Fine-tuning thermal expansion characteristics of solid oxide fuel cell cathode via composite cathode fabrication

Solid oxide fuel cells (SOFCs) offer promising prospects for sustainable electricity generation, attributed to high efficiency and fuel adaptability. However, their widespread application relies on three critical factors: performance, cost-effectiveness, and durability. Durability presents a significant hurdle; one key reason is the thermal expansion mismatch between cobalt-based cathodes and electrolytes, potentially leading to detachment at the cathode-electrolyte interface. In this study, we propose an approach to mitigate this challenge by fine-tuning the thermal expansion characteristics of the cathode. By tailoring lattice and chemical expansion, our composite cathode incorporates recognized materials like Ba0·5Sr0·5Co0·8Fe0·2O3-δ with Sm0.2Ce0·8O1.9 and the negative thermal expansion (NTE) material Y2W3O12. Through the design of composite materials, we achieve enhanced thermal cycling stability with only ∼20 % area-specific resistance (ASR) increases after 40 harsh thermal cycles between 300–600 °C compared to pure BSCF with over 100 % increment. This optimization process effectively reduces the thermal expansion coefficient while preserving BSCF's overall properties, offering a promising path for supporting SOFC durability and performance.