On the origin of the non-Arrhenius Na-ion conductivity in Na3OBr

Journal article

The sodium-rich antiperovskites (NaRAPs) with composition Na₃OB (B=Br, Cl, I, BH₄, 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. In this work, we 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. We first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; then identified the presence of a 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 these relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes.

Authors: Darminto, B; Rees, GJ; Cattermull, J; Hashi, K; Diaz-Lopez, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Angewandte Chemie International Edition
• Volume: 62
• Issue: 51
• Article number: e202314444
• Place of publication: Germany
• Publication date: 2023-11-14
• Acceptance date: 2023-10-30
• DOI: 10.1002/anie.202314444
• EISSN: 1521-3773
• ISSN: 1433-7851
• Pmid: 37902095
• Language: English
• Keywords: poorly crystalline impurities; sodium antiperovskites; solid sodium-ion conductors; solid-state batteries; non-Arrhenius behaviour