Leveraging catalytic effects of heterointerfaces through multilayering for superior cathode performance

Abstract Cathode materials with high activity for oxygen surface exchange are required to achieve high-performance solid oxide fuel cells (SOFCs) at intermediate operating temperatures. LSC (La0.6Sr0.4CoO3-δ) and gadolinia-doped ceria (GDC, Ce0.9Gd0.1O1.95) thin films are alternately stacked to create multilayered cathode structures on yttria-stabilized zirconia (YSZ) electrolytes using pulsed laser deposition. Analysis of the electrochemical impedance spectra of symmetrical cells having varied number of LSC and GDC layers revealed that the existence of additional heterointerfaces leads to catalytic effects on the oxygen exchange properties. This is evidenced by a monotonic enhancement of the oxygen surface exchange coefficient (k*), commensurate with the increasing number of LSC-GDC interfaces. Due to the remarkable enhancement of the oxygen exchange properties, a significant lowering of the polarization resistance with increasing number of LSC-GDC interfaces is achieved. Furthermore, the LSC-GDC multilayers exhibited better long-term stability of the polarization resistance compared to a single-layer LSC in cell tests up to 600 h performed at 600 °C in air. These results highlight the important role of similar heterointerfaces in SOFC structures and provide guidance for the rational design of novel cathode materials with superior electrochemical performance at intermediate temperatures.