Electrochemical performance of electrochemical capacitors prepared with activated carbons from sugarcane bagasse

Abstract

Sugarcane bagasse waste was valorized as a precursor to synthesize activated carbon (AC) for supercapacitor electrodes. The ACs were prepared using H₃PO₄ (1–4 mol L⁻¹) followed by thermal treatment at 700 °C, yielding AC-1, AC-2, and AC-4. Among them, AC-4 exhibited the best electrochemical performance. SEM and TEM analyses showed a rough, porous morphology with a surface area of 790.5 m² g⁻¹, micropore area of 497.7 m² g⁻¹, and micropore volume of 0.23 cm³ g⁻¹. FTIR, Raman, and XPS revealed functional groups and aromatic structures enhancing conductivity and electrolyte interaction. AC-4 showed moderate structural disorder with balanced graphitic/amorphous phases. In a three-electrode cell, it delivered a specific capacitance of 266 F g⁻¹, while in a coin cell, it reached 33.9 F g⁻¹ at 0.1 A g⁻¹. It retained 82.41% capacitance after 14 500 cycles and achieved 267.69 W kg⁻¹ power and 1.15 Wh kg⁻¹ energy density, confirming its promise for sustainable energy storage.