The Interdependence of Macro-and Microstructure on Internal-Reforming Performance in Ni-YSZ SOFC Anode Supports

This paper presents an analysis of the gas-transport and methane internal-reforming characteristics of two commercially developed solid-oxide fuel cell (SOFC) anode supports. The anode supports are fabricated by CoorsTek, Inc. (Golden, CO, USA) and RisO-DTU (Lyngby, Denmark). While both supports are ceramic-metallic composites of yttria-stabilized zirconia and nickel (Ni-YSZ), their morphological structures and thicknesses are quite different. The CoorsTek support is thick and displays an open microstructure, while the RisO-DTU support is fairly thin with a tighter morphology. These micro- and macrostructural differences lead to significant variations in gas transport and methane internal-reforming chemistry within the porous support structures that directly affect cell performance. In this study, anode-support performance is analyzed using the separated anode experiment, a unique tool that decouples anode-support thermal-chemistry processes from electrochemical processes typically underway during SOFC operation. Experimental results are interpreted using a detailed computational model. Gas transport is higher in the CoorsTek support despite being nearly five times thicker than the RisO-DTU support. The methane internal-reforming performance of the RisO-DTU anode, however, speaks to its tighter microstructure and resulting higher catalytic surface area. These results highlight the dependence of support performance on macro- and microstructure in terms of gas transport and internal-reforming chemistry.