Significant Suppression of Sr Segregation to Substantially Enhance Performance of La _0.6 Sr _0.4 Co _0.4 Fe _0.6 O _3‐δ Cathodes for SOFCs via Thermodynamic‐Kinetic Engineering

Abstract In advanced La _0.6 Sr _0.4 Co _0.4 Fe _0.6 O _3‐δ (LSCF) cathode for solid oxide fuel cells, Sr segregation form a dense oxide layer that inhibits oxygen reduction reaction (ORR) activity and stability. To address this issue, this study investigates the Sr segregation in materials using an optimized solid‐phase reaction method. This optimized solid‐phase reaction method generated LSCF (S‐R LSCF), introduces a homogeneous microstructure that can effectively reduce Sr migration. Comparing sol–gel generated LSCF (S‐G LSCF), S‐R LSCF shows lower crystallinity, smaller particle size, and significantly less Sr segregation. The optimized solid‐phase reaction is observed to effectively inhibit the segregation of Sr and improve the stability of the material, which can be attributed to the decreased formation of oxygen vacancies raised by compressive stress. Moreover, the thermal expansion coefficient (TEC) of S‐R LSCF is notably decreased to 13.3 × 10 ⁻⁶ K ⁻¹ , thereby substantially enhancing the durability of the material when utilized as a cathode. Such a S‐R LSCF cathode can achieve a 1.42‐fold higher power density, and a slower decay rate surpass 6 times than that of S‐G LSCF. This study effectively addresses Sr segregation in LSCF cathodes, leading to significant improvements in performance and stability, and provides a novel approach for exploring high‐performance cathode of SOFCs.