Transport properties and battery discharge characteristics of the Ag+ ion conducting composite electrolyte system (1?x)[0.75AgI: 0.25AgCl]: xFe2O3

Ion transport and battery discharge characteristic studies are reported for a new Ag⁺ ion conducting two-phase composite electrolyte system (1?x)0.75AgI: 0.25AgCl]: xFe₂O₃, where 0 ≤ x ≤ 0.5 in molar weight fraction. An alternative single-phase host-matrix ‘annealed 0.75AgI: 0.25AgCl] mixed system/ solid solution’ has been used in place of the traditional host, AgI. Submicron size particles (<1 µm) of Fe₂O₃ has been used as second phase dispersoid. The composition 0.80.75AgI: 0.25AgCl]: 0.2Fe₂O₃, exhibiting the highest room temperature conductivity has been referred to as the optimum conducting composition (OCC). The reason for an enhancement of an order of magnitude in the conductivity from that of the pure host has been identified through direct determination of ionic mobility (μ) and mobile ion concentration (n) using transient ionic current (TIC) technique. The XRD study confirmed the coexistence of the constituent phases. The ionic transference number is found to be very close to unity. This reveals the fact that the silver ions are the sole charge carriers in the system. The results are discussed in the light of space-charge models proposed for the two-phase composite electrolyte systems. Solid state batteries, fabricated using OCC as electrolyte, Ag-metal as anode and mixtures of iodine &; graphite, viz. (C+I₂), (C+KI₃), (C+(CH₃)₄NI₃), (C+(C₂H₅)₄NI₃), etc. as cathodes, were discharged under different load conditions. The battery with (C+I₂) cathode performed satisfactorily specially under low current drain states.