Method for manufacturing cathode active material for lithium ion secondary battery

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

• a mixing process of mixing transition metal-containing composite compound particles containing lanthanum with a lithium compound to obtain a lithium mixture;
• a calcination process of firing the lithium mixture at a temperature equal to or lower than a melting point of the lithium compound;
• and
• a main firing process of firing the lithium mixture at a temperature higher than the melting point of the lithium compound after the calcination process, wherein
• the method brings about a cathode active material for a lithium ion secondary battery, the cathode active material including a lithium transition metal-containing oxide constituted by secondary particles each formed of a plurality of primary particles, in which lanthanum compound particles each having a perovskite-type structure are dispersed on surfaces of the secondary particles and/or in gaps or grain boundaries between the primary particles, and the lanthanum compound particles have a cross-sectional average particle size of 0.70 μm or less.