Positive active material for rechargeable, method of preparing same, and rechargeable lithium battery comprising same

PURPOSE: A positive electrode active material, a manufacturing method thereof, and a lithium secondary battery including thereof are provided to simplify synthesis method and improve conductivity, thermal stability, and high rate property. CONSTITUTION: A positive electrode active material is composed of 200 nm -1 micron sized particle which is represented by chemical formula 1: Li_aMn_(1-x)M_xPO_4. The particle has 5-10nm thickness of carbon coating layer on surface. In the chemical formula 1, M is a mixture of more than one or two which are selected from Mg, Fe, Co, Cr, Ti, Ni, Cu, Zn, Zr, Nb and Mo. a is 0.9 to 1.1, and x is larger than or equal to 0 and smaller than 0.5. A lithium secondary battery includes a positive electrode which includes anode active material, a negative electrode which includes cathode active material, and non-aqueous electrolyte.