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 199 F·g−1, and a 1.6% loss in the specific capacitance after 1000 charge-discharge cycles, indicating a long-term cycling stability.