Evaluation of the effect of sulfur on the performance of Ni/CGO-based solid oxide fuel cell (SOFC) anodes

Abstract

The focus of this study is the measurement and understanding of the sulfur poisoning phenomena of Ni/gadolinium-doped ceria (CGO) based solid oxide fuel cells (SOFC). Cells with Ni/ CGO10 and NiCu5/CGO40 anodes were characterized by using impedance spectroscopy at different temperatures and H2/H2O fuel ratios. The short-term sulfur poisoning behavior was investigated systematically at temperatures of 800–9508C, current densities of 0–0.75 Acm@2, and H2S concentrations of 1– 20 ppm. A sulfur poisoning mitigation effect was observed at high current loads and temperatures. The poisoning behavior was reversible for short exposure times. It was observed that the sulfur-affected processes exhibited significantly different relaxation times that depend on the Gd content in the CGO phase. Moreover, it was demonstrated that the capacitance of Ni/CGO10 anodes is strongly dependent on the temperature and gas-phase composition, which reflects a changing Ce3+/ Ce4+ ratio.