Positive electrode active material precursor and positive electrode active material for secondary batteries

A positive electrode active material particle comprising:

• a core portion;
• and
• a shell portion,
• wherein the core portion includes nickel (Ni) and aluminum (Al),
• the shell portion includes cobalt (Co),
• a mol % value of the nickel (Ni) of the core portion is greater than a mol % value of nickel (Ni) of the shell portion,
• a mol % value of the aluminum (Al) of the core portion is greater than a mol % value of aluminum (Al) of the shell portion,
• a mol % value of the cobalt (Co) of the shell portion is greater than a mol % value of cobalt (Co) of the core portion,
• wherein, the mol % value of a specific transition metal of the core portion means a mol % value of the specific transition metal with respect to all transition metals other than lithium (Li) included in the core portion, and
• the mol % value of a specific transition metal of the shell portion means a mol % value of the specific transition metal with respect to all transition metals other than lithium (Li) included in the shell portion.