Effects of composite cathode on electrochemical and redox properties for intermediate-temperature solid oxide fuel cells

Abstract

A composite cathode composed of NdBa0.5Sr0.5Co1.5Fe0.5O5+δ (ΝΒSCF) and Ce0.9Gd0.1O1.95 (GDC) has been investigated to evaluate its electrochemical properties for intermediate-temperature solid oxide fuel cells (IT-SOFCs) based on structural characteristics and oxygen redox stability. The composite cathode has a lower polarization loss than a pure NBSCF cathode because the specific addition of GDC provides extended electrochemically active sites where the oxygen reduction reaction (ORR) occurs. Accordingly, the optimized NBSCF-40GDC cathode material had the lowest ASR, 0.074Wcm2 at 873K, resulting in excellent cell performance of 1.83Wcm-2 at 873K. In particular, investigation into the oxygen redox stability reveals that the composite cathode has superior redox stability under the operating conditions than a bulk NBSCF cathode material, which affects the long-term stability of the cathode performance.