Supercapacitor fabricated with 30 M KOH electrolyte and highly stable Pd4S electrodes

In this work, supercapacitors have been fabricated using Pd4S electrode material which is highly conducting and chemically robust to the acid and alkali media. The synthesis strategy is simple and involves a single step thermolysis of palladium octanethiolate film in the H2 atmosphere at 250°C for 1 h. Besides its conducting nature, its porous morphology makes it a suitable electrode material for supercapacitors. The electrochemical properties of the Pd4S were examined in harsh alkali media (30 M KOH). Typically, in the literature, only lower electrolyte concentration (1–6 M KOH) is preferred as the electrode may not withstand higher concentrations. Using the prepared Pd4S film as supercapacitor electrode, a specific capacitance of 570 F g−1 with energy and power densities of 28 Wh kg−1 and 1.5 kW kg−1, respectively, were achieved with 30 M KOH electrolyte. After 1500 cycles of charging and discharging with a constant current density of 1.75 A g−1, more than 98% capacitance retention was observed.