| 主权项 |
1. A positive active material comprising:
a core comprising a lithium nickel-based composite oxide; and a composite coating layer formed on a surface of the core, the composite coating layer comprising lithium metal phosphate and metal phosphate, wherein lithium content at the surface of the core is higher than lithium content inside the core and the surface of the core has a surface composition, and wherein the surface composition of the core comprises at least one compound selected from the group consisting of compounds represented by Formulae 6 and 7-shown below:
LiaNi1-b-cMnbM′cAp [Formula 6]LiaNi1-b-cMnbM′cO2-pXp [Formula 7] wherein in Formula 6, a, b, c, and p respectively satisfy 1.01≦a≦1.35, 0<b≦0.5, 0<c≦0.5, and 0<p≦2, M′ is selected from the group consisting of Co, Cr, Mg, strontium (Sr), vanadium (V), scandium (Sc), yttrium (Y), and a lanthanide element, A is at least one component selected from the group consisting of oxygen (O), fluorine (F), sulfur (S), and phosphorus (P), wherein in Formula 7, a, b, c, and p respectively satisfy 1.01≦a≦1.35, 0<b≦0.5, 0<c≦0.5, and 0<p<2, M′ is selected from the group consisting of Al, Co, Cr, Fe, Mg, strontium (Sr), vanadium (V), scandium (Sc), yttrium (Y), and a lanthanide element, and X is at least one component selected from the group consisting of fluorine (F), sulfur (S), and phosphorus (P). |
