Production method of high-purity nanocrystalline silicon

Abstract

The invention discloses a production method of high-purity nanocrystalline silicon, which comprises the following steps: 1) pretreating a waste silicon material and / or byproduct silicon powder to obtain 10-50 [mu]m silicon powder; (2) adding the silicon powder in the step (1) into dispersion liquid according to the proportion of 5-30wt% of solid content, then adding 1-10wt% of dispersing agent, and performing stirring in a dispersing tank to form silicon powder slurry; 3) pumping the silicon powder slurry formed in the step 2) into a sand mill for grinding to obtain nanocrystalline silicon slurry with the average particle size of 20-30 nm; and 4) conveying the nanocrystalline silicon slurry obtained in the step 3) to a spray drying system to obtain the nano-porous crystalline silicon particles. According to the invention, low-cost large-scale production is realized, the stability, purity and granularity of the nanocrystalline silicon are effectively controlled, the morphology of the produced nano-porous crystalline silicon particles is adjustable, the internal pores of the nano-porous crystalline silicon particles are nano communicating pores, the volume expansion of the silicon iseffectively relieved, and the electrical properties of the silicon negative electrode are also remarkably improved.

Description

technical field [0001] The invention relates to a method for producing nanocrystalline silicon, in particular to a method for producing high-purity nanocrystalline silicon, and belongs to the technical field of high-purity nanocrystalline silicon preparation. Background technique [0002] At present, the negative electrode material of lithium-ion batteries generally adopts the traditional graphite negative electrode. In the fully intercalated state (LiC 6 ), the corresponding capacity is only 372mAh / g. With the development of technology, the actual theoretical energy density of the commercialization of traditional graphite negative electrodes has reached 360mAh / g, which is close to the theoretical energy density, and there is no room for improvement. Studies have found that silicon can be alloyed with lithium at room temperature to form Li 4.4 Si phase, the theoretical specific capacity is as high as 4200mAh / g, so silicon anode materials have attracted the attention of re...

AI Technical Summary

Problems solved by technology

[0008] Aiming at the problems of high cost, low purity, poor stability, and difficulty in industrialized production of the existing nanocrystalline silicon preparation technology, the present invention provides a production method of high-purity nanocrystalline silicon, which can effectively control the purity, particle size and Stability, realizing low-cost mass production, and the morphology of the produced porous nanocrystalline silicon particles is flexible and adjustable

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