Electrochemical evaluation of honeycomb-structured activated carbon prepared from Maranta arundinacea bagasse fiber for supercapacitor applications

Biomass-derived carbon materials are increasingly being explored for energy storage applications due to their environmental compatibility, renewability, and cost-effectiveness. This work proposes a sustainable strategy to address the growing demand for green energy storage systems by converting agricultural waste into high-performance supercapacitor electrodes. Activated carbon was prepared from bagasse obtained from Maranta arundinacea (arrowroot tuber, ART), selected for its low cost, abundant availability, and potential to enhance power delivery characteristics. The ART bagasse was first carbonised at 800 °C under a nitrogen atmosphere to obtain the carbon material (AR). Subsequent activation was performed at 600, 700, 800, and 900 °C, yielding samples denoted AR 600, AR 700, AR 800, and AR 900, respectively. Comprehensive structural and surface characterisation was performed using XRD, Raman spectroscopy, FT-IR, FE-SEM, HR-TEM, BET, and XPS analysis. Among the prepared materials, AR 800 exhibited the highest specific surface area of 2553 m² g^− 1, as determined by BET analysis. Electrochemical measurements revealed that AR 800 delivered superior capacitive performance, achieving a specific capacitance of 336 F g^− 1 at a current density of 1 A g^− 1 in a three-electrode system. This optimized material was further assembled into a symmetric supercapacitor device, which demonstrated a specific energy of 7.4 Wh kg^− 1 and a specific power of 1300 W kg^− 1 at 1 A g^− 1. The device maintained 95.4 % of its initial capacitance and a coulombic efficiency of 95.6 % after 20,000 charge–discharge cycles. Additionally, the fabricated symmetric supercapacitor successfully powered LED lights at various operating voltages, highlighting its practical applicability.