阅读说明：本技术 一种具有较高质量比电容的碳化硅制备方法 (Preparation method of silicon carbide with high mass specific capacitance ) 是由 侯新梅 杨涛 刘世纯 王恩会 陈俊红 李斌 于 2019-10-24 设计创作，主要内容包括：本发明提供了一种具有较高质量比电容的碳化硅制备方法,其步骤包括：将研磨后的碳硅化铝湿法球磨处理,得碳硅化铝料浆；将所述碳硅化铝料浆干燥处理,得碳硅化铝粉末；向所述碳硅化铝粉末中加入浓度为20-40％的氢氟酸,在隔绝空气条件下水浴加热至30-70℃,搅拌反应36-48h得反应混合液；将所述反应混合液离心处理,对得到的沉淀洗涤、过滤,再将滤出的固相干燥处理,得到碳化硅粉末材料。本发明提供的一种具有较高质量比电容的碳化硅制备方法,反应所需温度低,制得的碳化硅电化学性能优良。(The invention provides a preparation method of silicon carbide with high mass specific capacitance, which comprises the following steps: performing wet ball milling treatment on the ground carbon aluminum silicide to obtain carbon aluminum silicide slurry; drying the carbon silicon aluminum slurry to obtain carbon silicon aluminum powder; adding 20-40% hydrofluoric acid into the carbon-silicon aluminum powder, heating the mixture to 30-70 ℃ in a water bath under the air isolation condition, and stirring the mixture for reacting for 36-48h to obtain a reaction mixed solution; and centrifuging the reaction mixed solution, washing and filtering the obtained precipitate, and drying the filtered solid phase to obtain the silicon carbide powder material. The preparation method of the silicon carbide with higher mass specific capacitance provided by the invention has the advantages that the reaction temperature is low, and the prepared silicon carbide has excellent electrochemical performance.)

1. A preparation method of silicon carbide with high mass specific capacitance is characterized by comprising the following steps:

performing wet ball milling treatment on the ground carbon aluminum silicide to obtain carbon aluminum silicide slurry;

drying the carbon silicon aluminum slurry to obtain carbon silicon aluminum powder;

adding 20-40% hydrofluoric acid into the carbon-silicon aluminum powder, heating the mixture to 30-70 ℃ in a water bath under the air isolation condition, and stirring the mixture for reacting for 36-48h to obtain a reaction mixed solution;

and centrifuging the reaction mixed solution, and drying the separated solid phase to obtain the silicon carbide powder material.

2. The method for preparing silicon carbide with high specific mass capacitance according to claim 1, wherein: the amount of the hydrofluoric acid with the concentration of 20-40% added into the carbon-containing aluminum silicate powder is 10ml of the hydrofluoric acid with the concentration of 20-40% added into each 0.5-1g of the carbon-containing aluminum silicate powder.

3. The method for preparing silicon carbide with high specific mass capacitance according to claim 1, wherein: when the grinded aluminum carbo-silicate is subjected to wet ball milling treatment, ethanol is used as a medium for ball milling, and the ball milling time is 8-10 h.

4. The method for preparing silicon carbide with high specific mass capacitance according to claim 1, wherein: the grain size of the aluminum carbo-silicate powder is 400-600 um.

5. The method for preparing silicon carbide with high specific mass capacitance according to claim 1, wherein the centrifugal treatment method comprises the following steps: centrifuging the reaction mixture, adding ethanol into the separated solid, washing to obtain suspension, centrifuging the obtained suspension, adding ethanol into the separated solid, washing to obtain suspension, and repeating the steps until the pH value of the obtained suspension is 6-7.

6. The method for preparing silicon carbide with high specific mass capacitance according to claim 5, wherein: the rotation speed of the centrifuge during the centrifugation is 5000-.

7. The method for preparing silicon carbide with high specific mass capacitance according to claim 1, wherein: the solid phase separated by filtration is dried in an oven at the temperature of 70-90 ℃ for 8-12 h.

8. The method for preparing silicon carbide with higher specific mass capacitance according to any one of claims 1 to 7, wherein: the mass specific capacitance of the silicon carbide is 100-120/g.

Technical Field

The invention relates to the technical field of inorganic nonmetallic materials, in particular to a preparation method of silicon carbide with high mass specific capacitance.

Background

The super capacitor is used as an efficient, green and environment-friendly chemical power supply, and is widely applied to the fields of aerospace, network communication, transportation and the like due to the superior performances of large capacity, high power, long service life, no pollution and the like. In the research of the super capacitor, the performance of the electrode material directly determines the energy storage characteristic of the super capacitor, so how to develop the electrode material with high specific capacitance has important application value and theoretical significance. The silicon carbide material as a semiconductor material has the characteristics of wide band gap, low density, corrosion resistance, good chemical stability, large heat conductivity and the like, and can be used as an electrode material of a super capacitor.

The existing synthesis methods of silicon carbide materials include physical vapor deposition, chemical deposition, carbothermic reduction, hydrothermal synthesis, template methods and the like. However, the above methods all have two inherent disadvantages: firstly, the synthesis requires high temperature of thousands of ℃ to cause danger in the synthesis process, poor controllability, high energy consumption and large equipment investment; secondly, the product has poor uniformity and quality is difficult to control. Therefore, in order to solve the above problems, development of a new silicon carbide synthesis method is currently in demand.

Disclosure of Invention

The invention aims to provide a method for preparing silicon carbide with high mass specific capacitance, which has low temperature required by reaction and excellent electrochemical performance.

In order to solve the technical problems, the invention provides a preparation method of silicon carbide with higher mass specific capacitance, which comprises the following steps:

performing wet ball milling treatment on the ground carbon aluminum silicide to obtain carbon aluminum silicide slurry;

drying the carbon silicon aluminum slurry to obtain carbon silicon aluminum powder;

adding 20-40% hydrofluoric acid into the carbon-silicon aluminum powder, heating the mixture to 30-70 ℃ in a water bath under the air isolation condition, and stirring the mixture for reacting for 36-48h to obtain a reaction mixed solution;

and centrifuging the reaction mixed solution, washing and filtering the obtained precipitate, and drying the filtered solid phase to obtain the silicon carbide powder material.

Further, the amount of the hydrofluoric acid added to the carbon-silicon aluminum powder at a concentration of 20-40% is 10ml of hydrofluoric acid at a concentration of 20-40% per 0.5-1g of the carbon-silicon aluminum powder.

Further, when the grinded aluminum silicon carbide is subjected to wet ball milling treatment, a medium adopted by ball milling is ethanol, and the ball milling time is 8-10 hours.

Further, the grain size of the aluminum carbo-silicate powder is 400-600 um.

Further, the centrifugal processing method comprises the following steps: centrifuging the reaction mixture, adding ethanol into the separated solid, washing to obtain suspension, centrifuging the obtained suspension, adding ethanol into the separated solid, washing to obtain suspension, and repeating the steps until the pH value of the obtained suspension is 6-7.

Further, the rotation speed of the centrifuge during the centrifugation is 5000-9000 rpm.

Further, the solid phase separated by filtration is dried in an oven at the temperature of 70-90 ℃ for 8-12 h.

Further, the mass specific capacitance of the silicon carbide is 120/g-100.

According to the preparation method of the silicon carbide with the high mass specific capacitance, provided by the invention, a wet etching method is adopted, and hydrofluoric acid with the concentration of 20-40% is used for etching and dealuminating the silicon carbide powder at the lower temperature of 30-70 ℃, so that the hexagonal crystal silicon carbide material with a stable structure and excellent electrochemical performance can be prepared. The preparation method of the silicon carbide provided by the invention has the advantages of low requirement on reaction temperature, simple preparation process, low requirement on required equipment, high preparation efficiency, and low preparation cost and high economic benefit, and the preparation rate of the silicon carbide produced by each unit mass of the aluminum carbo-silicide can reach 40-70%. In addition, the silicon carbide material prepared by the preparation method provided by the invention has stable performance and can be used in acidic and alkaline electrolytes, the prepared silicon carbide material is used for modifying the surfaces of glassy carbon electrodes, titanium sheet electrodes and the like to manufacture super capacitors, and higher mass specific capacitance can be obtained, and the mass specific capacitance can reach 100-120F/g when the sweep rate is 5-20mV/s in a three-electrode system.

Drawings

FIG. 1 is a flow chart of a method for preparing silicon carbide with high specific capacitance;

fig. 2 is an XRD chart of the silicon carbide material prepared by the method for preparing silicon carbide with higher specific capacitance in example 1 of the present invention;

FIG. 3 is an SEM image of a silicon carbide material prepared by the method for preparing silicon carbide with higher specific mass capacitance provided by embodiment 1 of the invention;

fig. 4 is a CV curve of a glassy carbon electrode modified by silicon carbide powder prepared by the method for preparing silicon carbide with higher mass-to-capacitance ratio provided in embodiment 1 of the present invention;

fig. 5 is an XRD chart of the silicon carbide material prepared by the method for preparing silicon carbide with higher specific capacitance in example 2 of the present invention;

FIG. 6 is an SEM image of a silicon carbide material prepared by the method for preparing silicon carbide with higher specific mass capacitance provided by embodiment 2 of the invention;

fig. 7 is a CV curve of a glassy carbon electrode modified by silicon carbide powder prepared by the method for preparing silicon carbide with higher mass-to-capacitance ratio provided in embodiment 2 of the present invention;

fig. 8 is an XRD chart of the silicon carbide material prepared by the method for preparing silicon carbide with higher specific capacitance according to example 3 of the present invention;

FIG. 9 is an SEM image of a silicon carbide material prepared by the method for preparing silicon carbide with higher specific mass capacitance provided by embodiment 3 of the invention;

fig. 10 is a CV curve of a glassy carbon electrode modified by silicon carbide powder prepared by the method for preparing silicon carbide with higher mass-to-capacitance provided in embodiment 3 of the present invention.

Detailed Description

Referring to fig. 1, a method for preparing silicon carbide with high specific capacitance by using an embodiment of the present invention includes the following steps:

raw material treatment: grinding industrially prepared carbon-silicon aluminum into fine powder, then carrying out wet ball milling treatment on the carbon-silicon aluminum fine powder obtained by grinding, wherein a ball milling medium adopts ethanol, the ball milling time is 8-10h, so as to obtain carbon-silicon aluminum slurry, and finally drying the slurry, so as to obtain the carbon-silicon aluminum powder with the particle size of 400-600 mu m.

Dealuminizing by a chemical etching method: and taking the carbon-silicon aluminum powder prepared in the step, and adding 20-40% hydrofluoric acid into the carbon-silicon aluminum powder, wherein the amount of the 20-40% hydrofluoric acid added into the carbon-silicon aluminum powder is 10ml of 20-40% hydrofluoric acid added into each 0.5-1g of the carbon-silicon aluminum powder. And then sealing the mixture of the carbon-silicon aluminum powder and the hydrofluoric acid, putting the mixture into a constant-temperature water bath heating device, heating the mixture to 30-70 ℃, and then starting an electromagnetic stirrer to stir and react for 36-48h to obtain a reaction mixed solution.

Centrifugal drying: centrifuging the reaction mixture, adding ethanol into the separated solid, washing to obtain suspension, centrifuging the obtained suspension, adding ethanol into the separated solid, washing to obtain suspension, and repeating the steps for 4-6 times until the pH value of the obtained suspension is 6-7. Wherein the rotation speed of the centrifuge at the time of the centrifugal separation is 5000-. And (3) putting the separated solid phase into an oven to be dried for 8-12h at the temperature of 70-90 ℃ to obtain the silicon carbide powder material.

The silicon carbide powder material prepared by the method is used for modifying a glassy carbon electrode, a three-electrode method is used for detecting a super capacitor, an electrolyte is 2mol/L KCl solution, cyclic volt-ampere tests are respectively carried out at different scanning rates, and constant current charge and discharge tests are carried out at different current densities. The sweep rate range of the cyclic voltammetry test is 5mV/s-200mV/s, and when the sweep rate is 5-20mV/s, the mass specific capacitance is measured to be 120F/g. Therefore, according to the preparation method of the silicon carbide with the higher mass specific capacitance, provided by the invention, under the condition of a lower temperature of 30-70 ℃, the prepared silicon carbide powder has more excellent performance in the application field of the pure silicon carbide super capacitor, and the mass specific capacitance of the silicon carbide powder can reach the order of magnitude of that of a silicon carbide composite material. In addition, according to the preparation method of the silicon carbide with the higher mass specific capacitance, the preparation rate of the silicon carbide powder produced by the aluminum carbo-silicide of each unit mass can reach 40% -70%, the preparation yield is high, and therefore the cost can be reduced, and the economic benefit is improved.

The following provides a specific description of a method for preparing silicon carbide with high specific capacitance by using specific examples.