Time-dependent performance change of single layer fuel cell with Li0.4Mg0.3Zn0.3O/Ce0.8Sm0.2O2−δ composite

Abstract A Large-size engineering single layer fuel cell (SLFC) consisting of a nano-structured Li 0.4 Mg 0.3 Zn 0.3 O 2− δ /Ce 0.9 Sm 0.1 O 2− δ (LMZSDC) composite with an active area of 25 cm 2 (6 cm × 6 cm × 0.1 cm) is successfully fabricated. The SLFC is evaluated by testing the cell durability with a time-dependent degradation using an H 2 fuel and an air oxidant at 600 °C for over 120 h. A maximum power of 12.8 W (512 mW cm −2 ) is achieved at 600 °C.In the initial operation stage around 50 h, the cell's performance decreases from 12.8 to 11.2 W; however, after this point, the performance was consistently stable, and no significant degradation is observed in the current density or the cell performance. The device performed excellently at low temperatures with a delivered power output of more than 250 mW cm −2 at a temperature as low as 400 °C. By curve fitting the X-ray photoelectron spectroscopy (XPS) results, the ratio of Ce 3+ /(Ce 3+ +Ce 4+ ) before and after the long-time operation is analyzed. The ratio increased from 28.2% to 31.4% in the electrolyte which indicates a reduction occurs in the beginning operation that causes an initial performance loss for the device power output and OCV. Electrochemical impedance analyses indicate that the LMZSDC had a high ionic transport, and the device had quick dynamic processes and, thus, a high fuel cell performance. The LMZSDC is a new type of ionic material that has been successfully applied to SLFCs.