Hydrogen Crossover in PEM and Alkaline Water Electrolysis

Mechanisms, Direct Comparison and Mitigation Strategies

verfasst von

P. Trinke, P. Haug, J. Brauns, B. Bensmann, R. Hanke-Rauschenbach, Thomas Turek

Abstract

This study provides a direct comparison of hydrogen crossover in PEM (Nafion 117) and alkaline water electrolysis (Zirfon) at a temperature of 60?C applying state-of-the-art separating unit materials. To this end, occurring crossover mechanisms are described first, before experimental data of the anodic hydrogen content are shown in dependence of current density, system pressure and process management strategy. The results suggest that permeation in PEM electrolyzers is mainly governed by diffusion due to a supersaturated concentration of dissolved hydrogen within the catalyst layer, showing a share of 98% of the total permeation flux at 1Acm-2 and atmospheric pressure. Permeation in alkaline electrolyzers also exhibits a significant influence of supersaturation, but the overall crossover is mainly influenced by mixing the electrolyte cycles, which makes up a share of 90% at 0.7Acm-2 and 1 bar. Generally it becomes evident that hydrogen permeation across the separating unit is more than one order of magnitude smaller in alkaline electrolysis, which is mainly a consequence of the significantly lower hydrogen solubility in concentrated KOH electrolyte. Finally, this study concludes with an assessment of the impact of separating unit thickness and provides mitigation strategies to reduce hydrogen crossover.

Organisationseinheit(en)

Fachgebiet Elektrische Energiespeichersysteme

Externe Organisation(en)

Technische Universität Clausthal

Typ

Artikel

Journal

Journal of the Electrochemical Society

Band

165

Seiten

F502-F513

Anzahl der Seiten

12

ISSN

0013-4651

Publikationsdatum

16.05.2018

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Elektronische, optische und magnetische Materialien, Erneuerbare Energien, Nachhaltigkeit und Umwelt, Oberflächen, Beschichtungen und Folien, Elektrochemie, Werkstoffchemie

Ziele für nachhaltige Entwicklung

SDG 7 – Erschwingliche und saubere Energie

Elektronische Version(en)

https://doi.org/10.1149/2.0541807jes (Zugang: Geschlossen)