A-site cation deficient SrTa0.1Fe0.9O3-δ as a bi-functional cathode for both oxygen ion- and proton-conducting solid oxide fuel cells

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 CO 2 tolerance. Herein, an A-site deficient cobalt-free (Co-free) perovskite oxide Sr 0.95 Ta 0.1 Fe 0.9 O 3-δ (S 0.95 TF) is prepared by introducing cation deficiencies into SrTa 0.1 Fe 0.9 O 3-δ (STF), and it proves to be a highly active cathode. The increased oxygen vacancies , the decreased thermal expansion coefficient (TEC) value and improved CO 2 tolerance, efficiently enhance electrochemical performance and durability during long-term stability testing. As a result, the area specific resistance (ASR) values of S 0.95 TF at 600 °C are only 0.095 and 0.42 Ω cm 2 with the Sm 0.2 Ce 0.8 O 1.9 (SDC) and BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) electrolytes, respectively. In addition, both of the single cells with S 0.95 TF cathodes, based on different electrolytes, can function stably for 200 h without obvious performance decrease. These results clearly demonstrate that S 0.95 TF is a highly promising candidate for both oxygen ion-conducting SOFCs and PCFCs.