Optimizing cathode contact layer thickness for enhanced efficiency and durability in solid oxide fuel cell stacks

The introduction of a contact layer between the cathode and the interconnect effectively reduces their interfacial resistance and improves overall solid oxide fuel cell performance. In this study, LaCo_0.4Ni_0.6O₃ (LCN) was selected as the cathode contact material due to its excellent electrical conductivity, excellent chemical compatibility, and thermal expansion coefficient (TEC) well matched with adjacent cell components. A series of thicknesses of the LCN layer was systematically investigated to elucidate its impact on cell performance. Experimental results demonstrated a peak power output of 104.28 W at 750 °C with an optimal LCN thickness of 0.4 mm, accompanied by robust long-term stability. A 22-cell stack achieved a total power output of 1144.8 W at 750 °C, maintaining stable operation with an average efficiency decay of only 0.5 % over five thermal cycles. Excessive thickness hindered reactant gas diffusion, while inadequate thickness caused localized cathode overheating (“burning”), leading to premature cell failure. These findings underscore the necessity of optimizing LCN contact layer thickness to achieve a balance between electrical performance, gas transport efficiency, and thermal management in SOFC stacks.