A computational modeling approach for prediction of polarization losses inside porous micro-structured cathode used for CO2 reduction in SOEC

Abstract

Multi-component electrochemical models were developed and simulated to predict various losses associated with solid oxide electrolysis cells (SOEC) for CO2 reduction. Electrochemical reduction reactions were modeled and simulated for two feed compositions: CO2/H2 and CO2/CO. The concentration overpotentials were calculated using Fick’s Model and Dusty Gas Model, and subsequently, current-voltage characteristics of SOEC were estimated and compared. In case of CO2/H2 feed gas mixture, the predicted applied voltage by Dusty Gas Model (DGM) and Fick’s Model are 2.37 and 2.03 V respectively at current density of 0.8 A/cm2. While in CO2/CO atmosphere, both the models estimated the same value of applied potential at 0.05 A/cm2. In CO2/H2 mixture, a deviated prediction of applied voltage by two models at the same current density might be due to the equimolar counter diffusion assumption, made by Fick’s Model, which is invalid for the large difference in molar mass of constituent gases CO2 (44 g/mol) and H2 (2 g/mol). Furthermore, models were simulated to assess the role of temperature and molar compositions feed gas on the current-voltage characteristics of SOEC.