Thermodynamics of Non Aqueous and Pure Ionic Electrolyte Solutions

The development of thermodynamic models for non-aqueous electrolyte systems is a mostly unexplored field. In electrolyte models, the dielectric constant ε plays a significant role as physical input parameter governing the interactions of electrolytes. The often-drastic shift of ε in different solvents requires more physical‑based theories in the model. Further, with increasing electrolyte concentration, ε in the mixture exhibits an initial drastic reduction, ultimately ending in ε of the pure electrolyte.
The thermodynamic equation of state (EoS) ‘electrolyte Perturbed‑Chain Statistical Associating Fluid Theory’ (ePC‑SAFT) is further developed in this work and validated against thermodynamic equilibria including ionic liquids (ILs).
In this work, a concentration-dependent ε(x) was introduced together with the formal derivatives towards component concentration combined with a updated expression for solvation energies. Ultimately, this work led to the development of the new electrolyte EoS ePC-SAFT advanced. With this, it is now possible to calculate Gibbs energies of transfer and solvation, to, for the first time, accurately predict activity coefficients of either solvent and solute as well as an application towards salt solubility in non-aqueous surroundings.