Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic...

Area of Science:

• Materials Science
• Electrochemistry
• Imaging Techniques

Background:

• High-temperature polymer electrolyte fuel cells (HT-PEMFCs) rely on phosphoric acid (H3PO4) for proton conduction.
• Accurate characterization of H3PO4 distribution and concentration is crucial for optimizing fuel cell performance and durability.
• Existing methods struggle to precisely quantify H3PO4 concentration due to its wide range (40-100 wt%) within fuel cell components.

Purpose of the Study:

• To develop and validate a non-destructive imaging methodology for determining the local distribution and concentration of phosphoric acid in HT-PEMFCs.
• To address the challenges associated with quantifying varying H3PO4 concentrations within complex fuel cell architectures.

Main Methods:

• Utilized synchrotron-based X-ray tomographic microscopy with propagation-based phase contrast imaging.
• Implemented a referencing method and established calibration curves by correlating greyscale values with known H3PO4 concentrations in fuel cell components (gas diffusion layer, catalyst layer, membrane).

Main Results:

• Successfully imaged the local distribution and concentration of phosphoric acid within fuel cell components.
• Established reliable calibration curves for quantifying H3PO4 concentration across different components.
• Verified the non-destructive imaging methodology by comparing image-based acid content with results from chemical analysis.

Conclusions:

• Synchrotron X-ray tomographic microscopy with phase contrast imaging and referencing is a viable technique for quantifying phosphoric acid in HT-PEMFCs.
• This method overcomes limitations of previous techniques, enabling precise characterization of acid distribution.
• The validated methodology provides a powerful tool for fuel cell research and development.