Optimising the Temporal Development of Cobalt Sulfides: The Essential Influence of Hydrothermal Duration on Supercapacitor Efficacy

A fabrication and performance study of an asymmetric supercapacitor which employed a two-step hydrothermally synthesized cobalt sulfide (Co ₃ S ₄ ) via regulated sulfidation, as cathode, has been documented. Novel findings on the kinetics of sulfidation reactions, which are influenced by the synthesis duration are reported. The efficacy of the as-synthesized Co ₃ S ₄ has been demonstrated through several characterizations including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen (N ₂ ) adsorption-desorption. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) were conducted to examine the electrochemical behavior of the Co ₃ S ₄ . Among four variations of synthesis duration, the 20 h is the most suitable duration to synthesize a highly effective Co ₃ S ₄ active material to be utilized as cathode for supercapacitor since the as-prepared electrode exhibited a specific capacitance ( C _sp ) value of 480.40 F g ^− 1 at 1 A g ^− 1 . A Co ₃ S ₄ -20 h/KOH/GO asymmetric supercapacitor was fabricated, and it is documented that the supercapacitor exhibited a C _sp value of 25.94 F g ^− 1 at 0.5 A g ^− 1 , with energy density of 9.22 Wh kg ^− 1 and power density of 4000 W kg ^− 1 .