Sensitivity Analysis of One-Dimensional Multiphysics Simulation of CO2 Electrolysis Cell

Electrochemical (EC) carbon dioxide (CO2) reduction, where CO2 is converted to value-added products such as fuel precursors, plays a key role in helping the world's energy system reach net-zero carbon emissions. Simulations of EC cells provide valuable insight into their operation since detailed experimental results on short length and time scales are difficult to obtain. In this work, we construct a 1D simulation of a membrane-electrode-assembly EC cell for CO2 reduction, using a porous silver gas diffusion cathode. We run the simulation under different electrolyte conditions, showing how the cell performance is affected. We then perform a sensitivity analysis of all input parameters to the simulation, which has not been presented before in the literature. We show that the CO partial current density (i(CO)) is significantly affected by each input parameter of the simulation. i(CO) is most sensitive to EC kinetic parameters (i(0)/alpha) of all EC reactions, with a 1% change in alpha resulting in up to 6% change in i(CO). Since there is uncertainty associated with the value of each input parameter, this indicates that infidelity between experiment and simulation is likely, and thus, caution should be practiced when comparing experimental results to simulation results. Further, we show that the large range of conditions simulated in literature helps to explain the large variance in reported values of i(0) and alpha. The results of this paper demonstrate the potential of sensitivity analysis methods to quickly optimize aspects of cell performance (CO2 utilization, Faradaic efficiency, etc.).