Sealing Technologies for Solid Oxide Fuel Cells

Sealing technologies play a pivotal role in ensuring the performance, longevity and safety of solid oxide fuel cells (SOFCs). Effective seals must maintain gas tightness between fuel and oxidant streams at high temperatures (600–900 °C), accommodate differential thermal expansion of ceramics and metals, and resist chemical degradation over thousands of hours of operation. Common approaches include glass and glass-ceramic composites, compressive mica and vermiculite sheets, and hybrid polymer-inorganic systems. Glass-based sealants offer adjustable softening behaviour and the possibility of in situ crystallisation to match component expansion, while compressive seals provide mechanical compliance during thermal cycling. Advanced interconnect materials and surface treatments are often paired with tailored sealants to suppress interfacial reactions and minimise electrical resistance. Recent trends emphasise low-temperature processing, doping strategies to reinforce thermo-mechanical stability, and the integration of scalable manufacturing techniques such as paste deposition and robotic dispensing. The global drive for decarbonised energy generation underscores the importance of robust sealing solutions to support large-scale SOFC deployment in stationary and mobile power applications.

Research from Nature Portfolio

Recent studies have demonstrated that the incorporation of niobium oxide into borosilicate seal glasses markedly improves the thermo-mechanical stability of the glass/metal interface. By introducing around 4 mol% Nb₂O₅, the modified sealant maintained intimate bonding with ferritic steel interconnects over extended thermal cycling and prolonged ageing at 750 °C. Finite-element analysis combined with experimental evaluation revealed reduced interfacial stress and energy concentrations, leading to intact joints after 50 cycles and 1 000 h of operation. These findings establish a design pathway for doped glass systems that resist crack initiation and accommodate repeated temperature swings.

Sealing Technologies for Solid Oxide Fuel Cells publication trend

The graph below shows the total number of articles in sealing technologies for solid oxide fuel cells across all publications each year (not limited to Nature Index journals).

Technical terms

Sealant: Material that provides a gas-tight, electrically insulating barrier between SOFC components under high temperatures.

Glass-ceramic: Composite sealant combining amorphous glass and crystalline phases to achieve tailored viscosity and thermal expansion.

Coefficient of thermal expansion (CTE): Parameter describing dimensional change per degree temperature change, critical for matching sealant and substrate.

Interconnect: Metallic or ceramic element that electrically links adjacent SOFC cells and facilitates current collection.

Thermal cycling: Repeated heating and cooling of components, which tests seal durability under operational temperature swings.

References

1. Effect of Nb2O5 doping on improving the thermo-mechanical stability of sealing interfaces for solid oxide fuel cells. Scientific Reports (2017).
2. Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell. Molecules (2023).
3. Microscopic Analysis of the Wetting Morphology and Interfacial Bonding Mechanism of Preoxidised Kovar Alloys with Borosilicate Glass. Materials (2023).
4. Thermo-Mechanical Stability and Gas-Tightness of Glass-Ceramics Joints for SOFC in the System MgO-BaO/SrO-B2O3-SiO2. Frontiers in Materials (2020).