Comparison of Various Cathode Materials Fabricated by Pulsed Laser Deposition for Low-Temperature Ceramic Fuel Cells

Achieving reasonable performance in ceramic fuel cells at low operating temperatures is primarily hindered by the limitations of cathode properties. Aiming to formulate a guideline for the selection of cathode materials, we compared the most representative high-performance low-temperature cathode materials: lanthanum strontium cobalt oxide (LSC), samarium strontium cobalt oxide (SSC), praseodymium barium strontium cobalt iron oxide (PBSCF), and barium strontium cobalt iron oxide (BSCF) over the same anode-supported solid oxide fuel cell platform. The nanostructured LSC, SSC, PBSCF, and BSCF cathode layers were fabricated by pulsed laser deposition. The PBSCF cathode material showed the highest performance owing to the low activation loss and low polarization resistance under biased conditions. SSC exhibited the mildest degradation; however, its electrochemical performance was worse than those of LSC and PBSCF. LSC and PBSCF exhibited considerably high degradation rates, which were attributed to the surface composition alteration owing to strontium and/or barium segregation. At the same time, as-deposited BSCF exhibited significantly different microstructure from those of other cathode materials; it showed the worst performance and the fastest degradation as well, which was attributed to its composition and phase instability. Although numerous issues still need to be solved for the practical application of these cathode materials, we expect that the results of the present study will provide a guideline for selecting and improving cathode materials for the low-temperature operation of ceramic fuel cells.