A new fluorine-containing sulfone-based electrolyte for advanced performance lithium metal batteries

Lithium dendrite growth greatly limits the application of lithium metal batteries. Herein, a new fluorine-containing sulfone-based electrolyte is proposed for lithium metal batteries. Benefiting from the synergistic effect of lithium bis(fluorosulfonyl)imide (LiFSI) and fluoroethylene carbonate (FEC), a LiF-rich stable SEI with compact and uniform morphology is formed on lithium metal anode, suppressing the Li dendrite formation and enhance the cycling life. In Li||Cu half-battery, a remarkable Coulombic efficiency of 95.9 % within 130 cycles and 93.5 % within 100 cycles are realized at 0.5 mA·cm⁻² and 1 mA·cm⁻², respectively. In Li||Li symmetric battery, the cycling life is about 480 h at 1.0 mA·cm⁻² which is double as the commercial electrolyte. Moreover, in Li||LiFePO₄ battery, a significantly improved capacity retention of 94.3 % with a high average Coulombic efficiency of 99.8 % after 100 cycles is achieved at 0.5C. The designed new fluorine-containing sulfone-based electrolyte provides new strategy toward high energy density lithium metal batteries.