Polyaniline/zeolite as the cathode in a novel gel electrolyte primary dry cell

The ability of zeolite to accommodate and neutralize a great number of cations with all three mechanisms, adsorption, intercalation, and cation exchange reaction, combined with the high conductivity and stability of HCl-protonated polyaniline, which interposes into its laminar structure and the good contact between zeolite surface and polyaniline, make polyaniline/zeolite very suitable for a cathode electrode in dry electrical primary coin cells. Polyvinylalcohol (PVA) gel was used as the electrolyte and a Mg foil as the anode. The e.m.f. values of the cells ranged from 1.62 to 1.94 V, their specific energies from 4.34 to 8.88 Wh/kg and their energy densities from 3.10 to 6.34 mWh/cm(3) for cathodes containing 10-50% in zeolite. The parameter tau, which characterizes the aging rate of the polyaniline/zeolite cathode ranges between 70 and 320 h. The higher tau is, the slower is the aging of the sample. The best combination of high conductivity, slow aging of the cathode and high specific energy of the cells was obtained between 25 and 35% of zeolite content. Moreover, surface examination of the polyaniline/zeolite samples, was performed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. (C) 2003 Elsevier B.V. All rights reserved.