Open AccessAnalysis of Gas Permeation Phenomena in a PEM Water Electrolyzer Operated at High Pressure and High Current Density
Author(s) -
Maximilian Bernt,
Jonas Schröter,
Maximilian Möckl,
Hubert A. Gasteiger
Publication year - 2020
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abaa68
Subject(s) - permeation , anode , proton exchange membrane fuel cell , analytical chemistry (journal) , chemistry , cathode , nafion , membrane electrode assembly , membrane , electrolysis , hydrogen , chemical engineering , electrode , materials science , chromatography , electrochemistry , electrolyte , biochemistry , organic chemistry , engineering
In this study, on-line mass spectrometry is used to determine hydrogen permeation during proton exchange membrane water electrolyzer (PEM-WE) operation for a wide range of current densities (0–6 A cm −2 ) and operating pressures (1–30 bar, differential pressure). H 2 permeation measurements with a permeation cell setup, i.e., without applying a current, show a linear correlation between permeation rate and H 2 partial pressure, indicating diffusion as the main crossover mechanism. Measurements with full membrane electrode assemblies (MEAs) during PEM-WE operation reveal a significant increase of the gas permeation rate at high current densities, by up to ≈20-fold at 1 bar H 2 and up to ≈1.2-fold at 30 bar H 2 (Nafion ® 212 or Nafion ® 117 membrane; Ir-black (anode) and Pt/C (cathode)). Recently, H 2 super-saturation of the ionomer phase in the cathode catalyst layer was shown to be the reason for this increase, and we discuss the impact of this effect for different electrode compositions and operating conditions. Finally, the determined H 2 permeation rates and electrolyzer performance are used to discuss the overall PEM-WE efficiency for different membrane thicknesses and it is shown that the formation of an explosive gas mixture in the anode at low current densities requires additional mitigation strategies.