LAUSR

Abstract Anode supported BCY (at the anode side) – BZY (at the cathode side) cells were fabricated, and local electronic conduction and internal partial pressures in the electrolyte were investigated using embedded Pt probes. It was observed that BCY-BZY electrolyte close to electrode interfaces exhibits n- and p-type electronic conduction in the electrolyte region close to the anode and the cathode, respectively. Based on these results, internal p H 2  and p O 2 in the electrolyte were estimated, and accordingly the change in internal p H 2 and p O 2 were relatively small in the electrolyte regions close to the anode and the cathode interfaces, respectively. Constant current tests were also conducted on the BCY-BZY electrolyte cells, and they were very stable under negative voltage operation, contrary to BCY single layer cells. Thus, the present study indicates that the utilization of a BZY layer at the cathode side is effective for establishing electronic conduction as well as chemical stability, which should improve the durability of BCY based PCFCs under severe operating conditions such as negative voltage.