CATHODE ACTIVE MATERIAL, AND CATHODE AND LITHIUM SECONDARY BATTERY COMPRISING SAME

The present invention relates to a positive electrode active material including a lithium composite transition metal oxide in the form of a single particle composed of one nodule or a pseudo-single particle, which is a composite of 30 or fewer nodules, and a coating layer including a first coating layer formed on the surface of the lithium composite transition metal oxide and a second coating layer formed on the surface of the first coating layer, wherein the lithium composite transition metal oxide has a roundness, which is defined by Equation 1 below, of 0.50 to 0.68, and the second coating layer contains boron, wherein the boron is included in a weight of 300 ppm to 2400 ppm based on the total weight of the positive electrode active material. Roundness=4×Area/π×R2In Equation 1 above, R denotes the length of a major axis passing through the center of the lithium composite transition metal oxide, and Area denotes an actual area of the lithium composite transition metal oxide.