Enhanced Capacitance and Rate Capability of Nanocrystalline VN as Electrode Materials for Supercapacitors

摘要

Nanocrystalline VN was synthesized from the melamine reduction of V2O5 xerogel under a N2atmosphere for supercapacitors. The structure, particle size and surface elemental composition arecharacterized by X-ray diffraction spectroscopy (XRD), nitrogen adsorption/desorption at 77 K,transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-rayphotoelectron spectroscopy (XPS). The electrochemical characterizations were performed by cyclicvoltammetry (CV), galvanostatic charge-discharge (CD) test and the electrochemical impedancespectroscopy (EIS) measurements. The XRD result indicates that the nanocrystalline VN belongs tothe cubic crystal system. TEM images show the disperse nanocrystalline VN particles. FTIR and XPSresults reveal that change in the oxide on nanocrystalline VN surface was the main factor leading to theelectrochemical cycling-induced capacitance loss. In addition, the electrochemical results show that thenanocrystalline VN displayed exciting supercapacitive behaviors. A maximum specific capacitance of-1 -1 413 F g was recorded at the current density of 1 A g . A respectable rate capability was exhibited bythe nanocrystalline VN electrode, showing about 88% of its maximal capacitance at a current load of 4-1 A g . The experimental results indicate that the nanocrystalline VN is promising electrode material forelectrochemical supercapacitors.