 2, indicating that a covalent organic framework containing anthraquinone structure was prepared on a porous carbon surface using a solvothermal in-situ composite method, and the conjugated structure of the covalent organic framework can assist in electron conduction.

[0046] Test Example 5: Ion Diffusion Test Method: The hierarchical capacitor electrode material obtained in the examples and comparative examples was mixed with acetylene black at a mass ratio of 8:1, ground in an agate mortar, and then mixed with 0.12-0.13 times the mass of the hierarchical capacitor electrode material in polytetrafluoroethylene and coated onto a carbon rod. Ag / AgCl was used as the reference electrode, platinum electrode (Pt) as the counter electrode, and 1 mol / L H₂SO₄ as the electrolyte. The test was conducted using a CHI760E electrochemical workstation and a LAND battery testing system at a frequency range of 10... 5 ~10 -2 Electrochemical impedance spectroscopy was performed under the conditions of Hz and AC amplitude of 5mV to compare the ion diffusion impedance (the slope of the low-frequency part of the Nyquist plot).

[0047] Table 5 A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 5 reveals that the layered capacitor electrode material prepared by this invention exhibits good ion diffusion properties.

[0048] Comparative Example 1 did not involve the addition of sulfuric acid for microwave carbonization. By comparison, Examples 1, 2, and 3 showed lower ion diffusion impedance than Comparative Example 1, indicating that the use of concentrated sulfuric acid to absorb microwaves and assist polyphosphoric acid in heating the reaction system introduces phosphorus atoms into the carbon framework, thereby improving the wettability of the electrode material and accelerating ion transport.

[0049] Comparative Example 2 did not use 2,6-diaminoanthraquinone; by comparison, Examples 1, 2, and 3 showed lower ion diffusion resistance than Comparative Example 2, indicating that the preparation of covalent organic frameworks containing anthraquinone structures on porous carbon surfaces using the solvothermal in-situ composite method can synergistically promote ion transport with porous carbon through the regular channels of the covalent organic frameworks.

[0050] Comparative Example 3 did not contain sodium 1H-pyrrole-3-sulfonate. By comparison, Examples 1, 2, and 3 showed lower ion diffusion resistance than Comparative Example 3, indicating that by using ammonium persulfate as an oxidant and doping with hydrochloric acid, pyrrole and sodium 1H-pyrrole-3-sulfonate monomers were polymerized on the porous carbon surface through chemical oxidation to form conductive polypyrrole long chains with sulfonic acid groups in the side chains. The strong hydrophilicity of the sulfonic acid groups in the side chains can promote the wetting of the electrode material by the electrolyte, enhance the rapid transport of electrolyte ions inside the electrode, and improve the ion conductivity of the electrode material.

[0051] Test Example 6: Mass-to-Capacitance Ratio Test Method: The layered capacitor electrode material obtained in the examples and comparative examples was mixed with acetylene black at a mass ratio of 8:1, ground with an agate mortar, and then mixed with 0.12-0.13 times the mass of the layered capacitor electrode material in polytetrafluoroethylene and coated onto a carbon rod. Ag / AgCl was used as the reference electrode, platinum electrode (Pt) as the counter electrode, and 1 mol / L H₂SO₄ as the electrolyte. Constant current charge-discharge tests were performed in the potential range of 0-0.8V using a CHI760E electrochemical workstation and a LAND battery testing system. The specific capacitance of the electrode was calculated as (discharge current × discharge time during charge-discharge process) / (total working potential × mass).

[0052] Table 6 A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 6 reveals that the layered capacitor electrode material prepared by this invention has good specific capacitance.

[0053] Comparative Example 1 did not involve the addition of sulfuric acid in microwave carbonization. By comparison, Examples 1, 2, and 3 showed a larger specific capacitance than Comparative Example 1, indicating that concentrated sulfuric acid is a strong inorganic acid with excellent microwave absorption. It can assist the polyphosphoric acid heating reaction system, introduce phosphorus atoms into the carbon skeleton, increase defect sites, endow porous carbon with additional pseudocapacitive effects, and improve the specific capacitance of the electrode material.

[0054] Comparative Example 2 did not use 2,6-diaminoanthraquinone. By comparison, Examples 1, 2, and 3 had a larger specific capacitance than Comparative Example 2, indicating that the preparation of a covalent organic framework containing anthraquinone structure on the porous carbon surface using the solvothermal in-situ composite method forms physical spacers, enhances the dispersibility of porous carbon, and the quinone group (C=O) in the anthraquinone molecule can be reversibly oxidized and reduced, providing additional pseudocapacitance and improving the specific capacitance of the electrode material.

[0055] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A layered capacitor electrode material, characterized in that, The electrode material of the hierarchical capacitor is obtained by reacting composite porous carbon, sodium 1H-pyrrole-3-sulfonate and pyrrole. The composite porous carbon is obtained by reacting phosphorus-doped porous carbon, 2,6-diaminoanthraquinone and trialdehyde phloroglucinol. The phosphorus-doped porous carbon is obtained by microwave carbonization of dried and pulverized buckwheat hulls, polyphosphoric acid, and sulfuric acid.

2. A layered capacitor electrode material and its preparation method, characterized in that, The preparation steps include the following: (1) Mix the dried and crushed buckwheat hulls, polyphosphoric acid and sulfuric acid solution in a mass ratio of 1:(3.3~3.4):(0.6~0.7), react with microwave at 20~30℃ and 700~900W for 1~3 min, wash with deionized water and anhydrous ethanol 3~5 times respectively, and dry at 55~65℃ for 11~13 h to obtain phosphorus-doped porous carbon; (2) Phosphorus-doped porous carbon, 2,6-diaminoanthraquinone, trialdehyde phloroglucinol and N,N-dimethylformamide were mixed at a mass ratio of 1:(0.9~1.1):(2.3~2.5):(300~500), sonicated for 10~20s, and acetic acid solution of 37~38 times the mass of phosphorus-doped porous carbon was added. The mixture was degassed by freezing and thawing 2~4 times in a nitrogen atmosphere, heated to 85~95℃ and reacted for 47~49h. After cooling, the mixture was filtered, washed 3~5 times with anhydrous ethanol, and dried at 75~85℃ for 11~13h to obtain composite porous carbon. (3) The composite porous carbon, sodium 1H-pyrrole-3-sulfonate, hydrochloric acid solution and pyrrole ethanol solution are mixed at a mass ratio of 1:(0.7~0.9):(62~63):(24~26). The mixture is stirred at 20~30℃ and 300~400rpm for 35~45min. Ammonium persulfate solution with a mass of 15~25 times that of the nanoporous carbon is added uniformly within 30~40min. After standing at -2~0℃ for 11~13h, the mixture is filtered and washed 3~5 times with deionized water and anhydrous ethanol respectively. The mixture is then dried at 55~65℃ for 11~13h to obtain the layered structure capacitor electrode material.

3. The layered capacitor electrode material and its preparation method according to claim 2, characterized in that, The sulfuric acid solution mentioned in step (1) is a sulfuric acid solution with a mass fraction of 98%~99%.

4. The layered capacitor electrode material and its preparation method according to claim 2, characterized in that, The concentration of the acetic acid solution in step (2) is 5~7 mol / L.

5. The layered capacitor electrode material and its preparation method according to claim 2, characterized in that, The concentration of the hydrochloric acid solution in step (3) is 0.1~0.3 mol / L.

6. The layered capacitor electrode material and its preparation method according to claim 2, characterized in that, The concentration of the pyrrole ethanol solution in step (3) is 0.3~0.4 mol / L.

7. The layered capacitor electrode material and its preparation method according to claim 2, characterized in that, The concentration of the ammonium persulfate solution in step (3) is 0.9~1.1 mol / L.

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