Negative active material, lithium battery including the negative active material, and method of preparing the negative active material

A negative active material, comprising:

• a plurality of core particles, each core particle comprising a silicon based alloy,
• wherein the silicon based alloy comprises
• an inactive matrix consisting of inactive silicon and at least one selected from the group consisting of group 2 to 14 metal elements other than silicon, and
• a plurality of active silicon nanoparticles dispersed in the inactive matrix;
• amorphous carbon nanoparticles on a surface of the core particle, the amorphous carbon nanoparticles having an average particle diameter of about 10 nm or more and less than 100 nm;
• and
• an amorphous carbonaceous coating layer on at least a portion of the surface of the core particle, the amorphous carbonaceous coating layer covering the amorphous carbon nanoparticles,
• wherein the amorphous carbonaceous coating layer surrounds the surface of the core particle and covers the amorphous carbon nanoparticles, and
• wherein an average particle diameter of the core particle is greater than an average particle diameter of the amorphous carbon nanoparticles, the core particle being greater in amount than that of the amorphous carbon nanoparticles in combination with the amorphous carbonaceous coating layer.