Investigating Corrosion Degradation of Porous Transport Layers for PEM Water Electrolyzers Using on-Line ICP-MS

Abstract

The degradation of polymer electrolyte membrane water electrolyzer (PEMWE) is the net result of degradation phenomena across each component, which includes structural changes to the catalyst layer, deactivation of the electrolyte, loss of performance due to impurities in the feed water, and the corrosion and passivation of titanium-based bipolar plates (BPPs) and porous transport layers (PTLs).1, 2 This presentation will focus on PTL degradation, which has received relatively little attention compared to loss of performance related to catalyst and electrode degradation mechanisms. Generally, PTL degradation can be categorized into chemical/corrosion degradation and mechanical degradation. 3 In this work, we focus on corrosion degradation of the anode PTL. Titanium (Ti) is the state-of-the-art material for PTLs due to its stability and intrinsic electrical conductivity. Ti can however, develop an oxide layer in the harsh oxidizing conditions of the anode, thus reducing the effective electrical conductivity and cell performance. Coating the Ti parts with platinum group metals (Pt or Ir) is often used to protect against oxidation.4 An electrochemical flow cell system connected to an inductively-coupled plasma-mass spectrometer (ICP-MS) capable of detecting trace concentrations (<ppb) of dissolved elements in solution has been used to investigate the corrosion rates of the Ti-PTLs with and without coatings toward understanding factors influencing degradation mechanisms. The influence of various parameters such as potential, potentiodynamic profile parameters (e.g., scan rate, upper and lower potential limits), electrolyte type, and pH on the corrosion processes has been investigated. References Feng, X. Yuan, G. Liu, B. Wei, Z. Zhang, H. Li, H. Wang, J. Power Sources 2017, 366, 33.Babic, M. Suermann, F. N. Büchi, L. Gubler, T. J. Schmidt, J. Electrochem. Soc. 2017, 164, F387.Park, H. Oh, T. Ha, Y.I. Lee, K. Min, Appl. Energy 155 (2015) 866-880.Rakousky, U. Reimer, K. Wippermann, M. Carmo, W. Lueke, D. Stolten, J. Power Sources 326 (2016) 120–128. Acknowledgements This research is supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the H2NEW consortium. Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC under contract DE-AC-02-06CH11357.