Improved Long Term Performance Stability of Sr-Fe-O Infiltrated LSM/YSZ Solid Oxide Fuel Cells under High Steam and High Temperature

The LSM/YSZ cathode of commercial available anode supported button cells were infiltrated with a solution containing salts with strontium and iron cations in a 1:2 ratio. Both the uninfiltrated baseline cells and the infiltrated cells were evaluated for their performance and long-term stability in the humidified air and at high current density and high temperature. In comparison with baseline cell that experience severe performance degradation, Sr-Fe-O-infiltrated cells exhibited much higher performance and most importantly it significantly lowered performance degradation rate. This study demonstrated that appropriate nanomaterial infiltration can improve the cell performance and simultaneously mitigate performance degradation of solid oxide fuel cells. Nanostructure characterization using TEM revealed that LSM/YSZ baseline cell operated under steam was mainly caused by the formation of secondary phase nanoparticles and associated cracks along LSM/YSZ interfaces that are adjacent to the electrolyte. By contrast, Sr-Fe-O infiltration mitigated the formation of secondary phase particles and the associated nano-cracks in LSM/YSZ interface. Furthermore, Sr-Fe-O infiltration induced the formation of electrocatalyst of both Mn-Fe-O and Fe-doped LSM nano-particles on the surface of LSM and YSZ backbone, that could introduce additional new triple phase boundaries for adding the electrochemical reaction sites. In the meanwhile, there is continuous cation inter-diffusion between infiltrate and backbone and such cation exchange render the electronic conductor LSM backbone becoming Fe-doped LSM that is a mixed electronic conductor for further improving the cell performance.