Negative electrode active material for non-aqueous electrolyte rechargeable battery, method for preparing same, and non-aqueous rechargeable battery including same

1. A negative electrode active material for a non-aqueous electrolyte rechargeable battery, comprising a silicon oxide composite, the silicon oxide composite containing i) silicon, ii) a silicon oxide represented by general formula SiO x (0<x<2), and iii) an oxide including silicon and Mg,

wherein the silicon oxide composite exhibits at least one diffraction peak in each of the ranges of 27° to 32° and 21° to 23.5°, in the X-ray diffraction analysis, and

wherein there is no peak by SiO 2 in the X-ray diffraction analysis.

2. The negative electrode active material of claim 1 , wherein the oxide including silicon and M is Mg 2 SiO 4 .

3. The negative electrode active material of claim 1 , wherein, in the X-ray diffraction analysis of the silicon oxide composite, the range of the relative ratio between the intensity of a diffraction peak belonging to Si (111), I Si(111) , and the intensity of a diffraction peak belonging to Mg 2 SiO 4 (120), I Mg2SiO4(120) , is 0<I Mg2SiO4(120) /I Si(111) <1.0.

4. The negative electrode active material of claim 1 , wherein the size of silicon crystals contained in the silicon oxide composite, which is determined by Scherrer equation on the basis of the full width at half maximum (FWHM) of the diffraction peak of Si (111) in the X-ray diffraction analysis, is 1-50 nm.

5. The negative electrode active material of claim 1 , wherein the average particle diameter (D 50 ) of the silicon oxide composite is 0.1-20 μm.

6. The negative electrode active material of claim 1 , wherein the specific surface area of the silicon oxide composite is 1-50 m 2 /g.

7. The negative electrode active material of claim 1 , further comprising a coating layer or deposition layer containing a carbon-based material on a surface of the silicon oxide composite.

8. The negative electrode active material of claim 7 , wherein the content of the carbon-based material is 1-20 parts by weight on the basis of 100 parts by weight of the silicon oxide composite.

9. A negative electrode active material for a non-aqueous electrolyte rechargeable battery, comprising a silicon oxide composite, the silicon oxide composite containing i) silicon, ii) a silicon oxide represented by general formula SiO x (0<x<2), and iii) an oxide including silicon and Mg,

wherein the silicon oxide composite exhibits at least one diffraction peak in each of the ranges of 27° to 32° and 21° to 23.5°, in the X-ray diffraction analysis, and

wherein there is no peak by SiO 2 in the X-ray diffraction analysis;

wherein the negative electrode active material is manufactured by the method comprising:

(i) simultaneously injecting a silicon oxide powder and Mg into a reactor, the silicon oxide powder being obtained by mixing silicon and silicon dioxide (SiO 2 ) powders to have a mole ratio of 1:0.5 to 1:1.5, the mole ratio of the silicon and Mg being 1:0.01 to 1:1;

(ii) heating the silicon oxide powder and Mg at 1,000-1,800° C., followed by cooling at 500-900° C., to precipitate a silicon oxide composite; and

(iii) pulverizing the precipitated silicon oxide composite to an average particle diameter of 0.1-20 μm.