Residual stress change with time of a segmented-in-series solid oxide fuel cell using an in situ X-ray stress measuring method

Abstract The changes with time of the residual stress on the electrolyte were measured in situ during re-oxidation under solid oxide fuel cell (SOFC) operation conditions using a segmented-in-series (SIS)-type SOFC and a conventional anode-supported planar (ASP)-type SOFC to understand the mechanical behaviour of the materials in the SOFC. In situ X-ray residual stress measurement was successful, and the real-time change with time of the residual stress of the electrolyte was revealed under SOFC operating conditions. In the ASP-type SOFC, the residual stress changed from compression to tensile stress, and destruction of the cell was confirmed 20 min after the air introduction. In contrast, in the case of the SIS-type SOFC, the residual stress was almost constant, even when the anode material was exposed to oxidation conditions for more than 4 h. These results indicate that the SIS-type SOFC has a high tolerance against reduction and oxidation (redox) compared with the ASP-type SOFC, which requires a conductive support material with a high Ni content. This is because the SIS-type SOFC has an electrically insulated support material that does not require a high Ni content.