Effect of seawater on the performance of flat-tube solid oxide cell for CO2/H2O co-electrolysis

Abstract

Solid oxide electrolysis cell (SOEC) for CO2/H2O co-electrolysis is an advanced technology that converts excessive power into synthesis gas. The products from CO2/H2O electrolysis can be used to synthesize liquid fuels, which are easy to store and transport. This work compared the electrolytic performances of syngas preparation in CO2/seawater and CO2/deionized water atmospheres using a flat-tube SOEC. The results showed that there was no significant difference in the instantaneous performance and the stability of the cells when electrolyzed in a CO2/seawater atmosphere and a CO2/deionized water atmosphere. The voltage degradation rate of the cell in the CO2/seawater atmosphere was about 5.38%/kh with an operating time of nearly 400 h and a current density of 300 mA/cm2; the degradation rate of the cell in CO2/deionized water atmosphere was about 7.37%/kh with an operating time of nearly 400 h and current density of 300 mA/cm2. The microstructure characterization results showed that the degradation of the electrolytic cells under the two atmospheres might be caused by the agglomeration and loss of Ni particles, and the volatile components from seawater would not diffuse to the fuel electrode near the electrolyte and affect the electrode reaction.