Positive Electrode Active Material, Positive Electrode, and Lithium Secondary Battery

A positive electrode active material comprising a secondary particle in which a plurality of primary particles are aggregated,

• wherein the plurality of primary particles have an average particle size measured from a scanning electron microscope image of from 1.5 μm to 5.0 μm,
• wherein particle size of the plurality of primary particles is based on a long diameter of each primary particle of the plurality of primary particles, and
• in a frequency distribution graph illustrating a volume cumulative distribution of the positive electrode active material measured using a laser diffraction particle size analyzer, where an x value of an x-axis represents a particle diameter increasing from left to right on a log scale, and a y value of a y-axis represents a volume distribution increasing from bottom to top,
• when a triangle is drawn with a peak point at an uppermost end of the y-axis of a peak appearing at a mode;
• and two contact points of a frequency distribution curve which are cross at a full width at half maximum of the mode,
• a difference between an internal angle at a left contact point of the two contact points of the frequency distribution curve and an internal angle at a right contact point of the two contact points of the frequency distribution curve is in a range of from 6 to 20.