Fabrication and electrochemical study of copper doped zinc sulfide/graphene nanocomposites for supercapacitors†
Abstract
Transition metal sulfides exhibit excellent electrochemical performance and electrochemical energy storage capacity. Herein, we present high-capacity supercapacitor electrode based on copper doped zinc sulfide/graphene (ZCG) synthesized by co-precipitation method. Various techniques have been employed to characterize the ZCG nanocomposite including electrochemical measurements. The ZCG nanocomposites exhibit high crystallinity and phase purity. In three-electrode system and 1 M aqueous KOH solution, the prepared ZCG electrodes are evaluated using galvanostatic charge–discharge cycles (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The ZCG electrode exhibits an ultrahigh specific capacitance of 2295 F g−1 at a relatively low scan rate of 5 mV s−1 from CV and 743 F g−1 at 100 A g−1 from GCD, with exceptional cycling stability (93% capacity retention after 1000 cycles). Furthermore, the ZCG10 symmetric coin cell exhibits a specific capacitance, energy density, power density of 130.8 F g−1, 18 W h kg−1, 2400 W kg−1 at current density of 1.2 A g−1 in a 1 M KOH solution from GCD. The ZCG hybrid electrode material can be predicted a potential hybrid electrode material for the future development of energy storage devices.