Nitrogen-doped activated carbons via melamine-assisted NaOH/KOH/urea aqueous system for high performance supercapacitors

Abstract

Fabrication of carbon materials from biomass is a cost-effective and ecofriendly approach to solve the crisis of fossil resources. Herein, by melamine-assisted NaOH/KOH/urea aqueous system, nitrogen-doped activated carbon (NDAC) has been fabricated as high-performance electrode from Chinese fir sawdust. NaOH/KOH/urea aqueous is an activator and a solvent for cellulose, while urea and melamine are nitrogen sources. The effect of activation temperature and melamine dosage on the performance of NDAC was determined and discussed. The results showed that in the presence 10 g of melamine, the specific surface area (SBET) and nitrogen content of NDAC were greatly improved from 1040 to 1382 m2 g−1 and from 3.52 to 5.16%, respectively. In addition, NDAC had high N content and hierarchically interconnected porous structure, thus had good capacitive performance. Furthermore, NDAC prepared at an activation temperature of 850 °C and with 10 g of melamine had a specific capacitance of as high as 196 F g−1 at a current density of 1 A g−1. The NDAC showed satisfactory cycle capability; its capacitance retention rate could be maintained at 87.4% after 5000 galvanostatic cycles at 5A g−1. In addition, the 850°C-10-based symmetric SCs exhibit an energy density of 9.7 Wh kg−1 at a power density of 261.44 W kg−1, which enables it to be a promising electrode material for supercapacitors and renewable delivery devices.