Naturally O-N-S co-doped carbon with multiscale pore architecture derived from lotus leaf stem for high-performance supercapacitors

Abstract Lotus leaf stem is successfully exploited as a sustainable biomass to fabricate multi-heteroatom co-doped carbon with multiscale pore architecture by a readily scalable and effective strategy of pre-carbonization and KOH activation. By taking advantage of 3D hierarchical structure with high surface area and optimized pore size distribution, naturally O-N-S co-doping and nanosized graphitic structure (contributing to large accessible surface for charge storage, short ion diffusion distance, rapid charge transfer and low internal resistance), as-produced carbon is demonstrated as a promising electrode for supercapacitors with a high capacitance of 425 F/g at 0.5 A/g in a three-electrode system and 295 F/g at 0.1 A/g with superb rate capability (84% retention from 0.2 to 20 A/g) and outstanding recyclability (97.8% retention after 10000 charge-discharge cycles at 10 A/g) in a two-electrode system with KOH solution. The excellent recyclability of 93.3% is also achieved after 10000 cycles at 10 A/g for the symmetric supercapacitor using Na2SO4 electrolyte. These values may boost the commercial application of biomass-derived carbon for energy storage.