Investigation Of Anode And Electrolyte For Intermediate Temperature H₂S Solid Oxide Fuel Cell

In order to overcome the limitations of solid oxide fuel cells (SOFC) in high temperature and resistance to H2S, the paper was focused on electrolyte and anode materials for intermediate temperature H2S SOFC. The properties of these materials were examined by various methods to select proper candidates for SOFC and their electrochemical properties were then tested.Sol-gel method was employed to synthesize Ce0.85Ca0.15-xSrxO2-δ (x=:0.0.03.0.06) and Ce1-xSmxO2-δ (x=0.1,0.2,0.3). The structure and electrical properties of them were characterized by XRD, SEM and ac impedance, respectively. The results showed that doped CeO2had fluorite structure similar to pure ceria. The conductivity of Ce0.55Ca0.12Sr0.03O2-δwas highest. The conductivity of Ce0.9Sm0.1O2-δ was highest when the temperature was below500℃while the conductivity of Ce0.8Sm0.2O2-δ was highest when the temperature was above500℃. Because the conductivity of Ce1-xSmxO2-δ was bigger and the cell test temperature was above500℃, so Ce0.8Sm0.2O2-δ (SDC) was suit for as electrolyte.Sm0.9Sr0.1Cr1-xFexO3-δ (x=0.2.0.5.0.8) was synthesized by sol-gel method. The properties of them were characterized by XRD, SEM and ac impedance, respectively. They all had orthorhombic perovskite-type structure and exhibited good chemical compatibility with Ce0.8Sm0.2O2-δ.Conductivity increased with the increased temperature. At the same temperature, conductivity increased along with more doping Fe while sulfur tolerance reduced with more doping Fe. So Sm0.9Sr0.1Cr0.5Fe0.5O3-δ (SSCF) was fitting as anode for SOFCY0.9Sr0.1Cr1-xFexO3-δ (x=0.1,0.3.0.5) was synthesized by sol-gel method. The stability in reducing atmosphere of them was characterized by XRD, SEM and XPS, respectively. After reduction, only Y0.9Sr0.1Cr0.9Fe0.1O3-δ (YSCF) could capture oxygen to maintain the stability of structure and maintained good chemical stability upon exposure to H2S. Then it was choosen as anode for SOFCElectrochemical performance of single cell was studied with configuration of SSCF-SDC/SDC/Ag and YSCF-SDC/SDC/Ag in20ppm H2S,10%H2, respectively. At600℃. the maximum current density was100.5mA·cm-2and the maximum power density was34.04mW·cm-2for the cell SSCF-SDC/SDC/Ag. while the maximum current density was90mA·cm-2and the maximum power density was14mW·cm-2for the cell YSCF-SDC/SDC/Ag.