Self-stabilized hybrid cathode for solid oxide fuel cell: A-site deficient perovskite coating as solid solution for strontium diffusion

• Hybrid cathode is prepared by solution infiltration and in-situ phase formation. • Higher ORR activity is achieved by the introduction of LC95 coating. • LC95 coating works as solid solution to accept the diffused Sr species. • Remarkable durability is obtained by the single cell with hybrid cathode. Challenged by the surface strontium (Sr) enrichment, long-term stability of the La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) cathode remains to be the most intractable problem hindering its further development and application in solid oxide fuel cells (SOFCs). To enhance the durability and performance of LSCF-based electrodes, we propose a novel approach by introducing a highly active A-site deficient La 0.95 CoO 3-δ (LC95) thin film onto the surface of the porous LSCF scaffold, simultaneously working as the accepter for Sr diffusion and conformal collector for electrons conduction. Besides the inhibiting effect from the dense coating, the A-site deficiencies reserved in coating lattice enable promising stabilization for Sr diffusion and segregation. At 700 °C, the La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ @La 0.95 CoO 3-δ (LSCF@LC95) hybrid cathode shows a polarization resistance of 0.28 Ωcm 2 , much lower than that for pristine LSCF cathode (0.36 Ωcm 2 ). In addition to the higher electrochemical activity, single cell with LSCF@LC95 cathode exhibits remarkable long-term stability without detectable degradation over 120 h.