Waste-to-energy storage: Bio-Waste derived activated carbon from wood apple shell for symmetric electrochemical supercapacitors

A deep understanding of material properties continues to drive innovations in energy storage, particularly in the development of efficient, sustainable, and cost-effective electrode materials for supercapacitors. Among the different material choices, carbon-based materials have proven to be highly promising due to their excellent conductivity, surface area, and stability in real-world applications. In this context, biomass-derived carbons have gained growing attention as sustainable alternatives, owing to their natural abundance, rich carbon content, low cost, environmental friendliness, and potential for large-scale production. These materials not only reduce environmental waste but also offer a viable route to high-performance supercapacitor electrodes. In this study, we report the synthesis of porous activated carbon from wood apple shell, a naturally abundant biomass, using a simple hydrothermal method and KOH chemical activation to enhance its structural and electrochemical properties. The resulting carbon was thoroughly characterized to investigate its porous architecture, surface morphology, elemental composition, and electrochemical behaviour. The structure–property relationship and the influence of KOH activation on the material’s performance were critically analysed, demonstrating its suitability as an effective electrode material for symmetric supercapacitors. Electrochemical analysis in a three-electrode setup revealed a specific capacitance of 379 F g -1 at 1 A g -1 , along with remarkable cycling stability of 117% retention after 10,000 cycles at 10 A g -1 . In a two-electrode symmetric configuration, a specific capacitance of 92 F g -1 was also achieved at the same current density. • Activated carbon synthesized from wood apple shell via hydrothermal and KOH activation. • Biomass offers a green, low-cost, and scalable route for supercapacitor electrodes. • KOH activation improved surface area and porosity, boosting ion and charge transport. • Electrode showed 379 F g -1 at 1 A g -1 with 117 % retention after 10,000 cycles. • Symmetric supercapacitor delivered 92 F g -1 , showing promise for energy storage.