Comparative Investigation of Performance Degradation in Fuel Cell Membrane Electrodes during Long-Term Aging

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton-exchange membrane fuel cells (PEMFCs) require long-term operational stability for commercialization.
• Membrane electrode assemblies (MEAs) in PEMFCs suffer performance degradation due to complex, not fully understood mechanisms.
• Understanding catalyst layer degradation is crucial for improving PEMFC durability.

Purpose of the Study:

• To investigate the degradation mechanisms within the catalyst layer (CL) of a Pt/C catalyst.
• To correlate structural changes in the CL with electrochemical performance decay during long-term operation.
• To provide a multiscale perspective on the interplay between structural evolution and electrochemical degradation in PEMFCs.

Main Methods:

• Confocal Raman mapping was utilized to analyze the catalyst layer structure.
• Comparison of fresh and aged (5000 h) catalyst samples.
• Electrochemical measurements, including electrochemically surface area (ECSA) assessment.

Main Results:

• Significant electrochemical performance degradation (approx. 40% ECSA loss) was observed after aging.
• Spatial redistribution and reorganization of carbon structural features occurred in the aged CL.
• Anisotropic distributions of defect-related features within the CL were identified using Raman mapping.

Conclusions:

• Structural changes in the Pt/C catalyst layer are mechanistically linked to electrochemical degradation in PEMFCs.
• Carbon structural reorganization impacts the interfacial response of the CL.
• Confocal Raman mapping provides insights into the multiscale interplay of structural and electrochemical factors during PEMFC aging.