Effect of Microstructure of the Anode Support Tubes Towards SOFC Performance

Abstract

Reversible solid-oxide fuel cells (rSOFC) attract enormous attentions because of their capability to operate in both fuel cell and electrolysis modes. rSOFC with a tubular cell design has multiple advantages over a planar design for example allowing faster startup and shutdown. Successful fabrication of tubular cells needs to overcome numerous technological challenges, including control of its mechanical stress and high interlayer electrode resistance. The scope of the present work involves fabrication and testing of anode supported rSOFC single cells using both ionic conducting electrolyte and protonic conducting electrolyte. For the ionic conducting cells, the rSOFCs constituted Ni + yttria-stabilized zirconia (YSZ) anode support tube, Ni + scandia-stabilized zirconia (ScSZ) anode functional layer, scandia-stabilized zirconia (ScSZ) electrolyte, samarium doped ceria (SDC) protective layer, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) + SDC cathode functional layer, and LSCF cathode current collector layer, respectively. For the protonic conducting cells, BaZr0.1Ce0.7Y0.1Yb0.1O3-d (BZCYb) was used as electrolyte.In this work, sequential dip-coating coupled with co-firing technique was implemented over the thin film cell structure fabrication. The nickel based tubular anode supports were made from various methods, including extrusion, freeze-casting and dipping processes. To achieve low interlayer resistance and dense electrolyte layer, we have optimized the ceramic slurry (ink) formulation parameters. Cell performance and microstructure of the rSOFC will be discussed and compared with the available data.