The Role of a SiC Sublayer in Modulating the Electrochemical Behavior of CoxSy/SiC Heterostructure Supercapacitor Electrodes

In this study, we investigated the electrochemical properties and performance characteristics of CoxSy and silicon–carbon-based heterostructures synthesized on nickel foam substrates for energy storage applications. Cobalt sulfide films were successfully electrodeposited on nickel foam (NF) using cyclic voltammetry (CV) from the solutions with different Co2+ concentrations. The presence of a silicon–carbon sublayer promotes the deposition of cobalt sulfide material. The amorphous phase of α-CoS was observed by the X-ray diffraction technique. Raman spectroscopy confirmed the formation of CoS and CoS2 phases. A significant increase in electrode areal capacitance is observed with the silicon–carbon film sublayer from 0. 5 to 1. 3 F·cm−2 and from 1. 6 to 2. 3 F·cm−2 at 3 mA·cm−2 for samples prepared from solutions with CoCl2·6H2O concentrations of 0. 005 M and 0. 02 M, respectively. In the case of gravimetric capacitance, an increase is observed in the presence of a silicon–carbon sublayer for the SiC@CoS₀. 005 sample, rising from 690 F·g−1 to 748 F·g−1 at 4 A·g−1. Conversely, the SiC@CoS₀. 02 sample shows a decrease from 1287 F·g−1 to 6590 F·g−1. It was shown that the capacitance of all the electrodes derives from the mix of diffusion-controlled and surface-controlled capacitance processes. The electrochemical impedance spectroscopy (EIS) analysis indicates that the formation of heterostructure materials significantly alters the electrochemical properties by reducing both Rf and Rs.