Non-doped CeO2-carbonate nanocomposite electrolyte for low temperature solid oxide fuel cells

CeO 2 is an oxygen nonstoichiometric material for the coexistence of redox pair of Ce 3+ and Ce 4+ , even under an oxidizing atmosphere, and its self-doping is fulfilled bases on the multivalence characteristics. It has been served in versatile applications, including fuel cells and catalysis. Excellent electrochemical performances of solid oxide fuel cell (SOFC) have been achieved at intermediate and low-temperature range based on doped cerium oxide electrolyte. In this study, we utilize its self-doping form to prepare core-shell structure bi-phase nano-composite of CeO 2 and alkali carbonate (Li 2 CO 3 , Na 2 CO 3 and K 2 CO 3 ) through a two-step synthesis method. SEM, TEM, XRD, and EIS measurements were applied to characterize the morphology, crystal size, the ionic conductivity of the electrolyte, and the electrochemical performance of resulting ceramic fuel cells . An exceptional ionic conductivity of 0.34 S cm −1 was generated at 550 °C in air, significantly different from its insulating property of the perfect CeO 2 phase. A power density of 910 mW cm −2 was also achieved as the highest electrochemical performance of a single cell. The multi-ionic conduction behavior of CeO 2 -carbonate is also discussed. The results reveal an effective approach to develop alternative SOFC electrolyte materials for low-temperature, high-performance energy conversion applications.