Atomically Dispersed Fe–N–S-Doped Carbon as an Efficient Li–S Battery Host for Capturing Polysulfides

Lithium–sulfur batteries (LSBs) have emerged as promising candidates for advanced energy storage systems, due to their remarkable theoretical capacity of 1675 mAh g⁻¹ and specific energy density of 2600 Wh kg⁻¹, surpassing those of conventional Li-ion batteries. The abundance and cost-efficiency of sulfur make LSBs attractive in further. However, practical applications of LSBs face challenges such as the insulating nature of sulfur, migration of soluble lithium polysulfide (LIPS), and sluggish redox kinetics. Carbon-based materials have been explored to circumvent these barriers; however, their weak physical interactions limit their effectiveness. Heteroatom doping has shown the potential for anchoring LIPS; but optimization remains a challenge. In this study, we introduce a novel approach involving the synthesis of uniformly dispersed iron on activated carbon (AC, Ketjen black) as a support, yielding a single iron–nitrogen–sulfur-doped carbon (Fe–NSC) composite. This composite exhibited the following advantages as an LSB host: superior dispersion of the Fe catalyst, induced high surface area, and an increased proportion of Fe³⁺, which led to improved catalytic activity. These properties result in enhanced polysulfide capture and stable rate performance in the Fe–NSC-based LSBs.