Materials for Solid Oxide Electrolysis Cells

High conversion efficiency of solid oxide electrolysis cells (SOEC) to electrolyze steam into hydrogen, and co-electrolyze steam-carbon dioxide mixture into syngas (i.e. synthesis gas composed of hydrogen and CO) provides the means to store electricity from renewable sources in chemical form. Performance stability of SOEC is critical in achieving a commercially viable system. While the materials that are used for solid oxide fuel cells (SOFC) are applicable to high temperature solid oxide electrolysis cells (SOEC), there are degradation mechanisms that are unique to SOEC mode of operation. Significant reduction in degradation rate has been achieved by the use of a new set of electrode materials and protective coatings on interconnects. The stability improvement however came at the expense of initial stack performance. The use of higher conductivity current distribution layer restored the high performance while maintaining the stability gain. An overview of materials evaluation work is presented.