Bi-doped borosilicate glass as sealant for sodium sulfur battery

Bi-doped borosilicate glasses as sealants for sodium sulfur battery are developed. The joining properties involving hermeticity, wetting behavior, bonding strength, thermal shock resistance and corrosion resistance have been systematically investigated. As found, the joints achieve good hermeticity by bulk joining. The wetting behavior and bonding strength are governed by the joining temperature and Bi2O3 content. The higher temperature and higher Bi2O3 content induce better wetting behavior due to the low viscosity. The thermal shock resistance of the alpha-alumina/glass/beta-alumina joint is dependent of the thermal expansion match between the glasses and alpha-, beta-alumina. No microcracks are found in the glasses containing 12–42 wt.% Bi2O3 after 200-times thermal shock. The glass/alumina joints show good anti-corrosion behavior against sulfur, especially containing 42 wt.% Bi2O3.

Research highlights
► Bi2O3 is doped to the borosilicate glasses considering its polarization.
► We found that TiO2 is an effective nucleating agent in the Bi2O3-doped borosilicate glasses. The thermal expansion coefficients of the glass-ceramics are close to that of the parent glass, which matched with those of the alpha- and beta-alumina.
► The joining properties involving hermeticity, wetting behavior, bonding strength, thermal shock resistance and corrosion resistance have been systematically investigated, indicating that the developed Bi2O3-doped borosilicate glasses are appropriate sealants for sodium sulfur battery.