Cation-Dependent Ion Dynamics and Morphology in Metal-Contaminated Nafion Membranes
5 affiliations
- 1Institute of Energy Technologies (IET-1, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, Jülich, Germany, 52425
- 2Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, Aachen, Germany, 52074
- 3TUHH, Eißendorfer Straße 38, Hamburg, Germany, 21073
- 4Faculty of Mechanical Engineering, RWTH Aachen University, Eilfschornsteinstrasse 18, Aachen, Germany, 52062
- 5Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4–6, Berlin, Germany, 14195
Abstract
Metal cation contamination of Nafion proton-exchange membranes (PEMs) remains a persistent durability and performance issue in water electrolyzers as well as fuel cells. Contaminant metal cations originating from insufficiently deionized feed water, coolant leaks, or corrosion of metal cell components can bind to the sulfonate groups of Nafion, thereby interfering critically with proton transport. This work is the first joint experimental-simulation study that systematically elucidates the atomistic processes behind the metal-cation-based inhibition of proton conductivity in Nafion. The impact of humidity, metal cation charge, and temperature on morphology and ion transport is studied. Combining in-plane conductivity measurements of various metal cation impurities with classical molecular dynamics (MD) simulations reveals different water uptake at constant relative humidity (RH) driven by the chemical potential. The ion dynamics decrease from Li+ to K+ at constant RH, which is the exact opposite to the trend observed in bulk water. The apparent contradiction is identified as a consequence of the cation-water interaction dominating the water uptake and consequently the extent of percolation pathways. In contrast, the cation-sulfonate interaction is the decisive factor describing how the charge of metal cations impact conductivity in Nafion. By multidentate interaction of multivalent metal cations with multiple sulfonate groups, the pore is locally constricted disconnecting percolation pathways and inhibiting ion transport.
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BibTeX
@misc{mitra2026cationdependent,
title = {{Cation-Dependent Ion Dynamics and Morphology in Metal-Contaminated Nafion Membranes}},
author = {Souvik Mitra and Jialiang Liu and Kristina Fröhlich and Bianca Dißmann and Vasilii Korotenko and Rüdiger-A. Eichel and Christoph Scheurer and Simone S. Köcher},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008414/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008414/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Cation-Dependent Ion Dynamics and Morphology in Metal-Contaminated Nafion Membranes
AU - Souvik Mitra
AU - Jialiang Liu
AU - Kristina Fröhlich
AU - Bianca Dißmann
AU - Vasilii Korotenko
AU - Rüdiger-A. Eichel
AU - Christoph Scheurer
AU - Simone S. Köcher
PY - 2026
DA - 2026/09/07
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008414/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008414/v1
AB - Metal cation contamination of Nafion proton-exchange membranes (PEMs) remains a persistent durability and performance issue in water electrolyzers as well as fuel cells. Contaminant metal cations originating from insufficiently deionized feed water, coolant leaks, or corrosion of metal cell components can bind to the sulfonate groups of Nafion, thereby interfering critically with proton transport. This work is the first joint experimental-simulation study that systematically elucidates the atomistic processes behind the metal-cation-based inhibition of proton conductivity in Nafion. The impact of humidity, metal cation charge, and temperature on morphology and ion transport is studied. Combining in-plane conductivity measurements of various metal cation impurities with classical molecular dynamics (MD) simulations reveals different water uptake at constant relative humidity (RH) driven by the chemical potential. The ion dynamics decrease from Li+ to K+ at constant RH, which is the exact opposite to the trend observed in bulk water. The apparent contradiction is identified as a consequence of the cation-water interaction dominating the water uptake and consequently the extent of percolation pathways. In contrast, the cation-sulfonate interaction is the decisive factor describing how the charge of metal cations impact conductivity in Nafion. By multidentate interaction of multivalent metal cations with multiple sulfonate groups, the pore is locally constricted disconnecting percolation pathways and inhibiting ion transport.
ER -