Irreversible Additive Comprised in Cathode Material for Secondary Battery, Cathode Material Comprising the Same, and Secondary Battery Comprising Cathode Material

The present disclosure provides an irreversible additive contained in a cathode material for a secondary battery, wherein the irreversible additive is an oxide represented by the following chemical Formula 1, and wherein the oxide has a trigonal structure, a cathode material including the irreversible additive, and a secondary battery including the cathode material: LiNiMoO (1)