Chitosan-derived N-doped porous carbon with fiber network structure for advanced lithium‑sulfur batteries

Abstract

The flexible design and construction of advanced carbon-based sulfur hosts contribute to the rapid redox and reaction kinetics of lithium polysulfides (LiPSs) in lithium‑sulfur batteries (LSBs), laying the foundation for the next generation of high-energy density energy storage devices. Herein, chitosan (CS)-derived porous N-doped carbon with fiber network structure was prepared by a simple freeze-drying method combined with sintering process. The effect of inorganic salt additives on the morphology of CS-derived carbon was investigated by SEM. The types and contents of N-doping were investigated through XPS analysis. The influence of morphology and N content on the performance of LSBs has been explored in detail through cycling and CV testing. In addition, the true active sites in the CS-derived carbon were determined by XPS and first principles calculations. As an active species, pyrrolic N exhibits superior adsorption energy and the most suitable degradation energy barrier for LiPSs. As the optimal electrode, the performance of LSBs under different electrolyte to sulfur (E/S) conditions was further investigated to explore the potential application of CS-KOH electrodes in high-energy density batteries. The results unveil that the influence of E/S on Li2S deposition is quite significant, with a limit of 5 μL mg−1. This work provides a new strategy for the preparation of high-performance advanced carbon-based materials with fiber network structures from polysaccharide biomass, and also promotes the application of CS in energy storage.