On the origin of the non-Arrhenius na-ion Conductivity in Na3OBr

The sodium-rich antiperovskites (NaPAPs) with composition Na₃OB (B= Br, Ci, I, BH4) are a family of materials that have 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.

In this work the authors combined temperature-resolved bulk and local characterisation methods to gain an insight into the origin of this unusual behaviour using Na₃OBr as a model system.  They first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; they then identified the presence of poorly crystalline impurities (not detectable by XRD), and elucidated their effect on ionic conductivity.

These findings improve understanding of the processing-structure-properties relationships pertaining to NaRAPs and highlight the need to determine those relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes.

Read the full paper in Angewandte Chemie: 'On the origin of the non-Arrhenius Na-Ion Conductivity in Na₃OBr'.

* A team from this department, The National Institute for Materials Science in Tsukuba, Diamond Light Source, The Faraday Institution, Ulsan National Institute of Science and Technology in South Korea and Oxford Chemistry department