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Importance of Superstructure in Stabilizing Oxygen Redox in P3-Na0.67Li0.2Mn0.8O2

Published version
Peer-reviewed

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Authors

Kim, EJ 
Maughan, PA 
Bassey, EN 
Clément, RJ 
Ma, LA 

Abstract

jats:titleAbstract</jats:title>jats:pActivation of oxygen redox represents a promising strategy to enhance the energy density of positive electrode materials in both lithium and sodium‐ion batteries. However, the large voltage hysteresis associated with oxidation of oxygen anions during the first charge represents a significant challenge. Here, P3‐type Najats:sub0.67</jats:sub>Lijats:sub0.2</jats:sub>Mnjats:sub0.8</jats:sub>Ojats:sub2</jats:sub> is reinvestigated and a ribbon superlattice is identified for the first time in P3‐type materials. The ribbon superstructure is maintained over cycling with very minor unit cell volume changes in the bulk while Li ions migrate reversibly between the transition metal and Na layers at the atomic scale. In addition, a range of spectroscopic techniques reveal that a strongly hybridized Mn 3d–O 2p favors ligand‐to‐metal charge transfer, also described as a reductive coupling mechanism, to stabilize reversible oxygen redox. By preparing materials under three different synthetic conditions, the degree of ordering between Li and Mn is varied. The sample with the maximum cation ordering delivers the largest capacity regardless of the voltage windows applied. These findings highlight the importance of cationic ordering in the transition metal layers, which can be tuned by synthetic control to enhance anionic redox and hence energy density in rechargeable batteries.</jats:p>

Description

Funder: Powder Diffraction at the Australian Synchrotron


Funder: Australian Nuclear Science and Technology Organization


Funder: Engineering Physical Sciences Research Council


Funder: National Productivity Interest Fund


Funder: Center for Functional Nanomaterials


Funder: Brookhaven National Laboratory; Id: http://dx.doi.org/10.13039/100006231

Keywords

layered structures, oxygen redox, P3 structure, sodium-ion batteries, superstructures

Journal Title

Advanced Energy Materials

Conference Name

Journal ISSN

1614-6832
1614-6840

Volume Title

Publisher

Wiley
Sponsorship
Diamond (CY26699)
Faraday Institution (FIRG018)
Australian Research Council (DP170100269, DP200100959, FT200100707)
EPSRC (EP/L000202)
Basic Energy Sciences (DE‐AC02‐98CH10866)
Diamond Light Source (CY26699)