A supramolecular deep eutectic electrolyte enhancing interfacial stability and solution phase discharge in Li-O${}_2$ batteries

Li-O${}_2$ batteries (LOBs) have gained widespread recognition for their exceptional energy densities. However, a major challenge faced by LOBs is the lack of appropriate electrolytes that can effectively balance reactant transport, interfacial compatibility, and non-volatility. To address this issue, a novel supramolecular deep eutectic electrolyte (DEE) has been developed, based on synergistic interaction between Li-bonds and H-bonds through a combination of lithium salt (LiTFSI), acetamide (Ace) and boric acid (BA). The incorporation of BA serves as an interface modification additive, acting as both Li-bonds acceptor and H-bonds donor/acceptor, thereby enhancing the redox stability of the electrolyte, facilitating a solution phase discharge process and improving compatibility with the Li anode. Our proposed DEE demonstrates a high oxidation voltage of 4.5 V, an ultrahigh discharge capacity of 15225 mAh g${}^{-1}$ and stable cycling performance of 196 cycles in LOBs. Additionally, the intrinsic non-flammability and successful operation of a Li-O${}_2$ pouch cell indicate promising practical applications of this electrolyte. This research broadens the design possibilities for LOBs electrolytes and provides theoretical insights for future studies. (© 2024 Wiley-VCH GmbH)