Dual pore network modeling of coupled gas transport and electrochemical reactions in the cathode catalyst layer considering oxygen diffusion barriers at void–ionomer connections
Year: 2026
Type: article
Abstract: Proton exchange membrane fuel cells (PEMFCs) are promising clean energy-conversion devices, but their performance and durability are strongly governed by transport and reaction processes in the cathode catalyst layer (CCL). Here, a dual-network pore network model coupling oxygen diffusion, proton conduction, and electrochemical reaction was developed to clarify ionomer-dependent transport–reaction behavior in the CCL. Gas diffusion resistance is dominated by ionomer-related pathways, especially void–ionomer connections, while resistance in void pores is negligible. With increasing ionomer content, void–ionomer resistance decreases and ionomer–ionomer resistance increases. At low ionomer contents (<25%), the void pathway remains relatively open, but poor ionomer connectivity limits proton access and effective triple-phase-boundary formation, resulting in low catalyst utilization. Excessive ionomer (>30%) further improves proton conduction but leads to excessive Pt coverage by ionomer and increases local oxygen-diffusion resistance toward the Pt/ionomer interface, reducing oxygen-accessible active sites and aggravating concentration polarization. An intermediate ionomer content of 25–30% therefore provides the best balance among oxygen diffusion, proton conduction, and active-site availability, leading to enhanced reaction activity and catalyst utilization. The Damköhler-number analysis further suggests a shift toward active-site-utilization limitation in ionomer-rich structures. These results provide theoretical guidance for the efficient design of catalyst-layer microstructures.
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,560
Awards: G2615348439, G8080361281
OpenAlex ID: W7212284031