Molecularly designed N, S co-doped carbon nanowalls decorated on graphene as a highly efficient sulfur reservoir for Li–S batteries: a supramolecular strategy

Abstract

Sulfur is among the most promising cathodes for next-generation high energy storage systems. However, its practical applications have been hindered by its insulating nature (i.e., S and its discharge product Li₂S), substantial volume changes, and detrimental shuttle effect (polysulfide intermediates). Nanostructured hosts with high conductivity and strong polysulfide entrapment are the prerequisites for high-capacity and long-cycle life Li–S batteries. Here, we report a carbonaceous host based on N, S co-doped carbon nanowall decorated graphene (NSCNW-G) via a supramolecular strategy, which simultaneously achieves abundant voids for sulfur species accommodation and fast redox kinetics of polysulfides. As a result, NSCNW-G/S delivers a high capacity of 1246 mA h g⁻¹ at 0.02C, superb cycling stability with an ultralow decay rate of 0.021% per cycle for as long as 800 cycles at 0.5C, and a stable coulombic efficiency of up to 98% with a high mass loading of approximately 80 wt%. Even with a high areal loading of 3.2 mg cm⁻², a capacity of 510 mA h g⁻¹ is still retained after 300 cycles at 0.5C. Our present supramolecular strategy demonstrates a feasible pathway to the rational design of advanced carbonaceous materials for Li–S batteries and other electrochemical applications.