Unlocking solvation configuration in non-flammable fluorinated electrolytes enables aggressive high-voltage chemistries in lithium-metal batteries

● Non-flammability fluorinated electrolytes boost antioxidant activity and LMBs safety. ● Fluorinated electrolytes weaken the coordination between Li + and dipole. ● Advanced solvation structures promote ideal interfacial chemistry. ● The electrolyte is compatible with both Li metal anode and high-voltage cathode. Lithium metal batteries (LMBs) operated with high-voltage Ni-rich cathodes suffer from interphase fragility, electrolyte depletion, and safety concerns, which are tightly coupled to Li⁺ solvation chemistry. Here, guided by DFT screening and molecular dynamics analysis, we develop a nonflammable all-fluorinated electrolyte by co-solubilizing fluoroethylene carbonate (FEC) and bis(2,2,2-trifluoroethyl) carbonate (TFEC) at a 1:1 vol ratio. The relevant electrocatalyst weakens Li⁺-dipole interactions, reduces the solvent coordination number, and increases PF₆⁻ participation in the first solvation shell, thereby enabling anion-involved interfacial reactions. As a result, the relevant electrocatalyst with a tailored solvation configuration contributes to highly reversible Li plating/stripping with an average Coulombic efficiency of 98.4% over 300 cycles in Li||Cu cells and stable Li||Li cycling for over 900 h at 1 mA cm⁻ 2 . More importantly, Li||NCM811 full cells exhibit markedly improved high-voltage durability, retaining 60% of the initial capacity after 300 cycles at 4.3 V and 58% after 300 cycles at 4.6 V, with discharge capacities of 170.1 and 148.4 mAh g⁻¹ at 4 and 5 C, respectively. This work establishes a solvation structure-driven design principle for safe, high-voltage LMBs. The addition of TFEC solvent effectively adjusts the solvation configuration of the electrolyte and enhances the safety of Li metal batteries, further improving their high-voltage performance. Download: Download high-res image (232KB) Download: Download full-size image