Search

The anode porous transport layer (PTL) is a critical component of polymer electrolyte membrane (PEM) water electrolyzers, providing electrical conduction and water/oxygen transport to the anode catalyst layer. Platinum group metal (PGM) coatings are applied to titanium PTLs to prevent oxidation and preserve conductivity. To implement PEM water electrolysis on a large scale, it is essential to minimize the cost of mass-manufactured cell components while ensuring that defects in materials and components do not adversely affect the performance of the cell. In this study, we created gaps in the Pt coatings that are typically applied to PTLs to understand their effects on cell performance and inform on fabrication tolerances. The PTL coatings were fabricated by sputter deposition of Pt, intentionally leaving uncoated regions in either large patches or thin strips. For either geometry, the cell performance decreased with the increasing fraction of the uncoated regions. However, PTLs containing multiple thin uncoated strips caused a less severe performance effect than PTLs with continuous uncoated regions of the same relative total area. Through analysis of cell performance, impedance, and 3D charge transport modelling, we demonstrate that both the anode catalyst layer and membrane play a role in distributing current to mitigate the impact of coating defects at a short length scale. These results allow to draw conclusions about the tolerance requirements with regards to PTL coating uniformity in terms of both the size and total area of defects. [Display omitted] • Gaps of various geometries were artificially created in Pt coatings on Ti felt PTLs. • Narrow uncoated strips on PTL have less severe performance effect than large uncoated patches. • Anode catalyst layer and membrane play a role in distributing current to mitigate the impact of coating gaps. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane (PEM) water electrolysis is a promising technology to efficiently produce green hydrogen. Irregularities in membrane electrode assembly (MEA) component materials caused by manufacturing, processing, handling, or operation can lead to performance loss and failure. One example is the presence of pinholes in the membrane, which can cause increased gas transport (crossover) and lead to electrical shorting. This work investigates the effects of intentionally introduced pinholes with various sizes up to 350 μm in diameter. The presence of the pinholes resulted in minimal impacts on the cell voltage (±30 mV at 4 A cm−2). However, the pinholes significantly increased H 2 crossover, which decreased hydrogen production efficiency and increased the minimum current density for safe operation. The impacts of the pinhole on the H 2 crossover and efficiency are more severe for open pinhole features than tear-like pinhole features. This research demonstrates that even small pinholes cannot be disregarded from a safety, efficiency, and operating strategy perspective. • Pinholes impact PEM electrolyzer H 2 crossover, efficiency, and safety. • Pinholes have minimal impact on V–I curves. • Open-shaped pinholes increase hydrogen crossover dramatically more than tear-like pinholes. [ABSTRACT FROM AUTHOR]