Positive Electrode Active Material, Method for Producing the Same, and Positive Electrode and Lithium Secondary Battery Including the Same

A positive electrode active material includes a lithium nickel-based oxide having the content of nickel (Ni) ranging from about 50 mol % to 70 mol % among total transition metals, and a coating layer formed on a surface of the lithium nickel-based oxide and including cobalt (Co) and lithium (Li). The coating layer has a form including both dot-shaped and film-shaped phases, and the weight ratio of lithium (Li) to cobalt (Co) in the positive electrode active material ranges from about 5 to 20.