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Nitrogen-doped hollow-structure graphite microsphere, composite negative electrode material and preparation method thereof

A negative electrode material, nitrogen doping technology, applied in the direction of negative electrode, structural parts, nanotechnology for materials and surface science, etc., can solve the problems of SEI film rupture, low Coulombic efficiency, material pulverization, etc., and achieve low cost , The preparation process is simple, and the effect of improving the rate performance

Pending Publication Date: 2021-11-12
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there are also serious volume expansion during charging and discharging, which leads to the continuous rupture and reformation of the SEI film, and the pulverization of materials, etc.
Silicon oxide material, although its theoretical capacity is smaller than that of pure silicon, it will generate Li during charging and discharging. 2 O and Li 4 SiO 4 , these inactive phases can well suppress the volume expansion effect of the material, but at the same time, the inactive phase will also consume part of the lithium, and there is a problem of low first Coulombic efficiency

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  • Nitrogen-doped hollow-structure graphite microsphere, composite negative electrode material and preparation method thereof
  • Nitrogen-doped hollow-structure graphite microsphere, composite negative electrode material and preparation method thereof

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preparation example Construction

[0021] The invention provides a method for preparing a nitrogen-doped hollow graphite microsphere negative electrode material, which comprises:

[0022] In the first step, the surfactant and the nitrogen-containing organic matter are dissolved in the dispersion medium to obtain a solution;

[0023] In the second step, the ultrafine graphite powder is dispersed in the solution prepared in the first step, stirred evenly, and ultrasonically treated to obtain a uniform slurry;

[0024] The third step is spray drying and granulation to obtain powder materials;

[0025] The fourth step, optionally, the powder material obtained in the third step is fully mixed with the coating material;

[0026] The fifth step, carbonization treatment;

[0027] The sixth step, cooling treatment, is prepared.

[0028] The dispersion medium in the first step is water and ethanol, and the volume ratio of water and absolute ethanol is 1:(0-0.3).

[0029] The surfactant is one or more mixtures of poly...

Embodiment 1

[0060] Dissolve the surfactant PVP accounting for 0.5% of the mass of ultrafine graphite and the melamine accounting for 2% of the mass of ultrafine graphite in a mixed solution in which the ratio of water and absolute ethanol is 4:1, and disperse 2g of ultrafine graphite powder in the above solution , stirring and ultrasonic treatment for 10-120min, the obtained homogeneous slurry is atomized, dried and granulated on a spray dryer to obtain a powder material, and the powder material is placed in a tube furnace for carbonization treatment under an argon atmosphere. The treatment temperature is 100-400°C, the heat treatment is 1-3 hours, and the carbonization is 2-5 hours at a high temperature of 600-1000°C. The obtained nitrogen-doped hollow graphite ball negative electrode material ( figure 1 ), and conductive carbon black, CMC and SBR are uniformly mixed in deionized water at a mass ratio of 8:1:0.5:0.5 to make a slurry, coated with copper foil, and after drying, rolling and...

Embodiment 2

[0062] Dissolve the surfactant PVP accounting for 0.5% of the ultrafine graphite mass and the melamine accounting for 15% of the ultrafine graphite mass in a mixed solution of water and ethanol, the ratio of water and absolute ethanol is 4:1, and disperse the ultrafine graphite powder In the above solution, carry out stirring and ultrasonic treatment for 10-120 minutes, and the obtained uniform slurry is atomized, dried and granulated on a spray dryer to obtain a powder material, and the powder material and asphalt are fully mixed, and placed in a tube Carbonization treatment under argon atmosphere in a type furnace, treatment temperature 100-400 ° C, heat treatment 1-3 hours, high temperature 600-1000 ° C, carbonization 2-5 hours. The obtained nitrogen-doped hollow graphite ball negative electrode material is uniformly mixed with conductive carbon black, CMC and SBR in deionized water at a mass ratio of 8:1:0.5:0.5 to make a slurry, coated on a copper foil, and subjected to A...

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Abstract

The invention discloses a nitrogen-doped hollow-structure graphite microsphere negative electrode material and a nitrogen-doped hollow silicon / silicon monoxide / graphite composite negative electrode material, the hollow graphite microspheres are adopted, and the internal superfine graphite sheets have a random orientation so that the problem that lithium ion diffusion is blocked in the charging and discharging process can be reduced, electrolyte permeation is facilitated, an electrochemical kinetics process is promoted, meanwhile, the hollow structure can relieve the expansion stress of the graphite sheets in the charge-discharge process and provide a required space for the volume expansion of silicon. And nano silicon is converted into silicon monoxide so that the expansion effect of the material is further relieved. The nitrogen-doped carbon layer can improve the conductivity of the material, prevent a side reaction between an electrolyte and an active material, improve the first coulombic efficiency of the material and maintain the structural stability of the material.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery materials, in particular to a nitrogen-doped hollow graphite microsphere anode material, a nitrogen-doped hollow silicon / silicon oxide / graphite composite anode material and a preparation method thereof. Background technique [0002] Compared with traditional secondary batteries such as lead-acid, nickel-cadmium, and nickel-metal hydride, lithium-ion batteries are widely used in mobile phones, notebook computers and other digital aspects due to their high energy density, long cycle life, and no memory effect. With the rapid development of electric vehicles, aerospace and other fields, higher requirements are placed on the performance of lithium-ion batteries. One of the key factors that determine the performance of lithium-ion batteries is the anode material of lithium-ion batteries. Common negative electrode materials for lithium-ion batteries include graphite materials, amorphous car...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/48H01M4/587H01M4/62B82Y30/00B82Y40/00
CPCH01M4/362H01M4/628H01M4/625H01M4/386H01M4/483H01M4/587B82Y30/00B82Y40/00H01M2004/021H01M2004/027Y02E60/10
Inventor 黄正宏展长振吕瑞涛康飞宇
Owner TSINGHUA UNIV
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