Tailored activated carbon electrodes from sustainable charcoal for organic electrolyte supercapacitors

Four activated carbons (ACs), obtained by physical and chemical activation of locally sourced wood charcoal, were evaluated as sustainable and high-performance electrode materials for supercapacitors operating in an organic electrolyte (1M TEABF 4 in acetonitrile). The study provides a systematic comparison of electrode performance under identical testing conditions, including challenging high-current-density regimes often overlooked. The assembled devices demonstrated outstanding electrochemical performance over a wide temperature window (−25 °C to +45 °C). The best material achieved cell capacitances above 30 F g −1 (electrode capacitance, C e , over 120 F g −1 ) and 18 F cm −3 ( C e over 72 F cm −3 ) at 0.5 A g −1 and room temperature, storing up to 49 Wh·kg −1 , and outperforming the commercial reference YP-50F for these specific performance metrics. However, at current densities >20 A g −1 , samples with a predominantly microporous structure and low pore hierarchy experienced a sharp drop in performance, retaining only 11% of their initial capacitance. In contrast, ACs featuring mesopores around 4 nm in diameter showed superior capacitance retention up to 60%. These findings highlight the importance of tailored porous architectures, combining high specific surface area with hierarchical pore structures and well-defined mesopores to facilitate ion transport and ensure robust performance in organic electrolyte systems.