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Highlighting the Reversible Manganese Electroactivity in Na‐Rich Manganese Hexacyanoferrate Material for Li‐ and Na‐Ion Storage [in press]

Mullaliu, Angelo; Asenbauer, Jakob; Aquilanti, Giuliana; Passerini, Stefano; Giorgetti, Marco

Abstract:
The electroactivity of sodium‐rich manganese hexacyanoferrate (MnHCF) material constituted of only abundant elements, as insertion host for Li‐ and Na‐ions is herein comprehensively discussed. This material features high specific capacities (>130 mAh g−1) at high potentials when compared to other materials of the same class, i.e., Prussian blue analogs. The reversible electronic and structural modifications occurring during ion release/uptake, which are responsible for such high specific capacity, are revealed herein. The in‐depth electronic and structural analysis carried out combining X‐ray diffraction and X‐ray absorption spectroscopy (XAS), demonstrates that both Fe and Mn sites are involved in the electrochemical process, being the high delivered capacity the result of a reversible evolution in oxidation states of the metallic centers (Fe3+/Fe2+ and Mn2+/Mn3+). Along with the Mn2+/Mn3+ oxidation, the Mn local environment experiences a substantial yet reversible Jahn–Teller effect, being the equatorial Mn‐N distances shrunk by 10% (2.18 Å → 1.96 Å). Na‐rich MnHCF material offers slightly higher performance upon uptake and release of Na‐ions (469 Wh kg−1) than Li‐ions (457 Wh kg−1), being, however, the electronic and structural transformation independent of the adopted medium, as observed by XAS spectroscopy.

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Originalveröffentlichung
DOI: 10.1002/smtd.201900529
Zugehörige Institution(en) am KIT Helmholtz-Institut Ulm (HIU)
Publikationstyp Zeitschriftenaufsatz
Jahr 2019
Sprache Englisch
Identifikator ISSN: 2366-9608, 2366-9608
KITopen-ID: 1000098731
Erschienen in Small methods
Seiten 1900529
Vorab online veröffentlicht am 25.09.2019
Nachgewiesen in Web of Science
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