Multifunctional separator modified with catalytic multishelled structural CoS2 enables stable lithium-sulfur battery

Abstract

Lithium-sulfur battery has been considered as a promising next-generation energy storage device, due to its ultrahigh theoretical energy density and natural abundance of sulfur. However, the shuttle effect and sluggish redox kinetics of polysulfides hinder its commercial application. Herein, by combing the wise of material design and structure engineering, CoS₂ hollow multishelled structure (HoMS) is developed to modify separator and also to establish a “vice electrode”, which effectively hinders shuttle effect and catalyzes the redox reactions. CoS₂ HoMS can not only obstruct polysulfides through multiple shell barriers, but also provides a large available polar surface to effectively capture polysulfides. Additionally, CoS₂ HoMS with a good conductivity could greatly accelerates the redox conversion of polysulfides and enhances the decomposition of Li₂S. Moreover, these CoS₂ HoMS can buffer the large volume change of sulfur during cycling and ensure good contact and stability of electrodes. As a result, lithium-sulfur battery with CoS₂ HoMS modified separator exhibited a high discharge capacity of 873.1 mAh g₋₁ at a high rate of 1 C and delivered only 0.054% of capacity decay per cycle during 350 cycles.