LiNi
zCo
1−2zMn
zO
2 materials have been investigated as promising positive electrode materials for lithium-ion secondary batteries, in which cobalt ions are simultaneously substituted with nickel and manganese ions while preserving the α-NaFeO
2 structure. The materials can be regarded as solid solutions of LiNiO
2, LiCoO
2, and LiMnO
2, in which the transition metals are trivalent in all three materials, whereas the transition metals found in LiNi
zCo
1−2zMn
zO
2 materials are Ni
2+, Co
3+, and Mn
4+. The electrochemical lithium deintercalation-intercalation processes of these materials are mainly accompanied by the Ni
2+/4+ and Co
3+/4+ redox reactions, whereas Mn
4+ ions do not participate in the electrochemical redox reaction. Recently, Li
+ substitution for transition metals in Li
1+x(Ni
zCo
1−2zMn
z)
1−xO
2, so called overlithiation, has been introduced to improve their structural integrity and electrochemical performances.
In this paper, we introduce the overlithiation effects on the structural and electrochemical properties of the Li
1+x(Ni
zCo
1−2zMn
z)
1−xO
2 materials having diffrrent
x- and
z-values in the ranges from
x=0.00 to
x=0.17 and
z=0.00 to
z=0.50.
View full abstract