Van Marum Colloquium: Thermodynamic modeling of the electrode-electrolyte interface - Double-layer capacitance, Solvation number, Validation
- Tuesday 14 November 2023
2333 CC Leiden
In this talk, I will give an overview of the thermodynamic modeling of the electrode-electrolyte interface and some important developments over the last few years. A central aspect is a mixture theory of electrolytes, which explicitly accounts for solvation effects. I will show that this model is the very basis for a qualitative and quantitative understanding of the double-layer capacity  and provide some detailed insights on a broad validation study in aqueous electrolytes .
More recently experimental studies were performed on Ag(111) and Au(111) in aprotic solvents and it was possible to interpret or predict the measured capacity curves with the same thermodynamic modeling framework where it turned out that some crucial parameters are (expectably) dependent on the actual solvent e.g. the solvation number . This slowly but steadily develops a comprehensive picture of the electrode/electrolyte interface for various solvents and ionic species. However some crucial experimental work is yet missing e.g. series of non-aqueous electrolytes with multi-valent ionic species and I will address some aspects in my talk. More recently it was also possible to incorporate the concentration- and electric field-dependency in the dielectric permittivity (or electrolytic susceptibility) which additionally contributes to the spatial structure of the electrolytic double layer.
Additionally our surface mixture theory  accounts for adsorption on the metal surface as well as for partial de-solvation thus leading to an overall precise model that is able to predict also unsymmetric capacity curves of strongly adsorbing ions (i.e. NaF or NaClO4 [2,3,4]). I will finally some aspects on poly-crystalline surfaces as well as applications of the model framework in various projects e.g. intercalation batteries and biological ion channels.
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