▎ 摘　　要

NOVELTY - A porous silicon-carbon composite comprises silicon particles, magnesium fluoride, and carbon. USE - Porous silicon-carbon composite is used for negative electrode active material for lithium secondary battery (all claimed) for electronic device, automobiles, and power storage systems. ADVANTAGE - The porous silicon-carbon composite improves charge/discharge capacity, initial charge/discharge efficiency, and capacity retention ratio of the secondary battery. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) production of the porous silicon-carbon composite, which involves obtaining a silicon composite oxide powder using a silicon-based raw material and a magnesium-based raw material, etching the silicon composite oxide powder using an etching solution containing a fluorine-atom-containing compound, filtering and drying the composite obtained by the etching to obtain a porous silicon composite, and forming a carbon layer on the surface of the porous silicon composite by chemical thermal decomposition deposition; and (2) a negative electrode active material, which comprises the porous silicon-carbon composite.