Encapsulating Sulfur\ninto a Gel-Derived Nitrogen-Doped\nMesoporous and Microporous Carbon Sponge for High-Performance Lithium–Sulfur\nBatteries

Abstract

The practical application of Li–S batteries (LSBs)\nhas long\nbeen impeded by the inefficient utilization of sulfur and slow kinetics.\nUtilizing conductive carbonaceous frameworks as a host scaffold presents\nan efficient and cost-effective approach to enhance sulfur utilization\nfor redox reactions in LSBs. However, the interaction of pure carbon\nmaterials with lithium polysulfide intermediates (LiPSs) is limited\nto weak van der Waals forces. Hence, the development of an economical\nmethod for synthesizing heteroatom-doped carbon materials for sulfur\nfixation is of paramount importance. In this study, we introduce a\nhierarchical porous nitrogen-doped carbon sponge (NPCS) with an exceptionally\nhigh BET surface area of 3182.2 m² g^–1, achieved through a facile template-assisted polymerization method.\nThe incorporation of inorganic salts, free radical polymerization,\nand deuteric freeze-drying techniques facilitates the formation of\nhierarchical pores within the NPCS. After sulfur fixation, the resulting\nS/NPCS electrode demonstrates remarkable electrochemical performance\nin LSBs. Specifically, it achieves an 80% sulfur utilization rate,\nmaintains a high reversible specific capacity of 400 mA h g^–1 even after 600 cycles at a demanding current density of 5.0 A g^–1, and exhibits superior rate capability. It is believed\nthat this work will inspire the rational design of cost-effective\ncarbon-based electrodes for high-performance LSBs.