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

An amorphous and hydrous vanadium oxide (V2 O5 x H2 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 V2 O5 x H2 OCNT film electrode) for pseudocapacitor application. From cyclic voltammetry and galvanostatic discharging experiments in an organic electrolyte (LiCl O4 in propylene carbonate), the V2 O5 x H2 OCNT film electrode showed a specific Li-ion capacitance of 910 Fg at a potential scan rate of 10 mVs and a specific capacity of 540 mAhg at a current density of 10 Ag, with respect to the mass of V2 O5 x H2 O. Compared with V2 O5 x H2 O prepared onto a Pt plate substrate (denoted as a V2 O5 x H2 O thin-film electrode), the V2 O5 x H2 OCNT film electrode showed a threefold higher specific Li-ion capacitance. The improved specific Li-ion capacitance of V2 O5 x H2 O in the V2 O5 x H2 OCNT film electrode is attributed to its electrode construction comprising a very thin film of V2 O5 x H2 O on the conductive CNT film substrate with a three-dimensional nanoporous structure.