Increased Cathodic Kinetics in IT-SOFCs by Inserting Highly-Conductive Nanocrystalline Materials

Abstract

One of the crucial factors for improving intermediate-temperature SOFC performance relies on reduction of the activation loss originating from limited electrode reaction kinetics. We investigated the properties and functions of nanocrystalline interlayer via quantum simulation (QS) and electrochemical impedance analyses. Electrode impedances were found to decrease several-fold as a result of introducing a nanocrystalline interlayer and this positive impact was the most significant when the interlayer was a highly ionic-conductive nanocrystalline material. Both exchange current density and maximum power density were highest in the ultra-thin SOFCs (fabricated with MEMS compatible technologies) consisting of a 50nm thick nano-GDC interlayer. Oxygen vacancy formation energies both at the surface and in the bulk of pure zirconia, ceria, yttria-stabilized zirconia (YSZ), and gadolinia doped ceria (GDC) were computed from density functional theory, which provided insight on surface oxygen vacancy densities.