▎ 摘　　要

NOVELTY - Silicon-silicon oxide-carbon composite having a core-shell structure comprises core comprising silicon fine particles, silicon oxide compound (I) and magnesium silicate, and shell formed of a carbon film, where the silicon-silicon oxide-carbon composite has an electrical conductivity of 0.5-10 S/cm. USE - The silicon-silicon oxide-carbon composite is used for negative electrode active material for lithium secondary battery (claimed). ADVANTAGE - The silicon-silicon oxide-carbon composite improves capacity of the secondary battery and cycle characteristics and initial efficiency when used as negative active material of the secondary battery. DETAILED DESCRIPTION - Silicon-silicon oxide-carbon composite having a core-shell structure comprises core comprising silicon fine particles, silicon oxide compound of formula (I): SiOx and magnesium silicate, and shell formed of a carbon film, where the silicon-silicon oxide-carbon composite has an electrical conductivity of 0.5-10 S/cm. x = 0-2. INDEPENDENT CLAIMS are included for the following: (1) a negative electrode active material for a lithium secondary battery comprising the silicon-silicon oxide-carbon composite; and (2) a method for producing the silicon-silicon oxide-carbon composite having core-shell structure, which involves (i) mixing silicon and silicon dioxide to obtain a silicon-silicon oxide mixture, (ii) evaporating and depositing the silicon-silicon oxide mixture and metallic magnesium to obtain a silicon-silicon oxide composite, (iii) cooling the silicon-silicon oxide composite, (iv) crushing the cooled silicon-silicon oxide composite to obtain a core, and forming a shell on the core by covering the surface of the crushed silicon-silicon oxide composite with carbon, where the electrical conductivity is 0.5-10 S/cm.