POSITIVE ELECTRODE ACTIVE MATERIAL FOR SECONDARY BATTERY, METHOD OF PREPARING THE SAME, AND LITHIUM SECONDARY BATTERY INCLUDING THE POSITIVE ELECTRODE ACTIVE MATERIAL

The present invention relates to a positive electrode active material for a secondary battery which includes a lithium composite transition metal oxide including Ni, Co, and Mn, wherein the lithium composite transition metal oxide is in the form of a secondary particle, and a glassy coating layer formed on surfaces of particles of the lithium composite transition metal oxide, wherein, in the lithium composite transition metal oxide, an amount of the Ni in a total amount of transition metals is 60 mol% or more, and an amount of the Mn is greater than an amount of the Co, and the glassy coating layer includes a glassy compound represented by Formula 1. [Formula 1] LiaM1bOcwherein in Formula 1, M1 is at least one selected from the group consisting of B, Al, Si, Ti, and P, and 1≤a≤4, 1≤b≤8, and 1≤c≤20.