Highly Porous Willow Wood-Derived Activated Carbon for High-Performance Supercapacitor Electrodes

In this study, we present willow wood as a new low-cost, renewable, and sustainable biomass source for the production of a highly porous activated carbon for application in energy storage devices. The obtained activated carbon showed favorable features required for excellent electrochemical performance such as high surface area (∼2 800 m² g^-1) and pore volume (1.45 cm³ g^-1), with coexistence of micropores and mesopores. This carbon material was tested as an electrode for supercapacitor application and showed a high specific capacitance of 394 F g^-1 at a current density of 1 A g^-1 and good cycling stability, retaining ∼94% capacitance after 5 000 cycles (at a current density of 5 A g^-1) in 6 M KOH electrolyte. The prepared carbon material also showed an excellent rate performance in a symmetrical two-electrode full cell configuration using 1 M Na₂SO₄ electrolyte, in a high working voltage of 1.8 V. The maximum energy density and power density of the fabricated symmetric cell reach 23 W h kg^-1 and 10 000 W kg^-1, respectively. These results demonstrate that willow wood can serve as a low-cost carbon feedstock for production of high-performance electrode material for supercapacitors.