Preparation method of nitrogen-doped silicon/carbon core-shell structure lithium-ion battery negative electrode material

Abstract

The invention provides a preparation method of a nitrogen-doped silicon / carbon core-shell structure lithium-ion battery negative electrode material. The preparation method comprises the following steps: dissolving a nitrogen-containing substance and polyacrylonitrile into an N,N-dimethylformamide solvent to obtain sheath liquid; dissolving nano silicon powder and polyvinylpyrrolidone into the N,N-dimethylformamide solvent to obtain core liquid; putting injection syringes filled with the core liquid and the sheath liquid on two injection pumps of an electrostatic spinning device respectively and carrying out coaxial electrostatic electric spinning; collecting precursor fibers sprayed by the electric spinning on a rolling shaft; putting the obtained precursor fibers into an air atmosphere muffle furnace and carrying out pre-oxidization; then carbonizing under a protection atmosphere of inert gas and at the carbonization temperature of 700 to 1000 DEG C, so as to obtain a nitrogen-doped inner carbon net communicated silicon@carbon / carbon nano-fiber core-shell structure lithium-ion battery negative electrode material. The nitrogen-doped silicon / carbon core-shell structure lithium-ion battery negative electrode material obtained by the method provided by the invention has the characteristics of high capacity and good circulating stability.

Description

technical field [0001] The invention belongs to the field of materials science, and relates to a lithium ion battery negative electrode material, in particular to a preparation method of a nitrogen-doped silicon / carbon core-shell structure lithium ion battery negative electrode material. Background technique [0002] Lithium-ion batteries feature high energy density, low self-discharge rate, and high energy conversion efficiency, making them a power source for a variety of commodities. At present, lithium-ion batteries have been extended from being used in portable electronic devices to being used in electric (or hybrid) vehicles, etc. Accordingly, the demand for lithium-ion batteries with higher capacity and good cycle performance is also becoming higher and higher. [0003] As an important part of lithium-ion batteries, anode materials directly restrict the electrochemical performance of lithium-ion batteries. However, the commercial lithium-ion battery anode material gra...

AI Technical Summary

Problems solved by technology

[0004] Among all negative electrode materials, silicon has the highest theoretical specific capacity (4200mAh / g), which is an ideal negative electrode material, but the large volume expansion (about 300%) of silicon-based negative electrode materials during charge and discharge causes electrode powdering, Conductive network breakage, resulting in a rapid drop in capacity

For this reason, carbon-coated silicon electrode materials have been rapidly developed, but during cycling, the volume expansion of silicon will cause the carbon layer to crack, resulting in a decrease in capacity.

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