Silicon-based negative electrode material and preparation method and application thereof

Abstract

The invention relates to a silicon-based negative electrode material and a preparation method and application thereof. The silicon-based negative electrode material comprises a silicon-based inner core and a shell coating the surface of the silicon-based inner core. The shell comprises a first coating material and a second coating material, wherein the first coating material is composed of a compound of nitrogen-doped graphene, a nitrogen-doped hydrogen-containing lithium titanium oxide compound and nitrogen-doped hexagonal phase tungsten oxide, and the second coating material is composed of amesoporous carbon layer. The preparation method comprises the following steps: (1) dispersing a silicon-based material and a first coating material in a solvent to obtain a dispersion liquid, and carrying out spray drying to obtain an inner core material; (2) dispersing a triblock copolymer, amino alcohol and the core material in the step (1) in a solvent to obtain a dispersion liquid; and (3) adding dopamine into the dispersion liquid obtained in the step (3), carrying out a polymerization reaction, and then carbonizing in an inert atmosphere to obtain the silicon-based negative electrode material. The structure and the cycling stability of the silicon-based negative electrode material are obviously improved, and the cycling performance of the silicon-based negative electrode material isalso obviously improved.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and relates to a silicon-based negative electrode material and a preparation method and application thereof. Background technique [0002] Lithium-ion battery has become an ideal portable battery due to its high working voltage, light weight, small self-discharge, long cycle life, no memory effect, no environmental pollution and good safety performance. Si has a high lithium intercalation capacity, up to 4200mAh·g -1 , but in the process of lithium deintercalation of Si, the volume effect is as high as 300%, so that the lattice structure of Si collapses, the Si particles are pulverized, and the active material is separated from the current collector, resulting in a rapid capacity decay during the cycle. This hinders the practical application of Si as the negative electrode of lithium-ion batteries. [0003] CN105118974A discloses a silicon-based negative electrode material, which is a carbo...

AI Technical Summary

Problems solved by technology

Si has a high lithium intercalation capacity, up to 4200mAh·g -1 , but in the process of lithium deintercalation of Si, the volume effect is as high as 300%, so that the lattice structure of Si collapses, the Si particles are pulverized, and the active material is separated from the current collector, resulting in a rapid capacity decay during the cycle. This prevents Si from being put into practical application as the negative electrode of lithium-ion batteries.

[0003] CN105118974A discloses a silicon-based negative electrode material, which is a carbon-coated silicon / carbon nanofiber, which includes: carbon nanofibers loaded with silicon nanoparticles and silicon nanoparticles exposed on the surface of carbon nanofibers The carbon coating layer with secondary protective effect, its preparation method comprises the following steps: (1) Electrospinning: polyacrylonitrile, silicon nanoparticles are mixed and dissolved in N-N dimethylformamide solvent, after stirring and ultrasonic dispersion Obtain uniformly dispersed electrospinning solution, carry out electrospinning with gained electrospinning solution, obtain silicon / polyacrylonitrile nanofiber; (2) carbonization: the silicon / polyacrylonitrile nanofiber of step (1) gained is in air atmosphere (3) impregnation sucrose coating: impregnate the silicon / carbon nanofibers obtained in step (2) into a sucrose solution, and then take them out in the air Dry to obtain sucrose-coated silicon / carbon nanofibers; (4) secondary carbonization: carbonize the sucrose-coated silicon / carbon nanofibers obtained in step (3) in an argon atmosphere to obtain carbon-coated silicon / carbon nanofibers; The preparation process of the method described in this scheme is complicated, and the performance improvement is insufficient

The disadvantage is that LiH is flammable and explosive in contact with water, which has great safety hazards and is not easy to realize large-scale industrial production.

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