Composite Nd_(0.1)Ce_(0.9)O_(1.9)-BaZr0.1Ce0.7Y0.2-xYbxO3 electrolytes for intermediate temperature-solid oxide fuel cells

摘要

Composite electrolytes based on both proton and oxygen-ion conductors are designed for the operation of solid oxide fuel cells (SOFCs) at the intermediate temperature (IT, 500-700°C). Ceria-based oxygen-ion conductors such as Nd0.1Ce0.9O2-δ (NDC) have attracted attention as alternatives of yttria-stabilized zirconia (YSZ) electrolytes due to their high ionic conductivity at the IT. However, NDC materials are reduced at low oxygen partial pressure. Proton conductors such as BaZr0.85Y0.15O3-δ (BZY) have also received considerable attention as electrolytes of protonic ceramic fuel cells (PCFCs), because protons have lower activation energy for ion diffusion than that of oxygen ions. However, a high sintering temperature is required to densify BZY pellets. In this work, co-ionic (H+/O2-) composite electrolytes are designed by compositing both oxygen-ion and proton conductors. Hybridization of NDC and BZY materials may help to improve poor sinterability of BZY and prevent the electronic conductivity of NDC in reducing atmospheres. The performance of composite electrolytes is measured under real SOFC operating conduction.