Unveiling the Entropic Effect of Electrolytes on Kinetics and Cyclability for Practical Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries under low-temperature and lean electrolyte conditions for practical application are hindered by a sluggish conversion reaction, low sulfur utilization, and cycling stability. Herein, we designed a high-entropy (HE) electrolyte by mixing three Li salts. The HE electrolyte simultaneously improves lithium sulfide (Li₂S) conversion reaction kinetics, sulfur utilization, and cyclability due to the anticlustering effect on lithium polysulfides, three-dimensional Li₂S growth, and robust anion-derived solid electrolyte interphase layer formation, respectively. Consequently, the HE electrolyte exhibits a high initial reversible capacity (1159.9 mAh g^-1) and cycling stability for 40 cycles under a low electrolyte-to-sulfur ratio (3.5 μL mg^-1) at the pouch cell level. In addition, the Li-S cell with HE electrolyte exhibits high cycling stability with a capacity decay of 0.01% per cycle during 200 cycles at -15 °C.