Highly Stable and Conductive 1,3-Dioxolane/Hydrocarbon Based Electrolyte Solvent for Advanced Lithium-Sulfur Batteries

Developing effective electrolytes is crucial for boosting the performance of Lithium-Sulfur (LiS) rechargeable battery. Recent improvements in electrolyte formulations have enhanced cyclability by increasing electrochemical stability at the electrode interfaces. However, achieving both high ionic conductivity (σ) and stability at these interfaces simultaneously remains a significant challenge. In this study, we utilized a strategy to suppress polysulfide dissolution by employing a mixture of 1,3-dioxolane (DOL) and hydrocarbon solvents with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte salt. Compared to the conventional electrolyte solution, which is 1 M LiTFSI salt in a 50/50 vol % mixture of DOL and dimethoxy ethane (DME), the LiTFSI electrolyte with DOL/hydrocarbon solvents demonstrate better cycling stability, compatibility with the Li-metal anode, and a high specific discharge capacity (Csp). Among the various DOL/hydrocarbon and LiTFSI electrolyte salts, the combination of DOL and n-hexane, a linear hydrocarbon, with LiTFSI electrolyte salt, (DnH40LiTFSI) exhibits remarkable σ (6.5×10⁻³ S/cm at 30 °C), compatibility with the Li-metal anode, an initial Csp of ca. 1264 mAh/g, cycling stability (Csp and Coulombic efficiency are 811 mAh/g and 98.09 % after 120 cycles) at 0.1 C by forming a good protective layer on the Li-metal surface and preventing polysulfide dissolution.