In-situ measurements of oxygen concentration at the PEMFC cathode catalyst layer/membrane interface

The current trend in the development of Proton Exchange Membrane Fuel Cells (PEMFCs) towards high-power (>300 kW) applications is driving manufacturers to adopt ever-larger electrodes in pursuit of improvements in power density and durability required for heavy-duty use cases. One of the most significant challenges in large-format cells is maintaining a uniform oxygen concentration at the cathode. There are currently no direct techniques for measurement of the oxygen concentration at the interface between the cathode catalyst layer (CL) and membrane, where starvation is most likely to occur. In this work, a novel ‘instrumented membrane’ approach has been developed to address this gap in diagnostic capability. An in-situ, chronoamperometric oxygen sensor is fabricated directly on the PEMFC membrane. A data-driven model taking sensor DC current and impedance as inputs is able to predict local oxygen concentration at the PEM/catalyst layer interface with an accuracy of ±5 %. This in-situ diagnostic approach is demonstrated as a powerful tool for measuring and evaluating the distribution of oxygen in large-format PEMFCs, offering deep insights enabling improvements in system longevity and performance.