VxOy nanoparticles and activated charcoal based nanocomposite for supercapacitor electrode application

In the present work, a nanocomposite formed by dispersing vanadium oxide (VxOy) nanoparticles (NPs) in matrix activated charcoal for the purpose of electrode material in a supercapacitor. The synthesis of vanadium oxide (VxOy) has been carried out using cost effective method at room temperature. The starting materials vanadyl sulphate pentahydrate (VOSO4·xH2O) and sodium hydroxide (NaOH) have been dissolved to prepare stock solution and have been used to prepare vanadium oxide (VxOy) nanoparticles. The prepared nanoparticles have a size of approximately 26 nm, which has been determined from synchrotron X-ray diffraction data. The particle size distribution has been controlled through precipitation rate and calcination temperature. The final precipitates have been calcined at 400 °C and 500 °C temperatures to observe effect of temperature on particle size. The obtained nanopowder has been characterized by Synchrotron X-ray diffraction (SXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The XPS investigation provides different oxidation state of vanadium metal cations. The layer structure of oxide and different oxidation cations may have effect on charge transfer at interface between electrolyte and electrode. Further, the electrochemical characterization has been carried out to evaluate performance of nanopowder and activated charcoal composite as an electrode material in a supercapacitor. The specific capacitance of the cells containing electrolyte using 1 M H2SO4 and 6 M KOH and activated charcoal–vanadium oxide (VxOy), 1:1 mass ratio and 1:2 mass ratio electrodes in which vanadium oxide (VxOy) is prepared at 500 °C has resulted into better electrochemical performance. The specific capacitance of the supercapacitor cells is stable up to 2000 cycles at 100 mV cm−2, which shows that the device has good electrochemical reversibility and cycle life with 1 M H2SO4 and 6 M KOH electrolyte.