Modeling CO2 electrolysis in solid oxide electrolysis cell

A modified Butler–Volmer equation for the reduction of CO₂ by considering multi-step single-electron transfer reactions is presented. Exchange current density formulations free from arbitrary order dependency on the partial pressures of reactants and products are proposed for Ni and Pt surfaces. Button cell simulations are performed for Ni-YSZ/YSZ/LSM, Pt-YSZ/YSZ/Pt, and Pt/YSZ/Pt systems using two different electrochemical models, and simulation results are compared against experimental observations. The first electrochemical model considers charge transfer reactions occurring at the interface between the electrode and dense electrolyte, and the second model considers the charge transfer reactions occurring throughout the thickness of the cermet electrode. Single-channel simulations are further performed to asses the O₂ production capacity of CO₂ electrolysis system.