Integrated 3D modeling unravels the measures to mitigate nickel migration in solid oxide fuel/electrolysis cells

Numerical modeling plays an important role in understanding the multi-physics coupling in solid oxide fuel/electrolysis cells (SOFCs/SOECs) operated at elevated temperatures. During long-term operation of SOFCs and SOECs, cell durability is limited by nickel (Ni) morphological changes and migration. To reveal the mechanisms behind these phenomena, a unified numerical model utilizing the phase-field (PF) method is integrated with a finite element (FE) multi-physics coupled heterogeneous single-cell model to quantitatively investigate the microstructure evolution of hydrogen electrodes operated in different modes. Based on the 3D microstructures of single-cell components reconstructed using the focused ion beam-scanning electron microscopy (FIB-SEM) technique, the performances of different cells and the corresponding microstructure evolutions caused by Ni coarsening and migration can be simulated under an identical framework in the FC and EC modes, taking into account the complex multi-physics coupling effects. It is shown that, in addition to conventional interfacial energies, the Ni migration driven by the electrochemical potential gradient induced by current also plays an important role in the microstructure evolution. The integrated model is also applied to the simulation of the microstructure evolution of the Ni-YSZ hydrogen electrode infiltrated with GDC nanoparticles to interpret their positive effect on the improvement of the electrode durability.