Silicon-based anode active material and secondary battery comprising the same

1. A silicon-based anode active material particle having a center portion of the particle and a center-periphery portion of the particle, the particle comprising:

a silicon phase; a SiO x (0<x<2) phase; and a silicon dioxide phase wherein the silicon dioxide phase is dispersed in the SiO x phase and comprises cristoballite,

wherein the concentration of the silicon dioxide phase is higher in the center-periphery portion than in the center portion,

wherein the concentration of the silicon phase is higher in the center portion than in the center-periphery portion.

2. The silicon-based anode active material particle of claim 1 , wherein the silicon dioxide phase is crystalline.

3. The silicon-based anode active material particle of claim 1 , wherein the SiO x is silicon monoxide.

4. The silicon-based anode active material particle of claim 1 , wherein the silicon dioxide phase is present in an amount of 2-50 wt % based on the weight of the silicon-based anode active material particle.

5. The silicon-based anode active material particle of claim 1 , wherein the silicon phase and the silicon dioxide phase are formed by disproportionation of SiO x (0<x<2).

6. The silicon-based anode active material particle of claim 1 , further comprising a carbon coating material.

7. A secondary battery, which comprises a cathode comprising a cathode active material, an anode comprising an anode active material, and a separator, wherein the anode active material comprises the silicon-based anode active material particle of claim 1 .