Large-Scale Synthesis Of Fe9s10/Fe3o4@C Heterostructure As Integrated Trapping-Catalyzing Interlayer For Highly Efficient Lithium-Sulfur Batteries

The shuttle effect of soluble lithium polysulfides (LiPSs) and sluggish electrocatalysis of polysulfides conversion lead to severe capacity decay and poor rate capability, which is a determining factor for limiting the practical applications of lithium-sulfur (Li-S) batteries. To address such issues, a novel core-shell Fe9S10/Fe3O4@C architecture with well-defined heterointerfaces as a multifunctional polysulfides barrier for Li-S batteries is reported here. The spherical Fe9S10/Fe3O4@C heterostructure can be prepared by spray-drying technology on a large-scale and followed by a one-pot in-situ carbothermal reaction. With both physical entrapments by carbon shells and strong chemical interaction with Fe9S10/Fe3O4 heterostructure cores, this constructed dense-packing architecture alleviates the shuttle effect. The mechanisms involved in the Fe9S10/Fe3O4@C trapping interlayer are confirmed by both experimental results and density functional theory (DFT) calculations. Moreover, due to its high conductivity and intrinsic catalytic activity, the Fe9S10/Fe3O4@C facilitates fast electron/ion transport and greatly improves the conversion of LiPSs. Benefit from the integrated trapping-catalyzing effect, the Li-S cell constructed with a Fe9S10/Fe3O4@C interlayer exhibits enhanced cycling stability (a low capacity fading rate of 0.08% per cycle for 500 cycles at 1 C) and outstanding rate performance (660 mAh g-1 at 5 C). Even under a high areal sulfur loading of 3 mg cm-2, the high discharge capacity and capacity retention ratio can also be obtained. This work offers an insight into the construction of multi-functional heterostructures for high-performance Li-S batteries.