Cathode active material for lithium secondary battery, cathode including same, and lithium secondary battery including same

A cathode active material for a lithium secondary battery, the cathode active material comprising:

• secondary particles, each of the secondary particles comprising an aggregate of two or more primary particles,
• wherein, at a surface of the secondary particles, a primary particle coefficient is greater than or equal to 30 μm−1 and less than or equal to 60 μm−1 and a total circumferential length of the primary particles is greater than or equal to 220 μm,
• an average size of the primary particles based on a two-dimensional image measuring the surface of the secondary particles is less than or equal to 0.5 μm,
• an average particle strength of the secondary particles is greater than or equal to 70 MPa and less than or equal to 100 MPa, and
• the primary particle coefficient is measured at the surface of the secondary particles and not at a cross-section of the secondary particles exposed through cutting the cathode active material.