Tuning electrochemical activation to enhance the performance of bio-derived carbon electrode materials for supercapacitors

Carbon-based electrode materials are widely used in high-performance supercapacitors due to their high surface area, conductivity, and stability. Among these, bio-derived carbons offer a sustainable and cost-effective alternative by utilizing organic waste. Electrochemical activation (EA) provides a simple, tunable, energy-efficient and cost-effective method to enhance carbon electrode performance by improving porosity and introducing oxygen functional groups. This study examines EA conditions for a series of binder-free electrodes to identify the optimal parameters while maintaining electrode mechanical stability. The optimized electrode achieved a specific capacitance of 461 F/g at a 20 mV/s scan rate, and 570 F/g at 1 mA current, with a capacitance retention of 95% after 1000 charge-discharge cycles in a three-electrode cell. Morphological and surface analysis using SEM, FTIR, XPS and Raman spectroscopy revealed enhanced defects and the development of quinone (C=O) functional groups, which explains the improved electrochemical performance tested using CV and GCD. These findings demonstrate the potential of optimized EA parameters compared to traditional physical activation methods, offering valuable insights for the development of sustainable, binder-free, high-performance electrodes for supercapacitors applications. Density functional theory (DFT) calculations were employed to elucidate the pseudocapacitive charge-storage mechanism, revealing that oxygen functional groups strongly favor proton adsorption, induce significant charge transfer, and generate additional electronic states near the Fermi level, providing theoretical support for pseudocapacitive behavior.