Gas transport and internal-reforming chemistry in Ni-YSZ and ferritic-steel supports for solid-oxide fuel cells

摘要

Analyses of gas transport and hydrocarbon internal-reforming chemistry in nickel/yttria-stabilized zir-conia (Ni-YSZ) and ferritic-steel supports for solid-oxide fuel cell applications are presented. The Ni-YSZ anode supports are fabricated using reaction-sintered powders (Ni-YRSZ) developed by CoorsTek, Inc. (Golden, CO, USA); the porous ferritic-steel supports are developed by PLANSEE SE (Reutte, Austria). The gas-transport and methane internal-reforming properties of these supports are measured using a unique "Separated Anode Experiment" that decouples these processes from electrochemical processes that are normally present in an operational SOFC. Experimental results are interpreted using a computational model. Despite significant differences in thickness and morphology between the Ni-YRSZ and ferritic-steel supports, results show that the rate of gas transport across the ferritic-steel support is comparable to that of the Ni-YRSZ support. While the Ni-YRSZ supports show extensive methane internal-reforming activity, the ferritic-steel supports are essentially inert towards methane reforming. This lack of internal-reforming activity in the metallic support motivates application of the computational model toward design of a Ni-YSZ anode-functional layer (AFL) to be placed atop the metallic support. Anode functional layers are found to provide a moderate level of internal reforming, though significantly lower than the complete Ni-YRSZ anode support, with very little effect on gas transport. The tools and methods presented here may be used for further design optimization of next-generation SOFC supports and architectures.