Visualizing Internal Micro Damage Distribution in Solid Oxide Fuel Cells

Non-destructive evaluation of the bonding state between the components of all-solid-state power devices is important to ensure their performance and reliability. However, the thickness of all-solid-state power device components ranges from 10 to 100 μm, and their area ranges from 10 to 100 cm2. Furthermore, there are only a few methods for quantitatively observing large-area multi-layered interfaces, such as those in all-solid-state power devices, with a high spatial resolution. In this study, we investigated the use of terahertz waves, which are extremely permeable to oxides, in solid oxide fuel cells (SOFC), which are all-solid-state power devices, to evaluate the delamination of the interface between components. Specifically, the integrity of the cathode/intermediate layer interface of an anode-supported SOFC consisting of an anode/electrolyte/intermediate layer/cathode was evaluated. The obtained signals were classified using a self-organizing map, an information technology method, and then compared with the direct observation of the specimen cross-section. The classified terahertz wave signals and observation results were found to be in good agreement. Notably, this is the first time that terahertz waves have been used to quantitatively evaluate the interface delamination of all-solid-state power devices.