Equivalent circuit models for predicting electrical and gas output characteristics of CO2 electrolysis cells

Abstract

This paper proposes an equivalent circuit model that simulates the current–voltage characteristics, faradaic efficiency, and gas flow rates output from the cathode and anode channels for a CO₂ to CO producing electrolysis cell. Considering that the CO₂ flow rate introduced into the cathode channel limits the CO partial current density, this model can predict the output of CO, H₂, and CO₂ flow rates from the cathode channel. Furthermore, the model also enables the prediction of CO₂ flow rate output from the anode channel by assuming that both the carbonate and hydrogen carbonate ions transfer from the cathode side to the anode side. These simulations are validated using experimental results of the dependence of the electrical and gas output characteristics on the CO₂ flow rate. Our results show that the proposed model based on electrochemical kinetics and ion transfer phenomena can contribute to efficient power supply controllers and auxiliary equipment designs for CO₂ electrolysis systems.