Stabilizing Lithium-Oxygen Batteries through In Situ Generated Phenyl/LiF-Rich Hybrid SEI Layer with Sulfonyl Fluoride Electrolyte Additive

Lithium-oxygen batteries have a wide application due to their ultra-high theoretical energy density. However, uncontrollable lithium dendrites and highly reactive oxygen species greatly cause the corrosion of lithium anodes and the degradation of the electrolytes. In our work, we introduce 4-Methylbenzenesulfonyl Fluoride (4-MBSF) as a highly efficient film-forming additive. It can form a stable inorganic-organic composite solid electrolyte interfacial layer and inhibit the growth of lithium dendrites to stabilize the lithium anode, thus dramatically enhancing the lives of lithium-oxygen batteries. The sulfonyl fluoride group of 4-MBSF can react with LiOH to form a LiF-rich protective layer on the lithium metal surface, which can improve stripping/deposition stability and ionic conductivity. Besides, the π -conjugation of the benzene ring can improve the flexibility of the SEI layer to accommodate volume changes of the lithium anode during cycling and inhibit the attacks of the reactive oxygen species. The cycle life of lithium-oxygen batteries with 4-MBSF is prolonged to 400 cycles.