Justifying the significance of Knudsen diffusion in solid oxide fuel cells

Developing an appropriate diffusion mechanism to analyze the gas transport in porous electrodes of SOFCs (solid oxide fuel cells), has been a crucial step towards analyzing accurately the cell performance. In this report, the errors in evaluating the gas diffusivity, limiting current density and concentration polarization, are calculated quantitatively by taking bulk diffusion and the previously-overlooked Knudsen diffusion into account. In particular, this work analyzes the deviation between ignoring and considering the Knudsen diffusion of hydrogen transport in SOFC anodes. The study facilitates the rational pre-evaluation of micro- and nanoscale materials prior to assembly into SOFCs. •Analyzes mechanisms of gas diffusion in porous electrodes.•Evaluates uncertainty in performance analysis via previous models.•Justifies Knudsen diffusion for realizing high-performance SOFCs.