Oxidation failure modes of anode-supported solid oxide fuel cells

Investigations on anode-supported solid oxide fuel cells (SOFCs) using Ni-based anode supports are presented aiming at understanding how much oxidation such a cell can tolerate before incurring irreversible mechanical damage. The cells were oxidised both directly in air and electrochemically. The different oxidation procedures performed exhibited different damage modes. For free-standing cells oxidised in air, the main damage mode was electrolyte cracking after oxidation of approximately 50% of the Ni in the substrate. However, cells oxidised electrochemically failed by substrate cracking after only ca. 5% of the Ni was oxidised, mainly due to the non-uniform nature of oxidation in the SOFC. Models of the stress generation and fracture processes were developed for interpretation of the results.