Lithium complex oxide for lithium secondary battery positive active material and method of preparing the same

A lithium complex oxide secondary particle formed by coagulation of a plurality of primary particles, wherein Co concentration at a boundary of the primary particle is higher than Co concentration in an internal part of the primary particle,

• wherein the secondary particle has a bound energy (P1) of spin-orbit-spit 2p3/2 peak and a bound energy (P2) of 2p1/2 peak in a Co 2p core-level spectrometry obtained through XPS measurement,
• wherein the P1 and the P2 are ranged respectively in 779 eV≤P1≤780 eV and 794 eV≤P2≤795 eV, and
• wherein a primary particle located at a surface part of the secondary particle has a Co concentration gradient reduced by 0.05 to 0.07 mol % per nm toward a center of the primary particle from a surface of the primary particle.