Antisolvent‐Regulated Anionic Coordination Enabling Stable Li Metal Anode in Urea‐Based Electrolyte

Abstract

AbstractThe fabrication of NO3− anion‐participating solvation sheaths to derive inorganic‐rich solid electrolyte interphase (SEI) layers is critical for enhancing the stabilization of lithium metal batteries (LMBs). However, the application of LiNO3 salt is limited by its low solubility and the challenge of controlling NO3− coordination, primarily due to its high donor number. Herein, we demonstrate an antisolvent‐enhanced anionic coordination effect in urea‐based LiNO3 electrolytes for boosting the cycling stability of LMBs. We find that the incorporation of 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether (TTE) into these electrolytes enhances the interaction between the NO3− anion and urea‐based solvent to Li+ in the solvation sheath, resulting in an increase in ion‐pair formation. This also induces a transformation of the NO3− anion from a monodentate to a bidentate coordination configuration, facilitating preferential nitrate reduction at the anode interface. The optimized electrolyte formulation demonstrates remarkable cycling stability in lithium metal anode, achieving 6000 h of operation in a Li||Li cell and a high Coulombic efficiency of 99.6% in a Li||Cu cell. In full‐cell testing, Li||LiFePO4 cells (N/P = 3) maintain 88% capacity retention after 100 cycles at 0.2C.