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Oxygen Activity in Li-Rich Disordered Rock-Salt Oxide and the Influence of LiNbO$_{3}$ Surface Modification on the Electrochemical Performance

Cambaz, M. A.; Vinayan, B. P.; Geßwein, H.; Schiele, A.; Sarapuolva, A.; Diemant, T.; Mazilkin, A.; Brezesinski, T.; Behm, R. J.; Ehrenberg, H.; Fichtner, M.

Li-rich disordered rock-salt oxides such as Li$_{1.2}$Ni$_{1/3}$Ti$_{1/3}$Mo$_{2/15}$O$_{2}$ are receiving increasing attention as high-capacity cathodes due to their potential as high-energy materials with variable elemental composition. However, the first-cycle oxygen release lowers the cycling performance due to cation densification and structural reconstruction on the surface region. This work explores the influence of lithium excess on the charge compensation mechanism and the effect of surface modification with LiNbO$_{3}$ on the cycling performance. Moving from a stoichiometric LiNi$_{0.5}$Ti$_{0.5}$O$_{2}$ composition toward Li-rich Li$_{1.2}$Ni$_{1/3}$Ti$_{1/3}$Mo$_{2/15}$O$_{2}$, oxygen redox is accompanied by oxygen release. Thereby, cationic charge compensation is governed by the Ni$^{2+/3+}$ and Mo$^{3+/6+}$ redox reaction. Contrary to the bulk oxidation state of Mo$^{6+}$ in the charged state, a mixed Mo valence on the surface is found by XPS. Furthermore, it is observed that smaller particle sizes result in higher specific capacities. Tailoring the surface properties of Li$_{1.2}$Ni$_{1.3}$Ti$_{1/3}$Mo$_{2/15}$O$_{2}$ with a solid electrolyte layer of LiNbO$_{3}$ altered the voltage profile, resulting in a higher average discharge voltage as compared to the unmodified material. ... mehr

Postprint §
DOI: 10.5445/IR/1000096239/post
Veröffentlicht am 28.05.2020
DOI: 10.1021/acs.chemmater.8b04504
Zitationen: 17
Zitationen: 17
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Materialien - Energiespeichersysteme (IAM-ESS)
Institut für Nanotechnologie (INT)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2019
Sprache Englisch
Identifikator ISSN: 0897-4756, 1520-5002
KITopen-ID: 1000096239
HGF-Programm 37.01.01 (POF III, LK 01) Fundamentals and Materials
Erschienen in Chemistry of materials
Verlag American Chemical Society (ACS)
Band 31
Heft 12
Seiten 4330-4340
Vorab online veröffentlicht am 22.05.2019
Schlagwörter 2017-019-020610 TEM FIB
Nachgewiesen in Web of Science
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