Model-based design and 3D characterization of a SOFC electrode microstructure

The characterization of SOFC performance and reliability has conventionally relied on bulk parameter measurements, such as fuel cell impedance and other electrochemical parameters. These bulk parameters, however, have increasingly been correlated with the porous microstructure of the electrodes but have yet to be fully linked to the degradation of the micro- and nanostructure of the electrodes during use. In this work, a design led approach to electrode manufacture is implemented. A Ni-ScSZ scaffold was first produced using tape casting and characterised using FIB-SEM tomography in order to quantify the TPB density as well as the tortuosity of the phases. This initial microstructure was also used as an input in a physically-based electrochemical model to predict impedance. The electrode was then incorporated into a symmetrical cell and tested at 610°C to compare its performance to the one predicted by the physical model as well as to examine the degradation of the anode with time. The comparison allowed for a critical assessment of the assumptions of the electrochemical model and for the prediction of better performance with different phase fractions. This approach allows for a seminal pass at manufacturing electrodes with desired specific performance requirements using a predictive model.