Multiphysics-Driven Structural Optimization of Flat-Tube Solid Oxide Electrolysis Cells to Enhance Hydrogen Production Efficiency and Thermal Stress Resistance

The solid oxide electrolysis cell (SOEC) has potential application value in water electrolysis for hydrogen production. Here, we propose an integrated multi-scale optimization framework for the SOEC, addressing critical challenges in microstructure–property correlation and thermo-mechanical reliability. By establishing quantitative relationships between fuel support layer thickness, air electrode rib coverage, and Ni-YSZ volume ratio, we reveal their nonlinear coupling effects on the hydrogen production rate and thermal stress. The results show that when the fuel support layer thickness increases, the maximum principal stress of the fuel electrode decreases, and the hydrogen production rate and diffusion flux first increase and then decrease. The performance is optimal when the fuel support layer thickness is 5.4 mm. As the rib area decreases, the hydrogen production rate and thermal stress gradually decrease, but the oxygen concentration distribution becomes more uniform when the rib area portion is 42%. When the Ni volume fraction increases, the hydrogen production rate and the maximum principal stress gradually increase, but the uniformity of H2O flow decreases. When the Ni volume fraction is lower than 50%, the uniformity of H2O flow drops to 20%. As the volume fraction of nickel (Ni) increases, the fuel utilization gradually increases. When the volume fraction of Ni is between 50% and 60%, the fuel utilization reaches the range of 60–80%. This study indicates that the fuel support layer thickness, rib area, and Ni-YSZ ratio have different effects on the overall performance of the SOEC, providing guidance for the optimization of the flat-tube SOEC structure.