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 (LiS) conversion reaction kinetics, sulfur utilization, and cyclability due to the anticlustering effect on lithium polysulfides, three-dimensional LiS 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) and cycling stability for 40 cycles under a low electrolyte-to-sulfur ratio (3.5 μL mg) 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.