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

While solid oxide fuel cells (SOFCs) are considered potent candidates for future power generation systems owing to their high efficiency and fuel flexibility, it is yet far from their practical use mainly owing to high cost in manufacturing process. Since the costs for quality control and sintering steps rank as the top in total cost of SOFCs, the fabrication of large-area multilayers without processing defects at the interfaces and the decrease of sintering temperature should be achieved simultaneously for the cost-effectiveness. Here we firstly show that a simple and cost-effective roll calendering process for 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 roll calendering process are uniform regardless of cell size, facile particle rearrangements not only within the electrolyte layer but also at the interface between the anode and electrolyte layers can be achieved. It results in a uniform packing structure with high green density in the electrolyte layer and a good interfacial structure between the anode and the electrolyte. Consequentially, the thin (5.6 μm) and dense (relative density of 98.9%) electrolyte on the porous anode without processing defects is achieved after sintering at relatively low temperature of 1270○C, and a single cell based on the bilayer prepared by roll calendering process exhibits high power density of 880 mW/cm2 at 800○C, which is 1.5 times higher than that of a conventional cell prepared by uniaxial press and sintering at 1350○C.