Comparison of electrochemical characteristics of NiCo2O4 and NiCo2S4 nanostructures for supercapacitors

Abstract

This paper presents the results on the synthesis and study of the properties of NiCo2O4 and NiCo2S4 nanostructures obtained by hydrothermal synthesis for their use as supercapacitor electrodes. A method is developed for growing a nanostructure from a ternary metal oxide NiCo2O4 on a nickel substrate. The structural features of the synthesized NiCo2O4
and NiCo2S4 nanostructures are studied using X-ray phase analysis. The obtained samples have a cubic modification NiCo2O4 and NiCo2S4. The data on the morphology of the synthesized samples obtained by scanning electron microscopy are presented. The samples are in the form of nanoneedles and nanowires grown on a nickel substrate. Methods for the synthesis of NiCo2O4 nanostructures have been studied, optimal conditions for the growth of nanostructures from NiCo2O4 have been determined, and a NiCo2O4 sulfurization method has been developed to obtain a NiCo2O4 nanostructure. Comparative studies have been carried out on the effects of sulfurization on the electrochemical characteristics of the obtained electrodes. It is found that, despite the fact that NiCo2O4 oxide nanostructures have a high theoretical capacitance, the replacement of oxygen atoms by sulfur atoms increases the conductivity of the materials and leads to a further increase in the specific capacitance of the end electrodes. The maximum Cs obtained specific capacitance for NiCo2S4 is 1976 F g-1 and while for NiCo2O4 it is 413 F g-1 at a scan rate of 5 mV/s. The results of the dependence of the specific capacitance on the scanning speed during measurements are also presented.