Fluorine and Lithium: Ideal Partners for High‐Performance Rechargeable Battery Electrolytes

Abstract

Further enhancement in the energy densities of rechargeable lithium batteries calls for novel cell chemistry with advanced electrode materials that are compatible with suitable electrolytes without compromising the overall performance and safety, especially when considering high‐voltage applications. Significant advancements in cell chemistry based on traditional organic carbonate‐based electrolytes may be successfully achieved by introducing fluorine into the salt, solvent/cosolvent, or functional additive structure. The combination of the benefits from different constituents enables optimization of the electrolyte and battery chemistry toward specific, targeted applications. This Review aims to highlight key research activities and technical developments of fluorine‐based materials for aprotic non‐aqueous solvent‐based electrolytes and their components along with the related ongoing scientific challenges and limitations. Ionic liquid‐based electrolytes containing fluorine will not be considered in this Review.

An Anion‐Tuned Solid Electrolyte Interphase with Fast Ion Transfer Kinetics for Stable Lithium Anodes

“…After replacing EC/DEC to DME/FEC (Figure 5b), the energy barrier of Li + desolvation had slightly decreased due to weaker solvation of FEC compared with EC. [ 34 ] The Li + diffusion barrier across the SEI also be reduced. This can be ascribed to the increased content of LiF from FEC in addition to PF 6 − in the SEI, which enhanced the transport kinetics of Li + and produced less‐dendritic morphology.…”

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

“…The different increase in the CEI thickness between the phospholane containing cells can be explained by the different oxidation potentials (Figure S9). The introduction of the CF 3 group leads to an increased oxidation potential, as known from literature, resulting in a different decomposition mechanism . For the PFPOEPi containing electrolyte, the decomposition is mainly electrochemically induced, whereas, for the PFPOEPi‐1CF 3 containing counterpart it has a chemical nature.…”

“…The different increase in the CEI thickness between the phospholane containing cells can be explained by the different oxidation potentials ( Figure S9). The introduction of the CF 3 group leads to an increased oxidation potential, as known from literature, [13] resulting in a different decomposition mechanism.…”

“…The flammability of the considered electrolytes was determined by the self-extinguishing method (SET), in this case, mainly susceptible to phosphorus and fluorine atom(s) in the phospholane structure ( Figure 1b)). [13] Both atoms are able to scavenge hydrogen and hydroxyl radicals which evolve during combustion and thus inhibit the combustion chain reaction. [5] In addition, phosphorus is able to form a char layer, which prohibits heat transfer and volatile gases released into the atmosphere.…”

Fluoroalkylation of Diazo Compounds with Diverse Rfn Reagents

“…[3] Moreover, fluorinated polymers have played an indispensable role in modern life, which have found widespread applications as thermoplastics, elastomers, weatherproof coatings, biomedical materials, membranes, and others. [4] Fluorine can also be used as a diagnostic tool in positron emission tomography (PET) that employs 18 F-labeled radiotracers and in 19 F magnetic resonance imaging (MRI) that relies on polyfluorinated molecules. [5] In contrast to their wide applications in many fields of life and material sciences, only few naturally occurring fluorine-containing compounds have been identified.…”