Structural and Thermodynamic Understandings in Mn-Based Sodium Layered Oxides during Anionic Redox

Seok Mun Kang, Duho Kim, Kug Seung Lee, Min Seob Kim, Aihua Jin, Jae Hyuk Park, Chi Yeong Ahn, Tae Yeol Jeon, Young Hwa Jung, Seung Ho Yu, Junyoung Mun, Yung Eun Sung

Research output: Contribution to journalArticle

Abstract

A breakthrough utilizing an anionic redox reaction (O2−/On−) for charge compensation has led to the development of high-energy cathode materials in sodium-ion batteries. However, its reaction results in a large voltage hysteresis due to the structural degradation arising from an oxygen loss. Herein, an interesting P2-type Mn-based compound exhibits a distinct two-phase behavior preserving a high-potential anionic redox (≈4.2 V vs Na+/Na) even during the subsequent cycling. Through a systematic series of experimental characterizations and theoretical calculations, the anionic redox reaction originating from O 2p-electron and the reversible unmixing of Na-rich and Na-poor phases are confirmed in detail. In light of the combined study, a critical role of the anion-redox-induced two-phase reaction in the positive-negative point of view is demonstrated, suggesting a rational design principle considering the phase separation and lattice mismatch. Furthermore, these results provide an exciting approach for utilizing the high-voltage feature in Mn-based layered cathode materials that are charge-compensated by an anionic redox reaction.

Original languageEnglish
JournalAdvanced Science
DOIs
Publication statusAccepted/In press - 2020

Keywords

  • anionic redox
  • cathodes
  • sodium ion batteries
  • two-phase reactions

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Chemical Engineering(all)
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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  • Cite this

    Kang, S. M., Kim, D., Lee, K. S., Kim, M. S., Jin, A., Park, J. H., Ahn, C. Y., Jeon, T. Y., Jung, Y. H., Yu, S. H., Mun, J., & Sung, Y. E. (Accepted/In press). Structural and Thermodynamic Understandings in Mn-Based Sodium Layered Oxides during Anionic Redox. Advanced Science. https://doi.org/10.1002/advs.202001263