Electrochemical energy storage devices comprising batteries, fuel cells and supercapacitors play an important practical role in future energy applications. This is due to the growing demand forrenewable clean energies with discrete nature. Supercapacitors are receiving increasing consideration due to a combination of high power and high energy density, long cycle life and fast charge/discharge processes. Supercapacitors are generally classified into electrical doublelayercapacitors (EDLCs) and faradaic pseudocapacitors. The latter can provide much higher specific capacitance and energy density. In this work, spinel
NiCo₂O₄ nanostructures have been prepared by cathodic electrodeposition of mixed Ni/Co hydroxides and subsequent heating of thedeposited layer. The electrodeposition step has been carried out galvanostatically at different current densities ranging from 0.15 mA cm-² to 0.65 mA cm-² from a nitrate bath containing Ni and Co at an initial Ni/Co ratio of 0.5. In the second step, the obtained mixed hydroxide layer hasbeen calcined to prepare spinel NiCo₂O₄. The whole process has been monitored by a variety of characterization methods including X-Ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-Ray spectrometry (EDS). The XRD patterns showed that theobtained final product is composed of spinel
NiCo₂O₄ regardless of the variation in the applied current density. The SEM micrographs revealed that the obtained nanocrystals are composed of interlocked nanosheets but the morphological properties of the nanosheets are influenced by thecurrent density. The EDS analysis showed that the applied current density has a detrimental effect on the stoichiometry and Ni/Co ratio of the final product. It was found that, due to kinetic effects, the Ni/Co ratio changes from 0.43 to 0.53 by increasing the current density from 0.15mA cm-² to 0.55 mA cm-². The storage ability of the samples was investigated by cyclic voltammetry in 1M KOH aqueous solution at different scan rates ranging from 1 to 50 mVs-1. The results showed that the storage ability is a complex function of various structural parameters including morphology, stoichiometry and Ni/Co ratio of the obtained nanosheets. The maximum of the achieved storage ability was found to be 305 F g-¹ for the sample prepared at a current density of 5 mV s¯ ¹. The proposed method provides a facile, cost effective and high performance strategy for the synthesis of spinel NiCo2O4 for supercapacitor applications