Vanadium nitride decorated nitrogen-doped graphene with abundant active sites as S host in lithium sulfur batteries for enhanced cyclability and rate performance

Lithium–sulfur batteries (LSBs) are considered one of the most promising energy storage systems due to their high theoretical capacity, low cost, and eco-friendliness. However, the slow reaction kinetics of the sulfur cathode and the polysulfide shuttle effect remain major challenges in the practical application of LSBs. The use of catalytic materials is an effective strategy to adsorb and accelerate the conversion of lithium polysulfides (LiPSs), addressing the root cause of problems associated with the sulfur cathode. However, enhancing the active sites of catalytic materials remains a critical challenge in lithium-sulfur catalytic processes. Here, vanadium nitride ultrafine nanocrystals decorated nitrogen-doped graphene (VN@NG) was synthesized using a polymer-template method via a one-step reaction. The small size and uniform distribution of VN contribute to the full exposure of catalytically active sites. Catalytic performance tests coupled with theoretical analysis show that VN@NG possesses strong LiPSs adsorption and excellent catalytic conversion properties. Benefiting from these advantages, LSBs using VN@NG as sulfur hosts exhibit excellent C-rate performance, high sulfur loading, and good cycling stability. This study provides significant reference for exploring other high-active-site metal nitrides for advanced LSBs.