Influence of Nitrogen in Sulfurized Polymer‐Based Cathode Materials on Electrochemical Performance in Lithium–Sulfur Batteries: Electrochemical and Computational Insights

Lithium–sulfur (Li–S) batteries are postulated as alternatives to existing Li‐ion battery technology; however, their practical use is often hampered by the polysulfide shuttle. Here, we report for the first time the use of sulfurized‐poly(styrene) (SPS) and sulfurized‐poly(vinylpyridine) (SPVP), each containing ≥60 wt.% covalently bound sulfur, as cathode materials for Li–S batteries, synthesized by a scalable method. The homogenously distributed covalently bound sulfur overcomes the shuttle effect, while the porous architecture synergistically coupled with a nanostructured morphology mitigates electrode pulverization. At C/2‐rate, SPS and SPVP exhibit high discharge capacities of 1250 and 1400 mAh g ⁻¹ , respectively, with >75% capacity retention after 700 cycles and a coulombic efficiency >98%. The presence of nitrogen atoms improves the capacity of SPVP compared to nitrogen‐free SPS by 12%, as the thioamide(─C(═S)─NH─) groups in SPVP facilitate reversible reduction/oxidation by serving as docking sites for polysulfide recuperation. Computational studies suggest that in SPVP, the first discharge step involves Li ⁺ coordination at the nitrogen sites, while thioamide groups promote Li ₂ S nucleation, resulting in a more favorable Gibbs free energy profile throughout all steps, up to full discharge, as compared to SPS. Overall, the results highlight the key role of nitrogen atoms, which contribute to the superior performance of SPVP.