Lithium complex oxide for lithium secondary battery positive active material and method of preparing the same
Disclosed is a lithium complex oxide and method of manufacturing the same, more particularly, a lithium complex oxide effective in improving the characteristics of capacity, resistance, and lifetime with reduced residual lithium and with different interplanar distances of crystalline structure between a primary particle locating in a internal part of secondary particle and a primary particle locating on the surface part of the secondary particle, and a method of preparing the same.
1. A lithium complex oxide secondary particle formed by coagulation of a plurality of primary particles, comprising:
a graded Co concentration part on a surface of the secondary particle;
an uniform Co concentration part in an inner side of the surface; and
wherein the secondary particle has at least one peak generated from LiCoO 2 during XRD analysis,
wherein a thickness of the graded Co concentration part is 50 to 150 nm,
wherein the secondary particle has a ratio of peak intensity (I531) around 531 eV and peak intensity (I528) around 528.5 eV during an O 1s core-level spectrometry that is obtained through XPS measurement, and
wherein the ratio is I531/I528≤2.
2. The lithium complex oxide secondary particle of claim 1 , wherein Co concentration is graded in 0.05 to 0.07 mol % per one nm toward a center of the secondary particle.
3. The lithium complex oxide secondary particle of claim 1 , wherein a primary particle locating on the surface part of the secondary particle is configured to satisfy that dc/dh is 2 to 10, where the dc is a length toward a center and the dh is a length vertical to the center.
4. The lithium complex oxide secondary particle of claim 1 , wherein the secondary particle has at least one peak at positions (104), (110), (113), (101), (102), and (003) during XRD analysis.
5. The lithium complex oxide secondary particle of claim 1 , 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, and
wherein the P1 and the P2 are ranged respectively in 779 eV≤P1≤780 eV and 794 eV≤P2≤795 eV.
6. The lithium complex oxide secondary particle of claim 1 , wherein the secondary particle has a ratio between peak intensity (I 289 ) around 289 eV and peak intensity (I 284 ) around 284.5 eV during a C 1s core-level spectrometry that is obtained through XPS measurement, and
wherein the ratio is I 289 /I 284 ≤0.9.
7. The lithium complex oxide secondary particle of claim 1 , wherein the secondary particle is given by the following Formula 1,
Li X1 Ni 1-(x1+y1+z1) Co x1 M1 y1 M2 z1 M3 r1 O a , [Formula 1]
wherein, in the Formula 1, M1 is Mn or Al, and M2 and M3 are elements selected from a group of Al, Ba, B, Co, Ce, Cr, F, Li, Mg, Mn, Mo, P, Sr, Ti, and Zr, and
wherein 0.95≤X1≤1.05, 1.50≤a≤2.1, 0.02≤x1≤0.25, 0.01≤y1≤0.20, 0≤z1≤0.20, and 0≤r1≤0.20.
8. A lithium secondary battery comprising a lithium complex oxide secondary particle of claim 1 .
9. The lithium secondary battery of claim 8 , wherein the lithium secondary battery is configured to have residual lithium equal to or smaller than 6,000 ppm.