New Neutron Imaging Detectors for PEMFC through-Plane Water Content Measurement

The current state-of-the-art in neutron imaging spatial resolution of 10 µm to 20 µm prevents applying the technique to study the through-plane water content of commercially competitive membranes and catalyst layers. There have been many studies focused on the water distribution in the gas diffusion layer, and some recent work has looked at thick membranes and thick catalysts in order to compare the measured water content with that predicted by models. The spatial resolution limit stems from the range of the charged particles that result from the neutron capture reaction which produces a large blur of light. We have explored several techniques to either reduce this blur, by using higher density scintillators, employing structured illumination, and magnifying the scintillation light, all with the goal of measuring the through-plane water content in commercially competitive materials with a spatial resolution of ~1 µm. As an example, shown in Figure 1 is a comparison of the measured water content in a fuel cell operated at the same current and voltage conditions when the scintillation light is magnified by a factor of 4. The top image is the standard setup where the scintillation light is imaged with a 1:1 macro lens, the bottom image is when the scintillation light is imaged with a magnification 4, infinity corrected microscope configuration. Figure 1