Stable Lithium Oxygen Batteries Enabled by Solvent-diluent Interaction in N,N-dimethylacetamide-based Electrolytes.

Abstract

In the pursuit of next-generation ultrahigh-energy-density Li-O₂ batteries, it is imperative to develop an electrolyte with stability against the strong oxidation environments. N,N-dimethylacetamide (DMA) is a recognized solvent known for its robust resistance to the highly reactive reduced oxygen species, yet its application in Li-O₂ batteries has been constrained due to its poor compatibility with the Li metal anode. In this study, a rationally selected hydrofluoroether diluent, methyl nonafluorobutyl ether (M3), has been introduced into the DMA-based electrolyte to construct a localized high concentration electrolyte. The stable -CH₃ and C-F bonds within the M3 structure could not only augment the fundamental properties of the electrolyte but also fortify its resilience against attacks from O₂ ^- and ¹O₂. Additionally, the strong electron-withdrawing groups (-F) presented in the M3 diluent could facilitate coordination with the electron-donating groups (-CH₃) in the DMA solvent. This intermolecular interaction promotes more alignments of Li⁺-anions with a small amount of M3 addition, leading to the construction of an anion-derived inorganic-rich SEI that enhances the stability of the Li anode. As a result, the Li-O₂ batteries with the DMA/M3 electrolyte exhibit superior cycling performance at both 30 °C (359^th) and -10 °C (120^th).