CORE-SHELL CATHODE ACTIVE MATERIALS

A cathode active material including an interior and an exterior coating on the interior, and a total amount of lithium ions is provided. The interior has a layered metal oxide, the exterior coating has a lithium composite oxide having a spinel structure, and the cathode active material is for a rechargeable lithium battery having an upper charging limit voltage of at least 3.5 volt. The layered metal oxide includes about 70% to 90% of the total amount of lithium ions, and the lithium composite oxide includes about 5% to 20% of the total amount of lithium ions. A method of operating a rechargeable lithium battery including the cathode active material wherein a ratio of initial charge capacity of the interior to initial charge capacity of the exterior coating is about 5 to 50 is also provided.