CATHODE ACTIVE MATERIAL, PREPARATION METHOD THEREOF, AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

摘要

The present invention relates to a cathode active material, a preparation method thereof, and a lithium secondary battery comprising the same. The cathode active material comprises: a lithium transition metal oxide; and a coating layer on a surface of the lithium transition metal oxide. The coating layer contains a lithium boron oxide, and phosphorylated lithium. The cathode active material according to an embodiment of the present invention can greatly improve cycle properties of a lithium secondary battery since the generation of HF which can be generated due to side reaction between an electrolyte and moisture generated during charging the discharging the battery can be suppressed by reducing lithium impurities existing on a lithium transition metal oxide, and forming a coating layer on the lithium transition metal oxide. In addition, the method for preparing a cathode active material according to an embodiment of the present invention can ameliorate a high-temperature performance degradation phenomenon of a secondary battery and can suppress increase of resistance since each surface process can be conducted under optimal temperature conditions in accordance with the use of a phosphorus-containing compound and a boron containing compound by performing a two-step thermal treatment process.