Development of a Tubular Solid Oxide Cell for Co-Electrolysis of H2O and CO2 for Syngas Production

A tubular Ni-8YSZ/SSZ/GDC/SSC (Strontium-doped Samarium Cobaltite) cell was prepared for high temperature co-electrolysis of H2O and CO2. This cell enhanced a current density at 750oC by two-fold compared to a previous type of our cell. Measurements of voltage-current density (V-J) curves revealed that 0.55 A/cm2 was attained at 750oC and a thermoneutral voltage (1.33 V). The V-J curves were not influenced by change of H2/C (= 2-4) or flow-rate ratio (= 1-4) of positive electrode to negative one. In addition, V-J curve measurement at constant 80% utilization of H2O and CO2 clarified that 0.41 A/cm2 was achieved at the thermoneutral voltage and 750oC. It was observed by precise gas analyses that gas composition changed in proportion to J and utilization of H2O and CO2. Simultaneously, cross gas-leakages were detected from one electrode to the other.