Decoration of Vanadium Pentoxide on Conductive Carbon Nanotube Framework As Electroactive Materials for Aqueous Supercapacitors

Abstract

Supercapacitors (SCs) have been regarded as energy-storage devices that performance between conventional capacitors and batteries. They commonly have higher energy densities, deliver higher power densities, long cycling life and faster charge/discharge rates than conventional batteries. The charge storage mechanisms of SCs are generally divided into the following two types. The one is electric double-layer capacitors (EDLCs) which originates from the charge accumulation process at the electrode/electrolyte interface, and the other type is pseudocapacitors in which the charge storage mechanisms occurs through the faradic redox reactions. Among the transition-metal oxides, vanadium pentoxide (V2O5) has layered structure, the satisfactory charge storage capacity, a modest electronic conductivity, unique advantages of high energy density and wide potential window arising from its various vanadium oxidation states. In this work, we successfully decorated V2O5 thin layer on the surface of conductive carbon nanotubes (CNTs), designated as CNT@V2O5, by using pulsed-mode electrodeposition. It was found that the as-deposited V2O5 thin film is with nano-crystalline nature and the surface of the CNTs is evenly deposited with it. The as-deposited CNT@V2O5 electrode can reveal an enhanced discharge capacitance of 198 F/g at current density of 1 A/g in 2 M NaNO3 aqueous electrolyte.