Enhanced electrochemical performance and stability of biomass-derived activated carbon for supercapacitor applications

This study explores the synthesis of porous activated carbons (ACs) derived from the Calotropis procera fruit (CPF) using two activators, KOH and NaOH (CPF-AC_(KOH) and CPF-AC_(NaOH)), to produce low-cost and advanced electrode materials for high-performance supercapacitors. The findings indicate that CPF-AC_(KOH) and CPF-AC_(NaOH) form the best porous structures and combine micropores and mesopores. The Activation with NaOH favors mesopore formation more strongly than Activation with KOH. The CPF-AC_(KOH) exhibits the best specific surface area (2953.13 m² g⁻¹) with higher graphitization than that of CPF-AC_(NaOH). In a three-electrode system, CPF-AC _(KOH) and CPF-AC_(NaOH) demonstrate gravimetric-specific-capacitances of 341 and 286 F g⁻¹ at a current density of 1 A g⁻¹. CPF-AC_(KOH) at 0.1 A g⁻¹ reaches a peak gravimetric-specific-capacitance of 438 F g⁻¹, retaining 288 F g⁻¹ at 10 A g⁻¹. In a two-electrode, the CPF-AC_(KOH) demonstrates a high specific-energy of 41.1 Wh kg⁻¹ at a specific-power of 2489 W kg⁻¹. The efficient charge/discharge properties, low internal resistance, and powerful cycle stability, retaining 82 % of its capacitance after 10000 cycles at 5 A g⁻¹, highlight CPF-AC_(KOH) as a sustainable and environmentally friendly candidate for advanced supercapacitor applications and part of advancing energy-storage technologies.