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The differences in material properties of different components of solid oxide fuel cells cause high stresses during sintering and operation, and functional gradient material electrodes are expected to alleviate this problem. In this study, electrodes with three different material compositions are compared with electrodes using conventional materials, and the residual and thermal stresses are calculated by applying functional gradient materials to single-sided and double-sided electrodes, respectively, and the results are analyzed with the optimization goal of minimizing the stresses to find the optimal functional gradient material composition distribution. The study shows that the functional gradient material electrode can significantly reduce the interfacial stress and alleviate the local stress concentration. When using functional gradient materials for one side of the electrode, a specific material component distribution can reduce the residual stress and thermal stress on the other side, but the stresses may increase on the local side of the electrode. The interfacial stress between layers can be reduced to a maximum of 0.1 MPa when a functional gradient material with a quadratic linear distribution of components is used for both sides of the electrodes. This study has implications for the fabrication of functional gradient materials for SOFC electrodes.

In this paper, an anode and cathode material scheme with a continuous gradient variation of components is presented. The residual stress distribution of each part of the electrode model under the new material structure is derived by calculating the residual stress during the sintering process, and the optimal material component distribution curve is derived from the analysis of the results. A multi-physics 3D model covering heat transfer, mass transfer, flow, electrochemistry and solid mechanics is developed with the help of the finite element analysis software COMSOL Multiphysics 5.5. Simulation experiments are conducted to verify the effectiveness of the method for mitigating thermal stress mismatch, reducing residual stresses and increasing the working life of the fuel cell. The results show that the use of functional gradient materials for one side electrode significantly reduces the residual stresses generated in the other side electrode during sintering, and the effect of the sinusoidal distribution curve is the most significant. The stress concentration at the electrode-electrolyte interface can be improved when both side electrodes are used with functional gradient materials at the same time, and the sinusoidal and primary linear distributions are more effective.

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Solid oxide fuel cells convert chemical energy into electrical energy directly through electrochemical methods, and the residual stress in the preparation process endangers its reliability. In this study, the cosine function is used to approximate the non-flat cathode-electrolyte interface, and the effects of different wavelengths on residual stress and failure probability are clarified. The results show that the electrolyte is under compressive stress and the cathode is subjected to tensile stress at the non-flat interface. The compressive stress of electrolyte is the largest at the trough, while the tensile stress of cathode is the largest at the peak. The smaller the wavelength, the stronger the stress fluctuation. In the process of anode reduction, the failure probability of cathode is the largest. The longer the wavelength, the smaller the residual stress and the smaller the failure probability.