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The Effect of Ion Exchange Poisoning on the Ion Transport and Conduction in Polymer Electrolyte Membranes (PEMs) for Water Electrolysis

  • In water electrolyzers, polymer electrolyte membranes (PEMs) such as Nafion can accumulate cations stemming from salt impurities in the water supply, which leads to severe cell voltage increases. This combined experimental and computational study discusses the influence of sodium ion poisoning on the ionic conductivity of Nafion membranes and the ion transport in a thereon based water electrolysis cell. Conductivities of Nafion and aqueous solutions with the same amount of dissolved cations are measured with impedance spectroscopy and compared with respect to Nafion’s microstructure. The dynamic behavior of the voltage of a water electrolysis cell is characterized as a function of the sodium ion content and current density, showing the differences of the ion transport at alternating and direct currents. These experimental results are elucidated with a physical ion transport model for sodium ion poisoned Nafion membranes, which describes a proton depletion and sodium ion accumulation at the cathode. During proton depletion, the cathodic hydrogen evolution is maintained by the water reduction that forms hydroxide ions. Together with sodium ions from the membrane, the formed hydroxide ions can diffuse pairwise into the water supply, so that the membrane’s sodium ions can be at least partly be replaced with anodically formed protons.
Metadaten
Author:Maximilian Schalenbach, Lilli Keller, Benjamin Janotta, Alexander Bauer, Hermann Tempel, Hans Kungl, Martin Bonnet, Rüdiger-A. Eichel
URN:urn:nbn:de:hbz:832-epub4-20477
DOI:https://doi.org/10.1149/1945-7111/ac9087
ISSN:0013-4651
ISSN:1945-7111
Parent Title (English):Journal of The Electrochemical Society
Publisher:IOP Publishing
Document Type:Article
Language:English
Date of first Publication:2022/09/20
Date of Publication (online):2022/11/08
GND-Keyword:Nafion
Tag:Conductivity; Ion Transport; Nafion; Polymer Electrolyte Membrane; Water Electrolysis
Volume:169
Issue:9
Page Number:12
Institutes:Anlagen, Energie- und Maschinensysteme (F09) / Fakultät 09 / Institut für Werkstoffanwendung
Dewey Decimal Classification:500 Naturwissenschaften und Mathematik
Open Access:Open Access
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International