阅读说明：本技术 一种超级电容器用富含介孔的分级多孔碳材料的制备方法 (Preparation method of hierarchical porous carbon material rich in mesopores for supercapacitor ) 是由 赵亚萍 李凯 于 2019-11-19 设计创作，主要内容包括：本发明涉及一种超级电容器用富含介孔的分级多孔碳材料的制备方法。该方法包括：将木质素、丝胶与硫酸溶液混合,超声分散,将得到的悬浊液水热反应,水洗,烘干,然后与活化剂混合,活化反应,再浸泡到盐酸溶液中,洗涤,抽滤。该方法原料来源丰富且成本低,工艺简单,得到的分级多孔碳材料结构规整,孔径分级清晰,其表面呈现出多孔结构,将其制备成电极后具有较大电容且倍率性能优异,经过长时间循环后结构依旧稳定,满足了超级电容器开发的需要。(The invention relates to a preparation method of a hierarchical porous carbon material rich in mesopores for a super capacitor. The method comprises the following steps: mixing lignin, sericin and a sulfuric acid solution, carrying out ultrasonic dispersion, carrying out hydrothermal reaction on the obtained suspension, washing with water, drying, mixing with an activating agent, carrying out an activation reaction, soaking in a hydrochloric acid solution, washing, and carrying out suction filtration. The method has the advantages of rich raw material sources, low cost and simple process, the obtained hierarchical porous carbon material has a regular structure, the aperture is graded and clear, the surface of the hierarchical porous carbon material presents a porous structure, the hierarchical porous carbon material has larger capacitance and excellent rate capability after being prepared into an electrode, the structure is still stable after long-time circulation, and the requirement of development of a super capacitor is met.)

1. A hierarchical porous carbon material rich in mesopores for a supercapacitor is characterized in that lignin and a sericin solution are subjected to hydrothermal reaction and then activated with an activating agent to obtain the hierarchical porous carbon material.

2. The carbon material according to claim 1, wherein the activator comprises potassium hydroxide, potassium citrate, potassium carbonate or potassium bicarbonate.

3. The carbon material according to claim 1, wherein the mass ratio of the lignin, the sericin and the activator is 40-50: 1-5: 41-165.

4. A preparation method of a hierarchical porous carbon material rich in mesopores for a supercapacitor comprises the following steps:

(1) mixing lignin, sericin and a sulfuric acid solution, carrying out ultrasonic dispersion, and carrying out hydrothermal reaction on the obtained suspension to obtain a product, wherein the concentration of the lignin in the suspension is 40-50 g/L, and the concentration of the sericin is 1-5 g/L;

(2) and (2) washing the product obtained in the step (1) to be neutral, drying, mixing with an activating agent according to the mass ratio of 1: 1-1: 3, carrying out an activation reaction, soaking in a hydrochloric acid solution, washing to be neutral, and carrying out suction filtration to obtain the hierarchical porous carbon material rich in mesopores for the supercapacitor.

5. The method of claim 4, wherein in step (1), the lignin is derived from corn stover; sericin is obtained by evaporating waste liquid after degumming silk.

6. The method according to claim 4, wherein the sulfuric acid solution in the step (1) has a concentration of 5 to 10 wt%.

7. The method according to claim 4, wherein the ultrasonic dispersion time in the step (1) is 30-60 min; the hydrothermal reaction temperature is 170-190 ℃, and the hydrothermal reaction time is 16-20 h.

8. The method according to claim 4, wherein the activation reaction in the step (2) is: heating to 700-900 ℃ at a heating rate of 1-10 ℃/min and reacting for 1-3 h; the soaking time is 5-10 h.

9. Use of the carbon material of claim 1 in a supercapacitor.

Technical Field

The invention belongs to the field of preparation of porous materials, and particularly relates to a preparation method of a hierarchical porous carbon material rich in mesopores for a supercapacitor.

Background

The super capacitor is a novel energy storage device between a traditional capacitor and a rechargeable battery, and has the advantages which cannot be compared with the traditional capacitor and the rechargeable battery, wherein the electrode material is a key factor for determining the overall performance of the super capacitor. At present, electrode materials are divided into three categories, namely carbon materials, metal oxides and conductive polymers, wherein the metal oxides and the conductive polymers inevitably face the problems of high cost, environmental pollution and the like. Therefore, carbon materials, particularly porous carbon, which are relatively low in cost, have been attracting research interest. The porous carbon material has larger specific surface area and multi-stage distribution pore diameter, can provide abundant active sites, increase the adsorption capacity of charge ions and exceed the storage capacity of a common carbon material, and can also greatly shorten the ion diffusion distance, promote the charge transmission rate and enhance the charge transmission dynamics. The biomass raw material has the characteristics of wide source, rich reserves, reproducibility and the like. The preparation of high-value green porous carbon materials from biomass has become a research hotspot, such as soybeans, corncobs, ethanol production byproducts and the like. The biomass waste is converted into the porous material, so that the value of the porous material can be improved, and the environmental pressure can be reduced. Therefore, the biomass waste can be used as a precursor of the porous carbon material for the supercapacitor, and the prepared electrode material has wide application prospects in the fields of green energy, industry, traffic and the like. In addition, development and application research of the biomass-based porous carbon material provides a green conversion strategy for reducing environmental pressure and improving the added value of the biomass-based porous carbon material.

The porous carbon material has the advantages of high specific surface area, proper pore size distribution, good circulation stability and the like, is suitable for electrode materials, and porous carbon prepared by taking biomass as a raw material by adopting a traditional method has higher specific surface area but basically consists of micropores, so that ion transmission is greatly hindered, and the application value of the material is greatly reduced.

One recently proposed method for preparing graded porous carbon is a chemical template method, such as mesoporous silica foam, silicon spheres, etc., and porous carbon prepared using this type of template has both micropores, mesopores and macropores, which greatly enhances the electrochemical performance of porous carbon materials (LI Z, XU Z, TAN X, et al. But the template needs to be removed by dangerous chemicals, and the preparation cost of the template is high.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a hierarchical porous carbon material rich in mesopores for a supercapacitor, so as to overcome the defects that in the prior art, the preparation cost of a template agent (such as mesoporous silica foam, silicon spheres and the like) adopted for preparing a porous carbon material is high, dangerous chemicals are required to be removed, and the like.

The invention provides a hierarchical porous carbon material rich in mesopores for a supercapacitor, which is obtained by carrying out hydrothermal reaction on lignin and a sericin solution and then activating the lignin and the sericin solution with an activating agent.

The activating agent comprises potassium hydroxide, potassium citrate, potassium carbonate or potassium bicarbonate.

The mass ratio of the lignin, the sericin and the activator is 40-50: 1-5: 41-165.

The invention also provides a preparation method of the hierarchical porous carbon material rich in mesopores for the supercapacitor, which comprises the following steps:

(1) mixing lignin, sericin and a sulfuric acid solution, carrying out ultrasonic dispersion, and carrying out hydrothermal reaction on the obtained suspension to obtain a product, wherein the concentration of the lignin in the suspension is 40-50 g/L, and the concentration of the sericin is 1-5 g/L;

(2) and (2) washing the product obtained in the step (1) to be neutral, drying, mixing with an activating agent according to the mass ratio of 1: 1-1: 3, carrying out an activation reaction, soaking in a hydrochloric acid solution, washing to be neutral, and carrying out suction filtration to obtain the hierarchical porous carbon material rich in mesopores for the supercapacitor.

In the step (1), the lignin is derived from corn straws.

The lignin comprises enzymatically hydrolyzed lignin or papermaking delignification.

The sericin in the step (1) is obtained by evaporating waste liquid obtained after silk degumming.

The concentration of the sulfuric acid solution in the step (1) is 5-10 wt%.

The ultrasonic dispersion time in the step (1) is 30-60 min.

The hydrothermal reaction temperature in the step (1) is 170-190 ℃, and the hydrothermal reaction time is 16-20 h.

The activating agent in the step (2) comprises potassium hydroxide, potassium citrate, potassium carbonate or potassium bicarbonate.

The activation reaction in the step (2) is as follows: heating to 700-900 ℃ at a heating rate of 1-10 ℃/min and reacting for 1-3 h.

The concentration of the hydrochloric acid solution in the step (2) is 5-10 wt%, and the hydrochloric acid solution is mainly used for removing alkaline substances.

And (3) soaking for 5-10 h in the step (2).

The step (2) of washing water to neutrality and the step of washing water to neutrality are as follows: washing with deionized water for 3-5 times until the pH value is 7.

And (3) drying at the temperature of 80 ℃ in the step (2) until the mass is not changed.

And (3) the suction filtration in the step (2) is reduced pressure suction filtration.

The invention also provides an application of the hierarchical porous carbon material rich in mesopores for the supercapacitor in the supercapacitor, which comprises the following steps: and mixing the graded porous carbon material with acetylene black and PTFE in a mass ratio of 8:1:1, and coating the mixture on a stainless steel mesh to obtain the electrode for the supercapacitor.

According to the invention, sericin is hydrolyzed in a hydrothermal process and then undergoes a crosslinking reaction with lignin, the sericin serves as a novel biological template to promote the formation of mesopores in a subsequent activation process, and the amount of mesopores in the porous carbon material is adjusted by adjusting the addition amount of the sericin, so that the three-dimensional crosslinking graded porous carbon material with abundant mesopores is constructed.

Advantageous effects

(1) The raw materials of the invention have rich sources, low cost and simple process, sericin and lignin are combined into a whole through crosslinking reaction under the conditions of high temperature and high pressure, the invention is safe and environment-friendly, and provides a conversion strategy for high-valued biomass wastes;

(2) the structural regularity and the mesoporous specific surface area of the porous material are controlled by adjusting the addition amount of sericin, so that the high-energy-storage-capacity and excellent rate performance are obtained, the super-capacitor can be applied to assembly of super-capacitors, and the super-capacitor has a wide application prospect in the field of energy storage;

(3) the hierarchical porous carbon material prepared by the method has the advantages of regular structure, clear aperture grading, porous structure on the surface of the material, large capacitance and excellent rate capability after being prepared into an electrode, and the structure is still stable after long-time circulation, thereby meeting the requirement of super capacitor development.

Drawings

FIG. 1 is a graph showing the physical properties of the porous carbon material in example 1, wherein (a) is an SEM electron micrograph of the porous carbon material; (b) is the adsorption isotherm of the porous carbon material; (c) pore size distribution diagram of porous carbon material;

FIG. 2 is a cyclic voltammogram of the electrode for a supercapacitor in example 1 at different sweep rates, where (a) is 5mVs^-1(b) is 100mV s^-1；

FIG. 3 is a graph showing the charge and discharge curves of the electrode for a supercapacitor in example 1 at different current densities, in which (a) is 0.5A g^-1(b) is 10A g^-1。

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.