Abstract: The present invention relates to a method of preparing a porous silicon-based negative electrode active material comprising: mixing a porous silica (SiO2) and an aluminum powder; oxidizing all or part of the aluminum powder as an aluminum oxide while at the same time reducing all or part of the porous silica as a porous silicon (Si) by heat-treating a mixture of the porous silica with the aluminum powder, a negative electrode active material, and a rechargeable lithium battery including the same.

Abstract: Provided are a porous silicon-based anode active material including porous SiOx particles (0?x<2) having surfaces coated with an oxide layer, a method of preparing the same, and a lithium secondary battery including the porous silicon-based anode active material. Since the anode active material includes an oxide layer formed on the porous SiOx particles (0?x<2), a reactivity between the anode active material and an electrolyte solution may be reduced and, as a result, an electrical short circuit in an electrode may be minimized. Also, since a plurality of pores is included in surfaces or the surfaces and inside of the SiOx particles, a thickness change rate of the electrode generated during charge and discharge of a secondary battery may be reduced and lifetime characteristics may be improved.

Abstract: The present invention relates to a method for preparing a silicon-based negative electrode active material, a negative electrode active material for a lithium secondary battery, and a lithium secondary battery comprising the same. More particularly, the method for preparing the silicon-based negative electrode active material comprises: preparing a porous silica (SiO2) and a thin metal film; coating the porous silica onto the thin metal film; reducing the porous silica to a porous silicon by performing heat-treatment of the thin metal film and the porous silica; and obtaining the porous silicon.