Lithium complex oxide
The present invention relates to a lithium complex oxide, and more specifically, to a lithium complex oxide of which a range of FWHM (104) values maintains a constant relationship with a molar fraction of nickel when measuring XRD defined by a hexagonal lattice having a R-3m space group. The lithium complex oxide according to the present invention exhibits an effect of improving lifetime properties of the cells including high Ni-based cathode active materials accordingly by enabling a range of the FWHM (104) values at (104) peaks defined b the hexagonal lattice having the R-3m space group to maintain a constant relationship with the molar fraction of nickel, thereby maintaining the primary particles in a predetermined size range.
1. A lithium complex oxide of which primary particles are aggregated secondary particles and represented by the following chemical formula 1, and in which a range of FWHM (deg., 2θ) values at (104) peaks during the measurement of XRD defined by a hexagonal lattice having a R-3m space group is represented by the following relation formula 1:
Li a Ni x Co y Mn z M 1-x-y-z O 2 [Chemical Formula 1]
in chemical formula 1, M is selected from the group consisting of B, Ba, Ce, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, and a combination thereof, 0.9≤a≤1.3, 0.8≤x<1.0, 0.0<y+z≤0.2, 0.0≤1-x-y-z<0.2;
−0.025≤FWHM (104) −{0.04+( x− 0.6)×0.25}≤0.025 [Relation formula 1]
in relation formula 1, FWHM (104) of relation formula 1 is represented by the following relation formula 2:
FWHM (104) =FWHM chemical formula 1 powder (104) −FWHM Si powder (220) [Relation formula 2]
in relation formula 2, FWHM chemical formula 1 powder (104) indicates a FWHM (full width at half maximum) value at the (104) peak observed near 44.5° (2θ) during XRD measurement of the lithium complex oxide, and
in relation formula 2, FWHM Si powder (220) indicates a FWHM value at a (220) peak observed near 47.3° (2θ) during XRD measurement of the Si powder.
2. The lithium complex oxide of claim 1 , wherein FWHM (104) represented by relation formula 2 is in a range of 0.108° (2θ) to 0.162° (2θ) when the content x of nickel is 0.97 to 0.99.
3. The lithium complex oxide of claim 1 , wherein FWHM (104) represented by relation formula 2 is in a range of 0.098° (2θ) to 0.152° (2θ) when the content x of nickel is 0.93 to 0.95.
4. The lithium complex oxide of claim 1 , wherein FWHM (104) represented by relation formula 2 is in a range of 0.083° (2θ) to 0.137° (2θ) when the content x of nickel is 0.87 to 0.89.