On the Origin of the Non-Arrhenius Na-ion Conductivity in NaOBr.

The sodium-rich antiperovskites (NaRAPs) with composition NaOB (B=Br, Cl, I, BH, etc.) are a family of materials that has recently attracted great interest for application as solid electrolytes in sodium metal batteries. Non-Arrhenius ionic conductivities have been reported for these materials, the origin of which is poorly understood.