A novel phosphonium ionic liquid electrolyte enabling high-voltage and high-energy positive electrode materials in lithium-metal batteries

TitleA novel phosphonium ionic liquid electrolyte enabling high-voltage and high-energy positive electrode materials in lithium-metal batteries
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2021
AuthorsWu, F., Schür A.R., Kim G.-T., Dong X., Kuenzel M., Diemant T., D'Orsi G., Simonetti E., De Francesco M., Bellusci M., Appetecchi Giovanni Battista, and Passerini S.
JournalEnergy Storage Materials
Volume42
Pagination826-835
ISSN24058297
KeywordsAnodes, Electric discharges, Electrolytes, Energy, High-voltage lithium-metal battery, High-voltages, Ionic liquid electrolytes, Ionic liquids, Li metal, Li1.2ni0.2mn0.6O2, Lithium batteries, Lithium compounds, Lithium metals, Manganese compounds, Metals, Nickel compounds, Phosphonium cations, Phosphonium ionic liquid, Positive ions, Positive-electrode materials
Abstract

The synthesis of a new ionic liquid (IL), consisting of the symmetric tetra-butyl-phosphonium (P4444+) cation and the (nonafluorobutanesulfonyl)(trifluoromethanesulfonyl)imide (IM14–) anion, via a facile and environmentally-friendly aqueous route is reported. The novel P4444IM14 IL demonstrates excellent thermal and electrochemical stability (beyond 6 V vs. Li+/Li0 (against Ni-foil)) in combination with good near-room temperature conductivity and ionic liquid characteristics, such as non-measurable volatility and exceptional flame-retardant properties. Employed as electrolyte component in Li-metal cells together with the high-voltage, Li1.2Ni0.2Mn0.6O2 positive electrode material, enables an initial discharge capacity of 264 mA h g-1 at 12.5 mA g−1 and improved initial Coulombic efficiency. Additionally, the discharge capacity retention is promising (92.3% after 50 cycles and 84.4% after 100 cycles) when compared with using a conventional organic carbonate-based electrolyte (55.5% after 50 cycles). Further development of this ionic liquid electrolyte may facilitate the practical application of Li-metal anodes in high-voltage/high-energy lithium batteries. © 2021 Elsevier B.V.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85122645071&doi=10.1016%2fj.ensm.2021.08.030&partnerID=40&md5=02d22e0ad1dd08d28f1a566125357163
DOI10.1016/j.ensm.2021.08.030