Cold Sintering of Anode-Supported 8YSZ/NiO-8YSZ Bilayers for Solid Oxide Fuel Cells

In this study, fabrication of anode-supported solid oxide fuel cells (SOFCs) by cold sintering process (CSP) of electrolyte and anode layers was studied for the first time. A crack-free thin layer of 8YSZ electrolyte supported by a porous NiO-8YSZ anode was obtained by using the cold sintering process at 200 °C and 450 MPa uniaxial pressure for 1 h which then was post sintered at 1225 °C in conventional furnaces. Despite the much lower post-sintering temperatures as compared to the conventional ones at about 1400 °C, a continuous electrolyte/anode interface that was free of any defects such as delamination was achieved. Monolithic electrolyte prepared under identical conditions reached 95% of its theoretical density. Utilization of the cold sintering process resulted in limited grain growth in the anode which enhanced long triple-phase boundary densities. SOFCs constructed from cold-sintered 8YSZ/NiO-8YSZ bilayers exhibited open-circuit potentials of 0.90–0.85 V at 700–800 °C, confirming a fairly dense 8YSZ electrolyte. The highest power density achieved at 800 °C was 158 mW/cm2, which most likely would have the potential to be improved significantly upon further decreasing the anode thickness.