J. Scott Cronin

A reduced temperature solid oxide fuel cell with nanostructured anodes

Reduced-temperature solid oxide fuel cells (SOFCs), featuring thin strontium- and magnesium-doped lanthanum gallate (LSGM) electrolytes and nano-scale Ni anodes, showed high power densities of 1.20 W cm−2 at 650 °C and 0.39 W cm−2 at 550 °C when operated on humidified hydrogen fuel and air oxidant.

Fe-substituted SrTiO3−δ–Ce0.9Gd0.1O2 composite anodes for solid oxide fuel cells

A new composite solid oxide fuel cell anode material, SrTi1−xFexO3−δ mixed with Gd-doped ceria, was tested in La0.9Sr0.1Ga0.8Mg0.2O3−δ electrolyte-supported cells with La0.4Ce0.6O2 barrier layers and La0.6Sr0.4Fe0.8Co0.2O3 cathodes. The x = 0.7 composition had an anode polarization resistance of 0.17 Ω cm2, at 800 °C in humidified H2, much lower than the value 0.39 Ω cm2 measured for x = 0.4 and 3.14 Ω cm2 for x = 0. The reduced polarization resistance correlated with increased oxygen non-stoichiometry δ, which suggests that it may be related to increased ionic conductivity. Electrochemical impedance spectroscopy (EIS) measurements at 800 °C on the x = 0.7 anode cell showed a main response centered at ∼1 Hz that increased with decreasing hydrogen partial pressure. The maximum power density observed was for the x = 0.7 cell – 337 mW cm−2 at 800 °C in air and humidified hydrogen – and was limited mainly by the thick electrolyte.

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm res...