MEASUREMENT METHODS | Structural Properties: Neutron and Synchrotron Imaging, In-Situ for Water Visualization

Abstract

Neutron- and synchrotron-based methods can be employed to study the distribution and evolution of liquid water in operating fuel cells. Depending on the technique considered, resolutions down to a few micrometers can be gained. Flow field design aspects, the influence of material properties, and the effect of operating conditions can be evaluated in terms of liquid water distribution, water removal and retention, and water transport behavior. Neutron and synchrotron radiographies therefore allow for an unperturbed insight into unmodified fuel cell setups resembling realistic conditions. The detailed description of properties and processes taking place in fuel cells and batteries is usually not accessible by other methods and offers a wide range of possibilities toward performance and design optimization. Examples given in the article cover details on neutron and X-ray imaging, water transport in fuel cells, and the evolution of liquid water. The range of applications described in this article has been extended to batteries in order to cover the full range of electrochemical power sources: the hydrogen transport and diffusion processes in alkaline and lithium batteries are accessible because of the high sensitivity of neutrons toward hydrogen and lithium.