Abstract

In order to accelerate the widespread application of solid oxide fuel cells (SOFCs), especially proton-conducing solid oxide fuel cells (PCFCs), it is crucial to develop a cathode material with high activity for the oxygen reduction reaction (ORR), excellent long-term stability and CO2 tolerance. Herein, an A-site deficient cobalt-free (Co-free) perovskite oxide Sr0.95Ta0.1Fe0.9O3-δ (S0.95TF) is prepared by introducing cation deficiencies into SrTa0.1Fe0.9O3-δ (STF), and it proves to be a highly active cathode. The increased oxygen vacancies, the decreased thermal expansion coefficient (TEC) value and improved CO2 tolerance, efficiently enhance electrochemical performance and durability during long-term stability testing. As a result, the area specific resistance (ASR) values of S0.95TF at 600 °C are only 0.095 and 0.42 Ω cm2 with the Sm0.2Ce0.8O1.9 (SDC) and BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) electrolytes, respectively. In addition, both of the single cells with S0.95TF cathodes, based on different electrolytes, can function stably for 200 h without obvious performance decrease. These results clearly demonstrate that S0.95TF is a highly promising candidate for both oxygen ion-conducting SOFCs and PCFCs.