Nitrogen-doped carbon-coated graphite composite material as well as preparation method and application thereof

Abstract

The invention provides a nitrogen-doped carbon-coated graphite composite material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a graphite material with a nitrogen-containing compound to obtain a graphite-nitrogen mixture; (2) carrying out heat treatment on the graphite-nitrogen mixture to obtain a graphite phase C3N4 coated graphite material; and (3) mixing the graphite phase C3N4 coated graphite material with a coating agent to obtain a mixture, and carrying out heat treatment on the mixture to obtain the nitrogen-doped carbon coated graphite composite material. The nitrogen doping content of the nitrogen-doped carbon-coated graphite composite material is high, the nitrogen-doped carbon-coated graphite composite material has an effective induced deposition effect on lithium metal deposition in a fast charging process, and a proper pore structure is formed in a coating layer, so that the transmission characteristic of lithium ions and the deposition characteristic of lithium can be improved; a battery taking the nitrogen-doped carbon-coated graphite composite material as a negative electrode material is excellent in fast charge performance, high in discharge capacity and easy for industrial mass production.

Description

technical field [0001] The invention belongs to the technical field of carbon materials, and in particular relates to a nitrogen-doped carbon-coated graphite composite material and a preparation method and application thereof. Background technique [0002] With the continuous development of the new energy industry, especially the global attention to the new energy automobile industry, people's requirements for the electrochemical performance of lithium-ion batteries are also increasing, especially in the fast charging of lithium-ion batteries. The fast charging performance of the battery has high requirements on the material. The theoretical capacity of the traditional graphite material is only 372mAh / g, which can no longer meet the growing needs of people. Therefore, it is of great significance to develop a new type of fast charging graphite material. . [0003] In order to improve the lithium storage performance of graphite materials, and then improve the rate performance...

AI Technical Summary

Problems solved by technology

[0004] CN103050661A discloses a graphene composite lithium-ion battery negative electrode material and a preparation method thereof. The negative electrode material includes multilayer graphene sheets, and a hollow nanometer negative electrode particle layer is arranged between adjacent graphene sheets, and the graphene sheets will The hollow nano-anode particles are half-enclosed and spaced apart one by one, and there are gaps between adjacent graphene sheets; the hollow nano-anode particles are composed of a carbon outer layer and a hollow metal anode material inner layer, and the prepared graphene anode material has conductivity. Good performance, large electrochemical lithium storage capacity, high energy density, and good cycle performance, etc., but this process is relatively complicated, and graphene, carbon nanotubes, etc. are expensive and costly, and it is difficult to use them in large quantities in industrialization

However, this nitrogen doping method will lead to low nitrogen content in the material, and in the case of high-rate charging and discharging, it cannot ensure the uniform distribution of lithium dendrites on the surface of the carbon material, which is not conducive to the improvement of the battery rate performance.

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