Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2.
- Maitra U Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- House RA Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Somerville JW Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Tapia-Ruiz N Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Lozano JG Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Guerrini N Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Hao R Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Luo K Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Jin L Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Pérez-Osorio MA Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Massel F Department of Physics and Astronomy, Division of Molecular and Condensed Matter Physics, Uppsala University, Box 516, S-751 20 Uppsala, Sweden.
- Pickup DM School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK.
- Ramos S School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK.
- Lu X Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
- McNally DE Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
- Chadwick AV School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK.
- Giustino F Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Schmitt T Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
- Duda LC Department of Physics and Astronomy, Division of Molecular and Condensed Matter Physics, Uppsala University, Box 516, S-751 20 Uppsala, Sweden.
- Roberts MR Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- Bruce PG Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
- 2018-02-21
Published in:
- Nature chemistry. - 2018
English
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 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li+-O(2p)-Li+ interactions). Na2/3[Mg0.28Mn0.72]O2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg2+ 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, Na2/3[Mg0.28Mn0.72]O2 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 Mg2+ remains in Na2/3[Mg0.28Mn0.72]O2, which stabilizes oxygen.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1038/nchem.2923
- PMID 29461536
- Persistent URL
- https://sonar.ch/global/documents/68946
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