Deformation of the interconnect in a solid oxide fuel cell (SOFC) stack affects the internal thermal stresses of the cell at high temperatures. In this study, the effect of the interconnect deformation on the cell temperature and thermal stress at different operating voltages was simulated based on the thermal-chemical-electrical-mechanical multiphysics coupling theory. The results show that when the operating voltage of the cell is above 0.85 V, the interconnect mainly generates a compressive strain. When the operating voltage is below 0.85 V, the interconnect produces tensile strain, which increases with decreasing voltage. Interconnect deformation significantly increases the thermal stress of the cells within the stack, but effectively improves the uniform distribution of thermal stress. The coupling effect of interconnect deformation on cell thermal stress within the stack varies at different operating voltages.

High-temperature Solid Oxide Fuel Cells (SOFCs) typically operate under conditions involving repeated thermal cycling. The transient temperature rise during thermal cycling directly affects the stress distribution within the SOFC structure, particularly inducing non-uniform thermal stresses in the electrolyte layer. This can readily lead to cracking and fracture of the SOFCs, potentially degrading overall system performance. Therefore, investigating the effects of cyclic thermal loading on structural stress distribution is essential for optimizing SOFC design. To this end, this study developed a coupled thermo-chemo-mechanical finite element analysis for a planar tubular SOFC. The model is employed to analyze the influence of thermal impact on the thermal stress distribution within the cell structure under multiple thermal cycling conditions. The results indicate that both the transient temperature rise during SOFC operation and the number of thermal cycles significantly affect the peak stress in the electrolyte layer and the overall performance stability of the cell. By optimizing the geometric configuration of the flat-tubular and the transient temperature rise during thermal cycling, the thermal stress field distribution in the electrolyte can be improved. These findings provide theoretical guidance for optimizing the design and engineering application of high-temperature SOFCs.