Effects of Porous Transport Layer Coating Inhomogeneities on PEM Water Electrolyzer

Abstract

The porous transport layer (PTL) is a critical component of polymer electrolyte membrane (PEM) water electrolyzers, transporting water to the anode catalyst layer, conducting electrons, and removing the produced oxygen. Ti materials such as felts, mesh, and sintered powders are commonly used as PTLs at the anode due to the good corrosion resistance and conductivity of Ti. However, Ti forms an electrically resistive oxide surface layer that has detrimental effects on the performance and durability of PEM electrolyzer cells. In order to permit the use of Ti PTLs in PEM electrolyzers, platinum group metals (PGMs) such as Pt and Ir can be used as a conductive, protective layer [1-3]. However, use of PGM coatings adds to the cost of PEM electrolyzers, and it is likely that future systems will use thinner coatings to minimize cost. To implement the PEM water electrolysis on a larger scale, it is essential to minimize the cost of mass-manufactured cell components while ensuring that inhomogeneities do not adversely affect the performance and durability of the cell and ultimately the stack. Improved understanding of impact of inhomogeneities on cell performance and durability is key to enabling this goal.This study investigates the impacts of PTL coating inhomogeneities on the performance of PEM water electrolyzers. Coating inhomogeneities of various geometries were artificially made on Ti felt PTLs to investigate the effects on the cell performance and understand fabrication tolerances. In addition, a model is developed to analyze the impacts of coating geometry on the surface current density distribution and local electric potential of the cell. Reference Kang, Z., et al., Effects of interfacial contact under different operating conditions in proton exchange membrane water electrolysis. 2022. 429: p. 140942.Liu, C., et al., Constructing a Multifunctional Interface between Membrane and Porous Transport Layer for Water Electrolyzers. 2021. 13(14): p. 16182-16196.Liu, C., et al., Exploring the Interface of Skin ‐Layered Titanium Fibers for Electrochemical Water Splitting. Advanced Energy Materials, 2021. 11(8): p. 2002926.