A composite anode active material including: a silicon material and a coating layer formed on at least a portion of a surface of the silicon material, wherein the coating layer is chemically bonded to the silicon material, and wherein the coating layer includes a hydrosilylation product of a C4-C30 alkene having a terminal —C(═O)OR group, wherein R is a hydrogen, a C1-C5 alkyl group, a C2-C6 heteroalkyl group, a C6-C12 aryl group, or a C7-C13 arylalkyl group, each of which except hydrogen is substituted or unsubstituted.