The positive active material according to one embodiment of the present invention includes a composite metal oxide of the following Formula 1, and a compound being capable of intercalating and deintercalating lithium having the composite metal oxide coated on the surface thereof. M.sub.1-xAlO.sub.2 [Chemical Formula 1] Wherein, in the above Formula 1, M is selected from the group consisting of an alkali metal, an alkaline-earth metal, and combinations thereof, and 0.03.ltoreq.x.ltoreq.0.95. The composite metal oxide increases impregnation of an electrolyte, improves lithium mobility, and decreases internal resistance of a rechargeable lithium battery, and thereby improves discharge capacity and cycle-life characteristics.

The present invention relates to a positive active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery including the same. More particularly, the present invention relates to a positive active material for a rechargeable lithium battery including a compound that can reversibly intercalate/deintercalate lithium and a lithium metal phosphate produced through binding with lithium of the compound, the lithium metal phosphate existing from the surface of the compound to a predetermined depth, a method of preparing the positive active material, and a rechargeable lithium battery having the positive active material. The positive active material can accomplish excellent cycle-life characteristic and also, suppress battery swelling at a high temperature.