Degradation of Solid Oxide Fuel Cell Anode in Phosphorus-containing Coal Syngas

Coal is the dominant energy for electric power generation. Solid oxide fuel cells (SOFCs) has been proposed to be incorporated into the coal based power plant. Currently, Nickel-Yttria stabilized Zirconia (YSZ) composite is widely used as the anode in SOFCs (YSZ as electrolyte) due to its low-cost, high electric conductivity, and excellent catalytic activity for many fuel types. However, the long-term stability of the Ni/YSZ anode remains a major concern when a SOFC is operated using coal syngas. Poisoning by the impurity species in the coal syngas poses severe threat on the SOFCs. Of all the impurities present in coal syngas phosphorus (P) is the most detrimental. Therefore, it is vital to evaluate and unveil the underlying mechanism of phosphorus poisoning on the anode.;The present thesis deals with the influence of electric current and moisture concentration on the degradation of Ni/YSZ anode upon exposure to PH 3. Electrochemical testing has been carried out to evaluate the cell performance. In addition, the microstructure, elemental distribution, and chemical composition of the anodes are analyzed using various material characterization methods. Specifically, the behavior of Ni migration at the Ni/YSZ anode is quantitatively investigated. The nickel migration is induced by the electrostatic force due to electric current and by the chemical potential difference of phosphorus. In addition, cell degradation is accelerated by moisture in the PH3-containing fuel