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Delocalized electron holes on oxygen in a battery cathode

DOI: 10.1038/s41560-023-01211-0 DOI Help

Authors: Robert A. House (University of Oxford) , Gregory J. Rees (University of Oxford) , Kit Mccoll (University of Bath) , John-Joseph Marie (University of Oxford) , Mirian Garcia-Fernandez (Diamond Light Source) , Abhishek Nag (Diamond Light Source) , Ke-Jin Zhou (Diamond Light Source) , Simon Cassidy (University of Oxford) , Benjamin J. Morgan (University of Bath) , M. Saiful Islam (University of Oxfor) , Peter G. Bruce (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Energy , VOL 149

State: Published (Approved)
Published: February 2023
Diamond Proposal Number(s): 25589

Abstract: Oxide ions in transition metal oxide cathodes can store charge at high voltage offering a route towards higher energy density batteries. However, upon charging these cathodes, the oxidized oxide ions condense to form molecular O2 trapped in the material. Consequently, the discharge voltage is much lower than charge, leading to undesirable voltage hysteresis. Here we capture the nature of the electron holes on O2− before O2 formation by exploiting the suppressed transition metal rearrangement in ribbon-ordered Na0.6[Li0.2Mn0.8]O2. We show that the electron holes formed are delocalized across the oxide ions coordinated to two Mn (O–Mn2) arranged in ribbons in the transition metal layers. Furthermore, we track these delocalized hole states as they gradually localize in the structure in the form of trapped molecular O2 over a period of days. Establishing the nature of hole states on oxide ions is important if truly reversible high-voltage O-redox cathodes are to be realized.

Journal Keywords: Batteries; Electrochemistry; Materials chemistry

Diamond Keywords: Batteries

Subject Areas: Materials, Chemistry, Energy

Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)

Added On: 22/02/2023 09:02

Discipline Tags:

Energy Storage Energy Physical Chemistry Energy Materials Chemistry Materials Science

Technical Tags:

Scattering Resonant Inelastic X-ray Scattering (RIXS)