Tortuosity in anode-supported proton conductive solid oxide fuel cell found from current flow rates and dusty-gas model

Abstract

Ba(Ce0.8Y0.2)O3−δ anode-supported proton conductive solid oxide fuel cells were fabricated and tested. By changing the H2 partial pressure at the anode side, the effect of anodic concentration polarization on open-circuit voltage of the cell was observed. Saturation current densities under concentration polarization were obtained from different anode thickness cells and were used for tortuosity calculation. The calculation is based on the dusty-gas model which includes Knudsen diffusion and Stefan–Maxwell equation terms. The tortuosity value for our supporting anode is 1.55 ± 0.1 which is in a physically reasonable range for modern porous anode materials. The tortuosity that we found is independent of the cell testing temperature and anode thickness, which is consistent with the fact that tortuosity is a geometric factor of the anode structure. The derived equation also can be used for predicting the effect of varying the anode thickness, porosity and pore size. Also, the concentration of the gases as a function of position across the anode is determined.