Positive electrode active material for lithium secondary battery, method of preparing same and lithium secondary battery including same

A positive active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including the same. The positive active material has a carbon sheet having a structure including 1 to 200 polycyclic nanosheets, each nanosheet comprising a plurality of hexagonal rings each having six carbon atoms condensed and substantially aligned in a plane containing the hexagonal rings, the polycyclic nanosheets layered in a vertical direction to the plane containing the hexagonal rings; and particles of an olivine-based compound disposed on the surface of the carbon sheet.