Abstract
Long term durability and reliability tests of five different types of SOFCs and stacks, which have been developed by Kyocera, MHI, MMC/KEPCO, Tokyo-gas and TOTO, were carried out under the NEDO project (FY2008–2012). In this paper, we report the result of durability tests of segment-in series tubular type SOFC stacks fabricated by MHI. The voltage loss factors such as internal resistance and polarizations of anode and cathode were also determined by the electrode performance model. The cathode polarization of improved segment-in series tubular type SOFC stack was greatly reduced and the durability of stack was also improved by the application of cathode side SDC/YSZ interlayer. In the long term durability test, improved stacks exhibited no degradation for 10,000 hours without chromium exposure and also strong tolerance against chromium contamination in cathode air for 15,000 hours (degradation rate of output voltage: 0.16%/1,000 hours).