Encapsulating Sulfur into a Gel-Derived Nitrogen-Doped Mesoporous and Microporous Carbon Sponge for High-Performance Lithium–Sulfur Batteries

Abstract

The practical application of Li–S batteries (LSBs) has long been impeded by the inefficient utilization of sulfur and slow kinetics. Utilizing conductive carbonaceous frameworks as a host scaffold presents an efficient and cost-effective approach to enhance sulfur utilization for redox reactions in LSBs. However, the interaction of pure carbon materials with lithium polysulfide intermediates (LiPSs) is limited to weak van der Waals forces. Hence, the development of an economical method for synthesizing heteroatom-doped carbon materials for sulfur fixation is of paramount importance. In this study, we introduce a hierarchical porous nitrogen-doped carbon sponge (NPCS) with an exceptionally high BET surface area of 3182.2 m2 g–1, achieved through a facile template-assisted polymerization method. The incorporation of inorganic salts, free radical polymerization, and deuteric freeze-drying techniques facilitates the formation of hierarchical pores within the NPCS. After sulfur fixation, the resulting S/NPCS electrode demonstrates remarkable electrochemical performance in LSBs. Specifically, it achieves an 80% sulfur utilization rate, maintains 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 that this work will inspire the rational design of cost-effective carbon-based electrodes for high-performance LSBs.

Hollow Defect-Rich Nanofibers as Sulfur Hosts for Lithium–Sulfur Batteries

“…In order to solve the above problems, researchers have proposed various solutions, among which the design of sulfur host materials with high adsorption capacity and catalytic activity is of great significance. − Carbon materials, with their easy-to-construct spatial structure and excellent electrical conductivity, have been widely used in lithium–sulfur battery cathode sulfur host materials research . However, carbon material, as a nonpolar material, has only a physical domain-limiting effect on polar LiPSs, and it is difficult to effectively chemically anchor polar LiPSs, resulting in a rapid capacity decay during charging and discharging, especially at high sulfur loading. − As a result, compound materials with polarity have gradually entered the researchers’ field of vision, divided into metal oxides, metal sulfides, metal selenides, etc. − These polar materials can not only effectively adsorb LiPSs but also promote the interconversion of various types of sulfur species during the reaction process, accelerating the redox kinetics of lithium–sulfur batteries. − Metal compounds are generally effective anchors for intermediates by generating metal–sulfur bonds with LiPSs. − By introducing defects into the material helps to expose more active sites, further enhancing the catalytic ability of the material for LiPSs while improving its conductivity. − The structure of perovskite-type materials has the general formula of ABO 3 , in which the A-site is an alkaline earth or rare earth metal, which mainly plays a supporting role, while the B-site is generally a transition metal element, which mainly plays a catalytic role in the material .…”