ZIF-derived Cu doped Co3O4/RGO composites for asymmetric supercapacitors

Abstract

In this work, an asymmetric aqueous supercapacitor using a ZIF-derived Cu doped Co3O4/reduced graphene oxide cathode and an activated carbon (AC) anode have been developed. Firstly, Cu–Co3O4 flower-like NPs are synthesized by sol-gel method using cobalt based ZIF as a template to form a binder-free composite cathode able to reach a capacitance of 225 F/g at 1 A/g. The cathode can be additionally modified by reducing and depositing graphene oxide onto the Cu–Co3O4flower-like composite by chronopotentiometry obtaining a capacitance of 240 F/g at 1 A/g. The high performance of the ASC device is attributed to the easy electroactive composite fabrication method as well as the porous carbon and flower-like morphologies. The electrochemical performance of the asymmetric device is evaluated on the basis of the high potential redox reactions occurring in 2M KOH electrolyte within a potential window of 1.5 V, achieving a capacitance of 20 F/g at 1 A/g as well as density energies and power densities of 5.6 W h/kg and 6 kW/kg, respectively.