Evaluation of Electrolytic Characteristics with a Single Cell Developed as SOFC

Abstract

In recent years, it is concerned that a power supply and demand balance of power grid become unstable because of large introduction of variable renewable energy such as solar photovoltaic power generation. The reversible solid oxide cell (rSOC) can operate both SOFC and SOEC modes reversibly. Therefore, the rSOC can be used as a flexibility device for the power supply and demand adjustment by operating reversibly in response to power grid balance.Furthermore, CO2 electrolysis and co-electrolysis, which can generate synthesis gases such as H2 and CO, which are raw gases for methane or liquid fuels, from CO2 and H2O by adding an electric power, are promising carbon recycling technologies.In this study, the electrolytic characteristics were evaluated with a single cell developed as SOFC. It was confirmed in CO2 electrolysis test that CO2 can be directly electrolyzed to CO with about 100% current efficiency. In addition, the electrolysis voltages were clarified under various gas conditions in co-electrolysis and the cell performance factors were analyzed by our original method. In this method, the cell performance factors can be described by the internal resistance loss (IR loss, measured value), the fuel electrode overvoltage, the oxygen electrode overvoltage, and the Nernst loss (calculate value). As a result of this analysis in co-electrolysis mode before and after all tests, it was shown that the increase in IR loss was the main factor of the decrease in cell performance.