Designing kinetics of graphene composited multiscale porous carbon for advancing energy storage performance of supercapacitors

Abstract

Despite active research on supercapacitors to address the demand for high-power backup power systems, the energy storage performance of supercapacitors at high current densities has scope for improvement owing to the poor kinetics of active materials. In this study, multiscale porous carbon-based active materials were designed to improve the kinetics and power density of supercapacitors. These materials were fabricated by spinodal decomposition of a mixture comprising an epoxy resin, a curing agent, and a porogen, to which graphene was added to optimize the carbonaceous microstructure. The resultant material exhibited a wider pore-size distribution and considerably improved microstructure than commercial activated carbon (YP-50F). The charge-transfer resistance of the sample containing 3 wt.% graphene (A-EM3) was considerably lower than that of YP-50F owing to the microstructural improvement. Furthermore, the effective ionic conductivity of A-EM3 was approximately three times higher than that of YP-50F owing to enhanced mass transfer. A-EM3 exhibited a high specific capacitance (81.0 F g−1) at the highest current density (10.0 A g−1). Thus, spinodal decomposition and graphene addition are effective means to fabricate high-power-density supercapacitors.