Electrochemical characterization on cobalt sulfide for electrochemical supercapacitors

High capacitance at a high charge–discharge current density of 50 mA/cm2 for a new type of electrochemical supercapacitor cobalt sulfide (CoSx) have been studied for the first time. The CoSx was prepared by a very simply chemical precipitation method. The electrochemical capacitance performance of this compound was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge tests with a three-electrode system. The results show that CoSx has excellent electrochemical capacitive characteristic with potential range −0.3 ∼ 0.35 V (versus SCE) in 6 M KOH solution. Charge–discharge behaviors have been observed with the highest specific capacitance values of 475 F/g at the current density of 5 mA/cm2, even at the high current density of 50 mA/cm2, CoSx also shows the high specific capacitance values of 369 F/g.