In situ synthesis of a 3D highly porous NiO film electrode with enhanced performance for supercapacitors

Herein we successfully synthesized a 3D highly porous NiO film electrode via a simple in situ method, and fabricated an additive-free NiO electrode for battery-type supercapacitor cathodes. The proposed strategy includes the in situ growth of the precursor film by a hydrothermal method followed by a pore-making step under annealing conditions. The crystallographic properties, morphology and porous structure of the as-made film electrode have been deeply investigated. The results show that the in situ synthesized NiO film possesses integrated advantages of a highly porous inherent structure, high specific surface area, stable framework and enhanced affinity/conductivity with substrates. As for electrochemical investigations, the as-obtained NiO film electrode exhibits enhanced capacity and excellent cycling stability for fast energy storage, and also presents good mechanical flexibility. The assembled asymmetric supercapacitor device exhibits substantially high energy density, and the LED indication test reveales the promising application value of NiO film products.