High-Performance and High-Voltage Supercapacitors Based on N-Doped Mesoporous Activated Carbon Derived from Dragon Fruit Peels

Designing the mesopore-dominated activated carbon electrodes has witnessed a significant breakthrough in enhancing the electrolyte breakdown voltage and energy density of supercapacitors. Herein, we designed N-doped mesoporous-dominated hierarchical activated carbon (N-dfAC) from the dragon fruit peel, an abundant biomass precursor, under the synergetic effect of KOH as the activating agent and melamine as the dopant. The electrode with the optimum N-doping content (3.4 at. %) exhibits the highest specific capacitance of 427 F g(-1) at 5 mA cm(-2) and cyclic stability of 123% capacitance retention until 50000 charge-discharge cycles at 500 mA cm(-2) in aqueous 6 M KOH electrolytes. We designed a 4 V symmetric coin cell supercapacitor cell, which exhibits a remarkable specific energy and specific power of 112 W h kg(-1) and 3214 W kg(-1), respectively, in organic electrolytes. The cell also exhibits a significantly higher cycle life (109% capacitance retention) after 5000 GCD cycles at the working voltage of >= 3.5 V than commercial YP-50 AC (similar to 60% capacitance retention). The larger Debye length of the diffuse ion layer permitted by the mesopores can explain the higher voltage window, and the polar N-doped species in the dfAC enhance capacitance and ion transport. The results endow a new path to design high-capacity and high-working voltage EDLCs from eco-friendly and sustainable biomass materials by properly tuning their pore structures.

Automated summary

Designing N-doped mesoporous-dominated hierarchical activated carbon electrodes from abundant biomass precursors, using KOH as the activating agent and melamine as the dopant, leads to significant improvements in specific capacitance, cyclic stability, specific energy, and specific power of supercapacitors. These results demonstrate the potential of utilizing eco-friendly and sustainable biomass materials to develop high-performance energy storage devices with enhanced voltage windows and long cycle lives.