Positive electrode active material, lithium ion secondary battery, and method of producing positive electrode active material

A positive electrode active material comprising:

• secondary particles, wherein the secondary particles include a plurality of primary particles, the primary particles are a lithium-containing composite metal oxide, inside the secondary particles, an electron conducting oxide is disposed at substantially an entire grain boundary between the primary particles inside the secondary particle, and the electron conducting oxide has a perovskite structure and is represented by Formula (I):
• ACox1Mx2O3, wherein in the formula, A is at least one of La and Sr, M is at least one of Mn and Ni, and x1 and x2 satisfy 0<x1≤1, 0≤x2≤1, and 0.6≤x1+x2≤1.