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Influence of Complexing Additives on the Reversible Deposition/Dissolution of Magnesium in an Ionic Liquid

Weber, Isabella; Ingenmey, Johannes; Schnaidt, Johannes; Kirchner, Barbara; Behm, R. Jürgen

Abstract:
Aiming at a fundamental understanding of the synergistic effects of different additives on the electrochemical Mg deposition/dissolution in an ionic liquid, we have systematically investigated these processes in a combined electrochemical and theoretical study, using 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMP‐TFSI) as the solvent and a cyclic ether (18‐crown‐6) and magnesium borohydride as additives. Both crown ether and BH4− improve Mg deposition, its reversibility, and cycling stability. The combined presence of both additives and their concentration relative to that of Mg$^{2+}$ are decisive for more facile and reversible Mg deposition/dissolution. These results and those of quantum chemical calculations indicate that 18‐crown‐6 can partly displace TFSI− from its direct coordination to Mg$^{2+}$. Furthermore, the interaction between Mg$^{2+}$ and directly coordinated TFSI− is weakened by coordination with 18‐crown‐6, preventing its Mg$^{+}$‐induced decomposition. Finally, Mg deposition is improved by the weaker overall coordination upon Mg$^{2+}$ reduction to Mg$^{+}$.

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Verlagsausgabe §
DOI: 10.5445/IR/1000129838
Veröffentlicht am 05.03.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Helmholtz-Institut Ulm (HIU)
Post Lithium Storage (POLiS)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 2196-0216
KITopen-ID: 1000129838
Erschienen in ChemElectroChem
Verlag Wiley
Band 8
Heft 2
Seiten 390-402
Schlagwörter magnesium batteries; magnesium; complexing additives; electrochemistry; quantum chemical calculations
Nachgewiesen in Scopus
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