Activation of anion redox in P3 structure cobalt-doped sodium manganese oxide via introduction of transition metal vacancies

Eun Jeong Kim, Kenza Mofredj, David Pickup, Alan Chadwick, John Thomas Sirr Irvine, Robert Armstrong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
1 Downloads (Pure)

Abstract

Additional capacity delivered by oxygen redox activity may in principle represent a means of enhancing the electrochemical performance of layered sodium transition metal oxides. However, irreversible structural changes occurring during cycling typically cause significant capacity fade with limited reversibility of oxygen redox processes. Here, P3-structure Na0.67Co0.2Mn0.8O2 was synthesised under two different reaction conditions. Both materials exhibit very stable cycling performance in the voltage range 1.8-3.8 V where the redox couples of transition metals entirely dominate the electrochemical reaction. For the compound prepared under more oxidising conditions, anion redox activity is triggered in the wider voltage window 1.8-4.4 V in a reversible manner with exceptionally small voltage hysteresis (20 mV). The presence of vacancies in the transition metal layers is shown to play a critical role not only in generating unpaired O 2p states but also in stabilising the crystal structure in the high voltage region.
Original languageEnglish
Article number229010
JournalJournal of Power Sources
Volume481
Early online date20 Oct 2020
DOIs
Publication statusPublished - 1 Jan 2021

Keywords

  • Sodium ion batteries
  • Layered oxides
  • Oxygen redox
  • Transition metal vacancies
  • P3 structure

Fingerprint

Dive into the research topics of 'Activation of anion redox in P3 structure cobalt-doped sodium manganese oxide via introduction of transition metal vacancies'. Together they form a unique fingerprint.

Cite this