Skip to main content

Oxygen redox chemistry without excess alkali-metal ions in Na\(_{2/3}\)[Mg\(_{0.28}\)Mn\(_{0.72}\)]O\(_2\)

Maitra, Urmimala, House, Robert A., Somerville, James W., Tapia-Ruiz, Nuria, Lozano, Juan G., Guerrini, Niccoló, Hao, Rong, Luo, Kun, Jin, Liyu, Pérez-Osorio, Miguel A., and others. (2018) Oxygen redox chemistry without excess alkali-metal ions in Na\(_{2/3}\)[Mg\(_{0.28}\)Mn\(_{0.72}\)]O\(_2\). Nature Chemistry, 10 . pp. 288-295. ISSN 1755-4330. E-ISSN 1755-4349. (doi:10.1038/nchem.2923) (KAR id:65829)

PDF Author's Accepted Manuscript
Language: English
Download (1MB) Preview
[thumbnail of Accepted version prior to publication Nature Chem 2018.pdf]
This file may not be suitable for users of assistive technology.
Request an accessible format
Official URL


The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2\(p\) orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li\(^+\)–O(2\(p\))–Li\(^+\) interactions). Na\(_{2/3}\)[Mg\(_{0.28}\)Mn\(_{0.72}\)]O\(_2\) exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg\(^{2+}\) resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na\(_{2/3}\)[Mg\(_{0.28}\)Mn\(_{0.72}\)]O\(_2\) does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg\(^{2+}\) remains in Na\(_{2/3}\)[Mg\(_{0.28}\)Mn\(_{0.72}\)]O\(_2\), which stabilizes oxygen.

Item Type: Article
DOI/Identification number: 10.1038/nchem.2923
Uncontrolled keywords: Physics of Quantum Materials
Subjects: Q Science > QC Physics
Divisions: Divisions > Division of Natural Sciences > School of Physical Sciences
Depositing User: Alan Chadwick
Date Deposited: 31 Jan 2018 15:20 UTC
Last Modified: 20 May 2021 11:10 UTC
Resource URI: (The current URI for this page, for reference purposes)
Ramos, Silvia:
  • Depositors only (login required):