Enhanced sinterability and electrochemical performance of solid oxide fuel cells via a roll calendering process

Abstract

While solid oxide fuel cells (SOFCs) are considered potent candidates for future power generation systems owing to their high efficiency and fuel flexibility, they are far from being used practically, mainly owing to the high cost of their manufacturing process. Since the costs for the quality control and sintering steps rank as top of the total cost of SOFCs, the fabrication of large-area multilayers without processing defects at the interfaces and a decrease in sintering temperature should be achieved simultaneously for cost-effectiveness. Here we firstly show that a simple and cost-effective roll calendering process for the oxygen-ion conducting electrolyte, yttria-stabilized zirconia (YSZ), can effectively address the issues relevant to the processing defects and sintering temperature. Since normal and shear stresses applied in the roll calendering process are uniform regardless of cell size, facile particle rearrangements can be achieved not only within the electrolyte layer but also at the interface between the anode and electrolyte layers. This results in a uniform packing structure with a high grain density in the electrolyte layer and a good interfacial structure between the anode and the electrolyte. Consequently, a thin (5.6 μm) and dense (relative density of 98.9%) electrolyte on the porous anode without processing defects is achieved after sintering at the relatively low temperature of 1270 °C, and a single cell based on a bilayer prepared by the roll calendering process exhibits a high power density of 880 mW cm⁻² at 800 °C, which is 1.5 times higher than that of a conventional cell prepared by uniaxial pressing and sintered at 1350 °C.