Fluoride Ion Transport and Phase Evolution in the Cathode Material LaSrMnO4 within All-Solid-State Fluoride Ion Batteries

Fluoride ion batteries (FIBs) are an emerging energy storage technology with high gravimetrical and volumetric energy densities along with the potential for material sustainability. In this study, we increase the fundamental understanding of the Ruddlesden-Popper-type cathode material LaSrMnO₄. The layered structure of LaSrMnO₄ provides interstitial sites that facilitate reversible fluoride ion insertion and extraction. Structural and electrochemical analyses confirm its stability over multiple charge–discharge cycles, and structural changes within the defluorination process are highlighted within this study for the first time. Computational investigation of the LaSrMnO₄Fx (0