摘要 |
Disclosed is a cathode active material for secondary batteries comprising one or more compounds having a layered-crystal structure, represented by the following Formula 1, wherein a transition metal layer contains Li, in an amount lower than 20%, based on a total amount of a transition metal site, and a ratio of Ni positioned in a lithium layer, that is, a cation mixing ratio is 1% to 4.5%, based on a total amount of a lithium site in the lithium layer to stably support the layered-crystal structure: (1-s-t)[Li(LiaMn(1-a-x-y)NixCoy)O2]*s [Li2CO3]*t[LiOH] (1), wherein 0<a<0.2; 0<x<0.9; 0<y<0.5; a+x+y<1; 0<s<0.03; and 0<t<0.03. The cathode active material exhibits long lifespan and superior stability at room temperature and high temperatures in spite of repeated charge and discharge at a high current. |