Fluorinated Ether Based Electrolyte for High-Energy Lithium-Sulfur Batteries: Li+ Solvation Role Behind Reduced Polysulfide Solubility

摘要

By employing new electrolytes, the polysulfide shuttle phenomenon, one of the main problems of lithiumsulfur (LiS) batteries, can be significantly reduced. Here we present excellent Coulombic efficiencies as well as adequate performance of high-energy LiS cells by the use of a fluorinated ether (TFEE) based electrolyte at low electrolyte loading. The observed altered discharge profile was investigated both by electrochemical experiments and an especially tailored COSMO-RS computational approach, while the details of the discharge mechanism were elucidated by two operando techniques: XANES and UVvis spectroscopy. A significant decrease of polysulfide solubility compared to tetraglyme is due to different Li+ solvation mode.