Fluorite Alumina Fuel Cells

Abstract Solid oxide fuel cell (SOFC) is a promising technology for the hydrogen economy and clean energy production. However, the classical SOFC employing fluorite-type electrolytes such as yttrium-stabilized zirconia (YSZ) and Gd3+/Sm3+-doped CeO2 (GDC/SDC) faces significant technical challenges due to the required high operational temperature. Here, a groundbreaking result on alumina in fluorite structure deviated from the amorphous phase with high oxygen vacancy concentration is reported. Unlike lower valency cationic doping in traditional fluorite electrolytes, a higher-valency Ce4+ doping can further modulate fluorite alumina’s structural and electrical properties. Through electrochemical proton injection, we explored H+ transport coupled with intrinsic mobile O2- ions in Ce-doped alumina as an electrolyte, resulting in remarkable ionic conduction > 0.1 S cm-1 and a high fuel cell power density of 1057 mW cm-2 at 500 °C. The abundant nature and facile synthesis profile make fluorite a promising electrolyte material for next-generation SOFC.