Structural Reliability of Cathode Contact Materials in Planar SOFCs
Despite significant developments in material and stack design technologies to enhance performance, the long-term mechanical reliability of solid oxide fuel cells remained an issue. The contact between electrodes and interconnects (especially the cathode side) was identified as one of the weakest links in present generation planar solid oxide fuel cells. Computational modeling was used to gain valuable insights on the cathode contact sintering mechanics and bond reliability. A continuum viscous sintering model was incorporated into a commercial finite element analysis code to simulate contact material densification and evaluate the bond and stack mechanical reliability due to developed stresses from the contact layer sintering. The parameters required for the cathode contact material constitutive model were extracted from experiments conducted for the contact material development at PNNL. The effects of contact layer thickness and sintering conditions like temperature and pressure on the stack stresses and reliability were investigated.