Modeling and Simulation the Influence of Solid Carbon Formation on SOFC Performance and Degradation

An elementary kinetic model is established to represent the coupled behavior of (electro)-chemistry, transport and degradation processes in the porous Ni/YSZ anode of solid oxide fuel cells (SOFC). The model is applied to support the development and evaluation of solid carbon formation mechanisms at Ni/YSZ anodes. The simulations of cells operated on partially reformed hydrocarbons show that performance and degradation are influenced significantly by the operation temperature and applied potential. Specifically, at OCV and high temperature (1023 K), a surface carbon layer is formed which covers Ni surface and Ni three-phase boundary, blocking heterogeneous and charge-transfer reactions. However, at lower temperature (923 K) carbon growth mainly proceeds inside of anode porous phase leading to significant diffusion polarization. Literature experimental data is used for validation of the model.