▎ 摘　　要

NOVELTY - Porous silicon structure includes silicon particles, where a molar ratio (O/Si) of oxygen (O) atoms to silicon (Si) atoms in the porous silicon structure is 0.01-0.35. USE - The porous silicon structure is used for producing a porous silicon-carbon composite which is used for a negative electrode active material for a lithium secondary battery (all claimed). ADVANTAGE - When applied to a negative electrode active material, the porous silicon structure and the porous silicon-carbon composite can have excellent capacity retention and remarkably enhanced discharge capacity and initial efficiency. The porous silicon structure provides improved performance of a secondary battery when applied to the negative electrode active material. The porous silicon-carbon composite provides remarkably improved discharge capacity and initial efficiency while having an excellent capacity retention rate when applied to an anode active material by including the porous silicon structure and carbon. The method has the advantage that mass production is possible through a continuous process with minimized steps. The porous silicon structure is easy to disperse and has excellent mechanical properties such as strength, and when applied to an anode active material, the performance of a secondary battery can be improved. The porous silicon structure has high initial charge/discharge efficiency. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a porous silicon-carbon composite comprising the porous silicon structure and carbon; (2) a method for manufacturing the porous silicon structure, involving (a) etching the silicon-based raw material powder using an etchant containing a fluorine (F) atom-containing compound, and (b) filtering and drying the product obtained by the etching to obtain a porous silicon structure; (3) a method for producing the porous silicon-carbon composite, involving performing steps (a) and (b), and (c1) obtaining a porous silicon-carbon composite by forming a carbon layer on the surface of the porous silicon structure using a chemical thermal decomposition deposition method; and (4) a negative electrode active material for a lithium secondary battery, comprising the porous silicon-carbon composite.