Effect of Elastic Network of Ceramic Fillers on Thermal Cycle Stability of a Solid Oxide Fuel Cell Stack

Glass-based seals for planar solid-oxide fuel-cell (SOFC) stacks are open to uncontrolled deformation and mechanical damages, limiting both sealing integrity and stack reliability, particularly in thermal cycle operations. If the glass-based seals work like an elastomer-based compressive seal, SOFC stacks may survive unprecedented numbers of thermal cycles. A novel composite sealing gasket is successfully developed to mimic the unique features of the elastomer-based compressive seal by controlling the composition and packing behavior of binary ceramic fillers. A single-cell SOFC stack undergoes more than 100 thermal cycles with little performance loss, during which the sealing integrity is lost/recovered repeatedly upon cooling and reheating, corresponding to unloading/loading of the elastomer-based compressive seal. The thermal-cycle responses of the SOFC stack are explained in sequence by the concurrent events of elastic deformation/recovery of ceramic filler network and corresponding redistribution of sealing glass.