Driven by the rising demand for consumer electronics, the field of all solid-state batteries employing solid electrolytes as the ion-conducting separator has attracted enormous attention in the last years. Recently, the lithium-conducting rare-earth halides A 3 MX 6 (A = Li, M = Y, Er, X = Cl, Br, I) and Li 3 InX 6 have been rediscovered as potential solid electrolytes, showing a good overall electrochemical performance, while the corresponding sodium-based compounds have been mostly overlooked

more »

... yet. Here, we report the ionic transport properties of the Na-ion conducting rare-earth halide solid electrolyte Na 3−x Er 1−x Zr x Cl 6 . Na 3−x Er 1−x Zr x Cl 6 shows a conductivity enhancement from 10 −9 S·cm −1 up to of ∼0.04 mS·cm −1 for Na 2.4 Er 0.4 Zr 0.6 Cl 6 , alongside interesting local structural rearrangements of the polyhedral motifs along the series of solid solutions. This series of halide-based sodium-ion conductors sheds light on promising compositions in search for superionic materials.