A zero-dimensional simulation model of solid oxide cells considering degradation

Solid oxide cells (SOCs), including solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), are promising high-efficiency energy conversion devices. However, their long-term durability is limited by degradation under high-temperature operation. In addition, existing models often lack a consistent representation of coupled degradation mechanisms. In this study, a zero-dimensional (0D) degradation model is developed to predict SOC performance decay and support lifetime assessment. The model integrates chromium (Cr) poisoning in the oxygen electrode, fuel electrode microstructural degradation, and interconnect corrosion within a unified framework applicable to both SOFC and SOEC operation. A molecular-projected-area-based surface coverage formulation is introduced for the first time, enabling a physically consistent representation of Cr poisoning across different oxygen electrode materials. Fuel electrode degradation is modeled in a mode-dependent manner, with Ni coarsening dominating under SOFC operation and Ni migration under SOEC operation. Simulation results indicate that oxygen electrode degradation governs performance decay in SOFC, whereas Ni migration dominates in SOEC. The model shows good agreement with experimental and published values, and sensitivity analysis identifies key parameters influencing degradation. The proposed framework provides a computationally efficient tool for predicting SOC degradation and supports system-level performance analysis and optimization.