The use of conducting polymer and vanadium oxide composite materials as an electrode is of great interest to improve the lithium ion intercalation capacity and accessibility, mechanical flexibility, and ion mobility for rechargeable lithium batteries. We present herein the characteristics and improved electrochemical properties of V2O5/PANi composite films with controlled compositions for battery applications. The V2O5/PANi composite films were prepared by two consecutive electrochemical steps; the PANi film was firstly grown by a potentiodynamic polymerization method in an acid solution containing aniline monomer. Vanadium oxide was anodically deposited on the PANi film as a second step in a VOSO4 solution, whose temperature was varied in order to control the V2O5 contents in the composite films. The deposition of V2O5 increases with high current efficiency in the solution at high temperatures. The oxidative dissolution of PANi during the V2O5 deposition process in the high temperature solutions was identified by the structural and morphological characterization.
The large value of the diffusion coefficient estimated from the CVs for the composite film provides evidence for the synergistic effect of the conducting polymer and inorganic oxide composite. The conducting polymer acts not only as a conducting network but also as an electroactive material in the composites, thus enhancing the electrochemical response. The V2O5/PANi composite film cathodes show a high specific capacity and improved cyclability with almost no capacity fading. The first measured discharge capacity of the batteries assembled with the V2O5/PANi composite film cathode is as high as 460 mAh/g, and the stabilized and reproducible specific discharge capacities during the charge/discharge processes for 50 cycles were ca. 270 mAh/g.