Transforming Fallen Leaves into High-Performance Activated Carbon for Supercapacitor Applications

Fallen or dead leaves, an abundant and environmentally concerning waste, were used as precursors to synthesize advanced activated carbons (ACs) for use in supercapacitors. The innovative method involves the chemical activation of fallen leaves using a mixture of potassium hydroxide (KOH) and sodium hydroxide (NaOH), followed by low-temperature pyrolysis. The chemical composition, structural characteristics of the fallen leaves, and the formation of activated carbon materials were investigated using an advanced analytical technique. The synthesized activated carbon exhibited a maximum surface area of 317 m2 g–1, well-developed microporosity, and excellent conductivity─key features for supercapacitor applications. Electrochemical evaluation of the fallen-leaf-derived activated carbon revealed promising performance in both aqueous (6 M KOH) and neutral (1 M Li2SO4) electrolytes, achieving a maximum specific capacitance of 50 F g–1 and a noteworthy power density of 6000 W kg–1 at a current density of 0.5 A g–1. Additionally, it demonstrated outstanding capacity retention of 70% at a current density of 5 A g–1 over 10,000 charge–discharge cycles, indicating suitability for power application. These findings establish fallen leaves as sustainable, low-cost, and highly effective resources for producing advanced carbon materials, offering noteworthy potential for advanced energy storage devices such as supercapacitors.