Positive electrode active material having improved safety and lifetime characteristics and lithium secondary battery comprising the same

摘要

Provided is a secondary battery comprising a positive electrode active material represented by the following Chemical Formula 1,
Li{LiaMnxM1-a-x-yM′y}O2  [Chemical Formula 1]where 0(1−a)/2, and 0

主权项

1. A lithium secondary battery comprising a positive electrode active material represented by the following Chemical Formula 1:
Li{LiaMnxM1-a-x-yM′y}O2  [Chemical Formula 1] where 0(1−a)/2, and 0.05≦y<0.2(1−a), and M is simultaneously applied by two elements of nickel (Ni) and cobalt (Co), and M′ is a metal having an ion diameter of 70 pm or more with an oxidation number of 4 as well as a six-coordinate octahedral structure, wherein the positive electrode active material further comprises any one or two or more lithium-containing metal oxides selected from the group consisting of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium cobalt-nickel oxide, lithium cobalt-manganese oxide, lithium manganese-nickel oxide, lithium cobalt-nickel-manganese oxide, lithium-containing olivine-type phosphate, lithium-containing manganese spinel, and lithium-containing metal oxide having other element(s) substituted or doped thereto; wherein the battery is prepared by performing a formation process comprising charging at a voltage from 4.4V to 5.0 V based on a positive electrode potential and degassing after the formation process; and wherein a generation of gas is completed in an initial formation process and the gas is not generated during a subsequent charge and discharge cycle.