3D highly porous microspherical morphology of NiO nanoparticles for supercapacitor application

In the present work, the effect of reaction temperature and urea concentration on the electrochemical performance of NiO nanoparticles is investigated. The NiO nanosheets are synthesized by a facile and economical, hydrothermal method. The structural and morphological characterizations of the synthesized nanoparticles are done by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and Brunauer-Emmett-Teller (BET) analysis. The nanosheet morphology is developed when NiO is synthesized at 110 ? by keeping 01:02 proportion of nickel nitrate and urea in the growth solution. Formation of multiple highly porous microspheres is observed when NiO is grown directly on the nickel foam. The electrochemical performance of the developed electrodes is analysed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The binder-free electrode prepared by using these NiO nanosheets is able to display a magnificent specific capacity of 408 C/g (815 F/g) at 10 mV/s and 418 C/g (1045F/g) at 1 A/g. This electrode has shown a noteworthy cyclic stability by retaining 87.5% of its specific capacity after 1000 cycles, even at a high current density of 14A/g. The electrochemical performance of binder-enriched and binder-free electrodes and their dependence on the morphology of the NiO nanoparticles are analysed and discussed in this work. The asymmetric supercapacitor is assembled by considering NiO nanosheet-based electrode as anode, activated carbon-based electrode as the cathode and 6 M KOH/PVA-based gel as electrolyte. The asymmetric supercapacitor has delivered a maximum energy density of 22.5 Wh/kg at 0.9 kW/h.

Automated summary

In this study, the effect of reaction temperature and urea concentration on the electrochemical performance of NiO nanoparticles is investigated through the synthesis of NiO nanosheets using a hydrothermal method. The structural and morphological characterizations of the synthesized nanoparticles are analyzed and the electrochemical performance of the developed electrodes is evaluated. The binder-free electrode prepared using these NiO nanosheets displays excellent specific capacity and cyclic stability, demonstrating promising potential for energy storage applications.