Importance of superstructure in stabilizing oxygen redox in P3- Na0.67Li0.2Mn0.8O2

Eun Jeong Kim, Philip Maughan, Euan Bassey, Raphaële J. Clément, Le Anh Ma, Laurent C. Duda, Divya Sehrawat, Reza Younesi, Neeraj Sharma, Clare Grey, A. Robert Armstrong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)
7 Downloads (Pure)


Activation of oxygen redox represents a promising strategy to enhance the energy density of positive electrode materials in both lithium and sodium-ion batteries. However, the large voltage hysteresis associated with oxidation of oxygen anions during the first charge represents a significant challenge. Here, P3-type Na0.67Li0.2Mn0.8O2 is reinvestigated and a ribbon superlattice is identified for the first time in P3-type materials. The ribbon superstructure is maintained over cycling with very minor unit cell volume changes in the bulk while Li ions migrate reversibly between the transition metal and Na layers at the atomic scale. In addition, a range of spectroscopic techniques reveal that a strongly hybridized Mn 3d–O 2p favors ligand-to-metal charge transfer, also described as a reductive coupling mechanism, to stabilize reversible oxygen redox. By preparing materials under three different synthetic conditions, the degree of ordering between Li and Mn is varied. The sample with the maximum cation ordering delivers the largest capacity regardless of the voltage windows applied. These findings highlight the importance of cationic ordering in the transition metal layers, which can be tuned by synthetic control to enhance anionic redox and hence energy density in rechargeable batteries.
Original languageEnglish
Article number2102325
Number of pages12
JournalAdvanced Energy Materials
Issue number3
Early online date10 Dec 2021
Publication statusPublished - 21 Jan 2022


  • Layered structures
  • Oxygen redox
  • P3 structure
  • Sodium-ion batteries
  • Superstructures


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