Multiphysics Modeling and Performance Optimization of CO 2 /H 2 O Co-Electrolysis in Solid Oxide Electrolysis Cells: Temperature, Voltage, and Flow Configuration Effects

This study developed a two-dimensional multiphysics-coupled model for co-electrolysis of CO 2 and H 2 O in solid oxide electrolysis cells (SOECs) using COMSOL Multiphysics, systematically investigating the influence mechanisms of key operating parameters including temperature, voltage, feed ratio, and flow configuration on co-electrolysis performance. The results demonstrate that increasing temperature significantly enhances CO 2 electrolysis, with the current density increasing over 12-fold when temperature rises from 923 K to 1423 K. However, the H 2 O electrolysis reaction slows beyond 1173 K due to kinetic limitations, leading to reduced H 2 selectivity. Higher voltages simultaneously accelerate all electrochemical reactions, with CO and H 2 production at 1.5 V increasing by 15-fold and 13-fold, respectively, compared to 0.8 V, while the water–gas shift reaction rate rises to 6.59 mol/m 3 ·s. Feed ratio experiments show that increasing CO 2 concentration boosts CO yield by 5.7 times but suppresses H 2 generation. Notably, counter-current operation optimizes reactant concentration distribution, increasing H 2 and CO production by 2.49% and 2.3%, respectively, compared to co-current mode, providing critical guidance for reactor design. This multiscale simulation reveals the complex coupling mechanisms in SOEC co-electrolysis, offering theoretical foundations for developing efficient carbon-neutral technologies.