Organothiols for dual-interface modification of high performance lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries are considered as one of the most likely to be the next generation energy storage systems. However, the shuttle effect and interface instability of lithium metal anode plague their electrochemical performance. Researchers have made great efforts to solve these issues by introducing suitable electrolyte additives. Herein, we find a new electrolyte additive, Trithiocyanuric acid (TMT), greatly improving the Li-S battery electrochemical performance. The TMT decreases the polysulfides concentration in the electrolyte and inhibits the shuttle effect by changing the reaction pathway of active materials. Moreover, a stable solid electrolyte interphase (SEI) formed on the lithium metal anode with TMT enables the Li/Cu cell with an overpotential of about 0.02 V at a current density of 0.5 mA cm−2 for over 500 h. Li-S batteries with TMT show an extremely high reversible capacity of 674.5 mAh g−1 after 300 cycles at 0.5C and a low capacity fading rate of 0.12% per cycle for 300 cycles. Most importantly, Li-S pouch cells (300 Wh kg−1) with TMT exhibit stable long cycle with a high specific capacity of 602 mAh g−1 after 170 cycles at 0.1C, which greatly promotes the practical applications of Li-S batteries. This work demonstrates that multi aspect modifying together can better realize high-performance Li-S batteries.