Construction of SnS2-modified multi-hole carbon nanofibers with sulfur encapsulated as free-standing cathode electrode for lithium sulfur battery

Abstract

Lithium–sulfur (Li–S) batteries exhibit a huge potential in energy storage devices for the thrilling theoretical energy density (2600 Wh kg−1). Nevertheless, the serious shuttle effect rooted in polysulfides and retardative hysteresis reaction kinetics results in inferior cycling and rate performances of Li–S batteries, impeding commercial applications. In order to further promote the energy storage abilities of Li–S batteries, a unique binder-free sulfur carrier consisting of SnS2-modified multi-hole carbon nanofibers (SnS2-MHCNFs) has been constructed, where MHCNFs can offer abundant space to accommodate high-level sulfur and SnS2 can promote the adsorption and catalyst capability of polysulfides, synergistically promoting the lithium-ion storage performances of Li–S batteries. After sulfur loading (SnS2-MHCNFs@S), the material was directly applied as a cathode electrode of the Li–S battery. The SnS2-MHCNFs@S electrode maintained a good discharge capacity of 921 mAh g−1 after 150 cycles when the current density was 0.1 C (1 C = 1675 mA g−1), outdistancing the MHCNFs@S (629 mAh g−1) and CNFs@S (249 mAh g−1) electrodes. Meanwhile, the SnS2-MHCNFs@S electrode still exhibited a discharge capacity of 444 mAh g−1 at 2 C. The good performance of SnS2-MHCNFs@S electrode indicates that combining multihole structure designation and polar material modification are highly effective methods to boost the performances of Li–S batteries.