POSITIVE ELECTRODE ACTIVE MATERIAL, METHOD FOR PRODUCING SAME, AND LITHIUM SECONDARY BATTERY INCLUDING SAME
The present exemplary embodiments relate to a positive electrode active material, a manufacturing method thereof, and a lithium secondary battery including the same. A positive active material for a lithium secondary battery according to an exemplary embodiment is a lithium metal oxide particle in the form of secondary particles including a plurality of primary particles: a first coating layer positioned on at least a part of the surface of the primary particle, and a second coating layer positioned over at least a portion of the secondary particle surface, the first coating layer comprising a first niobium compound, the second coating layer comprising the first niobium compound and a second niobium compound having a composition different from the first niobium compound.
1 . A positive electrode active material for a lithium secondary battery, wherein:
the positive electrode active material is a lithium metal oxide particle in the form of a secondary particle including a plurality of primary particles, and
the positive electrode active material comprises:
a first coating layer positioned on at least part of the primary particle surface; and
a second coating layer positioned on at least part of the secondary particle surface
wherein, the first coating layer contains a first niobium compound,
the second coating layer contains the first niobium compound and a second niobium compound having a different composition from the first niobium compound.
2 . The positive electrode active material of claim 1 , wherein:
the primary particle on which the first coating layer is positioned is positioned inside the secondary particle.
3 . The positive electrode active material of claim 1 , wherein:
the first niobium compound does not contain lithium.
4 . The positive electrode active material of claim 1 , wherein:
at least one of the first niobium compound and the second niobium compound contains an amorphous structure.
5 . The positive electrode active material of claim 3 , wherein:
the first niobium compound is at least one of Nb 2 O 5 , NbO and NbO 2 .
6 . The positive electrode active material of claim 1 , wherein:
the second niobium compound is at least one of LiNbO 3 , Nb 2 O 5 , Li 3 NbO 4 and LiNb 3 O 8 .
7 . The positive electrode active material of claim 1 , wherein:
an average thickness of the first coating layer is less than 5 nm.
8 . The positive electrode active material of claim 1 , wherein:
an average thickness of the second coating layer is less than 30 nm.
9 . The positive electrode active material of claim 1 , wherein:
the second niobium compound is LiNbO 3 , and
a content of the LiNbO 3 is 15.7 at % or more based on the total of the first and second niobium compounds included in the positive active material.
10 . The positive electrode active material of claim 1 , wherein:
a content of niobium in the positive active material is 4,000 ppm or less based on the total of the positive active material.
11 . A method of manufacturing a positive electrode active material for lithium secondary battery, comprising:
preparing a coating composition comprising niobium;
obtaining a sintered body by mixing a metal precursor and a lithium raw material and then sintering them;
preparing a mixture by adding the coating composition and the sintered body; and
heating the mixture after drying the mixture;
wherein the heating temperature is in the range of 100 degrees to 500 degrees.
12 . The method of claim 11 , wherein:
the step of preparing a coating composition is performed by a method of mixing by adding ammonium niobium oxalate to distilled water.
13 . The method of claim 11 , wherein:
a heating time of the heating step is in the range of 3 hr to 10 hr.
14 . A lithium secondary battery comprising:
a positive electrode comprising the positive electrode active material of claim 1 ;
a negative electrode; and
a non-aqueous electrolyte.