Crystal and electronic structures of superstructural Li1−x[Co1/3Ni1/3Mn1/3]O2 (0≤x≤1)

Abstract Crystal and electronic structures of two model crystals for Li[Co 1/3 Ni 1/3 Mn 1/3 ]O 2 have been investigated using first principles calculations. One is so-called superlattice model of [√3×√3]R30°-type in triangular lattice of sites and the other is piled-up model among CoO 2 , NiO 2 and MnO 2 slabs. For both models, the formal charges of Co, Ni and Mn are, respectively, estimated to be +3, +2 and +4 from the interatomic distances and electronic structures. The formation energy for a superlattice model is −0.17 eV while that for a piled-up model is +0.06 eV, indicating that Li[Co 1/3 Ni 1/3 Mn 1/3 ]O 2 having a [√3×√3]R30°-type superlattice can be prepared when the processing method is exploited. The solid-state redox reactions in a superlattice model are also calculated and predicted that the reaction in the ranges of 0≤ x ≤1/3, 1/3≤ x ≤2/3 and 2/3≤ x ≤1 in Li 1− x [Co 1/3 Ni 1/3 Mn 1/3 ]O 2 consists of Ni 2+ /Ni 3+ , Ni 3+ /Ni 4+ and Co 3+ /Co 4+ , respectively, with smaller change in unit-cell volume associated with lithium insertion reaction than those of LiCoO 2 , LiNiO 2 and LiMnO 2 .