MIXED ELECTRONIC AND IONIC CONDUCTORS - A NEW ROUTE TO NAFION(R)-DOPED POLYANILINE

Nafion(R) 117-doped polyaniline films were prepared by two chemical me thods. The preparation procedures were very similar, differing only in the timing of the doping step, i.e. before or after film preparation. The method involving direct doping of neutral polyaniline in N-methyl pyrrolidone by the acid form of Nafion(R) is better. It enables the pr eparation of homogeneous films with electronic conductivities up to 0. 3 S cm(-1) and a doping level of sulfonate groups of up to 30%. Electr ochemical characterization reveals an improvement in the polyaniline d oping-undoping process kinetics compared with that of pure polyaniline films. The increased metal-insulator transition kinetics is explained by a high lithium diffusion coefficient, of the order of 10(-7) cm(2) s(-1), and a molecular entanglement of both polymeric networks deduce d from chronoamperometric experiments. The high cycle life and charge retention of this promising electrode material are demonstrated.