The effect of applied voltage on the behavior of Ni- gadolinium-doped ceria cathodes in SOECs using 2D comb-shaped patterned cells

Solid oxide electrolysis cells (SOECs), which are used for steam or co-electrolysis of H 2 O and CO 2 , are a promising clean energy technology. For commercialization, it is essential to understand long-term degradation mechanisms. To address the complexity of the porous structure of commercial cells and the associated challenges, this study employs a two-dimensional comb-shaped patterned cell. These patterned electrodes reproduce the cross-sectional geometry of conventional cells while avoiding the complexity of porous microstructures. In this configuration, Ni metal was applied as the cathode, and electrolysis experiments were conducted under various applied voltages. The results indicate that the effect of applied voltage on delamination is nonlinear, as the delamination sites vary with voltage. At −0.22 V, slight delamination occurred at the tips of the Ni stripes; at −0.47 V delamination became more pronounced. At the higher voltage of −0.94 V, the Ni tips adhere more strongly to the substrate and GDC shows a pronounced tendency to diffuse onto the Ni surface, while delamination initiates from the center of the cathode. These results demonstrate that the interaction between Ni and GDC is strongly dependent on the applied voltage, providing insights into optimized operating strategies. • Effect of applied voltage on Ni–GDC electrode under SOEC mode was investigated. • Two-dimensional comb-patterned cells enabled real-time observation of Ni evolution. • Ni stripes delaminated from the GDC layer at low and moderate applied voltages. • Higher voltages enhanced interaction between Ni and GDC, and promoted GDC diffusion onto Ni surface.