A lithium ion secondary battery including: a cathode including a plurality cathode active material particles; an electrolyte; and an anode, wherein a cathode active material particle of the plurality of cathode active material particles has a plate-shaped crystal structure having an aspect ratio of 2 to 1000, wherein a major surface in at least one direction of the plate-shaped crystal structure is a 111 face, wherein the cathode active material particle also has a spinel-type crystal structure, and wherein the cathode active material particle has a composition represented by the formula LiCo2-xNixO4, wherein 0