Activation Energy−Activation Volume Master Plots for Ion Transport Behavior in Polymer Electrolytes and Supercooled Molten Salts

• Published in: The journal of physical chemistry. B Vol. 109; no. 35; pp. 16567 - 16570
• Main Authors: Ingram, Malcolm D, Imrie, Corrie T, Stoeva, Zlatka, Pas, Steven J, Funke, Klaus, Chandler, Howard W
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.09.2005
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp053400n

We demonstrate the use of activation energy versus activation volume “master plots” to explore ion transport in typical fragile glass forming systems exhibiting non-Arrhenius behavior. These systems include solvent-free salt complexes in poly(ethylene oxide) (PEO) and low molecular weight poly(propylene oxide) (PPO) and molten 2Ca(NO3)2·3KNO3 (CKN). Plots showing variations in apparent activation energy E A versus apparent activation volume V A are straight lines with slopes given by M = ΔE A/ΔV A. A simple ion transport mechanism is described where the rate determining step involves a dilatation (expressed as V A) around microscopic cavities and a corresponding work of expansion (E A). The slopes of the master plots M are equated to internal elastic moduli, which vary from 1.1 GPa for liquid PPO to 5.0 GPa for molten CKN on account of differing intermolecular forces in these materials.