Direct Tracking of Additive-Regulated Evolution on the Lithium Anode in Quasi-Solid-State Lithium-Sulfur Batteries

The complicated problems confronted by lithium (Li) anode hinder the practical application of quasi-solid-state lithium-sulfur (QSSLS) batteries. However, the interfacial processes and reaction mechanisms, which are still vague, pose challenges to disclose. Herein, the insoluble sulfides stacking and Li dendrites growth on the Li anode are real-time monitored via in-situ atomic force microscopy inside the working QSSLS batteries. In the LiNO3-added electrolyte, it is detected that the formation process of solid electrolyte interphase (SEI) involves two stages, forming loose nanoparticles (NPs, approximate to 102 nm) at the open circuit potential and dense NPs (approximate to 74 nm) during discharging owing to the synergism of Li polysulfides (LiPSs) and LiNO3. The compact SEI film not only blocks the erosion of LiPSs but also homogenizes the Li deposition behaviors, leading to the electrochemical performance enhancement of QSSLS batteries. These straightforward insights uncover the additive-manipulated morphological/chemical evolution and interfacial properties and thus facilitate the improvement of QSSLS batteries.