An Experimental Study of Solid Oxide Fuel Cell With Optimized Cathode Structures

Solid oxide fuel cells (SOFCs) are highly efficient energy conversion devices, and planar anode‐supported single cells represent a major development direction. However, cathode interface delamination or even detachment under thermal cycling conditions severely limits their long‐term durability. To address this issue, this study proposes a composition‐gradient cathode design to alleviate thermal expansion mismatch and suppress interfacial delamination, thereby significantly enhancing the thermal cycling stability and service lifetime of large‐size SOFCs. This gradient structure comprises a transition layer (LSC 0.7 GDC 0.3 ) and a composite cathode (LSC 0.9 GDC 0.1 ), achieving a smooth transition in the coefficient of thermal expansion (CTE) between the barrier layer and the cathode layer. Experimental results show that the introduction of the transition layer and composite cathode reduces the CTE difference between the cathode and the barrier layer from 53.93% to 21.76%, effectively relieving thermal stress concentration. After 50 thermal cycles at 30 A, the voltage degradation rate of the gradient‐structured cell D is only 14%, and its thermal cycle life reaches 77 cycles, approximately 15 times that of the traditional‐structured cell A. Compared with cell A, the gradient structure significantly improves the structural integrity and damage resistance of the cathode side, effectively inhibiting element interdiffusion and the segregation/aggregation of Sr particles. This study provides a new design concept for enhancing the thermal cycling stability and long‐term reliability of SOFC single cells, demonstrating high engineering feasibility and commercial application potential.