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.