A Method for Time-Resolved Characterization of Polarization-Induced Solid Oxide Cell Microstructure Evolution

Abstract

Solid oxide cell long-term durability experiments are resource-intensive and have limited ability to capture the interdependence of microstructural evolution and electrochemical performance. Studies of microstructural degradation mechanisms are usually limited to before and after life-test images. Here we describe a life testing method that simultaneously operates multiple symmetric cells under different conditions, simultaneously providing information on electrolysis and fuel cell operation, while sampling the microstructure during operation. The method utilizes laser-cutting to exactly define different cell areas, allowing testing under different current densities with a single current source, and facilitating removal of segments of the cells during life tests, allowing for microstructural evaluation at intermediate times. The method is demonstrated in Ni-YSZ / YSZ / Ni-YSZ fuel-electrode-supported cells at low H2O/H2 ratios. Characterization using SEM-based imaging techniques shows pronounced microstructural damage that increases rapidly with increasing current density and time, mirroring observed electrochemical degradation. The present results agree with prior reports for SOC operation under such conditions but reveal new features of the degradation process via the unique capability of time-resolved imaging.