阅读说明：本技术 一种用作超级电容器电极的氟氮双掺杂活性炭的制备方法 (Preparation method of fluorine-nitrogen double-doped activated carbon used as supercapacitor electrode ) 是由 冯奕钰 陈昱霖 李瑀 于 2018-09-06 设计创作，主要内容包括：本发明公开了一种用作超级电容器电极的氟氮双掺杂活性炭的制备方法,将活性炭与KOH混合,之后将混合液加水并超声一段时间使其分散均匀,将混合液烘干；将所得产物放入管式炉中在氩气氛围下以一定温度保温一段时间；之后将得到的产物用洗涤至中性后烘干；将烘干得到的产物与含氟试剂混合；将得到的混合物,先在氩气氛围下以一定温度保温,之后在相同温度下通入氨气,之后保温通入氩气降残余氨气排净。将产物洗至中性后烘干,即得最终产物。制备得到的氟氮双掺杂活性炭材料具有大孔,介孔,微孔并存的多层次孔结构和良好的电解液浸润性,组装成半电池测试,在100mA/g的电流下比电容为220F/g。(The invention discloses a preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode, which comprises the steps of mixing activated carbon with KOH, adding water into a mixed solution, carrying out ultrasonic treatment for a period of time to uniformly disperse the mixed solution, and drying the mixed solution; putting the obtained product into a tubular furnace, and preserving the temperature for a period of time at a certain temperature under the argon atmosphere; then washing the obtained product to be neutral and drying; mixing the dried product with a fluorine-containing reagent; and (3) firstly preserving the temperature of the obtained mixture at a certain temperature in an argon atmosphere, then introducing ammonia gas at the same temperature, and then preserving the temperature, introducing argon gas and reducing the residual ammonia gas to be exhausted. And washing the product to be neutral, and drying to obtain the final product. The prepared fluorine-nitrogen double-doped activated carbon material has a multi-layer pore structure with coexistence of macropores, mesopores and micropores and good electrolyte wettability, is assembled into a half cell for testing, and has a specific capacitance of 220F/g under the current of 100 mA/g.)

1. A preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode is characterized by comprising the following steps:

step 1, uniformly mixing activated carbon and KOH according to a mass ratio of 1: 5-12, adding water into the mixture, wherein the mass of the water is 450-500 times that of the activated carbon, and uniformly mixing to obtain a mixed solution;

step 2, drying the mixed liquid obtained in the step 1 to obtain pretreated activated carbon;

step 3, treating the pretreated activated carbon obtained in the step 2 at the temperature of 600-850 ℃ for 45-90 min under the protection of inert gas, and cooling to room temperature after the treatment is finished;

step 4, washing the product obtained after the step 3 until the product is neutral by water, and drying the product after washing;

step 5, mixing the product obtained in the step 4 with a low-melting-point fluorinated alkali metal salt according to a molar ratio of 1: 5-10 to obtain a fluorinated mixture, adding water into the fluorinated mixture, uniformly mixing the fluorinated mixture and the water according to a mass ratio of 1: 350-400 to obtain a fluorinated mixed solution, and drying the fluorinated mixed solution to obtain fluorinated activated carbon;

and 6, treating the fluorinated activated carbon obtained in the step 5 at the temperature of 250-300 ℃ for 20-30 min under the protection of inert gas, then switching the inert gas into ammonia gas, introducing ammonia gas 2-3 times the mass of the fluorinated activated carbon per minute, keeping the temperature and introducing the ammonia gas for 20-30 min, then switching the ammonia gas into the inert gas, keeping the temperature and introducing the inert gas for 20-30 min, and cooling to obtain the fluorine and nitrogen double-doped activated carbon.

2. The method for preparing fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode according to claim 1, wherein in the step 1, activated carbon and 10mol/L KOH solution are mixed according to a mass ratio of the activated carbon to KOH in the KOH solution of 1: 5-12, then water is added to obtain a mixed solution, the mass ratio of the activated carbon to the water in the mixed solution is 1: 450-500, and the mixed solution is subjected to ultrasonic treatment for 15-30 min to be uniformly dispersed.

3. The method for preparing fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode according to claim 1, wherein the drying process in the steps 2 and 4 is as follows: and (3) putting the material to be dried into a vacuum drying oven for drying, wherein the vacuum degree is-0.3 to-0.25 MPa, the temperature is 90 to 110 ℃, and the drying time is 2 to 3 hours.

4. The preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode according to claim 1, wherein in the step 3, the temperature of the pretreated activated carbon obtained in the step 2 is raised to 600-850 ℃ in an argon atmosphere, the temperature raising rate is 5-10 ℃/min, the heat preservation treatment is performed for 45-90 min, and the temperature is lowered to room temperature after the treatment is completed.

5. The preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode according to claim 1 is characterized in that in step 5, the product obtained in step 4 is mixed with low-melting-point fluorinated alkali metal salt according to a molar ratio of 1: 5-10 to obtain a fluorinated mixture, water is added into the fluorinated mixture, the mass ratio of the fluorinated mixture to the water is 1: 350-400, the fluorinated mixture is subjected to ultrasonic treatment for 15-20 min to obtain a fluorinated mixed solution after uniform dispersion, the fluorinated mixed solution is dried in a vacuum drying oven at a vacuum degree of-0.3-0.25 MPa and a temperature of 90-110 ℃ for 2-3 hours, and the fluorinated activated carbon is obtained.

6. The preparation method of fluorine-nitrogen double-doped activated carbon used as supercapacitor electrode according to claim 1, wherein the low-melting-point alkali metal fluoride salt is KHF₂、NaHF₂Or LiHF₂。

7. The method for preparing fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode according to claim 1, wherein in the step 6, the fluorinated activated carbon obtained in the step 5 is treated at a temperature of 250-300 ℃ for 20-30 min under the protection of argon gas, then the argon gas is switched to ammonia gas, ammonia gas 2-3 times the mass of the fluorinated activated carbon is introduced every minute, the temperature is maintained, the ammonia gas is introduced for 20-30 min, then the ammonia gas is switched to inert gas, the temperature is maintained, the inert gas is introduced for 20-30 min, the temperature is reduced, the obtained product is washed to be neutral by water, and the obtained product is placed in a vacuum drying oven to be dried, wherein the vacuum degree is-0.3-0.25 MPa, the temperature is 90-110 ℃, and the drying time is 2-3 hours, so that the fluorine-nitrogen double-doped activated carbon is obtained.

8. The preparation method of fluorine-nitrogen double-doped activated carbon used as the electrode of the supercapacitor according to claim 2 or 5, wherein the ultrasonic treatment process adopts 30W of ultrasonic power and 15min of ultrasonic treatment time.

9. A preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode is characterized by comprising the following steps:

step 1, mixing activated carbon and 10mol/L KOH solution in a beaker according to the mass ratio of the activated carbon to KOH in the KOH solution of 1: 5-1: 12, then adding water to obtain a mixed solution, wherein the mass ratio of the activated carbon to the water in the mixed solution is 1: 450-500, and carrying out ultrasonic treatment on the mixed solution for 15min at the ultrasonic power of 30W to uniformly disperse the mixed solution;

step 2, putting the mixed solution obtained in the step 1 into a vacuum drying oven for drying for 3 hours at the vacuum degree of-0.3 MPa and the temperature of 100 ℃ to obtain pretreated activated carbon;

step 3, heating the pretreated activated carbon obtained in the step 2 to 800 ℃ in an argon atmosphere, carrying out heat preservation treatment for 90min at a heating rate of 10 ℃/min, and cooling to room temperature after the treatment is finished;

step 4, washing the product obtained after the step 3 until the product is neutral, and drying the product in a vacuum drying oven at the temperature of 100 ℃ and the vacuum degree of-0.3 MPa for 3 hours after washing;

step 5, mixing the product obtained in the step 4 with KHF₂Mixing according to a molar ratio of 1: 5-10 to obtain a fluorinated mixture, adding water into the fluorinated mixture, wherein the mass ratio of the fluorinated mixture to the water is 1:400, performing ultrasonic treatment for 15-20 min to obtain a uniformly dispersed fluorinated mixed solution, and drying the fluorinated mixed solution in a vacuum drying oven for 3 hours at the temperature of 100 ℃ under the vacuum degree of-0.3 MPa to obtain fluorinated activated carbon;

and 6, treating the fluorinated activated carbon obtained in the step 5 at the temperature of 270 ℃ for 30min under the protection of argon gas, then switching argon gas into ammonia gas, introducing ammonia gas with the mass being 3 times of that of the fluorinated activated carbon per minute, maintaining the temperature and introducing the ammonia gas for 30min, then switching the ammonia gas into inert gas, maintaining the temperature and introducing the inert gas for 30min, cooling, washing the obtained product to be neutral by using water, placing the product into a vacuum drying box for drying, wherein the vacuum degree is-0.3 MPa, the temperature is 100 ℃, and the drying time is 3 hours to obtain the fluorine-nitrogen double-doped activated carbon.

10. The fluorine-nitrogen double-doped activated carbon for the electrode of the supercapacitor prepared by the method for preparing the fluorine-nitrogen double-doped activated carbon for the electrode of the supercapacitor according to claim 1 or 9.

Technical Field

The invention belongs to the technical field of carbon composite materials, and particularly relates to a preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode.

Background

Activated carbon is a black, porous, solid carbonaceous material. The main component is carbon and contains a small amount of elements such as oxygen, hydrogen, sulfur, nitrogen, chlorine and the like. The activated carbon is a porous carbon with low bulk density and large specific surface area because the microcrystalline carbon is irregularly arranged and has pores between cross-links, which can generate carbon tissue defects during activation. And thus is widely used as an electrode of a supercapacitor.

However, the active carbon material widely used at present has low specific capacity due to the problem of concentrated distribution of the pore structure and the problem of wettability with the electrolyte.

The above prior art has the following disadvantages;

1. the prepared activated carbon has small specific surface area and high proportion of small pores in the pore diameter.

2. The prepared active carbon is difficult to be infiltrated by organic electrolyte.

3. The prepared activated carbon contains excessive impurity elements such as oxygen.

Disclosure of Invention

Aiming at the problem that the specific capacity of the conventional activated carbon electrode is low, the method for preparing the fluorine-nitrogen double-doped activated carbon with high specific capacity is provided, the problem of wettability of a material and an electrolyte is solved by introducing fluorine-nitrogen elements, the pore structure distribution of the material is more uniform, and the prepared fluorine-nitrogen double-doped activated carbon has higher specific capacity than that of the conventional activated carbon by matching with the effect of a pseudo capacitor. The invention is realized by the following technical scheme:

a preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode comprises the following steps:

step 1, uniformly mixing activated carbon and KOH according to a mass ratio of 1: 5-12, adding water into the mixture, wherein the mass of the water is 450-500 times that of the activated carbon, and uniformly mixing to obtain a mixed solution;

step 2, drying the mixed liquid obtained in the step 1 to obtain pretreated activated carbon;

step 3, treating the pretreated activated carbon obtained in the step 2 at the temperature of 600-850 ℃ for 45-90 min under the protection of inert gas, and cooling to room temperature after the treatment is finished;

step 4, washing the product obtained after the step 3 until the product is neutral by water, and drying the product after washing;

step 5, mixing the product obtained in the step 4 with a low-melting-point fluorinated alkali metal salt according to a molar ratio of 1: 5-10 to obtain a fluorinated mixture, adding water into the fluorinated mixture, uniformly mixing the fluorinated mixture and the water according to a mass ratio of 1: 350-400 to obtain a fluorinated mixed solution, and drying the fluorinated mixed solution to obtain fluorinated activated carbon;

step 6, treating the fluorinated activated carbon obtained in the step 5 at the temperature of 250-300 ℃ for 20-30 min under the protection of inert gas, then switching the inert gas into ammonia gas, introducing ammonia gas 2-3 times the mass of the fluorinated activated carbon per minute, keeping the temperature and introducing the ammonia gas for 20-30 min, then switching the ammonia gas into the inert gas, keeping the temperature and introducing the inert gas for 20-30 min, and cooling to obtain fluorine-nitrogen double-doped activated carbon;

in the technical scheme, in the step 1, activated carbon and 10mol/L KOH solution are mixed according to the mass ratio of the activated carbon to KOH in the KOH solution being 1: 5-12, then water is added to obtain a mixed solution, the mass ratio of the activated carbon to the water in the mixed solution is 1: 450-500, and the mixed solution is subjected to ultrasonic treatment for 15-30 min to be uniformly dispersed.

In the above technical solution, the drying processes in steps 2 and 4 are both: and (3) putting the material to be dried into a vacuum drying oven for drying, wherein the vacuum degree is-0.3 to-0.25 MPa, the temperature is 90 to 110 ℃, and the drying time is 2 to 3 hours.

In the technical scheme, in the step 3, the pretreated activated carbon obtained in the step 2 is heated to 600-850 ℃ in an argon atmosphere, the heating rate is 5-10 ℃/min, the heat preservation treatment is carried out for 45-90 min, and the temperature is reduced to room temperature after the treatment is finished.

In the technical scheme, step 5, mixing the product obtained in step 4 with low-melting-point fluorinated alkali metal salt according to a molar ratio of 1: 5-10 to obtain a fluorinated mixture, adding water into the fluorinated mixture, wherein the mass ratio of the fluorinated mixture to the water is 1: 350-400, performing ultrasonic treatment for 15-20 min to uniformly disperse the fluorinated mixture to obtain a fluorinated mixed solution, and drying the fluorinated mixed solution in a vacuum drying oven at a vacuum degree of-0.3 to-0.25 MPa and a temperature of 90-110 ℃ for 2-3 hours to obtain fluorinated activated carbon.

In the above technical scheme, the low melting point alkali metal fluoride salt is KHF₂、NaHF₂Or LiHF₂。

In the technical scheme, in the step 6, the fluorinated activated carbon obtained in the step 5 is treated at the temperature of 250-300 ℃ for 20-30 min under the protection of argon gas, then the argon gas is switched into ammonia gas, ammonia gas which is 2-3 times of the mass of the fluorinated activated carbon is introduced into the fluorinated activated carbon every minute, the temperature is kept, the ammonia gas is introduced into the fluorinated activated carbon for 20-30 min, then the ammonia gas is switched into inert gas, the temperature is kept, the inert gas is introduced into the fluorinated activated carbon for 20-30 min, the temperature is reduced, the obtained product is washed to be neutral by water, the product is placed into a vacuum drying oven to be dried, the vacuum degree is-0.3-0.25 MPa, the temperature is 90-110 ℃, and the drying time is 2-3 hours.

In the technical scheme, the ultrasonic power adopted in the ultrasonic treatment process is 30W, and the ultrasonic treatment time is 15 min.

A preparation method of fluorine-nitrogen double-doped activated carbon used as a supercapacitor electrode comprises the following steps:

step 1, mixing activated carbon and 10mol/L KOH solution in a beaker according to the mass ratio of the activated carbon to KOH in the KOH solution of 1: 5-1: 12, then adding water to obtain a mixed solution, wherein the mass ratio of the activated carbon to the water in the mixed solution is 1: 450-500, and carrying out ultrasonic treatment on the mixed solution for 15min at the ultrasonic power of 30W to uniformly disperse the mixed solution;

step 2, putting the mixed solution obtained in the step 1 into a vacuum drying oven for drying for 3 hours at the vacuum degree of-0.3 MPa and the temperature of 100 ℃ to obtain pretreated activated carbon;

step 3, heating the pretreated activated carbon obtained in the step 2 to 800 ℃ in an argon atmosphere, carrying out heat preservation treatment for 90min at a heating rate of 10 ℃/min, and cooling to room temperature after the treatment is finished;

step 4, washing the product obtained after the step 3 until the product is neutral, and drying the product in a vacuum drying oven at the temperature of 100 ℃ and the vacuum degree of-0.3 MPa for 3 hours after washing;

step 5, mixing the product obtained in the step 4 with KHF₂Mixing according to a molar ratio of 1: 5-10 to obtain a fluorinated mixture, adding water into the fluorinated mixture, wherein the mass ratio of the fluorinated mixture to the water is 1:400, performing ultrasonic treatment for 15-20 min to obtain a uniformly dispersed fluorinated mixed solution, and drying the fluorinated mixed solution in a vacuum drying oven for 3 hours at the temperature of 100 ℃ under the vacuum degree of-0.3 MPa to obtain fluorinated activated carbon;

and 6, treating the fluorinated activated carbon obtained in the step 5 at the temperature of 270 ℃ for 30min under the protection of argon gas, then switching argon gas into ammonia gas, introducing ammonia gas with the mass being 3 times of that of the fluorinated activated carbon per minute, maintaining the temperature and introducing the ammonia gas for 30min, then switching the ammonia gas into inert gas, maintaining the temperature and introducing the inert gas for 30min, cooling, washing the obtained product to be neutral by using water, placing the product into a vacuum drying box for drying, wherein the vacuum degree is-0.3 MPa, the temperature is 100 ℃, and the drying time is 3 hours to obtain the fluorine-nitrogen double-doped activated carbon.

The fluorine-nitrogen double-doped activated carbon prepared according to the technical scheme is used as a supercapacitor electrode.

The invention has the advantages and beneficial effects that:

(1) the method has the advantages of simple operation, wide sources of used raw materials such as activated carbon, potassium hydroxide and the like, and low price, so the method has the application prospect of industrial large-scale preparation, and the toxic byproducts in the preparation process are single in variety, so the post-treatment is simple, and the method has certain environmental protection property.

(2) The obtained fluorine-nitrogen double-doped activated carbon has high specific capacity because the obtained fluorine-nitrogen double-doped activated carbon has good pore size distribution, namely macropores, mesopores and micropores exist simultaneously, and the proportion of the mesopores which play a main role in improving the specific capacity is large; meanwhile, the formation of carbon-fluorine semi-ionic bonds in the fluorine-nitrogen doping process greatly improves the good wettability of the material and the electrolyte, promotes the improvement of the specific capacity of the material, and plays an important role in increasing the specific capacity of the material due to the introduction of pseudocapacitance in the nitrogen doping. In conclusion, the fluorine-nitrogen double-doped activated carbon has higher specific capacity than that of the traditional commercial activated carbon, and has wide application prospect.

Drawings

FIG. 1 is a scanning electron microscope image of fluorine-nitrogen double-doped activated carbon prepared in example 1;

FIG. 2 is a graph showing the nitrogen adsorption and desorption and DFT pore size distribution of fluorine-nitrogen double-doped activated carbon prepared in example 1;

a is a nitrogen adsorption and desorption curve, and b is a DFT pore size distribution curve.

FIG. 3 is an X-ray photoelectron spectrum of the fluorine-nitrogen double-doped activated carbon prepared in example 1;

FIG. 4 shows the assembly of fluorine-nitrogen double-doped activated carbon prepared in example 1 and conventional commercial activated carbon into a half-cell (electrolyte is 1mol/L LiClO)₄C-V curve of/EC);

a is the C-V curve of the traditional commercial activated carbon at different scanning speeds, and b is the C-V curve of the fluorine-nitrogen double-doped activated carbon at different scanning speeds, wherein the curve labels 1,2,3,4,5 and 6 respectively represent the scanning speeds of 2,5,10,20,50 and 100 mv/s.

For a person skilled in the art, other relevant figures can be obtained from the above figures without inventive effort.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the present invention is further described below with reference to specific examples.