Impedance Analysis of Ionic Transport in Polypyrrole-Polyazulene Copolymer and Its Charge-Discharge Characteristics

Ionic transport behavior across an electropolymerized polypyrrole/polyazulene composite film was investigated by using ac impedance analysis, and its charge-discharge characteristics were also studied. Co-electropolymerization of pyrrole and azulene was well defined and fairly stoichiometric in propylene carbonate solution. The charge capacity for the composite films showed a remarkable increase for films with about 50 to 75% of azulene monomer content, and the behavior was correlated with morphological and diffusivity changes. The charge-discharge characteristics were examined for cells with a lithium anode and various polypyrrole/polyazulene composite cathodes. Pure polypyrrole cathodes behaved exactly like a capacitor at low frequency, while pure polyazulene cathodes showed excellent rechargeable behavior with very flat discharge curves. Composite cathodes showed intermediate behavior.