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 language | English (US) |
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Article number | 1903128 |
Journal | Advanced Energy Materials |
Volume | 10 |
Issue number | 10 |
DOIs | |
State | Published - Mar 1 2020 |
Funding
Work in the Materials Science Division of Argonne National Laboratory (materials synthesis, crystal growth, electrochemical studies, single crystal diffraction) was sponsored by the US Department of Energy Office of Science, Basic Energy Sciences, Division of Materials Science and Engineering. L.W. was supported by financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD). B.K. was supported by the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE‐AC02‐06CH11357. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE‐AC02‐06CH11357.
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
- General Materials Science