Year: 2025
Type: preprint
Abstract: Understanding ion transport processes in polymeric ion exchange layers is an important direction for the development of bipolar membranes, particularly as the applications of these composite materials expand into concentrated and compositionally complex electrolytes. This work shows that the presence of salt (e.g. KCl) as an impurity in strong acid/base causes erosion of the transmembrane potential (the open circuit voltage, OCV) beyond what is predicted by the Nernst equation, and that this OCV erosion is related to increased salt crossover current under reverse bias polarization. We interrogate these phenomena through a combined approach of electrochemical experiments in a four-electrode setup and 1D continuum modeling. The results reveal that ion-ion associative interactions, which we represent in the model as reactions between mobile ions and fixed charge sites within the membrane, provide mechanistic pathways for the experimentally observed salt crossover and OCV erosion.
Source: ChemRxiv
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Harvard University, École Polytechnique Fédérale de Lausanne, Office of Science, Office of Energy Efficiency and Renewable Energy, University of Colorado Boulder, Basic Energy Sciences, Office of Energy Efficiency, National Science Foundation Graduate Research Fellowship Program
OpenAlex ID: W4413357313