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

In this paper, TMT forms a stable SEI on the anode surface while modifying the cathode side interface improving the cycle life and discharge specific capacity of lithium-sulfur batteries. [Display omitted] •Thiol groups have been found to promote the conversion of polysulfides.•TMT forms a stable SEI film on the anode surface to suppress the shuttle effect.•Li-S batteries with TMT exhibit a low capacity decay rate of 0.12% per cycle.•Li-S pouch cells (300Wh kg−1) with TMT show stable long-term cycling performance. 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.