Binary Mixtures of Highly Concentrated Tetraglyme and Hydrofluoroether as a Stable and Nonflammable Electrolyte for Li–O₂ Batteries

Abstract

Developing a long-term stable electrolyte is one of the most enormous challenges for Li-O batteries. Equally, the high flammability of frequently used solvents seriously weakens the electrolyte safety in Li-O batteries, which inevitably restricts their commercial applications. Here, a binary mixture of highly concentrated tetraglyme electrolyte (HCG4) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) was used for a novel electrolyte (HCG4/TTE) in Li-O batteries, which exhibit good wettability, enhanced ionic conductivity, considerable nonflammability, and high electrochemical stability. Being a co-solvent, TTE can contribute to increasing ionic conductivity and to improving flame retardance of the as-prepared electrolyte. The cell with this novel electrolyte displays an enhanced cycling stability, resulting from the high electrochemical stability during cycling and the formation of electrochemically stable interfaces prevents parasitic reactions occurring on the Li anode. These results presented here demonstrate a novel electrolyte with a high electrochemical stability and considerable safety for Li-O batteries.

Functionalization of 2D materials for enhancing OER/ORR catalytic activity in Li–oxygen batteries

“…Glyme-based material have been recognized as a promising electrolyte due to their good stability toward the oxidation potential of up to 4.0 V. The employment of glyme and ionic liquid-based electrolytes was found to lower the overpotential and enhance the cycle stability 21,22 . However, these materials suffer low ionic conductivity, and exhibit limited O 2 solubility.…”

Effects of Fluorinated Diluents in Localized High‐Concentration Electrolytes for Lithium–Oxygen Batteries

“…The LHCE was based on tetraethylene glycol dimethyl ether (G4) as the solvent because of its good stability and high reliability, and lithium trifluoromethanesulfonate (LiTf), a Li salt, which demonstrated stability in a previous study. [ 9b ] The effects of tris(2,2,2‐trifluoroethyl)orthoformate (TFEO), [ 10 ] TTE, [ 11 ] and 1 H ,1 H ,5 H ‐octafluoropentyl‐1,1,2,2‐tetrafluoroethyl ether (OTE) [ 12 ] diluents were investigated. A diluted concentration electrolyte (DCE), 1 m LiTf in G4, was included as a control electrolyte for comparison with the three LHCEs (TFEO‐LHCE, TTE‐LHCE, and OTE‐LHCE) prepared with the same molar ratio of LiTf, G4 and diluent at 1:1.75:3.5.…”

A Selection Rule for Hydrofluoroether Electrolyte Cosolvent: Establishing a Linear Free‐Energy Relationship in Lithium–Sulfur Batteries

“…For these new battery systems to be successful, it is critical to develop reliable electrolytes and to understand their working principles . First introduced as an electrolyte cosolvent a decade ago, hydrofluoroethers (HFEs) have rapidly been employed by researchers all over the world to construct functional electrolytes for high‐voltage lithium‐ion, lithium‐metal, lithium–sulfur (Li–S), lithium–air, lithium/selenium–sulfur, and even sodium‐ion batteries . Because of their low solvating ability, HFEs are exceptionally versatile as electrolyte cosolvents.…”