Impact of silver incorporation on cobalt rich 3-D porous carbon arising from solid state thermolysis of ZIF-67 as a pseudocapacitor electrode: Improvement of diffusion-controlled charge storage

Abstract

Here, for improvement of electrochemical energy storage properties of ZIF-67, it has been incorporated with low and high concentrations of silver ions, followed by a solid state thermolysis in an inert atmosphere to synthesis of Ag-incorporated cobalt/porous carbon composites. These as-synthesized active materials have been deposited on a nickel foam to electrochemical measurements including, Cyclic Voltammetry, Galvanostatic Charge-Discharge and Electrochemical Impedance Spectroscopy. The results revealed that the sample with trace amounts of Ag incorporation enhanced the supercapacitive performance and improved the specific charge capacity fourfold in all conducted scan rates. An increase in Ag ion improved the contribution of diffusion-controlled charge storage mechanism. Also, to investigate practical capabilities of these materials, the asymmetric supercapacitor was set up using one of the electrodes as the positive electrode and an activated carbon electrode as the negative electrode which performed maximum specific energy of 8.50 Wh/kg and maximum specific power of 7037.04 W/kg at gravimetric currents of 1 and 10 A/g respectively. Furthermore, this hybrid supercapacitor showed a high-capacity retention of 92% after 3000 cycles.