Nitrogen and sulfur self-doped porous carbon from brussel sprouts as electrode materials for high stable supercapacitors

Heteroatom self-doped porous carbon materials were synthesized for the first time via freeze drying technique, followed by carbonization of brussel sprouts under a nitrogen atmosphere. The resultant materials were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) measurements. Brussel sprouts carbonized at 800 degrees C exhibit superior capacitive performance, including specific capacitance of 255 F g(-1) at a current density of 0.5 A g(-1), high rate capability (83% capacitance retention from 0.5 A g(-1) to 50 A g(-1)), and good cycle life (99.5% maintained over 5000 cycles). The highly stable electrochemical performance could be due to the hierarchical porous structure combined with the high specific surface area and heteroatom doping efforts.