A comprehensive micro-scale model for transport and reaction in intermediate temperature solid oxide fuel cells

A comprehensive model for detailed description of micro-scale transport and electro-chemical reaction in intermediate temperature SOFCs (solid oxide fuel cells) was developed by combining many relevant theoretical and experimental researches. Dependence of electro-chemical performance of PEN (positive electrode/electrolyte/negative electrode) on micro-structural parameters of electrodes was investigated through numerical simulation. Spatial distribution of transfer current density confirmed that TPBs (three phase boundaries) at electrode/electrolyte interface were most active for electro-chemical reaction and its contribution to overall reaction increased at higher current densities. Spatial gradient of total pressure in cathode was found to facilitate oxygen transport while that in anode hinder hydrogen transport. Among various micro-structural parameters for electrodes, particle diameter was found to be the most important one that governs the PEN performance; smaller particle diameter decreased activation overpotential with larger TPB length, while increasing mass transport resistance and concentration overpotential with smaller pore diameter. The proposed micro-model was found successful in micro-structural characterization of PEN performance, and thus believed to serve as a bridge connecting micro-scale models and macro-scale calculations.