Electrochemical Impedance Spectroscopy of Core‐Shell Nanofiber Cathodes, with Ce${}_{0.9}$Gd${}_{0.1}$O${}_{1.95}$ (Core) and Cu‐Doped La${}_{0.6}$Sr${}_{0.4}$MnO${}_3$ (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${}_{0.6}$Sr${}_{0.4}$MnO${}_3$ (LSM), La${}_{0.6}$Sr${}_{0.4}$Cu${}_{0.1}$Mn${}_{0.9}$O${}_{3-\delta }$ (LSCuM_1), and La${}_{0.6}$Sr${}_{0.4}$Cu${}_{0.2}$Mn${}_{0.8}$O${}_{3-\delta }$ (LSCuM_2) perovskites, used at the shell side of the nanofibers. Ce${}_{0.9}$Gd${}_{0.1}$O${}_{1.95}$ (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 RP∼4.5 Ω cm${}^2$ at 650 °C. Improvement is accomplished with GDC10/LSCuM_1 and GDC10/LSCuM_2 core-shell nanofibers, with R${}_P$∼1.8 Ω cm${}^2$ and 1.7 Ω cm${}^2$ respectively at 650 °C. Post-test SEM characterization is carried out, to ascertain possible degradation and identify the most promising shell perovskite.