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

Abstract

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 EA versus apparent activation volume VA are straight lines with slopes given by M = DeltaEA/DeltaVA. A simple ion transport mechanism is described where the rate determining step involves a dilatation (expressed as VA) around microscopic cavities and a corresponding work of expansion (EA). 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.

First and Second Universalities: Expeditions Towards and Beyond

“…Further measurements of both DC and dynamic conductivities [22,25,85,86] and shear fluidities [25], on other ionic liquids [25,82,85] and on polymer electrolytes [22,85,86], have meanwhile corroborated the findings exemplified above for BMIm-BF 4 . The validity of Eq.…”

In search of invariants for viscous liquids in the density scaling regime: investigations of dynamic and thermodynamic moduli

“…Exploiting ambient and high pressure experimental data for selected supercooled van der Waals liquids as well as the criterion for the power density scaling law, we have verified the ideas on some material constants suggested by Ingram et al [18][19][20] preliminary attempt at taking up the challenge is simply to address to the first theoretical grounds for the power law density scaling, which suggest that the density scaling exponent is proportional to the exponent of the dominant repulsive part of the effective short-range intermolecular potential [10,43,44,45,46]. On the other hand, in consequence of our investigations, the density scaling exponent gains a robust interpretation as the material constant which indeed relates molecular dynamics and thermodynamics of viscous liquids, providing an additional argument for the concept of 'the thermodynamic scaling of molecular dynamics' as the density scaling is sometimes called.…”

“…Therefore, they postulated that M p-T can be used to characterize dynamic 5 properties of various materials. What is more, taking into account the dynamic modulus as some kind of 'material constant', Ingram et al suggested [18] a straightforward relation between M p-T and a parameter characterizing thermodynamic properties of materials, i.e., the isothermal bulk modulus B T defined as the inverse isothermal compressibility…”

“…However, the proportionality between the dynamic and thermodynamic moduli, M p-T ~ B T , potentially providing a tempting linkage between molecular dynamics and thermodynamics of glass formers, were argued only phenomenologically by showing the same order of magnitudes of the moduli M p-T and B T in tested ionic systems by the authors [18][19][20].…”

Effect of cooling rate on enthalpy and volume relaxation of polystyrene

“…(12) is related to the Grü neisen parameter. Not without interest in this context is a recent publication by Ingram et al [53] on ion transport in polymer electrolytes. The proportionality between H * and V * is interpreted in terms of a 'new' modulus of elasticity, the value of which is found to be 2.4 GPa for PEO, 2.1 GPa for PPO, and 5.0 GPa for a molten mixture of calcium and potassium nitrates.…”