Patent ID: 11557754

Abstract:
A positive electrode active material for a lithium secondary battery, comprising a lithium-containing composite metal oxide in the form of secondary particles formed by aggregation of primary particles capable of being doped and undoped with lithium ions, each of the secondary particles having on its surface a coating layer, the positive electrode active material satisfying the following requirements (1) to (3):(1) the metal oxide has an α-NaFeO2 type crystal structure of following formula (A): Lia(NibCocM11-b-c)O2  (A) wherein 0.9≤a≤1.2, 0.9≤b<1, 0<c≤0.1, 0.9<b+c≤1, and M1 represents at least one optional metal selected from Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In and Sn; (2) the coating layer comprises Li and M2, wherein M2 represents at least one optional metal selected from Al, Ti, Zr and W; and(3) the active material has an average secondary particle diameter of 2 to 20 μm, a BET specific surface area of 0.1 to 2.5 m2/g, and a value of 1.0 to 2.0 as a tamped density/untamped density ratio of the active material.