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

Abstract

Abstract Analyses of gas transport and hydrocarbon internal-reforming chemistry in nickel/yttria-stabilized zirconia (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.