Performance and sulfur poisoning of Ni/CeO₂ impregnated La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ anode in solid oxide fuel cells

Abstract In this study, comparison experiments are conducted based on yttria-stabilized zirconia (YSZ) electrolyte supported single solid oxide fuel cells (SOFCs) with pure La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ (LSCrM) or Ni/CeO₂ impregnated LSCrM anodes. The single cells are tested in dry H₂ and H₂/H₂S (50 ppm) mixture, respectively. Compared with the pure LSCrM anode, the cell with Ni/CeO₂ impregnated LSCrM presents a significant performance improvement when the pure H₂ is fueled to the anode, and shows a good stability during a constant-current discharge testing (398 mA cm^-2). When the fuel is switched to H₂/H₂S mixture, the cell with Ni/CeO₂ impregnated LSCrM anode still shows a remarkable constant-current discharge (120 mA cm^-2) performance compared with pure LSCrM anode. The Ni/CeO₂ impregnation can improve the electrochemical performance of the LSCrM anode without any sacrifice of sulfur tolerance ability. The Ni/CeO₂ impregnated LSCrM might be a potential anode material for solid oxide fuel cell operating in sulfur-containing fuels. The XRD and XPS results demonstrate that the anode poisoning product is composed of adsorbed sulfur, metal sulfides and sulfate radical. The mass spectrum result confirms that the poisoning mechanism involves the reaction of sulfur with anode rather than the direct reaction between H₂S gas and anode.