Positive electrode active material, and positive electrode and rechargeable lithium battery including the same

A positive electrode active material for a rechargeable lithium battery, comprising:

• a bimodal type positive electrode active material comprising large particles comprising a first lithium nickel-based composite oxide and small particles comprising a second lithium nickel-based composite oxide,
• wherein in each of the first lithium nickel-based composite oxide and the second lithium nickel-based composite oxide, a nickel content based on 100 mol % of a total metal excluding lithium is greater than or equal to about 80 mol %,
• a ratio (A/B) of a weight (A) of the first lithium nickel-based composite oxide and a weight (B) of the second lithium nickel-based composite oxide in the positive electrode active material is about 1 to about 4,
• a span {(an average particle diameter (D90)−an average particle diameter (D10))/an average particle diameter (D50)} of the first lithium nickel-based composite oxide is about 0.9 to about 1.2,
• a span {(an average particle diameter (D90)−an average particle diameter (D10))/an average particle diameter (D50)} of the second lithium nickel-based composite oxide is about 0.9 to about 1.2, and
• a span {(an average particle diameter (D90)−an average particle diameter (D10))/an average particle diameter (D50)} of the positive electrode active material is about 1.5 to about 2.