SiO2–B2O3-BaO-WO3 glasses with varying Al2O3 content as a sealing material for reversible solid oxide fuel cells

Abstract Silicate glasses based on SiO2–B2O3-BaO-WO3 (SBBW) are synthesized with varying added Al2O3 content, and their thermal and structural properties are examined as a sealing material for reversible solid oxide fuel cells (RSOCs). When up to 17.5 mol%, Al2O3 is added, glass stability is improved at the expense of viscosity at sealing temperature. The glass transition temperature (Tg), coefficient of thermal expansion (CTE) and flow at sealing temperature are investigated while varying Al2O3 content, to find the proper composition for RSOC sealing. The structural changes in the glasses resulting from the Al2O3 are inspected using Raman spectroscopy and an X-ray diffractometer. The adhesion characteristics of the glasses are examined by applying the glasses between NiO-yittria stabilized zirconia (NiO-YSZ) and Crofer22APU. A RSOC stack with 15 cells is prepared with glass containing 10 mol% of Al2O3 as a sealing material, and the practical feasibility of the glass is successfully demonstrated. The open circuit voltage is monitored while cycling the RSOC stack between water electrolysis mode and fuel cell mode.