Electrochemical Impedance Spectroscopy of Core-Shell Nanofiber Cathodes, with Ce_0.9Gd_0.1O_1.95 (Core) and Cu-Doped La_0.6Sr_0.4MnO₃ (Shell), for Application in Solid Oxide Fuel Cells

Several core-shell nanofiber electrodes are prepared through electrospinning and tested for application as intermediate-temperature solid oxide fuel cell (IT-SOFC) cathodes. The materials investigated are La_0.6Sr_0.4MnO₃ (LSM), La_0.6Sr_0.4Cu_0.1Mn_0.9O_3-δ (LSCuM_1), and La_0.6Sr_0.4Cu_0.2Mn_0.8O_3-δ (LSCuM_2) perovskites, used at the shell side of the nanofibers. Ce_0.9Gd_0.1O_1.95 (GDC10) fluorite is used as the core material. The electrochemical characterization of the core-shell nanofiber electrodes is performed through electrochemical impedance spectroscopy (EIS). The EIS results are reported and discussed based on equivalent circuit modeling. The polarization resistance of the GDC10/LSM core-shell nanofibers electrodes is R_P∼4.5 Ω cm² at 650 °C. Improvement is accomplished with GDC10/LSCuM_1 and GDC10/LSCuM_2 core-shell nanofibers, with R_P∼1.8 Ω cm² and 1.7 Ω cm² respectively at 650 °C. Post-test SEM characterization is carried out, to ascertain possible degradation and identify the most promising shell perovskite.