Mechanical Investigation of Various Stack Designs for Solid Oxide Cells

Abstract

Stress development in metallic interconnects during operational cycles of solid oxide cells (SOCs) could create permanent plastic deformations, which can cause contact losses in the interface between the interconnect and cells. The magnitude of these stresses and their distribution within the SOC stack are dependent on the overall design of the stack and its operational parameters/conditions. In this study, analysis of stress generation in metallic interconnects due to temperature and stack assembly loadings for different types of generic SOC stack designs operated under the same operational cycles is performed. The analysis includes stack design concepts with and without contact layers having cross-shaped and/or corrugated metallic interconnect. To consider the effect of thermal gradient over the surface of the stacks (due to electro-chemical reaction), stacks with two types of temperature profiles are studied. The analysis is performed numerically using finite element modeling of a standard repeating unit of SOC stack. Special focus is given to stresses that can cause possible delamination of the interconnect from the cell that subsequently leads to loss of electrical contact. Comparison of stress for different types of stack design concepts are presented. An effective way to minimize stresses in the interconnect is found to be through designing the micro-architectures of the interconnect and us eof contact layers materials. Key words: Solid oxide fuel cells, Metalic interconnect, Creep, finite element modeling