Systematic Research on Insertion Materials Based on Superlattice Models in a Phase Triangle of LiCoO[sub 2]-LiNiO[sub 2]-LiMnO[sub 2]

The first-principles calculations on the lithium insertion materials have been done to give the rationale for materials research on advanced lithium-ion batteries. To apply the computational methods, the model crystals are constructed by assuming in-plane two-dimensional superlattices based on -type structure for three sides of a phase triangle of Model crystals consisting of a superlattice gives two transition metal elements in the ratio of 3 to 1 and a superlattice model gives 2 to 1. For the ratio of 1 to 1, two model crystals are assumed, i.e. , so-called "straight" and "zigzag" models. The first-principles calculations for these model crystals indicate that ( i ) is a solid solution between and ( ii ) is not expected to be a solid solution between and (unstable, phase separation is expected), and ( iii ) is not a solid solution between and is expected to be a stable phase). Among these compounds calculated, having a layered structure may be a new compound consisting of and in their formal charges, which is neither a solid solution between and nor between NiO and From these theoretical results, materials design toward the implementation of novel lithium insertion materials for advanced lithium-ion batteries is discussed. © 2004 The Electrochemical Society. All rights reserved.