Nitrogen-rich fibrous carbon enabling polysulfide conversion for lithium–sulfur batteries

Abstract

Abstract The practical implementation of lithium–sulfur (Li–S) batteries is hindered by their poor rate performance and rapid capacity fade, primarily due to the sluggish kinetics of polysulfide conversion. To overcome these challenges, a nitrogen-rich fibrous carbon (NFC) material was synthesized using gelatin and g-C3N4 as raw materials through a stepwise pyrolysis process. The unique fibrous microstructure of NFC endows it with high ionic and electronic conductivities, facilitating rapid Li ion and electron transports. Furthermore, nitrogen doping increases the electrochemical performance of the Li–S battery by improving polysulfide adsorption and conversion kinetics. Consequently, the Li–S battery incorporated with NFC demonstrates significantly improved rate performance, exhibiting a high discharge specific capacity of 721 mAh g−1 at 4 C. Additionally, the pouch cell incorporating NFC displays a high average capacity of 821.6 mAh g−1 over 40 cycles at 0.1 C, with high cycling stability and a capacity retention rate exceeding 96%. These results highlight the effectiveness of NFC in improving the cycle longevity of Li–S batteries, thereby heralding a significant stride forward in their practical implementation in energy storage systems. Graphical Abstract

Keywords

• Nitrogen-rich fibrous carbon
• Gelatin
• Biomass carbon
• Lithium–sulfur battery
• Electrochemistry