Highly active CeO2-x/Fe interfaces enable fast redox conversion of polysulfides for high-performance lithium-sulfur batteries

Abstract

The reasonable design of sulfur cathode to suppress “shuttling effect” and enhance conversion kinetics of polysulfides can promote the practical application of high energy density lithium-sulfur batteries. Herein, we design CeO2-x/Fe@NC with hexagonal bipyramidal structure which combines the merits of strong adsorptive CeO2-x and highly conductive Fe to realize smooth trapping–diffusion–conversion of LiPSs across the active CeO2-x/Fe interfaces. In addition, the mesoporous architecture facilitates the electrolyte infiltration and physically confine sulfur species. The ultrathin N-doped carbon layer, uniformly distributed Fe nanoparticles and oxygen deficient CeO2 nanoparticles not only establish a highly conductive network to promote the electron/ion transfer, but also offer strong physical and chemical confinement for LiPSs to alleviate “shuttling effect”. Attributed to the unique structure, the CeO2-x/Fe@NC-700-S cathode exhibits excellent rate capacity (637 mAh g−1 at 5C), superior cycling performance (82.1% capacity retention after 1000 cycles at 2C) and high areal capacity (5.1 mAh cm−2 at 0.1 C under high sulfur loading of 5 mg cm−2). This work could inspire constructing heterostructures with active metal-oxide interfaces for high-performance lithium-sulfur batteries.