Diluted High Concentration Electrolyte with Dual Effects for Practical Lithium-sulfur Batteries

Abstract Lithium-sulfur (Li-S) battery, with their inherent advantages of high-energy density, low-cost, and eco-friendliness, shows promise as next-generation energy storage system. However, the practical Li-S batteries are far from achieving high-energy density and stable operation, because of the irreversible loss of active materials in both Li anode and S cathode. Herein, a modified diluted high concentration electrolyte (MDHCE) was designed for the practical Li-S batteries, which achieves a high energy density of 325 Wh kg–1 and stable cycling. Such an electrolyte enables a hybrid interface with high stability and fast Li-ion transport, thus improving the reversibility of Li anode and ameliorative kinetics of S cathode. The practicability of the MDHCE is further demonstrated in a 0.4 Ah Li-S pouch cell, which presents no obvious capacity fading with a steady Coulombic efficiency of 99.6%. This work not only provides guidance for electrolyte design, but also shines new lights towards practical high energy density Li-S batteries.