Preparation of nitrogen-doped pitch-based carbon materials for supercapacitors

• A N-doped carbon material with melamine was successfully synthesized with CTP as precursor.
• Carbonization yield produced by the mixture of CTP and melamine reached 35.6%.
• The N-doped carbon material with abundant mesopores exhibits promising supercapacitive properties.
• The content of surface N for the carbon materials after adding melamine increased by 134%.

Coal tar pitches (CTP) are used as precursor of electrode material because of their low cost and high carbon yield. In this study, CTP-based activated carbon materials (CACs) with high capacitance for supercapacitors were prepared by doping elemental N with co-carbonization of CTP and melamine. The electrochemical performance and textural characterization of CACs were investigated by constructing a single electrode capacitor in a 6 M KOH electrolyte, N2 adsorption, scanning electron microscopy, and XPS. Results show that CACs with mass proportion of melamine and CTP being 1:5 possess a surface area of 2573 m2 g−1, with mesopore volume accounting for 56% of the total volume. After co-carbonization, N content on the surface of the CACs increased by 134% compared to that of undoped activated carbons. Their capacitance reached up to 228 F g−1 at a current density of 1 A g−1. The high electrochemical performance of the CACs is attributed to its additional pseudo-capacitance and high surface area. The specific capacitance still possessed 94.2% retention after 1000 cycles, indicating good cycle stability.