Electronic to ionic conductivity of glasses in the Li 2S–Sb 2S 3–P 2S 5 system

Abstract

There is great interest in sulfide glasses because of their high lithium ion conductivity. New sulfide glasses in the Li 2S–Sb 2S 3–P 2S 5 system have been synthesized by classical quenching technique. The glass domain relays on the medium-lithium content (up to 50% molar). Electrical conductivities of the samples have been determined by Impedance Spectroscopy. The isothermal conductivity curves exhibit two regions on dependence of lithium content implying that the conductivity mechanisms in these two regions are different. The compositions of low lithium content (below 20% mol.) have presented low electronic conductivities close to 10 − 8 S/cm at room temperature. The compositions of medium lithium content (30–50% mol.) could be mixed ionic–electronic conductors with predominant ionic conductivities with a maximum close to 10 − 6 S/cm for sample with 50% Li 2S at room temperature. Arrhenius exponential behavior is verified between 25 °C and T g for all glasses. The activation energies, determined from temperature dependence, are 0.55–0.64 eV. A comparative study with glasses belonging to the other chalcogenide systems has been undertaken on base of the weak electrolyte model and the values of decoupling index, R τ , are reported. The impedance of the 0.5Li 2S–0.3Sb 2S 3–0.2P 2S 5 ionic conductor can be described by an equivalent circuit R(RQ)(RQ).