Improving the Activity and Stability of La0.6Sr0.4Co0.2Fe0.8O3‐δ Cathode Through Surface Modification with an Electro‐Catalyst

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.