Accurate 3D Fuel Cell Characterization Scott A Barnett, Northwestern University , DMR 1052678

1. Accurate 3D Fuel Cell CharacterizationScott A Barnett, Northwestern University, DMR 1052678 • A main objective of our collaboration with Danish Technical University (DTU) is to develop methods for accurate 3D measurements of electrodes • This slide highlights work done mainly by Kyle Yakal-Kremski (Northwestern student) and Peter Jørgensen (DTU postdoc) during Kyle’s visit to DTU • The aim was to assess the accuracy of three-phase boundary (TPB) lengths extracted from 3D images – error normally arises due to the voxelized nature of the images • A correction factor was calculated from idealized sphere structures by averaging over a wide range of sphere sizes and orientations TPB length error can be understood as follows. Image A above shows two spheres – while their intersection is nominally a perfect circle, the actual intersection is undulating (image B) because the 3D images are voxelized. Image C shows the TPB after smoothening, which corrects the TPB length but can also introduce error The plot at left shows the calculated correction factor versus the orientation of the TPB

2. Inkjet Printed Fuel CellsScott A Barnett, Northwestern University, DMR-1052678 • A benefit of our visits to Danish Technical University has been meeting scientists other than the ones we already knew • One such meeting, with Søren Jensen, led to him taking an extended (6 month) visit to Northwestern University (funded by non-NSF sources) • During the visit, Søren worked on a new project – inkjet printing of solid oxide fuel cells. The initial project was to deposit thin yttria-stabilized zirconia electrolyte layers. In future work, all fuel cell layers can be inkjet printed; this 3D manufacturing approach can be used to make novel fuel cell structures • Preliminary results suggest that inkjet printing can produce uniform, very thin, dense electrolyte layers such as the one pictured at right Cross-sectional SEM image of a solid oxide fuel cell where the thin (3 μm) dense yttria-stabilized zirconia electrolyte (middle) was produced by a $150 inkjet printer The fuel cell anode is below the electrolyte; the cathode is above