Silicon-based negative active material, preparing method of preparing same and rechargeable lithium battery including same

Abstract

A silicon-based negative active material that includes a core including silicon oxide represented by SiO(0<x<2); and a coating layer including metal oxide, and the metal of the metal oxide includes aluminum (Al), titanium (Ti), cobalt (Co), magnesium (Mg), calcium (Ca), potassium (K), sodium (Na), boron (B), strontium (Sr), barium (Ba), manganese (Mn), nickel (Ni), vanadium (V), iron (Fe), copper (Cu), phosphorus (P), scandium (Sc), zirconium (Zr), niobium (Nb), chromium (Cr), and/or molybdenum (Mo), the core has a concentration gradient where an atom % concentration of a silicon (Si) element decreases to the center of the core, and an atom % concentration of an oxygen (O) element increases to the center, and a depth from the surface contacting the coating layer where a concentration of the silicon (Si) element is about 55 atom % corresponds to about 2% to about 20% of a diameter of the core.