Surface regulating and hetero-interface engineering of an LSCF cathode by CVD for solid oxide fuel cells: integration of improved electrochemical performance and Cr-tolerance

Abstract

The sluggish oxygen reduction reaction (ORR) kinetics and the fast performance degradation caused by Cr-poisoning greatly hinder the commercialisation of an La_xSr_1–xCo_yFe_1–yO_3–θ (LSCF) cathode in solid oxide fuel cells (SOFCs). Herein, a surface regulating and hetero-interface engineering method by chemical vapour deposition (CVD) was applied to construct a CeO₂-coated LSCF cathode with enhanced ORR activity and durability. By controlling the CVD operating time, and the thickness of the CeO₂ coating, the CeO₂/LSCF heterointerface could be precisely engineered. With the optimal CVD time of 7 min, the x-LSCF cathode exhibited a minimal polarisation resistance (R_p) value of 0.11 Ω cm² at 750 °C, which is almost one-fifth of that of an LSCF cathode (0.46 Ω cm²). Moreover, the CeO₂-coated LSCF cathode exhibited a much lower degradation rate than the LSCF cathode in the long-term Cr-poisoning test. The improved ORR catalytic activity and durability of the CeO₂-coated LSCF cathode were also verified in the single-cell mode. This study provides a comprehensive and novel strategy for tailoring the surface of the SOFC cathode for achieving enhanced performance and Cr-tolerance.