Engineering of SOFC Anode/Electrolyte Interface

Cofiring of anode/electrolyte leads to improved mechanical adherence and lowers polarization losses at the anode. However, caused by different shrinkage of anode and electrolyte the compound is bending or breaking if it is under weight. Sintering experiments revealed that these mechanical stresses can be reduced by using an anode pattern consisting of a large number of small sized individual areas instead of a continuous layer. A simple static model was used to describe the shrinkage due to sintering by effective constant Young's moduli and pseudo linear thermal expansion coefficients (TEC). By the use of FEM different anode pattern geometries were analyzed with respect to curvature radius and mechanical stress in the electrolyte during cofiring. It turned out that anodes with a hexagonal pattern like honeycombs are preferable as they show small mechanical stress with high coverage at the same time.