Improving the Activity and Stability of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3‐δ Cathode Through Surface Modification with an Electro‐Catalyst

Abstract Although the conventional commercial solid oxide fuel cells cathode La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3‐δ (LSCF) exhibits excellent electrochemical performance, its oxygen reduction reaction (ORR) kinetics are still sluggish, and Strontium (Sr) segregation is also an issue for long‐term stability. Herein, a Sr‐free electro‐catalyst PrBa 0.9 Cs 0.1 Co 2 O 5+δ (PBCsC) is infiltrated on the surface of LSCF to form a PBCsC‐LSCF electrode, accelerating the surface oxygen exchange and thus improving the ORR activity and stability. PBCsC‐LSCF shows a higher concentration of oxygen vacancies and less Sr segregation, as confirmed by the analyses of X‐ray photoelectron spectroscopy (XPS). As a result, PBCsC‐LSCF demonstrates an area‐specific resistance of 0.010 Ω cm 2 at 750 °C, much lower than 0.067 Ω cm 2 of a bare LSCF. An improved peak power density of 1.70 W cm −2 is reached from the single cell with PBCsC‐LSCF at 750 °C, likely due to the higher oxygen surface exchange, as indicated by the distribution of relaxation time analyses. In addition, the cells' operational stability is greatly improved at a current density of 0.5 A cm −2 with a degradation rate of 0.055% h −1 , probably attributable to the suppression of Sr segregation by infiltration, as suggested by the XPS results.