Structure optimization of hydrogen electrode for enhancing solid oxide electrolysis cell performance and strength: A model-based quantitative analysis

Abstract

A comprehensive multi-channel three-dimensional (3D) multiphysics model based on the finite element method (FEM) was developed to systematically investigate the effect of electrode structure on the performance of solid oxide electrolysis cell (SOEC), This model integrates detailed descriptions of electrochemical and chemical reaction kinetics, heat and mass transfer phenomena, as well as electron and ion charge transport mechanisms, enabling a holistic simulation of SOEC operational behavior. A thorough examination and validation were conducted on SOEC with different hydrogen electrode structural parameters. It was revealed that the optimal structures of both the functional layer and the support layer within the hydrogen electrode exhibited certain conditional variations, yet the overall trend is generally consistent. Specifically, under the operating conditions of 1023 K, an applied voltage of 1.29 V, and a fuel gas inlet flow rate of 24 L/h, the optimal parameters for the functional layer were determined as follows: a porosity of approximately 0.2–0.25, a thickness of about 15 μm–20 μm, a Ni solid-phase volume fraction of roughly 0.45, and a Ni particle diameter of around 0.8 μm. For the support layer, the optimal porosity was approximately 0.45, and the optimal thickness was about 200 μm. With the aforementioned optimized structural parameters, the SOEC achieved a high current density of 1.33 A/cm² while maintaining a low thermal stress of only 111 MPa. This work not only deepens the researchers’ comprehension of the correlation between electrode structure and SOEC performance but also provides valuable theoretical guidance for the design and optimization of porous electrode design.