The proposed supramolecular deep eutectic electrolyte (DEE) based on LiTFSI, acetamide and boric acid, improving the oxidation voltage up to 4.5 V, and enhancing the solution phase discharge mechanism by forming Li-bonds and H-bonds with Li+ and O2 −. The introduction of boric acid also promotes the formation of inorganic-rich SEI, which induces Li+ uniform deposition. The Li−O2 battery with this DEE delivers ultrahigh discharge capacity, improved cycling performance and intrinsic safety.
Abstract
Li−O2 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−O2 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.
