CHARGE AND MASS TRANSPORT IN THE AMORPHOUS PHASE OF (PEG OR PEO)(Y) LITHIUM TRIFLUOROMETHANE SULFONATE

nderstanding of charge and mass transport mechanisms in polymeric electrolytes is still in a rather undeveloped state. The present investigation was aimed at improving our understanding of the transport behavior in the amorphous phase of (PEO or PEG);The reptation model of deGennes predicts the self-diffusion of polymer melt to vary as the inverse square of the molecular weight (M), whereas present investigation indicated that it varied as the inverse of the 2.35 power of M; this deviation was explained by considering that a constraint release mechanism was operating in addition to reptation. Complexation of polymer with salt was found to reduce the polymer self-diffusion and the molecular weight of the polymer host had no apparent influence on either the cation or anion diffusivities. The diffusion coefficients of the polymer host, cation and anion and the ionic conductivities were enhanced as the salt concentration in the complexes was reduced. The so-called thermodynamic factor, important in expressions for the ion diffusion coefficients, was evaluated through a phenomenological model. An estimation of the distance of separation between ions in these complexes based on the ion densities suggests that there is a high probability of forming significant concentrations of ionic aggregates (charged and neutral). Using a friction coefficient formalism, a trend was established from our observations that among the entities (polymer, cations and anions) present in these complexes, cation-cation, cation-anion and cation-polymer interactions are the strongest.;The diffusion coefficients were measured using pulsed field gradient (PFG) nuclear magnetic resonance (NMR) method by monitoring the diffusions of...