$\beta-Na_{1.7}IrO_{3}$

Subtitle:a tridimensional Na-Ion insertion material with a redox active oxygen network

The revival of the Na-ion battery concept has prompted an intense search for new high capacity Na-based positive electrodes. Recently, emphasis has been placed on manipulating Na-based layered compounds to trigger the participation of the anionic network. We further explored this direction and show the feasibility of achieving anionic-redox activity in three-dimensional Nabased compounds. A new 3D beta-Na1.7IrO3 phase was synthesized in a two-step process, which involves first the electrochemical removal of Li from beta-Li2IrO3 to produce beta-IrO3, which is subsequently reduced by electrochemical Na insertion. We show that beta-Na1.7IrO3 can reversibly uptake nearly 1.3 Na+ per formula unit through an uneven voltage profile characterized by the presence of four plateaus related to structural transitions. Surprisingly, the beta-Na1.7IrO3 phase was found to be stable up to 600 degrees C, while it could not be directly synthesized via conventional synthetic methods. Although these Na-based iridate phases are of limited practical interest, they help to understand how introducing highly polarizable guest ions (Na+) into host rocksalt-derived oxide structures affects the anionic redox mechanism.

Publication year:2018

Keywords:A1 Journal article

BOF-keylabel:yes

BOF-publication weight:10

CSS-citation score:1

Authors:International

Authors from:Higher Education

Accessibility:Open