▎ 摘　　要

NOVELTY - Cathode active material comprises carbon-based particles including pores; a silicon-containing coating layer formed inside the pores of the carbon-based particles or on the surfaces of the carbon-based particles; and a carbon coating layer formed on the silicon-containing coating layer, where the full width at half maximum (FWHM) of the O1s peak of the surface measured through X-ray photoelectron spectroscopy (XPS) is 2 or more, and XPS Si2p peak area ratio defined by equation as speciifed is 15% or less. The carbon-based particles include activated carbon, carbon nanotubes, carbon nanowires, graphene, carbon fibers, carbon black, graphite, porous carbon, pyrolyzed material of cryogel, pyrolyzed material of zero gel, and/or pyrolyzed material of airgel. The silicon-containing coating layer contains silicon oxide (SiOx) (x is 0-2) and silicon carbide. The carbon coating layer comprises carbon and/or a conductive polymer. USE - The cathode active material is useful for lithium secondary battery (claimed) as a power source for portable electronic communication devices e.g. camcorders, mobile phones, and notebook PCs according to the development of information communication and display industries and eco-friendly vehicle e.g. an electric vehicle, and nickel-cadmium battery and a nickel-hydrogen battery. ADVANTAGE - The cathode active material prevents cracks due to a difference in volume expansion rates between carbon and silicon during charging and discharging of the secondary battery, and the contact between the silicon of the cathode active material and moisture in the atmosphere or contact between the silicone and water in the cathode slurry; suppresses a decrease in the discharge capacity and capacity efficiency of the secondary battery for a period of time from the preparation of the cathode active material to the formation of the cathode, and the reaction of silicon and water on the surface of the cathode active material, and the conversion of silicon to silicon dioxide in the cathode active material, and thus improves the discharge capacity and capacity efficiency of the secondary battery. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing cathode active material.