Structural Stabilization of P2‐type Sodium Iron Manganese Oxides by Electrochemically Inactive Mg Substitution: Insights of Redox Behavior and Voltage Decay

Junghoon Yang, Annalise Maughan, Glenn Teeter, Bertrand Tremolet de Villers, Seong-Min Bak, Sang-Don Han

Research output: Contribution to journalArticlepeer-review

19 Scopus Citations

Abstract

Layered P2-type Na0.8Mn0.5Fe0.5O2 cathode material is a promising candidate for next-generation sodium-ion batteries due to the economical and environmentally benign characteristics of Mn and Fe. The poor cycling stability of the material, however, is still a problem that must be solved. To address the problem, electrochemically inactive Mg2+ was introduced into the structure by substituting some of the Fe ions. It was shown that Mg substitution led to a smoother voltage profile with improved cycling performance and rate capability. These observations were attributed to the suppressed structural changes during electrochemical processes. Detailed redox mechanisms, associated local structural changes, and phase transitions were investigated by X-ray absorption spectroscopy and X-ray diffraction. From the detailed analysis of electrochemical behaviors, it was also identified how the redox reactions and structural disordering occurred in the high- and low-voltage regions and how Mg substitution stabilized the structure.

Original languageAmerican English
Pages (from-to)5972-5982
Number of pages11
JournalChemSusChem
Volume13
Issue number22
DOIs
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020 Wiley-VCH GmbH

NREL Publication Number

  • NREL/JA-5900-77397

Keywords

  • layered sodium iron manganese oxides
  • Mg substitution
  • phase transition
  • redox behavior
  • voltage decay

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