A comparative study of nitrogen-doped hierarchical porous carbon monoliths as electrodes for supercapacitors

Two nitrogen-doped carbon monoliths with hierarchical porosity over a large size range were prepared by polymerization of resorcinol and formaldehyde in the presence of an organic amine, L-lysine, and an inorganic base, ammonium hydroxide under ambient conditions. Their physical and chemical features were characterized by N₂ sorption, transmission and scanning electron microscopy, and elemental analysis. Their electrochemical properties as the electrodes of supercapacitors were evaluated under both a three-electrode system and a two-electrode system. Results show that the two types of nitrogen-doped carbon possess similar pore structures, but have distinct electrochemical performances. The L-lysine incorporated carbon monolith has a high nitrogen content, a high specific capacitance of 199F · g^-1, and a 1.6% loss in the specific capacitance after 1000 charge-discharge cycles, indicating a long-term cycling stability.