Abstract: The degradation and durability of SOFC stacks have been a major concern for commercialization. Many degradation factors should be taken into account for assuring the stability and the durability of cells, stacks and systems. To solve the degradation issues in cell and stack, the national project, “Development of system and elemental technology for SOFCs/ Fundamental research for improvement of durability” has been started in 2008 FY. In this project, the degradation factors were investigated in several cell-stacks and durability was improved after modification of the stacks. The degradation rates so far are about 0.3%/1000h or even better by the modification of materials, cell structures, and stack designs. Here we show a recent progress of stack durability and degradation mechanism. In addition, analyses of the degradation mechanism are shown in relation to the impurity condensation at active sites of electrode. Secondary ion mass spectrometry (SIMS) technique has been applied to detect the concentration levels of several elements (in the order of ppm level) at active components. Possible degradation mechanisms were suggested based on the observed impurity data.
