Fe3C composite carbon nanofiber interlayer for efficient trapping and conversion of polysulfides in lithium-sulfur batteries

The poor electrical conductivity of the sulfur electrode and the severe shuttle effect limit the practical application of current lithium-sulfur (Li-S) batteries. Therefore, we demonstrate a methodology to design and develop a multifunctional interlayer based on carbon nanofiber (CNF) with Fe3C nanoparticles (Fe3C-CNF), which can simultaneously improve the electrical conductivity and reduce the shuttling effect by entrapping soluble polysulfides. The three-dimensional network-like structure of the Fe3C-CNF interlayer with uniformly distributed Fe3C nanoparticles not only enables the efficient deposition of active materials but also enhances the electron transfer of sulfur species. The Fe3C nanoparticles can effectively reduce the interfacial resistance and enhance the kinetics of the redox reaction of the sulfur material as a catalyst. A Li-S battery with a Fe3C-CNF interlayer and a conventional cathode (prepared by merely blending sulfur and conductive carbon) exhibits a capacity of 941 mAh g(-1) and average Coulombic efficiency of 98.0% at 0.2 C. Even after 250 cycles at 1.0 C, the Li-S battery with the Fe3C-CNF interlayer exhibits a reversible discharge capacity of 804 mAh g(-1), with an average capacity decay of 0.091% per cycle. The methodology proposed herein aids in the development of next-generation Li-S batteries. (C) 2020 Elsevier B.V. All rights reserved.