Composite positive electrode active material for lithium ion battery preparing method thereof and lithium ion battery including positive electrode comprising the same

The present invention relates to a composite positive electrode active material for a lithium ion battery, comprising: a nickel-rich lithium-nickel-based compound having a nickel content of 50 to 100 mol% based on the total amount of transition metals; and a coating film including a rare earth metal hydroxide formed on the surface of the nickel-rich lithium-nickel-based compound, to a manufacturing method thereof, and to a lithium ion battery containing a positive electrode comprising the same. The lithium ion battery has improved capacity, lifespan and high-temperature storage properties. 니켈의 함량이 전이금속 총량을 기준으로 하여 50 내지 100몰%인 니켈 리치(nickel rich) 리튬니켈계 화합물; 및 상기 니켈 리치 리튬니켈계 화합물의 표면에 형성된 희토류 금속 하이드록사이드(rare earth metal hydroxide)를 포함하는 코팅막을 포함하는 리튬이온전지용 복합양극활물질, 그 제조방법 및 이를 포함하는 양극을 함유한 리튬이온전지가 제시된다.