Durability Tests of Flatten Tubular Segmented-in-Series Type SOFC Stacks for Intermediate Temperature Operation

Abstract

Durability tests of flatten tubular segmented-in-series type SOFC stacks for intermediate temperature operation have been carried out since FY 2008 in the NEDO project, "Development of system and elemental technology on SOFCs". A short bundle composed of four cell stacks fabricated in FY 2009 showed a degradation rate of 0.31 % during the last 1000 hour of a 4000 hour continuous test at rated current density of 0.24 A/cm2 in an electric furnace, while another deteriorated by about 0.01 %/cycle in 100 thermal cycles. Secondary ion mass spectroscopy, scanning electron microscope and Raman spectroscopy analyses of tested cell stacks indicated that fuel leakage reduction at the cell stack surface, Cr poisoning reduction in cathode and uniform and dense formation of cathode interlayer were important for their durability improvement. FY 2010 durability tests are now in progress.