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

Abstract

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 b-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 À1 was evaluated for nanoplates at a scan rate of 5 mV s À1 . 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.

Supercapacitive properties of chemically deposited La 2 O 3 thin film

“…This shows that the La 2 O 3 electrode is useful for the supercapacitor application. The active surface areas for Ni(OH) 2 [28] and Fe 3 O 4 [29]thin filmsare less than that of observed for La 2 O 3 electrode.…”

Fabrication of three dimensional carbon nanotube foam by direct conversion carbon dioxide and its application in supercapacitor

“…Some flower-like Ni(OH) 2 are also observed from the same reaction batch which may appear at the intersections of the carbon nanotubes. As we all know, Ni(OH) 2 often results in compromises of rate capability and reversibility because they rely on faradic redox reactions and the active materials are typically too poorly conducting to support fast electron transport required by high rates [24,25]. For the present Ni(OH) 2 /CNTF composites, the unique structure significantly improves the surface area, especially the CNTF provides a low electronic and ionic charge-transfer resistances to enhance the electron transport to the ultrathin Ni (OH) 2 film.…”

Direct growth of FeCo2O4 nanowire arrays on flexible stainless steel mesh for high-performance asymmetric supercapacitor

“…The increasing temperature limits vertical growth of the nanomaterial, which reduces its surface energy. 26 That is why, after 100°C, the nanomaterial inclines in the horizontal direction to form aggregated nanorods and rhombus-shaped structure. The aggregated nanostructure does not allow access to the inner electroactive sites for the electrochemical reactions as it blocks path of the electrolyte ions.…”

“…26 For the SC applications, these physical properties, such as smooth, uniform porous nanostructured thin films, are required in order to create an easy path for the electrochemical reaction. 27,28 Hence, nanostructured FeCo 2 O 4 thin films on the SSM substrate at different reaction temperatures were prepared and their effects on electrochemical performance were studied systematically.…”

“…The maximum specific and volumetric capacitance for the MnO 2 //FeCo 2 O 4 asymmetric SC devices reached 170 F g − 1 and 1.066 F cm − 3 , respectively, at a current density of 1 mA cm − 2 ( Figure 7e). The specific energy and power were calculated by considering the discharge curve and plotted as a Ragone plot (Figure 7f) 40 Ni-Co LDH/3D RGO NF//AC (38.6 Wh kg − 1 , 6 M KOH) 26 (for more details see SI S15). The higher specific energy for the MnO 2 //FeCo 2 O 4 asymmetric SC devices was resulted from higher operating potential (2.0 V) and higher capacitance of the device.…”