Novel hybrid conductors based on doped ceria and BCY20 for ITSOFC applications

Ceria-based composites have been previously developed as functional electrolytes for high performance ITSOFC applications. These composites display hybrid proton and oxygen ion conduction. To meet demands for more functional hybrid proton and oxygen ion conductors we developed further composite electrolyte materials containing a proton conductor, BaCe0.8Y0.2O3-delta (BCY20), and an oxygen ion conductor, samarium doped ceria (SDC). The BCY20 and SDC composites were prepared based on composite technology using their starting powders produced via sol-gel and co-precipitation processes, respectively. Using the SDC-BCY20 composites as the electrolytes ITSOFCs were constructed using NiO-based composite anodes, silver-based cathodes. Applying hydrogen as the fuel, compressed air as the oxidant, the fuel cells were tested in the temperature region between 300 and 700 degreesC. The SDC-BCY20 electrolyte ITSOFCs reached a performance of 0.25 W/cm(2) at 550 degreesC. Under a constant discharge water was observed both, on the anode and the cathode side, indicative of hybrid conduction based on proton and oxygen ion transport. Initial experimental results showed that combining a proton with an oxygen ion conductor forming a novel hybrid ion conductor with promising applications for ITSOFCs was successful. (C) 2004 Elsevier B.V. All rights reserved.