Supercapacitors are deemed as reliable power sources for portable devices and electric vehicles. Electrode materials with high energy and power densities are greatly needed. Herein, we designed reducedgraphene-oxide supported nickel-cobalt layered double hydroxide nanosheets (NiCo-LDH/rGO) as electrode materials. The introduction of graphene could largely enhance the conductivity, and the supported NiCo-LDH could effectively prevent graphene from self-aggregation. Thanks to the synergistic effect of conductive graphene and electro-active LDH, the nanocomposites delivered a capacitance of 1675 F g(-1) at 1 A g(-1) and decent rate performance (capacitance retention of 83.8% at 10 A g(-1)); while NiCo-LDH could only exhibited a capacitance of 920 F g(-1) at 1 A g(-1) and 81.5% of the capacitance remained at 10 A g(-1). The asymmetric supercapacitors assembled with NiCo-LDH/rGO and activated carbon (AC) delivered high energy density and power density, up to 49.9 Wh kg(-1) and 3747.9 W kg(-1), respectively. The appealing electrochemical performance indicates its huge application potential in supercapacitors. (C) 2020 Elsevier Inc. All rights reserved.