3D porous graphene composite film embedded by Ni/NiO nanoparticles as freestanding electrodes for efficient energy storage devices

A 3D porous graphene composite film containing Ni/NiO hybrid nanoparticles (Ni/NiO NPs) is prepared by combining electrophoresis deposition and thermal H2 annealing techniques. The Ni/NiO NPs with a mean diameter of 45 nm are uniformly embedded on both the exterior and interior surfaces of reduced graphene, forming a 3D porous reduced graphene oxide composite film (Ni/NiO rGO). The insertion of Ni/NiO NPs into rGO greatly improves the electric conductivity and charge storage capability of the resultant Ni/NiO rGO film. By directly using it as freestanding electrodes, the fabricated lithium-ion battery and supercapacitor respectively exhibited high capacities of 758 mAh g-1@ 0.2 A g-1 and 430.8 F g-1@0.5 A g-1, an increase of 82.3-fold and 20.2-fold compared to the pure rGO electrode-based counterparts under the same condition.