Investigation of Hot Pressed Polymer Electrolyte Fuel Cell Assemblies via Xray Computed Tomography

Q. Meyer, N. Mansor, F. Iacoviello, P.L. Cullen, R. Jervis, D. Finegan, C. Tan, J. Bailey, P. R. Shearing, D. J. L. Brett - Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London, WC1E 7JE, United Kingdom

The hot pressing process for fabricating membrane electrode assemblies (MEAs) has been widely adopted, yet little is known of its effects on the microstructural properties of the different components of the MEA. In particular, the interaction of the electrolyte, electrode and gas diffusion layer (GDL) due to lamination is difficult to probe as conventional imaging techniques cannot access the internal structure of the MEA. Here, a novel approach is used, which combines characterisation of hot-pressed membrane electrode assemblies using X-ray computed tomography, thermogravimetric analysis, differential scanning calorimetry and atomic force microscopy, with electrochemical performance measurements from polarisation curves and high-frequency impedance spectroscopy.

How Amira-Avizo Software is used

For all reconstructed volumes, post-processing and image segmentation was performed using Avizo Lite to segment the GDL layer material, consisting of large fibres bonded with PTFE, from the micro-porous medium, catalyst medium and the Nafion polymer membrane. (…) The actual surface area of the gas diffusion electrode (GDE) and hot pressed membrane was determined using X-ray CT scans using the surface area volume toolkit (Avizo) (…) The normalised contact area between two surfaces was calculated (…) using the surface area patch modules of Avizo.