A preparation method of nanocrystalline silicon-silicon oxide-carbon composite powder

Abstract

The invention relates to a preparation method of nanocrystalline silicon-silicon oxide-carbon composite powder with high purity, uniform and controllable particle size, and surface passivation. Specifically, the present invention uses commercially available high-purity silicon powder and silicon dioxide powder as raw materials (purity: >99.9%, particle size: 50-800 mesh), and silicon powder and silicon dioxide powder are mixed under vacuum or atmosphere protection. Grind to nanometer size (1‑100nm), then mix the two powders in a certain proportion and then conduct high-temperature high-energy ball milling under the protection of the atmosphere. During the ball milling process, add a carbon source to passivate the surface of the powder to obtain a high-efficiency powder. Pure, particle size controlled, surface passivated nanocrystalline silicon-silicon oxide-carbon composite powder. The invention has the advantages of simple process, low cost and good repeatability, and the prepared silicon-based composite material has excellent performances such as many charge and discharge times and low expansion rate, and can be widely used in the fields of optoelectronic information and nanotechnology.

Description

technical field [0001] The invention relates to a method for preparing nanocrystalline silicon-silicon oxide-carbon composite powder, belongs to the technical field of nanomaterial preparation, and can be applied to fields such as optoelectronic information and nanotechnology. Background technique [0002] In recent years, silicon-based low-dimensional nanomaterials have achieved rapid development in the field of optoelectronic device applications, and have been successfully applied to non-volatile memories and lithium-ion batteries. Due to the advantages of high specific energy, high working voltage, good safety, and low environmental pollution, lithium-ion batteries have broad application prospects in various portable electronic devices and electric vehicles. In recent years, with the increasing demand for high-energy power sources, a lot of research has been carried out on how to develop lithium-ion batteries with high energy density, fast and high-power charge and discha...

AI Technical Summary

Problems solved by technology

Among these methods, C has the most extensive and in-depth research on Si-C composite materials due to its good stability, low price, various preparation methods, good conductivity and ability to accommodate the volume expansion of Si. The value is 372mAh / g, which is much smaller than the capacity value of silicon material 4212mAh / g, which cannot meet the requirements of high energy density lithium-ion batteries. During low-temperature charging, the phenomenon of "lithium precipitation" is prone to occur, which leads to potential safety hazards; at the same time, research on lithium-ion battery anode materials has found that common silicon-oxygen compounds include SiO 0.8 , SiO, SiO 1.1 etc., the conductivity of silicon oxide is slightly inferior to that of nano-silicon powder, and its irreversible capacity is relatively large, but Li 2 The expansion of the O system is small, which can effectively alleviate the pulverization of the negative electrode and improve the cycle performance of the battery. Therefore, another technical route in the existing research is to use silicon oxide as the negative electrode material of lithium-ion batteries.

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