Organic Thiolate as Multifunctional Salt for Rechargeable Lithium-Sulfur Batteries

The practical application of lithium-sulfur (Li-S) batteries is hindered by the severe shuttle effect of soluble polysulfide intermediates and the unstable lithium anode interface. Conventional lithium salts (e.g., LiPF₆, LiTFSI) just serve as conducting salts to provide necessary free lithium cations for internal ion transport, lacking full utilization of the anions. Herein, lithium 4-fluorobenzenethiolate (F-PhSLi) as a multifunctional salt for rechargeable Li-S batteries, which is able to chemically react with sulfur to alter the redox pathway of sulfur cathode, accelerate the sulfur redox kinetics, and inhibit the shuttle effect of polysulfides is reported. Meanwhile, due to the redox activity of F-PhSLi, the reactive electrolyte can offer additional capacity. In addition, it also can construct a stable LiF-rich solid electrolyte interface layer on the lithium metal anode. Such reactive electrolyte endows Li-S batteries with ultrahigh discharge specific capacity, improved sulfur utilization, long-term storage ability, enhanced rate capability, and outstanding low-temperature performance. This work presents a new solution for developing high performance Li-S batteries.