Integrating Polar and Conductive Fe2O3-Fe3C Interface with Rapid Polysulfide Diffusion and Conversion for High-Performance Lithium-Sulfur Batteries.

A low-cost in situ formed Fe2O3-Fe3C heterostructure highly dispersed in carbon nanofiber was delicately designed via a facile one-pot electrospinning method. The intense anchoring (by Fe2O3) and rapid electron transfer (by Fe3C) for lithium polysulfides transformation can be simultaneously achieved on the Fe2O3-Fe3C heterostructure interface, thus preventing the amassment of lithium polysulfides benefiting from its excellent interfacial contact and improving sulfur utilization. Experimental characterizations and DFT calculations confirmed the restrained polysulfides shuttle and enhanced redox kinetics. Therefore, the battery containing optimal Fe2O3-Fe3C heterostructure delivered a high capacity of 776.2 mA h g-1 after 300 cycles at 1 C at a low fading rate of 0.037% per cycle. Even at a high sulfur loading of 3.5 and 4.5 mg cm-2, high capacities of 773.6 and 533.6 mA h g-1 at 0.5 C can be achieved with capacity retentions of 91.7 and 94.2%, respectively. This distinctive heterostructure proposes an effective design of high-performance lithium-sulfur batteries contributing to the excellent electrochemical performance, which can synergize the virtues of effectively adsorptive metal oxides and appealing conductive metal carbides.