CN109920660B

CN109920660B - Preparation method of super capacitor electrode based on heteroatom doped carbon material

Info

Publication number: CN109920660B
Application number: CN201910144620.5A
Authority: CN
Inventors: 张晶晶; 陈锡安; 崔翠霞; 吴婉仪; 金辉乐; 金晓铭
Original assignee: Wenzhou University
Current assignee: Wenzhou University
Priority date: 2019-02-27
Filing date: 2019-02-27
Publication date: 2021-11-02
Anticipated expiration: 2039-02-27
Also published as: CN109920660A

Abstract

The invention relates to a preparation method of a super capacitor electrode based on a heteroatom doped carbon material. The dry yeast has more advantages for the high-temperature treatment of the yeast through the direct pyrolysis method, the excellent electrochemical performance of the biomass carbon can be better exerted, the synthesized electrode material can provide continuous and stable electric energy when being used in a super capacitor, and the service life is greatly prolonged.

Description

Preparation method of super capacitor electrode based on heteroatom doped carbon material

Technical Field

The invention relates to a bio-based carbon material, belongs to the technical field of inorganic functional materials and electrochemical energy, and particularly relates to a preparation method of a super capacitor electrode based on a heteroatom doped carbon material.

Background

In recent years, nonrenewable resources such as fossil fuels and the like generate serious air environment pollution under the condition of large consumption of developed industrial countries in the world, the pollution greatly influences the normal healthy life of human beings, people gradually realize the major development, and all countries actively call people to build a low-carbon environment-friendly, energy-saving and emission-reducing living environment. To this end, supercapacitor research has shifted the center of gravity to research efficient, environmentally friendly energy storage devices in response to calls. Researchers have studied common energy storage and supply devices such as solar cells and lithium batteries and have gained a lot of gains.

As for an electrode material which is one of important components in a super capacitor, the research and development of the electrode material greatly influence the overall service performance of the super capacitor, and the electrode material of the super capacitor developed up to now uses carbon materials and transition metal oxides as common electrode materials, while the conductive polymer material has good performance as a new electrode material. However, in practice, the latter two electrode materials are more costly than those in preparation and production, and are not environment-friendly, and meanwhile, the super capacitor electrode prepared by using the metal material and the conductive polymer as the electrode materials has lower stability, so that research on the super capacitors using the latter two electrode materials has more limitations and uncontrollable factors, and mass production and manufacturing are unlikely to be realized in a short period. On the contrary, heteroatom-doped activated carbon has characteristics of excellent adsorption performance, easy generation of porous structure, high ion transmission efficiency in electrolyte and the like, and is widely researched and applied.

The method adopts a carbon fluoride material or a carbon fluoride nano tube as a carbon substrate, pyridine, thiophene, triphenylphosphine solution and the like as nitrogen, sulfur and phosphorus sources, and the nitrogen, sulfur and phosphorus sources are doped into the carbon substrate by a cracking deposition method at high temperature.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of the prior art, and provides a preparation method of a super capacitor electrode based on a heteroatom doped carbon material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a super capacitor electrode based on a heteroatom doped carbon material comprises the following steps:

(1) direct pyrolysis treatment of yeast: weighing 2-4mg of dry yeast, placing the dry yeast in a porcelain boat, and placing the porcelain boat in a tubular furnace for calcining under the condition that nitrogen is taken as protective gas to form a heteroatom doped carbon material;

the calcination temperature in the step (1) is 600 ℃, 700 ℃, 800 ℃, 900 ℃ or 1000 ℃.

The invention also provides a heteroatom doped carbon material prepared by the preparation method.

The beneficial effect of above-mentioned scheme is: according to the invention, yeast is used as a raw material, and the biomass pellet material is obtained through special carbonization, so that the prepared pellet material has excellent rate performance, and the retention rate is 98.3% after 5000 cycles. Experimental results show that the porous carbon material prepared by using the biomass material as the carbon source has great development and application values in the super capacitor.

Preferably, the specific capacitance of the supercapacitor obtained under the condition that the calcination temperature in the step (1) is 800 ℃ is 1mV^-1At a scanning rate of 181.82Fg^-1。

Preferably, the super capacitor obtained in the step (1) under the condition that the calcination temperature is 800 ℃ is 0.5Ag^-1The specific capacitance of the capacitor reaches 198.5Fg under the current density^-1。

Preferably, the electrode material pyrolyzed and synthesized at 800 ℃ in the step (1) is subjected to a stability test, and the current density is 20Ag^-1The cycle number is 5000 times, and the capacity retention rate reaches 98.3 percent.

The invention has the beneficial effects that: the invention provides a super capacitor electrode based on a heteroatom-doped biomass carbon material and a preparation method thereof, wherein the direct thermal hydrolysis method has more advantages on high-temperature treatment of yeast, can better exert the excellent electrochemical performance of biomass, and simultaneously can realize environmental protection, energy conservation and low carbon, so that the method is a good process.

The invention also aims to provide the heteroatom-doped biomass carbon material prepared by the method.

The invention also provides an application method of the heteroatom-doped biomass carbon material prepared by the method, namely the heteroatom-doped biomass carbon material is used for preparing capacitor electrodes.

Specifically, the invention also provides a preparation method for preparing the capacitor electrode by adopting the heteroatom-doped biomass carbon material, which comprises the following steps:

s1, doping a carbon material with hetero atoms in a mass ratio: acetylene black: weighing the materials in a ratio of 8:1:1, dissolving the materials in 0.5-2mL of ethanol solution, fully and uniformly grinding the materials, stirring the materials into paste, and coating the paste on the foamed nickel;

s2, placing the foamed nickel coated with the heteroatom doped carbon material under an infrared irradiation lamp for 10-20min for drying, and then placing the nickel sheet into a weighing bottle filled with 5-7mol/L potassium hydroxide solution for soaking for 8-12h to obtain the supercapacitor electrode.

Preferably, the effective mass of the active material coated on the nickel foam sheet in the step S1 is 2-4mg, and the coating area is 1cm²。

Preferably, the mass ratio of the potassium hydroxide to the heteroatom-doped biomass carbon material in the step S2 is 1: 0.1-1.5.

Preferably, the mass ratio of the potassium hydroxide to the heteroatom-doped biomass carbon material in the step S2 may be 1:0.5, 1:1 or 1: 1.5.

Preferably, the electrode prepared in step S2 with the mass ratio of potassium hydroxide to the heteroatom-doped biomass carbon material being 1:1 is 0.5Ag^-1Current density of 272.4F g^-1。

The beneficial effects of the above technical scheme are: the prepared capacitor electrode has good rate performance, high stability, simple preparation method and low cost, and is beneficial to popularization and use.

Finally, the invention also provides a capacitor electrode containing the heteroatom-doped biomass carbon material prepared by the method.

In conclusion, the beneficial effects of the invention are as follows: the method for preparing the heteroatom-doped carbon material and the capacitor electrode prepared by the method have the advantages that the prepared electrode has good electrochemical performance, large-current charge and discharge are easy, the cycle life is long, and importantly, the preparation process is simple and convenient, the cost is low, the method is suitable for industrial production, and the popularization and application values are high.

Drawings

FIG. 1 SEM image of yeast at 700 ℃ by direct pyrolysis method;

FIG. 2 SEM image of yeast at 800 ℃ in direct pyrolysis process;

FIG. 3 SEM image of yeast at 900 ℃ in the direct pyrolysis method;

FIG. 4 XRD patterns of yeast treated at high temperature of 700 deg.C, 800 deg.C, 900 deg.C;

FIG. 5800 ℃ BET plot of a yeast synthesized by the high temperature direct pyrolysis method;

FIG. 6 influence of different synthesis temperatures on the electrochemical performance of electrode materials;

plots CV and CP at different scan rates for 7800 ℃ synthesized material;

FIG. 8800 ℃ is a plot of power density and energy density of the composite material;

FIG. 9 is a graph of the impedance of electrode material at different temperature treatments;

FIG. 10 is a stability test chart of the electrode material pyrolytically synthesized at 800 ℃.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

The starting materials used in the present invention are commercially available or commonly used in the art, unless otherwise specified, and the methods in the following examples are conventional in the art, unless otherwise specified.

Example 1

Weighing 2-4mg of dry yeast, placing the dry yeast in a porcelain boat, placing the porcelain boat in a tubular furnace under the condition of taking nitrogen as protective gas, carrying out pyrolysis to form a heteroatom-doped biomass-based porous carbon material, carrying out high-temperature treatment at 800 ℃, and then naturally cooling to room temperature to obtain an activated material;

example 2

The temperature of 800 ℃ in example 1 was changed to 700 ℃ and the rest of the conditions were unchanged.

Example 3

The temperature of 800 ℃ in example 1 was changed to 900 ℃ and the rest of the conditions were unchanged.

Example 4

The substances obtained in examples 1, 2 and 3 were subjected to electrochemical tests, the results of which are given in the following table:

carrying out high-temperature pyrolysis treatment on dry yeast at 700 DEG C

Carrying out high-temperature pyrolysis treatment on dry yeast at 800 DEG C

Carrying out high-temperature pyrolysis treatment on dry yeast at 900 DEG C

And (4) conclusion: when carbonized at 800 ℃, the capacitance value of the obtained product is the highest. The following examples use 800 ℃ carbonized materials.

Example 5

From the above examples and results analysis, the substance and parameters adopted in example 1 are the most preferred examples, so the heteroatom-doped carbon material prepared in example 1 is used to prepare capacitor electrodes, comprising the following steps:

s1, doping a carbon material with hetero atoms in a mass ratio: acetylene black: weighing the materials in a ratio of 80:10:10 in PTFE (polytetrafluoroethylene) emulsion, adding ethanol, uniformly mixing, stirring into paste, and coating the paste on the foamed nickel;

s2, placing the foamed nickel coated with the heteroatom doped carbon material under an infrared irradiation lamp for 10-20min for drying, and then placing the nickel sheet into a weighing bottle filled with 5-7mol/L potassium hydroxide solution for soaking for 8-12h to obtain the supercapacitor electrode. In this embodiment, the mass ratio of the potassium hydroxide to the heteroatom-doped biomass carbon material in step S2 may be 1:0.5, 1:1, or 1: 1.5.

Microscopic characterization

(1) SEM, XRD and BET micro-characterization of the high temperature yeast obtained in examples 1-3 were carried out.

As can be seen from the SEM images of figures 1-3, a plurality of spherical substances are attached to the surface of the material, the microscopic size of the material is about 10-20 microns, and the yeasts treated by different high-temperature direct pyrolysis methods all have holes with different degrees, wherein the substance particles on the surface of the yeast treated at 800 ℃ are smaller, the shapes are relatively regular, the porosity is smaller, the holes are favorable for the electrolyte to pass through, the ion channels are smoother, and the pore structure can possibly enable the electrode material prepared from the raw material to have good conductivity.

(2) From the sample XRD pattern of FIG. 4 after different heat treatment temperatures, it can be seen that XRD of each porous carbon has two wider diffraction peaks, the diffraction peak of 23.4 degrees corresponds to (002) of graphitized carbon, and the diffraction peak of 43.8 degrees corresponds to (100) of graphitized carbon. And (4) conclusion: the crystallinity of the material is best under the treatment of 800 ℃.

(3) FIG. 5 shows N in porous carbon₂The adsorption-desorption diagram and the pore size distribution diagram can be concluded as follows:from the aspect of the pore size of the material, the distribution interval of the pore size of the microscopic particles of the material is roughly judged to be mainly concentrated between 1.0 nm and 2.0nm, and the property that most of the microscopic particles belong to micropores or mesopores is judged according to the standard; the microstructure of the feedstock varies with temperature. Wherein, the material under the high-temperature treatment at 800 ℃ has higher specific surface area and pore volume than the material under the other two-temperature treatment, and the total specific surface area is up to 348.69cm² g^-1Therefore, the material has more catalytic active sites under the high-temperature treatment at 800 ℃. Provides guarantee for storage, diffusion and transportation of charges, which is one of the prominent reasons for material performance. And (4) conclusion: the material treated at 800 ℃ has higher specific surface area and better pore size distribution.

TABLE 1

Electrochemical performance test

(4) Effect of temperature variation on electrochemical Performance

As shown in fig. 6, the effect of different synthesis temperatures on the electrochemical performance of the electrode material is set at different scanning rates, and it can be seen from the data that: under the premise of the same scanning rate interval, the specific capacitance of the supercapacitor obtained under the condition that the synthesis temperature is 800 ℃ has the best effect at the scanning rate of 1mV/s, the electrode material prepared at 800 ℃ has longer discharge time, and if the electrode material is used as a power supply, the electrode material can provide longer endurance, but the electrode material at 700 ℃ and 900 ℃ has poor performance, and the electrode material is not synthesized at the temperature. And (4) conclusion: the electrode material prepared at 800 ℃ has the best performance.

(5) The performance tests of CV and CP are carried out on the electrode material prepared by the synthesis method at 800 ℃, the results are shown in two graphs of figure 7, and the specific capacitance of the super capacitor under the optimal condition can reach 198.5Fg calculated by a formula^-1Compared with the electrode material synthesized by the solvothermal method at the same temperature, the performance of the electrode material is improved by 61.1 percent. As can be seen from the CP plot, the electrode material discharge time at small current densities is longer,and the maximum energy density can reach 25.4Kw kg from the energy density and the power density (as shown in figure 8)^-. Table 2 below shows the specific capacitance of the electrode material at the optimal synthesis temperature at different scan rates, and table 3 below shows the specific capacitance of the electrode material at the optimal synthesis temperature at different current densities. And (4) conclusion: the material can show excellent electrochemical performance under high current.

TABLE 2

TABLE 3

(6) As shown in FIG. 9, it can be seen from the yeast impedance test chart treated at different temperatures that: the resistance values of the materials treated at high temperature are all very small, and are all about 1.1 omega, wherein the resistance value of a sample treated at 800 ℃ is the smallest, so the conductivity is better.

(7) Referring to FIG. 10, the stability of the electrode material pyrolyzed and synthesized at 800 deg.C was tested by chronopotentiometry, and the current density was set to 20Ag^-1And the cycle number is 5000 times, so that the initial specific capacitance value is not greatly reduced, and the calculated retention rate is still 98.3%. And (4) conclusion: the carbon material calcined at 800 ℃ under nitrogen has excellent stability performance.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.

Claims

1. A super capacitor electrode based on a heteroatom doped carbon material is characterized in that the preparation method comprises the following steps:

(1) preparing a heteroatom doped carbon material: direct pyrolysis treatment of yeast: weighing 2-4mg of dry yeast, placing the dry yeast in a porcelain boat, and placing the porcelain boat in a tubular furnace for calcining under the condition that nitrogen is taken as protective gas to form a heteroatom doped carbon material;

(2) the method is used for preparing the capacitor electrode and comprises the following steps:

s1, doping a carbon material with hetero atoms in a mass ratio: acetylene black: weighing the materials in a ratio of 1:1 to 8 of PTFE emulsion, dissolving the materials in 0.5-2mL of ethanol solution, fully and uniformly grinding the materials, stirring the materials into paste to obtain an active substance, and coating the active substance on foamed nickel;

s2, placing the foamed nickel coated with the heteroatom doped carbon material under an infrared irradiation lamp for 10-20min to dry, and then placing a nickel sheet into a weighing bottle filled with 5-7mol/L potassium hydroxide solution to soak for 8-12h to obtain a supercapacitor electrode;

in the step (1), the calcination temperature parameter of the dry yeast is 800 ℃; the effective mass of the active substance coated on the foamed nickel sheet in the step (2) is 2-4mg, and the coating area is 1cm²；

The mass ratio of the potassium hydroxide to the heteroatom-doped carbon material in the step (2) is 1: 0.1-1.5.