关键词: 掺氢天然气, 内重整, 稳定性, 固体氧化物电堆

Abstract:

In this work, the long-term stability and degradation mechanism of a direct internal-reforming solid oxide fuel cell stack (IR-SOFC stack) using hydrogen-blended methane steam reforming were investigated. An overall degradation rate of 2.3%·kh^-1 was found after the stack was operated for 3000 hours, indicating a good long-term stability. However, the voltages of the two cells in the stack were increased at the rates of 3.38 mV·kh^-1 and 3.78 mV·kh^-1, while the area specific resistances of the three metal interconnects in the stack were increased to 0.276 Ω·cm², 0.254 Ω·cm² and 0.249 Ω·cm². The degradation of the stack might be caused by segregation of chromium on the surface of metal interconnects and the formation of SrCrO₄ insulating phase in the current collecting layer of the cathode, which result in an increase in the interfacial resistance and a decrease in the stack performance. The long-term performance of a flat-tube IR-SOFC stack could be further improved by suitably coating the metal interconnect surface. This work provides theoretical and experimental guideline for the application of hydrogen-blended methane steam reforming in flat-tube IR-SOFC stacks.

Key words: Hydrogen-blended methane steam, Internal-reforming, Stability, Solid oxide fuel cell stack