CN111969190A

CN111969190A - Method for improving sodium storage performance through nitrogen doping and defect-rich nanoshell

Info

Publication number: CN111969190A
Application number: CN202010851899.3A
Authority: CN
Inventors: 封伟; 孔令辰; 李瑀; 彭聪
Original assignee: Tianjin University; Global Energy Interconnection Research Institute; Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
Current assignee: Tianjin University; Global Energy Interconnection Research Institute; Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2020-11-20

Abstract

The invention relates to a method for improving sodium storage performance by nitrogen doping and defect-rich nano shells, which comprises the following steps: 1) mixing phenolic resin serving as a main component with chitosan in water, and performing coating treatment by using the chitosan; 2) heating the blended phenolic resin and chitosan in an inert atmosphere to raise the temperature to 700-1000 ℃; 3) keeping the reaction for a period of time to obtain the product of the N-GCNs coated by the nitrogen-doped nanoshell.

Description

Method for improving sodium storage performance through nitrogen doping and defect-rich nanoshell

Technical Field

The invention relates to a method for storing high-performance sodium by nitrogen doping and defect-rich nano shells, in particular to a method for preparing a hard carbon nano spherical shell with nitrogen doping and defect-rich nano graphitized regions coupled together at a relatively low temperature.

Background

The current human society faces various energy crisis, environmental pollution and other problems, and clean energy such as solar energy, wind energy and the like is too dependent on natural conditions and has the characteristic of instability, and a safe and reliable energy storage system is also needed for the practical application of the clean energy. Electrochemical energy storage plays an important role in the storage and utilization of clean energy, wherein sodium ion batteries are one of the most promising technologies for electrochemical energy storage, and the selection of electrode materials is the key to the research of the sodium ion batteries. At present, one of the main research directions of the sodium ion battery cathode material is a hard carbon material, in order to search for a hard carbon anode material with high specific energy, biomass can be decomposed into the hard carbon material with abundant disordered structures through carbonization, and the carbonization temperature and the carbonization time are important factors influencing the electrochemical performance of the material.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for storing high-performance sodium by doping nitrogen and enriching defect nano shells, which is simple and effective to operate. The prepared hard carbon material shows excellent sodium storage performance, and the invention adopts the following technical scheme:

a method for improving sodium storage performance by nitrogen doping and defect-rich nanoshells, comprising the steps of:

1) mixing phenolic resin serving as a main component with chitosan in water, and performing coating treatment by using the chitosan;

2) heating the blended phenolic resin and chitosan in an inert atmosphere to raise the temperature to 700-1000 ℃;

3) keeping the reaction for a period of time to obtain the product of the N-GCNs coated by the nitrogen-doped nanoshell.

Preferably, the mass ratio of the phenolic resin to the chitosan is 5: and 1, drying the blended phenolic resin and chitosan.

In step 2), the temperature was raised to 850 ℃.

In step 3), the reaction was maintained for 4 hours.

The method needs proper calcination temperature to find the maximum sodium storage performance, and has the advantages of simple operation, low cost, high yield, simple post-treatment and low preparation cost. The sodium storage capacity can be regulated by using nitrogen-doped and defect-rich nanoshells for a high-performance sodium storage method. The sodium storage performance of the obtained N-GCNs materials is different according to different calcination temperatures.

Drawings

FIG. 1 SEM image of N-GCNs-750

FIG. 2 SEM image of N-GCNs-850

FIG. 3 SEM image of N-GCNs-950

FIG. 4 XPS spectra of N-GCNs-750

FIG. 5 XPS spectra of the peak N1s

FIG. 6 charge-discharge test curves of N-GCNs

Detailed Description

The technical solution of the present invention is explained below by specific examples. The various carbon sources used in the examples are commercially available products that can be used.

Example 1

1) Taking phenolic resin as a main component, mixing the phenolic resin with chitosan, and mixing the phenolic resin with the chitosan in a ratio of 5: 1 in deionized water for 6 hours, drying and coating with chitosan.

2) And (3) placing the blended phenolic resin and chitosan into a heating area of a tubular furnace, installing and checking the air tightness of the tubular furnace, and introducing sufficient argon into the tube to remove air in the tubular furnace.

3) The tube furnace was warmed from room temperature to 750 ℃ over 150 minutes.

4) Keeping the reaction time for 4 hours, cooling the hearth to room temperature after the reaction is finished, and taking out the hearth to obtain the product of the phenolic resin (N-GCNs-750) coated by the nitrogen-doped nanoshell.

5) Finally, assembling N-GCNs-750 and sodium metal to obtain a sodium-hard carbon battery, and performing charge and discharge tests, wherein the coulombic efficiency is close to 100%, and the capacity reaches 325.21mAh g^-1And the capacity retention rate reaches 98.21 percent after 100 cycles.

Example 2

3) The tube furnace was warmed from room temperature to 850 ℃ over 150 minutes.

4) Keeping the reaction time for 4 hours, cooling the hearth to room temperature after the reaction is finished, and taking out the hearth to obtain the product of the phenolic resin (N-GCNs-850) coated by the nitrogen-doped nanoshell.

5) Finally, assembling N-GCNs-850 and sodium metal to obtain the sodium-hard carbon battery, and performing discharge test, wherein the coulombic efficiency is close to 100 percent, and the capacity reaches 347.95 mAh.g^-1And the capacity retention rate reaches 99.43% after 100 cycles.

Example 3

3) The tube furnace was warmed from room temperature to 950 ℃ over 150 minutes.

4) Keeping the reaction time for 4 hours, cooling the hearth to room temperature after the reaction is finished, and taking out the hearth to obtain the product of the phenolic resin (N-GCNs-950) coated by the nitrogen-doped nanoshell.

5) And finally, assembling the N-GCNs-950 and sodium metal to obtain the sodium-hard carbon battery, and performing charge and discharge tests, wherein the coulombic efficiency is 62.15%, the capacity reaches 261.17 mAh.g < -1 >, and the capacity retention rate reaches 95.77% after 100 cycles.

Fig. 1 to 3 are SEM images of N-GCNs at different calcination temperatures, from which it can be seen that the 750 degree calcined sample has less wrinkles. As the temperature is increased, the wrinkles begin to increase, and the surface of the N-GCNs calcined at 950 ℃ is not smooth and has more wrinkles. It is shown that the higher the temperature, the more defects are calcined, which has an influence on the sodium storage performance.

Fig. 4 is an XPS spectrum of N-GCNs-950 from which it can be seen that the nitrogen-doped hard carbon material has a distinct N1s peak, which indicates that nitrogen successfully entered the hard carbon material and that a nitrogen-doped hard carbon material was obtained.

Fig. 5 is an XPS spectrum after the peak separation of the N1s peak. After the N1s peak is subjected to peak separation treatment, three nitrogen configurations in graphene are obtained, namely nitrogen of pyridine, pyrrole and graphite, wherein the nitrogen content of graphite is low, and the nitrogen content of pyridine and pyrrole is high. It is shown that the introduction of nitrogen has a great influence on the defects of hard carbon.

As can be seen from FIG. 6, N-GCNs-850 performed best, the coulombic efficiency was close to 100%, the capacity was 347.95mAhg-1, and the capacity retention rate was 99.43% after 100 cycles. N-GCNs-750 are expressed twice, the coulombic efficiency is close to 100%, the capacity reaches 325.21mAhg < -1 >, and the capacity retention rate reaches 98.21% after 100 cycles. The N-GCNs-950 has the worst performance, the coulombic efficiency is 62.15%, the capacity reaches 261.17mAh g < -1 >, and the capacity retention rate reaches 95.77% after 100 cycles.

According to the invention, nitrogen is doped into the hard carbon material, and the chitosan is used for coating the phenolic resin to prepare the hard carbon nano spherical shell with nitrogen doped and defect-rich nano graphitized regions coupled together, so that the material shows excellent sodium storage performance. Due to the introduction of nitrogen doping, carbon configuration is defected, so that the energy storage active sites of hard carbon are increased, and the charge storage capacity of the material is remarkably improved. The excellent electrochemical performance of the material benefits from the unique nano structure of the prepared hard carbon material. The unique nitrogen-doped coupled defect-rich graphitized structure can enhance the charge transfer capability and ion diffusion dynamics of the hard carbon nanoshell, and meanwhile, the special open shell structure can relieve the problem of volume expansion of the material in the ion embedding process.

Claims

1. A method for improving sodium storage performance by nitrogen doping and defect-rich nanoshells, comprising the steps of:

2) and heating the blended phenolic resin and chitosan in an inert atmosphere to raise the temperature to 700-1000 ℃.

2. The method according to claim 1, wherein in the step 1), the mass ratio of the phenolic resin to the chitosan is 5: and 1, drying the blended phenolic resin and chitosan.

3. The method according to claim 1, wherein in step 2), the temperature is raised to 850 ℃.

4. The method as claimed in claim 1, wherein in step 2), the temperature is raised to 700-1000 ℃ within 150 minutes.

5. The method of claim 1, wherein in step 3), the reaction is maintained for 4 hours.