Effect of high temperature creep behavior of component materials on long-term performance of SOFCs

Fuel cells are high-efficiency energy conversion devices that are environmentallyfriendly with little or no toxic emissions. The solid oxide fuel cell (SOFC) continues toshow great promise as a future power source, with potential applications in stationarypower generation and as auxiliary power units. At high operating temperature, however,creep deformation of component materials becomes relevant when the operatingtemperature exceeds or even is less than half of its melting temperature (in degrees ofKelvin). The operating temperatures for most of the SOFCs under development arearound 1,073 K. With most stainless steels having a melting temperature around 1,800 K,possible creep deformation of the ferritic interconnect under a typical cell operatingtemperature should not be neglected. Meanwhile, typical glass sealants used in planarSOFCs are also characterized by the creep behavior at the SOFC operating temperature.This chapter describes how the effects of the creep behavior of component materials onstack geometry change, and the stress redistribution of different cell components arepredicted and summarized. The goal of the study was to investigate the performance ofthe fuel cell stack by obtaining the change of the fuel- and air-channel geometry due tocreep of the ferritic stainless steel IC, therefore indicating possible changes in SOFCperformance under long-term operations. Finite element analyses were performed toquantify the deformed configuration of the SOFC stack under the long-term, steady-stateoperating temperature.