| CPC H01M 4/366 (2013.01) [C01G 53/50 (2013.01); H01M 4/04 (2013.01); H01M 4/505 (2013.01); H01M 4/525 (2013.01); H01M 10/0525 (2013.01); C01P 2006/40 (2013.01); H01M 2004/028 (2013.01)] | 15 Claims |

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1. A positive electrode active material comprising:
a lithium transition metal oxide represented by Formula 2 below;
a first coating layer formed on a surface of the lithium transition metal oxide, wherein the first coating layer includes a coating element M1, wherein M1 includes aluminum (Al), or aluminum (Al) and sodium (Na); and
a second coating layer, wherein the second coating layer includes a coating element M2, wherein M2 includes boron (B),
wherein, when M1 includes Al, in a time-of-flight secondary ion mass analysis spectrum of the positive electrode active material, a ratio of the intensity of a peak detected at a mass exceeding 27 and a mass of 27.5 or less and the intensity of a peak of Al+ is 1:0.5 to 1:2,
Lia1Nib1Coc1Mnd1Ale1Xf1O2 [Formula 2]
wherein, in Formula 2,
1.03≤a1≤1.12, 0.7≤b1<1.0, 0<c1≤0.3, 0<d1≤0.3, 0<e1≤0.1, and 0≤f1≤0.1, and
X includes one or more selected from the group consisting of zirconium (Zr), B, tungsten (W), magnesium (Mg), cerium (Ce), hafnium (Hf), tantalum (Ta), titanium (Ti), strontium (Sr), barium (Ba), fluorine (F), phosphorus (P), sulfur (S), and lanthanum (La).
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