NiFe-La0.3Sr0.7TiO3 Composites as Current Collectors for Solid Oxide Electrolysis Cells: Enhanced Microstructural Stability and Electrochemical Performance

초록

Particle coarsening and microstructural degradation of conventional NiFe current collectors limit solid oxide electrolysis cell (SOEC) performance during high-temperature operation. This work investigates NiFe-La0.3Sr0.7TiO3 (LST) composites as advanced current collectors with enhanced structural stability. LST ceramic phases (0-20 wt%) were incorporated into NiFe matrices via ball milling. X-ray diffraction confirmed successful composite formation without secondary phases. Microstructural analysis revealed that 5-10 wt% LST addition increased porosity while reducing particle size distribution, facilitating gas diffusion. Electrochemical impedance spectroscopy of symmetric cells demonstrated that NiFe-LST (5 wt%) and NiFe-LST (10 wt%) achieved the lowest area-specific resistance values across 650-800 degrees C under 50% H2O/H2 atmosphere. During operation over the tested duration at 750 degrees C showed NiFe-LST (5 wt%) maintained superior microstructural stability compared to pure NiFe, with reduced particle growth and area-specific resistance degradation trend. Single-cell SOEC incorporating NiFe-LST current collector achieved current densities of 1.6 A cm-2 (750 degrees C) at 1.3 V, demonstrating excellent performance under steam-rich conditions. The LST ceramic phase effectively suppresses metal particle coarsening through a pinning mechanism while maintaining electrical conductivity above 100 S cm-1. These results establish NiFe-LST composites as promising current collector materials for improving SOEC durability behavior and performance.

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