EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Solid Oxide Cells (SOC) are some of the most efficient energy conversion devices for producing and consuming hydrogen. In this research, thermodynamic state analysis is applied to quantify a planar Solid Oxide Fuel Cell stack's degradation during a long performance experiment. The experiment demonstrated an atypical result: a consistent increase rather than a deterioration of terminal voltage after over 3 700 hours of operation. The distributions of specific Gibbs free energy of the anodic ceramic-metal composites are computed using the Ginzburg-Landau-type model of a multiphase system, known for its applications in phase-field models used for simulating microstructure evolution. The model accounts for the surface and interfacial energies of the metal and ceramic phases estimated from a three-dimensional microstructure reconstruction of the anodic composite. The phase distribution and the interfaces are determined using material data from Focused Ion Beam Scanning Electron Microscopy analysis of 10 samples of the SOC anode. Of the 10, one sample was taken from a reference electrode, corresponding to the state of the system prior to the long-term performance study, and the remaining samples were taken from 9 distinct sites: the fuel inlet, the middle and the outlet of three cells, located, respectively, at the bottom, in the center, and at the top of the Solid Oxide Cell stack. The anisotropy of degradation phenomena is illustrated and the main driving forces for the microstructure degradation are discussed.