Comparative activation of pine pollen-derived carbon with KOH and CuCl₂ for high-performance supercapacitor electrodes

Biomass-derived porous carbons have emerged as promising candidates for high-performance supercapacitor electrodes owing to their low cost, sustainability, and tunable physicochemical properties. In this work, pine pollen, an abundant and underutilized natural precursor, was converted into porous carbon via hydrothermal carbonization followed by chemical activation using KOH and CuCl2. A systematic comparison of these activation agents was conducted to elucidate their effects on structural, morphological, and electrochemical characteristics. KOH activation produced carbon with a high specific surface area of 2030.32 m2/g and a specific capacitance of 230 F/g at 5 A/g, while CuCl2 activation yielded carbon with a surface area of 736.8 m2/g and a capacitance of 176 F/g. After 5000 charge-discharge cycles, capacitance retention was 76% for the KOH-activated electrode and 93% for the CuCl2-activated counterpart. This study provides the first comprehensive insight into the role of activation chemistry in tailoring pine pollen-derived carbon for supercapacitor applications, demonstrating the potential of pine pollen as a sustainable and low-cost resource for advanced energy storage systems.