Synthesis and characterization of Co-based hydroxides and metal disulphides with various forms of carbon for supercapacitor applications

Abstract

The aim and objectives of this work are to synthesize cobalt-based hydroxides and transition metal disulphides composites with carbon materials such as graphene foam and activated carbon by a facile and environmentally friendly hydrothermal technique for energy storage application. Because faradaic materials suffer from poor electrical conductivity and low electrochemical stability, while carbon materials are known to have good electrical conductivity and electrochemical stability, the combination of the two materials to make hybrid material should be able to improve the electrochemical properties of the composite material. Morphological, structural, surface area and compositions properties of the produced materials were evaluated and characterized using methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption isotherm (BET), Fourier transformation infrared spectroscopy (FTIR) and Raman spectroscopy. Electrochemical characterization involved cycling voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling life were carried out in two (asymmetric device) and three-electrode configurations using 6 M KOH aqueous electrolyte and they all showed excellent electrochemical performance. For instance the asymmetric devices based on CoA-LDH/graphene foam//AEG gave specific capacitance of 101.4 F g-1 with a maximum energy density of 28 Wh kg-1 and a corresponding power density of 1420 W kg-1 at a current density of 0.5 A g-1 , VS2//AC gave specific capacity of 155 F g-1 and high energy and power densities of 42 Wh kg-1 and 700 W kg-1 respectively at current density of 1 A g-1.and MoS2_150 mg GF //AEG gave high specific capacitance of 59 F g-1 with maximum energy and power densities of 16 Wh kg-1 and 758 W kg-1 respectively at a current density of 1 A g-1 respectively . All these results showed the great potential of the hybrid materials derived from the incorporation of cobalt based hydroxides and transition metal disulphides with carbon for supercapacitor application.