Positive electrode active material for rechargeable lithium battery and rechargeable lithium battery
A positive electrode active material for a rechargeable lithium battery, and a rechargeable lithium battery including the same are provided. The positive electrode active material includes a lithium nickel-based composite oxide wherein the positive electrode active material is in a form of secondary particles in which a plurality of primary particles are aggregated and at least a portion of the primary particles are radially arranged, in a cross-section of the secondary particles, a number ratio of the primary particles having a cross-sectional area of less than about 0.1 μm 2 is greater than or equal to about 65%, and a full width at half maximum (FWHM) of the peak corresponding to the (003) plane in the X-ray diffraction analysis for the positive electrode active material is less than or equal to about 0.125.
1 . A positive electrode active material for a rechargeable lithium battery, the positive electrode active material comprising: a lithium nickel-based composite oxide,
wherein the positive electrode active material comprises a secondary particle in which a plurality of primary particles are aggregated and at least a portion of the primary particles are radially arranged,
in a cross-section of the secondary particle, a number ratio of the primary particles having a cross-sectional area of less than about 0.1 μm 2 to a total number of the primary particles is greater than or equal to about 65%, calculated from a scanning electron microscope image, and
a full width at half maximum (FWHM) of a peak corresponding to the (003) plane in an X-ray diffraction analysis for the positive electrode active material is less than or equal to 0.125.
2 . The positive electrode active material of claim 1 , wherein
in the cross-section of the secondary particle, the number ratio of the primary particles having a cross-sectional area of less than about 0.1 μm 2 is about 65% to about 90%.
3 . The positive electrode active material of claim 1 , wherein
in the cross-section of the secondary particle, a number ratio of the primary particles having a cross-sectional area of greater than about 0.3 μm 2 is less than or equal to about 5%, based on the total number of the primary particles.
4 . The positive electrode active material of claim 1 , wherein
in the cross-section of the secondary particle, a number ratio of the primary particles having a cross-sectional area of about 0.1 μm 2 to about 0.3 μm 2 is about 5% to about 30%, based on the total number of the primary particles.
5 . The positive electrode active material of claim 1 , wherein
the full width at half maximum of the peak corresponding to the (003) plane in the X-ray diffraction analysis for the positive electrode active material is about 0.100 to 0.125.
6 . The positive electrode active material of claim 1 , wherein
the secondary particle comprises an inner portion in which primary particles and pores are irregularly arranged, and an outer portion in which at least a portion of the primary particles are radially arranged, and
wherein the outer portion is a region around the inner portion.
7 . The positive electrode active material of claim 1 , wherein
an average particle diameter (D50) of secondary particles in the positive electrode active material is about 5 μm to about 20 μm.
8 . The positive electrode active material of claim 1 , wherein
the lithium nickel-based composite oxide is represented by Chemical Formula 1:
Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O 2-z X z Chemical Formula 1
wherein, in Chemical Formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and 0≤z≤0.1, M 1 and M 2 are each independently at least one element selected from Al, B, Ba, Ca, Ce, Co, Cr, Fe, Mg, Mn, Mo, Nb, Si, Sr, Ti, V, W, and Zr, and X is at least one element selected from F, P, and S.
9 . A positive electrode for a rechargeable lithium battery, the positive electrode comprising:
the positive electrode active material of claim 1 ; and
a current collector supporting the positive electrode active material.
10 . A rechargeable lithium battery, comprising
a positive electrode comprising the positive electrode active material of claim 1 ,
a negative electrode, and
an electrolyte.
11 . The positive electrode active material of claim 1 , wherein
in the cross-section of the secondary particle, a number ratio of the primary particles having a cross-sectional area of greater than about 0.3 μm 2 is 0.1% to about 5%, based on the total number of the primary particles.
12 . The positive electrode active material of claim 1 , wherein
the positive electrode active material comprises a core, an intermediate layer and a shell.
13 . The positive electrode active material of claim 12 , wherein
the positive electrode active material is produced through a three-step co-precipitation reaction in which one or more selected from a concentration of a complexing agent, an input rate of a composite metal raw material, a pH range, a reaction temperature, a reaction time, and a stirring power are differently adjusted for each step.