Positive electrode active material for lithium secondary battery, method for preparing the same and lithium secondary battery comprising the same

Abstract

A positive electrode active material includes at least one secondary particle including an agglomerate of primary macro particles. The average particle size of the primary macro particle is 2 μm or more. A ratio of the average particle size of the primary macro particle to an average crystal size of the primary macro particle is 8 or more. An average particle size of the secondary particle is 3 to 10 μm. The secondary particle includes a nickel-based lithium transition metal oxide. The primary macro particle does not crack in a rolling process under 9 tons. A method for preparing the positive electrode active material includes mixing a nickel-based transition metal oxide precursor having a tap density of 2.0 g/cc or less and a lithium precursor and performing primary sintering to form a primary sintered product and performing secondary sintering on the primary sintered product.