OLIGOMERIC PHTHALOCYANINE MODIFIED POLYANILINE - AN ELECTRODE MATERIAL FOR USE IN AQUEOUS SECONDARY BATTERIES

Polyaniline (PANI) and oligomeric phthalocyanine (PPC) are prepared an d characterized by spectroscopic and analytical methods. They are blen ded in different proportions and their blends are characterized by cyc lic voltammetry, electrochemical impedance measurements and are studie d as electrodes in aqueous secondary batteries. The cell Zn/0.1 M ZnSO 4/PANI-PPC is constructed and its charging-discharging behaviour is st udied at different current densities. The effect of oligomeric phthalo cyanine content on the cycle stability and the cell performance was al so studied. The impedance spectra of the system were studied in two-el ectrode and three-electrode modes. The charge transfer resistance is f ound to be potential dependent. The complex impedance of the system is found to be independent of frequency at high frequencies and it shows a complex capacitive behaviour at low frequencies. The cell shows a m aximum capacity of 93.3 Ah kg(-1) for a particular ratio of PANI to PP C in the system. The current efficiency was close to 100% over at leas t 1000 complete cycles when cycled between 1.2 to 0.6 V at a constant current of 0.9 mA cm(-2). The cell performance is stable at current de nsities ranging from 0.9 to 10 mA cm(-2). (C) 1998 Elsevier Science S. A. All rights reserved.