Abstract

As appetite steadily grows for sustainable in the same vein high-performance need for better energy storage has sparked a surge of research into activated carbon-based supercapacitor electrodes derived from biomass. They have attracted immense interest due to its cost-effectiveness, natural abundance, eco-friendly synthesis, from agricultural waste, fruit peels, and plant residues exhibits tunable porosity, a substantial surface area-rich surface and active sites, making it highly suitable for electrochemical applications. The synthesis of ACB/g-C3N4/NiO nanocomposite involved the use of Ni(NO3)2, NaOH, melamine, banana peel waste, HCl, KOH, PVDF, ? (C2H2F2)n ?), carbon black, and N-methyl-2-pyrrolidone. Banana peel waste as a cost-effective and eco-friendly precursor was used to synthesize activated carbon (ACB) and was subsequently combined with g-C3N4 and NiO to form a hybrid nanocomposite with enhanced electrochemical performance. Electrochemical performance of ACB/g-C3N4/NiO shows a high specific capacitance of 883.26 Fg?1 at 1 Ag?1, excellent cycling stability with 94.21% retention over 5000 cycles in three-electrode system. ACB/g-C3N4/NiO device demonstrated an energy density of 57.84 Wh?kg?1 and power density of 3838.87 Wkg?1, highlighting its excellent charge storage capability. The electrode maintains exceptional cycling stability, a remarkable 92.82% capacitance retention was observed after 10,000 cycles, confirming the long term. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.