Degradation Analysis of SOFC Stack Performance: Investigation of Cathode Sulfur Poisoning Due to Contamination in Air

Central Research Institute of Electric power Industry (CRIEPI) has tested on seven types of SOFC stacks, which are developed by MITSUBISHI HITACHI POWER SYSTEMS (MHPS), KYOCERA, TOTO, NGK SPARK PLUG, NGK INSULATORS, MURATA, and Denso in order to reveal their durability and find dominant degradation factor for each SOFC stacks under NEDO's project. Large degradation behaviors arising from SO2 in air have been observed in our site for the stacks of Kyocera's, TOTO's, NGK's, and Murata's. Therefore, the stacks were reexamined by adopting sophisticated chemical filter for SO2 removal, and a concentration of the sulfur in supplied air was measured. As results, acceptable degradation data have been obtained under the operation with chemical filter. Moreover, it was found that organic sulfur compound such as dimethyl sulfide almost comes through the physical filter and fed to their stack. In this study, we report our recent results on the durability and the change of degradation behaviors with chemical filter.