Organic Polysulfides Based on -S-S-S- Structure as Additives or Cosolvents for High Performance Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are presently attracting immense research interest on the global level due to their excellent specific capacity and energy density. However, the practical development of Li-S batteries has so far been hindered by a series of obstacles. To enhance the sulfur utilization rate and facilitate capacity performance of Li-S batteries, a new organosulfide, dimethyl trisulfide (DMTS, CH3S3CH3), as electrolyte additive or cosolvent was employed. Boosted capacities were demonstrated with appropriate amount of DMTS. Li-S batteries with 5% and 10% DMTS delivered discharge capacities of 1207(1st)/1009(100th) and 1648(1st)/1133(100th) mAh g(-1), respectively. Such high capacities are particularly attractive for Li-S batteries towards high energy density devices. The methyl-terminated polysulfides (DMTS and reaction products of DMTS/S-8) were supposed to contribute the extra capacity.