High energy density hybrid supercapacitors based on graphitic carbon nitride modified BiFeO3 and biomass-derived activated carbon

One of the major challenges to the commercialization of supercapacitors (SCs) remains the low energy density, especially at high current densities. Electrode materials with a wide operating voltage and high capacitance are promising for addressing this challenge. Bismuth ferrite (BiFeO3) is utilized as a battery-type electrode which exhibits a wide voltage window and high specific capacitance by storing charge through reversible redox reactions. In this study, bismuth ferrite functionalized with graphitic carbon nitride (g-C3N4) is synthesized by hydrothermal and ball milling techniques to form the cathode for hybrid SCs. As anode, biowaste-derived activated carbon is synthesized from orange peels via a sequential carbonization and activation process. The device exhibits a high specific capacitance of 330 F/g, excellent energy density of 244.8 Wh kg−1 and power density of 1.155 kW kg−1 at a current density of 1 A g−1. An innovative pathway has been developed for designing and fabricating asymmetric supercapacitors with high energy density. The assembled device provides a high operating voltage window of 2.4 V, opening up new possibilities for high-voltage high performance energy storage devices.