POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE, AND RECHARGEABLE LITHIUM BATTERIES

A positive electrode active material includes: a first positive electrode active material including a lithium nickel-manganese composite oxide having a nickel content of at least about 60 mol% based on a total metal excluding lithium and being in a form of secondary particles each including a plurality of primary particles; and a second positive electrode active material including a lithium nickel-manganese-based composite oxide having a nickel content of at least about 60 mol% based on a total metal excluding lithium and being in a form of single particles and a coating layer on the surface of the single particle and containing aluminium and yttrium, an aluminium content of the coating layer being about 0.1 mol% to about 2 mol% and an yttrium content of the coating layer being about 0.1 mol% to about 1 mol%, based on a total metal excluding lithium in the second positive electrode active material.