CN113178338B - A kind of carbazole-based porous carbon/polyaniline composite electrode material and its preparation method - Google Patents

Abstract

The invention belongs to the field of electronic materials, and in particular relates to a carbazole-based porous carbon/polyaniline composite electrode material and a preparation method thereof. The preparation process includes: using carbazole as a monomer and dimethoxymethane as an external link to prepare hypercrosslinked polycarbazole, and then mix it with potassium hydroxide as a precursor of porous carbon, and heat it at high temperature under a nitrogen atmosphere. The nitrogen-containing hierarchical porous carbon is obtained by decomposing, and finally the polyaniline is supported by a chemical oxidation polymerization method to prepare the carbazole-based porous carbon/polyaniline composite electrode material. The present invention utilizes the nitrogen-containing functional group of carbazole and the pore structure of the super-crosslinked polymer to prepare nitrogen-doped porous carbon with a specific surface area of 1576 m² g ^‑1 , and the specific capacitance of the composite electrode material obtained after loading polyaniline reaches 462 F·g ^‑1 , can be used to prepare supercapacitors.

Description

A kind of carbazole-based porous carbon/polyaniline composite electrode material and its preparation method

technical field

The invention belongs to the field of electronic materials, and in particular relates to a carbazole-based porous carbon/polyaniline composite electrode material and a preparation method thereof.

Background technique

Supercapacitor is an emerging green energy storage device, which is generally composed of electrodes, current collectors, electrolytes and separators. Among them, electrode materials are the key factors affecting the performance of supercapacitors, which directly determine the specific capacitance, cycle stability, Performance parameters such as energy density and power density, and the cost of electrode materials and whether they can be mass-produced determine whether supercapacitors can enter the market.

According to the different electrical energy storage mechanisms, supercapacitors can be divided into two main types: electric double layer capacitors and pseudocapacitors. Electric double layer capacitor materials are mainly carbon materials, and pseudocapacitive materials mainly include metal oxides and conductive polymers. The internal resistance of the carbon material is low, and the electric double layer capacitor made has high cycle stability and power density, but the specific capacitance and energy density are low. Pseudocapacitors have higher theoretical capacitance and energy density than electric double layer capacitors, but due to the poor conductivity of pseudocapacitive materials, their cycle stability and rate performance are poor, and their power density is not as good as that of electric double layer capacitors. Therefore, it is a research focus of current electrode materials to organically combine carbon materials and pseudocapacitive materials and try to achieve synergy between components with different energy storage mechanisms to obtain composite materials with excellent performance.

Contents of the invention

The object of the present invention is to provide a carbazole-based porous carbon/polyaniline composite electrode material and a preparation method thereof for the deficiencies of the prior art. In order to prepare a porous carbon/polyaniline composite electrode material with high electrochemical performance and improve the specific capacitance and cycle stability of the material, the present invention proposes to first supercrosslink carbazole with an external linking agent, and make the supercrosslinked The combined polymer is used as the precursor of porous carbon, and at the same time, the etching effect of potassium hydroxide is used to prepare nitrogen-containing porous carbon with a hierarchical porous structure by pyrolysis, and then the polyaniline is loaded on the porous carbon by chemical oxidation polymerization. The carbazole-based porous carbon/polyaniline composite electrode material was obtained.

For realizing above-mentioned object, the technical scheme that the present invention takes is:

A preparation method of carbazole-based porous carbon/polyaniline composite electrode material, comprising the following steps:

(1) Hypercrosslinking of carbazole monomer: Dissolve carbazole monomer in 1,2-dichloroethane, then add dimethoxymethane and stir thoroughly, then add anhydrous ferric chloride, and heat up while stirring to 80°C, and reacted at 80°C for 24 hours. After the product was filtered, it was ultrasonically cleaned with methanol and suction filtered until the filtrate was nearly colorless. After vacuum drying at 80°C, a carbazole-based hypercrosslinked polymer was obtained; wherein, (carbazole+ The molar ratio of dimethoxymethane)/anhydrous ferric chloride is 3:1-1:2, and the molar ratio of dimethoxymethane/carbazole is 3:1-1:2.

(2) Preparation of porous carbon by pyrolysis: disperse the carbazole-based hypercrosslinked polymer and potassium hydroxide prepared in step (1) in absolute ethanol at a mass ratio of 1:2-1:6, at 60°C Stir until the solvent is evaporated to dryness, then place the dried mixture in a tube furnace, raise the temperature to 600-900°C at a rate of 5°C/min under a nitrogen atmosphere, and then maintain the temperature for 1-3 hours for pyrolysis at high temperature. The product is acid-washed, washed with water and dried to obtain carbazole-based porous carbon.

(3) Porous carbon-supported polyaniline: disperse carbazole-based porous carbon in 1M hydrochloric acid, and then add a certain proportion of aniline (the final concentration of aniline is 0.05M-0.2M, and the mass ratio of aniline/porous carbon is 2:1- 1:2), stirred at 0-5°C for 1 hour for later use; then dissolved a certain amount of ammonium persulfate in an equivalent amount of 1M hydrochloric acid (the molar ratio of aniline/ammonium persulfate was 5:1-1:2), and After being stored at 0-5°C for 0.5 hours, it is added to the above mixed solution, reacted at 0-5°C for 12 hours, and the product is washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material.

The present invention adopts the above technical scheme, utilizes carbazole as a monomer of a hypercrosslinked polymer, and uses dimethoxymethane as an external linking agent to prepare hypercrosslinked polycarbazole, and then uses it as a precursor of porous carbon and hydrogen Potassium oxide is mixed, nitrogen-containing hierarchical porous carbon is obtained by high-temperature pyrolysis, and finally polyaniline is loaded by chemical oxidation polymerization to prepare a carbazole-based porous carbon/polyaniline composite electrode material.

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts hypercrosslinked polycarbazole as the precursor of porous carbon, utilizes the nitrogen-containing functional group of carbazole and the microporous structure of hypercrosslinked polymer, and prepares a carbon fiber with a specific surface area of 1576 m²·g ^-1 and an average pore diameter A nitrogen-doped porous carbon with a density of 22.0 Å can be loaded with polyaniline to obtain a composite electrode material with a specific capacitance of 462 F·g ^-1 .

2. The hypercrosslinked polymer prepared by using carbazole as a monomer in the present invention has a rigid main chain and a conjugated electron-rich system, which is conducive to the formation of a permanent porous structure and will not be easily denatured. The porous carbon prepared by using it as a precursor can fully Retaining the microporous structure and rigid skeleton of hypercrosslinked polycarbazole is not only beneficial to the loading of polyaniline, but also conducive to the diffusion and contact of electrolyte.

3. The present invention utilizes the nitrogen-containing functional group of carbazole to prepare nitrogen-doped porous carbon through pyrolysis of hypercrosslinked polycarbazole. Nitrogen doping can enhance the surface wettability of the material and provide more abundant active sites. And provide pseudocapacitance for carbon materials, improve the conductivity and charge storage capacity of composite materials after porous carbon loaded polyaniline.

4. The carbazole-based porous carbon/polyaniline composite electrode material prepared by the present invention is a black powder with excellent electrochemical performance, which provides a new idea for the preparation of composite electrode materials.

Description of drawings

Fig. 1 is the galvanostatic charge-discharge curve of embodiment 1 porous carbon/polyaniline composite electrode material;

Fig. 2 is the scanning electron micrograph of embodiment 1 porous carbon/polyaniline composite electrode material;

Fig. 3 is that embodiment 1 is the nitrogen adsorption-desorption curve of carbazole-based porous carbon;

Fig. 4 is a pore size distribution diagram of the carbazole-based porous carbon in Example 1.

Detailed ways

In order to make the content of the present invention easier to understand, the following examples will further illustrate the present invention, but the protection scope of the present invention is not limited to these examples.

Example 1

(1) Dissolve 30 mmol of carbazole monomer in 120 mL of 1,2-dichloroethane, then add 60 mmol of dimethoxymethane and stir thoroughly, then add 45 mmol of anhydrous ferric chloride, while stirring Raise the temperature to 80°C and react at 80°C for 24 hours. After the product is filtered, it is ultrasonically cleaned with methanol and filtered until the filtrate is nearly colorless. After vacuum drying at 80°C, a carbazole-based hypercrosslinked polymer is obtained;

(2) Disperse 1 g of the product obtained in step (1) and 4 g of potassium hydroxide in 300 mL of absolute ethanol, raise the temperature to 60 ° C and stir until the solvent evaporates to dryness, place the solid mixture in a tube furnace, and Under the atmosphere, the heating rate was increased to 700 °C at a rate of 5 °C/min, and the pyrolysis was maintained at 700 °C for 1.5 hours, cooled to room temperature, and the pyrolysis product was acid-washed, washed with water, and dried to obtain carbazole-based porous carbon;

(3) Disperse 0.1396g of dried porous carbon and 0.0931g (1 mmol) of aniline in 15mL of 1M hydrochloric acid, and stir at 0°C for 1 hour for later use; another 1 mmol of ammonium persulfate was dissolved in an equivalent amount of 1M hydrochloric acid, and After being stored at 0°C for 0.5 hours, it was added to the mixed solution of aniline and carbon, and reacted at 0°C for 12 hours. The product was washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material with a specific capacitance of 462 F· g ^-1 .

Example 2

(1) Dissolve 30 mmol of carbazole monomer in 120 mL of 1,2-dichloroethane, then add 60 mmol of dimethoxymethane and stir thoroughly, then add 60 mmol of anhydrous ferric chloride, while stirring Raise the temperature to 80°C and react at 80°C for 24 hours. After the product is filtered, it is ultrasonically cleaned with methanol and filtered until the filtrate is nearly colorless. After vacuum drying at 80°C, a carbazole-based hypercrosslinked polymer is obtained;

(2) Disperse 1 g of the product obtained in step (1) and 4 g of potassium hydroxide in 300 mL of absolute ethanol, raise the temperature to 60 °C and stir until the solvent evaporates to dryness. The temperature was increased to 700 °C at a rate of 5 °C/min, and kept at 700 °C for 1.5 hours for pyrolysis, and then cooled to room temperature. The pyrolysis product was acid-washed, washed with water, and dried to obtain carbazole-based porous carbon.

(3) Disperse 0.1396g of dried porous carbon and 0.0931g (1 mmol) of aniline in 15mL of 1M hydrochloric acid, and stir at 0°C for 1 hour for later use; another 1 mmol of ammonium persulfate was dissolved in an equivalent amount of 1M hydrochloric acid, and After being stored at 0°C for 0.5 hours, it was added to a mixed solution of aniline and carbon, reacted at 0°C for 12 hours, and the product was washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material.

Example 3

(1) Dissolve 22.5 mmol of carbazole monomer in 120 mL of 1,2-dichloroethane, then add 67.5 mmol of dimethoxymethane, stir well, then add 45 mmol of anhydrous ferric chloride, while stirring While raising the temperature to 80°C, react at 80°C for 24 hours. After the product is filtered, it is ultrasonically cleaned with methanol and filtered until the filtrate is nearly colorless. After vacuum drying at 80°C, a carbazole-based hypercrosslinked polymer is obtained;

(2) Disperse 1 g of the product obtained in step (1) and 4 g of potassium hydroxide in 300 mL of absolute ethanol, raise the temperature to 60 °C and stir until the solvent evaporates to dryness. The temperature was increased to 700 °C at a rate of 5 °C/min, and kept at 700 °C for 1.5 hours for pyrolysis, and then cooled to room temperature. The pyrolysis product was acid-washed, washed with water, and dried to obtain carbazole-based porous carbon.

(3) Disperse 0.1396g of dried porous carbon and 0.0931g (1 mmol) of aniline in 15mL of 1M hydrochloric acid, and stir at 0°C for 1 hour for later use; another 1 mmol of ammonium persulfate was dissolved in an equivalent amount of 1M hydrochloric acid, and After being stored at 0°C for 0.5 hours, it was added to a mixed solution of aniline and carbon, reacted at 0°C for 12 hours, and the product was washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material.

Example 4

(1) Dissolve 30 mmol of carbazole monomer in 120 mL of 1,2-dichloroethane, then add 60 mmol of dimethoxymethane and stir thoroughly, then add 45 mmol of anhydrous ferric chloride and heat up while stirring to 80°C, react at 80°C for 24 hours, filter the product, ultrasonically clean it with methanol and suction filter until the filtrate is nearly colorless, and dry it in vacuum at 80°C to obtain a carbazole-based hypercrosslinked polymer;

(2) Disperse 1g of the product obtained in step (1) and 3g of potassium hydroxide in 300mL of absolute ethanol, raise the temperature to 60°C and stir until the solvent evaporates to dryness. The temperature was increased to 700 °C at a rate of 5 °C/min, and kept at 700 °C for 1.5 hours for pyrolysis, and then cooled to room temperature. The pyrolysis product was acid-washed, washed with water, and dried to obtain carbazole-based porous carbon.

(3) Disperse 0.1396g of dried porous carbon and 0.0931g (1 mmol) of aniline in 15mL of 1M hydrochloric acid, and stir at 0°C for 1 hour for later use; another 1 mmol of ammonium persulfate was dissolved in an equivalent amount of 1M hydrochloric acid, and After being stored at 0°C for 0.5 hours, it was added to a mixed solution of aniline and carbon, reacted at 0°C for 12 hours, and the product was washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material.

Example 5

(1) Dissolve 30 mmol of carbazole monomer in 120 mL of 1,2-dichloroethane, then add 60 mmol of dimethoxymethane and stir thoroughly, then add 45 mmol of anhydrous ferric chloride while stirring Warm to 80°C, react at 80°C for 24 hours, filter the product, ultrasonically clean it with methanol and suction filter until the filtrate is nearly colorless, and dry it in vacuum at 80°C to obtain a carbazole-based hypercrosslinked polymer;

(2) Disperse 1 g of the product obtained in step (1) and 4 g of potassium hydroxide in 300 mL of absolute ethanol, raise the temperature to 60 °C and stir until the solvent evaporates to dryness. The temperature was increased to 700 °C at a rate of 5 °C/min, and kept at 700 °C for 1.5 hours for pyrolysis, and then cooled to room temperature. The pyrolysis product was acid-washed, washed with water, and dried to obtain carbazole-based porous carbon.

(3) Disperse 0.0931g of dried porous carbon and 0.0931g (1 mmol) of aniline in 15mL of 1M hydrochloric acid, and stir at 0°C for 1 hour for later use; another 1 mmol of ammonium persulfate was dissolved in an equivalent amount of 1M hydrochloric acid, and After being stored at 0°C for 0.5 hours, it was added to a mixed solution of aniline and carbon, reacted at 0°C for 12 hours, and the product was washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material.

Example 6

(1) Dissolve 30 mmol of carbazole monomer in 120 mL of 1,2-dichloroethane, then add 60 mmol of dimethoxymethane and stir thoroughly, then add 45 mmol of anhydrous ferric chloride, while stirring Raise the temperature to 80°C and react at 80°C for 24 hours. After the product is filtered, it is ultrasonically cleaned with methanol and filtered until the filtrate is nearly colorless. After vacuum drying at 80°C, a carbazole-based hypercrosslinked polymer is obtained;

(2) Disperse 1 g of the product obtained in step (1) and 4 g of potassium hydroxide in 300 mL of absolute ethanol, raise the temperature to 60 °C and stir until the solvent evaporates to dryness. The temperature was increased to 700 °C at a rate of 5 °C/min, and kept at 700 °C for 1.5 hours for pyrolysis, and then cooled to room temperature. The pyrolysis product was acid-washed, washed with water, and dried to obtain carbazole-based porous carbon.

(3) Disperse 0.1396g of dried porous carbon and 0.0931g (1 mmol) of aniline in 15mL of 1M hydrochloric acid, and stir at 0°C for 1 hour for later use; another 1.5 mmol of ammonium persulfate was dissolved in an equivalent amount of 1M hydrochloric acid, and After being stored at 0°C for 0.5 hours, it was added to a mixed solution of aniline and carbon, reacted at 0°C for 12 hours, and the product was washed with water and dried to obtain a carbazole-based porous carbon/polyaniline composite electrode material.

Application example

The present invention measures the mass specific capacitance of the prepared carbazole-based porous carbon/polyaniline composite electrode material through an electrochemical workstation, and the specific measurement method is:

Take the composite material prepared in Example 1, mix it with polytetrafluoroethylene and acetylene black in a mass ratio of 8:1:1, add a few drops of ethanol to help disperse, ultrasonicate for 5 minutes, and evenly coat it on the acetone-treated On the hydrophilic carbon cloth, the electrode sheet is pressed at 10MPa, dried in vacuum at 70°C, and the constant current charge-discharge curve of the electrode is tested by the electrochemical workstation, and its mass specific capacitance is calculated by the following formula:

In the formula, C _m is the mass specific capacitance, F g ^-1 ; I is the discharge current, A; Δt is the discharge time, s; m is the mass of the active material of the working electrode, g; ΔV is the voltage drop, V.

Figure 1 is the constant current charge and discharge curve of the composite electrode material in a three-electrode system at a current density of 1A/g, from which the specific capacitance can be calculated to be 462F/g. Figure 2 shows that the composite electrode material has a loose porous structure, indicating that the porous skeleton structure of hypercrosslinked polycarbazole is well maintained after high-temperature carbonization, and the rough surface of the particles proves the loading of polyaniline. The nitrogen adsorption-desorption curves in Figure 3 show that the synthesized carbazole-based porous carbon is basically micropores, and the presence of hysteresis rings indicates that there are still certain mesopores. Figure 4 is the pore size distribution diagram of carbazole-based porous carbon, which shows that micropores below 2nm are the main ones, followed by mesopores of 2-50nm, indicating that carbazole-based porous carbon has a hierarchical porous structure.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (3)

1. A preparation method of a carbazolyl porous carbon/polyaniline composite electrode material is characterized by comprising the following steps: which comprises the following steps:

(1) And (3) carbazole monomer hypercrosslinking: dissolving a carbazole monomer in 1, 2-dichloroethane, adding dimethoxymethane, fully stirring, adding anhydrous ferric trichloride, heating to 80 ℃ while stirring, reacting at 80 ℃ for 24 hours, filtering a product, washing with alcohol, and drying to obtain a carbazolyl hypercrosslinked polymer;

(2) Preparing porous carbon by pyrolysis: dispersing the carbazolyl hypercrosslinked polymer prepared in the step (1) and potassium hydroxide in absolute ethyl alcohol, stirring at 60 ℃ until the solvent is evaporated to dryness, then placing the dried mixture in a tubular furnace, heating to a specific temperature in a nitrogen atmosphere for high-temperature pyrolysis, and carrying out acid washing, water washing and drying on the pyrolysis product to obtain the carbazolyl porous carbon;

(3) Porous carbon-supported polyaniline: dispersing carbazolyl porous carbon in 1M hydrochloric acid, adding aniline, and stirring at 0-5 ℃ for 1 hour to obtain a mixed solution for later use; dissolving ammonium persulfate in equivalent 1M hydrochloric acid, preserving at 0-5 ℃ for 0.5 h, adding into the mixed solution, reacting at 0-5 ℃ for 12 h, washing and drying the product to obtain the carbazolyl porous carbon/polyaniline composite electrode material;

in the step (1), the molar ratio of (carbazole + dimethoxymethane)/anhydrous ferric chloride is 3;

in the step (1), the alcohol washing and drying method comprises the following steps: ultrasonically cleaning the product in methanol until the filtrate is nearly colorless, and then drying in vacuum at 80 ℃;

in the step (2), dispersing the carbazolyl hypercrosslinked polymer and the potassium hydroxide in absolute ethyl alcohol according to the mass ratio of 1;

in the step (2), the high-temperature pyrolysis specifically comprises the following operations: heating to 600-900 ℃ at a heating rate of 5 ℃/min in the nitrogen atmosphere, and then maintaining the temperature for pyrolysis for 1-3 hours;

in the step (3), the aniline concentration in the mixed solution is 0.05M-0.2M, the mass ratio of aniline/carbazolyl porous carbon is 2.

2. The carbazolyl porous carbon/polyaniline composite electrode material prepared by the preparation method according to claim 1.

3. The application of the carbazolyl porous carbon/polyaniline composite electrode material as defined in claim 2 to an electrode of a supercapacitor.

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