Functionally Gradient Seals for Solid Oxide Fuel Cells
World energy markets have entered a period of inexpensive natural gas and fossil fuels, as hydraulic fracturing technologies offer energy independence to the U.S. This likely will extend the continued and increased fossil fuels use for the next decades. To create the greatest economic advantage from these domestic natural gas, oil and coal reserves, new energy systems are required that utilize these resources efficiently at the emerging micro-grid and conventional grid scale. Further, the cost of these systems must be comparable to current energy systems. SOFC’s are highly efficient, quiet, and environmentally clean devices for generating electricity and heat from natural gas, coal, biomass, and other fuels. They are one of the most promising technologies to meet the Nation’s future energy needs. For SOFC to realize their potential and achieve widespread commercial adoption these complex electrochemical systems must be made robust to harsh operating conditions and periodic thermal cycling. Component technologies (fuel cell membranes, interconnects, and balance of plant components) have been developed to meet the performance requirements, but sealing has remained a persistent issue facing SOFC developers. To achieve the required U.S. DOE long-term performance degradation target (< 0.2 percent per 1000 hours over an operating lifetime of 40,000 hours) and cost targets (stack cost of $225/kW), reliable cost-effective seals are critical. Nexceris’ GasLok sealing technology was designed specifically to address failure mechanisms that cause seal degradation. In the Phase I project, Nexceris successfully demonstrated the technical feasibility of a TCE-graded sealing approach for electrolyte and anode-supported cell platforms. To enable adherence of the seal coatings, metal interconnects were pre-treated with Nexceris’ AlumiLok process to roughen the metal surface and achieve coating adhesion that otherwise would not be possible. A 90-percent improvement in sealing performance was demonstrated versus Nexceris’ incumbent sealing technology and enhanced seal durability and thermal cycling robustness were demonstrated in offline and single-cell electrochemical tests. In this Phase II project, Nexceris focused on strengthening the value proposition of the GasLok sealing technology. New testing capabilities were designed and implemented to enable testing and validation of new seal and coating formulations. In the first year of Phase II, several manufacturing process improvements were developed and qualified to reduce cost of the seal technology and make processing more amenable to high-volume production. This enabled a clear roadmap for scaling the technology to high-volume production and achieving U.S. DOE cost targets. In the second year of Phase II, Nexceris focused on stack-level demonstrations to position GasLok for future implementation and commercialization. Three different seal formats were evaluated, including tape casting of graded seal gaskets, screen-printing of graded seal coatings, and aerosol spray deposition (ASD) of graded seal coatings. The ASD approach was found to be the most promising from both performance and cost perspectives.
- Research Organization:
- NexTech Materials, Ltd.
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0018534
- OSTI ID:
- 1877188
- Type / Phase:
- SBIR (Phase II)
- Report Number(s):
- DOE-NEX-18534-2
- Country of Publication:
- United States
- Language:
- English
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