Dense Li Deposition and Enhanced Flame-retardant Enabled by Localized Strong Ion-Dipole Interactions

Uncontrolled lithium (Li) deposition can lead to the formation of dendrites and "dead" Li, accelerating the degradation of cycling stability and safety performance in lithium metal batteries (LMBs). Herein, we propose a strategy to achieve dense Li deposition and flame-retardant by designing an electrolyte based on localized strong ion-dipole (LSID) interactions. The strong ion-dipole interactions between the multiple-dipole solvent (G4), NO₃ ^-, FSI^-, and Li⁺ promote the formation of Li⁺ primary solvation sheaths for stabilizing Li deposition behavior. While the weak dipole fluorine-containing diluent (TTE) is distributed in the secondary solvation sheath due to weak ion-dipole interactions of Li⁺-TTE to improve interfacial wettability and flame retardancy due to preferential separation. Consequently, the localized strong ion-dipole interactions strategy in the designed electrolyte successfully achieves a Coulombic efficiency of more than 99% for Li||Cu cells, and ultrathin Li-matched Li||LFP and Li||NCM523 cells also demonstrate excellent cycling stability, as well as an improved safety performance of LMBs.