Facile fabrication strategy of highly dense gadolinium-doped ceria/yttria-stabilized zirconia bilayer electrolyte via cold isostatic pressing for low temperature solid oxide fuel cells

Gadolinium-doped ceria/yttria-stabilized zirconia bilayer electrolytes have received significant attention for use in solid oxide fuel cells since this electrolyte enables the use of a cobalt-containing cathode, which show a high performance at low temperature. However, the low sintering temperature of the bilayer electrolyte, which is required to avoid side reactions, results in low density, limiting its practical applications. In this study, we report a facile and cost-effective method for the fabrication of dense gadolinium-doped ceria/yttria-stabilized zirconia bilayer electrolytes at low temperatures. Even at a low sintering temperature of 1250 °C, a thin and dense bilayer electrolyte structure was achieved using an isostatic pressure process on the dip-coated electrolyte layers and anode support substrate. Solid oxide fuel cells adopting this dense gadolinium-doped ceria/yttria-stabilized zirconia bilayer electrolyte exhibited high power density of 1.251 W cm⁻² at 650 °C and high stability for 100 h. These significant improvements in performances is attributed to the greatly reduced porosity (<2.5%) of the bilayer electrolyte when there are no side reactions between the gadolinium-doped ceria and yttria-stabilized zirconia layers. The strategies presented here provide general guidelines on electrolyte design and processing for the fabrication of high-performance solid oxide fuel cells with low operation temperature, low cost and mass-producibility.