A numerical tool to estimate SOFC mechanical degradation: Case of the planar cell configuration

The stress state and cell degradation have been modelled considering the classical solid oxide fuel cells (SOFCs) materials (Ni-YSZ//YSZ//LSM). The anode-supported cell is found to be un-cracked after its elaboration. However, the high level of energy stored in the thin electrolyte layer lowers the cell robustness as it constitutes the driving force for interfacial delamination. The elaboration of the electrolyte supported cell leads to the anode layer cracking. The heating up to 800 degrees C and the cermet reduction allow relaxing the stress level in the cell. For the anode-supported cell, the cermet re-oxidation induces cathode damage as soon as the anodic strain exceeds 0.05-0.09% whereas the electrolyte fracture occurs for strain ranging between 0.12% and 0.15%. For the electrolyte supported cell, the cermet re-oxidation induces a triggered risk of anode/electrolyte delamination when the anodic strain is higher than 0.3-0.35%. The risk of rupture initiation in cell singularities has been also investigated. A pure material electrode/electrolyte Singularity is harmless. A perpendicular corner at the electrode/electrolyte free edge constitutes a harmful singularity. (C) 2008 Elsevier Ltd. All rights reserved.