Modeling and Investigation of Water Electrolysis in a Solid Oxide Electrolysis Cell with Composite Electrode

A two-dimensional mathematical model describing the process of hydrogen production in a solid oxide electrolysis cell (SOEC) with composite electrode is established. The Butler-Volmer equation, extended Fick’s model and Brinkman equation are adopted to describe the electrochemical reaction, multi-component mass transport, momentum and mass conservation in the cell. Meanwhile, The Bruggeman relation and percolation model are employed to maintain the material and structural properties of composite electrode. Based on this model, the reliable evaluation of the electrolysis performance of the SOEC is realized. The effects of the volume fraction and the particle radius of the electrolyte/electrode phase are studied. The results show that when the ratio of electrode volume fraction to electrolyte volume fraction decreases, the external voltage and overpotential is reduced and the electrochemical reaction area is obviously expanded. In addition, the excellent electrolysis performance is obtained when the ratio of electrolyte particle radius to electrode particle radius is close to 1 and the particle radii are 5 µm. This study can provide the guidance for the design and optimization of composite electrode in SOEC for hydrogen production.