Synthesis and electrochemical characterization of vanadium oxide on carbon nanotube film substrate for pseudocapacitor applications

An amorphous and hydrous vanadium oxide (V2O5 center dot xH(2)O) thin film of approximate 6-nm thickness was electrochemically prepared onto a carbon nanotube (CNT) film substrate with a three-dimensional porous structure on a nanometer scale (denoted as a V2O5 center dot xH(2)O/CNT film electrode) for pseudocapacitor application. From cyclic voltammetry and galvanostatic discharging experiments in an organic electrolyte (LiClO4 in propylene carbonate), the V2O5 center dot xH(2)O/CNT film electrode showed a specific Li-ion capacitance of 910 F/g at a potential scan rate of 10 mV/s and a specific capacity of 540 mAh/g at a current density of 10 A/g, with respect to the mass of V2O5 center dot xH(2)O. Compared with V2O5 center dot xH(2)O prepared onto a Pt plate substrate (denoted as a V2O5 center dot xH(2)O thin-film electrode), the V2O5 center dot xH(2)O/CNT film electrode showed a threefold higher specific Li-ion capacitance. The improved specific Li-ion capacitance of V2O5 center dot xH(2)O in the V2O5 center dot xH(2)O/CNT film electrode is attributed to its electrode construction comprising a very thin film of V2O5 center dot xH(2)O on the conductive CNT film substrate with a three-dimensional nanoporous structure. (C) 2006 The Electrochemical Society.