Spatially Resolved Differentiation of Functional Degradation and Perforating Structural Defects in Membrane Electrode...

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Understanding membrane degeneration is key to extending the lifespan of polymer electrolyte membrane (PEM) fuel cells (PEMFCs) and water electrolyzers (PEMWEs).
• Local degeneration processes within membrane electrode assemblies (MEAs) significantly impact device longevity.

Purpose of the Study:

• To develop a spatially resolved analytical method for differentiating functional and structural degeneration in aged PEM membranes.
• To provide a tool for assessing membrane integrity under realistic operating conditions.

Main Methods:

• Utilized scanning electrochemical microscopy (SECM) combined with a flow-through diffusion cell (DiffC-DC-SECM).
• Employed ferrocyanide and protons as redox mediators for spatially resolved analysis.
• Performed SECM scans at cathodic potential to assess proton conductivity and at anodic potential to visualize structural damage.

Main Results:

• Successfully differentiated proton conductivity (functional) from structural damage like cracks and holes in various membrane types.
• Validated the technique on pristine PEMs, catalyst-coated membranes (CCMs) with artificial defects, chemically aged CCMs, and aged MEAs from operational PEMFCs.
• Demonstrated high local resolution for membrane integrity testing.

Conclusions:

• DiffC-DC-SECM is a powerful technique for localized membrane integrity testing in PEMFCs and PEMWEs.
• The method enables the development of more durable materials by identifying specific degeneration mechanisms.
• Facilitates realistic operational condition testing for improved long-term performance.