Synergistic Ternary Solvent and Mixed Lithium Salts Enable Stable Li Anodes and Long-Life Li–O2 Batteries via Solvation Regulation

The composition of the electrolyte in lithium–oxygen (Li–O2) batteries, including the types and concentrations of lithium salts and the ratio of solvents, plays a decisive role in the nucleation and decomposition pathways of Li2O2, and the stability of the solid electrolyte interphase (SEI) on the lithium metal anode. Electrolytes based on single solvents or lithium salts struggle to simultaneously achieve high ionic conductivity, a wide electrochemical window, and a stable electrode/electrolyte interface. This study proposes a coupling optimization strategy based on the synergistic effects of a ternary solvent and multicomponent lithium salt anions. Molecular dynamics (MD) simulations, Raman spectroscopy, transport measurements, and electrochemical and surface analyses reveal competitive coordination and complementary film-forming pathways. The electrolyte exhibits an anodic stability window of approximately 4.8 V vs Li+/Li and forms a compositionally graded SEI with an inorganic Li3N–LiF-rich inner region and a flexible organic-rich outer region. Li–O2 cells achieve 209 cycles at a capacity limit of 1000 mAh g–1, an overpotential of 0.59 V, and a Coulombic efficiency (CE) of 98.18%. The coupled formulation balances oxygen-reaction kinetics and Li-metal interfacial stability, providing a basis for designing multifunctional electrolytes for long-life Li–O2 batteries.