Study of ionic associations in solid lithium electrolytes with lithium electrode

Aim of project
The aim of the project is to describe the equilibrium between free ions and ionic aggregates in different temperatures, in salt- poly(ethylene oxide) and in model systems based on poly(ethylene glycol) dimethyl ether (PEGDME) and on mixtures of 1,2-dimethoxyethane and 1,4-dioxane, with electrochemical (dielectric constant) and acceptor-donor properties (AN and DN numbers) close to PEGDME. Use of variety NMR methods (19F NMR, 7Li NMR, 1H NMR) enables a more detailed study of ion-ion interactions than using Raman or FT-ir spectroscopy. The experiments will be performed mostly for lithium salts; because of the simplicity of experiments we have decided to use fl uorine-containing anions, such as BF4 –, CF3SO3 -, (CF3SO2)2N-. The measurements will give the information concerning the behavior of supramolecular additives in composite systems, which is particularly important due to competition of the cation and receptor in the anion complexation, or receptor and ionic pair in the anion complexation. Analysis of these interactions allows to choose the best receptor to the anion, with the best from the point of view of conductivity anion-receptor complex formation constant. The estimation of ion transference numbers by Newman method will supply additional information concerning influence of various ionic aggregates on ionic transport.

Expected results
The result of the project will be the estimation of complex formation constant in model lithium electrolytes with electrochemical and donor- acceptor properties similar to that of poly(ethylene oxide). These results allow a greater understanding of ionic association in these systems and thus obtaining electrolytes with enhanced cation conductivity.