Chitin-Derived Heteroatom-Doped Porous Carbon for High-Performance Room-Temperature Na-S Batteries

Porous carbon derived from biomass is considered as a promising active electrode material for the next-generation energy storage systems. Herein, carbon particles with a hierarchical structure are fabricated from chitin through a facile pyrolysis/activation process, which is loaded with sulfur (S) as the cathode material in a room-temperature sodium–sulfur (RT Na-S) battery. Owing to the large specific surface area, enriched microporous structure, and nitrogen and oxygen-self-doping, the obtained carbon particles can not only provide abundant active sites for energy storage and rapid ion transport channels but also improve the utilization of S. Consequently, the S-cathode achieves an excellent cycle stability of 230 mAh g–1 at a current density of 1 A g–1 after 2000 cycles with a capacity retention of ∼94%. According to the kinetic analysis and density functional theory calculation, the unique and robust structure of carbon particles enables physical encapsulation and chemical confinement of S and polysulfides (PSs), which can strengthen Na+ adsorption and diffusion. Therefore, this work established a universal technique for producing high-performance S-cathode materials, which may offer the potential for economical energy storage in RT Na-S batteries.