Fundamental Insights from a Single-Crystal Sodium Iridate Battery

Sanja Tepavcevic, Hong Zheng, David G. Hinks, Baris Key, Logan Ward, Zhi Lu, Konstantinos Stoumpos, Yang Ren, John W. Freeland, Christopher Wolverton, Patrick Phillips, Robert Klie, John F. Mitchell*, Nenad M. Markovic

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Electrochemically driven chemical transformations play the key role in controlling storage of energy in chemical bonds and subsequent conversion to power electric vehicles and consumer electronics. The promise of coupling anionic oxygen redox with cationic redox to achieve a substantial increase in capacities has inspired research in a wide range of electrode materials. A key challenge is that these studies have focused on polycrystalline materials, where it is hard to perform precise structural determinations, especially related to the location of light atoms. Here a different approach is utilized and a highly ordered single crystal, Na2−xIrO3 is harnessed, to explore the role of defects and structural transformations in layered transition metal oxide materials on redox-activity, capacity, reversibility, and stability. Within a combined experimental and theoretical framework, it is demonstrated that 1) it is possible to cycle Na2−xIrO3, offering proof of principle for single-crystal based batteries 2) structural phase transitions coincide with Ir 4+/Ir 5+ redox couple with no evident contribution from anionic redox 3) strong irreversibility and capacity fade observed during cycling correlates with the Na + migration resulting in progressive growth of an electrochemically inert O3-type NaIrO3 phase.

Original languageEnglish (US)
Article number1903128
JournalAdvanced Energy Materials
Volume10
Issue number10
DOIs
StatePublished - Mar 1 2020

Keywords

  • electrochemical synthesis
  • oxygen redox
  • polycrystalline powders
  • single-crystals
  • structural and redox behavior
  • structural defects

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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