Identification of ferrimagnetic orbitals preventing spinel degradation by charge ordering in Li${}_x$Mn${}_2$O${}_4$

Abstract

Spinel Li${}_x$Mn${}_2$O${}_4$ is a key cathode material that is used extensively in commercial Li-ion batteries. A challenge with this material has been that the capacity of the battery fades with cycling, an effect that can be traced to the presence of an anti-ferromagnetic insulator phase in the fully lithiated LiMn${}_2$O${}_4$ (LMO) and the associated charge disproportionation that drives distortions of the MnO${}_6$ octahedra. Here, by combining x-ray magnetic Compton scattering experiments with parallel first-principles computations, we show that the anti-ferromagnetic phase of LMO is surrounded by a robust ferrimagnetic metallic phase, which becomes stable when even a small amount of Li is removed from or added to the charge-ordered LMO. In this surprising ferrimagnetic state, charge-ordering and octahedral distortions are found to be strongly suppressed. We identify the nature of the ferrimagnetic orbitals involved through theoretical and experimental analyses of the magnetic Compton scattering spectra.

References in corpus (4)

• Origin of band gaps in 3d perovskite oxides
• Calculation of valence electron momentum densities using the projector augmented-wave method
• Extracting the Redox Orbitals in Li Battery Materials with High-Resolution X-Ray Compton Scattering Spectroscopy
• Spin moment over 10-300 K and delocalization of magnetic electrons above the Verwey transition in magnetite

Cited by in corpus (1)

• Topological Dirac Semimetal Phase in Bismuth Based Anode Materials for Sodium-Ion Batteries