Positive electrode active material for secondary battery, and secondary battery comprising the same

Abstract

The present invention provides a positive electrode active material for a secondary battery, the positive electrode active material including a lithium composite metal oxide particle represented by Formula 1 below, and a secondary battery including the same.LiNiCoM1M2M3O  [Formula 1] In Formula 1, M1 is a metal element whose surface energy (ΔE) calculated by Equation 1 below is −0.5 eV or higher, M2 is a metal element whose surface energy (ΔE) calculated by Equation 1 below is −1.5 eV or higher and less than −0.5 eV, M3 is a metal element whose surface energy (ΔE) calculated by Equation 1 below is less than −1.5 eV, and 1.0≤a≤1.5, 0<x≤0.5, 0<z≤0.05, 0.002≤w≤0.1, 0<x+y≤0.7. In Equation 1 above, Erepresents an extent to which a metal element is oriented toward the outermost surface of the lithium composite metal oxide particle, Erepresents an extent to which the metal element is oriented toward a central portion of the lithium composite metal oxide particle, Eis energy of a slab model of the lithium composite metal oxide particle when the metal element is at the central portion of the lithium composite metal oxide particle, Eis energy of a slab model of the lithium composite metal oxide when the metal element is at the outermost surface of the lithium composite metal oxide, and Eis energy of a bulk model corresponding to each of the slab models.