Fluorosulfonyl Additive-Reinforced Interphases for High-Voltage and Fast-Charging Lithium Metal Batteries

Electrolytes capable of simultaneously stabilizing lithium metal anodes and high-nickel cathodes under high-voltage and high-rate operation are essential for practical lithium metal batteries yet remain difficult to realize. Here, methyl fluorosulfonyldifluoroacetate (MDFSA) is introduced as an electrolyte additive to regulate the Li+ solvation structure in an ether-carbonate co-solvent electrolyte. MDFSA weakens the coordination of 1,2-dimethoxyethane (DME) with Li+ and promotes the involvement of DFOB- in the solvation sheath, facilitating the formation of robust inorganic-rich interphases at both the lithium metal anode and the cathode. The optimized electrolyte enables Li||LiNi0.91Co0.06Mn0.03O2 cells to deliver 75.8% capacity retention after 500 cycles at 4.5 V and 1 C and 80.53% capacity retention after 500 cycles at 4.3 V and 4 C. These results highlight the effectiveness of fluorosulfonyl additive-enabled solvation and interphase regulation for improving the high-voltage stability, rate capability, and cycling durability of lithium metal batteries.