Fe₃O₄-Decorated Porous Graphene Interlayer for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are seriously restrained by the shuttling effect of intermediary products and their further reduction on the anode surface. Considerable researches have been devoted to overcoming these issues by introducing carbon-based materials as the sulfur host or interlayer in the Li-S systems. Herein, we constructed a multifunctional interlayer on a separator by inserting Fe₃O₄ nanoparticles (NPs) in a porous graphene (PG) film to immobilize polysulfides effectively. The porous structure of graphene was optimized by controlling the oxidation conditions for facilitating ion transfer. The polar Fe₃O₄ NPs were employed to trap sulfur species via strong chemical interaction. By exploiting the PG-Fe₃O₄ interlayer with optimal porous structure and component, the Li-S battery delivered a superior cycling performance and rate capability. The reversible discharge capacity could be maintained at 732 mAh g^-1 after 500 cycles and 356 mAh g^-1 after total 2000 cycles at 1 C with a final capacity retention of 49%. Moreover, a capacity of 589 mAh g^-1 could also be maintained even at 2 C rate.