Effect of plasticizers on magnesium-poly(ethyleneoxide) polymer electrolyte

Solid polymer electrolytes (SPEs) of poly(ethyleneoxide) and magnesium trif late, which are plasticized with propylene carbonate (PC), ethylene carbona te (EC) and a mixture of PC and EC, are studied for their conductivity, ac impedance of the Mg I SPE interface, cyclic voltammetry, infrared spectrosc opy and differential scanning calorimetry. in the presence of plasticizers, the ionic conductivity (a) increases from a value of 1 x 10(-8) S cm(-1) t o about 1 x 10(-4) S cm(-1) at ambient temperature. The a is found to follo w a VTF relationship with temperature. The values of the activation energy, pre-exponential factor and equilibrium glass transition temperature are sh own to depend on the concentration of plasticizer. Ac impedance studies ind icate lower interfacial impedance of Mg/plasticized SPE than stainless stee l/plasticized SPE. The impedance spectra are analyzed using a non-linear le ast square curve fitting technique and the interfacial resistance of Mg/pla sticized SPE is evaluated. The cyclic voltammetric results suggest a quasir eversible type of Mg/Mg2+ couple in plasticized SPE. (C) 2000 Elsevier Scie nce B.V. All rights reserved.