Electrochemical Impedance Spectroscopy of Core‐Shell Nanofiber Cathodes, with Ce<sub>0.9</sub>Gd<sub>0.1</sub>O<sub>1.95</sub> (Core) and Cu‐Doped La<sub>0.6</sub>Sr<sub>0.4</sub>MnO<sub>3</sub> (Shell), for Application in Solid Oxide Fuel Cells
ChemElectroChem