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| Hauptseite > Publikationsdatenbank > Towards Predictive Non-Equilibrium Thermodynamics in Multi-Ionic Electrolytes: A Case Study in Buffered Electrolyte Dynamics |
| Hauptseite > Publikationsdatenbank > Towards Predictive Non-Equilibrium Thermodynamics in Multi-Ionic Electrolytes: A Case Study in Buffered Electrolyte Dynamics |
| Conference Presentation (Plenary/Keynote) | FZJ-2026-02874 |
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2026
Abstract: Predicting spatiotemporal concentrations and pH values in multi-ionic electrolytes accurately remains a central challenge for the development of electrochemical reactors[1]. A primary source of uncertainty stems from the scarcity of required transport properties and accurate models for thermodynamic driving forces. Physics-based modelling of electrochemical transport parameters and activity coefficients aims to overcome this lack of data. Here, a model based on the Mean Spherical Approximation and Onsager’s theory for transport properties is presented that predicts activity coefficients, diffusion coefficients, ionic conductivities, and viscosities based on a consistent unified-parametrization approach, minimizing the number of artificial parameters[2–4].To highlight the value of the developed model, the transient evolutions of simulated pH fronts of a buffered electrolyte under galvanostatic operation are compared to experimental data from a custom-developed optical reactor. The multi-ion property calculation includes homogeneous acid-base equilibria to capture how buffering reactions affect ionic fluxes and slow the propagation of pH fronts. The integration of multiple homogeneous reactions also highlights the invasive character of pH indicators on experiments. However, incorporating these reactions, along with ionic strength dependent transport properties modelled via the Mean Spherical Approximation, enables quantitative agreement between simulated and measured pH values.The case study illustrates how predictive physical modelling of electrolyte properties can improve predictions of electrochemical ion transport significantly, especially when compared to classically used models that omit concentration-dependences. Overall, this work highlights a pathway toward predictive, mechanism-based non-equilibrium thermodynamics for complex electrolytes relevant to electrochemical technologies.References1. Mistry, A. & Srinivasan, V. Do we need an accurate understanding of transport in electrolytes? Joule 5, 2773–2776; 10.1016/j.joule.2021.10.007 (2021).2. Janotta, B., Schalenbach, M., Tempel, H. & Eichel, R.-A. An assessment of electroneutrality implementations for accurate electrochemical ion transport models. Electrochimica Acta 508, 145280; 10.1016/j.electacta.2024.145280 (2024).3. Janotta, B., Schalenbach, M., Tempel, H. & Eichel, R.-A. Fitting ambiguities mask deficiencies of the Debye-Hückel theory: revealing inconsistencies of the Poisson-Boltzmann framework and permittivity. Phys. Chem. Chem. Phys. 27, 7703–7715; 10.1039/d5cp00646e (2025).4. Janotta, B., Schalenbach, M., Turiaux, M., Tempel, H. & Eichel, R. A. Buffering effects of supporting electrolytes on pH profiles in electrochemical cells. Scientific reports 15, 32458; 10.1038/s41598-025-18219-z (2025).
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