Comparative study on solid oxide fuel cell anode microstructure evolution after long-term operation

The evolution of solid oxide fuel cell anode microstructure during operation has important affects on cell performances and degradation. The degradation expectation requires a quantitative evaluation of the microstructure. In this work, anode support unit cells from 4 stacks are sampled and their anode functional layers and supports’ microstructure are evaluated with Focused Ion Beam-Scanning Electron Microscope and optical microscope. The cells are also cut into button cells and perform electrochemical evaluations. These compared microstructures reveal a time-related Ni migration that occurs from the functional layer deep into the support layer and Ostwald ripening. The change of Ni also affects the pore structure in the support layer and influences concentration polarization. The impact of microstructure evolution on electrochemical performance is revealed by Electrochemical Impedence Spectrum tests and Distribution of Relaxation Time analysis.