Comparative Study of Lithium Halide-Based Electrolytes for Application in Lithium-Sulfur Batteries

Among the next-generation energy storage technologies, lithium-sulfur batteries are considered one of the most appealing solutions owing to their remarkable theoretical capacity. However, to become commercially competitive, there is a strong need to address some issues still characterizing this technology. One of the explored strategies is the optimization of the electrolyte formulation. To this aim, we compared 1,3-dioxolane/1,2-dimethoxyethane-based electrolytes containing two lithium halides, i.e., lithium bromide (LiBr) and lithium iodide (LiI), with lithium bis (trifluoromethane)sulfonylimide (LiTFSI) as a reference electrolyte. The obtained results show how the donicity of the lithium-salt anions might affect the solid electrolyte interphase stability and the lithium sulfide deposition morphology, therefore influencing the electrochemical performance of the cells. Among the tested electrolytes, the sulfur cell containing LiBr salt exhibited the best electrochemical performance maintaining a specific capacity of 900 mAh g(-1) at C/4 and a stable trend along cycling at 1C with a specific capacity of about 770 mAh g(-1) for 200 cycles.

Automated summary

Lithium-sulfur batteries are considered as one of the most appealing solutions among the next-generation energy storage technologies due to their remarkable theoretical capacity. However, to become commercially competitive, some issues still need to be addressed, and one of the strategies explored is the optimization of the electrolyte formulation. The results show that the donicity of the lithium-salt anions might affect the stability of the solid electrolyte interphase and the lithium sulfide deposition morphology, thereby influencing the electrochemical performance of the cells. Among the tested electrolytes, the sulfur cell containing LiBr salt exhibited the best electrochemical performance, maintaining a specific capacity of 900 mAh g(-1) at C/4 rate and a stable trend along cycling at 1C rate with a specific capacity of about 770 mAh g(-1) for 200 cycles.