Operando Magnetic Resonance Imaging for Visualizing Electrochemical Triple-Phase Boundary

Area of Science:

• Electrochemistry
• Materials Science
• Imaging Techniques

Background:

• The triple-phase boundary (TPB) is critical for electrochemical devices like fuel cells and batteries.
• Conventional methods fail to capture dynamic TPB processes and flooding.
• Understanding TPB evolution is key to improving device performance.

Purpose of the Study:

• To develop and apply operando electrochemical magnetic resonance imaging (EC-MRI) for real-time TPB visualization.
• To investigate the relationship between power output, water content, and TPB dynamics in proton exchange membrane fuel cells (PEMFCs).
• To elucidate the primary cause of flooding at the TPB.

Main Methods:

• Operando electrochemical magnetic resonance imaging (EC-MRI) using ¹H sensitivity.
• Non-invasive probing of bulk and boundary regions in operational devices.
• Studying PEMFCs with a focus on the oxygen reduction reaction (ORR).

Main Results:

• EC-MRI quantitatively mapped TPB evolution in real-time during PEMFC operation.
• TPB maps showed significant spatial and dynamic variations correlating with power output.
• TPB deterioration was identified as the direct cause of flooding, independent of water accumulation.

Conclusions:

• Operando EC-MRI provides unprecedented insights into TPB behavior under working conditions.
• TPB deterioration is the critical factor triggering flooding in PEMFCs.
• Findings offer new strategies for water management and TPB design in electrochemical devices and processes.