LAUSR

Lithium-sulfur (Li-S) batteries are severely suffered from the shuttling of soluble polysulfides intermediates, the insulation of sulfur and lithium sulfides, and volumetric expansion of sulfur electrodes, which result in the fast capacity decay and low utilization of active materials. To overcome these issues, a new type of porous phthalazinone-based covalent triazine frameworks (P-CTFs) with inherent N, O-atoms have been in-situ grown onto conductive reduced graphene oxide (rGO) by the sulfur-mediated cyclization of dinitrile monomers to afford S/P-CTFs@rGO hybrids. The well-designed structure endows the S/P-CTFs@rGO composites with several features for enhanced Li-S batteries: (i) the nanoporous structure could spatially trap the sulfur species within the P-CTFs; (ii) the covalent binding of sulfur and polar groups of phthalazinone and triazine in P-CTFs exhibit strong chemical attachment and adsorption with polysulfides, and further limit the diffusion of polysulfides; (iii) the conductive rGO and semi-conductive P-CTFs help faster electronic transportation and accelerated electrochemical process. Therefore, the S/P-CTFs@rGO cathodes show greatly enhanced electrochemical performances with a high initial specific capacity of 1130 mAh g-1 at 0.5 C, and a good capacity retention of 81.4% after 500 cycles, indicating an only 0.04% degradation per cycle.