Seal Glass for Solid Oxide Fuel Cells

Abstract

Barium calcium aluminum boro-silicate glass (BCABS) is used as a sealant for Solid Oxide Fuel Cells (SOFCs) to protect against air and hydrogen gas leaking at 800 C. One major problem is the chemical reaction of this glass with barium oxide and other materials in the composition such as BaY Co -Fe (BYCF) and Ba-Sr-Co-Fe (cathode) used in the fuel cell components, leading to the formation and spreading of barium aluminosilicate glass on the cathode surface in the fuel cell. This investigation indicated that adding 0.4 mol% ZrO 2 to BCABS prevents the formation of barium aluminosilicate glass. Generally, the sealing glass of fuel cells must show high resistivity for no disturbance to electricity from the fuel cell system when generating the electron. The 0.4 mol% ZrO 2 to BCABS is generated with resistivity of 4 MΩ that is useful for SOFCs technology. The thermal expansion coefficient (TEC) in SOFCs is the major condition for producing the cell layers. The thermal expansion coefficient of SOFCs based on each layer (cathode, electrolyte, anode, interconnect and sealant) should be closed to prevent broken cells. The thermal expansion coefficient is 12.40 Â 10 À6 / o C matched with the TEC of the GDC 10 electrolyte. Therefore, BCABS glass with 0.4 mol%ZrO 2 generated a novel composite for SOFCs.

Review on silicate and borosilicate‐based glass sealants and their interaction with components of solid oxide fuel cell

“…The BaO‐Al 2 O 3 ‐B 2 O 3 glass sealant could be a good choice in a high‐temperature T‐SOFC, particularly, Sm‐doped ceria electrolyte 158 . Not only the addition of 0.4 mol% ZrO 2 in the glass sealant avoids the formation of the BAS phase, but also CTE of this glass sealant is met with the gadolinium doped ceria 159 . The mechanical and chemical stability of the interconnect (steel) and BaO‐based glass sealant (27BaO·18MgO·7.5B 2 O 3 ·47.5SiO 2 ) joints has also been studied as a function of the crystallization degree, the resistance versus thermal cycling and the influence of a reducing atmosphere.…”

“…158 Not only the addition of 0.4 mol% ZrO 2 in the glass sealant avoids the formation of the BAS phase, but also CTE of this glass sealant is met with the gadolinium doped ceria. 159 The mechanical and chemical stability of the interconnect (steel) and BaO-based glass sealant (27BaOÁ18MgOÁ7.5B 2 O 3 Á47.5SiO 2 ) joints has also been studied as a function of the crystallization degree, the resistance versus thermal cycling and the influence of a reducing atmosphere. The developed and tested materials could be promising for long-term stable SOFC and Solid oxide electrolyzer cells (SOEC) applications.…”

Investigation of the Glass-Ceramic Sealants in SOFC Stacks

“…A robust and durable seal is one of the keys for the application and commercialization of planar solid oxide fuel cell (SOFC) stacks. Due to the complicated and harsh working conditions, such as high temperature (700~900 ℃) and strong reducing atmosphere, reliable sealing is still a challenge for stack application (1)(2)(3). Rigid seals based on glass and glass-ceramic materials are widely investigated and used due to their high stability, simple application, low cost, and amenability to mass production (4).…”