Temperature influence on morphological progress of Ni(OH)(2) thin films and its subsequent effect on electrochemical supercapacitive properties

The temperature dependent morphological evolution and its effect on the electrochemical supercapacitive properties of Ni(OH)(2) thin films have been systematically investigated. A temperature dependent growth mechanism model is proposed for the changes in microstructure. Different nanostructures of Ni(OH)(2) thin films such as nanoplates, stacked nanoplates, nanobelts and nanoribbons have been fabricated by varying the deposition temperature. An X-ray diffraction study discloses the orientations of different nanostructures and the formation of nanocrystalline beta-Ni(OH)(2). Further, these Ni(OH)(2) nanostructures demonstrate excellent surface properties like uniform surface morphology, good surface area, pore volume and uniform pore size distribution. The electrochemical supercapacitive properties of Ni(OH)(2) nanostructures have been investigated by cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy techniques. The electrochemical studies of the Ni(OH)(2) samples show an obvious influence of surface properties on the pseudocapacitance. The maximum specific capacitance of 357 F g(-1) was evaluated for nanoplates at a scan rate of 5 mV s(-1). Furthermore, all these Ni(OH)(2) samples show good long-term cycling performances in KOH electrolyte. The Ragone plots ascertain good power and energy densities of all Ni(OH)(2) nanostructured samples. Subsequently, electrochemical impedance measurements for the different nanostructures of Ni(OH)(2) electrodes are assessed indicating that the Ni(OH)(2) nanoplates structured electrodes are suitable for good capacity electrochemical supercapacitors.