Irreversible additive contained in positive electrode material for secondary battery, positive electrode material comprising same, and secondary battery comprising same

The present invention provides an irreversible additive contained in a positive electrode material for a secondary battery, a positive electrode material comprising the irreversible additive, and a secondary battery comprising the positive electrode material, in which the irreversible additive is an oxide represented by the following Chemical Formula 1, and in which the oxide has a trigonal crystal structure. Li2 + aNi1-bMobO2 + c (1), where-0.2 < = a < = 0.2, 0 lt; b < = 0.2, and 0 < = c < = 0.2. 本发明提供了一种二次电池用正极材料中所含的不可逆添加剂、包含所述不可逆添加剂的正极材料以及包含所述正极材料的二次电池，其中所述不可逆添加剂是下述化学式1表示的氧化物，并且其中所述氧化物具有三方晶系晶体结构。Li2+aNi1-bMobO2+c(1)，其中，-0.2≤a≤0.2，0