Effective adsorption and acceleration redox conversion towards lithium polysulfide by nanorod-like Sb-doped SnO2 nanofibers for high-performance lithium-sulfur battery

Abstract

Lithium-sulfur batteries (LSBs) have attracted increasing attention due to high theoretical energy density and low cost of sulfur. However, there are still many challenges regarding sulfur cathodes such as the “shuttle effect” of polysulfides, insulating properties of sulfur and Li2S2/Li2S, and the sluggish redox kinetics. In this study, the nanorod-like Sb-doped SnO2 nanofibers (ATO NFs) with hollow structure were prepared by the electro-blown spinning technology and calcination processes, and used as a sulfur host for cathode materials. The internal hollow structure and the nanorod-like structure on the surface of the nanofibers with the increased specific surface area are beneficial to load sulfur and improve transport channels of electrons and lithium ions. And the hollow nanofibers also can well accommodate to huge volume changes in the reaction process. More importantly, the ATO NFs with hollow structure have good physical confinement and chemical adsorption performance to polysulfides. Based on these merits, the ATO NFs composite cathode exhibits a high initial discharge specific capacity of 765.3 mAh g−1 and maintains 550.6 mAh g−1 after 900 cycles at a rate of 2 C with 1.9 mg cm−2 sulfur loading. More importantly, high initial area discharge specific capacity of the electrode is 5.5 mAh cm−2 at 0.1 C with sulfur loading of 5.6 mg cm−2. Even, at a rate of 0.2 C, the area capacity still is stabilized at 3.5 mAh cm−2 after 100 cycles. The work illustrates that the ATO NFs for LSBs exhibit good cycling stability over a long period of time, entering the ranks of high performance and ultra-stable capacity. And it also facilitate to expand the scope of application of ATO NFs in other related energy storage fields.