Exceptionally High-Performance Reversible Solid Oxide Electrochemical Cells with Ultrathin and Defect-Free Sm0.075Nd0.075Ce0.85O2-delta Interlayers

Abstract

Solid oxide electrochemical cells (SOCs) are promising energy conversion and storage systems owing to their high efficiency and low environmental impact. To lower operating temperatures, the state-of-the-art SOCs with highly active cobaltite-based oxygen electrodes essentially require doped-ceria interlayers to avoid undesirable reactions with commercially available zirconia electrolytes. However, the inherent cation interdiffusion between ceria and zirconia materials at high temperatures (>1300 degrees C) has retarded the construction of highly dense and stoichiometric ceria/zirconia bilayers. This study reports the fabrication of a highly conductive, ultra-thin (250 nm), and defect-free Sm0.075Nd0.075Ce0.85O2-delta (SNDC) interlayer via readily processable gelatin-assisted deposition. The SOC with the gelatin-derived SNDC interlayer achieved exceptionally high electrochemical performances both in the fuel cell (approximate to 3.34 W cm(-2)) and electrolysis mode (approximate to 2.1 A cm(-2) at 1.3 V) at 750 degrees C-one of the best records for SOCs with similar configuration to date-along with excellent long-term durability (1500 h). Mechanistic analysis reveals that the ultra-thin and dense structure of the SNDC interlayer provides a faster route for oxygen-ion conduction and more active sites for both oxygen reduction and oxygen evolution reactions at the oxygen electrode/electrolyte interface. The findings suggest that the thin and dense gelatin-derived SNDC interlayer has great potential for use in high-performance reversible SOCs.