Synthetic perylenequinone as anchoring center of sulfur and catalyst for polysulfides conversion

Lithium-sulfur batteries (LSBs) with high theoretical specific capacities are one of the most promising energy storage systems for the next generation. However, the issues of shuttle effect and poor cycle stability seriously hold off their commercialization. In this work, the organic molecule of perylenequinone (6,12-dihydroxyperylene-1,7-dione, DPD) was anchored on the surface of carbon material through π-π interaction and the prepared composite was applied as the cathode of LSBs. The combination of theory and experiment proved that the π-π interaction between DPD and carbon materials can overcome the solvation effect of DPD in organic electrolytes, which provided a prerequisite for the stable existence of DPD in the long-cycle process of LSBs. The further density functional theory (DFT) calculations indicated that both carbonyl and hydroxyl groups in DPD can form Li-O bonds with Li to covalently fix polysulfides, and the interacting mechanism was revealed by in-situ infrared spectroscopy. The prepared S@DPD/C electrode exhibited an initial discharge specific capacity of 625.3 mAh g⁻¹ at 1C current density. A good cycling stability was observed at high current region with a capacity decay rate of 0.069% per cycle for 500 cycles.