Freeze-casting for the fabrication of solid oxide fuel cells: A review

Freeze-casting, also called ice-templating, is a promising method to produce hierarchically porous ceramics with aligned and directional pores. Additionally, freeze-casting offers strict control over the pore sizes, the percentage of porosity, and morphology evolution. This method has found a wide range of applications. For instance, freeze-casting has emerged as a promising strategy to overcome the gas diffusion limitation through solid oxide fuel cell (SOFC) electrodes and to generate high power density. Firstly, the freeze-casting method, processing steps, and characteristics of the freeze-cast structures are presented. The effect of processing parameters including freezing conditions, solids loading and additives on the microstructure is reviewed. This article includes the developed processing routes and derived porous structures for fabricating both planar and tubular SOFCs through the freeze-casting method. Finally, discussions regarding applications are provided and suggestions for future investigations on the processing of freeze-cast electrodes and scaffolds for SOFCs are proposed.