Composite cathode active material, cathode and lithium battery each containing composite cathode active material, and preparation method of cathode active material

A composite cathode active material comprising:

• a core comprising a plurality of primary particles;
• and
• a shell on the core,
• wherein the primary particles comprise a first lithium transition metal oxide comprising nickel,
• wherein the first lithium transition metal oxide comprises a second metal, wherein the second metal comprises zirconium,
• wherein the shell comprises a first layer and a second layer on the first layer,
• wherein the first layer comprises a first composition represented by Formula 1A:
• M1bOc
• wherein, in Formula 1A,
• M1 is at least one of cobalt, magnesium, zirconium, aluminum, manganese, silicon, palladium, titanium, tin, iridium, platinum, ruthenium, cerium, boron, niobium, vanadium, iron, and zinc,
• 0.9≤b≤3.1, and 1.9≤c≤4.1,
• the second layer comprises a second composition comprising cobalt and phosphorus, and an amount of the second composition included in the second layer is about 2 parts by weight or less based on 100 parts by weight of the first lithium transition metal oxide, and
• wherein the core comprises a grain boundary located between primary particles of the plurality of primary particles, and the grain boundary comprises a third composition comprising Li2ZrO3.