Impregnation assisted synthesis of 3D nitrogen-doped porous carbon with high capacitance

Three-dimensional (3D) porous carbons with controlled mesopore and micropore structures were prepared through a simple and low-cost ultrasonic and impregnation assisted method from waste air-laid paper. The ammonia management was used to dope the 3D porous carbons with different types of nitrogen heteroatoms in a way that replaced carbon atoms. The N2 adsorption-desorption characterization suggested that the nitrogen-doped carbons have a high surface area of 1470 m2 g−1 with the average pore diameter of 4.2 nm, which are conducive to form electric double layer under high current density. The resulting 3D carbon exhibited a higher capacitance at 296 F g−1 in comparison with the nitrogen-free one at 252 F g−1 in 6 M KOH electrolyte. Moreover, a high power density ca. 0.313 kW kg−1 and energy density ca. 34.3 Wh kg−1 were achieved in the ionic liquid ([EMIm]BF4). The findings will open a new avenue to use waste materials for high-performance energy-storage devices.