Effective Suppression of LSCF Air Electrode Degradation by Air Cleaning

Abstract

The performance degradation of air electrodes in solid oxide cells is strongly affected by impurities such as sulfur dioxide. Filtration is a practical approach for proton-exchange membrane fuel cells with high air purity demands. This study aims to evaluate the applicability of such a filter consisting of specially modified activated carbons for the LSCF air electrode. Different air quality qualities were used to differentiate degradation mechanisms caused by ambient air impurities from the intrinsic aging of a cell. Analyzing the impedance spectra using a distribution of relaxation times (DRT) and a complex nonlinear least squares fit (CNLS) revealed a significant degradation rate in the first 360 hours. Filtering the air reduces the degradation rate significantly. A similar degradation of cell performance occurs in cleaned air as in synthetic air, indicating the ability of the filter material to prolong the lifetime of SOCs through the adsorption of gas impurities.