In this work, nickel oxide (NiO) films have been prepared by a sparking method on a flexible chromium/gold coated polyethylene terephthalate substrates and investigated for electrochemical energystorage applications. Structural characterizations by scanning/transmission electron microscopies, X-ray 10 diffraction, X-ray photoelectron spectroscopy and UV-vis spectrophotometer reveal that the film comprises polycrstalline NiO nanoparticles with diameters in the range of 3.0-6.0 nm loosely agglomerated into porous foam-like network. The nanoporous sparked NiO films, exhibits remarkable energy-storage behavior with a high average specific charge capacity of 402.75 C g -1 at a discharge current of 1 A g -1 and a good capacity retention of 88% after 1000 cycles at a high discharge current of 40 15 A g -1 . Thus, the sparking method is a promising alternative route for the preparation of high-performance electrochemical energy-storage devices. 65 storage performances are investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements.
Materials and methodsThe schematic illustration of the sparking apparatus for the fabrication of NiO nanoparticles (NiO-NPs) and NiO films is 70