Polystyrene foam derived nitrogen-enriched porous carbon/graphene composites with high volumetric capacitances for aqueous supercapacitors

Polystyrene (PS) foam derived nitrogen-enriched porous carbon/graphene (AC/Gr) composites were prepared using ammonia, ethylene diamine and melamine as nitrogen sources, respectively. The as prepared AC/Gr composites and graphene-free PS-derived porous carbon (PSAC) exhibit moderate specific surface areas in a range of 915-1489 m(2) g(-1). Compared to PSAC, AC/Gr composites exhibit significantly improved energy storage capability, a high gravimetric capacitance of 339 F g(-1) or volumetric capacitance of 365 F cm(-3) was achieved at a current density of 0.05 A g(-1) in 6 M KOH aqueous electrolyte. The assembled aqueous symmetric supercapacitors are capable of deliver both high energy density and high power density, for example, 11.8 W h kg(-1) (12.7 W h L-1) with a power density of 12.5 W kg(-1) (13.4 W L-1), and 6.2 W h kg(-1) (6.7 W h L-1) with 4.6 kW kg(-1) (5.0 kW L-1) for MAC/Grbased supercapacitor. (C) 2016 Elsevier Inc. All rights reserved.