A nanosized graphitic carbon with balanced and connected micro/mesopores is prepared by directly carbonizing Ni(II) cation-exchanged resin at a moderate temperature of 800 degrees C. The homogeneously dispersed Ni nanoparticle well acts as the catalyst for "in-situ" graphitization of the low-cost resin and the porogen for the formation of configured micro- and mesopores. The graphitic carbon GC-800 exhibits a balanced micro/mesoporosity at the ratio of 1:2, which delivers an excellent specific capacitance 66.0 mu F/cm(2) and a high volumetric capacitance of 552.6 F/cm(3) at the current density of 0.50 A/g in the electrolyte of 1.0 M H2SO4. In the dual-electrode system, it also displays high energy density of 7.43 Wh/kg at a power density of 125.0 W/kg. Its superior cyclic performance is not only confirmed by the capacitance retention (95%) after 400 h using the rigid floating technique but also 10000 cycles of GCD measurement at the current density of 5.0 A/g in both double- and triple-electrode systems. (C) 2018 Elsevier Ltd. All rights reserved.