Morphology and performance evolution by infiltration process on SOFC electrode: An integrated pore scale study

The mixed ionic and electronic conductive (MIEC) material plays critical roles in the development of intermediate-temperature solid oxide fuel cells, while the infiltration process is an important way to further improve effective reaction sites. In this study, a kinetic Monte Carlo method is employed for the reconstruction of initial backbones, followed by a three-dimensional numerical infiltration method. A lattice Boltzmann method is employed to comprehensively evaluate the electrochemical performance of the infiltrated electrode with the transport processes of species, electron and ion all considered. The numerical predictions with the volume ratios of La_0.6Sr_0.4CoO_3-δ: Gadolinia-doped ceria (LSC: GDC = 100:0% and 50:50%) show good agreement with the experimental results. The three-dimensional polarization characteristics and performance improvement mechanism of the infiltration electrode are thoroughly investigated. Under a backbone composition of LSC: GDC = 0.64:0.36, the optimal range of infiltration load for LSC catalysts is identified as 10% ~15%, while the desirable range for the GDC infiltrated electrode is approximately 5% ~10%. The selection of desirable infiltrated catalysts is closely related to the volume ratio of LSC:GDC. GDC catalysts are suitable for high LSC content backbones (>55%), while high GDC contents (>45%) correspond to LSC catalysts. The generation of three-phase boundary (TPB) reaction lines is more efficient for performance optimization than that of surface reaction areas. This study establishes a quantitative framework for real structure mesoscopic studies based on the LBM method and provides an important basis for infiltrated electrode performance optimization.