Biomass-Derived Micro-Mesoporous Carbon with Oxygen Functional Groups for High-Rate Na–S Batteries at Room Temperature

Room-temperature sodium–sulfur batteries are potential candidate for sustainable large-scale energy storage systems due to their high energy density and low cost. However, the shuttling effect of high-order polysulfides (Na 2 S n , 4 < n ≤ 8) usually leads to rapid capacity fading, while the reaction kinetics of low-order polysulfides (Na 2 S n , 1 ≤ n ≤ 4) are slow. In this work, microporous-mesoporous carbon derived from mangosteen peels is reported as cathode materials for RT Na–S batteries. The designed micro-mesoporous structure not only effectively suppresses the shuttling effect of sodium polysulfides (NaPS), but also has high electrical conductivity and porosity, which facilitates electron/ion diffusion. Oxygen functional groups on the surface provide high catalytic activity for efficient low-order NaPS conversion. The obtained Na–S battery exhibits high reversible capacity with excellent long-term cycle performance (526.1 mAh g −1 at 4 A g −1 after 1000 cycles) and outstanding rate performance (676.59 mAh g −1 at 16 A g −1 ). This work demonstrates a novel activation strategy of biomass-derived carbons for high-performance Na–S batteries.