Investigation of Solid Oxide Electrolysis Cell Electrodes for Methane Synthesis

Methane-synthesis solid oxide electrolysis cell (MS-SOEC) technology has potential to provide efficient renewable energy storage systems. However, there are few studies focusing on MS-SOEC electrode materials. In this study, several materials were tested experimentally. As anode materials, La0.6Sr0.4MnO3-delta (LSM), La0.6Sr0.4CO0.2Fe0.8O3-delta-Ce0.8Sm0.2O1.9 composite (LSCF-SDC) and platinum were compared. The cell with LSCF-SDC exhibited lower overpotentials and higher stability than LSM. Platinum showed even better performance than LSCF-SDC. Ni-SDC was used for the cathode, and the cathode outlet gas compositions were analyzed for several operation temperatures and current densities. It was found that catalytic activity for methanation was enhanced under polarized conditions. Effects of ruthenium addition to the cathode were also examined. Impedance analysis combined with gas composition measurements revealed high electrochemical activity of ruthenium, while methane production was suppressed possibly due to methane reforming reactions promoted by ruthenium.