Nitrogen-Doped Hierarchical Porous Activated Carbon Derived from Paddy for High-Performance Supercapacitors

A facile and environmentally friendly fabrication is proposed to prepare nitrogen-doped hierarchical porous activated carbon via normal-pressure popping, one-pot activation and nitrogen-doping process. The method adopts paddy as carbon precursor, KHCO₃ and dicyandiamide as the safe activating agent and nitrogen dopant. The as-prepared activated carbon presents a large specific surface area of 3025 m²·g^-1 resulting from the synergistic effect of KHCO₃ and dicyandiamide. As an electrode material, it shows a maximum specific capacitance of 417 F·g^-1 at a current density of 1 A·g^-1 and very good rate performance. Furthermore, the assembled symmetric supercapacitor presents a large specific capacitance of 314.6 F·g^-1 and a high energy density of 15.7 Wh·Kg^-1 at 1 A·g^-1, maintaining 14.4 Wh·Kg^-1 even at 20 A·g^-1 with the energy density retention of 91.7%. This research demonstrates that nitrogen-doped hierarchical porous activated carbon derived from paddy has a significant potential for developing a high-performance renewable supercapacitor and provides a new route for economical and large-scale production in supercapacitor application.