Flexible and ITO-free asymmetric energy storage devices based on graphene/Ni(OH)2 nanocomposites

•Asymmetric energy storage devices using rGO/Ni(OH)2 as cathode and activated carbon as anode.•Both cathode and anode thin films were obtained through the liquid/liquid interfacial route.•ITO-free and flexible devices were prepared using carbon nanotubes/PET thin films as electrode.•Fully characterization of both rigid and flexible devices.•Good capacities and charge-discharge stability were achieved.