Temperature-Dependent Dynamic Disproportionation in LiNiO
arXiv:2211.09047 · doi:10.1038/s41467-025-64429-4
Abstract
Nickelate materials offer diverse functionalities for energy and computing applications. Lithium nickel oxide (LiNiO) is an archetypal layered nickelate, but the electronic structure of this correlated material is not yet fully understood. Here we investigate the temperature-dependent speciation and spin dynamics of Ni ions in LiNiO. Our ab initio simulations predict that Ni ions disproportionate into three states, which dynamically interconvert and whose populations vary with temperature. These predictions are verified using x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and resonant inelastic x-ray scattering at the Ni L-edge. Charge-transfer multiplet calculations consistent with disproportionation reproduce all experimental features. Together, our experimental and computational results support a model of dynamic disproportionation that explains diverse physical observations of LiNiO, including magnetometry, thermally activated electronic conduction, diffractometry, core-level spectroscopies, and the stability of ubiquitous antisite defects. This unified understanding of the fundamental material properties of LiNiO is important for applications of nickelate materials as battery cathodes, catalysts, and superconductors.
30 pages, 16 figures