Temperature-dependent dynamic disproportionation in LiNiO2

Nickelate materials offer diverse functionalities for energy and computing applications.  Lithium nickel oxide (LiNiO₂) is an archetypal layered nickelate, but the electronic structure of this correlated material is not yet fully understood.

In the paper 'Temperature-dependent dynamic disproportionation in LiNiO₂', published in Nature Communications, the authors investigate the temperature-dependent speciation and spin dynamics of Ni ions in LiNiO₂.  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 NiL₃,_2-edge.  Charge-transfer multiplet calculations consistent with disproportionation reproduce all experimental features.

The results support a model of dynamic disproportionation that explains diverse physical observations of LiNiO₂, including magnetometry, thermally activated electronic conduction, diffractometry, core-level spectroscopies, and the stability of ubiquitous antisite defects.  This unified understanding of the material properties of LiNiO₂ is important for applications of nickelate materials as battery cathodes, catalysts and superconductors.