▎ 摘　　要

NOVELTY - A silicon-silicon composite oxide-carbon composite comprises a core-shell structure comprising a core comprising silicon, a silicon oxide compound, and magnesium silicate, and a shell comprising a carbon layer. When the particle sizes at which the cumulative volume concentration (%) in the particle size distribution (D10) is 10%, (D50) is 50%, and (D90) is 90%. The composite has a span value of ratio of the difference of the D90 and D10 with respect to the D50 of 0.6-1.5. USE - Silicon-silicon composite oxide-carbon composite used for active material for negative electrode of lithium secondary battery (all claimed) used as power source for electronic device, automobile and power storage system. ADVANTAGE - The silicon-silicon composite oxide-carbon composite has improved capacity, and excellent cycle characteristics and initial efficiency. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) manufacture of silicon-silicon composite oxide-carbon composite, which involves (s1) preparing a raw material obtained by using a silicon powder and a silicon oxide (SiOx, where x is 0.5-2) powder, (s2) heating and evaporating the raw material and the metallic magnesium at different temperatures, followed by deposition and cooling to obtain a silicon-silicon composite oxide composite of the core, (s3) pulverizing and classifying the silicon-silicon composite oxide composite to have an average particle diameter of 0.5-10 mu m to obtain a silicon-silicon composite oxide composite powder, (s4) obtaining a composite containing a core-shell structure by forming a carbon layer on the surface of the silicon-silicon composite oxide composite powder by using a chemical thermal decomposition deposition method, and (s5) performing at least one process of pulverizing and classifying the composite of the core-shell structure; and (2) a negative electrode active material, which comprises the silicon-silicon composite oxide-carbon composite.