The present invention relates to a lithium cobalt positive electrode active material, apreparation method thereof, a positive electrode and a secondary battery 10including the same, and more specifically, to a lithium cobalt positive electrode active materialhaving excellent cycle properties even during a high-voltage driving of 4.45 V or higher, a preparation method thereof, a positive electrode and a secondary battery including the same.15BACKGROUND ART[0002]As technology development and demand for mobile devices have increased, the demand for secondary batteries as an energy source has been rapidly increased. Among such 20secondary batteries, lithium secondary batteries having high energy density and voltage, long cycle life, and low self-discharging rate have been commercialized and widely used.[0003]One example of positive electrode active materialsfor a lithium secondary battery which has been actively 25
2developed and used is LiCoO2of a layered structure. LiCoO2is most widely used since the synthesis thereof is easily achieved and the electrochemical performance thereof, including lifespan properties, is excellent. However, due to the poor structural stability thereof, there is a limitation 5in applying LiCoO2to a high capacity battery technology.[0004]Therefore, a technology of improving the structural stability of a lithium cobalt oxide by coatinganoxide ofa metal such as Al, Zr, and the like on the surface of a lithium cobalt oxide particle has been proposed. A lithium 10cobalt oxide coated with a metal oxide as described above exhibited excellent electrochemical performance in a battery having a driving voltage of less than 4.45 V. However, according to the studies of the present inventors, when a lithium cobalt oxide coated with a metal oxide is applied to 15a battery having a driving voltage of less than 4.45 V, the cycle properties are rapidly deteriorated.[0005]Therefore, there has been a demand for developing a lithium cobalt positive electrode active materialwhich is excellent in cycle properties even when applied to high 20voltage.DISCLOSURE OF THE INVENTIONTECHNICAL PROBLEM[0006]The present invention is made for solving the above-25
3mentioned problems, and it aims to provide a lithium cobalt positive electrode active materialwhich exhibits excellent cycle propertiesin a case ofbeing driven at a high voltage of 4.45 V or higher.5TECHNICAL SOLUTION[0007]According to an aspect of the present invention, there is provided a lithium cobalt positive electrode active materialincluding sodium and calcium, wherein the total amount of the sodium and calcium is 150 ppm to 500 ppm based 10on the total weight of the lithium cobalt positive electrode active material. [0008]At this time, the sodium and calcium may be included in lithium sites. [0009]Specifically, the lithium cobalt positive electrode 15active materialmay be represented by Formula 1 below.[0010][Formula 1]Li1-xM1xCo1-yM2yO2[0011]In Formula 1, M1includes Na and Ca, M2is one or more selected from the group consisting of Al, Mg, W, Mo, Zr, 20Ti, Fe, V, Cr, Ba, Ca, and Nb, and 0