CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY

摘要

The present invention relates to a cathode active material for lithium secondary battery, which is a lithium transition metal oxide of a-NaFeO2 layered crystal structure, wherein the transition metal includes mixed transition metals of Ni and Mn. The cathode active material satisfies the conditions that the average oxidation number of total transition metals except for lithium is greater than +3, and m(Ni) = m(Mn), wherein m(Ni) and m(Mn) stand for mole of manganese and nickel respectively. Contrary to the prior art, the cathode active material adjusts the oxidation state of transition metals to greater than +3, and thus forms a more uniform and stable layered structure, wherein the transition metals are in the transition metal oxide layer and form layered structure. Accordingly, the overall electrochemical properties including the battery capacity can be improved and especially, the high charge and discharge rate property is excellent.