A rational design of the coupling mechanism of physical adsorption and chemical charge effect for high-performance lithium–sulfur batteries

Abstract

Lithium sulfur batteries are considered as potential energy storage systems for electrical devices owing to their high energy density, low cost, and environmental friendliness. However, the hasty capacity fading originating from the solution and migration of polysulfides is the major obstacle for their industrial application. The polysulfide adsorption and repulsion effect achieved by adding an extra coating layer on the side of the cathode and separator have been separately proved to be effective in mitigating the shuttle effect. Herein, a cooperative coated separator, which employs a hybrid carbon matrix as the coated material, including an appropriate ratio of N-doped activated conductive carbon and commercial acetylene black, and sulfonated polystyrene as the binder, is established to prevent the migration of polysulfides and serves as a secondary current collector to reutilize the active materials for high-performance lithium sulfur batteries. The research results showed that the coated separator with 50 wt% N-doped activated conductive carbon as the coating material and sulfonated polystyrene as the binder showed highlighted cycle performance, and 731 mA h g⁻¹ was maintained after 150 cycles at 800 mA g⁻¹(the capacity retention was 86.0%). The superior performance may be because the coated separator can efficiently restrain the polysulfides by physical and chemical effects and also reject the polysulfides by the anion electrostatic effect. In summary, this study provides a new cooperative way to address the shuttle effect and promotes the development of lithium sulfur batteries.