Achieving High-Performance Li-S Batteries via Polysulfide Adjoining Interface Engineering

Abstract

To realize lithium-sulfur (Li-S) batteries with high energy density, it is crucial to maximize the loading level of sulfur cathode and minimize the electrolyte content. However, excessive amounts of lithium polysulfides (LiPSs) generated during the cycling limit the stable operation of Li-S batteries. In this study, a high-loading S cathode with a three-dimensional (3D) network structure is fabricated using a simple pelletizing method, and the exhausting overcharging phenomenon, which occurs in the high-loading Li-S cell, is successively prevented by pretreating the lithium metal anode. Moreover, adding a diluent to the electrolyte containing viscous LiPSs enables the facile conversion between S species during the cycling of high-loading Li-S cells under lean electrolyte conditions. Finally, a prototype Li-S pouch cell with high energy density (427 Wh kg(-1)) was realized by combining a compacted 3D cathode with a high-loading, pretreated thin lithium metal and diluent-modified electrolyte. We believe that the results reported herein will be a good guideline to establish proper strategies to achieve high energy density Li-S batteries.