Triazine-based porous organic polymers with enhanced electronegativity as multifunctional separator coatings in lithium–sulfur batteries

The commercialization of lithium–sulfur batteries is seriously affected by the shuttle behavior and slow conversion kinetics of polysulfides. Herein, a new porous organic polymer (POP) is synthesized and grown on reduced graphene oxide (rGO) in situ to improve battery performance, which serves as an efficient polysulfide adsorber and catalytic promoter for polysulfide conversion. The polar POP shows strong chemisorption to polysulfides, which is confirmed by a series of calculations and experimental results. As a popular conductive substrate, rGO offers an electron transport channel for sulfur and polysulfide conversion. Due to the synergistic functions of composite materials, the batteries with POP@rGO modified separators retain a high specific capacity of 697.3 mA h g−1 and a minimum capacity fading rate of 0.04% per cycle at 1C over 500 cycles. Besides, even at a high sulfur loading of 5 mg cm−2, a high area capacity of 4.27 mA h cm−2 can also be achieved, which shows that it has great potential in promoting the commercialization of lithium–sulfur batteries.