Improved Performance of Solid Oxide Fuel Cells with the BaCo0.4Fe0.4Zr0.1Y0.1O3-δ Cathode by a Modified Acid Etch of Sm0.2Ce0.8O2-δ Electrolyte

The cathode/electrolyte interface bonding plays an important role in the electrochemical properties and long-term stability of solid oxide fuel cells (SOFCs). A modified acid etching technique of alternately dropping concentrated nitric acid and hydrogen peroxide on Sm0.2Ce0.8O2-delta (SDC) electrolyte (0, 5, 10, and 15 min) is developed to improve the bonding between the SDC and BaCo0.4Fe0.4Zr0.1Y0.1O3-delta (BCFZY) effectively. The 10 min-treated cell exhibits the maximum interface peeling strength (25.2 +/- 5.1 N/cm2) and the highest peak power density (1.443-0.169 W cm-2 at 923-723 K). More importantly, markedly enhanced long-term stability at 873 K is observed. The total degradation rate during 20-200 h for the 10 min-treated cell is only 0.102%. The improved performance should be closely associated with an increase in the contact area between the SDC and BCFZY as well as the rejuvenation of the SDC surface. In all, the developed acid etching technique leads to a significantly improved performance of the SDC-based SOFC, showing strong potential for application in distributed power stations.