Electrochemical preparation and characterization of V2O5/polyaniline composite film cathodes for Li battery

Vanadium pentoxide/polyaniline (V2O5/PANi) composite films were prepared by a two-step electrochemical method and evaluated for their application in lithium batteries. As a first step the PANi film was potentiodynamically grown in an acid solution containing aniline monomer, and secondly vanadium oxide was oxidatively deposited on the polyaniline film in a temperature controlled VOSO4 solution. The increased current efficiency obtained with the larger anodic current in the high temperature solutions results in high contents of V2O5 in the composites, even if the oxidative dissolution of PANi also occurs. The large value of the diffusion coefficient estimated from the cyclic voltammograms for the composite film provides evidence for the synergistic effect of the conducting polymer and the inorganic composite. The cell exhibited excellent cycle stability with a high charge storage capacity. The large increase in the specific capacity for the composite film prepared in this work demonstrates that the conducting polymer in the composite acts as a binding and conducting element by contributing its electroactivity. The V2O5/PANi composite film cathodes show a large specific capacity (ca. 270 mAh/g) and improved cyclability with an extremely small amount of capacity fading (ca. 3.4%) during repeated charge/discharge cycles.