Degradation of SOFC Single Cells Under Severe Current Cycles

In this contribution, the degradation of solid oxide fuel cells (SOFC) is accelerated by means of high current load cycles. The ageing phenomena are studied and characterised by material analyses. The results show that degradation of cell performance is mainly caused by the delamination of the cathode layer. The accumulated delamination is ascribed to a loss in mechanical stability at the cathode-electrolyte interface. We find that the interface adhesion is degraded due to the formation of lanthanum zirconate between the cathode and electrolyte. This process is intensified by current density. Therefore, our contribution is of particular interest for the stability of the (La,Sr)MnO3-zirconia system. Furthermore, the results are an important preparatory step for applying Accelerated Life Testing (ALT) to SOFCs. In reliability engineering, ALT is a well known method that allows rapid lifetime evaluation.