Cathode active material precursor for lithium secondary battery, cathode active material for lithium secondary battery and lithium secondary battery
A cathode active material precursor for a lithium secondary battery has a structure of a nickel composite hydroxide. A first peak intensity ratio represented by Equation 1 is 0.5 or more, and a second peak intensity ratio represented by Equation 2 is 0.7 or more. A cathode active material and a lithium secondary battery having a stabilized crystal structure are provided using the cathode active material precursor.
1 . A cathode active material precursor for a lithium secondary battery having a structure of a nickel composite hydroxide,
wherein the nickel composite hydroxide includes Ni, Co and Mn, and further includes at least one of Mg, Sr, Ba, B, Al, Si, Ti, Zr and W,
wherein a first peak intensity ratio represented by Equation 1 is 0.7 or more, and a second peak intensity ratio represented by Equation 2 is in a range from 0.7 to 1.4:
First peak intensity ratio= I (101)/ I (001) [Equation 1]
Second peak intensity ratio= I (101)/ I (100) [Equation 2]
wherein, in Equations 1 and 2, I(101), I(001) and I(100) are peak intensities or maximum peak heights of (101), (001) and (100) planes, respectively, by an X-ray diffraction analysis.
2 . The cathode active material precursor for a lithium secondary battery of claim 1 , wherein the structure of the nickel composite hydroxide is represented by Chemical Formula 1:
Ni 1-x-y-z CO x Mn y M z (OH) 2+a [Chemical Formula 1]
wherein, in Chemical Formula 1, M includes at least one selected from the group consisting of Mg, Sr, Ba, B, Al, Si, Ti, Zr and W, 0.02≤x≤0.15, 0≤y≤0.15, 0≤z≤0.1, and −0.5≤a≤0.1.
3 . The cathode active material precursor for a lithium secondary battery of claim 1 , wherein a molar ratio of nickel among elements other than a hydroxyl group is 0.8 or more.
4 . The cathode active material precursor for a lithium secondary battery of claim 1 , wherein the first peak intensity ratio is in a range from 0.75 to 1.3.