Non‐Flammable Fluorinated Phosphorus(III)‐Based Electrolytes for Advanced Lithium‐Ion Battery Performance

• Published in: ChemElectroChem Vol. 7; no. 6; pp. 1499 - 1508
• Main Authors: Aspern, Natascha, Leissing, Marco, Wölke, Christian, Diddens, Diddo, Kobayashi, Takeshi, Börner, Markus, Stubbmann‐Kazakova, Olesya, Kozel, Volodymyr, Röschenthaler, Gerd‐Volker, Smiatek, Jens, Nowak, Sascha, Winter, Martin, Cekic‐Laskovic, Isidora
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 16.03.2020
• Subjects: Anode effect; cathode-electrolyte interphase; Cycles; DFT calculations; Electrolytes; Electrolytic cells; Flame retardants; Flammability; Functional materials; Lithium batteries; Lithium-ion batteries; non-flammable non-aqueous aprotic electrolytes; phospholane molecules; Product safety; solid-electrolyte interphase; Solvents
• DOI: 10.1002/celc.202000386
• ISSN: 2196-0216

In the quest for ever higher energy and power densities of lithium‐based batteries, numerous functional materials are being utilized, however in many cases their highly reactive nature is likely to increase the risk of danger in case of battery failures. This especially affects the aprotic non‐aqueous organic carbonate‐based electrolyte, still considered as the state‐of‐the‐art (SOTA) and its volatile and highly flammable components. Efforts to identify different forms of flame‐retardants or nonflammable electrolyte solvents/co‐solvents to reduce the risk of fire or explosion are inevitably followed by a trade‐off between the improved safety and deteriorated overall cycling performance of a battery. Here, we report on a smartly tailored, multifunctional nonflammable electrolyte formulation comprising 15.0 wt.% 2‐(2,2,3,3,3‐pentafluoro‐propoxy)‐4‐(trifluormethyl)‐1,3,2‐dioxaphospholane (PFPOEPi‐1CF3), significantly advancing the cycling performance of the NMC111||graphite cells by formation of an effective interphase on/at both anode and cathode and correlate its performance to the 2‐(2,2,3,3,3‐pentafluoropropoxy)‐1,3,2‐dioxaphospholane (PFPOEPi) containing electrolyte counterpart by establishing a strong structure‐reactivity‐performance‐relationship. A safer electrolyte: The state‐of‐the‐art nonaqueous aprotic electrolytes still cope with the well‐known challenges, among which high flammability and electrolyte decomposition stand for the most critical ones. Here, we report on fluorinated phosphorus‐based multifunctional electrolyte co‐solvent(s), which results in a nonflammable, organic carbonate‐based electrolyte formulation, and at the same time outperforms the state‐of‐the‐art counterpart in respect to overall electrochemical performance.