▎ 摘　　要

NOVELTY - Negative electrode active material comprises a nanoparticles, and a polymer binder surrounding at least one of the nanoparticles comprising a core comprising silicon, a first shell formed on the surface of the core and including silicon oxide, and a second shell formed on a surface of the first shell and comprising carbon. USE - The negative electrode active material is useful for lithium secondary battery. ADVANTAGE - The negative electrode active material adopts the polymer binder which is made of two or more polymers crosslinked, so that expansion and contraction are freely possible, so that can serve as a smart ball that can help the silicon to shrink to original shape after expansion when a voltage is applied by applying the material for the lithium secondary battery, and the characteristics of the lithium secondary battery are reversible, so that the coulombic efficiency, periodicity, charge/discharge rate, shelf-life can be improved, and helps to maintain electrical contact between the core, first shell, and second shell, and prevents breakage and detachment due to excessive expansion. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for manufacturing the negative electrode active material, involving (a) drying the silicon core particles, (b) oxidizing the silicon core particles under an oxidizing agent to form a first shell including silicon oxide on the silicon core particles, (c) mixing and pulverizing the particles on which the first shell is formed with a carbon source to form a second shell including carbon on the surface of the first shell, (d) preparing a mixture by mixing the particles on which the second shell is formed with a polymer binder, (e) pressing and heating the mixture, and (f) pulverizing the pressurized and heat-treated mixture.