Cathode active material for lithium secondary battery, method for preparing same, and lithium secondary battery including same

According to an embodiment, there is provided a positive electrode active material for a lithium secondary battery, the positive electrode active material including a nickel-based composite metal oxide including a secondary particle in which a plurality of primary particles are aggregated, in which the secondary particle includes a central portion and a surface portion, the surface portion including the nickel-based composite metal oxide doped with manganese, and an amount of manganese at grain boundaries of the plurality of primary particles present in the surface portion is greater than an amount of manganese present inside the primary particles. 根据实施方式，提供用于锂二次电池的正极活性物质，正极活性物质包括包含其中聚集了多个初级颗粒的次级颗粒的镍类复合金属氧化物，其中，次级颗粒包括中心部分和表面部分，表面部分包括掺杂有锰的镍类复合金属氧化物，并且存在于表面部分中的多个初级颗粒的晶界处的锰的量大于存在于初级颗粒内部的锰的量。