The role of oxygen excess on fluoride intercalation in Ruddlesden–Popper electrodes for fluoride ion batteries: the case of LaSrMnO4

Abstract

Ruddlesden–Popper-type compounds are particularly attractive electrode materials for fluoride-ion batteries. Among them, LaSrMnO₄ has received significant attention due to its high fluoride incorporation capability and lower environmental impact compared to nickel- and cobalt-based analogues. In this work, neutron diffraction data are used to provide an experimental visualization of fluoride-ion diffusion in this class of materials, through maximum entropy method (MEM) and bond valence site energy (BVSE) analysis. Additionally, since oxygen excess is well known in Ruddlesden–Popper oxides but its impact on fluoride-ion transport has not been previously investigated, molecular dynamics (MD) simulations were employed to reveal how oxygen over-stoichiometry affects fluoride intercalation mechanisms and energetics, unveiling new migration pathways that hinder fluoride mobility. These findings have direct implications for fluoride-ion battery performance, highlighting the critical role of oxygen content in determining anion transport and the electrochemical performance of this class of materials.