Heating‑rate‑controlled interface engineering for improved cathodic performance in solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are attracting attention as promising power devices for a carbon-neutral society due to their high energy conversion efficiency and fuel flexibility. The performance and durability of SOFCs are strongly influenced by the microstructure of the electrode layer and its interfacial properties with the electrolyte, both of which are highly affected by the electrode sintering process. In this study, single cells employing an SSC cathode were fabricated under three different heating rates during sintering: 3, 6, and 10 °C·min⁻¹. The effect of heating rate on microstructural evolution, interfacial diffusion between the electrode and electrolyte, and electrochemical performance was systematically investigated. Scanning electron microscopy (SEM) revealed that the cell sintered at 6 °C·min⁻¹ exhibited a uniform particle size distribution and optimal porosity, enabling efficient ionic transport across the electrode–electrolyte interface. Electrochemical impedance spectroscopy (EIS) confirmed that this condition minimized interfacial resistance, resulting in the highest maximum power density of 1.48 W·cm-2 at 800 °C. These enhancements are attributed to the suppression of excessive grain growth and pore loss while optimizing ionic conduction pathways. The findings demonstrate that precise control of heating rate during electrode sintering could significantly enhance SOFC efficiency, providing a crucial basis for process optimization in large-area cell manufacturing and advancing the commercial viability of the technology.