Promoting Strong Adsorption and Fast Conversion of Polysulfides in Li-S batteries Based on Conductive Sulfides Host with Hollow Prism Structure and Surface Defects

The chemical binding between metal compounds and polysulfides provides a good solution to inhibit shuttle effect in Li-S batteries. However, the Sabatier principle predicts that overly strong adsorption will commonly hinder the conversion of polysulfides, so building the synergetic effect mechanism between strong adsorption and fast conversion for polysulfides is a significant strategy. To realize this goal, in this study, the defect-enriched Co9S8 hollow prisms (DHCPs) as both S host and catalyst material for Li-S batteries are designed. Based on in situ UV-vis spectroscopy results, it is found that DHCPs can profitably promote the generation of S-3(center dot-) radicals during the discharge process. In the case of the relatively high conversion barrier of liquid-liquid reaction, the generated S-3(center dot-) radicals are responsible for the fast conversion reaction via a unique reaction pathway. When the sulfur loading is 4.63 mg cm(-2), the cell with DHCP/S cathode delivers a high areal capacity of 4.75 mAh cm(-2) at 0.1 C and keeps a high capacity of 2.99 mAh cm(-2) after 100 cycles at 0.5 C. This study provides a positive attempt to achieve strong adsorption and fast conversion of polysulfides simultaneously, which will convincingly boost the development and practical process of Li-S batteries.

Automated summary

This study designs defect-enriched Co9S8 hollow prisms as both S host and catalyst material for Li-S batteries, achieving strong adsorption and fast conversion of polysulfides. The experiment shows that the material can effectively promote the generation of S-3(center dot-) radicals and realize fast conversion through a unique reaction pathway. Under certain conditions, the cell with this material exhibits high capacity and cycling stability, which is of great significance for the development of Li-S batteries.