Electrochemical preparation and characterization of polypyrrole doped with bis(trifluoromethanesulfone) imide anions

Polypyrrole-bis(trifluoromethanesulfone)imide, PPy-TFSI, thin film electrode was prepared electrochemically by potential cycling or galvanostatically at a platinum electrode from a 0.5 M pyrrole/ 0.1 M lithium bis(trifluoromethanesulfone)imide, LiTFSI, /acetonitrile solution. The TFSI anion was selected as a dopant for polypyrrole because previous studies have shown that such polymer has a high electrical conductivity. The resulting PPy-TFSI film electrodes were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The apparent redox potential for a TFSI-doped polypyrrole film is slightly shifted to more positive potential in comparison to a perchlorate-doped film. This is related to the high delocalization of the charge of the TFSI anion which results in weaker anion–cationic polymer coulombic interactions. The low frequency capacitance and ionic resistance of the TFSI-doped polypyrrole are comparable to those reported for other polypyrrole film electrode.