Electrochemical and physical characterization of lithium ionic salt doped polyaniline as a polymer electrode of lithium secondary battery

Polyaniline films doped with lithium ionic salts such as LiPF₆ and LiBF₄ were prepared by using the electrolyte solution mixture of ethylene carbonate and dimethyl carbonate. The doping level of the polyaniline films was confirmed by X-ray photoelectron spectroscopy and dc conductivity experiments. A doping mechanism of lithium ion through the interaction with a nitrogen at imine site is proposed. Electrochemical cells of Li//polyaniline-LiPF₆ or Li//polyaniline-LiBF₄ were assembled to investigate electrical capacity and its trends over the repeated charge/discharge cycles. The capacity of Li//polyaniline cell was increased and then saturated over 15 cycles. However, it did not reach the half of theoretical capacity of polyaniline material. The mechanism of electrochemical reaction during charge/discharge process of Li//polyaniline cell is presented.