▎ 摘　　要

NOVELTY - Negative electrode active material comprises a silicon-carbon composite comprising silicon nanoparticles and a carbon matrix, and can have a degree of oxidation of 10.5% or less. USE - The negative electrode active material for a lithium secondary battery, is used in a negative electrode for a lithium secondary battery (claimed). ADVANTAGE - The active material has characteristics capable of improving the electrochemical performance of a battery while using a silicon-based negative electrode material. The active material has excellent electrochemical performance, and has excellent structural stability and high capacity, is possible to have reversible charging/discharging without cracking, and has a long lifespan-low expansion characteristic. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a method of preparing the negative electrode active material, involving pulverizing the silicon raw material to obtain silicon nanoparticles, mixing the silicon nanoparticles and crystalline carbon to obtain a silicon-crystalline carbon precursor, binding the silicon-crystalline carbon precursor with a first amorphous carbon precursor, and carbonizing the silicon-crystalline carbon precursor and the first amorphous carbon precursor mixture to obtain a silicon-carbon composite, where the silicon raw material has an X-ray diffraction angle (2theta) using copper K alpha on the (111) plane with a half width of 0.2 degrees or more; and (2) a lithium secondary battery comprising a negative electrode comprising the above-mentioned negative electrode active material, positive electrode, and electrolytes.