Oxygen-enriched coal-based porous carbon under plasma-assisted MgCO3 activation as supercapacitor electrodes

Abstract Functional carbon materials are used for supercapacitor (SCs) energy storage. Here, an eco-efficient water vapor plasma-assisted MgCO3 activation technology is developed to transform low-grade coal into high-value added porous carbon materials with coordinated regulation of pore structure, specific surface area (SSSA) and surface characteristics. The surface of coal-based porous carbon modified by water vapor plasma is rough and porous. The pores are interconnected with a three dimensional distribution and conducive for the rapid transport of electrolytes. Moreover, the doping of oxygen atoms improves the wettability of the porous carbon electrode and provides pseudo-capacitance. The obtained modified coal-based porous carbon has a large SSSA, abundant mesopore volume, reasonable pore size distribution and high O/C ratio, resulting in superior performance of SCs. Consequently, the assembled symmetric SCs manifests a superior energy density (10.35 Wh kg−1) under power density at 125 W kg−1 and 7.64 Wh kg−1 at 5 kW kg−1. This work can broaden the application of low-grade coal.