Interface Fracture Energy of Contact Layers in a Solid Oxide Cell Stack

A critical factor for improving the long-term stability/reliability of solid oxide cell stacks is ensuring good adhesion between the stack components. Specifically, ensuring strong adherence between the oxygen electrode and the interconnect is challenging. This work compares the suitability of several materials as contact layers between a La0.6Sr0.4CoO3−δ-Ce0.8Gd0.2O2 composite oxygen electrode and Mn1.5Co1.5O4- or Co-coated metallic interconnects. The contact materials were screened on the basis of measurements of the interface fracture energy using four-point bending of sandwiched samples. The highest fracture energies were measured using a CuMn metallic, spinel-forming foam as the contact layer. The fracture energy of the interface between a Mn1.5Co1.5O4-coated interconnect and the contact layer is ∼8 times higher using the CuMn foam compared with using conventional (La0.8Sr0.2)0.98MnO3-σ, La0.6Sr0.4CoO3−δ, (La0.8Sr0.2)0.98MnO3-σ + La0.6Sr0.4CoO3−δ or LaNi0.6Fe0.4O3 as the contact material. The interface bonding and fracture mechanisms are discussed on the basis of scanning electron microscopy investigations.