Nitrogen-content-adjustable nitrogen-doped carbon-coated nano-silicon composite material and preparation method thereof

Abstract

The invention provides a nitrogen-doped carbon-coated nano-silicon composite material with adjustable nitrogen content and a preparation method thereof. The preparation method comprises the following steps: carrying out hydrolysis reaction on nano-silicon and tetraethoxysilane under the action of ammonia water as a catalyst to synthesize Si@SiO2 particles; dispersing the Si@SiO2 in a hydrochloric acid solution containing aniline and o-phenylenediamine, adding an ammonium persulfate solution to initiate a polymerization reaction, drying an obtained product, and performing high-temperature calcination to form Si-coated SiO2@NC; and etching the Si@SiO2@NC with hydrofluoric acid to form a yolk structure Si@void@NC. The nitrogen doping amount can be adjusted by controlling the relative concentration of the monomer aniline and o-phenylenediamine, the electrochemical performance of the material is further improved, meanwhile, the method has the advantages of being mild in reaction condition, simple in equipment, easy and convenient to operate, safe, reliable and the like, and as the lithium / sodium ion battery negative electrode material, the material has good charge-discharge cycle performance and rate capability.

Description

technical field [0001] The invention relates to the technical field of battery negative electrode material manufacturing, in particular to a preparation method of a nitrogen-doped carbon-coated nano-silicon composite material with adjustable nitrogen content. Background technique [0002] Lithium-ion batteries have been widely used as a portable new energy source in many electronic product fields due to their safety, long service life, and convenience and portability. At present, lithium-ion batteries are developing towards lithium-ion battery materials with high specific capacity, high rate cycle performance and high safety performance. [0003] Anode materials are very important components of lithium-ion batteries, which directly affect the energy density and electrochemical performance of lithium-ion batteries. The theoretical specific capacity of traditional graphite anode materials is 372mAh / g, which cannot meet the requirements of high specific energy lithium-ion batt...

AI Technical Summary

Problems solved by technology

Although these technologies have successfully prepared nitrogen-doped carbon-coated silicon composite materials, and their performance has been improved to a certain extent, in these methods, a single organic compound is selected as the nitrogen source, and the nitrogen doping ratio in the carbon layer is fixed, and the doping amount is low.

It is especially important that the conductivity of the carbon layer is affected by the amount of nitrogen doping, and the wettability of carbon-coated silicon composites with different nitrogen doping ratios in different electrolyte systems and the reactivity of lithium ions are quite different.

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