Synthesis of reduced graphene oxide supported nickel-cobalt-layered double hydroxide nanosheets for supercapacitors.

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 reduced-graphene-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.