Observation of Fast Low-Temperature Oxygen Ion Conduction in CeO2/β"-Al2O3 Heterostructure.

Abstract

Semiconductor ion fuel cells (SIFCs) have demonstrated impressive ionic conductivity and efficient power generation at temperatures below 600°C. However, the lack of understanding of the ionic conduction mechanisms associated with composite electrolytes has impeded the advancement of SIFCs toward lower operating temperatures. In this study, a CeO2/β″-Al2O3 heterostructure electrolyte is introduced, incorporating β″-Al2O3 and leveraging the local electric field (LEF) as well as the manipulation of the melting point temperature of carbonate/hydroxide (C/H) by Na+ and Mg2+ from β″-Al2O3. This design successfully maintains swift interfacial conduction of oxygen ions at 350°C. Consequently, the fuel cell device achieved an exceptional ionic conductivity of 0.019S/cm and a power output of 85.9mW/cm2 at 350°C. The system attained a peak power density of 1W/cm2 with an ultra-high ionic conductivity of 0.197S/cm at 550°C. The results indicate that through engineering the LEF and incorporating the lower melting point C/H, there approach effectively observed oxygen ion transport at low temperatures (350°C), effectively overcoming the issue of cell failure at temperatures below 419°C. This study presents a promising methodology for further developing high-performance semiconductor ion fuel cells in the low temperature range of 300-600°C.