β-Na1.7IrO3: A Tridimensional Na-Ion Insertion Material with a Redox Active Oxygen Network

Paul E. Pearce, Gwenaelle Rousse, Olesia M. Karakulina, Joke Hadermann, Gustaaf Van Tendeloo, Dominique Foix, François Fauth, Artem M. Abakumov, Jean Marie Tarascon

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

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 Na-based compounds. A new 3D β-Na1.7IrO3 phase was synthesized in a two-step process, which involves first the electrochemical removal of Li from β-Li2IrO3 to produce β-IrO3, which is subsequently reduced by electrochemical Na insertion. We show that β-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 β-Na1.7IrO3 phase was found to be stable up to 600 °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.

Original languageEnglish
Pages (from-to)3285-3293
Number of pages9
JournalChemistry of Materials
Volume30
Issue number10
DOIs
Publication statusPublished - 22 May 2018

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