阅读说明：本技术 基于甲基纤维素的b,n双掺杂碳气凝胶及其制备方法和在电化学储能领域的应用 (B, N double-doped carbon aerogel based on methyl cellulose, preparation method thereof and application thereof in electrochemical energy storage field ) 是由 许鑫华 贾丽敏 张茜 郑丽婷 马绍帅 于 2018-06-15 设计创作，主要内容包括：本发明公开了基于甲基纤维素的B,N双掺杂碳气凝胶及其制备方法和在电化学储能领域的应用。甲基纤维素由于分子链上的大量羟基与水分子形成氢键作用,从而在没有交联剂存在作用下,可形成自交联的水凝胶。该水凝胶经过干燥,碳化,得到具有三维多孔网络结构的碳气凝胶材料,掺杂剂硼酸铵溶液作为甲基纤维素的良好溶剂,使得掺杂过程简便,并且更易于调控杂原子的掺杂量,从而得到性能优异的电极材料。本发明制备的B,N双掺杂碳气凝胶材料,可有效提高碳材料的比表面积和导电性,同时阻止了材料的粉化和团聚,是一种极具应用前景的超级电容器电极材料。(The invention discloses a B, N double-doped carbon aerogel based on methyl cellulose, a preparation method thereof and application thereof in the field of electrochemical energy storage. The methyl cellulose can form self-crosslinking hydrogel under the condition of no existence of a crosslinking agent because a large number of hydroxyl groups on a molecular chain and water molecules form hydrogen bond action. The hydrogel is dried and carbonized to obtain the carbon aerogel material with a three-dimensional porous network structure, and the ammonium borate solution serving as a dopant is used as a good solvent of the methyl cellulose, so that the doping process is simple and convenient, and the doping amount of the heteroatom is easier to regulate and control, thereby obtaining the electrode material with excellent performance. The B and N double-doped carbon aerogel material prepared by the method can effectively improve the specific surface area and the conductivity of the carbon material, simultaneously prevents the pulverization and the agglomeration of the material, and is a super capacitor electrode material with a great application prospect.)

1. The B and N double-doped carbon aerogel based on methyl cellulose is characterized in that a carbon aerogel material is double-doped by using boron and nitrogen, the methyl cellulose is dissolved in an ammonium borate aqueous solution and uniformly dispersed, the methyl cellulose is transferred into a container and sealed by using a preservative film, ageing is carried out at room temperature and gelation change is carried out, then freeze drying is carried out to obtain aerogel, high-temperature carbonization treatment is carried out on the aerogel in inert protective gas to realize double-doping of the carbon aerogel by using the boron and the nitrogen, the carbon aerogel is heated to 500-600 ℃ from the room temperature of 20-25 ℃ at the heating rate of 1-3 ℃ per minute for heat preservation treatment for 1-5 hours, then the carbon aerogel is heated to 1000-1200 ℃ at the heating rate of 1-5 ℃ per minute for heat preservation treatment for 1-5 hours, and then the carbon aerogel is naturally cooled to the room temperature of 20-25 ℃.

2. The methylcellulose-based B, N double-doped carbon aerogel according to claim 1, wherein the aging and gelation change are carried out at room temperature of 20 to 25 ℃ for 1 to 5 days and 24 hours per day.

3. The methylcellulose-based B, N double-doped carbon aerogel according to claim 1, wherein the freeze-drying is carried out at a temperature of-10 to-30 ℃ for 10 to 30 hours, preferably at a temperature of-15 to-25 ℃ for 15 to 25 hours.

4. The methylcellulose-based B, N double-doped carbon aerogel according to claim 1, wherein the high-temperature carbonization treatment process comprises the following steps: heating from room temperature of 20-25 ℃ to 500-550 ℃ at a heating rate of 1-3 ℃ per minute, carrying out heat preservation treatment for 1-3 h, heating to 1000-1100 ℃ at a heating rate of 1-5 ℃ per minute, keeping the temperature for 1-3 h, and naturally cooling to room temperature of 20-25 ℃.

5. The preparation method of the B, N double-doped carbon aerogel based on the methyl cellulose is characterized by comprising the following steps of:

dissolving methylcellulose in an ammonium borate aqueous solution, uniformly dispersing, transferring the solution into a container, sealing the container by using a preservative film, aging the container at room temperature and carrying out gelation change, then freeze-drying the container to obtain aerogel, carrying out high-temperature carbonization treatment on the aerogel in inert protective gas to realize double doping of carbon aerogel by elements of boron and nitrogen, heating the carbon aerogel from the room temperature of 20-25 ℃ at the heating rate of 1-3 ℃ per minute to the temperature of 500-600 ℃ for heat preservation treatment for 1-5 h, heating the carbon aerogel to the temperature of 1000-1200 ℃ at the heating rate of 1-5 ℃ per minute for 1-5 h, and then naturally cooling the carbon aerogel at the room temperature of 20-25 ℃.

6. The method of claim 5, wherein the aging is carried out at room temperature of 20-25 ℃ for a period of 1-5 days and 24 hours per day; the inert protective gas is nitrogen, helium or argon; dissolving methyl cellulose in ammonium borate water solution and stirring at 60-90 deg.c and 100-500 rpm.

7. The method for preparing B, N double-doped carbon aerogel based on methylcellulose according to claim 5, wherein the freeze-drying is performed at a temperature of-10 to-30 ℃ for 10 to 30 hours, preferably at a temperature of-15 to-25 ℃ for 15 to 25 hours.

8. The preparation method of B, N double-doped carbon aerogel based on methyl cellulose according to claim 5, wherein the high-temperature carbonization treatment process comprises the following steps: heating from room temperature of 20-25 ℃ to 500-550 ℃ at a heating rate of 1-3 ℃ per minute, carrying out heat preservation treatment for 1-3 h, heating to 1000-1100 ℃ at a heating rate of 1-5 ℃ per minute, keeping the temperature for 1-3 h, and naturally cooling to room temperature of 20-25 ℃.

9. The process for preparing B, N double-doped carbon aerogel based on methylcellulose according to claim 5, characterized in that, in the aqueous solution of ammonium borate, the concentration of ammonium borate is 0.05mol/L to 0.2mol/L, preferably 0.1 to 0.2 mol/L; dissolving methyl cellulose in ammonium borate water solution, wherein the mass percent of the methyl cellulose is 1-10%, and preferably 3% -8%.

10. Use of a methylcellulose-based B, N double-doped carbon aerogel according to one of claims 1 to 4 or obtained according to the preparation process of one of claims 5 to 9 in the field of electrochemical energy storage, characterized in that the elemental B and N double-doped carbon gel material has a high electron conductivity and a low electrical resistance.

Technical Field

The invention belongs to the field of novel functional material preparation and electrochemical energy storage, and particularly relates to a B and N co-doped carbon aerogel material prepared based on methylcellulose aerogel, which is prepared by preparing the cellulose aerogel from a large amount of hydroxyl groups on a methylcellulose molecular chain and unique water solubility and gelling characteristics of the hydroxyl groups, and preparing the carbon aerogel through a doping agent and a carbonization process.

Background

The super capacitor is a novel green energy storage device, has higher power density than a lithium ion battery, has wide application range, is safe and easy to maintain, and the like, and thus has wide attention in the field of new energy. At present, along with the continuous development of electronic devices, the demand on energy storage materials is higher and higher, and the caused environmental problems are more and more serious. The emission of pollutants and the release of toxic substances need to be reduced from a material preparation source, and the cellulose aerogel is widely used as third-generation aerogel due to the environment-friendly characteristic in the fields of heat insulation, sound absorption materials and the like, but is still in the starting stage in the aspect of electrode materials, so that the cellulose aerogel is widely concerned.

There are many limiting factors affecting the use of supercapacitor materials in industrial processes, where environmental reasons and cost are the first factors to consider. The ideal electrode material needs to have higher specific capacity and good stability, and the carbon material becomes the most concerned electrode material in the industrial process and is also the most deeply researched material. Cellulose aerogels offer great environmental and cost advantages over phenolic aerogels, but undoped carbon aerogels require improvement in both conductivity and capacity. The methyl cellulose has good water solubility, so that a urea/sodium hydroxide mixed solvent can be avoided in the gel preparation process, and the environment friendliness is greatly improved. A large amount of hydroxyl on a molecular chain can well form hydrogen bond interaction with water molecules and initiate supermolecule self-assembly, so that self-crosslinking hydrogel is formed. Reports on cellulose-based carbon aerogels are becoming hot, but improvements in material properties and preparation processes are still needed. In order to meet the industrial demand, more and more researchers propose carbonizing various biomasses and natural polymer materials to prepare carbon materials. On one hand, the carbon sources have rich reserves and wide sources, and on the other hand, the environmental pressure generated in the preparation process is small, thereby meeting the requirements of green industry. In order to obtain a carbon material with excellent performance, the electrode material with pseudo capacitance is prepared by compounding the carbon material with metal oxide or conductive polymer, and the method with more application prospect is to improve the specific surface area of the carbon material and carry out doping. By doping the heteroatom into the carbon network, the defect degree of the carbon material can be improved, so that the conductivity and the specific capacity are improved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a B, N double-doped carbon aerogel based on methyl cellulose, a preparation method thereof and application thereof in the field of electrochemical energy storage, namely, the invention combines the advantages of rich porous structure and large specific surface area of a carbon aerogel material to prepare a heteroatom-doped carbon material, namely, the B, N double-doped carbon aerogel material with industrial production prospect and excellent electrochemical performance.

The technical purpose of the invention is realized by the following technical scheme:

b and N double-doped carbon aerogel based on methyl cellulose, double-doping a carbon aerogel material by using element boron and nitrogen, dissolving methyl cellulose in an ammonium borate aqueous solution, uniformly dispersing, transferring the methyl cellulose into a container, sealing the container by using a preservative film, aging the container at room temperature to generate gelation change, then freeze-drying the container to obtain aerogel, then performing high-temperature carbonization treatment on the aerogel in inert protective gas to realize double-doping of the carbon aerogel by using the element boron and the nitrogen, heating the aerogel to 500-600 ℃ from the room temperature of 20-25 ℃ at the heating rate of 1-3 ℃ per minute, performing heat preservation treatment for 1-5 hours, heating the aerogel to 1000-1200 ℃ at the heating rate of 1-5 ℃ per minute, keeping the aerogel for 1-5 hours, and then naturally cooling the room temperature to 20-25 ℃.

The preparation method of the B, N double-doped carbon aerogel is carried out according to the following steps:

dissolving methylcellulose in an ammonium borate aqueous solution, uniformly dispersing, transferring the solution into a container, sealing the container by using a preservative film, aging the container at room temperature and carrying out gelation change, then freeze-drying the container to obtain aerogel, carrying out high-temperature carbonization treatment on the aerogel in inert protective gas to realize double doping of carbon aerogel by elements of boron and nitrogen, heating the carbon aerogel from the room temperature of 20-25 ℃ at the heating rate of 1-3 ℃ per minute to the temperature of 500-600 ℃ for heat preservation treatment for 1-5 h, heating the carbon aerogel to the temperature of 1000-1200 ℃ at the heating rate of 1-5 ℃ per minute for 1-5 h, and then naturally cooling the carbon aerogel at the room temperature of 20-25 ℃.

In the technical scheme, the room temperature is 20-25 ℃, the time for aging and generating gelation change is 1-5 days, and 24 hours are taken every day.

In the above technical scheme, the inert protective gas is nitrogen, helium or argon.

In the technical scheme, the carbon aerogel material doped with the elements B and N is obtained by washing and drying after high-temperature treatment.

In the technical scheme, the methyl cellulose is dissolved in the ammonium borate water solution and stirred at the temperature of 60-90 ℃, and the stirring speed is 100-500 revolutions per minute.

In the technical scheme, the temperature is minus 10 to minus 30 ℃ and the time is 10 to 30 hours when freeze drying is carried out, and the preferable temperature is minus 15 to minus 25 ℃ and the time is 15 to 25 hours.

In the technical scheme, the high-temperature carbonization treatment process comprises the following steps: heating from room temperature of 20-25 ℃ to 500-550 ℃ at a heating rate of 1-3 ℃ per minute, carrying out heat preservation treatment for 1-3 h, heating to 1000-1100 ℃ at a heating rate of 1-5 ℃ per minute, keeping the temperature for 1-3 h, and naturally cooling to room temperature of 20-25 ℃.

In the above technical solution, the concentration of ammonium borate in the aqueous solution of ammonium borate is 0.05mol/L to 0.2mol/L, preferably 0.1mol/L to 0.2 mol/L.

In the technical scheme, the methyl cellulose is dissolved in an ammonium borate water solution, and the mass percent of the methyl cellulose is 1-10%, preferably 3-8%.

The B, N double-doped carbon aerogel based on the methyl cellulose is applied to the field of electrochemical energy storage, namely the B and N double-doped carbon aerogel material has higher electronic conductivity and lower resistance, namely the double doping of the B and N elements improves the conductivity of the material.

The B, N double-doped carbon aerogel based on methyl cellulose is applied to the field of electrochemical energy storage, 1mol/L aqueous solution of sodium sulfate is used as electrolyte, the carbon aerogel, PVDF binder, conductive carbon black and N-methyl pyrrolidone are prepared into slurry, the slurry is coated on a current collector, and the current collector is dried and pressed into tablets to test electrochemical performance.

According to the technical scheme, the cellulose aerogel is prepared by a one-step sol-gel method, and a three-dimensional network structure is formed by interaction among molecular chains. In the carbonization process, B and N heteroatoms are doped into the carbon skeleton to cause defects, so that the conductivity of the carbon material is improved. And the aerogel material has rich porous structure and large specific surface area, so that the contact between the active material and the electrolyte can be effectively improved, and the electrochemical performance is greatly improved. Meanwhile, the stable carbon skeleton greatly improves the stability of the material.

Drawings

FIG. 1 is a schematic flow chart of the preparation of the B, N double-doped carbon aerogel material in the invention.

Fig. 2 is a graph showing the adsorption and desorption curves of the B, N double-doped carbon aerogel material prepared in example 1 of the present invention.

Fig. 3 is a raman spectrum of different materials prepared in example 2 of the present invention.

FIG. 4 is a graph of electrochemical performance tests of different B, N double-doped carbon aerogel materials prepared in example 2 of the present invention, wherein (a) constant current charge-discharge curves are shown, curve 1 is 0BN-MC, curve 2 is 0.05BN-MC, curve 3 is 0.1BN-MC, and curve 4 is 0.15 BN-MC; (b) the cyclic voltammogram has a curve 1 of 0BN-MC, a curve 2 of 0.05BN-MC, a curve 3 of 0.1BN-MC and a curve 4 of 0.15 BN-MC.

Fig. 5 is an X-ray photoelectron spectrum (XPS) of the B, N double-doped carbon aerogel material prepared in example 3 of the present invention.

Detailed Description

The technical solution of the present invention will be further described with reference to the following specific examples, wherein the methyl cellulose in the experiment is methyl cellulose M450 (imported from England for Biochemical industries).