Unraveling Structure-Performance Trade-Offs in Porous Transport Layers for PEM Water Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Proton exchange membrane water electrolyzers (PEMWEs) are crucial for scalable hydrogen production.
• Efficiency losses in PEMWEs stem from complex transport and interfacial phenomena within the membrane electrode assembly.
• Porous transport layers (PTLs) significantly impact PEMWE performance due to their role in multiphase transport and interfacial contact.

Purpose of the Study:

• To develop and validate a multiscale computational framework for analyzing structure-performance relationships in PTLs.
• To identify design principles for PTLs that minimize interfacial resistance and improve PEMWE efficiency.
• To provide mechanistic insights into how PTL architecture affects voltage losses and overall performance.

Main Methods:

• Development of a multiscale computational framework combining pore network modeling and finite-element-based reactive transport simulations.
• Experimental benchmarking of the electrochemical model using commercial single-layer PTLs and microporous layer (MPL)-integrated configurations.
• Analysis of structure-performance trade-offs in various PTL architectures, including single-layer, bilayer, and stratified multilayer designs.

Main Results:

• The computational model achieved excellent agreement with experimental measurements.
• Single-layer PTLs show trade-offs between mass transport facilitation and increased contact resistance with the anode catalyst layer (ACL).
• Bilayer PTLs with thin, moderately dense MPLs effectively reduce voltage penalties by optimizing transport and contact.
• Stratified multilayer PTLs with a gradient of pore sizes enhance performance at high current densities.

Conclusions:

• The developed framework provides accurate and efficient resolution of structure-performance trade-offs in PTLs.
• PTL design, particularly porosity and layer integration, is critical for minimizing interfacial resistance and enabling high-efficiency PEMWE operation.
• Mechanistic guidelines for porosity-informed PTL design are established, paving the way for advanced PEMWE development.