(576f) Modeling Electrolyte Systems: Recent Progress and Current Challenges

Recent advances in modeling electrolyte systems will be reviewed in the context of well-established and emerging needs in the chemical process industry. Development of models for systems containing aqueous, mixed-solvent, and non-aqueous electrolytes remains an active area of research. A large fraction of simulation needs can be met by using excess Gibbs energy models that account for ionic interactions on a semi-empirical basis. Here, one of the main challenges lies in correctly predicting ionic reaction equilibria, which usually play an important role in systems containing electrolytes. For this purpose, it is essential to account for both the standard-state properties of species as a function of temperature, pressure, and solvent environment and for their interactions at finite concentrations. In addition to thermodynamic properties and phase equilibria, it is increasingly important to account for transport properties (e.g., electrical conductivity) and surface properties (i.e., surface and interfacial tension) in practical applications involving electrolytes. Equations of state for electrolytes present an alternative to the excess Gibbs energy models and become particularly attractive for high-temperature applications. At such conditions, predicting the changes of ionization as a function of density and temperature remains an important challenge. Various applications that are providing a stimulus for electrolyte theory, models, and experimental techniques will be discussed. Such applications include problems associated with flow assurance (in particular, mineral scaling) and CO₂ capture and sequestration including the interactions between carbon dioxide and minerals. Of particular interest is the role of electrolyte properties in energy storage and hydrogen production. There is increasing interest in the properties of electrolytes in the context of materials synthesis and processing high-value inorganic materials. Furthermore, properties of electrolytes are essential for understanding and mitigating electrochemical corrosion. Examples of such applications will be discussed and analyzed to identify the gaps in electrolyte data and models.