Impedance Monitoring of the Anodic Dissolution of PANi during the V_2O_5 Deposition Step for the PANi/V_2O_5 Composite Film Preparation

摘要

Vanadium pentoxide / polyaniline (V_2O_5/PANi) composite films were prepared by a two-step electrochemical method for the cathode material 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 VOSO_4 solution. The increased anodic current efficiency in the hot VOSO4 solution results in high contents of V2O5 in the composite films. The in-situ electrochemical impedance spectra for the second step of V_2O_5-deposition at the PANi-film electrodes were measured. The impedance increases as the oxidative deposition of V_2O_5 proceeds. Polyaniline film is also oxidized during the second "V_2O_5-deposition step in the high temperature acidic solutions, which result in the polyaniline being overoxidized to a less conductive form.