Fabrication and Electrochemical Characterization of Freeze-Cast Tubular Solid Oxide Fuel Cells

The use of freeze casting is suggested as a solution to significantly increase the volumetric power density of Tubular SOFCs (TSOFCs) by enhancing gas diffusivity and triple phase boundary reactions. This paper reports the fabrication and characterization of freeze cast tubular anode supports for SOFCs. Tubular anode supports were fabricated using three methods: gelation casting, center pin method, and a freeze and drain method. A dual purpose freezing and drying chamber was designed and manufactured. The effects of slurry properties and process parameters were studied with respect to the resulting microstructures. The freeze and drain method was determined to be optimum for producing highly porous tubular anode supports with hierarchical, acicular or dendritic micro-pore channels. With an optimized freeze-drying cycle, drying time was reduced significantly with minimal residual moisture in the green bodies. Additionally, the electrochemical performance of the T-SOFCs with freeze cast anode was evaluated.