Cathode active material, method for manufacturing same, and lithium secondary battery comprising same
A method for manufacturing a positive active material is provided. The method includes forming a positive active material precursor including nickel, mixing and firing the positive active material precursor and lithium salt to form a preliminary positive active material particle, forming a coating material including fluorine on the preliminary positive active material particle by dry-mixing the preliminary positive active material particle with a coating source including fluorine, and manufacturing a positive active material particle by thermally treating the preliminary positive active material particle on which the coating material is formed.
1. A positive active material including a positive active material particle containing lithium, a transition metal, fluorine (F), and oxygen,
wherein the fluorine is provided on a surface of the positive active material particle and an inner portion of the positive active material particle,
the fluorine provided on the surface of the positive active material particle includes a coating material containing LiF, and is provided in a form of a layer or a particle on the surface of the positive active material particle,
a content of the fluorine provided in the inner portion of the positive active material particle gradually decreases in at least a part of the inner portion of the positive active material particle,
the transition metal contains 60 mol % or more of nickel, and
the fluorine (F) is provided to the positive active material particle by dry-mixing using a fluorine source containing NH 4 F or NH 4 HF 2 .
2. The positive active material of claim 1 , wherein the positive active material particle contains lithium, a transition metal, fluorine (F), and oxygen, and
the positive active material particle contains LiOH and Li 2 CO 3 as surface residual lithium, and the amount of Li 2 CO 3 is smaller than the amount of LiOH.
3. The positive active material of claim 1 , wherein the transition metal further includes at least one of cobalt, manganese, and aluminum.
4. The positive active material of claim 1 , wherein a concentration of the transition metal is constant in the inner portion of the positive active material particle.
5. The positive active material of claim 1 , wherein the transition metal has a concentration gradient in the inner portion of the positive active material particle.