A systematic study of electrolytes has been conducted to explore how solution structure dictates electrolyte properties. Specifically, the transport properties (viscosity, conductivity and molar conductivity) of acetonitrile-lithium salt mixtures, (AN)n-LiX, are reported for electrolytes with LiPF6, LiTFSI (i.e., LiN(SO2CF3)2), LiClO4, LiBF4 and LiCF3CO2. These salts have widely varying ion solvation/ionic association behavior which is directly reflected in the transport properties of the AN solutions. Information about the solution structure has been utilized, in concert with molecular dynamic (MD) simulations, to provide mechanistic explanations for the variability noted in the transport properties of the electrolyte mixtures.

Solution structure is the key determinant for electrolyte properties, but little is known about the ion solvate structures present in liquids. A detailed exploration of this topic is begun here utilizing acetonitrile (AN) due to the simplicity of this solvent's interactions with Li + cations. Phase diagrams have been prepared for (AN) n -LiClO 4 and -LiBF 4 mixtures (salts with intermediate ionic association). The solvate species present in the solid and liquid phases have been analyzed utilizing single crystal solvate structures and Raman spectroscopy to determine how the anion identity influences the solvate species equilibrium (i.e., ionic association and solvation number). The phase behavior and solvation interactions of these mixtures are compared with those for (AN) n -LiCF 3 SO 3 , -LiNO 3 and -LiCF 3 CO 2 mixtures (salts which are highly associated). Quantum chemical calculations for the (AN) n -LiBF 4 and -LiClO 4 solvates have been performed to aid in the analysis. Results from MD simulations for (AN) n -LiBF 4 and -LiClO 4 mixtures have been compared to the experimental work to explore both the insight gained and limitations of the experimental work and simulations for electrolyte characterization.

In this study, LiBF4 mixtures with the cyclic carbonate ethylene carbonate (EC) and ester γ-butyrolactone (GBL) have been investigated. To determine how the physical properties of these electrolytes are influenced by the solvation that exists, a multi-step process has been employed. Each system has been tested via DSC analysis to produce phase diagrams. From the phase diagrams, single crystal solvates were obtained and analyzed using XRD analysis to determine the solvate structures that are present in the solid-state. Raman spectroscopy was used to determine the degree of solvation that is present in the liquid electrolytes, which may then be directly correlated to the physical properties of the electrolyte.

Phase diagrams have been prepared for cyclic carbonate and ester mixtures with LiClO4. A Raman analysis of the mixtures enables the determination of the degree of solvation of the Li+ cations. Key insight into the link between solvent structure and solvation is obtained. It was discoverd that GBL solvates Li+ cations more effectively than EC despite having a lower permittivity than EC.

not Available.