Cathode active material, method for preparing same, and lithium secondary battery comprising same
A positive active material, a manufacturing method thereof, and a lithium secondary battery including the same are disclosed, and a positive active material including lithium metal oxide particles in a secondary particle form including primary particles, wherein the secondary particle surface includes planar primary particles with a narrow angle of 70 to 90° from among angles between a c axis of the primary particles and a straight line connecting a virtual point of a center of the primary particle and a center point of the secondary particle may be provided.
1. A positive active material including lithium metal oxide particles in a secondary particle form including primary particles,
wherein the secondary particle surface includes planar primary particles with a narrow angle of 60 to 90° from among angles between a c axis of the primary particles and a straight line connecting a virtual point of a center of the primary particle and a center point of the secondary particle, and
with respect to the area of 100 area % formed by a circle of 50% reference of a radius of the secondary particles at the center point of the secondary particle, an area occupied by the planar primary particles is equal to or greater than 20 area %.
2. The positive active material of claim 1 , wherein
with respect to the area 100 area % formed by the circle of 50% reference of the radius of the secondary particles at the center point of the secondary particle, and
an average length of the planar primary particles existing in the area is 750 nm to 1.25 μm.
3. The positive active material of claim 1 , wherein
an inside of the secondary particle includes acicular primary particles with a narrow angle of equal to or greater than 0° and less than 70° from among angles between a c axis of the primary particles and a straight line connecting a virtual point of a center of the primary particle and a center point of the secondary particle.
4. The positive active material of claim 1 , wherein
a content of nickel from among metals in the secondary particle is equal to or greater than 80 mol %.
5. A method for manufacturing the positive active material of claim 1 , comprising:
obtaining a metal precursor by inputting a metallic salt aqueous solution into a co-precipitation reactor; and
obtaining a positive active material by mixing the metal precursor and a raw lithium material and baking the same,
wherein, in the obtaining of a metal precursor by inputting the metallic salt aqueous solution into the co-precipitation reactor, a pH condition is changes within a range of a reaction end time of 1 to 30 time % with respect to an entire reaction time of 100 time %, and the pH condition rises by 0.1 to 0.8 within a range of the reaction end time of 1 to 30 time % for the entire reaction time of 100 time %.
6. The method of claim 5 , wherein
a difference between a reaction start pH and a reaction end pH in the obtaining of a metal precursor by inputting the metallic salt aqueous solution into the co-precipitation reactor is 0.1 to 0.8.
7. The method of claim 5 , wherein
the rising speed of the pH condition is 0.0016 to 0.0133 pH/min.
8. A lithium secondary battery comprising:
a positive electrode including the positive active material according to claim 1 ;
a negative electrode including a negative active material; and
an electrolyte positioned between the positive electrode and the negative electrode.