Catalytically altering the redox pathway of sulfur in propylene carbonate electrolyte using dual-nitrogen/oxygen-containing carbon

Abstract

Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries (LSBs) because of their successful implementation in commercial Li-ion batteries. The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs. However, regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions. In this study, we report a catalytic redox mechanism of sulfur in propylene carbonate (PC) electrolyte based on a comparison study. The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon, which largely prevents side reactions between polysulfides and the carbonate electrolyte. Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte. Favorable dual N/O functional groups are identified via a density functional theory study. This work provides an alternative route for enabling LSBs in carbonate electrolytes.