Electrode kinetics of porous Ni-3YSZ cermet operated in fuel cell and electrolysis modes for solid oxide cell application

The electrochemical reactions of hydrogen oxidation and steam reduction have been investigated for a porous cermet electrode made Ni 3YSZ. characterizations performed over large range gas compositions at 700°C. It has shown that the fuel response is activated by potential under anodic current while limiting density appears cathodic polarization. Moreover, impedance diagrams exhibit shape representative kind finite-length Gerischer element with low-frequency contribution sensitive to content. To interpret these experimental results, continuous dynamic model developed describing mass charge transfers within electrode. reaction divided into sequence elementary steps considering two scenarios transfer based on oxygen spillover mechanisms. Three-dimensional reconstructions obtained synchrotron X-ray nano-holotomography used provide structural properties simulations. numerical computations scenario most appropriate mechanism reproduce correctly experiments. Besides, controlled triple phase boundary lengths, vacancies migration in 3YSZ network pure chemical surface process depending In cell mode, desorption water molecules from would co-limit response, electrolysis adsorption become one rate determining steps. Finally, sensitivity analysis diffusion also play key role response.