Progress in Glass-Ceramic Seal for Solid Oxide Fuel Cell Technology

Abstract

Solid oxide fuel cells (SOFCs) have emerged as promising energy conversion devices nowadays. SOFC consists of several components such as cathode, anode, electrolyte, interconnects, and sealing materials. In planar SOFC stack construction, the sealant and interconnection functions play an important role. Glass and ceramics are quite popularly used as SOFC sealing materials to achieve several functions including preventing leakage of fuel and oxidants in the stack and electrically isolating cells in the stack. In this review, material preparation, material composition, ceramic properties especially thermal properties are compared from various systems that have been developed previously. The main challenges and complexities in the functional part of SOFC sealants include: (i) chemical incompatibility and instability in the oxidizing and reducing environment by adjusting the value of the thermal expansion coefficient (CTE) with the interconnecting material during SOFC operation, and (ii) insulation of oxidizing fuels and gases by matching CTE anode and cathode. Also, the sealant glass transition determines the maximum permissible working temperature of the SOFC. The choice of method and analysis will provide data on various ceramic attributes. The search for thermal attributes consisting of Glass transition (Tg), Deformation temp (Td), Crystallization temp (Tx), Melting pt (Tm) became a focus on SOFC sealant development.

A critical review of key materials and issues in solid oxide cells

“…Glass-ceramics (e.g., BaO-Al 2 O 3 -SiO 2 and its modification) were then developed that typically improves the strength and allows for property control through adjusting the amount and species of the constituting phase(s). [82] The important characteristics of glass-ceramic-based sealants are the recrystallization properties and volatility of the boron components, which is critically related to the thermal cycle capability and structural stability of the sealant materials. [83,84] The most common failure of glass-ceramic-based sealants is the crack in the bulk sealant or at the sealing interfaces during thermal cycling, and the strength of the sealing interfaces may deteriorate due to direct or indirect deleterious chemical interactions.…”

Synthesis, Structural Properties, and Resistance to High-Temperature Degradation of Perovskite Ceramics Based on Lanthanum–Strontium Ferrite

“…One of the promising directions in the transition from traditional energy sources to alternative ones are methods for generating energy from hydrogen using fuel cells based on proton-or oxygen-conducting membranes or solid fuel oxide cells (SOFCs) [1][2][3][4]. Moreover, when it comes to using high-temperature SOFC elements based on oxygen-containing membranes or ceramics, the operating temperature at which acceptable conductivity values are achieved is more than 700 • C, which results in high heat release, alongside a long start-up time [5,6]. Moreover, an essential factor influencing the use of such structures in the fuel cycle is the preservation of their stability and sustainability during operation for a long time (40,000-50,000 h) [7][8][9].…”

Leak test for solid oxide fuel cells and solid oxide electrolysis cells

“…Otherwise, leaks will result in direct mixing of fuel and oxidants at elevated temperatures, greatly reducing the cell/stack electrochemical performance and potentially leading to total cell failure or fire in extreme cases. To separate fuels such as hydrogen from oxidants such as air, these seals are typically composed of borosilicate glasses (Gunawan et al, 2021;Singh and Walia, 2021) which are fired at elevated temperatures according to a specified temperature profile based on the thermal and physical properties of each individual sealing glass. Other sealing technologies such as brazing and compressive mica seals have also been investigated (Weil et al, 2003;Simner and Stevenson, 2001;Chou et al, 2002;Fergus, 2005;Lessing, 2007).…”