NMR and electrochemical study on lithium oligoether sulfate in polymeric and liquid electrolytes

Electrolytes based on lithium oligoether sulfate, and dissolved in liquid or polymer solvents, are studied. Their properties in term of ionic conductivities, transference numbers, diffusion coefficients, and electrochemical stabilities are reported. The comparison between NMR and electrochemical data, that is, transference numbers and conductivities, provides important information about the existence of ion pairs and aggregates. A fairly good agreement can be noticed between the highest occupied molecular orbital (HOMO) energies and the stability of the salts towards oxidation in relation with the length of the oligoether tail.