One-step synthesis of Zn-doped nickel sulfide/graphene derived from Ni-MOF for supercapacitor application

A metal sulfide derived from a metal-organic framework (MOF) was synthesized to be used as the active material for the supercapacitor's electrode. In this article, nickel-MOF was hydrothermally synthesized through a facile method; then, the synthesized MOF was doped with Zinc and composited with graphene oxide (GO) in different concentrations. Then, the composites that were achieved were sulfurized to study the improvement of the synthesized active materials. The synthesized materials were characterized with XRD, FESEM, EDS, and N₂ adsorption-desorption hysteresis techniques. The fabricated electrodic active materials were studied employing cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. Comparing the electrochemical performance of the synthesized sulfides revealed that the electrode with a higher amount of GO has the best electrochemical performance among other compositions with the specific capacitance of 442.66 F/g, which was obtained at a current density of 1 A/g. In addition, the asymmetric supercapacitor cell consisting of the mentioned electrode as the positive electrode and activated carbon as the negative electrode provided a power density of 774.99 W/kg at the maximum energy density of 2.142 Wh/kg and a higher cycling stability of 96 % retention at about 10,000 cycles.