Polarization modeling for SOEC degradation during long-term operation

Solid oxide cells (SOCs) operate in both fuel cell (FC) and electrolysis cell (EC) modes. However, SOCs experience performance and microstructural degradation during long-term operation. In this study, a non-destructive method is developed to quantitatively analyze electrochemical and microstructural changes using polarization modeling. The model separates experimental electrochemical data into ohmic, activation, and concentration polarization components, enabling the identification of degradation mechanisms. The exchange current density ( i 0 ) and charge transfer coefficient (α) are employed as fitting parameters to evaluate triple-phase boundary (TPB) loss and reaction-mechanism changes. Based on 506-h long-term solid oxide electrolysis cell operation, the combination of distribution of relaxation time (DRT) analysis and polarization modeling reveals TPB loss at the fuel electrode due to a decrease in i 0 , f u e l and a change in the reaction mechanism indicated by an increase in α f u e l . It demonstrates that polarization modeling provides a quantitative and non-destructive tool for evaluating electrode degradation in SOCs. • Polarization modeling enables non-destructive analysis of SOC degradation. • Electrochemical fitting extracted i 0 and α as key kinetic parameters. • Observed TPB loss and reaction-mechanism change during 506 h SOEC operation. • Linked performance degradation to TPB loss in long-term operation.