IRREVERSIBLE ADDITIVE INCLUDED IN CATHODE MATERIAL FOR SECONDARY BATTERY, CATHODE MATERIAL COMPRISING 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. Li2+aNi1-bMobO2+c (1)in the above formula, -0.2≤a≤0.2, 0