Positive electrode active material for secondary battery, manufacturing method thereof, and secondary battery including same

A method for preparing a positive electrode active material for a secondary battery, comprising:

• preparing a lithium transition metal oxide including nickel (Ni) and cobalt (Co), and at least one selected from the group consisting of aluminum (Al), manganese (Mn), and a combination thereof;
• rinsing the lithium transition metal oxide with water to remove lithium impurities present on a surface of the lithium transition metal oxide;
• and
• subjecting the lithium transition metal oxide rinsed with water to a high-temperature heat treatment to form a high-temperature heat treated lithium transition metal oxide, wherein
• the high-temperature heat treatment includes:
• elevating a temperature to an elevated temperature;
• maintaining the elevated temperature;
• and
• cooling,
• wherein an amount of time spent in the elevating the temperature step is 20 to 30% of a total time of the high-temperature heat treatment,
• wherein an amount of time spent in the maintaining step is 40 to 50% of the total time of the high-temperature heat treatment, and
• wherein an amount of time spent in the cooling step is 20 to 30% of the total time of the high-temperature heat treatment.