Silicon-based active material particles for secondary battery and method for producing same

1. A method for preparing silicon-based active material particles, the method comprising:

a step of providing silicon powder;

a step of providing a pre-pulverization mixture, in which the silicon powder is dispersed in a solvent for dispersion selected from the group consisting of water, deionized water, an alcoholic solvent, and a mixture of two or more thereof, the solvent further comprising an antioxidant;

a step of applying mechanical compression and shear stress to the silicon powder of the pre-pulverization mixture to granulate the silicon powder, thereby forming a resulting product comprising silicon particles comprising a chemical silicon oxide layer formed on a core of a silicon particle by the solvent comprising the antioxidant, the silicon particles having an oxygen content controlled by the antioxidant; and

a step of drying the resulting product comprising the silicon particles to remove the solvent comprising the antioxidant and obtain silicon-based active material particles.

2. The method of claim 1 , wherein the antioxidant is selected from the group consisting of alpha lipoic acid, octene, propyl gallate, tocopherol, glutathione, butyl hydroxyanisole, butylated hydroxytoluene, tertiary butyl hydroquinone, nordihydroguaiaretic acid, sesamol, vitamin E, vitamin C, and quercetin.

3. The method of claim 1 , wherein the antioxidant is used in an amount of 1 wt % to 10 wt % relative to the weight of the silicon powder.

4. The method of claim 1 , wherein the solvent for dispersion comprises the alcoholic solvent and the alcoholic solvent comprises a member selected from the group consisting of ethyl alcohol, methyl alcohol, glycerol, propylene glycol, isopropyl alcohol, isobutyl alcohol, polyvinyl alcohol, cyclohexanol, octyl alcohol, decanol, hexadecanol, ethylene glycol, 1,2-octanediol, 1,2-dodecanediol, and 1,2-hexadecanediol, and mixtures thereof.

5. The method of claim 1 , wherein the step of applying mechanical compression and shear stress is achieved by grinding, which performs pressing and abrasion while supplying the pre-pulverization mixture between a spinning abrasive plate and a fixed plate.

6. The method of claim 1 , wherein the method further comprises:

a step of mixing the resulting product comprising the silicon particles and a carbon precursor solvent to form a dispersion solution;

a step of forming solid secondary particles, in which the silicon particles are dispersed within a carbon precursor matrix from the dispersion solution; and

a step of heat treating the solid secondary particles to carbonize the carbon precursor matrix, thereby forming silicon-based secondary active material particles.

7. The method of claim 1 wherein, in the silicon-based active material particles, an oxygen content relative to a total weight of the cores of silicon particles and the chemical silicon oxide layers is limited to a range of 5 wt % to 15 wt % or 6 wt % to 10 wt %.

8. The method of claim 1 , wherein the core of a silicon particle has a low crystallinity or is amorphous.

9. The method of claim 1 , wherein an average particle diameter of the silicon-based active material particles is in the range of 30 nm to 300 nm or 30 nm to 200 nm.

10. The method of claim 1 , wherein, in the silicon-based active material particles, an oxygen content relative to a total weight of the cores of silicon particles and the chemical silicon oxide layers is limited to a range of 6 wt % to 10 wt %.